GB2279800A - Magnetic head apparatus - Google Patents

Magnetic head apparatus Download PDF

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Publication number
GB2279800A
GB2279800A GB9417710A GB9417710A GB2279800A GB 2279800 A GB2279800 A GB 2279800A GB 9417710 A GB9417710 A GB 9417710A GB 9417710 A GB9417710 A GB 9417710A GB 2279800 A GB2279800 A GB 2279800A
Authority
GB
United Kingdom
Prior art keywords
magnetic head
density magnetic
track
low density
density
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.)
Granted
Application number
GB9417710A
Other versions
GB9417710D0 (en
GB2279800B (en
Inventor
Masaru Nishimura
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.)
Mitsubishi Electric Corp
Original Assignee
Mitsubishi Electric Corp
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
Priority to JP12254391A priority Critical patent/JP2922671B2/en
Priority to JP17941691A priority patent/JP2833274B2/en
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Priority to GB9208410A priority patent/GB2255221B/en
Publication of GB9417710D0 publication Critical patent/GB9417710D0/en
Publication of GB2279800A publication Critical patent/GB2279800A/en
Application granted granted Critical
Publication of GB2279800B publication Critical patent/GB2279800B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

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
    • G11B5/012Recording on, or reproducing or erasing from, magnetic disks
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B19/00Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
    • G11B19/02Control of operating function, e.g. switching from recording to reproducing
    • 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
    • G11B5/48Disposition 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
    • G11B5/488Disposition of heads
    • G11B5/4886Disposition of heads relative to rotating disc
    • 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
    • G11B5/48Disposition 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
    • G11B5/54Disposition 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 into or out of its operative position or across tracks
    • G11B5/55Track change, selection or acquisition by displacement of the head
    • G11B5/5521Track change, selection or acquisition by displacement of the head across disk tracks
    • G11B5/5526Control therefor; circuits, track configurations or relative disposition of servo-information transducers and servo-information tracks for control thereof

Abstract

In a magnetic head apparatus, having a high density magnetic head (2) and a low density magnetic head (3) for reading/reproducing selectively tracks at different track densities of a disc, the effective width TWL of the low density magnetic head (3) is set to be an even number multiple of the track pitch TPU of the high density tracks to minimise the effects of cross-talk. The heads may be on a single slider, or on two sliders on opposite sides of a disc. They may be arranged side-by-side or one-behind-the-other in the track direction, to which they may be inclined. <IMAGE>

