JPH10176995A - Method and apparatus for inspection for transparent object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a transparent-object inspection apparatus by which the fault of a transparent object and dust particles stuck on the transparent object can be discriminated and detected automatically. SOLUTION: A transparent-object inspection apparatus is provided with an inspection camera 18 which is arranged so as to be faced with one fact side of a liquid-crystal glass 1 to be moved and which scans the glass 1 in a direction crossed at right angles to its movement direction, with an illumination device 19 which is arranged so as to be faced with the other face side of the glass 1 and which illuminates the visual field of the camera 18, and with a signal processing part 12 by which brightness information is discriminated from darkness information on the basis of an inspection signal obtained by the imaging operation of the camera 18. The illumination device 19 is composed so as to be provided with a light-shielding body 19c arranged on the optical axial 18c of the camera 18 and with a light source 19b arranged on the side face of the light-shielding body 19c so as to be deviated from the optical axis 18c. The camera 18 receives transmitted refracted light which is projected from the illumination device 19 so as to be refracted inside the glass 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a transparent body such as a transparent glass substrate and a flexible synthetic resin substrate provided in a liquid crystal display device with a backlight, and a method for inspecting the transparent body for defects. Related to the device.

[0002]

2. Description of the Related Art A transparent glass substrate (hereinafter abbreviated as "liquid crystal glass") provided in a liquid crystal display device with a backlight is provided.
If there is a defect, that is, a scratch (hereinafter abbreviated as a scratch) on the front or back surface of the liquid crystal glass, a bubble or a cullet (a small thing in the bubble), etc., the light of the backlight is generated at the defect. It is known that, because of refraction, color display becomes uneven in color display, and black-and-white display looks blackish.

In order to avoid such a point, it is necessary to inspect the liquid crystal glass for defects. For this reason, conventionally, inspection is generally performed by visual inspection in a clean room by a human, and based on the inspection result, the liquid crystal glass is polished or discarded.

An automatic inspection for defects of a transparent film, which is not a liquid crystal glass, is performed as follows. In this automatic inspection, an inspection camera is installed at an inspection position of the transparent body so as to face one surface of the transparent body, and an illumination device for illuminating a field of view of the camera is provided on the other surface side of the transparent body.
The light source of the illuminating device is arranged on the optical axis of the camera, and the light emitted therefrom passes through the transparent body without being refracted and enters the camera, and the inspection camera has a one-dimensional CCD that it has. The field of view is scanned by an image sensor along a width direction perpendicular to the moving direction of the transparent body to obtain inspection information. Such an optical inspection is called a direct transmission method. Then, it is considered that this inspection method is applied to the inspection of the liquid crystal glass.

[0005]

However, the disadvantage of the liquid crystal glass is minute, equivalent to a minimum of 20 μm. In a visual inspection in which it is necessary to perform this under an expanded field of view with a magnifying glass or the like, the inspection efficiency is low. Very bad.

[0006] Further, the present applicant has tried the automatic inspection by the direct transmission method, but found that there are the following problems. In other words, the production of liquid crystal glass is performed in a clean room, and although inspections are conducted by the direct transmission method in this clean room, the ingress and egress of workers due to the ingress and egress of dust of the size equivalent to the defect size of the liquid crystal glass Cannot be avoided, and this dust adheres to the liquid crystal glass.

Since the above-mentioned automatic inspection is performed in a state where the dust adheres, the dust adhering to the glass surface during scanning by the inspection camera blocks transmitted light which is going to be incident on the inspection camera from the illumination device, and the liquid crystal glass surface It is imaged with the defect. Therefore, in the inspection signal (inspection information) output from the inspection camera, the voltage of the signal component of the defect and the dust is lower than the level of the signal component (formation level) of a normal portion having no defect and the dust. This is so-called dark information. Therefore, when trying to automatically detect defects by performing signal processing on the inspection signal by an electronic circuit,
Since the defect cannot be distinguished from the dust and the dust is erroneously recognized as a defect, it has been found that such an automatic inspection by the direct transmission method is not suitable for practical use.

[0008] The first problem to be solved by the present invention is:
An object of the present invention is to provide a method and an apparatus for inspecting a transparent body, which can automatically detect a defect of the transparent body and dust adhering to the transparent body by discriminating them.
Further, in the automatic inspection by the direct transmission method, even if the defect is on the front surface, the back surface, or inside the liquid crystal glass,
Since all are detected as dark information, it is not possible to know the position of the defect in the thickness direction (the front surface, the back surface, or the inside) of the defect based on the information. Therefore, for example, when the liquid crystal glass is polished again, there is a problem that it is not possible to determine which surface should be polished again.

