JPH09274743A - Inspection standard optical disk, its manufacture and its inspecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain mass production and to improved reproducibility by providing a specified track pattern in a part of a track. SOLUTION: By reproducing an optical disk 10, errors are produced by various abnormal information pits intentionally set beforehand based on a HF signal from the optical disk 10. Accordingly, by detecting the actual disabled reproduction of an optical disk device 40, depending on the degree of a generated error, an inspection reference relating to the error generation of the device 40 is confirmed or adjusted. Then, by adjusting or correcting the optical disk device 40 or a measuring circuit 43, an inspection reference relating to an error generation during optical disk mass production is maintained constant.

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. 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. Incidentally, this reproduction signal is usually obtained by binarizing the output signal (HF signal) from the photodetector of the optical pickup 3 by the binarizing circuit 3b as shown in FIG. The clock of the carrier wave included in the binarized signal is extracted by the clock extraction circuit 3c, the binarized signal is shaped by the waveform shaping circuit 3d based on this clock, and then error-corrected by the error detection / correction circuit 7. , A correct reproduction signal (reproduction data) is generated.

The objective lens 3 of the optical pickup 3
a is supported by an actuator (not shown) so as to be movable at least in the tracking direction.
Then, in the tracking servo of the objective lens 3a, 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 removed of the high frequency component through the low pass filter 5. After that, it is amplified by the drive amplifier 6 and applied to the actuator of the optical pickup 3 as the objective lens drive current TD, 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. The objective lens 3a
Is controlled in the tracking direction.

By the way, when the above-mentioned optical disc 2 is manufactured, whether or not the optical disc is properly manufactured is inspected in the inspection process. In the inspection of such an optical disc, when the manufactured optical disc is reproduced,
As described later, it is necessary to be able to detect the error rate of the reproduction signal caused by the information pit formation error. However, as a prerequisite for such error detection,
In an optical disk device or an inspection machine including the system as shown in FIG. 8, when an information pit has a predetermined formation error, the optical disk device and the inspection machine function properly so that the error can be correctly detected in response to the formation error. I have to do it. Therefore, before inspecting whether or not the optical disc is manufactured correctly, adjustments or the like are performed so that the optical disc device or the inspection machine functions properly (calibration of the inspection process), so that a predetermined error may occur during reproduction. It is necessary to prepare a defective disk and play it back.

Defective disks that can be produced in such a mass production process are as follows. For example, in the process of manufacturing an optical disc, opaque impurities are mixed into the disc substrate, and irregularities formed on the disc substrate surface due to foreign matter or scratches adhering to the surface of the stamper cause the information pits to be missing. Alternatively, a defect such as the presence of an information pit that is erroneously formed in a mirror portion that should have no information pit (hereinafter referred to as an information pit formation error) may occur. Then, in such a defective optical disc, an error in the reproduction signal (HF signal) may be induced due to such an information pit formation error.

Therefore, in the inspection in the manufacturing process of the optical disk, the number of errors contained in the reproduced signal (HF signal) from the optical pickup 2 is determined by the error detection / correction circuit 7.
Is detected by the error coefficient circuit 8, and the error coefficient circuit 8 counts the error based on the error detection signal.
I try to get the error rate.

[0008]

By the way, in such a defective disk, since the defects themselves are randomized, there is a possibility that a desired defect may not be obtained even when used for the calibration of the inspection process. was there. Further, if the reading surface side of the optical disc is intentionally contaminated, the defects will vary from optical disc to optical disc, so that the reproducibility of defects cannot be substantially obtained, and there is a problem in terms of mass productivity. However, there is a problem in that the 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.

[0009] In particular, regarding a defective disk relating to an information pit formation error, various impurities, stains, and lack of information pits are required. If defective disks actually generated in the manufacturing process are used, the quantity and Since the types are limited, it is difficult to prepare a large number of defective discs for each type of information pit formation error required for the inspection process.

In view of the above points, the present invention has a defect relating to a desired information pit formation error as a reference for inspection, can be mass-produced and has good reproducibility, and a method for manufacturing the same. And to provide an inspection method.

[0011]

According to the present invention, the above object is recorded on at least a part of the track in an optical disk having tracks configured to have a predetermined track pitch in the radial direction. This is achieved by a standard optical disk for inspection having an information signal to be formed and a track pattern which is intentionally made different in advance.

The standard optical disc for inspection according to the present invention is preferably configured such that the track pattern is formed by intentionally omitting information pits to be originally formed in the information signal to be recorded. Or
The track pattern is configured by intentionally forming information pits in advance in an area where information pits are not originally formed with respect to an information signal to be recorded.

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 In the method of manufacturing an optical disc, the method further comprises: a fifth step of forming a track pattern, which is intentionally different from an information signal to be recorded in advance in the first step. In addition, it is achieved by a method of manufacturing a standard optical disc for inspection, which modulates an original signal input to a cutting machine.

According to the above-mentioned structure, the track pattern which causes an error is desired by the information pits due to the intentional lack of predetermined information pits or the formation of the information pits in the area between the information pits. It is possible to stably obtain a standard optical disc for inspection that causes the error occurrence.

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. The track pattern that does not exist and gives rise to the above error 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 information pit formation error is generated based on the reproduction signal (HF signal) obtained by detecting the return light by the photodetector of the optical pickup. By detecting, the error occurrence is detected. In this case, since the track pattern having the information pit formation error is strictly determined in advance, for example, the adjustment of the inspection standard for the error occurrence of the optical disc in the inspection process or the operation confirmation for the error occurrence of the optical disc reproducing device is performed. Will be done accurately and easily.

