US2335277A - Magnetic recording machine - Google Patents

Description

Nov. 30, 1943. H. s. HELLER MAGNETIC RECORDING MACHINE 7 Sheets-Sheet 1 Filed Oct. 25, 1940 Nov. 30, 1943. H. s. HELLER MAGNETIC RECORDING MACHINE Filed Oct. 25, 1940 7 Sheets-Sheet 2 .Zizwenfar J/man Sin/Elle,

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Filed 001:. 25, 1946 MNQN MMMM

Patented Nov. 30, 1943' MAGNETIC nnconnmc MACHINE 'Herman S. Heller, West Los Angeles, Calif. Application October 25, 1940, Serial No. 362,754

' 11 Claims. (01.179-1002) r This invention relates generally to magnetic recording machines, and more particularly "to magnetic recording machines of the typein which a multiplicity of recordings are made in parallellines along a record tape.

The general object of the present invention is the provision of a multiple lane recording machine adapted particularly to the making of preliminary flight tests of aircraft. The invention will therefore be described with this application particularly in view though no limitation to such use is to be implied since the invention has various other applications.

In making preliminary flight tests of aircraft, it is now frequent practice to employ a recording oscillograph for making records of noise and vibration. The oscillograph, however, has several disadvantages. Among these are the cost and delicacy of such equipment, the necessity of processing the record prior to reproduction, the fact that. the picture record which it produces'is not in a form capable of simple and convenient analysis, and the further fact that the recording oscillograph cannot be employed for recording speech in a manner capable of easy reproduction.

The recording machine of the present invention employs one or more magnetic record tapes, each furnished with a multiplicity of recording magnets, which are spaced transversely of the tape and so designed that each magnet acts on a limited width lane of the tape. A multiplicity of parallel, separate recordings are thus made across the width of a single tape. A feature of primary importance i the provision of arrangements for employing the several record lanes either simultaneously or consecutively. Thus, assuming eight lanes, and a time of one hour for running the tape through the machine, eightfrecordings of on hour duration may be made simultaneously, or one recording of eight hours duration may be made by using the several lanes consecutively. It is sometimes very desirable to make one recording of extended time in which case the record lanes are used consecutively. On the other hand, the optional capability of using all lanes simultaneously is of g eat advantage in such practical applications as testing aircraft, where a number of tests can be performed simultaneously. Thus, in flight testing a plane, it is the practice to mount a number of vibration and noise pick-up devices in various places of interest about the plane. In accordance with the invention, these are connected to input channels leading to the several recording magnets of my multiple lane-recording machine.

Connected to other input channels may be conventional instruments providing voltages proportional to meter readings, stresses, motor temperature, motor R. P. M. etc.. .One or more input channels may be reserved for microphones, into which the pilots or observers may dictate observed data, such as plane behavior during flight evolutions, meter readings, etc., the possibility of dictating instead of writing observed data allows for great savings of time, and allows for recording many occurrences which otherwise could not be noted down for lack of time.

The capability for making various necessary records simultaneously means very heav savings in test flight time and expense. Further, in the event of a fatal crash during the test fl ght, the dictated data becomes invaluable in ascertaining the cause of the accident.

A present illustrative form of the invention, embodying various features not above mentioned, will now be described in detail, reference being made to the accompanying drawings, in which:

Fig, 1 is a plan view of the main or bottom section of a present illustrative embodiment of the recording machine, with all the view being taken as indicated by line [-5 of Fig. 3;

Fig. 2 is a bottom plan view of the section seen in Fig. 1, Fig. 2 being a section taken as indicated by line 2-2 of Fig. 3;

Fig. 3 is a view taken as indicated by the broken line 3-3 of Fig. 2, and also by the arrows 33 on Fig. 1;

Fig. '4 is a section taken as indicated by line 4-4 on Figs. 1 and 3;

Fig. 5 is a. section taken on line 55 of Fig. 1;

Fig. 6 is a section taken on line 6-6 of Fig. 1;

Fig. 7 is a section taken on line 1-! of Fig. 6, being a section through one of the reel driving clutches;

Fig. 8 is a view similar to Fig. 7 but taken through the other reel driving clutch;

Fig. 9 is a diagram showing one tape threading arrangement for erasing purposes;

Fig. 10 is a section taken on line ill-l0 of Fig. 1;

Fig. 11 is a section taken on line lll| of Fig. 10;

Fig. 12 is a section taken on line |2l2 of Fig. 10, but'with the recording head in open position;

Fig. 13 is a section taken as indicated by line l3 |3 of Fig. 1;

parts above removed,

Fig. 14 is a schematic diagram of the record= ing system; and

, Fig. 15 shows a portion of the system of Fig. 14,

with reproducing means connected-in place of in put means.

