US20100284105A1 - Apparatuses and methods for pre-erasing during manufacture of magnetic tape - Google Patents

Apparatuses and methods for pre-erasing during manufacture of magnetic tape Download PDF

Info

Publication number
US20100284105A1
US20100284105A1 US12/773,544 US77354410A US2010284105A1 US 20100284105 A1 US20100284105 A1 US 20100284105A1 US 77354410 A US77354410 A US 77354410A US 2010284105 A1 US2010284105 A1 US 2010284105A1
Authority
US
United States
Prior art keywords
servo
head
magnetic tape
pattern
erase
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US12/773,544
Inventor
Matthew P. Dugas
Theodore A. Schwarz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to US12/773,544 priority Critical patent/US20100284105A1/en
Publication of US20100284105A1 publication Critical patent/US20100284105A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/008Recording on, or reproducing or erasing from, magnetic tapes, sheets, e.g. cards, or wires
    • G11B5/00813Recording on, or reproducing or erasing from, magnetic tapes, sheets, e.g. cards, or wires magnetic tapes

Definitions

  • the present invention relates to apparatuses and methods for use in the manufacture of magnetic tape.
  • the present invention relates to apparatuses and methods for pre-erasing a servo channel of a magnetic tape.
  • Magnetic tape as a data storage medium requires the ability to effectively write and read data to data tracks of the magnetic tape; many such data tracks typically extend linearly along the length of tape and, in part, define tape data storage density.
  • servo tracks which also extend linearly along the length of tape are commonly used. Servo tracks are typically written in such a way as to span the tape in an efficient manner that maximizes the number of data tracks and minimizes the number of servo tracks for a given tape system.
  • a servo track contains servo data and is read by a servo read head. This information is used to determine the relative position of the servo read head with respect to the magnetic media in a translating direction (i.e., movement across the width of the tape). This is also called the cross track direction.
  • a translating direction i.e., movement across the width of the tape. This is also called the cross track direction.
  • apparatuses and methods of manufacture to create a servo channel that enables the servo data to be read more effectively would be helpful.
  • the present invention addresses apparatuses and methods to improve a servo control system.
  • the present invention relates to direct current (“DC”) pre-erasing servo channels of a magnetic tape prior to writing servo data in a servo channel.
  • the present invention particularly relates to those servo recordings which were written with a uni-polar current waveform.
  • the DC pre-erase is performed using a uni-polar direct current of a polarity that is opposite to the polarity of the direct current used to write the servo data.
  • This pre-erase may be done with one or more heads.
  • the pre-erase of a servo channel and writing to a servo channel may be done by making two passes over a single head or by using two or more heads to perform both steps.
  • the present invention relates to a magnetic tape comprising a substrate and a magnetic layer, the magnetic tape having at least one direct current pre-erased servo channel that includes servo data.
  • the present invention relates to a magnetic tape having at least one servo channel that is direct current pre-erased and has servo data written in the at least one servo channel.
  • the magnetic tape is made by a method comprising writing a servo pattern using a uni-polar direct current of a particular pulse train. Prior to writing a servo pattern, erasing the servo channel of the magnetic tape by applying a direct current of a substantially opposite polarity to that of the servo write current pulse sequence.
  • the present invention also relates to an apparatus for use in pre-erasing magnetic tape, comprising a housing supporting at least two heads, wherein at least one of the two heads includes a gap pattern to direct current pre-erase the servo channels on the magnetic tape, wherein the other of the two heads includes a gap pattern for recording the servo channel that is written after the pre-erase has been first recorded.
  • the present invention further relates to an apparatus for use in pre-erasing magnetic tape, comprising a compound substrate having at least a first substrate and a second substrate, wherein the first substrate includes at least one servo pattern and the second substrate includes at least one direct current pre-erase pattern.
  • FIG. 1 shows a typical servo track and data track organization on the tape.
  • FIG. 2 is a schematic drawing of one embodiment of the present invention showing a housing supporting two heads with magnetic tape extending over the heads, where one of the heads is used to pre-erase with direct current the servo channels of a magnetic tape and the other is used to record the servo pattern onto the pre-erase servo channels.
  • FIG. 3 is a schematic drawing of one embodiment of the present invention showing a housing supporting one head with the magnetic tape extending over the head, where the head is used to pre-erase with direct current the servo channels of a magnetic tape.
  • FIG. 4 shows an exemplary servo erase gap pattern on the surface of a surface film head.
  • FIG. 5 shows an exemplary servo gap pattern on the surface of a surface film head that may be used to write a servo pattern in the servo channel on a magnetic tape.
  • FIG. 6 shows a two head configuration in which one head has a gap pattern that would be used to DC pre-erase the servo channel and the other head has a timing based servo gap pattern that would write a timing based pattern onto the servo channel on a magnetic tape.
  • FIG. 7 shows a close-up of the patterns shown in FIG. 6 . Note that the patterns are matched so that the erase track width is substantially the same as the servo track width.
  • FIGS. 8A-8B show a portion of a magnetic layer and substrate of a magnetic tape and a theoretical output signal from a servo pattern on a magnetic tape in which the tape and servo channel have been AC erased.
  • FIGS. 8C-8D show a portion of a magnetic layer and substrate of a magnetic tape and a theoretical output signal from a servo pattern on a magnetic tape in which the servo channel has been DC erased prior to recording the servo signal.
  • FIGS. 9A and 9B show theoretical waveforms for relating the magnetoresistive (MR) response curve of the head, an input field from the magnetic tape, and an output voltage signal from the MR head element.
  • MR magnetoresistive
  • FIG. 10 shows a two head configuration in which one head is a ferrite MIG head having a gap pattern that would be used to DC pre-erase the servo channel and the other head is a surface thin film head using the low inductance, ferrite sub-gap substrate having a timing based servo gap pattern that would write a timing based pattern onto the servo channel on a magnetic tape.
  • FIG. 11 shows an embodiment of the present invention using a compound substrate.
  • FIG. 12 is a schematic drawing of one embodiment of the present invention showing a first housing supporting one head with the magnetic tape extending over the head, where the head is used to pre-erase with direct current the servo channels of a magnetic tape and a second housing supporting one head with magnetic tape extending over the head, where the head is used to write servo data in the servo channel of the magnetic tape.
  • the present invention relates to apparatuses and methods used in manufacturing magnetic tape.
  • the present invention relates to manufacture of magnetic tape that includes servo data in one or more servo channels, where one or more servo channels has been pre-erased with a uni-polar signal prior to the servo data being written in a servo channel.
  • Pre-erasing a servo channel with direct current enables the servo read signal representing the uni-polar written servo pattern to be stronger than a servo read signal in a similar servo channel that is not pre-erased.
  • pre-erasing the servo channel during the manufacture and formatting of the magnetic tape will provide benefits by increasing the signal to noise ration of the servo read signal.
  • FIG. 1 shows a magnetic tape 10 having data bands or data tracks 12 (also, may be referred to as data channels) and servo bands or servo tracks 14 (also may be referred to servo channels).
  • the data tracks 12 would be the portion of tape 10 to which data elements 16 would be written and from which data elements 16 would be read.
  • servo tracks 14 would include servo data 18 which are written into the servo track during manufacture of the magnetic tape 10 .
  • This servo data 18 is used by the servo control system to help properly position the read and write heads with respect to the data tracks 12 .
  • the present invention relates to pre-erasing servo tracks 14 with a direct current or uni-polar pre-erase signal prior to writing a uni-polar servo pattern of the opposite polarity in the servo track 14 .
  • the servo channels 14 of a magnetic tape 10 are pre-erased by applying a uni-polar, direct current erase signal through a precise gap pattern in the head.
  • a uni-polar servo pattern is then written upon the pre-erased servo channel but in the opposite polarity.
  • the servo pattern may be timing based or amplitude based or a combination of both.
  • the present invention will typically be used with a time based pattern as timing patterns are typically uni-polar and amplitude patterns are typically bi-polar.
  • the technique is less effective in increasing the signal-to-noise (“SNR”) of the servo read system.
  • the DC pre-erase and the writing of a servo pattern may be accomplished using two or more heads or using one head.
  • a portion of the magnetic tape 10 is first passed over a head to perform a DC erase of servo channels 14 of the magnetic tape 10 and then another head is used to write a servo pattern into the servo channels 14 of the magnetic tape 10 .
  • the same head may be used to perform a DC erase of the servo channels 14 on a magnetic tape 10 and then to write a servo pattern in the servo channels 14 of the magnetic tape 10 . That is, in this embodiment, the magnetic tape 10 is passed over the head to perform a DC erase of the servo channels 14 . A pulse is applied through the pattern in the head to DC erase the servo channels 14 of the magnetic tape 10 . Then, the tape 10 is passed over the head a second time to write a servo pattern into the servo channels 14 of the magnetic tape 10 .
  • each head is used and are mounted into a housing so that an efficient one pass servo formatting system may be used. This embodiment is shown in FIG. 2 .
  • each head may be separately supported by a separate housing or even a separate tape deck (as shown in FIG. 12 ).
  • FIG. 2 shows a housing 20 with magnetic tape 10 extending across the two heads 22 , 22 ′.
  • the embodiment includes a housing 20 that supports a first head 22 and a second head 22 ′.
  • the heads have a first surface 24 , 24 ′, a second surface 26 , 26 ′, a first side surface 28 , 28 ′, and a second side surface 30 , 30 ′.
  • the first surface 24 , 24 ′ is in contact with the magnetic tape 10 .
  • the second surface 26 , 26 ′ of the heads is attached to and supported by the housing 20 .
  • the heads 22 , 22 ′ are mounted to the housing an epoxy. However, the heads may be mounted using any suitable means.
  • the heads 22 and 22 ′ are disposed side-by-side separated by a predetermined distance L. As shown in FIG. 2 , in one embodiment, the heads 22 and 22 ′ are spaced apart approximately 1.0 millimeters (“mm”) around the top edge 29 , 29 ′ (i.e., toward the first surface 24 ) and spaced apart approximately 0.80 mm at the bottom edge 31 , 31 ′ (i.e., toward the second surface 26 ). It will be appreciated that while the distance between the heads is specified, other distances may be used. Similarly, the angle A formed between the two heads may be varied and even flat contours may be used. While FIG.
  • the heads 22 and 22 ′ may be spaced in such a manner that the sides 30 , 28 ′ of the first and second heads 22 and 22 ′ are substantially parallel to each other in the vertical direction as shown.
  • any type of head may be used in the dual head configuration including, but not limited to thin film heads, ferrite based heads, and surface thin film heads.
  • the first and second heads 22 and 22 ′ may be heads with low inductance, ferrite sub-gap substrate surface film head structures of the type described in U.S. Pat. No. 6,496,328, which is hereby incorporated by reference in its entirety, a surface thin-film head of the type disclosed in U.S. Pat. No. 6,269,533, which is hereby incorporated by reference in its entirety, or a ferrite metal-in-gap (“MIG”) head.
  • MIG ferrite metal-in-gap
  • Any combination of these types of heads may be used when using two or more head in implementing an embodiment of the present invention. It will be noted that one head will be optimized as an erase head and the other head will be optimized as a servo write head.
  • a ferrite MIG head or a surface thin film head with a pattern would be used to perform the DC erase and a surface thin film head using the low inductance, ferrite sub-gap substrate surface film head with a time base servo pattern would be used to write a servo pattern on the servo channel of the magnetic tape.
  • FIG. 10 shows a ferrite MIG head with a pre-erase gap 46 to perform a DC erase with a surface thin film head having gap for an amplitude or a time based servo pattern for writing to a servo channel 14 .
  • the width of the pre-erase gap is substantially the same as the width of the servo pattern.
  • the housing 20 may be formed from any appropriate material including metal.
  • the housing 20 is milled to position the heads 22 , 22 ′ to the housing.
  • FIG. 2 shows a housing that includes two heads, a housing having more than two heads is within the scope of the present invention.
  • FIG. 3 shows a housing mount 20 that has a first head 22 .
  • This embodiment may be used when the heads for performing the DC pre-erase on the servo channels 14 and writing the servo patterns on the servo channels 14 are located on different tape decks or this embodiment may be used when the same head is used to perform both the DC erase on one pass and write the servo data 18 on the servo track 14 on a second pass.
  • FIG. 3 shows a housing mount 20 that has a first head 22 . This embodiment may be used when the heads for performing the DC pre-erase on the servo channels 14 and writing the servo patterns on the servo channels 14 are located on different tape decks or this embodiment may be used when the same head is used to perform both the DC erase on one pass and write the servo data 18 on the servo track 14 on a second pass.
  • FIG. 1 shows a housing mount 20 that has a first head 22 .
  • FIG. 12 shows a first housing 20 supporting a first head 22 with the magnetic tape 10 extending over the head 22 , where the head is used to pre-erase with direct current the servo channels 14 of a magnetic tape 10 and a second housing 20 ′ supporting a second head 22 ′ with magnetic tape 10 extending over the second head 22 ′, where the second head 22 ′ is used to write servo data in the servo channel 14 of the magnetic tape 10 .
  • FIG. 11 shows an alternative embodiment that may be used for more precise pattern combinations than a mechanically assembled dual module head pair.
  • FIG. 11 shows a compound substrate 80 .
  • the compound substrate 80 has a first substrate 81 and a second substrate 83 .
  • the first and second substrates 81 and 83 are spaced apart a predetermined distance L by use of a first block 85 to separate the substrates.
  • the first substrate includes a pre-erase gap 46 to DC erase a servo channel and the second substrate includes a servo pattern that is written in the DC pre-erased servo channel.
  • the pre-erase gap is ideally substantially the same width at the servo pattern.
  • the pre-erase gap may have a slightly larger width than the width of the servo pattern.
  • the first block 85 separating the compound substrate may be formed with ceramic. However, other materials may be used to separate the substrates.
  • the substrates may be joined together using epoxy.
  • FIG. 11 shows a compound substrate 80 having a combination of a surface thin film head (of the type described in U.S. Pat. No. 6,269,533) and a low inductance surface thin film head (of the type described in U.S. Pat. No. 6,496,328). Also, while two substrates are joined together in FIG. 11 , a compound substrate having more than two substrates is within the scope of the present invention.
  • the compound substrate in FIG. 11 may have all the gaps lithographically printed by a single mask and hence all patterns printed on those sub-gaps will have lithographic precision to the order of 0.1 microns or better. Hence, the compound substrate module may be used for more precise pattern combinations than a mechanically assembled dual module head pair.
  • FIGS. 2 and 3 may contain various servo patterns where one of the patterns is for performing a DC pre-erase of a servo track 14 .
  • FIG. 4 shows an exemplary servo erase gap pattern on the surface of a surface film head. While the servo head itself of FIG. 5 may be used to pre-erase the tape 10 this would require a two pass operation which would be time inefficient. However that would be within the scope of the present invention.
  • FIG. 4 shows an exemplary servo erase gap pattern on the surface of a surface film head.
  • the servo erase gap pattern 32 includes a first termination 34 and a second termination 36 .
  • the terminations 34 , 36 may have curved portions. As shown in FIG. 4 , the terminations 34 and 36 are circular.
  • FIG. 5 shows an exemplary servo gap pattern on the surface of a surface film head that may be used to write a servo pattern in the servo channel 14 on a magnetic tape 10 .
  • FIG. 5 shows a servo gap pattern 38 that is time based.
  • the servo gap pattern 38 has a first portion 40 and a second portion 40 ′, with each portion 40 , 40 ′ having a first termination 42 , 42 ′ and a second termination 44 , 44 ′.
  • the terminations 42 , 42 ′, 44 , 44 ′ have curved portions, and as shown, have circular terminations. It will be appreciated that other types servo patterns may be used without departing from the scope of the present invention.
  • FIG. 6 shows a two head configuration in which one head has a gap pattern 32 that would be used to DC pre-erase the servo channel and the other head has a timing based servo gap pattern 38 that would write a timing based pattern onto the servo channel on a magnetic tape 10 .
  • FIG. 7 shows a close-up of the patterns shown in FIG. 6 . Note that the patterns are matched so that the erase gap track width is substantially the same as the servo gap track width. Such a configuration would allow the entire servo track 14 to be DC erased
  • FIGS. 4-6 show each head having five patterns that may be used to perform a DC pre-erase. Such heads may have the same number of patterns to perform a pre-erase as the number of servo channels or servo tracks 14 contained on the magnetic tape 10 .
  • FIG. 8A shows magnetic tape 10 with servo track 14 , wherein the servo track 14 has been AC erased but not DC erased.
  • the magnetic tape 10 has a magnetic layer 11 and a substrate 13 .
  • the “M” stands for magnetization and shows that a portion 19 of the servo channel 14 is magnetized (e.g., by the writing of servo data).
  • FIG. 8B shows the input signal 50 from a tape 10 as read by a read head of the servo pattern 14 in such a condition.
  • the amplitude B indicates, at least in part, the strength of the signal 50 .
  • FIG. 8C shows magnetic tape 10 with servo track 14 , wherein the servo track has been DC erased in accordance with the present invention.
  • the servo channel 14 has be magnetized by the written servo data.
  • the portion of the servo channel adjacent the servo data has been DC pre-erased.
  • FIG. 8D shows the input signal 52 from the tape 10 as read by the servo read head in such a condition.
  • the amplitude C indicates the strength of the input signal 52 from the DC pre-erased servo channel is theoretically greater than the input signal 50 from the servo channel that was not DC pre-erased.
  • a DC pre-erased channel in theory, would provide a servo read voltage signal twice as strong as an input signal from a servo channel that has not been DC pre-erased but which had been randomly erased.
  • FIGS. 9A and 9B show a theoretical response curve 70 of the MR stripe, a theoretical input signal from a tape 71 and a theoretical output voltage 72 .
  • the response curve 70 includes a peak 73 and a portion that approximates a linear region 74 .
  • the angel .phi. being the angle between the resultant magnetization vector of the MR stripe and the applied current direction in the stripe. (.delta..rho./.rho.) is called the magnetoresistive coefficient of the material that makes up the stripe.
  • the output voltage should correspond to a waveform shown in FIG. 9A in which the input signal is within the linear region of the response curve.
  • FIG. 9B when the output voltage has a “rabbit ears” 75 , that the input signal extends outside the linear region and, as shown, to the negative slope of there response curve.
  • the DC pre-erase must be such that the signal output remains within the liner region of the response curve.
  • the present invention when used appropriately allows for greater voltages of the input signal while still remaining in the linear region of the response curve.
  • the MR read sensor output voltage is a function of the thickness of the magnetic tape.
  • the tape thickness is generally decreased to maintain magnetic bit cell stability.
  • the servo read signals may need to be increased as tape thickness decreases.
  • performing a DC pre-erase of a servo channel enables a stronger signal to be read without going into the non-linear region of the MR read elements response curve.
  • a dual head system consisting of a servo write head and servo DC erase head would be used in making magnetic tape.
  • the servo DC erase will erase only that part of the medium upon which will be recorded the servo format signal.
  • the DC erase head track widths and the servo format head track widths would be the same and they would be matched up within certain engineering tolerances. That is, the magnetic tape would only be DC erased in the servo track region and not in the data track regions. This is because data zones should remain ideally AC erased so that the subsequent data written thereupon will have the highest possible signal-to-noise ration and the data will not be biased by the underlying DC erasure.
  • the magnetic tape During manufacture, the magnetic tape would move in a transducing direction over the heads.
  • the servo channel of the magnetic tape is first pre-erased, and then a servo pattern is written in the servo channel 14 (see FIG. 1 ).
  • the resulting magnetic tape 10 would have a pre-aligned magnetization of the opposite polarity to that of the servo signal.
  • the dual module head system on one mount, the dual heads on separate individual mountsor the compound substrate head may be used to enable this concept.
  • This concept can apply to timing based servo systems, amplitude based systems or a combination of both in some more advanced servo system.
  • the concept will be most effective when the servo write system is uni-polar in nature and when the DC pre-erase is made using the opposite polarity.

