JP2008176862A - Magnetic disk medium, magnetic disk unit, and tracking method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple method of continuously performing tracking along a circumference direction of magnetic tracks in a magnetic disk medium by a DIR (discrete track recording) system and a magnetic disk medium embodying the same, and a magnetic disk device applying them. <P>SOLUTION: In the magnetic disk medium used for the DIR system in which the magnetic tracks adjacent to each other are previously separated by grooves, zones are constituted by the plurality of magnetic tracks and large grooves broader than the grooves between the adjacent grooves are provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetic disk medium, a magnetic disk device, and a tracking method to which a DTR (discrete track recording) system and a patterned media recording system are applied.

  In a conventional magnetic disk apparatus, there are a predetermined number (for example, 128) of servo pattern areas in one circumference of a magnetic disk medium, and servo positioning signals and address information for the magnetic track when the head passes through these areas. Thus, recording / reproduction is performed in the subsequent data area. That is, there is no positioning signal while the head passes through the data area, and the data area is recorded and reproduced based on the positioning signal in the servo pattern area.

  FIG. 1 shows a magnetic disk medium of a conventional magnetic disk device. A plurality of magnetic tracks 5 are concentrically formed with respect to the center hole 2 of the magnetic disk medium 1, and a predetermined number of servo pattern areas 3 and data areas 4 are provided in one circumference of each magnetic track 5.

  In order to improve the surface recording density of the magnetic disk medium of the above-described type, it is necessary to increase the linear recording density and the magnetic track density.

  As a method for increasing the linear recording density, there is a possibility that the linear recording density can be significantly increased by changing from the in-plane magnetic recording method to the perpendicular magnetic recording method, and attention is paid to it.

  On the other hand, in the direction of increasing the magnetic track density, when the magnetic track density is increased, there is a possibility that a so-called cross write occurs due to the influence of the writing blur of the recording on the adjacent magnetic track during recording. When cross writing occurs, for example, information already recorded on the adjacent magnetic track is partially overwritten, and normal information recording cannot be guaranteed. At the time of reproduction, in addition to the signal of the target magnetic track, the signal from the adjacent magnetic track is picked up and crosstalk causing noise increases.

  Therefore, as one method for increasing the magnetic track density, for example, a DTR method is proposed in Patent Document 1. In this system, since at least the magnetic track is separated and defined in advance by a groove, cross-write during recording and cross-talk during reproduction are reduced, which is advantageous for narrowing the track.

  In the patterned media recording system, the 1-bit area is further separately defined along the magnetic track, but the magnetic track is separately defined as in the DTR system.

  In the DTR system, the problem is how to make the head follow a magnetic track separated and defined on the disk. In a conventional magnetic disk device using a continuous film disk, a servo pattern is magnetically recorded and a data recording area is used between the servo pattern and the servo pattern. However, as the track density is increased by the DTR method, a high-precision head Since tracking is required, it is desired to continuously servo the magnetic track itself.

  Known examples of this include, for example, methods described in Patent Document 2, Patent Document 3, and the like.

  In Patent Document 2, in a discrete magnetic disk, a head positioning signal is written along a magnetic track, and tracking of the magnetic head is performed based on the head positioning signal. Since the head follows the distortion and scans on the magnetic track, a tracking error caused by the distortion of the magnetic track is suppressed.

In Patent Document 3, in a discrete magnetic disk, a magnetic track is divided in the circumferential direction by dividing lines, and further subdivided by a plurality of signal gaps formed in a predetermined pattern arrangement in the circumferential direction. Each is changed, and tracking control is performed using the difference in the pattern arrangement.
JP 2006-31756 A JP 09-7143 A JP 2003-263850 A

  As described above, in the DTR magnetic disk medium, a tracking signal is embedded in the entire circumferential direction of the magnetic track or a part of the circumferential direction of the magnetic track in order to perform tracking servo. As the track density is further increased, high-precision head tracking is required. Therefore, it is desirable to continuously apply servo to the magnetic track.

  However, the method of continuously writing servo signals on the magnetic track itself becomes increasingly technically difficult in terms of space and reliability.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a method for easily and continuously tracking a magnetic track of a magnetic disk medium in the circumferential direction, a magnetic disk medium embodying the method, and a magnetic disk device to which these are applied. To do.

