JPH09274742A - Inspection standard optical disk, its manufacture and its inspecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain mass production and to improve reproducibility by providing a track pattern for generating a dropout confirming signal in a part of a track. SOLUTION: This optical disk 10 includes a disk substrate 11 having a center hole 11a in the center and reflection and protective films sequentially formed on the surface of this substrate 11. For the optical disk 10, a track pattern for generating dropouts is formed so as to intentionally form small or shallow information pits 13a and 13b beforehand according to a pulse signal from a modulation device. Thus, an inspection standard optical disk for giving desired dropouts is stably provided.

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 reference for inspecting optical disks such as a compact disk (CD), a mini disk (MD), and a high-density recording optical disk, and a manufacturing method and inspection thereof It is about the 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. 9, for example.

In FIG. 9, an optical disc apparatus 1 uses an objective lens 3a of an optical pickup 3 for a track 2a on a signal recording surface of an optical disc 2 which is rotationally driven.
Irradiate a light beam such as a laser beam. Then, as shown in FIG. 10, the return light from the signal recording surface of the optical disc 2 is
It is detected by a photodetector (not shown) of the optical pickup 3 via the objective lens 3a of the optical pickup 3, and a reproduction signal is generated based on an HF (high frequency) signal which is an output signal of the photodetector. It has become. This HF signal becomes H level or L level due to the different reflectance due to the information pits 2b formed along the track 2a, and is observed as a so-called envelope signal by reducing the time axis. It is like this.

The objective lens 3a of the optical pickup 3 is supported by an actuator (not shown) so as to be movable at least in the tracking direction. And the tracking servo of the objective lens 3a is
The detection signal from the optical pickup 3 is amplified by the amplifier 4 to obtain the tracking error signal TE, and the tracking error signal TE is amplified by the drive amplifier 6 after removing the high frequency component through the low pass filter 5. By applying the objective lens drive current TD to the actuator of the optical pickup 3, the objective lens 3a is moved 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. This is performed by controlling the drive.

When the optical disk 2 reproduced in this way is manufactured, whether or not the optical disk is manufactured correctly is inspected in the inspection process. For example, in an optical disc manufacturing process, as shown in FIG. 11, reading is hindered due to mixing of opaque impurities A into the disc substrate, adhesion of dirt B to the signal reading surface side, and the like, and reproduction. The upper limit of the signal (HF signal) drops, or as shown in FIG. 12, a so-called defect occurs in which the lower limit of the reproduction signal (HF signal) is raised due to the lack of information pits for some reason. Sometimes.

Due to the fluctuation of the returning light due to such a defect, the upper limit of the HF signal falls and the lower limit rises.
This is called a dropout, and it may be impossible to read the information pits in the area where such a dropout occurs. Further, in some cases, tracking servo for causing the optical pickup 3 to follow the track of the optical disk 2 may become difficult, which causes a serious problem such as a track jump.

Therefore, in the inspection in the manufacturing process of the optical disc, the envelope detection circuit 7 extracts the upper limit voltage V1 and the lower limit voltage V2 of the HF signal from the optical pickup 2 and the subtracter 8 outputs the output difference V0.
Get. By monitoring the output difference V0 by the monitoring / quantification means 9, the dropout of the HF signal, that is, the attenuation or loss of the amplitude is observed, and the dropout is quantified and measured based on the waveform. become. Therefore, in the inspection process, if the output difference V0 exceeds a predetermined value, it is determined that a dropout has occurred.

Further, in the inspection of the optical disk as described above, when the manufactured optical disk is reproduced, the opaque impurities A are mixed into the disk substrate and the dirt B is attached to the signal reading surface side. It is premised that it is possible to confirm that the above-mentioned dropout occurs due to the above. That is, as a premise for detecting such a dropout, when an optical disk having a predetermined defect is reproduced in an optical disk device or an inspection machine including the system as shown in FIG. The optical disk device and the inspection machine must function properly so that the optical disk device can be detected.

