JP2003208737A - Apparatus and method for inspecting eccentricity of recording disk medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for inspecting eccentricity of a recording disk medium capable of detecting both the amount and direction of eccentricity present in the medium. <P>SOLUTION: The apparatus for inspecting eccentricity of a recording medium includes: a rotation drive section 20 for supporting and rotating an optical disk 100 with tracks at a prescribed interval on its signal face 101; an optical pickup 30 placed at a prescribed position with respect to the rotation center of a spindle motor 21 and generating a read signal DS on the basis of the intensity of a returned light of the signal face 101 on which a ray is emitted on the optical disk 100; and a controller 50 acting like an eccentricity detection means that detects the amount and direction of eccentricity of the optical disk 100 on the basis of: relative motion information obtained from the read signal DS resulting from a relative motion in a direction of the interval of tracks between the optical pickup 30 and the optical disk 100 caused by the eccentricity of the rotated optical disk 100; and an origin position signal 25s as rotary angle information of the optical disk 100. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eccentricity inspection device and an eccentricity inspection method for inspecting an eccentricity amount and an eccentric direction of a disk-shaped recording medium.

[0002]

2. Description of the Related Art For example, CD (Compact Disc), MD (M
ini Disc), MO (Magneto Optical disc), DVD (Dig
A disk-shaped recording medium called an optical disk such as an ital Versatile Disc) basically has a structure in which a reflective layer and a protective layer are formed on a signal surface formed on a substrate that transmits light. Recording of data on the signal surface is performed, for example, by forming irregularities such as pits and grooves along a track on a substrate according to the data. To reproduce the data recorded on the signal surface, for example, while the optical disk is placed on a rotary table and rotated, the optical pickup irradiates the signal surface with laser light through the substrate, receives the return light from the reflective layer, and outputs it. It is performed by converting into a signal.

[0003]

An optical disc is manufactured by forming a reflection film or a protective film on a substrate molded by a molding method such as injection molding. Due to the factors, eccentricity occurs in the optical disc. If the eccentricity of the optical disk is too large,
Since a problem such as a reading error of data recorded on the optical disc is likely to occur, it is necessary to accurately measure the eccentricity of the optical disc in the manufacturing process of the optical disc, and feed back this to suppress the eccentricity of the optical disc as much as possible.

Conventionally, in order to measure the amount of eccentricity of an optical disc, the optical disc is placed on a rotary table and rotated, and the operator measures the magnitude of radial deflection of the rotating optical disc using a microscope. However, in this measuring method, the measured value varies depending on the skill of the operator, and the eccentricity of the optical disk may not be accurately measured.

A technique for measuring the amount of eccentricity of an optical disc with higher accuracy is disclosed in, for example, Japanese Patent Application Laid-Open No. 11-162096. The technology disclosed in this publication places an optical disc on a rotary table, rotates the optical disc, arranges an optical pickup on the rotating optical disc, and detects the number of tracks crossed by the optical pickup per rotation of the optical disc. The amount of eccentricity of the optical disc is detected. However, with this technique, although it is possible to accurately detect the amount of eccentricity of the optical disc, there is a disadvantage that the direction of eccentricity cannot be detected. When correcting the eccentricity in the optical disk manufacturing process, it may be difficult to correct it unless the direction of the eccentricity is specified.

Recently, many optical discs having a plurality of signal surfaces have been proposed in order to increase the recording density. Although various methods of manufacturing an optical disc having a multilayered signal surface have been proposed, for example, it can be manufactured by bonding a plurality of substrates having signal surfaces formed thereon. In the optical disc formed by bonding the plurality of substrates, eccentricity may occur for each of the plurality of substrates. If the amount of eccentricity between the boards is large, when data is reproduced by the optical pickup,
When an optical pickup is moved from a track on one signal surface to a track on another signal surface, it is expected that problems such as difficulty in quick movement occur. Therefore, in order to suppress both the eccentricity of each board and the eccentricity of the boards,
It is necessary to specify the eccentricity amount and the eccentricity direction of each substrate.

The present invention has been made in view of the above problems, and an object thereof is to provide an eccentricity inspection apparatus and an eccentricity inspection method capable of detecting both the amount of eccentricity and the direction of eccentricity existing in a disk-shaped recording medium. To provide.

