JPH09274740A - Standard optical disk for inspection, its manufacture and inspecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a defect related to required tracking abnormality, to make possible mass production and to enhance reproducibility by providing a confirming tracking pattern on a part of a track. SOLUTION: An optical disk 10 is provided with a disk like disk substrate 11 having a central hole 11a, and a reflection film, a protection film successively formed on the surface of the substrate 11. Then, a cutting machine 30 shifts a spot of a cutting beam in the radial direction from an original track answering to a signal waveform from an optional waveform generator 32, and makes meander the track. Thus, the track pattern generating a confirming tracking driving current or a tracking error signal is formed beforehand and intentionally based on the signal waveform from the optional waveform generator 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a standard optical disk for inspection, which serves as a standard for inspecting an optical disk such as a compact disk (CD), a mini disk (MD), a high density recording optical disk, etc., and a manufacturing method thereof. It relates to the inspection method.

[0002]

2. Description of the Related Art Conventionally, an optical disc has been constructed so as to have tracks configured to have a predetermined track pitch in the radial direction. An optical disk device for reproducing such an optical disk is configured as shown in FIG. 8, for example.

In FIG. 8, an optical disk device 1 irradiates a signal recording surface of a rotationally driven optical disk 2 with a light beam such as a laser beam by an objective lens 3a of an optical pickup 3. Then, the return light from the signal recording surface of the optical disc 2 is detected by a photodetector (not shown) of the optical pickup 3 via the objective lens 3a of the optical pickup 3, and based on the output signal of the photodetector, It is designed to generate a reproduction signal.

The objective lens 3a of the optical pickup 3
Are movably supported at least in the tracking direction by an actuator (not shown). The tracking servo of the objective lens 3a is performed as follows. That is, the detection signal from the optical pickup 3 is amplified by the amplifier 4 to obtain the tracking error signal TE. This tracking error signal TE is passed through a low pass filter 5 to remove high frequency components, then amplified by a drive amplifier 6 and given to a drive coil of an actuator of an optical pickup 3 as an objective lens drive current (tracking drive current) TD. To be As a result, the objective lens 3a is drive-controlled in the tracking direction so that the amount of deviation between the spot and the track on the signal recording surface of the optical disc 2 by the objective lens 3a becomes small.

Here, the optical pickup 3 generally has a natural frequency determined by the moment of inertia of the objective lens 3a, the low-pass filter 5 and the like. Therefore, when the defect of the optical disk is abnormal tracking, at least a part of the track of the optical disk meanders in a radial direction from the original position. Here, the meandering of the truck is roughly classified into two types. There are a case where the track meandering is longer than the natural frequency and a case where the track meandering is shorter than the natural frequency. When the meandering has a period longer than the period of the natural frequency, when the optical disc device 1 reproduces the optical disc 2, the optical pickup 3 follows the meandering of the track, as shown in FIG. Since the lens drive current TD largely changes and is controlled in accordance with the meandering of the track, the tracking error signal TE does not change very much.

On the other hand, when the meandering has a cycle shorter than the cycle of the natural frequency, when the optical disk 2 is reproduced by the optical disk device 1, the optical pickup 3 causes the optical pickup 3 to track the track, as shown in FIG. Since it becomes impossible to follow the meandering, the objective lens drive current TD does not fluctuate, and the tracking error signal TE largely fluctuates according to the meandering. For this reason, when the optical disk is reproduced, reproduction problems such as skipping of sounds and reproduction failure occur.

By the way, when the above-mentioned optical disc 2 is manufactured, whether or not the optical disc is manufactured correctly is inspected in the inspection process. In such inspection,
It is necessary to judge whether the track of the optical disc has the above tracking abnormality. Therefore, an inspection machine that performs such an inspection includes a system similar to the optical disc device 1 as shown in FIG.
Tracking abnormality is judged.

