JPH05189764A - Optical disk device - Google Patents

Abstract

PURPOSE:To provide an optical disk device in which throughput of read processing and write processing is improved, also which is suitable for protection of data on an optical disk. CONSTITUTION:A position of a dropout detected by the dropout detecting section 40 is stored in the serial memory 90, an amount of the dropout is measured by the counter 50. When the value of the counter 50 becomes larger than the value preset in the flip flop 70, an optical head reads an optical disk again by control of the optical head control means, and when the position of the dropout is read, an output and a gain of the laser 35 connected to the laser output control section 30 and the automatic gain control means 10 are changed based on the dropout position stored in the serial memory 90.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device for reading an optical disk on which predetermined information is recorded by an optical head, and more particularly to a case where a dropout occurs due to a scratch on the optical disk. Also relates to an optical disc device capable of reading information.

[0002]

2. Description of the Related Art An optical disk device irradiates a laser on an optical disk and an optical head reads the laser to obtain data stored in the optical disk. In such an optical disk device, when the optical disk is scratched and good data cannot be obtained, that is, dropout may occur.

Since the optical disk device normally performs an error correction process using an error correction code on a read signal, the occurrence of dropout to some extent is allowed. Therefore, after the error correction is performed on the read signal, it is first determined whether the sector can be used. If the error cannot be corrected, the sector is read again (retry), or the sector is not used.

An optical disk device equipped with a circuit for detecting dropout is disclosed in, for example, Japanese Patent Laid-Open No.
The one described in JP-A-2-99962 has been proposed. Here, FIG. 3 is a block diagram of a conventional dropout detection circuit, and FIG. 4 is a diagram showing an input signal read from an optical head and a dropout detection signal. In this device, only the preformatted signal is recorded, and the optical disc in which the data is not yet recorded is reproduced, and the dropout is detected when the obtained signal is out of the range of the predetermined levels a and b. I am supposed to. That is, the dropout detection circuit 140 uses the slicer a14.
1, a slicer b 142 and an OR circuit 143. As shown in FIG. 4, when the signal (input signal) read by the optical head fluctuates within a predetermined range or more, the OR circuit 143 outputs a logical value “1”. The AND circuit 160 outputs the logical product of the signal B generated by the synchronization signal detection circuit 130 and the gate signal generation circuit 150 and the dropout detection signal is obtained.

By counting such dropout detection signals, it is possible to count the dropout amount in a predetermined sector. If the dropout amount exceeds a predetermined value, an error correction code is set. Even if it is used, error correction cannot be performed in the sector, and no data is recorded in the sector.

[0006]

However, the above-mentioned conventional optical disk device has the following problems. (1) After performing the error correction process, it is determined whether or not the error correction of the read sector is possible, so the read time and the write time become long and the throughput decreases.

Further, even the optical disk device provided with the dropout detection circuit has the following problems. (2) Dropout can be detected only on an optical disc on which no data is recorded. That is, it is not possible to detect the case where a dropout occurs subsequently after the data is written, and
It is impossible to restore the originally written data.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical disk device which improves throughput during read processing and write processing and is also suitable for protecting data on an optical disk. ..

[0009]

In order to solve the above problems, the present invention provides a laser diode for generating a laser beam for irradiating an optical disk through an optical head, and laser output control means for controlling the output of the laser diode. ,
The automatic gain control means for controlling the gain of the data of the optical disc read by the optical head, the optical head control means for controlling the optical head, and the level shift of the signal read from the optical disc are out of a predetermined range. In an optical disk device having dropout detection means for detecting as dropout, dropout position detection means for detecting and storing the position of the dropout detected by the dropout detection means, and drop detected by the dropout detection means A dropout counting means for counting the amount of out, and when the amount of dropout counted by the dropout counting means becomes larger than a preset value, the optical head controls the optical head control means. Read the optical disk again, and When reading the stored drop-out position by dropout position detection means, and changing the gain of the laser output and automatic gain control means of the laser output control means.

[0010]

According to the present invention, the optical disk device is constructed as described above, the dropout counting means counts the amount of dropout, and when the amount of dropout becomes larger than the error correction processable quantity, the optical disk is read again. Is read, the time until retry processing is shortened.

Further, when the optical head reads the dropout position again, the laser output control means changes the laser output to a predetermined level, and the automatic gain control means changes the gain of the obtained data output to a predetermined level. To set
Data can be read even at the dropout position, which is usually difficult to read.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an optical disk device according to the present invention. In the figure, 10 is an automatic gain control unit that controls the gain of an input signal RD read by an optical head (not shown), 20 is an equalizer amplifier, 30 is a laser power control unit that controls laser power, 35 is a laser diode, and 40 is a laser diode. Is a dropout detection unit for detecting dropout, 50 is a counter, 60 is a comparator, 70
Is a flip-flop, 80 is a CPU, 90 is a serial memory, and 100 is a data processing device.

The signal RD read from an optical head (not shown) is amplified to a predetermined level by the automatic gain controller 10 and further output through the equalizer amplifier 20. The automatic gain control unit 10 and the equalizer amplifier 20 are CP
The gain or the characteristic can be changed by the control signal R_CONT generated by the U80 and the AND circuit 85, respectively. Similarly, the laser power control unit 3
In the case of 0, the output of the laser diode 35 can be controlled by the control signal R_CONT.

The dropout detection section 40 includes a comparator 4
1, 42, an inverter circuit 43, an AND circuit 44, and resistors R1, R2, R3. The output of the equalizer amplifier 20 is applied to one of the comparators 41 and 42, respectively, and is connected to the comparator 41 by resistors R1, R2, and R3.
In this case, when the output of the equalizer amplifier 20 is smaller than a predetermined level A, and when the output of the comparator 42 is smaller than a predetermined level B (A> B), the logical value is "
1 "is output. The output of the comparator 41 is input to one of the AND circuits 44, and the comparator 42
Is inverted in the inverter circuit 43 and input to the other side of the AND circuit 44.

