WO1997042613A2 - Moisture detecting devices such as for diapers and diapers having such devices - Google Patents

Abstract

A pair of spaced electrodes (114) within an area subject to wetness couple non-conductively with a sensor (124) protected from wetness, and an alarm sounds in response to moisture decreasing the resistance between the electrodes (114). For example the electrodes (114) project into the absorbent material of a diaper and extend along the inside of the diaper sheath (110) opposite a pouch on the outside of the sheath (110). The pouch contains a sensor (124) capacitively coupled to the electrodes (114).

Description

TITLE

MOISTURE DETECTING DEVICES SUCH AS FOR DIAPERS AND DIAPERS HAVING SUCH DEVICES

FIELD OF THE INVENTION

This invention relates to devices for monitoring wetness, particularly in diapers, and to diapers containing such devices.

BACKGROUND OF THE INVENTION

Various methods and means have been developed for monitoring moisture or wetness in diapers. The purpose of such devices is to set off an alarm when a diaper becomes wet . This permits a mother to tend to a newborn infant or toddler. However such devices have disadvantages in that they may require conductors to pass mechanically through the diaper's plastic outer sheath, may subject the skin of the wearer to direct voltages from a voltage source, may be sensitive only in a limited area, may accidentally respond to the wearer sitting on a wet or metal bench or park slide, or have other drawbacks.

SUMMARY OF THE INVENTION

According to an embodiment of the invention, a pair of spaced electrodes within the area subject to wetness couple non-conductively with a sensor protected from wetness, and an alarm sounds in response to moisture decreasing the resistance between the electrodes. For example the electrodes project into the absorbent material of a diaper and extend along the inside of the diaper sheath opposite a pouch on the outside of the sheath. The pouch contains a sensor capacitively coupled to the electrodes.

The various features of novelty which characterize the invention are pointed out in the claims forming a part of this specification. Objects and advantages of the invention will become evident from the following detailed descriptions of embodiments of the invention when read in light of the following drawings .

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an exploded view of a diaper embodying the invention.

Fig. 2 is a perspective view of Fig. 1.

Fig. 3 is circuit diagram of a sensor used in Figs . 1 and 2.

Figs. 4 and 5 illustrate an embodiment of a pouch in Figs . 1 and 2.

Fig. 6 is a plan view of the rear of an embodiment of a diaper with a pouch on the outside and containing a sensor.

Fig. 7 is an frontal elevation of the rear of the diaper, when opened, in Fig. 6.

Fig. 8 is a plan view of the rear of another embodiment of a diaper with a pouch on the outside and containing a sensor.

Fig. 9 is an frontal elevation of the rear of the diaper, when opened, in Fig. 8.

Fig. 10 is a perspective view of a sensor embodying the invention.

Fig. 11 is a block diagram of another embodiment of the invention.

Fig. 12 is a flow chart which illustrates the steps performed by the processor in Fig. 11.

Fig. 13 is a continuation of the flow chart in Fig. 12.

Fig. 14 is a block diagram of a chip that, according to an embodiment of the invention, serves in place of a circuit in Fig. 3 or the processor of Fig. 11.

Figs. 15A, 15B, and 15C illustrate the waveforms induced on the sensing circuit by the chip after current limiting by an external resistor.

Fig. 16 illustrates the pins of the chip in

Fig. 14.

Fig. 17 illustrates the operation with a piezoelectric element as the only output .

Fig. 18 illustrates the operation with only an LED output .

Fig. 19 illustrates the operation with piezoelectric and LED outputs.

Fig. 20 illustrates the operation with an LED and external DC-powered output circuit.

Fig. 20A illustrates operation with an external DC-powered output circuit only.

Figs. 21A and 21B are exploded perspective views of a diaper conveying two embodiments of the invention.

Figs. 22A, 22B, 22C, and 22D are plan views of surfaces that bear electrode arrangements corresponding to several embodiments of the invention.

Figs. 23A and 23B are plan views of surfaces that bear electrode arrangements corresponding to other embodiments of the invention.

Fig. 24 is an elevation of an electrode arrangement corresponding to an embodiment of the invention.

Fig. 25 is an elevation of an electrode arrangement corresponding to another embodiment of the invention.

Fig. 26 is an elevation of an electrode arrangement corresponding to another embodiment of the invention .

Fig. 27 is a perspective view of an electrode arrangement corresponding to another embodiment of the invention.

Fig. 28 is a perspective view of an electrode arrangement corresponding to another embodiment of the invention.

Fig. 29 is a perspective view of a pocket with aspects embodying the invention.

Fig. 30 is a perspective view of a pocket with a further aspect embodying the invention.

Fig. 31 is a perspective view illustrating the folding of a sensor element to shorten its effective length.

Fig. 32 is a perspective view illustrating an apparatus for the removal of a coating from an area of coated film.

Fig. 33 is a perspective view illustrating an apparatus for the placement of the sensing electrodes onto a diaper backing sheet web.

Fig. 34 is a perspective view illustrating an apparatus for the removal of non-conductive fibers from a wire-wrapped yarn.

Fig. 35 is a sectional view illustrating an example of a module in a pocket on the back of a diaper .

Fig. 36 is a plan view of the frontal area of a diaper having a cloth-like backing sheet and a treated rectangular portion.

Fig. 37 is a sectional view through an area of cloth-like backing sheet containing a treated portion.

Fig. 38 depicts an ultrasonic apparatus for processing of the treated portion of Figs. 16 and 17.

Fig. 39 is a perspective view of a diaper produced by the process of the invention.

Fig. 40 is a schematic representation of a machine for constructing diapers.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the exploded view of Fig. 1 and the partially-exploded perspective of Fig. 2, a disposable diaper 100 embodying the invention includes an inner sheet 104 of a water-permeable film which overlies a wetness absorber layer 107 of powerfully liquid- absorbent padding or other powerfully absorbent material. In one embodiment the layer 107 may include a gel-forming absorbent resin. An outer water- impermeable electrically-insulating plastic sheath 110 supports two conductive spaced-apart electrodes 114, in the form of metallic or other electrically-conductive strips, that extend along the center of the sheath 110 and in electrical contact with the absorber layer 107. According to an embodiment of the invention, the electrodes 114 pass longitudinally through the layer 107. According to another embodiment, the electrodes 114 are in the form of conductive threads or wires.

The sheet 104 is common to most disposable diapers and is often referred to as cover stock. It is composed of thick porous, relatively hydrophobic, bonded fibers which tend to pass liquid in one direction from the wearer to the absorber layer 107. The urine is held away from the skin by the competition between the highly absorbent layer 107 and the not-so- absorbent sheet 104. In this way the relatively hydrophobic fibers space the wet mass of the layer 107 from the skin of the wearer. This keeps the skin dry even when the wearer has wet the diaper. The sheet 104 may be omitted in training diapers that intend to make the wearer uncomfortable when the diaper is wet . The diaper is worn in the usual fashion.

The electrodes 114 terminate in widened pairs of adjacent fixedly spaced electrically-conductive pads 117 on each end. The pairs of pads 117 at each end are printed on the sheath 110 or are bonded to the sheath 110 so they maintain a fixed position on the sheath 110 and so they are in intimate contact with the sheath. According to another embodiment, the pads 117 are otherwise deposited or applied, such as by selective metallization, or carbonization using a laser. Bonded to the outer face of the sheath 110, directly opposite the pads 117 at each end of the sheath, are pouches 120. Each pouch 120 is adapted to receive a removable sensor 124 having thin electrically-conductive rectangular planar members or surfaces 127. Although two pouches 120 exist, only one pouch receives a sensor 124. When two pouches exist, the selection of the pouch which receives the sensor 124 depends upon the preferences, e.g. based on the comfort, of the user.

The position of each pouch 120 is such as to place the pair of planar members 127 on the sheath 110, directly behind a pair of the pads 117 without overlapping one member 127 with two of the opposing adjacent pads 117 or vice versa. One of the pairs of pads or members is larger than the other to permit tolerance in placement .

According to an embodiment, each pouch 120 is composed of or contains, in some portion, resilient material (not shown) to press the members 127 into position against the sheath 110 when the diaper is worn. The members 127 do not electrically contact the pads 117, rather the sheath 110 separates the members from the pads. When a sensor 124 sits in the pouch 120, the pair of members 127 of the sensor 124, and the opposing pair of pads 117 form two adjacent capacitors.

According to an embodiment, the sides of the sensor 124 are tapered to facilitate insertion in the collapsed pouch. The faces of the sensor 124 may also be tapered.

As shown in Fig. 2, suitable fastening strips

130 secure the diaper in operable condition, and the sensor 124 is placed in the pouch 120 at the rear or front of the diaper. When a user wears and wets the diaper, the liquid passes through the sheet 104 into the absorber layer 107 and to the sheath 110. The liquid then electrolytically short-circuits the electrodes 114. Hence the electrodes 114 operate as a conductive switch which is open, i.e. non-conductive, in a dry diaper and closed, i.e. conductive, in a wet diaper.

According to another embodiment of the invention, the diaper contains only one pouch 120. The diaper may further comprise other accessories as may be necessary or desired, such as elastic electrodes for close fit to the wearer, tapes, tabs, snaps or the like for fastening the diaper in place upon the wearer, for example .

The sensor 124 contains an oscillating voltage or pulse source, preferably one having a low duty cycle, which capacitively couples to the members 127 to the pads 117 using the sheath 110 as the dielectric medium, and an alarm device which responds to the source. The spaced electrodes 114 form a switch that remains open (non-conductive) when the diaper is dry. The sensor 124 is set so varying current from the source cannot pass through the open switch formed by the electrodes 114. When the diaper is wet, the electrolytic action of the urine in the diaper contacts the electrodes 114 and closes the switch, i.e. makes it conductive across the gap between the electrodes 114. The sensor 124 is set so varying voltage of the source then passes a current from the sensor 124 through the capacitor formed by one member 127 and the opposing pad 117, through one electrode 114 through the electrolytically conductive gap between electrodes to the other electrode 114, through the capacitor formed by the second of the pair of pads 117 and the second of the pair of members 127, back to the sensor. The resulting current triggers an alarm which, according to one embodiment, energizes a piezoelectric sounder and plays a tune or makes some other sound such as a beep.

According to another embodiment, the alarm takes the form of a blinking or turned on light, such as an LED. According to another embodiment, the alarm is transmitted by radio waves, infra-red radiation, or other means to a remote position where an attendant can monitor a number of children or other wearers.

The alarm, in the form of a sound or light, informs the wearer, who may be an infant being trained, or the infant's parent, that the diaper is becoming wet. This allows prompt action. A sound or light alarm may for example make the infant in training associate its urges with its training needs. The sound or light can also serve to notify an infant's parent that the child's diaper needs changing. A sound or light alarm can inform a toddler's attendant of these needs. A sound alarm can be an aid in enuresis training. A light alarm can also warn an elderly incontinent or handicapped person without sensation in the peritoneal area of an incident, or inform a caregiver of the need for changing.

The sensor 124 sets an alarm threshold sufficiently high to prevent a false alarm when a wearer sits on a metal bench or on a wet surface. The capacitive impedance between the pads 117 and members 127 is far less than that between the electrodes 114, even when the electrodes 114 are in the vicinity of metal or a wet surface. Thus the electrodes 114 present a high impedance unless shorted electro¬ lytically by urine in the diaper. The sensor threshold is sufficiently high to avoid responding to the capacitive coupling between the dry electrodes 114, and yet low enough to respond to the electrolytic conduction between the electrodes 114.

Sensing electrodes 114 are made to have such a small surface area that the amount of capacitive coupling between sensing electrodes 114 and any items placed opposite them in contact with the outer surface of backing sheet 110 will^' be so small that the amount of current shunted to such external items will not be detectable by detector module 124. As a consequence, the alarm will not be activated as the result of conditions external to the diaper 100, but only due to electrolytic conduction between the sensing electrodes 114. An example of an external item that might be placed against the outside of a diaper is a metal chair that a wearer sits on.