Therefore, before inspecting whether or not the optical disc is manufactured correctly, adjustment is performed so that the optical disc device and the inspection machine function properly (calibration of the inspection process), so that dropout occurs due to reproduction. It is necessary to prepare such a defective disc and play it back. And conventionally, in such an inspection process,
An inspection defective disk is used for inspection and calibration of the optical disk. 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.

[0010]

By the way, in such a defective disc, when the original disc is scratched, the same defect is reproduced, but since the defect itself becomes random, a desired defect is not produced. There was a problem that it could not be obtained. Further, when the reading surface side of the optical disc is intentionally contaminated, the defect reproducibility varies from optical disc to optical disc.
There is a problem in terms of mass productivity, and there is a problem in that a reproduced defect signal may be different for each optical disk drive device, making it impossible to perform accurate calibration in the inspection process. 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.

In particular, regarding a defective disk related to dropout, various impurities, stains, and lack of information pits are required. However, if defective disks actually generated in the manufacturing process are used, the number and types thereof are different. There is a problem in that it is difficult to prepare a large number of defective discs for each type of dropout required for the inspection process because the number of defective discs is limited.

In view of the above points, the present invention has a defect related to a desired dropout as a reference of inspection,
An object of the present invention is to provide a standard optical disc for inspection, which can be mass-produced and has good reproducibility, and a manufacturing method and an inspection method thereof.

[0013]

According to the present invention, the above-mentioned object is intended in advance in at least a part of the track in an optical disk provided with a track configured to have a predetermined track pitch in the radial direction. By a standard optical disc for inspection, which has a track pattern that generates a dropout confirmation signal
Achieved.

Further, according to the present invention, according to the present invention, a master machine having a photoresist coated on its surface is cut along a track formed by a cutting machine so as to have a predetermined track pitch in the radial direction. 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 And a fifth step, which is input to the cutting machine so as to generate a track pattern for intentionally forming a dropout confirmation signal in advance in the first step. The original signal is modulated so that at least a part of the track is cut in a half-cut state,
This is achieved by a method of manufacturing a standard optical disk for inspection.

According to the above arrangement, the track pattern that causes the dropout has a predetermined information pit area on the track or an area between the predetermined information pits, which is intentionally set beforehand.
Since it is formed as a small or shallow information pit, a standard optical disc for inspection which gives a desired dropout 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. In addition, the track pattern that gives the dropout is formed by the shape of the information pit formed on the signal recording surface.

Therefore, by reproducing such a standard optical disk for inspection, the above-mentioned dropout confirmation signal is obtained based on the reproduction signal (HF signal) obtained by detecting the return light by the photodetector of the optical pickup. It is detected that a dropout has occurred by detecting. In this case, since the track pattern that causes the dropout is strictly determined in advance, for example, it is necessary to adjust the inspection standard for the optical disc dropout in the inspection process or to confirm the operation of the optical disc playback device against the dropout. It will be done accurately and easily.

[0018]

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 disk 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. Accordingly, the tracks 12 are arranged at a predetermined track pitch in the radial direction and extend substantially parallel to the circumferential direction, as shown in FIG. The track 12 is composed of information pits 13 arranged side by side with the track 12 as a center line. The information pit 13 has a length and / or a length based on the information to be recorded.
Or the interval is determined.

As shown in FIG. 3, the track 12 is
At least a part thereof, in the illustrated case, the information pits (abnormal information pits) 13a of the second track 12a from the right side in the radial direction are intentionally made smaller or shallower than the normal information pits 13 in advance. Has been formed. Such an information pit 13a causes drop-up when the HF signal is raised and the lower limit signal of the envelope signal is raised when the optical disc 10 is reproduced, as shown in the lower part of FIG.

Alternatively, in the optical disc 10 according to the present invention, as shown in FIG. 4, the track 12 has at least a part thereof, in the case of the figure, the original information about the third track 12b from the right side in the radial direction. An abnormal information pit 13 formed in a region between the pits 13 is smaller or shallower than the normal information pit 13.
b is formed. Such information pit 13b is
When the optical disk 10 is reproduced, the HF signal has a drop in the upper limit signal of the envelope signal, as shown in the lower part of FIG. 4, which causes drop-up.