The counter 50 counts up each time the clock CLK generated in synchronization with the code bit of the optical disk is input when the logical value "0" is input to the inhibit terminal INH. That is, when the output of the dropout detection unit 40 is a logical value “1”, in other words, the counter operates while the optical head is reading the location where the dropout occurs, and the code where the dropout occurs The number of bits will be counted.

The flip-flop 70 is a CPU 80.
A predetermined value is written and held by. The value written in the flip-flop 70 represents the amount of error that can be corrected by the error correction code when one sector of data on the optical disk is read. The amount of such error is 40 bytes if one sector is 512 bytes and 80 bytes if it is 1024 bytes. Therefore, 320 is written as a value in the flip-flop 70 when reading an optical disc in which one sector is 512 bytes, and 640 is read when reading an optical disc in which 1024 bytes are read.

In the comparator 60, the value of the counter 50 is compared with the value held in the flip-flop 70, and when (value of the counter 50 ≧ value of the flip-flop 70), error correction is considered impossible. , Error alarm signal Er
Output r to the CPU 80.

The serial memory 90 is composed of shift registers corresponding to one sector, and input data is sequentially shifted every clock CLK. That is, the logical value "0" is set for the bit in which the dropout has not occurred.
A logical value "1" is recorded for the generated bit.

The output of the equalizer amplifier 20 is also sent to the data processing device 100 to be subjected to error correction processing and the like to form data, which is sent to the host computer.

Next, the operation of the optical disk device of this embodiment will be described. Here, FIG. 2 shows the input signal and the counter 5.
It is a figure explaining the value of 0 and the serial memory 90. When reading a predetermined sector of the optical disc, the retry enable signal R_EN output from the CPU 80 is a logical value "0".
Therefore, the control signal R_CONT which is the output of the AND circuit 85 has the logical value “0”. Therefore, the automatic gain controller 10, the equalizer amplifier 20, and the laser output controller 30 operate normally. If the input signal RD read by the optical head is as shown in FIG. 2, the dropout detection section 40 detects the dropout location. That is, the signal read by the optical head is usually high level above the level A and low level below the level B, so that the dropout occurs when the amplitude level of the signal does not fluctuate between A and B. ..

Therefore, based on the dropout detection signal D_OUT, the data stored in the serial memory 90 and the value of the counter 50 are as shown in FIG.

If the error alarm signal Err is output during reading of a predetermined sector, that is, if the data processing device 100 cannot correct the error of the sector, the CPU 80 reads the sector. When the processing is completed, the retry processing for the sector is performed without waiting for the result of the error correction processing. When performing such retry processing, the CPU 80 sets the optical head control retry signal HRTRY and the retry enable signal R_EN to a logical value "
1 ". The optical head control retry signal HRTRY moves the optical head (not shown) to the head of the sector to be read again.

The serial memory 90 outputs the sequentially stored data to the AND circuit 85 at every clock CLK. Therefore, the AND circuit 85 outputs a logical value “1” when the data output from the serial memory 90 has a logical value “1”, and outputs a control signal to the automatic gain control unit 10, the equalizer amplifier 20, and the laser output control unit 30. R_CONT is applied.

Since the serial memory 90 stores the dropout position in the sector for which the retry process is to be performed, the dropout position is read when the control signal R_CONT has the logical value "1". The laser power of the laser output control unit 30, the gain level in the automatic gain control unit 10, and the characteristics of the equalizer amplifier 20 are switched to the optimum set values so that the dropout point of Data can also be read.

[0025]

As described above, according to the present invention, the following excellent effects can be obtained. (1) Since the counter 50 counts the number of dropouts, it is possible to determine whether or not to perform the retry process before performing the error correction process. Therefore, the time until the optical disc is read again is shortened, and the throughput is reduced. improves.

(2) Since the serial memory detects and stores the dropout position, the laser output control unit when reading the dropout position during the retry process,
Since the outputs of the automatic gain control device and the equalizer amplifier can be changed respectively, the probability that the data can be read at the dropout point becomes high, and as a result, the data on the optical disk can be sufficiently protected.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical disc device according to the present invention.

FIG. 2 shows an input signal, a counter 50, and a serial memory 9.
It is a figure explaining the value of 0.

FIG. 3 is a diagram showing a dropout detection circuit of a conventional optical disc device.

FIG. 4 is a diagram showing an input signal and a dropout detection signal.

[Explanation of symbols]

 10 Automatic Gain Control Section 20 Equalizer Amplifier 30 Laser Power Control Section 35 Laser Diode 40 Dropout Detection Section 50 Counter 60 Comparator 70 Flip-Flop 80 CPU 90 Serial Memory 100 Data Processing Circuit

Claims (1)

[Claims] 1. A laser diode for generating a laser beam for irradiating an optical disc through an optical head, a laser output control means for controlling an output of the laser diode, and a gain of data of the optical disc read by the optical head. In an optical disc device having an automatic gain control unit for controlling and an optical head control unit for controlling the optical head, when a level displacement of a signal read from the optical disc is out of a predetermined range, it is detected as a dropout. Dropout detection means, dropout position detection means for detecting and storing the position of the dropout detected by the dropout detection means, and dropout for counting the amount of dropout detected by the dropout detection means Equipped with counting means When the amount of dropout counted by the dropout counting means becomes larger than a preset value, the optical head reads the optical disc again under the control of the optical head control means, and the dropout position An optical disk device, wherein the laser output of the laser output control means and the gain of the automatic gain control means are changed when the dropout position stored by the detection means is read.