JP2001188048A - Inspection method for pinhole - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method, for a pinhole, in which the pinhole can be inspected safely inside an ordinary illuminated room, in which a judgment reference conforming to an actual environment or an actual condition in its inspection can be set and in which the pinhole can be detected not only simply but also with high accuracy and at high speed according to a hole diameter zone. SOLUTION: In the method, the number of pinholes and their hole diameters are inspected by image-processing image data which is obtained in such a way that a beam of light which is transmitted through the pinhole 3 existing in a light-shielding thin film out of beams of light with which one face of a light-shielding thin film substrate 2 is irradiated from a light source 1 is photographed by an image receiving sensor 4 in a position facing the light source 1. In an optical device which is provided at an apparatus in advance, a relationship between the measured value of the hole diameter of the pinhole and a pixel which corresponds to the pinhole in image data acquired by the image receiving sensor is stored as a correlation approximate equation. When the pinhole is inspected, the number of pixels corresponding to the pinhole is substituted into the correlation approximate equation. The hole diameter of the pinhole is calculated. The number of pinholes is counted according to the hole diameter zone of the pinhole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pinhole inspection method. More specifically, a pin for inspecting a pinhole generated in a light-shielding thin film used as a black matrix of a color filter substrate mounted on a flat panel display (FPD) based on criteria for determining the diameter and number of pinholes. It relates to a hole inspection method.

[0002]

2. Description of the Related Art In recent years, an FPD, particularly a liquid crystal display (LCD), which has been widely used as a display panel of various information devices, has, for example, a black matrix (60) functioning as a light shielding film as shown in FIG. It is composed of a color filter substrate composed of pixel regions (61) of three primary colors of light and a TFT substrate opposed to the color filter substrate (62) with a liquid crystal layer interposed therebetween.

[0003] The black matrix (60) is made of a metal or alloy as a target, and is formed on a transparent glass substrate by a known sputtering method.
A light-shielding thin film having a thickness of about 1 μm and an optical density of 3.5 or more is formed, and is manufactured by patterning by photolithography. This black matrix (60)
The function of (1) is to prevent erosion from each pixel area (61), increase the contrast of the display screen, sharpen the image,
The purpose of the present invention is to prevent the transmission of external light to the pixel switch element on the FT substrate side, thereby preventing a switching malfunction. Therefore, a pinhole in which a part of the light-shielding thin film is peeled off in a substantially circular or elliptical shape due to the effect of foreign matter or film stress attached during film formation or insufficient adhesion to a transparent substrate. Occurs. When the diameter of the pinhole is large to some extent, or when the number is large, the etching solution is immersed in the pinhole portion during buttering, and a part of the pattern is largely peeled off, or a desired pattern shape is obtained. There was no problem. Further, even when assembled as a liquid crystal display in such a state, external light passes through the pinhole portion, and thus does not function sufficiently as the black matrix described above.

As a conventional pinhole inspection method, for example, there is a visual inspection method using a high-luminance light source in a dark room. In this inspection method, the judgment is made based on whether the diameter of the pinhole (the long diameter in the case of an ellipse) and the number thereof are within an allowable limit (judgment criterion). Variations have occurred, and it has been difficult to set a quantitative allowable limit. further,
Since inspection work is performed in a dark room, sufficient consideration must be given to safety when handling brittle transparent glass substrates, etc. In addition, this method depends on the level of proficiency, as the number of inspectable sheets per hour depends on the skill level. It was a task, and automation of the task was required.

[0005] To meet the demand for automated inspection,
The amount of transmitted light when illuminating light is applied to the inspection object, or the amount of reflected light or scattered light when reflected is measured by a sensor,
A method for detecting the presence or absence of a pinhole defect and an inspection device therefor have been developed.However, since the optical system and the substrate transport system in the device are complicated in order to suppress disturbances such as vibration and changes in illumination, the inspection is performed. Was causing the cost to increase.

