JPH05334696A - Access controller - Google Patents

Abstract

PURPOSE:To provide an access controller by which transfer from seek to tracking control can be stably performed even when external shock, etc., is applied, and the access time of an optical disk device can be shortened. CONSTITUTION:The access controller of the optical disk device using an optical disk 10 provided with a circular shape track for information recording is equipped with a lens position sensor 6 which detects the position of the objective lens 3L of an optical pickup 2, and a lens vibration suppression circuit 7B controlled corresponding to the output of the lens position sensor 6 and which suppresses the vibration of the objective lens 3L. The output of the lens vibration suppression circuit 7B is supplied to a tracking driving circuit 5 which controls a tracking actuator 3 for a prescribed time just before and immediately after the transfer from the seek to the tracking control is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an access control device, and more particularly to a servo circuit for an optical disk device.

[0002]

2. Description of the Related Art First, an outline of an optical disk device will be described. The optical pickup collects laser light from a semiconductor laser, irradiates it at a target position on an optical disc, records and reproduces information, and is composed of an optical system and a drive system. The optical system is a mechanism for condensing laser light on the optical disk and detecting a deviation between a laser light spot and a target position on the optical disk, such as a semiconductor laser, lenses, a beam splitter, and a photodiode. Composed of.

The drive system performs focusing control for causing the objective lens to follow the surface wobbling of the optical disk and tracking control for tracking the track wobbling to maintain a constant positional relationship between the target position on the optical disk and the light beam spot. It is a drive mechanism for
It is composed of a coil and a support member. In addition, the drive system also includes a drive mechanism of a seek control system for moving the entire optical pickup to a target position in the radial direction of the optical disc.

The access control device is a control device for moving the light beam spot to a target position. Here, the outline of the access control system of the conventional optical disk device will be described below with reference to FIG. FIG. 3 is a diagram showing an example of a conventional access control device. In FIG. 3, the slider 18 is guided by a rail 19 to move in the radial direction of the optical disc 10, and is driven by a coarse movement motor 21 driven by a slider drive circuit 9.

The movement (or movement) of the optical pickup to a predetermined sector on a predetermined track is called an access operation. In this access operation, the movement of the optical pickup in the radial direction of the disk to the vicinity of the target track is called a seek operation. The seek operation is called coarse seek when the distance the optical pickup moves is large,
When the distance traveled is one to several hundred tracks, it is called fine seek.

In FIG. 3, the entire optical pickup 2 is fixed to the slider 18, and the rough seek operation is performed by a microprocessor (hereinafter referred to as MPU) 12.
The coarse movement motor 21 moves the slider 18 to move the light beam from the laser light source to the vicinity of the target track. The fine seek operation is an operation of stopping the slider 18 and moving the laser light beam to a track separated by 1 to several hundred tracks by an operation called a track jump as described above.

In the figure, the objective lens 3L is connected to the tracking actuator 3 by a spring material, and is controlled by the tracking actuator 3 to move. The laser light beam passes through the objective lens 3L and the like, is reflected by the recording surface of the optical disc 10, and passes through a beam splitter (not shown), a condenser lens (not shown), and the like, and is used for signal detection photo. It is incident on the diode 23. The photodiode 23 is a four-division photodiode.
A reproduction signal is detected from a plurality of outputs of the above and is supplied to the demodulator 25, and the displacement of the light beam in the radial direction of the disk is detected as a track error signal TE by the track error detection circuit 4 by the one-beam push-pull method. It

The tracking control circuit 13 and the track jump control circuit 13A are controlled by the output TE of the track error detection circuit 4. The slider control circuit 14
As the optical pickup 2 moves on the circular track, the slider drive circuit 9 is controlled to move the slider 18.

The position of the objective lens 3L is detected by a lens position sensor 6, and a slider control circuit 14 for aligning the center of the objective lens 3L with the optical axis of the laser beam at the time of recording or reproducing, and the objective lens at the time of seeking. It is input to the lens hold circuit 7A that fixes 3L at a predetermined position. The output terminals of the tracking control circuit 13, the track jump control circuit 13A and the lens hold circuit 7A are connected to the input terminals 62, 63 and 64 of the switch 15A, respectively. The tracking drive circuit 5 for driving the tracking actuator 3 is controlled by a signal from the output terminal 61 of the switch 15A.

The position of the slider 18 is detected by a linear encoder 20, and the output signal thereof is a slider position control circuit 17 for stopping the slider, a slider speed control circuit 8 for controlling the slider transfer speed, and the slider control circuit. 14 and the output terminals of these three circuits are the input terminals 6 of the switch 16A.
6, 67 and 68, respectively. The signal from the output terminal 65 of the switch 16A controls the slider drive circuit 9 for driving the coarse movement motor 21.