Description

MAGNETIC HEAD APPARATUS The invention relates to a magnetic head apparatus used for magnetic disc apparatus or flexible disc apparatus.
FIG. 7 of the accompanying drawings is a general construction diagram of a conventional magnetic head apparatus disclosed in the laidopen Japanese patent publication No. 62-28913. In the figure, 1 is a slider, which mounts a high density magnetic head 2 and a low density magnetic head 3. Either a recording medium 4A for low density or a recording medium 4B for high density is arranged under the slider 1. A low track 5 is arranged on the surface of the low density recording medium 4A, and a high track 6 is arranged on the surface of the high density recording medium 4B. 7 is representative of magnetic interference (crosstalk) between the high density magnetic head 2 and the low density magnetic head 3. TWU is a track width of the high density magnetic head 2. Two is a track width of the low density magnetic head 3. Tpu is a track pitch between the tracks on the high density recording medium 4B. TpL is a track pitch between the tracks on the low density recording medium 4A. T, is a distance between the high density magnetic head 2 and the low density magnetic head 3. TWA is a distance between the low tracks 5 on the low density recording medium 4A.
The operation of the conventional magnetic head apparatus is explained hereinafter. The conventional slider 1 has a plurality of heads for different densities, such as the high density magnetic head 2 and the low density magnetic head 3, in order to record and reproduce the data in a plurality of the different density recording mediums 4A and 4B. The plurality of magnetic heads operate independently according to each standard.
A mechanical feeding stepping motor is used for positioning the Jer 1 to an arbitrary position. The high density magnetic head 2 is iven to the arbitrary position at the high density track 6 for every one ?ulse, and the low density magnetic head 3 is driven to the arbitrary position at the low density track 5, for example, for every two pulses.
The positions at the low density track 5 and the high density. track 6 on the respective recording mediums 4A and 4B are deEmed by the apparatus standard. Therefore, not only the low density magnetic head 3 but also the high density magnetic head 2 may be positioned over the low density track 5 ,while the low density magnetic head 3 is operated by the feeding pitch of the stepping motor.
Since the conventional magnetic head apparatus is constructed as described above, if the high density magnetic head 2 is positioned over another bw density track SB ,while the low density magnetic head 3 is recording or reproducing the recording signal, when a recording signal is applied to the low density magnetic head 3, a part of the recording signal leaks to the high density magnetic head 2 by the influence of the crosstalk 7 between the high density magnetic head 2 and the low density magnetic head 3.
The recording signal to be recorded onto the low density track 5A is also recorded into another low density track SB by the influence of the above mentioned crosstalk. When the low density magnetic head 3 reproduces the data on the low density track SA, the high density magnetic head 2 reproduces the data on the low density track SB at the same time, and a part of the reproduced data by the high density magnetic head 2 leaks to the low density magnetic head 3 by the influence of the crosstalk 7.
Accordingly, there occur error problems, since the data reproduced by the high density magnetic head 2 are superimposed over the data reproduced from the low density track 5A by the low density magnetic head 3.
FIG. 8 and FIG. 9 of the accompanying drawings are respectively, an enlarged diagram and a diagram for enplaning the operation of the conventional magnetic head apparatus disclosed in the laid-open Japanese patent publication No. 62-28913. In FIG. 8, 1 is a slider, 2 is a magnetic head having narrower track width (having high density ) , referred as a high density magnetic head in the following. 3 is a magnetic head having wider track width (having low density ), referred as a low density magnetic head in the following. 4 is a recording medium. 5 is a signal track recorded on the recording medium. 6 shows magnetic interference between the low density magnetic head and the high magnetic head, referred as crosstalk in the following. Twu is a track width of the high density magnetic head 2. T,is a track width of the low density magnetic head 3. Tpu is a track pitch between the signal tracks of the high density magnetic head. S1 to Slo, A and B are the servo signals recorded on the signal track.
The operation of the conventional magnetic head apparatus is explained hereinafter. The conventional magnetic head apparatus has a plurality of magnetic heads for different densities as shown in FIG. 8, such as the high density magnetic head 2 and the low density magnetic head 3, in order to record and reproduce the data in a plurality of the different density recording mediums. The plurality of magnetic heads operate independently according to each standard. As shown in FIG. 8 , while the high density magnetic head 2 is recording and reproducing the data to the high track density on the recording medium 4, the low density magnetic head 3 is positioned over a plurality of signal track 5. Accordingly the low density magnetic head 3 reproduces the data signal and the servo signal, and some of the signals generated by the crosstalk 6 leak to the high density magnetic head 2 and are superposed on the signal reproduced by the high density magnetic head 2.
In order to position the high density magnetic head 2 to the desired signal track 5 on the recording medium 4, a sector servo system is generally used.
Figure 9 of the accompanying drawings shows an example of the sector servo system. In Figure 9, when the high density magnetic head 2 is going to be positioned relative to the signal track, for example 5g, the high density magnetic head 2 is moved to the near position 5g by detecting the servo signal S, which records the information such as the track number and the sector number. By detecting the difference of the servo signal A and B, the high density magnetic head 2 is positioned precisely over the position 5g.
Since the conventional magnetic head apparatus is constructed as described above, while the difference of the servo signals A and B is detected in order to position the high density magnetic head to the accurate position, the low density magnetic head also detects the servo signals A and B. The detected signal at the low density magnetic head is superposed on the high density magnetic head signal by the crosstalk. Therefore, the servo signals A and B to be detected at the high density magnetic head include error signals. Accordingly, it has been difficult to detect the accurate position of the magnetic head because the errors are increased for positioning.
According to the present invention, there is provided magnetic head apparatus for use with a recording medium of predetermined format comprising circumferential tracks of predetermined widths and pitches including a wide track width and a narrow track width, the apparatus comprising a plurality of magnetic heads having different effective widths corresponding to the predetermined widths, said heads being carried by at least one slider, herein the effective width of the magnetic head orresponding to the wide tracks is set to be an even number multiple of the predetermined track pitch of the narrow tracks.
