JPH08114777A - Display panel inspection method and inspection apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] In the display panel inspection, it is possible to automatically inspect whether or not each pixel has a display defect. [Structure] A multi-valued image displayed in a predetermined pattern in which only predetermined pixels are turned on is captured by an image pickup means, and first
The multi-valued image storage means is stored. Next, the multivalued image displayed in the reverse pattern in which only the pixels other than the predetermined pixels are turned on is captured by the image pickup means and stored in the second multivalued image storage means. Subsequently, the brightness of the multi-valued image of each pixel of the predetermined pattern stored in each of the first and second multi-valued image storage means and the brightness of the multi-valued image of each pixel of the reverse pattern are subtracted by the computing means. From the subtracted value of the brightness of the pixel, each pixel is binarized based on a predetermined threshold value by the comparison means. Then, 2 of each binarized pixel
The value image is stored in the binary image storage means, and a predetermined inspection result is displayed on the inspection result display device based on the stored binary image of each pixel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of inspecting each pixel in a display panel such as an LCD and an inspection apparatus used for the inspection.

[0002]

2. Description of the Related Art For example, an LCD (Liquid Cry) is used.
In a display panel such as a stall display (liquid crystal display), when inspecting the display state of each pixel,
Conventionally, each pixel of the display panel is set to a fully lit display state by a display lighting device, and an operator visually checks the presence or absence of a display defect at this time.

[0003]

However, in the past, since the multi-valued image was visually observed, the labor cost was high and the cost was high.

An object of the present invention is to make it possible to automatically inspect a display panel for the presence or absence of a display defect in each pixel.

[0005]

In order to solve the above problems, the invention according to claim 1 is a method for inspecting a pixel region of a display panel, wherein a predetermined pixel of the display panel is turned on. A multi-valued image is displayed in a pattern, and the displayed multi-valued image of the predetermined pattern is captured by the image pickup means and stored in the first multi-valued image storage means, and then the predetermined value of the display panel is set. A multi-valued image is displayed in a reverse pattern in which only pixels other than the pixels are turned on, and the displayed multi-valued image of the reverse pattern is captured by the image pickup means and stored in the second multi-valued image storage means. Then, the brightness of the multi-valued image of each pixel of the predetermined pattern stored in the first multi-valued image storage means and each pixel of the reverse pattern stored in the second multi-valued image storage means. And the brightness of the multi-valued image of After the subtraction processing by the calculation means, each pixel is binarized based on a predetermined threshold value by the comparison means from the subtracted value of the luminance of the subtracted pixel, and the inspection is performed. There is.

Further, the invention according to claim 2 is based on claim 1.
In the display panel inspection method described above, the binary image of each pixel binarized by the comparison unit is stored in a binary image storage unit, and each pixel captured in the binary image storage unit is stored. The binary image of 1 is displayed on the inspection result display device.

The predetermined pattern is, for example, a state in which every other pixel is lit in the vertical and horizontal directions.

According to a fourth aspect of the present invention, there is provided an apparatus for inspecting a pixel area of a display panel, which comprises an image pickup means for taking in a multi-valued image displayed by turning on the pixels of the display panel, and the image pickup means. First multi-valued image storage means and second multi-valued image storage means for storing the captured multi-valued image, and brightness of the multi-valued image of each pixel stored in the first multi-valued image storage means And calculation means for subtracting the brightness of the multi-valued image of each pixel stored in the second multi-valued image storage means, and a predetermined value from the subtraction value of the brightness of each pixel subtracted by this calculation means. The present invention is characterized in that it comprises a comparing means for binarizing each pixel based on a threshold value, and a judging means for judging whether the display panel is a non-defective product or a defective product based on a result of comparison by the comparing means. I am trying.

Further, the invention according to claim 5 is the same as claim 4
In the display panel inspection apparatus described above, a binary image storage unit that stores a binary image of each pixel binarized by the comparison unit, and a binary value of each pixel captured in the binary image storage unit. An inspection result display device that displays a predetermined inspection result based on an image is further provided.