Abstract

The present invention relates to direct current (“DC”) pre-erasing servo channels of a magnetic tape prior to writing servo data in a servo channel. The present invention particularly relates to those servo recordings which were written with a uni-polar current waveform. The DC pre-erase is performed using a uni-polar direct current of a polarity that is opposite to the polarity of the direct current used to write the servo data. This pre-erase may be done with one or more heads. Also, as will be described, the pre-erase of a servo channel and writing to a servo channel may be done by making two passes over a single head or by using two or more heads to perform both steps. Also, it is within the scope of the present invention to have the heads mounted on a single mount or have the heads on separate mounts and on separate tape decks.

Description

    CROSS-REFERENCE TO RELATED APPLICATIONS
  • This application is a divisional of U.S. patent application Ser. No. 11/838,006, filed on Aug. 13, 2007, which is a continuation of U.S. patent application Ser. No. 10/768,719, filed on Jan. 30, 2004, issued as U.S. Pat. No. 7,283,317, the contents of each of which are incorporated herein by reference.
  • TECHNICAL FIELD
  • The present invention relates to apparatuses and methods for use in the manufacture of magnetic tape. In particular, the present invention relates to apparatuses and methods for pre-erasing a servo channel of a magnetic tape.
  • BACKGROUND OF THE INVENTION
  • Magnetic tape as a data storage medium requires the ability to effectively write and read data to data tracks of the magnetic tape; many such data tracks typically extend linearly along the length of tape and, in part, define tape data storage density. In addition, for providing a controlled movement of tape reading and/or writing heads with respect to the data track, servo tracks, which also extend linearly along the length of tape are commonly used. Servo tracks are typically written in such a way as to span the tape in an efficient manner that maximizes the number of data tracks and minimizes the number of servo tracks for a given tape system.
  • A servo track contains servo data and is read by a servo read head. This information is used to determine the relative position of the servo read head with respect to the magnetic media in a translating direction (i.e., movement across the width of the tape). This is also called the cross track direction. To improve positioning of the tape reading and/or writing heads on a magnetic tape, apparatuses and methods of manufacture to create a servo channel that enables the servo data to be read more effectively would be helpful. The present invention addresses apparatuses and methods to improve a servo control system.
  • BRIEF SUMMARY OF THE INVENTION
  • The present invention relates to direct current (“DC”) pre-erasing servo channels of a magnetic tape prior to writing servo data in a servo channel. The present invention particularly relates to those servo recordings which were written with a uni-polar current waveform. The DC pre-erase is performed using a uni-polar direct current of a polarity that is opposite to the polarity of the direct current used to write the servo data. This pre-erase may be done with one or more heads. Also, as will be described, the pre-erase of a servo channel and writing to a servo channel may be done by making two passes over a single head or by using two or more heads to perform both steps. Also, it is within the scope of the present invention to have the heads mounted on a single mount or have the heads on separate mounts and on separate tape decks.
  • In one embodiment, the present invention relates to a magnetic tape comprising a substrate and a magnetic layer, the magnetic tape having at least one direct current pre-erased servo channel that includes servo data.
  • In another embodiment, the present invention relates to a magnetic tape having at least one servo channel that is direct current pre-erased and has servo data written in the at least one servo channel.
  • The magnetic tape is made by a method comprising writing a servo pattern using a uni-polar direct current of a particular pulse train. Prior to writing a servo pattern, erasing the servo channel of the magnetic tape by applying a direct current of a substantially opposite polarity to that of the servo write current pulse sequence.
  • The present invention also relates to an apparatus for use in pre-erasing magnetic tape, comprising a housing supporting at least two heads, wherein at least one of the two heads includes a gap pattern to direct current pre-erase the servo channels on the magnetic tape, wherein the other of the two heads includes a gap pattern for recording the servo channel that is written after the pre-erase has been first recorded.
  • The present invention further relates to an apparatus for use in pre-erasing magnetic tape, comprising a compound substrate having at least a first substrate and a second substrate, wherein the first substrate includes at least one servo pattern and the second substrate includes at least one direct current pre-erase pattern.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 shows a typical servo track and data track organization on the tape.
  • FIG. 2 is a schematic drawing of one embodiment of the present invention showing a housing supporting two heads with magnetic tape extending over the heads, where one of the heads is used to pre-erase with direct current the servo channels of a magnetic tape and the other is used to record the servo pattern onto the pre-erase servo channels.
  • FIG. 3 is a schematic drawing of one embodiment of the present invention showing a housing supporting one head with the magnetic tape extending over the head, where the head is used to pre-erase with direct current the servo channels of a magnetic tape.
  • FIG. 4 shows an exemplary servo erase gap pattern on the surface of a surface film head.
  • FIG. 5 shows an exemplary servo gap pattern on the surface of a surface film head that may be used to write a servo pattern in the servo channel on a magnetic tape.
  • FIG. 6 shows a two head configuration in which one head has a gap pattern that would be used to DC pre-erase the servo channel and the other head has a timing based servo gap pattern that would write a timing based pattern onto the servo channel on a magnetic tape.
  • FIG. 7 shows a close-up of the patterns shown in FIG. 6. Note that the patterns are matched so that the erase track width is substantially the same as the servo track width.
  • FIGS. 8A-8B show a portion of a magnetic layer and substrate of a magnetic tape and a theoretical output signal from a servo pattern on a magnetic tape in which the tape and servo channel have been AC erased.
  • FIGS. 8C-8D show a portion of a magnetic layer and substrate of a magnetic tape and a theoretical output signal from a servo pattern on a magnetic tape in which the servo channel has been DC erased prior to recording the servo signal.
  • FIGS. 9A and 9B show theoretical waveforms for relating the magnetoresistive (MR) response curve of the head, an input field from the magnetic tape, and an output voltage signal from the MR head element.
  • FIG. 10 shows a two head configuration in which one head is a ferrite MIG head having a gap pattern that would be used to DC pre-erase the servo channel and the other head is a surface thin film head using the low inductance, ferrite sub-gap substrate having a timing based servo gap pattern that would write a timing based pattern onto the servo channel on a magnetic tape.
  • FIG. 11 shows an embodiment of the present invention using a compound substrate.
  • FIG. 12 is a schematic drawing of one embodiment of the present invention showing a first housing supporting one head with the magnetic tape extending over the head, where the head is used to pre-erase with direct current the servo channels of a magnetic tape and a second housing supporting one head with magnetic tape extending over the head, where the head is used to write servo data in the servo channel of the magnetic tape.
  • DETAILED DESCRIPTION
  • The present invention relates to apparatuses and methods used in manufacturing magnetic tape. In particular, the present invention relates to manufacture of magnetic tape that includes servo data in one or more servo channels, where one or more servo channels has been pre-erased with a uni-polar signal prior to the servo data being written in a servo channel. Pre-erasing a servo channel with direct current enables the servo read signal representing the uni-polar written servo pattern to be stronger than a servo read signal in a similar servo channel that is not pre-erased. As such, pre-erasing the servo channel during the manufacture and formatting of the magnetic tape will provide benefits by increasing the signal to noise ration of the servo read signal. This in turn can lead to higher areal data storage densities for the magnetic tape. However, it is important to note that the response of a magnetoresistive (“MR”) head to this technique may be too strong and result in distortion and non-linear servo read signals. Hence this technique is to be used when the media thickness and M.sub.rt ratio has become smaller in more aggressive higher density products and when using such a technique will not overdrive the MR servo read head. Since the result of this technique is to increase the servo read signal, it is important to not use it if it will send the read head into a non-linear response region. On the other hand, as areal densities are ever increasing and typically accompanying this the M.sub.rt ratio is decreasing, the use of this technique may prove beneficial in certain servo systems as tape thicknesses continue to decrease.
  • FIG. 1 shows a magnetic tape 10 having data bands or data tracks 12 (also, may be referred to as data channels) and servo bands or servo tracks 14 (also may be referred to servo channels). The data tracks 12 would be the portion of tape 10 to which data elements 16 would be written and from which data elements 16 would be read. Similarly, servo tracks 14 would include servo data 18 which are written into the servo track during manufacture of the magnetic tape 10. This servo data 18 is used by the servo control system to help properly position the read and write heads with respect to the data tracks 12. The present invention relates to pre-erasing servo tracks 14 with a direct current or uni-polar pre-erase signal prior to writing a uni-polar servo pattern of the opposite polarity in the servo track 14.
  • In the preferred embodiment, only the servo channels 14 of a magnetic tape 10 are pre-erased by applying a uni-polar, direct current erase signal through a precise gap pattern in the head. A uni-polar servo pattern is then written upon the pre-erased servo channel but in the opposite polarity. The servo pattern may be timing based or amplitude based or a combination of both. However, the present invention will typically be used with a time based pattern as timing patterns are typically uni-polar and amplitude patterns are typically bi-polar. On bi-polar current written or recorded servo channels 14, the technique is less effective in increasing the signal-to-noise (“SNR”) of the servo read system.
  • In manufacturing magnetic tape 10, the DC pre-erase and the writing of a servo pattern may be accomplished using two or more heads or using one head. For instance, in one embodiment, a portion of the magnetic tape 10 is first passed over a head to perform a DC erase of servo channels 14 of the magnetic tape 10 and then another head is used to write a servo pattern into the servo channels 14 of the magnetic tape 10. Alternatively, the same head may be used to perform a DC erase of the servo channels 14 on a magnetic tape 10 and then to write a servo pattern in the servo channels 14 of the magnetic tape 10. That is, in this embodiment, the magnetic tape 10 is passed over the head to perform a DC erase of the servo channels 14. A pulse is applied through the pattern in the head to DC erase the servo channels 14 of the magnetic tape 10. Then, the tape 10 is passed over the head a second time to write a servo pattern into the servo channels 14 of the magnetic tape 10.
  • In one embodiment, two heads are used and are mounted into a housing so that an efficient one pass servo formatting system may be used. This embodiment is shown in FIG. 2. However, each head may be separately supported by a separate housing or even a separate tape deck (as shown in FIG. 12).
  • With reference to FIGS. 2 and 3, embodiments of an apparatus for use in DC pre-erasing a servo channel 14 of a magnetic tape 10 will be described. FIG. 2 shows a housing 20 with magnetic tape 10 extending across the two heads 22, 22′. As shown in FIG. 2, the embodiment includes a housing 20 that supports a first head 22 and a second head 22′. The heads have a first surface 24, 24′, a second surface 26, 26′, a first side surface 28, 28′, and a second side surface 30, 30′. The first surface 24, 24′ is in contact with the magnetic tape 10. The second surface 26, 26′ of the heads is attached to and supported by the housing 20. In one embodiment, the heads 22, 22′ are mounted to the housing an epoxy. However, the heads may be mounted using any suitable means.