A feature of the invention is the provision of a magnetic recording machine in sectional form, one section of which carries the driving motor,

accept and also the driving, guiding and recordingprovisions for one magnetic tape, and one or more sections of which carryv the driving, guiding and recording provisions for additional tapes, each.

the illustrated section I6 as desired. The power of the drive motor of course limits the number of such sections that may be used in any given instance. L

'tion disclosed, the several sections embody frame plates or. deck I1, arranged preferably in horizontal planes one above the other as illustrated in Fig. 3. Deck I1 of lower or motor section I is secured by screws I8 to an inwardly turned flange I9 at the upper edge of a suitablesheet metal housing 26 which encloses the parts of section I5 mounted on the underside of deck I1. A removable plate 2| at the bottom of housing 26 permits access to the interior of the latter.

At the upper end of housing 26 is an encircling band 24, and received inside said band 24 is a housing section 25 extending downwardly from section l6. This housing section 25 is flanged inwardly at its top edge, as at 26, and is secured to the deck I1 of section I6. At the upper end of housing section 25 is an encircling band 21 similar to band 24, andreceived inside the band 21 is a housing cover 28. Locking devices of any suitable type, as indicated at 29, may be employed to secure the housing parts in assembly.

When two or more sections are used, the decks of the several sections are spaced and supported one above the other by means of supporting posts 35 located at the four corners of the decks. In the preferred construction as illustrated in Fig. 3, the lower end of each post 35 is supported within a cup 36 resting on the deck I1 immediately below, and having a reduced screw-threaded stud 31 extending downwardly through the latter and secured in place as by a nut 38. The upper end portion of the post is reduced as at 39, affording an upwardly facing annular houlder at 40 which supports the deck I1 above, in the arrangement clearly illustrated in Fig. 3. A cup 36a, generally similar to cup 36, rests on this deck I1 and has a bored, externally screwthreaded stud 42 projecting downwardly through the deck. This stud is threaded within a socket 43 in the upper end of post 35. The lower end portion of post 35 is formed witha socket 45, which receives a stud 46 extending upwardly from cup member 36, and a long screw 48 reaching downwardly through stud 43 and through a central bore 49 in post '35 is screwed into a socket in the upper end of stud 46. A lock washer 50 is preferably placed between the head 5| of screw 48 and the face 5Ia of cup member 360. and head 5| is formed with a screwthreaded socket 52 for engagement by a screw similar to screw 46 in the event of addition of one or more further sections above. -Cup member 5| with its screwthreaded stud 62 holds post 35 in assembly with upper deck i1, while screw 48 serves to secure the post and the deck Ii above down to lower deck I1.

When only the lower section E5 of the machine is to be used, the whole of section i6 is removed by removing thefo'ur corner screws 68,- and it will be understood that the cover 28 may then be mounted directly on section I5.

The electric drive motor, designed generally at 55,- is hung by means of a suitable mounting 56' from the underside of the deck I1 of lower sec- In the particular exemplification of the invention I5, the motor being arranged in a horizontal position, as illustrated. This motor is preferably a governor-controlled variable speed motor, of a known type, such as manufactured by Bodine Electric Company, the end portion 55a of the motor housing containing a governor which is set to adjust the speed of the motor by means of a screw 51 manipulated by a manual operating knob 58 projecting through the wall of housing 20, Such motors are well known and will require no description here.

The other end of motor 55 has a right-angle drive 60, containing conventional gearing whereby vertical shaft 6| is driven at reduced speed from the shaft of the motor. The disposition of the motor is such that this shaft 6| is at about the center of deck I1.

Shaft 6| (see Fig. 4) has a reduced, slotted upperend portion 62, adapted to receive and drivingly engage a transverse pin 63 carried by the lower end of a sleeve 64, which is pinned, as at 65, onto a shaft 66 extending up through deck I1. Shaft 66 is journaled in a bushing 61 carried by a bearing 68 secured to deck I1, and has above bearing 68 a, head 69 providing a downwardly facing shoulder 16 which bears on a thrust bearing 1| supported by the upper end of bearing 68. A similar thrust bearing 12 is placed between bearing 68 and sleeve 64. A pair of pulleys 13 and 14, for a purpose presently to be described, are set on sleeve 64.

Shaft 66 of lower section I5 has above head 69 a reduced end portion 15 provided with a transverse coupling pin 16, which is engaged by a slot 11 in the lower end of a sleeve 64a. mounted I on the lower end of the corresponding shaft 66 The head 69 near the of the section I6 above. upper end of shaft 66 of upper section I6 may be equipped with a hand wheel 18 by which the shaft may be conveniently rotated to enable the slot 11 to be engaged with the coupling pin 16 of the shaft below.

The described shafts 66, through the correlating magnets as described for the lower section will be duplicated for each section above.

