JPS635249A - Method for detecting flaw of planar body - Google Patents

Abstract

PURPOSE:To accurately detect the flaw of a planar body having a large inspection width by a simple means, by positively scattering the reflected or transmitted light from the planar body at the time of optical scanning by a scattering member and allowing the scattering light to be incident to a light transmitting member. CONSTITUTION:The light source 12 of a light irradiating system 11 comprises a laser diode or a light emitting diode and the surface of a planar body 41 is optically scanned by an optical scanner 15 such as a rotary mirror. Corresponding to a reflected or transmitted light receiving region due to the planar body 41, a scattering member 25 and the light incident part of the light transmitting member 21 are relatively arranged on front and rear sides, and the light emitting part of the light transmitting member 21 and a light receiving detection system 31 are preliminarily connected to each other. Then, reflected or transmitted light generated when the surface of the planar body 41 is optically scanned by the light irradiating system 11 is scattered by the scattering member 25 to be incident on the light transmitting member 21 from the light incident part and the incident light is allowed to be incident on the light receiving detection system 31 from the light emitting part and the flaw of the planar body 41 is detected on the basis of the change in a light receiving level.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application 1 The present invention relates to a method for optically detecting defects in various planar objects such as sheets, films, and plates.

rConventional technology Synthetic resin sheets (including films), metal plates.

The flying spot method is widely used as a means for optically inspecting these planar objects such as glass plates.

In this flying spot method, parallel light emitted from a laser light source is focused by a lens system, and the light beam is irradiated and scanned on the surface of the object (planar object) through an optical scanning means. Light or transmitted light is detected by a light receiving and scraping system, and the optical signal is converted from light to light and electrically processed.

When such a method is used, the reflected light or transmitted light from the one-sided object differs between the normal part and the defective part of the one-sided object, and the amount of light incident on the light receiving detection system also differs. By detecting changes in the amount of received light, the presence or absence of a defect in the planar object, the defective location, etc. can be determined.

- In general, optical fiber receiving methods, mirror focusing methods, diffuser plate receiving methods, condenser lens focusing methods, etc. are used as light receiving methods for the flying spot method. There is still room for improvement in terms of ensuring rationality and economy, and therefore a new method shown in Figure 3 is being considered.

The method shown in FIG. 3 will now be explained.

In FIG. 3, the light irradiation system 11 includes a light source 12, a condensing lens 13, and a light scanning means 14.
is mainly composed of an optical scanner 15.

The light-transmitting member 21 is made of a transparent body, and the circumferential surface of a constant width along its longitudinal direction serves as a light input i''[!22, and the - end in the longitudinal direction serves as a light output portion 23. .

The light detection system 31 includes a light receiver (light detection base) 32 and a detection device 33, and the light receiver 32 is connected to the light output portion 23 of the light-transmitting member 21.

41 is a planar body which is a subject.

In FIG. 3, the second position (lower position is also acceptable) of the planar body 41
The light irradiation system 11 arranged at Part 2
1 is arranged as follows.

That is, the one-sided body 41 receives the scanning light Ls from the light irradiation system 11.
When the light-transmitting member 21 reflects

When the planar body 41 is disposed in a region that receives the reflected light LR as shown by the solid line in FIG. The light entering portion 22 of the light transmitting member 21 is disposed in a region that receives the light Lr, and thus the light entering portion 22 of the light transmitting member 21 extends along the width direction of the planar body 41, and the above-mentioned light enters the light transmitting member 21 from the light entering portion 22. The reflected light LR or the transmitted light LT enters, and the scattered light of the light-transmitting member 21 enters the light reception detection system 31.

In FIG. 3, when the planar body 41 is moving in the direction of the arrow in the figure, the light beam emitted from the light source 12 of the light irradiation system 11 and focused by the condensing lens 13 is transmitted to the light scanning means 1.
The surface of the planar body 41 is irradiated through the optical scanner 15 of No. 4, and scanned in the width direction of the planar body 41.
When 1 is an opaque body, the scanning light Ls is reflected on the surface of the planar body 41, and the reflected light LR enters the inside of the transparent member 21 through the light entrance part 22, and conversely, when the planar body 41 is transparent In the case of the body,
The scanning light Ls passes through the planar body 41, and the transmitted light L+ enters the interior of the light-transmitting member 21 through the light entrance portion 22 thereof.