Thus, the present invention can prevent tihe generation of an error servo signal by the crosstalk and provide for accurate positioning because of the small positioning error.
The invention will be further described by way I of non-limitative example, with reference to the accompanying drawings, in which: Figure 1 is an enlarged diagram of the head of the magnetic head apparatus of a first embodiment of the present invention.
Figure 2 is a diagram for explaining the operation of the first embodiment of the present invention.
Figure 3 is a general diagram of a second embodiment of the present invention.
Figure 4 is an enlarged diagram of a third embodiment of the present invention.
Figure 5 is a general diagram of a fourth embodiment of the present invention.
Figure 6 is a general diagram of a fifth embodiment of the present invention.
Figure 7 is a construction diagram of a conventional magnetic head apparatus.
Figure 8 is an enlarged diagram of a conventional magnetic head apparatus.
Figure 9 is a diagram for explaining the operation of the conventional magnetic head apparatus.
The first embodiment of the present invention is described hereinafter. Figure 1 of the accompanying drawings is an enlarged diagram of the head portion of the magnetic head apparatus of the present invention. Figure 2 of the accompanying drawings is a diagram for explaining the operation of the invention. The reference numbers in Figure 1 are the same as those used in Figure 8 for the same portions or the corresponding portions.
In the first embodiment of the present invention of Figure 1, high density magnetic head 2 is adjacent to the low density magnetic head 3 in slider 1 and the track width Tt of the low density magnetic head 3 is set to be an even number multiple of the track pitch TpU of the high density magnetic head 2.
The operation of the magnetic head apparatus is explained hereinafter. Since the track width Tt of the low density magnetic head 3 is set to be an even number multiple of the track pitch Tor of the high density magnetic head 2, when the high density magnetic head 2 is positioned to the signal track 5g in Figure 2, the low density magnetic head 3 is positioned over the tracks 5b - Se. Accordingly, the low density magnetic head 3 reproduces the servo signal A from the 7b and 7c and the servo signal B from the oblique line parts of Sa, 8b and 8c. Since the sunimation amount of the oblique line parts of 8a , 8b and Sc corresponds to one servo signal B, the ratio of the servo signal A and the servo signal B is always equal to 1:1.
Therefore, even if some of the signals reproduced by the low density magnetic head 3 leak to the high density magnetic head 2 by the crosstalk between the heads, the difference signal of the servo signals A and B for positioning the high density magnetic head 2 is detected accurately. Because the difference signal of the servo signal A and the servo signal B influences to the high density magnetic head 2 with a small amount.
That is, even if the servo signals A and B reproduced by the low density magnetic head 3 leak to the high density magnetic head 2 by the crosstalk between the heads, the high density magnetic head 2 is not influenced by the crosstalk. Therefore the high density magnetic head 2 can be positioned accurately to the track 5g.
In the first embodiment of the present invention, the high density magnetic head 2 is arranged adjacent to the low density magnetic head 3. But, in FIG. 3, the high density magnetic head 2 is arranged far from the low density magnetic head 3. In this second embodiment of the present invention shown in FIG. 3, the same effect is obtained as that of the first embodiment of the present invention.
In the first embodiment and the second embodiment of the present invention, the effects of the crosstalk are explained. FIG. 4 of the accompanying drawings shows the crosstalk 6 generated between the slider la and the slider ib which are arranged at the opposite side of the recording medium 4. Therefore, if the track width TWL of the low density magnetic head 3 is set to be an even number multiple of the track pitch Tpu of the high density magnetic head 2 arranged at opposite side'for the recording medium 4, the same effect is obtained as that of the first embodiment of the present invention.
In the above embodiment 1, 2 and 3, the high density magnetic head 2 and the low density magnetic head 3 are arranged in parallel along the running direction. In FIG. 5 (a) and (b), the high density magnetic head 2 and the low density magnetic head 3 are arranged in series along the running direction. In this case, if the track width TWL of the low density magnetic head is set to be an even number multiple of the track pitch Tpu of the high density magnetic head 2, the same effect is obtained as that of the first embodiment of the third present invention. In the figure 5 (a) and (b), 13 is a coil for the high density magnetic head 2 and 15 is a coil for the low density magnetic head 3. 33 is a gap of the high density magnetic head 2 and 35 is a gap of the low density magnetic head 3. 41 is an erasing core.
In the fourth embodiment, it is better to set the distance L between the high density magnetic head 2 and low density magnetic head 3 to be smaller. In other words, when the high density magnetic head 2 is reproducing the servo signal A, the low density magnetic head 3 is preferable to reproduce the servo signal A for a long time. Therefore, as shown in FIG, 5 (b), the length Ls of the servo signal A along the track direction is preferable to be set such as L < Ls.
In Figure 6, the high density magnetic head 2 and the low density magnetic head 3 are formed by the core 31 and core 32 arranged oblique along the running direction. In this case, if the track width Tt of the low density magnetic head is set to be an even number multiple of the track pitch TpU of the high density magnetic head 2, the same effect is obtained as that of the first embodiment of the present invention.
The above shows the design of the magnetic head apparatus in which the track width is set to be an even number multiple in the case where the track pitch is constant. The invention may be applied though to a design in which the track width is constant. The track pitch is not decided by the track width of the head but also decided by the feeding pitch of the drive. The track pitch becomes large and the track density becomes small when the feeding amount becomes large even if the head having narrow track width is used. That is, the magnetic disc apparatus having the different pitch can be designed if the same magnetic head is used. Thus, in the invention, the track pitch can be designed so that the influence of the crosstalk may be maximally decreased by the same principle as that explained above.
This application was divided from copending application number 92 08410.2 which relates to spacing the heads by an odd number multiple of half the low density track pitch. A related divisional application is copending application number 94 which relates to spacing the heads by an integer multiple of the low density track width.

