JPH08147739A - Tracking servo control method and tracking servo controller for disk reproducing device - Google Patents

Abstract

PURPOSE: To make it possible to calculate a frame of one round forward from a present frame decided to have the presence of a flaw on a disk and to control a remedy against the flaw of tracking servo before a pickup enters the flaw region on the disk. CONSTITUTION: Tracks 11 are spirally formed on a CD disk 1. These tracks 11 are composed of the plural frames 12. Synchronizing signals and A time are recorded in each frame. The A time is the same as the absolute time and indicates the lapse time from the start of a program in minute and second. The point t2 of the time of the A time of one round forward from the A time of the frame at the point t1 of the time the central side end 13 of the disk of the flaw on the CD disk 1 is detected is first calculated and the control for the remedy for the flaw of the tracking servo is executed at the point of the time the pickup moves to t2. As a result, the control of the remedy for the flaw of the tracking service is made executable before the point t3 of the time the pickup enters the flaw region 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking servo control method and a tracking servo control device in a disc reproducing apparatus.

[0002]

2. Description of the Related Art Conventionally, a CD type disc (hereinafter referred to as a CD
For scratches on the disk (such as a disk), lower the gain of the tracking servo compared to normal playback to weaken the servo effect, or hold the control output value of the tracking servo and slide the scratched area. Prevents the pickup from swinging to tracks other than the track being traced.

[0003]

In such a control method, since the scratch on the disk is judged based on the change in the light amount obtained from the pickup, at the moment the pickup enters the scratch area, the tracking servo There is a problem that control cannot be performed to prevent damage. Control methods for preventing scratches on the tracking servo include a method of reducing the gain of the tracking servo and a method of holding the control output value of the tracking servo.

The amount of light obtained from the pickup drops after the pickup enters the scratched area. Since a flaw is detected based on the decrease in the light amount and the control for the flaw of the tracking servo is performed, the control for the flaw cannot be performed at the moment when the pickup enters the flaw area.

The present invention provides a tracking servo control method and a tracking servo control device in a disk reproducing device which can perform control for tracking servo damage measures before a pickup enters a scratch area on a disk. With the goal.

[0006]

A tracking servo control method in a disc reproducing apparatus according to the present invention calculates an absolute time of a frame one round ahead from a current frame which is determined to have a flaw on the disc and reads it from the disc. The present invention is characterized in that when the issued absolute time coincides with the calculated absolute time, control is performed to prevent scratches on the tracking servo. Absolute time means the elapsed time from the start of the program, and is called A time, program time, or the like. The absolute time is recorded for each frame of the disc. Control methods for preventing scratches on the tracking servo include a method of reducing the gain of the tracking servo and a method of holding the control output value of the tracking servo.

The first tracking servo control device in the disc reproducing device according to the present invention comprises means for calculating the absolute time of the frame one round ahead from the current frame which is judged to have a flaw on the disc, and read from the disc. It is characterized in that it is provided with a means for performing control as a countermeasure against scratches in the tracking servo when the calculated absolute time matches the calculated absolute time.

The second tracking servo control device in the disk reproducing apparatus according to the present invention performs control for the tracking servo against damage when the end of the disk on the center side of the disk is detected, and at the same time The first to calculate the absolute time of the frame one round ahead from the frame
Means, when the absolute time read from the disk matches the calculated absolute time, control is performed for tracking servo damage countermeasures, and the absolute time of the frame one round ahead of the current frame is calculated. In the second means, and in the frame in which the tracking servo is controlled by the second means to prevent damage, the processing by the second means is repeated until no damage is detected.
It is characterized by comprising means.

For each disc, a history information storage memory for storing the absolute time of a frame in which the end portion of the disc on the disc center side exists in association with the disc identification information, the disc center side of the disc on the disc A fourth means for storing the absolute time of the current frame read from the disc in the history information storage memory together with the disc identification information read from the disc when the edge is detected, the disc read from the disc When the identification information is stored in the history information storage memory and the absolute time read from the disc matches the absolute time stored in the history information storage memory in relation to the disc identification information. Controls the tracking servo against scratches and calculates the absolute time of the frame one round ahead from the current frame Fifth means that, as well as in the frame in which the control is performed for the tracking servo wound measures by the fifth means, scratches until no longer detected, the sixth means for repeating the processing by the fifth means, the second
It may be provided in the tracking servo control device.

The absolute time of the frame one round ahead of the current frame is calculated, for example, based on the absolute time read from the current frame, the linear velocity and the track pitch.

[0011]

In the tracking servo control method for the disk reproducing apparatus according to the present invention or the first tracking servo control apparatus for the disk reproducing apparatus according to the present invention, the frame one cycle ahead of the current frame determined to have a scratch on the disk is detected. Absolute time is calculated. Then, when the absolute time read from the disk matches the calculated absolute time, control is performed to prevent damage to the tracking servo.

In the second tracking servo controller in the disk reproducing apparatus according to the present invention, when the edge of the disk on the center side of the disk is detected, the tracking servo is controlled as a countermeasure against the scratch. The absolute time of the frame one round ahead from the current frame is calculated (first processing).

Then, when the absolute time read from the disk matches the calculated absolute time, control is performed to prevent scratches in the tracking servo, and the absolute value of the frame one round ahead from the current frame is performed. The time is calculated (second process). The second process is repeated until the scratch is no longer detected in the frame in which the control for the scratch countermeasure of the tracking servo is performed by the second process.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a CD type disc reproducing apparatus will be described below with reference to the drawings.

First, the basic idea of the tracking servo gain control for scratches on a CD type disk (CD disk) will be described.

As shown in FIG. 6, the CD disk 1 has spirally formed tracks 11. Truck 11
Is composed of a plurality of frames 12. And
For each frame 12, a synchronization signal and A time (AB
SOLUTE TIME: Absolute time) is recorded. The A-time represents the elapsed time from the start of the program in minutes and seconds. The A time also includes the frame number within 1 second. The CD disc has 75 frames of data for 1 second, and the A time is recorded in a data format of minutes / seconds / frames.

In this embodiment, as shown in FIG. 7, the scratch 1 (end of the scratch on the center side of the disk) 1 is first on the CD disk 1.
From the A time of the frame at the time t1 when 3 is detected, 1
By calculating the A time at the lap ahead and performing control for the tracking servo against scratches at the time t2 when the pickup moves to the frame in which the calculated A time is recorded, from the time t3 when the pickup enters the scratch area. In addition, it is possible to control the tracking servo to prevent scratches. Control methods for preventing scratches on the tracking servo include a method of reducing the gain of the tracking servo and a method of holding the control output value of the tracking servo.

Even in this case, when the pickup first enters the scratch area, control for the tracking servo against scratches cannot be performed at the moment when the pickup enters the scratch area, but from one round ahead. At the moment when the pickup enters the scratch area, it becomes possible to perform the control for the scratch countermeasure.

Generally, the scratches 13 on the CD disc are shown in FIG.
As shown in FIG. 5, many CD disks 1 extend in the radial direction, the widths of both ends thereof are narrow, and the width of the middle portion of the length thereof is wide. Therefore, when such a scratch is detected for the first time, the width of the scratch is narrow, so even if control is performed to prevent damage after the pickup enters the scratch area, the pickup will be removed from the track being traced. There are few things.

However, since the width of the middle portion of the scratch is wide, the pickup can be removed from the track being traced when the control for the scratch countermeasure is performed after the pickup enters the scratch area. It is highly likely. In this embodiment, after the scratch is first detected, the control for the scratch can be performed at the moment when the pickup enters the scratch area, so that the pickup is less likely to be detached from the traced track.

The current frame on the CD disc (hereinafter
If the number of frame updates from the current frame) to the frame one round ahead is K and the A time of the current frame is a, the A time a ′ one round ahead of the current frame is expressed by the following formula 1. It

[0022]

## EQU1 ## a '= a + K

For example, the A time a of the current frame is "1".
Assuming that the frame update count is 0 minutes 12 seconds 20 frames "and the number of frame updates up to the frame one round ahead is 10, the A time a'one cycle ahead is" 10 minutes 12 seconds 30 frames ". When the frame number in the A time changes from 75 to 0, the content of the second is incremented by one.

The number of frame updates K from the current frame to the frame one round ahead is expressed by the following equation 2.

[0025]

## EQU2 ## K = 2.pi. (D + T.P) / WD: The inner diameter of the program area (recording area) of the CD disc, which is usually 25 mm. P: Track pitch (space between tracks), which is usually 0.0016 mm. W: The moving distance of the pickup per frame,
Linear velocity / 75. In the case of a CD disc, the linear velocity is constant, usually 1300 mm / sec. T: Track number of the current frame.

That is, 2π (D + T ·
P) corresponds to the circumference of the track in which the current frame exists, and the circumference is divided by the movement distance per frame to obtain the number of frames up to the frame one cycle ahead.

