JP2000163759A - Optical disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable fast access control over an optical pickup by reading a counter electromotive force which is proportional to the vibration of an objective according to the difference signal from a differential circuit, outputting a driving current for reducing the vibration of the objective, and suppressing the vibration of the objective in seek operation. SOLUTION: In the seek operation, the driving coil of a tracking actuator 6 is connected to a differential amplifier 21, whose output is converted by an AD converter 22 into digital data and read by a servo processor 12. This servo processor 12 outputs constant digital data which reduces the actuator current to zero to a DA controller 17 which controls the tracking actuator 6 in specific cycles. The voltage developed at the driving coil of the tracking actuator 6 in the driving current state wherein the actuator current becomes zero is of the counter electromotive force proportional to the vibration of the objective 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical disk device capable of performing high-speed access control of an optical pickup.

[0002]

2. Description of the Related Art In an optical disk apparatus which is an information recording / reproducing apparatus, an optical disk is rotated at a predetermined rotation speed by a spindle motor for rotating the optical disk, and information is recorded on the optical disk by a focus actuator movable in the optical disk rotation axis direction. Positioning the objective lens so that the light spot is focused on the reproduction surface, positioning the optical pickup near a predetermined track on the optical disk by a feed motor that can move in the radial direction of the optical disk, and tracking that can move in the radial direction of the optical disk The recording and reproduction of information is performed by positioning the objective lens so that the light beam follows a predetermined track by the actuator.

If the target track from which information is to be read or written is far from the current track on which the light beam is currently following, the optical pickup is moved to the vicinity of the target track by the feed motor, and then the target is moved by the tracking actuator. A seek operation for capturing a track is performed. Since the time required for the seek operation is a waiting time in the system, a high-speed seek operation for quickly moving to the target track is indispensable.

However, since the objective lens is supported by the holding member so as to be movable in the rotation axis direction of the optical disk and in the radial direction of the optical disk, a large acceleration occurs when the optical pickup is moved in the radial direction of the optical disk by the feed motor at high speed. Alternatively, the objective lens causes free vibration in the radial direction of the optical disk due to the deceleration. Therefore, during the movement, the objective lens shifts greatly from the center position,
The signal indicating that the vehicle has crossed the track obtained by the signal from the optical pickup cannot be obtained normally,
In the worst case, the focus servo is shifted beyond the movable range of the objective lens. Further, even after the feed motor is stopped, the objective lens vibrates, and it becomes difficult to catch the target track by the tracking actuator.

Conventionally, a technique has been used in which a current is applied to the tracking actuator from the driving gas pressure of the feed motor to cancel the acceleration generated in the optical pickup. However, the drive voltage of the feed motor is a voltage that cancels the acceleration generated in the optical pickup due to the driving coil resistance of the motor, the torque constant of the motor, and the frictional force of the sliding bearing that holds the optical pickup movably in the radial direction of the optical disk. This is a problem because it is not possible to accurately obtain

Therefore, a back electromotive voltage proportional to the speed at which the objective lens vibrates is generated in the drive coil of the tracking actuator. Therefore, a technique has been used in which the voltage is detected and a current for reducing the speed is supplied to the tracking actuator. Was.

Japanese Patent Application Laid-Open No. Hei 6-333242 discloses a conventional technique for suppressing the vibration of the objective lens by the back electromotive voltage generated in the tracking actuator. According to this, there are a period for detecting a back electromotive voltage proportional to the speed generated in the drive coil of the tracking actuator, and a period for supplying a drive current for reducing the speed from the detected back electromotive voltage to the tracking actuator. The objective lens vibration caused by the acceleration applied to the tracking actuator accompanying the high-speed transfer is suppressed by speed feedback.

