JP2002319148A - Actuator brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator brake device with which a rapid focus control is restarted even when a focus is deviated by vibration. SOLUTION: An existence/nonexistence discrimination device 7 of a position- deciding signal discriminates that the focus deviation occurs at the point of time when the position-deciding signal is not detected for a prescribed time. When a command on the basis of the discrimination is given, a focus brake generator 12 generates a brake pulse corresponding to the driving direction of an actuator (not shown in the figure) in which an optical pickup 3 is built in, which is detected with a detector 11 of driving direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an actuator brake device for focus control in an optical disk device.

[0002]

2. Description of the Related Art An optical disk apparatus for recording / reproducing an optical disk such as a CD or a DVD performs an operation of reading data spirally arranged on a rotating optical disk with a laser beam output from an optical pickup. The control of the optical pickup includes focus control for focusing a laser beam output from the optical pickup on data on a track and tracking control for positioning the optical pickup on a predetermined track on an optical disk.

The focus control is a control for positioning an objective lens included in an optical pickup so that a laser beam is focused on an optical disk. An actuator for moving the objective lens in the optical axis direction is replaced with an actuator for the actuator. The driving is controlled by using the driving position information. That is, the amount of deviation from the in-focus state is obtained as drive position information of the actuator, a positioning signal for positioning the actuator is generated from the amount of deviation, and the in-focus state is maintained by controlling the drive of the actuator. .

[0004] As a method of obtaining the amount of deviation from the in-focus state, an astigmatism method is generally used. Hereinafter, focus control using the astigmatism method will be described in detail.
In the case of using the astigmatism method, the laser beam output from the laser diode and reflected back to the optical disk is input to a four-divided detector (see FIG. 17) through a condenser lens or a kamaboko-shaped cylindrical lens. Construct an optical pickup.

The input of the laser beam to the quadrant detector is
Due to the astigmatism phenomenon that occurs when the light passes through the condenser lens and the cylindrical lens, the light beam becomes a perfect circle in the focused state and an elliptical light in the out-of-focus state. Therefore, the amount of deviation of the actuator from the in-focus state is obtained by adding the outputs of the diagonal lines of the quadrant detector and taking the difference between the addition results. That is, a signal proportional to (A + C)-(B + D) is generated based on the photocurrent output from the quadrant detector, and this is used as a positioning signal for the actuator (see FIG. 17). The output of this positioning signal is 0 in the focused state, and becomes an output proportional to the shift amount when the focus is out of focus.
Is performed (see FIG. 18).

However, in this method, if the focus is too deviated, the laser beam will not be focused on the quadrant detector, and a normal positioning signal will not be detected. Therefore, when performing focus control, the actuator must be driven by open control to move the objective lens to a position where a normal positioning signal is detected.

Hereinafter, a conventional focus control device will be described. FIG. 19 is a block diagram showing a configuration (main part) of a focus control device in a conventional optical disk device, wherein 1 is an optical disk, 2 is a spindle motor, 3 is an optical pickup, and 4 is a head amplifier for positioning signals. A positioning signal for positioning an actuator (not shown) built in the pickup 3 is generated.
5 is a servo filter calculator, 6 is an optical pickup drive driver for driving the actuator, 7 is a positioning signal presence / absence determiner, 8 is a triangular wave generator, and 9 is servo ON / OFF.
An OFF switch 10 is a driver output changeover switch. However, the actuator is for driving an objective lens (not shown) built in the optical pickup 3 in the optical axis direction.

A track on which data is spirally written is provided on the optical disk 1. The data on the track is read by a laser beam output from the optical pickup 3. To read the data normally, the optical pickup is used. It is necessary to perform focus control for focusing the laser light from No. 3 on the data. That is, it is necessary to move the objective lens to the focal point by the actuator. Note that the focal point is the position of the objective lens when the focal point of the laser beam is focused on the data on the track.

However, since the range of generation of the positioning signal for positioning the actuator is smaller than the movable range of the actuator, before performing the focus control, the objective lens is moved to a position near the focal point where the positioning signal is normally generated. There must be.

A focus pull-in process, which is a processing operation for enabling the optical disc device to perform focus control, will be described below. First, in the initial state, the servo ON / OFF switch 9 is set to OFF, and the driver output changeover switch 10 is set to the triangular wave generator 8 side. When the focus control start command is input to the focus control device, a triangular wave for driving the actuator is generated from the triangular wave generator 8. While the actuator is being driven, the positioning signal presence / absence determiner 7 constantly monitors the positioning signal generated by the positioning signal head amplifier 4. When the generation of the positioning signal is detected by the positioning signal presence / absence determining unit 7, the servo ON / OFF switch 9 is turned ON, and the driver output changeover switch 10 is set to the servo filter computing unit 5 side to start the focus control. If the positioning signal is not detected even when the actuator moves to the maximum movable position, the polarity of the output from the triangular wave generator 8 is inverted and the output is driven in the opposite direction, and the focus pull-in process is attempted again. The maximum drive current level of the actuator must be determined by the objective lens at the position where the positioning signal is detected in consideration of the positional relationship between the optical pickup 3 and the optical disk 1 (that is, the positional relationship between the objective lens and the optical disk 1). It is necessary to decide in advance so that it will pass.

When vibration or the like occurs during focus control and the objective lens moves out of the positioning signal generation range, the laser beam is defocused and no positioning signal is generated, and the current position of the actuator is changed. I can't understand and can't do focus control.

As a countermeasure against this, utilizing the relationship that the positioning signal is not generated when the laser beam is out of focus, when the positioning signal is no longer detected by the positioning signal presence / absence determining unit 7, the driver output changeover switch is used. 10 is set to the triangular wave generator 8 side, the servo ON / OFF switch 9 is turned off, and a triangular wave is output from the triangular wave generator 8 to the optical pickup 3 to perform focus pull-in processing.

However, if the laser beam is defocused during the focus control, as shown in FIG. 20, the vibration of the optical pickup 3 (ie, the objective lens) immediately after the defocusing is stopped, and then the operation of the actuator is stopped. There is a problem that it takes time to restart the focus control because the drive starts, and if the initial drive direction by the triangular wave is the same as the focus position direction, the maximum movable After the objective lens is moved to the position, the polarity of the triangular wave is inverted and the focus pull-in process is performed again, which causes a problem that the time required for the focus pull-in process is further increased.

As another countermeasure against the occurrence of vibration or the like during the focus control and the inability to perform the focus control, it is conceivable to prevent the laser beam from being out of focus. Nothing has been embodied, and a device for preventing such laser light from being out of focus is desired.