In the particular embodiment shown in Figs. 1-5, pulley 13 on shaft 66 is connected by belt 86 with pulleys 8| and 82 set upon reel shafts 83, the latter being spaced apart sufliciently to accommodate the two tape reels indicated at 84 in Fig. 1. As will appear, the two reelsare positioned side by side, over substantially one half of the deck II, the two reel shafts and drive shaft ll forming a triangle. Each reel shaft I! (see Fig. 6) is journalled in a bushing 85 carried by a bearing 86 mounted on and extending through deck II. Shaft ll projects upwardly above deck I! as illustrated. and has immediately above the deck an integral flange 48 supported by thrust bearing 89.

Reels 44 mounted on the portions of shafts 83 projecting above deck I1 are preferably of a type disclosed and claimed in a copending application of Homer G. Tasker, entitled Magnetic recording machine. One of these reels is shown in section in Fig. 6, and will be seen to embody a pair of complementary hub members an and II. to which are fastened the two reel flanges 32. Enclosed and relatively rotatable within hub members and SI is a clutch disk 95 having a central bore 96 which receives shaft 83 with free rotating fit. Mounted in angular cavities 91 in disk 85, which open inside bore 96, are rollers 98 engaged by shaft 83 as shown in Fig. 7. The rollers 88 are yieldingly urged into engagement with shaft 83 by means of resilient felt pads 99 placedin cavities 91 in back of the rollers. The described elements form a simple and effective overrunning or roller-ratchet clutch, rotation of shaft 83 in a clockwise direction as viewed in Fig. '7 taking place without corresponding rotation being imparted to disk 95, while rotation of shaft 83 in a counterclockwise rotation results in wedging of the rollers 98 and rotation of disk 95. It may here be mentioned that Fig. 7 shows the clutch for the left hand reel 84 as viewed in Fig. 1, while Fig. 8 shows the corresponding clutch for the right hand reel 84 in said figure. The two clutches will be seen tobe identical except for the fact that the clutch disk of the left hand reel 84 is driven when the corresponding reel shaft 83 is driven in a counterclockwise direction, whereas the clutch disk 95 of the right hand reel is driven when the corresponding shaft 83 is rotated in a clockwise direction.

The rotation of clutch disk 95 is imparted to the reel through pairs of buttons or pads I02,-

preferably formed of some such material as fiber or Micarta, which. are mounted in holes I03 extending through the disk and are pressed outwardly against the inside surfaces of hub members 30 and 9| by means of springs I04. The rollers 98 form a positive one-way driving connection between shaft 83 and disk 35. The spring-pressed pads I02 provide a yielding or slipping frictional or driving connection between the sides of disk 95 and the hub of the reel so that necessary slippage may occur at this point whenever the roll of tape on the reel is of sumcient diameter that the reel tends to take up the tape faster than it is fed by the drive pulleys.

At such times slippage takes place between pads I02 and the hub of the reel.

Shaft 68 and the two reel shafts 83 are drivingly interconnected in such a manner that they all rotate in the same direction, For a left handed direction of rotation the left hand reel 84, which then functions as the take-up reel is driven and the right hand reel then functioning as the feed reel, will idle, while for a right handed direction of rotation, the right hand reel is driven and the left hand reel will die.

A slight friction drag is applied to each reel, in order to prevent the reel from overrunning while it is idling on its shaft, or in other words, while it is acting as the feed reel. In the present instance this friction drag element consists of a felt washer ing the underside of lower reel hub member 8|. 3 cup member III secured to deck I! around shaft 43 receiving the felt Washer and positioning it properly.

Bearing downwardly against the upper member 94 of the reel hub is a ring I I2 of a thrust bearing II3, the latter being carried by a disk I I4 on the lower end of a stud I I 5 which is screwthreadedly mounted in a supporting strap or bar 6. This bar II6 overlies the shaft of both reels, and is mounted at the center on a block II'I secured to deck II. Preferably, the nature of the mounting of the bar IIS on block III is such as to enable the bar to be conveniently disassembled; in the present instance. the bar is secured down to block ill by means of a screw II8 having a large knurled head 9. To mount the reels on the machine, the bar H5 is removed and the reels slipped on over the reel shaft 83. Bar IIB is then secured in place by means of screw II9,'and screw members II5 are next screwed downwardly through bar II5 to exert a downward pressure on the upper sides of the reels through thrust bearings II3, the adjustment being such that the reel is pressed downwardly against felt washer I III with sufficient force to give just the frictional drag required to avoid any tendency for overrunning of the reel. At the same time, the reel should not be pressed against washer IIll so tightly as to cause undue binding. The upper end of screw member H5 is preferably slotted, as at I2Il,- for reception of an adjusting tool, and a lock nut I2I screwed on member H5 and set down against bar II6 secures member H5 in adjusted position.

The steel record tape T is wound about the hubs of the two reels as illustrated. The ends of the tape may be secured to the hubs in any suitable or conventional manner; Figs. 7 and 8 show one simple arrangement, in which the two ends of the tape are provided with enlargements I30, which are received in drill holes I3I in the sides of the two reel hubs, an angular slot I32 extending between hole I3I and the periphery of the hub passing the end portion of the tape. It will be understood that the end portion of the tape is entered into hole I3I and slot I32 from the side of the hub.

