JPH0772037A - Inspection of liquid crystal display panel - Google Patents

Abstract

PURPOSE:To achieve the versatility and the lower cost while enabling inspection using no limit sample by detecting a display defect based on a difference between images of the same color on which with the maximum luminance expanded has been performed. CONSTITUTION:A backlight 4 is turned on to light a liquid crystal display panel 2 fully and all display areas are taken with a CCD camera 5 to be taken into a image processor 6. The device 6 reads a display pitch of a panel 2 from an image separated into R, G and B while expansion which maximizes the luminance in the R, G and B separately is performed at the maximum luminance within the display pitch of the panel for all R, G and B images. In other works, in a 3X3 convolution, adjacent eight display pixels are replaced necessary times for the maximum luminance. Subsequently, one image is shifted by the display pitch toward the other image the same in color to determine a difference between the two images. Thus, a display defect such as failure in lighting, abnormal lighting, missed dot and gradation difference in the display luminance is detected based on the difference.

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 panel inspection method.

[0002]

2. Description of the Related Art Conventionally, inspections for display defects (non-lighting, abnormal lighting, dot chipping, gradation difference in display brightness, etc.) of liquid crystal display panels have generally been conducted by visual inspection. Inspectors are likely to have variations in quality judgment,
It has various drawbacks such as low reliability of the judgment result.

Therefore, as an alternative inspection method, a method has been developed in which the lighting state of the liquid crystal display panel is captured by a CCD camera in an image processing apparatus. In this method, for example, Japanese Patent Application Laid-Open No. 4-44493. As disclosed in the official gazette, a display defect is detected based on a difference between luminance data captured by a CCD camera and reference luminance data written in advance in the memory portion. It is necessary to write the reference data of (3), and therefore, the limit sample composed of an ideal pixel group having no defects in all the R, G, and B pixels has been used.

[0004]

However, the critical samples are not always the same ones. For example, a high quality sample used for inspection of a liquid crystal display panel for one application and another sample for other applications. Since it is different from the low quality level used for the inspection of the liquid crystal display panel of, the predetermined limit sample is selected corresponding to the liquid crystal display panel to be inspected, and it is used for the reference data. It had to be written, and therefore there was a drawback that the change of the reference data was troublesome and the versatility was not sufficient. The present invention pays attention to such a point, and as a result of intensive studies to eliminate such a defect, it is sufficient to detect the display defect based on the difference between the images of the same color with the maximum brightness expanded. I found that.

[0005]

That is, in the inspection method for a liquid crystal display panel according to the present invention, a CCD camera captures the entire lighting state of the liquid crystal display panel and captures it in an image processing device. R, G, B that gives maximum brightness
The maximum brightness is expanded in the display pitch range of the panel for all images, and then one image is shifted toward the other image of the same color by the display pitch to obtain the difference between the two images. In addition, the display defect is detected.

[0006]

EXAMPLE An example of the present invention will be described below. In FIG. 1, a liquid crystal display panel 2 is mounted on an inspection table 1, a prober 3 is connected thereto, and a backlight 4 is turned on. , The emitted light passes through the opening 1a of the inspection table 1 and illuminates the liquid crystal display panel 2,
That is, the liquid crystal display panel 2 is in a fully lit state. In addition, the fully-lit state is captured by the CCD camera 5 located above the liquid crystal display panel 2 and captured in the image processing device 6.

The image processing device 6 includes an AD converter 7, an image memory 8, an arithmetic circuit 9, and a display circuit 10. The CCD camera 5 is a color or monochrome camera, and a monochrome camera is used. When used, an optical filter is generally placed at a suitable position between it and the liquid crystal display panel 2.

In addition, the full lighting state of the liquid crystal display panel 2 is
The image pick-up by the camera 5 and the capturing in the image processing device 6 are carried out for a part of the display section of the liquid crystal display panel 2 and for the other part, and in this manner, the entire area of the display section of the liquid crystal display panel 2 is processed. Be seen. that time,
The inspection table 1 is horizontally slid in two directions of X and Y, and is horizontally rotated about the vertical axis at a predetermined angle θ, so that C
The liquid crystal display panel 2 is positioned with respect to the visual field of the CD camera 5 one after another.

On the other hand, in the image processing device 6, R,
The display pitch of the liquid crystal display panel 2 is read from the images separated into G and B, and the R, G, and B images have the maximum luminance within the display pitch range. Luminance expansion, that is, replacement of 8 adjacent display pixels with maximum luminance in 3 × 3 convolution is performed as many times as necessary, and subsequently, one image is shifted toward the other image of the same color ( For example, R
The one image separated into R is shifted by the display pitch (to the other image separated into R), and non-lighting, abnormal lighting, dot chipping, and display brightness are based on the difference between the two images obtained thereby. Detects display defects such as adjustment. At that time, the AD converter 7 digitizes the incoming video signal, which is stored in the image memory 8 and directly accessed by the arithmetic circuit 11. The inspection result is displayed on the display circuit 10.

As described above, in the present invention, since the inspection can be performed in a form utilizing only the maximum luminance taken into the image processing device 6 through the CCD camera 5, the use of the limit sample, which is indispensable in the conventional method, is used. Therefore, it is possible to obtain an inspection method which can be generalized. Moreover, since the inspection can be performed in the all-lighted state, it is possible to omit probing the R, G, and B wirings of the liquid crystal display panel, respectively, and it is possible to reduce the cost.

In the present invention, the CCD camera 5
Regarding, regarding the black and white camera, the optical filter may be omitted, but in this case, R,
The display pitch of the liquid crystal display panel 2 is read from the display images of G and B, and then R, G, and B are calculated from the respective luminances of R, G, and B.
After reading the positions of G and B, R, G and B are subjected to mask processing of the image processing means or pattern superposition.
It is also possible to create a separated image in step S1, and then to enhance it if necessary, and then to expand the image thus separated into R, G, and B in the same manner as described above.

The inspection table 1 may be composed of a θ table and an XY table, and the CCD camera 5 may be mounted on the XY table. The loader 11 shown in FIG. 1 uses the unloader 12 in order to mount the liquid crystal display panel 2 to be inspected on the inspection table 1.
Are provided in order to remove the inspected liquid crystal display panel 2 from the inspection table 1.

[0013]

As described above, according to the present invention, with respect to the display defect inspection of the liquid crystal display panel, an inspection method which can be inspected without using a limit sample and can be generalized and cost down can be obtained. To be

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a CCD camera type liquid crystal display panel inspection device.

[Explanation of symbols]

 1 Inspection table 2 Liquid crystal display panel 4 Backlight 5 CCD camera 6 Image processing device

Claims (1)

[Claims] 1. A liquid crystal display panel is imaged with a CCD camera to capture all the lighting states and taken into an image processing apparatus, and all the R, G, and B images such that R, G, and B have maximum brightness are displayed on the panel. Detecting a display defect based on the difference between the two images obtained by expanding the maximum luminance within the display pitch range and then shifting one image toward the other image of the same color by the display pitch. A method for inspecting a liquid crystal display panel, characterized by: