JP2001074669A - Apparatus for inspecting optical disk defect - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inspect pin holes of a multilayer multi-density disk in a simple constitution in a short time by radiating a laser light while rotating the optical disk, reflecting part of a quantity of light by a first reflecting film, reflecting most of the passing light by a second reflecting film, detecting a quantity of the reflected light and comparing the quantity with a reference level. SOLUTION: A laser light emitted from a laser light source 2 passes a deflecting beam splitter 202 through a collimate lens 203, is reflected by approximately 30% through a quarter-wave plate 201 by a reflecting film 9 of a disk 8 to be inspected and enters again the quarter-wave plate. Approximately 60-70% of a quantity of light passes the reflecting film 9, and approximately 80% of the quantity of light is reflected by a reflecting film 10, approximately 60-70% of which passes the reflecting film 9 and enters the quarter-wave plate 201 again. The laser light entering the quarter-wave plate 201 again is reflected by the deflecting beam splitter 202 and enters a photodetecting apparatus 204. An output voltage of the photodetecting apparatus 204 is compared with a reference level, thereby judging the presence of pin holes of the reflecting films 9 and 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting optical discs for optically recording and reproducing data for defects, and more particularly to an apparatus for inspecting a first information surface and a second information surface covered with a first reflection film. The present invention relates to an optical disk defect inspection apparatus for detecting a defect in a first reflective film and a second reflective film of an optical disk having a second information surface covered with a reflective film.

[0002]

2. Description of the Related Art An optical disk on which data is recorded and reproduced optically by using a laser beam is manufactured at the time of manufacturing the disk.
The signal recording surface and the disk surface are inspected for defects. FIG. 7 is a schematic diagram showing a cross-sectional structure of a conventional compact disc. 701 is a substrate, 702 is an information surface, 70
3 is a reflective film, 704 is a protective film, and 705 is a print layer.
A compact disc (CD) includes a substrate 701 having an information surface 702 on one side of which information is recorded as a pit row. The information surface 702 is covered with a reflective film 703 made of a metal such as aluminum.
The reflective film 703 is covered with a protective film 704 made of a transparent resin such as an ultraviolet curable resin. On the protective film 704, a print layer 705 on which the title of the disc and the like are displayed is formed.

[0003] The reflection film 703 is formed by sputtering metal such as aluminum by a sputtering apparatus. When foreign matter such as dust or dirt adheres to the information surface of the substrate 701 during sputtering, the reflective film 703 is formed on the foreign matter. After that, when the foreign matter and the reflective film 703 formed thereon are peeled off before or during the formation of the protective film 704, a minute hole called a pinhole is generated in that portion.

[0004] Since the reproduction laser beam is not reflected at a portion where the pinhole exists, the reproducing device cannot read the information on the information surface 702 at that portion. Thus, the presence of the pinhole leads to the deterioration of the reproduction signal of the CD. Therefore, a reflective film 703 is formed in a CD manufacturing process,
Before forming the print layer 705, it is inspected whether a pinhole is generated in the reflective film 703.

In general, a pinhole inspection of a CD is performed by irradiating a laser beam or white light from the substrate 701 side or the protective film 704 side to detect the presence or absence of transmitted light. A method of determining that a hole exists, or irradiation of laser light from the substrate 701 side or the protective film 704 side,
The amount of light reflected by the reflective film 703 is detected,
When the detected amount of reflected light is smaller than the reference value, it is determined that a pinhole exists.

On the other hand, in addition to the CD layer, HD (High Density)
Multi-layer, multi-density disks having high-density recording layers, called layers, have been developed and are becoming popular. FIG. 8 is a schematic diagram showing a cross-sectional structure of a conventional multilayer multi-density disk. 80
1 is a first substrate, 802 is a first information surface, 803 is a first information surface.
804 is a transparent adhesive layer, 805 is a second substrate,
806 is a second information surface, and 807 is a second reflection film.

[0007] Multi-layer, multi-density discs have a CD on one side.
Information surface 8 recorded at a recording density 5 times or more of
And a first substrate 801 having the same. The first information surface 802 has a first reflection film 803 made of silicon or the like having a reflectivity of about 30% with respect to a laser beam having a wavelength of 635 to 650 nm and a transmittance of about 80% or more with respect to a laser beam having a wavelength of 780 nm. Covered in.

A multi-layer, multi-density disk has a CD on one side.
Second information surface 806 recorded at the same recording density as
Is provided. The second information surface 806 is covered with a second reflective film 807 made of aluminum or the like having a reflectance of about 80% or more for the laser light having a wavelength of 635 to 650 nm and the laser light having a wavelength of 780 nm.

