JP2002334430A - Method and device for magnetic disk transfer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect foreign objects containing particles at low costs by a compact device when a particular magnetic pattern is recorded on a magnetic disk by a magnetic transfer system. SOLUTION: The inspection of foreign objects such as particles on the surface of a magnetic disk or a master disc surface is carried out by using an illumination unit 15 having a linear parallel light source 18, and a foreign object inspection head 14 having a linear sensor unit 16. Thus, miniaturization and low costs are achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is written on the surface of a magnetic recording disk in a hard disk drive (HDD) using a magnetic film as a recording material, which is now mainstream as an external storage device of a computer. The present invention relates to a method and an apparatus for writing a servo signal for positioning a magnetic head for writing / reading data or specific data using a magnetic transfer technique.

[0002]

2. Description of the Related Art Conventionally, a magnetic disk is shipped in a state where no magnetic information is written therein, and is incorporated in an HDD device, and thereafter, magnetic information necessary for the HDD device is written.
In the HDD, a magnetic disk is magnetically partitioned into concentric tracks having a fixed width, and data is read and read while a head follows the track.
Write. The HDD detects a head displacement from a magnetic signal called a servo signal written on a track, and controls the head so as not to deviate from the track. This operation is called track servo.

However, in order to write servo signals precisely concentrically on a magnetic disk on which nothing is written, a device having a precise position control function is required. In order to insert the HDD more, the work is done to prevent dust from entering the HDD.
This had to be done in a clean room. Also, it takes several tens of minutes to write servo signals on tens of thousands of tracks on one surface while performing precise alignment. As described above, it is necessary to perform this servo signal writing operation for each HDD in a clean room, and since a high-precision device is used, this is a major factor in increasing the manufacturing cost of the HDD.

[0004] A technique is known in which a special disk for magnetic transfer called a master disk having the above-described servo signal pattern is brought into close contact with the magnetic disk and a magnetic field is applied from the outside to transfer the servo signal pattern instantaneously. Equipment is being developed. As a result, it is possible to reduce drive manufacturing costs and further increase the track density (narrow the track width). However, since the magnetic transfer is performed while the master disk is brought into close contact with the magnetic disk, particles sandwiched between them cause a serious problem. In particular, particles often adhere to the outer peripheral portion while the magnetic disk is transported. The trapped particles deteriorate the adhesion between the master disk and the magnetic medium, resulting in deterioration of the quality of the transfer signal.

Prior to magnetic transfer, the surface of the magnetic disk is inspected for particles or the like, and if so, the magnetic disk is ejected without being transferred. The particle size that poses a problem in magnetic transfer is 1 to several μm. In order to detect this at high speed, the laser light emitted from a light source having a large output such as a carbon dioxide laser is squeezed into a circle of several μm or an ellipse of several μm × several μm,
This light spot is irradiated onto a magnetic disk, and the reflected light is detected by an optical sensor such as a high-sensitivity laser diode.

[0006]

However, the above-mentioned optical inspection method requires a large light source and the like, and it is necessary to adjust the optical system with high accuracy.
It becomes very expensive. There is also a problem that the size of the inspection unit cannot be reduced, so that the transfer device itself cannot be downsized. Therefore, an object of the present invention is to reduce the cost without increasing the size of the device.

[0007]

According to the first aspect of the present invention, a master disk having a predetermined magnetic pattern is brought into close contact with a magnetic disk to apply a magnetic field from the outside, and the predetermined magnetic pattern is applied. In the magnetic disk transfer method of transferring a pattern onto a magnetic disk, the magnetic disk is inspected for foreign matter adherence by irradiating a predetermined portion of a relatively rotating magnetic disk before magnetic transfer. In this case, the light is detected by detecting the light from an area with a line sensor.

According to the first aspect of the present invention, the inspection can be performed on a master disk (the second aspect of the invention), or the inspection can be performed on the master disk using the same line sensor. (Invention of claim 3). In any one of the first to third aspects of the invention, the irradiation can be performed in a ring shape (the invention of the fourth aspect), or the irradiation can be performed by linear parallel light. Invention). Further, in the invention according to claim 5, the angle formed between the surface of the irradiated portion and the parallel light irradiated in a line is 6 degrees.
The angle can be 0 degrees or less (the invention of claim 6).