The connection relationship between the switches 15A and 16A is M to which the output of the demodulator 25 is applied.
It is controlled by the PU 12. For example, at the time of rough seek, the terminal 65 is connected to the terminal 67 and the slider 18 is transferred at high speed, and when the slider 18 reaches a target position, the terminal 65 is moved.
Is connected to a terminal 66, the slider 18 is stopped in a short time, and the terminal 61 is connected to a terminal 64. The terminal 65 is connected to the terminal 68 and the terminal 61 is connected to the terminal 63 during the fine seek, and the terminal 65 is connected during the tracking control.
Is connected to the terminal 68, and the terminal 61 is connected to the terminal 62. The track number is read from the output of the photodiode 23 via the demodulator 25 and transmitted to the MPU 12.

The order of the access operation is as follows. Step 1 The rotation system including the rotation control disk is set to a target rotation speed. Step 2 Focus pull-in The so-called focus pull-in operation is performed to control the objective lens and bring the beam waist of the light beam to the recording surface of the disc. Step 3 Focusing Focusing is performed so that the recording surface is always near the beam waist of the laser or within the depth of focus of the objective lens.

Step 4 Track pull-in In order to read the address on the disk illuminated by the light beam, the tracking control circuit 13 performs a beam track pull-in operation. step 5 tracking step 6 The seek address is read, and when the distance from the target address is equal to or more than a predetermined value, the seek operation of moving the light beam according to this distance is performed. This operation is performed by the slider speed control circuit 8 and the slider position control circuit 17. When the distance is less than a predetermined value, track jump is performed.

Step 7 At the place where the track jump seek control system lands, the tracking control circuit 13 again performs the track pull-in operation and the tracking operation to read the address information. Step 8 Re-execution When the light beam does not match the target address, the operation for reaching the target address again is performed. That is, the tracking error signal is counted, and the operation of moving the light beam continuously instead of one track to reach the target track, that is, a so-called track jump operation is performed. This operation mode is performed by the track jump control circuit 13A.

By the way, in the above-mentioned optical disk device, when vibration or impact is applied from the outside in the track seek direction at the time of pulling in the tracking, the above step is performed.
In step 4 and 5, stable tracking is no longer achieved, the control system of the objective lens 3L tends to oscillate, the objective lens 3L vibrates to the limit of movement, or a focus signal is obtained. There was a problem that the focus was lost because it was not possible to do so, and the access time increased.

[0016]

As described above, in the conventional access control apparatus, when the optical disk apparatus is externally vibrated or shocked when the tracking control is performed after the seek, the tracking is not stable. was there. The present invention has been made to solve the above problems, and an object of the present invention is to improve the stability of the tracking pull-in operation at the start of tracking control and shorten the access time.

[0017]

An optical pickup for recording and reproducing information on an optical disk having a circular information recording track, and a tracking actuator for controlling a light beam spot on the optical disk to follow a target track. , A tracking error detection circuit for detecting a deviation of the light beam spot from a target track and a tracking drive circuit for driving the tracking actuator according to the output of the track error detection circuit In an access control device for an optical disk device for moving to a position, at least a lens position sensor for detecting the position of the objective lens of the optical pickup, and vibration of the objective lens controlled according to the output of the lens position sensor. Vibration suppression that outputs a signal that suppresses And an access control device that suppresses the vibration of the objective lens by supplying the output of the lens vibration suppression circuit to the tracking drive circuit for a predetermined period immediately before and after the transition to the tracking control after seek. Is.

[0018]

When the seek control is switched to the tracking control, the output of the tracking control circuit and the output of the lens vibration suppressing circuit are supplied to the tracking drive circuit that drives the tracking actuator. That is, the objective lens is controlled not only by the tracking control circuit but also by the output of the lens position sensor, and the characteristics of the control system including the tracking drive circuit, the tracking actuator, and the objective lens have good damping. Therefore, even if a noise signal applied from the outside of the control system, such as acceleration, is applied, the control system does not become vibrating, and therefore the objective lens does not vibrate significantly, and stable tracking control can be achieved. I can.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the access control device of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing an embodiment of the access control device of the present invention. FIG. 2 is a diagram illustrating an example of the lens vibration suppression circuit. In FIG. 1, elements corresponding to those in FIG. 3 used in the description of the conventional technique are designated by the same reference numerals, and the description thereof will be omitted. Further, since the outline of the access control sequence has already been described, the description thereof will be omitted here.

The operation sequence of the access control system when recording / reproducing data at the target address on the disk is as follows: step 1 rotation control step 2 focus pull-in step 3 focusing step 4 track pull-in step 5 tracking step 6 seek step 7 track jump step 8 It is already mentioned that it is re-execution.