As best illustrated in Fig. 1, the tape T is threaded from the reels around guide pulleys I35 mounted on deck I I1, and is then looped back around drive pulleys I36. The stretch of tape between the two drive pulleys I36 passes through or between the two halves of a recording head I38 containingthe translating magnets.

Figs. 2 and 5 show the driving arrangement for drive pulleys I36. Lower drive pulley I4 on shaft ii is connected by belt I31 with pulleys I38a set on the lower ends of, shafts I39 extending through deck I1 and on the upper ends of which the aforementioned drive pulleys I36 are mounted. Shaft I39 is shown in Fig. 5 to be journalled in a bushing I40 carried by a bearing member I 4| mounted on and extending through deck II. The pulley I36 i tightly mounted on a hub I42, and the latter is secured by set screw I43 onto the portion of shaft I 33 projecting above deck I1. The underside of hub I4! is supported by means of a thrust bearing I44 bearing downwardly on the upper end of bearing I4I.

' Drive pulleys I36 are thus driven from center drive shaft 66. To assure non-slipping driving engagement between the pulleys and the tape, the tape passing around each of said pulley is IIII surrounding shaft 83 and engag- I engaged by a pair of retainingrolls I50, which are spring-urged into pressural engagement against the tape. The rolls I50 are mounted on a carrier plate I5I, which has a guide slot I52 slidable on a stud I53 set into deck I1. Movement of plate I5I toward and from pulley I36 moves retaining rolls I50 into and out of engagement with the tape. Screws I55 mount rolls I50 on plate I5I,

and the lower ends of these screws engage deck riphery of pulley I36. Stud I56 is shaped to be v conveniently grasped by the fingers for movement of plate I5I in a direct-ion away from pulley I36 to permit threading of the tape around the pulley. When this stud is released, the retaining rolls I50 are pressed into engagement with the tape with sufiicient pressure to assure substantially nonslipping driving engagement between pulley and tape.

Magnet head I38 is preferably of the general type disclosed and claimed in my copending application entitled Sound head for magnetic recording machines, Ser. No. 170,985, filed October 25, 1937. This head embodies two rectangular insulation blocks I60 and I6I, the opposite sides of which are secured to mounting plates I62 and I63. A pair of headed pins I66 pass with sliding fit through plate I69 and block I6I and tightly engage block I60. Block IE1 is thus movable toward and from block I60 on pins I66, the opposing faces of the two blocks being in engagement when the device is in operating position; Preferably pins I64 have hinged joints I65 permitting block I6I to be swung away from block I60 after being pulled outwardly on pins I66. This opening arrangement is of great convenience in threading the recording tape between the two blocks and in inserting or removing the pole pieces contained in the magnets.

As here shown, the mounting plate I62 for block I60 is secured to deck I1 as by means of screws I66, while block I6I and its mounting plate I63 are adapted to be swung downwardly through an aperture I61 formed in deck i1 when the two halves of the device are opened for tape threading purposes (see Fig. 12). The opposing faces of blocks I60 and I6I ar formed with a longitudinally extending groove or way I10 adapted to receive and pass the recording tape. This way should be only sufficiently larger than the cross sectional size of the tape to permit the tape to be drawn freely therethrough.

Assuming that there are to be eight recording lanes on the magnetic tape, eight sets of recording or translating electromagnets I12 are mounted in laterally offset or staggered position in blocks I60 and I6I. Each of the magnets I121 comprises a wound magnetic bobbin I13 provided with a central aperture I14 of rectangular cross section for the magnetic pole piece I15.

The pole pieces I15 are of rectangular cross section, and are slidably mounted in apertures I14, their inner ends of tips being tapered to a width preferably slightly less in dimension than one-eighth the width of the tape. The pole pieces are also preferably beveled at the ends so that their dimensions at the tip are of the order of approximately .003 Inch. The outer ends of pole pieces I15 are engaged by plunger members I60 lightly pressed against them by springs I8I mounted in sockets I62 in plates I62 and I63, in the manner clearly illustrated-in Fig. 11.

The tips of each pair of pole pieces are thus lightly pressed into contact with opposite sides of the recording tape, but are of such dimensions as to contact only within the limited width 1ongitudinal lane area of the tape within which the individual pole pieces are to operate. It is to be understood that a multiplicity of recordings are intended to be made side by side on the single tape, either simultaneously or consecutively. These recordings do not substantially or noticeably afiect one another. and any one lane may be recorded on, reproduced, or erased (in a manner later to b explained), without efiecting recordings on adjacent lanes.