Details of electrical portions of one embodiment of sensor 124 appear in Fig. 3 which includes a low duty-cycle pulser 300. In the pulser 300, an oscillator 304 and divider counter 307, forming part of an integrated circuit or chip, provide the time base for all events in the wetness detection process. In one embodiment, the counter 307 yields a low frequency pulse rate such as 30 Hz to a rising-edge sensitive clock input of a D-type flip-flop 310. A higher frequency pulse, some derivative of the same clock, e.g. 60 kHz to result in a 1:2000 duty cycle, furnishes a reset to the flip-flop 310 a brief period later. As a consequence, the flip-flop 310, which has its data input connected to a positive supply 314, clocks in a logic high which is reset 15 microseconds later by the higher frequency clock. The inverting output Q' of the flip-flop 310 is used and a corresponding 15 microsecond logical low pulse is subsequently generated. This low pulse appears at an inverting amplifier 317 which drives an output pin on the chip, and also appears at a rising-edge sensitive clock input of second flip-flop 320. The buffered output pulse from the inverter 317 passes to an external resistor 324.

The external resistor 324 performs a charge current limiting function in the external R/C circuit formed with the diaper's capacitor-switch network 327. The latter includes a first capacitor 330 formed by one of the members 127 and one of the pads 117 facing each other across the sheath 110, the resistance 334 of the switch formed by the electrodes 114 and the gap between them, and a second capacitor 337 formed by the other of the members 127 and the other of the pads 117 facing each other across the sheath 110.

The voltage at the resistor 324 and across the capacitor switch network 327 also appears at a Schmidt input buffer 340 which produces an output at the D input of the flip-flop 320. The flip-flop 320 is set at power-up to avoid a brief alarm. An output Q' of the flip-flop 320 drives an alarm 344. In the example shown in Fig. 3, the alarm 344 includes a beep- producing piezoelectric crystal PZ, an LED, a radio transmitter RT, an infra-red transmitter IR, a music generating circuit MG, and a tactilely-sensible vibrator VB for enuresis training, any of which may be energized selectively, either alone or all together. The piezoelectric crystal PZ may also produce ultrasonic chirps to communicate the alarm to a remote or bedside receiver. According to other embodiments of the invention, the sensor 124 includes any one or more of the crystal, LED, radio transmitter, infra-red transmitter, music generating circuit, or a tactilely- sensible vibrator without the others. The others may be omitted. Other means of alarm may be used. In one embodiment only the piezoelectric PZ and the LED is used.

In each charge cycle a 15 microsecond current-limited pulse feeds into the capacitor-switch network 327. Assuming the network 327 is initially discharged, it begins to acquire a charge, the terminal voltage of which is a function of the charging source voltage, current-limiting resistor 324, the pulse length, and the capacitance of the series-connected capacitors in the sensor network 327. When the diaper is dry the open circuit at the switch 324 between the electrodes 114 allows the charge across the circuit 327 to rise rapidly toward its peak and beyond the threshold of the Schmidt trigger 340. This places a low at the output Q' of the flip-flop 320. This holds the alarm 320 off. The voltage rises rapidly because, in the proximity of the dry layer 107, the total capacitance of circuit 327 is extremely low, much lower than the series capacitance of the capacitors 330 and 337.

When urine electrolytically shorts the electrodes 114, the total capacitance of network 327 rises substantially to approximately the series combination of the value of the far higher capacitance of coupling capacitances 330 or 337. The Schmitt network 327 then appears as a capacitive load equal to approximately the value of the series combination of the fixed coupling capacitances 330 and 337. The voltage across the network 327 then fails to rise above the positive-going threshold of the Schmidt trigger 340. At the termination of the sensing pulse from flip-flop 310 and inverter 317, flip-flop 320 is clocked by the rising Q' output of flip-flop 310 and stores the logic low level- output of Schmitt trigger 340 as a logic high level on its Q' output. This high level on the Q' output of flip-flop 310 activates the alarm 344. At the next pulse, when the flip-flop 310 resets the flip-flop 320, the output at Q' of the flip- flop 320 goes high and triggers the alarm 344.

More specifically, the resistor 324 has a value such that the network 327 charges to at least the threshold (typically 1.6 volts) of a Schmidt input buffer 340, when the diaper is dry. Thus, at the time of charge termination, and the exact moment when the synchronous rising-edge clock is fed to the second flip-flop 320, the instantaneous level of the output of the Schmidt input buffer 340, being a function of its presently imposed input voltage, is clocked into the sampling flip-flop 320. The resulting state of the outputs of flip-flop 320 indicate the wet or dry state of the diaper in that previous instant and the whole cycle recurs at the previously mentioned 30 Hz rate.

When the diaper is dry, the flip-flop 320 produces a 0 at the Q' output. When the diaper is wet, the charge does not reach the level needed to cause the Schmidt input buffer 340 to apply a 1 to the

D input of the flip-flop 320. This produces a 1 at the

Q' output of the flip-flop 320 and activates the alarm 344.

Beside the usual noise-reducing function typical of Schmidt input circuits, this Schmidt input buffer 340 provides an additional effect. As the network charging pulse voltage varies in response the power supply, so too varies the threshold voltage of the Schmidt input buffer 340. This is because the Schmidt threshold points are set by a voltage divider as a fixed, moderate fraction directly from the supply voltage. The effect is the reduction of supply voltage-induced variations in the sensing threshold as the battery voltage supply weakens, as would tend to be the case when batteries are used as the power source.

The low pulse rate at the resistor 324 serves at least two purposes. First, a relatively long zero- voltage cycle helps assure that the voltage at the network 327 returns to zero between pulses under all conditions. Each cycle therefore tends to be isolated from the previous one. The low duty cycle assures the bias of the external capacitive network 327, thereby eliminating the need for resistive bias components were, for instance, a comparator used and were the applied waveform a 50% duty cycle square wave. Second, the average current required by the test circuit is reduced by making the tests less frequent than they might otherwise be, since the majority of test current is drawn during the pulse. Since the required response is in the order of one or more seconds, the average current consumption could theoretically be reduced to a minimum by reducing the duty cycle to the extent that the interval between pulses is made to be on the order of the required response time.

According to an embodiment, for a duty cycle of 1:2000 for the applied pulse, the values of the resistor 324 and the threshold of the Schmidt trigger can be selected so the average power applied to the series resistor, coupling capacitors, and electrodes approximates 3 nanowatts of power.

Figs. 4 and 5 illustrate an embodiment of a pouch. Here, an adhesive holds an outer curved flange 407 of an elastic pouch 410 against the outside of the outer water-impermeable electrically-insulating sheath 110. According to another embodiment of the invention, a thermal bond holds the flange 407 to the sheath 110. When the sensor 124 is inserted into the pouch 410, the pouch shapes itself securely about the sensor.

Fig. 6 is a plan view of the rear of an embodiment of a diaper with a pouch 410 on the outside of the sheath 110 and containing a sensor 124. Fig. 7 is an frontal elevation of the rear of the diaper, when opened, in Fig. 6. Here, the thicknesses are exaggerated for clarity. The sensor 124 in the pouch 410 carries the members 127 and presses them against the outside of the sheath 110 opposite the pads 117 printed on the inside of the sheath. A substrate 600 supports the pads 117. A layer 604 common to existing disposable diapers covers the pads 117 and the sheath 110, and provides a mounting surface for an absorber layer 607 corresponding to the layer 107. The latter is also common to most disposable diapers. Covering the absorber layer 607 is a relatively hydrophobic inner sheet 610, also common to disposable diapers, and corresponding to the sheet 104. The relatively hydrophobic fibers space the wet mass of the layer 607 from the skin of the wearer and do not conduct moisture back to the skin. This keeps the skin dry even when the wearer has wet the diaper. The urine is held away from the skin by the competition between the highly absorbent layer 607 and the not-so-absorbent sheet 610.

Fig. 8 is a plan view of the rear of another diaper similar to the diaper in Figs. 6 and 7, but using bare wires or conductive threads 614 as the electrodes 114. Fig. 9 is an frontal elevation of the rear of the diaper, when opened, in Fig. 8. Here also, the thicknesses are exaggerated for clarity. The bare wires or conductive threads electrically connect to the pads 117 as they are squeezed between the pads and the sheath 110. According to another embodiment, the wires or conductive threads 614 pass through the absorber layer 607.

In the embodiments of Figs 6 to 9, as in other embodiments, when the diaper is dry the sensor 124 produces no alarm. The spaced electrodes 114 form the electrically conductive switch that remains open when the diaper is dry. Varying current from the source can then not pass through the open switch formed by the electrodes 114. When the diaper is wet, the electrolytic action of the urine in the diaper contacts the electrodes 114 and closes the switch, i.e. across the gap between the electrodes 114. The varying voltage of the source then passes a current from the sensor 124 through the capacitor formed by one member 127 and the opposing pad 117, through one electrode 114 through the electrolytically conductive gap between electrodes to the other electrode 114, through the capacitor formed by the second of the pair of pads 117 and the second of the pair of members 127, back to the sensor. The resulting current energizes the alarm which, according to one embodiment, energizes a piezoelectric sounder and plays a tune or makes some other sound such as a beep.

According to another embodiment of the invention, the sheets 104 and 610 are omitted to give the wearer a sensation of wetness and reinforce the alarm.

According to another embodiment, the wires or threads 614 are buried in the absorber layer 607 and fixedly contact a pair of thin plates within the layer 607. The sensor 124 with the members 127 is then insulated and also buried in the absorber layer. According to another embodiment, the arrangement is the same as in Figs. 1 to 9, but rather than using pouches, the sensor 124 with members 127 is fastened to the sheath 110 by mechanical clips, snaps, or quarter turn locking units on the outside of the diaper.

Fig. 10 is perspective view of an embodiment of a sensor 1000 corresponding to the sensor 124. This includes a housing 1004, an extractor tab 1007, slightly-downwardly tapered sides 1010 and beveled edges 1014. The tapered sides permit alignment on insertion into a pouch. An optional spring loaded switch 1017 is turned on when the sensor 1000 is place in a pouch. The dimensions of the sensor 1000 are such as to fit securely in a pouch. The housing has a rear face 1020 which is curved to furnish a contact force against the sheath 110 and the pouch when place in a pouch.

According to other embodiments, the pads 117 use very thin layers of metals selected for reflectivity as well as oxidation and corrosion resistance. Sputtered or vaporized aluminum covered with nickel avoids oxidation and presents an aesthetically pleasing white appearance outside the diaper.

According to other embodiments, the sensor arrangement is used to inflate a life vest when the vest touches water, in bird feeder water supplies to indicate dry conditions, security doorknobs which respond to skin moisture, liquid level sensors, plant soil moisture indicators, etc.

The invention permits a mother to tend to a newborn infant or toddler, to alert a child during toilet training that it is wetting, to help in enuresis training, and to forewarn the incontinent elderly of a problem before it arises. The invention avoids connecting the source mechanically to the conductors in the diaper from the outside. It also frees the skin of the person wearing the arrangement from direct contact with the voltages that the source applies to the electrodes. Moreover, it avoids a false alarm when the wearer sits on a wet or metal bench, leans on a wet or metal wall, or descends on a metal or wet park slide. According to other embodiments of the invention, the non-conductive coupling from the sensor to the electrodes is optical rather than capacitive. This involves using an LED and light detector combination on opposite sides of the sheath 110.

According to another embodiment, the non-conductive coupling from the sensor to the electrodes is magnetic. This involves applying an electromagnetic field from the sensor in the pouch and then having the field sensed inside the diaper. ■ According to another embodiment, the non-conductive coupling from the sensor to the electrodes is inductive from the sensor to the electrodes .

According to another embodiment of the invention, the speed of the response of the switch formed by the electrodes 114 is varied by changing the relative hydrophobic and hydrophilic correlations of the layers 104 and 107.

The sizes of the members 127 and the pads 117 are sufficiently large, and the face to face spacing between each pad 117 and the opposing member 127 across the dielectric sheath 110 is sufficiently small, so that the capacitances 330 and 337 formed thereby are substantially greater than the very small, almost unmeasurable, stray capacitance between the side-by- side electrodes 114. The Schmidt trigger 340 is set at a low enough value, and the capacitances 330 and 337 are sufficiently high, so that even when a child sits on a wet or metal surface, the stray capacitance across the switch 334 formed by the electrodes 114 does not add enough capacitance to the series circuit 327 to drop the input to the Schmidt trigger below its positive-going threshold. Hence, the flip-flop 320 will not set off a false alarm in response to the wearer sitting on a wet or metal surface. The dimensions ar set to set off the alarm only in response to conduction across the switch 334 formed by the electrodes 114.

