JPH04141822A - Magnetic disk and magnetic disk device - Google Patents

Abstract

PURPOSE:To allow the discrimination as to on which of an inner side or outer side an off track arises by forming the above disk to such a shape that the depth of the grooves between magnetic particle tracks increases monotonously in the transverse direction of the grooves. CONSTITUTION:The depth of the grooves 3 to be eventually positioned below sensors when the sensors attain the offtrack state is varied on the outer side and the inner side. Namely, the grooves 3 are formed to such shape that the depth thereof increases monotonously in the transverse direction of the grooves 3. The electrostatic capacities of the sensors 11, 12 consisting of conductive thin films of Ni, Cu, etc., are measured at all times during tracking. On which of the inner side or outer side the offtrack arises is discriminated when the monotonous increase or decrease of the electrostatic capacity is detected by either of the sensors. On which of the inner side or outer side the offtrack arises is discriminated in this way.

Description

[Detailed Description of the Invention] [Summary] Regarding the magnetic disk and magnetic disk device installed in a magnetic disk device used as an external storage device of a computer, off-track occurs on either the inner side or the outer side. The purpose of the present invention is to provide a magnetic disk and a magnetic disk device that can determine whether the recording track is in a magnetic disk or a magnetic disk device. The grooves may be provided with a shaped groove, or the depth of the groove may be alternated between adjacent tracks.

[Industrial application field]

The present invention relates to a magnetic recording medium installed in a magnetic disk device used as an external storage device of a computer, and particularly to a technique for increasing track density necessary to realize high-density recording. The present invention also relates to such a magnetic disk device.

In recent years, with the miniaturization and increase in capacity of magnetic disk devices, it has become important to improve recording density. The recording density is expressed as the r-line recording density J in the circumferential direction of the disk and the r-track recording density in the radial direction, and compared to the optical recording method that is synonymous with high-density recording, the r-line recording density 1 is superior. However, the r-track recording density 1 has decreased significantly, and improvement of this has become a major issue.

[Conventional technology]

In order to achieve both prevention of magnetic interference from adjacent tracks and high-precision positioning, which is an issue in increasing track density,
A magnetic disk with pre-groups in which grooves are provided between tracks has come to be considered.

FIG. 8 shows the media surface structure of a magnetic disk with pre-group. In the figure, 1 is a substrate usually made of N1-P plated aluminum, glass, or ceramic, 2 is a recording layer made of a magnetic material with a very thin film thickness of usually 0.1 μm or less, and 3 is 0.3~ The grooves (groups) have a depth of 0.4 μm.

As shown in Figure 8, the magnetic disk with pre-group is
Recording N2 corresponding to the track width of the data area 21;
The groove 3 is configured to cut off the recording layer 2 of the track directly above the probe from the recording N2 of the adjacent track. Track positioning can be performed with high accuracy due to changes in the capacitance of the groove 3 and a positioning detection element attached to a signal detector such as a magnetic head.

Furthermore, the presence of the groove 3 prevents writing blur that occurs during recording, and reduces crosstalk noise.

[Problems to be Solved by the Invention] In the track positioning method using grooves described with reference to FIG. Even though I knew that a truck had occurred, I couldn't tell whether it was off-track to the inch side or the outer side. In this case, accurate information for returning the probe from off-track to its normal track position could not be obtained, and the amount of off-track sometimes increased.

Therefore, an object of the present invention is to provide a magnetic disk and a magnetic disk device that can determine whether off-track occurs on the inch side or the outer side.

[Means for Solving the Problems] A first magnetic disk according to the present invention is a magnetic disk having grooves between recording tracks, in which the depth of the grooves increases monotonically in the width direction of the grooves. It is characterized by having a groove having such a shape.

A second magnetic disk according to the present invention is characterized in that, in a magnetic disk having grooves between recording tracks, the depth of the grooves between adjacent tracks is alternately changed.

