JPH1011771A - Optical disk device, and adjusting method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk device capable of properly adjusting other parameters such as the adjustment of a focusing bias even before adjusting the gain of a tracking servo. SOLUTION: A control part 40 sets a prescribed gain sufficiently larger than a gain at the time of normal operation and a phase compensation characteristic for stabilizing a servo system in a tracking servo signal generating part 31 and the setting ability of tracking is made high. Under this condition, a prescribed value of an initial control characteristic is set in a focusing servo signal generating part 21, the objective lens is forcedly moved in the focusing direction by adding a prescribed signal from a disturbance impressing part 22 and the condition of proper focusing is detected. The gain and the phase of the focusing servo signal generating part 21 is adjusted so that the state of proper focusing is maintained as a stationary state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus for performing recording / reproduction on a disk-shaped recording medium by using optical means, and an optical disk apparatus capable of appropriately setting control parameters. And its adjustment method.

[0002]

2. Description of the Related Art In an optical recording / reproducing apparatus (hereinafter, referred to as an optical disk apparatus) for recording / reproducing data on a so-called optical disk such as a compact disk (CD) or a mini disk (MD), data is recorded by a tracking servo. Track, and the focus servo keeps the distance between the objective lens and the recording surface of the optical disc constant.
A signal can be normally recorded or reproduced on an optical disk. These servo processes are performed based on each error signal such as a tracking error signal and a focus error signal generated based on the distribution of the reflected light of the light beam applied to the optical disk. A servo signal is generated by applying an appropriate gain to these error signals and performing phase compensation and the like, and drives a tracking actuator, a focusing coil, and the like via a driver.

In order to perform such servo processing properly,
Also, in order to properly reproduce signals from optical discs,
It is necessary to appropriately set various parameters defining the servo operation and the reproduction process. However, the control conditions change depending on various factors such as the set optical disk and the state of the set. Therefore, it is preferable to adjust those parameters every time the conditions change. For example, an optimum point of a focus bias important for obtaining a more appropriate signal from an optical disc changes due to eccentricity of the disc. Therefore, the adjustment is made every time the disk is replaced by a method of forcibly changing the focus bias and detecting the position where the focusing state is optimal.

[0004]

However, in the above-described parameter adjustment, when the optimum state is detected by changing the parameter, the tracking may be deviated and the appropriate parameter adjustment may not be performed. There is a problem that there is. For example, when adjusting the focus bias described above, by changing the focus bias, the focus of the light beam is blurred, an error signal cannot be obtained correctly, and the tracking becomes unstable and the tracking may be lost. Basic adjustments such as adjustment of the focus bias are usually performed before adjusting the gain of the tracking servo. In other words, the adjustments of the tracking servo and the like cannot be made unless the focus bias is adjusted. Therefore, from the viewpoint that the settling property of the tracking servo at the time of the adjustment is not sufficient, there is a high possibility that the tracking will be violated and the adjustment cannot be properly performed. In particular, when an eccentric disk is mounted, such a state is highly likely to occur.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an optical disk apparatus capable of appropriately adjusting other parameters such as adjustment of a focus bias even before adjustment of a tracking servo gain. It is another object of the present invention to provide a method of adjusting an optical disc apparatus in which other parameters such as adjustment of a focus bias can be appropriately adjusted before adjusting the gain of a tracking servo.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the tracking servo gain is increased by substantially increasing the gain of the tracking servo at the time of the parameter adjustment operation, so that the tracking stabilization is enhanced and off-tracking is prevented. I made it.

Therefore, the optical disk device of the present invention
A tracking error signal detecting means for detecting a tracking error signal based on the reflected light of the light beam applied to the optical disc; and generating a tracking servo signal by amplifying the tracking error signal with a predetermined gain and performing phase compensation. Tracking servo signal generating means, tracking actuator driving means for actually driving the tracking actuator based on the tracking servo signal, and tracking servo characteristic changing means and parameter adjusting means. The tracking servo characteristic changing means is referred to for generating a tracking servo signal in the tracking servo signal generating means when adjusting a parameter for defining a predetermined operation of the optical pickup relating to tracking and focusing. The gain is changed to a predetermined value large enough to make it difficult to perform off-track than during normal operation.Further, the phase for phase compensation is also substantially changed in such a manner that the change in the gain enhances tracking stabilization. Change so that a servo signal that contributes can be generated.