Fig. 11 is a block diagram of another embodiment of the invention wherein a processor 1400 performs the functions of the circuit 300 and members 340 and 320 in Fig. 3. The structure of the system is otherwise the same as shown in Fig. 3.

Fig. 12 illustrates the steps performed by the processor 1400. Here, in step 1504, the processor 1400 powers up in response to the detector module 20 being turned on, for example, when it is placed in the pouch of a diaper for the first time (i.e., by a latching switch activated by one of levers 37A or 37B) .

In step 1507, the system is reset after a predetermined elapse of time. In step 1510, the processor 1400 detects the hard wire condition to determine which of the devices in alarm 344 are connected for the purpose of creating the alarm. In step 1514, the processor 1400 determines whether the system is set for an alarm to occur immediately upon sensing or whether a short delay should occur. In step 1514, the processor 1400 may also determine whether the number of operations (alarm conditions) should be counted, said counting to occur only after the aforementioned short delay has expired.

In step 1517, the processor 1400 generates pulses on a continuous basis. As shown in figure 3, these test pulses are applied to network 327 via resistor 324. In "threshold reached?" decision step 1520, the processor 1400 determines whether the voltage has reached a predetermined value, typically a moderate fraction of the supply voltage, such as 40%.

If the result is YES, this means that a conductive condition is not present at switch 334, and the sequence of steps that could lead to activation of the alarm is not begun. Instead, upon each such determination, in the "final alarm counted" decision step 1528, the processor checks whether the alarm counter had flagged a final alarm during the previous alarm event. If the alarm counter was not enabled in configuration step 1514, then the result of this decision will always be NO. If it is YES, step 1530 disables the outputs so that the unit will no longer function. If NO, step 1532 initializes the delay timer (it does not matter whether or not the delay timer is actually flagged for use in qualifying alarm conditions) . Next, the "alarm in progress?" decision step 1535 checks whether there is an alarm condition present. If YES, step 1538 deactivates whatever signals had been active, and the processor returns to the "threshold reached?" decision step 520. If NO, step 1538 is skipped, and the processor returns directly to the "threshold reached?" decision step 1520.

If the result of the "threshold reached?" decision step 1520 is NO, this means that a conductive condition is present at switch 334, and the sequence of steps that could lead to activation of the alarm is begun. Upon each such determination, the "delay feature engaged?" decision step 1522 checks whether the delay feature has been flagged as being engaged. If YES, the "delay underway?" decision step 1524 checks whether a delay is currently underway. If YES, the unit will pulse the LED output pin at 8 Hz and return to the decision step 1524, where it will continue to check for the end of the delay period, rather than proceed with an alarm condition. If an LED is connected, a user of the product can see that a qualified alarm may be imminent, which helps prevent inadvertent activation of the alarm counter due to some form of mis-handling of the unit. Once the delay period is over, the result of the "delay underway?" decision step 1524 will become NO, as long as the result of the "threshold reached?" decision step 1520 persists in the NO condition, and this is what results in a positive alarm condition.

Fig. 13 is a continuation of the flow chart in Fig. 12, showing the steps that may occur upon the occurrence of a positive alarm condition. First, in step 1604, the alarm counter is incremented by a count of one, if it was enabled in the configuration step 1514. Next, in step 1521, the alarm condition is latched (i.e., by use of a persistent flag) . Then, in the "last alarm?" decision step 1607, the processor checks whether this is the last alarm. If the alarm counter was not enabled, this decision will always be NO. If it is YES, the processor pulses the LED pin at 8 Hz, contrary to the usual 2 Hz rate, to indicate that the unit will not function after this alarm. Next, the "piezo?" decision step 1618 checks whether configuration step 1510 flagged that a piezo is connected. If YES, then the processor will feed the non-LED output pin with a signal that will cause an audio piezo transducer to produce a steady monotone . This tone is different from the usual warbling tone to indicate that the unit will not function after this alarm. If NO, then the processor will supply DC power the non-LED output pin for the purpose of driving any of a number of possible output devices.

If the result of the " last alarm?" decision step 1607 is NO, the processor pulses the LED pin at 2 Hz. that the unit will not function after this alarm. Next, the "piezo?" decision step 1619 checks whether configuration step 1510 flagged that a piezo is connected. If YES, then the processor will feed the non-LED output pin with a signal that will cause an audio piezo transducer to produce a warbling tone. If NO, then the processor will supply DC power the non-LED output pin for the purpose of driving any of a number of possible output devices.

It will be evident that certain details of the internal logic of processor 1400 are different from circuit 300, most obviously the latching of the alarm condition. This was done to facilitate implementation in software/firmware. The essential functions, however, remain common to the two.

With reference to the use of the alarm counter in any implementation, in the usual commercial context, it is expected that a detector module 20 has sufficient battery power to operate with one pack of diapers. Any attempt to use the device with a second pack of diapers would likely result in a failure of operation at some time during use with one of those diapers due to the dead or dying battery. Accordingly, the processor 1400 and the circuit 1700 count the number of operations and continue in operation only for the number of diapers in a single package. The number of possible alarms may be increased slightly over the package count to allow for the possibility of inadvertent alarms caused by mis-handling (such as re¬ insertion into an already wet diaper) . This assures continued operation without failure in the middle of a pack.

Fig. 14 is a block diagram of a chip 1700 that, according to an embodiment of the invention, serves in place of the circuit 300, Schmitt trigger 340, and flip-flop 320 of Fig. 3, or in place of the circuit 300 of Fig. 3 or in place of the processor 1400 of Fig. 11. The chip 1700 senses the state of the switch 334 in the network 327. Specifically it senses whether a conductive condition is present at switch 334 in the network 327, indicating the presence of a conductive electrolyte across the sensing electrodes, as evidenced by the effect of the load presented by the series combination of substantially fixed-value capacitors 330 and 337 on the voltage at the connection to network 327 as of the end of the sensing pulse. The basic concept used is to generate short, current- limited, periodic, electrical test pulses to network 327. If network 327 is connected by the closure of switch 334, then network 327 serves to load down the test pulse, but if switch 334 is open, the pulse will be for practical purposes unaffected. The circuit checks the voltage at the connection to network 327 at the end of each pulse, and can detect the state of switch 334 by comparing this voltage to a predetermined threshold.

Fig. 15A illustrates the test pulse applied to the network 327, and Figs. 15B and 15C illustrate the waveforms induced on the network 327 by the test pulses after current limiting by an external resistor using typical values. There is a schematic insert indicating the nodes on an equivalent circuit for which the voltages are plotted. V(l) , the test pulse, is shown in Fig. 15A. V(2) , the voltage across network 327 for the case of a dry diaper, is shown in Fig. 15B. V(2) is also shown in Fig. 15C, this time for the case of a wet diaper. The sensing threshold is shown in Figs. 15B and 15C as a level at approximately 0.8V. The distortion seen in the waveform in Fig. 15B for the case of a dry diaper is caused by the deliberate inclusion of relatively large strays in the simulation model to demonstrate immunity to such strays.

Fig. 16 illustrates the pins of the chip 1700. It shows the external circuit connections to the CT chip. The connection (pin) characters shown in Fig. 16 correspond to those in Fig. 14.

The chip 1700 structure offers several different module configurations to satisfy the needs of different users. The primary module implementations appear in Figs. 17, 18, 19, 20, and 20A.

Fig. 17 illustrates the operation with a piezoelectric element as the only output. Here, the piezoelectric element PE is connected between the "B" and "C" pins and the "A" pin is left unconnected. The sensing circuitry is the same in all of the configuration illustrations. The supply voltage applied across the "+" and "-" pins is shown as a battery B. The "D" pin input is shown, to be optionally connected to either the "+" pin or to the "-" pin. This provides two versions for each configuration; the delay and count operation may or may not be enabled in each of the five configurations of Figs. 17 to 20 and 20A.

Fig. 18 illustrates the operation with an LED as the only output. The LED is driven from the "B" pin. The "C" pin is connected to the "- " pin to prevent spurious piezoelectric element detection and the "A" pin is left unconnected.

Fig. 19 illustrates the operation with piezoelectric and LED outputs. Here, the LED is driven from the "A" pin and the piezoelectric element PE is driven from the "B" and "C" pins.

Fig. 20 illustrates the operation with an LED and external DC-powered output circuit. Here, the LED is driven from the "B" pin. In this configuration the "C" pin is connected to the "-" pin to prevent spurious piezoelectric element detection and the "A" pin is used to provide a constant DC voltage output to provide, or cause to be provided, a supply voltage for the external output circuit . According to an embodiment of the invention, the external output circuit is a device which plays a melody or sound effect, drives a motor or vibrator, activates a relay, generates a radio signal or infrared signal to a remote receiver, etc.

Fig. 20A illustrates operation with an external DC-powered output circuit only. Here, the "B" pin is left unconnected in this configuration and that as in the previous configuration, the "C" pin is connected to the " - " pin to prevent spurious piezoelectric element detection and output of the "A" pin furnishes a constant DC voltage output to provide, or cause to be provided, a supply voltage for the external output circuit. According to an embodiment of the invention, the external output circuit is a device which plays a melody or sound effect, drives a motor or vibrator, activates a relay, generates a radio signal or infrared signal to a remote receiver, etc.

A pin designated "+" is connected to the positive supply voltage. A pin designated "-" is connected to the negative supply voltage (or ground) . According to an embodiment of the invention, the difference between the positive and negative supply voltage is greater than 2 volts and less than 6 volts (DC) . Another embodiment provides for higher supply voltage differences and yet another embodiment provides for lower supply voltage differences.

In normal operating mode, an "R" pin provides the sensing pulses to the external network 327. In a Testl mode, this pin provides access to the most significant output bit of a primary 15-bit counter to verify operation of the ripple count function. In a

TEST2 mode, this pin provides a 32 kHz pulse train with approximately a 50% duty cycle.

In normal operating mode and in TEST2 mode, an "S" pin is the sense input from the external network 327. In TEST1 mode, this pin provides access to the oscillator tank circuit. In normal operating mode, a "D" pin is tied either to the pin "+" or the pin "-" prior to the application of power to the chip. If this pin is connected to the pin "-" when power is applied, all detected alarm conditions are indicated by signaling on the "A", "B", and/or "C" pins immediately following the end of each sense pulse and the operation counter function is inhibited. If this pin is connected to the pin "+" when power is applied, then a 4 second qualification timeout is observed prior to alarm signaling on the outputs. If the alarm condition does not persist throughout this qualification period, the pending alarm is canceled. If the alarm condition does persist throughout this period, alarm signaling appears at the outputs when the qualification period expires and the operation counter is incremented. If a falling edge is provided to this input while in normal operating mode, the chip enters the TEST1 mode, the primary 15-bit counter is set to all ones, and the clock input to the primary counter is disabled. A second falling edge arms the primary counter to be clocked by the next rising edge on this input. The next rising edge causes the primary counter to "roll-over" from all ones to all zeroes. The next falling edge causes a reset to be delivered to the circuitry. The fourth falling edge removes the reset and enables subsequent rising edges on this pin D to clock the primary counter directly. Additionally, the fourth falling edge causes exit of the TEST1 mode and entry of the TEST2 mode.

In normal operating mode, an "A" pin provides either a light emitting diode (LED) drive signal or a high level DC voltage (near supply voltage at the pin "+" dependent on loading) when an alarm condition is sensed. If there is no alarm condition, pin A is in a high-impedance state. In the TEST1 mode, this pin provides access to the output of the on-chip oscillator (64 kHz +/- 30%) . In the TEST2 mode, pin A resumes its normal function.

In normal operating mode, a "B" pin immediately after the application of power, provides the piezo sensing pulse. After the piezo sensing function is completed, this pin provides either a piezo drive signal or an LED drive signal when an alarm condition is sensed. If there is no alarm condition, this pin is in a high-impedance state. Neither the TEST1 mode nor TEST2 mode has any direct effect on the function of pin B.