Accordingly, a second object of the present invention is to provide a transparent body inspection apparatus capable of automatically detecting the position of a defect in the thickness direction while solving the first object.

[0010]

According to a first aspect of the present invention, there is provided a method for inspecting a transparent body, wherein the method is arranged to face a transparent body to be moved at a first inspection position. A first inspection camera that scans the transparent body in a direction intersecting at right angles to the direction of movement of the first inspection camera, on the optical axis of the first inspection camera on the opposite side of the first inspection camera with the transparent body interposed therebetween. Receiving a transmitted light emitted from a first illuminating device having a light source disposed at a right angle and transmitting at right angles in a thickness direction without refracting the transparent body to obtain a first inspection signal, and obtaining the first inspection. At a second inspection position downstream or upstream of the position, a second inspection camera arranged to face the transparent body and scans the transparent body in a direction perpendicular to the moving direction of the transparent body, and Opposite to the second inspection camera in between And a refracted light projected from a second lighting device having a light-shielding body disposed on the optical axis of the second inspection camera and a light source disposed on the side thereof, and refracted through the transparent body and transmitted therethrough. Receiving light to obtain a second inspection signal,
Then, the first and second inspection signals are compared.

According to the first aspect of the present invention, the first
Obtain inspection information by the direct transmission method at the inspection position. That is,
The first illumination device illuminates the field of view of the first inspection camera, transmits the light at right angles to the thickness direction of the transparent body without refracting the transparent body, and the first inspection camera illuminates the field of view of the transparent body. The transmitted light transmitted as described above is received. Thereby, the first inspection signal including the dark information on the defect of the transparent body and the dust attached to the transparent body is obtained.

At the second inspection position downstream or upstream of the first inspection position (in other words, before or after obtaining the first inspection signal), inspection information is obtained by the indirect transmission method. In other words, the second illumination device illuminates the field of view of the second inspection camera, but since there is a light shield on the optical axis of the second inspection camera, the light projected from the second illumination device is oblique to the field of view. The second inspection camera receives the refracted light that has been transmitted by refracting the visual field as described above. In such an indirect transmission method, since the second inspection camera does not directly look at the light source, if there is a defect in the transparent body, scattered light diffracting that part enters the second inspection camera. Thereby, this defect looks shiny and can therefore be detected as bright information with a voltage higher than the formation level. Also,
Dust adhering to the transparent body is shielded from light as in the case of the direct transmission method, and can be detected as dark information. In this way, a second inspection signal including bright information about the defect of the transparent body and dark information about dust adhering to the transparent body is obtained.

Then, the first and second inspection signals obtained by the first and second inspection cameras are compared with their addresses. Accordingly, if the first check signal is dark information and the second check signal is bright information for a certain address, it is considered as a defect. Similarly, the first check signal and the second check signal for a certain address are determined. Are all dust information, it is determined to be dust.

Therefore, in the transparent object inspection method according to the first aspect, the inspection signals obtained by the combination of the direct transmission method and the indirect transmission method as described above are compared to discriminate the defect of the transparent object from dust. Can be automatically detected.

Also, in order to solve the first problem, a transparent body inspection apparatus according to a second aspect of the present invention is disposed to face one side of a transparent body to be moved so as to move the transparent body in the moving direction. An inspection camera that scans in a direction that intersects at right angles, an illuminating device that is disposed opposite to the other surface of the transparent body and illuminates the field of view of the inspection camera, and bright information from an inspection signal obtained by imaging the inspection camera. A signal processing unit for discriminating dark information, wherein the illumination device is disposed on the optical axis of the inspection camera, and a light-shielding unit disposed off the optical axis and disposed on a side of the light-shielding unit. The inspection camera receives refracted light projected from the illumination device, refracted in the transparent body, and transmitted therethrough.

In the transparent object inspection apparatus according to the second aspect, the optical inspection section formed by the inspection camera and the illumination device includes:
The inspection by the indirect transmission method already described in the first aspect of the present invention is performed.

That is, in this inspection, the light projected from the illumination device is oblique to the visual field because the light blocking member of the illumination device is on the optical axis of the inspection camera that scans the visual field illuminated by the illumination device. The inspection camera receives the refracted light that is transmitted through the refraction of the field of view as described above. In such an indirect transmission method, since the inspection camera does not directly look at the light source, if there is a defect in the transparent body, scattered light diffracting that part enters the inspection camera. Thereby, the defect looks shiny, and thus the defect can be detected as bright information having a voltage higher than the formation level. Further, dust adhering to the transparent body blocks the refracted light, and can be detected as dark information.

Since the inspection signal output from the inspection camera includes bright information about the defect of the transparent body and dark information about dust adhering to the transparent body as described above,
The signal processing unit to which the inspection signal is supplied discriminates between the two using the level difference between the bright and dark information.

