JPH05314706A - Optical disc inspection device - Google Patents

Abstract

(57) [Abstract] [Purpose] It is not necessary to attach or remove the correction plate that corrects the focus of the signal surface of the optical disc and stamper, the mounting accuracy is secured, damage on the signal surface is prevented, and stable inspection can be performed. To do so. [Structure] An optical pickup 10 for an optical disk 1 and an optical pickup 11 for a stamper 2 are provided on a rotary table 5.
The optical disc 1 or the stamper 2 is mounted on the lower surface of the rotary table 5 with the signal surface facing down, and the correction plate is bonded to the objective lens 24 of the optical pickup 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk inspecting apparatus for inspecting the signal characteristics of an optical disk and a mold (hereinafter referred to as a stamper) for molding the signal surface of the optical disk.

[0002]

2. Description of the Related Art Conventionally, when inspecting the respective signal surfaces of an optical disk and a stamper, the optical disk or the stamper is mounted with the signal surface facing upward on a rotary table that is driven to rotate by a spindle motor, and an optical pickup is mounted on the upper part. It mounted and scanned the laser beam on the signal surface, analyzed the signal by reflected light, and inspected. In this case, in the optical disc, resin or the like as a disc material exists between the optical pickup and the signal surface, but in the case of the stamper, only air exists between the optical pickup and the signal surface. Therefore, if the optical pickup is set so that the laser beam is focused on the signal surface of the optical disc, it cannot be focused on the signal surface of the stamper.

In order to solve the above-mentioned problems, usually, between the objective lens of the optical pickup and the signal surface of the stamper,
A correction plate having the same refractive index and thickness as the resin such as polycarbonate, which is the material of the optical disc, is inserted. As the correction plate, it is better to use glass, which is a non-birefringent material, than to use a resin having birefringence, and it is possible to obtain a reproduction signal that is not affected by birefringence and improve inspection accuracy. be able to. This correction plate is conventionally fixed between the optical pickup and the stamper signal surface.

[0004]

In the conventional optical disc inspection apparatus configured as described above, the optical pickup is
Since there are only one, the correction plate must be removed when inspecting an optical disk, and the correction plate must be attached when inspecting a stamper. Therefore, there is a problem in that the accuracy of the mounting angle of the correction plate decreases as the correction plate is repeatedly attached and detached and used for a long period of time. Also, since the correction plate is fixed between the optical pickup and the stamper signal surface,
The correction plate does not move and cannot follow when the stamper moves or the objective lens moves. As a result, there is a drawback that the parallelism between the stamper surface and the correction plate shifts, the refractive index changes, and the reproduced RF signal characteristics deteriorate. Further, in order to prevent the surface runout of the stamper and the movement of the objective lens, there is a problem that the mechanism becomes complicated and the cost becomes high.

On the other hand, since the stamper is mounted on the upper surface of the rotary table with the signal surface facing upward, and the optical pickup is mounted on the upper part of the stamper, dust generated from the drive system of the optical pickup or floating dust is generated. There is a risk that the signal surface of the stamper will fall and damage or stain the signal surface. Further, if the power supply voltage drops during the inspection, the lens of the optical pickup may contact the signal surface of the rotating stamper due to its own weight and may be damaged.

The present invention has been made in view of the above circumstances, and it is possible to secure the mounting accuracy by eliminating the attachment and detachment of the correction plate, prevent the signal surface of the stamper from being damaged, and perform a stable inspection. It is an object of the present invention to provide an optical disc inspection apparatus capable of performing the above.

[0007]

An optical disk inspection apparatus according to claim 1 is an optical disk inspection apparatus for inspecting the signal characteristics of an optical disk 1 and a stamper 2 as a mold for molding the optical disk 1.
And a pair of optical pickups 10 for irradiating the rotary table 5 that is driven by the motor 7 and the optical disk 1 or the stamper 2 held on the rotary table 5 with laser light and outputting a signal by reflected light. 11 and
A signal processing unit 15 for processing signals output from the optical pickups 10 and 11 and evaluating signal characteristics of the optical disc 1 and the stamper 2 is provided.

The optical disk inspection apparatus according to claim 2 is
It is characterized in that the stamper 2 is held on the lower surface of the rotary table 5 with the signal surface 2a on the lower side, and the optical pickup 11 is provided on the lower side of the stamper 2.

The optical disk inspection apparatus according to claim 3 is
It is characterized in that the stamper 2 is held on the lower surface of the rotary table 5 via a stamper holder 32 as a holding member that attracts by magnetic force.