  The invention according to claim 1 of the present invention is a magnetic disk medium in which magnetic tracks adjacent to each other are separated in advance by a groove, and a plurality of the magnetic tracks form a zone, and the groove is formed between the adjacent zones. The magnetic disk medium is characterized in that a wider groove is provided.

  According to the first aspect of the present invention, a DTR or patterned media recording type magnetic disk in which a zone is formed for each predetermined number of magnetic tracks, and the zones are separated by wider grooves than the grooves between the magnetic tracks. Hereinafter, a magnetic disk medium means a magnetic disk medium using a DTR system including a patterned media recording system unless otherwise specified.

  For example, the magnetic disk medium is irradiated with laser light having a light spot diameter substantially equal to the width of the zone to obtain 0th-order diffracted light and ± 1st-order diffracted light reflected from the zone and the large groove. Since the light intensity balance of the ± 1st order diffracted light changes depending on the relative position of the light spot position with respect to the zone and the thick groove, the head mounted with the laser light source is detected by the so-called push-pull method by detecting the light quantity difference of the ± 1st order diffracted light. The relative position signal is used as a relative position signal for each zone, and the tracking control of the head for each magnetic track in the zone is attempted using this relative position signal.

  In the present invention, a servo signal for head tracking control is provided in each magnetic track in order to use the relative position signal of each zone and head in the magnetic disk medium for head tracking control for each magnetic track in the zone. This is a magnetic disk medium that can be continuously subjected to tracking servo over one circumference of the magnetic track.

  Here, the magnetic disk medium in the present invention may be either for in-plane magnetic recording or for perpendicular magnetic recording.

  In addition, each magnetic track from the bottom surface of the groove between the magnetic tracks to the surface of the magnetic disk medium may be composed entirely of a magnetic material for magnetic recording, or a part may be composed of a magnetic material for magnetic recording. .

  According to a second aspect of the present invention, there is provided a magnetic disk medium in which a magnetic layer for performing magnetic recording is provided on at least a surface portion of the magnetic track, and the groove and the thick groove are filled with a nonmagnetic material. The magnetic disk medium according to claim 1, wherein the magnetic disk medium is provided.

  When a floating head is used for a magnetic disk medium, the grooves between the magnetic tracks and the thick grooves between the zones are filled with a nonmagnetic material from the viewpoint of the flying characteristics of the head, and the surface is flush with the surface of the magnetic track. Preferably there is.

  According to the second aspect of the present invention, the groove between the magnetic tracks and the thick groove between the zones of the magnetic disk medium are filled with the nonmagnetic material, and preferably, the surface corresponding to the peak portion of the magnetic track, and the magnetic track The surface corresponding to the crests of the nonmagnetic material filled in the inter-grooves and the thick grooves between the zones are on the same plane and includes at least the surface corresponding to the crests of the magnetic track. The magnetic disk medium has a layer and a protective layer and / or a lubricant layer on the same plane.

  According to the second aspect of the present invention, the tracking control is performed by utilizing the difference in the light reflection characteristics between the nonmagnetic material filled in the grooves between the magnetic tracks and the thick grooves between the zones and the magnetic material for magnetic recording of the magnetic tracks. .

  According to a third aspect of the present invention, adjacent magnetic tracks are separated in advance by a groove, a zone is constituted by a plurality of the magnetic tracks, and a thick groove wider than the groove is provided between the adjacent zones. And a head for recording / reproducing data on the magnetic disk medium, and a diameter of a light spot generated on the surface of the magnetic disk medium when the magnetic disk medium is irradiated with light from the head. Light irradiation means covering the width of the head, position error signal detection means for detecting a position error signal between the head and the magnetic track in the zone by a push-pull method, and a signal obtained from the position error signal detection means And a positioning means for positioning the head on the magnetic track.

  According to the third aspect of the present invention, in the magnetic disk device incorporating the magnetic disk medium according to the present invention, first, the magnetic disk device specifies to which magnetic track number to which zone number the head is located. For example, in order to recognize the position of the zone number of the magnetic disk device from the reference position of the head, the groove between the magnetic tracks and the thick groove between the zones are read from the read signal as the head moves in the magnetic track direction. By detecting the difference in width, the number of zones is counted to recognize the zone number.