In normal operating mode, a "C" pin serves immediately after the application of power, to route the piezo element sensing signal to internal circuitry. After the piezo sensing function is completed, this pin provides a piezo drive signal when an alarm condition is sensed (only if the presence of a piezo element was sensed between the " C" pin and the "B" pin) . If direct piezo drive is not to be used for a given circuit arrangement, this pin should be tied to the " -" pin which will assure that no piezo element is sensed.

Making this connection will also guarantee that the "C" pin is permanently left in the high impedance state.

In Fig. 14, an analog section 1704 of the chip 1700 provides all the bias and reference voltages necessary for operation of the oscillator, power-on- reset circuit and the Schmitt trigger functions as well as those functions themselves. Shortly after power is applied between the "+" and "-" pins, the oscillator function starts and the POR (power-on-reset) and OSC signals are fed to a built-in test circuit block 1707. Additionally, the analog section 1704 contains the

Schmitt trigger circuit which is used to convert the analog signal present at the connection to the network 327 to discrete digital logic levels for sensing by the sensor signal detector. An OSC signal comes from the micropower oscillator and has a nominal frequency of 64 kHz. A POR signal is a short pulse produced by a monostable multivibrator.

A "D" Pin Capture flip-flop 1710 is clocked by the POR signal shortly after power is applied and is used to capture the power-up state of the "D" pin. The output of this block is a signal called DELON. If DELON is high following the POR pulse, then alarm qualification counter 1714 and operation counter 1717 are enabled for subsequent alarm detection processing and the LED blink rate is switched to 8 Hz during the alarm qualification timeout period. If DELON is low following the POR pulse, then the alarm qualification counter 1714 and operation counter 1717 functions are inhibited for subsequent alarm detection processing and the LED blink rate is always 2 Hz when an alarm condition is detected.

The built-in test circuit block 1707 controls a primary 15-bit counter 1720 with set, reset, and clock signal outputs based on activity on the "D" pin subsequent to the end of the POR pulse. The TST1 output from this block 1707 controls the signaling on the "A" pin while in the TEST1 mode. It also controls the frequency and duty cycle of the signal output on the "R" pin. The TST2 signal is used strictly to control the test frequency multiplexer and, once asserted by the fourth falling edge on the "D" pin as described above, remains asserted until a full power off/on cycle is detected.

The primary 15-bit counter 1720 provides all of the key timing signals for chip operation. It is a 15-bit binary ripple counter which is normally clocked at the nominal oscillator frequency of 64 kHz. In the TEST1 mode, it can be manipulated by various transitions on the "D" pin (see "D" pin description above) . In the TEST2 mode, it is clocked by the signal present on the "D" pin.

A test frequency multiplexer 1724 is a 9-wide

2-to-l multiplexer. Eighteen inputs are fed by various outputs of the primary counter 1720. Nine outputs are timing signals used for sense signal generation and detection, LED blink rate, piezo detection, piezo tone generation, and alarm qualification counter timeouts. This block is controlled by the TST2 signal which is generally used to increase the various frequencies for manufacturing test purposes (to decrease test times) .

A sensor signal generator 1727 receives timing from the primary counter 1720 via the test frequency multiplexer 1724 (32 Hz and 32 kHz) and an enable signal from a piezo presence sensor block 1730. When the piezo presence sensing function is completed, the piezo presence sensor block 1730 produces the GOSENSOR signal. This signal enables the signal generator 1727 to produce a sensing signal whose frequency is nominally 32 Hz (64,000 divided by 2¹⁰) and whose duty cycle is 0.05%. The SENSE_OUT output of this block is the signal on the "R" pin. The SAMPLE output of this block is used to provide a synchronous sampling clock to a sensor signal detector 1734.

The sensor signal detector 1734 is reset at power-up time. Once the sensing function is enabled (by assertion of the GOSENSOR signal) , the connection to network 327 is fed to the Schmitt trigger in the analog section (to convert the analog voltage present there to a discrete digital level) and the converted digital level is sensed by this block when the SAMPLE signal is asserted by the sensor signal generator. The SAMPLE signal is asserted simultaneously with the end of the sensing pulse.

The chip 1700 provides a non-alarm condition feature. If the signal present at the connection to the circuit 1727 was above the upper (supply-voltage- tracking) threshold of the Schmitt trigger circuit, then the ALARM output signal of this block is not asserted and the ALARM_RESET output signal is asserted. The ALARM_RESET signal inhibits the alarm qualification counter 1714 from counting which, in turn, prevents any clocking signals from reaching the operation counter 1717.

The chip 1700 provides alarm condition with delay and count feature. If the signal present at the connection to the network 327 was below the upper (supply-voltage-tracking) threshold of the Schmitt trigger circuit, then the ALARM output signal of sensor signal detector block 1734 is asserted and the ALARM_RESET signal is not asserted. If the DELON signal is high ("D" pin high when power was applied) , then the alarm qualification counter circuit 1714 is enabled to begin the qualification delay and the LED blinker circuit sets the LEDALARM signal high and generates an 8 Hz signal on LEDFLASH. When the qualification timeout has ended, the signals QUALIFIED and QUALMUX are asserted. The QUALIFIED signal is used to increment the operation counter 1717 and change the LEDFLASH signal from 8 Hz to 2 Hz (except for last operation) . The QUALMUX signal is used to satisfy several logic equations relating to the usage of the outputs dependent largely on whether a piezo was detected between pins "B" and "C" following the application of power.

The chip provides an alarm condition without delay and count feature. If the signal present at the connection to the network 327 was below the upper (supply-voltage-tracking) threshold of the Schmitt trigger circuit, then the ALARM output signal of block 1734 is asserted and the ALARM_RESET signal is not asserted. If the DELON signal is low ("D" pin low when power applied) then the alarm qualification counter 1714 remains disabled and the LED blinker circuit sets the LEDALARM signal high and generates a 2 Hz signal on LEDFLASH. The QUALIFIED signal is never asserted so the operation counter never increments. The QUALMUX signal is used to satisfy several logic equations relating to the usage of the outputs dependent largely on whether a piezo was detected between pins "B" and "C" following the application of power.

The chip 1700 provides an end-of-alarm condition feature. As soon as the voltage present at the connection to the network 327 is found to have returned above the upper (supply-voltage-tracking) threshold of the Schmitt trigger circuit, then the ALARM output signal of the block 1734 is de-asserted and the ALARM_RESET signal is asserted. All alarm activity stops and the outputs return to a high impedance state.

An LED blinker circuit 1737 has several inputs. The ALARM signal activates the basic function. The DELON, QUALIFIED, and LASTOP signals control the output frequency of a LEDFLASH signal. The frequency and pulse-width control timing signals which define the shape of the LEDFLASH signal are provided from the primary counter via the test frequency multiplexer

(ALL_TIMING) . An LEDALARM signal is asserted (primary operand in logic equation to generate LEDFLASH) whenever an alarm condition exists and either: (a) the delay and count feature is enabled and the operation counter has not reached its terminal count, or, (b) the delay and count feature is disabled.

A piezo tone generator 1740 also has several inputs. The basic tone references (2 kHz, 4 kHz, and the 2 Hz warble control) are provided by the primary counter via the test frequency multiplexer. The actual signal (ALTONE) to be generated from these basic inputs is controlled by the LASTOP signal from the operation counter. The time during an alarm condition at which the ALTONE signal is allowed to drive the outputs is controlled by the QUALMUX output from the alarm qualification counter. The generator 1740 produces a warbling tone when an alarm condition occurs and either: (a) the delay and count feature is disabled, or, (b) the delay and count feature is enabled and the current operation cycle is not the last operation. Under either of these conditions, the ALTONE signal is a fairly symmetrical square wave which is modulated between 2 kHz and 4 kHz at 2 Hz.

The generator 1740 also produces a Last Tone signal when an alarm condition occurs and the delay and count feature is enabled and the operation counter has reached its terminal count . The ALTONE signal is a fairly symmetrical square wave at a constant frequency of 4 kHz.

The piezo presence sensor 1730 is enabled immediately after power is applied to the chip. The activation signal is provided by the primary counter via the test frequency multiplexer. When this signal is asserted, the PZSENSE output of this block produces a single high-going pulse which causes the "B" pin control circuits to transfer this pulse to the "B" pin itself. During this pulse interval, the "C" pin output is disabled. If a piezoelectric buzzer is connected between pins "B" and "C" at this time, the pulse is capacitively coupled from the "B" pin to the "C" pin since a piezoelectric buzzer is electrically equivalent to a small capacitor. The presence or absence of this pulse (PZOIN) is then sampled by the block 1730. If the piezo was present, then the PIEZO signal is asserted. Otherwise, the PIEZO signal is not asserted. In either case, when the sampling is completed the GOSENSOR signal is asserted which, in turn, enables the sensor signal generator to begin transmitting the SENSE_OUT pulses and generating the SAMPLE signal to the sensor signal detector. It should be noted that devices other than piezoelectric buzzers may be used to form a connection between the "B" and "C" pins as long as the impedance is suitably low, say, below 1 million ohms.

The alarm qualification counter 1714 provides the delay portion of the delay and count function. Its purpose is to impose a four second delay between the detection of an alarm condition and the generation of alarm-related output pin signals. This functional block is activated when an alarm condition exists and the DELON signal is asserted. When the timeout has expired and the operation counter has not yet reached terminal count, the QUALIFIED signal is asserted. This signal is used to increment the operation counter 1717 by one count (1 count = 1 operation) and to change the LEDFLASH output of the LED blinker circuit 1737. When this function is enabled LEDFLASH starts generating an 8 Hz signal as soon as an alarm condition is detected. Once the alarm qualification timeout expires, LEDFLASH changes its frequency from 4 Hz to 2 Hz as a result of the assertion of the QUALIFIED signal. The assertion of the QUALIFIED signal also causes the QUALMUX signal to be asserted. The QUALMUX signal is used to satisfy several logic equations relating to the usage of the outputs, dependent largely on whether a piezo was detected between pins "B" and "C" following the application of power.

The operation counter 1717 counts the total number of alarms which persist beyond the four-second qualification timeout period. The purpose of this counter is related to diaper wetness sensing inasmuch as the number of diapers in a package varies both from product to product as well as from manufacturer to manufacturer. Since for this application the product utilizing the chip is invariably battery operated and since the battery size for these products is selected to provide optimum energy capacity for the size of the package of diapers with which the product is shipped, this functional block is used to inhibit the chip from operating once the expected end of useful life of the battery energy source is approached. The actual battery life is difficult to predict since the power consumption of the chip and related circuitry fluctuates wildly (maybe more than 1000:1) between the dormant (non-alarm) and active (alarm) states.

Variability in the duration of the alarm condition adds further uncertainty to the prediction.

A block identified as "A" Pin Control Circuit 1744 determines the manner of signaling present on the "A" pin during alarm conditions and while in the different test modes. The active output signal level is a high voltage level. In TEST1 Mode, the on-chip oscillator signal appears on the "A" pin.

In TEST2 Mode, the "A" pin produces signals equivalent to the signals described below, except that the sensor signal generator duty cycle in this mode is about 50%.

When the "A" pin signals in the normal operating mode, the "A" pin signaling has five different formats which depend on: (a) whether or not the delay and count function is enabled or, (b) if the delay and count function is enabled (regardless of whether or not the current operation is the last operation) or, (c) whether or not a piezoelectric buzzer (or other suitable electrical connection) is detected by the piezo presence sensor.

If the delay and count function is enabled and a piezo was sensed and the operation counter has not yet reached terminal count, the "A" pin produces an 8 Hz signal with a 31.25 ms active pulse width during the first four seconds after the alarm condition is detected. Once the four second delay expires, the "A" pin signaling changes to a 2 Hz signal with a 31.25 ms active pulse width. The low (about 6%) duty cycle is used to reduce power consumption.

