JPS6325871A - Deterioration detecting system for recording media - Google Patents

Abstract

PURPOSE:To diagnose easily the condition of the deterioration of recording media by reading test data, correcting with an error correcting circuit and comparing the number of times of correction with the number of times of correction recorded at the recording media at the time of inspecting the deterioration of the recoding media. CONSTITUTION:By an error correcting code circuit 2, an error correcting code is added to the data inputted through a controller 1, and the data, to which the error correcting code is added, are recorded to an optical disk 5 by an optical pick-up 4. At the time of inspecting the deterioration of the optical disk, the test data written beforehand beforehand are read and reproduced from the optical disk 5, then a correcting action pulse outputted from an error correcting circuit 7 is counted for respective sectors by the controller 1 and the number of times of correction corresponding to the test data of respective sectors is counted. The number of times of the correction corresponding to respective sectors at the time of recording the test data recorded in the same optical disk 5 beforehand is read, the number of times of the correction counted concerning respective sectors and the number of times of the correction are compared and the deterioration of the recording media is detected.

Description

[Detailed Description of the Invention] [Summary] In order to detect deterioration of a recording medium used in a data recording/reproduction device that corrects data errors using an error correction code, an error correction code is added to the recording medium. The test data read out and the number of corrections performed by the error correction circuit are recorded. When inspecting the recording medium for deterioration, the test data is read and corrected by the error correction circuit. The deterioration of the recording medium is detected by comparing the number of corrections performed with the number of corrections recorded on the recording medium.

[Industrial application field]

The present invention relates to a method for detecting deterioration of a recording medium, particularly a recording medium such as an optical disk or a magneto-optical disk used in a recording apparatus that records data added with an error correction code.

[Conventional technology]

Recording media used in various recording devices gradually deteriorate due to changes over time, but this deterioration is rarely a problem in recording media used in recording systems with low recording densities.

However, in high-density recording/reproducing devices that record digitized data using the above-mentioned optical disks or magneto-optical disks as recording media, the recording density is high, so scratches, crystal defects, and dust on the recording medium can occur. If there is any adhesion or deformation of the recording medium, erroneous data will be immediately recorded or erroneous data will be reproduced, which will have an extremely serious effect.

Therefore, in the above-mentioned high-density recording/reproduction device, an error correction code is added to the data to be recorded and recorded on the recording medium, and the data read from the recording medium is processed using the above error correction code. Errors in read data are recovered by error correction.

However, although commonly used error correction codes have a high ability to recover from so-called bit errors such as small scratches, they can recover from so-called burst errors caused by abnormalities on the recording surface over a relatively wide range caused by deterioration of the material of the recording medium. There is a limit to the ability, and correct data cannot be reproduced depending on the data containing errors exceeding this limit.

Conventionally, as a means of detecting deterioration of recording media such as optical discs, the reflectance of the surface of the recording medium has been examined, but additional equipment is required for this purpose.
Furthermore, even if a recording medium with advanced deterioration that can be detected by visually inspecting the surface of the recording medium is reproduced, the error correction limit has already been exceeded and the recorded data cannot be reproduced without error. In many cases, this is not possible, and for this reason, it is necessary to prepare a data bank amplifier means.

[Problem that the invention seeks to solve]

The present invention improves the reliability of data by detecting deterioration of the recording medium at an early stage, and also transfers the data to another recording medium during the period when correct data can be reproduced by error correction from the read data and saves the data. It is designed so that it can be carried out.

[Means for solving problems]

Test data to which an error correction code is added is recorded on a recording medium, the test data is read from the recording medium, errors are corrected by an error correction circuit, and the number of corrections is further recorded on the recording medium.

When inspecting the recording medium for deterioration, the recorded test data is read out and corrected by an error correction circuit.
Deterioration of the recording medium is detected by comparing the number of error corrections with the number of corrections recorded on the recording medium.

