JPH05274675A - Method for inspecting optical disk - Google Patents

Abstract

PURPOSE:To prevent the degradation of a medium by shifting the position of test data at random at every write of the data repeated and writing on a different part of a phase change medium. CONSTITUTION:Random shift amt. data at every 1 track is stored in a shift amt. generator 34 previously and the shift amt. data is generated by the input of a starting sector and a shift data selector 35 is operated by the data and a start signal and a gate signal are shifted at every 1 track at random. By both shifted signals, the position of write data generated by a write data generation circuit 38 is shifted at random and the write data is inputted to the light source 21 of an optical head 2 through a pulse width correction circuit 37. The light source 21 outputs the spot Sv of a writing level and the writing is executed on a disk 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase change recording type optical disc inspection method.

[0002]

2. Description of the Related Art As a recording medium of an information processing apparatus, there is a rewritable optical disc using a phase change medium. As the phase change medium, for example, an oxide of tellurium to which germanium and tin are added is used, and this is vapor-deposited on the substrate. Immediately after vapor deposition, it is amorphous and has a low reflectance (15%), but when it is heated and cooled, it crystallizes and has a high reflectance (30%). An optical disk of a phase change recording system (hereinafter simply referred to as an optical disk) is configured by using this crystallized state as an unrecorded medium. A method of writing / reading and erasing data on the optical disc will be described with reference to FIG. (A) of Figure 3
Is a phase change medium (hereinafter simply referred to as medium) 1b on the substrate 1a.
Shows an optical disc 1 on which the medium is vapor-deposited, and the medium 1b is a crystal body having a high reflectance at this stage. As the contrast (b) is irradiated with laser spot S _W write level,
The irradiated portion is heated and rapidly cooled to return to an amorphous state, the reflectance is lowered, and data is recorded. (C) shows the reading of data, and when the spot S _r at the reading level is irradiated, the data is read due to the difference in the intensity of the reflected light. Next, in order to erase the data, as in (d), the spot S _{e of the} erase level is irradiated to gradually heat and cool the medium, and the medium is recrystallized to erase. In the above, the crystallization of the medium has a certain critical temperature, and when converted into the intensity of the laser spot, it is about 10 mW, for example, the write spot S _W , is 20 mW, the read spot S _r is 5 mW, and the erase spot is S _e is 3 of 10 mW
It is considered as a stage.

A data recording area of the above optical disk will be described with reference to FIG. In (a), a large number of tracks T _R are formed in the circumferential direction on the optical disc 1, and each track T _R is divided into a plurality of sectors S _{0 to} S _m . (b)
Shows a development view of a sector, and each of the sectors S _{0 to} S _m comprises an ID section for recording identification information such as a sector number and a data (DATA) section for recording data. (c) indicates the data recorded on the track T _R with a black circle. In the fabrication of the optical disk 1, is first穿溝the groove track T _R on the master by etching, the stamper is made of nickel-plated from master, this higher number of optical disks will be replicated. The data in the DATA section is rewritten,
Since the ID section does not need to be rewritten, the ID information is pre-formatted together with the track at the stage of the master.

If there is any defect in the medium of the above optical disk, the recording performance is deteriorated. Therefore, the inspection device detects the defect, and the quality is evaluated and classified based on the result. In the inspection, writing and reading of test data is performed on the DATA part, a defect is detected by comparing with the original write data, and when this is finished, the data is erased. However, since a single test is not sufficient for highly reliable inspection, the DATA portion of each track is repeatedly tested a plurality of times.

[0005]

In the above-mentioned plural times of tests, the same test data is repeatedly written, read and erased in the same portion of the DATA portion. Due to the irradiation of the laser spot for this purpose, the same portion of the medium is melted and the crystallization and the non-crystallization are repeated, so that the fluidity of the medium changes and there is a risk that the recording performance deteriorates. Therefore, there is a need for an inspection method in which the performance does not deteriorate even after repeated tests. On the other hand, it is effective and simple method not to write the test data in the same portion of the medium. Based on the above idea, it is an object of the present invention to provide an inspection method capable of testing a plurality of times without deteriorating the quality of a phase change medium of an optical disc.

[0006]

SUMMARY OF THE INVENTION The present invention is an inspection method for achieving the above object, wherein in the above optical disc inspection apparatus, the position of test data is randomly shifted every time data is repeatedly written, Write to different parts of the phase change medium. The written test data is read, original test data before writing is generated by the read data mark, and the original test data generated is compared with the read test data to inspect the phase change medium. ..

