CA1042100A - Device for controlling the position of a magnetic head with respect to an information track to be followed - Google Patents
Device for controlling the position of a magnetic head with respect to an information track to be followedInfo
- Publication number
- CA1042100A CA1042100A CA204,386A CA204386A CA1042100A CA 1042100 A CA1042100 A CA 1042100A CA 204386 A CA204386 A CA 204386A CA 1042100 A CA1042100 A CA 1042100A
- Authority
- CA
- Canada
- Prior art keywords
- head
- tap
- track
- voltage
- information
- 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.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
- G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B5/596—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on disks
- G11B5/59683—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on disks for magnetoresistive heads
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/127—Structure or manufacture of heads, e.g. inductive
- G11B5/33—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only
- G11B5/39—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
- G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B2005/0002—Special dispositions or recording techniques
- G11B2005/0005—Arrangements, methods or circuits
- G11B2005/001—Controlling recording characteristics of record carriers or transducing characteristics of transducers by means not being part of their structure
- G11B2005/0013—Controlling recording characteristics of record carriers or transducing characteristics of transducers by means not being part of their structure of transducers, e.g. linearisation, equalisation
- G11B2005/0016—Controlling recording characteristics of record carriers or transducing characteristics of transducers by means not being part of their structure of transducers, e.g. linearisation, equalisation of magnetoresistive transducers
Abstract
Abstract:
A device for the automatic control of the posi-tion of the playback head with respect to an information track recorded on a magnetic recording medium cooperating with the playback head. For generating a signal for con-trolling the position of the head, the device comprises an elongate element of magnetoresistance material having two final taps and one center tap. The difference of the voltages across each final tap and the center tap is in-dicative of the position of the head.
A device for the automatic control of the posi-tion of the playback head with respect to an information track recorded on a magnetic recording medium cooperating with the playback head. For generating a signal for con-trolling the position of the head, the device comprises an elongate element of magnetoresistance material having two final taps and one center tap. The difference of the voltages across each final tap and the center tap is in-dicative of the position of the head.
Description
104;~100 "Device for controlling the position of a magnetic hcad with respect of an information track to be followed"
The invention relates to a device for the automatic control of the position of a magnetic playback head with respect to a selected information track of a number of information tracks recorded on a magnetic recording medium, which device comprises a sensing device for generating an error signal which is a function of the deviation of the head from the centre of the track, and comprises positioning means which are controlled by the error signal for moving the head to arrange it centrally on the track.
When the information recorded on a recording medium, for example a magnetic tape or a magnetic disc, is played back by means of a magnetic head, it is of essential importance that the head constantly follows the information track on the recording medium exactly and this independently of possible shifts of the record medium which, in the case in which this is a magnetic tape, may occur due to vibrations during the travel of the tape, or, in the case in which the medium is a magnetic disc, by a possible eccentricity of the track as a result of the fact that the information has not been recorded on the recording medium in the device used for playing back.
The number of tracks of information which is recorded on magnetic recording media has ever been increasing in the past several years. As a result of this the width of one single track and the distance between the tracks has inevitably become smaller. In a certain available type of video recording device, the tracks, for example, have a width of 150 /um with a track distance of 25 /um. This means that high requirements are imposed upon the accuracy with which a magnetic head follows a given information track.
It is the object of the invention to provide a device with which it is possible to cause a playback head to accurately follow information tracks with the above-mentioned or even considerably smaller width.
For that purpose, the device according to the invention is charac-terized in that the sensing device comprises an elongate sensing element of .
104~100 magnetoresistance material which has a first and a second end tap and acenter tap and the length of which corresponds to the track width used, the difference between the voltage across the first end tap and the center tap and the voltage across the second end tap and the center tap being indicative of the position of the playback head with respect to the recorded information track.
For generating a signal with which a head can be controlled it is known per se to use a conventional head having two poleshoes one of which is divided into two parts so that the information track is divided into two parts which are played back separately. By adding the two playback signals, again one output signal is obtained in principle which is proportional to the full track width, while subtraction provides a difference signal which is a measure of the transverse deviation between head and track.
