JP2001344786A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce motion sound caused by the movement of an objective lens driven by an actuator, in the case where vibration, face wobbling of an optical disk, and eccentricity that are above the allowable level are detected in the optical disk device. SOLUTION: The device is constituted of a disk motor, rotational frequency generating means, disk motor control means, focus actuator, tracking actuator, focus error signal detecting means, focus control signal generating means, tracking error signal detecting means, tracking control signal generating means, actuator frequency characteristics setting means, wobbling correcting signal generating means, and eccentricity correcting signal generating means. The frequency characteristics of an actuator control loop is set to the absolute minimum, the motion sound caused by the movement of the objective lens driven by the actuator is reduced, the focus and tracking error signal levels are monitored constantly, and, focus control and tracking control are interrupted, thus, the motion sound can be reduced.

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 recording or reproducing information, and more particularly to an optical disk apparatus having a control system for reducing an operation sound generated due to an operation of an objective lens driven by an actuator. About.

[0002]

2. Description of the Related Art At present, an optical disk device for recording or reproducing information using an optical disk such as a CD or a DVD as a medium has been put into practical use, and its application is various, such as information recording / reproducing equipment in personal computers and AV.

[0003] First, an example of a sequence up to recording or reproduction of information in an optical disk device will be briefly described.

After mounting an optical disk at a predetermined position in the apparatus,
This is rotated by a disk motor. Next, the optical disk surface is irradiated with laser light, and the objective lens is driven in a direction perpendicular to the optical disk surface to start focus control for focusing. Subsequently, the tracking control for following the track by driving the objective lens in the horizontal direction with respect to the optical disk surface is started. Finally, information is recorded or reproduced by accessing the target track from the current track by the seek control.

Next, an actuator for driving an objective lens and a mechanism around the actuator in the optical disk device will be described with reference to FIG.

In FIG. 3, reference numeral 101 denotes an objective lens, 10
2 is a magnet, 103 is a focus drive coil, 10
4 is a tracking drive coil, 105 is a movable housing, 10
6 is a yoke, 107 is a base plate. When a current is applied to the focus drive coil, the movable housing 105 including the objective lens 101 operates in the focus direction, and can move the objective lens to the focal position. Similarly, the tracking drive coil 104
When an electric current is applied to the movable housing 10 including the objective lens 101,
Reference numeral 5 operates in the tracking direction, and can move the objective lens to a predetermined track position.

[0007]

In the actuator for driving the objective lens and its peripheral mechanism described in the prior art, when the movable housing 105 is driven in the focus direction or the tracking direction, the yoke 106 is simultaneously moved from the magnet 102. It receives a reaction force via the generated magnetic force and vibrates at a plurality of natural frequencies existing in a band of several KHz to tens KHz. If this state continues, there is a problem that the movable housing 105 acts as a vibrator of the speaker, and the yoke 106 acts as a resonance plate, so that an operation sound having a peak from several KHz to tens KHz is remarkably generated.

When an information recording / reproducing apparatus using an optical disk as a medium is put to practical use, especially in an apparatus capable of recording external sound, when an operation sound generated from the inside of the apparatus is remarkable, it may be affected as noise. Conceivable. Further, this operation sound varies depending on the optical disk device, but causes a hearing problem.

Therefore, the following two methods can be considered as a method of reducing the operation noise caused by the operation of the actuator, such as the vibration of the yoke 106.

One is a method of reducing vibration by optimizing the weight and hardness by changing the shape and material of the base plate 107 described above. This is effective as a countermeasure for reducing the operation noise, but it is often difficult to take a sufficient countermeasure in consideration of the recent miniaturization, thinning, and cost reduction of the optical disk device.

As a second method, the current flowing through the focus drive coil 103 and the tracking drive coil 104 for driving the objective lens 101 is changed, and the acceleration of the actuator is reduced, so that the yoke 106
A method for reducing the reaction force applied to the surface is considered. Normal FB
The maximum acceleration that can be generated by the actuator in the case of the control operation depends on the frequency characteristic determined by the loop transfer function of the FB loop. Therefore, the operating noise can be reduced by changing the frequency characteristics of the actuator control loop.

However, this frequency characteristic is designed so that the objective lens can follow the surface deviation and the eccentric component of the optical disk in which the actuator operates at the target rotation speed. Further, in order to be able to cope with vibrations such as when used in a portable application, the gain near the frequency of the vibration is increased to compensate. For this reason, changing the frequency characteristic of the actuator control loop, especially lowering the gain, deteriorates the tracking performance of focus and tracking and the seismic performance against disturbance.