[0008]

On the other hand, as shown in FIG.
An inspection machine (of an optical disk) including the above system must be able to accurately detect the tracking abnormality when reproducing the optical disk. For the check, a defective inspection disk having an abnormal tracking is reproduced, whether or not a predetermined tracking abnormality is detected is confirmed, and necessary inspection machines are adjusted based on the result. The defective disk for inspection uses a defective disk actually generated in the mass production process of optical disks. For this reason, if a large number of defective discs are required in the daily inspection of the inspection process, etc., the stamper, which is the master disc of the optical disc, is intentionally scratched or the reading surface side of the normally manufactured optical disc. The desired defective disk was obtained by means such as intentionally contaminating the.

By the way, in such a defective disk, when the original disk is scratched, the same defect is reproduced, but since the defect itself becomes random, a desired defect may not be obtained. There was a problem. In addition, if the reading surface side of the optical disk is intentionally contaminated,
Since the defects vary from optical disc to optical disc, the reproducibility of defects is not substantially obtained, and there is a problem in terms of mass productivity, and the reproduced defect signal differs for each optical disc drive device. However, there is a problem that accurate calibration of the inspection process cannot be performed. Further, the defects due to contamination of the optical disc change over time as the optical disc is used, and therefore, there is a problem that it is not practical because it needs to be re-contaminated after periodical replacement or cleaning.

[0010] Particularly, regarding a defective disk relating to tracking abnormality, meandering having various periods and amplitudes is required, but if defective disks actually generated in the manufacturing process are used, the number and types thereof are limited. Therefore, it is difficult to prepare a large number of defective discs for each type required for the inspection process.

In view of the above points, the present invention has a defect relating to a desired tracking abnormality as a reference for inspection, can be mass-produced, and has good reproducibility, a standard optical disk for inspection, a method of manufacturing the same, and an inspection. It is intended to provide a way.

[0012]

SUMMARY OF THE INVENTION According to the present invention, the above object is to provide an optical disc provided with a track having a predetermined track pitch in the radial direction, wherein a part of the track is used for confirmation. This is achieved by a standard optical disc for inspection, which is provided with a track pattern that is intentionally formed in advance so as to generate a tracking drive current or a tracking error signal.

Further, according to the present invention, the above object is to provide a master having a surface coated with a photoresist along a track configured to have a predetermined track pitch in a radial direction by a cutting machine. Irradiating a position corresponding to the information pit with laser light, and developing and removing the photoresist exposed in the first step and the first step to create a master disc having the information pit. A metal thin film is formed on the surface of the master obtained in the second step and the second step, and a metal layer is formed thereon by electroforming or the like to form a stamper. A transparent resin is injection-molded on the stamper surface obtained by the casting step to form a substrate. A fourth step is performed, and a reflective film and a protective film are formed on the substrate surface obtained in the fourth step. , Optical disc Exposing the cutting machine so as to generate a track pattern that generates a preset tracking drive current for confirmation or a tracking error signal in the first step. This is achieved by a method of manufacturing a standard optical disc for inspection, in which a serpentine signal is given to a cutting machine in order to cause the laser light for use to meander in the radial direction of the glass master.

According to the above structure, the track pattern for the inspection of the tracking abnormality is intentionally formed in advance so as to have the meandering of the predetermined amplitude and period. Therefore, the inspection for confirming the desired tracking abnormality can be performed. The standard optical disc for use can be stably obtained.

Further, since the track pattern is recorded on the master by controlling the cutting machine during cutting on the master, there is almost no variation among the standard optical disks formed via the stamper. Absent.

By reproducing such a standard optical disk for inspection, it is possible to detect the return light by the photodetector of the optical pickup and obtain the above-mentioned tracking drive current and tracking error signal for confirmation. In this case, since the meandering of the track pattern that causes the tracking abnormality is strictly determined in advance, it is possible to confirm the waveform of the tracking drive current or the tracking error signal for confirmation, for example, in the inspection process. Adjustment of the inspection device regarding the tracking abnormality of the optical disk, operation check for the tracking abnormality of the optical disk reproducing device, etc. can be accurately and easily performed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. still,
The embodiments described below are preferable specific examples of the present invention, and therefore, various technically preferable limitations are given,
The scope of the present invention is not limited to these embodiments unless otherwise specified in the following description.