  • The heads 22 and 22′ are disposed side-by-side separated by a predetermined distance L. As shown in FIG. 2, in one embodiment, the heads 22 and 22′ are spaced apart approximately 1.0 millimeters (“mm”) around the top edge 29, 29′ (i.e., toward the first surface 24) and spaced apart approximately 0.80 mm at the bottom edge 31, 31′ (i.e., toward the second surface 26). It will be appreciated that while the distance between the heads is specified, other distances may be used. Similarly, the angle A formed between the two heads may be varied and even flat contours may be used. While FIG. 2 shows the heads 22 and 22′ not spaced such that the sides 30, 28′ are parallel to each other, the heads may be spaced in such a manner that the sides 30, 28′ of the first and second heads 22 and 22′ are substantially parallel to each other in the vertical direction as shown.
  • Any type of head may be used in the dual head configuration including, but not limited to thin film heads, ferrite based heads, and surface thin film heads. For instance, the first and second heads 22 and 22′ may be heads with low inductance, ferrite sub-gap substrate surface film head structures of the type described in U.S. Pat. No. 6,496,328, which is hereby incorporated by reference in its entirety, a surface thin-film head of the type disclosed in U.S. Pat. No. 6,269,533, which is hereby incorporated by reference in its entirety, or a ferrite metal-in-gap (“MIG”) head. Any combination of these types of heads may be used when using two or more head in implementing an embodiment of the present invention. It will be noted that one head will be optimized as an erase head and the other head will be optimized as a servo write head.
  • In one embodiment of the dual configuration (as shown in FIG. 10), a ferrite MIG head or a surface thin film head with a pattern would be used to perform the DC erase and a surface thin film head using the low inductance, ferrite sub-gap substrate surface film head with a time base servo pattern would be used to write a servo pattern on the servo channel of the magnetic tape. FIG. 10 shows a ferrite MIG head with a pre-erase gap 46 to perform a DC erase with a surface thin film head having gap for an amplitude or a time based servo pattern for writing to a servo channel 14. As shown in FIG. 10, the width of the pre-erase gap is substantially the same as the width of the servo pattern.
  • The housing 20 may be formed from any appropriate material including metal. The housing 20 is milled to position the heads 22, 22′ to the housing. Furthermore, it will be appreciated that while FIG. 2 shows a housing that includes two heads, a housing having more than two heads is within the scope of the present invention.
  • FIG. 3 shows a housing mount 20 that has a first head 22. This embodiment may be used when the heads for performing the DC pre-erase on the servo channels 14 and writing the servo patterns on the servo channels 14 are located on different tape decks or this embodiment may be used when the same head is used to perform both the DC erase on one pass and write the servo data 18 on the servo track 14 on a second pass. FIG. 12 shows a first housing 20 supporting a first head 22 with the magnetic tape 10 extending over the head 22, where the head is used to pre-erase with direct current the servo channels 14 of a magnetic tape 10 and a second housing 20′ supporting a second head 22′ with magnetic tape 10 extending over the second head 22′, where the second head 22′ is used to write servo data in the servo channel 14 of the magnetic tape 10.
  • FIG. 11 shows an alternative embodiment that may be used for more precise pattern combinations than a mechanically assembled dual module head pair. FIG. 11 shows a compound substrate 80. As shown in FIG. 11, the compound substrate 80 has a first substrate 81 and a second substrate 83. The first and second substrates 81 and 83 are spaced apart a predetermined distance L by use of a first block 85 to separate the substrates. The first substrate includes a pre-erase gap 46 to DC erase a servo channel and the second substrate includes a servo pattern that is written in the DC pre-erased servo channel. As shown in FIG. 11, the pre-erase gap is ideally substantially the same width at the servo pattern. The pre-erase gap may have a slightly larger width than the width of the servo pattern. The first block 85 separating the compound substrate may be formed with ceramic. However, other materials may be used to separate the substrates. The substrates may be joined together using epoxy.
  • FIG. 11 shows a compound substrate 80 having a combination of a surface thin film head (of the type described in U.S. Pat. No. 6,269,533) and a low inductance surface thin film head (of the type described in U.S. Pat. No. 6,496,328). Also, while two substrates are joined together in FIG. 11, a compound substrate having more than two substrates is within the scope of the present invention.
  • The compound substrate in FIG. 11 may have all the gaps lithographically printed by a single mask and hence all patterns printed on those sub-gaps will have lithographic precision to the order of 0.1 microns or better. Hence, the compound substrate module may be used for more precise pattern combinations than a mechanically assembled dual module head pair.
  • The apparatuses discussed with respect to FIGS. 2 and 3 may contain various servo patterns where one of the patterns is for performing a DC pre-erase of a servo track 14. FIG. 4 shows an exemplary servo erase gap pattern on the surface of a surface film head. While the servo head itself of FIG. 5 may be used to pre-erase the tape 10 this would require a two pass operation which would be time inefficient. However that would be within the scope of the present invention.
  • FIG. 4 shows an exemplary servo erase gap pattern on the surface of a surface film head. The servo erase gap pattern 32 includes a first termination 34 and a second termination 36. The terminations 34, 36 may have curved portions. As shown in FIG. 4, the terminations 34 and 36 are circular. FIG. 5 shows an exemplary servo gap pattern on the surface of a surface film head that may be used to write a servo pattern in the servo channel 14 on a magnetic tape 10. FIG. 5 shows a servo gap pattern 38 that is time based. The servo gap pattern 38 has a first portion 40 and a second portion 40′, with each portion 40, 40′ having a first termination 42, 42′ and a second termination 44, 44′. As with the pattern in FIG. 4, the terminations 42, 42′, 44, 44′ have curved portions, and as shown, have circular terminations. It will be appreciated that other types servo patterns may be used without departing from the scope of the present invention.
  • FIG. 6 shows a two head configuration in which one head has a gap pattern 32 that would be used to DC pre-erase the servo channel and the other head has a timing based servo gap pattern 38 that would write a timing based pattern onto the servo channel on a magnetic tape 10. FIG. 7 shows a close-up of the patterns shown in FIG. 6. Note that the patterns are matched so that the erase gap track width is substantially the same as the servo gap track width. Such a configuration would allow the entire servo track 14 to be DC erased
  • FIGS. 4-6 show each head having five patterns that may be used to perform a DC pre-erase. Such heads may have the same number of patterns to perform a pre-erase as the number of servo channels or servo tracks 14 contained on the magnetic tape 10.
  • A pre-erase process may be performed during the production of magnetic tape in order to provide a stronger signal for reading the servo pattern. FIG. 8A shows magnetic tape 10 with servo track 14, wherein the servo track 14 has been AC erased but not DC erased. As shown in FIG. 8A, the magnetic tape 10 has a magnetic layer 11 and a substrate 13. The “M” stands for magnetization and shows that a portion 19 of the servo channel 14 is magnetized (e.g., by the writing of servo data). FIG. 8B shows the input signal 50 from a tape 10 as read by a read head of the servo pattern 14 in such a condition. The amplitude B indicates, at least in part, the strength of the signal 50.
  • FIG. 8C shows magnetic tape 10 with servo track 14, wherein the servo track has been DC erased in accordance with the present invention. As in FIG. 8A, the servo channel 14 has be magnetized by the written servo data. However, unlike FIG. 8A, the portion of the servo channel adjacent the servo data has been DC pre-erased. FIG. 8D shows the input signal 52 from the tape 10 as read by the servo read head in such a condition. The amplitude C indicates the strength of the input signal 52 from the DC pre-erased servo channel is theoretically greater than the input signal 50 from the servo channel that was not DC pre-erased. A comparison of FIGS. 8B and 8D shows that, in theory, the input signal 52 from a DC pre-erased servo channel is greater than the input signal 50 from a servo channel that has not been DC pre-erased. In one embodiment, a DC pre-erased channel, in theory, would provide a servo read voltage signal twice as strong as an input signal from a servo channel that has not been DC pre-erased but which had been randomly erased.
  • FIGS. 9A and 9B show a theoretical response curve 70 of the MR stripe, a theoretical input signal from a tape 71 and a theoretical output voltage 72. The response curve 70 includes a peak 73 and a portion that approximates a linear region 74. This response curve is sometime referred to the cosine squared response as the curve can be modeled as .DELTA.R=(.delta..rho./.rho.)R cos.sup.2.phi.). The angel .phi. being the angle between the resultant magnetization vector of the MR stripe and the applied current direction in the stripe. (.delta..rho./.rho.) is called the magnetoresistive coefficient of the material that makes up the stripe.
  • This response curve in turn leads to a voltage .DELTA.V=I.DELTA.R, where I is the bias current of the stripe. This discussion could equally apply to giant magnetoresistive (“GMR”) materials where the response is similar but modeled as a cosine curve.
  • In general, the output voltage should correspond to a waveform shown in FIG. 9A in which the input signal is within the linear region of the response curve. However, as shown in FIG. 9B, when the output voltage has a “rabbit ears” 75, that the input signal extends outside the linear region and, as shown, to the negative slope of there response curve.
  • This condition is not desired. As such, the DC pre-erase must be such that the signal output remains within the liner region of the response curve. As such, the present invention when used appropriately allows for greater voltages of the input signal while still remaining in the linear region of the response curve.
  • Also, in general, the MR read sensor output voltage is a function of the thickness of the magnetic tape. To achieve higher linear recording densities the tape thickness is generally decreased to maintain magnetic bit cell stability. Hence the servo read signals may need to be increased as tape thickness decreases. As such, under proper conditions, and assuming certain system parameters of higher density recordings, performing a DC pre-erase of a servo channel enables a stronger signal to be read without going into the non-linear region of the MR read elements response curve.
  • In practical operation, a dual head system consisting of a servo write head and servo DC erase head would be used in making magnetic tape. The servo DC erase will erase only that part of the medium upon which will be recorded the servo format signal. For all practical purposes, the DC erase head track widths and the servo format head track widths would be the same and they would be matched up within certain engineering tolerances. That is, the magnetic tape would only be DC erased in the servo track region and not in the data track regions. This is because data zones should remain ideally AC erased so that the subsequent data written thereupon will have the highest possible signal-to-noise ration and the data will not be biased by the underlying DC erasure.
  • In principle one could wipe the entire tape width with a DC erase and achieve the same result on the servo track, however that may compromise the subsequently recorded data in the data track areas. Hence, while one could use a full tape width DC erase head this would not be preferred method for reasons that go beyond the scope of this document.
  • During manufacture, the magnetic tape would move in a transducing direction over the heads. The servo channel of the magnetic tape is first pre-erased, and then a servo pattern is written in the servo channel 14 (see FIG. 1). The resulting magnetic tape 10 would have a pre-aligned magnetization of the opposite polarity to that of the servo signal.
  • The dual module head system on one mount, the dual heads on separate individual mountsor the compound substrate head may be used to enable this concept. This concept can apply to timing based servo systems, amplitude based systems or a combination of both in some more advanced servo system. The concept will be most effective when the servo write system is uni-polar in nature and when the DC pre-erase is made using the opposite polarity.
  • In that the foregoing description of the present invention discloses only exemplary embodiments thereof, it is to be understood that other variations are contemplated as being within the scope of the present invention. Accordingly, the present invention is not limited in the particular embodiments which have been described in detail therein. Rather, reference should be made to the appended claims as indicative of the scope and content of the present invention.