[0008]

By the way, Japanese Patent Application Laid-Open No.
According to the prior art as disclosed in Japanese Patent No. 333242, the actuator driving coil is connected to the back electromotive voltage detection circuit during the period of detecting the back electromotive voltage, and the actuator driving coil is connected to the driving circuit during the driving period of supplying the driving current for reducing the speed. Requires an associated switching element. Therefore, in order to solve the above-mentioned problem, the present invention provides a drive circuit that outputs a drive current to a drive coil of a tracking actuator so that a light beam follows a predetermined track on a recording or reproducing surface of an optical disc; And a differential circuit that outputs a differential signal of the voltage between both ends of the drive coil, and controls the drive circuit so that the drive current is not output during a seek operation, based on the differential signal output from the differential circuit. Provided is an optical disk device having a control circuit for reading a back electromotive voltage proportional to the vibration of the objective lens and thereafter controlling the drive circuit so as to output a drive current for reducing the vibration of the objective lens. Enables high-speed access control of the optical pickup by suppressing the vibration of the objective lens during seek operation. For the purpose of Rukoto.

[0009]

The present invention provides an optical disk device having the following configuration.

As shown in FIG. 1, an objective lens 4 is set so that a light spot is focused on a recording or reproducing surface of an optical disk 1.
And an optical pickup 3 having a tracking actuator 6 for positioning the objective lens 4 so that a light beam follows a predetermined track on the recording or reproducing surface. A drive circuit (tracking actuator drive circuit) 18 for outputting a drive circuit to a drive coil 6A of the tracking actuator 6 so that a light beam follows the predetermined track. A differential circuit (differential amplifier) 21 for outputting a differential signal between the voltages 6A1 and 6A2 at both ends of the drive coil 6A, and the drive circuit 18 for preventing the drive current from being output during a seek operation.
And reads a back electromotive voltage proportional to the vibration of the objective lens 4 based on the differential signal,
A control circuit (servo processor) 1 for controlling the drive circuit 18 so as to output a drive current for reducing vibration of the motor 1
An optical disk device, comprising: suppressing vibration of the objective lens 4 during a seek operation, thereby enabling high-speed access control of the optical pickup 3.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the optical disk drive according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing a main part (objective lens control circuit) of the optical disk device of the present invention, FIG. 2 is a diagram for explaining the operation of the optical disk device shown in FIG. 1, and FIG. It is a figure for explaining.

As shown in FIG. 1, the objective lens control circuit includes a spindle motor 2, a light source (not shown), an objective lens 4, a focus actuator 5, a tracking actuator 6, an optical pickup 3 having an optical sensor 8, Feed motor 7, focus error signal generation circuit 9, tracking error signal generation circuit 10, AD converters 11, 15, 22, servo processor (control circuit) 1
2. DA converters 13, 17, 19, focus actuator drive circuit 14, track counter circuit 16, tracking actuator drive circuit (drive circuit) 18, feed motor drive circuit 20, differential amplifier (differential circuit) 2.
One.

The optical disc apparatus of the present invention is capable of recording or reproducing an arbitrary track on the optical disc 1 by the optical pickup 3 having the focus actuator 5 and the tracking actuator 6 described above. In particular, by suppressing and removing the vibration of the objective lens 4 (unnecessary vibration that occurs mainly in the radial direction) generated during the seek operation,
This enables stable high-speed access control of the optical pickup 3 described above.

The optical pickup 3 includes a focus actuator 5 for positioning the objective lens 4 such that a light spot is focused on a recording or reproducing surface of the optical disc 1.
And a tracking actuator 6 for positioning the objective lens 4 so that a light beam follows a predetermined track on the recording or reproducing surface. As is well known, the focus actuator 5 includes a drive coil wound around a yoke, a magnet opposed to the drive coil, and the like so that the objective lens 4 can advance and retreat in the direction of the optical axis of the objective lens 4. . On the other hand, the tracking actuator 6
As shown in FIG. 3, a drive coil 6A wound around a yoke 6B so that the objective lens 4 can move in a direction perpendicular to the optical axis of the objective lens 4, a magnet 6C opposed to the drive coil 6A, etc. It is composed of

