JP3203985B2 - Optical disc playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention checks whether an optical disk such as a CD-ROM (compact disk ROM) in which information such as a TV (television) game is stored is legitimate and performs unauthorized copying. The present invention relates to a reproducing apparatus for preventing such a situation.

[0002]

2. Description of the Related Art At present, most optical disks such as CD-ROMs are formatted according to published standards such as "ISO9660". Various software such as TV games should be protected from illegal copying from the viewpoint of copyright protection. However, if the software is formatted according to the published standards as described above, Restrictions are added to copy protection measures.For example, a copy protection code is recorded in advance, and if there is the code at the time of reproduction, it is a legitimate disk, and if there is no code, it is regarded as an illegal copy disk and the reproduction is performed. Stopping is performed.

[0003] However, in such an illegal copy prevention measure, if a copy machine for copying the data described in the logical standard as a whole is manufactured, it is possible to easily copy the data, which is not a very effective method.

In the case of CD-ROMs which have been commercialized relatively quickly, most of the CD-ROMs have been produced by making their own standards before the above-mentioned standards have been established.
D-ROMs conforming to this standard will be mainstream.
Then, CDs with weak copy protection are circulated, and illegal copying is circulated, and the same situation is likely to occur especially for CD-ROM type game software.

Therefore, as a copy prevention measure for a new CD, for example, as shown in Japanese Patent Application Laid-Open No. Sho 61-178732, "pseudo pits" of pits smaller than normal pits are formed on a disk, and the pseudo pits are detected. By doing so, the composite output is deformed to prevent copying.

[0006]

However, as described above, the format can be written in accordance with the standard by writing a code for copy protection, by a proprietary standard, or by including pits. Also normal C
Even if the software cannot read the D-ROM, any disc can be copied by a copying machine that reads data in units of lower-level frames and copies the data to a CD-write-once disc or the like. There was a problem.

In particular, when forming a pseudo pit, not only the pseudo pit is formed smaller than the normal pit and mass production is required, but also strict management is required.
Since small pseudo pits have to be detected, there has been a problem that the detection reliability is reduced. As a related technique, as disclosed in Japanese Patent Application Laid-Open No. 4-353631, there is also a technique in which different transfer rate areas are allocated to a disk having a plurality of recording transfer rates mixed according to the amount of information. Although it has been developed, it aims at improving the recording efficiency of the optical disk, and does not take any copy protection measures.

The present invention focuses on the above problems,
The present invention has been made to solve this problem effectively, and an object of the present invention is to provide an optical disk reproducing apparatus capable of reliably preventing unauthorized copying.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a track formed by arranging a large number of pit rows concentrically or spirally.
In a reproducing apparatus for reproducing an optical disk in which the recording transfer rate of some tracks is different from the recording transfer rate of a normal track, an address recorded at the recording transfer rate of a normal track and a recording different from this recording transfer rate A storage unit for storing an address recorded at a transfer rate; a measurement unit for measuring a rotation cycle of the optical disc at the two addresses; and a rotation cycle measured by the measurement unit based on a predetermined formula. And a control unit that determines whether or not the optical disc is legitimate based on the comparison result of the comparison unit.

[0010]

The present invention has been configured as described above.
Based on the addresses in the storage unit, the normal track of the optical disk and the addresses of some of the tracks at different rates are respectively sought, and the rotation cycle of the optical disk at each of these addresses is measured by the measuring unit. The measured rotation cycle is compared in a comparison unit based on a predetermined calculation formula. Here, the normal optical disk is recorded at a predetermined address portion at a recording transfer rate different from that of the other portions, so that the control section will generate a change if the recording transfer rate has changed as a result of the comparison. If the result indicates a wax comparison, the optical disk is determined to be a legitimate optical disk. If the result indicates another comparison, the optical disk is determined to be an unauthorized optical disk. As an example of this determination process, for example, CLV (Constant Linear Vel)
In the case of the (ocity) method, a rotation cycle is obtained, and a determination regarding the optical disc is made based on whether or not the rate of change of the rotation cycle is greater than a predetermined value.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical disk reproducing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing an optical disk reproducing apparatus according to the present invention,
FIG. 2 is a schematic plan view showing an optical disk reproduced by the apparatus of the present invention, and FIG. 3 is a graph showing a relationship between a normal optical disk address and a rotation cycle.