[0009] The first substrate 801 and the second substrate 805 are composed of a first reflection film 80 formed on the first substrate 801.
3 are bonded together via a transparent adhesive layer 804 such that the surface opposite to the surface on which the second information surface 806 of the second substrate 805 is formed faces each other.

[0010]

As described above, a multilayer multi-density disc has two information surfaces unlike a conventional CD. The first information surface 802 is the first reflection film 8
03, and the second information surface 806 is covered with a second reflective film 807. Therefore, when an inspection for determining the presence or absence of a pinhole by irradiating a laser beam or white light as in the related art is performed on a multilayer multi-density disk, the following problem occurs.

(1) In the inspection for detecting transmitted light by irradiating laser light or white light and determining the presence or absence of a pinhole, pinholes generated in the first reflection film 806 and the second reflection film 807 are determined. Since the transmitted light cannot be obtained unless the position is located exactly at the same position with respect to the irradiated optical axis of the laser light or white light, it is necessary to set different positions for the optical axis with the laser light or white light. It is not possible to determine the presence or absence of the pinhole of the first reflection film 803 or the pinhole of the second reflection film 807 that has occurred. In the inspection for irradiating the laser light and detecting the reflected light to determine the presence or absence of the pinhole, the first reflective film 80
Since the inspection of the pinholes of the third and second reflective films 807 had to be performed separately (for example, before the first substrate 801 and the second substrate 805 were bonded), the pin for the CD was inspected. This requires twice as much time as hole inspection, which increases the manufacturing cost. (3) After bonding the first substrate 801 and the second substrate 805, a pinhole inspection of the first reflection film 803 using a first laser beam having a wavelength reflected by the first reflection film 803 is performed. Do
It is conceivable to adopt a method of inspecting the presence or absence of a pinhole in the second reflection film 807 by using a second laser beam having a wavelength transmitted through the first reflection film 803 and reflected by the second reflection film 807. However, the number of parts of the apparatus increases, resulting in a large-scale and expensive apparatus.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a pinhole inspection of a multilayer multi-density optical disk can be performed in the same inspection time as a conventional CD pinhole inspection, and It is an object of the present invention to provide an optical disk defect inspection device having a configuration similar to that of a conventional defect inspection device used for CD inspection.

[0013]

In order to solve the above-mentioned problems, the invention according to claim 1 of the present application is directed to a first information surface covered with a first reflection film and a second information surface covered with a second reflection film. An optical disc defect inspection apparatus for detecting a defect of the first reflection film and the second reflection film of the optical disc having the second information surface, wherein a rotation driving means for rotating the optical disc; Beam irradiating means for irradiating the optical disc with a light beam having a wavelength that transmits through the first reflective film, a part of the light amount reflects on the first reflective film, and most of the light amount is reflected on the second reflective film; Light amount detecting means for detecting the light amount of the light beam reflected from the light source, and defect determining means for determining the presence or absence of a defect in the first reflection film and the second reflection film from the output signal of the light amount detection means. It is characterized by.

According to a second aspect of the present invention, in the optical disk defect inspection apparatus according to the first aspect, when the voltage level of the output signal is substantially the same as a reference level, the defect judging means may be a first reflection film. And determining that there is no defect in the second reflection film.

According to a third aspect of the present invention, in the optical disk defect inspection apparatus according to the first or second aspect,
When the voltage level of the output signal is higher than a reference level, the defect determination unit determines that only the first reflection film has a defect.

According to a fourth aspect of the present invention, in the optical disk defect inspection apparatus according to the first to third aspects,
When the voltage level of the output signal is lower than a reference level, the defect determination unit determines that only the second reflection film has a defect or that the first reflection film and the second reflection film have a defect. It is characterized by.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk defect inspection apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the optical disk defect inspection apparatus according to the present invention. 1 is a spindle motor, 2 is a laser light source, 3 is a laser irradiation unit, 4 is a light amount detection unit, 5 is a defect determination unit, 6 is a control unit, 7 is an output terminal, 8 is a disk to be inspected,
Reference numeral 9 denotes a first reflection film, and reference numeral 10 denotes a second reflection film.

In FIG. 1, reference numeral 8 denotes a disk to be inspected which is a multi-layer, multi-density disk, and a laser beam to be described later from the light incident surface (the surface of the first substrate 201 in FIG. 8 where the first information surface 202 is not formed). It is placed on a turntable (not shown) so that light enters. The turntable is rotationally driven by a spindle motor 1 at a predetermined rotation speed.