As a more advanced inspection method of these methods, a method of inspecting a pinhole photographed image by an image sensor such as a CCD camera by image processing has been proposed. There is a problem that the risk of erroneous determination is high because the calculation is made by associating the number of pixels with a linear expression. Furthermore, when the judgment criteria are complicated and strict, such as when the allowable number of pinholes is specified for each pinhole diameter band, the false detection rate is high even when compared with human visual inspection, and the inspection speed is high. Is also a problem.

[0007] The invention of this application has been made in view of the above-mentioned circumstances, and can be safely inspected in a room with normal lighting, and a judgment criterion corresponding to an actual inspection environment and conditions is set. It is another object of the present invention to provide a simple pinhole inspection method that can detect pinholes with high accuracy and high speed in each hole diameter band, in addition to simple pinhole detection.

[0008]

Means for Solving the Problems The present invention solves the above-mentioned problems by providing a pinhole existing on a light-shielding thin film among light rays emitted from a light source to one side of a light-shielding thin film substrate. A method for inspecting the number and diameter of pinholes by image processing image data obtained by capturing a transmitted light beam by an image receiving sensor at a position facing a light source. The relationship between the measured value of the hole diameter of the hole and the pixel corresponding to the pinhole in the image data acquired by the image receiving sensor is stored as a correlation approximation formula, and the number of pixels corresponding to the pinhole is used in this correlation approximation formula during inspection. The pinhole hole diameter is calculated by substituting, and the number of pinholes is counted for each pinhole diameter band. Claim 1) provides.

Further, in the pinhole inspection method of the invention of the present application, the above-mentioned correlation approximation formula is represented by y = αxβ−γ (α, β, γ are coefficients obtained by correlation approximation, x is a pixel area of a pinhole portion, y is the diameter of a pinhole) (Claim 2). The image data acquired by the image receiving sensor is converted into a value of a pixel corresponding to a portion of the light beam transmitted through the light-shielding thin film. Is binarized by floating threshold processing so that the values of the pixels become “1” and the values of the other pixels become “0”, and the sum of the values is calculated for an area where the pixel values are continuous with “1”. The pixel area corresponds to the hole (claim 3).

Still further, the invention of this application is directed to a light shielding thin film substrate / image receiving sensor which is movable, and a mechanism for transporting the light shielding thin film substrate / image receiving sensor at a constant speed of 10 m / min or more at a constant speed. Using a belt transport mechanism or an air transport mechanism capable of transporting the image receiving sensor (Claim 4), the light irradiation angle from the light source to the light-shielding thin film substrate, and the photographing angle of the image receiving sensor facing the light source to the light-shielding thin film substrate Are the same angle and 45 ° to 135 ° (Claim 5), and a laser beam is incident on the beam expander, and further, is radiated and diffused by a polygon mirror with a scan lens, and is shielded by a reflection mirror. The thin film substrate is irradiated linearly (claim 6).

According to the invention of this application, a computer-readable recording medium which records a program for executing the above-described pinhole inspection method (claim 7), and a computer-readable recording medium for executing the pinhole inspection method are provided. A pinhole inspection device having a mechanism is provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The invention of this application has the features as described above, and embodiments thereof will be described below.

FIG. 1 is a schematic diagram showing a configuration example of a pinhole inspection apparatus for realizing the pinhole inspection method of the present invention. In the pinhole inspection method according to the invention of this application, for example, as shown in FIG. 1, a light source (1) irradiates a light-shielding thin film substrate (2) with a light beam, and if a light-shielding thin film has a pinhole (3). Is present, the state of transmission of light rays is photographed by the CCD (4), which is an image receiving sensor installed at a position facing the light source. The photographed image is subjected to image processing as digital data by a processing device (5) connected to a CCD (4) to calculate the number and diameter of pinholes and output the result to an output device (6). You.