[0015]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a positioning signal presence / absence determining means for determining the presence / absence of a positioning signal, a driving direction detecting means for monitoring the driving direction of an actuator, By providing a brake pulse generating means for generating a brake pulse that is a drive output in a direction opposite to the drive direction, the focus pull-in process can be completed quickly even when the focus is lost due to the occurrence of vibration or the like. The purpose of the present invention is to provide an actuator brake device that performs the following.

Also, the present invention monitors whether the envelope signal of the data signal from the optical disk is below a predetermined level, and the laser beam is out of focus and the positioning signal is no longer detected. It is an object of the present invention to provide an actuator brake device capable of determining whether the value has become zero due to focusing of a laser beam.

Further, according to the present invention, the vibration of the actuator (objective lens) is converged by generating a brake pulse when the positioning signal reaches a predetermined level,
An object of the present invention is to provide an actuator brake device that makes it difficult to lose focus.

Further, according to the present invention, when the positioning signal is higher than a predetermined level and the envelope signal of the data signal from the optical disk is lower than a predetermined level or the slope of the envelope signal is lower than the predetermined slope, the brake pulse generating means By converging the vibration of the actuator (objective lens) by generating a brake pulse from
An object of the present invention is to provide an actuator brake device that makes it difficult to lose focus.

[0019]

According to a first aspect of the present invention, there is provided an actuator brake device for moving an objective lens in an optical axis direction so that a laser beam is focused on an optical disk, and positioning the actuator. Positioning signal generating means for generating a positioning signal for driving the actuator from driving position information of the actuator, driving direction detecting means for detecting a driving direction of the actuator from the positioning signal, and presence or absence of a positioning signal for determining the presence or absence of the positioning signal Determining means, and brake pulse generating means for generating a brake pulse corresponding to the driving direction of the actuator immediately before the positioning signal is no longer detected, from the time when the positioning signal is determined to be absent to the time when the positioning signal is determined to be present; It is characterized by having.

The actuator brake device according to a second aspect of the present invention is the actuator brake device according to the first aspect, wherein the positioning signal presence / absence determining means determines that the positioning signal is not detected when the positioning signal is not detected for a predetermined time. It is characterized in that it is determined, and that it is determined to be present when it is detected thereafter.

An actuator brake device according to a third aspect of the present invention is the actuator brake device according to the second aspect, wherein a drive speed detecting means for detecting a drive speed of the actuator from the positioning signal; And a gain adjusting means for adjusting the gain of the brake pulse accordingly.

An actuator brake device according to a fourth aspect of the present invention is the actuator brake device according to the first aspect, further comprising an envelope signal generating means for generating an envelope signal of a data signal representing all data read from the optical disk. The positioning signal presence / absence determining means includes an envelope signal monitoring means for monitoring the envelope signal, and determines that there is no signal when the envelope signal when the positioning signal is no longer detected is below a predetermined level. When the envelope signal when the positioning signal is detected exceeds the predetermined level, it is determined that the envelope signal is present.

An actuator brake device according to a fifth aspect of the present invention is the actuator brake device according to the fourth aspect, wherein an envelope signal inclination detecting means for detecting an inclination of the envelope signal, and an envelope signal inclination detecting means for detecting an inclination of the envelope signal. And a gain adjusting means for adjusting the gain of the brake pulse.

According to a sixth aspect of the present invention, there is provided the actuator brake device according to the first to fifth aspects, wherein the triangular wave generating means for outputting a triangular wave for driving and controlling the actuator, and the brake pulse. Switching means for switching the output source to the actuator from the brake pulse generating means to the triangular wave generating means when the positioning signal is not detected by the positioning signal presence detecting means even if the generating means generates the brake pulse for a predetermined time; And characterized in that:

According to a seventh aspect of the present invention, there is provided an actuator brake device comprising: an actuator for moving an objective lens in an optical axis direction so that a laser beam is focused on an optical disc; and a positioning signal for positioning the actuator. Positioning signal generating means for generating from the driving position information of the actuator, positioning signal inclination detecting means for detecting a peak state of the positioning signal from the inclination of the positioning signal, and driving for detecting the driving direction of the actuator from the positioning signal Direction detection means, positioning signal validity / invalidity determination means for determining whether the positioning signal is valid or invalid, and from the time when the positioning signal is determined to be invalid to the time when the positioning signal reaches a peak, it is determined to be invalid. Immediately before the actuator moves according to the drive direction of the actuator. Characterized by comprising a brake pulse generating means for generating a Kiparusu.

An actuator brake device according to an eighth aspect of the present invention is the actuator brake device according to the seventh aspect, wherein the positioning signal valid / invalid determining means includes a positioning signal monitoring means for monitoring the positioning signal,
When the positioning signal is equal to or higher than a predetermined level, invalidation is determined.

An actuator brake device according to a ninth aspect of the present invention is the actuator brake device according to the eighth aspect, wherein the drive speed detecting means for detecting the drive speed of the actuator from the positioning signal; And a gain adjusting means for adjusting the gain of the brake pulse accordingly.

An actuator brake device according to a tenth aspect of the present invention is the actuator brake device according to the seventh aspect, further comprising an envelope signal generating means for generating an envelope signal of a data signal representing all data read from the optical disk. The positioning signal valid / invalid determining means includes a positioning signal monitoring means for monitoring the positioning signal, and an envelope signal monitoring means for monitoring the envelope signal, wherein the positioning signal is equal to or higher than a predetermined level, and When the envelope signal is lower than a predetermined level, the envelope signal is determined to be invalid.

An actuator brake device according to an eleventh aspect of the present invention is the actuator brake device according to the seventh aspect, further comprising an envelope signal generating means for generating an envelope signal of a data signal representing all data read from the optical disk. The positioning signal validity / invalidity determination means includes a positioning signal monitoring means for monitoring the level of the positioning signal, and an envelope signal gradient for detecting a gradient of the envelope signal and comparing the gradient of the envelope signal with a predetermined gradient. Comparing means for determining that the positioning signal is equal to or higher than a predetermined level and that the slope of the envelope signal is lower than a predetermined slope.