A first magnetic disk device according to the present invention includes a first or a second magnetic disk device.
The first magnetic disk includes a magnetic disk and a magnetic head, and is characterized in that capacitance sensors are attached to both sides of the magnetic head in the width direction of the groove of the first magnetic disk.

The second magnetic disk device according to the present invention has a
A magnetic disk is included, and a single capacitive sensor is attached, which has the same width as the magnetic pole part in the width direction of the groove, and has a shape such that the tip of the disk facing surface exists only on both sides of the magnetic pole. shall be.

[Effect]

In order to solve the above-mentioned problem, the invention as claimed in claim 1 has a cross-sectional shape of the groove, in which the bottom part is conventionally flat, but is asymmetrical, that is, the depth of the groove is different on the inch side and the outer side. It was made differently. The shape of the groove from the inner side to the outer side is determined so that the depth increases monotonically, that is, does not increase discontinuously. If the depth increases discontinuously, the detection accuracy of the groove depth tends to be disturbed, which is not preferable for accurate tracking.

In order to achieve the above object, the invention as claimed in claim 2 has a structure in which the groove depths between adjacent tracks are alternately changed. Since the groove depths on both sides of the recording track are different, the degree of change in the groove depth during off-track is different depending on whether the groove is shifted toward the inch side or when it is shifted toward the outer side. As a result, since the direction of displacement of the magnetic head can be recognized, accurate tracking can be performed.

To detect off-track when magnetically recording and reproducing the above-mentioned magnetic disk, it is possible to employ an optical detection means to physically detect the depth of the groove, but this method is used in VHD etc. It is preferable to adopt a capacitance detection method.

In the magnetic disk drive of the present invention, capacitance detection sensors are provided on both sides of the magnetic head in the width direction of the groove (claim 3), or a single capacitance sensor is provided (claim 3).
Claim 4) The magnetic head is caused to off-track,
As soon as the sensor on either side is positioned above the groove, a change in capacitance occurs and is detected by the sensor, and as the sensor moves across the width of the groove, a monotonous increase or decrease in capacitance is detected. .

The tracking method in the magnetic disk device according to claim 1 includes the following:
It is preferable to determine which of the adjacent grooves is off-track by a monotonous increase or decrease in capacitance, correct the position of the magnetic head toward the other adjacent groove, and return it to the recording track. In this method, the capacitance of two sensors is constantly measured during tracking, and if a monotonous increase or decrease in capacitance is detected by either sensor, off-tracking occurs on either the inner or outer side. It is determined whether the Next, the position of the magnetic head is corrected from the off-track side to the opposite side. Constantly monitor the capacitance change signal that occurs during this position correction,
Feedback is applied so that the capacitance value is on track.

In the tracking method in the magnetic disk device according to claim 2, when the magnetic head deviates from the recording track,
One of the adjacent grooves that is off-track is determined based on the magnitude of the electrostatic capacitance, and the position of the magnetic head is corrected toward the other adjacent groove to return it to the recording track. In this tracking method, when the detected capacitance is large (small), the position of the head is corrected toward the groove on the small (large) side.

〔Example〕

Hereinafter, one embodiment of the present invention will be described while comparing it with a conventional example.

FIG. 1 is a block diagram showing an embodiment of the present invention (claim 1), and shows a cross section of a recording medium. FIG. 2 is a block diagram showing another embodiment, and shows a cross section of the recording medium as described above. In the figure, parts similar to those in FIG. 8 are designated by the same reference numerals. In FIG. 1, the bottom surface 3a of the groove 3 is formed of an inclined surface with a constant slope, and in FIG. 2, the bottom surface 3a of the groove 3 is formed of a curved surface with a varying slope. The depth of the groove 3 is preferably twice or more.

In the magnetic recording medium shown in FIGS. 1 and 2, the depth of the groove 3 that is located below the sensor when the sensor is in an off-track state is made different on the outer side and the inner side. The direction of the shift can be determined from the change in capacitance.