The parameter adjusting means changes the predetermined parameter when tracking is performed based on a tracking servo signal generated with reference to the changed gain and phase, and performs the predetermined operation. The predetermined parameter is adjusted to an appropriate state by detecting a state in which is performed appropriately. The time when the parameters are adjusted is, for example, when a new optical disk is accessed, for example, when the power is turned on or when the disk is replaced. Specifically, the parameter is a parameter for determining a focus bias applied to the optical pickup so that focusing can be performed appropriately.

The method of adjusting an optical disk device according to the present invention is a method of adjusting an arbitrary parameter that defines a predetermined operation of an optical pickup relating to tracking, focusing, and the like in an optical disk device. When the access to a new optical disk is started, the gain of the tracking servo is changed to a predetermined gain that is larger than the gain in the normal operation and makes it more difficult to perform off-tracking than in the normal operation. Performing tracking based on the obtained gain, changing the parameter while the tracking is being performed, and detecting a state in which the predetermined operation performed based on the changed parameter is substantially optimal. Using the detected parameter at the time of the optimal operation as the parameter used at the time of the normal operation. It is set as the over data.

[0010] Changing the gain to a predetermined gain which makes it more difficult to perform off-tracking than in the normal operation and performing tracking based on the gain substantially contributes to improving the settling of tracking. This means that such a servo signal is generated, and also includes a change in phase for phase compensation accompanying a change in gain. Specifically,
The predetermined parameter is a parameter that substantially sets a focus bias.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIG. The optical disc device 1 has an optical pickup 10, a focus servo unit 20, a tracking servo unit 30, and a control unit 40. Optical pickup 10
Has an optical block 11, a focus actuator 12, and a tracking actuator 13. The focus servo unit 20 includes the focus servo signal generation unit 2
1, a disturbance applying unit 22, an adder 23, and a focus drive amplifier 24. Tracking servo unit 30
Are the tracking servo signal generation unit 31 and the disturbance application unit 3
2. Adder 33 and tracking drive amplifier 34
Having.

The configuration and function of each unit will be described below. The optical block 11 of the optical pickup 10 emits a light beam for irradiating the optical disk 50, an objective lens for focusing the light beam on the recording surface of the optical disk 50, and receives reflected light of the light beam from the optical disk 50. The photodetector includes a circuit for generating a focus error signal FE and a tracking error signal TE based on a light detection signal from the photodetector. The generated focus error signal FE is sent to the focus servo signal generation unit 21 to output the tracking error signal TE.
Are input to the tracking servo signal generator 31.

The focus actuator 12 moves the objective lens of the optical block 11 in a direction perpendicular to the recording surface of the optical disk 50 based on a drive signal input from the focus drive amplifier 24. The tracking actuator 13 moves the objective lens of the optical block 11 in the system direction of the optical disk 50 based on a drive signal input from the tracking drive amplifier 34.

The focus servo signal generator 21 keeps a predetermined distance between the recording surface of the optical disk 50 and the objective lens of the optical block 11 so that the light beam emitted from the optical block 11 A focusing servo signal is generated on the basis of the focus error signal input from the optical block 11 so as to focus on. The focus servo signal generator 21 amplifies the focus error signal with a preset gain, performs phase compensation, and generates a focus servo signal. The control characteristics such as the gain and the phase are adjusted by the control of the control unit 40 every time the disk is replaced. The generated focus servo signal is output to the focus drive amplifier 24 via the adder 23.

The disturbance applying unit 22 applies a predetermined signal to a focus servo signal to detect an optimum focusing point during a focus bias adjustment operation, for example, after disc replacement, and forcibly changes the focus bias. Let it. The adder 23 adds the focus servo signal output from the focus servo signal generation unit 21 and the disturbance signal output from the disturbance application unit 22, and outputs the result to the focus drive amplifier 24. During a normal operation, since a substantially effective signal is not input from the disturbance applying section 22, the adder 23 outputs the output of the focus servo signal generating section 21 as it is to the focus drive amplifier 24.
Output to The focus drive amplifier 24 amplifies the focus servo signal input from the adder 23 to generate a signal for actually driving the actuator, and applies the signal to the focus actuator 12 of the optical pickup 10.