When the recordings made on the tape T are to be erased, the machine is re-threaded, in accordance with the diagram of Fig. 9, through an erasing magnet head I90. As a precautionary measure, in order to guard against the possibility of accidentally erasing a recording during a test flight, this erasing head is here shown as so positioned that the tape must be rethreaded through it in order to erase. Further, the erasing head is preferably demountable on the machine, so that it can simply be removed while recordings are being made. Thus, for erasing purposes, the tape is taken from the reels directly to the drive pulleys I36, and from the latter around the idler pulleys I35, the stretch of the tape between the latter being threaded between the two halves of erasing head I90, which is demountably positioned on deck I1 just inside head I36, and with its plane of separation in line with pulleys I35. The head I96 comprises insulation blocks I9! and Q92, backed up by mounting plates I93 and I96, plate I96 being provided with pins I95 adapted for removable insertion in deck I1, while block IN and plate I93 are slidable for opening and closing movement on pins I96 set into block I92. Blocks I9I and I92 are provided with three pairs of electromagnets I98, which will be understood to be of the same nature as the electro-magnets I12 shown fully in Fig. 11, the pole pieces I99 of magnets I98 being of sufficient width at the tip,

however, that the three pole piece tips cover the entire width of the tape. The blocks I9I and N2 will be understood to be formedwith a longi= tudinal guideway 290 for the tape, the same as in head I38. Numeral 20I designates connector prongs, through which, together with electrical connections within the block, not shown, electrical erasing current is delivered to the electromagnets. One of said contacts is utilized as a ground connection for conventional shielding means, not illustrated.

The electrical system is schematically shown in Fig. 14, to which reference is now directed. In Fig. 14, energizing circuits for the electric drive motor are shown, and the windings and associated circuits for the translating magnets of the bottom or main section of the machine are shown, it being understood that the translating magnets associated circuits for any added sec-s tions may be repetitions of those shown in Fig. 14. The electric drive motor for the tape driving pulleys is again indicated in Fig. 14 by numeral 55, being here shown as a series wound motor having a reversible field winding 55a. One power supply input lead 220 is connected directly to one side of the armature of the motor. The

other power supply lead 22| is connected to field winding 55:: through manual motor reversing switch 222. The other side of the armature of the motor is connected via lead 223 to the contacts 224 and 225 of a pair of normally closed limit switches S and S1. The other contacts 226 and 221 of said limit switches are connected by leads 228 and 229, respectively, to the outside stationary contacts 230 and 231 of motor reverse switch 222. Opposed to and between contacts 230 and 23| are contacts 232 and 233, respectively, and between the pairs of contacts 230 and 232 and 23|, 233 are movable switch arms 234 and 235, respectively. The arms 234 and 235 are adapted to stand in a neutral position, half way between the described pairs of contacts, or to be moved to position to make with contacts 230 and 233, respectively, or to position to make with contacts 232 and 23|, respectively. Contacts 232 and 233 are connected to power supply lead 22|, while switch arms 234 and 235 are connected by leads 231 and 238 across series motor winding 55a. It will be evident that when switch arms 234 and 235 are in intermediate or neutral position, the motor circuit will be open, and that by throwing switch arms 234 and 235 in either direction from neutral, the motor circuit will be closed. It will also be evident that the polarity of the field winding of the motor is reversed for opposite directions of throw of the switch arms, and the motor there fore turns in reverse directions for the two positions.

The above mentioned limit switches S and S1 are normally closed, and are automatically opened as the tape reaches the end limits of its travel in opposite directions. Suitable means for this purpose are shown in Figs. 1 and 2, to which attention is now directed. Bearing on the roll of tape on one of the reels, here the left hand reel as viewed in Fig. 1, is a roller 2|ll carried by a crank arm 2 supported by a shaft 2| 2 mounted for rotation in deck l1. shaft 2|2, below deck I 1, is a switch operating arm 2 I4, which are here shown carries adjustable screws 2|5 adapted to engage movable arms 2|6 and 211 of limit switches S and S1, respectively (see Fig. 2). A tension spring 2! connected to switch actuating arm 2l4 urges crank arm 2 and the roller I carried thereby toward the roll of tape on the corresponding reel 64, maintaining roller 2|0 in light pressural contact with the tape. When the tape is nearly wholly on the left hand reel 84, as viewed in Fig. l, crank arm 2 is swung outwardly to a position in which switch actuating arm 2| 4 engages switch arm 2" and moves it to open the contacts of switch S1. And when the tape has been reeled nearly wholly onto the right hand reel 84, as viewed in Fig. 1, crank arm 2 has swung inwardly toward the reel sufficiently far that switch actuating arm 2 has engaged switch arm 2| 6 and moved it to open the contacts of switch S. Thus, it will be understood that as the tape nears its extreme limits of travel in either direction, one or the other of limit switches S and S1 are automatically opened. The one of these switches that is so opened is in series with which ever of leads 228 and 229 is then carrying current to the motor armature, and the motor therefore immediately stops. The motor can then be energized to drive in the reverse direction by throwing motor reverse switch 222, which acts both to reverse the polarity of field winding 55a, and to supply current to the armature through the other limit switch, then understood to be closed.