Here, the above-mentioned abnormality information pits 13a, 13
b is set to various sizes and / or depths so as to be able to deal with various dropout inspections of the optical disc 10.

FIG. 5 shows an embodiment of the manufacturing process of the optical disk 10 described above. In FIG. 5, first, in step ST1, 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 is not limited to glass, but other transparent materials such as a synthetic resin substrate can be used as appropriate. Then, step ST
At 3, the glass master 20 having the photoresist film 21 formed thereon is cut by a cutting machine. That is, first, the glass master 20 is mounted on the turntable of the cutting machine (see FIG. 6),
It is driven to rotate. Then, the glass master 2 that is rotationally driven.
Laser light L to the photoresist film 21 on the surface of
Is irradiated.

At this time, the objective lens 22 for irradiating the laser beam L of the cutting machine is the glass master 20.
While moving slowly from the inner peripheral side to the outer peripheral side, the laser light emitted through the objective lens repeats irradiation / non-irradiation based on a signal from an original signal generator described later. 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. Become. Here, in the above-mentioned cutting, the irradiation of the laser beam of the cutting machine, as will be described later with reference to FIG.
13b is formed.

Next, in step ST4, the photoresist film 21 is developed, and the photosensitive portion due to the laser light is removed. 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 in a spiral shape 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 a 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 of the optical disk 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 disk 10, the cutting machine used for cutting the glass master 20 is constructed as shown in FIG. That is, in FIG. 5, the cutting machine 30
Has a substantially known structure, and a laser beam (cutting beam) is passed through an objective lens (not shown) to a glass master disk 20 mounted on a turntable that is rotationally driven at a predetermined rotational speed. The irradiation / non-irradiation of the laser light is controlled based on the original signal input from the original signal generator 31 through the modulator 32, and also based on the glass master disc rotation synchronization signal. Thus, the objective lens slowly moves from the inner peripheral side to the outer peripheral side of the glass master 20.

Here, the modulator 32 is, for example, as shown in FIG.
As shown in FIG. 5, the laser signal of the cutting machine 30 is controlled by superimposing a pulse signal that repeatedly turns on and off with an original signal from the original signal generator 31 and performing pulse width modulation. . Then, the modulator 32 outputs the output signal S1 as shown in FIG. 7 when performing pulse width modulation on the H level signal corresponding to the information pits of the original signal. As a result, the information pits are made smaller by half-cutting like the information pits 13a shown in FIG. 3 because the laser irradiation time of the cutting machine 30 is substantially shortened and the exposure amount of the photoresist is reduced. And / or will be shallowly formed.

On the other hand, when the modulator 32 performs pulse width modulation on the L level signal corresponding to the mirror portion between the information pits of the original signal, as shown in FIG. S2 will be output. This allows
Similarly, the mirror portion between the information pits is formed to be small or shallow by half-cutting like the information pit 13b shown in FIG. Thus, by switching the pulse modulation by the modulator 32,
The incomplete information pit 13a or the incomplete information pit 13b serving as an incomplete mirror portion is intentionally formed in advance. In the modulator 32, the information pits 13a and 13b formed by adjusting the pulse width thereof are
Various sizes or depths are set as compared with the original information pit 13 or the mirror portion between them.

The optical disc 10 according to the present embodiment is configured as described above, and the optical disc 10 has a track pattern for causing dropout intentionally intentionally based on the pulse signal of the modulator 32. Since it is formed by forming the small or shallow information pits 13a and 13b, a standard optical disc for inspection which gives a desired dropout can be stably obtained.

When inspecting the optical disc 10 thus constructed by the optical disc device 40, as shown in FIG. 7, the optical disc 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 (HF signal), a tracking error signal and the like. .