As shown in FIG. 2, the optical disk 1 has a track 2 formed by arranging a large number of pit rows concentrically or spirally. In the illustrated example, tracks arranged in a spiral shape are shown.
Most of the track 2A of the track 2 has a higher pit density and is recorded at a normal high recording transfer rate.
Track 2B is recorded at a low recording transfer rate, for example, in which the pit density is made smaller than the previous pit density. Track 2B recorded at a low recording transfer rate corresponds to one or a plurality of tracks from address at1 to at2, and in the example shown in FIG.
The number of tracks is equal to the number of tracks, but the tracks may be formed over a plurality of rotations. An optical disk having tracks partially recorded at a recording transfer rate different from that of its peripheral portion is regarded as a legitimate optical disk.

The reproducing apparatus according to the present invention is used for reproducing the optical disk. The reproducing apparatus has a determining function for determining whether the optical disk is legitimate. First, the optical disk 1 is installed and fixed on a turntable (not shown) rotatable by a spindle motor 3. And the pickup unit 4
Has an optical system including a laser oscillator and a lens 5 inside, and reads out recorded information on an optical disk surface by a laser beam 6.

The servo processing unit 7 includes a focus unit 7A and a tracking unit 7B for controlling the driving of the pickup unit 4.
And a driver unit 7 for controlling the driving of the spindle motor 3
C, and a pickup unit 4 for the optical disc 1.
Focusing and tracking are performed, and the rotation speed of the optical disc is adjusted appropriately, for example, CLV (Constant).
ant Linear Velocity).

The data output of the pickup unit 4 is connected to the servo processing unit 7 and the signal processing unit 8, respectively. The signal processing section 8 is a section for reproducing and processing an image signal, an audio signal, and the like.
case Locked-Loop) circuit, EFM (E
right to Fourteen Modulati
on) decoder, CIRC (Cross Interl)
An address decoder 9 as a code error correction unit and an address recognition unit of an eave Reed-Solomon Code) system is provided.

The signal processing unit 8 and the servo processing unit 7 are, for example, a control unit 1 comprising a microcomputer or the like.
0 controls its operation. The control unit 10 includes:
Normal track 2 recorded at a high recording transfer rate
A specific address a in A and track 2 recorded at a recording transfer rate lower than the above-described recording transfer rate
A storage unit 11 composed of, for example, a ROM for recording a specific address b of B, and a measuring unit 12 for measuring the rotation cycle of the optical disk 1 at each of the addresses a and b are connected. The specific address b is located between the addresses at1 and at2 as is clear from FIG. Further, a comparison unit 13 is connected to the control unit 10 for comparing the two measured values measured by the measurement unit 12 based on a predetermined formula, and based on the comparison result, the control unit 10 Determines whether the optical disc 1 is a regular one. Further, the control unit 10 has a timer 14 for measuring time therein.

Next, the operation of the present embodiment configured as described above will be described. Here, as shown in FIG. 2, a regular optical disc has a recording area having a different recording transfer rate, for example, a small recording area, in the middle of a track, and the same recording transfer rate is applied to other optical discs, for example, all tracks. The optical disk recorded at the rate is irregular.

In this embodiment, the CLV method is used in which the rotation speed of the optical disk is controlled so that the rotation speed of the optical disk decreases as the seek position of the pickup portion moves outward in the radial direction of the optical disk so that the linear velocity of the track is always constant. The case of (1) will be described as an example. First, a laser beam 6 condensed from a pickup unit 4 via a lens 5 is applied to the optical disk surface, and recorded information is read out by the reflected light.
The read signal is input to the servo processing unit 7, and the servo processing unit 7 controls the focusing and tracking of the optical disk 1 by the pickup unit 4 based on the focus error signal and the tracking error signal formed here. . At the same time, the servo processing unit 7 performs CLV control of the spindle motor 3 based on a command from the control unit 10.

