JPH041973A - Disk eccentricity measuring device and eccentricity adjusting device using this measuring device - Google Patents

Abstract

PURPOSE:To cope with a large eccentricity and also to measure the disk eccentricity with high accuracy by moving back and forth a reading means with a transfer means in response to the revolution of a disk and following an information track of the disk and measuring the eccentricity of the disk based on the moving amount of the transfer means. CONSTITUTION:A reading means 11 is provided to read the information on a disk 100 together with a transfer means 13 which moves back and forth the means 11 in response to the revolution of the disk 100 and following an information track of the disk 100, and a measuring means which measures the eccentricity of the disk 100 based on the moving amount of the means 13. In this case, the measured eccentricity is decided by the movable extent of the means 13 and the measuring accuracy is dependent on the positioning accuracy of the means 13. Thus, it is possible to cope with a large eccentricity and also to improve the measuring accuracy.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a disk eccentricity measuring device and an eccentricity adjusting device using the same, and particularly to a disk eccentricity measuring device for measuring the eccentricity of a disk rotated by a rotational drive means. The present invention relates to an eccentricity measuring device and a disk eccentricity adjusting device that corrects disk eccentricity based on the eccentricity measurement results.

[Prior Art] Conventionally, an eccentricity measuring device is known as a device for measuring the eccentricity of an optical disc in the manufacturing and inspection process of optical discs. Here, the reason why an optical disk is eccentric is that the center of the track groove formed on the surface of the disk, which is typified by a glass master disk such as an optical disk or magneto-optical disk or a disk substrate, and the center when the disk is mounted and rotated. This is because eccentricity of several tens of micrometers to several hundred micrometers occurs due to problems with the centering accuracy of disks in various manufacturing devices. The track grooves formed on the surface of the disk are usually called groups, and are specifically composed of recording grooves and optical pickup guide grooves, and their size may be, for example, a width of 0. 5 μm.

Sizes such as a pitch of 1.6 μm and a depth of 500 to 900 A are known. In addition, the conventional method for measuring the eccentricity of a group with respect to the center of rotation of the disk is as follows:
The following two are known.

That is, automatic focus control (hereinafter referred to as "focus servo") is performed using an optical pickup on the information track of the rotating disk, and the optical pickup 1. Kur,.

The track counting method measures the eccentricity of the disk by counting the number of disks that cross the track, and the track following control method (hereinafter referred to as ``tracking servo'') uses an optical pickup with a capacitive displacement sensor on the information track of the rotating disk. There is an optical pickup displacement measuring method in which the amount of displacement in the radial direction of the disk of the optical pickup is directly measured using a displacement meter.

Further, conventionally, there has been known a disk eccentricity adjusting device that measures the amount of eccentricity of a disk in the manufacturing inspection process of an optical disk and corrects the eccentricity of the disk based on the measurement result. In this disk eccentricity adjusting device, a spindle for rotating the disk to which the disk is attached is attached to an XY child table, and the eccentricity of the disk is corrected by moving the XY child table.

[Problems to be Solved by the Invention] As mentioned above, as a method for measuring the amount of eccentricity using a conventional disk eccentricity measuring device, the eccentricity of the disk can be determined by counting the number of optical pickups that cross the tracks of the rotating disk. track counting method to measure the amount;
There is an optical pickup displacement measurement method that uses an optical pickup with a capacitive displacement sensor to directly measure the amount of radial displacement of a rotating disk with a displacement meter.

However, among these methods, the track counting method has the problem that it is difficult to detect the direction in which the disk is eccentric. Since it is limited by the amount of possible displacement, there is a problem in that it cannot cope with cases where the eccentricity of the optical disc is large.

Further, as described above, there is conventionally known a disk eccentricity adjustment device that measures the eccentricity of the disk and corrects the eccentricity of the disk based on the measurement result. The disk eccentricity adjustment device measures and corrects the eccentricity of the disk by attaching the spindle to which the disk is attached to an XY child table and moving the XY child table, so the configuration of the device is The problem was that it was complicated and large-scale.

Therefore, the object of the invention according to the first claim is to provide a disk eccentricity measuring device that can cope with a large eccentricity and perform highly accurate measurement. An object of the invention is to provide a disk eccentricity adjustment device that has a simple configuration and is capable of highly accurate eccentricity adjustment.

[Means for Solving the Problem] The invention according to the first claim is a disk eccentricity measuring device for measuring the eccentricity of a disk rotated by a rotational drive means, the invention comprising a reading means for reading information on the disk. and a moving means for moving the reading means back and forth following the information track of the disk according to the rotation of the disk, and a measuring means for measuring the amount of eccentricity of the disk based on the amount of movement of the moving means. .

The invention in claim 2 is a disk eccentricity adjusting device that measures the eccentricity of a disk rotated by a rotational drive means, detects a correction reference position for correcting the eccentricity, and corrects the eccentricity of the disk, A reading means for reading information on the disk, a moving means for moving the reading means back and forth following the information track of the disk according to the rotation of the disk, and an amount of eccentricity of the disk based on the amount of movement of the moving means. a measuring means for measuring; a correcting means that moves integrally with the reading means and corrects the eccentricity of the disk by coming into contact with the periphery of the disk based on the measurement result of the measuring means; and correction reference position detection means for detecting a position in contact with the circumferential edge of the disk when the correction means corrects the eccentricity of the disk based on the correction means.

[Function] In the disk eccentricity measuring device according to the first aspect, the information on the disk is read by the reading means, and the reading means is moved back and forth by the moving means to follow the information track of the disk according to the rotation of the disk. Since the amount of eccentricity of the disk is measured by the measuring means based on the amount of movement of the moving means, the measured amount of eccentricity is determined by the amount of movement of the moving means, and the measurement accuracy is determined by the positioning accuracy of the moving means.

In the disk eccentricity adjusting device according to the second aspect, the information on the disk is read by the reading means, and the reading means is moved back and forth by the moving means to follow the information track of the disk according to the rotation of the disk. The amount of eccentricity of the disk is measured by the measuring means based on the amount of movement of the measuring means, and the correcting means that moves integrally with the reading means comes into contact with the circumferential edge of the disk based on the measurement result of the measuring means to correct the eccentricity of the disk, When the correction means corrects the eccentricity of the disk based on the reading signal from the reading means, the position in contact with the circumference of the disk is detected by the correction reference position detection means, so the spindle itself with the disk attached cannot be moved as in the conventional case. There's no need to do it.

[Embodiment of the Invention] FIG. 1 is a schematic diagram showing the configuration of an optical disk eccentricity measuring apparatus according to an embodiment of the present invention. Referring to FIG. 1, the optical disc eccentricity measuring device includes an optical pickup 11 for reading information on a disc 100, a support base 12 for supporting the optical pickup 11, and a support base 12 attached thereto. 11 in the radial direction of the disk 100, a slide stand 14 to which the slide 13 is movably attached, a mounting base 15 to which the slide stand 14 is attached, and an attachment base 15.
The tower 17 includes a spindle 16 attached to the spindle 16 for rotating the disk 100, and a tower 17 connected to the spindle 16 and having the disk 100 attached to the tip thereof.

As described above, in this embodiment, by moving the optical pickup 11 in the radial direction relative to the disk 100 by using the slide 13 via the support base 12, the amount of movement of the optical pickup 11 in the radial direction relative to the disk 100 is controlled by the slide 13. Since the amount of eccentricity that can be measured is determined by the amount of movement of 13, the amount of eccentricity that can be measured is not limited as in the conventional pickup displacement measurement method using an optical pickup with a capacitive displacement sensor, and it is possible to measure large amounts of eccentricity. Can correspond to Furthermore, as will be described later, since the eccentric direction can be easily detected, the problems encountered with the conventional track counting method do not occur.

FIG. 2A is a waveform diagram of a tracking error signal detected by the optical pickup shown in FIG.
This figure is a waveform diagram of the fundamental wave component of the tracking error signal shown in FIG. 2A. Further, FIG. 3 is a schematic diagram for explaining a method of measuring the amount of eccentricity using the eccentricity measuring device shown in FIG. 1. Next, a method for measuring eccentricity of an optical disk will be explained with reference to FIGS. 1 to 3. First, the disk 100 is rotated by the spindle 16.

Focus servo and tracking servo are applied by the optical pickup 11. In this state, a tracking error signal as shown in FIG. 2A is obtained from the optical pickup 11.

Only the fundamental wave component as shown in FIG. 2B is extracted from the tracking error signal shown in FIG. 2A using a low-pass filter or the like. Slide 1 based on this fundamental wave component
3 in the direction of canceling the fundamental wave component. As a result, the slide 13 moves to follow the eccentricity of the group of disks 100. Here, spindle 16
Its own eccentricity is extremely small and can be ignored.

In addition, high frequency components other than the fundamental wave component are detected by the optical pickup 1.
The operation of 1 itself is in charge. This type of control is called a two-stage control system, which is disclosed in, for example, 1982-82585 (Application No.) proposed by the applicant of the present invention. In this embodiment, eccentricity is measured using this method. The slide 13 is left in the state where the two-stage servo is applied, and the disk 100 is rotated once. At that time, the slide 13 moves back and forth according to the eccentricity of the group of disks 100. If the amount of movement of this slide is detected by a linear encoder (not shown), etc., 1 of the detected amount
The amount of /2 is the amount of eccentricity of the group of disks 100. Here, as shown in FIG.
0 rotation center is O, the maximum value of the position of the slide 13 when the disk 100 rotates once is a, and the minimum value is b
Then, the eccentricity of the group of disks 100 is expressed by the following equation.

la bl (1) In this way, in this example, the measured eccentricity is
Since it is determined by the moving distance of the
Since measurement accuracy depends on the positioning resolution of the slide 13, highly accurate measurement is possible by using a slide with high resolution positioning accuracy. The eccentric direction of the disk 100 is such that the rotation angle of the disk 100 is adjusted so that the optical pickup 11 is at the position a shown in FIG. It can be easily detected by detecting with a rotary encoder or the like (not shown).

FIG. 4 is a schematic diagram showing the configuration of a correction reference position detection device showing an embodiment of the present invention. Referring to Figure 4,
The correction reference position detection device detects the disc 10 by pressing the optical pickup 21 and the outer circumference of the disc 100.
a disk push pin 22 for correcting the eccentricity of 0; a support stand 23 for supporting the optical pickup 21 and the disk push pin 22; a slide 24 to which the support stand 23 is attached and moves in the radial direction of the disk 100; A slide stand 25 on which the slide 24 is movably installed, a mounting stand 26 on which the slide stand 25 is attached, a base part 27 attached on the mounting stand 26, and a disk integrally attached to the base part 27. 100.

5A and 5B are waveform charts for explaining a method of detecting a correction reference position by the correction reference position detection device shown in FIG. 4. FIG. With reference to Figures 4 to 5B,
Next, the operation will be explained.

First, the optical pickup 21 is used to move the slide 24 while applying focus servo (automatic focus control) to the disk 100. Note that, at this time, tracking servo (track following control) is not performed. After the slide 24 moves, the optical pickup 21 traverses the group of disks 100 until the disk push pin 22 comes into contact with the disk 100, so that the pickup output signal when the disk is stopped as shown in FIG. 5A is obtained.

When the slide 24 moves further and the disk push pin 22 comes into contact with the disk 100 and starts pushing the disk 100, the optical pickup 21 moves in synchronization with the disk 100. As a result, the optical pickup 21 does not cross the group of disks 100, and the pickup output signal shown in FIG. 5A during disk movement is obtained. In this way, a pickup output signal as shown in FIG. 5A is obtained, and the difference in this signal (frequency) is expressed as f
/v conversion (frequency/voltage conversion)
A signal as shown in Figure B is obtained, and the eccentricity correction reference position when correcting the eccentricity of the disk 100 can be accurately detected.