According to a seventh aspect of the present invention, in the magnetic disk transfer apparatus, a master disk having a predetermined magnetic pattern is brought into close contact with the magnetic disk and an external magnetic field is applied to transfer the predetermined magnetic pattern onto the magnetic disk. An irradiation unit and a line sensor are provided, and a predetermined portion of a relatively rotating magnetic disk is irradiated by the irradiation unit before magnetic transfer to check whether or not foreign matter adheres to the magnetic disk. Light from an area is detected and detected by the line sensor.

In the above invention, the inspection may be performed on the master disk (the invention of claim 8), or the inspection may be performed on the master disk using the same line sensor. (Invention of claim 9). In any one of the seventh to ninth aspects, the irradiation by the irradiation means can be performed in a ring shape (the invention of claim 10), or the irradiation by the irradiation means is performed by linear parallel light. (Invention of claim 11). Further, in the invention of the eleventh aspect, the angle between the surface of the irradiated portion and the parallel light illuminated linearly can be 60 degrees or less (the invention of the twelfth aspect).

[0011]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention. In the figure, 1 is a magnetic disk transfer device, 2 is a cassette stage (entrance), 3 is a cassette stage (exit), 4 is a disk handler, 5 is a disk holding and feeding mechanism, 6 is a vacuum suction head, and 7 is a cleaning. , 8 a foreign matter inspection unit, 9 a magnetic erase unit, 10 a magnetic transfer unit, 11 a disk cassette, and 12 a magnetic disk.

In such a configuration, the magnetic disk 1
2 are usually put into the disk cassette 11 by 25 sheets, and are conveyed to the cassette stage 2 which is the transfer apparatus input port by the conveyor of the production line. The cassette stage 2 has a mechanism for pushing the disks up from the gap below the cassette, and raises the magnetic disks 12 one by one to the upper part of the disk cassette 11. The disk handler 4 has an inner peripheral chucking mechanism, inserts the chucking mechanism in a closed state on the inner periphery of the protruded magnetic disk 12, and then holds the magnetic disk 12 by opening the chucking mechanism.

The disk handler 4 holding the magnetic disk 12 rotates the held magnetic disk by a rotation operation of 180 degrees in the horizontal direction and a rotation operation of 90 degrees in the vertical direction thereafter. Attach to part 5. The transfer operation of the magnetic disk mounted on the disk holding / feeding mechanism 5 is performed in the transfer device 1 in four stages as illustrated in FIG. The disk holding / feeding mechanism unit 5 is constituted by assembling six arms having a vacuum suction head 6 for vacuum-holding and holding the inner peripheral portion of the disk at the tip end thereof at an equal angle. While the disk holding / feeding mechanism 5 makes one rotation on the horizontal plane, the magnetic disk 12 held in the. The remaining two stages are used for loading and unloading the magnetic disk.

The above-described transfer operation is performed in four steps of cleaning, foreign substance inspection, magnetic erasure and magnetic transfer. For the magnetic disk 12 held by the disk handler 4 on a surface different from the magnetic transfer surface, the cleaning unit 7 performs a cleaning process on the magnetic transfer surface. As the cleaning process, there is a so-called tape cleaning system in which the tape is brought into contact with the medium surface to remove particles. By such a cleaning process, particles near the outermost peripheral portion, which do not cause a problem particularly when a normal magnetic disk is used but cause a problem in magnetic transfer, are removed.

Next, the magnetic disk is optically inspected by a foreign substance inspection unit 8 to determine whether or not particles adhere to the magnetic transfer surface of the magnetic disk 12. As a result of this inspection, the magnetic disk 12 that has been determined to be free of particles that pose a problem in magnetic transfer should be magnetically erased on the magnetic transfer surface in the magnetic eraser 9 and then transferred in the magnetic transfer unit 10. It is brought into close contact with a master disk having a magnetic pattern, and magnetic transfer processing is performed. The magnetic disk 12 that has completed the magnetic transfer is transferred by the disk handler 4 to the disk cassette 11 waiting on the cassette stage 3 for exit. By the foreign matter inspection unit 8,
The magnetic disk 12, which is determined to have particles that cause a problem in the magnetic transfer, is skipped by the magnetic erase process and the magnetic transfer process, and is discarded as a defective disk.

