JPH05182256A - Disk defect inspection device - Google Patents

Abstract

PURPOSE:To improve a working efficiency and a precision of detection of defects. CONSTITUTION:Rays for inspection irradiate from a peripheral edge part of a laser-vision-disk 30 to inside, the surface of a disk base board 31 is image picked up by CCD camera 50 and scattered rays from the surface is received to discriminate defects since a judge of defects become easily, a working efficiency and a precision of detection of defects are improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk defect inspection apparatus for detecting defects such as scratches and pinholes existing on the surface of a disk or inside a disk by optical inspection.

[0002]

2. Description of the Related Art Conventionally, laser vision discs (L
Defects such as scratches and pinholes existing on the surface of optical discs such as VDs and compact discs (CDs) and inside the discs have been found by visually inspecting each one. However, such visual inspection requires not only skill but also poor work efficiency,
Moreover, since there are variations due to individual differences, defective products may be judged to be good products.

In order to avoid such a situation, attempts have been made to automate defect inspection, for example, Japanese Patent Laid-Open No. 1-3.
Japanese Patent No. 13741 discloses a disc surface inspection device as shown in FIG. As shown in the figure, the scanner 2 including the laser oscillator and the rotary polygon mirror is
And scanning is performed to form scanning lines 5 on the surface of the CAV type LVD 4. The position of this scanning line 5 is LVD
The straight line 15 passing through the rotation center axis 6 of 4 is translated to the near side by a distance L. The value of this distance L is 1
It is 0 mm or more.

The light receiver 7 receives the scattered light 11 scattered from the surface of the LVD 4 according to the scanning line 5. The scattered light 11 is not only the light scattered and reflected by the defect portion S existing on the surface of the LVD 4, but also the transparent layer 8 and is diffracted by the pits.
It also contains the scattered light. When the defect portion S does not exist on the surface of the LVD 4, the light beam 3 is reflected in a certain direction as the specular reflection light 3a and does not enter the light receiver 7.

Therefore, in this case, only the scattered light from the pit enters the light receiver 7. Also, the LVD 4 is rotated by the disk rotating device 17 for inspection over the entire circumference.

The light receiver 7 outputs a photoelectric signal of a level corresponding to the amount of incident light to the defect detection circuit 18. Defect detection circuit 1
In 8, the sample and hold circuit 19 first shapes the photoelectric signal from the light receiver 7 into a waveform based on a predetermined sampling period. The bandpass filter 20 extracts a change in the photoelectric signal when the defective portion S exists from the output of the sample hold circuit 19. The low-pass filter 22 extracts a low frequency component from the photoelectric signal output from the sample hold circuit 19. The binarization circuit 21 binarizes the output from the bandpass filter 20 with the threshold signal from the amplifier 23 as a reference.

In the disk surface inspection apparatus having such a configuration, since the inspection is performed over the entire circumference of the LVD 4,
The VD 4 is rotated at a low speed by the disc rotating device 17. However, the scanning speed of the light beam 3 is much higher than the rotation speed of the LVD 4.

When the surface of the LVD 4 is irradiated with the light beam 3 by the scanner 2, a part of the light beam 3 is absorbed by a light absorber (not shown) without entering the light receiver 7 as specular reflection light 3a. In addition, it passes through the transparent layer 8 and reaches the signal recording surface,
The scattered light 11 diffracted and scattered by the pits emerges from the surface of the LVD 4. The scattered light 11 has an arc pattern corresponding to the pit shape, but the position of the scanning line 5 is LV.
Since the straight line passing through the rotation center axis 6 of D4 is translated by the distance L, the arc-shaped pattern of the scattered light 11 is inclined as the scanning position approaches the inner side.

As a result, as shown in FIG. 2, most of the scattered light 11 is incident on the light receiver 7 having the light receiving width D even when the scanning position is inside. Therefore, if there is no defective portion during one scan, the photoelectric signal output from the light receiver 7 has some level fluctuation as shown in FIG.
The fluctuation range is quite small.