As described above, in the transparent body inspection apparatus according to the second aspect, an inspection signal capable of discriminating between a defect and dust is obtained by one system of optical inspection section for performing inspection by an indirect transmission method, and the signal is processed by a signal processing section. Since the discrimination is performed by the circuit processing in the above, the defect of the transparent body and the dust can be automatically distinguished and detected.

Further, in order to solve the second problem,
4. A transparent body inspection apparatus according to claim 3, wherein the inspection camera scans the transparent body in a direction orthogonal to the moving direction of the transparent body and is disposed opposite to one surface side of the transparent body to be moved, and the other surface of the transparent body. An optical inspection unit comprising an illumination device which is arranged opposite to the side and illuminates the field of view of the inspection camera is provided in two systems shifted in the moving direction of the transparent body, and the illumination device is provided with an optical axis of the inspection camera. An optical inspection device comprising: a light shielding member disposed on the upper side; and a light source disposed off the optical axis and disposed on a side of the light shielding member, and one of the two optical inspection units. The angle of refraction of the refracted light in the field of view due to the illumination of the illumination device of the other optical inspection unit is smaller than the angle of refraction of the refracted light in the field of view due to the illumination of the illumination unit of the inspection unit. Bright information and darkness from the inspection signal obtained by Thereby discriminating between distribution, it is characterized by comprising a signal processing unit for comparing the light information comrades.

In the transparent body inspection apparatus according to the third aspect, the optical inspection units provided in two systems with the positions shifted in the moving direction of the transparent body each perform the inspection by the indirect transmission method described above. In this case, the refraction angle of the refracted light in the visual field by one optical inspection unit is smaller than the refraction angle of the refracted light in the visual field by the other optical inspection unit. Thereby, the bright information on the defect included in the inspection signal of the inspection camera that has received the refracted light having the larger refraction angle is regarded as the bright information of the high voltage level with respect to the defect on the transparent body surface (the inspection camera side). ,
In addition, the defect on the back surface of the transparent body (the lighting device side) is regarded as bright information at a low voltage level. Conversely, bright information about the defect in the inspection camera that has received the refracted light with the smaller refraction angle is regarded as low-voltage bright information about the defect on the transparent body surface (the inspection camera side), and Defects on the back surface of the transparent body (the lighting device side) are regarded as bright information at a high voltage level.

The signal processing section compares the inspection signals supplied from the inspection cameras of both inspection sections with their addresses. As a result, when the inspection signals from both optical inspection units are both bright information for a certain address, it is determined to be a defect. Similarly, for a certain address, the inspection signals from both optical inspection units are both dark information. In some cases, the dust is determined.

In addition, the signal processing section compares characteristic bright information having different signal levels between the front surface and the back surface of the transparent body depending on the angle of refraction as described above (in other words, the magnitude of the signal level is compared. To)
The position of the defect with respect to the transparent body in the thickness direction is determined.

As described above, in the apparatus for inspecting a transparent body according to the third aspect, an inspection signal capable of discriminating between a defect and dust is obtained by two types of optical inspection sections for performing inspection by an indirect transmission method, and the signal is processed by a signal processing section. In the circuit processing in the above, it is possible to distinguish between the defect of the transparent body and the dust, and to automatically detect the defect, and the position of the detected defect in the thickness direction with respect to the transparent body is also automatically determined. Can be detected.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a view showing a configuration of a transparent body inspection apparatus according to a first embodiment, which is used for defect inspection of a transparent inspection glass, for example, a liquid crystal glass 1. The manufacturing environment of the liquid crystal glass 1 is in a clean room, and the liquid crystal glass 1 is moved to an inspection area in the clean room by a transport means (not shown) while maintaining a horizontal posture and installed in the inspection area. Are automatically inspected by the transparent object inspection apparatus according to (1). Note that the arrow in FIG. 4 indicates the moving direction of the liquid crystal glass 1.

The disadvantages of the liquid crystal glass 1 include a surface flaw 2 such as a scratch on the surface of the liquid crystal glass 1 (the upper surface in the inspection position) as shown in an exaggerated manner in FIG.
Of the liquid crystal glass 1 (including a cullet having a small bubble).

This inspection apparatus includes first to fourth optical inspection units, a gain correction circuit 11, and a signal processing unit 12 as detection means. The first provided at the first inspection position
The optical inspection unit includes a first inspection camera 15 arranged opposite one surface, for example, the surface of the liquid crystal glass 1 to be moved, and a liquid crystal glass 1 on the opposite side of the first inspection camera 15 with the liquid crystal glass 1 interposed therebetween. 1st lighting device 1 arrange | positioned facing the other surface
6 is provided.