However, the said division of a poleshoe presents serious structural problems with smaller track widths in particular with track widths below 100 /um, in particular when ferrite is used as a magentic material. In addition, efficiency differences between the two head halves should be taken into account in series production as a result of which, when used in a servo loop, an "offset" with respect to the desired head position will occur which differs for each individual head. Moreover, the coupling between the two halves is considerable.
The device according to the invention in which a magnetoresistance element with two end taps and a center tap is used does not exhibit the said drawbacks.
That certain magnetic materials having a low coercive force, for example permalloy, present a magnetoresistance effect is known from the United States Patent Specification 3,493,694. When a thin strip of such a material is placed in a magnetic field, its resistance varies in accordance with the strength of the field. Information stored in a recording medium can be read-out by conveying a direct current or an alternating current through a magneto-~ . :
104;~100 resistance strip arranged in the proximity of the recording medium andmeasuring the voltage differences across the strip caused by its resistance variations.
Although the sensing device with magnetoresistance element according to the invention may be used to control the position of a separate playback head which is aligned accurately with respect to the magnetoresistance element, it is an extra aspect of the invention that the magnetoresistance element itself may also be used as a playback head, so that a separate playback head is superfluous. A preferred embodiment of the device according to the invention is for that purpose characterized in that the sensing element is also a playback head in which the sum of the voltage across the first end tap and the center tap and the voltage across the second end tap and the cen-ter tap represents the information recorded in the information track.
A further preferred embodiment of the device according to the invention is characterized in that the halves of the sensing element of magnetoresistance material which are present on either side of the center tap are decoupled magnetostatically.
Dependent upon the magnetoresistance material used, this may show a coherent or an incoherent rotation of the magnetisation vector under the influence of a magnetic field. A material having an incoherent rotation does not present particular problems when used in a device according to the inven-tion, since the two halves of lhe elements are "automatically" decoupled.
When a material is used having a coherent rotation it is recommendable, how-ever, to ensure that the two halves are decoupled so that no exchange coupling can occur. This can be realized, for example, by making the magnetoresistance material inoperative in the center by alloying it with another material or by providing a scratch in it.
Since information can be played back but cannot be recorded with a magnetoresistance element, a magnetoresistance playback head will in most applications have to be combined with a recording head. It may be of impor-., . . :
, .
~04Z100 tance, for example, in systems in which the recorded information is playedback again immediately, that the gap of the recording head and the magneto-resistance element be located as closely together as possible. In a further preferred embodiment of the device according to the invention this is realized in that the sensing element of magnetoresistance material extends in the gap of a recording head.
The various characteristic features and advantages of the present invention will be described in greater detail with reference to the drawing.
Figure 1 is an elevation of a magnetoresistance sensing element to be used in a device according to the invention, and Figure 2 shows a diagram of an amplifier with which a signal genera-ted by the element shown in Figure 1 can be amplified.
According to the invention, in sensing narrow tracks a magneto-resistance element 1 is used having two electric connections 2 and 3 at the ends and a center tap 4 (Figure 1) the overall length L of which corresponds to the track width B used. For an element having a resistivity p and a thick-ness D = 1000 ~, height H = 2 /um and length L = 50 /um, the resistance in a particular case is given by R = D H = 140Q
or a permalloy element the resistance variation ~R/R under the influence of the field from the recording medium 5 is in the order of 1 to 1.5%. Reading said resistance variation with a current of 1 mA then already provides a signal voltage of 1.4 to 2.1 mV which can be amplified in a comparatively simple manner, the noise level being low. Amplification may take place, for example, by means of the transistor circuit shown in Figure 2 in which an advantage is that the resistance of the detection element is such that it can be connected directly to the transistor circuit. When the substrate is of a suitable crystalline material, for example silicon, the transistor circuit may be formed on the same substrate as the detection element in order to form an 104Z~OO
integrated circuit. An advantage is that the sensitivity to interference pulses is considerably reduced by the small distance between the amplifier and the detection element. The current Io through the magnetoresistance element 6 is adjusted by means of the voltage Eb. The collector voltage difference VR = Vcl - V 2 then is available as a control voltage for the sero device with which the position of the head is controlled, while the information signal VInf can be derived from the common collector resistance of the output emitter follower. VInf is maximum and proportional to the overall track width if the head is positioned on the track, while VR then has just the desired passage through zero.