[0013] It is an object of the present invention to detect the acceleration (vibration) applied to the apparatus, the amount of surface deviation and the amount of eccentricity of the optical disk, and set the frequency characteristics of the actuator control loop to the minimum necessary. It is an object of the present invention to provide an optical disk device having high data quality and high reliability, which can reduce operation noise generated while maintaining control performance of an actuator.

[0014]

An optical disk apparatus according to the present invention changes the frequency characteristic of an actuator control loop in accordance with the vibration level, the deviation of the surface of the optical disk, and the eccentricity of the optical disk. , Are operated so as to reduce the operation sound generated due to the actuator operation during the seek operation or during the recording or reproduction of information.

Therefore, the optical disk apparatus according to the present invention comprises a disk motor for rotating an optical disk, a rotation frequency generating means for outputting a signal corresponding to the rotation angle of the disk motor, and a disk motor control means for controlling the rotation speed of the disk motor. A focus actuator for driving the objective lens in a direction perpendicular to the optical disk surface, a tracking actuator for driving the objective lens in a direction horizontal to the optical disk surface, a focus error signal detection unit, a focus control signal generation unit, and a tracking error signal detection Means, a tracking control signal generating means, an actuator frequency characteristic setting means, a focus vibration level detecting means, and a tracking vibration level detecting means.

Here, the actuator frequency characteristic setting means has a first memory and a second memory. The actuator frequency characteristic setting unit sets at least one of a frequency characteristic of the focus FB control system and a frequency characteristic of the tracking FB control system based on the vibration level or the output of the disk motor control unit.

Further, the optical disk apparatus of the present invention comprises a surface shake correction signal generating means for detecting a surface shake amount and calculating a surface shake correction signal, a third memory control means, and converting the surface shake correction data into a focus control signal. Plane deviation correction data adding means for adding, eccentricity correction signal generating means for detecting the amount of eccentricity and calculating the eccentricity correction signal, fourth memory control means, and adding the eccentricity correction data to the tracking control signal It is provided with tracking correction data adding means.

Here, the plane deviation correction signal generation means has a third memory for storing the plane deviation correction data, and the eccentricity correction signal generation means has a fourth memory for storing the eccentricity correction data.

The actuator frequency characteristic setting means sets the frequency characteristic of the focus FB control system based on the surface shake correction data, and sets the frequency characteristic of the tracking FB control system based on the eccentricity correction data.

Further, the focus control signal generating means in the optical disk apparatus of the present invention, based on the focus error signal, suspends the focus control if the error signal does not fall below a predetermined level within a predetermined time due to disturbance. Operate. The tracking control signal generating means operates based on the tracking error signal so as to interrupt the tracking control if the error signal does not fall below a predetermined level within a predetermined time due to the influence of disturbance.

By providing the above means, the vibration level, the amount of surface deviation and the amount of eccentricity of the optical disk are detected, and the frequency characteristic of the actuator control loop is set in accordance with these states, thereby causing the operation of the actuator control loop. Operating noise generated by the operation can be reduced. Furthermore, by monitoring the error signal levels of the focus and tracking over time and operating the focus control and tracking control to be interrupted, the operation noise generated due to the operation of the objective lens driven by the actuator is reduced. It is possible to do. As a result, high-quality data can be recorded, and the reliability of the device can be improved.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the configuration of an embodiment of the optical disk apparatus of the present invention will be described with reference to FIG. 1 is an optical disk, 2 is a disk motor, 3 is a rotation frequency generating means, 4
Is a disk motor control means, 5 is an objective lens, 6 is a focus actuator, 7 is a tracking actuator, 8 is a focus error detection means, 9 is a focus control signal generation means, 10 is a tracking error detection means, 11
Is a tracking control signal generating means. 12 is an actuator frequency characteristic setting means, 13 is a focus vibration level detecting means, 14 is a tracking vibration level detecting means, 15 is a first memory for storing the vibration level of the actuator, and 16 is a first memory for storing the output of the disk motor control means. Second memory. Reference numeral 17 denotes a plane blur correction signal generating unit, 18 denotes a third memory for storing the plane blur correction data, 19 denotes a third memory control unit that outputs the plane blur correction data, and 20 denotes a plane blur correction data adding unit. . Further, 21 is an eccentricity correction signal generating means, 22 is a fourth memory for storing eccentricity correction data, 23 is a fourth memory control means for outputting eccentricity correction data, and 24 is an eccentricity correction data adding means. is there.