The track number T of the current frame is expressed by the following equation 3 where a is the A time of the current frame and v is the linear velocity.

[0028]

Equation 3] T = [{(a · P · v / π) + D 2} 1/2 -D ] / P

A method of deriving Equation 3 will be described. Assuming that the radius of a track with the current frame is r, the track number T of the current frame is calculated by dividing the distance between the innermost track and the track with the current frame by the track pitch P, as shown in the following Equation 4. Required by.

[0030]

## EQU00004 ## T = (r-D) / P

Further, the track length l from the start point of the track to the current frame is expressed by the following formula 5, where the area of the region sandwiched between the innermost track and the track with the current frame is the track pitch P. It is obtained by dividing by.

[0032]

(5) l = π (r ² −D ² ) / P

Also, the A time a (sec) of the current frame
Is calculated by dividing the track length 1 from the start point of the track to the current frame by the linear velocity v, as shown in the following formula 6.

[0034]

## EQU6 ## a = 1 / v

By substituting the equation 5 into 1 of the equation 6, the following equation 7 is obtained.

[0036]

## EQU7 ## a = π (r ² −D ² ) / P · v = (πr ² / P · v) − (πD ² / P · v)

By transforming Equation 7, Equation 8 can be obtained.

[0038]

[Formula 8] πr ² / P · v = a + (πD ² / P · v) r ² = (a · P · v / π) + D ² r = {(a · P · v / π) + D ² } ^{1 / 2}

By substituting the r obtained by the equation 8 into the equation 4, the equation 3 can be obtained.

FIG. 1 shows the structure of a CD disc reproducing apparatus.

The CD disk 1 is rotationally driven by the disk motor 2. The optical pickup 3 reads information from the CD disk 1. The data read by the optical pickup 3 and the error signal (focus error signal, tracking error signal) obtained from the optical pickup 3 are amplified by the amplifier 4. Of the signals amplified by the amplifier 4, signals other than error signals are sent to the signal demodulator 5. The signal demodulator 5 demodulates the input signal and outputs the demodulated main signal (audio signal, video signal, other data) as a reproduction signal.

Further, the signal demodulator 5 outputs the sync signal and the A time signal read by the pickup 3 and the light amount signal obtained from the pickup 3. The light amount signal and the A time signal are sent to the flaw processing circuit 9. The flaw processing circuit 9 detects the flaw area and outputs a gain control signal for the tracking servo.

Error signal from amplifier 4, signal demodulator 5
And the gain control signal from the flaw processing circuit 9 are sent to the servo control circuit 6. Servo control circuit 6
Are for controlling focus servo, tracking servo, spindle servo, and the like.

The focus servo is for adjusting the vertical position of the objective lens based on the focus error signal so that the spot of the laser beam emitted from the pickup 3 accurately converges on the pit. The tracking servo is a servo that adjusts the reflection angle of the tracking mirror based on the tracking error signal to make the laser beam spot follow a track composed of a pit row, and moves the entire pickup 3 in the radial direction of the CD disk 1 as the reproduction progresses. It consists of a servo to make. The spindle servo is for controlling the rotation speed of the CD disc 1 by controlling the disc motor 2 based on the synchronization signal.

The servo control circuit 6 outputs a motor control signal and a servo control signal. The motor control signal is sent to the drive circuit 7 of the disk motor 2. The servo control signal is sent to the pickup 3.

The signal demodulator 5, flaw processing circuit 9 and servo control circuit 6 are controlled by a system control circuit 8 including a microcomputer, DSP and the like.

FIG. 2 shows the structure of the scratch processing circuit 9.

The scratch processing circuit 9 includes a light amount determination circuit 93 to which a light amount signal is input and an A time / A time signal to which an A time signal is input.
A track number conversion circuit 91, an A time storage memory 92,
A history information storage memory 95 and a gain control circuit 94 are provided.

FIG. 3 shows the contents of the history information storage memory 95. The history information storage memory 95 stores disc identification information and scratch information for each CD disc in which a scratch is detected when the playback is performed by the present playback apparatus. As the disc identification information, the number of songs included in the subcode, index information, minute / second / frame data in each song, total minute / second / frame data, and the like are used. As the scratch information, the A time of the frame in which each scratch is first detected (the frame having the scratch center side edge of the disc) is used.

4 and 5 show the tracking servo control processing procedure.

