JP2003162834A - Optical disc drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device that can improve tracking and focusing of an optical disc drive against defects by correcting errors in servo signals based on the tracking or focusing errors caused by the defects. <P>SOLUTION: The optical disc drive of this invention has a signal processing means that finds defects based on the optical signals received from a disc and makes calculation for the tracking or focusing servo signals when there are any defects or no defect. When there are defects, it sample-and-holds the low frequency components of the servo signals right before the defects are found, and adds eccentricity correction signals or surface wobble correction signals. It also adds reverse polarity signals and brake signals to the above sum signals right after the defects are found. <P>COPYRIGHT: (C)2003,JPO

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 recording, reproducing and erasing information using an optical disk as a medium, and more particularly to a means for detecting a defect on the basis of a light receiving signal from the disk, and an effect of the defect. The present invention relates to an optical disc device having a control system for correcting each feedback control signal based on an erroneous tracking or focus error signal.

[0002]

2. Description of the Related Art In an optical disk device for recording, reproducing and erasing information using an optical disk as a medium, an error signal is detected based on a light receiving signal from the disk and a feedback control signal is generated to control a tracking and focus actuator. . Therefore, when the light spot passes through the defect, the received light signal becomes unbalanced due to the influence of the defect, and an erroneous tracking or focus error signal is generated. Since the track or focus actuator is driven based on this error signal generated by mistake, the light spot moves from the servo tracking position while passing the defect, and the track or focus tracking performance deteriorates significantly after passing the defect. There was a problem of doing (Fig. 1). Here, the deterioration of the track or focus following performance is related to the deterioration of the recording, reproducing and erasing performance of the optical disc device.

As a means for improving this problem, a method has been reported in which the defect is detected by the defect detecting means and the gain of the tracking or focus servo is lowered at the time of detecting the defect to prevent the deterioration of the track or focus tracking performance. ing. An example of this is JP-A-9-326120.

[0004]

However, the conventional countermeasures against defects are effective during the defect detection period, and in the optical disc device for detecting the defect based on the threshold level for the light receiving signal from the disc, the defect countermeasure is performed. It is not possible to correct an erroneous track or focus tracking operation that occurs due to the detection delay.

Therefore, an object of the present invention is to provide a control system for correcting an erroneous track or focus follow-up operation caused by a defect detection delay in an optical disk device which detects a defect based on a threshold level for a light receiving signal from the disk. In this way, it is possible to provide an optical disk device with improved track or focus tracking performance against defects.

[0006]

An optical disk device of the present invention detects a defect based on a threshold level for a light receiving signal from a disk, and calculates a tracking or focus feedback control signal when a defect is detected and when no defect is detected. It is characterized by comprising signal processing means for performing processing.

Here, the signal processing means holds the low frequency component of each feedback control signal immediately before the defect detection at the time of the defect detection, thereby suppressing the movement of the light spot from the servo following position while passing the defect. can do. Further, by adding the signal holding the low frequency component of each feedback control signal immediately before the defect detection and the eccentricity correction signal or the surface shake correction signal to the optical disk device having the large eccentricity or the surface shake component, the track can be tracked. Alternatively, the focus following performance can be improved. Further, immediately after the defect is detected, the signal is added to the signal obtained by adding the eccentricity correction signal or the surface shake correction signal to the signal that holds the low frequency component of each feedback control signal immediately before the defect detection, and the signal is held by the arithmetic unit in the signal processing means. By adding the reverse polarity signal and the brake signal at a predetermined output time, the acceleration applied to the objective lens due to the defect detection delay can be canceled, and the position of the light spot moved due to the defect detection delay can be determined. It is possible to return to the servo follow-up position before the defect.

Therefore, according to the present invention, a disk motor for rotating an optical disk, a rotation frequency generating means for outputting a signal corresponding to a rotation angle of the disk motor, and an objective lens for converging a laser beam on the disk are provided. A photodetector that generates a light reception signal from the disc, and first and second threshold levels can be set for the light reception signal,
A defect detection unit that detects a defect by the first threshold level and ends the defect detection period based on the second threshold level; a tracking actuator that drives the objective lens in the tracking direction; and a tracking error signal detection unit. A tracking drive signal generating means for generating a tracking feedback control signal, a tracking actuator driver, a focus actuator for driving the objective lens in the focus direction, a focus error signal detecting means, and a focus drive signal generation for generating a focus feedback control signal. And a focus actuator driver.

The first and second defect detecting means are also provided.
Based on the threshold level of, at the time other than the defect detection and the defect detection, the tracking signal processing means for performing the arithmetic processing on the tracking feedback control signal generated by the tracking drive signal generating means, the tracking signal processing means, It has a tracking signal calculator, an eccentricity correction signal generating means, and a tracking signal adding means.