Claims (22)

1. A method for making a magnetic media, the method comprising:
pre-erasing at least one servo channel of the magnetic media, without direct current pre-erasing the data channels of the magnetic media, by applying a direct current of a first polarity; and
writing a servo pattern by applying a direct current of substantially opposite polarity of the first polarity.
2. The method of claim 1, wherein the pre-erasing and the writing is performed using a compound magnetic recording head.
3. The method of claim 2, wherein the compound magnetic recording head comprises:
a first head comprising a magnetically permeable thin film layer comprising an erase gap pattern for pre-erasing a servo track of a magnetic media; and
a second head comprising a magnetically permeable thin film layer comprising a servo write gap pattern for writing a servo pattern in the servo track.
4. The method of claim 3, wherein the erase gap pattern of the first head and the servo write gap pattern of the second head are lithographically printed using a single mask.
5. The method of claim 4, wherein pre-erasing at least one servo channel is performed by passing a portion of the magnetic media over the erase gap pattern of the first head and writing a servo pattern is performed by then passing a portion of the magnetic media over the servo write gap pattern of the second head.
6. The method of claim 5, wherein the servo write gap pattern of the second head is a timing-based servo pattern.
7. The method of claim 5, wherein the servo write gap pattern of the second head is an amplitude-based servo pattern.
8. The method of claim 1, wherein prior to pre-erasing at least one servo channel of the magnetic media, the magnetic media is alternating current erased.
9. A magnetic tape having at least one servo channel that is direct current pre-erased and has servo data written in the at least one servo channel and at least one alternating current pre-erased data channel for receiving data subsequently written thereon, the magnetic tape made by a method comprising: writing a servo pattern using a direct current of a first polarity; prior to the act of writing a servo pattern, erasing at least one servo channel of the magnetic tape by applying a direct current of a substantially opposite polarity of the first polarity.
10. The magnetic tape of claim 9, wherein the act of writing and erasing is performed using a first head.
11. The magnetic tape of claim 10, wherein the first head comprises a time-based servo pattern.
12. The magnetic tape of claim 10, wherein the first head comprises an amplitude-based servo pattern.
13. The magnetic tape of claim 10, wherein the act of erasing at least one servo channel of the magnetic tape is performed by first passing a portion of the magnetic tape that includes the at least one servo channel to be erased over the first head.
14. The magnetic tape of claim 13, wherein the act of writing a servo pattern in the at least one servo channel of the magnetic tape is performed by then passing a portion of the magnetic tape that includes the at least one servo channel to be written over the first head.
15. The magnetic tape of claim 9, wherein the act of erasing is performed by a first head and the act of writing a servo pattern is performed by a second head.
16. The magnetic tape of claim 15, wherein the second head includes a time based servo pattern.
17. The magnetic tape of claim 15, wherein the second head includes an amplitude-based servo pattern.
18. The magnetic tape of claim 15, wherein the first head includes an erase pattern having an erase gap track width that is substantially the same as the servo gap track width.
19. The magnetic tape of claim 15, wherein the second head is one of a thin film head, ferrite based head, and surface thin film head.
20. The magnetic tape of claim 15, wherein the two heads are located on a single mount.
21. The magnetic tape of claim 15, wherein the two heads are located on separate mounts.
22. The magnetic tape of claim 15, wherein the head used to erase is located on a separate tape deck from the head used to write a servo pattern.
US12/773,544 2004-01-30 2010-05-04 Apparatuses and methods for pre-erasing during manufacture of magnetic tape Abandoned US20100284105A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US12/773,544 US20100284105A1 (en) 2004-01-30 2010-05-04 Apparatuses and methods for pre-erasing during manufacture of magnetic tape