When the reproduction of the CD disc 1 is started, it is judged whether or not the disc identification information in the sub-code read from the CD disc 1 is already stored in the history information storage memory 95 (step). 1).

When the read history identification information is not stored in the history information storage memory 95, the CD disc 1 has never been played by the playback apparatus in the past or has been played in the past. It is determined that no scratch is detected, and the process proceeds to step 3.

When the read history identification information is stored in the history information storage memory 95, it is determined that the CD disk 1 has been reproduced in the past by the reproducing apparatus and a flaw has been detected, and the process proceeds to step 2. .

In step 2, the history information storage memory 95
The scratch information (A time) corresponding to the disc identification information of the CD disc 1 in FIG. Then, the process proceeds to step 3.

In step 3, it is judged whether or not the A time read from the CD disc 1 has been updated. That is, it is judged whether or not the data reading frame of the CD disc 1 moves to the next and the A time has changed. C
Until the A time read from the D disc 1 is updated, the light amount determination circuit 93 determines whether or not the light amount has dropped below a predetermined value (step 4).

When the light quantity falls below a predetermined value (YES in step 4), the A time / track number conversion circuit 91 calculates the track number of the current frame from the current A time (step 5). . This calculation is performed based on Equation 3 above.

Then, the gain control circuit 94 performs a process (tracking gain down / hold process) for lowering the tracking servo gain or holding the tracking servo control output value (step 6). Also, using the track number of the current frame calculated in step 5 above, the A time of the frame one round ahead from the current frame is calculated based on the above equations 1 and 2, and the calculation result is the A time storage memory. It is stored in 92 (step 7).

Further, the history information memory 95 stores the current A
It is checked whether or not the time is stored, and if not stored, the current A time is stored in association with the disc identification information of the CD disc 1 (step 8). Then, it is in a standby state until the A time is updated.

When the A time is updated and the pickup moves to the next frame (step 9), the control of the tracking servo is returned to the normal control (step 1).
0). Then, the process proceeds to step 11.

In step 3 above, when the A time is updated, the process proceeds to step 11. In step 11, the A time / track number conversion circuit 91 calculates the track number of the current frame from the current A time. This calculation is performed based on Equation 3 above.

Next, the A time stored in the A time storage memory 92 is compared with the current A time (step 12). If they do not match (NO in step 13), the process returns to step 3. Therefore, the light amount determination processing is performed in step 4 until the current A time is updated.

When the A time stored in the A time storage memory 92 matches the current A time (YES in step 13), the gain of the tracking servo is lowered by the gain control circuit 94 or the tracking servo gain is changed. A process (tracking gain down / hold process) for holding the control output value is performed (step 14).

Then, until the A time is updated,
The light quantity determination circuit 93 determines whether or not the light quantity is lower than a predetermined value (steps 15 and 16). When the light quantity falls below a predetermined value, the flag F is set (F
= 1) (step 17).

When the A time is updated (YES in step 15), the tracking servo control is returned to the normal control (step 18). Then, it is determined whether or not the flag F is set (step 19).

When the flag F is set (F = 1), it is determined that there is a scratch in the previous frame, and the track number of the previous frame calculated in step 11 above is used to detect one round ahead from the previous frame. The A time of the frame is calculated based on the above equations 1 and 2, and the calculation result is stored in the A time storage memory 92 (step 2).
0). Then, after the flag F is reset (F = 0) (step 21), the process proceeds to step 11. If the A-time in the current frame is not stored in the A-time storage memory 91, the process proceeds from step 11 to step 3 through steps 12 and 13, so that the light amount determination process in step 4 is also performed in the current frame. Done.

When the flag F is not set (F = 0) in the above step 19, it is judged that the pickup is located on the track beyond the scratched area in the previous frame, and the A time storage memory 92. To A time of the previous frame is deleted (step 22). Then, the process proceeds to step 11. If the A time in the current frame is not stored in the A time storage memory 91, the process proceeds from step 11 to step 3 through steps 12 and 13, so that the light amount determination process of step 4 is performed in the current frame. .

In the above embodiment, after the scratched area is first detected, the gain of the tracking servo can be reduced or the control output value of the tracking servo can be held at the moment the pickup enters the scratched frame. , The pickup is less likely to come off the track being traced than in the past.

For the CD disc in which the scratch information is stored in the history information storage memory 95, the tracking servo is performed at the moment when the pickup enters the scratched frame in the entire scratch area specified by the scratch information. Since it is possible to reduce the gain of or to hold the control output value of the tracking servo, the pickup is less likely to be disengaged from the track being traced, as compared with the conventional case.