When reflected light 'LR' or transmitted light Ll enters the light-transmitting member 21, part of the light passes through the light-transmitting member 21, but the other part is scattered within the light-transmitting member 21. , the scattered light is incident on the light receiving and detecting system 31.

In this optical scanning, when the scanning light L5 is irradiated to the IF normal part of the planar body 41, the reflected light LR or the transmitted light Ll enters into the transparent member 21 in a steady state, so the light is received. The light reception level at the detection system 31 does not change, and the light reception detection system 31 recognizes that the planar body 41 has no defect.

On the other hand, when the scanning lights t and s are irradiated onto a defective part of the planar body 41, light scattering occurs due to the defect, and light different from that in the IF normal part enters into the transparent member 21. Therefore, the light reception level at the light reception detection system 31 changes, and due to the change in the light reception level, the light reception detection system 31 recognizes that the planar body 41 has a defect.

In this way, defects in the planar body 41 are detected.

Problems to be Solved by the Invention J However, the method shown in FIG. 3 described above has the following problems.

That is, in the planar object inspection shown in FIG. 3, when the light beam from the light irradiation system 11 is optically scanned within the range of angle α+α′ as shown on the left side of FIG. The received light level is as shown on the right side of FIG.

The slope (level difference) between A and B on the right side of Figure 4 is:
When viewed from the light receiver 32 side, internal scattering of the light-transmitting member 21,
This is attenuation due to absorption, and this decreases as the distance from the light receiver 32 increases.

The level difference between B-0 on the right side of FIG. 4 is largely influenced by total reflection due to the difference in refractive index between the intrinsic refractive index of the light-transmitting member 21 and its outer part (air).

- The maximum transmission angle in the light-transmitting member 21, ie, 5ine (see FIG. 5), is determined by the following equation.

s: nO=m nI: Transmissive substance (transparent member 21) nl: Air (nl>nl) Therefore, in principle, the light reception level should increase rapidly from a certain part of the incident angle, but Figure 4B-
The light reception level will be between C and C.

As is clear from the above, when the light between A and C in FIG. Defects cannot be detected accurately.

As a countermeasure for this, it may be possible to utilize only the light between A and B in FIG. 4, but in this case, the inspection width of the one-sided body 41 would be halved.

Of course, by widening the distance between the optical scanner 15 and the planar object 41, the full width inspection of the planar object 41 is performed in rotation, but in this case, the beam-shaped scanning light Ls is larger than the optimum spot diameter. This also increases the detection sensitivity.

Therefore, if the optical scanner 15 is a rotating mirror, f-θ
If the optical scanner 15 is a vibrating mirror due to the lens,
It is necessary to correct the optical path length to the surface of the planar object using arc-sine (sini) and 7 lenses, and if the inspection width is large, a large lens is required, so the inspection system is Economic efficiency cannot be ensured.

In view of the above-mentioned problems, the present invention aims to provide a method for accurately detecting defects in planar bodies having a large inspection width using simple means.

Means for Solving Problem 1 In order to achieve the intended purpose, the present invention scans the surface of a planar body with light using a light irradiation system equipped with a light scanning means, and applies the scanning light to the planar body. In a method for detecting a defect in a planar object by reflecting or transmitting the reflected light or transmitting the light by a light receiving detection system, a change in the reflected light or the transmitted light depending on the presence or absence of a defect in the planar object is provided. A scattering member is placed on the front side and a light entrance part of a light transmitting member is placed on the rear side so as to correspond to the light receiving area, and the light outputting part of the light transmitting member and the light receiving detection system are mutually connected. The reflected light or transmitted light when the surface of the planar object is scanned by the light irradiation system,
The light is scattered by a scattering member and enters the light-transmitting member through the light input section, and the incident light is made to enter the light reception and detection system through the light output section.

Effect J In the case of the method of the present invention, as described above, reflected light or transmitted light from the planar body is scattered by the scattering member and enters the light-transmitting member, and a part of the scattered light is transmitted through the light-transmitting member. The light enters the light receiving and detecting system.

At this time, the reflected light or transmitted light changes depending on the presence or absence of defects in the planar body, and the scattered light also inevitably changes accordingly. Therefore, a part of the scattered light that has passed through the scattering member and the transparent member By detecting with.

Defects in planar bodies and their defective parts can be detected.