[0007]

In the above inspection method, the position of the test data is randomly shifted every time data is repeatedly written, and different portions of the medium are written. In reading, the original test data is generated by the data mark and this is compared with the read test data. The position of the medium to be written, read and erased changes each time the test is performed. Also, there is no risk of deterioration of the medium.

[0008]

1 and 2 show an embodiment of the present invention. FIG. 1 is a test data generating / writing unit, and FIG. 2 is a data reproducing / writing unit.
The schematic block configuration of each of the inspection units is shown. In FIG. 1, 2 is an optical head and 3 is a test data generator. The start signal and the gate signal output from the timing generator 31 of the test data generator 3 are converted into an arbitrary shift amount by the shift register 32. On the other hand, in the optical head 2, the light source is
A laser spot S _r (see FIG. 3) at the read level is emitted from the disk 21 and the reflected light is input to the code detector 23 via the beam splitter 22. The data read section 33 decodes the write start sector of the detected data signal and inputs it to the shift amount data generator 34. Random shift amount data for each track is stored in advance in the shift amount generator 34, and shift amount data is generated by the input of the start sector, which operates the shift data selector 35 to start the above-mentioned start signal and The gate signal is randomly shifted for each track. The shifted signals randomly shift the position of the write data generated by the write data generating circuit 36, and the write data is input to the light source 21 of the optical head 2 via the pulse width correction circuit 37. The light source 21 outputs a writing level spot S _W corresponding to the write data, and writing is performed on the disc 1. When the writing on one track is completed, the following data read, reproduction and defect detection are started in one rotation of the disk.

In FIG. 2, the laser spot S _r at the read level is output from the light source 21 to read the test data written as described above. The read signal is differentiated by the differentiating circuit 41 of the data reproducing unit 4, and a part of the output is input to the data mark detecting circuit 42, and the data mark at the head of the test data is detected. By the input of the detected data mark, the write data generation circuit 43 generates the original test data before writing and inputs it to the comparison processing unit 44. On the other hand, part of the output of the differentiating circuit 41 is the comparison processing circuit 44.
, A defect is detected by comparing with the above-mentioned original test data, and then, in the next one revolution of the disk, the erasing level spot S _e is outputted from the light source 21 to erase the data and perform one test. Ends. The above test is repeated a plurality of times, and the defect detection signal obtained as described above is sequentially subjected to predetermined processing by the data processing unit 5 for each test, and evaluation data for evaluating the quality of the medium is created. Note that each element of the block configurations of FIGS. 1 and 2 is based on a normal technique, and detailed description of the operation of each element is omitted. Further, each block configuration is an example, and details may be different from those as long as they can realize the scope of the claims.

[0010]

As described above, in the optical disc inspecting method according to the present invention, the position of the medium on which the test data is written changes randomly at each test. Therefore, the repeated test of write, read and erase is performed. However, the medium does not deteriorate, and it greatly contributes to strict inspection of the phase change recording type optical disk.

[Brief description of drawings]

FIG. 1 shows a schematic block configuration of a test data generating / writing unit in an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a data reproducing / reproducing method according to an embodiment of the present invention.
1 shows a schematic block configuration of an inspection unit.

FIG. 3 is an explanatory diagram of a recording principle of an optical disc of a phase change medium recording system.

FIG. 4 is an explanatory diagram of a data area of an optical disc of a phase change medium recording system.

[Explanation of symbols]

1 ... Phase change recording type optical disk, 1a ... Substrate, 1b ...
Phase change recording medium, 2 ... Optical head, 21 ... Light source, 22 ... Beam splitter, 23 ... Code detector, 3 ... Test data generator, 31 ... Timing generator, 32 ... Shift register, 33 ...
Data reading unit, 34 ... Shift amount data register, 35 ...
Shift selector, 36 ... Write data generation circuit, 37 ... Pulse width correction circuit, 4 ... Data reproduction section, 41 ... Differentiation circuit, 42 ...
Data mark detection circuit, 43 ... Write data generation circuit, 44
... Comparison processing unit, 5 ... Data processing unit.

Claims (1)

[Claims] 1. An inspection apparatus for inspecting the performance of a phase change medium by repeatedly writing, reading and erasing test data having a data mark as a head on a data portion of a phase change recording type optical disk, For each repeated writing, the position of the test data is randomly shifted, writing is performed on different portions of the phase change medium, the written test data is read, and the data mark before writing is read by the read data mark. A method of inspecting an optical disc, comprising: generating original test data, comparing the generated original test data with the read test data, and inspecting the phase change medium.