Numeral 250 (Fig. 14) designates a tape footage meter, which may consist of an ordinary alvanometer or voltmeter. One terminal of this meter is connected to switch arm of a jack 252, arm 25| normally making with contact 253 connected to power supply lead 22I. One terminal of the meter is thus connectedto power supply lead 22L The other terminal of the meter is connected by lead 255 to the moving arm 256 of the winding 251 of a potentiometer P, lead 255 preferably including a resistor 258 of about 10,000 ohms. Potentiometer resistance 251 may be about 1,000 ohms. One terminal of potentiometer resistance 251 is connected by lead 258 to the first mentioned terminal of meter 250, that is, to that terminal of the meter which is connected to power supply lead 22|. The other terminal of potentiometer 251 is conected by lead 266 to the other power supply lead 220. Lead 250 preferably includes a resistor 26| of about 2,000 ohms, and an adjustable shunt 262 is arranged to short out a portion of resistor 26L Potentiometer P is also shown in Fig. 2, to

which attention is directed. This potentiometer On the lower end of l ply is connected to leads may be of an ordinary commercial type, having a rotatable shaft 265 understood to carry a movable arm which travels over a resistance winding. Such potentio-meters are well known, and need not be detailed herein. Potentiometer P is mounted below deck H in such a position that a spur gear 266 mounted on shaft 265 meshes with a larger spur gear 261 mounted on the aforementioned shaft 2|2 that carries crank arm 2| 1. The ratio of gears 266 and 261 is such that the moving arm of the potentiometer will sweep from one end of the resistance winding to the other as arm 2| moves between its limits of travel.

The meter 250 is connected across a portion of the resistance winding 25'! of potentiometer P. The reading of the meter will then vary with the movement of the potentiometer arm 256 along winding 25! as crank arm 2 moves between its limits of travel. The reading of the meter accordingly varies with the amount of tape on that reel with which the crank arm 2 is associated, and may therefore be calibrated in tape footage. The adjustable resistor at 26| is employed simply for the purpose of adjusting the zero setting of the motor, resistance 26| being adjusted to such a value that the meter will read zero footage when crank arm 2| is in its extreme outward position. It will of course be evident that the meter 253 may be calibrated for both directions of travel of the tape.

The power supply leads 229 and HI may be connected to either alternating or direct current power. However, the meter 250 requires direct current, and when an alternating source of sup- 220 and HI, a meter battery is utilized. This battery, not shown, is connected to a conventional switch board plug, also not shown, which is plugged into jack 252, thus connecting the battery across arms 25| and 25la, and opening the circuit from power lead 22| to the meter at 253. Jack arm 25|a is connected to lead 220, and it will be evident that the plugged in battery is then substituted as a source of voltage supply across the potentiometer P whose variable voltage drop is read by meter 250.

In addition to the footage meter, I preferably also provide a means for indicating tape speed. For this purpose, I show in Fig. 2 a generator 215 driven from motor 55 by means of belt 216. The voltage generated by this generator is proportional to the speed of motor 55, and therefore of beginning of a test run.

\ the tape. This voltage may of course be read with a suitable voltmeter, not shown.

The windings of the pairs of translating electromagnets I12 are connected to individual input circuits or channels 280, 281, 282, etc. These input circuits may be fed from any suitable source of electrical current whose voltage is to be recorded; as here typically shown, the input terminals of circuits 280, 28l, etc., are shown as connected to the output terminals of amplifiers A, to the input terminals of which are connected pick-up or input devices I. It will be understood that the devices I may be microphones designed to pick up speech or noise, or may be vibration pick-up devices adapted to generate a voltage proportional to a vibration, or any type of device or instrumentality which will produce or deliver a voltage or electrical current proportional to a sound, movement, etc.

Each of circuits 280, 261 etc., includes a series connected push button or other suitable type switch 290, and a shunt connected magnetshorting switch 29L The switches 290 areemployed to close the circuits to the translating magnets when it is desired to record. The switches 2! are all controlled by a single push button or other operating member, and by closing these switches simultaneously while the machine is in operation, all magnets are simultaneously shorted out, and a period of silence results which can be utilized as a convenient marker for the A pair of microphones 30B and 30! designed for speech input are adapted to be connected across selected input circuits 280, 28!, etc. These microphones 300 and 3M are connected into amplifiers 302 and 303, respectively. A four level gang selector switch 305 of conventional type is provided, the four rotary switch arms 306 of which will be understood to have a common operating shaft, not shown. Each switch arm sweeps over a plurality of circularly arranged contacts 1, 2, 3, etc., one for each of the input circuits 280, 28l, 282, etc. As shown in Fig. 14, the output leads from amplifier 302 are connected to the first and third switch arms 3lll6, which are arranged to make with corresponding contacts of the selector switch, and the output leads from amplifier 303 are connected to the second and fourth switch arms 306, which are arranged to make with corresponding contacts of the selector switch, but which, however, do not correspond to the contacts contacted by the first and third switch arms. Corresponding contacts of the first and second levels of the switch are interconnected, and are connected by leads am to one side of the'respective input circuits 280, 28l, etc. Corresponding contacts of the third and fourth levels of the switch are similarly interconnected, and are connected by leads 3 to the other side of the respective input circuits 280, 28l, etc. From an inspection of Fig. 14 it will be evident that the selector switch connects the two microphones 300 and 30! selectively across different pairs of the input circuits to the translating magnets.

