JPH04162255A - Optical disk device - Google Patents

Abstract

PURPOSE:To remove eccentricity of an optical disk by finding the eccentricity of the disk on the basis of a track error signal obtained from an optical head and moving an eccentricity removing section from the central axis by the found eccentricity after the eccentricity removing section is brought into contact with the outermost peripheral section of the disk. CONSTITUTION:This optical disk device is provided with an eccentricity removing section 6 which is brought into contact with the outermost peripheral section of an optical disk 1 and moves the disk 1 in the radial direction, driving section 5 which moves the section 6, drive circuit 4 which drives the section 5, optical head 2, filter 3, and track servo circuit 10. The head 2 and filter 3 constitute an eccentricity detecting means for optical disks 1 and the filter 3 extracts sine waves corresponding to the full circumference of the disk 1. The circuit 4 brings the eccentricity removing tool 6 connected to the section 5 into contact with the outermost side face of the disk 1 and pushes the outermost side face of the disk 1 so that the signal obtained by the filter 3 becomes zero. Therefore, the center of the disk 1 becomes coincident with the center of a rotating shaft 9 and the eccentricity of the disk 1 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc device that records, reproduces, and erases information using laser light.

[Conventional technology]

Optical disk recording and reproducing systems using laser light are capable of recording and reproducing large amounts of information, and because they allow contactless and high-speed access, they have begun to be put into practical use as large-capacity memories. Optical discs are classified into read-only types known as compact discs and laser discs, write-once types that can be recorded by the user, and rewritable types that can be repeatedly recorded by the user. The rewritable type is expected to be used as an alternative to magnetic disks as external memory for computers, or as document and image files.

The method for recording and reproducing information on an optical disk is: - When fishing on a boat, a laser beam is irradiated onto an optical disk rotating at high speed, and the laser beam is made to follow a guide groove (hereinafter referred to as a pre-group) carved in a spiral shape inside the optical disk. Record and play back information. In the conventional method, the laser beam is focused on the recording film of the disk and moved in the radial direction of the disk so that the laser beam follows the pre-group. Furthermore, the eccentricity of the disk has been eliminated only by the mechanical precision of the disk rotating section and the disk clamping section.

[Problem to be solved by the invention]

However, when moving the laser beam in the radial direction of the disk so that the laser beam follows the pre-group of the optical disk, there are two methods: moving the condenser lens 14 using the magnet coil 13 as shown in FIG. There is a method of moving the laser beam 16 with a galvanometer mirror 17 as shown in the figure, but in either case the tracking range is 1100.
II, and could not follow the eccentricity of the disk exceeding 100 bonds. Also, even if 100μ
- If the disk is rotating at high speed even with eccentricity below, it cannot be tracked due to the spring constant of the spring 15 supporting the condenser lens 14 and galvano mirror 17, or the weight of the condenser lens 14 and galvano mirror 17. was there. If the laser beam 16 cannot follow the pre-group of the disc, it will be impossible to read or write information recorded on the disc, and the optical disc device will no longer function as an optical disc device.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical disc device that can solve the above-mentioned drawbacks and minimize the eccentricity of the optical disc when the optical disc device is mounted.

Another object of the present invention is to provide a method for removing eccentricity of an optical disk using this optical disk device.

[Means to solve the problem]

The present invention provides an optical disc device that records, reproduces, and erases information using a laser beam, and includes: an eccentricity remover that contacts the outermost circumference of an optical disc and moves the optical disc in a radial direction; and a drive circuit that moves the eccentricity remover. and eccentricity detection means for detecting the eccentricity of the optical disc and controlling the drive circuit so that the eccentricity error signal becomes zero.

The present invention also provides a method for removing eccentricity of an optical disk using the optical disk device, characterized in that the eccentricity removing section is brought into contact with the optical disk and the optical disk is moved in the radial direction so that the eccentricity error signal becomes zero.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of an optical disc device according to the present invention. This optical disk device includes an eccentricity removing section 6 that contacts the outermost circumference of the optical disk 1 and moves the optical disk 1 in the radial direction, a drive section 5 that moves the eccentricity removal section 6, and a drive circuit that moves the drive section 5. 4, an optical head 2, a filter 3, and a track servo circuit 10. In addition, 8 is a clamp part which clamps the optical disc 1, 9 is a rotating shaft, and 7 is a rotating motor.

Note that the optical head 2 and the filter 3 constitute an eccentricity detection means of the optical disc.

Since the eccentric remover 6 is a part that comes into direct contact with the outermost peripheral side of the rotating disk 1, it is preferable that the shape is cylindrical as shown in Fig. 2 so that it can idle, and that it is made of a material that will not damage the disk. . Further, the eccentricity remover 6 is attached to the drive section 5, and can be moved toward the center of the disk by the power of the drive section 5. A voice coil, a near motor, or the like is used as a power source for the drive unit 5. As shown in FIG. 3, the disc clamping part 8 has a rotary shaft 9 whose diameter is approximately 100 μm smaller than the inner diameter of the center hole 18 of the disc 1, and the outermost side surface of the optical disc l is clamped with an eccentric remover 6.
When pressed, the disk 1 is deviated from the rotating shaft 9, but the spring 15 is held down to such an extent that the disk 1 will not be deviated from the rotating shaft 9 under the rotational torque of the motor 7.