An actuator brake device according to a twelfth aspect of the present invention is the actuator brake device according to the tenth and eleventh aspects, wherein the envelope signal inclination detecting means for detecting the inclination of the envelope signal; and the inclination of the envelope signal. And a gain adjusting means for adjusting the gain of the brake pulse in accordance with

According to the present invention, even if the laser beam is defocused due to vibration or the like during focus control, the objective lens is moved in the optical axis direction so that the objective lens returns to the focused position. By outputting a brake pulse to the actuator, the time required for resuming the focus control can be significantly reduced as compared with the related art. In addition, even when the focus is completely deviated due to large vibration and the process shifts to the conventional focus pull-in process using a triangular wave, the vibration of the optical pickup is suppressed to some extent because the brake pulse is output, The vibration convergence waiting time can be shortened, and the time required until the focus control is restarted can be made much faster than in the past.

Also, when the optical pickup is almost out of focus due to vibration or the like, a brake pulse is output so that the optical pickup returns to the original position.
Stronger earthquake and shock resistance.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. The first to third embodiments relate to the focus pull-in process when the laser beam is out of focus due to vibration or the like, and the fourth to seventh embodiments are active before the laser beam is out of focus. 1 is an embodiment relating to a processing operation for generating a brake pulse in FIG.

Embodiment 1 Hereinafter, Embodiment 1 will be described with reference to the drawings. Note that members having the same configuration as the above-described conventional example (FIG. 19) are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 is a block diagram showing a configuration (main part) of an actuator brake device in a focus control device of an optical disk device according to the first embodiment, wherein 1 is an optical disk, 2 is a spindle motor, and 3 is an optical pickup. In addition, an objective lens, an actuator for moving the objective lens in the optical axis direction, a four-segment detector, and the like are incorporated. Reference numeral 4 denotes a positioning signal head amplifier serving as a positioning signal generation unit, 5 denotes a servo filter calculator, 6 denotes an optical pickup drive driver, 7 denotes a positioning signal presence / absence determination unit (positioning signal presence / absence determination unit), and 8 denotes a triangular wave generator (triangular wave). Generating means), 9 is a servo ON / OFF switch, 10 is a driver output changeover switch, 11 is a driving direction detector (driving direction detecting means) for detecting a driving direction of an actuator (not shown) from a positioning signal, and 12 is an actuator. A focus brake generator which is a brake pulse generating means for generating a brake pulse corresponding to the driving direction of the motor;
This is a triangular wave switch.

The focus pull-in process in the optical disk device will be described below. In the initial state, the servo ON / OFF switch 9 is set to OFF, the driver output changeover switch 10 is set to the focus brake / triangular wave changeover switch 14, and the focus brake / triangle wave changeover switch 14 is set to the triangular wave generator 8 side. When a focus control start command is given to the apparatus, an output (triangular wave) for driving an objective lens (not shown) in the optical axis direction is generated from the triangular wave generator 8. The actuator is driven according to this output, and operates to move the objective lens closer to or away from the optical disc 1. The positioning signal presence / absence determiner 7 constantly monitors the positioning signal generated by the positioning signal head amplifier 4 while the actuator drives the objective lens.
Detects the positioning signal, the apparatus sets the driver output changeover switch 10 to the servo filter computing unit 5 side, turns on the servo ON / OFF switch 9, and starts the focus control.

During the focus control, the positioning signal presence / absence determining unit 7 and the driving direction detector 11 constantly monitor the positioning signal. When the value reaches 0 after reaching, and when the state of 0 continues for a certain period of time, it is determined that there is no positioning signal. That is, it is determined that the laser beam is out of focus and the focus control cannot be performed. The driving direction detector 11 monitors the driving direction of the actuator based on the polarity of the positioning signal, and determines whether the positioning signal reaches the positive peak and defocuses the laser light, or reaches the negative peak and defocuses the laser light. To determine if it has come off. That is, it is determined whether the objective lens is too close to the optical disc 1 and the laser beam is out of focus or too far away and out of focus. Since the peak position and the 0 position of the positioning signal may vary, the determination is made with a certain width.

When the focus of the laser beam is out of focus due to vibration or the like during the focus control (when the positioning signal presence / absence determination unit 7 determines "absence"), the servo ON / OF is performed.
Turn off the F switch 9 and set the driver output switch 1
0 is set to the focus brake / triangular wave switch 14 and the focus brake / triangular wave switch 14 is set to the focus brake generator 12. Information is input to the focus brake generator 12.

As shown in FIG. 2, the focus brake generator 12 outputs a brake pulse, which is a drive output in a direction opposite to the current drive direction of the actuator, in accordance with these instructions, and outputs the brake pulse to the optical pickup 3 (that is, the objective lens). )
In the vertical direction (optical axis direction) quickly converges. During output of brake pulse, positioning signal presence / absence judgment device 7
Constantly monitors the positioning signal, and outputs a command to terminate the brake pulse output to the focus brake generator 12 when the positioning signal is detected. At the same time, the apparatus turns the driver output changeover switch 10 to the servo filter computing unit 5 side and turns on the servo ON / OFF switch 9 to restart the focus control. It is assumed that the gain of the brake pulse is set in advance according to the characteristics of the optical pickup 3.

Since the brake pulse is output by the open control, when the brake pulse is output for a long time, the actuator continues to be driven even if the positioning signal is generated, and the laser beam may be defocused in the opposite direction. is there.
That is, there is a possibility that the objective lens that has been too close to the optical disk has passed the focal point and has gone too far. Further, when the focus is largely out of focus, it may take a long time to perform the focus pull-in process with the brake pulse output. As a countermeasure against this, the device uses a timer 1
3 is started, and if the positioning signal is not detected even when the timer 13 reaches a predetermined time, the brake pulse output is interrupted and the process shifts to the conventional focus pull-in process using a triangular wave. That is, the servo ON / OFF switch 9 serving as the switching means is turned off, the driver output changeover switch 10 is switched to the focus brake / triangular wave switch 14, the focus brake / triangle wave switch 14 is switched to the triangular wave generator 8, and the triangular wave is output. This is given to the pickup drive driver 6. The height of the brake pulse and the time of the timer need to be set in advance according to the characteristics of the optical pickup 3.

Embodiment 2 Hereinafter, Embodiment 2 will be described with reference to the drawings. Note that members having the same configurations as those of the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 3 is a block diagram showing a configuration (main parts) of an actuator brake device in a focus control device of an optical disk device according to a second embodiment, wherein 1 is an optical disk, 2 is a spindle motor, 3 is an optical pickup, 4 is a positioning signal head amplifier, 5 is a servo filter calculator, 6 is an optical pickup drive driver, 7 is a positioning signal presence / absence determiner, 8 is a triangular wave generator, 9 is a servo ON / OFF switch, and 10 is a driver output switch. , 11 is a drive direction detector, 12 is a focus brake generator, 13 is a timer, and 14 is a focus brake /
A triangular wave switch 15 is a driving speed detector (driving speed detecting means) for detecting a driving speed of an actuator (not shown) built in the optical pickup 3 from a positioning signal, 16
Reference numeral denotes a focus brake gain adjuster as gain adjusting means for adjusting the gain of the brake pulse in accordance with the speed information from the drive speed detector 15. However, the actuator is an objective lens (not shown) built in the optical pickup 3.
Is driven in the optical axis direction.