When used in digital systems, the sensitivity can even be increased by construction Io as a pulse current with low duty cycle ~so as to restrict the dissipation) which is derived from the digital clock. In this manner bit detection may take place simultaneously or an alternating voltage signal which can be amplified more easily can be obtained in the case of record carriers which slowly move or are stationary when played back.
It will generally be of advantage that the magnetoresistance play-back head according to the invention is combined with an inductive recording head. For optimum playback of the signals recorded by the recording head it is of great importance that the gap of the recording head be accurately paral-lel to the magnetoresistance playback head and that the distance between the recording head and the magnetoresistance playback head be small. For example, an integrated recording head and the magnetoresistance playback head shown in Figure 1 may be provided on either side of a plane parallel substrate. To those skilled in the art it will present no problems to manufacture a subs-trate having two mutually accurately parallel sides, while the manufacture of magnetic heads by means of integrated technologies (both in planar and in stratified structure) is known from the art.
An alternative possibility is to provide the magnetoresistance -element in the gap of an inductive recording head, for example, by means of vapour deposition. This presents an important advantage, notably in the case of a disc memory. Due to such an arrangement it is prevented actually that the recording head and sensing element start travelling on different radii.
The relation between the voltage across a magnetoresistance element and the field of the recording medium is in fact parabolic. Linearisation can be effected by causing a magnetic bias voltage field to influence the element.
The bias voltage field at the area of the element must necessarily be large as compared with the field of the recording medium, but on the other hand the stray field of the means which have to produce the bias voltage field may not be able to influence the recording medium: this means that said stray field must be very small at the area of the medium as compared with the field of the recording medium itself. Nor may, viewed from the magnetoresistance elements, the means to apply the bias voltage field deform the field of the recording medium. A further requirement is that for supplying a correct positioning signal the detection element must "feel" a bias voltage field which is as uni-form as possible, which means that the parallism between the device to pro-duce the bias voltage field and the detection element, as well as their mutual distance, must be very accurately defined.
Several manners to produce a bias voltage field and to cause it to influence a magnetoresistance strip are known and may be used in the scope of the invention.
The displacement of the head may be realized, for example, by mount-ing the head on a swingable arm which is maintained in an equilibrium position as a result of the pretension of a spring and the electromagnetic force of an electromagnet when the sensing element produces no signal and which, when the sensing element does produce a signal meaning that the head is not positioned correctly on the track, is drawn out of its equilibrium position by the ele~tromagnet. However, the invention is not restricted to the above-described servo device.
The invention relates to a device for the automatic control of the position of a magnetic playback head with respect to a selected information track of a number of information tracks recorded on a magnetic recording medium, which device comprises a sensing device for generating an error signal which is a function of the deviation of the head from the centre of the track, and comprises positioning means which are controlled by the error signal for moving the head to arrange it centrally on the track.
When the information recorded on a recording medium, for example a magnetic tape or a magnetic disc, is played back by means of a magnetic head, it is of essential importance that the head constantly follows the information track on the recording medium exactly and this independently of possible shifts of the record medium which, in the case in which this is a magnetic tape, may occur due to vibrations during the travel of the tape, or, in the case in which the medium is a magnetic disc, by a possible eccentricity of the track as a result of the fact that the information has not been recorded on the recording medium in the device used for playing back.
The number of tracks of information which is recorded on magnetic recording media has ever been increasing in the past several years. As a result of this the width of one single track and the distance between the tracks has inevitably become smaller. In a certain available type of video recording device, the tracks, for example, have a width of 150 /um with a track distance of 25 /um. This means that high requirements are imposed upon the accuracy with which a magnetic head follows a given information track.