  In order to specify the magnetic track number in the zone, for example, the relationship between the head deviation from the center of the zone and the median value of each magnetic track is obtained in advance, and the detected relative position of the zone and the head is determined. The position of the magnetic track number is specified from the value of.

  In order to perform head tracking control at a predetermined magnetic track number at a predetermined zone number, a value obtained in advance from the relationship between the relative position of the zone and the head with respect to the median value of the magnetic track at the predetermined magnetic track number is used as a reference value. As a result, the actually measured value is brought close to this reference value.

  Furthermore, in order to specify the head position from the circumferential starting point of the magnetic track at a predetermined magnetic track number, for example, starting point information is written in advance at the starting point position of each magnetic track, and this is read to determine the starting point. It comes to recognize.

  A fourth aspect of the present invention is the magnetic disk apparatus according to the third aspect, wherein the diameter of the light spot by the light irradiation means is substantially equal to the width of the zone.

  According to the fourth aspect of the present invention, for example, the surface of the magnetic disk medium is irradiated with laser light emitted from a laser light source mounted on the head, and the diameter of the spot generated on the surface of the magnetic disk medium is approximately equal to the zone width. To be. The 0th-order diffracted light and the ± 1st-order diffracted light reflected from the zone and the thick groove are received by the two-part photo detector. Since the light intensity balance of the ± 1st order diffracted light changes depending on the relative position of the light spot position with respect to the zone and the thick groove, the light amount difference of the ± 1st order diffracted light is detected by the push-pull method, and the relative position signal for the head zone The tracking control of the head for each magnetic track in the zone is performed using this relative position signal.

  By setting the diameter of the light spot generated on the surface of the magnetic disk medium to be a light spot diameter substantially equal to the width of the zone, when the center position of the spot moves onto the magnetic track located at both ends of each zone, It is possible to improve the accuracy of detecting the relative position with respect to each zone of the head by the push-pull method so that the outer periphery of the spot does not cover the adjacent zone beyond the thick groove.

  According to a fifth aspect of the present invention, adjacent magnetic tracks are separated in advance by a groove, a zone is constituted by a plurality of the magnetic tracks, and a thick groove wider than the groove is provided between the adjacent zones. A head for recording / reproducing data on the magnetic disk medium, and the diameter of the light spot generated on the surface of the magnetic disk medium by irradiating light from the head covers the width of the thorn; A tracking method characterized by detecting a position error signal with the magnetic track in the zone by a push-pull method, and positioning the head on the magnetic track based on a signal obtained from the position error signal detecting means. It is.

  According to the present invention, in the case of increasing the track density using the DTR method in a magnetic disk medium, the head can be continuously controlled in the circumferential direction with respect to a predetermined magnetic track, and high-precision head tracking can be achieved. It becomes possible.

  Furthermore, as compared with a method in which servo signals are continuously written on the magnetic track itself, it is possible to provide a superior technique in terms of space and reliability, and a manufacturing yield is large.

  FIG. 2 shows an embodiment of a magnetic disk medium according to the present invention.

  A plurality of magnetic tracks 23 are provided concentrically with respect to the center hole 22 of the magnetic disk medium 21. Referring to an enlarged view of a portion B of the AA ′ cross section in which the vicinity of the magnetic track 23 is a detailed cross-sectional view, the magnetic track 23 formed on the surface of the magnetic disk medium 21 is separated by a groove 27 and further a predetermined number of A zone 26 is formed from the magnetic track 23, and the zone 26 is separated from the adjacent zone by a thick groove 28.

  The magnetic disk medium 21 is made of, for example, aluminum or glass, and the magnetic track 23, the groove 27, and the thick groove 28 are formed by a thin film forming technique.

  The magnetic track 23 may be formed of a magnetic recording layer (not shown) from the bottom portion to the surface of the groove 27, or a part of the surface may be formed of a magnetic recording layer.