Hereinafter, focus pull-in processing in this apparatus will be described. The focus pull-in process in the initial state is the same as in the first embodiment, and a description thereof will not be repeated.

The difference between the second embodiment and the first embodiment is that the drive speed detector 15 as well as the positioning signal presence / absence determination unit 7 and the drive direction detector 11 during the focus control. The point is that the positioning signal is constantly monitored. Specifically, the driving speed detector 15 detects the inclination of the positioning signal, that is, the moving speed of the objective lens.

When the focus of the laser beam is out of focus due to vibration or the like during the focus control (when the positioning signal presence / absence determination unit 7 determines "absence"), the servo ON / OF is performed.
Turn off the F switch 9 and set the driver output switch 1
0 is set to the focus brake / triangular wave switch 14, the focus brake / triangular wave switch 14 is set to the focus brake generator 12, a brake start command is issued from the positioning signal presence / absence judging device 7, and the brake direction is sent from the drive direction detector 11. Information is input to the focus brake generator 12, and speed information immediately before the positioning signal is no longer detected from the drive speed detector 15 is input to the focus brake gain adjuster 16. That is, the focus brake generator 12 inputs a brake pulse according to these instructions to the focus brake gain adjuster 16, and the focus brake gain adjuster 16 inputs a predetermined gain amount according to the characteristics of the optical pickup 3. Based on the obtained speed information, the gain is adjusted so as to be larger than the set gain amount when the speed of the objective lens is fast, and to be smaller when the speed of the objective lens is slow (see FIG. 4).

During the output of the brake pulse, similarly to the first embodiment, the positioning signal presence / absence determining unit 7 constantly monitors the positioning signal. When the positioning signal is detected, the brake pulse output to the focus brake generator 12 is terminated. The command to perform is output. Then, at the same time, the device turns the driver output changeover switch 10 to the servo filter calculator 5 side and turns the servo ON / OFF switch 9 ON, and resumes the focus control.

Note that, for the same reason as in the first embodiment, the device starts the timer 13 from the time when the brake pulse output is started, and the positioning signal is not detected even when the timer 13 reaches a predetermined time. In such a case, the brake pulse output is interrupted, and the process shifts to a conventional focus pull-in process using a triangular wave.

Embodiment 3 Hereinafter, Embodiment 3 will be described with reference to the drawings. Note that members having the same configurations as those of the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 5 is a block diagram showing a configuration (main parts) of an actuator brake device in a focus control device of an optical disk device according to the third embodiment, wherein 1 is an optical disk, 2 is a spindle motor, 3 is an optical pickup, 4 is a positioning signal head amplifier, 5 is a servo filter calculator, 6 is an optical pickup drive driver, 7 is a positioning signal presence / absence determiner, 8 is a triangular wave generator, 9 is a servo ON / OFF switch, and 10 is a driver output switch. , 11 is a drive direction detector, 12 is a focus brake generator, 13 is a timer, and 14 is a focus brake /
A triangular wave changeover switch 17 is a head amplifier for an envelope signal which is an envelope signal generating means for generating an envelope signal of a data signal representing all data read from the optical disk 1, and 18 is an envelope signal monitoring means built in the positioning signal presence / absence judging device 7. Is an envelope signal level comparator.

Hereinafter, focus pull-in processing in the apparatus will be described. The focus pull-in process in the initial state is the same as in the first embodiment, and a description thereof will not be repeated.

The difference between the third embodiment and the first embodiment is that the positioning signal presence / absence determining unit 7 and the driving direction detector 11 constantly monitor the positioning signal while performing the focus control. The point is that the envelope signal level comparator 18 built in the positioning signal presence / absence determination unit 7 constantly monitors the envelope signal generated by the envelope signal head amplifier 17.

When the focus control is performed and the laser beam is in a focused state, the level of the positioning signal continues to be infinitely close to 0. Therefore, the level of the positioning signal becomes 0 due to the defocus of the laser beam. Must be distinguished from a state where no positioning signal is generated. Therefore, in the third embodiment, it is determined in which state the focal point of the laser light is in consideration of a signal indicating the total amount of light received by a four-divided detector (not shown) of the optical pickup 3. . Specifically, since the total amount of light represents the data signal read from the optical disc 1, an envelope signal representing the envelope of this data signal is generated by the envelope signal head amplifier 17 as shown in FIG. The determination is made by comparing the level of the envelope signal with a predetermined level set in advance by the envelope signal level comparator 18.

In the apparatus, the positioning signal and the envelope signal are monitored by the positioning signal presence / absence determining unit 7 and the envelope signal level comparator 18 built in the determining unit 7 during the focus control. When the envelope signal when the level reaches 0 after reaching the peak is equal to or lower than the predetermined level, it is determined that the laser light is out of focus and the focus control cannot be performed (that is, the laser light is out of focus). The positioning signal is judged to be nothing). This is because when the laser light is out of focus, the envelope signal has a low level output. Conversely, the predetermined level of the envelope signal needs to be set according to the characteristics of the optical pickup 3 so that the above determination can be made. In addition, the driving direction detector 11 determines the position of the optical pickup 3 based on the polarity of the positioning signal.
Monitors the driving direction of the actuator (not shown) of the laser beam, and determines whether the positioning signal has reached the positive peak and defocused the laser beam, or has reached the negative peak and defocused the laser beam. Deciding. Since the peak position and the 0 position of the positioning signal may vary, the determination is performed with a certain width.

When the focus of the laser beam is out of focus due to vibration or the like during the focus control (when the positioning signal presence / absence determination unit 7 determines "absence"), the servo is turned on / off.
The OFF switch 9 is turned OFF, and the driver output changeover switch 10 is set to the focus brake / triangular wave changeover switch 14.
On the other hand, the focus brake / triangular wave switch 14 is set to the focus brake generator 12 side, and a brake start command is input from the positioning signal presence / absence determiner 7 and brake direction information is input to the focus brake generator 12 from the drive direction detector 11. I do.