FIG. 2 shows an example of the configuration of the foreign matter inspection unit 8. That is, the magnetic disk 12 is chucked by the spindle motor 13 and rotates at a constant speed. Magnetic disk 12
The upper particles are inspected by the foreign matter inspection head 14. The foreign matter inspection head 14 includes an illumination unit 15 and a line sensor unit 16. Lighting unit 1
Numeral 5 irradiates the surface of the magnetic disk 12 with parallel light elongated in the radial direction at a low angle. Most of the light reflected on the surface of the magnetic disk 12 passes in the opposite direction at the same angle as the incident angle. If foreign matter is present on the magnetic disk surface,
The incident light is scattered at that portion, and is detected by the line sensor unit 16 placed vertically on the surface of the magnetic disk 12. The reflected light detection signal from the line sensor unit 16 is input to the determination unit 17.

FIG. 3 shows a line sensor inspection area of the foreign substance inspection unit. The irradiation area 19 is an area irradiated by the parallel light from the illumination unit 15. Line sensor inspection area 2
Reference numeral 0 denotes an area to be inspected by the line sensor unit 16. If a foreign substance is present in this area, scattered light is generated, and an electric signal is applied to a pixel which is one or more light detection units of the line sensor corresponding to the position. Is induced. The signal of the line sensor is sent to the determination unit 17 for each pixel, and the signal level is compared with a certain threshold value. If there is a pixel signal exceeding the threshold value, it is determined that scattered light exceeding the setting has occurred in the corresponding pixel portion.

FIG. 4 is a diagram illustrating the relationship between the particle size and the scattered light intensity. As is clear from the figure, until the particle size reaches a certain size, there is a proportional relationship between the particle size and the scattered light intensity, and in that portion, the particle size can be determined based on the scattered light intensity. Therefore, by using this relationship, it is possible to detect the presence of particles of a certain size or more based on the threshold value for the signal level from the line sensor.

FIG. 5 shows the relationship between the incident angle of the irradiation light and the scattered light. As shown in the figure, the intensity of the scattered light increases as the incident angle approaches the vertical, but the intensity of the light reflected from the surface of the magnetic disk rapidly increases at a certain angle or more. Therefore, the incident angle of the irradiation light is appropriate up to 60 degrees (60 degrees or less) with respect to the magnetic disk surface.

FIG. 6 shows an example of an output signal from the line sensor unit 16 which is detected as the magnetic disk rotates. The scattered light intensity is output from the inner circumference to the outer circumference at the radial position for each specific rotation angle. If a particle exists at a certain position, a peak appears at the corresponding output position of the line sensor, and the particle size can be detected based on this intensity level. FIG. 7 shows another example of illumination, showing that not only elongated parallel light but also ring illumination 21 is possible. In a specific circular portion under illumination (ring-shaped illumination area 22), light from a light source arranged in a ring shape gathers from the periphery, but light reflected by the magnetic disk 12 does not go in a direction perpendicular to the surface of the magnetic disk. It is reflected in the vertical direction only when scattered light occurs. This allows
As in the case of the linear parallel light, particles on the surface of the magnetic disk can be detected.

FIG. 8 shows a magnetic transfer step. Magnetic transfer is
It is performed in two stages of magnetic erasing and magnetic pattern transfer performed by closely attaching the master disk 25. In magnetic erasing, the entire surface is erased by rotating the erasing magnet 23 once while keeping a fixed distance on the magnetic disk 12. The magnetic pattern transfer is performed by rotating the transfer external magnet 24 having a magnetic field in a direction opposite to that of the erase operation once while keeping a fixed distance, with the master disk 25 being in close contact with the magnetic disk 12.

FIG. 9 shows the configuration of the master disk 25.
As shown, the transfer magnetic pattern 26 formed on the surface
Is usually formed in a pattern having a width of about 1 μm,
The magnetic transfer process is performed between the master disk 25 and the magnetic disk 12 on which magnetic transfer is to be performed, while maintaining the adhesion of about one tenth to one-tenth of the pattern width. In the above description, the case where the foreign substance on the magnetic disk as the transfer medium is inspected is mainly described.

[0023]

According to the present invention, foreign matter inspection on the surface of a magnetic disk or a master disk before magnetic transfer is performed.
Since line-shaped or ring-shaped illumination is used, and scattered light due to projections of particles or the like existing on the surface is detected using a line sensor, a small-sized, low-cost, and high-speed foreign substance inspection can be performed.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of a foreign substance inspection unit according to the present invention.