  As an example, in the figure, if the width of the magnetic track 23 is 50 nm, the width of the groove 27 is 40 nm, and the width of the thick groove 28 is 210 nm, the zone 26 is composed of five magnetic tracks 23 and the width of the zone is 410 nm. The pitch of the magnetic tracks 23 is 90 nm.

  Here, a plurality of magnetic tracks 23 may be provided on both sides of the magnetic disk medium 21. The magnetic recording layer provided on the magnetic track 23 may be an in-plane magnetic recording material or a perpendicular magnetic recording material.

  Further, the groove 27 and the thick groove 28 may be filled with a nonmagnetic filler so as to be the same as the surface of the magnetic track 23.

  FIG. 3 is an explanatory diagram of application of the push-pull method according to the present invention.

  a) illustrates a two-divided photodetector 31, and b) illustrates details of a cross section of a magnetic disk medium 30 according to the present invention.

  The magnetic tracks 301 formed on the surface of the magnetic disk medium 30 are separated by a groove 302 to form a zone 304, and the zone 304 is separated by an adjacent zone 304 and a thick groove 303.

  In the figure, for example, if the width of the magnetic track 301 is 50 nm, the width of the groove 302 is 40 nm, and the width of the thick groove 28 is 210 nm, the zone 304 is composed of five magnetic tracks 23 and the width of the zone is 410 nm. The pitch of the magnetic tracks 23 is 90 nm.

  An incident light beam 305 of laser light from above the magnetic disk medium 30 irradiates the surface of the magnetic disk medium 30 with an incident light beam 305 having a spot diameter of 420 nm, and the reflected light is received on the light receiving surface of the two-divided photodetector 31 (surface in the figure). Condensed to

  For the purpose of explanation, the center of the incident light beam 305 on the surface of the magnetic disk medium 30 is drawn so as to be located at the center of the zone 304. The reflected light of the incident light beam 305 is adjusted so as to be positioned at the center of the light receiving surface of the two-divided photodetector 31.

  On the light receiving surface of the two-divided photodetector 31, the 0th-order reflected light 313, the + 1st order reflected light 314, and the −1st order reflected light 315 are received by the light receiving surfaces of the photodetectors A311 and B312. An error signal 317 is output as a voltage difference by the operational amplifier 316 with the difference in the amount of light received between the A311 and the photodetector B312.

  In this figure, the amounts of light received by the photodetectors A311 and B312 are depicted as being balanced and receiving the same amount of light.

  As the magnetic disk medium 30 moves to the left or right with respect to the incident light beam 305, an error signal 37 corresponding to the amount of movement is detected.

  FIG. 4 is an explanatory diagram of the tracking servo system according to the present invention.

  When the surface of the magnetic disk medium 40 of the present invention is irradiated with a light spot 44 and the center of the light spot 44 is located at the center of a zone 46 having a plurality of magnetic tracks 41, a servo error signal is output from a photodetector (not shown). 0 is detected (detected as an output difference between the light detector A 311 and the light detector B 312 in FIG. 3).

  When the magnetic disk medium 40 moves left and right, the center of the light spot 44 with respect to the magnetic disk medium 40 moves, and the position within the zone 46 at the center of the light spot 44 (the position within the zone at the center of the light spot) and the servo error signal output are Draw a curve as shown.

  In order to know the servo error signal output at the center of a predetermined magnetic track 41 in the zone 46 and keep the servo error signal output, for example, an R / W head with a laser light source attached is provided. The head slider (not shown) performs position control in the track direction (head tracking control).

  FIG. 5 shows an embodiment of a head according to the invention.

  A) Head and disk medium The figure shows an outline of the head 50 with respect to the magnetic disk medium 51. The head slider 501 is instructed by the support spring 502 and floats on the surface of the rotating magnetic disk medium 51.

B) An enlarged view of the C section shows an enlarged view of a portion having an R / W (read / write) head.
The head slider 501 floats with a flying gap 52 with respect to the rotating disk medium 51. An R / W portion 503 that is an R / W head is formed at one end of the head slider 501 by a thin film head forming technique. Further, the optical unit 504 is formed using the thin film magnetic head forming technique so as to cover the R / W unit 503, the center of the laser spot light 505 is on the center line of the core width of the R / W head, and In the vicinity of the R / W unit 503, the surface of the magnetic disk medium 51 is irradiated. The surface of the optical unit 504 is covered with a protective layer, for example, a silicon layer.