FIG. 1 shows a first embodiment of an optical disc according to the present invention. In FIG. 1, an optical disk 10
Is composed of a disk-shaped disk substrate 11 having a center hole 11a in the center, and a reflective film and a protective film (not shown) sequentially formed on the surface of the disk substrate 11.

The disc substrate 11 has a signal recording surface (not shown) formed on the surface thereof, and the signal recording surface has tracks 12 formed so as to have a predetermined track pitch in the radial direction. I have it. As a result, the track 12 is, as shown in the upper part of FIG.
While lining up at a predetermined track pitch in the radial direction,
It extends substantially parallel to the circumferential direction. The track 12 is actually composed of information pits 13 arranged side by side with the track 12 as a center line, as shown in the lower part of FIG.

As shown in FIG. 3, the track 12 is
At least a part thereof, in the case of the drawing, only one track region 12a in the radial direction is configured to meander in advance intentionally in the radial direction from a predetermined track position. The meandering of the track area is shown in FIG.
As shown in FIG.
2b may be configured to be radially displaced from a predetermined track position.

Here, the meandering of the track area is set to an arbitrary period and amplitude so as to be able to correspond to the inspection of various quality items of the optical disc 10. FIG. 5 shows an embodiment of the manufacturing process of the optical disc 10 described above. In FIG. 5, first step ST
In 1, a master 20 made of a glass substrate is prepared.
Then, in step ST2, a thin photoresist film 21 is formed by applying a photoresist solution to the surface of the glass substrate 20. The master 20 may be made of a material other than glass, for example, a transparent synthetic resin master may be used.

Then, in step ST3, the glass master 20 on which the photoresist film 21 is formed is cut by a cutting machine. That is, first, the glass master 20 is a cutting machine (see FIG. 6).
It is mounted on a turntable (see) and driven to rotate.
Then, the laser light L is applied to the photoresist film 21 on the surface of the glass master 20 that is rotationally driven. At this time, the objective lens 22 for irradiating the laser beam L of the cutting machine slowly moves from the inner peripheral side to the outer peripheral side of the glass master 20, and the laser beam emitted through the objective lens is described later. The irradiation / non-irradiation is repeated based on the signal from the original signal generator.

Thus, the photoresist film 21 on the glass master 20 is exposed at a predetermined track pitch in the radial direction, and a photosensitive portion / non-photosensitive portion is formed corresponding to irradiation / non-irradiation of laser light. Will be. Here, in the above-mentioned cutting, the irradiation of the laser beam of the cutting machine is performed so as to meander in the radial direction of the glass master in at least a part of the area, as described later with reference to FIG.

Next, in step ST4, the photoresist film 21 is developed to remove the photosensitive portion due to the laser light. As a result, the photosensitive portion is removed, so that the concave portion 21a as an information pit is formed. The information pits 21a are arranged as described above, and the center line thereof defines a track.

Thereafter, in step ST5, the metal thin film 2
After formation of the metal layer 3, the conductive layer is formed, and then in step ST6, the metal layer 2 is formed by electroforming.
4 is formed, and further, in step ST7, the glass master 20 and the photoresist film 21 are removed, so that the stamper 25 including the metal thin film 23 and the metal layer 24 is obtained. The stamper 25 has information pits 21 formed on the surface thereof in the developing process (step ST4).
a is transferred in a shape in which unevenness is reversed.

Next, in step ST8, the stamper 25 is mounted in the mold of the injection molding machine, and the transparent resin 26 such as polycarbonate resin melted at high temperature is injected and cooled in the mold. Then, in step ST9, the injection-molded transparent resin 26 is taken out of the mold to obtain the disk substrate 27 having the information pits 27a to which the shape of the information pits 21a is transferred.

Finally, in step ST10, a reflective film 28 is formed on the surface of the disk substrate 27 by sputtering or vapor deposition, and in step ST11, a protective film 29 is formed by coating a resin film thereon. The optical disc 10 is completed by forming the optical disc.

In this case, the information pit 1 on the optical disc 10
3 (27a) has almost the same shape as the information pit 21a obtained by developing the photoresist film 21 on the glass master 20, and there is almost no wear or damage to the stamper 25 due to the injection molding of step ST8.
By repeating the processes from ST11 to ST11, a large number of optical discs 10 having the same array of information pits 13 are manufactured.

