JPH087290A - Optical disk - Google Patents

Abstract

PURPOSE:To decide whether an optical disk is a master or a copy and to make the duplication of a similar disk difficult by disability visual identification of a place added by the information for deciding the copy by setting a rotating speed in a CAV region so that the number of sectors on a track per one round of the disk is not an integer. CONSTITUTION:The recording signal of a disk 1 is recorded by the condition of constant rotating velocity (CAV) in one region, recorded by the condition of constant linear velocity(CLV) on the other region and the rotating velocity in the CAV region is set so that the number of sectors on a track 2 per one round of the disk 1 does not become an integer. Consequently, the position of a synchronizing signal 3 is not lined up on a straight line radially drawn from the center of the disk 1, inclined in the circumferencial direction on the disk and not identified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is manufactured by a CD (compact disc) type optical disc, particularly by a publisher having a copyright.
CD-ROM (compact disc read only memory) Discs with a function to prevent illegal copy (transfer) discs.

[0002]

2. Description of the Related Art In the field of electronic publications using a CD-ROM disc, it is easy to copy a reproduction signal to produce an illegal copy disc, so that the copyright protection thereof is practically difficult. . Especially in the field of electronic publications such as game software, books, dictionaries, etc., illegal copying is systematically made, so there is a danger of destroying normal commercial transactions, and there is a strong demand to prevent it. .

As a conventional copy protection, the actual Kaihei 2-20
Japanese Patent No. 884 discloses forming a visible pattern on the surface of a signal recording layer of an optical disc.

Further, Japanese Patent Laid-Open No. 2-179941 discloses that a visible pattern or the like is formed by changing the pit shape on the signal surface of an optical disk.

In many cases, a dedicated reproducing device is used for the above CD-ROM publication. Therefore, it is possible to detect the copy disk and prevent the copy disk from being reproduced by this specialized reproducing apparatus.

In Japanese Patent Laid-Open No. 4-286768, a part of a sync signal added to the head of a frame-structured digital signal recorded on an optical disk is replaced with another signal, and a reproducing apparatus determines whether or not this replacement signal is present. There is disclosed a method of detecting and determining that the optical disc is an illegal copy disc if there is no replacement signal.

[0007]

The above-mentioned conventional techniques have problems that the number of processing steps is increased and the S / N ratio of the reproduced signal from a visible pattern is deteriorated. There is also a problem that the signal format deviates from the CD standard.

An object of the present invention is to provide a disc capable of judging whether the optical disc is a master or a copied disc, and the place where the disc discriminating information is added cannot be visually identified. This makes it difficult to copy a disk.

[0009]

In order to achieve the above object, the optical disc of the present invention records a part of its area under the condition that the rotation speed is constant (CAV), and the other area has a constant linear velocity (CLV). ), And the rotational speed of the CAV area is set so that the number of sectors on the track around the disk does not become an integer.

[0010]

According to the disk of the present invention, the presence or absence of the CAV area is used as a disk identifying means, and the recording positions of the synchronizing signals are not aligned on the disk, so that the CAV area cannot be visually identified. I can.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an external view showing an embodiment of an optical disc according to the present invention. In FIG. 1, the recording signal of the disc 1 is CAV in a partial area. However, since the number of sectors on the track 2 for one rotation of the disk is not an integer, the position of the synchronization signal 3 is not aligned on a straight line radially drawn from the center of the disk 1 and is invisible. There is.

FIG. 2 shows a disk on which CAV is recorded by a conventional method. In FIG. 2, the recording signal of the disk 4 is CAV in a part of the area, and the number of sectors on one circumference of the track 5 is an integer. Therefore, the positions of the synchronizing signals 6 are aligned radially, and a visible pattern is obtained. Becomes

Generally, when a video signal is recorded, it is necessary to arrange the sync signals in alignment on the same radial line in order to reduce crosstalk that adversely affects the sync signals of adjacent tracks on the reproduction information. Yes, the number of sectors on one track is an integer.

The reason why the synchronization signals become visible when they are aligned on a straight line will be described.

FIG. 3 shows the signal format used in the CD-ROM. The data of the CD-ROM is divided into sectors, and a sync signal is attached to the head of the data. The signal of one sector is divided into frames, which is a CD-DA (digital audio) format, and a synchronization signal is attached to the beginning of each frame. In the EFM signal which is the CD modulation method, the synchronization signal is defined as one set of 11-bit length (11T) 'High'and'Low'signals.
Is the longest pit length according to the EFM modulation method.

