JPH064989A - Optical disk device - Google Patents

Abstract

PURPOSE:To provide a highly precise position control even when a low performance servo control system and an optical pickup are used by changing the relative loading position of an optical disk on a spindle motor. CONSTITUTION:A disk deviation detector 22 which detects the eccentricity and the wobbling surface of an optical disk 1 and outputs signals and a position change signal generator 23 are provided. The detector 22 detects a maximum amount of eccentricity of the disk 1 including the eccentricity of a spindle motor 2 from the size of tracking error signals while a tracking servo is turned on. One revolution of the disk 1 is equally divided by reference pulses, the position of the maximum eccentricity of the disk 1 is judged and the position at which the maximum amount of eccentricity is generated is outputted to the generator 23. The generator 23 outputs the signal which shows the position change to an automatic loading mechanism 3. The mechanism 3 unloads the disk 1 from the motor 2 after the motor 2 stops, rotates the motor 2 with prescribed number of reference pulses and again reloads the disk 1 onto the motor 2 so as to change the relative position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device for recording or reproducing information by light.

[0002]

2. Description of the Related Art In recent years, a technique for recording and reproducing an information signal using light has made remarkable progress. An optical disc, which is a recording medium used in an optical disc device, has a higher recording density and is capable of large-capacity recording than a magnetic disc, but since the track pitch is as small as 1 to 2 μm, a target track on the optical disc irradiated from the objective lens. Must be positioned with high precision. However, since the rotating optical disc is displaced due to surface wobbling or eccentricity, highly precise focus servo and tracking servo control techniques are required. Generally, an objective lens that focuses or focuses laser light is mounted on a pickup, and a coil actuator performs a minute servo operation for focusing the objective lens, and a linear motor roughly moves the optical pickup in the radial direction of the optical disc. The two-step servo method is widely used.

A conventional optical disk device will be described below with reference to the drawings. As shown in FIG. 5, the conventional optical disc apparatus has an automatic loading mechanism 3 for mounting or dismounting the inserted optical disc 1 on or from the spindle motor 2, and the optical pickup 4 is fixed for condensing light on the optical disc 1. An optical system, a focus coil 5 for performing a minute servo operation for focusing the objective lens, a tracking coil 6, and a linear motor 7 for moving a light spot in the radial direction of the optical disc 1 are integrated.

Further, a focusing drive circuit 8 and a tracking drive circuit 9 are used to pass control signals to the focus coil 5 and the tracking coil 6, respectively.

The operation of the conventional optical disk device configured as described above will be described below.

First, a focus error signal output indicating the relative positional deviation amount between the light spot output from the optical pickup 4 and the surface of the optical disc 1 is obtained from the focusing drive circuit 8 to drive the focus coil 5 to drive the focus error signal. Operates so that it becomes zero. Further, the tracking drive circuit 9 drives the tracking coil 6 by the tracking error signal indicating the deviation amount of the light spot output from the optical pickup 4 from the track position, and operates so that the tracking error signal becomes zero.

Next, as shown in FIG. 6, the optical pickup 4
The light flux emitted from the semiconductor laser 10 is converted into a parallel light flux by the collimator lens 11, transmitted through the light beam splitter 12, further reflected by the flip-up mirror 13, and then incident on the objective lens 14 to condense the objective lens 14. An image is formed on the recording surface of the optical disc 1 by. Data is recorded on the recording surface by the light thus modulated by the modulated light. Next, the reflected return light from the recording surface is again picked up by the objective lens 14 and guided to the photodetector 15 side, and the light incident on the photodetector 15 is appropriately processed to reproduce the recording signal and focus the light. An error signal and a tracking error signal can be detected. There are several methods for detecting the focus and tracking error signals. Here, an optical disk device using the astigmatism method for focusing and the push-pull method for tracking will be described. First, focusing will be described. The light beam returning from the recording surface of the optical disk 1 is separated by the light beam splitter 12 toward the photodetector 15 side. A condenser lens 16 and a cylindrical lens 17 are arranged in the optical path to the photodetector 15. The return light flux made substantially parallel by the condenser lens 16 is condensed on the photodetector 15, and the cylindrical lens 17 causes astigmatism, which is an aberration on the optical axis. The pattern of this astigmatism is an elliptical pattern as shown in FIG. 7 (a) due to focusing and defocusing on the recording surface of the objective lens,
It changes into a perfect circle pattern. Photodetector 1 divided into four
5 is rotated and installed on an axis relative to the generatrix direction of the elliptical pattern by 45 °. By taking the differential output of the sum of the four detectors in the diagonal direction, the characteristics of the focus error (hereinafter abbreviated as FE) signal associated with the objective lens defocusing as shown in FIG. 7B can be obtained. .
The focus servo is operated by feeding back this FE signal to the focus coil 5.

