JP2556354B2 - Optical disk medium evaluation device - Google Patents

Description

The present invention relates to an optical disc medium evaluation apparatus, and more specifically, to an extended constant angular velocity recording (MCAV) or extended constant linear velocity recording (MCLV) type optical disc. This is an evaluation device that determines whether a pre-formatted identification (ID) code is correct or not, and writes / reads a test pattern to evaluate the quality.

[Prior Art] An optical disc, which is widely used as an information recording medium, is capable of extremely high-density information recording by forming information pits at minute intervals in tracks with minute pitch intervals.
FIGS. 3 (a) and 3 (b) are for explaining the recording method of the optical disc. In FIG. 3 (a), the outer circumference of the optical disc 1 is 1a, and the recording range is between the circumferences 1b and 1c having an appropriate radius. A large number of tracks 1d are set within the range, and each track is divided into sectors S _{1 to} Sn at equal angles in the circumferential direction.
Sector information such as a sector mark (SM), a synchronization code (VFOSYNC), and an identification (ID) code for the sector number and track number is recorded in advance in each track for each sector as shown in FIG. Preformatted). When used, information data is recorded in the data area (DATA) following these sector information. A special code system different from the general code system is used in the optical disc, and the code conversion is performed for the exchange with the computer.

Recently, in order to increase the recording capacity of an optical disc, the size is increased (12 inches) and the recording method is improved or expanded.

FIG. 4 shows an extended recording method, in which the disk surface is divided into a plurality of track groups (G _{1 to} Gm) 1e in the radial direction, and the number of sectors is changed for each track group from the inside to the outside. The number of sectors is increased. There are two types of recording methods, one of which is a method in which the rotational angular velocity is constant (MCAV), and different clock frequencies are applied to the track groups so that the recording density of all tracks is almost constant. To use. The other is that the recording frequency of each track is almost constant by adopting the (MCLV) method in which the clock frequency is constant and the constant linear velocity rotation is performed for each track group.
On the other hand, it is necessary to perform sector information inspection and write / read evaluation test by a test pattern at the manufacturing stage of the optical disc.

[Problems to be Solved] A conventional optical disk medium evaluation apparatus is compatible with a constant angular velocity recording method with only one clock frequency, and is capable of switching the clock frequency with respect to the optical disk according to the extended recording method. , Or the function of changing the rotation speed is not provided, so that it is impossible to read the sector information and evaluate the medium performance by the test pattern. In this case, in the evaluation device, the rotational speed (angular velocity, linear velocity) of the optical disc has some fluctuations, and therefore it is necessary to stably read the sector information regardless of this fluctuation.

This invention is an ID code of a pre-formatted recording code system by switching the clock frequency for each track group for an (MCAV) system optical disk and the linear velocity for a (MCLV) system. Is read stably, and the read ID code is converted (demodulated) into a computer code to determine whether it is correct. It is another object of the present invention to provide a medium evaluation device for an optical disc that converts (modulates) a test pattern of a computer code into a recording code, writes / reads it, demodulates it into a computer code, and inspects whether it is good or bad.

[Means for Solving the Problems] The present invention is a medium evaluation apparatus for an optical disc of the above (MCAV) system or (MCLV) system, wherein each track has a synchronization code by a recording code, a track number, a sector number, etc. The optical disc pre-formatted with the identification (ID) code is targeted. The configuration includes a computer and a disk drive unit, a data read / write unit, and a test control / evaluation unit which are controlled by the computer.

The data read / write unit includes an optical head that reads / writes data from / to the optical disc, a bit detection circuit that detects a bit string from the signal read by the optical head, and a write control unit. The test control / evaluation unit inputs the bit string detected by the bit detection circuit and reproduces the ID code of the bit string synchronized with the clock frequency of the corresponding track group by the selection of the computer, and the reproduction data to the computer. Demodulation section that demodulates to the ID code of the code and demodulated ID
It is composed of a defect detection section for detecting a defect by comparing the code with an ID code preset in the computer, and a defect position memory for storing the position of the defect data.

In the above, the write pattern from the test pattern generator is modulated into a recording code by the write control unit to write / read to the data part of the optical disc, and the read pattern is demodulated into a computer code in the demodulation unit, The defect detection unit detects a defect by comparing it with the write pattern, and stores the position of the defect data in the defect position memory.