[0008]

DISCLOSURE OF THE INVENTION An eccentricity inspection device for a disk-shaped recording medium according to the present invention comprises a rotating means for holding and rotating a disk-shaped recording medium having tracks at predetermined intervals on a signal surface, and a rotation center of the rotating means. And a reading unit that is arranged at a predetermined position and that generates a read signal based on the intensity of the returning light from the signal surface of the light beam that irradiates the disc-shaped recording medium, and the eccentricity of the rotating disc-shaped recording medium. Based on the relative movement information obtained from the read signal of the reading unit by the relative movement of the track between the reading unit and the disc-shaped recording medium in the spacing direction, and the rotation angle information of the disc-shaped recording medium, And an eccentricity detecting means for detecting an eccentricity amount and an eccentric direction of the disk-shaped recording medium.

Preferably, the relative movement information is waveform data whose value changes periodically every time the reading means crosses a track, and the eccentricity detection means is formed by one rotation of the disk-shaped recording medium. The eccentricity amount is detected based on the obtained wave number of the waveform data and the track interval, and the eccentric direction is detected by associating the density of the waveform data with the rotation angle information.

In the disc-shaped recording medium eccentricity inspection method of the present invention, the disc-shaped recording medium having tracks at predetermined intervals on the signal surface is rotated, and the disc-shaped recording medium is arranged at a predetermined position with respect to the rotation center of the disc-shaped recording medium. A reading signal is generated by the reading means based on the intensity of the return light from the signal surface of the light beam applied to the signal surface, and is generated by the eccentricity of the rotating disk-shaped recording medium obtained from the reading signal of the reading means. An eccentric amount and an eccentric direction of the disc-shaped recording medium are detected based on relative movement information in the track spacing direction between the reading unit and the disc-shaped recording medium and rotation angle information of the disc-shaped recording medium. To do.

Preferably, the relative movement information is waveform data whose value changes periodically each time the reading unit crosses a track, and the relative movement information is obtained by one rotation of the disk-shaped recording medium. The eccentricity amount is detected based on the wave number and the track interval, and the eccentricity direction is detected by associating the rotation angle information with the density of the waveform data obtained by one rotation of the disk-shaped recording medium. .

In the present invention, when the disc-shaped recording medium is rotated by the rotating means and the center of the disc-shaped recording medium is eccentric from the rotation center of the rotating means, the disc-shaped recording medium makes an eccentric movement. Due to this eccentric movement, the reading means and the disk-shaped recording medium arranged at a predetermined position with respect to the center of rotation relatively move not only in the direction along the track but also in the track spacing direction. Due to this relative movement, the reading means traverses the track, and relative movement information is obtained from the read signal of the reading means. Based on the obtained relative motion information and the rotation angle information of the disc-shaped recording medium, the eccentric amount and the eccentric direction of the disc-shaped recording medium from the rotation center of the rotating means are specified.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a diagram showing a configuration of an eccentricity inspection device according to an embodiment of the present invention. In FIG. 1, the eccentricity inspection device 1 includes a rotation drive unit 20, an optical pickup 30, and a control device 5.
It has 0 and. The optical pickup 30 is an embodiment of the reading means of the present invention, the rotary drive unit 20 is an embodiment of the rotating means of the present invention, and the control device 50 is an embodiment of the eccentricity detecting means of the present invention. is there.

The rotary drive unit 20 includes a spindle motor 21.
, A rotation position detector 25, and a mounting member 23 connected to the output shaft 22 of the spindle motor 21. The spindle motor 21 is driven by the control device 50. The rotation position detector 25 generates a pulsed origin position signal every time the spindle motor 21 makes one rotation. In the present embodiment, the origin position signal 25s among these signals is output to the control device 50. An optical type is used for the rotational position detector 25, for example. Mounting member 2
The reference numeral 3 is fitted in the central hole 100h of the optical disc 100 to hold the optical disc 100 detachably. The mounting member 23 transmits the rotation of the output shaft 22 of the spindle motor 21 to the optical disc 100. As a result, the optical disc 100 rotates in the direction of arrow R about the output shaft 22 of the spindle motor 21.

FIG. 2 is a diagram showing an example of the structure of the optical pickup 30. As shown in FIG. 1, the optical pickup 30 is fixed on a base 31, and includes a laser light source 32, an optical system 33, an objective lens 34, and a photodetector 3.
It is equipped with 5. The laser light source 32 outputs the laser light L. As the laser light source 32, for example, a semiconductor laser such as a red laser or a blue laser is used. The output of the laser light source 32 is controlled by the controller 50.

