JP2788297B2 - Optical disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an optical disc apparatus having an alternate processing function of rewriting information that has been determined to be defective, for example.

(Prior Art) As is well known, information is written (recorded) by irradiating a laser beam with a spot on an information track of an optical disk.
Alternatively, an optical disk device for performing reproduction has been put to practical use.

Some optical disk devices of this type have a replacement processing function for rewriting information that has been determined to be defective.
That is, information written by a read-after-write operation accompanying the end of recording of information is reproduced, and information that cannot be reproduced correctly is re-recorded in another area, for example. In general, whether or not to perform this replacement processing is determined by the read rate (error rate) of information read by the read-after-write operation.

However, when a foreign substance is attached to the recording surface of the optical disc, or when there is a flaw, the laser light is blocked or the focus is temporarily shaken. For this reason,
Information recorded at or near a portion to which a foreign substance is attached, a portion with a flaw, or the like has insufficient formation of recording pits. Therefore, the amplitude of the reproduced signal obtained at the time of reproducing the information is reduced. If the amplitude of the reproduced signal is almost at the level of the binarization level, the information may or may not be reproduced depending on the case. Such information in the unstable state of writing can be correctly reproduced by a read-after-write operation, even if it is a writing failure,
There is a disadvantage that the replacement process is not performed.

(Problems to be Solved by the Invention) As described above, in the conventional optical disk device having the replacement processing function, when information in an unstable writing state happens to be correctly reproduced by a read-after-write operation. However, there is a disadvantage that the replacement process is not performed despite the writing failure.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly reliable optical disk device capable of reliably exchanging information whose writing state is unstable by a replacement process.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned object, an optical disc apparatus according to the present invention provides a recording track of an optical disc by irradiating a spot light to write or reproduce information. Reading means for reading out the information written on the recording track at the end of writing, and a write failure of the information based on an envelope signal of a reproduction signal obtained at the time of reading out the information by the reading means. First detecting means for detecting an error, a second detecting means for detecting an abnormal writing when the information read by the reading means does not match the written information, and a first detecting means Rewriting means for rewriting the information when a writing error is detected by the means or when a writing error is detected by the second detecting means.

(Operation) In the present invention, the detection of a writing abnormality by a coincidence check by reading the written information and the detection of a defect based on a reproduction signal at the time of reading are performed in parallel, and at least one of the detections is performed. , A replacement process is performed.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of an optical disk device according to the present invention.

That is, the optical disk 1 is driven to rotate by the motor 2 at a constant speed, for example. The motor 2 is controlled by a motor control circuit 18.

The optical disk 1 is irradiated with a laser beam by the optical head 3 to record or reproduce information by the laser beam irradiation.

The optical head 3 includes a movable part and a fixed part. The fixed part of the optical head 3 is fixed to a drive coil 13 constituting a linear motor movable part, and the drive coil 13 is connected to a linear motor control circuit 17.

Further, a permanent magnet (not shown) is disposed on the fixed portion of the linear motor. Therefore, when the drive coil 13 is excited by the linear motor control circuit 17, the linear motor moves in the radial direction of the optical disc 1 (the left and right direction in the drawing). Then, the optical head 3 is moved in the radial direction of the optical disk 1 with the movement of the linear motor.

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

An objective lens 6 is held on the optical head 3 by a wire suspension or the like (not shown). The objective lens 6 is movable in a focusing direction (optical axis direction of the lens) by a drive coil 5 and is driven. The coil 4 can move in a tracking direction (a direction orthogonal to the optical axis of the lens 6).

On the other hand, the laser light generated by the semiconductor laser 9 driven by the laser control circuit 14
The light is radiated onto the optical disc 1 via the half prism 11b and the objective lens 6. The reflected light from the optical disk 1 is guided to the half prism 11c via the objective lens 6 and the half prism 11b, and one light beam split by the half prism 11c is transmitted to the position sensor (a pair of An image is formed on the tracking detector 8 and converted into an electric signal. Further, the half prism 11c
The other light beam split by the light source forms an image on a position sensor (a pair of focus detectors) 7 via a condenser lens 11d and a knife edge 12, and is converted into an electric signal.

The output signal of the tracking detector 8 is supplied to a tracking control circuit 16 via an operational amplifier OP1. A track difference signal (a signal indicating whether or not a laser beam is positioned on a recording track of the optical disc 1, for example, an operation signal) output from the tracking control circuit 16 is
While being supplied to the linear motor control circuit 17, the drive coil 4 in the tracking direction is
The position of the objective lens 6 is controlled so that the laser light follows the recording track on the optical disc 1.