The tracking defect processing means is
On the basis of the first and second threshold levels of the defect detection means, at the time of defect detection, a tracking hold signal which holds the low frequency component of the tracking feedback control signal immediately before the defect detection is generated and output. On the other hand, except when a defect is detected,
Outputs the tracking feedback control signal.

The tracking signal calculator can adjust the polarity and the gain of the tracking feedback control signal up to a predetermined time before, and immediately after the defect is detected, the amplitude is doubled with the polarity opposite to the tracking feedback control signal up to the predetermined time before. A tracking brake signal that corrects the transient response of the tracking actuator after adding the tracking reverse polarity signal and the tracking reverse polarity signal corresponding to the signal is generated and output at a predetermined output time.

The eccentricity correction signal generating means cancels the eccentricity component of the disk or the optical disk device for each rotation angle of the disk motor based on the tracking feedback control signal and the output of the rotation frequency generating means. To calculate.

The tracking signal adding means includes first and second tracking signal adding means.
At the time of the defect detection, the tracking hold signal and the eccentricity correction signal are added on the basis of the threshold level of, and the tracking reverse polarity signal and the tracking brake signal are added to the addition signal immediately after the defect detection. On the other hand, except when a defect is detected,
It operates to add the tracking feedback control signal and the eccentricity correction signal.

Further, the first and second defect detecting means are provided.
Based on the threshold level of, except the time of the defect detection and the defect detection, the focus signal processing means for performing the arithmetic processing on the focus feedback control signal generated by the focus drive signal generation means, the focus signal processing means, It has a focus defect processing means, a focus signal calculator, a surface shake correction signal generating means, and a focus signal adding means.

The focus defect processing means, on the basis of the first and second threshold levels of the defect detecting means, generates a focus hold signal in which a low frequency component of the focus feedback control signal immediately before the defect detection is held at the time of the defect detection. And output. On the other hand, the focus feedback control signal is output except when the defect is detected.

The focus signal calculator can adjust the polarity and gain of the focus feedback control signal up to a predetermined time before, and immediately after the defect detection, the polarity is opposite to that of the focus feedback control signal up to a predetermined time before and the amplitude is doubled. The focus brake signal that corrects the transient response of the focus actuator after adding the focus reverse polarity signal, which is a signal corresponding to, and the focus reverse polarity signal is generated and output at a predetermined output time.

The surface shake correction signal generation means is based on the focus feedback control signal and the output of the rotation frequency generation means, and a surface shake correction signal for canceling the surface shake component of the disk or the optical disk device for each rotation angle of the disk motor. To calculate.

The focus signal adding means adds the focus hold signal and the surface shake correction signal at the time of defect detection based on the first and second threshold levels of the defect detection means, and immediately after the defect detection, It operates so as to add the focus reverse polarity signal and the focus brake signal. On the other hand, except when the defect is detected, the focus feedback control signal and the surface shake correction signal are added together.

By the above operation, it is possible to improve the track or focus following performance at the time of defect detection and at the time of other than defect detection.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows a configuration of an optical disk device of the present invention.

Each block and operation will be specifically described with reference to FIGS. 2 and 3.

The optical disk device records, reproduces, and erases information on the optical disk 1. The disc motor 2 rotates the disc 1 at a predetermined speed. Disk 1
The rotation frequency generating means 3 generates a signal corresponding to the rotation angle of the disk motor 2 in accordance with the rotation of No. 1, and sends it to the eccentricity correction signal generating means 14 and the surface shake correction signal generating means 23. The objective lens 4 condenses the laser light applied to the recording surface of the disc 1. The photodetector 5 generates a light reception signal based on the reflected light from the disc 1. The defect detection means 6 sets the first and second threshold levels in the light reception signal output from the photodetector 5 (S1 and S2 in FIG. 3).
Then, the defect is detected by the first threshold level, and the defect detection period is ended based on the second threshold level. Further, the defect detection means 6 outputs a threshold level signal (A1 in FIG. 2) to the tracking signal processing means 11 based on the first threshold level or the second threshold level.
Alternatively, it is sent to the focus signal processing means 20.

The tracking actuator 7 drives the objective lens 4 in the radial direction of the disk 1 to position the focused focal point on the track on the disk. The tracking error signal detecting means 8 generates a tracking error signal including the track following error information of the objective lens 4 and the disk 1 based on the light receiving signal output from the photodetector 5, and the tracking error signal is generated. Send to. The tracking drive signal generation means 9 sends to the tracking signal processing means 11 a tracking feedback control signal such that the objective lens 4 follows the track of the disk 1 based on the sent tracking error signal. The tracking actuator driver 10 is the tracking signal processing means 1
The tracking actuator 7 is driven on the basis of the signal sent from 1.