The optical system 33 transmits the laser light L outputted from the laser light source 32 and guides it to the objective lens 34, and reflects the return light RL reflected by the optical disc 100 and passed through the objective lens 34 to detect the photodetector 35. Lead to.

The objective lens 34 transmits the laser light L output from the laser light source 32 to the signal surface 101 of the optical disc 100.
Converge on top.

The photodetector 35 receives the return light RL from the optical system 33, converts it into an electric signal corresponding to the intensity of the return light RL, and outputs this to the control device 50 as a read signal DS. For the photodetector 35, for example, a photodiode is used.

Here, an example of the structure of the optical disc 100 will be described with reference to FIGS. 3 and 4. As shown in FIG. 3, the optical disc 100 has a lead-in area 104 and a program area 103 in order from the inner circumference side to the outer circumference side.
And a lead-out area 105.

FIG. 4 is a view showing a sectional structure of a part of the optical disc 100. As shown in FIG.
Is a substrate 110 made of a transparent resin such as polycarbonate and having a plurality of concave pits P formed on its surface.
And a reflective film 111 made of a metal thin film such as aluminum formed on the substrate 110, and a protective film 112 formed on the reflective film 111. In addition,
The above-mentioned signal surface 101 is formed by the surface of the substrate 110 on which the pits P are formed. A pit P formed on the substrate 110 is a signal recorded on the optical disc 100. These pits P are arranged concentrically,
A track TR is composed of a row of pits P.
The interval between the tracks TR, that is, the optical disc 1
00 interval T between adjacent tracks TR in the radial direction
RP is equal.

FIG. 5 is a diagram for explaining a read signal DS output from the optical pickup 30 when the optical pickup 30 irradiates the optical disc 100 with a laser beam. FIG. 5A is a cross-sectional view of the optical disc 100 in the radial direction (direction in which tracks TR are spaced). For example, while moving the optical pickup 30 in the direction of the interval TRP of the tracks TR at a constant speed between the positions S1 and S2 shown in FIG.
When the laser light L is irradiated from the side toward the reflective film 111,
The return light RL received by the optical pickup 30 is intensity-modulated by the pit P. Therefore, the read signal DS output from the optical pickup 30 becomes a sine wave having the interval TRP of the tracks TR as one cycle. That is, the read signal DS changes periodically every time the optical pickup 30 crosses the track TR. As will be described later, by counting the number of waves included in the waveform data of the read signal DS, the number of tracks TR crossed by the optical pickup 30 can be detected.

The control device 50 shown in FIG. 1 includes A / D converters 51 and 52, a processor 53, and a ROM (Read Only).
Memory) 54 and RAM (Random Access Memory) 55
And a driver 56. The A / D converter 51 is a rotary position detector 2 attached to the spindle motor 21.
Origin position signal 2 consisting of analog signal output from 5
5s is converted into a digital signal according to the sampling signal sp input from the processor 53, and the converted signal 5
1s is output to the processor 53.

The A / D converter 52 converts the read signal DS consisting of an analog signal from the photodetector 35 into a digital signal according to the sampling signal sp input from the processor 53, and the converted signal 52s is processed by the processor. Output to 53. The sampling signal sp input to the A / D converter 52 is the same signal as the sampling signal sp input to the A / D converter 51.
Performs sampling in synchronization with the A / D converter 52.

The ROM 54 stores a program that defines the processing performed by the processor 53. RAM55 is
It stores various data necessary for the processing performed by the processor 53. The processor 53 comprehensively controls the control device 50. Specifically, the control includes rotation control of the spindle motor 21, calculation of an eccentric amount and an eccentric direction of the optical disc 100, which will be described later, output of various data to the display device 60, and the like.

The driver 56 supplies a drive current to the spindle motor 21 according to a control command from the processor 53.

The display device 60 displays various data output from the processor 53. In this display device 60,
For example, a liquid crystal display device or a CRT (Cathode Ray Tube) is used.

Next, a method of detecting the amount of eccentricity and the direction of eccentricity of the optical disc 100 using the eccentricity inspection device 1 having the above-described configuration will be described with reference to the flowchart shown in FIG.
First, the optical disc 100 is mounted on the spindle motor 21 (step S1).

Here, FIG. 7 is a diagram for explaining the amount of eccentricity and the direction of eccentricity existing on the optical disc 100.
In FIG. 7, a circle C indicated by a dotted line indicates a virtual reference position when the optical disc 100 has no eccentricity when the optical disc 100 is mounted on the mounting member 23 of the eccentricity inspection device 1. That is, the center 100 of the optical disc 100
c is the position of the optical disc 100 in a state where it coincides with the rotation center Ct of the spindle motor 21.