As a result, it is possible to easily maintain an on-track state.

FIG. 3 shows Ni on the recording medium of FIG.

This shows that the sensors 11 and 12, which are made of conductive thin films such as Cu, are on track. In FIG. 3, the capacitance is maximum when the sensor is on-track, and decreases when off-track occurs. That is, the capacitance (C,,,C,,) detected between the sensor 11.12 and the substrate 1 is CI l 2C@
It is expressed as am + CI□=C1,8. When off-tracking on the width of the sensor 11 to the left side (inner side) in the figure, the capacitance C++, C1□ detected by the sensor 11.12 is C+ + = C,'< C□8... (1
) C12” Cman... (2)
becomes. That is, when the capacitance (change) of (1) or (1) and (2) is detected, it is determined that off-tracking to the inch side is occurring.

Furthermore, when offtracking to the inch side, C,,=c″
<C'<C,,, ---(3) C1□=C□8
...(4), so from the relationship of equations (1) and (3), it is determined that the capacitance detected by the sensor 11 is smaller (as it becomes smaller, it is further shifted toward the inner side) .

The off-track toward the inch side has been described above, but if an off-track of the width of the sensor 120 or more occurs on the right side, the capacitance will once rapidly decrease and then increase. Therefore, if the capacitance increases, the head position is adjusted to the left, and if it decreases, the head position is adjusted to the right, and feedback is provided so that the capacitance reaches the maximum value.

Note that the above is limited to the case of two capacitance sensors, but even in the case of a single capacitance sensor, it is the same as CII + CI2 connected in parallel, so it is the sum of (1) and (2), and the same can be handled. That is, as shown in FIGS. 9 and 10, a single electrostatic capacitor having the same width as the magnetic pole portion 40b and a shape such that the tip portions 31a and 31b of the disk facing surface are present only on both sides of the magnetic pole portion 40b. The capacitive sensor 30 can determine whether the vehicle is on track or off track.

In FIG. 2, the bottom shape of the groove is curved. Basically, for off-track, the same capacitance change as in the case of FIG. 1 occurs.

The same effect can be obtained if the groove shape is one in which the depth constantly changes, such as a step shape, and the depth monotonically increases in the radial direction within the groove width. Needless to say.

FIG. 4 is a schematic cross-sectional view showing the outline of the present invention (claim 2). The feature of this medium is that it is a grouped magnetic disk in which the depth of the grooves formed between adjacent tracks differs on the left and right sides of the recording track. In other words, 3a is a shallow groove;
b is a deep groove.

10 is a magnetic head.

5 and 6, the magnetic head 10 is located directly above the recording tracks 21b and 21a, respectively, and the magnetic head 10 is located directly above the recording tracks 21b and 21a,
This shows a situation where the vehicle is off-track at the '10' position.

In the present invention, since the depths of the grooves 3 on both sides of the recording track 21 are different, the degree of change in capacitance during off-track also varies even in combination with strip-shaped electrodes (capacitance sensors) on both sides of the magnetic head. It can be detected differently depending on whether it is shifted toward the inner side (see 10 to 10 in FIG. 5.6) or toward the outer side (see 10' in FIG. 5.6). That is, the fifth
In the figure, the capacitance C' at 10' and the capacitance C'' at 10'' become C'<C'. Furthermore, when detecting capacitance at 3b (deep groove), on-track is 21b.
If the on-track is 21a, move it to the inner side, and if the on-track is 21a, move it to the outer side. As a result, the direction of displacement of the magnetic head can be recognized, so accurate tracking can be performed.

A method of manufacturing the magnetic disk according to the embodiment of the present invention (FIG. 4) will be explained with reference to FIGS. 7(a) to (k).