By the way, in the manufacturing process of the optical disc 10, the cutting machine used for cutting the glass master 20 is constructed as shown in FIG. That is, in FIG. 6, the cutting machine 30
Is configured to irradiate a glass master disk 20 mounted on a turntable which is rotationally driven at a predetermined rotation speed with a laser beam (cutting beam) through an objective lens (not shown). Irradiation / non-irradiation of laser light is controlled based on the original signal from the generator 31, and the objective lens is slowly moved from the inner peripheral side to the outer peripheral side of the glass master 20 based on the glass master rotation synchronization signal. It is supposed to do.

Further, in this embodiment, the cutting machine 30 is provided with an optical system for moving the spot of the laser light at high speed by several μm in the radial direction of the glass master disk 20 mounted on the turntable, By moving this optical system based on the voltage applied to the control voltage input terminal 30a, the spot of the laser light can be moved by a distance proportional to this voltage. An arbitrary waveform generator 32 is connected to the control voltage input terminal 30a. The arbitrary waveform generator 32 generates an arbitrary waveform based on the glass master disc rotation synchronizing signal from the output terminal 30b of the cutting machine 30. Generate a signal.

According to such a configuration, the cutting machine 30 causes the spot of the cutting beam to be displaced in the radial direction from the original track in accordance with the signal waveform from the arbitrary waveform generator 32 so that the track meanders. be able to. Therefore, based on the signal waveform from the arbitrary waveform generator 32, the track pattern for generating the checking tracking driving current or the tracking error signal is
It is intentionally formed beforehand. The arbitrary waveform signal generated by the arbitrary waveform generator 32 has a movement trajectory of the cutting beam formed on the glass master disk, that is, a track having various periods and amplitudes due to the movement of the spot of the cutting beam of the cutting machine 30. It is set to perform meandering.

The optical disc 10 according to the present embodiment is configured as described above, and the optical disc 10 has an arbitrary waveform in which the track pattern for the inspection of the tracking abnormality is applied to the control voltage input terminal 30a of the cutting machine 30. According to the signal waveform from the generator 32, the standard optical disc for inspection giving a desired tracking abnormality can be stably obtained because it is intentionally formed so as to have a meandering of a predetermined amplitude and period.

When inspecting the optical disk 10 thus constructed by the optical disk device 40, as shown in FIG. 7, the optical disk 10 placed on the turntable (not shown) is rotated by the spindle motor 41. The optical pickup 42 is driven and the objective lens 42a is driven.
A light beam is irradiated onto the signal recording surface of the optical disc 10 via the. Then, the return light from the signal recording surface of the optical disc 10 is detected by a photodetector (not shown) of the optical pickup 42 to generate a reproduction signal, a tracking error signal and the like.

Here, a measuring circuit 43, a control unit 44 and a computer 45 are connected to the optical disk device 40. The measurement circuit 43 takes out various signals from the optical disc device 40 and performs measurement for inspecting the quality of the optical disc 10. The control unit 44 controls the optical disk device 40 and the measuring circuit 4 based on an instruction from the computer 45.
3 and sends the result of the measurement regarding various quality items to the computer 45.

According to such a configuration, the optical disk 10
Is reproduced from the optical disk 10 based on the track meandering with various periods and amplitudes, and the tracking drive current TD as shown in FIG. 9 and the tracking error signal TE are intentionally set in advance. Various tracking abnormalities will occur. Therefore, for example, by checking whether the fluctuation of the tracking drive current TD or the fluctuation of the tracking error signal TE as shown in FIG. It is possible to adjust or calibrate the inspecting machine and the measuring circuit 43 including it. As a result, the inspection standard in the mass-production process of optical disks is kept constant. Therefore, since the optical disc device is inspected for the tracking abnormality relating to the reproduction of the optical disc, the quantitative inspection for the tracking abnormality of the optical disc becomes possible.

In the above embodiment, the case where the tracking abnormality inspection is performed by the optical disc device 40 has been described, but the present invention is not limited to this, and the optical disc 10 can be used to check the operation of the optical disc device 40. Is.