In FIG. 7, the center 1 of the optical disc 100
The distance between 00c and the rotation center Ct of the spindle motor 21 is Ea. The optical disk 100 has twice the distance Ea.
Is the amount of eccentricity. Further, an angle formed by a straight line SL connecting the center 100c of the optical disc 100 mounted on the spindle motor 21 and the rotation center Ct of the spindle motor 21 and the origin position OR in the rotation direction of the spindle motor 21 is α. The direction of the straight line SL with respect to the origin position OR is the eccentric direction of the optical disc 100. The center 100c of the optical disc 100 has a circumference K having a radius of the distance Ea.
It is located at a position rotated from the origin position OR in the counterclockwise direction by an angle of α + 180 °.

Next, the spindle motor 21 is rotated at a constant rotation speed in the direction of arrow R shown in FIG. 7 (step S2). When the spindle motor 21 is rotated, as shown in FIG. 7, the center 100c of the optical disc 100 eccentrically moves around the rotation center Ct of the spindle motor 21.

Next, the optical pickup 100 irradiates the optical disc 100 with the laser light L (step S3).
The spot SPt of the laser light emitted from the optical pickup 30 to the optical disc 100 moves along the trajectory K on the rotating optical disc 100, as shown in FIG.
This locus K is a circle centered on the rotation center Ct of the spindle motor 21, and this circle is eccentric with respect to the center 100c of the optical disc 100. The spot SPt reciprocates between the position P1 and the position P2 on the optical disc 100 shown in FIG. 7 according to the rotation of the optical disc 100. That is, the optical pickup 30 relatively moves in the radial direction of the optical disc 100 (direction in which the tracks TR are spaced). When the spot SPt reciprocates between the position P1 and the position P2, the spot SPt crosses the number of tracks TR corresponding to the distance Ea. The relative speed of the spot SPt in the radial direction of the optical disc 100 is minimum at the positions P1 and P2, and is maximum at the central position between the positions P1 and P2.

Next, the read signal DS from the photodetector 35
And the origin position signal 25s from the rotational position detector 25 is sampled by the A / D converters 51 and 52, respectively (step S4). Here, FIG. 8A is a graph showing an example of sampling data of the read signal DS, and FIG. 8B is a graph showing an example of sampling data of the origin position signal 25s. As shown in FIG. 8B, from the rotational position detector 25, the spindle motor 21
A pulse-shaped origin position signal 25s is output every time the motor rotates once.

On the other hand, as shown in FIG. 8 (a), the sampling data of the read signal DS is waveform data having sparse and dense periods. The density of the waveform data is generated according to the relative speed of the optical pickup 30 in the radial direction of the optical disc 100. The waveform data has the sparsest waveforms at the positions rotated by the angle α and the angle α + 180 ° with reference to the origin position signal 25s shown in FIG. 8B. The number of waveforms of the read signal DS existing between the origin position signals 25s is the number of tracks TR that the optical pickup 30 (laser light spot SPt) crosses.

After sampling the read signal DS for at least one rotation (step S5), the sampling is completed (step S6). The processor 53 then
Read signal DS sampled and origin position signal 25
The optical disc 100 based on the sampling data of s
The eccentricity amount and the eccentric direction are calculated (step S7).

Specifically, the processor 53 specifies the number of crossed tracks TR by counting the number of waves included in the waveform data of the read signal DS for one rotation.
The eccentricity amount of the optical disc 100 is calculated by multiplying the number of the tracks TR by the interval TRP of the tracks TR and obtaining 1/2 of this value. The number of waves is measured by, for example, shaping the waveform data into pulses and counting the number of pulses. Further, the processor 53
From the sampling data of the reading signal DS associated with the origin position signal 25s, the angle α and the angle α + 180 °
Is calculated and this is taken as the eccentric direction.

By the above processing procedure, the optical disc 100
It is possible to simultaneously obtain the eccentric amount of the spindle motor 21 with respect to the rotation center Ct and the eccentric direction from the origin position in the rotation direction of the spindle motor 21. By using the eccentricity amount and the eccentricity direction as information for reducing the eccentricity amount of the optical disc 100 in the manufacturing process of the optical disc 100, the eccentricity of the optical disc 100 can be easily corrected.