[For production]

As the recording medium deteriorates, the recording state of data written on the recording medium also changes, and the data read from the recording medium will be read as data different from the data recorded before the deterioration.

The present invention records test data to which an error correction code is added on the recording medium before the recording medium deteriorates, for example, at the time of shipping the recording medium or before the user starts using the recording medium. is read out and corrected by an error correction circuit, and based on the number of corrections, the amount of recording errors in the recording state of this recording medium before deterioration is determined and recorded on this recording medium.

When the above test data is read from this recording medium at the time of inspection, the test data will be different from the test data at the time of recording because the recording state of the test data on this recording medium has changed depending on the deterioration of the recording medium. The error correction circuit corrects the test data read from the recording medium when inspecting the recording medium for deterioration. The number of corrections performed by the error correction circuit also increases.

Therefore, before the recording medium deteriorates, such as before shipping the recording medium or before the user starts using it, test data and the number of corrections made by reading the test data and correcting it by the error correction circuit are recorded on the recording medium. Diagnose the state of deterioration of this recording medium by reading out this test data when inspecting the deterioration of the medium, making corrections using the error correction circuit, and comparing the number of corrections with the number of corrections recorded on this recording medium. Can be done.

〔Example〕

First, the recording of test data and the number of corrections and its format will be explained.

FIG. 1 is a diagram conceptually showing the state in which the test data and the number of corrections according to the embodiment are recorded on an optical disk in which the capacity of one sector is 2048 bytes.As shown in FIG. Byte ascending data “00”
” to “FF” (in hexadecimal notation) are repeated 8 times and written in one sector, and this writing is performed for 128 sectors (in the figure, sector numbers are shown as 1 to 128).

Next, the test data written in the above 128 sectors is read from the disk, and the error correction circuit performs error correction. At the time of error correction, for example, the correction operation pulses output from the error correction circuit are counted for each sector. 128 correction times n, ~n corresponding to each obtained sector
For example, +zs is set to 16 in one sector as shown in the same figure (b).
Write repeatedly.

Such test data can be written when the manufacturer ships the disk or when the user uses the disk for the first time.

Next, a method for determining the deterioration of a disk on which test data and the number of corrections are recorded as described above will be explained.

Now, if the number of corrections recorded when writing test data corresponding to test data of an arbitrary sector is N6%, and the number of corrections counted by reproducing test data of this sector when inspecting disk deterioration is N, then Compare the initial number of corrections N0 and the number of corrections during inspection for each sector, and if there is at least one sector that satisfies the following formula % formula % (1) (where α is a constant described later), deterioration is detected. is judged to be in an advanced state.

However, the constant α in equation (1) is set as follows.

Errors in data read from a disk include those that always occur at a fixed location due to scratches or crystal defects on the disk, and those that occur due to fluctuations in location or number of errors due to fluctuations in disk rotation or jitter in the read signal. Even with the same data in the same recording area, the number of errors that occur in combination due to different types of factors varies each time it is read, and the distribution of the number of corrections is based on a fixed number of corrections. Dispersion occurs around the center.

Furthermore, as the disk deteriorates, the number of errors that always occur will generally increase, so as the disk deteriorates, the number of corrections, which is the center of variation, will also increase.

FIG. 2 is a diagram showing the initial state of the disk on which test data has been recorded and the frequency distribution of the number of corrections when the disk has deteriorated to some extent.

As mentioned above, there is a variation β in the number of corrections during data reproduction, so for example, even if the number of corrections recorded in the initial state for a certain sector is the minimum number of corrections Na at point a, the test of that sector at the time of inspection Since the number of corrections during data reproduction may be Nd at point d, deterioration is determined simply when the number of corrections N counted by reproducing the test data during inspection exceeds the pre-recorded number of corrections N0. cannot be used as a standard.