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US10/768,719 US7283317B2 (en) 2004-01-30 2004-01-30 Apparatuses and methods for pre-erasing during manufacture of magnetic tape
US11/838,006 US7576949B2 (en) 2004-01-30 2007-08-13 Servo track magnetic recording head for pre-erasing magnetic tape
US12/271,203 US7710675B2 (en) 2004-01-30 2008-11-14 Apparatuses and methods for pre-erasing during manufacture of magnetic tape
US12/773,544 US20100284105A1 (en) 2004-01-30 2010-05-04 Apparatuses and methods for pre-erasing during manufacture of magnetic tape

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US12/271,203 Continuation US7710675B2 (en) 2004-01-30 2008-11-14 Apparatuses and methods for pre-erasing during manufacture of magnetic tape

Publications (1)

Publication Number Publication Date
US20100284105A1 true US20100284105A1 (en) 2010-11-11

Family

ID=34807936

Family Applications (4)

Application Number Title Priority Date Filing Date
US10/768,719 Expired - Fee Related US7283317B2 (en) 2004-01-30 2004-01-30 Apparatuses and methods for pre-erasing during manufacture of magnetic tape
US11/838,006 Expired - Fee Related US7576949B2 (en) 2004-01-30 2007-08-13 Servo track magnetic recording head for pre-erasing magnetic tape
US12/271,203 Expired - Fee Related US7710675B2 (en) 2004-01-30 2008-11-14 Apparatuses and methods for pre-erasing during manufacture of magnetic tape
US12/773,544 Abandoned US20100284105A1 (en) 2004-01-30 2010-05-04 Apparatuses and methods for pre-erasing during manufacture of magnetic tape

Family Applications Before (3)

Application Number Title Priority Date Filing Date
US10/768,719 Expired - Fee Related US7283317B2 (en) 2004-01-30 2004-01-30 Apparatuses and methods for pre-erasing during manufacture of magnetic tape
US11/838,006 Expired - Fee Related US7576949B2 (en) 2004-01-30 2007-08-13 Servo track magnetic recording head for pre-erasing magnetic tape
US12/271,203 Expired - Fee Related US7710675B2 (en) 2004-01-30 2008-11-14 Apparatuses and methods for pre-erasing during manufacture of magnetic tape

Country Status (1)

Country Link
US (4) US7283317B2 (en)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020017330A (en) * 2018-07-27 2020-01-30 富士フイルム株式会社 Magnetic tape, magnetic tape cartridge, and magnetic tape device
US20200211592A1 (en) 2018-12-28 2020-07-02 Fujifilm Corporation Magnetic tape, magnetic tape cartridge, and magnetic tape apparatus
JP2020177724A (en) * 2018-12-28 2020-10-29 富士フイルム株式会社 Magnetic tape, magnetic tape cartridge, and magnetic tape device
JP2020177722A (en) * 2020-07-17 2020-10-29 富士フイルム株式会社 Magnetic tape, magnetic tape cartridge, and magnetic tape device
US10902874B2 (en) 2018-07-27 2021-01-26 Fujifilm Corporation Magnetic tape having characterized magnetic layer, magnetic tape cartridge, and magnetic tape apparatus
US11361793B2 (en) 2018-03-23 2022-06-14 Fujifilm Corporation Magnetic tape having characterized magnetic layer and magnetic recording and reproducing device
US11361792B2 (en) 2018-03-23 2022-06-14 Fujifilm Corporation Magnetic tape having characterized magnetic layer and magnetic recording and reproducing device
US11373680B2 (en) 2017-09-29 2022-06-28 Fujifilm Corporation Magnetic tape having characterized magnetic layer and magnetic recording and reproducing device
US11417359B2 (en) 2019-09-17 2022-08-16 Fujifilm Corporation Magnetic recording medium having characterized magnetic layer and magnetic recording and reproducing device
US11417358B2 (en) 2019-01-31 2022-08-16 Fujifilm Corporation Magnetic tape, magnetic tape cartridge, and magnetic tape apparatus
US11430478B2 (en) 2018-12-28 2022-08-30 Fujifilm Corporation Magnetic tape, magnetic tape cartridge, and magnetic tape apparatus
US11468911B2 (en) 2018-10-22 2022-10-11 Fujifilm Corporation Magnetic tape having characterized magnetic layer, magnetic tape cartridge, and magnetic tape apparatus
US11475915B2 (en) 2017-06-23 2022-10-18 Fujifilm Corporation Magnetic recording medium
US11501799B2 (en) 2017-09-29 2022-11-15 Fujifilm Corporation Magnetic tape having characterized magnetic layer and magnetic recording and reproducing device
US11514944B2 (en) 2018-03-23 2022-11-29 Fujifilm Corporation Magnetic tape and magnetic tape device
US11514943B2 (en) 2018-03-23 2022-11-29 Fujifilm Corporation Magnetic tape and magnetic tape device

Families Citing this family (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7773340B2 (en) * 1999-02-23 2010-08-10 Advanced Research Corporation Patterned magnetic recording head having a gap pattern with substantially elliptical or substantially diamond-shaped termination pattern
US6496328B1 (en) 1999-12-30 2002-12-17 Advanced Research Corporation Low inductance, ferrite sub-gap substrate structure for surface film magnetic recording heads
US7106544B2 (en) * 2003-05-09 2006-09-12 Advanced Research Corporation Servo systems, servo heads, servo patterns for data storage especially for reading, writing, and recording in magnetic recording tape
JP2005085361A (en) * 2003-09-09 2005-03-31 Fuji Photo Film Co Ltd Servo writer
JP2005166230A (en) * 2003-11-10 2005-06-23 Sony Corp Recording method for magnetic recording medium, recording device for magnetic recording medium, and magnetic recording medium
US8144424B2 (en) 2003-12-19 2012-03-27 Dugas Matthew P Timing-based servo verify head and magnetic media made therewith
US7283317B2 (en) * 2004-01-30 2007-10-16 Advanced Research Corporation Apparatuses and methods for pre-erasing during manufacture of magnetic tape
US7301716B2 (en) * 2004-02-17 2007-11-27 Advanced Research Corporation Stepped time based servo pattern and head
US7511907B2 (en) 2004-02-17 2009-03-31 Advanced Research Corporation Stepped time based servo pattern and head
US7199957B2 (en) * 2004-03-30 2007-04-03 Imation Corp. Write head alignment for full amplitude time-based servo
US7450341B2 (en) 2004-05-04 2008-11-11 Advanced Research Corporation Intergrated thin film subgap subpole structure for arbitrary gap pattern magnetic recording heads and method of making the same
JP2005327386A (en) * 2004-05-14 2005-11-24 Fuji Photo Film Co Ltd Magnetic recording medium, servo signal write head unit, and servo writer
US7304576B2 (en) * 2005-10-20 2007-12-04 Imation Corp. Refurbishing and resale techniques for data storage tape
US7289289B2 (en) * 2005-10-27 2007-10-30 Hewlett-Packard Development Company, L.P. Recording servo stripes onto a servo track
US7474486B2 (en) * 2005-11-18 2009-01-06 International Business Machines Corporation Magnetic storage media
US7511908B2 (en) * 2005-11-18 2009-03-31 International Business Machines Corporation Magnetic-polarity encoded servo position information for magnetic-based storage media
JP2007207365A (en) * 2006-02-02 2007-08-16 Fujifilm Corp Servo writer and servo signal writing method
JP2007257728A (en) * 2006-03-23 2007-10-04 Fujifilm Corp Servo writer, signal output control method, signal output control program, and manufacturing method of magnetic tape using signal output control method
US7791834B2 (en) 2006-08-14 2010-09-07 International Business Machines Corporation Magnetic head having a ratio of back gap width to front gap width in about a defined range
JP4137987B1 (en) * 2007-01-25 2008-08-20 日立マクセル株式会社 Servo signal recording apparatus, servo signal recording method, and magnetic tape
US8068300B2 (en) 2008-03-28 2011-11-29 Advanced Research Corporation Thin film planar arbitrary gap pattern magnetic head
US20100177437A1 (en) * 2008-08-11 2010-07-15 Gregory Lawrence Wagner Method for Bipolar Trailing Edge Timing-Based Servo Track Recording and Magnetic Tape Made Therewith
US7986485B2 (en) * 2009-03-31 2011-07-26 Oracle America, Inc. Servo writer providing a pre-writing, longitudinal magnetic bias in a magnetically unoriented tape supply
WO2011014836A2 (en) 2009-07-31 2011-02-03 Advanced Research Corporation Erase drive systems and methods of erasure for tape data cartridge
US8749912B2 (en) * 2010-07-20 2014-06-10 International Business Machines Corporation Method and apparatus for bipolar servo marks writing with self DC-erase
JP5658512B2 (en) * 2010-08-31 2015-01-28 富士フイルム株式会社 Method for manufacturing magnetic tape on which servo signal is written and servo writer
US8693127B2 (en) * 2011-01-27 2014-04-08 International Business Machines Corporation Writing timing-based servo patterns in perpendicular and non-oriented magnetic media
US9093095B2 (en) 2013-10-18 2015-07-28 Western Digital Technologies, Inc. Electronic system with media preparation mechanism and method of operation thereof
US9373346B1 (en) 2015-06-27 2016-06-21 International Business Machines Corporation Adjustable spacing formatter head
GB2557564B (en) * 2016-06-22 2020-10-28 Insurgo Media Services Ltd Magnetic head
US10748573B2 (en) * 2019-01-14 2020-08-18 International Business Machines Corporation Multichannel tape head module having mechanically settable transducer pitch
US11929104B2 (en) 2022-02-18 2024-03-12 Seagate Technology Llc Data storage drive with dedicated erase transducer
US11837263B1 (en) * 2022-08-18 2023-12-05 International Business Machines Corporation Tape erase element included in a tape erase device to erase a tape medium