Second Embodiment FIG. 9 is a view showing the arrangement of an eccentricity inspection device according to another embodiment of the present invention. The eccentricity inspection device 15 shown in FIG.
0, the same reference numerals are used for the same components as those of the eccentricity inspection device 1 according to the first embodiment described above. The eccentricity inspection device 150 of the present embodiment and the eccentricity inspection device 1 according to the first embodiment are different in that the eccentricity inspection device 150 of the present embodiment has a plurality of optical pickups 30a.
And 30b. Further, the optical disc 20 that is the inspection target of the eccentricity inspection device 150 of the present embodiment.
0 has a plurality of signal planes 201 and 202.

FIG. 10 is a view showing a cross-sectional structure of the optical disc 200 in the radial direction (track spacing direction). As shown in FIG. 10, the optical disc 200 has a substrate 210.
A reflective film 211 formed on the substrate 210, an adhesive layer 212 formed on the reflective film 211, a reflective film 213 formed on the adhesive layer 212, and the reflective film 21.
3 and a substrate 214 formed on the substrate 3.

The substrate 210 is formed by molding a transparent resin such as polycarbonate into a disc shape, and has a plurality of pits P formed on its surface. These pits P are arranged concentrically, and a track TR is formed by a row of pits P.
2 are configured. In addition, the interval between the tracks TR2,
That is, the intervals TRP2 between the adjacent tracks TR2 in the radial direction of the optical disc 100 are equal. Substrate 210
The surface on which the pit P is formed constitutes the signal surface 201.

The substrate 214 is, for example, a disc-shaped transparent resin material in the form of a film, and has a plurality of pits P formed on its surface. These pits P are arranged concentrically like the pits P formed on the substrate 210, and the track TR1 is formed by the rows of the pits P. The surface of the substrate 214 on which the pits P are formed constitutes the signal surface 202. The intervals TRP1 of the tracks TR1 are equal.

The adhesive layer 212 is composed of the substrate 210 and the substrate 214.
And are bonded via the reflection films 211 and 213. The adhesive layer 212 is formed of, for example, a material such as an ultraviolet curable resin or a material having an adhesive property, and transmits light. The reflection film 213 is formed of a metal film of aluminum, gold, silver or the like, and reflects the laser light L incident from the substrate 214 side. The reflection film 211 is formed of a metal film of aluminum, gold, silver or the like, and the laser light L incident from the substrate 214 side.
Among them, the laser light transmitted through the reflective film 213 and the adhesive layer 212 is reflected.

In the manufacturing process of the optical disc 200 described above, for example, as shown in FIG. 11, after the reflective films 211 and 213 are formed on the substrates 210 and 214 on which the pits P have been transferred by the stamper, respectively, the surface of the reflective film 211 is formed. UV curable resin UVR is applied to. In this state,
By bonding the substrate 214 to the substrate 210 and curing the ultraviolet curable resin UVR, the reflective films 211 and 211
The substrate 210 and the substrate 214 are adhered to each other via 13. The cured UV curable resin UVR is the adhesive layer 212 described above.
Becomes

The data recorded on the optical disc 200 is recorded, for example, while the optical disc 200 is being rotated.
The focus position of the objective lens provided in the optical pickup is adjusted to the signal surface to be reproduced of the signal surfaces 201 and 202, and the optical pickup is irradiated with laser light while following the desired track of the signal surface, and the pit of the signal surface is lit. The optical pickup picks up the return light from the signal surface that has been intensity-modulated by P and is reproduced by converting it into an electric signal. The signal surface to be reproduced is switched by changing the focal position of the objective lens provided in the optical pickup and causing the optical pickup to follow a desired track on the changed signal surface.

By the way, in a recording medium having a plurality of signal surfaces 201 and 202 by laminating a plurality of substrates 210 and 214 like the above optical disc 200, eccentricity occurs between the substrate 210 and the substrate 214. there is a possibility. The eccentricity between the substrate 210 and the substrate 214 is
10 is a combination of the eccentricity generated in each of the substrates 10 and 214 at the manufacturing stage and the eccentricity generated in the step of bonding the substrate 210 and the substrate 214 together.

When the amount of eccentricity between the substrate 210 and the substrate 214 is large, the amount of eccentricity between the signal surface 201 and the signal surface 202 also becomes large. If the amount of eccentricity between the signal surface 201 and the signal surface 202 is large, there arises a problem that it becomes difficult to make the optical pickup follow a desired track of the signal surface to be reproduced when switching the signal surface to be reproduced. there is a possibility. Therefore, it is necessary to suppress the amount of eccentricity between the substrate 210 and the substrate 214 due to the bonding of the substrate 210 and the substrate 214. In order to suppress the eccentricity amount due to the bonding between the substrate 210 and the substrate 214, the eccentricity amount and the eccentric direction between the substrate 210 and the substrate 214 are detected, and this detection information is fed back to the bonding process. There is a need to.