An optical disk inspection apparatus according to a fourth aspect is
A correction plate for focusing the optical pickup 11 on the signal surface 2a of the stamper 2 is directly attached to the objective lens 24 of the optical pickup 11.

An optical disk inspection apparatus according to a fifth aspect is
The correction plate is made of glass.

[0012]

In the optical disk inspection apparatus according to claim 1, the optical pickups 1 for the optical disk and the stamper are provided.
Since 0 and 11 are separately provided, the correction plate can be fixed to the optical pickup 11 for the stamper, the correction plate need not be attached and detached, and the mounting accuracy can be stably maintained.

In the optical disc inspection apparatus according to the second and third aspects, the stamper 2 is held on the lower surface of the rotary table 5 with the signal surface 2a facing downward, and the optical pickup 11 for the stamper is positioned below the stamper 2. Since it is provided, it is possible to prevent dust generated from the drive system of the optical pickup 11 or floating dust from falling on the signal surface 2a of the stamper 2 and damaging or contaminating the signal surface 2a.

In the optical disk inspection apparatus according to the fourth aspect, the correction plate is the objective lens 2 of the optical pickup 11.
Since the correction plate is directly mounted on the lens 4, the correction plate moves in conjunction with the objective lens 24, and the correction plate moves with the follow-up movement of the lens 24 even if the surface runout of the signal surface 2a of the stamper 2 occurs. As a result, the angle of the correction plate is also corrected at the same time, and a stable RF signal is obtained.

In the optical disk device according to the fifth aspect, since the correction plate is made of glass, it is possible to obtain a reproduction signal that is not affected by birefringence and improve the inspection characteristics.

[0016]

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

1 to 4 show the configuration of an embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of the optical disc inspection apparatus according to this embodiment. This device is provided with a player unit 3 for generating an inspection signal for the optical disc 1 or the stamper 2.
And a control unit 4 for processing signals. The player unit 3 is provided with a rotary table 5 that holds the optical disk 1 or the stamper 2 on the lower surface.
Is driven to rotate by a spindle motor 7 via a rotary shaft 6. The spindle motor 7 is driven by a spindle servo 9 controlled by a mechanical controller 8.

An optical disc optical pickup 10 and a stamper optical pickup 11 are provided below the rotary disc 5 on both sides of the rotary shaft 6, and the optical pickups 10 and 11 are respectively focus / tracking servos 12 and 13. Is driven in the focus direction and the tracking direction. The focus / tracking servos 12 and 13 are controlled by the mechanical controller 8, respectively. And each optical pickup 10,
11 is a stamper 2 for inspecting the optical disk 1 respectively
Is selected, the selected optical pickup 10 or 11 is driven to emit a laser beam, and the reflected light reproduces a signal for inspecting the signal characteristic of each signal surface.

The signal is sent to the signal processing unit 15 of the control unit 4 through the interface 14, and the signal processing unit 15 analyzes the signal to measure and inspect the signal characteristics. That is, items such as block error rate, burst error, tracking error noise, dropout, asymmetry, crosstalk, push bull, and TOC information check are inspected, and pass / fail judgment is made by comparison with a preset threshold value. The inspection result is displayed on the output device such as the CRT 17 and the printer 18 via the host computer 16.

FIG. 2 shows a mounting structure of the optical pickups 10 and 11. The optical pickups 10 and 11 are movably attached to a pair of guide rails 21 and 22 provided in the apparatus main body in parallel with the rotary table 5. The objective lenses 23 and 24 provided in the optical pickups 10 and 11, respectively, face the optical disk 1 or the stamper 2 mounted on the lower surface of the rotary table 5 and move in their respective radial directions. ..
Further, a disc-shaped correction plate (not shown) having a diameter smaller than that of the objective lens 24 is bonded to the objective lens 24 of the optical pickup 11 for the stamper. The correction plate is made of glass SK-5 having a refractive index close to that of polycarbonate at 780 nm which is the wavelength of the semiconductor laser of the optical pickup 11.

When the optical disc 1 is inspected by the optical disc inspection apparatus configured as described above, the optical disc 1 is mounted on the lower surface of the turntable 5 with the signal surface 1a facing downward. When inspecting the stamper 2, the magnet sheet 31 is attached to the lower surface as shown in FIGS.
The stamper 2 is attracted to the lower surface of the disk-shaped stamper holder 32 to which is adhered with the signal surface 2a facing downward, and together with the stamper 2, the stamper holder 32 is attached to the rotary table 5 with screws or the like.