[0010]

According to the first aspect of the invention, the multivalued image displayed in the predetermined pattern in which only the predetermined pixels of the display panel are turned on is captured by the image pickup means and stored in the first multivalued image storage means. Then, the multivalued image displayed in the reverse pattern in which only the pixels other than the predetermined pixels are turned on is captured by the image pickup means and stored in the second multivalued image storage means, and then the first and The subtraction value of the brightness of each pixel obtained by subtracting the brightness of the multi-valued image of each pixel of the predetermined pattern and the brightness of the multi-valued image of each pixel of the reverse pattern stored in each second multi-valued image storage means by the calculation means. Therefore, since the comparison means performs the binarization processing of each pixel based on a predetermined threshold value and inspects it, the presence or absence of display defect of each pixel can be automatically inspected, that is, the multivalued image Each pixel is binarized for stable inspection. It is done in.

Further, according to the present invention, the binary image of each pixel binarized by the comparison means and stored in the binary image storage means is displayed on the inspection result display device. The inspection result can be confirmed by displaying the binary image as it is.

In the vertical and horizontal directions, by setting a predetermined pattern in which each pixel is lit every other pixel, a subtraction process with an opposite pattern opposite to this is performed,
Accurate inspection of individual pixels is possible.

According to the invention described in claim 4, the multivalued image displayed by turning on the pixels of the display panel is photographed by the image pickup means, and the photographed multivalued image is divided into the first and second images. The brightness of the multi-valued image of each pixel that has been taken in is respectively subtracted by the arithmetic means and subtracted from the brightness of each pixel by the comparison means to obtain a predetermined threshold value. Since each pixel is binarized and the inspection device determines whether the display panel is a non-defective product or a defective product from the comparison result, the inspection of each pixel can be automatically performed. By the binarization process, stable inspection of the display panel can be automatically performed.

Further, according to the invention of claim 5, the binary image of each pixel binarized by the comparing means is stored in the binary image storing means, and the binary image of the stored pixel is stored.
Since the predetermined inspection result is displayed by the inspection result display device based on the value image, each pixel of the multi-valued image can be binarized to perform stable inspection automatically.

[0015]

Embodiments of the display panel inspection method and inspection apparatus according to the present invention will be described below with reference to FIGS. First, FIG. 1 shows an example of a display panel to be inspected to which the present invention is applied. In the embodiment, a display inspection of a simple matrix LCD, which is one of the display panels, is performed.
FIG. 1A illustrates a display state of a predetermined pattern in which each pixel is lit up every other pixel in the vertical and horizontal directions, and FIG. 1B shows a display pattern opposite to that of FIG. 1A. The state is illustrated.

That is, in the embodiment, the OF is dark in the ON state in which the pixel is turned on by the voltage application, and the OF is not applied.
In a so-called normally white transmissive simple matrix LCD that is bright in the F state, as shown in FIG. 1A, a display state by a multi-valued image in which each pixel is turned on (lit) every other pixel in the vertical and horizontal directions is shown. Contrary to this, as a pattern A, as shown in FIG. 1B, a display state of a multivalued image in which each pixel of the reverse pattern is turned on (lighted) is a pattern B. Here, the display state in which each pixel is turned on every other pixel is as described below.
This is so that a short circuit between adjacent lines can be recognized. In the embodiment, a transmissive simple matrix LCD is used, but the present invention can be applied to a reflective simple matrix LCD.

Further, in the present invention, the pattern A of the display state by the multi-valued image of each pixel shown in FIG. 1A is, as will be described later, the multi-valued image memory 1 as the first multi-valued image storage means. The pattern B of the display state by the multivalued image of each pixel in the reverse pattern shown in FIG. 1B is stored in the multivalued image storage means as the second multivalued image storage means. It is captured in the memory 2 and stored. Further, in the present invention, the brightness of the multi-valued image of each pixel of the pattern A and the brightness of the multi-valued image of each pixel of the pattern B are subtracted by the arithmetic means, and the subtracted value of the brightness of each pixel is used. The comparison means obtains a binary image by binarizing each pixel based on a predetermined threshold value. In that case, if there is no defective pixel in the binary image, as shown in FIG. The pixel is in a High state. High for this pixel
The (bright) state is flagged as "1", and the pixel Low
The (dark) state is set to the flag “0”. In this state, all the peripheral areas of the LCD except the pixel formation area (display area) are in a low (dark) state. The above binary image is captured and stored in the binary image memory 3 as a binary image storage means, as described later.