In the eccentricity inspection device 150 according to this embodiment, as shown in FIG.
a and 30b. In FIG. 9, the optical pickup 30a is positioned at a position where the signal recorded on the signal surface 202 of the optical disc 200 can be read. The read signal DS1 of the optical pickup 30a is A /
It is output to the D converter 52a. Optical pickup 30b
Is positioned at a position where the signal recorded on the signal surface 201 of the optical disc 200 can be read. The read signal DS2 of the optical pickup 30b is output to the A / D converter 52b.

A / D converters 51, 52a and 52b
The sampling signal sp is input from the processor 53. A / D converters 51, 52a and 52b
Performs synchronous sampling of the origin position signal 25s of the rotational position detector 25 and the read signals DS1 and DS2, converts these signals into digital signals, and outputs them to the processor 53.

The processor 53 calculates the eccentricity amount and the eccentric direction of the optical disc 200 based on the sampled data of the read signals DS1 and DS2 and the origin position signal 25s.

FIG. 12 is a graph showing an example of sampling data read by the processor 53.
(A) is a read signal DS1, (b) is a read signal DS2,
(C) shows the origin position signal 25s.

As can be seen from FIG. 12, the waveform data of the read signal DS1 on the signal surface 202 and the waveform data of the read signal DS2 on the signal surface 201 have different waveforms, respectively. There are many waves. That is, it means that the signal surface 202 (the substrate 214) has a larger eccentric amount than the signal surface 201 (the substrate 210) with respect to the rotation center Ct of the spindle motor 21.
The wave number of the waveform data of the read signal DS1 and the wave number of the waveform data of the read signal DS2 are respectively counted by the processor 53, and the difference between these wave numbers is calculated to obtain the substrate 210.
The amount of eccentricity between the substrate and the substrate 214 can be calculated.

As can be seen from FIG. 12, the position where the waveform data of the read signal DS1 on the signal surface 202 is the most sparse is the position of the angle α based on the origin position signal 25s, and from the origin position OR of the spindle motor 21. The direction of the angle α is the eccentric direction of the substrate 214. The position where the waveform data of the read signal DS2 on the signal surface 201 is the most sparse is a position of an angle β with respect to the origin position signal 25s, and the direction of the angle β from the origin position OR of the spindle motor 21 is the substrate 21.
The direction of eccentricity is 0. The processor 53 detects the angles α and β and calculates the difference between the angles α and β to obtain the substrates 210 and 214.
The relative eccentricity direction of is known.

As described above, according to the present embodiment, the relative eccentricity amount and the eccentric direction between the substrates (each signal surface) of the optical disc 200 having a plurality of signal surfaces are simultaneously detected by bonding the substrates together. By using this detection information, it is possible to suppress the eccentricity between the substrates caused by the bonding process.

Third Embodiment FIG. 13 is a diagram showing the configuration of an eccentricity inspection device according to still another embodiment of the present invention. In the eccentricity inspection device 350 shown in FIG. 13, the same components as those of the eccentricity inspection devices 1 and 150 according to the above-described first and second embodiments are denoted by the same reference numerals. The optical disc 2 to be inspected by the eccentricity inspection device 350 according to the present embodiment.
00 is the same as the inspection target of the eccentricity inspection device 150 of the second embodiment, and includes a plurality of signal surfaces 201 and 202. Further, the eccentricity inspection device 350 according to the present embodiment,
The optical pickup 30 includes a single optical pickup 30 and actuators 90 that position the optical pickup 30 at positions where the signals recorded on the signal surfaces 201 and 202 can be read. This actuator 9
0 moves and positions the optical pickup 30 in the direction FCS perpendicular to the signal surfaces 201 and 202 of the optical disc 200.

The optical disc 2 in the eccentricity inspection device 350
In order to detect the eccentricity amount and the eccentric direction of each of the signal surfaces 201 and 202 of 00, the optical pickup 30 is mounted on the signal surface
Of the origin position signal 2 of the rotational position detector 25 in the same procedure as described in the first embodiment.
5s and the read signal of the signal surface 202 are sampled,
Acquire the read signal for one rotation. Then, the signal surface 201
The focus position of the optical pickup 30 is adjusted to, and the origin position signal 25s of the rotation position detector 25 and the read signal of the signal surface 201 are sampled by the same procedure as described in the first embodiment to read one rotation. Get the signal.