FIG. 1 shows an optical disk apparatus according to an embodiment of the present invention.
Each block will be specifically described according to the following. The disk motor 2 rotates the optical disk 1 at a predetermined speed. As the optical disk 1 rotates, the rotation frequency generator 3 sends a signal corresponding to the rotation angle of the disk motor 2 to the disk motor controller 4. The disk motor control means 4 controls the disk motor 2 to a predetermined rotation speed using the signal sent from the rotation frequency generation means.

The objective lens 5 focuses the laser light irradiated on the optical disk 1 surface. The focus actuator 6 drives the objective lens 5 in a direction perpendicular to the optical disk 1 to position the focused focal point on the optical disk 1 surface.
The tracking actuator 7 drives the objective lens 5 in the horizontal direction with respect to the optical disc 1 to position the focused focal point on a track on the optical disc 1. The reflected light from the optical disk 1 is sent to the focus error signal detecting means 8 and the tracking error signal detecting means 10.

The focus error detecting means 8 generates a focus error signal including focus error information of the objective lens 5 and the optical disk 1 based on the transmitted reflected light, and sends the focus error signal to the focus control signal generating means 9. The focus control signal generation means 9 sends a control signal to the focus actuator 6 to maintain the focal length of the objective lens 5 based on the sent error signal.

The tracking error detecting means 10 generates a tracking error signal including track following error information of the objective lens 5 and the optical disk 1 from the transmitted reflected light,
This is sent to the tracking control signal generator 11. The tracking control signal generating means 11 sends a control signal to the tracking actuator 7 so that the objective lens 5 follows the track based on the sent error signal.

In this optical disk apparatus, focus FB control for feeding back a focus error signal and tracking FB control for feeding back a tracking error signal are performed. Normal F
In the case of the B control, the maximum acceleration that can be generated by the actuator depends on a frequency characteristic determined by a loop transfer function of the FB loop. Therefore, an actuator frequency characteristic setting means 12 for changing each frequency characteristic of the focus FB control system and the tracking FB control system according to the disturbance.
Is provided.

The focus vibration level detecting means 13
Detects the vibration in the focus direction applied to the objective lens 5 and sends the vibration level to the first memory 15. Similarly, the tracking vibration level detecting means 14 detects the vibration in the tracking direction applied to the objective lens 5 and sends the vibration level to the first memory 15. Referring to the first memory 15, the actuator frequency characteristic setting means 12 determines, based on each of the transmitted vibration levels, that the vibration level is large (small) for an arbitrary state as shown in FIG. 4, for example. An operation is performed to set at least one of the gains of the frequency characteristics of the focus FB control system and the frequency characteristics of the tracking FB control system to be high (low). The output of the disk motor control means 4 is sent to the second memory 16. Referring to the second memory 16, the actuator frequency characteristic setting means 12 determines, based on the output value sent, when the rotation speed of the optical disc 1 is low (high) with respect to an arbitrary state, for example, as shown in FIG. Operates such that at least one of the frequency characteristics of the focus FB control system and the frequency characteristics of the tracking FB control system is set low (high).

Next, an embodiment of the surface blur correction and the eccentricity correction of the optical disk apparatus of the present invention will be described with reference to FIG. The plane blur correction signal generation unit 17 calculates a plane blur amount by associating the signal sent from the rotation frequency generation unit 3 with the focus error signal sent from the focus error detection unit 8,
The image blur correction data is stored in the third memory 18. Based on the third memory control means 19, the stored face shake correction data is sent to the face shake correction data adding means 20 and the actuator frequency characteristic setting means 12. The plane deviation correction data adding means 20 adds the transmitted plane deviation correction data and the focus control signal output from the focus control signal generation section 9, and sends a control signal to the focus actuator 6. The actuator frequency characteristic setting means 12 determines the frequency characteristic of the focus FB control system based on the transmitted surface shake correction data, for example, when the surface shake amount is large (small) with respect to an arbitrary state as shown in FIG. It operates to set the gain high (low).