If the delay and count function is enabled and a piezo was sensed and the operation counter has reached terminal count, the "A" pin produces another signal, for example, an 8 Hz signal with a 31.25 ms active pulse width during the entire alarm condition. If the delay and count function is enabled and a piezo was not sensed, the "A" pin produces a high impedance state during the first four seconds after the alarm condition is detected. Once the four second delay expires, the "A" pin produces another signal, for example, a high voltage level approximating the voltage on the "+" pin for light loads. If the delay and count function is not enabled and a piezo was sensed, the "A" pin produces another signal, for example, a 2 Hz signal with a 31.25 ms active pulse width during the entire alarm condition. If the delay and count function is not enabled and a piezo was sensed, the "A" pin produces another signal, for example, a high voltage level approximating the voltage on the "+" pin for light loads.

A block 1747 identified as "B" Pin Control Circuits determines the manner of signaling present on the "B" pin during alarm conditions and while in the different test modes. The active output voltage level is a high level .

The B pin control circuits 1747 are involved in piezo presence sensing. The block 1747 causes the "B" pin, shortly after power is applied to the chip, to sense the presence or absence of a connection between the "B" pin and the "C" pin. This involves generation of a single pulse of approximately 32 ms within approximately the first 100 ms of chip operation.

In the TEST1 Mode, the block 1747 produces signals on the "B" pin largely equivalent to the signaling cases described below except the sensor signal generator duty cycle in this mode is about 50% In the TEST2 Mode the block 1747 applies signals on the "B" pin largely equivalent to the signaling cases described below except that the sensor signal generator duty cycle in this mode is about 50%.

In the normal operating mode the block 1747 applies signals on the "B" pin with six different formats which depend on: (a) whether or not the delay and count function is enabled or, (b) if the delay and count function is enabled (regardless of whether or not the current operation is the last operation) or, (c) whether or not a piezoelectric buzzer (or other suitable electrical connection) is detected by the piezo presence sensor.

If the delay and count function is enabled and a piezo was not sensed and the operation counter has not yet reached terminal count, block 1747 constrains the "B" pin to produce an 8 Hz signal with a 31.25 ms active pulse width during the first four seconds after the alarm condition is detected. Once the four second delay expires, the block 1747 causes the "B" pin signaling to change to another signal, for example, a 2 Hz signal with a 31.25 ms active pulse width. If the delay and count function is enabled and a piezo was not sensed and the operation counter has reached terminal count, the block 1747 causes the "B" pin to produce another signal, for example, an 8 Hz signal with a 31.25 ms active pulse width, during the entire alarm condition. If the delay and count function is not enabled and a piezo was not sensed, the block 1747 causes the "B" pin to produce another signal, for example, a 2 Hz signal with a 31.25 ms active pulse width, during the entire alarm condition.

If the delay and count function is enabled and a piezo was sensed and the operation counter has not yet reached terminal count, the block 1747 causes the "B" pin to exhibit a high impedance state during the first four seconds after the alarm condition is detected. Once the four second delay expires, the block 1747 causes the "B" pin to produce a "warbling" signal which switches back and forth from 2 kHz to 4 kHz at a 2 Hz rate .

If the delay and count function is enabled and a piezo was sensed and the operation counter is at its terminal count, the block 1747 causes the "B" pin to produce a constant 4 kHz signal with an approximately square shape for the entire duration of the alarm condition. If the delay and count function is not enabled and a piezo was sensed, the block 1747 causes the "B" pin to produce a "warbling" signal which switches back and forth from 2 kHz to 4 kHz at a 2 Hz rate.

A block 1750 designated as "C" Pin Control Circuits determines the manner of signaling present on the "C" pin during alarm conditions and while in the different test modes.

The block 1750 is involved in piezo presence sensing. As described, the block 1750 causes the "C" pin, shortly after power is applied to the chip, to sense the presence or absence of a connection between the "B" pin and the "C" pin. During this interval, the "C" pin serves as an input. In an embodiment of the invention, to prevent a piezo from being sensed, this pin is grounded during this interval.

In TEST1 Mode, the block 1750 causes the "C" pin to produce signals largely equivalent to the signaling cases described below except that the sensor signal generator duty cycle in this mode is about 50%.

In TEST2 Mode, the block 1750 causes the "C" pin to produce signals largely equivalent to the signaling cases described below except that the sensor signal generator duty cycle in this mode is about 50%.

In the normal operating mode, the block 1750 causes the "C" pin to produce three different signalling formats that depend on: (a) whether or not the delay and count function is enabled or, (b) if the delay and count function is enabled (regardless of whether or not the current operation is the last operation) or, (c) whether or not a piezoelectric buzzer (or other suitable electrical connection) is detected by the piezo presence sensor.

If the delay and count function is enabled and a piezo was sensed and the operation counter has not yet reached terminal count, the block 1750 causes the "C" pin to exhibit a high impedance state during the first four seconds after the alarm condition is detected. Once the four second delay expires, the block 1750 causes the "C" pin to produce another signal, for example, a "warbling" signal which switches back and forth from 2 kHz to 4 kHz at a 2 Hz rate. If the delay and count function is enabled and a piezo is sensed and the operation counter is at its terminal count, the block 1750 causes the "C" pin to produce another signal, for example, a high impedance state for the first 4 seconds of the alarm condition followed by a constant 4 kHz signal with an approximately square shape, for the remainder of the alarm condition. If the delay and count function is not enabled and a piezo was sensed, the block 1750 causes the "C" pin to produce a "warbling" signal that switches back and forth from 2 kHz to 4 kHz at a 2 Hz rate.

Figs. 21A to 40 illustrate other embodiments of the invention. In the exploded perspective view of Fig. 21A, a disposable diaper 2100 includes an inner sheet 2104 of a water-permeable film, generally known and hereinafter referred to as cover stock 2104, that overlies a wetness absorber layer 2107 of highly liquid-absorbent padding or other highly absorbent material, generally known and hereinafter referred to as the core 2107. In one embodiment the core 2107 may include granules or filaments of water-retentive polymer, such as polyacrylic acid. An outer, electrically insulating plastic film that is impermeable to liquid water, generally known and hereinafter referred to as the backing sheet 2110, supports two conductive spaced-apart electrodes 2114, in the form of metallic or other electrically- conductive strips, with low surface area, hereinafter referred to as the sensing electrodes 2114, that extend along the center of the backing sheet 2110. The backing sheet 2110 also supports a tissue 2108 and a barrier 2109. According to embodiments of the invention, the sensing electrodes 2114 electrically contact the core 2107, or the tissue 2108, or the barrier 2109. According to an embodiment of the invention, the sensing electrodes 2114 pass longitudinally through the core 2107. According to another embodiment, sensing electrodes 2114 project along the interior surface of the backing sheet 2110 in contact with the core 2107. According to another embodiment, the sensing electrodes 2114 are in the form of conductive filaments, threads or wires.

The sensing electrodes are connected electrically to widened conductive areas 2117, hereinafter referred to as coupling electrodes 2117, that serve to couple signals between the sensing electrodes 2114 and a detector module that is to be placed against the outer surface of the backing sheet 2110. The detector module is provided with pickup electrodes each of which couples non-conductively, for example capacitively, to respective coupling electrodes 2117.

An optional tissue layer 2108 may be in contact with the core 2107, that serves to distribute wetness more quickly and uniformly about the core 2107, and that also serves to bring wetness from core 2107 into close contact with sensing electrodes 2114.

An optional wetness barrier layer 2109 may be interposed between a portion of the sensing electrodes 2114 and the core 2107 or the tissue 2108, that may serve to prevent wetness in the core 2107 from reaching a defined portion of the sensing electrodes 2114. If barrier layer 2109 is soluble in water, the effect will be a delay before wetness reaches the covered portion of the sensing electrodes 2114. If barrier layer 2109 is not soluble in water, the effect will be a requirement that the wetness in the core 2107 reaches beyond the covered portion of the sensing electrodes 2114 before the wetness may be detected.

Pocket slip 2112 is bonded to backing sheet 2110 along all but one of its edges to as to form the pocket 2111. The pocket 2111 is positioned so that when a detector module is placed therein, the pickup electrodes in the pocket 2111 are registered opposite the coupling electrodes 2117. The bonded area of pocket slip 2112 is identified with cross-hatching. If pocket slip 2112 is composed of material that is resilient, then insertion of an item that is slightly larger than the relaxed size of the pocket 2111 into the pocket 2111 will deform the unbonded portion of pocket slip 2112, which will tend to hold such an inserted item snugly in place and apply tension to the area of backing sheet 2110 located beneath the unbonded portion of pocket slip 2112. If pocket slip 2112 is composed of an inelastic material, then the same tension and secure insertion may be obtained by a combination of deformation of the backing sheet 2110 and deformation of the inserted item itself. According to one embodiment, one pair of the coupling electrodes 2117 and one pocket 2111 is located near either the front or the rear waistband of the diaper 2100, and in another embodiment, a separate set of these aspects is located near both waistbands.

In the exploded perspective view of Fig. 21B, a disposable diaper 2100 includes a sensor carrier layer 2119, onto which the sensing electrodes 2114 and coupling electrodes 2117 may be printed or otherwise pre-assembled prior to assembly onto backing sheet 2110.

Figs. 22A, 22B, 22C, and 22D show four possible arrangements of sensing and coupling electrodes 2114 and 2117. These represent repeated patterns that are to be parted at the separation line 2140. The separation line 2140 may correspond to the place where the diapers 2100 made in the machine direction are separated from one another near the end of the production line, or where sets of electrodes 2114 and 2117 that are printed or otherwise pre- assembled onto a carrier layer are separated prior to placement onto the backing sheet 2110, or the separation line 2140 may simply be conceptual, where electrodes 2114 and 2117 are assembled repeatedly onto a diaper that is made in the cross-direction.

In Fig. 22A, sensing electrodes 2114 are discontinuous, and there are two pair of coupling electrodes 2117 for each pair of sensing electrodes 2114. This provides a pair of coupling electrodes near each waistband. In Fig. 22B, sensing electrodes 2114 are also discontinuous, but there is one pair of coupling electrodes 2117 for each pair of sensing electrodes 2114. This provides a pair of coupling electrodes near only one waistband. In Fig. 22C, sensing electrodes 2114 are continuous, and there are two pair of coupling electrodes 2117 for each pair of sensing electrodes 2114. This provides a pair of coupling electrodes near each waistband. In Fig. 22D, sensing electrodes 2114 are also continuous, but there is one pair of coupling electrodes 2117 for each pair of sensing electrodes 2114. This provides a pair of coupling electrodes near only one waistband.

The sensing electrodes 2114 may be filaments, wires, yarn, ribbon, foil, fabric or film made from conductive material. The sensing electrodes 2114 may be filaments, yarn, ribbon, fabric or film that bears conductive filler material, that is coated with conductive material, or with surfaces subjected to a conversion process or suffused with a material that renders said surfaces conductive. The sensing electrodes 2114 may be in the form of yarn that includes continuous or discontinuous lengths of conductive filament or wire, that is wrapped with conductive filament or wire, that is infused with material that is conductive, or that is infused with material that bears conductive filler material. The sensing electrodes 2114 may be liquid or plastic material that is conductive or that bears conductive filler material, such as a thermoplastic, wax, paste, gel, latex, adhesive, or ink, that may be selectively applied onto a surface or into an absorbent matrix by methods such as printing, rolling, or extrusion.

Sensing electrodes 2114 may be formed by the selective conversion or suffusion of portions of a surface of a film, fabric or tissue material by a process that renders said portions conductive. Sensing electrodes 2114 may be formed by the selective removal of continuous conductive coating or converted outer layer from surface of a film material such as by abrasion or photolithography to render multiple isolated conductive areas (electrodes) from a continuous piece of coated film. Sensing electrodes 2114 may be formed by the selective removal of portions of an electrode film, fabric or tissue material such as by die-cutting to render multiple isolated conductive elements (electrodes) from a continuous element of coated film, fabric or tissue material.

Sensing electrodes 2114 may be redundant, in that each of the two electrodes that make up a pair may have more than one strand, ribbon, strip, etc., and that these redundant elements may be of different morphologies .