The operation of the disk rotating device 17 causes LVD
4 rotates and the defect S existing on the surface of the light beam 3
When the light beam 3 moves to the irradiation area of, that is, above the scanning line 5, the light beam 3 becomes scattered by the defect portion S in the process of scanning. As a result, the photoelectric signal output from the light receiver 7 is the photoelectric signal output shown in FIG. 3 plus the scattered reflected light from the defect portion S.

If, for example, two defective portions S are present during one scanning period of the light beam 3, the signal line (A) of FIG.
Signal waveforms as shown in FIG. 4 appear in (B), (C), and (D). That is, the photoelectric signal output from the light receiver 7 includes the ripple component a due to the scattered reflected light from the defect S, as shown in FIG. The photoelectric signal output from the light receiver 7 is waveform-shaped by the sample hold circuit 19 and the bandpass filter 20 as shown in FIG. Further, the low-pass filter 22 extracts the low frequency, that is, the “undulation” component included in the photoelectric signal output from the light receiver 7.

The "waviness" component extracted from the photoelectric signal output from the photodetector 7 has a waveform shown in FIG. 4C by the amplifier 23, which is used as a threshold signal of the binarization circuit 21. The binarization circuit 21 outputs a binarized signal "1" indicating "defective" when the signal output of FIG. 7B exceeds the threshold signal of FIG. The inspection output as shown in (D) is obtained.

Therefore, the scanning position of the light beam 3 is LV.
Even in the case of being close to the inside of D4, the scattered reflected light from the defect portion S can be satisfactorily detected.

[0014]

However, in the above-described conventional disk surface inspection apparatus, the light beam 3 from the scanner 2 is applied to the surface of the LVD 4, and the scattered reflected light is received by the light receiver 7.
The method of receiving light is adopted. Therefore, in addition to scratches or the like to be originally detected, even if dust or the like that can be eliminated by wiping is attached, it is detected as a defect.

In such a case, it is necessary to wipe off dust and the like on the surface of the LVD 4 and then perform the defect inspection again by the inspection device, resulting in a drawback that work efficiency is reduced. Further, since the defect is detected by the scattered reflection light from the surface of the LVD 4, the difference in contrast between the defective portion and the non-defective portion is small, and in some cases, the defective portion cannot be detected.

The present invention has been made in consideration of such a situation, and the inspection light is projected from the end edge side of the disk substrate into the inside of the disk substrate, so that the defect can be easily judged, and as a result, Another object of the present invention is to provide a disk defect detection device capable of improving work efficiency and defect detection accuracy.

[0017]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is to optically inspect a disk made of a transparent disk substrate on one side of which a signal corresponding to information is recorded for defects. A disk defect inspection device of
An inspection light projecting unit that projects inspection light from the edge side of the disc substrate into the disc substrate, and a defect detection unit that receives scattered reflected light emitted from the surface of the disc substrate and detects a defect of the disc. It is characterized by having.

[0018]

In the disk defect inspection apparatus of the present invention, when the inspection light is projected from the edge side of the disk substrate to the inside of the disk substrate by the inspection light projection means, the defect detection means detects scattered scattered light emitted from the surface of the disk substrate. A disc defect is detected.

That is, when the inspection light propagates inside the disk substrate by total reflection and reaches the inside of the disk substrate or a defective portion on the surface, the inspection light is scattered and reflected and emitted from the surface of the disk substrate. Since the dust or the like is attached to the disk substrate surface in a floating state without adhering to it, the inspection light is not scattered and reflected by this. Further, since the inspection light incident on the inside of the disk substrate progresses by total reflection in a portion having no defect, there is no possibility that dust or the like is erroneously detected as a defect, and the brightness of the defective portion and the non-defective portion is not detected. The level difference can be increased.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 5 shows an embodiment of the disk defect inspection apparatus of the present invention, which is a laser vision disk (LV
D) A light irradiating member 40 as an inspection light projecting means for projecting the inspection light into the inside of the disk substrate 31 described later is arranged in the vicinity of the edge portion of D. A CCD camera 50 as a defect detecting means for inspecting the appearance of the LVD 30 based on scattered light from the surface of the disk substrate 31 is arranged in a direction orthogonal to the recording surface of the LVD 30.