The focusing detector 7 outputs a signal relating to the focus point of the laser beam, and this signal is supplied to the focusing control circuit 15 via the operational amplifier OP2. The output signal of the focusing control circuit 15 is supplied to the driving coil 5 in the focusing direction via a driver 28.
, Whereby the position of the objective lens 6 is controlled so that the laser light is always just focused on the optical disc 1.

The laser control circuit 14, the focusing control circuit
15, the tracking control circuit 16, the linear motor control circuit 17, and the motor control circuit 18 are connected to an upper output control circuit 31, and the CP is controlled via the input / output control circuit 31.
It is controlled by a U (central processing unit) 23.

The input / output control circuit 31 has, for example, an analog / digital (A / D) conversion function and a digital / analog (D / A) conversion function, and has the above-described laser control circuit 14, focusing control circuit 15, tracking control circuit 16, linear motor control circuit 17, motor control circuit 18, timing circuit 33, host interface circuit 34 and the CP
It exchanges information with U23.

A bus line 35 is connected to the input / output control circuit 31. The bus line 35 includes the CPU 23 and the C
The PU memory 24, the host interface circuit 34, the data buffer 36, the error correction circuit 37, and the like are connected.

The data buffer 36 temporarily stores information to be recorded on the optical disk 1 or information read from the optical disk 1. The information storage address and the timing of reading and writing are controlled by the CPU 23 and the timing circuit 3.
3 and is controlled by.

The CPU 23 performs a predetermined operation according to a program stored in the CPU memory 24.

As described above, in the state where the focusing servo and the tracking servo are performed, the sum signal of the output from the tracking detector 8 reflects the unevenness of the recording pit formed on the recording track of the optical disc 1. . Therefore, the sum signal is used as a reproduction signal of information and supplied to the video circuit 19, and the video circuit 19
It is binarized at 19.

The binarized signal (video signal) binarized in the video circuit 19 is sent to the modulation / demodulation circuit 32 and demodulated under the control of the timing circuit 33. Then, it becomes playback information and is stored in the data buffer 36.

The reproduction 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 reproduction operation is performed.

On the other hand, when information is recorded on the optical disk 1, the modulation / demodulation circuit 32 modulates the information to which an error correction code or the like is added, converts the modulated information into a pulse signal, and converts the information into a pulse signal.
Supplied to 14. Then, when the semiconductor laser 9 is pulse-lit by the laser control circuit 14, recording pits are formed on recording tracks of the optical disc 1 according to the information.

Note that PD is a light receiving element provided near the semiconductor laser 9 for detecting the light emission amount of the semiconductor laser 9, and the output of the light receiving element PD is supplied to the laser control circuit 14.

Reference numeral 30 denotes a recording abnormality detection circuit. The recording abnormality detection circuit 30 performs the video circuit operation at the time of a read-after-write operation, that is, when reading out the written information at the end of the recording of the information. The CPU 23 interrupts the CPU 23 by detecting a change in an envelope signal of the reproduction signal supplied to the CPU 19. This recording abnormality detection circuit 30
It is reset by a reset signal from the CPU 23 supplied through the input / output control circuit 31.

FIG. 2 shows the configuration of the recording abnormality detection circuit 30.

The recording abnormality detection circuit 30 includes a reference voltage generation unit 30 that generates a reference voltage corresponding to an allowable limit of the fluctuation of the envelope signal.
a, a comparator 30b for comparing the reference voltage from the reference voltage generator 30a with the envelope signal of the reproduction signal from the video circuit 19, a flip-flop that latches a change in the output of the comparator 30b and interrupts the CPU 23 Loop 3
0c and the like.

That is, the envelope signal is taken in from the positive input terminal of the comparator 30b and compared with the reference voltage from the reference voltage generator 30a supplied to the negative input terminal. In this case, as shown in FIG. 3 (a), for example, when the laser beam is blocked by a foreign matter, a scratch, or the like, the focus is temporarily fluctuated, resulting in insufficient formation of the recording pit. , That portion has a small amplitude. Therefore, as shown in FIG. 3 (b), the envelope signal is changed in accordance with the change in the amplitude of the reproduction signal. With respect to this envelope signal, a high-level signal as shown in FIG. 3 (c) is output from the comparator 30b corresponding to the portion where the fluctuation exceeds the reference voltage shown by the broken line in the figure. Then, the high-level signal from the comparator 30b is latched by the flip-flop circuit 30c, so that a recording abnormality detection signal as shown in FIG. 3D is supplied to the interrupt terminal of the CPU 23. .