Next, FIG. 3 showing an example of the configuration of the display panel inspection apparatus according to the present invention will be described. As shown,
The LCD 1 to be inspected has a signal generator (driving device) 2
Are connected, and the multivalued image of the pattern A and the multivalued image of the pattern B of each pixel of the LCD 1 are captured by a camera 3 as an image pickup unit. This camera 3 is, for example, a CCD (Charg).
e Coupled Device: solid-state image sensor) camera and the like. The camera 3 and the signal generator 2 are connected to the inspection device 10 according to the present invention.

The inspection apparatus 10 includes an A / D converter 4 for A / D converting an image signal from the camera 3, and a multi-valued pixel of each pattern A after being converted by the A / D converter 4. A first multi-valued image storage means (multi-valued image memory 1) 5 for capturing and storing an image and a multi-valued image of each pixel of the pattern B after being converted by the A / D converter 4 are also captured. A second multi-valued image storage means (multi-valued image memory 2) 6 for storing, a multi-valued image of each pixel of the pattern A and a multi-valued image of each pixel of the pattern B are obtained as described below. A binary image storage means (binary image memory 3) 7 for fetching and storing a binary image to be stored, and a CPU (C for controlling predetermined arithmetic processing and comparison processing as described later).
The central processing unit 8 is further provided, and the inspection result display device 11 by a monitor TV is further provided. That is, the CPU 8
Arithmetic means for subtracting the brightness of the multi-valued image of each pixel of the pattern A and the brightness of the multi-valued image of each pixel of the pattern B, and a predetermined value described later from the subtracted value of the brightness of each pixel. A computing unit including a comparing unit for binarizing the threshold value to obtain a binary image, storing the display drive signals of the pattern A and the pattern B, and It has a memory 9 for storing a threshold value.

Next, the procedure and control example of the display panel inspection method according to the present invention will be described with reference to the flow chart shown in FIG. First, the CPU 8 displays the pattern A by operating the signal generator 2 based on the display drive signal of the pattern A stored in the memory 9 to drive each pixel of the LCD 1 (step S).
1). The multi-valued image of each pixel according to the pattern A displayed on the LCD 1 is captured by the camera 3, and the image signal from the camera 3 is A / D converted by the A / D converter 4.
After conversion, it is stored in the multi-valued image memory 1 (step S2).

From the multivalued image of each pixel according to the pattern A stored in the multivalued image memory 1, the O
Half of the brightness difference between the N pixel and the OFF pixel is stored in the memory 9 of the CPU 8 as a binarization level (step S
3). Here, the binarization level is a threshold of brightness, and for example, when the gradation of the brightness of the pixel is 0 to 256,
The threshold value is about 20 to 30. Next, the CPU 8
The pattern B is displayed by operating the signal generator 2 based on the display drive signal of the pattern B stored in the memory 9 to drive each pixel of the LCD 1 (step S4).

The pattern B displayed on the LCD 1
The multi-valued image of each pixel is captured by the camera 3, the image signal from the camera 3 is A / D converted by the A / D converter 4, and then stored in the multi-valued image memory 2 (step S5). Subsequently, in the arithmetic unit of the CPU 8, the brightness of the multi-valued image of each pixel according to the pattern A and the brightness of the multi-valued image of each pixel according to the pattern B, which are respectively captured between the multi-valued image memories 1 and 2, are calculated. The subtracting process is performed by the calculating means, and the subtracting value of the brightness of each pixel is binarized by the comparing means based on the threshold value (step S6).