The pairs of electromagnets I98 oi the demountable erasing magnet head I90 are connected in series, and the series connected pairs are connected in parallel across erasing current circuit 320, as shown in Fig. 14. This erasing current circuit is connected to any suitable source of erasing current, here the high frequency oscillator indicated at 32L Circuit 230 is shown as provided with a control switch 322.

The erasing magnet head I90 erases all recordlug across the entire width of the tape Addi-' tionally, there is preferably providedmeans for separately erasing recorded matter 'on'any given record lane. For this purpose, a two level gang selector switch 330 is provided, the two arms 33| of which are connected to the terminals of a jack 332 adapted to receive plug 333 connected to the output circuit of oscillator 32!. Arms 33! sweep over pairs of corresponding circularly arranged contacts I, 2, 3, etc., which are connected across the respective circuits 280, 28!, etc. When plug 333 is plugged into jack 332, switch 330 enables the erasing current delivered by oscillator 32l to be circulated through any selected pair of translating coils I12. A recording on. any individual lane or track of the tape may thus be erased, and this may be accomplished without affecting recordings on the remaining lanes or tracks. Moreover, the same magnets used for recording are in this instance used for erasing.

The recording system as now described has great flexibility, permitting the carrying out of a large number of different operations. A number of sound and vibration pick-up devices I may be connected to the terminals of the various input circuits 28B, 28l, etc., and, in the instance of flight testing of a plane, these pick-up devices may be located in various positions of interest about the plane. Records of the non-related voltages delivered by the several devices I may be made simultaneously, side by side, on the several lanes of the record tape.

If desired, a speech input microphone may be used as one of pick-up devices 1. Further, the microphones 300 and Gill may be switched across selected circuits 280, 28!, etc., and data dictated on the corresponding lane of the tape. Such dictated data may be superimposed on a record lane on which a noise or vibration record is simultaneously being made, or may be recorded ona record lane of the tape which is otherwise free. Assuming a time of one hour for running the tape through the machine, eight simultaneous recordings of one hour duration may be made simultaneously or, if a second recording section is mounted on the machine, sixteen such simultaneous recordings may be made.

In the event that one recording of extended time should be desired, by proper manipulation of switches 29d, the several input circuits may be used consecutively, giving a recording time of eight hours with a machine of one section, or a recording time of sixteen hours with two sections. In the event that speech only is to be recorded, either microphone 300 or 3! may be used, and if the lanes are used successively, eight or sixteen hours of speech may be recorded. As a further variational use, any pick-up device other than a microphone, such as a vibration pick-up device, may obviously be substituted for either of microphones 300 or 3!.

Recordings may be made with the tape travelling in either direction. For reproduction purposes, the terminals of circuits 280, 28l, etc., are simply connected to the input terminals of amplifiers, such as 340 (see Fig. 15) the output terminals of which may be connected to either a speaker 341, an oscillograph 342, or any other reproduction device, the remainder of the system remaining as before.

I have now illustrated and described in some detail one specific embodiment of my invention; it will be understood, however, that this is for illustrative purposes only, and that various changes in design, structure and arrangement may be ma without departing from the spirit and scope o the invention or of the appended claims.

I claim:'

erative relation to said tape and offset trans versely of the tape with respect to one another so as to act exclusively on adjacent longitudinally extending lanes of the tape, input circuits connected to said electromagnet means, and switching means whereby said circuits may'be used to carry electrical currents either simultaneously or successively.

2. In a magnetic recording system, the combination of a flat magnetizable tape, means for longitudinally driving said tape in reverse directions, a plurality of recording electromagnet means mounted in operative relation to said tape and offset transversely of the tape with respect to one another so as to-act exclusively on adjacent longitudinally extending lanes of the tape, a corresponding plurality of input circuits, and switching means for connecting all input circuits or any selected circuit or electromagnet means.

3. In a magnetic recording system, the combination of a fiat magnetizable tape, means for longitudinally driving said tape, a plurality of recording electromagnet means mounted in operative relation to said tape and offset transversely of the tape with respect to one another so as to act exclusively on adjacent longitudinally extending lanes of the tape, individual input channels connected to said electromagnet means, a source of erasing current, and means for selectively connecting said source of erasing current to any one of said input channels.

4. In a recording and/or reproducing system, the combination of a fiat record tape, means for longitudinally driving said tape in reverse directions, a plurality of translating means cooperable with transversely offset lanes of the record tape, individual electric current channels for said translating means, and switching means for connecting all input channels or any selected chan-' he] or channels to respective translating means.