The LVD 30 has a structure in which single disks A and B are bonded together, as shown in FIG. 6, for example. Each single plate A, B is provided with a disk substrate 31 made of a transparent synthetic resin such as acrylic resin or polycarbonate. A reflective film 32 made of aluminum is formed on each disk substrate 31. A plastic protective film 33 is formed on the reflective film 32. In addition, 3 in the figure
Denoted at 4 is a pit formed on the surface of the disk substrate 31.

The light irradiating member 40 is provided with a light projecting member 43 having a slit 41 for projecting the inspection light of the thickness of the disk substrate 31. Thereby, the slit 41
Since the width of the inspection light projected from the device is thinned, the leakage of the inspection light to the outside of the disk substrate 31 can be made extremely small, and the difference in the brightness level of the defective portion can be increased as described later. ..

An optical fiber 44 for transmitting inspection light from a light source (not shown) is connected to the light projecting member 43. Here, as the inspection light transmitted by the optical fiber 44, halogen light, laser light, or the like is used.

A light irradiation member 40 for the disk substrate 31.
The positions of the slits 41 are aligned by an alignment mechanism (not shown). CCD camera 50 is LV
A predetermined area of the surface of D30 is imaged.

Here, it is desirable that the area of the disk substrate 31 imaged by the CCD camera 50 is a place sufficiently distant from the place where the inspection light is incident. This is because the intensity of the incident inspection light is high, and the intensity of the light leaking from the surface of the disk substrate 31 is high in a region near the incident position, which makes it difficult to detect defects.

The visual inspection of the LVD 30 is performed as follows. First, as shown in FIG.
Is rotated at a predetermined rotation speed. The inspection light is made incident on the inside of the disk substrate 31 from the outer peripheral edge portion through the slit 41 of the light irradiation member 40. One of the reasons for injecting the inspection light from the outer peripheral edge of the disk substrate 31 is that it can detect streak-shaped defects extending in the radial direction of the disk substrate 31. When such a defect is made incident from the inner peripheral edge of the disc substrate 31, the incident direction of the inspection light is limited to the radial direction of the disc substrate 31, which makes detection difficult.

Since the disk substrate 31 made of synthetic resin such as acrylic or polycarbonate has a higher refractive index than air, the light incident on the boundary surface 35 with air at a critical angle or more is repeatedly totally reflected by the boundary surface 35. Proceed inside the substrate 31.

If a part of the disk substrate 31 has a defect 36 such as a scratch as shown in FIG. 8, the angle of the boundary surface 35 at that part changes. In such a case, the defect 36
Since the angle of incidence of the inspection light on the boundary surface 35 at the portion is small, the inspection light at that portion is scattered to the outside of the disk substrate 31. When the area of the defect 36 is imaged by the CCD camera 50, a signal output can be obtained as shown in FIG. Here, level A in FIG.
Is due to leakage of the inspection light incident on the boundary surface 35 of the disk substrate 31 at an angle smaller than the critical angle to the outside.

Further, as shown in FIG. 9, the disk substrate 31
When a viscous substance 37 such as an adhesive is adhered and adheres to the upper part, the light incident from the inside of the disk substrate 31 to the viscous substance 37 side is scattered on the surface of the viscous substance 37. In this case as well, by imaging the area of the viscous material 37 with the CCD camera 50 in the same manner as described above, a signal output as shown in FIG. 12B can be obtained.

Further, as shown in FIG. 11, the disk substrate 3
Even if there is a defect such as a bubble 39 generated in the inside of the substrate 1 during the molding process of the substrate 1, light scattering occurs at that portion, so that a signal output as shown in FIG. 12 is obtained.

Then, such a signal output is compared with the threshold level B, and when the threshold level B is exceeded, "there is a defect".
It is possible to obtain a defect detection output indicating However, as shown in FIG. 10, since dust 38 that can be removed by wiping off the disk substrate 31 is not in close contact with the disk substrate 31 and is attached in a floating state, the inspection light is scattered and reflected. There is no end.