As described above, in this embodiment, there is no need to move the disk mounting portion itself in order to position the disk with high precision as in the conventional case, and the configuration of the apparatus is simplified.

FIG. 6 is a schematic diagram showing the configuration of an optical disk eccentricity adjusting device according to an embodiment of the present invention. Referring to FIG. 6, the optical disc eccentricity adjusting device includes an optical pickup 1,
A disk push pin 2 for correcting the eccentricity of the disk 100, a support stand 3 for supporting the optical pickup 1 and the disk push pin 2, and a support stand 3 are attached so that the disk 100 can be moved in the radial direction. a slide 4 installed on the slide 4, a linear encoder 5 on which the slide 4 is movably installed and for measuring the amount of movement of the slide 4, and a mounting base 6 on which the linear encoder 5 is attached;
A spindle 7 attached to the mounting plate 6 for rotating the disk 100, a rotary encoder 8 for detecting the rotation angle of the spindle 7, and a spindle 70.
It includes a turntable 9 that is attached to the tip of the rotating shaft and on which the disk 100 is placed. In this embodiment, by configuring as described above, the disk 100 can be
There is no need to place the spindle 7 itself on an X/Y table and move it, and the configuration of the apparatus can be simplified. The optical disk eccentricity adjusting device shown in FIG. 6 is also similar to the optical disk eccentricity measuring device shown in FIG.
It has a built-in optical disk correction reference position detection device shown in the figure, and it is possible to measure the eccentricity of the disk and detect the correction reference position with one device.
Furthermore, the disc 100 can be corrected based on it.

FIG. 7 is a schematic diagram for explaining an eccentricity correction method using the eccentricity adjusting device shown in FIG. 6. The eccentricity correction method will be described with reference to FIGS. 6 and 7. First, the measurement of the amount of eccentricity of the disk 100 is the same as the measurement method explained in FIGS. 1 to 3, so a description thereof will be omitted. After the amount of eccentricity of the disk 100 is measured by the optical pickup 1, the disk 100 is positioned in the eccentricity correction direction. That is, after stopping the rotation of the spindle 7, the disk 100 is positioned so that the rotation angle of the disk 100 is determined by a rotary encoder or the like when measuring the amount of eccentricity. This positioning method utilizes the sine wave output of the rotary encoder, and can perform accurate positioning by analog control using the linear waveform near the 0 cross section. These are disclosed, for example, in 1999-174517 (application number) proposed by the applicant of the present invention. After completing the positioning of the disk 100, the holding state of the disk 100 is released.

That is, the disk 10 provided on the turntable 9
Release the vacuum state of the chuck that is vacuum suctioning 0.

Next, the operation of correcting the eccentricity of the disk 100 will be explained. The disc 100 placed on the turntable 9 in a released state is pressed by the disc push pin 2 by the movement of the slide 4. Note that the position where the disc push pin 2 contacts the disc 100 is the fourth position mentioned above.
It can be detected by the same method as explained in FIGS. 5B to 5B.

Using this method, disc push pin 2 and disc 10
The eccentricity of the disk 100 can be corrected in the correct direction by detecting the zero contact point and making the amount of movement of the slide 4 from that point equal to the initially measured amount of eccentricity of the disk 100. That is, as shown in FIG. 7, if the center of the group is O' with respect to the 1'-1 rotation center O, then O'
The eccentricity of the disk 100 is corrected so that it overlaps with 0. In this way, in this embodiment, the disk 100
When adjusting the center of rotation and the eccentricity of the group, measurement is easy and the measurement range follows the amount of movement of the slide.
It is also possible to deal with cases where the eccentricity of the disk is large. Further, when correcting the eccentricity of the disk, there is no need to move the disk mounting portion, so the configuration of the apparatus is simplified, and moreover, it is possible to adjust the eccentricity with high accuracy.