The first inspection camera 15 has a one-dimensional CCD image sensor (also referred to as a CCD line image sensor or a CCD linear array image sensor) as a photo-electric conversion type viewing angle sensor in the light receiving portion 15a. CCD
A camera is employed. The camera 15 scans the liquid crystal glass 1 along a width direction orthogonal to the moving direction.

The first lighting device 16 has one light source 16b accommodated in a reflecting mirror 16a. A straight tube fluorescent lamp is used as the light source 16b, and the light source 16b is provided to extend in the width direction of the liquid crystal glass 1. This first lighting device 16
The light source 16b is arranged and provided on the optical axis 15c of the first inspection camera 15;
The light illuminating the field of view of the first inspection camera 15 is transmitted through the inspection glass 1 at right angles in the thickness direction without being refracted, and is received by the first inspection camera 15.

A second optical inspection section provided at a second inspection position, for example, on the downstream side of the first inspection position, includes a second inspection camera 1 arranged opposite one surface, for example, the surface of the liquid crystal glass 1.
8 and a second illuminating device 19 disposed opposite to the second inspection camera 18 with the liquid crystal glass 1 interposed therebetween and opposed to the other surface of the liquid crystal glass 1. The second optical inspection section may be provided on the upstream side of the first inspection position.

As the second inspection camera 18, a CCD camera having a one-dimensional CCD image sensor as a photoelectric conversion type viewing angle sensor in the light receiving portion 18a is employed. The camera 18 scans the liquid crystal glass 1 along a width direction orthogonal to the moving direction.

The second illuminating device 19 has a light-shielding body 19b and two light sources 19c housed in a reflecting mirror 19a. For example, a black light shielding plate is adopted as the light shielding body 19b.
When detecting oil stains or the like as a defect, a white light-shielding plate may be used and is not limited to a plate. The light shield 19b is provided on the optical axis 18c of the second inspection camera 18. A straight tube fluorescent lamp is used as the two light sources 19c, and these light sources 19c are provided to extend in the width direction of the liquid crystal glass 1. The pair of light sources 19c are arranged on the sides of the light source 19b with the light shield 19b therebetween. Therefore, the light projected from these light sources 19c and illuminating the field of view of the second inspection camera 18 is refracted in the inspection glass 1 and transmitted in the thickness direction, thereby transmitting the second inspection camera 18
Is received.

The third optical inspection section provided at the third inspection position, for example, on the downstream side of the second inspection position, has a third optical inspection section disposed opposite to one surface, for example, the surface of the liquid crystal glass 1 like the second optical inspection section. The camera includes a second inspection camera 21 and a third illumination device 22 disposed opposite to the second inspection camera 21 with the liquid crystal glass 1 interposed therebetween and opposed to the other surface of the liquid crystal glass 1. The third optical inspection section may be provided on the upstream side of the first inspection position or the second inspection position.

The third inspection camera 21 employs a CCD camera having a one-dimensional CCD image sensor as a photoelectric conversion type viewing angle sensor in the light receiving portion 21a. The camera 21 scans the liquid crystal glass 1 along a width direction orthogonal to the moving direction.

The third illuminating device 22 includes a light shielding body 22b and two light sources 22c housed in a reflecting mirror 22a. For example, a black light shielding plate is adopted as the light shielding body 22b.
When detecting oil stains or the like as a defect, a white light-shielding plate may be used and is not limited to a plate. The light shield 22b is provided on the optical axis 21c of the third inspection camera 21. Further, straight fluorescent lamps are used as the two light sources 22c, and these light sources 22c are provided to extend in the width direction of the liquid crystal glass 1. The pair of light sources 22c are respectively arranged on the sides with the light shielding body 22b interposed therebetween. Therefore, the light projected from these light sources 22c and illuminating the field of view of the third inspection camera 21 is refracted in the inspection glass 1 and transmitted in the thickness direction to be received by the third inspection camera 21. I have.

The two light sources 22c in the third optical inspection section
The distance d2 between them is smaller than the distance d1 between the two light sources 19c in the second optical inspection unit, and thus, the third optical inspection unit has a third optical inspection unit that is smaller than the refraction angle of the refracted light in the liquid crystal glass 1 in the third optical inspection unit. The angle of refraction of the refracted light in the liquid crystal glass 1 at the inspection section is reduced.

The fourth optical inspection unit disposed at the fourth inspection position downstream of the first to third optical inspection units in the moving direction of the liquid crystal glass 1 is moved similarly to the first optical inspection unit. The liquid crystal glass 1 includes, for example, a fourth inspection camera 24 arranged to face the surface of the liquid crystal glass 1 and a fourth lighting device 25 arranged to face the other surface of the liquid crystal glass 1. In the present invention, the fourth optical inspection section may be omitted.