As described above, in this embodiment, the slit 41 is
The inspection light is projected from the outer peripheral edge portion of the LVD 30 to the inside through the CCD camera 50, and the disc substrate 31
Since the surface of is imaged and the scattered light from the surface is received to determine the defect, the presence or absence of the defect can be easily determined, and the work efficiency and the defect detection accuracy are improved.

In the present embodiment, the case where the disk inspection target is the LVD having the structure in which the single disks A and B are bonded together has been described, but the present invention is not limited to this example, and a single disk such as a CD is used. It may be an inspection target.

In the present embodiment, the case where the disc substrate 31 is rotated at a predetermined number of revolutions at the time of determining a defect has been described, but the present invention is not limited to this example, the disc substrate 31 is fixed, and the light irradiation member 40 and It is also possible to sequentially move the CCD camera 50 side and perform defect determination in the same manner.

Further, in this embodiment, the case where the inspection light is projected from the outer peripheral edge of the LVD 30 to the inside through the slit 41 has been described, but the present invention is not limited to this example.
The inspection light may be projected from the inner peripheral edge portion of the center opening of 0 to the inside thereof, and the defect determination may be performed in the same manner.
Further, in order to prevent the detection level from being lowered due to the influence of outside light, it is preferable to carry out defect discrimination in a dark room environment.

[0036]

As described above, according to the disk defect inspection apparatus of the present invention, the inspection light projection means projects the inspection light from the edge side of the disk substrate into the inside of the disk substrate, and the defect detection means performs the disk operation. The defect of the disk is detected from the scattered reflected light emitted from the surface of the substrate.

That is, when the inspection light propagates inside the disk substrate by total reflection and reaches the inside of the disk substrate or a defective portion on the surface, the inspection light is scattered and reflected and emitted from the surface of the disk substrate. Since the dust or the like is attached to the disk substrate surface in a floating state without adhering to it, the inspection light is not scattered and reflected by this. Further, since the inspection light incident on the inside of the disk substrate progresses by total reflection in a portion having no defect, there is no possibility that dust or the like is erroneously detected as a defect, and the brightness of the defective portion and the non-defective portion is not detected. The level difference can be increased.

Therefore, by projecting the inspection light into the inside of the disc substrate from the edge side of the disc substrate, it becomes possible to easily determine the defect and the type of the defect.
It is possible to improve work efficiency and defect detection accuracy.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a conventional disk defect inspection apparatus.

FIG. 2 is a diagram showing a defect detection state by the disk defect inspection apparatus of FIG.

FIG. 3 is a diagram showing a defect detection state by the disk defect inspection apparatus of FIG. 1.

4 is a diagram showing a defect detection state by the disk defect inspection apparatus of FIG. 1. FIG.

FIG. 5 is a perspective view showing an embodiment of the disk defect inspection apparatus of the present invention.

FIG. 6 is a diagram showing a structure of the disc of FIG.

7 is a diagram showing a state of progress of inspection light by the disk defect inspection apparatus of FIG.

FIG. 8 is a diagram showing a case where the disc of FIG. 1 is scratched.

9 is a diagram showing a case where an adhesive is attached to the disc of FIG. 1. FIG.

10 is a diagram showing a case where the disc of FIG. 1 has dust.

11 is a diagram showing a case where bubbles are present in the disc of FIG. 1. FIG.

FIG. 12 is a diagram showing a brightness level difference due to the defects of FIGS. 8 to 11;

[Explanation of symbols]

 30 LVD 40 Light Irradiating Member 31 Disk Substrate 32 Reflective Film 40 Light Irradiating Member 41 Slit 43 Light Emitting Member 44 Optical Fiber 50 CCD Camera

Claims (1)

[Claims] 1. A disk defect inspection device for optically inspecting a disk defect consisting of a transparent disk substrate on one side of which a signal corresponding to information is recorded, the edge portion of the disk substrate. The inspection light projection means for projecting the inspection light into the inside of the disk substrate from the side, and the defect detection means for receiving the scattered reflection light emitted from the surface of the disk substrate and detecting the defect of the disk. Disk defect inspection system.