As shown in FIG. 3, one terminal 6A1 of the drive coil 6A constituting the tracking actuator 6 is connected to the input side (or output side) of the tracking actuator drive circuit 18 and one input side of the differential amplifier 21. It is connected. On the other hand, the other terminal 6A2 is connected to the output side (or input side) of the tracking actuator drive circuit 18 and the other input side of the differential amplifier 21. Thus, the tracking actuator driving circuit 18 described above drives the driving coil 6A of the tracking actuator 6 so that the light beam follows the predetermined track.
And a drive current for suppressing unnecessary vibration of the objective lens 4 during a seek operation. Further, the above-described differential amplifier 21 is provided with both ends 6A1 of the driving coil 6A of the tracking actuator 6.
A difference signal of the voltage of 6A2 is output.

During the seek operation, the servo processor 12 controls the tracking actuator driving circuit 18 so that the driving current is not output from the tracking actuator driving circuit 18, and outputs the signal from the differential amplifier 21. A counter electromotive voltage proportional to the vibration of the objective lens 4 is read based on the differential signal to be generated, and thereafter, the tracking actuator drive circuit 18 is controlled so as to output a drive current for reducing the vibration of the objective lens 4. I do.

Next, a specific description will be given. The optical disk 1 is driven to rotate by a spindle motor 2. Reading and writing of data on the surface (recording or reproducing surface) of the optical disk 1 is performed by the optical pickup 3. The objective lens 4 in the optical pickup 3 is positioned by the focus actuator 5 in the optical disk rotation axis direction so that the light spot is focused on the information recording or reproducing surface of the optical disk 1. Further, the tracking actuator 6 is positioned so that the light beam follows a predetermined track in the radius of the optical disk 1. Since the tracking actuator 6 does not have a movable range from the innermost track to the outermost track of the optical disc 1, the feed motor 7 that can move the optical pickup 3 in the radial direction of the optical disc 1 moves the optical pickup 3 near a predetermined track on the optical disc 1. The optical pickup 3 is positioned at the position.

The light beam reflected on the information recording or reproducing surface of the optical disk 1 is converted into an electric signal by an optical sensor 8 and sent to an information processing circuit (not shown), and a focus error signal generating circuit for positioning the focus actuator 5. 9 and a tracking error signal generating circuit 1 necessary for controlling the tracking actuator 6
Sent to 0.

The focus error signal output from the focus error signal generation circuit 9 is converted to digital data by the AD converter 11 and then sent to the servo processor 12. The servo processor 12 sends the digital manipulated variable for which the predetermined positioning compensation operation has been performed to the DA converter 13 and converts it into an analog manipulated variable, and then sends it to the focus actuator drive circuit 14 to drive the focus actuator 5. The objective lens 4 is positioned so that the light spot is focused on the information recording / reproducing surface of the optical disk 1.

The tracking error signal output from the tracking error signal generation circuit 10 is sent to the AD converter 15 and to the track counter circuit 16.
At the time of the track following control operation, the tracking error signal converted into digital data by the AD converter 15 is sent to the servo processor 12, and the digital operation amount obtained by performing the predetermined positioning compensation calculation is converted into the analog operation amount by the DA converter 17. After being converted into an amount, the signal is sent to a tracking actuator drive circuit 18 to drive the tracking actuator 6 and positioned so that the light beam follows a predetermined track.

During the track following control operation, the servo processor 12 performs a predetermined compensation operation on the track following control operation amount, which is a digital operation amount sent to the DA converter 17, and then performs an analog operation by the DA converter 19. After being converted into an amount, the optical pickup 3 is sent to a feed motor drive circuit 20 to drive the feed motor 7 to position the optical pickup 3 near a predetermined track on the optical disc 1.