In the above, the selection of the above-mentioned data reproducing section for the (MCAV) type optical disc and the switching of the constant linear velocity corresponding to the track group for the (MCLV) type optical disc are performed by the computer by the demodulated ID code ( The track number and sector number) are identified.

[Operation] In the optical disk medium evaluation device of the present invention having the above configuration, the data writing / reading unit detects the ID code preformatted in the recording code format as a bit string, and the test control / evaluation unit In the case of the MCAV method, the data reproducing unit reproduces the ID code of the bit string synchronized with the clock frequency of the track group. In the case of the (MCLV) method, the computer switches the rotation of the constant linear velocity with respect to the track group to reproduce the ID code in the same manner. The reproduction data is demodulated into a computer code ID code in the demodulation section, and the defect detection section compares it with an ID code preset in the computer to determine the correctness. In the case of a test pattern, the writing pattern in the computer code format from the test pattern generator is modulated into the recording code format for writing / reading, and the read pattern is demodulated into a computer code in the demodulation unit, and the same as above. The comparison judgment is made. The position of the data determined to be defective according to the determination is stored in the defect position memory.

Next, regarding the selection switching of the data reproducing unit with respect to the clock frequency of the track group described above, the ID code obtained above in the computer identifies the last track number of the track group and the last sector number of the track. Can be switched. Also for the (MCLV) system, the constant linear velocity is switched by identifying each of the above numbers. It should be noted that the transition between the track groups can be skipped over the adjacent track groups in the order set in the computer in advance.

[Embodiment] FIG. 1 shows a block configuration in an embodiment of an optical disk medium evaluation apparatus according to the present invention. The configuration and operation of each unit will be described with reference to the drawings. The motor driver 32 of the disk drive unit 3 has a programmable rotational speed specified by the computer 2, and a current from this is supplied to the spindle motor 31 to drive the spindle motor 31. The optical disk to be inspected mounted on the disk rotates. Data read /
In the writing unit 4, an optical head 41 is provided corresponding to an optical disc, reads / writes data, and the read data is adjusted to an appropriate level by an amplifier (AMP) 42 and a bit detection circuit 43. Detects the bit string for the ID code. Bit detection circuit is AGC, LP
It is a normal one consisting of F, differentiating circuit and binarizing circuit.
In the test control unit 5, the above bit string is input to the data reproducing unit 51. The data reproducing section is provided with m sets of clock circuits 511 and variable frequency oscillators (VFO) 512, which are the same number as the (MCAV) type track groups, and the clock oscillator circuit oscillates a clock substantially equal to the clock frequency of each track group. ing. By the corresponding variable frequency oscillator, the frequency of the clock circuit is pulled into the input bit string,
The clock is synchronized with this. The bit string is converted into an ID code of the recording code by the synchronization, and is further selected by the computer in the selector 513 and input to the demodulation unit 52 to be demodulated into a computer code. The demodulated ID code is preset in the computer in the defect detection unit 53.
Whether it is correct or not is compared with the ID code, and if there is a defect, its position is stored in the defect position memory 54.

Next, an evaluation test using a test pattern will be described. An appropriate test pattern of a computer code is generated by the test pattern generator 55, modulated into a recording code pattern by the write control unit 44, and written in the data section of the optical disc 1 by the optical head 41. This is read and adjusted by amplifier 42 to an appropriate level. In this case, the read data is directly transferred to the demodulation unit 52 and demodulated into a computer code pattern,
In the defect detection unit 53, a defect is detected by comparison with the writing pattern. The operations of the defect detection unit 53 and the defect position memory 54 described above can be performed by a program process inside the computer 2.

Next, the selection switching of the clock (in the above, the data reproducing unit) in the data reproducing unit for the above track group will be described. This selection switching is the last track number in the track group of the ID code obtained above,
When the number of the last sector is identified by the computer and the rear end of the data area of the last sector is detected, the clock frequency of the adjacent track group is switched to. In this case, the identification of the final track and sector is performed by using not only each number but also the number of detected sector marks (see FIG. 3B).

According to the evaluation device of the present invention, it is also possible to perform an evaluation test by the (MCAV) method on an (MCLV) method optical disk.