Here, a measuring circuit 43, a control section 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
By reproducing, the various intentionally set dropouts are generated based on the HF signal from the optical disk 10. Therefore, by detecting how much dropout actually causes the optical disk device 40 to become unreproducible, the inspection standard for the dropout of the optical disk device 40 is confirmed or adjusted. As a result, the optical disk device 40
Alternatively, by adjusting or calibrating the measuring circuit 43 and the inspection machine using these, the inspection standard for dropout in the optical disk mass production process can be kept constant. Therefore, since the optical disc device is inspected for the dropout relating to the reproduction of the optical disc, it is possible to perform the qualitative inspection regarding the dropout of the optical disc.

In the above-described embodiment, the case where the dropout 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 device 4 can be used.
It is also possible to use the optical disc 10 to confirm the operation regarding the 0 dropout.

[0039]

As described above, according to the present invention, a standard optical disk for inspection, which has a defect related to a desired dropout to be used as an inspection standard, can be mass-produced, and has good reproducibility, is provided. A manufacturing method and an inspection method 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 partially enlarged view showing original information pits constituting a track in the optical disc of FIG. 1 and H during reproduction thereof.
It is a graph which shows F signal.

FIG. 3 is a partially enlarged view showing relatively small or shallowly formed information pits for generating a dropout confirmation signal in the optical disc of FIG.

FIG. 4 is a partially enlarged view showing relatively small or shallowly formed information pits formed in a portion other than the information pits for generating the dropout confirmation signal in the optical disc 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;

7 is a time chart exemplifying an original signal, a modulation signal, and an output signal in the cutting machine of FIG.

FIG. 8 is a schematic diagram showing a system for carrying out the method for detecting tracking abnormality by the optical disc of FIG.

FIG. 9 is a schematic diagram showing a configuration of a conventional optical disc device.

10 is a schematic diagram showing an information pit forming an optical disk track in the optical disk device of FIG. 9 and an HF signal from an optical pickup.

FIG. 11 is a schematic cross-sectional view of an optical disc showing an example of dropout due to impurities and dirt on the optical disc, and a graph showing an HF signal at the time of reproduction thereof.

FIG. 12 is a schematic cross-sectional view of an optical disc showing an example of dropout due to a lack of information pits of the optical disc, and a graph showing an HF signal during reproduction thereof.

FIG. 13 is a schematic diagram showing an example of a conventional optical disc dropout detection method.

[Explanation of symbols]

10 optical disk, 11 disk substrate, 12
... Tracks, 13 ... Information pits, 13a, 13
b ... Abnormality information pit, 20 ... Glass master, 21
... Photoresist film, 21a ... Information pit, 2
2 ... Objective of cutting machine, 23 ...
Metal thin film, 24 ... metal layer, 25 ... stamp pad,
26 ... Transparent resin, 27 ... Disk substrate, 27a
... information pit, 28 ... reflective film, 29 ... protective film, 30 ... cutting machine, 31 ... original signal generator, 32 ... modulation device, 40 ... optical disk device, 41 ... Spindle motor, 42 ... Optical pickup, 43 ... Measuring circuit, 44 ... Control unit, 4
5 ... 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 comprising tracks configured to have a predetermined track pitch in the radial direction, wherein a dropout confirmation signal intentionally formed in advance is generated on at least a part of the tracks. A standard optical disc for inspection having a track pattern. 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 injection-molding transparent resin to form a substrate, and 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 And includes In the first step, at least one of the tracks is modulated by modulating the original signal input to the cutting machine so as to generate a track pattern for intentionally forming a dropout confirmation signal in advance. A method for producing a standard optical disc for inspection, characterized in that a part is cut in a half-cut state. 3. A track pattern, which comprises tracks configured to have a predetermined track pitch in the radial direction, and intentionally formed on at least a part of the tracks to generate a dropout confirmation signal. A standard optical disk for inspection having the following, a reproduction signal is generated based on the return light from the standard optical disk for inspection, and the dropout confirmation signal is detected from the reproduction signal. Inspection method with standard optical disk.