JPH0383235A - Optical disk device - Google Patents

Abstract

PURPOSE:To surely interchange a recording area by interchangeable processing even for information unstable in a writing condition, and to improve reliability by switching the binary level of a reproduction signal at the time of the normal reproduction of information and at the time of detecting a write failure. CONSTITUTION:A switch SW is set to be an off-state by a switching signal from CPU at the time of normal reproducing and it is set to be an on-state at the time of operating read after write action in a binarization circuit 19a. Thus, resistances R1 and R3 are connected in parallel at the time of operating read after write, and the reproduction signal is binarized at a level where a threshold voltage is higher than the time of normal reproduction of information. Consequently, information written in the unstable state can accurately be rewritten in the interchange area by the interchangeable processing and reliability improves at the time of operating the read-after-write action.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an optical disc device having a replacement processing function for rewriting information that has been determined to be a write failure, for example.

(Prior Art) As is well known, optical disc devices have been put into practical use that write (record) or reproduce information by irradiating a light spot onto an information track of an optical disc.

Some optical disk devices of this type include a replacement processing function for rewriting information that has been determined to be a write failure. That is, the information written by the read-after-write operation is reproduced, and information that cannot be reproduced correctly is re-recorded, for example, in another area. Generally, the decision as to whether or not to perform this replacement process is determined based on the information reading rate (error rate) during read-after-write operations.

However, if foreign matter or scratches are present on the recording surface of the optical disc, the laser beam may be blocked or the focus may be temporarily shifted. For this reason, recording bits are insufficiently formed for information recorded in or near areas to which foreign matter or scratches are attached. Therefore, the amplitude of the reproduced signal obtained when reproducing information becomes small. If the amplitude of the reproduced signal is at the very edge of the binarization level, the information may or may not be reproduced depending on the situation. The problem with such unstable written information is that if it happens to be correctly reproduced by a read-after-write operation, replacement processing is not performed even though there is a writing failure.

(Problem to be Solved by the Invention) As described above, in an optical disk device equipped with a conventional replacement processing function, if information in an unstable writing state is accidentally reproduced correctly by a read-after-write operation, , despite the write failure.
There was a drawback that replacement processing was not performed.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical disc device that can reliably replace even information whose written state is unstable through replacement processing, and can further improve the reliability of information.

[Configuration of the Invention (Means for Solving the Problems) In order to achieve the above object, an optical disk device of the present invention is provided with a replacement processing function for rewriting information that has been determined to be a write failure. The structure includes a switching means for switching the binarization level of the reproduced signal during normal information reproduction and when a write failure is detected.

(Function) The present invention allows information written in an unstable state to be detected relatively easily by the above-described means.
This makes it possible to appropriately perform replacement processing even for information that is highly likely to have been written incorrectly.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of an optical disc device of the present invention.

That is, the optical disc 1 is rotated by the motor 2 at, for example, a constant speed. This motor 2 is controlled by a motor control circuit 18.

The optical disc 1 is irradiated with a spot of laser light by an optical head 3, and information is recorded or reproduced by irradiation with this laser light.

The optical head 3 is composed of a movable part and a fixed part. A fixed portion of the optical head 3 is fixed to a drive coil 13 that constitutes a movable portion of a linear motor, and this drive coil 13 is connected to a linear motor control circuit 17.

Moreover, a permanent magnet is arranged at the fixed part of the linear motor. Therefore, when the drive coil 13 is excited by the linear motor control circuit 17, the linear motor is moved in the radial direction of the optical disc 1 (in the horizontal direction in the drawing). Then, as the linear motor moves, the optical head 3 is moved in the radial direction of the optical disc 1.

A linear motor position detector 26 is connected to the linear motor control circuit 17, and by detecting an optical scale 25 provided on the optical head 3, the linear motor position detector 26 detects the optical scale 25 provided on the optical head 3. The position of is now detected.

An objective lens 6 is held in the optical head 3 by a wire suspension (not shown), and the objective lens 6 is movable in the focusing direction (optical axis direction of the lens) by a drive coil 5. The coil 4 allows movement in the tracking direction (direction perpendicular to the optical axis of the lens 6).

On the other hand, the laser beam generated by the semiconductor laser 9 driven by the laser control circuit 14 is transmitted to the collimator lens 1.
The light is irradiated onto the optical disc 1 via the 1a1 half prism 11b and the objective lens 6.

