JP2672999B2 - Optical disk device data abnormality detection method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a data abnormality detection method for an optical disc device, which is suitable for determining whether or not data has been accurately recorded on an optical disc.

[Conventional technology]

FIG. 5 is a waveform diagram for explaining a conventional method of binarizing a read waveform from an optical disc. In FIG. 5, the waveform portions 503 and 504 represent the waveform shapes of drop-in and drop-out that may be erroneously binarized. That is, the read waveform 500 is binarized by the slice level 505. In the read waveform 500, the dropout or dropin waveforms 503 and 504 may occur due to dust or the like existing on the optical disc or the influence of the detection system.

In the prior art, for example, as disclosed in Japanese Patent Application No. 58-209032, the peak value of the read waveform 500 is level 501.
If it is between 502 and 502, it is judged that there is a possibility that it may be erroneously binarized, the waveform is regarded as abnormal, the same data is rewritten to another area in place of the sector where the abnormality has occurred, and again Normal data reproduction is guaranteed by confirming that there is no abnormality.

[Problems to be solved by the invention]

In the above-mentioned conventional technology, when the method of writing information on the optical disc is a method of writing information on the optical disc depending on the length of the pit (usually called the pit edge recording method), the sensitivity of the optical disc, the circuit system, the optical system, etc. Even if there is a large variation in the recording pit length, there is a problem in that it cannot be determined as abnormal.

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly reliable data abnormality detection method for an optical disc device, which detects data recording with an abnormal pit length in a pit edge type optical disk device.

[Means for solving the problem]

The data abnormality detection method of the magnetic disk device of the present invention is
The front and rear edges of the pit are detected from the read signal read from the optical disc, and it is determined whether the output time difference between the detected front and rear edges is within a predetermined range. If it is determined that
It is characterized in that the written data is judged to be abnormal and an error signal is output.

[Action]

According to this invention, during read-after-write,
The front edge and the rear edge of the pit are detected from the read signal read from the optical disk, the time difference between the output timings of the front edge and the rear edge is obtained, and it is determined from this time difference whether the data is within the reproducible range. If it is determined that the data cannot be reproduced, it is determined that the data writing has failed, and the error signal and the write conditions such as the write power and the correction value of the write pulse width are output.

This makes it possible to determine whether or not the data has been correctly written on the optical disc.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to examples shown in the accompanying drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In FIG. 1, the recording data recorded as pits on the optical disc 101 is converted into a read signal 103 by the optical head 102. As shown in FIG. 2, the recording pit 202 starts its formation when the recording data 201 first becomes “1”, finishes its formation when the recording data 201 next becomes “1”, and so on. It is formed by the process. Therefore, the recording pit 202 is formed in a long hole shape. Less than,
This method is called a pit edge recording method. Note that, as shown in FIG. 2, the data SD of a specific format is added to the beginning of the recording data 201. And data SD of specific format
Is followed by the data that should be recorded. Here, the pattern format and the number of bits of the data SD of the specific format may be arbitrary. The read signal 103 is amplified by the amplifier 104 and input to the edge detection circuit 106 as the read signal 105. The edge detection circuit 106, as shown in FIG.
The front edge and the rear edge of the recording pit 202 are detected and separated, and the front edge detection signal 107 and the rear edge detection signal 108 are detected.
Are output to the VFO circuits 109 and 113, respectively. VFO circuit 1
09 receives the front edge detection signal 107 and outputs the read synchronization clock 112 and the front edge detection signal 111 synchronized with this. Similarly, the VFO circuit 113 receives the trailing edge detection signal 108 and outputs the read synchronization clock 114 and the trailing edge detection signal 113 synchronized with this. The data synthesizing circuit 115 receives the read synchronous clocks 112, 114, the front edge detection signal 112, and the rear edge detection signal 113, and as shown in FIG.
A reproduction signal 117 synchronized with 18 is formed.