[0037]

As described above, according to the present invention, a standard optical disk for inspection, which has a defect relating to a desired tracking anomaly serving as an inspection reference, can be mass-produced, and has good reproducibility, and its manufacture. Methods and inspection methods will be provided.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an entire optical disc according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a region of a normal track in the optical disc of FIG. 1 and a partially enlarged view of information pits constituting the track.

FIG. 3 is a schematic diagram showing an area of a track pattern for generating a tracking error signal of a checking tracking driving current in the optical disc of FIG.

FIG. 4 is a schematic view showing a modified example of the track pattern of FIG.

5 is a flowchart sequentially showing a manufacturing process of the optical disc of FIG.

6 is a schematic view showing a cutting machine used in a master disc cutting process in the manufacturing process of FIG. 5;

FIG. 7 is a schematic diagram showing a system for implementing the method for detecting tracking abnormality by the optical disc of FIG.

FIG. 8 is a schematic diagram showing a configuration of a conventional optical disc device.

9 is a time chart showing a track, a tracking error signal, and an objective lens drive current when an optical disc having tracking abnormality (meandering with a relatively long cycle) is reproduced by the optical disc device of FIG.

10 is a time chart showing a track, a tracking error signal, and an objective lens drive current when an optical disk having tracking abnormality (meandering with a relatively short cycle) is reproduced by the optical disk device of FIG.

[Explanation of symbols]

10 optical disk, 11 disk substrate, 12
... Tracks, 13 ... Information pits, 12a, 12
b ... track meandering, 20 ... glass master, 21 ...
..Photoresist film, 21a ... Information pits, 22
... Objective lens of cutting machine, 23 ... Metal thin film, 24 ... Metal layer, 25 ... Stampato, 2
6 ... Transparent resin, 27 ... Disk substrate, 27a ...
..Information pits, 28 ... Reflective film, 29 ... Protective film, 30 ... Cutting machine, 31 ... Original signal generator, 32 ... Arbitrary waveform generator, 40 ... Optical disk device , 41 ... Spindle motor, 42 ... Optical pickup, 43 ... Measuring circuit, 44 ... Control unit, 45 ... Computer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiro Nakamura 134, Kobe-cho, Hodogaya-ku, Yokohama-shi, Kanagawa Sony Disk Technology Co., Ltd.

Claims (3)

[Claims] 1. An optical disc having tracks arranged to have a predetermined track pitch in the radial direction, wherein a part of the tracks is previously generated so as to generate a tracking drive current or a tracking error signal for confirmation. A standard optical disc for inspection, which is provided with a track pattern intentionally formed. 2. A laser beam is applied to a position corresponding to an information pit along a track configured to have a predetermined track pitch in a radial direction by a cutting machine with respect to a master having a photoresist coated on its surface. The first step of irradiating the substrate and the photoresist exposed in the first step are developed and removed to form a master disc having information pits. The second step and the second step On the surface of the obtained master, a metal thin film is formed, a metal layer is formed on it by electroforming, etc., to create a stamper, the third step, and the stamper surface obtained by the electroforming step, Fourth step of making a substrate by injection molding a transparent resin, and a fifth step of forming an optical disk by forming a reflection film and a protective film on the surface of the substrate obtained in the fourth step Including and In the first step, the laser light for exposure of the cutting machine is set in the radial direction of the glass master so as to generate a preset tracking drive current for confirmation or a track pattern for generating a tracking error signal. A method of manufacturing a standard optical disk for inspection, which comprises applying a meandering signal to a cutting machine to cause the cutting machine to meander. 3. A track tracking drive current or a tracking error signal, which is provided on a part of this track and has a track configured to have a predetermined track pitch in the radial direction, is generated. By reproducing a standard optical disc for inspection having a track pattern and performing tracking control based on the return light from the standard optical disc for inspection, a tracking drive current or a tracking error signal is obtained, and a tracking drive current or tracking is obtained. An inspection method using a standard optical disc for inspection, which comprises detecting a confirmation signal waveform from an error signal.