Each multi-valued image memory 1 in step S6
Regarding the binarization processing of the subtraction value after subtracting the brightness of each pixel between two, as shown in detail in FIG. 5, the absolute value of the brightness subtraction value of the pixel between the multi-valued image memories 1 and 2 is binary. It is determined whether or not it is higher than the conversion level (the threshold value; 20 to 30) (step S61).
The flag is set to "1" (High) because the switching has been performed (step S62). Also, if it becomes large, it will be normally ON /
Flag "0" (Lo
w) (step S63). After that, all return to the main routine, and the luminance subtraction values in all the pixels are determined. Through the above step S6, the binary image with the flags "1" and "0" is loaded into the binary image memory 3 (step S7).

Next, it is determined whether or not there is a pixel below the binarization level in the binary image taken into the binary image memory 3 (step S8), and if there is, below the binarization level. The position of the pixel is searched (step S9). Thereby, the defective pixel can be identified. Then, the result of the search in step S9 is used as the inspection result display device 11
(Step S10). In addition, the step S
In 8, if there is no pixel below the binarization level,
Control goes to step S10.

Next, FIG. 6 exemplifies a case where a pixel defect occurs. In this example, the third column and the fourth column in the pixel array are shown.
This is the case where there is a short circuit with the column. At this time, as shown in FIG. 6A, in the pattern A, the pixels in the third and fourth columns are continuously turned on, and
As shown in (b), in the pattern B, the pixels in the third and fourth columns are continuously turned on, and in the binary image,
As shown in FIG. 7, a portion corresponding to each pixel in the third and fourth columns has a flag “0”, which indicates that each pixel in the third and fourth columns is defective in display. As described above, according to the inspection of the display panel of the present invention, it is possible to properly binarize each pixel of the multi-valued image and perform a stable inspection.

In the above embodiments, the simple matrix LCD is used as the display panel to be inspected, but the present invention is not limited to this, and any display panel having another pixel configuration may be used. Good. Further, in the embodiment, the binary image is displayed on the inspection result display device, but instead of displaying the binary image, it is determined whether the display panel is a good product or a defective product, or a defect occurs. You may make it display the comment which points out the location of a pixel.

That is, for example, an inspection apparatus may be provided with a judging means for judging whether the display panel is a non-defective product or a defective product based on the result of comparison by the comparison means. If the display panel inspecting device is configured in this way, each pixel of the two pixels is calculated based on a predetermined threshold value by the comparing unit from the subtraction value of the luminance of each pixel which is subtracted by the calculating unit.
It is possible to determine whether the display panel is a non-defective product or a defective product by the determination means based on the result of the comparison after the value conversion process. Then, the inspection apparatus having such a determination means may be configured to include the binary image storage means and the inspection result display device, as in the embodiment.

[0028]

As described above, according to the display panel inspection method of the first aspect of the present invention, a multi-valued image displayed in a predetermined pattern in which only predetermined pixels are turned on is photographed and stored. On the other hand, the multi-valued image displayed in the reverse pattern in which only the pixels other than the predetermined pixel are turned on is photographed and stored, and the brightness of the multi-valued image of each pixel of the stored predetermined pattern and reverse pattern is stored. Since each pixel is binarized and inspected based on a predetermined threshold value from the subtraction value of the luminance of each pixel subjected to the subtraction process, it is possible to automatically inspect whether or not each pixel has a display defect. Therefore, a stable inspection can be automatically performed by appropriately binarizing each pixel of the multi-valued image.

Further, according to the display panel inspection method of the second aspect of the present invention, since the binary image of each pixel which is binarized and stored is displayed, the inspection result is confirmed by the binary image. can do.

If a predetermined pattern in which each pixel is lit up every other pixel in the vertical and horizontal directions is set as in the third aspect, the individual patterns are subtracted from the opposite pattern. The pixel inspection can be performed accurately.

Further, according to the display panel inspection apparatus of the fourth aspect of the present invention, the multivalued image captured by the image pickup means is stored in each of the first and second multivalued image storage means, Each pixel is binarized based on a predetermined threshold value by the comparison means from the subtraction value obtained by subtracting the stored brightness of the multi-valued image of each pixel by the calculation means, and by the determination means from the comparison result. Since it is possible to determine whether the display panel is a non-defective product or a defective product, it is possible to automatically inspect whether or not each pixel has a defective display. Therefore, it becomes possible to automatically perform a stable inspection of the display panel by the binarization process.