Therefore, if the criterion for determining deterioration is when the number of corrections counted at the time of inspection is greater than the maximum number of corrections Nb that can occur in the initial state, then error 1 indicates that the initial state is considered to be a state of advanced deterioration. There is no judgment.

In other words, α〉β ・・・・・・・・・・・・・・・・・・・・・
The constant α is set so as to satisfy (2).

Note that the minimum number of corrections and the maximum number of corrections are not fixed values, so a certain amount of difference between α and β may be provided.

FIG. 3 is a block diagram of a recording/reproducing apparatus using an optical disk as a recording medium to which the deterioration detection method of the present invention is applied. An error correction code circuit 2 adds an error correction code to the data, and a modulation circuit 3 modulates the data with the error correction code into a recording signal and adds a synchronization signal to record it on a recording medium. The necessary signals are recorded on the optical disc 5 by the optical pickup 4.

When reproducing data, the signal read from the optical disk 5 by the optical pickup 4 is demodulated by the demodulation circuit 6, and the data containing the demodulated error correction code is subjected to error correction by the error correction circuit 7, and the data is reproduced. This reproduced data is output to the host processor via the controller 1.

In this embodiment, a correction operation pulse is output to the controller 1 every time the error correction circuit 7 performs correction during reproduction, so that the number of corrections can be detected by the controller or the host processor.

With such a recording/playback device, test data is written as described above and played back before using the optical disk, and the controller 1 counts the correction operation pulses output by the error correction circuit 7 during playback. The number of corrections obtained is written on the optical disc 5.

When inspecting the optical disc for deterioration, test data written in advance is read out from the optical disc 5 and reproduced, and the controller 1 counts the correction operation pulses output from the error correction circuit 7 for each sector to obtain test data for each sector. Count the number of corrections corresponding to .

In addition, the number of corrections corresponding to each sector at the time of recording test data recorded in advance on the same optical disk 5 is read out,
The number of corrections counted for each sector above is compared with this number of corrections, and if a sector that satisfies equation (1) is detected as described above, the controller 1 issues a warning to the host processor and notifies the detection of optical disk deterioration. be done.

In the embodiment described above, 256 bytes of ascending data are written as test data in 128 sectors, but the present invention provides a formant or an error correction method for writing the number of sectors, the content of test data, the test data and the number of corrections. It is not limited by.

〔Effect of the invention〕

According to the present invention, it is possible to detect deterioration of a recording medium such as an optical disk at an early stage, issue a warning, and obtain a guideline for saving data before correction becomes impossible with an error correction code.

In addition, by recording test data on a recording medium,
It is possible to inspect the recording medium for deterioration without adding any special circuit.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the recording state of test data and the number of corrections in the embodiment, Fig. 2 is a diagram showing the frequency distribution of the number of corrections, and Fig. 3 is a block diagram of an optical disc recording/reproducing device to which the embodiment is applied. It is a diagram. 1 is a controller, 2 is an error correction code circuit, 3 is a modulation circuit, 4 is an optical pickup, 5 is an optical disk, 6 is a demodulation circuit, and 7 is an error correction circuit.

Claims (2)

[Claims] (1) To detect deterioration of the above-mentioned recording medium used in a data recording/reproduction device that reads data from a recording medium that records data to which an error correction code has been added and uses this correction code to correct data errors. Then, test data to which an error correction code has been added is recorded on a recording medium, this test data is read out, an error correction circuit performs error correction, and the number of corrections is further recorded on this recording medium. When performing a deterioration test,
The above test data is read from this recording medium, the error correction circuit performs error correction, and the number of corrections is compared with the number of corrections recorded on this recording medium, and the number of corrections exceeds a predetermined number of corrections. A method for detecting deterioration of a recording medium, characterized in that deterioration of the recording medium is detected by: (2) The recording according to claim 1, characterized in that the test data and the number of corrections for the test data are written on the recording medium at the time of shipment of the recording medium or before the user starts using it. Media deterioration detection method.