According to this embodiment, since the optical pickups 10 and 11 for the optical disk and the stamper are separately provided, the correction plate can be fixed to the optical pickup 11 for the stamper, and the correction plate need not be attached or detached. Therefore, the mounting accuracy can be stably maintained. Further, since the stamper 2 is held on the lower surface of the turntable 5 with the signal surface 2a facing downward, it is possible to prevent the signal surface 2a from being damaged by dust or the like. Further, since the correction plate is attached to the objective lens 24, the correction plate moves together with the objective lens 24, and the angle of the correction plate is corrected at the same time, so that a stable RF signal can be obtained. Further, since the correction plate is made of glass having a diameter smaller than that of the objective lens 24, it is possible to reduce the air resistance of the correction plate during the focus servo and reduce the load on the focus servo. Moreover, it is possible to obtain a reproduction signal that is not affected by birefringence, and improve the inspection characteristics.

In the above embodiment, the optical pickup 10 for the optical disk and the optical pickup 11 for the stamper are
The case of guiding the guide rails 21 and 22 separated from each other and moving them in the radial direction has been described.
Alternatively, the guide rails 21 and 22 may be connected to form a pair of guide rails 41 so that the optical pickups 10 and 11 can be moved in diameter.

Further, as shown in FIG. 6, two optical pickups for optical disks or stampers are mounted, one of which is inspected from the innermost circumference to half in the radial direction, and the other one is inspected from half to the maximum. You may make it inspect to the outer periphery. By dividing the inspection range in this way, an optical disk inspection machine or stamper inspection machine that can reduce the inspection time by half can be created by modifying the control system and the like to meet this specification. In this case also, as shown in FIG. 7, a pair of guide rails may be used.

[0025]

As described above, according to the optical disc inspection apparatus of the first aspect, the optical disc optical pickup and the stamper optical pickup are provided side by side. Therefore, the correction plate is fixed to the stamper optical pickup. Therefore, the accuracy of mounting the correction plate can be stably maintained.

According to the optical disk inspection apparatus of the second and third aspects, since the stamper is held on the lower surface of the rotary table with the signal surface facing down, the signal surface of the stamper is prevented from being damaged by dust or the like. be able to.

According to the optical disc inspection apparatus of the fourth and fifth aspects, since the correction plate is made of glass and is directly attached to the objective lens of the optical pickup, it is affected by surface runout and birefringence of the signal surface of the stamper. Without, a stable reproduction signal can be obtained and the inspection characteristics can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of an optical disc inspection apparatus of the present invention.

FIG. 2 is a plan view showing a mounting structure of the optical pickup of FIG.

FIG. 3 is a plan view showing a structure of a stamper holder that holds the stamper of FIG.

4 is a vertical cross-sectional view of FIG.

FIG. 5 is a plan view showing a mounting structure of an optical pickup according to a second embodiment of the present invention.

FIG. 6 is a plan view showing a mounting structure of an optical pickup according to a third embodiment of the present invention.

FIG. 7 is a plan view showing the mounting structure of the optical pickup according to the first embodiment of the present invention.

[Explanation of symbols]

 1 Optical Disc 2 Stamper (Type) 1a, 2a Signal Surface 5 Rotating Table 7 Motors 10, 11 Optical Pickup 15 Signal Processing Section 24 Objective Lens 32 Stamper Holder (Supporting Member)

Claims (5)

[Claims] 1. An optical disk inspecting apparatus for inspecting a signal characteristic of an optical disk and a mold for molding the optical disk, comprising: a rotary table which holds the optical disk or the mold and is rotationally driven by a motor; and a rotary table held by the rotary table. A pair of optical pickups for irradiating an optical disc or a mold with laser light and outputting signals by reflected light, and a signal processing for processing signals output by the optical pickups to evaluate the signal characteristics of the optical disc and the mold. And an optical disc inspection apparatus. 2. The optical disc inspection apparatus according to claim 1, wherein the mold is held on the lower surface of the rotary table with the signal surface facing down, and the optical pickup is provided under the mold. 3. The optical disk inspection apparatus according to claim 1, wherein the mold is held on the lower surface of the rotary table via a holding member that attracts the mold by magnetic force. 4. A correction plate for focusing the optical pickup on the signal surface of the mold is directly attached to the objective lens of the optical pickup.
The optical disk inspection device described. 5. The optical disc inspection apparatus according to claim 1, wherein the correction plate is made of glass.