Further, according to the display panel inspecting apparatus of the present invention, the binary image of each pixel binarized by the comparing means is stored in the binary image storing means. Since a predetermined inspection result can be displayed on the inspection result display device on the basis of the binary image of, the stable inspection can be automatically performed by binarizing each pixel of the multivalued image. .

[Brief description of drawings]

FIG. 1 shows an example of a display panel to be inspected, to which the present invention is applied, and FIG. 1A is a plan view illustrating a display state of a predetermined pattern in which each pixel is lit up every other pixel in the vertical and horizontal directions. , (B) are plan views illustrating a display state of a pattern opposite to that of (a).

FIG. 2 is a plan view exemplifying a binary image in which a multi-valued image of a predetermined pattern and a multi-valued image of an inverse pattern are binarized to have no defective pixels.

FIG. 3 is a block diagram showing a configuration example of a display panel inspection apparatus according to the present invention.

FIG. 4 is a flowchart showing a procedure and a control example of a display panel inspection method according to the present invention.

FIG. 5 is a flowchart showing an example of control of binarization processing.

FIG. 6 illustrates an example of a case where a pixel defect occurs, and
FIG. 4A is a plan view illustrating a display state of a predetermined pattern, and FIG. 7B is a plan view illustrating a display state of an inverted pattern.

FIG. 7 is a multi-valued image of a predetermined pattern of FIG.
It is a top view which illustrated the binary image at the time of a defect generate | occur | produced which binarized the multi-valued image of the reverse pattern of (b).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 display panel 2 signal generator 3 imaging means 4 A / D converter 5 first multi-valued image storage means 6 second multi-valued image storage means 7 binary image storage means 8 control means 9 memory 10 inspection device 11 inspection Result display device

Claims (5)

[Claims] 1. A method of inspecting a pixel region of a display panel, comprising displaying a multi-valued image in a predetermined pattern in which only predetermined pixels of the display panel are turned on, and displaying the multi-valued image of the displayed predetermined pattern. The multi-valued image is captured by the image pickup means and stored in the first multi-valued image storage means, and then the multi-valued image is displayed in a reverse pattern in which only the pixels other than the predetermined pixels of the display panel are turned on. Then, the displayed multivalued image of the reverse pattern is captured by the image pickup means and stored in the second multivalued image storage means, and subsequently, the predetermined value stored in the first multivalued image storage means. The brightness of the multi-valued image of each pixel of the pattern and the brightness of the multi-valued image of each pixel of the reverse pattern stored in the second multi-valued image storage means are subtracted after the subtraction processing by the operation means. Brightness of each processed pixel A method of inspecting a display panel, which comprises binarizing each pixel based on a predetermined threshold value by a comparing means from the subtracted value of the degree and inspecting the pixel. 2. The binary image of each pixel binarized by the comparing means is stored in a binary image storage means, and the binary image of each pixel captured in the binary image storage means. Is displayed on the inspection result display device. The method for inspecting a display panel according to claim 1, wherein 3. The method for inspecting a display panel according to claim 1, wherein the predetermined pattern is a state in which each pixel is lit up every other pixel in the vertical and horizontal directions. 4. An apparatus for inspecting a pixel area of a display panel, comprising: an image pickup means for taking in a multivalued image displayed by turning on the pixels of the display panel; and the multivalued image taken in by the image pickup means. First multi-valued image storage means and second multi-valued image storage means for storing, luminance of the multi-valued image of each pixel stored in the first multi-valued image storage means, and the second multi-valued image An arithmetic means for subtracting the brightness of the multi-valued image of each pixel stored in the storage means, and each pixel based on a predetermined threshold value from the subtracted value of the brightness of each pixel subtracted by this arithmetic means. An inspection apparatus for a display panel, comprising: a comparison unit that performs a binarization process; and a determination unit that determines whether the display panel is a non-defective product or a defective product based on a result of comparison by the comparison unit. 5. A binary image storage means for storing a binary image of each pixel binarized by the comparison means, and a binary image of each pixel loaded in the binary image storage means. The inspection device for a display panel according to claim 4, further comprising: an inspection result display device for displaying a predetermined inspection result.