It is the object of the invention to provide a device with which it is possible to cause a playback head to accurately follow information tracks with the above-mentioned or even considerably smaller width.
For that purpose, the device according to the invention is charac-terized in that the sensing device comprises an elongate sensing element of .
104~100 magnetoresistance material which has a first and a second end tap and acenter tap and the length of which corresponds to the track width used, the difference between the voltage across the first end tap and the center tap and the voltage across the second end tap and the center tap being indicative of the position of the playback head with respect to the recorded information track.
For generating a signal with which a head can be controlled it is known per se to use a conventional head having two poleshoes one of which is divided into two parts so that the information track is divided into two parts which are played back separately. By adding the two playback signals, again one output signal is obtained in principle which is proportional to the full track width, while subtraction provides a difference signal which is a measure of the transverse deviation between head and track.
However, the said division of a poleshoe presents serious structural problems with smaller track widths in particular with track widths below 100 /um, in particular when ferrite is used as a magentic material. In addition, efficiency differences between the two head halves should be taken into account in series production as a result of which, when used in a servo loop, an "offset" with respect to the desired head position will occur which differs for each individual head. Moreover, the coupling between the two halves is considerable.
The device according to the invention in which a magnetoresistance element with two end taps and a center tap is used does not exhibit the said drawbacks.
That certain magnetic materials having a low coercive force, for example permalloy, present a magnetoresistance effect is known from the United States Patent Specification 3,493,694. When a thin strip of such a material is placed in a magnetic field, its resistance varies in accordance with the strength of the field. Information stored in a recording medium can be read-out by conveying a direct current or an alternating current through a magneto-~ . :
104;~100 resistance strip arranged in the proximity of the recording medium andmeasuring the voltage differences across the strip caused by its resistance variations.
Although the sensing device with magnetoresistance element according to the invention may be used to control the position of a separate playback head which is aligned accurately with respect to the magnetoresistance element, it is an extra aspect of the invention that the magnetoresistance element itself may also be used as a playback head, so that a separate playback head is superfluous. A preferred embodiment of the device according to the invention is for that purpose characterized in that the sensing element is also a playback head in which the sum of the voltage across the first end tap and the center tap and the voltage across the second end tap and the cen-ter tap represents the information recorded in the information track.
A further preferred embodiment of the device according to the invention is characterized in that the halves of the sensing element of magnetoresistance material which are present on either side of the center tap are decoupled magnetostatically.
Dependent upon the magnetoresistance material used, this may show a coherent or an incoherent rotation of the magnetisation vector under the influence of a magnetic field. A material having an incoherent rotation does not present particular problems when used in a device according to the inven-tion, since the two halves of lhe elements are "automatically" decoupled.
When a material is used having a coherent rotation it is recommendable, how-ever, to ensure that the two halves are decoupled so that no exchange coupling can occur. This can be realized, for example, by making the magnetoresistance material inoperative in the center by alloying it with another material or by providing a scratch in it.
Since information can be played back but cannot be recorded with a magnetoresistance element, a magnetoresistance playback head will in most applications have to be combined with a recording head. It may be of impor-., . . :
, .
~04Z100 tance, for example, in systems in which the recorded information is playedback again immediately, that the gap of the recording head and the magneto-resistance element be located as closely together as possible. In a further preferred embodiment of the device according to the invention this is realized in that the sensing element of magnetoresistance material extends in the gap of a recording head.
The various characteristic features and advantages of the present invention will be described in greater detail with reference to the drawing.
Figure 1 is an elevation of a magnetoresistance sensing element to be used in a device according to the invention, and Figure 2 shows a diagram of an amplifier with which a signal genera-ted by the element shown in Figure 1 can be amplified.