[Effects of the Invention] According to the invention according to the first claim, the information on the disc is read by the reading means, and the reading means is moved back and forth by the moving means to follow the information track of the disc according to the rotation of the disc, By measuring the amount of eccentricity of the disk by the measuring means based on the amount of movement of the moving means, the measured eccentricity is determined by the amount of movement of the moving means, and the measurement accuracy is determined by the positioning accuracy of the moving means. By using a moving means with a large amount of displacement and high positioning accuracy, it has become possible to provide a disk eccentricity measuring device that can cope with a large amount of eccentricity and can perform highly accurate measurements.

According to the invention according to the second claim, the information on the disk is read by the reading means, the reading means is moved back and forth by the moving means following the information track of the disk according to the rotation of the disk, and the amount of movement of the moving means is The amount of eccentricity of the disk is measured by a measuring means based on the measurement result of the reading means, and a correction means that moves integrally with the reading means is brought into contact with the periphery of the disk based on the measurement result of the measuring means to correct the eccentricity of the disk. When the correction means corrects the eccentricity of the disk based on the read signal, the correction reference position detection means detects the position in contact with the circumference of the disk, thereby eliminating the need to move the spindle itself on which the disk is attached as in the conventional case. Therefore, it has become possible to provide a disk eccentricity adjusting device which has a simple configuration and is capable of highly accurate eccentricity adjustment.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of an optical disk eccentricity measuring device according to an embodiment of the present invention, FIG. 2A is a waveform diagram of a tracking error signal detected by the optical pickup shown in FIG. 1, and FIG. FIG. 2B is a waveform diagram of the fundamental wave component of the tracking error signal shown in FIG. 2A, FIG. Figure 4 is a schematic diagram showing the configuration of a correction reference position detection device according to an embodiment of the present invention;
Av! J and 5B are waveform diagrams for explaining the method of detecting the correction reference position by the correction reference position detection device shown in FIG. 4, and FIG. FIG. 7 is a schematic diagram showing the configuration, and is a schematic diagram for explaining an eccentricity correction method using the eccentricity adjusting device shown in FIG. 6. In the figure, 1 is an optical pickup, 2 is a disk push pin, 4 is a slide, 5 is a linear encoder, 7 is a spindle, 8 is a rotary encoder, 9 is a turntable,
11 is an optical pickup, 13 is a slide, 16 is a spindle, 17 is a tower 21 is an optical pickup, 22 is a disk push pin, 24 is a slide, and 100 is a disk. In each figure, the same reference numerals indicate the same or corresponding parts. Figure 2A Patent Applicant Konutn Co., Ltd.

Claims (2)

[Claims] (1) A disk eccentricity measuring device for measuring the eccentricity of a disk rotated by a rotation drive means, comprising: a reading means for reading information on the disk; and a reading means for reading information on the disk, and information on the disk according to the rotation of the disk. A disk eccentricity measuring device, comprising: a moving means for moving the reading means back and forth following a track; and a measuring means for measuring an amount of eccentricity of the disk based on the amount of movement of the moving means. (2) A disk eccentricity adjustment device that measures the eccentricity of a disk rotated by a rotary drive means, detects a correction reference position for correcting the eccentricity, and corrects the eccentricity of the disk, comprising information on the disk. a reading means for reading the information; a moving means for moving the reading means back and forth following the information track of the disk according to the rotation of the disk; and an eccentricity of the disk based on the amount of movement of the moving means. a measuring means for measuring the quantity; a correcting means that moves integrally with the reading means and corrects the eccentricity of the disk by coming into contact with the peripheral edge of the disk based on the measurement result of the measuring means; correction reference position detection means for detecting a position in contact with a peripheral edge of the disk when the correction means corrects the eccentricity of the disk based on a read signal from the reading means;
Disc eccentric adjustment device.