The coupling electrodes 2117 may be ribbon, foil, fabric, tissue or film made from conductive material. The coupling electrodes 2117 may be ribbon, fabric, tissue or film that bears conductive filler material, that is coated or infused with conductive material, or with surfaces subjected to a conversion process or suffused with a material that renders said surfaces conductive. The coupling electrodes 2117 may be ribbon, fabric, tissue or film material that is conductive or has one or both surfaces made conductive, where said structure is optically transparent or translucent. The coupling electrodes 2117 may be liquid or plastic material that is conductive or that bears conductive filler material, such as a thermoplastic, wax, paste, gel, latex, adhesive, or ink, that may be selectively applied onto a surface or into an absorbent matrix by methods such as printing, rolling, or extrusion.

The coupling electrodes 2117 may be formed by the selective conversion or suffusion of portions of a surface of a film, fabric or tissue material by a process that renders said portions conductive. The coupling electrodes 2117 may be formed by the selective coating of portions of a surface of a film, fabric or tissue material with conductive material, such as by sputtering or thermal vapor deposition. The coupling electrodes 2117 may be formed by the selective removal of continuous conductive coating or converted outer layer from surface of a film material to render multiple electrodes from a continuous piece of coated film. The coupling electrodes 2117 may be formed by the selective removal of portions of an electrode film, fabric or tissue material such as by die-cutting to render multiple electrode elements from a continuous element of coated film.

Figs. 23A and 23B depict two embodiments of an electrode arrangement where a plurality of individual electrodes 2314 and 2317 may function together to effectively form pairs of electrodes corresponding to sensing electrodes 2114 and coupling electrodes 2117 in Figs. 21A and 21B and 22A to 22D. In Fig. 23A, the electrodes are of uniform width, where the portions of these electrodes that are to function as the coupling electrodes 2317 are the portions that are located in coupling area 2316. In Fig. 23B, the sensing electrodes 2314 are narrower than coupling electrodes 2317. The arrangement of the electrodes into a plurality of parallel elements serves to provide great immunity to translational variation in the registration between the pocket 2111 and the coupling electrodes 2317.

Figs. 24, 25, and 26 depict three possible construction schemes pertaining to the placement of the electrodes relative to the other layers in the diaper 2100. Each figure is an elevation that cuts across a single coupling electrode 2117 in a direction orthogonal to the sensing electrode 2114, and that includes all layers but the pocket 2111. These are simplified to the extent that certain adhesive applications and other typical or possible processes are not depicted, and no indication is given as to the treatment of the various layers as they exist beyond the boundaries of the drawn area.

In Fig. 24, the backing sheet 2110 has been sprayed with the construction adhesive 2133, has had the sensing electrode 2114 laid down into the construction adhesive 2133, has had the coupling electrode 2117, which is oriented so that the conductive coating 2118 is facing the sensing electrode 2114, nipped down against the sensing electrode 2114, has had the tissue 2108 nipped down over both electrodes 2114 and 2117, has had the core 2107 nipped down over the tissue 2108, and finally had the cover 2107 nipped down over the core 2107.

An electrically conductive liquid, paste, putty, or powdered solid material may be deposited in the gap 2130 in contact with the sensing electrode and the coupling electrode.

Fig. 25 differs from Fig. 24 only in that barrier layer 2119 is added between tissue 2108 and sensing and coupling electrodes 2114 and 2117.

In Fig. 26, the side of the sensing electrode 2114 that bears the adhesive 2135 has been nipped down to the backing sheet 2110, and the side with the conductive coating 2118 faces outward. The tissue 2108 has been sprayed with the construction adhesive 2133, and the sensing electrode 2114 has been laid down into the construction adhesive 2133 in the tissue 2108, whereupon the tissue 2108 bearing the sensing electrodes 2114 has been nipped down to the backing sheet 2100 that bears the coupling electrodes 2117. This places the conductive coating 2118 on the coupling electrodes 2117 in contact with sensing electrodes 2114. The core 2107 is nipped down onto the existing structure, and ultimately the cover 2104 is nipped down over this .

An electrically conductive liquid, paste, putty, or powdered solid material may be deposited in the gap 2130 in contact with the sensing electrode and the coupling electrode.

Figs. 27 and 28 depict two possible arrangements of sensing and coupling electrodes 2114 and 2117 where they are incorporated into the core 2104. In both cases, sensing and coupling electrodes 2114 and 2117 are printed or otherwise pre-assembled onto a carrier layer 2119, and placed within the core 2104, with the ends bearing coupling electrodes 2117 protruding from its ends. In Fig. 27, the coupling electrodes 2117 are to be assembled to the backing sheet 2110 in an area near the waistband that is clear of the core 2104. In Fig. 28, the portion of carrier 2119 that bears the coupling electrodes 2117 is folded back over the core and is therefor located beneath the core in the finished diaper 2100.

In another embodiment, unsupported sensing electrodes 2114 are laid into the core 2107, and the coupling electrodes are brought down over them as in Fig. 24.

Fig. 29 is a detail of the pocket 2111 bonded to the backing sheet 2110, showing the bonded area around all but one edge of the pocket slip 2112,

Fig. 30 is the same as Fig. 29, except that one method of reinforcement of the unbonded edge of pocket 2111 is illustrated, where the edge that is not to be bonded to the backing sheet 2110 is folded over on itself one or more times and bonded to itself prior to or concurrent with the bonding of the pocket 2111 to the backing sheet 2110. In another embodiment, the open edge of the pocket 2111 is reinforced by bonding a separate strip of material to it.

Fig. 31 depicts the folding of the carrier strip 2119 bearing electrodes 2114 and 2117 so as to shorten its length. The Z-fold can be placed into the material as it is being assembled onto the diaper 2100, or prior to assembly.

Fig. 32 depicts an apparatus for abrading the conductive coating 2118 from the carrier strip 2119. Here, the rubber wheel 2210 rotates so that it rubs the carrier strip 2119 counter to its direction of travel.

Fig. 33 depicts an apparatus for applying the sensing electrodes 2114 into the construction adhesive 2133 on the backing sheet 2110. Reels of wire 3305 are fitted with appropriate feed, braking and anti-run-on means. Sensing electrodes 2114 in the form of wires take one or more turns around tensioning drums 3310, thread through direction control pins 3315, and are drawn onto backing sheet web 2110 by the motion of said web. Also depicted for clarity are pockets 2111, and frontal tape 2102. The backing sheet passes over a drum 3320.

Fig. 34 depicts an apparatus for removing the non-conductive fibers from the core of a yarn 3414 that has been spun-wrapped with wire to form an electrode 2114. Gaseous fuel source 3405 feeds gas to burner

3415. Gas flow modulator 3410 is connected in parallel with gas source 3405. Ignition source 3420 may ignite flame 3417. The yarn 3414 is drawn through the space directly over the flame, and the flame is modulated so that it vaporizes, melts, or partially vaporizes and partially melts the non-conductive fibers in the core of the yarn. The resultant segments of bare wire can make improved contact with conductive surfaces, such as coupling electrodes 2117.

Fig. 35 illustrates an example of a module 3504 having pickup electrodes 3507 in the pocket 2111 formed by the pocket slip 2112 on the backing sheet 2110. The pickup electrodes 3507 are positioned opposite, and are here non-conductively and capacitively coupled to, the coupling electrodes 2117 across the backing sheet 2110. Thicknesses are exaggerated for clarity.

Figs. 36 and 37 depict a portion of an embodiment of the backing sheet 2110 in the form a typical two-component cloth-like sheet 2110, composed of a non-woven fabric layer 2110A and a film layer 2110B, and containing a rectangular treated portion 3613. The treated portion 3613 includes a monolithic matrix of the non-woven fabric layer 2110A and the film layer 2110B. The treatment serves to increase the dielectric constant and decrease the thickness of the treated portion 3613, and to render it more amenable to later bonding of the pocket material . The treatment of the portion 3613 may be accomplished thermally or ultrasonically, but the preferred method is ultrasonic.

In Fig. 36, the treated portion 3613 is located centrally and near the front of the waistband, as indicated by the presence of the frontal tape 2102. According to other embodiments the treated area is alternatively or additionally located near the rear waistband or on another part of the diaper. For a given diaper construction, the position of the treated portion 3613 will tend to coincide with that of the pocket 2111 that is shown in various other figures.

Fig. 37 show the fibers of the backing sheet non-woven layer 2110A separate from and randomly oriented over the backing sheet film layer 2110B, except in the treated portion 3613. There, the two materials are shown combined into a monolithic matrix.

In addition to backing sheet film 2110B, the embedding encapsulant, according to embodiments .of the invention, includes another material added to either side of the portion 3613 prior to treatment. This additional material may be a thermoplastic film that is compatible with the backing sheet film 2110B, or it may be some other material that could serve the purpose of increasing the fraction of solid thermoplastic available to encapsulate the fibers of the non-woven backing sheet layer 2110A.-

Fig. 38 depicts the basics of an ultrasonic apparatus for performing the treatment of the portion 3613. The backing sheet 2110 is conveyed continuously on the roll 3855 with the non-woven layer 2110B typically facing the ultrasonic horn 3850. The ultrasonic horn 3850 is powered periodically, so that it supplies energy across its width to the backing sheet 2110 for uniform time periods at uniform time intervals. This is done to assure that uniform lengths of a narrow portion of the overall width of the backing sheet 2110 are subjected to treatment at uniform spatial intervals. According to an embodiment of the invention, a rotary horn is used as an alternative to a stationary horn in order to eliminate the risk of the backing sheet 2110 becoming snagged on the horn.

In each of the embodiments of Figs. 21A to 38, the diapers are made by forming each of the components of the figures, for example the components 2104, 2107, 2110, 2111, 2112, 2114, and 2117, assembling the components with suitable adhesives or other adhering means to achieve the arrangements shown, and then shaping them to the typical diaper shape. The order in which the components are formed or assembled may vary with the needs of the manufacturer.

A general manufacturing process may involve forming a liquid-impermeable backing sheet having an exterior surface and an interior surface so as to produce an exterior of the diaper and an interior of the diaper, forming a liquid-absorbing arrangement and placing the liquid-absorbing arrangement next to the backing sheet, forming an elastic pocket and bonding the pocket to the exterior surface of the backing sheet to contain a detector module, forming sensing electrodes and placing sensing electrodes within the interior of the diaper and within the interior surface of the backing sheet in contact with the liquid absorbing arrangement in a direction to extend opposite the elastic pocket so as to allow the sensing electrodes to couple capacitively to the detector module, assembling the various components by bonding, and forming the product into the shape of a diaper. The bonding of any component may occur at any phase of the process. Each of the elements formed and assembled are constructed to achieve the structure described for each of the figures and as described below. The process is finished by configuring the assembly into a diaper shape and adding elastics at the waist and legs and fastening strips 2130 to produce the diaper of Fig. 39.

According to embodiments of the invention, diapers are manufactured by automatic machine where component materials are supplied from rolls or other sources located at points in the line. In one example, the backing sheet runs as a web through the full length of the manufacturing line up to the point where the individual diapers are separated from one another. However, the backing sheet may be put in sheets. The other components are affixed continuously, individually, or in partially pre-assembled combinations upon the backing sheet 2110. In an exemplary machine direction assembly operation, at a point where the backing sheet web is fed in, the frontal tape is cut and placed onto the outer side of the backing sheet 2110, and the pocket 2111 is cut and bonded in place onto the outer side of the backing sheet 2110. Adhesive is applied onto the area where the coupling electrodes 2117 are to be placed, the sensing electrodes 2114 are fed in, the coupling electrodes 2117 are cut and placed, construction adhesive is applied to the entire surface, leg and waistband elastics are applied, and an absorbent pad 2107 that was formed off line is carried between a web of tissue layer 2109 and cover stock 2104 and fed in and affixed, and the backing sheet 2110 is cut to shape so as to narrow the crotch Finally, the individual diapers are cut apart, separated, folded, and bagged. The order of these steps may change as desired..