As the fourth inspection camera 24, a CCD camera having a one-dimensional CCD image sensor as a photoelectric conversion type viewing angle sensor in the light receiving section 24a is employed. The camera 24 scans the liquid crystal glass 1 along a width direction orthogonal to the moving direction. The fourth lighting device 25 has the same configuration as the first lighting device 16, and includes one light source 25b housed in a reflecting mirror 25a.

A straight tube fluorescent lamp is used as the light source 25b. The light source 25b is provided to extend in the width direction of the liquid crystal glass 1. The fourth illumination device 25 is provided with its light source 25b disposed on the optical axis 24c of the fourth inspection camera 24. Therefore, the fourth illumination device 25 is projected from the light source 25b to illuminate the field of view of the fourth inspection camera 24. Light is inspection glass 1
Are transmitted at right angles to the thickness direction without being refracted and received by the fourth inspection camera 24.

In the first to fourth optical inspection units which are arranged side by side in the moving direction of the liquid crystal glass 1 as described above, each of the light receiving units 15a, 18a, 21a, 24a has a one-dimensional CCD. Instead of the image sensor, a CCD camera having an area-type one-dimensional CCD image sensor can be adopted. Each of the inspection cameras 15, 18, 21, and 24 of the first to fourth optical inspection units is used at least one each so as to obtain a necessary resolution for the entire width of the liquid crystal glass 1. Also, as shown in FIG. 1, each of the inspection cameras 15, 1 of the first to fourth optical inspection units.
It is advantageous to arrange the units 8, 21, and 24 on one surface side of the liquid crystal glass 1 in terms of unitization. Similarly, each of the lighting devices 16, 19, 22, 25 is connected to the liquid crystal glass 1.
It is advantageous to arrange them collectively on the other surface side in terms of unitization, but these arrangements are not limited in the present invention.

In FIG. 1, reference numerals 28 and 29 denote ion type dust removers which may be omitted in the present invention. These dust removers 28 and 29 are provided between the fourth optical inspection unit and, for example, a third optical inspection unit on the upstream side of the fourth optical inspection unit.
8 is arranged close to the front surface of the liquid crystal glass 1, and the other dust remover 29 is arranged close to the back surface of the liquid crystal glass 1. These dust removers 28 and 29 are used in synchronization with the inspection apparatus of the present invention, and are used to remove dust attached to the front and back surfaces of the liquid crystal glass 1. Since the use of the dust removers 28 and 29 suppresses the flow of air in the clean room, the dust floating in the clean room is attracted to the liquid crystal glass 1 by the air current as in the case of blowing off dust with air. It is excellent in that there is no fear of causing it to occur.

Each of the light receiving sections 15a, 18a, 21a, 2
4a outputs, for example, a monochrome inspection signal (imaging signal). The inspection signal is supplied to the signal processing unit 12 via the gain correction circuit 11, and the signal is processed by an electronic circuit included in the processing unit 12. The gain correction circuit 11 as a normalizing means performs processing for canceling the gain fluctuation of the imaging level and optimizing the level of the detection signal.

As shown in FIG. 1, the signal processing unit 12
It includes a signal conversion circuit 31 as signal conversion means, a buffer memory 32 as memory means, a timing correction circuit 33 as timing correction means, and a matching determination circuit 34 as comparison / determination means.

The signal conversion circuit 31 includes the gain correction circuit 11
Circuit for binarizing the test signal supplied through
An A / D converter or a differentiating circuit is used. This first
Has an amplifying function for signal components (bright information and dark information) such as defects in the inspection signal. Therefore, even small defects can be surely binarized, and the reliability of the detection and determination thereof can be improved. The differential circuit that can increase the value is adopted.

The buffer memory 32 connected to the output terminal of the signal conversion circuit 33 is used to know an address of a binarized defect or the like. In the timing correction circuit 33 connected to the output terminal of the memory 32, the optical inspection sections are displaced in the moving direction of the liquid crystal glass 1 (the positional displacement distances are indicated by L1, L2, and L3 in FIG. 1). In response to this, the timing is provided so that the signal matching can be determined for the same address. The correction circuit 33 is supplied with a position signal from a distance sensor such as a rotary encoder provided in the transport means (not shown). The address in the width direction of the liquid crystal glass 1 can be obtained in each inspection signal according to the scanning in the width direction of the liquid crystal glass.

The matching determination circuit 34 connected to the output terminal of the timing correction circuit 33 performs a matching determination on the test signal whose timing has been corrected according to the matching determination criteria shown in Tables 1 and 2.