When the optical disk 1 is mounted in an optical disk device, the disk is rotated, and the laser beam emitted from the optical head 2 is caused to follow the pre-group of the optical disk 1, a track error signal is obtained from the optical head 2. If there is eccentricity in the optical disc itself or if eccentricity occurs when the optical disc is loaded into an optical disc device, the track error signal for the disc circumference as shown in Figure 4(a)
A periodic sine wave is ordered. The larger the eccentricity of the disk, the wider the difference between the peaks and valleys of the sine wave as shown in Figure 4(b), and the smaller the eccentricity is, the greater the difference between the peaks and valleys of the sine wave as shown in Figure 4(C). The difference from the trough becomes smaller.When the eccentricity disappears, no sine wave is generated as shown in FIG. 4(d).Returning to the explanation of FIG. 1.

The optical disc 1 is mounted in an optical disc device, the disc is rotated at low speed, and the laser beam emitted from the optical head 2 is made to follow the pregroup of the optical disc 1. The rotational speed of the optical disc is preferably 10 rpm to 1100 rpm. Next, the track error signal obtained from the optical head 2 is passed through a filter 3 to extract a sine wave of one period with respect to the circumference of the disk. Based on the sine wave obtained by the filter 3, the eccentricity remover 6 connected to the drive unit 5 in the drive circuit 4 is brought into contact with the outermost side surface of the disk, and the signal obtained by the filter 3 is further reduced to zero. By pushing the outermost side surface of the disk so that the optical disk 1 is displaced from the rotation axis 9, the center of the optical disk and the center of the rotation axis are aligned, and eccentricity is eliminated. Note that a normal trunking operation is performed by a track servo circuit 10 to which a track error signal is input via a filter 3 outputting a track servo signal, thereby moving the optical head 2.

It is desirable to perform the eccentricity removal operation described above before reading or writing information to or from an optical disk.

Even if there is an eccentricity of 100 μm or more between the optical disc 2 and the rotating shaft 9, if the eccentricity removal work is started at the same time as the laser beam emitted from the optical disc 2 follows the pre-group of the optical disc 1, The problem that the emitted light from the optical head 2 cannot fully follow the pre-group of the optical disc 1 does not occur.

If you try to remove all the eccentricity of the disk during one rotation of the disk, the impact on the disk may become large, so remove the eccentricity little by little while the disk rotates multiple times until the eccentricity becomes zero. At that point, the optical disc is rotated to the number of rotations necessary for recording and reproducing information. The sine wave of one period with respect to the circumference of the disk obtained from the optical head is
As shown in FIG. 5, the value of the eccentricity of the disk on the straight line A connecting the center 11 of the rotating shaft 9 and the laser beam emitting section 12 of the optical head 2 is shown, so that the eccentricity removing section 8 and the optical disk l
It is desirable that the contact point be at point B or point 0, where the extension of straight line A and the outer peripheral edge of optical disc 1 intersect.

〔Effect of the invention〕

As explained above, in the present invention, the optical disc device is equipped with an eccentricity removing unit that uses power to contact the outermost circumference of the optical disc and move the disc in the radial direction, and also detects the tracking error signal obtained from the optical head. Then, the eccentricity of the disk is determined, the eccentricity removing part is brought into contact with the outermost circumference of the disk, and pressure is applied in the radial direction to move the optical disk toward the center axis by the amount of eccentricity of the disk obtained based on the track error signal. By moving the optical disk further, eccentricity of the optical disk can be removed.

Therefore, the burden of making the laser beam emitted from the optical head follow the pre-group of the optical disk is reduced.
Provided is a highly reliable optical disc device that can stably record, reproduce and erase information even when the optical disc rotates at high speed, and solves the problem of not being able to record, reproduce and erase information due to eccentricity of the disc. There is an effect that it can be done.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of an optical disc device, Fig. 2 is a diagram showing an optical disc eccentricity removing section, Fig. 3 is a diagram showing an optical disc clamp section, and Fig. 4 is a diagram showing a track error signal obtained from an optical head. FIG. 5 is a diagram showing the position where the optical disc eccentricity remover and the optical disc are brought into contact, and FIGS. 6 and 7 are schematic diagrams of main parts of a conventional optical disc device. 1... Optical disc 2... Optical head 3... Filter 4... Drive circuit 5... Drive unit 6... Eccentricity remover 7... ... Rotating motor 8 ... Clamp section 9 ... Rotating shaft 10 ... Trunk servo circuit 11 ... Center of rotating shaft 12 ... Laser light emitting section 13... Magnet coil 14... Condensing lens 15... Spring 16... Laser beam 17... Galvano mirror 18... Center hole agent Patent attorney Yoshiyuki Iwasa 1, optical disc 6. Oblique remover 2, optical head 73 rotation motor 3, filter 8. Clamp part 4, drive circuit
95 rotation axis 5,,% [U! 71 copies
10. Track servo circuit Fig. 1 6, bias) O#ff, tool Fig. 2 old, center hole Fig. 3 Fig. 4 1, optical disc 2. Optical head 1) 1 Center of rotation axis 12, laser light emitting part (Figure 5) 15, spring 16, laser light shoe (Figure 6)

Claims (2)

[Claims] (1) An optical disc device that records, reproduces, and erases information using a laser beam, comprising: an eccentricity remover that contacts the outermost circumference of an optical disc and moves the optical disc in a radial direction; and a drive circuit that moves the eccentricity remover. 1. An optical disc device comprising: eccentricity detection means for detecting the eccentricity of an optical disc and controlling the drive circuit so that the eccentricity error signal becomes zero. (2) A method for removing eccentricity of an optical disk using the optical disk device according to claim 1, characterized in that the eccentricity removing section is brought into contact with the optical disk and the optical disk is moved in the radial direction so that the eccentricity error signal becomes zero. A method for removing eccentricity from an optical disc.