Further, the focus actuator 16 drives the objective lens 4 in the direction perpendicular to the disc 1 to position the focused focal point at the focal point of the recording surface of the disc 1. The focus error signal detection means 17 generates a focus error signal including focusing error information of the objective lens 4 and the disc 1 based on the light receiving signal output from the photodetector 5,
This is sent to the focus drive signal generation means 18. The focus drive signal generation means 18 sends a focus feedback control signal to the focus signal processing means 20 based on the sent focus error signal so that the objective lens 4 maintains the focal length with the disc 1. The focus actuator driver 19 drives the focus actuator 16 based on the signal sent from the focus signal processing means 20.

The tracking signal processing means 11 has a tracking defect processing means 12, a tracking signal calculator 13, an eccentricity correction signal generating means 14 and a tracking signal adding means 15.

Defect processing means 12 for tracking
Generates a tracking hold signal when a defect is detected based on the first threshold level and outputs the tracking hold signal. At this time, if the received light signal exceeds the second threshold level, the tracking feedback control signal is output. Is output. On the other hand, the tracking feedback control signal is output except when the defect is detected.

The tracking signal calculator 13 generates a tracking reverse polarity signal and a tracking brake signal immediately after the defect is detected and outputs them at a predetermined output time.

The eccentricity correction signal generating means 14 calculates an eccentricity correction signal based on the signal sent from the rotation frequency generating means 3 and the tracking feedback control signal.

The tracking signal adding means 15 is a tracking defect processing means 12 when a defect is detected.
The tracking hold signal output from the eccentricity correction signal and the eccentricity correction signal sent from the eccentricity correction signal generation means 14 are added. Immediately after the defect detection, the tracking reverse polarity signal ((b) in FIG. 3) and the tracking brake signal ((c) in FIG. 3) output from the tracking signal calculator 13 are added to the addition signal ((d) in FIG. 3). to add. At this time, if the received light signal exceeds the second threshold level,
The tracking signal adding means 15 adds the tracking feedback control signal and the eccentricity correction signal sent from the eccentricity correction signal generating means 14. On the other hand, except when the defect is detected, the tracking feedback control signal and the eccentricity correction signal sent from the eccentricity correction signal generating means 14 are added.

The focus signal processing means 20 has a focus defect processing means 21, a focus signal calculator 22, a surface shake correction signal generating means 23, and a focus signal adding means 24.

Defect processing means 21 for focus
When a defect is detected based on the first threshold level, the focus hold signal is generated and output at the time of the defect detection.
When it exceeds the threshold level of, the focus feedback control signal is output. On the other hand, the focus feedback control signal is output except when the defect is detected.

The focus signal calculator 22 generates a focus reverse polarity signal and a focus brake signal immediately after detecting a defect and outputs them at a predetermined output time.

The surface shake correction signal generating means 23 calculates the surface shake correction signal based on the signal sent from the rotation frequency generating means 3 and the focus feedback control signal.

The focus signal adding means 24 adds the focus hold signal output from the focus defect processing means 21 and the surface shake correction signal sent from the surface shake correction signal generating means 23 when a defect is detected. Immediately after the defect detection, the focus reverse polarity signal ((b) in FIG. 3) and the focus brake signal ((c) in FIG. 3) output from the focus signal calculator 22 are added to the addition signal ((d) in FIG. 3). to add. At this time, if the received light signal exceeds the second threshold level, the focus signal addition means 24 outputs the focus feedback control signal and the surface shake correction signal sent from the surface shake correction signal generation means 23 except when the defect is detected. to add. On the other hand, except when the defect is detected, the focus feedback control signal and the surface shake correction signal sent from the surface shake correction signal generating means 23 are added.

[0035]

As described above, according to the present invention, in the optical disk device for detecting the defect based on the threshold level for the received light signal from the disk,
When a defect is detected, the signal that holds the low-frequency component of the tracking or focus feedback control signal immediately before the defect detection is added to the eccentricity correction signal or the surface shake correction signal. Immediately after the defect detection, the reverse polarity signal and its brake are added to this added signal. By generating and adding signals, it is possible to cancel the acceleration applied to the objective lens due to the defect detection delay, and
Since the position of the light spot moved due to the delay in the defect detection can be returned to the servo follow-up position before the defect, the track or focus follow-up performance with respect to the defect can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a light receiving signal and a servo signal at the time of a conventional defect.