The focus brake generator 12 outputs a brake pulse in accordance with these instructions so that the vertical (optical axis) fluctuation of the optical pickup 3 (that is, the objective lens) quickly converges. During brake pulse output,
The positioning signal presence / absence determining unit 7 and the envelope signal level comparator 18 constantly monitor the positioning signal and the envelope signal. When the envelope signal when the positioning signal is detected exceeds a predetermined level, the focus brake generator 12 To output the brake pulse output command. At the same time, the device sets the driver output changeover switch 10 to the servo filter calculator 5 side,
The servo ON / OFF switch 9 is turned ON to restart the focus control (see FIG. 7).

Note that the head amplifier 1 for the envelope signal
7 is added between the focus brake generator 12 and the focus brake generator 12, and a gain adjuster (gain adjusting means) for adjusting the gain of the brake pulse according to the slope of the envelope signal is added to the focus brake generator. With this configuration, the focus control can be quickly resumed.

Further, for the same reason as in the first embodiment, the device activates the timer 13 from the time when the brake pulse output is started, and the positioning signal is not detected even when the timer 13 reaches a predetermined time. In such a case, the brake pulse output is interrupted, and the process shifts to a conventional focus pull-in process using a triangular wave.

Embodiment 4 Hereinafter, Embodiment 4 will be described with reference to the drawings. Note that members having the same configurations as those of the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 8 is a block diagram showing a configuration (main parts) of an actuator brake device in a focus control device of an optical disk device according to a fourth embodiment, wherein 1 is an optical disk, 2 is a spindle motor, 3 is an optical pickup, 4 is a head amplifier for positioning signals, 5 is a servo filter calculator, 6 is an optical pickup drive driver, 8 is a triangular wave generator, 9 is a servo ON / OFF switch, 10 is a driver output changeover switch, 11 is a drive direction detector, 1
2 is a focus brake generator, 14 is a focus brake / triangular wave switch, 19 is a positioning signal validity / invalidity judging device (positioning signal validity / invalidity judging means), and 20 is a positioning signal validity / invalidity judging device 19 built-in positioning signal monitoring means. A positioning signal level comparator 21 is a positioning signal inclination detector.

The focus pull-in process in the initial state of the apparatus is the same as that in the first embodiment, and therefore, the description is omitted. The difference between the fourth embodiment and the first embodiment is that the drive direction detector 11 always monitors the positioning signal while performing the focus control, and the positioning signal level comparator 20 and the positioning signal inclination detection. The device 21 also constantly monitors the positioning signal, so that a brake pulse is positively generated before the laser beam is defocused, thereby making it difficult to defocus.

The processing operation for generating a brake pulse while performing focus control will be described below. While the focus control is being performed, the driving direction detector 11 detects the optical pickup 3 based on the polarity of the positioning signal.
The drive direction of a built-in actuator (not shown) is determined. The positioning signal level comparator 20 monitors whether the positioning signal has reached a predetermined level, and determines that the positioning signal is invalid when the positioning signal becomes higher than the predetermined level. This predetermined level is for determining the timing for starting the output of the brake pulse. The positioning signal tilt detector 21 monitors whether or not the tilt of the positioning signal has been reversed, that is, where the speed of the objective lens (not shown) built in the optical pickup 3 in the optical axis direction becomes zero. The device is configured to output a brake pulse from the time when the positioning signal reaches a predetermined level during the focus control to the time when the inclination of the positioning signal is reversed. That is, when the positioning signal becomes higher than a predetermined level, the optical pickup 3
It is determined that vibration has occurred in the (objective lens), and a brake pulse is output so that the vibration immediately converges (see FIG. 9). However, as shown in FIG. 10, it is meaningless if the optical pickup 3 (objective lens) vibrates as it is due to a large vibration despite the output of the brake pulse and the positioning signal reaches the peak position as it is. . Therefore, according to the characteristics of the optical pickup 3, no brake pulse is generated during normal focus control, and when the brake pulse is output, a predetermined level is set so that the positioning signal does not reach the peak position even if a large vibration is applied. Must be set. It is assumed that the gain of the brake pulse is set in advance in accordance with the characteristics of the optical pickup 3.

When the positioning signal level comparator 20 detects that the positioning signal has exceeded a predetermined level during the focus control (when the positioning signal valid / invalid determining unit 19 determines "invalid"), the driver output is switched. The switch 10 is set to the focus brake / triangular wave switch 14, the focus brake / triangular wave switch 14 is set to the focus brake generator 12, and a brake start command is sent from the positioning signal valid / invalid judging device 19 to the drive direction detector 11. The brake direction information is input to the focus brake generator 12. In accordance with these instructions, the focus brake generator 12 outputs a brake pulse in a direction in which the vertical displacement of the objective lens stops.

During the output of the brake pulse, the positioning signal inclination detector 21 constantly monitors the inclination of the positioning signal. If the inclination is reversed, it is regarded that the speed of the objective lens in the optical axis direction has become 0, and the braking is performed. A command to end the pulse output is output to the focus brake generator 12. At the same time, the apparatus sets the driver output changeover switch 10 to the servo filter computing unit 5 side so that focus control can be performed normally.

Embodiment 5 Hereinafter, Embodiment 5 will be described with reference to the drawings. Note that members having the same configuration as the above-described fourth embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 11 is a block diagram showing a configuration (main part) of an actuator brake device in a focus control device of an optical disk device according to a fifth embodiment, wherein 1 is an optical disk, 2 is a spindle motor, 3 is an optical pickup, 4 is a head amplifier for positioning signals, 5 is a servo filter calculator, 6 is an optical pickup drive driver, 8 is a triangular wave generator, 9 is a servo ON / OFF switch, 10 is a driver output changeover switch, 11 is a drive direction detector, 1
2 is a focus brake generator, 14 is a focus brake / triangular wave switch, 15 is a drive speed detector that detects the drive speed of an actuator (not shown) built in the optical pickup 3 from a positioning signal, and 16 is a drive speed detector 15 A focus brake gain adjuster as a gain adjusting means for adjusting the gain of the brake pulse in accordance with the speed information from the controller;
0 is a positioning signal level comparator, and 21 is a positioning signal inclination detector. However, the actuator is for driving an objective lens (not shown) built in the optical pickup 3 in the optical axis direction.