FIG. 2 shows a flowchart of a computer for clock switching. First, when the switching sequence is started, when the sector number reaches the end, the trailing edge of the data area is detected and the clock switching for the adjacent track group is performed. To be Then, when the sector mark is detected, it is determined that the switching has been normally performed, the ID code or the information data of each track is detected and determined, and the switching is repeated until the number of switching becomes the same number m as the track group. If the sector mark is not detected at, the clock is switched again, and if the sector mark is detected, the above track detection is performed. When the sector mark is still not detected in and the number of switching is less than m, the process returns to and the clock is switched again. When the number of switchings reaches m, it is determined that none of the switchings has been normally performed, and error processing is performed, and the process ends. With the above, the evaluation test of one optical disk is completed. The constant linear velocity switching for the (MCLV) method is the same as above.

[Effects of the Invention] As is apparent from the above description, in the optical disc medium evaluation apparatus according to the present invention, the clock frequency switching corresponding to the track group for the (MCAV) or (MCLV) type optical disc, or The constant linear velocity is switched accurately, and the data is stably reproduced by the frequency pulling action of the data reproducing unit even if the rotational speed of the optical disc is slightly changed. In addition, for the ID code or test pattern of each track, the evaluation test can be completely executed by performing necessary modulation and demodulation between the computer code format and the recording code format. There are significant effects that contribute to the media evaluation of.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of an optical disk medium evaluation apparatus according to the present invention, FIG. 2 is a partial flowchart of computer processing for FIG. 1, and FIG. 3 (a).
6 and 7 are explanatory views of tracks and sectors of the optical disk and sector information set in the tracks, and FIG. 4 is an explanatory view of extended recording methods (MCAV) and (MCLV). 1 ... Optical disk, 1a ... Disk outer circumference, 1b, 1c ... Circumference, 1d ... Track, 1e ... Track group, 2 ... Computer, 3 ... Disk drive unit, 31 ... Spindle motor, 32 ...... Motor driver, 4 …… Data read / write unit 41 …… Optical head, 42 …… Amplifier, 43 …… Bit detector, 44 …… Write control unit, 5 …… Test control / evaluation unit, 51 ...... Data recovery unit, 511 ...... Clock circuit, 512 …… Variable frequency oscillator, 513 …… Selector, 52 …… Demodulation unit, 53 …… Defect detection unit, 54 …… Defect position memory unit, 55 …… Test Pattern generator, ... Flowchart number.

Claims (3)

(57) [Claims] 1. An extended type in which a large number of tracks set on a disk surface are divided into a plurality of track groups, each track group is divided into a different number of sectors, and a different clock frequency is used for each track group. Constant angular velocity recording (MCAV) method,
Alternatively, an extended constant linear velocity recording (MCL) which records information data at a constant linear velocity (hereinafter simply referred to as a constant linear velocity) which is different for each track group using a constant clock frequency.
In the evaluation test of the V) method optical disc, an identification (ID) code such as a synchronization code, a track number and a sector number according to a recording code system (hereinafter simply referred to as a recording code) for the optical disc is recorded on each track. An optical head for reading and writing data to and from the optical disk, which is provided with a disk drive unit for rotating the optical disk, which is controlled by a computer and targets the pre-formatted optical disk. A bit detection circuit for detecting a bit string from a signal detected by the head, a data read / write unit including a write control unit, and the bit string detected by the bit detection circuit are input, and the corresponding track is selected by the computer. Plays an ID code synchronized to the group clock frequency A data reproduction unit, an ID demodulation unit that demodulates the reproduction data obtained by the data reproduction unit into an ID code of the computer code system (hereinafter simply referred to as a computer code), and the demodulated ID code is set in the computer in advance. An optical disc, comprising: a defect detection section for detecting a defect in comparison with the ID code, and a test control / evaluation section including a defect position memory for storing the position of the detected defect data. Medium evaluation device. 2. In the above, a write test pattern from a test pattern generator is modulated into a pattern of the recording code in a write control unit, and writing / reading is performed on the data portion of the optical disc, and the read The demodulation unit demodulates the test pattern into the computer code pattern, the defect detection unit compares it with the write test pattern to detect a defect, outputs the position of the defect data, and stores it in the defect position memory. The optical disk medium evaluation apparatus according to claim 1, wherein 3. The selection of a computer for the data reproducing section in the (MCAV) type optical disc or the switching of the constant linear velocity for a track group in the (MCLV) type optical disc in the demodulating section of the computer. Demodulated into computer code
3. The optical disk medium evaluation device according to claim 1, wherein the ID code (track number, sector number) is identified.