As described above, when a fluctuation exceeding the allowable limit of the envelope signal is detected during the read-after-write operation, that is, when it is detected that the recording pit is not correctly formed in the recording track, the CPU 23 is interrupted. It has become.

Next, an operation of recording information in the above configuration will be described.

For example, it is assumed 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.

Further, the CPU 23 controls the laser control circuit 14, the linear motor control circuit 17, the motor control circuit 18, and the like. Then, the linear motor control circuit 17 is controlled based on a control signal from the CPU 23 and a position signal from the linear motor position detector 26, and further reads address information on the optical disk 1, thereby providing, for example, an optical head. Reference numeral 3 corresponds to a target recording track on which information is to be recorded. Further, the focus servo is turned on so that the light from the semiconductor laser 9 condensed by the objective lens 6 is focused on the recording track, and the laser light follows the recording track. The 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 or the like is 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, when the semiconductor laser 9 is pulse-lit, irregularities corresponding to information called recording pits are formed on the recording track.

When the writing of the information is completed in this way, a read-after-write operation is performed. That is, the laser control circuit 14 is controlled so that the recording track on which the information is written is irradiated with a laser beam necessary for reproduction. Then, a video signal 19 binarizes a sum signal of the output from the tracking detector 8 obtained by irradiating the recording track with the laser beam, that is, a reproduction signal.

In parallel with the operation of reproducing this information,
The recording abnormality detection circuit 30 detects whether or not a recording abnormality has occurred during the after-write operation. When the recording abnormality detection circuit 30 interrupts the CPU 23, that is, when an abnormal fluctuation of the saturation line signal is detected, the optical disk 1 is placed in a spare area provided separately from the information recording area, for example. The information is rewritten in the same manner as the operation described above. Since the information is guaranteed by this replacement process, it is possible to prevent a state in which the information cannot be reproduced later.

Thereafter, for example, if no abnormal fluctuation of the envelope signal is detected, the information reproduced by the read-after-write operation is checked. As a result of this check, if the information that should have been written could not be reproduced correctly or if the number of errors is large, the above-described replacement processing is performed. As a result, it is possible to replace information that has become defective in writing due to factors other than focus shift, and to obtain higher reliability.

As described above, the reproduction signal during the read-after-write operation is detected by detecting the fluctuation of the envelope signal and adding this to the condition of whether or not to perform the replacement processing.

That is, the information that the formation of the recording pits is insufficient due to the focus shake during the recording is detected by checking the saturation signal of the reproduction signal obtained at the time of the read-after-write operation. As a result, information in an unstable writing state can be relatively easily obtained.
And it can be detected reliably. Therefore, an optical disk device with higher reliability can be realized by using the detection result as a condition for performing the replacement process.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.

[Effects of the Invention] As described above in detail, according to the present invention, it is possible to provide a highly reliable optical disk device capable of reliably exchanging information whose writing state is unstable by an exchange process.

[Brief description of the drawings]

1 shows an embodiment of the present invention, FIG. 1 is a block diagram showing an optical disk device, FIG. 2 is a block diagram showing a configuration of a recording abnormality detection circuit, and FIG. 3 is an operation of the recording abnormality detection circuit. It is a figure shown in order to explain. DESCRIPTION OF SYMBOLS 1 ... Optical disk, 3 ... Optical head, 7,8 ... Position sensor, 19 ... Video circuit, 23 ... CPU, 30 ... Recording abnormality detection circuit, 30a ... Reference voltage generator, 30b ... Comparator , 30c …… Flip-flop circuit.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 20/18 572 G11B 20/18 572F

Claims (1)

(57) [Claims] 1. An optical disk device for writing or reproducing information by irradiating a spot light on a recording track of an optical disk, wherein reading means for reading out the information written on the recording track upon completion of the writing. And a first detecting means for detecting a writing failure of the information from an envelope signal of a reproduction signal obtained when the information is read by the reading means.
Detecting means for detecting a writing error when the information read by the reading means does not match the written information; and detecting a writing failure by the first detecting means. An optical disc device, comprising: a rewriting means for rewriting the information when the detection is detected or when a writing error is detected by the second detection means.