The focus pull-in process in the initial state of the apparatus is the same as that of the fourth embodiment, and the description is omitted. The difference between the fifth embodiment and the fourth embodiment is that, in addition to the drive direction detector 11, the positioning signal level comparator 20, and the positioning signal inclination detector 21, during the focus control. Drive speed detector 15
Therefore, the gain of the brake pulse is adjusted according to the driving speed of the actuator (movement speed of the objective lens) by constantly monitoring the positioning signal. Specifically, the driving speed detector 15 detects the inclination of the positioning signal, that is, the moving speed of the objective lens (not shown).

The processing operation for generating a brake pulse while performing focus control will be described below. As in the fourth embodiment, this device detects that the positioning signal has exceeded a predetermined level during the focus control by the positioning signal level comparator 20 ("invalid" by the positioning signal valid / invalid determiner 19). Is determined), the driver output changeover switch 10 is set to the focus brake / triangular wave changeover switch 14 side, the focus brake / triangular wave changeover switch 14 is set to the focus brake generator 12 side, and the positioning signal valid / invalidity judgment device 19 A brake start command is input from the drive direction detector 11 to input the brake direction information to the focus brake generator 12, and the speed information immediately before the positioning signal is no longer detected is output from the drive speed detector 15 to the focus brake gain adjuster 16. To enter.

The focus brake generator 12 inputs a brake pulse according to these instructions to the focus brake gain adjuster 16. The focus brake gain adjuster 16 adjusts the gain amount of the brake pulse according to the input speed information in the same manner as in the second embodiment (see FIG. 12).

During output of the brake pulse, similarly to the fourth embodiment, the positioning signal tilt detector 21 constantly monitors the tilt of the positioning signal, and when the tilt reverses, the speed of the objective lens in the optical axis direction decreases. Assuming that it has become 0, a command to end the brake pulse output is output to the focus brake generator 12. At the same time, the apparatus sets the driver output changeover switch 10 to the servo filter computing unit 5 side so that focus control can be performed normally.

Embodiment 6 Hereinafter, Embodiment 6 will be described with reference to the drawings. Note that members having the same configuration as the above-described fourth embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 13 is a block diagram showing a configuration (main parts) of an actuator brake device in a focus control device of an optical disk device according to a sixth embodiment, wherein 1 is an optical disk, 2 is a spindle motor, 3 is an optical pickup, 4 is a head amplifier for positioning signals, 5 is a servo filter calculator, 6 is an optical pickup drive driver, 8 is a triangular wave generator, 9 is a servo ON / OFF switch, 10 is a driver output changeover switch, 11 is a drive direction detector, 1
2 is a focus brake generator, 14 is a focus brake / triangular wave switch, 17 is a head amplifier for an envelope signal, 19 is a positioning signal valid / invalid determiner, 2
0 is a positioning signal level comparator as a positioning signal monitoring means built in the positioning signal validity / invalidity judging device 19, 21 is a positioning signal inclination detector, and 22 is an envelope signal as an envelope signal monitoring means built in the positioning signal validity / invalidity judging device 19. It is a level comparator.

The focus pull-in process in the initial state of the apparatus is the same as that of the fourth embodiment, and the description is omitted. The difference between the sixth embodiment and the fourth embodiment is that during the focus control, the driving direction detector 11, the positioning signal level comparator 20, and the positioning signal tilt detector 21 determine the position of the positioning signal. Is constantly monitored, and the envelope signal level comparator 22 constantly monitors the envelope signal generated by the envelope signal head amplifier 17, so that a brake pulse is actively generated before the laser beam is defocused. Is difficult to remove.

Hereinafter, a processing operation for generating a brake pulse while performing focus control will be described.
During the focus control, the positioning signal valid / invalidator 19 monitors the positioning signal and the envelope signal by the positioning signal level comparator 20 and the envelope signal level comparator 22, and the level of the positioning signal becomes a predetermined level. When the envelope signal at the time of reaching the predetermined level or less, the positioning signal is invalidated, and it is determined that the vibration is generated while the focus control is continued. In such a case, in such a case, the driver output changeover switch 10 is set to the focus brake / triangular wave changeover switch 14 side, the focus brake / triangular wave changeover switch 14 is set to the focus brake generator 12 side, and the positioning signal is invalidated. A brake start command is input from the determiner 19, and brake direction information is input from the drive direction detector 11 to the focus brake generator 12.
The focus brake generator 12 follows these instructions,
A brake pulse is output in a direction in which the vertical (optical axis) fluctuation of an objective lens (not shown) built in the optical pickup 3 stops (see FIG. 14). Note that, unlike the third embodiment, the predetermined level of the envelope signal needs to be set according to the characteristics of the optical pickup 3 so that the above determination can be made.

The fourth embodiment is performed during the output of the brake pulse.
Similarly to the above, the inclination of the positioning signal is constantly monitored by the positioning signal inclination detector 21. If the inclination is reversed, it is considered that the speed of the optical pickup 3 (objective lens) in the optical axis direction has become 0, and the focus brake generator 12 To output the brake pulse output command. At the same time, the driver output changeover switch 10 is set to the servo filter computing unit 5 side so that focus control can be performed normally.

As in the third embodiment, an envelope signal inclination detector is added between the envelope signal head amplifier 17 and the focus brake generator 12.
If a configuration is adopted in which a gain adjuster (gain adjusting means) for adjusting the gain of the brake pulse according to the gradient of the envelope signal is added to the focus brake generator, the focus control can be restarted quickly.

Embodiment 7 Hereinafter, Embodiment 7 will be described with reference to the drawings. Note that members having the same configuration as the above-described fourth embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 15 is a block diagram showing a configuration (main parts) of an actuator brake device in a focus control device of an optical disk device according to a seventh embodiment, wherein 1 is an optical disk, 2 is a spindle motor, 3 is an optical pickup, 4 is a head amplifier for positioning signals, 5 is a servo filter calculator, 6 is an optical pickup drive driver, 8 is a triangular wave generator, 9 is a servo ON / OFF switch, 10 is a driver output changeover switch, 11 is a drive direction detector, 1
2 is a focus brake generator, 14 is a focus brake / triangular wave switch, 17 is a head amplifier for an envelope signal, 19 is a positioning signal valid / invalid determiner, 2
0 is a positioning signal level comparator as a positioning signal monitoring means built in the positioning signal validity / invalidity judging device 19, 21 is a positioning signal inclination detector, and 23 is an envelope as an envelope signal inclination comparing means in the positioning signal validity / invalidity judging device 19 It is a signal tilt detector.