The arrangement of the 11T pits can be visually identified for the following reason. Of the light incident on the signal surface of the optical disc, the light incident on the pit surface is diffusely reflected and hardly returns, but the light incident on the surface outside the pit is reflected at a constant angle with respect to the incident angle. Therefore, if the pit length and the interval are different, the light reflection interval is different, and thus the interference is different. Therefore, the 11T longest pit string that is linearly aligned visually has an average difference in reflectance compared with the surrounding places, and can be recognized as a pattern.

In this embodiment, since the CAV rotation is not an integer on one track, the sync signal positions on the adjacent tracks are displaced in the circumferential direction, which is a track pitch of 1.6 microns. Since the deviation distance of the upper synchronizing signal is large, the arrangement of the synchronizing signals is tilted substantially in the circumferential direction on the board and cannot be identified.

Next, an embodiment for disc identification will be described.

In this embodiment, a part of the disk is recorded at a constant rotational speed, that is, a constant angular velocity (CAV), and the other area is recorded at a constant linear velocity (CLV). This disc is hereinafter referred to as a dedicated disc.

FIG. 4 is a block diagram of the CD-ROM drive.

Reference numeral 401 is an optical disk, 402 is a spindle motor, 403 is an optical pickup, 404 is a servo circuit, 405 is an access control unit, 406 is a pickup feeding device, 407 is a preamplifier, 408 is a CD digital signal processing unit, and 409 is a CD-. ROM controller, 41
0 is the host system.

Optical pickup 40 from optical disc 401
The signal read by 3 is amplified by the preamplifier 407 and EFM demodulated by the CD digital signal processing unit 408. The EFM demodulated data is CD-
The ROM controller 409 unscrambles the data as a CD-ROM and sends it as ROM data to the host system 410. The access control signal controls the CD-ROM controller 409, the access control unit 405, and the servo circuit 404 according to an instruction from the host system 410, and realizes movement of the optical pickup 403 by the pickup feeding device 406 and rotation control of the spindle motor 402. .

FIG. 5 is a flowchart for checking that a partial area of the disc is recorded at a constant rotation speed (CAV).

(Step 502) It is judged whether the disc is a dedicated disc or not.

(Step 503) Since the disc is not a dedicated disc, processing based on the contents of the disc is performed.

(Step 504) The track m in the area which should have been recorded by CAV is accessed.

(Step 505) The rotational speed when the track m is being read is detected.

In the CD-ROM, the rotation servo is generally applied based on the reproduction signal, so that the rotation speed can be easily detected.

(Step 506) Access any track n (different from track m) in the CAV area.

(Step 507) The rotational speed when the track n is being read is detected.

(Step 508) The rotation speeds when the tracks m and n are read are compared, and if they match, it is determined that they are the same rotation speed, and the routine proceeds to step 509. If they do not match, it is determined that the rotation speeds are different, and the process proceeds to step 511.

(Step 509) Since the tracks in the CAV area have been correctly recorded at a constant rotation speed, it is judged that the disk is a specified dedicated disk, and the routine proceeds to Step 510.

(Step 510) The application program is loaded and executed.

(Step 511) Since the tracks in the CAV area are not recorded at a constant rotation speed, it is judged that the disk is out of the standard, and the process proceeds to step 512.

(Step 512) It is displayed that the disc is out of the regulation, and the disc is ejected.

[0037]

As described above, according to the present invention,
By recording a partial area of the optical disk by CAV, recording the other area by CLV, and setting the rotational speed of the CAV area so that the number of sectors on the track of the disk does not become an integer, The presence / absence can be used as a disc identification means, and the recording positions of the synchronization signals can no longer be aligned on the disc so that the CAV area cannot be visually identified.

[Brief description of drawings]

FIG. 1 is an external view showing an embodiment of an optical disc according to the present invention.

FIG. 2 is an external view showing an optical disc on which CAV recording is performed by a conventional method.

FIG. 3 is a diagram showing a signal format of a CD-ROM.

FIG. 4 is a block diagram of a CD-ROM drive.

FIG. 5 is a flowchart for checking that a part of the optical disc is recorded at a constant rotation speed.

[Explanation of symbols]

 1 ... 407 ... Preamplifier, 408 ... CD digital signal processing unit, 409 ... CD-ROM controller, 410 ... Host system.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Takeuchi, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture

Claims (1)

[Claims] 1. A CD for recording data delimited by sectors arranged according to a predetermined data format.
-In the ROM disc, a part of the area is recorded under the condition that the rotation speed is constant, and the other region is recorded under the condition that the linear velocity is constant. An optical disc characterized in that the number of sectors on a track is not an integer.