The tracking servo signal generator 31 generates a tracking servo signal based on the tracking error signal TE input from the optical block 11 so that the objective lens of the optical block 11 appropriately follows a desired track. . The tracking servo signal generator 31 amplifies the tracking error signal with a preset gain, performs phase compensation, and generates a tracking servo signal. The control characteristics such as the gain and the phase are set by the control unit 40, but different values are set in the normal operation and the focus bias adjustment operation. During normal operation, a predetermined initial value is set by the control unit 40 every time the disk is replaced, and a value adjusted by an adjustment operation described later is set. Further, at the time of the focus bias adjustment operation, a predetermined gain which is sufficiently larger than at the time of the normal operation,
Further, a predetermined phase compensation characteristic for stabilizing the system at the gain is set by the control unit 40. The generated tracking servo signal is output to the tracking drive amplifier 34 via the adder 33.

The disturbance applying unit 32 applies a predetermined signal to the tracking servo signal in order to forcibly change the tracking state and detect an optimum level of the tracking error signal during a tracking servo gain adjustment operation such as after disc replacement. Apply. The adder 33 adds the tracking servo signal output from the tracking servo signal generation unit 31 and the disturbance signal output from the disturbance application unit 32, and outputs the result to the tracking drive amplifier. During a normal operation, since a substantially effective signal is not input from the disturbance applying unit 32, the adder 33 outputs the output of the tracking servo signal generating unit 31 to the tracking drive amplifier 34 as it is. The tracking drive amplifier 34 amplifies the tracking servo signal input from the adder 33 to generate a signal for actually driving the actuator, and applies the signal to the tracking actuator 13 of the optical pickup 10.

The control section 40 controls each section of the optical disc apparatus 1 so that focus servo and tracking servo can be appropriately performed. In particular, the control unit 40 performs an operation related to adjustment of control characteristics in the focus servo signal generation unit 21 and the tracking servo signal generation unit 31. That is, at the time of disc replacement, first, a predetermined initial control characteristic value is set in the focus servo signal generation unit 21, and the control characteristic is adjusted to an appropriate value while the focus state is changed by the disturbance application unit 22. At this time, the tracking servo signal generator 31 is set with a predetermined gain that is sufficiently larger than the gain during the normal operation and a phase compensation characteristic for stabilizing the servo system accordingly. When the focus bias adjustment is completed,
This time, a predetermined initial control characteristic value is set in the tracking servo signal generating unit 31, and the disturbance error applying unit 32 changes the tracking error signal to adjust the control characteristic to an appropriate value.

Next, the operation of the optical disk device 1 will be described. First, when starting to access the optical disk in a substantially new state, such as when replacing the disk, the focus bias is first adjusted. In the adjustment of the focus bias, the control unit 40 first sets the tracking servo signal generation unit 31 with a predetermined gain sufficiently larger than the gain in the normal operation and the phase compensation characteristic for stabilizing the servo system accordingly, and sets the tracking. Keep it high. Then, the focus servo signal generation unit 21
A predetermined initial control characteristic value is set, a predetermined signal is applied from the disturbance applying unit 22 to forcibly move the objective lens in the focus direction, and a state in which focusing is appropriate is detected. Then, the gain and the phase of the focus servo signal generator 21 are adjusted to control characteristics such that the appropriate focusing state is maintained as a steady state.

After the adjustment of the focus bias is completed,
Next, the tracking servo gain is adjusted. At this time, a predetermined initial control characteristic value is set in the tracking servo signal generation unit 31, a predetermined signal is applied from the disturbance application unit 32 of the tracking servo unit 30, and the objective lens is forcibly vibrated in the tracking direction, and the tracking servo signal is generated. Is adjusted so that the gain of becomes an appropriate value.

When these adjustment processes are completed, normal operation starts. At the time of normal operation, a focus servo signal is generated by the focus servo signal generation unit 21 based on the adjusted gain and phase characteristics based on the focus error signal FE detected by the optical block 11, and the focus servo signal is generated via the focus drive amplifier 24. Applied to the actuator 12, appropriate focusing is performed. The tracking error signal TE detected by the optical block 11 is input to a tracking servo signal generation unit 31, and a tracking servo signal is generated based on the adjusted gain and phase characteristics.
3 and appropriate tracking is performed.