Next, the tracking operation will be described with reference to FIG. As shown in FIG. 8A, the light spot imaged on the recording surface generates + 1st-order and -1st-order diffracted light on the guide track, and the diffracted light and the 0th-order diffracted light that is regular reflection light are detected by the photodetector. On the surface of No. 15, some of them interfere with each other and the light intensity decreases. That is, +1, -1, and 0
Interfering portions are formed at the line-symmetrical positions with respect to the 0th-order diffracted light as the center. When the imaging light spot is located at the center of the recording track, the sum of the light intensities of the two areas with the line of line symmetry as the boundary becomes equal. Further, when the image forming light spot deviates from the above-mentioned central portion, the balance of the sum of the light intensities of the two areas is lost, and the amount of this disintegration, that is, the differential signal of the light intensities, becomes the track error signal.
FIG. 8B shows the characteristic of the tracking error signal due to this track shift. Also, every time the track is crossed, a sinusoidal tracking error (hereinafter abbreviated as TE) signal as shown in FIG. 8B is generated. Focusing and tracking control are performed by the FE signal and the TE signal as described above, so that positioning control is performed by following surface deviation or eccentricity of the optical disc.

[0009]

However, in the above-mentioned conventional configuration, when the surface deviation direction 19 or the eccentric direction 18 of the optical disk 1 and the spindle motor 2 coincide with each other as shown in FIG. Although it is the maximum, the optical pickup 4 needs to follow the maximum amount of surface deviation and the maximum amount of eccentricity, which is the sum of the amount of surface deviation and the amount of eccentricity of the spindle motor 2 and the optical disc 1, and to perform stable position control. However, the high-performance servo control system and the optical pickup 4 need to be designed, and the design margin is small.

The present invention solves the above-mentioned conventional problems. As shown in FIG. 9, the optical disk 1 is placed at the optimum position such that the surface runout direction 21 or the eccentric direction 20 of the optical disk 1 and the spindle motor 2 are opposite to each other. By mounting the spindle motor 2 and the spindle motor 2, it is possible to perform high-precision position control even when using a servo control system and an optical pickup, which have lower performance than the conventional optical disk device, and to allow a large design margin. The purpose is to provide.

[0011]

In order to achieve the above object, an optical disk apparatus of the present invention is provided with an automatic loading mechanism for mounting or removing an optical disk of an inserted exchangeable medium on a spindle motor, and an eccentricity or surface of the optical disk. A disc deviation detector that detects a shake and outputs a detection signal, and a position change signal generator that outputs a change position signal indicating the position where the relative position of chucking of the optical disk and the spindle motor are changed by the detection signal are provided. is doing.