According to the invention, in sensing narrow tracks a magneto-resistance element 1 is used having two electric connections 2 and 3 at the ends and a center tap 4 (Figure 1) the overall length L of which corresponds to the track width B used. For an element having a resistivity p and a thick-ness D = 1000 ~, height H = 2 /um and length L = 50 /um, the resistance in a particular case is given by R = D H = 140Q
or a permalloy element the resistance variation ~R/R under the influence of the field from the recording medium 5 is in the order of 1 to 1.5%. Reading said resistance variation with a current of 1 mA then already provides a signal voltage of 1.4 to 2.1 mV which can be amplified in a comparatively simple manner, the noise level being low. Amplification may take place, for example, by means of the transistor circuit shown in Figure 2 in which an advantage is that the resistance of the detection element is such that it can be connected directly to the transistor circuit. When the substrate is of a suitable crystalline material, for example silicon, the transistor circuit may be formed on the same substrate as the detection element in order to form an 104Z~OO
integrated circuit. An advantage is that the sensitivity to interference pulses is considerably reduced by the small distance between the amplifier and the detection element. The current Io through the magnetoresistance element 6 is adjusted by means of the voltage Eb. The collector voltage difference VR = Vcl - V 2 then is available as a control voltage for the sero device with which the position of the head is controlled, while the information signal VInf can be derived from the common collector resistance of the output emitter follower. VInf is maximum and proportional to the overall track width if the head is positioned on the track, while VR then has just the desired passage through zero.
When used in digital systems, the sensitivity can even be increased by construction Io as a pulse current with low duty cycle ~so as to restrict the dissipation) which is derived from the digital clock. In this manner bit detection may take place simultaneously or an alternating voltage signal which can be amplified more easily can be obtained in the case of record carriers which slowly move or are stationary when played back.
It will generally be of advantage that the magnetoresistance play-back head according to the invention is combined with an inductive recording head. For optimum playback of the signals recorded by the recording head it is of great importance that the gap of the recording head be accurately paral-lel to the magnetoresistance playback head and that the distance between the recording head and the magnetoresistance playback head be small. For example, an integrated recording head and the magnetoresistance playback head shown in Figure 1 may be provided on either side of a plane parallel substrate. To those skilled in the art it will present no problems to manufacture a subs-trate having two mutually accurately parallel sides, while the manufacture of magnetic heads by means of integrated technologies (both in planar and in stratified structure) is known from the art.
An alternative possibility is to provide the magnetoresistance -element in the gap of an inductive recording head, for example, by means of vapour deposition. This presents an important advantage, notably in the case of a disc memory. Due to such an arrangement it is prevented actually that the recording head and sensing element start travelling on different radii.
The relation between the voltage across a magnetoresistance element and the field of the recording medium is in fact parabolic. Linearisation can be effected by causing a magnetic bias voltage field to influence the element.
The bias voltage field at the area of the element must necessarily be large as compared with the field of the recording medium, but on the other hand the stray field of the means which have to produce the bias voltage field may not be able to influence the recording medium: this means that said stray field must be very small at the area of the medium as compared with the field of the recording medium itself. Nor may, viewed from the magnetoresistance elements, the means to apply the bias voltage field deform the field of the recording medium. A further requirement is that for supplying a correct positioning signal the detection element must "feel" a bias voltage field which is as uni-form as possible, which means that the parallism between the device to pro-duce the bias voltage field and the detection element, as well as their mutual distance, must be very accurately defined.
Several manners to produce a bias voltage field and to cause it to influence a magnetoresistance strip are known and may be used in the scope of the invention.
The displacement of the head may be realized, for example, by mount-ing the head on a swingable arm which is maintained in an equilibrium position as a result of the pretension of a spring and the electromagnetic force of an electromagnet when the sensing element produces no signal and which, when the sensing element does produce a signal meaning that the head is not positioned correctly on the track, is drawn out of its equilibrium position by the ele~tromagnet. However, the invention is not restricted to the above-described servo device.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A device for the automatic control of the position of a magnetic playback head with respect to a selected information track of a number of information tracks recorded on a magnetic recording medium, which device com-prises a sensing device for generating an error signal which is a function of the deviation of the head from the centre of the track, and comprises position-ing means which are controlled by the error signal for moving the head to arrange it centrally on the track, characterized in that the sensing device comprises an elongate sensing element of magnetoresistance material which has a first and a second end tap and a center tap and the length of which corres-ponds to the track width used, the difference between the voltage across the first end tap and the center tap and the voltage across the second end tap and the center tap being indicative of the position of the playback head with res-pect to the recorded information track.