An example of an automatic machine appears in Fig. 40. Here, a manufacturing line 4101 receives a web of material that forms the backing sheet, either pre-formed or uncut, from a backing sheet web source 4104. The line 4101 either moves the pre-formed backing sheets along the line or cuts the web to form the backing sheets. A liquid-absorber layer source 4107 supplies the components of the liquid-absorber layer, either individually or as a unit, either pre¬ formed or as linear sheets, to the line 4101. The line 4101 bonds the liquid-absorbing arrangement to the backing sheet made from the web. An elastic pocket source 4110 supplies an elastic pocket, pre-formed or uncut, to the line 4101 and the latter bonds the elastic pocket to the backing sheet made from the web. A sensing electrode source 4114 supplies sensing electrodes, in partially or completely shaped condition, to the line 4101 and the latter bonds them in the proper position in contact with the liquid- absorbing arrangement and opposite the pocket. An elastic source 4117 furnishes elastic to the line 4101, and the latter adds the elastic, and cuts and shapes the diapers into the state shown in Fig. 39. The line 4101 also separates, folds, and bags the diapers.

According to various embodiments of the invention, each of the sources 4104, 4107, 4110, 4114, and 4117 assume different positions so that the order of processing may vary. The bonding may occur at phases of the process other than those shown. Also any one of the sources

4104, 4107, 4110, 4114, and 4117 may supply pre-formed or partially formed materials, and the line 4101 uses these material. Where the sources furnish incomplete or partially formed components, the line 4101 constructs the material into final forms.

According to embodiments of the invention, the sensing electrodes are made as any one or more of the following: filament, wire, yarn, ribbon, foil, fabric or film made from conductive material filament, yarn, ribbon, fabric or film that bears conductive filler material, that is coated with conductive material, or with surfaces subjected to a conversion process or suffused with a material that renders said surfaces conductive yarn that includes continuous or discontinuous lengths of conductive filament or wire, that is wrapped with conductive filament or wire, that is infused with material that is conductive, or that is infused with material that bears conductive filler material liquid or plastic material that is conductive or that bears conductive filler material, such as a thermoplastic, wax, paste, gel, latex, adhesive, or ink, that may be selectively applied onto a surface or into an absorbent matrix by methods such as printing, rolling, or extrusion selective conversion or suffusion of portions of a surface of a film, fabric or tissue material by a process that renders said portions conductive selective removal of continuous conductive coating or converted outer layer from surface of a film material such as by abrasion or photolithography to render multiple isolated conductive areas (electrodes) from a continuous piece of coated film selective removal of portions of an electrode film, fabric or tissue material such as by die-cutting to render multiple isolated conductive elements (electrodes) from a continuous element of coated film, fabric or tissue material electrodes may be in the form of a plurality of stripes each electrode may consist of a plurality of conductors .

According to embodiments of the invention, the attachment of the electrodes involves doing any one or more of the following: selective coating or application of conductive material onto portions of a surface of a film, fabric or tissue material where said surface may be the backing sheet or where said film, fabric or tissue material may be subsequently applied onto said backing sheet incorporation into pad, tissue, or other component layer such as by weaving or laminating.

According to embodiments of the invention, the coupling electrodes are made as any one or more of the following: ribbon, foil, fabric, tissue or film made from conductive material ribbon, fabric, tissue or film that bears conductive filler material, that is coated or infused with conductive material, or with surfaces subjected to a conversion process or suffused with a material that renders said surfaces conductive ribbon, fabric, tissue or film material that is conductive or has one or both surfaces made conductive, where said structure is optically transparent or translucent liquid or plastic material that is conductive or that bears conductive filler material, such as a thermoplastic, wax, paste, gel, latex, adhesive, or ink, that may be selectively applied onto a surface or into an absorbent matrix by methods such as printing, rolling, or extrusion selective conversion or suffusion of portions of a surface of a film, fabric or tissue material by a process that renders said portions conductive selective coating of portions of a surface of a film, fabric or tissue material with conductive material, such as by sputtering or thermal vapor deposition selective removal of continuous conductive coating or converted outer layer from surface of a film material to render multiple electrodes from a continuous piece of coated film selective removal of portions of an electrode film, fabric or tissue material such as by die-cutting to render multiple electrode elements from a continuous element of coated film electrodes may be in the form of a plurality of stripes .

According to an embodiment of the invention, connection of each coupling electrode to each sensing electrode are made as one or more of the following: connection formed by conductive adhesive that is printed, transferred, thermally bonded or otherwise applied to the coupling electrode, the sensing electrode, or to another surface to which the electrodes are to be bonded connection formed by physical contact, where sensing electrode is interposed between a coupling electrode and another surface, where a non- conductive adhesive is applied to said other surface that holds said coupling electrode to said other surface connection optionally enhanced by presence of an electrically conductive liquid, paste, putty, or powdered solid material in contact with the sensing electrode and the coupling electrode

According to an embodiment of the invention, combined sensing and coupling electrodes are made as one or more of the following: electrode pattern deposited or pre-assembled onto a carrier film, fabric or tissue, where pattern may be repeated continuously on a roll of material, either in the machine or cross directions, and where pattern may consist of pairs of sensing electrodes with coupling electrodes at one or both ends when printed, the ink used for the sensing electrodes and the coupling electrodes may have different conductivity' s electrodes that are uniform in width along their entire length where diminished sensitivity to conditions external to the diaper may be attained by the placement of the electrodes so that one or more layers of dielectric material are interposed between the portion that will perform the sensing function and the backsheet where the electrodes may be in the form of a plurality of stripes According to an embodiment of the invention, the pocket involves making it in one or more of the following ways: composed of an elastomeric or plastomeric, solid or foamed, film or fabric material to retain a substantially non-deformable item, or a substantially inelastic film or fabric material to retain a spring-loaded deformable item transparent or opaque printing with or without superficial or sub-surface formed by bonding a relatively small patch of material along all but one of its edges directly to the backsheet to the bondable surface of a secondary patch of material, such as a label or frontal tape, that is applied to the backsheet reinforcement of the open edge by rolling and self- bonding an edge of the patch of material that will become the open edge prior to bonding onto a diaper or secondary patch of material reinforcement of the open edge by bonding a strip of reinforcing material to an edge of the patch of material that will become the open edge prior to bonding onto a diaper backsheet or secondary patch of material printing on transparent material, forming a portion of a graphic that is completed or changed when the pocket is occupied by an object bearing a corresponding graphic acts to obscure a view of the electrodes from the exterior of a diaper According to embodiments of the invention, the attachment of the pocket to the backsheet involves any one or more of the following steps: direct thermal or ultrasonic bonding; thermoplastic or thermosetting adhesive bonding adhesive as coextruded skin on pocket material, selectively bonded, adhesive selectively printed on pocket material; allows selective bonding by heating full area, adhesive film co-laminated with pocket, selectively bonded adhesive printed or sprayed onto pocket material and selectively bonded; bond directly to backsheet backsheet may be printed forming a portion of a graphic that is completed or changed when the pocket is occupied by an object bearing a corresponding graphic, acting to obscure a view of the electrodes from the exterior of a diaper; bond to a label that is applied to the backsheet label may be variously opaque to obscure view of electrodes, variously opaque material, variously opaque coating on transparent or variously opaque material, label may be printed forming a portion of a graphic that is completed or changed when the pocket is occupied by an object bearing a corresponding graphic, acting to obscure a view of the electrodes from the exterior of a diaper; deformable module with a generally non-deformable pocket to achieve retention and tension; side levers on module actuate one or more switches, retain one or more batteries, provide tensile force against sides of pocket.

According to embodiments of the invention, the control mechanisms operate any one or more of the following ways:

interposition of a layer of water barrier film between the sensing electrodes and the absorbent material in the vicinity of the urine discharge area to prevent wetness from reaching said electrodes until the core is to some degree saturated;

interposition of a layer of water-soluble, water barrier film between the sensing electrodes and the absorbent material to impart a time delay prior to when wetness reaches the sensing electrodes; alteration of the length or the spacing or both the length and spacing of the sensing electrodes to alter the degree to which the core must be saturated and the speed with which wetness reaches said electrodes.

According to embodiments of the invention, the structures and orientations involve assembling the components to achieve any one or more of the following sequences : backsheet/construction adhesive/sensing electrode/ film coupling electrode/core backsheet/PSA/sensing electrode/ film coupling electrode/core backsheet/construction adhesive/sensing electrode/ film coupling electrode/tissue/core backsheet/PSA/sensing electrode/ film coupling electrode/tissue/core backsheet/PSA/film coupling electrode/sensing electrode/construction adhesive/tissue backsheet/printed coupling electrode/sensing electrode/construction adhesive/tissue According to embodiments of the invention, the methods for manufacture involve any one or more of the following steps : adjustment of the length of combined sensing and coupling electrodes to match various diaper lengths, where said combined electrodes are first deposited or pre-assembled onto a carrier film, fabric or tissue with coupling electrodes at both ends, said length adjustment executed by imparting a double fold, generally known as a Z-fold, across the carrier film, such as during or proximal to the process of cutting and placing the combined electrodes onto a diaper backsheet clear a swath in the conductive coating on the coupling electrode material to render multiple electrodes from a continuous piece of coated film using abrasion rotating frictive wheel, such as of rubber rotating abrasive wheel, such as of grit-coated aluminum rotating wire or fiber wheel, such as of brass or polyester one or more blade edges, oriented so as to scrape rather than slice the material surface using an electrical arc using a beam of light, such as from a laser incorporate coupling electrodes into a diaper by unwinding electrode material from a roll or spool where coupling electrode material is slit, cut and placed where electrode material may bear a coating of conductive adhesive where another layer to which the coupling electrode is being applied may bear a coating of adhesive where the adhesive may be pressure-sensitive or thermally activated, transparent or variously opaque incorporate coupling electrodes into a diaper by printing conductive ink onto backsheet incorporate sensing electrodes into a diaper by unwinding electrode material continuously in-line with the backsheet in the case of diapers that are made in the machine direction where the electrode material is affixed to the backing sheet by laying it onto open construction adhesive previously applied to the backsheet by laying it onto the backsheet and keeping it in tension before the construction adhesive is applied where the sensing electrodes are severed between diapers by the same blade or blades that separate the diapers from one another by an electric current applied to a relatively short span of the sensing electrodes by knife edges in the region of the waistband incorporate sensing electrodes into a diaper by cutting and placing lengths of electrode material where the electrode material is affixed to the backing sheet by laying it onto open construction adhesive previously applied to the backsheet by laying it onto the backsheet and keeping it in tension before the construction adhesive is applied where the lengths of electrode material are cut to length using one or more blades, water jets, flames, or beams of light, such as from a laser remove the non-conductive fibers from segments of a continuous yarn containing or wrapped with one or more conductive fibers or wires by application of a flame where the flame height and intensity is modulated by direct modulation of the gas flow where the flow rate modulation is effected by control of a valving orifice plumbed in series with the gas flow where the flow rate modulation is effected by the motion of a piston in a cylinder or a diaphragm in a cavity that has a single inlet plumbed in parallel with the gas flow by modulation of the flow velocity of a cross-flowing jet of air by modulation of the flow into a cross- oriented vacuum inlet by a combination of the above where the flame is interrupted periodically by a perforated solid or mesh disk, while optionally the gas flow is simultaneously modulated where the flame is intermittently applied by moving the gas nozzle, while optionally the gas flow is simultaneously modulated by application of a jet of hot air (with similar approaches to modulation or interruption) by application of a modulated beam of light, such as from a laser by application of a jet of water where the jet is intermittently applied by moving the nozzle, while optionally modulating the flow simultaneously.

According to embodiments of the invention, the coating materials involve incorporating one or more of the following-. metals for optically dense, electrically conductive coating, such as Ni , NiCr, Ni over Al, Sn se iconductive oxides to create an optically transparent, electrically conductive coating, such as ITO, ATO, ZnO multiple layers incorporating both metals and oxides to create an optically transparent, electrically conductive coating, such as Al₂0₃/Ag/ITO

According to embodiments of the invention, the electrode materials are made as, or in any one or more of the following ways : fabric made electrically conductive by impregnation with one or more salts that remain wet, and therefore ionic and conductive, due to the hygroscopic nature of the mixture, such as of calcium chloride and sodium chloride, or lithium chloride and sodium chloride electrically conductive putty composed of a mixture of an electrically conductive filler and an oil base, optionally made stickier by the addition of one or more tackifiers, such as rosin.

According to other embodiments of the invention, the other aspects of the structure or method involve one or more of the following means or steps: coat surface of item to be placed into pocket with slippery coating, such as wax coat interior surfaces of pocket with slippery material, such as silicone oil.