FIG. 2 is a block diagram of the present invention.

FIG. 3 is a diagram illustrating a correction process at the time of a defect according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Disk motor, 3 ... Rotation frequency generating means, 4 ... Objective lens, 5 ... Photodetector, 6 ... Defect detecting means, 7 ... Tracking actuator, 8
... tracking error signal detection means, 9 ... tracking drive signal generation means, 10 ... tracking actuator driver, 11 ... tracking signal processing means, 12 ... tracking defect processing means, 13 ... tracking signal calculator, 14 ... eccentricity correction signal generation Means, 15 ... Tracking signal adding means, 16 ... Focus actuator, 17 ... Focus error signal detecting means, 18 ... Focus drive signal generating means, 19 ... Focus actuator driver, 20 ... Focus signal processing means, 21 ... Focus defect processing means , 22 ... Focus signal calculator, 23 ... Surface shake correction signal generating means, 24 ... Focus signal adding means, (A1) ... Threshold level signal.

Continued front page    (72) Inventor Motoyuki Suzuki             292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa             Ceremony Hitachi Digital Media Development Book             Department (72) Inventor Imagawa             292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa             Ceremony Hitachi Digital Media Development Book             Department F term (reference) 5D118 AA17 AA19 AA28 BA01 CA07                       CA11 CA13 CB02 CD02 CD03                       CD09 CD12 CD13

Claims (4)