In FIG. 1, the output TE, that is, the tracking error signal, of the track error detection circuit 4 is the MPU 12, the tracking control circuit 13, and the track jump control circuit 1.
Applied to 3A. The output LC of the lens position sensor 6 that detects the position of the objective lens 3L is applied to the slider control circuit 14, the lens hold circuit 7A, and the lens vibration suppression circuit 7B that suppresses the vibration of the objective lens. The output terminal of the lens vibration suppression circuit 7B is connected to one terminal 70 of the switch 24, and the other terminal 71 of the switch 24 is connected to the input terminal of the tracking drive circuit 5.

As already mentioned, the switches 15A, 1
Each connection relationship of 6A is controlled by the MPU 12. For example, at the time of rough seek, the terminal 61 is connected to the terminal 64, the terminal 65 is connected to the terminal 67, the slider 18 is transferred at high speed, and when the target position is reached, the terminal 65 is connected to the terminal 66. The slider 18 is stopped in a short time. Terminal 6 during fine seek
5 is connected to the terminal 68, and the terminal 61 is connected to the terminal 63. During tracking control, the terminal 65 is connected to the terminal 68.
The terminals 61 are connected to the terminals 62, respectively.

In FIG. 1, at the time of shifting to tracking control, that is, at the time of shifting from step 4 to step 5, the switch 24 is closed, and the tracking drive circuit 5 includes the tracking control circuit 13 and the lens vibration suppressing circuit. 7B and controlled. The lens vibration suppression circuit 7B includes a differential element and a non-linear amplifier, an example of which is shown in FIG. FIG. 2 is a diagram illustrating an example of the lens vibration suppression circuit. As shown in the figure, the lens vibration suppression circuit 7B includes a differential element including a capacitor C1, resistors R1 and R2, an amplifier AP, and diodes d1 and d.
It is composed of two non-linear elements.

The input / output characteristic of the lens vibration suppressing circuit 7B shown in FIG. 2 is such that the amplification degree becomes larger and the phase advances in the vicinity of a predetermined frequency as compared with the low frequency region, and control including a tracking actuator is performed. The stability of the closed loop characteristic of the system is increased. When the output of the lens position signal LC from the lens position sensor 6 becomes large, that is, when the objective lens 3L largely deviates from a predetermined position, the amplification degree of the lens vibration suppressing circuit 7B becomes large and the objective The force for returning the lens 3L to the predetermined position is increased. When the displacement of the objective lens becomes small, the diodes d1 and d2 do not conduct and the normal operation is resumed.

In FIG. 1, the tracking control circuit 13 is provided for controlling the laser beam spot so as to follow the center of the track, whereas the lens vibration suppressing circuit 7B is for tracking control. This is provided in order to suppress unnecessary vibration of the objective lens when shifting to (4) and to stably shift to tracking operation. Therefore, the output of the lens vibration suppression circuit 7B is supplied to the tracking drive circuit 5 only for about 10 ms, for example. The control of this timing is realized by controlling the opening / closing of the switch 24 by the output of the MPU.

[0026]

According to the access control device of the present invention, even if a mechanical shock or the like is applied to the optical disk device, the seek mode is stably switched to the tracking control mode, and the light beam spot on the target track is changed. The positioning is performed reliably, and the access time of the optical disk device can be shortened.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an access control device of the present invention.

FIG. 2 is a diagram showing an example of a lens vibration suppression circuit.

FIG. 3 is a diagram showing an example of a conventional access control device.

[Explanation of symbols]

 2 ... Optical pickup 3 ... Tracking actuator 3L ... Objective lens 4 ... Track error detection circuit 5 ... Tracking drive circuit 6 ... Lens position sensor 8 ... Slider speed control circuit 9 ... Slider drive circuit 10 ... Optical disk 12 ... Microprocessor 13 ... Tracking control Circuit 13A ... Track jump control circuit 14 ... Slider control circuit 15A, 16A, 24 ... Switch 17 ... Slider position control circuit 18 ... Slider 20 ... Linear encoder 21 ... Coarse motor 23 ... Photodiode 25 ... Demodulator LC ... Lens position signal TE: tracking error signal

Claims (1)

[Claims] 1. An optical pickup for recording and reproducing information on an optical disc having a circular information recording track, a tracking actuator for controlling a light beam spot on the optical disc to follow a target track, and the light beam. A track error detection circuit that detects a deviation of the spot from the target track and a tracking drive circuit that drives the tracking actuator according to the output of the track error detection circuit are provided to move the light beam spot to the target position. And a lens position sensor for detecting the position of the objective lens of the optical pickup,
A lens vibration suppression circuit that outputs a signal that suppresses the vibration of the objective lens that is controlled according to the output of the lens position sensor, and the lens vibration suppression circuit for a predetermined period immediately before and after the transition to the tracking control after seek. The access control device is characterized in that the vibration of the objective lens is suppressed by supplying an output to the tracking drive circuit.