JPH0894493A - Inspection equipment for liquid display board - Google Patents

Abstract

PURPOSE: To obtain an inspection equipment for liquid crystal board in which a board holding table can be made compact and the weight thereof can be reduced while facilitating the adjustment and maintenance of optical system. CONSTITUTION: The inspection equipment for liquid crystal board comprises a light source 11 for projecting an illumination light 18 obliquely from above to the upper surface of a liquid crystal display board 1, a reflector 15 having an inclining face 24 disposed on the rear side of the board 1, and an image pickup unit 9 disposed above the upper surface of the board 1 in order to receive the light 23 projected from the light source 11, transmitted through the board 1, reflected on the reflector 15 and transmitted through the board 1 again. Since the reflector 15 disposed on the rear surface of the board 1 functions equivalently to the light source 11 and the light source 11 can be disposed on the upper surface side of the light source 11, adjustment and maintenance of the inspection equipment can be facilitated and interference of a board holding table can be avoided. This structure reduces the weight of the board holding table and realizes high speed high response driving of the board 1 easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display substrate inspection apparatus which is applied to a defect inspection by a transmission method performed on a glass substrate, a substrate after a color filter has been applied, and the like.

[0002]

2. Description of the Related Art In a defect inspection of a liquid crystal display substrate by a conventional transmission method, a light source is installed below the back side of the substrate,
An imaging device is installed above the upper surface of the substrate, the substrate is irradiated with illumination light of the light source while the substrate is moved in the horizontal direction, and the transmitted light is captured by the imaging device to output an image,
The image was processed to extract defects on the substrate.

[0003]

In recent years, the production of liquid crystal displays has grown remarkably and the size of substrates has also increased. For example, in a liquid crystal display production line, a so-called 10-inch 4-piece substrate is used, which produces four liquid crystal displays of a 10-inch panel on one glass substrate. Also, the production speed is tact time of 60 for a 10-inch 4-piece board.
It is as fast as a second.

As the size of the substrate is increased and the production speed is increased as described above, it is required that the inspection device for the substrate be capable of high-speed inspection and the reliability is improved. The following points have become important. (1) The substrate holding table for driving and positioning the substrate to be inspected, which is driven at high speed, in two axial directions in a horizontal plane should be made compact and lightweight. (2) The optical system including the light source, lens, and camera should be centrally located in one place to facilitate maintenance and adjustment.

However, the conventional inspection device in which the light source is installed on the back side of the substrate has a problem that it cannot fully meet the above customer needs for the following reasons. That is, as the light source, it is necessary to use a strobe light source in order to reduce the shake of the image in the high-speed inspection, and to cover the limit of the shutter speed of the imaging device. It is necessary to add a collimator lens in order to obtain illumination light having sufficient directivity and sufficient light intensity with a strobe light source. Also, strobe light sources have a relatively short life and require periodic replacement.

Therefore, it is necessary to arrange the light source and the lens system on the back side of the substrate so as not to interfere with the operation of the substrate holding table and to hold the substrate from the fixed side. When the size of the light source and the lens system becomes large, in order to avoid the interference between the substrate holding table and the light source / lens system, it is necessary to provide the substrate holding table with a space for avoiding the interference. As a result, the substrate holding table is increased in size and weight.

Further, since the light source and the image pickup device are separately installed, adjustment of the installation angle and maintenance are inconvenient. The present invention is intended to solve the above problems,
The objective is to make the substrate holding table compact and lightweight, and to facilitate adjustment and maintenance of the optical system.

[0008]

A liquid crystal display substrate inspection apparatus according to the present invention comprises an image pickup device located above the upper surface side of a liquid crystal display substrate to be inspected, and an optical device of the image pickup device located above the substrate upper surface side. The optical axis of the light source is arranged at a constant angle with respect to the axis, and a reflection mirror having a reflecting surface located below the back surface of the substrate and inclined at a predetermined angle. The regular reflection light of the illumination light on the upper surface of the substrate does not enter the imaging device, and the illumination light transmitted through the substrate is regularly reflected by the reflection mirror, and then passes through the substrate again and enters the imaging device. However, the image pickup device is characterized by detecting a defect in the color filter provided on the substrate.

[0009]

In the above, the irradiation light emitted from the light source is
The light reaches the surface of the liquid crystal display substrate, part of which is reflected by the surface of the substrate to be specularly reflected light, and part of which is transmitted through the substrate to be light transmitted through the substrate.

Since the optical axis of the light source has a constant angle with respect to the optical axis of the image pickup device, the regular reflection light does not enter the image pickup device. The substrate-transmitted light reaches the reflection mirror and is reflected by the reflection mirror. However, since the reflection surface of the reflection mirror is inclined at a predetermined angle, the reflection light passes through the substrate again and the image pickup device. And is imaged.

Since the above-mentioned substrate is provided with a color filter formed by alternately arranging minute portions colored in red, green and blue, the light transmitted through the substrate is red and green. , And the light of the blue wavelength component are separated, but there is a certain interval between the substrate and the reflection mirror, and the light is completely integrated between them, so that the reflection light of the reflection mirror becomes white light.

The reflected light of the reflection mirror is transmitted again through the substrate to be transmitted light, which is picked up by the image pickup device.
If the part of the substrate through which this reflected light passes is normal,
The transmitted light is divided into wavelength components of three colors. When color loss occurs, it is white light, and when there is a foreign substance, the received light level is low.