Citations (92)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2938962A (en) * 1955-07-12 1960-05-31 Konins Azimuth seeking reproducing head
US4007493A (en) * 1975-05-06 1977-02-08 Burroughs Corporation Track positioning system for magnetic transducer head
US4088490A (en) * 1976-06-14 1978-05-09 International Business Machines Corporation Single level masking process with two positive photoresist layers
US4268881A (en) * 1978-06-15 1981-05-19 Olympus Optical Co., Ltd. Azimuth adjusting device for magnetic head
US4314290A (en) * 1977-06-16 1982-02-02 Burroughs Corporation Di-bit recording technique and associated servo indicia
US4318146A (en) * 1978-12-29 1982-03-02 Sony Corporation Rotary head assembly
US4586094A (en) * 1984-03-13 1986-04-29 Irwin Magnetic Systems, Inc. Method and apparatus for pre-recording tracking information on magnetic media
US4642709A (en) * 1985-10-16 1987-02-10 International Business Machines Corporation Twin track vertical magnetic recording servo control method
US4897748A (en) * 1987-04-03 1990-01-30 Matsushita Electric Industrial Co., Ltd. Magnetic head for azimuth recording in a high density magnetic recording system
US4901178A (en) * 1986-02-13 1990-02-13 Sony Corporation Thin film magnetic head
US4906552A (en) * 1988-02-22 1990-03-06 Hughes Aircraft Company Two layer dye photoresist process for sub-half micrometer resolution photolithography
US4914805A (en) * 1987-02-10 1990-04-10 Masahiro Kawase Method of manufacturing a magnetic head having a plurality of magnetic gaps
US4927804A (en) * 1987-07-15 1990-05-22 U.S. Philips Corp. Thin-film transformer and magnetic head provided with such a transformer
US4992897A (en) * 1988-04-15 1991-02-12 Commissariat A L'energie Atomique Device for reading and writing on a magnetic medium
US5017326A (en) * 1989-10-05 1991-05-21 Eastman Kodak Company Film mid roll interrupt protection for a camera using magnetic azimuth recording on film
US5016342A (en) * 1989-06-30 1991-05-21 Ampex Corporation Method of manufacturing ultra small track width thin film transducers
US5079663A (en) * 1990-01-29 1992-01-07 International Business Machines Corporation Magnetoresistive sensor with track following capability
US5086015A (en) * 1988-08-24 1992-02-04 Hitachi, Ltd. Method of etching a semiconductor device by an ion beam
US5090111A (en) * 1989-09-29 1992-02-25 Commissariat A L'energie Atomique Process for producing a magnetic recording head
US5093980A (en) * 1989-06-27 1992-03-10 Thomson-Csf Method for making a multitrack head
US5189580A (en) * 1989-06-30 1993-02-23 Ampex Corporation Ultra small track width thin film magnetic transducer
US5195006A (en) * 1990-06-07 1993-03-16 Mitsubishi Denki Kabushiki Kaisha Thin-film magnetic head element having high recording/reproducing characteristics
US5196969A (en) * 1989-03-31 1993-03-23 Sharp Kabushiki Kaisha Head positioning system for serpentine magnetic recording/reproducing system
US5211734A (en) * 1989-03-31 1993-05-18 Tdk Corporation Method for making a magnetic head having surface-reinforced glass
US5280402A (en) * 1991-08-30 1994-01-18 Minnesota Mining And Manufacturing Company Combined stepper motor and voice coil head positioning apparatus
US5293281A (en) * 1989-10-02 1994-03-08 Behr Michael I Method of reading and writing data transitions on side-by-side tracks on magnetic media
US5301418A (en) * 1991-04-12 1994-04-12 U.S. Philips Corporation Method of manufacturing a magnetic head
US5307217A (en) * 1992-06-24 1994-04-26 Digital Equipment Corporation Magnetic head for very high track density magnetic recording
US5309299A (en) * 1992-10-07 1994-05-03 International Business Machines Corporation Method and system for position error signal generation using auto correlation
US5379170A (en) * 1992-04-13 1995-01-03 Minnesota Mining And Manufacturing Company Dynamically adjustable head positioning mechanism for tape drives
US5394285A (en) * 1993-07-21 1995-02-28 Storage Technology Corporation Multi-track longitudinal, metal-in-gap head
US5398145A (en) * 1991-10-10 1995-03-14 Eastman Kodak Company Tracking control apparatus including a servo head having a tapered transducing gap
US5402295A (en) * 1990-04-16 1995-03-28 Hitachi, Ltd. Magnetic recording head capable of defining narrow track width and magnetic recording apparatus using the same
US5405734A (en) * 1992-03-31 1995-04-11 Seiko Instruments Inc. Method for correcting a patterned film using an ion beam
US5488525A (en) * 1994-08-18 1996-01-30 International Business Machines Corporation Decoupled magnetic head assembly for quarter-inch tape
US5504339A (en) * 1993-10-28 1996-04-02 Kabushiki Kaisha Toshiba Method of repairing a pattern using a photomask pattern repair device
US5506737A (en) * 1994-07-05 1996-04-09 Industrial Technology Research Institute High-density electronic head
US5593065A (en) * 1995-04-10 1997-01-14 Pakmax, Inc. Metered dual dispenser cap for squeeze containers
US5602703A (en) * 1994-12-27 1997-02-11 Seagate Technology, Inc. Recording head for recording track-centering servo signals on a multi-track recording medium
US5606478A (en) * 1994-12-08 1997-02-25 International Business Machines Corporation Ni45 Fe55 metal-in-gap thin film magnetic head
US5616921A (en) * 1993-06-28 1997-04-01 Schlumberger Technologies Inc. Self-masking FIB milling
US5621188A (en) * 1994-05-06 1997-04-15 Lee; Sang C. Air permeable electromagnetic shielding medium
US5629813A (en) * 1993-06-14 1997-05-13 International Business Machines Corporation Initialization and calibration of magnetic tape having multiple servo areas
US5710673A (en) * 1996-06-07 1998-01-20 Ampex Corporation Azimuth record head for minimizing and equalizing crosstalk between tracks of opposite azimuths
US5715597A (en) * 1993-10-01 1998-02-10 Applied Magnetics Corporation Method for manufacturing thin film magnetic head
US5719730A (en) * 1996-07-17 1998-02-17 Headway Technologies, Inc. Low fringe-field and narrow write-track magneto-resistive (MR) magnetic read-write head
US5723234A (en) * 1995-02-28 1998-03-03 Dai Nippon Printing Co., Ltd. Phase shift photomask and phase shift photomask dry etching method
US5726841A (en) * 1996-06-11 1998-03-10 Read-Rite Corporation Thin film magnetic head with trimmed pole tips etched by focused ion beam for undershoot reduction
US5737826A (en) * 1995-06-07 1998-04-14 Seagate Technology, Inc. Method of making a thin-film transducer design for undershoot reduction
US5742452A (en) * 1996-01-10 1998-04-21 International Business Machines Corporation Low mass magnetic recording head and suspension
US5751526A (en) * 1995-06-05 1998-05-12 Mke-Quantum Components Colorado Llc Flux enhanced write transducer and process for producing the same in conjunction with shared shields on magnetoresistive read heads
US5752309A (en) * 1996-06-14 1998-05-19 Quantum Corporation Method and apparatus for precisely dimensioning pole tips of a magnetic transducing head structure
US5757575A (en) * 1996-10-31 1998-05-26 Ampex Corporation Track-curvature detection using clock phase shift in azimuth recording
US5863450A (en) * 1955-04-04 1999-01-26 Commissariat A L'energie Atomique Process for making a plane magnetic head and magnetic head obtained by this process
US5867339A (en) * 1996-01-11 1999-02-02 Quantum Corporation Two channel azimuth and two channel non-azimuth read-after-write longitudinal magnetic head
US5890278A (en) * 1997-04-01 1999-04-06 U.S. Philips Corporation Method of manufacturing a magnetic head having a structure of layers
US6018444A (en) * 1997-10-28 2000-01-25 Hewlett-Packard Company Batch fabricated servo write head having low write-gap linewidth variation
US6021013A (en) * 1994-06-30 2000-02-01 International Business Machines Corporation Timing based servo system for magnetic tape systems
US6025970A (en) * 1997-08-07 2000-02-15 International Business Machines Corporation Digital demodulation of a complementary two-frequency servo PES pattern
US6031673A (en) * 1998-03-04 2000-02-29 Hewlett-Packard Company Servo band verification in linear tape systems having timing-based servo formats
US6034835A (en) * 1997-08-07 2000-03-07 International Business Machines Corporation Multiple servo track types using multiple frequency servo patterns
US6169640B1 (en) * 1998-03-04 2001-01-02 Hewlett-Packard Co. Servo band identification in linear tape systems having timing based servo formats
US6190836B1 (en) * 1997-01-21 2001-02-20 International Business Machines Corporation Methods for repair of photomasks
US6222698B1 (en) * 1998-05-22 2001-04-24 Hewlett-Packard Company Magnetic tape dimensional instability compensation by varying recording head azimuth angle
US6236525B1 (en) * 1998-08-14 2001-05-22 Storage Technology Corporation Tape head with pattern timing for servo writing application
US6236538B1 (en) * 1992-10-20 2001-05-22 Mitsubishi Denki Kabushiki Kaisha Magnetic structure and magnetic head using the same
US20020034042A1 (en) * 1999-03-24 2002-03-21 Storage Technology Corporation Highly aligned thin film tape head
US20020058204A1 (en) * 2000-02-28 2002-05-16 International Business Machines Corporation Underlayer compositions for multilayer lithographic processes
US20030016446A1 (en) * 2001-07-17 2003-01-23 Nitto Denko Corporation Optical film, polarizer and display device
US20030039063A1 (en) * 1999-12-30 2003-02-27 Advanced Research Corporation, A Minnesota Corporation Wear pads for timing-based surface film servo heads
US20030048563A1 (en) * 2001-09-12 2003-03-13 Magnusson Steven L. Alternating-azimuth angle helical track format using grouped same-azimuth angle heads
US6542325B1 (en) * 1999-03-10 2003-04-01 Imation Corp. Time-based servo for magnetic storage media
US6545837B1 (en) * 1999-12-21 2003-04-08 Imation Corp. Method and apparatus for servo controlled azimuth data recording
US20040001275A1 (en) * 2002-06-27 2004-01-01 International Business Machines Corporation Apparatus and method to read and/or write information to a magnetic tape medium
US6700729B1 (en) * 2000-10-17 2004-03-02 Hewlett-Packard Development Company Alignment marks for tape head positioning
US6721126B1 (en) * 2000-08-16 2004-04-13 International Business Machines Corporation Position identification for a coarse actuator portion of a compound actuator
US20050007323A1 (en) * 2003-07-08 2005-01-13 Appelbaum Ian Robert Magneto-luminescent transducer
US6865050B2 (en) * 2001-06-07 2005-03-08 Fuji Photo Film Co., Ltd. Servo signal recording device and servo signal verifying device using edge detection
US20050052779A1 (en) * 2003-09-05 2005-03-10 Fuji Photo Film Co., Ltd. Servo writer and servo writing method
US20050052783A1 (en) * 2003-09-09 2005-03-10 Fuji Photo Film Co., Ltd. Combined magnetic head and manufacturing method thereof
US6873487B2 (en) * 2001-11-26 2005-03-29 Imation Corp. Hybrid servopositioning systems
US6879457B2 (en) * 2002-02-13 2005-04-12 International Business Machines Corporation Timing based servo with fixed distances between transitions
US6987648B2 (en) * 1999-02-23 2006-01-17 Advanced Research Corporation Magnetic media and process of making thereof
US6989950B2 (en) * 2003-09-11 2006-01-24 Fuji Photo Film Co., Ltd. Magnetic tape and manufacturing method thereof, and servo writer and servo write method
US7170702B2 (en) * 2003-09-11 2007-01-30 Fuji Photo Film Co., Ltd. Servo band recorded magnetic tape, manufacturing method of the same, servo band writer and servo band writing method
US7190551B2 (en) * 2003-12-04 2007-03-13 Fuji Photo Film Co., Ltd. Composite magnetic head and process for producing the same
US7196870B2 (en) * 1999-02-23 2007-03-27 Advanced Research Corporation Patterned magnetic recording head with termination pattern having a curved portion
US7206170B2 (en) * 2004-05-19 2007-04-17 Imetion Corp. Thin film servo head apparatus with canted servo gaps
US7511908B2 (en) * 2005-11-18 2009-03-31 International Business Machines Corporation Magnetic-polarity encoded servo position information for magnetic-based storage media
US7515374B2 (en) * 2003-04-15 2009-04-07 Fujifilm Corporation Magnetic tape and manufacturing method thereof, and servo writer
US7525761B2 (en) * 1999-12-30 2009-04-28 Advanced Research Corporation Method of making a multi-channel time based servo tape media
US7679858B2 (en) * 2005-11-18 2010-03-16 International Business Machines Corporation Method for differential timing based servo pattern for magnetic-based storage media