The eccentricity correction signal generating means 21 calculates the amount of eccentricity by associating the signal sent from the rotation frequency generating means 3 with the tracking error signal sent from the tracking error detecting means 10, and calculates the eccentricity. The core correction data is stored in the fourth memory 22. The stored eccentricity correction data is stored in the eccentricity correction data adding means 2 based on the fourth memory control means 23.
4 and the actuator frequency characteristic setting means 12. The eccentricity correction data adding means 24 adds the sent eccentricity correction data and the tracking control signal output from the tracking control signal generating means 11 and sends a control signal to the tracking actuator 7. Actuator frequency characteristic setting means 12 based on the transmitted eccentricity correction data,
For example, when the amount of eccentricity is large (small) with respect to an arbitrary state as shown in FIG. 4, the operation is performed to set the gain of the frequency characteristic of the tracking FB control system to be high (low).

Further, the features of the focus control signal generating means 9 and the tracking control signal generating means 11 in the optical disk device according to the embodiment of the present invention will be described.

The focus control signal generating means 9 operates based on the focus error signal so as to interrupt the focus control if the error signal does not fall below a predetermined level within a predetermined time due to disturbance. Further, based on the tracking error signal, the tracking control signal generating means 11 operates so as to interrupt the tracking control if the error signal does not fall below a predetermined level within a predetermined time due to the influence of disturbance. Thus, the audible time of the operation sound generated due to the operation of the objective lens can be shortened.

Finally, the effects of the embodiment of the present invention will be described. When the optical disk device having the means for changing the frequency characteristic of the actuator control loop as described above detects a vibration level exceeding an allowable value, and the amount of runout and eccentricity of the optical disk, control of the actuator is performed. It is possible to reduce operation noise generated due to the operation of the objective lens driven by the actuator while maintaining performance. Furthermore, by monitoring the error signal levels of the focus and tracking over time and operating the focus control and tracking control to be interrupted, the operation noise generated due to the operation of the objective lens driven by the actuator is reduced. It is possible to do.

Here, there are several means for calculating and adding the surface shake correction data and the eccentricity correction data.
For example, there is a method in which an error signal is detected for each rotation angle of the disk motor, and correction data for each rotation is calculated and added. Further, there is a method of detecting an error signal according to the rotation speed of the optical disc, calculating correction data, and adding the correction data. Further, there is a method of detecting an error signal for each rotation angle of the disk motor, storing the first correction data in a memory, performing a comparison operation with subsequent data, and adding the data. The present invention is not limited to one of these approaches.

[0035]

As described above, according to the present invention, the frequency characteristic of the actuator control loop is set to the necessary minimum when the vibration level exceeding the allowable value, the amount of surface deviation and the amount of eccentricity of the optical disk are detected. As a result, it is possible to reduce the operation noise generated due to the operation of the objective lens driven by the actuator while maintaining the control performance of the actuator. Furthermore, by monitoring the error signal levels of the focus and tracking over time and operating the focus control and tracking control to be interrupted, the operation noise generated due to the operation of the objective lens driven by the actuator is reduced. It became possible to make it. Thereby, high-quality data can be recorded, and the reliability of the device is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

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

FIG. 3 is a diagram of an actuator and a mechanism around the actuator.

FIG. 4 is an actuator frequency characteristic diagram.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Disk motor, 3 ... Rotation frequency generation means, 4 ... Disk motor control means, 5 ... Objective lens, 6 ... Focus actuator, 7 ... Tracking Actuator 8 Focus error detecting means 9 Focus control signal generating means 10 Tracking error detecting means 11 Tracking control signal generating means 12 Actuator frequency characteristic setting means 13: focus vibration level detecting means, 14: tracking vibration level detecting means, 15: first memory, 16: second memory, 17: surface shake correction signal generating means, 18 ... third memory, 19 ... third memory control means, 20 ... surface shake correction data adding means, 21 ... eccentricity compensation Signal generation means, 22 ... fourth memory, 23 ... fourth memory control means, 24 ... eccentricity correction data adding means.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroaki Ono 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture F-term in the Digital Media Development Division, Hitachi, Ltd. 5D118 AA23 BA01 CA04 CD02 CD03 CD12 CD13

Claims (12)