The signal read out by the pickup unit 4 is also input to a signal processing unit 8, where it is EFM decoded or a code error is corrected to reproduce an audio-visual signal or the like. In the section 8, the address of the information is read out or decoded to be obtained.

Next, a case will be described in which it is checked whether or not the currently used optical disc 1 is legitimate. First, when the recorded information of this optical disk is reproduced, as shown in FIG. 3, as the address value increases from left to right on the horizontal axis, the rotation speed decreases and the rotation period increases with time due to the CLV method as the address value increases. Go.
In this embodiment, as the track is closer to the center of the optical disc,
Address value is too small.

Here, in the case of a regular optical disk, the recording transfer rate is set to be small from the addresses at1 to at2, so that the rotation speed of the disk increases in this part in order to keep the transfer rate constant. The rotation cycle decreases. Then, after passing the area between the addresses at1 and at2, the disk returns to the original rotation cycle. In FIG. 3, the dashed line indicates the transition of the rotation cycle of the optical disc when the recording transfer rate is constant over all tracks, that is, the irregular optical disc.

Accordingly, the rotation period (reciprocal of the rotation speed) at a predetermined address, for example, address a in a track having a high recording transfer rate, and the rotation period at a predetermined address, for example, address b, in a track having a low recording transfer rate. By comparing, for example, the rate of change of the rotation cycle with a predetermined calculation formula, it is possible to determine whether the optical disc is correct.

The procedure of the check mode will be described with reference to FIGS. 4 and 5. First, in S1, it is determined whether or not the optical disk is set. If YES, the optical disk is CD-ROM or DA-ROM. (Digital audio) is determined (S2). Here, when the disc is DA, the DA reproduction processing is performed as it is (S3). When the disc is CD-ROM, the pickup unit 4 is moved to a predetermined address a of the normal track based on the information in the storage unit 11. The seek is performed (S4), and the rotation cycle of one rotation of the disk in this portion is measured (S5).

The determination as to whether or not the pickup section 4 has accessed a predetermined address is made by looking at the output value of the address decoder 9. Here, the procedure of measuring the rotation period will be described with reference to FIG. 5. First, the address currently accessed by the pickup unit 4 is read (SS1), and it is determined whether or not this address is the initial address (SS2). Here, the initial address indicates, for example, the first sector of each track.

If the read address is not the initial address, the next address is read sequentially. If the read address is the initial address, the timer 14 of the control unit 10 is cleared and then started to measure the time (SS3). Subsequently, the address is read (SS4), and it is determined whether or not the address after one rotation of the disk, that is, for example, is the last sector of the track (SS5). When the disk has made one rotation, the timer 14 is stopped, and the timer value at this time is the rotation cycle at address a,
For example, it is Ta (SS6). The rotation cycle Ta is temporarily stored and held.

After measuring the rotation period in this way, the flow returns to the flow shown in FIG. 4 again, and next, the addresses at1 and at2 of the tracks recorded at a low recording transfer rate.
The pickup unit 4 seeks to the address b between (S
6) The rotation cycle of the optical disk is measured in the same process as described with reference to FIG. 5 (S7). The rotation cycle at this address is Tb. If the optical disc is a regular one, the rotation cycle Tb becomes short because the recording transfer rate of the area at the address b is low. Then, the comparison unit 13 calculates, for example, the following equation (1) to determine the rate of change of the rotation cycle, and determines whether the rate of change is less than a predetermined set value H (S8).

(Tb−Ta) / Ta (1)

As the predetermined value H, the value obtained when the rotation cycle Tb 'at address b in the case of a disc (an irregular disc) in which all tracks are recorded at a fixed recording transfer rate is given to the above equation (1). Regular disk rotation period T
What is necessary is just to select a value that is substantially intermediate between the values obtained when b is given in the above equation 1.

As a result of this judgment, if the value obtained by the equation 1 is equal to or smaller than the set value H (YES), the part of the track where the recording transfer rate is partially low is recorded. Is present, the control unit 10 recognizes that the disc is a legitimate disc (S9) and continues the reproduction operation as it is. On the other hand, when the value obtained by Expression 1 is larger than the set value H (NO), it means that the recording transfer rate of the portion corresponding to the address b is not lower than the surroundings. Therefore, the control unit 10 recognizes that the disc is an unauthorized disc (S10), and takes copy prevention measures such as disc ejection operation (S1).
1).

