JPH11213403A - Tracking servo method and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute a normal reproducing operation even when disturbance vibration is applied on an optical disk device by detecting vibration of a prescribed value or above applied for the outside, thereby stopping the operation that increases the gain of the rotational frequency range of an optical disk and increasing the gain of the entire servo band of servo control. SOLUTION: A vibration detection circuit 14 extracts vibration from outside the device through a band pass filter circuit, and, if the amplitude level is at a prescribed value or above, outputs a vibration detection signal. A controller 15, with the vibration detection signal inputted, stops the sample action and the output of a repetitive compensator 6. Concurrently, the controller 15 increase the gain of an amplifier 4 by a prescribed quantity so as to compensate the lowering of the gain in the rotational frequency range of an optical disk 16. As a result, the lowering of the servo gain, which is caused by the output stoppage of the repetitive compensator 6, is presented by increasing the gain over the entire servo band by means of the amplifier 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo system for a rotary recording medium, and more particularly to a tracking servo method and an optical disk device for an optical disk device.

[0002]

2. Description of the Related Art As a rotating recording medium, an optical disk, such as an audio CD, a CD-ROM, a write-once optical disk, a rewritable magneto-optical disk device, and the like have already been put into practical use. Active development is underway.

Since the information track pitch of this optical disk is very narrow, a high-precision servo device is required to accurately reproduce information. Recently, a CD-ROM drive has been attracting attention as a central player of multimedia as a data reproducing apparatus for a computer. However, the need for high-speed operation has been increased in accordance with an increase in application software that handles a large amount of data such as image data. At present, a drive device capable of reproducing information at a rotation speed several times higher than the conventional music reproduction speed has been developed. In a servo device of a drive device in which such a disk rotates at a high speed, a design is performed in which a so-called servo band is eventually increased to secure a loop gain in a rotation frequency region of the disk.

However, in general, increasing the servo band impairs the stability of the servo system in response to noise or scratches on the disk irrelevant to the servo signal, or the pickup actuator or actuator due to wasteful power loss. There are problems such as heat generation of the circuit and inability to reduce power consumption.

In order to solve the above-mentioned problems, a servo device as shown in FIG.

FIG. 4 is a block diagram of a conventional tracking servo device of an optical disk device. 4, 1 is an optical pickup, 2 is a spindle motor for rotating a disk, 3 is a phase compensation filter, 4 is an amplifier, 5 is a driver, 6 is a repetition compensator, 7 is a low-pass filter, 8 is an A / D converter, 9 is a memory, 10 is a D / A converter, 11
Is an adder, 12 is a spindle motor control circuit, 13 is R
F amplifier, 14 is a vibration detection circuit, 15 is a controller,
Reference numeral 16 denotes an optical disk.

The operation of the tracking servo device in the conventional optical disk device will be described below with reference to FIG. The rotation of the optical disk 16 is controlled by the spindle motor control circuit 12 and the spindle motor 2, and the tracking error signal generated by the RF amplifier 13 based on the optical signal detected by the optical pickup 1 is rotated by the repetition compensator 6. The gain in the frequency domain is amplified. After the gain amplification of the tracking error signal, the signal passes through a phase compensation filter 3 for stabilizing the servo loop and an amplifier 4 for securing a necessary gain in the entire servo band, and is driven by a driver 5 for driving a tracking actuator of the optical pickup 1. It is converted to a signal and output.

The spindle motor 2 outputs, for example, an encoder pulse signal generated based on the output of a Hall element provided in the spindle motor 2 and used for rotation control. The memory 9 of the repetition compensator 6 samples the signal of the output stage of the repetition compensator 6 by the A / D converter 8 at the timing of the encoder pulse signal and stores it in the memory 9 at the same time as the rotation of the spindle motor 2 one rotation before. The D / A converter 10 stores the sampled and stored data.
, And the adder 11 performs a process of adding the tracking error signal to the output.

By using such a repetition compensator 6, it is possible to amplify the gain of only the rotation frequency region of the optical disk 16, which is a low-frequency signal filtered by the low-pass filter 7, and the filtering prevents passage. The tracking error can be suppressed without making the servo band extra high.

However, such a repetition compensator 6 is effective only for an error signal in the rotation frequency region of the optical disk 16 and suppresses errors outside the rotation frequency region of the optical disk 16 caused by disturbance vibration from outside the apparatus. Can not. If the compensator 6 repeatedly samples and outputs such an error signal that is not synchronized with the rotation cycle of the optical disk 16, a malfunction such as an increase in errors may occur. Therefore, when such a disturbance is applied to the apparatus, it is necessary to stop the sampling operation of the repetitive compensator 6. The vibration detection circuit 14 extracts a disturbance appearing in the tracking error signal when a vibration from outside the apparatus is given by a band-pass filter circuit, and outputs a vibration detection signal when the amplitude level becomes larger than a certain value. is there. Controller 1
5 controls the normal operation of the repetition compensator 6 when the vibration detection signal is not input from the vibration detection circuit 14, and controls to stop the output from the repetition compensator 6 when the vibration detection signal is input. Do.