In the pinhole inspection method of the invention of this application, before the inspection is performed, the measured value of the hole diameter of the pinhole in the optical arrangement of the apparatus and the CCD which is the image receiving sensor are used.
The relationship between the image data obtained by the camera and the number of pixels corresponding to the pinhole is obtained as a correlation approximation formula.
The correlation approximation formula is stored in a memory inside the processing device (5),
At the time of inspection, the number of pixels in the portion corresponding to the pinhole is counted from the captured image data, and then the actual number of pinhole holes is calculated by substituting the number of pixels into a correlation approximation formula. It is also possible to count the number of pinholes for each hole diameter band in the object.

More specifically, the above-mentioned correlation approximation formula is as follows: y = αxβ−γ (α, β, γ are coefficients obtained by correlation approximation, x is a pixel area of a pinhole portion, and y is a hole diameter of the pinhole. Is shown).

In the image data obtained by the CCD as an image receiving sensor, the value of the pixel corresponding to the portion where the light beam has passed through the light-shielding thin film, ie, the pinhole, is “1”, and the values of the other pixels are “1”. Is binarized by threshold processing so that is set to “0”. The threshold processing is preferably a floating threshold processing in which the threshold value of each pixel is different, and the value is appropriately set according to the optical system of the apparatus. With respect to the image data that has been subjected to the binarization processing, the sum of the values is calculated for a region where the pixel value is continuously “1”, and this value is calculated as the total area of the pixel corresponding to the pinhole. Will be treated. The total area of the pixels corresponding to this pinhole is substituted into the above-described approximate correlation equation, and the actual pinhole hole diameter is calculated.

In the pinhole inspection method according to the invention of the present application, either the light-shielding thin film substrate or the CCD which is an image receiving sensor is movable, and a mechanism for transporting them is a constant 10 m / min or more. A belt transport mechanism or an air transport mechanism capable of transporting the light-shielding thin film substrate at a high speed is used. These mechanisms are provided with a mechanism that is less susceptible to noise and vibration irrespective of belt conveyance or air conveyance.

As shown in FIG. 2, the light irradiation angle α from the light source (21) to the light-shielding thin film substrate (22) and the light-shielding thin film substrate (22) of the CCD (23) facing the light source (21). Is preferably the same, and the range of α and β is preferably limited to 45 ° to 135 °.

In the pinhole inspection method according to the present invention, for example, a linear light source is used as the light source.
As a specific example, a large number of illumination lights from a halogen lamp are bundled in a straight line to take in from one end face of an optical fiber whose end faces are aligned, propagate through the fiber, and emit the illumination light from the other end face via a diffusion filter or the like. It is structured to emit light. Of course, the light source may be a planar light source such as a backlight, or a laser light source (3) as shown in FIG.
The laser beam emitted from 1) enters a beam expander (32), and is further scanned with a scan lens (3).
The light is diffused by a polygon mirror (34) provided with 3), and the light-shielding thin film substrate (3) is reflected by a reflection mirror (35).
6) may be irradiated.

In the pinhole inspection method according to the present invention, not only one CCD but also a plurality of CCDs can be used. The CCD may be either a line CCD or an area CCD.

Further, in the invention of this application, the pinhole inspection method described above is stored as a program on a computer-readable recording medium,
Is achieved. By the device that can execute this program,
Detects pinholes in real time in synchronization with the scanning cycle of the line CCD camera, counts the number of defects while classifying the pinholes according to the number of pixels detected, and counts the number of defects based on the preset criterion value. It is also possible to determine the final quality of a light-shielding thin film substrate.

It goes without saying that the invention of this application is not limited by the above-described embodiments. The invention of this application has the above-mentioned features, and will be described in more detail with reference to examples below.

[0023]

Example 1 First, a light-shielding thin film made of an iron group metal was formed on a transparent substrate made of a rectangular glass plate. At this time, the film thickness was 0.11.
At μm, the optical density was 4.4. Of the many light-shielding thin film substrates, those having a pinhole having a hole diameter of φ20 μm as measured by a microscope were inspected using the pinhole inspection device illustrated in FIG. As the image receiving device, four line CCD cameras having 5,000 pixels were used.