In the above embodiment, the history information storage memory 95
In addition, although the scratch information of the CD disc reproduced in the past is stored, such a history information storage memory 95 may not be provided. If the history information storage memory 95 is not provided,
Steps 1, 2, and 8 of FIG. 4 are omitted.

In the above embodiment, 1 is calculated from the current frame according to the equation 2 derived based on the linear velocity and the track pitch.
Although the number of frame updates up to the previous round is calculated, the number of frame updates from the current frame to the next round may be calculated as follows.

That is, 1 from the track of each track number.
The number of frame updates up to the track ahead is determined by calculation or experiment in advance, and the number of frame updates from the track of each track number to the track one round ahead is stored in the storage device in association with the corresponding track number I will let you. Then, when it is desired to obtain the frame update number from the current frame to one round ahead, the frame update number corresponding to the current track number (obtained by Equation 3) may be read from the storage device.

The present invention can be applied to a disc reproducing device other than a CD disc as long as the disc reproducing device stores the elapsed time from the start of the program corresponding to the A time.

[0073]

According to the present invention, it is possible to perform control for the tracking servo against scratches before the pickup enters the scratched area on the disk. Compared to less.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a CD disc reproducing apparatus.

FIG. 2 is a block diagram showing a configuration of a flaw processing circuit.

FIG. 3 is a schematic diagram showing the contents of a history information storage memory.

FIG. 4 is a flowchart showing a tracking servo control processing procedure.

FIG. 5 is a flowchart showing a tracking servo control processing procedure.

FIG. 6 is a schematic diagram showing a CD disc.

FIG. 7 is a schematic diagram for explaining the basic idea of the present invention.

[Explanation of symbols]

 1 CD Disc 2 Disc Motor 3 Optical Pickup 6 Servo Control Circuit 7 Drive Circuit 8 System Control Circuit 9 Scratch Treatment Circuit 91 A Time / Track Number Conversion Circuit 92 A Time Storage Memory 93 Light Quantity Judgment Circuit 94 Gain Control Circuit 95 History Information Storage Memory

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ritsu Katayama 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (6)

[Claims] 1. An absolute time of a frame one round ahead from a current frame determined to have a scratch on a disc is calculated,
A tracking servo control method in a disk reproducing device, which performs control for tracking servo damage countermeasures when the absolute time read from the disk matches the calculated absolute time. 2. A means for calculating an absolute time of a frame one round ahead from a current frame determined to have a scratch on the disk, and an absolute time read from the disk coincides with the calculated absolute time. Sometimes, a tracking servo control device in a disk reproducing device, which is provided with a means for performing control for tracking servo damage countermeasures. 3. When the end of the disc on the center side of the disc is detected, control is performed to prevent the tracking servo from being scratched, and the absolute time of the frame one round ahead from the current frame is calculated. 1 means, when the absolute time read from the disc matches the calculated absolute time, control is performed to prevent scratches on the tracking servo, and the absolute time of the frame one round ahead from the current frame is calculated. And a third means for repeating the process by the second means until the scratch is no longer detected in the frame in which the tracking servo is controlled by the second means to prevent scratches. Tracking servo controller in playback device. 4. A history information storage memory for storing, for each disc, the absolute time of a frame in which the disc center side end of the disc is present in association with the disc identification information, and the disc on the disc A fourth means for storing, in the history information storage memory, the absolute time of the current frame read from the disc together with the disc identification information read from the disc when the center side end is read from the disc. When the disc identification information is stored in the history information storage memory, the absolute time read from the disc matches the absolute time stored in the history information storage memory in association with the disc identification information. At the same time, control is performed to prevent scratches on the tracking servo, and the absolute time of the frame one round ahead from the current frame is calculated. And a sixth means for repeating the process by the fifth means until the scratch is no longer detected in the frame in which the tracking servo is controlled to prevent the scratch by the fifth means. Item 4. A tracking servo control device in the disk reproducing device of item 3. 5. The tracking in the disc reproducing apparatus according to claim 1, wherein the absolute time of the frame one round ahead of the current frame is calculated based on the absolute time read from the current frame, the linear velocity and the track pitch. Servo control method. 6. The absolute time of the frame one round ahead from the current frame is calculated based on the absolute time read from the current frame, the linear velocity and the track pitch.
A tracking servo control device in the disk reproducing device described in 3 and 4.