[0012]

According to the present invention, in the above-mentioned structure, the relative position where the optical disk and the spindle motor are mounted is changed by detecting the eccentricity or surface deviation of the rotating optical disk and reducing the surface deviation or eccentricity of the optical disk. Even if a servo control system and an optical pickup having lower performance than those of the optical disk device are used, highly accurate position control is possible, and a large design margin can be secured for each.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the optical disk apparatus of this embodiment has a spindle motor 2 for mounting and rotating an optical disk 1, and an optical pickup 4 has a fixed optical system for focusing light on the optical disk 1. A focus coil 5 for focusing the objective lens, a tracking coil 6, and a linear motor 7 for moving the light spot in the radial direction of the optical disc 1 are integrated. Further, the focusing drive circuit 8 operates the focus coil 5 by the focus error signal output from the optical pickup 4 so that the focus error signal becomes zero. The tracking drive circuit 9 drives the tracking coil 6 by the tracking error signal output from the optical pickup 4 so that the tracking error signal becomes zero. The configuration of the optical pickup 4 and the focusing and tracking operations are the same as those described in the conventional example. Next, as a feature of this embodiment, a disc deviation detector 22 for detecting eccentricity or surface deviation of the optical disc 1 and outputting a detection signal and a position change signal generator 23 are newly provided, and the optical disc 1 and the spindle motor are detected by these detection signals. A change position signal indicating the position for changing the relative position of chucking 2 is output. The automatic loading mechanism 3 automatically mounts the inserted optical disc 1 on the spindle motor 2, and further changes the relative positions of the optical disc 1 and the spindle motor 2 by a change position signal.

Next, the structure and operation of the automatic loading mechanism 3 will be described with reference to FIGS. 2 (a), 2 (b) and 2 (c). When the cartridge 24 containing the optical disk 1 is inserted into the main body 25 as shown in FIG. 2A and the cartridge 24 is completely inserted into the main body 25 as shown in FIG. 2B, the shutter of the cartridge 24 is released. Is opened. Then, as shown in FIG. 2C, the cartridge 24 is automatically lowered by a mechanism (not shown), and the optical disk 1 is mounted on the spindle motor 2.

When the change position signal is received, the optical disk 1 is detached from the spindle motor 2 and the cartridge is held at the position shown in FIG. 2B. Then, after the correction for changing the relative position is completed, the cartridge 24 is lowered again as shown in FIG. 2C, and the spindle motor 2 and the optical disk 1 are mounted.

The operation of the optical disk device configured as described above will be described below. First, the spindle motor 2 rotates with the inserted optical disk 1 mounted, and the eccentric direction as shown in FIG. 3A when the optical pickup 4 follows the target position by the above-mentioned servo operation. When the optical disc 1 and the spindle motor 2 are provided with 26 and 27, a tracking error signal is generated when a track is crossed due to eccentricity as shown in FIG. 3B when the focus servo is turned on and the tracking servo is turned off. To do. The dense portion of the waveform of the error signal is where the eccentric component is large. Therefore, the disc deviation detector 22 detects the magnitude of the current flowing through the tracking coil 6 in accordance with the magnitude of the tracking error signal in the state where the tracking servo is turned on, so that the optical disc including the eccentricity of the spindle motor 2 is also detected. The maximum eccentricity amount of 1 is detected. Then, as shown in FIG. 3C, one rotation of the optical disc is equally divided by m reference pulses, and the maximum eccentricity amount is determined by which position of the optical disc the maximum eccentricity amount depends on at which reference pulse. It is determined whether or not it has been detected, and a detection signal indicating the position where the maximum eccentricity has occurred is output to the position change signal generator 23. Further, for example, an encoder pulse used for rotation control of the spindle motor 2 can be used as the above-mentioned reference pulse. When the detection signal indicates that the eccentricity amount is detected at the nth reference pulse, the position change signal generator 23 outputs n
A position change signal indicating the (n + k) th position to which the k-th reference pulse having the preset position is added is output. When the spindle motor 2 is stopped by the automatic loading mechanism 3 by the position change signal, the optical disk 1
Is held in a state of being detached from the spindle motor 2, the spindle motor 2 is rotated by k reference pulses, and then the optical disk 1 and the spindle motor 2 are mounted again to change the relative position. By repeating the above-described operation, the optical disc 1 and the spindle motor 2 can be mounted at positions where the surface deviation directions or the eccentric directions 28 and 29 are opposite to each other as shown in FIG. 4, and the surface deviation amount and the eccentric amount can be reduced. can do. For example, the above operation is repeated until (n + k) makes one rotation and exceeds the first n-th position,
The maximum eccentricity of the optical disc at each position is detected. Then, by the above-mentioned automatic loading mechanism 3, the spindle motor 2 and the optical disk 1 are mounted at the position showing the minimum value in the detected maximum eccentricity amount, and the servo operation is performed.
Alternatively, when the maximum amount of eccentricity of the optical disc 1 is smaller than the preset amount of eccentricity that satisfies the servo performance in advance, the above operation is ended and the servo operation is performed at the mounting position.