[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. 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, an abnormal information pit 13a which should not be originally present is intentionally preliminarily provided in the area of the mirror portion between the original information pits 13 on the second track 12a from the left side in the radial direction. Is formed in.

Alternatively, in the optical disk 10 according to the present invention, as shown in FIG. 4, the track 12 should be originally at least a part thereof, in the illustrated case, the second track 12b from the right side in the radial direction. The information pit 13b is missing.

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 a glass substrate, and a transparent material such as synthetic resin may be used as appropriate.

Then, in step ST3, 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 a turntable of a cutting machine (not shown) 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, at the time of the above-mentioned cutting, the irradiation of the laser beam of the cutting machine is, as will be described later with reference to FIG. 6, an information pit formation error, that is, an abnormal information pit 13a is formed or a pit 13b is missing in at least a partial area. Is caused to occur.

Next, in step ST4, the photoresist film 21 is developed to remove the photosensitive portion due to the laser beam. 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.

Then, 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 reflection 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 applying a resin film or the like from above. 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 disc 10, the cutting machine used for cutting the glass master disc 20 is constructed as shown in FIG. That is, in FIG. 5, 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). From generator 31 to modulator 32
The irradiation / non-irradiation of the laser light is controlled on the basis of the original signal input via the, 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 designed to move.

Here, the modulator 32 normally forces the original signal, which is a digital signal from the original signal generator 31, at a specific timing during a low level corresponding to the mirror section. It is controlled so as to be modulated to a high level forcibly or forcibly to a low level during the high level corresponding to the information pit 13. Thereby, the cutting machine 30 does not intentionally form the information pit 13a in the area of the mirror portion between the information pits with respect to the original signal or without forming the information pit in the area where the information pit should be formed. Therefore, the information pit 13b is intentionally dropped. Thus, by the control of the modulation by the modulator 32, the extra information pits 13a or the missing information pits 13b are intentionally formed beforehand.

The optical disc 10 according to the present embodiment is configured as described above, and the optical disc 10 has a track pattern for generating an information pit formation error.
Since it is configured by intentionally forming the abnormal information pits 13a and 13b based on the modulation of the modulator 32, it is possible to stably obtain the standard optical disk for inspection that gives a desired error occurrence. Become.

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 (HF signal), a tracking error signal, etc. It is designed to count the errors that occur.

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
By reproducing the data, an error will occur due to various abnormal information pits that are intentionally set in advance based on the HF signal from the optical disc 10. Therefore, for example, it is possible to confirm or adjust the inspection standard regarding the error occurrence of the optical disk device 40 by detecting how much error the optical disk device 40 actually becomes unreproducible. Further, by reproducing the optical disc in which the abnormal information pit 13a is formed and / or the pit 13b is deleted, it is inspected whether or not an inspection machine or a disc player including the system of FIG. 8 correctly detects an error. Can be adjusted. Thereby, the optical disk device 40 or the measurement circuit 4
By carrying out the adjustment or calibration of No. 3, the inspection standard for the error occurrence in the optical disk mass production process is kept constant. Therefore, since the optical disk device is inspected for the error occurrence related to the reproduction of the optical disk, the qualitative inspection related to the error occurrence for the optical disk can be performed.

In the above-described embodiment, the case where the error occurrence inspection is performed by the optical disk device 40 has been described, but the present invention is not limited to this, and the optical disk 10 is used for the operation confirmation regarding the error occurrence of the optical disk device 40.
It is also possible to use

[0037]

As described above, according to the present invention, a defect relating to a desired information pit formation error serving as an inspection reference is provided, mass production is possible, and reproducibility is good.
A standard optical disc for inspection, a manufacturing method thereof, and an inspection method are 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 that form a track in the optical disc of FIG.

FIG. 3 is a partially enlarged view showing information pits in the optical disc of FIG. 1 where information pits that should not be originally formed.

FIG. 4 is a partially enlarged view showing information pits in the optical disc of FIG. 1 where information pits that should originally exist are missing.

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 schematic diagram showing error rate detection in the optical disc device of FIG.

[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 (5)

[Claims] 1. An optical disc having tracks configured to have a predetermined track pitch in the radial direction, wherein at least a part of the tracks is formed intentionally differently from an information signal to be recorded in advance. A standard optical disc for inspection, which has a recorded track pattern. 2. The track pattern is formed by intentionally omitting information pits originally to be formed with respect to an information signal to be recorded. Standard optical disc for inspection described. 3. The track pattern is formed by intentionally forming information pits beforehand in an area where information pits are not originally formed for an information signal to be recorded. Item 1. The standard optical disc for inspection according to Item 1. 4. 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 And includes In the first step, the inspection is characterized by modulating the original signal input to the cutting machine so as to generate a track pattern formed by intentionally different from the information signal to be recorded. For manufacturing standard optical discs. 5. A standard optical disk for inspection, which is provided with tracks configured to have a predetermined track pitch in the radial direction, and which has an information signal to be recorded and a track pattern which is intentionally made different in advance. A test method using a standard optical disc for inspection, which is reproduced and a signal different from the information signal is detected from a reproduced signal based on the return light from the standard optical disc for inspection.