2. A device as claimed in claim 1, characterized in that the sensing element is also a playback head, in which the sum of the voltage across the first end tap and the other tap and the voltage across the second end tap and the center tap represents the information recorded in the information track.
3. A device as claimed in claim 1 or 2, characterized in that the halves of the sensing element of magnetoresistance material which are present on either side of the center tap are decoupled magnetostatically.
4. A device as claimed in claim 2, characterized in that the sensing element of magnetoresistance material extends in the gap of a recording head.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7309590A NL7309590A (en) | 1973-07-10 | 1973-07-10 | DEVICE FOR CONTROLLING THE POSITION OF A MAGNETIC HEAD WITH REGARD TO AN INFORMATION TRACK TO BE TRACKED. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1042100A true CA1042100A (en) | 1978-11-07 |
Family
ID=19819231
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA204,386A Expired CA1042100A (en) | 1973-07-10 | 1974-07-09 | Device for controlling the position of a magnetic head with respect to an information track to be followed |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US3918091A (en) |
| JP (1) | JPS5427129B2 (en) |
| CA (1) | CA1042100A (en) |
| DE (1) | DE2430612C2 (en) |
| FR (1) | FR2397040A1 (en) |
| GB (1) | GB1449756A (en) |
| NL (1) | NL7309590A (en) |
Families Citing this family (31)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4012781A (en) * | 1975-08-14 | 1977-03-15 | International Business Machines Corporation | Magnetoresistive read head assembly for servo operation |
| US3979775A (en) * | 1975-09-08 | 1976-09-07 | International Business Machines Corporation | Magnetoresistive multitransducer assembly with compensation elements for thermal drift and bias balancing |
| US4055849A (en) * | 1976-04-15 | 1977-10-25 | Eastman Kodak Company | Magnetic head positioning and playback apparatus utilizing a split head for self-tracking and selective reproduction |
| JPS6131418Y2 (en) * | 1976-05-20 | 1986-09-12 | ||
| JPS5819695Y2 (en) * | 1976-05-20 | 1983-04-22 | 日本電気株式会社 | magnetic storage device |
| JPS5367460U (en) * | 1976-11-10 | 1978-06-06 | ||
| JPS548975U (en) * | 1977-06-21 | 1979-01-20 | ||
| DE2920912A1 (en) * | 1978-05-29 | 1979-12-13 | Philips Nv | AZIMUTH CORRECTION OF HEAD COLUMNS |
| US4492997A (en) * | 1980-11-28 | 1985-01-08 | Hitachi, Ltd. | Reproducing and amplifying circuit for magnetoresistive head |
| JPS59160814A (en) * | 1983-03-02 | 1984-09-11 | Pioneer Electronic Corp | Thin film magnetic head |
| US4647992A (en) * | 1984-11-26 | 1987-03-03 | International Business Machines Corporation | Combined magnetic channel signal sensor and servo control track following system and method |
| US4652945A (en) * | 1985-05-03 | 1987-03-24 | Eastman Kodak Company | Flux sensitive tracking |
| US4670800A (en) * | 1985-05-03 | 1987-06-02 | Eastman Kodak Company | Edge guided magnetic tape tracking |
| US4611249A (en) * | 1985-05-03 | 1986-09-09 | Eastman Kodak Company | Flux sensitive tracking |
| US4633344A (en) * | 1985-05-28 | 1986-12-30 | Eastman Kodak Company | Unambiguously tracking a data track in response to signals derived from the track data itself |
| US5285331A (en) * | 1989-02-23 | 1994-02-08 | Wangtek Incorporated | System for aligning a read head gap over a track of magnetic data |
| US5079663A (en) * | 1990-01-29 | 1992-01-07 | International Business Machines Corporation | Magnetoresistive sensor with track following capability |