FIG. 4 shows a signal obtained by A / D converting the irradiation light from the linear light source transmitted through the pinhole by one line CCD camera among the light receiving devices by the processing device. FIG. 4 shows that the difference (S / N ratio) between the light detection signal and the noise between the portion corresponding to the pinhole and the other portion is very large, so that the presence of the pinhole can be clearly detected.

The broken line in FIG. 4 is a threshold value used in the above-described threshold value processing, and a different value is set for each pixel. In a region where the threshold value is high at the pixel on the end of the horizontal axis in FIG. 4, no signal is used because the field of view overlaps with an adjacent camera.

FIG. 5 shows the result of examining the hole diameter of the pinhole on the light-shielding thin film substrate and the number of pixels corresponding to the pinhole. Actual pore size (unit: [mu] m) pinholes from this that the relation of the pixel area, the correlation approximate expression is represented by y ≒ 7.4x ^0.5 -21, pore diameter and the pixel area of the pinhole is extremely high correlation (phase The relationship number was found to be 0.99).

Based on the correlation approximation formula, the inspection conditions (such as a criterion value) for the hole diameter and the number of the pinholes are input to the processing device and the inspection is performed. Large (φ50μm or more), medium (φ30μm or more and less than φ50μm), small (φ3
(Less than 0 μm), it is possible to perform high-precision identification determination easily corresponding to various criteria such as the hole diameter of the pinhole and the allowable number.

In this embodiment, the speed at which pinholes can be inspected with high accuracy and stability without oversight is, for example, the size of the substrate to be inspected is 550 × 65.
At 0 mm, it was about 3 seconds / sheet. Inspection speed of visual inspection and commonly known inspection methods and devices is 40
By comparison, the invention of this application,
It can be said that extremely high-speed inspection has become possible. Example 2 When the irradiation angle of the linear light source and the light receiving angle of the line CCD camera facing the linear light source were changed,
Although the light intensity distribution of the pinhole differs depending on the angle, if it is within a certain range, the relationship between the actual size of the pinhole and the cumulative number of detection pixels is as follows. Direction), there was a strong correlation as well.

From this, the irradiation angle of the linear light source,
Even if the light receiving angle of the line CCD camera facing the line light source is changed, the high detection capability of the pinhole can be maintained, but the irradiation angle and the light receiving angle need to be equal, and 45 ° to 135 °. It is desirable to be limited.

It has also been found that by increasing or decreasing the number of line CCD cameras as image receiving devices, it is possible to easily cope with a change in the size of the substrate to be inspected.

[0031]

As described in detail above, according to the invention of this application, it is possible to inspect safely in a room with normal lighting,
In addition, a pinhole inspection method that can set a criterion in accordance with an actual inspection environment and conditions is realized. Further, there is provided a pinhole inspection method capable of counting pinholes with high accuracy and high speed for each hole diameter band as well as simply detecting pinholes. Since the configurations of the optical system and the transport system are simple, it is considered that the inspection apparatus can be realized at low cost, and practical use for quality control of liquid crystal production is expected.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an embodiment of a pinhole inspection method according to the present invention.

FIG. 2 is a schematic view showing an optical arrangement of a light source, a light-shielding thin film substrate, and a CCD in the pinhole inspection method according to the invention of this application.

FIG. 3 is a schematic diagram showing a configuration of a linear light source using a laser in the pinhole inspection method of the invention of this application.

FIG. 4 shows a line CC according to an embodiment of the present invention.
5 is a graph showing a signal intensity of a light-shielding thin film substrate having a pinhole, which is photographed by a D camera.

FIG. 5 is a diagram showing a correlation between an actually measured value of a pinhole hole diameter and the number of pixels detected by a line CCD camera in an embodiment of the present invention.

FIG. 6 is a schematic view illustrating the configuration of a color filter substrate.