In the laser light source 2, about 30% of the light amount is reflected by the first reflection film 9 of the disk 8 to be inspected, and about 60 to 70% of the light amount passes through the first reflection film 9, and A laser beam having a wavelength at which about 80% or more of the light amount is reflected by the second reflection film 10 is emitted. In this embodiment, the wavelength of the laser light is 650 nm.

The laser light emitted from the laser light source 2 is
The disk 8 to be inspected is irradiated by the laser irradiation unit 3.
FIG. 2 is a schematic diagram illustrating a configuration of a laser irradiation unit of the optical disc defect inspection apparatus according to the present embodiment. Laser irradiation unit 3
A を wavelength plate 201, a deflection beam splitter 202 and a collimating lens 203 are provided.

The laser light emitted from the laser light source 2 is
The light is shaped into parallel light by the collimating lens 203 and passes through the deflection beam splitter 202. Further, the deflection direction of the laser light is rotated by 45 ° by the quarter-wave plate 201, and about 30% of the light amount is reflected by the first reflection film 9 of the disk 8 to be inspected. Incident.

Also, the laser light is about 60 to 70% of the light amount.
Are transmitted through the first reflection film 9 and reach the second reflection film 10. About 8 of the amount of laser light reaching the second reflective film 10
0% is reflected and reaches the first reflection film 9. The laser light reaching the first reflection film 9 has a light amount of about 60 to 70
% Transmits through the first reflective film 9 and again becomes a quarter-wave plate 201.
Incident on. In this embodiment, the beam diameter of the laser light on the first reflection film 9 and the second reflection film 10 is about 30 μm.
It is.

The laser beam again incident on the quarter-wave plate 201 is reflected by the deflection beam splitter 202 because the deflection direction is further rotated by 45 °. The laser light reflected by the deflection beam splitter 202 is incident on the detection device 204 of the light amount detection unit 4 shown in FIG.

As shown in FIG. 1, the laser light reflected by the disk 8 to be inspected and emitted from the laser irradiating section 4 enters the light quantity detecting section 4 (detecting device 204), and a change in the reflected light quantity is detected. . The laser irradiation unit 3 moves at a predetermined speed in the radial direction of the disk 8 to be inspected by a slide motor (not shown) during the defect inspection. Also,
Instead of moving the laser irradiation unit 3 by the slide motor, the laser light emitted from the laser irradiation unit 3 may be moved by a polygon mirror or the like.

The light quantity detection section 4 outputs an output signal to the defect determination section 5 based on a change in the reflected light quantity of the laser light detected by the detection device 204. The defect determination unit 5 determines the presence or absence of a pinhole in the first reflection film 9 and the second reflection film 10 of the disk 8 to be inspected from the input output signal, and outputs the determination result to the output terminal 7. The control section 6 controls the operation of each section described above.

As described above, the optical disk defect inspection apparatus according to the present embodiment is configured to simultaneously irradiate the first reflective film 9 and the second reflective film 10 of the disk 8 to be inspected with laser light. The presence / absence of pinholes in the first reflection film 9 and the second reflection film 10 of the disk 8 can be inspected simultaneously.

Next, a method for judging the presence / absence of pinholes in the first reflective film 9 and the second reflective film 10 of the disk 8 to be inspected by the optical disk defect inspection apparatus of this embodiment will be described. FIG. 3 is a schematic diagram illustrating the determination of the presence or absence of a pinhole in the optical disk defect inspection apparatus according to the present embodiment when there is no pinhole in both the first reflection film and the reflection film of the inspection target disk. is there. Here, FIG.
The light amount detection unit 4 shown in FIG. 1 detects the reflection light amount of the laser light reflected from the disk 8 to be inspected input from the laser irradiation unit 3, converts the detected reflection light amount of the laser light into an electric signal, and outputs the electric signal. Output to the defect determination unit 5.

As shown in FIG. 3A, when neither the first reflection film 9 nor the second reflection film 10 of the disk 8 to be inspected has a pinhole, the laser beam is not reflected on the first reflection film. 9 reflects 30%. In addition, the laser light causes the first reflection film 9 to emit light of about 60 to 70% (in this embodiment, 65%
And ) The light is transmitted and reaches the second reflection film 10. Second
80% of the light amount of the laser light that has reached the reflective film 10 is reflected, and reaches the first reflective film 9 again. The laser beam reaching the first reflection film 9 transmits 65% of the light amount.