  C) A perspective view from the direction D is an enlarged view of the head and disk medium diagram as viewed from the direction D obliquely from the front to the back of the figure. The head slider 501 is supported by a support spring 502, and the write head portion of the R / W portion 503 is a so-called perpendicular magnetic recording write head including an auxiliary magnetic pole 5031, a winding coil 5032, and a main magnetic pole 5033. A GMR head (or TMR head) is not shown as a head hidden behind the auxiliary magnetic pole 5031.

  A lead wire 5034 required for the R / W unit 503 is connected to one end of an FPC (not shown) affixed to the support spring 502 in the terminal part I. Further, the other end of the FPC is not shown. Connected with.

  Further, the optical unit 504 passes through the laser light source 5041, the hologram lens 5042 provided in front of the laser light source 5041 for irradiating the surface of the magnetic disk medium 51 with a desired light spot diameter, and the hologram lens 5042. The laser beam (shown by a bold line in the figure) passes through the beam splitter 5043 and is changed in direction by the reflection mirror I 5044, and further changed in direction by the reflection mirror II 5045, and the laser spot beam 505 is applied to the surface of the magnetic disk medium 51. Irradiate. The laser beam reflected from the surface of the magnetic disk medium 51 enters the two-divided photodetector 5046 via the reflection mirror II 5045, the reflection mirror I 5044, and the beam splitter 5043, and as a servo error signal output via the lead wire 5047 to the terminal portion II. 1 is connected to one end of an FPC (not shown) attached to the support spring 502, and the other end of the FPC is connected to a tracking control circuit provided in a magnetic disk device (not shown).

Magnetic disk medium of conventional magnetic disk device An embodiment of a magnetic disk medium according to the present invention Explanatory drawing of push-pull method application according to the present invention Illustration of tracking servo system according to the present invention An embodiment of a head according to the present invention

Explanation of symbols

1, 21, 30, 40, 51 Magnetic disk medium 2, 22 Center hole 3 Servo pattern area 4 Data area 5, 23, 41 Magnetic track 26, 46 Zone 27, 42 Groove 28, 43 Thick groove 31 2-split photo detector 44 Light Spot 45 Center position of light spot 50 Head 52 Flying gap

Claims (5)

A magnetic disk medium in which magnetic tracks adjacent to each other are separated in advance by grooves,
A plurality of the magnetic tracks constitute a zone;
A magnetic disk medium characterized in that a wide groove wider than the groove is provided between the adjacent zones.   2. The magnetic disk medium according to claim 1, wherein a magnetic layer for performing magnetic recording is provided on at least a surface portion of the magnetic track, and the groove and the thick groove are a magnetic disk medium filled with a nonmagnetic material. Magnetic disk medium. Magnetic disk media in which magnetic tracks adjacent to each other are separated in advance by a groove, a zone is constituted by a plurality of the magnetic tracks, and a thick groove wider than the groove is provided between the adjacent zones;
A head for recording and reproducing data on the magnetic disk medium;
A light irradiating means for irradiating the magnetic disk medium with light from the head, and a diameter of a light spot generated on a surface of the magnetic disk medium covering a width of the thorn;
Position error signal detection means for detecting a position error signal between the head and the magnetic track in the zone by a push-pull method;
A magnetic disk apparatus comprising: positioning means for positioning the head on the magnetic track based on a signal obtained from the position error signal detecting means.   4. The magnetic disk apparatus according to claim 3, wherein the diameter of the light spot by the light irradiation means is substantially equal to the width of the zone. Adjacent magnetic tracks are separated in advance by grooves, and a plurality of magnetic tracks form a zone, and a magnetic disk medium in which a thick groove wider than the groove is provided between the adjacent zones is used for data storage. Having a head for recording and playback,
The diameter of the light spot generated on the surface of the magnetic disk medium when irradiated with light from the head covers the width of the thorn,
A position error signal between the head and the magnetic track in the zone is detected by a push-pull method,
A tracking method comprising positioning the head on the magnetic track based on a signal obtained from the position error signal detecting means.

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