With reference to the origin position signal 25s, the waveform data of the read signal on the signal surface 201 and the waveform data of the read signal on the signal surface 202 are associated with each other, and the signal surface 201 is processed in the same procedure as described in the second embodiment. , 202 relative eccentricity amount and eccentric direction are calculated.

In the present embodiment, with the above configuration, even when the signal surface is not a two-layer structure but a multi-layer structure, the optical pickup 30 is driven by the actuator 90.
Need only be positioned on the optical disc 200, and no optical pickup is required for each signal surface.

As described above, the present invention has been described with reference to various embodiments, but the present invention is not limited to the above-mentioned embodiments. In the embodiment described above, the spindle motor 21
The reading signal DS for one rotation of the spindle motor 21 is sampled by using the origin position signal 25s of the rotation position detector 25 as the rotation angle information of.
The rotation position detector 25 generates a pulse signal according to the rotation amount of the spindle motor 21, and the pulse signal is A /
The read signal DS for one rotation may be sampled by using it as the sampling signal sp of the D converter 52.

Further, in the above-described embodiment, the origin position signal 25s and the read signal DS are converted into A / D converters 51 and 52.
The eccentricity amount and the eccentricity direction are calculated by converting the signal into a digital signal by using the.
It is also possible to adopt a configuration in which an analog circuit for calculating the eccentricity amount and the eccentricity direction is prepared without using 2, and the eccentricity amount and the eccentricity direction are calculated by analog processing.

As the read signal DS, the one obtained by converting the intensity of the return light RL received by the photodetector 35 into an electric signal as it is is used. For example, the photodetector 35 is divided into a plurality of light receiving elements. It is also possible to use a tracking error signal or the like in which a predetermined calculation is added to the electric signal detected by each light receiving element.

Further, a plurality of light receiving elements are used for the photodetector 35, and two signals having phases different from each other by 90 ° are generated by calculation from the electric signals detected by the respective light receiving elements, and these signals are read signals. It can also be used as a DS. That is, although it is possible to specify the eccentric direction in the above-described embodiment, it is determined whether the center 100c of the optical disc 100 shown in FIG. 7 is at the position of the angle α or the position of the angle α + 180 ° from the origin position OR. Difficult to identify. Return light RL from optical disc 100
Of the optical disc 100 of the optical pickup 30 by generating a first signal and a second signal whose phases are different from each other by 90 ° based on the intensity of the signal and detecting the advance and delay relations of the phases of these first and second signals. Direction of the relative movement in the radial direction (direction of the interval of the track TR) can be detected, and from this relative movement direction, whether the center 100c of the optical disc 100 is at the position of the angle α or the angle α + 180 ° from the origin position OR. Can be specified.

In the above-mentioned embodiments, the case where the track TR is composed of the pits P has been described as an example, but the present invention, for example, uses a groove (guide groove) formed concentrically to form a track. It is also applicable to configured optical disks.

[0062]

According to the present invention, it is possible to detect both the amount of eccentricity and the direction of eccentricity existing on the disk-shaped recording medium. As a result, it becomes possible to adjust the manufacturing process of the disk-shaped recording medium with less eccentricity and less eccentricity.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an eccentricity inspection device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a structure of an optical pickup 30.

FIG. 3 is a diagram for explaining the structure of an optical disc 100.

FIG. 4 is a diagram showing a cross-sectional structure of a part of the optical disc 100.

FIG. 5 is a diagram for explaining a read signal DS output from the optical pickup 30 when the optical pickup 30 irradiates the optical disc 100 with a laser beam.

FIG. 6 is a flowchart showing a procedure for detecting an eccentricity amount and an eccentric direction of the optical disc 100 using the eccentricity inspection device 1.

FIG. 7 is a diagram for explaining an eccentricity amount and an eccentric direction existing on the optical disc 100.

FIG. 8 is a graph showing an example of sampling data of a read signal DS and an origin position signal 25s.

FIG. 9 is a diagram showing a configuration of an eccentricity inspection device according to another embodiment of the present invention.

FIG. 10 is a diagram showing a cross-sectional structure of the optical disc 200 in the radial direction (track spacing direction).

FIG. 11 is a diagram for explaining a manufacturing process of the optical disc 200.

FIG. 12 is a graph showing an example of sampling data read by a processor 53.