[0011]

However, since the conventional tracking servo device is configured as described above, when the operation of the repetitive compensator 6 is stopped, the servo gain is reduced, resulting in rotation of the optical disk. There is a problem that an error signal increases.

FIG. 5 shows a signal waveform diagram in a conventional tracking servo device. 5A shows a waveform of the tracking error signal, and FIG. 5B shows a vibration detection signal by the vibration detection circuit 14. In a state where there is no disturbance vibration, a disturbance detection signal is detected almost simultaneously with the occurrence of a high-frequency component in the tracking error signal due to disturbance vibration being applied from the outside of the apparatus, and the output of the compensator 6 is repeatedly stopped by the controller 15. Therefore, it can be seen that the rotational frequency component of the optical disk 16 in the tracking error signal has increased.

As described above, in the conventional tracking servo device, when the operation of the repetitive compensator 6 is stopped, the servo gain is reduced and the error signal due to the rotation of the optical disk 16 is increased. There was a problem that it became impossible.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a tracking servo device capable of executing a normal reproducing operation even when disturbance vibration is applied from outside the device.

[0015]

SUMMARY OF THE INVENTION The present invention detects an externally applied vibration of a predetermined value or more to an optical disk device, and increases the rotational frequency gain of the optical disk based on the detection signal. In addition to the stop, the gain of the entire servo band of the servo control is increased.

With the above configuration, it is possible to increase the loop gain only in the rotational frequency region of the disk.
Also, when vibration is applied from outside the device,
To provide a tracking servo method and an optical disk device for an optical disk device, which can increase the servo band after stopping the operation of the error signal correction means, and can stably reduce power consumption even with a disturbance signal. Can be.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention detects that an optical disk device is subjected to vibration of a predetermined value or more from the outside, and based on the detection signal, detects the rotation frequency range of the optical disk. The operation of increasing the gain is stopped, and the gain of the entire servo band of the servo control is increased. According to the present invention, a normal reproduction operation can be performed even when disturbance vibration is applied.

According to the present invention, it is possible to increase the loop gain only in the rotational frequency region of the disk with a simple structure, and to operate the error signal correcting means when vibration is applied from outside the apparatus. Since the servo band can be increased after stopping the operation, a tracking servo method that is stable with respect to a disturbance signal and that can reduce power consumption can be realized.

According to a second aspect of the present invention, an optical disk of an information recording medium is rotated to execute recording or reproduction of information on an information track of the optical disk by servo control, and a gain in a rotation frequency region of the optical disk is obtained. In the tracking servo method of the optical disc for amplifying the servo loop and stabilizing the servo loop, in the servo droop, compensating means constituted by a variable gain amplifier or characteristic variable filter, rotating means for rotating the disc,
A rotational position detecting means for generating a timing signal according to the rotational position of the rotating means, an error signal correcting means for sampling an error signal based on the timing signal and simultaneously adding a correction signal to a preceding stage of the error signal; Control means for changing the characteristics of the compensator at the same time as stopping the sampling operation of the means, and having a simple configuration, and usually increasing the loop gain only in the rotational frequency region of the disk. In addition, when vibration is applied from the outside of the apparatus, the operation of the error signal correction unit is stopped, and the servo band can be increased.

(Embodiment) Hereinafter, a recording / reproducing apparatus for an optical disk apparatus according to an embodiment of the present invention will be described together with a method thereof.
This will be described with reference to the drawings.

FIG. 1 is a block diagram of a tracking servo device of an optical disk device according to an embodiment of the present invention.
3 is an operation flowchart of FIG. 1, and FIG. 3 is a signal waveform diagram of FIG. In FIG. 1, 1 is an optical pickup, 2 is a spindle motor for rotating a disk, 3 is a phase compensation filter,
4 is an amplifier, 5 is a driver, 6 is a repetition compensator, 7 is a low-pass filter, 8 is an A / D converter, 9 is a memory,
0 is a D / A converter, 11 is an adder, 12 is a spindle motor control circuit, 13 is an RF amplifier, 14 is a vibration detection circuit, 15 is a controller, and 16 is an optical disk. The operation of the tracking servo device according to the embodiment of the present invention will be described below with reference to FIGS.

The rotation of the optical disk 16 is controlled by the spindle motor control circuit 12 and the spindle motor 2, and the tracking error signal generated by the RF amplifier 13 based on the optical signal detected by the optical pickup 1 is repeated by the repetition compensator 6. After the gain in the rotation frequency region of the optical disk 16 has been amplified, it passes through a phase compensation filter 3 for stabilizing the servo loop and an amplifier 4 for securing the required gain in the entire servo band, and is then subjected to a driver 5 by a driver 5 for the tracking actuator of the optical pickup 1. It is converted into a driving signal for driving and output.