Similarly to the detection of the eccentricity, the detection of the surface deviation is performed by detecting the magnitude of the current flowing through the focus coil 5 in accordance with the magnitude of the focus error signal with the focus servo turned on. The maximum surface deviation of the optical disk 1 including the surface deviation of the spindle motor 2 is detected. Then, the automatic loading mechanism 3 operates similarly to the operation at the time of eccentricity, and it becomes possible to mount the optical disk 1 and the spindle motor 2 at the position where the surface deviation is the minimum. Further, by simultaneously performing the above-described operations for the eccentricity and the surface deviation of the optical disk 1, it is possible to perform the servo operation at the position where the eccentricity and the surface deviation are small.

[0019]

As is apparent from the above embodiments, according to the present invention, an automatic loading mechanism for loading or unloading an inserted optical disk of a removable medium to or from a spindle motor, and an eccentricity or surface wobbling of the optical disk are detected. By providing a disc deviation detector that operates and a position change signal generator that outputs a change position signal indicating a position for correcting the relative position of chucking of the optical disc and the spindle motor, servo control with lower performance than the conventional optical disc device is provided. Even if a system and an optical pickup are used, highly accurate position control can be performed, and an excellent optical disk device capable of ensuring a large design margin for each can be realized.

[Brief description of drawings]

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

2A is a sectional view of an automatic loading mechanism according to an embodiment of the present invention. FIG. 2B is a sectional view of an automatic loading mechanism according to the embodiment. FIG. 2C is a sectional view of an automatic loading mechanism according to the embodiment.

FIG. 3A is an operation explanatory diagram of the optical disc device according to the embodiment of the present invention. FIG. 3B is an operation waveform diagram of the optical disc device according to the embodiment. FIG. 3C is a reference pulse diagram of the optical disc device according to the embodiment.

FIG. 4 is an operation diagram of the optical disc device according to the embodiment.

FIG. 5 is a block diagram of a conventional optical disc device.

FIG. 6 is a block diagram of a main part of a conventional optical pickup unit.

FIG. 7 is an operation explanatory view of the optical pickup section.

FIG. 8 is an operation explanatory view of the optical pickup section.

FIG. 9 is an operation explanatory diagram of the optical disc device.

[Explanation of symbols]

 1 Optical Disc 2 Spindle Motor 3 Automatic Loading Mechanism 4 Optical Pickup 8 Focusing Drive Circuit 9 Tracking Drive Circuit 15 Photodetector 22 Disc Deviation Detector 23 Position Change Signal Generator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Muraoka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. An automatic loading mechanism for loading or unloading an inserted optical disk of a replaceable medium to or from a spindle motor, and the spindle motor for loading and rotating the optical disk, irradiating a light spot on the optical disk, The reflected light or transmitted light is detected by a photodetector to control the position of the light spot on the optical disc, the information signal is recorded / reproduced, the eccentricity or surface wobbling of the optical disc is detected, and a detection signal is output. And a position change signal generator that outputs a change position signal indicating a relative position where the optical disk and the spindle motor are mounted according to a detection signal. The change position signal causes the optical disk and the spindle motor to move. An optical disk device that can change the mounting position.