[Claims] 1. An optical disk device for recording, reproducing, and erasing information using an optical disk as a medium, a disk motor for rotating the disk, and a rotation frequency generating means for outputting a signal corresponding to a rotation angle of the disk motor. An objective lens for focusing laser light on the recording surface of the disc; a photodetector for generating a light reception signal based on the reflected light from the disc of the laser light focused by the objective lens; Defect detection means for setting a threshold level for a light reception signal output from a detector, and detecting dirt and scratches (hereinafter referred to as a defect) on the disk surface based on a predetermined threshold level; and the objective. A tracking actuator that drives a lens in the radial direction of the disk (hereinafter referred to as the tracking direction). A tracking error signal detecting means for detecting a tracking error signal, which is an error in the tracking direction between the track following position and the predetermined position in the objective lens, based on a light receiving signal output from the photodetector; Tracking drive signal generating means for generating a tracking feedback control signal for the objective lens to follow a track on the disk based on the output of the error signal detecting means; a tracking actuator driver for driving the tracking actuator; Based on the threshold level of the defect detection means, arithmetic processing is performed on the tracking feedback control signal generated by the tracking drive signal generation means other than at the time of defect detection and at the time of defect detection. And a tracking signal processing means for performing a tracking hold signal which holds a low frequency component of the tracking feedback control signal immediately before the defect at the time of the defect detection, based on the threshold level of the defect detection means. On the other hand, the tracking defect processing means for outputting the tracking feedback control signal and the polarity and the gain of the tracking feedback control signal up to a predetermined time before the defect detection can be adjusted except when the defect is detected. A signal whose polarity is opposite to that of the tracking feedback control signal up to the time before and which corresponds to double the amplitude (hereinafter referred to as a tracking reverse polarity signal) and the tracking reverse polarity signal after addition of the track A tracking brake signal for correcting the transient response of the tracking actuator, and a tracking signal calculator for setting and outputting the output time of the tracking reverse polarity signal and the tracking brake signal under a predetermined condition, and the tracking feedback control A signal for canceling the eccentricity component of the disk or the optical disk device for each rotation angle of the disk motor based on the signal and the output of the rotation frequency generating means (hereinafter referred to as an eccentricity correction signal). ) Eccentricity correction signal generating means, based on the threshold level of the defect detection means, at the time of the defect detection by adding the tracking hold signal and the eccentricity correction signal, immediately after the defect detection to the addition signal, It operates so as to add the tracking reverse polarity signal and the tracking brake signal in a predetermined output time, while the tracking feedback control signal generated by the tracking drive signal generating means and the bias are generated except when a defect is detected. An optical disk device, comprising: a tracking signal adding unit that operates to add the eccentricity correction signal generated by the core correction signal generation unit. 2. The defect detecting means is capable of setting first and second threshold levels for a light receiving signal output from the photodetector, and detects a defect based on the first threshold level. Then, the defect detection period is ended based on the second threshold level, and the tracking signal processing unit is configured to perform the defect detection and the defect detection based on the first and second threshold levels of the defect detection unit except at the time of the defect detection and the defect detection. Calculating processing for the tracking feedback control signal generated by the tracking drive signal generating means, and the tracking defect processing means detects the defect based on the first and second threshold levels of the defect detecting means. Sometimes a defect The tracking hold signal that holds the low-frequency component of the previous tracking feedback control signal is output, while the tracking feedback control signal is output except when a defect is detected, and the tracking signal adding unit is configured to detect the defect detection unit. Based on the first and second threshold levels, the tracking hold signal and the eccentricity correction signal are added when a defect is detected, and the tracking reverse polarity signal is added to the added signal immediately after the defect is detected and at a predetermined output time. And the tracking brake signal, the tracking feedback control signal generated by the tracking drive signal generation means and the eccentricity generated by the eccentricity correction signal generation means except when a defect is detected. Correction The optical disk device according to claim 1, wherein the optical disk device operates so as to add the number and the number. 3. An optical disk device for recording, reproducing and erasing information using an optical disk as a medium, a disk motor for rotating the disk, and a rotation frequency generating means for outputting a signal corresponding to a rotation angle of the disk motor. An objective lens for focusing laser light on the recording surface of the disc; a photodetector for generating a light reception signal based on the reflected light from the disc of the laser light focused by the objective lens; Defect detection means for setting a threshold level for a light reception signal output from a detector, and detecting dirt and scratches (hereinafter referred to as a defect) on the disk surface based on a predetermined threshold level; and the objective. A focus actuator that drives the lens in a direction perpendicular to the disk surface (hereinafter referred to as the focus direction). And a focus error signal detection unit that detects a focus error signal that is an error in the focus direction between the in-focus point and the predetermined position in the objective lens based on the light reception signal output from the photodetector, and the focus error signal. A focus drive signal generating means for generating a focus feedback control signal for the objective lens to focus on the recording surface of the disc based on the output of the signal detecting means; a focus actuator driver for driving the focus actuator; Focus signal processing means for performing arithmetic processing on the focus feedback control signal generated by the focus driving signal generation means at the time other than the defect detection and the defect detection, based on the threshold level of the defect detection means. The focus signal processing means outputs a focus hold signal which holds a low frequency component of the focus feedback control signal immediately before the defect detection at the time of the defect detection, based on the threshold level of the defect detection means, while detecting the defect. Other than the time, it is possible to adjust the focus defect processing means for outputting the focus feedback control signal and the polarity and gain of the focus feedback control signal up to a predetermined time before, and the focus up to a predetermined time immediately after the defect detection. A signal whose polarity is opposite to that of the feedback control signal and which corresponds to double the amplitude (hereinafter,
This is referred to as the focus reverse polarity signal. ), And a focus brake signal that corrects the transient response of the focus actuator after adding the focus reverse polarity signal,
A focus signal calculator for setting and outputting the output time of the focus reverse polarity signal and the focus brake signal under a predetermined condition, and the focus feedback control signal and the output of the rotation frequency generating means, based on the output of the disk motor. Based on the threshold level of the surface deviation correction signal generating means for calculating a signal for canceling the surface deviation component of the disk or the optical disk device (hereinafter referred to as surface deviation correction signal) for each rotation angle, and the threshold level of the defect detection means. When the defect is detected, the focus hold signal and the surface shake correction signal are added, and the focus reverse polarity signal and the focus brake signal are added to the added signal at a predetermined output time immediately after the defect is detected. On the other hand, except when a defect is detected Includes a focus feedback control signal generated by the focus drive signal generating means and a focus signal adding means that operates to add the surface shake correction signal generated by the surface shake correction signal generating means. Optical disk device. 4. The defect detection means is capable of setting first and second threshold levels with respect to a light reception signal output from the photodetector, and detects a defect based on the first threshold level. Then, the defect detection period is ended based on the second threshold level, and the focus signal processing unit is based on the first and second threshold levels of the defect detection unit except during the defect detection and the defect detection. A focus feedback control signal generated by the focus drive signal generating means is calculated, and the focus defect processing means detects the defect based on the first and second threshold levels of the defect detecting means. Sometimes just before a defect is detected A focus hold signal that holds the low frequency component of the focus feedback control signal is output, while the focus feedback control signal is output except when a defect is detected, and the focus signal addition means is the first of the defect detection means. And based on the second threshold level, when the defect is detected, the focus hold signal and the eccentricity correction signal are added,
Immediately after a defect is detected in this addition signal, it operates to add the focus reverse polarity signal and the focus brake signal at a predetermined output time, while the focus drive signal generating means generates the signal except when a defect is detected. 4. The optical disc apparatus according to claim 3, wherein the optical disc apparatus operates so as to add a focus feedback control signal and a surface shake correction signal generated by the surface shake correction signal generating means.