Accordingly, the amount of laser light reflected by the first reflection film 9 and the second reflection film 10 and emitted from the disk 8 to be inspected is 30% + (100% of the incident laser light). (65% × 80% × 65%) = 64
% (Equation 1). In the disk defect inspection apparatus of the present embodiment, the voltage level of the output signal corresponding to the 64% light amount is set as the reference level. That is, as shown in FIG. 3B, when there is no pinhole in the first reflection film 9 and the second reflection film 10, the voltage of the output signal output by the light amount detection unit 4 is substantially equal to the reference level. Therefore, the defect determination unit 5 determines that neither the first reflective film 9 nor the second reflective film 10 has a pinhole. The defect determination unit 5 outputs to the output terminal 7 a signal indicating that there is no pinhole in the first reflection film 9 and the second reflection film 10.

FIG. 4 is a schematic diagram for explaining the determination of the presence / absence of a pinhole in the optical disk defect inspection apparatus according to the present embodiment in the case where the inspection target disk has a pinhole only in the first reflection film. . As shown in FIG. 4A, when there is a pinhole in the first reflective film 9 of the disk 8 to be inspected, the laser light is completely absorbed or absorbed by the first reflective film 9 in the portion where the pinhole exists. The light reaches the second reflection film 10 without being reflected. The laser light reflected by the second reflection film 10 is emitted from the disk 8 to be inspected at the pinhole portion without being absorbed or reflected by the first reflection film 9 at all, as in the outward path. That is, the reflected light amount of the laser light irradiated on the pinhole of the first reflection film 9 becomes equal to the light amount reflected only by the second reflection film 10 (the light amount of the laser light incident on the inspection target disk 8 is reduced by 100%). Therefore, the amount of reflected light is 30% when the area of the first reflective film 9 where there is no pinhole is irradiated (the amount of laser light incident on the disk 8 to be inspected is 100%). Light amount). Therefore,
As shown in FIG. 4B, when a pinhole exists in the first reflection film 9, the voltage of the output signal output by the light amount detection unit 4 becomes higher than the reference level.

As described above, when the pinhole exists only in the first reflection film 9, the light quantity detection unit 4 inputs the output signal shown in FIG. Defect judgment unit 5
Determines that a pinhole exists only in the first reflection film 9 when the voltage of the input output signal is higher than the reference level. The defect determination unit 5 outputs to the output terminal 7 a signal indicating that a pinhole exists only in the first reflection film 9.

FIG. 5 is a schematic diagram for explaining the determination of the presence or absence of a pinhole in the optical disk defect inspection apparatus according to the present embodiment when the second reflective film of the disk 8 to be inspected has a pinhole. . As shown in FIG. 5A, when there is a pinhole in the reflection film 10 of the disk 8 to be inspected, the first laser light passes through the first reflection film 9 in the portion where the pinhole exists ( Assuming that the light amount of the laser light incident on the inspection target disk 8 is 100%, 65% of the light amount is transmitted), and further passes through the pinhole of the second reflection film 10. That is, the reflected light amount of the laser beam irradiating the area of the second reflective film 10 where the pinhole exists is 0% in the (65% × 80% × 65%) portion of the above (Equation 1), Is smaller than the reflected light amount of the laser light irradiating the area of the reflective film 10 where no pinhole exists. Therefore, as shown in FIG. 5B, when a pinhole exists in the second reflection film 10, the voltage of the output signal output from the light amount detection unit 4 becomes lower than the reference level.

As described above, when the pinhole exists only in the second reflection film 10, the light amount detection unit 4 performs the operation shown in FIG.
Is input to the defect determination unit 5. The defect determination unit 5 detects that the voltage of the input output signal is lower than the reference level.

FIG. 6 illustrates the determination of the presence / absence of a pinhole in the optical disk defect inspection apparatus according to the present embodiment when the first and second reflective films of the disk to be inspected have a pinhole. FIG. FIG.
As shown in (a), when there is a pinhole at the same position with respect to the optical axis of the laser light of the first reflection film 9 and the second reflection film 10 of the disk 7 to be inspected, the laser light The light passes through the pinhole of the first reflection film 9 and further passes through the pinhole of the second reflection film 10. That is, the reflected light amount of the laser light that irradiates the region where the pinhole exists at the same position on the first reflection film 9 and the second reflection film 10 is 0%,
The reflected light amount becomes lower than the reflected light amount of the laser light that irradiates the first reflection film 9 and the second reflection film 10 in the region where the pinhole does not exist. Therefore, as shown in FIG. 6B, when a pinhole exists at the same position on the first reflection film 9 and the second reflection film 10, the voltage of the output signal output from the light amount detection unit 4 is equal to the reference voltage. Lower than the level.