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6650596B2 (en) * 2001-03-22 2003-11-18 International Business Machines Corporation Method of calculating religious Hijri calendar
JP2002312907A (en) * 2001-04-13 2002-10-25 Sony Corp Magnetic mead and its manufacturing method
US6650496B2 (en) * 2001-05-15 2003-11-18 Phs Mems Fully integrated matrix magnetic recording head with independent control
US6970312B2 (en) * 2002-12-23 2005-11-29 Imation Corp. Full amplitude time-based servopositioning signals
JP2005063623A (en) * 2003-08-20 2005-03-10 Fuji Photo Film Co Ltd Servo writer and servo writing method
US7283317B2 (en) * 2004-01-30 2007-10-16 Advanced Research Corporation Apparatuses and methods for pre-erasing during manufacture of magnetic tape
US7199957B2 (en) * 2004-03-30 2007-04-03 Imation Corp. Write head alignment for full amplitude time-based servo

Patent Citations (99)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5863450A (en) * 1955-04-04 1999-01-26 Commissariat A L'energie Atomique Process for making a plane magnetic head and magnetic head obtained by this process
US2938962A (en) * 1955-07-12 1960-05-31 Konins Azimuth seeking reproducing head
US4007493A (en) * 1975-05-06 1977-02-08 Burroughs Corporation Track positioning system for magnetic transducer head
US4088490A (en) * 1976-06-14 1978-05-09 International Business Machines Corporation Single level masking process with two positive photoresist layers
US4314290A (en) * 1977-06-16 1982-02-02 Burroughs Corporation Di-bit recording technique and associated servo indicia
US4268881A (en) * 1978-06-15 1981-05-19 Olympus Optical Co., Ltd. Azimuth adjusting device for magnetic head
US4318146A (en) * 1978-12-29 1982-03-02 Sony Corporation Rotary head assembly
US4586094A (en) * 1984-03-13 1986-04-29 Irwin Magnetic Systems, Inc. Method and apparatus for pre-recording tracking information on magnetic media
US4642709A (en) * 1985-10-16 1987-02-10 International Business Machines Corporation Twin track vertical magnetic recording servo control method
US4901178A (en) * 1986-02-13 1990-02-13 Sony Corporation Thin film magnetic head
US4914805A (en) * 1987-02-10 1990-04-10 Masahiro Kawase Method of manufacturing a magnetic head having a plurality of magnetic gaps
US4897748A (en) * 1987-04-03 1990-01-30 Matsushita Electric Industrial Co., Ltd. Magnetic head for azimuth recording in a high density magnetic recording system
US4927804A (en) * 1987-07-15 1990-05-22 U.S. Philips Corp. Thin-film transformer and magnetic head provided with such a transformer
US4906552A (en) * 1988-02-22 1990-03-06 Hughes Aircraft Company Two layer dye photoresist process for sub-half micrometer resolution photolithography
US4992897A (en) * 1988-04-15 1991-02-12 Commissariat A L'energie Atomique Device for reading and writing on a magnetic medium
US5086015A (en) * 1988-08-24 1992-02-04 Hitachi, Ltd. Method of etching a semiconductor device by an ion beam
US5196969A (en) * 1989-03-31 1993-03-23 Sharp Kabushiki Kaisha Head positioning system for serpentine magnetic recording/reproducing system
US5211734A (en) * 1989-03-31 1993-05-18 Tdk Corporation Method for making a magnetic head having surface-reinforced glass
US5093980A (en) * 1989-06-27 1992-03-10 Thomson-Csf Method for making a multitrack head
US5016342A (en) * 1989-06-30 1991-05-21 Ampex Corporation Method of manufacturing ultra small track width thin film transducers
US5189580A (en) * 1989-06-30 1993-02-23 Ampex Corporation Ultra small track width thin film magnetic transducer
US5090111A (en) * 1989-09-29 1992-02-25 Commissariat A L'energie Atomique Process for producing a magnetic recording head
US5293281A (en) * 1989-10-02 1994-03-08 Behr Michael I Method of reading and writing data transitions on side-by-side tracks on magnetic media
US5017326A (en) * 1989-10-05 1991-05-21 Eastman Kodak Company Film mid roll interrupt protection for a camera using magnetic azimuth recording on film
US5079663A (en) * 1990-01-29 1992-01-07 International Business Machines Corporation Magnetoresistive sensor with track following capability
US5402295A (en) * 1990-04-16 1995-03-28 Hitachi, Ltd. Magnetic recording head capable of defining narrow track width and magnetic recording apparatus using the same
US5195006A (en) * 1990-06-07 1993-03-16 Mitsubishi Denki Kabushiki Kaisha Thin-film magnetic head element having high recording/reproducing characteristics
US5301418A (en) * 1991-04-12 1994-04-12 U.S. Philips Corporation Method of manufacturing a magnetic head
US5280402A (en) * 1991-08-30 1994-01-18 Minnesota Mining And Manufacturing Company Combined stepper motor and voice coil head positioning apparatus
US5398145A (en) * 1991-10-10 1995-03-14 Eastman Kodak Company Tracking control apparatus including a servo head having a tapered transducing gap
US5405734A (en) * 1992-03-31 1995-04-11 Seiko Instruments Inc. Method for correcting a patterned film using an ion beam
US5379170A (en) * 1992-04-13 1995-01-03 Minnesota Mining And Manufacturing Company Dynamically adjustable head positioning mechanism for tape drives
US5307217A (en) * 1992-06-24 1994-04-26 Digital Equipment Corporation Magnetic head for very high track density magnetic recording
US5309299A (en) * 1992-10-07 1994-05-03 International Business Machines Corporation Method and system for position error signal generation using auto correlation
US6236538B1 (en) * 1992-10-20 2001-05-22 Mitsubishi Denki Kabushiki Kaisha Magnetic structure and magnetic head using the same
US5629813A (en) * 1993-06-14 1997-05-13 International Business Machines Corporation Initialization and calibration of magnetic tape having multiple servo areas
US5616921A (en) * 1993-06-28 1997-04-01 Schlumberger Technologies Inc. Self-masking FIB milling
US5394285A (en) * 1993-07-21 1995-02-28 Storage Technology Corporation Multi-track longitudinal, metal-in-gap head
US5715597A (en) * 1993-10-01 1998-02-10 Applied Magnetics Corporation Method for manufacturing thin film magnetic head
US5504339A (en) * 1993-10-28 1996-04-02 Kabushiki Kaisha Toshiba Method of repairing a pattern using a photomask pattern repair device
US5621188A (en) * 1994-05-06 1997-04-15 Lee; Sang C. Air permeable electromagnetic shielding medium
US6021013A (en) * 1994-06-30 2000-02-01 International Business Machines Corporation Timing based servo system for magnetic tape systems
US5506737A (en) * 1994-07-05 1996-04-09 Industrial Technology Research Institute High-density electronic head
US5488525A (en) * 1994-08-18 1996-01-30 International Business Machines Corporation Decoupled magnetic head assembly for quarter-inch tape
US5606478A (en) * 1994-12-08 1997-02-25 International Business Machines Corporation Ni45 Fe55 metal-in-gap thin film magnetic head
US5602703A (en) * 1994-12-27 1997-02-11 Seagate Technology, Inc. Recording head for recording track-centering servo signals on a multi-track recording medium
US5723234A (en) * 1995-02-28 1998-03-03 Dai Nippon Printing Co., Ltd. Phase shift photomask and phase shift photomask dry etching method
US5593065A (en) * 1995-04-10 1997-01-14 Pakmax, Inc. Metered dual dispenser cap for squeeze containers
US5751526A (en) * 1995-06-05 1998-05-12 Mke-Quantum Components Colorado Llc Flux enhanced write transducer and process for producing the same in conjunction with shared shields on magnetoresistive read heads
US5737826A (en) * 1995-06-07 1998-04-14 Seagate Technology, Inc. Method of making a thin-film transducer design for undershoot reduction
US5742452A (en) * 1996-01-10 1998-04-21 International Business Machines Corporation Low mass magnetic recording head and suspension
US5867339A (en) * 1996-01-11 1999-02-02 Quantum Corporation Two channel azimuth and two channel non-azimuth read-after-write longitudinal magnetic head
US5710673A (en) * 1996-06-07 1998-01-20 Ampex Corporation Azimuth record head for minimizing and equalizing crosstalk between tracks of opposite azimuths
US5726841A (en) * 1996-06-11 1998-03-10 Read-Rite Corporation Thin film magnetic head with trimmed pole tips etched by focused ion beam for undershoot reduction
US5752309A (en) * 1996-06-14 1998-05-19 Quantum Corporation Method and apparatus for precisely dimensioning pole tips of a magnetic transducing head structure
US5719730A (en) * 1996-07-17 1998-02-17 Headway Technologies, Inc. Low fringe-field and narrow write-track magneto-resistive (MR) magnetic read-write head
US5757575A (en) * 1996-10-31 1998-05-26 Ampex Corporation Track-curvature detection using clock phase shift in azimuth recording
US6190836B1 (en) * 1997-01-21 2001-02-20 International Business Machines Corporation Methods for repair of photomasks
US5890278A (en) * 1997-04-01 1999-04-06 U.S. Philips Corporation Method of manufacturing a magnetic head having a structure of layers
US6025970A (en) * 1997-08-07 2000-02-15 International Business Machines Corporation Digital demodulation of a complementary two-frequency servo PES pattern
US6034835A (en) * 1997-08-07 2000-03-07 International Business Machines Corporation Multiple servo track types using multiple frequency servo patterns
US6229669B1 (en) * 1997-10-28 2001-05-08 Hewlett-Packard Co Servo head design and method of using the same
US6018444A (en) * 1997-10-28 2000-01-25 Hewlett-Packard Company Batch fabricated servo write head having low write-gap linewidth variation
US6031673A (en) * 1998-03-04 2000-02-29 Hewlett-Packard Company Servo band verification in linear tape systems having timing-based servo formats
US6169640B1 (en) * 1998-03-04 2001-01-02 Hewlett-Packard Co. Servo band identification in linear tape systems having timing based servo formats
US6222698B1 (en) * 1998-05-22 2001-04-24 Hewlett-Packard Company Magnetic tape dimensional instability compensation by varying recording head azimuth angle
US6236525B1 (en) * 1998-08-14 2001-05-22 Storage Technology Corporation Tape head with pattern timing for servo writing application
US7009810B2 (en) * 1999-02-23 2006-03-07 Advanced Research Corporation Thin-film magnetic recording head having a timing-based gap pattern for writing a servo track on magnetic media
US20090097155A1 (en) * 1999-02-23 2009-04-16 Advanced Research Corporation Magnetic media having a servo track written with a patterned magnetic recording head
US6987648B2 (en) * 1999-02-23 2006-01-17 Advanced Research Corporation Magnetic media and process of making thereof
US7196870B2 (en) * 1999-02-23 2007-03-27 Advanced Research Corporation Patterned magnetic recording head with termination pattern having a curved portion
US6542325B1 (en) * 1999-03-10 2003-04-01 Imation Corp. Time-based servo for magnetic storage media
US6842305B2 (en) * 1999-03-10 2005-01-11 Imation Corp. Time-based servo for magnetic storage media
US20020034042A1 (en) * 1999-03-24 2002-03-21 Storage Technology Corporation Highly aligned thin film tape head
US6545837B1 (en) * 1999-12-21 2003-04-08 Imation Corp. Method and apparatus for servo controlled azimuth data recording
US20030039063A1 (en) * 1999-12-30 2003-02-27 Advanced Research Corporation, A Minnesota Corporation Wear pads for timing-based surface film servo heads
US7525761B2 (en) * 1999-12-30 2009-04-28 Advanced Research Corporation Method of making a multi-channel time based servo tape media
US6989960B2 (en) * 1999-12-30 2006-01-24 Advanced Research Corporation Wear pads for timing-based surface film servo heads
US20060061906A1 (en) * 1999-12-30 2006-03-23 Advanced Research Corporation Wear pads for timing-based surface film servo heads
US20100002335A1 (en) * 1999-12-30 2010-01-07 Dugas Matthew P Method of making a multi-channel time based servo tape media
US20020058204A1 (en) * 2000-02-28 2002-05-16 International Business Machines Corporation Underlayer compositions for multilayer lithographic processes
US6721126B1 (en) * 2000-08-16 2004-04-13 International Business Machines Corporation Position identification for a coarse actuator portion of a compound actuator
US6700729B1 (en) * 2000-10-17 2004-03-02 Hewlett-Packard Development Company Alignment marks for tape head positioning
US6865050B2 (en) * 2001-06-07 2005-03-08 Fuji Photo Film Co., Ltd. Servo signal recording device and servo signal verifying device using edge detection
US20030016446A1 (en) * 2001-07-17 2003-01-23 Nitto Denko Corporation Optical film, polarizer and display device
US20030048563A1 (en) * 2001-09-12 2003-03-13 Magnusson Steven L. Alternating-azimuth angle helical track format using grouped same-azimuth angle heads
US6873487B2 (en) * 2001-11-26 2005-03-29 Imation Corp. Hybrid servopositioning systems
US6879457B2 (en) * 2002-02-13 2005-04-12 International Business Machines Corporation Timing based servo with fixed distances between transitions
US20040001275A1 (en) * 2002-06-27 2004-01-01 International Business Machines Corporation Apparatus and method to read and/or write information to a magnetic tape medium
US7515374B2 (en) * 2003-04-15 2009-04-07 Fujifilm Corporation Magnetic tape and manufacturing method thereof, and servo writer
US20050007323A1 (en) * 2003-07-08 2005-01-13 Appelbaum Ian Robert Magneto-luminescent transducer
US20050052779A1 (en) * 2003-09-05 2005-03-10 Fuji Photo Film Co., Ltd. Servo writer and servo writing method
US20050052783A1 (en) * 2003-09-09 2005-03-10 Fuji Photo Film Co., Ltd. Combined magnetic head and manufacturing method thereof
US6989950B2 (en) * 2003-09-11 2006-01-24 Fuji Photo Film Co., Ltd. Magnetic tape and manufacturing method thereof, and servo writer and servo write method
US7170702B2 (en) * 2003-09-11 2007-01-30 Fuji Photo Film Co., Ltd. Servo band recorded magnetic tape, manufacturing method of the same, servo band writer and servo band writing method
US7190551B2 (en) * 2003-12-04 2007-03-13 Fuji Photo Film Co., Ltd. Composite magnetic head and process for producing the same
US7206170B2 (en) * 2004-05-19 2007-04-17 Imetion Corp. Thin film servo head apparatus with canted servo gaps
US7511908B2 (en) * 2005-11-18 2009-03-31 International Business Machines Corporation Magnetic-polarity encoded servo position information for magnetic-based storage media
US7679858B2 (en) * 2005-11-18 2010-03-16 International Business Machines Corporation Method for differential timing based servo pattern for magnetic-based storage media