A positive photoresist is applied to a pre-cleaned glass substrate 1 using a spin coater to a thickness of about 1 to 1.5 μm to form a resist layer (see FIG. 7(a)), and then patterned at a pitch of 3 μm in advance. Exposure is performed on concentric circles using a mask 32 (see FIG. 7(b)). Next, after developing and fixing the exposed portions of the photoresist layer 31 to remove them (see FIG. 7(c)), etching was performed using an ion mill to form group 3 grooves with a depth of 0.4 μm.
3 (see FIG. 7(d)). After removing the photoresist layer 31 (see FIG. 7(e)), a positive photoresist 34 is applied again using a spin coater to fill the etched grooves (see FIG. 7(f)). Next, exposure is performed using the mask 35 for every other track (Fig. 7(g)).
After developing and fixing to remove the exposed portion of the photoresist layer (see No. 7 (g)), etching was performed using an ion mill to form group 3 grooves with a groove depth of 0.8 μm.
6 (see FIG. 7(h)).

After etching is completed, the photoresist 34 is removed using a plasma etching device (see FIG. 7(i)). This forms alternating groups 33, 36 with groove depths of 0.4 .mu.m and 0.8 .mu.m (see FIG. 7(i')).

Next, on this substrate 1 with groups, C is
An r layer 37 is formed to a thickness of about 0.15 μm (see FIG. 7(j)). Thereafter, a CoCr recording layer 38 is formed to a thickness of about 0.05 μm (see FIG. 7(k)).

In the above manufacturing method, the groups are formed by etching, but the groups may also be formed by forming. Groups may be formed not only on the substrate but also on the magnetic layer or protective film.

[Effects of the Invention] As described above, according to the present invention, it is possible to determine the side on which off-track has occurred in a simple and reliable manner.

[Brief explanation of drawings]

1 is a schematic structural diagram of a magnetic disk with groups according to an embodiment of the invention as claimed in claim 1; FIG. 2 is a schematic structural diagram of a magnetic disk with groups according to an embodiment of the invention as claimed in claim 1; FIG. 4 is a schematic diagram of the structure of a magnetic disk with groups according to an embodiment of the invention as claimed in claim 2. FIG. 5 and FIG. 4 is a schematic diagram of the off-track state of the magnetic disk, FIGS. 7(a) to (k) are manufacturing process diagrams of the magnetic disk according to claim 2, and FIG. 7(a) is a photoresist process, Figure 7(b) is the photoresist exposure process, Figure 7(c)
7(d) is the group forming step, FIG. 7(e) is the next step after FIG. 7(d), FIG. 7(f) is the photoresist step, Figure 7 (g) is the photoresist process, Figure 7 (h) is the group formation process, Figure 7 (i) is the next process after Figure 7 (h), and Figure 7 (j) is the Cr layer soot battering process. (k) corresponds to the CoCr recording layer recording lath batter process, FIG. 8 is a schematic structural diagram of a conventional grouped magnetic disk, and FIGS. 9 and 10 are drawings showing an example of a single sensor. 1-substrate, 2-recording layer, 3-groove (group), 11.1
2-Capacitance sensor, 10-Magnetic head, 21-Data area (Figure 3) Figure 3

Claims (1)

[Scope of Claims] 1. A magnetic disk having grooves between recording tracks, characterized by having grooves having a shape such that the depth of the grooves increases monotonically in the width direction of the grooves. magnetic disk. 2. A magnetic disk having grooves between recording tracks, characterized in that the depth of the grooves between adjacent tracks is alternately changed. 3. A magnetic disk device comprising the magnetic disk and magnetic head according to claim 1 or 2, characterized in that capacitance sensors are attached to both sides of the magnetic head in the width direction of the groove of the disk. 4. A groove comprising a magnetic disk and a magnetic head according to claim 1 or 2, and having the same width as the magnetic pole part in the width direction of the groove,
A magnetic disk drive characterized in that a single capacitance sensor is attached, the tip of the disk facing surface being located only on both sides of the magnetic pole.