[0047]

[Table 1]

[0048]

[Table 2]

The matching criterion in Table 1 is to compare the inspection signals of the first optical inspection unit and the second optical inspection unit, or to compare the inspection signals of the first optical inspection unit and the third optical inspection unit. Therefore, the discrimination between the defect and the dust is made. The matching criteria in Table 2 are as follows:
The second and third optical inspection sections compare the test signals and determine the relationship between the voltage levels of the test signals, thereby discriminating between the defect and the dust and detecting the liquid crystal of the detected defect. The position in the thickness direction of the glass 1 is discriminated.

Further, the matching judgment circuit 34 has a defect recognition circuit for evaluating the size of the defect information detected according to the above-mentioned criterion. Only the defect information having a size larger than a predetermined value is regarded as a defect. It is determined and output.

The matching determination circuit 34 determines whether the first,
The inspection signals of the fourth optical inspection section are also compared with each other, whereby whether the dust on the front and back surfaces of the liquid crystal glass 1 is properly removed is monitored.

The transparent body inspection apparatus having the above-described configuration inspects the defect of the liquid crystal glass according to the following procedure. The liquid crystal glass 1 moved by the transport means (not shown) is imaged by the first optical inspection unit at the first inspection position by the direct transmission method. That is, when passing through the first optical inspection unit, the first
The directly transmitted light that is projected from the illumination device 16 and transmitted straight upward in the thickness direction of the liquid crystal glass 1 without being refracted by the liquid crystal glass 1 is incident on the first inspection camera 15. By scanning in the width direction, the liquid crystal glass 1 is imaged in the field of view illuminated by the first illumination device 16.

In the imaging by the first optical inspection section, the front inspection camera 2, the back flaw 3, the bubble 4, and the dust adhering to the front and back surfaces of the liquid crystal glass 1 all block the transmitted light. As shown in FIG. 2A, the first inspection signal output from the dark information 2a (corresponding to the surface flaw 2) corresponding to each of the defects 2 to 4 and dust (not shown) and the dark information 3a (corresponding to back flaw 3), dark information 4a (corresponding to bubble 4),
It contains dark information 5a (corresponding to dust).

Next, the liquid crystal glass 1 is imaged at the second inspection position in the second optical inspection section by the indirect transmission method. That is, when passing through the second optical inspection unit, the light is projected from the second lighting device 19 and refracted in the liquid crystal glass 1,
Since the refracted light transmitted through the glass 1 in the thickness direction is incident on the second inspection camera 18, the camera 18 scans in the width direction of the liquid crystal glass 1, so that the liquid crystal in the field of view illuminated by the second illumination device 19 The glass 1 is imaged.

In the imaging by the second optical inspection section, the second inspection camera 18 takes an image of the light shield 19b when no scratch is located on the optical axis 18c, so that the voltage level of the formation is low. Is output. When the flaw is located on the optical axis 18c, the refracted light is scattered by the flaw, and the flaw appears to be shining to the second inspection camera 18, and the flaw is imaged. As shown in FIG. 2, the information about the front flaw 2, the back flaw 3, and the bubble 4 is included in the second inspection signal as bright information having a voltage level higher than the local level. In FIG. 2, the light information 2b corresponds to the front flaw 2, the light information 3b corresponds to the back flaw 3, and the light information 4b corresponds to the bubble 4. Further, since the dust adhering to the front and back surfaces of the liquid crystal glass 1 blocks the refracted light, the second inspection signal output from the second inspection camera 18 outputs the dark information 5b corresponding to the dust as shown in FIG. Contains.

Next, the liquid crystal glass 1 is imaged by the indirect transmission method at the third inspection position at the third inspection position. That is, when passing through the third optical inspection unit, the light is projected from the third lighting device 22 and refracted in the liquid crystal glass 1,
Since the refracted light transmitted through the glass 1 in the thickness direction is incident on the third inspection camera 21, the camera 21 scans in the width direction of the liquid crystal glass 1 so that the liquid crystal can be viewed in the field of view illuminated by the third illumination device 21. The glass 1 is imaged.

In the imaging by the third optical inspection section, the third inspection camera 21 takes an image of the light shield 21b when no flaw is located on the optical axis 21c, so that the voltage level of the formation is low. Is output. When the flaw is located on the optical axis 21c, the flaw is scattered by the flaw and the flaw appears to the third inspection camera 21, and the flaw appears as an image. As shown in FIG. 2, the information about the front flaw 2, the back flaw 3, and the bubble 4 is included in the second inspection signal as bright information having a voltage level higher than the local level. In FIG. 2, the light information 2c corresponds to the front flaw 2, the light information 3c corresponds to the back flaw 3, and the light information 4c corresponds to the bubble 4. Further, since dust adhering to the front and back surfaces of the liquid crystal glass 1 blocks the refracted light, the third inspection signal output from the third inspection camera 21 outputs dark information 5c corresponding to the dust as shown in FIG. Contains.