FIG. 3 is a diagram illustrating a relationship between a light source irradiation area and a line sensor inspection area.

FIG. 4 is a diagram illustrating the relationship between particle size and scattered light intensity.

FIG. 5 is a diagram illustrating the relationship between the incident angle of illumination light, the intensity of scattered light, and the intensity of light reflected from the surface of a magnetic disk.

FIG. 6 is an explanatory diagram of a line sensor output.

FIG. 7 is a configuration diagram illustrating an example of a ring-shaped illumination.

FIG. 8 is a conceptual diagram illustrating a magnetic transfer step.

FIG. 9 is an explanatory diagram showing a configuration example of a master disk.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic disk transfer apparatus, 2 ... Cassette stage (entrance), 3 ... Cassette stage (exit), 4 ... Disk handler, 5 ... Disk holding / feeding mechanism part, 6 ... Vacuum suction head, 7 ... Cleaning part, 8 ... Foreign matter inspection unit, 9: magnetic erasing unit, 10: magnetic transfer unit, 11: disk cassette, 12: magnetic disk, 13: spindle motor, 1
4 ... Foreign matter inspection head, 15 ... Illumination unit, 16 ... Line sensor unit, 17 ... Judgment unit, 18 ... Line parallel light source, 19 ... Light source irradiation area, 20 ... Line sensor inspection area, 21 ... Ring illumination, 22 ... Ring illumination area, 2
3: external magnet for erasure, 24: external magnet for transfer, 25: master disk, 26: magnetic pattern for transfer.

(72) Inventor Eiichi Fujisawa 1-1-1, Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (72) Inventor Shoichi Seki 1-1-1, Tanabe-Nitta, Kawasaki-ku, Kawasaki-ku, Kanagawa Prefecture No. Fuji Electric Co., Ltd. (72) Inventor Mitsugu Wada 3-11-10 Musashino, Akishima-shi, Tokyo Y-Aishi Co., Ltd. (72) Masato Yamada 3-11-10 Musashino, Akishima-shi, Tokyo Y-Ai shares F term in the company (reference) 2G051 AA71 AB01 BA00 BA20 CA03 CB01 CB05 DA01 DA08 DA13 EA16 EB01 EB02 ED07 5D091 AA10 BB08 FF02 JJ25 5D112 JJ03 JJ05

Claims (12)

[Claims] 1. A magnetic disk transfer method in which a master disk having a predetermined magnetic pattern is brought into close contact with a magnetic disk and a magnetic field is externally applied to transfer the predetermined magnetic pattern onto the magnetic disk. A magnetic disk characterized in that the inspection for adhesion is performed by irradiating a predetermined portion of a relatively rotating magnetic disk before magnetic transfer and detecting light from the irradiated area by a line sensor. Transfer method. 2. The magnetic disk transfer method according to claim 1, wherein the inspection is performed on a master disk. 3. The magnetic disk transfer method according to claim 1, wherein the inspection is performed on the master disk using the same line sensor. 4. The method according to claim 1, wherein the irradiation is performed in a ring shape. 5. The magnetic disk transfer method according to claim 1, wherein the irradiation is performed by linear parallel light. 6. The magnetic disk transfer method according to claim 5, wherein the angle between the surface of the irradiated portion and the parallel light irradiated in a line is 60 degrees or less. 7. A magnetic disk transfer apparatus for bringing a master disk having a predetermined magnetic pattern into close contact with a magnetic disk and applying a magnetic field from the outside to transfer the predetermined magnetic pattern onto the magnetic disk. Before the magnetic transfer, the magnetic disk is irradiated with a predetermined portion of the relatively rotating magnetic disk by the irradiating means, and the light from the irradiated area is irradiated with the light. A magnetic disk transfer device, wherein the detection is performed by a line sensor. 8. The magnetic disk transfer device according to claim 7, wherein the inspection is performed on a master disk. 9. The magnetic disk transfer device according to claim 7, wherein the inspection is performed on the master disk using the same line sensor. 10. The magnetic disk transfer device according to claim 7, wherein the irradiation by the irradiation unit is performed in a ring shape. 11. The method according to claim 7, wherein the irradiation by the irradiating means is performed by linear parallel light.
The magnetic disk transfer device according to any one of the above. 12. The magnetic disk transfer device according to claim 11, wherein the angle between the surface of the irradiated portion and the parallel light irradiated in a line is 60 degrees or less.