5. In a recording machine, the combination of a frame, a drive motor on said frame, a pair of reels for a record tape, supporting means for said reels on said frame, means on said frame for guiding the record tape from one of said reels to the other, recording means on said frame operable on the tape between said reels, reel driving means on said frame for driving either of said reels fromsaid drive motor, a second frame demountably supported on the first frame, a second pair of reels for a second record tape, supporting means for said second tape on said second frame, means on said second frame for guiding said second tape between said second pair of reels, recording means on said second frame operable on the second record tape between the reels for said tape, and driving -means for said second reels on said second frame disengageably connected with said reel driving means on said first frame.

6. In a recording machine, the combination of a frame, a drive motor on said frame, a pair of reels for a record tape, supporting means for said reels on said frame, means on said frame for guiding the record tape from one of said reels circuits torespective to the other, recording means on said frame operable on the tape between said reels, reel driving means on said fram for driving either of said reels from said drive motor, a second frame demountably supported on the first frame, a second pair of reels for a second record tape, supporting means for said second tape on said second frame, means on said second frame for guiding said second tape between said second pair of reels. recording means on said second frame operable on the second record tape between the reels for said tape, and driving means for said second reels on said second frame operatively disengageably connected with the driving motor on the first frame.

7. In a recording machine, the combination of a frame plate, a drive motor mounted on one side of said frame plate, reel supporting means on said frame plate forlsupporting a pair of reels on the opposite side of said plate, reels on said reel supporting means, means for guiding a record tape between said reels, recording means operable on the tape between said'ree reel driving means on said frame plate for driving either of said reels from said drive motor, a second frame plate demountably supported on the first frame plate in parallelism therewith and on said opposite side of said first frame plate, reel supporting means on said second frame plate for supporting a pair of'reels on the side of said second frame plate that faces away from said first frame plate, reels on said reel supporting means, means for guiding a second record tape between said reels, recording means operable on the tape between said reels, and reel driving means on said second frame plate disengageably connected with said reel driving means on said first mentioned frame plate.

8. In a recording machine, the combination of a frame plate, a drive motor mounted on one either of said reels from said drive motor, av

second frame plate demountably supported on the first frame plate in parallelism therewith and on said opposite side of said first frame plate, reel supporting means on said second frame plate for supporting a pair of reels on the side of said second frame plate that faces away from said first fram plate, reels on said reel supporting means, means for guiding a second record tape between said reels, recording means operable on the tape between said reels, and reel driving means on said second frame plate disengageably connected with the driving motor on the first frame plate.

9. In a recording machine, the combination of a frame, a drive motor on said frame, reel supporting means on said frame for supporting a pair of reels, reels for a record tape on said reel supporting means, recording means on said frame operable on the tape between said reels,

a tape driving pulley supported on said frame and operating on the tape between said reels, pulframe demountably supported on the first frame, reel supporting means on said second frame for supporting a second pair of reels, reels for a second record tape on said reel supporting means, recording means on said second frame operable on said second tape between the second mentioned reels, a tape driving pulley supported on said second frame and operating on said second tape between said reels, pulley drive means for driving the last mentioned pulley disengageably connected with the driving means for the first pulley, and reel take-up means on the second frame drivingly interconnecting said last mentioned pulley drive means with whichever of the two reels is acting as take-up reel for the direction the tape is then travelling.

10. In a recording machine, the combination of a horizontal frame plate, a drive motor mounted on the underside of said frame plate, a pair of vertical reel shafts mounted on said plate, reels for a record tape on said shafts, recording means on the upper side of said frame plate operable on the tape between said reels, a main drive shaft driven from said motor projecting vertically through and mounted for rotation in said frame plate, a drive pulley for said tape mounted above said frame plate and driven by said main drive shaft, reel take-up means on said frame plate drivingly interconnecting said main drive shaft driving whichever with whichever of th take-up reel for the travelling, a second mountably supported on and above the first mentioned frame plate, a pair of vertical reel shafts mounted on said second frame plate, reels for a second record tape on said shafts, recording means on the upper side of said second frame plate operable on the tape between the last mentioned reels, a drive pulley for said second tape mounted above said second frame plate, reel take-up means on said second frame plate for of the two reels is acting as take-up reel for the direction the tape is then travelling, and means drivingly engaging said main drive shaft with said tape drive pulley and said reel take-up means of said second frame plate when said second frame plate is mounted on the first mentioned frame plate.

11. In a magnetic recording machine, the combination of a frame, two reels for a record tape rotatably mounted on said frame, means for advancing the tape, recording magnet means on said frame, erasing magnet means on said frame, and means acting on the'tape between the two reels for guiding said tape either past said recording magnet means, or past said erasing magnet means.

two reels is acting as the direction the tape is their;

HERMAN S, I-IELL'ER.

horizontal frame plate de-'

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