Incidentally, in the second and third optical inspection sections, the refraction angles of the refracted light in the liquid crystal glass 1 are larger in the second optical inspection section due to the illumination devices 19 and 22, and the third optical inspection section is not used. Since the inspection unit is set to be smaller, the scattering method for the scratch is different. As a result, the bright information 2b on the front flaw 2 in the second optical inspection unit has a high voltage level (for example, 12 V), and the bright information 2b on the back flaw 3
Indicates that the voltage level is low (for example, 3.1 V), and the bright information 2 on the surface flaw 2 in the third optical inspection unit.
c has a low voltage level (for example, 3.7 V), and the bright information 3c about the back flaw 3 has a high voltage level (for example, 1 V).
1.5V) is detected. Further, since the position of the bubble 4 is located at the center in the width direction of the liquid crystal glass 1, as shown in FIG. 2, the bright information 4b and 4c of the bubble 4 in the second and third optical inspection sections are represented by the voltage. No difference in level (for example, 8
V) Detected.

The dust adhering to the liquid crystal glass 1 is detected as dark information (the voltage value is, for example, 8.0 V) in accordance with the image pickup by the first to third inspection units.
Note that dust on the front and back surfaces of the liquid crystal glass 1 is removed by the dust removers 28 and 29 from the third inspection position to the fourth inspection position. At the fourth inspection position, the liquid crystal glass 1 is inspected by the direct transmission method as in the inspection at the first inspection position. Thereby, as shown in FIG. 2, the dark information 2d (corresponding to the surface flaw 2) corresponding to each of the defects 2 to 4,
Dark information 3d (corresponding to back flaw 3) and dark information 4d (corresponding to bubble 43) are obtained.

The first to fourth inspection signals obtained at each inspection position as described above are supplied to the signal processing unit 12 via the gain correction circuit 11, respectively. Therefore, first, the inspection signal is binarized by a differentiation process in the signal conversion circuit 31, and then each of the light and dark information is given an address by the buffer memory 32, and then the timing correction circuit 33 makes the matching judgment circuit 34. The timing is corrected so as to conform to the above-described matching determination operation, and the corrected timing is supplied to the matching determination circuit 34.

The matching judgment circuit 34 judges the matching of the inspection signal according to the criteria shown in Table 1 or Table 2. In this determination, the first and second inspection signals obtained by the first and second inspection cameras 15 and 18 are:
Since the addresses are compared with each other, as shown in Table 1, when the first inspection signal is dark information and the second inspection signal is bright information, as shown in Table 1, the detection information is It can be determined that it is a defect. Similarly, when the first and second inspection signals of the detection information of a certain address are both dark information, it can be determined that the detection information is dust.

As described above, the defects 2 to 4 of the liquid crystal glass 1 and the dust 5 are discriminated from each other automatically by the judgment operation of the matching judgment circuit 34 for comparing the inspection signals obtained by the combination of the direct transmission method and the indirect transmission method. Can be detected.

Further, the second and third inspection cameras 18 and 21
In the determination by the matching determination circuit 34, which compares the test signals supplied from the PAT with the addresses thereof, Table 2
As described above, when the inspection signals from both optical inspection units are both bright information with respect to the detection information at a certain address, it is determined that the detection information is a defect. Similarly, for the detection information of a certain address, when the inspection signals from both optical inspection units are both dark information, it is determined that the detection information is dust.

Further, as described above, characteristic bright information having different signal levels between the front surface and the rear surface of the liquid crystal glass 1 depending on the refraction angle is compared (in other words, the magnitude of the signal level is compared). Matching determination circuit 34
As shown in Table 2, the position of the defect with respect to the liquid crystal glass 1 in the thickness direction can be determined.

As described above, an inspection signal capable of discriminating between a defect and dust is obtained by the two types of optical inspection units for inspection by the indirect transmission method, and the inspection signals are compared by the matching determination circuit 34 of the signal processing unit 12. The defects 2 to 4 of the glass 1 and the dust 5 can be automatically detected separately, and the positions of the detected defects 2 to 4 in the thickness direction with respect to the liquid crystal glass 1 can also be automatically detected.

In the first embodiment,
Since the fourth optical inspection unit is provided, the inspection signal obtained by the first optical inspection unit and the inspection signal obtained by the first optical inspection unit after the operation of the dust removers 28 and 29 provided before the fourth optical inspection unit. By comparing the inspection signal with the matching determination circuit 34 of the signal processing unit 12, the positions and states of the defects 2 to 4 are correctly recognized, and the determination is made to take necessary measures such as repolishing and disposal. be able to. In addition, when both inspection signals for the same address are dark signals by this comparison, it can be determined that the dark signals are dust, and when one of the two inspection signals is a dark signal and the other is a bright signal. , It can be determined that the dark information is a bubble (cullet).