Further, the leading edge detection signal 107 and the trailing edge detection signal 113 output from the edge detection circuit 106 are input to the recording pit length variation determination circuit 116 as shown in FIG.
The recording pit length variation determination circuit 116 measures the input time difference Te between the leading edge detection signal 107 and the trailing edge detection signal 108 as shown in FIG. 3 for the data SD of the specific format shown in FIG. Is within a predetermined range. For example, it is determined whether or not the input time difference Te is within the range of (T-Tb / 2) <Te <(T + Tb / 2). Here, T represents a preset cycle of the leading edge detection signal and the trailing edge detection signal, and Tb is a value indicating its allowable range. When it is determined that the time difference Tb is within the predetermined range, it is determined that the recording data has been normally written. If it is determined that the value is out of the predetermined range, the error signal 119 and the correction value signal 120 are output. The correction value signal 120 is a signal for correcting the pit writing conditions (power setting, pulse width setting, etc.), and is output according to the amount of deviation of the time difference Te from a predetermined value.

In FIG. 3, when the trailing edge detection signal 108 is output at the timing 301, it is determined to be normal. When the trailing edge detection signal 108 is output at the timings 302 and 303, it is determined that an error has occurred, and the error signal 119 and the correction value signal 120 are output.

FIG. 4 is a block diagram showing a specific example of the recording pit length variation determination circuit 116 shown in FIG. As shown in FIG. 4, the recording pit length variation determination circuit 116 includes a counter 401 and a variation determination circuit 402 for measuring the time difference Te between the leading edge detection signal 107 and the trailing edge detection signal 108. The counter 401 receives the leading edge detection signal 107 and starts counting, and receives the trailing edge detection signal 108 and stops counting. The counted time difference Te is input to the variation determination circuit 402, and it is determined whether or not it is within a predetermined range. If it is determined that the difference is outside the predetermined range, the error signal 119 and the correction value signal 120 are output as described above. The variation determination circuit 402 includes a memory that stores a correction value such as the irradiation power of light or the pulse width of an optical pulse corresponding to the value of the time difference Te, and outputs the correction value signal 120 by reading the correction value from this memory. To do.

In the above embodiment, the edge detection circuit 106
The leading edge detection signal 107 and the trailing edge detection signal 108 output from are input to the recording pit length variation determination circuit 116 and it is determined whether or not the data recording is accurately performed, but the present invention is not limited to this. Not a thing, for example, the VFO circuit 109
The leading edge detection signal 111 output from the VFO circuit 113 and the trailing edge detection signal 113 output from the VFO circuit 113 may be input to the recording pit length variation determination circuit 116.

As described above, according to this embodiment, it is possible to accurately check the recording pit variation at the time of read-after-write, improve the quality of data writing, and guarantee normal data reproduction. It will be possible.

〔The invention's effect〕

According to the present invention, it is possible to sufficiently guarantee the quality of data written on an optical disc, and thus it is possible to significantly improve the reliability of reproduced data.

Further, even if there is a large variation in the recording pit length caused by the sensitivity of the optical disc, the circuit system, the optical system, etc., the data quality can be sufficiently guaranteed,
It is also effective in ensuring data compatibility.

[Brief description of the drawings]

1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the operation of the embodiment shown in FIG. 1,
3 is a waveform diagram for explaining the operation of the recording pit length variation determination circuit shown in FIG. 1, FIG. 4 is a block diagram showing a concrete example of the recording pit length variation determination circuit shown in FIG. 1, and FIG. The figure is a waveform diagram for explaining a method of binarizing a read signal from an optical disc according to a conventional technique. 101 ... Optical disk, 102 ... Optical head, 103 ... Read signal, 104 ... Amplifier, 106 ... Edge detection circuit, 107, 11
1 …… Front edge detection signal, 108,113 …… Rear edge detection signal, 109,113 …… VFO circuit, 115 …… Data combination circuit, 116
...... Recording pit length variation determination circuit, 119 ... Error signal, 120 ... Correction value signal.

Claims (1)

(57) [Claims] 1. A front edge and a rear edge of a pit are detected from a read signal read from an optical disk, and it is judged whether or not a difference in output time between the detected front edge and a rear edge is within a predetermined range. A data abnormality detecting method for a magnetic disk device, which judges that the written data is abnormal and outputs an error signal when it is determined that the data is out of a predetermined range.