The reflected light from the optical disc 1 is guided to the half prism 11C via the objective lens 6 and the half prism 11b, and one beam separated by the half prism 11c is transmitted via the condenser lens 10 to the position sensor (two pairs of (tracking detector) 8 and is converted into an electrical signal. Further, the other light beams separated by the half prism llc are collected by the condenser lens 11d1 and the knife edge 12.
Through the position sensor (a pair of focus detectors)
7, where it is converted into an electrical signal.

The output signal of the tracking detector 8 is supplied to a tracking control circuit 16 via a differential amplifier OPI. Track difference signal (recording groove (recording track) of optical disc 1) output from this tracking control circuit 16
A signal indicating whether or not the laser beam is located above (for example, a differential signal) is supplied to the linear motor control circuit 17, and is also supplied to the tracking direction drive coil 4 via the driver 27. The position of the objective lens 6 is controlled so that the laser beam follows the recording track on the optical disc 1.

The focus detector 7 outputs a signal related to the focus point of the laser beam, and this signal is supplied to the focusing control circuit 15 via the differential amplifier OP2. The output signal of this focusing control circuit 15 is
The laser beam is supplied to the driving coil 5 in the focusing direction through the driver 28, and thereby the laser beam is directed to the optical disc 1.
The position of the objective lens 6 is controlled so that it is always in just focus at the top.

The laser control circuit 14, the focusing control circuit 15, the tracking control circuit 16, the linear motor control circuit 17, the motor control circuit 18, etc. are connected to a human output control circuit 31, and this input/output control circuit 3
It is controlled by a CPU (central processing unit) 23 via 1.

The CPO 23 is configured to perform predetermined operations according to a program stored in the CPU memory 24.

The input/output control circuit 31 is, for example, analog/digital (
A/D) conversion and digital/analog (D/A) conversion functions, etc., and the laser control circuit 14 described above,
Focusing control circuit 15, tracking control circuit 1
6. In addition to the linear motor control circuit 17 and the motor control circuit 18, the video circuit 19, the timing circuit 33, and the host interface circuit 34 exchange information with the CPU 23.

Further, a pass line 35 is connected to the human output control circuit 31. This pass line 35 has the CPU 2
3. The CPU memory 24, the host interface circuit 34, the data buffer 36, the error correction circuit 37, and the like are connected.

Note that PD is a light receiving element provided near the semiconductor laser 9 to detect the amount of light emitted from the semiconductor laser 9, and the output of this light receiving element PD is supplied to the laser control circuit 14.

Further, a modulation/demodulation circuit 32 is connected to one of the video circuits, and this modulation/demodulation circuit 32 is connected to the laser control circuit 1.
4 and the above-mentioned timing circuit 33 are connected, and the above-mentioned data buffer 36 is connected to this timing circuit 33, and this data buffer 36 is controlled by the above-mentioned CPU 23.

As mentioned above, when focusing servo and tracking servo are performed, the sum signal of the output from the tracking detector 8 reflects the unevenness of recording bits formed on the recording track of the optical disc 1. There is. Therefore, this sum signal is used as an information reproduction signal and is supplied to the video circuit 19, where it is binarized.

The binarized signal binarized in this one video circuit is sent to the modulation/demodulation circuit 32, where it is demodulated.

Then, it becomes reproduction information and is stored in the data buffer 36.

The playback information stored in the data buffer 36 is transferred to an external host computer (not shown) via the host interface circuit 34. In this way, a normal playback operation is performed.

Next, a procedure for recording information in the above configuration will be described.

For example, suppose that information to be recorded is input from the host computer. Then, the information is stored in the data buffer 36 via the host interface circuit 34 under the control of the CPU 23.

The CPU 23 also controls the laser control circuit 14, linear motor control circuit 17, motor control circuit 18, etc.
It will be ill. The linear motor control circuit 1
7 is controlled based on the control signal from the CPO 23 and the position signal from the linear motor position detector 26, and the address information on the optical disc 1 is read, so that, for example, the optical head 3 is able to record information. Corresponds to the target recording track. Further, the focus servo is turned on so that the light from the semiconductor laser 9 that is focused by the objective lens 6 is just in focus with respect to the recording track, and the focus servo is turned on so that the laser light follows the recording track. Tracking servo is turned on.

In this state, the error correction circuit 37 adds an error correction code or the like to the information stored in the data buffer 36. The information to which the error correction code and the like are added is modulated by the modulation/demodulation circuit 32 and then supplied to the laser control circuit 14 as a pulse signal. As a result, the semiconductor laser 9 is pulse-lit, thereby forming irregularities corresponding to information called recording bits on the recording track.