From the spindle motor 2, for example, an encoder pulse signal generated based on the output of a Hall element provided in the spindle motor 2 and used for rotation control is output. The memory 9 of the repetition compensator 6 samples the output stage signal of the repetition compensator 6 at the timing of the encoder pulse signal by the A / D converter 8 and stores the sampled signal in the memory 9 at the same time as the sampling before one rotation of the spindle motor. The stored data is output by the D / A converter 10, added to the tracking error signal by the adder 11, and output.

By using such a repetition compensator 6, it is possible to amplify the gain of only the rotation frequency region of the optical disc 16, and suppress the tracking error without making the servo band extra high. In addition, the signal output from the repetitive compensator 6 is stored in the memory 9 as a past history, and the controller 15 selects the data corresponding to the optimum value from the history data. Signal of D /
It is also possible to adopt a configuration in which the signal is output to the adder 11 via the A converter 10.

Next, the operation of the tracking servo device based on the configuration will be described with reference to FIG.
This will be described with reference to FIG.

The vibration detecting circuit 14 extracts a disturbance appearing in the tracking error signal when a vibration from outside the apparatus is given by a band pass filter circuit (step 1), and judges whether the amplitude level is equal to or larger than a predetermined value. (Step 2). If the vibration level is determined by the vibration detection circuit 14 to be equal to or higher than a predetermined value, a vibration detection signal is output (step 3). The controller 15 repeatedly stops the sampling operation and output of the compensator 6 when the vibration detection signal is input (Step 4).

At the same time as the sampling operation of the repetition compensator 6 is stopped, the controller 15 sets the gain of the amplifier 4 in order to compensate for the decrease in the gain in the rotation frequency region of the optical disk 16 by stopping the operation of the repetition compensator 6. Is increased by a predetermined amount (step 4).

As a result, a decrease in the servo gain caused by stopping the output of the repetitive compensator 6 can be prevented by increasing the gain for the entire servo band by the amplifier 4.

FIG. 3A shows the waveform of the tracking error signal, and FIG. 3B shows the vibration detection signal by the vibration detection circuit. Normally, in a state where there is no disturbance vibration, a vibration detection signal is detected immediately after a high frequency component is generated in the tracking error signal due to disturbance vibration being applied from outside the apparatus. Subsequently, the sampling operation and the output of the compensator 6 were repeatedly stopped by the controller 15, and at the same time, the gain of the amplifier 4 in the servo loop was increased.
It can be seen that the rotational frequency component of the optical disk 16 in the tracking error signal does not increase, and the vibration frequency component is suppressed as compared with the related art (see FIG. 5).

As described above, according to the present invention, it is possible to increase the loop gain in the rotation frequency region of the optical disk 16 without increasing the servo band, and to operate without error even if disturbance is applied from outside the apparatus. A servo device with high tracking ability can be realized with a simple configuration capable of suppressing signals.

Although only the tracking servo device in the optical disk device has been described so far, it is added that the present invention can be easily applied to a focus servo device and other servo devices related to a rotary recording medium.

[0032]

As described above, according to the present invention, it is possible to increase the loop gain in the rotation frequency region of a disk without increasing the servo band, and to malfunction even if a disturbance is given from outside the apparatus. An extremely excellent tracking servo method and an optical disk device which can suppress an error signal without error and have a high tracking ability and a high resistance to disturbances can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of a tracking servo device of an optical disc device according to an embodiment of the present invention.

FIG. 2 is an operation flowchart of FIG. 1;

FIG. 3 is a diagram showing a waveform of a signal in FIG. 1;

FIG. 4 is a block diagram of a tracking servo device of a conventional optical disk device.

FIG. 5 is a diagram showing signal waveforms in a conventional tracking servo device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical pickup 2 Spindle motor 3 Phase compensation filter 4 Amplifier 5 Driver 6 Repetition compensator 7 Low-pass filter 8 A / D converter 9 Memory 10 D / A converter 11 Adder 12 Spindle motor control circuit 13 RF amplifier 14 Vibration detection circuit 15 Controller 16 Optical disk

Claims (2)

[Claims] An optical disk of an information recording medium is rotated to execute recording or reproduction of information on an information track of the optical disk by servo control, and a gain in a rotation frequency region of the optical disk is amplified to stabilize a servo loop. A tracking servo method for detecting the vibration of a predetermined value or more externally applied to the optical disk device, and stopping the operation of increasing the gain in the rotation frequency region of the optical disk based on the detection signal, A tracking servo method comprising: increasing a gain of an entire servo band of the servo control. 2. An optical disk of an information recording medium is rotated to execute recording or reproduction of information on an information track of the optical disk by servo control, and a gain in a rotation frequency region of the optical disk is amplified to stabilize a servo loop. An optical disk device, comprising: a compensating means in the servo loop comprising a variable gain amplifier or variable characteristic filter; and a rotational position detecting means for generating a timing signal in accordance with the rotational position of the rotating optical disk. Error signal correction means for sampling the error signal based on the timing signal and simultaneously adding a correction signal to the preceding stage of the error signal; and stopping the sampling operation of the error signal correction means while simultaneously compensating the error signal. An optical disk device comprising: a control unit for changing characteristics.