The focus pull-in process in the initial state of the optical disk device is the same as that of the fourth embodiment, and the description is omitted. Seventh Embodiment and Fourth Embodiment
Is that while the focus control is being performed, the driving direction detector 11, the positioning signal level comparator 20, and the positioning signal tilt detector 21 always monitor the positioning signal, and the envelope signal tilt detector 23 is to constantly monitor the envelope signal generated by the envelope signal head amplifier 17 to actively generate a brake pulse before the laser beam is defocused, thereby making it difficult to defocus.

Hereinafter, a processing operation for generating a brake pulse while performing focus control will be described.
During the focus control, the driving direction detector 11 determines the moving direction of the objective lens (not shown) built in the optical pickup 3 from the polarity of the positioning signal.
The positioning signal level comparator 20 monitors whether the positioning signal has reached a predetermined level. This predetermined level determines the timing of starting the output of the brake pulse. In addition, the positioning signal inclination detector 21
Monitors whether the inclination of the positioning signal is reversed, that is, where the velocity of the objective lens in the optical axis direction becomes zero. The envelope signal inclination detector 23 detects the inclination of the envelope signal (change rate of the envelope signal) and compares it with a predetermined value. Here, the predetermined value is set to 0.
However, a desired value can be set.

During the focus control, as shown in FIG. 16, when the level of the positioning signal is higher than a predetermined level and the slope of the envelope signal is lower than 0 (point A in FIG. 16), the driver output is output. Changeover switch 10
To the focus brake / triangular wave switch 14
The focus brake / triangular wave switch 14 is set to the focus brake generator 12 side, and a brake start command is input from the positioning signal valid / invalid determiner 19 and brake direction information is input to the focus brake generator 12 from the drive direction detector 11. Focus brake generator 1
In accordance with these instructions, 2 outputs a brake pulse in a direction in which the optical pickup 3 (objective lens) stops shaking in the vertical direction (optical axis direction). That is, when it is determined that the slope of the envelope signal when the level of the positioning signal reaches a predetermined level during the focus control is equal to or less than 0, the focus control is continued and vibration occurs. And the positioning signal is determined to be invalid.

During output of the brake pulse, the positioning signal tilt detector 21 constantly monitors the tilt of the positioning signal. When the tilt of the positioning signal reaches 0, a command is issued to the focus brake generator 12 to output the brake pulse. Is terminated (point B in FIG. 16). In the case of FIG. 16, even at the point B, the slope of the envelope signal is still 0 or less,
In addition, since the level of the positioning signal is equal to or higher than the predetermined level, a brake pulse is further output until the inclination of the positioning signal becomes 0 (point C in FIG. 16). At the point C, the level of the positioning signal is also lower than the predetermined level, and the slope of the envelope signal is 0 or more. At the same time, the driver output changeover switch 10 is set to the servo filter computing unit 5 side so that the focus control is normal. To be able to do it.

As in the third embodiment, an envelope signal tilt detector is added between the envelope signal head amplifier 17 and the focus brake generator 12.
If a configuration is adopted in which a gain adjuster (gain adjusting means) for adjusting the gain of the brake pulse according to the gradient of the envelope signal is added to the focus brake generator, the focus control can be restarted quickly.

[0083]

According to the present invention, even if the laser beam is out of focus due to vibration or the like during focus control,
The time required until the focus control is restarted can be remarkably shortened as compared with the related art. In addition, even when the focus is completely deviated due to the large vibration and the process shifts to the conventional focus pull-in process using a triangular wave,
Because the brake pulse is output, the vibration of the optical pickup is suppressed to some extent, the waiting time for vibration convergence can be shortened, and the time required to resume focus control is made much faster than before. Can be.

Further, even when the focus is likely to be out of focus due to vibration or the like, by actively outputting the brake pulse, the earthquake resistance against vibration and impact can be enhanced.

Therefore, when employed in a portable player, an in-vehicle player or the like, since it is strong against vibration and impact, data can be stably reproduced even under such conditions. Further, in a system in which data is stored in a memory by rotating an optical disk at a high speed, and when laser light is out of focus, data is reproduced using data in the memory so that data reproduction is not interrupted. Since the time during which the focus is out of focus can be reduced, the capacity of the memory can be reduced and the cost of the apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration (main parts) of an actuator brake device in a focus control device of an optical disc device according to a first embodiment of the present invention;

FIGS. 2A and 2B are diagrams showing timing of generation of a brake pulse during focus pull-in processing according to the first embodiment of the present invention, wherein FIG. 2A shows a positioning signal, and FIG. 2B shows focus from an optical pickup driving driver; Diagram showing drive output

FIG. 3 is a block diagram showing a configuration (main parts) of an actuator brake device in a focus control device of an optical disc device according to a second embodiment of the present invention;

4A and 4B are diagrams illustrating gain adjustment of a brake pulse according to the second embodiment of the present invention, in which FIG. 4A illustrates a positioning signal, and FIG. 4B illustrates a focus drive output from an optical pickup driving driver.

FIG. 5 is a block diagram showing a configuration (main parts) of an actuator brake device in a focus control device of an optical disc device according to a third embodiment of the present invention;

FIG. 6 is an explanatory diagram of an envelope signal.

FIGS. 7A and 7B are diagrams showing timings of generation of a brake pulse during focus pull-in processing according to Embodiment 3 of the present invention, wherein FIG. 7A is a diagram showing a positioning signal, FIG. 7B is a diagram showing an envelope signal, 3C is a diagram showing a focus drive output from the optical pickup drive driver.

FIG. 8 is a block diagram showing a configuration (main parts) of an actuator brake device in a focus control device of an optical disc device according to a fourth embodiment of the present invention;

9A and 9B are diagrams showing timings for generating a brake pulse during focus control according to Embodiment 4 of the present invention, wherein FIG. 9A shows a positioning signal, and FIG. 9B shows a focus drive from an optical pickup driving driver. Diagram showing output

FIG. 10 is an explanatory diagram for determining a predetermined level of a positioning signal according to Embodiments 4 to 7 of the present invention;
(A) is a diagram showing a positioning signal, and (b) is a diagram showing a focus drive output from an optical pickup drive driver.

FIG. 11 is a block diagram showing a configuration (main parts) of an actuator brake device in a focus control device of an optical disc device according to a fifth embodiment of the present invention.

12A and 12B are diagrams illustrating gain adjustment of a brake pulse according to Embodiment 5 of the present invention, wherein FIG. 12A illustrates a positioning signal, and FIG. 12B illustrates a focus drive output from an optical pickup driving driver.