[Claims] 1. An optical disk device for recording or reproducing information using an optical disk as a medium, a disk motor for rotating the optical disk, a rotation frequency generating means for outputting a signal corresponding to a rotation angle of the disk motor, and the disk Disk motor control means for controlling a rotation speed of a motor; an objective lens for condensing laser light on an optical disk surface; a focus actuator for driving the objective lens in a direction perpendicular to the optical disk surface; A tracking actuator that drives in the horizontal direction; a focus error signal detection unit that detects a focus error signal that is an error between the optical disk and the objective lens in a vertical direction with respect to the optical disk surface; The objective A focus control signal generating means for generating a focus control signal for causing the lens to focus on the optical disk surface; and a tracking error signal for detecting a tracking error signal that is a horizontal error between the optical disk and the objective lens with respect to the optical disk surface. Detecting means, based on an output of the tracking error signal detecting means,
A tracking control signal generating means for generating a tracking control signal for the objective lens to follow a track on the optical disc; and a focus feedback control system configured to include the focus control signal generating means in the focus system. An actuator frequency for setting at least one of a frequency characteristic and a frequency characteristic of a tracking feedback (hereinafter, referred to as FB) control system including the tracking control signal generating means in the tracking system in accordance with a disturbance to the actuator. An optical disk device comprising a characteristic setting unit. 2. The apparatus according to claim 1, wherein the disturbance to the actuator is a vibration in a focus direction, and further includes a focus vibration level detecting means for detecting the vibration, and the actuator frequency characteristic setting means is based on an output of the focus vibration level detecting means. hand,
2. The optical disk device according to claim 1, wherein a frequency characteristic of the focus FB control system is set. 3. The apparatus according to claim 2, wherein the disturbance to the actuator is a vibration in a tracking direction, and further includes tracking vibration level detecting means for detecting the disturbance. The actuator frequency characteristic setting means is based on an output of the tracking vibration level detecting means. 3. The optical disk device according to claim 1, wherein frequency characteristics of the tracking FB control system are set. 4. An actuator frequency characteristic setting means, comprising: a frequency characteristic of the focus FB control system and the tracking frequency based on an output of the disk motor control means.
4. The optical disk device according to claim 1, wherein at least one of the frequency characteristics of the B control system is set. 5. The actuator frequency characteristic setting means has a first memory for storing and referring to the vibration level in the focus direction and the vibration level in the tracking direction, and the focus stored in the first memory. 3. The method according to claim 2, wherein at least one of a frequency characteristic of the focus FB control system and a frequency characteristic of the tracking FB control system corresponding to the vibration level is set based on at least one of a vibration level and a tracking vibration level.
An optical disk device according to any one of claims 4 to 4. 6. The actuator frequency characteristic setting means has a second memory for storing and referring to the number of rotations of the disk motor, and based on the number of rotations of the disk motor held in the second memory. 6. The optical disk device according to claim 4, wherein at least one of a frequency characteristic of the focus FB control system and a frequency characteristic of the tracking FB control system is set. 7. A data (hereinafter, referred to as a data hereinafter) for detecting a surface shake amount of the optical disk device based on the focus error signal and an output of the rotation frequency generating means and canceling the surface shake amount.
This is referred to as surface shake correction data. ), A third memory for storing the shake correction data, and a third memory control for selectively outputting the shake correction data stored in the third memory. 7. The apparatus according to claim 1, further comprising: a means for adding the shake correction data output from the third memory to the focus control signal. 8. Optical disk device. 8. Data for detecting the eccentricity of the optical disk device based on the tracking error signal and the output of the rotation frequency generating means and canceling the eccentricity (hereinafter referred to as eccentricity correction data). ), A fourth memory for storing the eccentricity correction data, and a fourth memory for selectively outputting the eccentricity correction data stored in the fourth memory. 8. An eccentricity correction data adding means for adding the eccentricity correction data output from the fourth memory to the tracking control signal, the control means comprising: Optical disk device. 9. The apparatus according to claim 7, wherein said actuator frequency characteristic setting means sets a frequency characteristic of said focus FB control system based on said surface shake correction data.
An optical disk device according to any one of claims 8 to 10. 10. The frequency characteristic of the tracking FB control system, wherein the actuator frequency characteristic setting means sets the frequency characteristic of the tracking FB control system based on the eccentricity correction data.
10. An optical disk device according to any one of claims 9 to 9. 11. The focus control signal generating means, according to the focus error signal, suspends focus control if the error signal does not fall below a predetermined level within a predetermined time due to disturbance. The optical disk device according to claim 1. 12. The tracking control signal generating means, based on the tracking error signal, interrupts the tracking control if the error signal does not fall below a predetermined level within a predetermined time due to disturbance. The optical disk device according to claim 1.