Therefore, it is possible to determine whether the substrate is normal or has a white or black defect by receiving the transmitted light that has passed through the substrate again and performing image processing.

[0014]

[Embodiment] Regarding an inspection apparatus according to an embodiment of the present invention,
This will be described with reference to FIG. In FIG. 1, 1 is a substrate,
The black matrix 2, the color filter 3, and the overcoat 4 are applied. The substrate 1 is supported by an XY table (not shown) and is reciprocally driven in the directions of arrows a and b, and is also driven in the direction perpendicular to the paper surface to be positioned.

An image pickup device 9 including a lens 5, an aperture plate 6, a color CCD camera 7 and an image processing device 8 is installed above the upper surface of the substrate 1 and fixed to the stationary side. Further, the light source 11, the diaphragm 12, and the collimator lens 13 are provided at a position inclined with respect to the optical axis 10 of the image pickup device 9.
Is installed and is fixed to the stationary side. A total reflection mirror 15 is installed below the back surface of the substrate 1 and is fixed to the stationary side.

Next, the operation of the above inspection apparatus will be described. In addition, in this embodiment, as a manufacturing defect in the substrate 1,
A case will be described in which there is a black dot defect that appears to be black due to the foreign substance 16 being overcoated 4 and a white defect 17 that is caused by a part of the color filter 3 being dropped to cause color loss.

When the substrate 1 is irradiated with the illumination light 18 from the illuminating device 14, a part of the light is specularly reflected on the surface of the substrate 1 to become specular reflection light 19, whose optical axis (broken line in FIG. 1). (Denoted by the symbol) 20 is largely deviated from the optical axis 10 of the image pickup device 9 and therefore does not enter the image pickup device 9.

A part of the illumination light 18 passes through the substrate 1 to become a substrate transmitted light 21, and then is reflected by a total reflection mirror 15 to become a reflected light 22, which again passes through the substrate 1 and is transmitted. It becomes the light 23, which is imaged by the imaging device 9 and image-processed. Here, the total reflection mirror 15 has its reflection surface 24.
Is set to a predetermined angle, the direction of the transmitted light 23 coincides with the optical axis 10 of the imaging device.

Next, the principle and function of extracting a black spot defect and a white spot defect by using the inspection device provided with the above optical system will be described below. Generally, color filter 3
Are colored R (red), G (green), and B (blue) are alternately arranged. The width of one color filter is about 0.1 mm. The thickness of the glass plate 25 is about 0.7 to 1.1 mm. Therefore, the substrate transmitted light 21 contains the wavelength components of the R, G, and B lights.

Further, if the distance between the substrate 1 and the total reflection mirror 15 is set to several mm or more, the reflected light 22 is a combination of R, G and B described above. Therefore, the white defect 17
The transmitted light 23 that has passed through contains the R, G, and B wavelength components. However, the transmitted light 23 transmitted through the color filter 3 in the normal portion has only one wavelength component of R, G, or B. Therefore, the white spot defect 17 can be extracted by applying the color image processing technique in the imaging device 9.

As for the black dot defect, since the transmitted light 23 is blocked by the foreign matter 16, this portion is a region having a low received light level on the image pickup surface (not shown) of the image pickup device 9, and therefore 2 It can be extracted by an image processing technique such as binarization.

[0022]

The liquid crystal display substrate inspection apparatus according to the present invention comprises a light source for irradiating the upper surface of the liquid crystal display substrate with irradiation light obliquely from above, a reflection mirror provided on the back surface side of the substrate and having an inclined reflection surface, and The reflection mirror provided on the back surface of the substrate is provided as a light source by providing an image pickup device which is provided above the upper surface of the substrate and which receives light emitted from the light source, transmitted through the substrate, reflected by the reflection mirror, and transmitted through the substrate again. Since the light source can be arranged on the upper surface side of the substrate, the adjustment and maintenance of the device can be facilitated and the interference of the substrate holding table can be avoided, and the weight of the substrate holding table can be reduced. This makes it possible to drive the board at high speed and with high response, and shorten the inspection time.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an inspection device according to an embodiment of the present invention.

[Explanation of symbols]

 1 Liquid Crystal Display Substrate 3 Color Filter 5 Lens 7 Color CCD Camera 8 Image Processing Device 9 Imaging Device 11 Light Source 13 Collimating Lens 14 Illumination Device 15 Total Reflection Mirror 18 Illumination Light 19 Specular Reflection Light 21 Transmitted Light 22 Reflected Light 23 Transmitted Light 25 Glass Board

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiko Ikeshita 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City Mitsubishi Heavy Industries Ltd. Hiroshima Works

Claims (1)

[Claims] 1. An image pickup device located above an upper surface side of a liquid crystal display substrate to be inspected, wherein the optical axis is located above the upper surface side of the substrate, and its optical axis has a constant angle with respect to the optical axis of the image pickup device. A disposed light source, and a reflection mirror located below the back side of the substrate and having a reflection surface inclined at a predetermined angle,
The regular reflection light of the illumination light from the light source on the upper surface of the substrate does not enter the image pickup device, and the substrate transmission light of the illumination light is regularly reflected by the reflection mirror, and then passes through the substrate again and An inspection device for a liquid crystal display substrate, which is incident on an image pickup device, and the image pickup device detects a defect of a color filter provided on the substrate.