FIG. 13 is a block diagram showing a configuration (main parts) of an actuator brake device in a focus control device of an optical disc device according to a sixth embodiment of the present invention;

14A and 14B are diagrams illustrating timings at which a brake pulse is generated while performing focus control according to Embodiment 6 of the present invention. FIG. 14A illustrates a positioning signal.
(B) is a diagram showing an envelope signal, and (c) is a diagram showing a focus drive output from an optical pickup drive driver.

FIG. 15 is a block diagram showing a configuration (main parts) of an actuator brake device in a focus control device of an optical disc device according to a seventh embodiment of the present invention;

16A and 16B are diagrams showing timings for generating a brake pulse while performing focus control according to the seventh embodiment of the present invention. FIG. 16A is a diagram showing a positioning signal.
(B) is a diagram showing an envelope signal, and (c) is a diagram showing a focus drive output from an optical pickup drive driver.

FIG. 17 is a diagram showing a quadrant detector.

FIG. 18 is a diagram showing a relationship between a positioning signal and a focal point;

FIG. 19 is a block diagram showing a configuration (main parts) of a focus control device in a conventional optical disc device.

FIGS. 20A and 20B are diagrams showing the timing of triangular wave generation during focus pull-in processing in a conventional optical disk device, where FIG. 20A shows a positioning signal, and FIG. 20B shows a focus drive output from an optical pickup driving driver.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 2 Spindle motor 3 Optical pickup 4 Positioning signal amplifier 5 Servo filter calculator 6 Optical pickup drive driver 7 Positioning signal presence / absence judgment device 8 Triangular wave generator 9 Servo ON / OFF switch 10 Driver output changeover switch 11 Driving direction detector 12 Focus brake generator 13 Timer 14 Focus brake / triangular wave switch 15 Drive speed detector 16 Focus brake gain adjuster 17 Head amplifier for envelope signal 18, 22 Envelope signal level comparator 19 Positioning signal valid / invalidator 20 Positioning signal level comparison 21 Position signal inclination detector 23 Envelope signal inclination detector

Claims (12)

[Claims] An actuator for moving an objective lens in an optical axis direction so that a laser beam is focused on an optical disk; and a positioning signal for generating a positioning signal for positioning the actuator from driving position information of the actuator. Generating means, driving direction detecting means for detecting the driving direction of the actuator from the positioning signal, positioning signal presence / absence determining means for determining the presence / absence of the positioning signal, and existence from the time when the positioning signal is determined to be absent An actuator brake device comprising: brake pulse generating means for generating a brake pulse corresponding to a driving direction of the actuator immediately before the positioning signal is no longer detected until the determination is made. 2. The apparatus according to claim 1, wherein said positioning signal presence / absence determining means determines that there is no signal when said positioning signal is not detected for a predetermined time, and determines that said signal is present when said signal is detected thereafter. Actuator brake device. 3. The apparatus according to claim 2, further comprising: a drive speed detecting means for detecting a drive speed of the actuator from the positioning signal; and a gain adjusting means for adjusting a gain of the brake pulse in accordance with the drive speed. Item 3. The actuator brake device according to Item 2. 4. An envelope signal generating means for generating an envelope signal of a data signal representing all data read from the optical disk, wherein the positioning signal presence / absence determining means includes an envelope signal monitoring means for monitoring the envelope signal, When the envelope signal when the positioning signal is no longer detected is lower than a predetermined level, it is determined to be nothing.When the envelope signal when the positioning signal is detected exceeds the predetermined level, 2. The actuator brake device according to claim 1, wherein the presence / absence determination is performed. 5. An apparatus according to claim 1, further comprising an envelope signal inclination detecting means for detecting an inclination of said envelope signal, and a gain adjusting means for adjusting a gain of said brake pulse in accordance with said inclination of said envelope signal. 5. The actuator brake device according to item 4. 6. A triangular wave generating means for outputting a triangular wave for controlling the driving of said actuator, and said positioning signal is detected by said positioning signal presence / absence detecting means even if said brake pulse generating means generates said brake pulse for a predetermined time. 6. The actuator brake device according to claim 1, further comprising: a switching unit that switches an output source to the actuator from the brake pulse generation unit to the triangular wave generation unit when the output is not detected. 7. An actuator for moving an objective lens in an optical axis direction so that a laser beam focuses on an optical disk, and a positioning signal for generating a positioning signal for positioning the actuator from driving position information of the actuator. Generating means; positioning signal inclination detecting means for detecting a peak state of the positioning signal from the inclination of the positioning signal; driving direction detecting means for detecting a driving direction of the actuator from the positioning signal; and whether the positioning signal is valid. A positioning signal valid / invalid determining means for determining whether or not the positioning signal is invalid, from a time when the positioning signal is determined to be invalid to a time when the positioning signal reaches a peak, according to a driving direction of the actuator immediately before being determined to be invalid. Brake pulse generating means for generating a brake pulse Actuator brake system, characterized by Bei. 8. The positioning signal valid / invalid determining means includes positioning signal monitoring means for monitoring the positioning signal, and determines that the positioning signal is invalid when the positioning signal is equal to or higher than a predetermined level. Actuator brake device. 9. A driving speed detecting device for detecting a driving speed of the actuator from the positioning signal, and a gain adjusting device for adjusting a gain of the brake pulse according to the driving speed. Item 10. An actuator brake device according to Item 8. 10. Envelope signal generating means for generating an envelope signal of a data signal representing all data read from an optical disk, said positioning signal validity / invalidity determining means monitoring a positioning signal, and a positioning signal monitoring means; 8. An envelope signal monitoring means for monitoring the envelope signal, wherein when the positioning signal is equal to or higher than a predetermined level and the envelope signal is equal to or lower than a predetermined level, it is determined that the signal is invalid. An actuator brake device according to any one of the preceding claims. 11. A positioning signal monitoring means for generating an envelope signal of a data signal representing all data read from an optical disk, wherein said positioning signal validity / invalidity determination means monitors a level of said positioning signal. And an envelope signal slope comparison means for detecting the slope of the envelope signal and comparing the slope of the envelope signal with a predetermined slope, wherein the positioning signal is equal to or higher than a predetermined level, and the slope of the envelope signal. 8. The actuator brake device according to claim 7, wherein when is smaller than a predetermined inclination, it is determined to be invalid. 12. An apparatus according to claim 1, further comprising: an envelope signal inclination detecting means for detecting an inclination of said envelope signal; and a gain adjusting means for adjusting a gain of said brake pulse according to an inclination of said envelope signal. The actuator brake device according to claim 10 or 11.