| NL9001231A (en) * | 1990-05-30 | 1991-12-16 | Philips Nv | READING HEAD DEVICE WITH 2N MR TYPE READING HEADS AND DISPLAY EQUIPPED WITH READING HEAD DEVICE. |
| US6088176A (en) * | 1993-04-30 | 2000-07-11 | International Business Machines Corporation | Method and apparatus for separating magnetic and thermal components from an MR read signal |
| DE4319322C2 (en) * | 1993-06-11 | 1998-04-23 | Heidenhain Gmbh Dr Johannes | Position measuring device |
| US5388014A (en) * | 1993-09-10 | 1995-02-07 | Hewlett-Packard Company | Apparatus and method of sensing the position of a magnetic head |
| US5825593A (en) * | 1994-02-18 | 1998-10-20 | Seagate Technology, Inc. | Electric field modulated MR sensor |
| US5872676A (en) * | 1996-01-02 | 1999-02-16 | International Business Machines Corporation | Method and apparatus for positioning a dual element magnetoresistive head using thermal signals |
| US5751510A (en) * | 1996-01-02 | 1998-05-12 | International Business Machines Corporation | Method and apparatus for restoring a thermal response signal of a magnetoresistive head |
| US5739972A (en) * | 1996-01-02 | 1998-04-14 | Ibm | Method and apparatus for positioning a magnetoresistive head using thermal response to servo information on the record medium |
| US6239936B1 (en) | 1997-08-19 | 2001-05-29 | International Business Machines Corporation | Method and apparatus for calibrating a thermal response of a magnetoresistive element |
| US6266205B1 (en) | 1998-03-10 | 2001-07-24 | Maxtor Corporation | Parallel servo with ultra high bandwidth off-track detection |
| US6157510A (en) * | 1998-03-10 | 2000-12-05 | Maxtor Corporation | Magnetic storage device with multiple read elements which are offset laterally and longitudinally |
| NL1011679C2 (en) * | 1999-03-26 | 2000-09-27 | Onstream B V | Magnetic flux sensor. |
| US6606216B1 (en) | 1999-05-05 | 2003-08-12 | Maxtor Corporation | Transducer head with separate data and servo read elements |
| US7564656B2 (en) * | 2005-02-28 | 2009-07-21 | Hitachi Global Storage Technologies Netherlands B.V. | Integrated servo and read EMR sensor |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT221288B (en) * | 1959-07-02 | 1962-05-10 | Siemens Ag | Pick-up head for magnetic recordings |
| CH387972A (en) * | 1959-10-29 | 1965-02-15 | Siemens Ag | Device for reproducing magnetograms |
| NL279482A (en) * | 1961-06-15 | |||
| US3493694A (en) * | 1966-01-19 | 1970-02-03 | Ampex | Magnetoresistive head |
| US3789378A (en) * | 1971-05-24 | 1974-01-29 | Olivetti & Co Spa | Transducer positioning mechanism |
| FR2165206A5 (en) * | 1971-12-22 | 1973-08-03 | Cii |
-
1973
- 1973-07-10 NL NL7309590A patent/NL7309590A/en unknown
-
1974
- 1974-06-26 DE DE2430612A patent/DE2430612C2/en not_active Expired
- 1974-07-05 GB GB2993974A patent/GB1449756A/en not_active Expired
- 1974-07-08 JP JP7747974A patent/JPS5427129B2/ja not_active Expired
- 1974-07-09 US US486772A patent/US3918091A/en not_active Expired - Lifetime
- 1974-07-09 CA CA204,386A patent/CA1042100A/en not_active Expired
- 1974-07-10 FR FR7423965A patent/FR2397040A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| FR2397040B1 (en) | 1981-09-04 |
| GB1449756A (en) | 1976-09-15 |
| DE2430612A1 (en) | 1975-01-30 |
| JPS5427129B2 (en) | 1979-09-07 |
| US3918091A (en) | 1975-11-04 |
| DE2430612C2 (en) | 1982-07-29 |
| NL7309590A (en) | 1975-01-14 |
| FR2397040A1 (en) | 1979-02-02 |
| JPS5039531A (en) | 1975-04-11 |
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