The optical pickup 3 is driven by the feed motor 7.
During the seek operation to move the track to the vicinity of the target track, the servo processor 12 sets the value of the track counter 16 for counting the number of tracks crossing the track by the optical pickup 3 to the number of tracks to the target track calculated in advance. The feed motor 7 is controlled to be equal to

During the seek operation, both terminals 6A1, 6A of the drive coil 6A of the tracking actuator 6 are operated.
A2 is connected to the differential amplifier 21, and the output voltage of the differential amplifier 21 is converted into digital data by the AD converter 22 and read by the servo processor 12. Serpo processor 12
2 outputs constant digital data such that the actuator current becomes zero (0) to a DA converter 17 that controls the tracking actuator 6 in a T1 cycle shown in FIGS. 2A and 2B.

Tracking actuator drive circuit 18
Is a constant current drive circuit, the impedance is infinite, and in the drive current state where the actuator current is 0, the voltage generated at both ends 6A1 and 6A2 of the drive coil 6A of the tracking actuator 6 is The back electromotive voltage is proportional to the speed of the vibration of the objective lens 4. Since the T1 cycle is set to the time until the actuator current settles to zero, the digital data taken in by the AD converter 22 at the end of the T1 cycle is a counter electromotive voltage proportional to the speed due to the vibration of the objective lens 4. It is.

At the end of the T1 period, the digital data converted by the AD converter 22 is
The servo processor 12 outputs the drive current to the DA converter 17 in the period T2 so that a drive current for reducing the speed due to the vibration of the objective lens 4 flows through the tracking actuator 6. By repeating the T1 cycle and the T2 cycle in this manner, the vibration of the objective lens 4 during the seek operation can be suppressed.

[0026]

As described above, according to the optical disk apparatus of the present invention, (1) a drive circuit for outputting a drive current to a drive coil of a tracking actuator so that a light beam follows a predetermined track on a recording or reproducing surface of an optical disk. A differential circuit that outputs a differential signal of a voltage between both ends of a driving coil of the tracking actuator; and a control circuit that controls the drive circuit so that a drive current is not output from the drive circuit during a seek operation. And a control circuit for controlling the drive circuit so as to output a drive current for reducing the vibration of the objective lens after reading a back electromotive voltage proportional to the vibration of the objective lens based on the differential signal output from Therefore, by suppressing the vibration of the objective lens during the seek operation, high-speed access control of the optical pickup becomes possible. . In addition, since the objective lens vibration due to the high-speed movement of the feed motor can be suppressed without using an element for switching the driving state of the tracking actuator and the state of the back electromotive force generated at both ends of the driving coil, the number of parts can be reduced and the high-speed seek can be performed. There is an advantage that the operation becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of an optical disk device according to the present invention.

FIG. 2 is a diagram for explaining the operation of the optical disk device shown in FIG.

FIG. 3 is a diagram for explaining the structure of a tracking actuator 6;

[Explanation of symbols]

Reference Signs List 1 optical disk 3 optical pickup 4 objective lens 5 focus actuator 6 tracking actuator 6A drive coil 6A1, 6A2 terminal 12 servo processor (control circuit) 18 tracking actuator drive circuit (drive circuit) 21 differential amplifier (differential circuit)

Claims (1)

[Claims] 1. A focus actuator for positioning an objective lens such that a light spot is focused on a recording or reproducing surface of an optical disk, and the objective lens is arranged so that a light beam follows a predetermined track on the recording or reproducing surface. An optical disc apparatus comprising: an optical pickup having a tracking actuator for positioning; and an optical disc apparatus for recording or reproducing an arbitrary track on an optical disc, wherein the optical beam is driven by a driving coil of the tracking actuator so that a light beam follows the predetermined track. A driving circuit that outputs a current; a differential circuit that outputs a differential signal of a voltage between both ends of the driving coil; and a drive circuit that controls the driving circuit so that the driving current is not output during a seek operation. Reading a back electromotive force proportional to the vibration of the objective lens based on the A control circuit for controlling the drive circuit so as to output a drive current for reducing the vibration of the lens, and suppressing high-speed access control of the optical pickup by suppressing the vibration of the objective lens during a seek operation. An optical disk device characterized in that it can be used.