[Explanation of symbols]

 Reference Signs List 1 light source 2 light-shielding thin film substrate 3 pinhole 4 image receiving sensor: CCD 5 processing device 6 output device 21 light source 22 light-shielding thin film substrate 23 image receiving sensor: CCD 24 pinhole 31 laser light source 32 beam expander 33 scan lens 34 polygon mirror 35 reflection Mirror 36 Light-shielding thin film substrate 60 Black matrix 61 Pixel area 62 Color filter substrate

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[Procedure amendment]

[Submission date] February 28, 2001 (2001.2.2
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

(Equation 1) 2. The pin according to claim 1, wherein α, β, and γ are coefficients obtained by correlation approximation, x is a pixel area of a pinhole portion, and y is a hole diameter of the pinhole. Hall inspection method.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

In the pinhole inspection method according to the invention of the present application, the correlation approximation formula is

(Equation 2) (Α, β, and γ are coefficients obtained by correlation approximation, x is a pixel area of a pinhole portion, and y is a hole diameter of the pinhole). The image data obtained by the above is binarized by floating value processing so that the value of the pixel corresponding to the portion of the light beam transmitted through the light-shielding thin film is “1” and the values of the other pixels are “0”, The sum of the values is calculated for a region where the pixel value is “1” and is continuous, and this value is used as the pixel area corresponding to the pinhole (claim 3).

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

More specifically, the above correlation approximation formula is

(Equation 3) (Α, β, γ are coefficients obtained by correlation approximation, x is a pixel area of a pinhole portion, and y is a pinhole hole diameter).

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G051 AA90 AB04 BB01 BB11 BC06 CA03 CA04 CA06 CB02 EA11 EC07

Claims (8)

[Claims] 1. A light beam transmitted through a pinhole existing on a light-shielding thin film out of light beams emitted from a light source to one surface of a light-shielding thin film substrate, and is obtained by photographing the light receiving sensor at a position facing the light source. A method of inspecting the number and diameter of pinholes by performing image processing on image data that is obtained,
The relationship between the measured value of the hole diameter of the pinhole and the pixel corresponding to the pinhole in the image data obtained by the image receiving sensor is stored in advance in the optical arrangement of the apparatus as a correlation approximation formula. A pinhole inspection method, wherein a pinhole hole diameter is calculated by substituting the number of pixels corresponding to the pinhole, and the number of pinholes is counted for each pinhole diameter band. 2. A correlation approximation formula is a relational expression of y = αxβ−γ (α, β, γ are coefficients obtained by correlation approximation, x is a pixel area of a pinhole portion, and y is a pinhole hole diameter). The pinhole inspection method according to claim 1, wherein the inspection method is represented by: 3. The image data acquired by the image receiving sensor is floated such that the value of the pixel corresponding to the portion where the light beam has passed through the light-shielding thin film is “1”, and the values of the other pixels are “0”. 2. A binarization process by a threshold value process, a sum of values is calculated for a region where the pixel value is "1" and continuous, and this value is used as a pixel area corresponding to a pinhole.
Or the pinhole inspection method described in 2. 4. The light-shielding thin-film substrate / image-receiving sensor is movable, and as a mechanism for transporting the light-shielding thin-film substrate / image-receiving sensor, the light-shielding thin-film substrate / image-receiving sensor can be transported at a constant speed of 10 m or more per minute. 4. The pinhole inspection method according to claim 1, wherein a belt transport mechanism or an air transport mechanism is used. 5. The light irradiation angle from the light source to the light-shielding thin film substrate and the photographing angle of the image receiving sensor facing the light source with respect to the light-shielding thin film substrate are the same angle, and 45 ° to 13 °.
The pinhole inspection method according to claim 1, wherein the angle is 5 °. 6. A laser beam is made incident on a beam expander, further radiated and diffused by a polygon mirror having a scan lens, and is radiated linearly to a light-shielding thin film substrate by a reflection mirror. The pinhole inspection method according to any one of the above. 7. A computer-readable recording medium on which a program for executing the pinhole inspection method according to claim 1 is recorded. 8. A pinhole inspection apparatus having a mechanism for executing the pinhole inspection method according to claim 1.