The present invention is not limited to the first embodiment. The optical inspection unit may include, for example, only the first and second optical inspection units, or may include and implement only the second and third optical inspection units, or may include the second and third optical inspection units. The present invention can be implemented by providing only one of the optical inspection units.

[0068]

The present invention is embodied in the form described above and has the following effects. According to the method for inspecting a transparent body according to claim 1, an inspection signal obtained by a direct transmission method in which a visual field illuminated by light transmitted in a thickness direction without refracting a moving transparent body is scanned by a first inspection camera. And the inspection signal obtained by the indirect transmission method in which the field of view illuminated by the light refracting the transparent body is scanned by the second inspection camera, so that it is possible to automatically detect the defects of the transparent body by distinguishing them from dust. it can.

According to the transparent object inspection apparatus of the second aspect,
Despite being a one-system optical inspection unit that performs inspection by the indirect transmission method, an inspection signal that can be distinguished from defects and dust is obtained, and it is discriminated by circuit processing in the signal processing unit. It can be automatically detected separately.

According to the transparent object inspection apparatus of the third aspect,
Inspection signals that can be distinguished from defects and dust are obtained by two systems of optical inspection units that perform inspections by the indirect transmission method, and the signals are discriminated and compared by circuit processing in the signal processing unit. In addition to being able to distinguish and automatically detect, the position of the detected defect in the thickness direction with respect to the transparent body can also be automatically detected.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a transparent body inspection apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing signal waveforms of inspection signals obtained by respective optical inspection units of the transparent object inspection apparatus according to the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid crystal glass (transparent), 12 ... Signal processing part, 15 ... 1st inspection camera (1st optical inspection section), 16 ... 1st illumination device (1st optical inspection section), 16b ... 1st illumination device Light source, 18: second inspection camera (second optical inspection unit), 19: second illumination device (second optical inspection unit), 19b: light source of second illumination device, 19c: light shield of second illumination device, 21 ... third inspection camera (third optical inspection unit), 22 ... third illumination device (third optical inspection unit), 21b ... light source of third illumination device, 21c ... light shield of third illumination device, 35 ... matching judgment Circuit, 15c, 18c, 21c ... optical axis.

Claims (3)

[Claims] At a first inspection position, a first inspection camera arranged to face a transparent body to be moved and scans the transparent body in a direction perpendicular to the moving direction of the transparent body. The light is projected from a first illuminating device having a light source disposed on the optical axis of the first inspection camera on the side opposite to the first inspection camera and is perpendicular to the thickness direction without refracting the transparent body. A first inspection signal is obtained by receiving the transmitted light transmitted through the first inspection position, and at a second inspection position downstream or upstream from the first inspection position, the transparent object is disposed opposite to the transparent body. Second scanning in a direction perpendicular to the direction of movement
In the inspection camera, a light-shielding body disposed on the optical axis of the second inspection camera on the opposite side to the second inspection camera with the transparent body interposed therebetween and a light source disposed on the side thereof (2) receiving a refracted light projected from the illumination device and refracted through the transparent body and transmitted to obtain a second inspection signal; and then comparing the first and second inspection signals. Transparent body inspection method. 2. An inspection camera which is arranged opposite to one surface side of the transparent body to be moved and scans the transparent body in a direction perpendicular to the moving direction of the transparent body, and which is arranged opposite to the other surface side of the transparent body. An illumination device that illuminates the field of view of the inspection camera, and a signal processing unit that discriminates bright information and dark information from an inspection signal obtained by imaging with the inspection camera. A light-shielding body disposed on the optical axis, and a light source disposed off the optical axis and disposed on the side of the light-shielding body, are projected from the lighting device to refract the transparent body. A transparent body inspection apparatus, wherein the inspection camera receives the transmitted refracted light. 3. An inspection camera which is disposed on one side of the transparent body to be moved and scans the transparent body in a direction perpendicular to the moving direction of the transparent body, and which is arranged on the other side of the transparent body so as to face the same. An optical inspection unit including an illumination device that illuminates the visual field of the inspection camera is provided with two systems that are displaced in the moving direction of the transparent body, and the illumination device includes a light-shielding device arranged on an optical axis of the inspection camera. A light source disposed off the optical axis and disposed on the side of the light-shielding body, and illumination of a lighting device of one of the two optical inspection units. The angle of refraction of the refracted light in the field of view due to the illumination of the illumination device of the other optical inspection unit is smaller than the angle of refraction of the refracted light in the field of view according to When discriminating between bright and dark information from a signal Moni, transparent body inspection apparatus comprising the signal processing unit for comparing the light information comrades.