Claims (5)

1. Magnetic head apparatus for use with a recording medium of predetermined format comprising circumferential tracks of predetermined widths. and pitches including a wide track width and a narrow track width, the apparatus comprising a plurality of magnetic heads having different effective widths corresponding to the predetermined widths, said heads being carried by at least one slider, wherein the effective width of the magnetic head corresponding to the wide tracks is set to be an even number multiple of the predetermined track pitch of the narrow tracks.
2. Magnetic head apparatus according to claim 1, wherein the heads are positioned to face opposite sides of the recording medium.
3. Magnetic head apparatus according to claim 1, wherein the heads are arranged sequentially in the tracking direction.
4. Magnetic head apparatus according to claim 1, wherein the heads are formed in cores arranged obliquely to the tracking direction.
5. Magnetic head apparatus constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 6 of the accompanying drawings.
GB9417710A 1991-04-25 1992-04-16 Magnetic head apparatus Expired - Fee Related GB2279800B (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP12254391A JP2922671B2 (en) 1991-04-25 1991-04-25 Magnetic head device
JP17941691A JP2833274B2 (en) 1991-07-19 1991-07-19 Magnetic head and magnetic disk drive
GB9208410A GB2255221B (en) 1991-04-25 1992-04-16 Magnetic head apparatus

Publications (3)

Publication Number Publication Date
GB9417710D0 GB9417710D0 (en) 1994-10-19
GB2279800A true GB2279800A (en) 1995-01-11
GB2279800B GB2279800B (en) 1996-01-03

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ID=27266149

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Application Number Title Priority Date Filing Date
GB9417710A Expired - Fee Related GB2279800B (en) 1991-04-25 1992-04-16 Magnetic head apparatus
GB9417711A Withdrawn GB2279801A (en) 1991-04-25 1994-09-02 Magnetic head apparatus

Family Applications After (1)

Application Number Title Priority Date Filing Date
GB9417711A Withdrawn GB2279801A (en) 1991-04-25 1994-09-02 Magnetic head apparatus

Country Status (1)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0994474A1 (en) * 1998-10-14 2000-04-19 Sony Corporation Disc drive and control thereof
US6304419B1 (en) * 1998-02-20 2001-10-16 Sony Corporation Magnetic head device and recording medium drive

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4805051A (en) * 1984-11-15 1989-02-14 Ing. C. Olivetti & C., S.P.A. Apparatus for recording and reproducing data on a magnetic recording medium
EP0423661A2 (en) * 1989-10-20 1991-04-24 Insite Peripherals, Inc. Dual magnetic head and method for writing on very high track density and conventional track density floppy disk

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4805051A (en) * 1984-11-15 1989-02-14 Ing. C. Olivetti & C., S.P.A. Apparatus for recording and reproducing data on a magnetic recording medium
EP0423661A2 (en) * 1989-10-20 1991-04-24 Insite Peripherals, Inc. Dual magnetic head and method for writing on very high track density and conventional track density floppy disk

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6304419B1 (en) * 1998-02-20 2001-10-16 Sony Corporation Magnetic head device and recording medium drive
EP0994474A1 (en) * 1998-10-14 2000-04-19 Sony Corporation Disc drive and control thereof
US6535346B1 (en) 1998-10-14 2003-03-18 Sony Corporation Dual head disk drive unit for differing recording densities

Also Published As

Publication number Publication date
GB2279800B (en) 1996-01-03
GB9417711D0 (en) 1994-10-19
GB9417710D0 (en) 1994-10-19
GB2279801A (en) 1995-01-11

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Legal Events

Date Code Title Description
746 Register noted 'licences of right' (sect. 46/1977)

Effective date: 19971202

PCNP Patent ceased through non-payment of renewal fee

Effective date: 20080416