Moreover, in the case where the reflected light or transmitted light is actively scattered by a scattering member, the scattered light is made to enter the light-transmitting member, and the negative part thereof is made to enter the light reception detection system from the light-transmitting member as a detection optical signal. , there is almost no difference in the level of received light due to the position of light incidence on the light-transmitting member, internal scattering within the light-transmitting member, etc., and as long as there is no abnormality in the planar body, a constant level of light is sent to the light receiving detection system. It becomes incident.

Therefore, even if there is a difference in the light reception level between the normal part and the defective part of the planar body, there is no difference in the light reception level between the normal parts of the planar body, and as a result, the light that enters the light reception detection system from the transparent member Since the signal is stable, defects in the planar object can be detected accurately.

Of course, the scattering member may be one that causes diffused reflection.
The light-transmitting member only needs to be a transparent member, and there is no need to optically or electrically correct the light that enters the light-transmitting member through the scattering member. The method for receiving and transmitting this to the light receiving and detecting system is simplified.
The economic efficiency and rationality of the inspection system can be ensured.

1 Example 1 Hereinafter, the defect detection method for a planar object according to the present invention will be explained based on the illustrated example.

The method of the present invention shown in FIGS. 1 and 2 is basically the same as the method shown in FIG. 3 above.

Therefore, the configuration of each part in FIGS. 1 and 2 will be mainly explained with reference to its specificity and differences from FIG. 3.

In FIG. 1, the light source 12 of the light irradiation system 11 is composed of a laser diode (LD) such as a gas laser or solid-state laser, or a light emitting diode (LED), and the light scanning means 14 is a rotating mirror (polygon mirror) or a light emitting diode (LED). It is mainly composed of an optical scanner 15 such as a vibrating mirror.

In FIGS. 1 and 2, the light-transmitting member 21 is made of a transparent glass rod (for example, quartz-based) or a transparent plastic rod (for example, acrylic-based, styrene-based, silicone-based), etc., and its cross-sectional shape is , a circular shape, a rectangular shape, a notched circular shape with the light entrance portion 22 being a flat surface, etc. can be adopted.

As described above, the light-transmitting member 21 is arranged in a predetermined light-receiving area corresponding to the width direction of the planar body 41, and the reflected light or transmitted light from the planar body 41 is reflected at a constant angle of incidence. In some cases, an arcuate shape curved with a predetermined curvature is used to allow the light to enter.

Furthermore, regarding the light-transmitting member 21, the one shown in FIG. 2(A) is as follows.
Its lower end is a light emitting part 23 and the other end is a reflecting part 24, and the reflecting part 24 is constructed by coupling a transparent member having a reflective surface such as a mirror surface to the other end of the transparent member 21. has been done.

On the other hand, the light transmitting member 21 shown in FIG. 2(B) has light emitting portions 23 at both ends thereof.

The light-transmitting member 21 has a light entrance portion 22 arranged over the aforementioned predetermined light-receiving region, that is, the width direction of the planar body 41, and a scattering member 25 is arranged in front of the light entrance portion 22.

The scattering member 25 is made of plate-shaped glass, plastic, or the like, and has been subjected to a scattering process to cause light scattering, such as frosted glass.

The scattering member 25 may also be curved in the same manner as described for the light-transmitting member 21.

The light reception detection system 31 includes a light receiver (such as a photodiode or an avalanche photodiode (APD)).
The detection device 33 includes a photodetector) 32 and an electric/electronic signal processing circuit, a recorder, etc., and the light receiver 32 is connected to the light output portion 23 of the light-transmitting member 21.

In the case of FIG. 2(B) in which the light emitting parts 23 are provided at both ends of the light-transmitting member 21, both the light emitting parts 23 are connected to the light receiving detection system 31, but the light receiving detecting system in this specific example 31
performs a predetermined detection by averaging the amount of light incident from the two light output sections 23.

The planar body 41 may be transparent or opaque, such as a synthetic resin sheet, a synthetic resin film, a metal plate, or a glass plate.

Hereinafter, an example of defect detection of the planar body 41 by the method of the present invention will be described.

In FIG. 1, when the one-sided body 41 is moving in the direction of the arrow in the figure, the light source 12 of the light irradiation system 11
The light beam emitted from the condenser lens 13 is passed through the optical scanner 15 of the optical scanning means 14 to the planar body 41.
The beam is irradiated onto the surface of the planar body 41 and scanned in the width direction of the planar body 41.