As described above, a recording area having a low recording transfer rate is provided in a part of the optical disk at a predetermined address, and the rate of change of the rotation cycle of this part is compared with that of the other parts to thereby obtain the optical disk. Is legitimate or an irregular one such as a copy.

For example, if the above-mentioned information on an optical disk is read by a normal CD-ROM drive or the like in order to copy the information, it cannot be correctly copied to a CD write-once disk or the like because no modification has been made on the main data. No error. Although a large number of duplicated disks can be produced using this copy disk as a master disk, even if the main data can be duplicated, a portion having a low recording transfer rate cannot be duplicated. Then, since the change in the rotation cycle as described above is not detected, the disc is recognized as an irregular disc and cannot be reproduced. Therefore, copy can be prevented.

In the above-described optical disc, it is difficult to analyze the code because the code is not written in the main data. Moreover, even if dust or scratches are formed on the disk surface, the durability can be improved against them, unlike copy protection measures in pit units.

In the above embodiment, when two rotation periods are compared, the rate of change of the rotation period is determined.
The method is not limited to the above-described comparison method as long as it is possible to recognize whether or not the rotation period is changing linearly, and any comparison method may be used. Further, in the above-described embodiment, the case where the recording transfer rate of a part of the track is set to be lower than that of the other part has been described. Alternatively, the recording transfer rate may be set to be higher than that of the other part.

Further, in the above embodiment, the optical disk is CL
Although the case of rotating in the V method has been described, the invention is not limited to this, and CAV (Constant Angular) is used.
Of course, the present invention can be applied to the case of the (Velocity) method. In this case, when the recording transfer rate is partially set to, for example, a small value, the rotation cycle of the portion becomes smaller than that of the other portions, so that the determination can be easily performed.

[0035]

As described above, according to the optical disk reproducing apparatus of the present invention, the following excellent operational effects can be exhibited. When reproducing a regular optical disk having recording tracks with different recording transfer rates in part, the rotation period of the portion having the different recording transfer rate is compared with the rotation period of the other normal recording transfer rate. Therefore, it can be easily determined whether or not the optical disk is a legitimate optical disk. Further, since the present invention can be adopted only by rewriting the software in the reproducing apparatus, there is no burden on hardware, which is advantageous in cost. Furthermore, since the rotation cycle is measured in a state where servo with good rotation accuracy is applied and the timer accuracy is high, the reliability of detection can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an optical disk reproducing apparatus according to the present invention.

FIG. 2 is a schematic plan view showing an optical disc reproduced by the apparatus of the present invention.

FIG. 3 is a graph showing a relationship between an address of a regular optical disc and a rotation cycle.

FIG. 4 is a flowchart showing a procedure for checking whether or not the optical disc is legitimate.

FIG. 5 is a flowchart showing a procedure for measuring a rotation cycle of the optical disc.

[Explanation of symbols]

1 optical disk, 2 track, 4 pickup unit,
5 lens, 6 laser light, 7 servo processing unit, 8 signal processing unit, 9 address decoder, 10 control unit, 11
... Storage unit, 12 Measurement unit, 13 Comparison unit, 14 Timer, a, b, at1, at2.

Claims (2)

(57) [Claims] An optical disk in which a recording transfer rate of a part of a track formed by arranging a large number of pit rows concentrically or spirally is different from a recording transfer rate of a normal track is reproduced. In a reproducing apparatus, a storage unit for storing an address recorded at a recording transfer rate of a normal track and an address recorded at a recording transfer rate different from the recording transfer rate; A measuring unit that measures a rotation cycle, a comparison unit that compares the rotation cycle measured by the measurement unit based on a predetermined formula, and the optical disc is authentic based on a comparison result of the comparison unit. An optical disc reproducing apparatus comprising: a control unit for determining whether or not the optical disc is in the optical disc. 2. The optical disk reproducing apparatus according to claim 1, wherein a recording transfer rate of said partial track is set lower than a recording transfer rate of said normal track.