When writing of information is completed in this manner, a read◆after-write operation is performed. That is, the laser control glJ circuit 14 is controlled so that the recording track on which the above information has been written is irradiated with laser light necessary for reproduction. Then, the sum signal of the output from the tracking detector 8 obtained by irradiating the recording track with the laser beam, that is, the reproduction signal, is binarized by one video circuit.

In this case, the switching signal supplied from the CPU 23 via the input/output control circuit 31 causes the binarization level of the reproduced signal to be set to a threshold voltage higher than the binarized level of the reproduced signal used during normal information reproduction. can be changed to something.

Thereafter, it is checked whether the information has been written correctly or not based on the information reproduced by the above-mentioned read◆after-write operation. If the information that was supposed to have been written could not be reproduced correctly or if there were a large number of errors, the optical disc
For example, information is re-recorded in a replacement area provided separately from the information recording area in the same manner as described above. This replacement process guarantees the recorded information.

FIG. 2 shows the configuration of a binarization circuit provided within the video circuit 19.

This binarization circuit 19a is operated by the CPU during normal information reproduction.
The analog switch SW is opened by a switching signal from 23, and closed during read-after-write operation.

That is, when the analog switch SW is opened,
A voltage generated by the resistors R2 and R2 is supplied to one input terminal of the comparator CC. In addition, analog switch S
When W is closed, the resistor R1 is connected in parallel to the resistor R, and a voltage corresponding to the combined resistance of the resistors R8, R2, and R1 is supplied to one side input terminal of the comparator CC. .

In this case, for example, the resistors R, , R2 are each 10Ω,
If the resistor R1 is 1Ω, the comparison voltage for binarization during normal information reproduction is 6V, and the comparison voltage for binarization during read-after-write operation is approximately 6.2V.
It becomes 8V.

In this manner, during read-after-write operations, the reproduced signal is binarized at a higher threshold voltage level than during normal information reproduction.

FIG. 3 shows a comparison of the binarization processing of the reproduced signal during normal information reproduction and during read-after-write operation.

In this case, the binary level A of the reproduced signal a during the read-after-write operation is such that the reproduced signal a corresponding to the recording bit C correctly formed in the recording track b is binary-coded, and the reproduction signal a corresponding to the recording bit C correctly formed in the recording track b is binary-coded. The reproduced signal a for a portion of the recorded bit d for which pit formation is insufficient due to adhesion or scratches is set at a threshold voltage that is not binarized. Therefore, when the reproduced signal a is binarized at the binarization level A during the read-after-write operation, information written in an unstable state can be easily detected. Therefore, information whose writing is unstable can be appropriately replaced by replacement processing, and the reliability of the information is more reliably guaranteed.

On the other hand, the binarization level B of the reproduced signal a during normal information reproduction is set to a threshold voltage that allows the reproduction signal a to be binarized even if the amplitude of the reproduced signal a is somewhat medium.

This improves information reproduction performance.

As described above, the binarization level used when reproducing information written in an unstable state is switched to be more severe than the binarization level used when normally reproducing information.

That is, during read-after-write operations, the reproduced signal is binarized at a binarization level with a higher threshold voltage than the binarization level used during normal information reproduction. This makes it possible to relatively easily and reliably detect information in an unstable writing state. Therefore, replacement processing can be appropriately performed on information that has not been written correctly. Therefore, a situation in which information cannot be reproduced later does not occur, and reliability can be improved.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the invention.

[Effects of the Invention] As detailed above, according to the present invention, even information in an unstable writing state can be reliably replaced by replacement processing, and the reliability of information can be further improved. equipment can be provided.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a block diagram showing an optical disc device, FIG. 2 is a block diagram showing the configuration of a binarization circuit, and FIG. 3 is a block diagram for explaining the operation. FIG. DESCRIPTION OF SYMBOLS 1... Optical disk, 3... Optical head, 8... Position sensor, 19... Video circuit, 19a... Binarization circuit, 23... CPU, SW... Analog switch, CC ...Comparator, R+, R2, Ri...Resistance.

Claims (2)

[Claims] (1) In an optical disk device equipped with a replacement processing function for rewriting information that has been determined to be a write failure, a switching means is provided to switch the binary level of the reproduced signal between normal information reproduction and when a write failure is detected. An optical disc device characterized by: (2) The binarization level of the reproduced signal used when detecting the writing failure is characterized by stricter criteria for binarization than the binarization level of the reproduced signal used during normal information reproduction. The optical disc device according to claim (1).