As described above, in the optical disc device 1 of the present embodiment, when adjusting the focus bias, a gain that is sufficiently higher than that in the normal operation is set to the tracking servo unit 30 and this gain is increased. Thus, the position of the phase compensation is changed to an appropriate position. As a result, the tracking stabilization is enhanced, so even if the focus is deviated and the tracking error signal cannot be detected properly by forcibly moving the objective lens when adjusting the focus bias, This makes it possible to reduce the possibility of the focus bias and appropriately adjust the focus bias. In particular, even for an eccentric disk that is easily off-tracked, the focus bias can be appropriately adjusted without tracking off-tracking. Further, since these gain changes can be easily performed by the control unit 40 including, for example, a microcomputer, the present invention can be easily implemented with a simple circuit.

The present invention is not limited to the present embodiment, and various modifications are possible. For example, in the present embodiment, the gain of the tracking servo is increased at the time of adjusting the focus bias after replacing the disk. However, the present invention is not limited to only at the time of replacing the disk. At times, such control may be performed. The control is not limited to the adjustment of the focus bias, and such control may be performed for an adjustment operation of an arbitrary parameter.

[0024]

According to the present invention, in the optical disc apparatus, even before the tracking servo gain is adjusted,
Adjustment of other parameters such as adjustment of focus bias can be performed appropriately without off-tracking.

[Brief description of the drawings]

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

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk apparatus, 10 ... Optical pickup, 11 ... Optical block, 12 ... Focus actuator, 13 ... Tracking actuator, 20 ... Focus servo part, 21 ... Focus servo signal generation part, 22 ... Disturbance applying part, 23 ... Adder, 24: focus drive amplifier, 30: tracking servo section, 31: tracking servo signal generation section, 32: disturbance applying section, 33: adder,
34: tracking drive amplifier, 40: control unit, 5
0 ... optical disk

Claims (4)

[Claims] An optical pickup detects reflected light of a light beam applied to an optical disk, and based on the reflected light,
Tracking error signal detection means for detecting a tracking error signal; tracking servo signal generation means for amplifying the detected tracking error signal with a predetermined gain and performing phase compensation to generate a tracking servo signal; A tracking actuator driving means for driving a tracking actuator based on the tracking servo signal, and an operation for adjusting a predetermined parameter for defining a predetermined operation of the optical pickup; A tracking circuit for changing a gain to a predetermined value large enough to make it difficult to perform off-tracking than in a normal operation, and for changing a phase of the tracking servo signal so as to substantially increase tracking stabilization by changing the gain. Characteristic changing means, and when the tracking is performed based on the tracking servo signal generated with reference to the changed gain and phase, the predetermined parameter is changed, and the predetermined operation is appropriately performed. An optical disk device having parameter adjustment means for adjusting the predetermined parameter to an appropriate state by detecting the state of the optical disk. 2. The method according to claim 1, wherein the predetermined parameter is a parameter for determining a focus bias applied to the optical pickup so that focusing can be performed appropriately. The gain and phase are changed so that the settling property of tracking is enhanced, and the parameter adjusting unit detects the focusing state by substantially changing the focus bias when the settling property of tracking is increased. 2. The optical disc apparatus according to claim 1, wherein the focus bias in a state where the focusing is properly performed is set as a focus bias in a normal operation. 3. A method for adjusting a predetermined parameter defining a predetermined operation of an optical pickup in an optical disk device, wherein a gain of a tracking servo is adjusted when a substantially new optical disk is started to be accessed. The gain is changed to a predetermined gain that is larger than the gain at the time, and it is difficult to perform off-tracking than during the normal operation, tracking is performed based on the changed gain, and the parameter is changed while the tracking is performed. Detecting a state in which the predetermined operation performed based on the changed parameter is substantially optimized, and setting the detected parameter at the time of the optimum operation as the parameter used at the time of the normal operation. Adjustment method for optical disk device. 4. The method according to claim 1, wherein the predetermined parameter is a parameter for substantially setting a focus bias, and when starting access to a substantially new optical disc, the gain of the tracking servo is set to be smaller than the gain during normal operation. The tracking gain is changed to a predetermined gain that makes it harder to perform off-tracking than in the normal operation, and tracking is performed based on the changed gain. During the tracking, the focus bias is substantially changed. 4. A state where the focusing is substantially optimized is detected, and the focus bias value in a state where the detected optimum focusing can be performed is set as a focus bias value in a normal operation. The adjusting method of the optical disk device described in the above.