As described above, when there is a pinhole at the same position on the first reflection film 9 and the second reflection film 10, the light amount detection unit 4 determines the output signal shown in FIG. Input to section 5. When the voltage of the input first output signal is lower than the first reference level, the defect determination unit 5 determines whether there is a pinhole only in the second reflection film 10 or the first reflection film It is determined that there is a pinhole at the same position of 9 and the second reflection film 10. The defect determination unit 5 determines whether there is a pinhole only in the second reflection film 10 or the first reflection film 9
And a signal indicating that a pinhole exists in the second reflection film 10 is output to the output terminal 7.

[0036]

According to the present invention, a pinhole inspection of a multilayer multi-density disk having two information surfaces can be performed in the same inspection time as that of a conventional CD pinhole inspection. An optical disk defect inspection device having the same configuration as that of the defect inspection device described above can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an optical disk defect inspection apparatus according to the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of a laser irradiation unit of the optical disc defect inspection apparatus according to the present embodiment.

FIG. 3 is a diagram showing a first example of a disk to be inspected in the optical disk defect inspection apparatus according to the present embodiment for determining the presence or absence of a pinhole;
FIG. 9 is a schematic diagram illustrating a determination in a case where there is no pinhole in both the reflection film and the second reflection film.

FIG. 4 shows a first example of the disk to be inspected in the optical disk defect inspection apparatus according to the present embodiment for determining the presence or absence of a pinhole.
FIG. 4 is a schematic diagram for explaining determination when only a reflection film has a pinhole.

FIG. 5 shows a second example of the disk to be inspected in the optical disk defect inspection apparatus according to the present embodiment for determining the presence or absence of a pinhole.
FIG. 4 is a schematic diagram for explaining determination when only a reflection film has a pinhole.

FIG. 6 shows a first example of the disk to be inspected in the optical disk defect inspection apparatus according to the present embodiment for determining the presence or absence of a pinhole.
FIG. 8 is a schematic diagram for explaining determination when a reflection film and a second reflection film have a pinhole.

FIG. 7 is a schematic diagram showing a cross-sectional structure of a conventional compact disc.

FIG. 8 is a schematic diagram showing a cross-sectional structure of a conventional multilayer multi-density disc.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 spindle motor 2 laser light source 3 laser irradiation unit 4 light quantity detection unit 5 defect determination unit 6 control unit 7 output terminal 8 disk to be inspected 9 first reflection film 10 second reflection film 201 1/4 wavelength plate 202 deflection beam split 203 Collimating lens 204 Detector 701 Substrate 702 Information surface 703 Reflective film 704 Protective film 705 Print layer 801 First substrate 802 First information surface 803 First reflective film 804 Transparent adhesive layer 805 Second substrate 806 Second Information surface 807 Second reflective film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA49 BB03 BB16 CC03 DD06 FF44 FF49 GG04 GG12 GG22 HH03 HH08 HH13 JJ01 JJ09 LL04 LL14 LL36 LL37 LL62 MM04 MM07 MM14 MM16 PP02 PP13 AQ08 RB01 DA08 EA11 EB01 5D121 AA05 HH01

Claims (4)

[Claims] An optical disk having a first information surface covered with a first reflection film and a second information surface covered with a second reflection film; An optical disc defect inspection apparatus for detecting a defect of a reflective film, a rotation driving means for rotating the optical disc, a part of the light amount reflected by the first reflective film, and a part of the light amount transmitted through the first reflective film; Beam irradiating means for irradiating the optical disc with a light beam having a wavelength which is mostly reflected by the second reflective film; light quantity detecting means for detecting the light quantity of the light beam reflected from the optical disc; The first reflection film and the second
An optical disc defect inspection device, comprising: a defect determining unit that determines whether a reflective film has a defect. 2. The optical disk defect inspection apparatus according to claim 1, wherein said defect determination means includes a first reflection film and a second reflection film when said voltage level of said output signal is substantially equal to a reference level.
An optical disk defect inspection device, which determines that there is no defect in the reflective film. 3. An optical disk defect inspection apparatus according to claim 1, wherein said defect determining means has a defect only in said first reflection film when a voltage level of said output signal is higher than a reference level. An optical disk defect inspection device characterized by determining that: 4. The optical disk defect inspection apparatus according to claim 1, wherein said defect determining means has a defect only in said second reflection film when a voltage level of said output signal is lower than a reference level. Alternatively, the first reflection film and the second reflection film
An optical disk defect inspection device for determining that a reflective film has a defect.