While embodiments of the invention have been described in detail it will be evident to those skilled in the art that the invention may be embodied otherwise without departing from its spirit and scope.

Claims

What is claimed is:

1. A wetness detector for a detecting electrolytic wetness in a first area, said first area being subject to wetness, comprising:

a first electrode projecting into the first area;

a second electrode spaced from the first electrode and projecting into the first area;

a sensing device in the second area protected from wetness in said first area and non-conductively coupled to each of said electrodes and responsive to the impedance between said electrodes in said first area so as to produce a signal when the first area becomes wet and electrolytic wetness couples the electrodes in the first area.

2. A wetness detector as in claim 1, wherein said sensing device is capacitively coupled to said first and second electrodes.

3. A wetness detector as in claim 1, wherein said sensing device includes a first conductor in said second area protected from the wetness of said first area and capacitively coupled to said first conductor and a second conductor in said second area protected from wetness of said first area and capacitively coupled to said second conductor.

4. A wetness detector as in claim 1, wherein said sensing device includes a source of varying voltage coupled non-conductively to said first and second electrodes and a signal output responsive to reduction of impedance between said electrodes.

5. A wetness detector as in claim 2, wherein said sensing device includes a source of varying voltage coupled capacitively to said first and second electrodes and a signal output .

6. A wetness detector as in claim 3, wherein said sensing device includes source of varying voltage connected to said first conductor and to said second conductor, and further includes a signal output responsive to reduction of resistance between said electrodes .

7. A wetness detector as in claim 1, wherein said sensor includes a signal output responsive to reduction of resistance between said electrodes.

8. A wetness detector as in claim 7, wherein said signal output is audible .

9. A wetness detector as in claim 7, wherein said signal output is visible .

10. A wetness detector as in claim 7, wherein said signal output is in the form of radio waves .

11. A wetness detector as in claim 7, wherein said signal output is m the form of infra-red radiation.

12. A wetness detector as in claim 7, wherein said coupling is capacitive, said sensor having a pair of fixedly spaced planar conductors and said electrodes having a pair of fixedly spaced pad shaped conductors respectively capacitively coupled to said planar conductors, one of said pair of conductors being larger than the other of said conductors to permit misalignment of said conductors relative to each other without changing capacitance between said conductors.

13. A diaper, comprising:

an absorbent portion;

a liquid resistant portion having first and second faces and lining the absorbent portion along the first face;

a pouch on the second face of the liquid resistant portion;

a first electrode extending along said absorbent portion and projecting along the first face of the liquid resistant portion opposite the pouch;

a second electrode space from the first electrode and extending along said absorbent portion and projecting along the first face of the liquid resistant portion opposite the pouch;

said first and second electrodes projecting along the absorbent portion opposite the pouch and being insulated from said pouch so as to non- conductively couple to contents in the pouch.

14. A diaper as in claim 13, wherein said electrodes have enlarged portions opposite said pouch.

15. A diaper as in claim 13, wherein said electrodes are coated on plastic material.

16. A diaper as in claim 13, wherein said electrodes are conductive areas on a water permeable substrate.

17. A diaper as in claim 13, wherein said electrodes are conductive wires.

18. A diaper as in claim 13, wherein said electrodes are conductive threads woven into the absorbent material .

19. A diaper as in claim 13, wherein said electrodes are printed on said liquid resistant portion.

20. A diaper as in claim 13, wherein said pouch contains a sensor non-conductively coupled to said electrodes.

21. A diaper as in claim 13, wherein said pouch contains a sensor capacitively coupled to said electrodes.

22. A diaper as in claim 20, wherein said sensor includes a source of varying voltage and an alarm responsive to urine induced lowered resistance between said electrodes.

23. A diaper as in claim 13, wherein said sensor includes a pair of conductive plate-shaped members opposing said electrodes across said liquid resistant portion.

24. A diaper in claim 13, wherein said coupling is capacitive, said sensor having a pair of fixedly spaced planar conductors and said electrodes having a pair of fixedly spaced pad shaped conductors respectively capacitively coupled to said planar conductors, one of said pair of conductors being larger than the other of said conductors to permit misalignment of said conductors relative to each other without changing capacitance between said conductors.

25. A wetness detector for placement in a pouch on the outside of a waterproof sheath of the diaper having an absorber and a pair of electrodes extending into the absorber and along the sheath opposite the pouch, comprising:

a source of varying voltage;

a pair of members spaced from each other for placement against the outside of the sheath within the pouch;

and alarm responsive to detection of low impedance between the conductive members.

26. A detector as in claim 25, wherein said alarm is audible.

27. A detector as in claim 25, wherein said alarm is electromagnetic.

28. A detector as in claim 25, wherein said alarm is visible.

29. A detector as m claim 25, wherein said alarm is in the form of radio waves .

30. A detector as in claim 25, wherein said alarm is in the form of infrared radiation.

31. A detector as m claim 25, wherein said members are plate shaped for capacitive coupling with electrodes in the diaper.

32. A detector as m claim 25, wherein said members are inductive to couple inductively with electrodes in the diaper.

33. A detector as in claim 25, further including a housing, said housing having tapered and beveled edges.

34. A detector as m claim 33, wherein said housing includes an extractor tab

35. A detector as in claim 33, wherein said housing includes a spring loaded switch.

36. A detector as m claim 33, wherein said housing has a curved surface

37. A detector as m claim 25, wherein said alarm produces tactilely-sensible vibrations.

38. A detector as m claim 25, wherein said alarm is audible.

39. A detector as in claim 25, wherein said alarm is visible.

40. A detector as in claim 25, wherein said alarm is electromagnetically detectable.

41. A method of manufacturing a diaper, comprising:

forming a liquid-impermeable backing sheet having an exterior surface and an interior surface so as to form an exterior of the diaper and an interior of the diaper;

bonding a liquid-absorbing arrangement to the interior surface of the backing sheet;

bonding an elastic pocket to the exterior surface of the backing sheet to contain a detector module;

placing sensing electrodes within the interior of the diaper and within the interior surface of the backing sheet m contact with the liquid absorbing arrangement that is bonded to the backing sheet, and in a direction to extend opposite the elastic pocket that is bonded to the outside of the backing sheet so as to allow the sensing electrodes to couple capacitively to the detector module.

42. A method as m claim 41, wherein bonding of the liquid absorbing arrangement includes placing a wetness-absorbing core layer on the water-impermeable layer and placing a water-permeable film layer on the core layer.

43. A method as in claim 41, wherein placing the sensing electrodes includes bonding coupling electrodes forming a part of the sensing electrodes and having widened conductive areas on the ends of the sensing electrodes against the interior surface of the backing sheet opposite the elastic pocket.

44. A method as in claim 42, wherein bonding of the liquid absorbing arrangement includes placing a wetness distributing tissue layer between the backing sheet and the wetness-absorbing core layer and over the sensing electrodes.

45. A method as m claim 41, wherein bonding of the liquid absorbing arrangement includes placing a wetness-impermeable barrier between portions of the sensing electrodes and the core layer to define parts of the electrodes to be subject to liquid.

46. A method as in claim 43, wherein placing sensing electrodes within the interior of the diaper and within the interior surface of the backing sheet includes assembling the sensing electrodes and the coupling electrodes with a sensor carrier and bonding the sensor carrier to the backing sheet .

47. A method as in claim 41, wherein placing sensing electrodes within the interior of the diaper and within the interior surface of the backing sheet includes forming pluralities of pairs of sensing electrodes in a continuous line and separating the pairs of sensing electrodes from the other pairs before placing each pair of sensing electrodes in a diaper.

48. A method as in claim 41, wherein placing sensing electrodes within the interior of the diaper and within the interior surface of the backing sheet includes forming the sensing electrodes by selective removal of continuous conductive coating or converted outer layer from surface of a film material to render multiple isolated conductive areas from a continuous piece of coated film.

49. A method as in claim 41, wherein placing sensing electrodes within the interior of the diaper and within the interior surface of the backing sheet includes forming each sensing electrode from a plurality of parallel filamentary elements.

50. A method as in claim 41, wherein placing sensing electrodes within the interior of the diaper and within the interior surface of the backing sheet includes forming the sensing electrodes of filamentary elements in contact with flat conductors forming the coupling electrodes nipped down against the sensing electrode with the tissue layer nipped down over said sensing and said coupling electrodes and the core layer nipped down over the tissue layer and the tissue layer nipped down over the core layer.

51. A method as in claim 41, wherein placing sensing electrodes includes placing an electrically conductive material in spaces adjacent the sensing electrodes .

52. A method as in claim 41, wherein placing sensing electrodes within the interior of the diaper and within the interior surface of the backing sheet includes incorporating the sensing electrodes within the core layer.

53. A method as in claim 42, wherein placing sensing electrodes within the interior of the diaper and within the interior surface of the backing sheet includes incorporating the sensing electrodes within the core layer and extending the ends of the electrodes outside of the core layer between the core layer and the backing sheet .

54. A method as in claim 41, wherein placing sensing electrodes within the interior of the diaper and within the interior surface of the backing sheet includes forming the sensing electrodes by abrading portions of a conductive layer from a ribbon of non- conductive material carrying a conductive layer.

55. A method as in claim 41, wherein placing sensing electrodes within the interior of the diaper and within the interior surface of the backing sheet includes forming the sensing electrodes by placing conductive filaments on an adhesive on a backing layer.

56. A method as in claim 41, wherein placing sensing electrodes within the interior of the diaper and within the interior surface of the backing sheet includes forming the sensing electrodes by spin wrapping wire about a yarn.

57. A method as in claim 41, wherein forming the backing sheet includes forming the backing sheet from two overlying bonded components and treating a portion at the pocket to make the portion at the pocket thinner than the remainder of the backing sheet.

58. A method as in claim 57, wherein treating a portion of the backing sheet at the pocket includes ultrasonic treatment .

59. An apparatus for manufacturing a diaper, comprising:

means for forming a backing sheet having an exterior surface and an interior surface so a to form an exterior of the diaper and an interior of the diaper and including a backing sheet carrier;

a wire feed, braking, and anti-run-on placement device adjacent the backing sheet carrier;

wire directional control pins aligned with said placement device above the backing sheet carrier and in the path of wire passing to said backing sheet;

means for bonding a tissue layer to the interior surface of the backing sheet and wires; and

means for bonding an elastic pocket to the exterior surface of the backing sheet to contain a detector module .

60. An apparatus as in claim 59, wherein said means for bonding a pocket includes a backing sheet thinner for making a portion of the backing sheet thinner at the location of the pocket .

61. A wetness detector, comprising:

a source of varying voltage;

a pair of conductive members spaced from each other for placement in the vicinity of an area to be tested for wetness;

and alarm responsive to detection of conductance between the conductive members;

a counter for counting the number of times wetness is detected.

62. A detector as in cLaim 61, wherein said alarm is audible.

63. A detector as in claim 61, wherein said alarm is visible.

64. A detector as m claim 61, wherein said alarm is both audible and visible.

65. A detector as in claim 61, wherein said members are plate shaped for capacitive coupling with electrodes in the area to be sensed for wetness.

66. A detector as in claim 61, further including a housing, said housing having tapered and beveled edges .

67. A detector as m claim 66, wherein said housing includes an extractor tab.

68. A detector as m claim 66, wherein said housing includes one or more retractable levers.

69. A detector as m claim 66, wherein said housing has one or more curved surfaces, where said levers may be spring-loaded.

70. A detector as in claim 61, wherein said alarm is visible.

71. A detector as m claim 61, wherein said alarm is visible.

72. A detector as in claim 61, wherein said counter stops detection after a predetermined number of counts .

73. A detector as in claim 61, wherein said source includes a signal generator having a duty cycle less than 50%.

74. A detector as in claim 61, wherein said source includes a signal generator having a duty cycle less than 1/2000.

75. A detector as in claim 61, wherein said alarm includes an LED blinker circuit.

76. A detector as in claim 61, wherein said alarm includes a piezo tone generator.

77. A detector as in claim 61, wherein said alarm includes a piezo presence sensor to sense the presence of a piezo device .