FIG. 13 is a diagram showing a configuration of an eccentricity inspection device according to still another embodiment of the present invention.

[Explanation of symbols]

1, 150, 350 ... Eccentricity inspection device, 20 ... Rotation drive unit, 21 ... Spindle motor, 25 ... Rotation position detector,
30 ... Optical pickup, 50 ... Control device, 100, 2
00 ... Optical disc, 101, 201, 202 ... Signal surface.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Eijiro Kikuno             6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo Stocks             Company Sony Disc Technology F-term (reference) 5D090 AA01 BB02 BB10 BB12 CC18                       DD03 HH01 JJ05 LL08                 5D096 AA05 CC01 DD06 GG07 HH04                       KK01                 5D109 BA15 BA17 BA21 BB05 BB12                       BB22                 5D117 AA02 BB04 CC07 FF14                 5D121 AA01 HH05 HH18

Claims (7)

[Claims] 1. Rotating means for holding and rotating a disk-shaped recording medium having tracks at predetermined intervals on a signal surface, and arranged at a predetermined position with respect to a rotation center of the rotating means,
A reading unit that generates a read signal based on the intensity of the return light from the signal surface of the light beam applied to the disk-shaped recording medium; the reading unit and the disk-shaped recording medium that are generated by the eccentricity of the rotating disk-shaped recording medium. And the eccentricity of the disc-shaped recording medium, based on the relative movement information obtained from the read signal of the reading means by the relative movement of the tracks between the disc-shaped recording medium and the rotation angle information of the disc-shaped recording medium. An eccentricity inspection device for a disk-shaped recording medium having an eccentricity detection means for detecting a direction. 2. The relative motion information comprises waveform data whose value changes periodically each time the reading means crosses a track, and the eccentricity detection means is obtained by one rotation of the disk-shaped recording medium. The disc according to claim 1, wherein the eccentricity amount is detected based on the wave number of the waveform data and the interval between the tracks, and the eccentric direction is detected by associating the density of the waveform data with the rotation angle information. Eccentricity inspection device for recording medium. 3. The disk-shaped recording medium has a plurality of signal surfaces by bonding a plurality of disk-shaped substrates, and the reading means is provided at a position where the relative motion information can be obtained from each of the signal surfaces. The eccentricity detection unit further includes a movement positioning unit that can position the disc-shaped recording medium, and the eccentricity detection unit, based on the relative motion information obtained from the signal surfaces, eccentricity amount of each disc-shaped substrate. The eccentricity inspection device for a disk-shaped recording medium according to claim 1, wherein the eccentricity direction is detected. 4. The disk-shaped recording medium has a plurality of signal surfaces by bonding a plurality of disk-shaped substrates, and a plurality of reading means capable of acquiring the relative motion information from each of the signal surfaces. However, the eccentricity detection unit detects the eccentricity amount and the eccentric direction of each of the disk-shaped substrates based on the relative motion information obtained from each of the signal surfaces. Eccentricity inspection device. 5. A light beam applied to the signal surface by rotating a disk-shaped recording medium having tracks at predetermined intervals on the signal surface, and reading means arranged at a predetermined position with respect to the center of rotation of the disk-shaped recording medium. A read signal is generated based on the intensity of the return light from the signal surface, and the read unit and the disk-shaped recording medium are obtained by the eccentricity of the rotating disk-shaped recording medium, which is obtained from the read signal of the reading unit. An eccentricity inspection method for a disk-shaped recording medium, which detects an eccentricity amount and an eccentric direction of the disk-shaped recording medium based on relative movement information in the interval direction between tracks and rotation angle information of the disk-shaped recording medium. 6. The relative motion information comprises waveform data whose value changes periodically each time the reading unit crosses a track, and the wave number of the waveform data obtained by one rotation of the disc-shaped recording medium. The eccentric direction is detected by detecting the eccentricity amount based on the track interval and associating the rotation angle information with the density of the waveform data obtained by one rotation of the disk-shaped recording medium. 5. An eccentricity inspection method for a disk-shaped recording medium according to 5. 7. The disk-shaped recording medium has a plurality of signal surfaces by bonding a plurality of disk-shaped substrates, the relative motion information is obtained from each of the signal surfaces, and obtained from each of the signal surfaces. The eccentricity inspection method for a disk-shaped recording medium according to claim 5, wherein the eccentricity amount and the eccentric direction of each of the disk-shaped substrates are detected based on the obtained relative motion information.