Cited By (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11631427B2 (en) 2017-06-23 2023-04-18 Fujifilm Corporation Magnetic recording medium
US11475915B2 (en) 2017-06-23 2022-10-18 Fujifilm Corporation Magnetic recording medium
US11373680B2 (en) 2017-09-29 2022-06-28 Fujifilm Corporation Magnetic tape having characterized magnetic layer and magnetic recording and reproducing device
US11501799B2 (en) 2017-09-29 2022-11-15 Fujifilm Corporation Magnetic tape having characterized magnetic layer and magnetic recording and reproducing device
US11462242B2 (en) 2017-09-29 2022-10-04 Fujifilm Corporation Magnetic tape having characterized magnetic layer and magnetic recording and reproducing device
US11361793B2 (en) 2018-03-23 2022-06-14 Fujifilm Corporation Magnetic tape having characterized magnetic layer and magnetic recording and reproducing device
US11514943B2 (en) 2018-03-23 2022-11-29 Fujifilm Corporation Magnetic tape and magnetic tape device
US11361792B2 (en) 2018-03-23 2022-06-14 Fujifilm Corporation Magnetic tape having characterized magnetic layer and magnetic recording and reproducing device
US11514944B2 (en) 2018-03-23 2022-11-29 Fujifilm Corporation Magnetic tape and magnetic tape device
US11551716B2 (en) 2018-03-23 2023-01-10 Fujifilm Corporation Magnetic tape having characterized magnetic layer and magnetic recording and reproducing device
US11581015B2 (en) 2018-03-23 2023-02-14 Fujifilm Corporation Magnetic tape having characterized magnetic layer and magnetic recording and reproducing device
JP2020017330A (en) * 2018-07-27 2020-01-30 富士フイルム株式会社 Magnetic tape, magnetic tape cartridge, and magnetic tape device
US11417357B2 (en) 2018-07-27 2022-08-16 Fujifilm Corporation Magnetic tape, magnetic tape cartridge, and magnetic tape apparatus
US11430475B2 (en) 2018-07-27 2022-08-30 Fujifilm Corporation Magnetic tape, magnetic tape cartridge, and magnetic tape apparatus
US10902874B2 (en) 2018-07-27 2021-01-26 Fujifilm Corporation Magnetic tape having characterized magnetic layer, magnetic tape cartridge, and magnetic tape apparatus
US11468911B2 (en) 2018-10-22 2022-10-11 Fujifilm Corporation Magnetic tape having characterized magnetic layer, magnetic tape cartridge, and magnetic tape apparatus
US11423935B2 (en) 2018-12-28 2022-08-23 Fujifilm Corporation Magnetic tape with particular refractive index characteristics, magnetic tape cartridge, and magnetic tape apparatus
US11430478B2 (en) 2018-12-28 2022-08-30 Fujifilm Corporation Magnetic tape, magnetic tape cartridge, and magnetic tape apparatus
US20200211592A1 (en) 2018-12-28 2020-07-02 Fujifilm Corporation Magnetic tape, magnetic tape cartridge, and magnetic tape apparatus
US11443766B2 (en) 2018-12-28 2022-09-13 Fujifilm Corporation Magnetic tape with particular refractive index characteristics, magnetic tape cartridge, and magnetic tape apparatus
JP2020177724A (en) * 2018-12-28 2020-10-29 富士フイルム株式会社 Magnetic tape, magnetic tape cartridge, and magnetic tape device
JP2020107380A (en) * 2018-12-28 2020-07-09 富士フイルム株式会社 Magnetic tape, magnetic tape cartridge, and magnetic tape device
US11417358B2 (en) 2019-01-31 2022-08-16 Fujifilm Corporation Magnetic tape, magnetic tape cartridge, and magnetic tape apparatus
US11437063B2 (en) 2019-01-31 2022-09-06 Fujifilm Corporation Magnetic tape, magnetic tape cartridge, and magnetic tape apparatus
US11417359B2 (en) 2019-09-17 2022-08-16 Fujifilm Corporation Magnetic recording medium having characterized magnetic layer and magnetic recording and reproducing device
JP2020177722A (en) * 2020-07-17 2020-10-29 富士フイルム株式会社 Magnetic tape, magnetic tape cartridge, and magnetic tape device
JP7109508B2 (en) 2020-07-17 2022-07-29 富士フイルム株式会社 Magnetic tapes, magnetic tape cartridges and magnetic tape devices

Also Published As

Publication number Publication date
US20050168869A1 (en) 2005-08-04
US20090067087A1 (en) 2009-03-12
US7576949B2 (en) 2009-08-18
US7283317B2 (en) 2007-10-16
US20080037166A1 (en) 2008-02-14
US7710675B2 (en) 2010-05-04

Similar Documents

Publication Publication Date Title
US7710675B2 (en) Apparatuses and methods for pre-erasing during manufacture of magnetic tape
US5963400A (en) Thin film tape head including split top pole
US6873487B2 (en) Hybrid servopositioning systems
US7511907B2 (en) Stepped time based servo pattern and head
US7466510B2 (en) Distributed servo patterns for data storage media
US7095583B2 (en) Dual mode servo pattern
US6970312B2 (en) Full amplitude time-based servopositioning signals
US7436622B2 (en) Concurrent servo and data track writing
US7266880B2 (en) Method of making a monolithic magnetic read-while-write head apparatus
US5321570A (en) Systems using superimposed, orthogonal buried servo signals
US5426543A (en) Servo positioning system for magnetic recording media
US7057834B2 (en) Master information carrier and method for manufacturing magnetic disc using the same
US6873482B1 (en) Magnetic recording drive with continuous magnetic servo system
US7880999B2 (en) Magnetic storage system with read during write
US7301716B2 (en) Stepped time based servo pattern and head
JP3705076B2 (en) Magnetic recording method on perpendicular magnetic recording medium using master information carrier
US20100177437A1 (en) Method for Bipolar Trailing Edge Timing-Based Servo Track Recording and Magnetic Tape Made Therewith
US20050057845A1 (en) Two-sided data storage tape with servo information on both sides of the tape
WO1999050834A1 (en) Thin film tape head including split top pole
JP3343339B2 (en) Method for manufacturing in-plane magnetic recording medium
JPH1186213A (en) Magnetic head and magnetic disk apparatus using the same
JPH1125429A (en) Thin film magnetic head
US20020057539A1 (en) Magnetoresistive head
Kryder Future of Magnetic Recording Systems
JPS61107508A (en) Vertical magnetic recording head

Legal Events

Date Code Title Description
STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO PAY ISSUE FEE