In this case, if the planar body 41 is an opaque body, the scanning lights t and s will be reflected on the surface of the planar body 41, and conversely, if the planar body 41 is a transparent body, the scanning lights t and s will be reflected on the surface of the planar body 41. 41, the reflected light LR or the transmitted light L+ is scattered by the scattering member 25 and enters the inside of the light-transmitting member 21 through the light entrance portion 22 thereof.

When the reflected light LR or the transmitted light Lr enters the light transmitting member 21, a part of the light passes through the light transmitting member 21, but the other part passes from the light transmitting member 21 to the light receiving detection system 31.
Eight injections are made.

In the light reception detection system 31, the light reception level at this time is detected and arithmetic processed through the light receiver 32, the detection device 33, etc., and the presence or absence of a defect in the planar body 41 is detected based on the light reception level.

That is, in the above-mentioned optical scanning, when the normal part of the planar body 41 is irradiated with the scanning lights t and s, the reflected light LR or the transmitted light Ll is in a steady state and moreover is scattered by the scattering member 25 and transmitted. Since the light enters the member 21, there is no change in the level of light received by the light reception detection system 31, and the light reception detection system 3
1 recognizes that the planar body 41 has no defects.

On the other hand, if the one-sided body 41 has a defect such as a scratch, foreign matter, or contamination, and the scanning light Ls is irradiated onto this, the light will be scattered due to the defect, and the light will be different from that in the normal area. enters the light-transmitting member 21, the level of light received by the light reception detection system 31 changes, and the light reception detection system 31 recognizes that the planar body 41 has a defect due to the change in the light reception level.

More specifically, the light reception and detection system 31 photoelectrically converts the optical signal based on the defect by the photoreceiver 32, and the detection device 33 performs arithmetic processing on the signal, thereby recognizing the defect in the planar body 41. Report the defect and record the defective part.

In this way, defects in the one-sided body 41 are detected.

r Effects of the Invention J As explained above, according to the method for detecting defects in a planar object according to the present invention, reflected light or transmitted light from the planar object during optical scanning is actively scattered by a scattering member to detect the defect in the planar object. The scattered light is made to enter the light-transmitting member, and the negative part thereof is made to enter the light-receiving and detecting system from the light-transmitting member as an optical signal for detection.

Even without the need for electrical correction means, defects in wide planar bodies can be detected accurately with simple means, and this type of inspection can thus be carried out economically and rationally.

[Brief explanation of drawings]

FIG. 1 is a perspective view schematically showing an embodiment of the method of the present invention, and FIG.
Figures (A) and (B) are side views schematically showing different specific examples of the method of the present invention, FIG. FIG. 5 is an explanatory diagram showing the light reception level, and FIG. 5 is an explanatory diagram showing the maximum transmission angle of the light-transmitting member in the method of FIG. 3. 11...Light irradiation system 12...Light source 13 of the light irradiation system...Condensing lens 14 of the light irradiation system...
・Light scanning means 15 of the light irradiation system...Light scanner 21 of the light scanning means...Light-transmitting member 22...Light entrance part 23 of the light-transmitting member... ... Light emitting part 24 of the light-transmitting member ... Reflection part 25 of the light-transmitting member ... Scattering member 31 ... Light reception detection system 32 ... Light reception detection Light receiver 33 of the system...Detection device 41 of the light reception detection system...
- Planar body Ls...Scanning light LR...Reflected light Ll...Transmitted light Agent Patent attorney Yoshio Saito Figure 1 291

Claims (1)

[Claims] A light irradiation system equipped with a light scanning means scans the surface of the planar object, and the scanning light is reflected or transmitted from the planar object. In a method of detecting a defect in a planar object by detecting a change using a light receiving detection system, a light incident part of a scattering member on the front side and a light transmitting member on the rear side corresponds to the light receiving area of the reflected light or transmitted light. are arranged relative to each other, and the light emitting part of the light transmitting member and the light reception detection system are connected to each other, and the reflected light or transmitted light when the surface of the planar body is scanned by the light irradiation system is 1. A method for detecting defects in a planar object, characterized in that the incident light is scattered by a scattering member and enters a light-transmitting member through the light input section, and the incident light is made to enter a light reception detection system through the light output section.