JPH0522239B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an inspection device for liquid crystal display panels used for televisions and the like.

(Prior Art) In recent years, a liquid crystal display panel for television, as shown in FIG. 11, which combines thin film transistors and color filters has been developed. This liquid crystal display panel is constructed by arranging pixels 1 of each of the three primary colors of light in a predetermined arrangement order, and its cross-sectional configuration is shown in FIG. 12. The structure is such that flat glass substrates 3 and 4 are arranged facing each other using spacers 2 and 2' as supports, and a common electrode 5 is passed between the spacers 2 and the glass substrate 3 between the glass substrates 3 and 4. , and a plurality of pixel electrodes 6-1, 6-2... are arranged on a plane on the glass substrate 4, and the common electrode 5 and each pixel electrode 6-1, 6-2... are arranged facing each other. There is. Each pixel electrode 6-1, 6-2 between the common electrode 5 and the glass substrate 3
Color filters 7-1, 7-2, etc. of the three primary colors of light are arranged in the corresponding portions, respectively.
Then, the common electrode 5 and each pixel electrode 6-1, 6-
2... alignment films 8 and 9 are respectively arranged between them,
A liquid crystal 10 is inserted between these alignment films 8 and 9. Note that 11 and 12 are deflection plates, and 13-1, 13-2, . . . are thin film transistors. For color display, a light source 14 is arranged to irradiate light into the liquid crystal 10 through the glass substrate 4. In this state, the common electrode 5 and the predetermined pixel electrode 6
-1, 6-2..., when a voltage is applied between the color filters 7-1, 7-2...
Light with a wavelength of ... will pass through. This causes the image to be displayed on the panel.

By the way, when manufacturing such a liquid crystal display panel, the panel is inspected. The items include image defects, brightness unevenness, crosstalk, afterimages, etc., and these inspections are performed visually by an operator because the liquid crystal display panel has a large external size and a very large number of pixels. For example, the inspection can be carried out by placing a liquid crystal display panel on an inspection table, connecting the liquid crystal panel display controller to the display panel, and in this state, controlling the display panel according to each inspection item using the liquid crystal panel display controller. Display the image. Then, the inspection results are obtained by visually observing each image at this time by an operator. For example, if the inspection item is a brightness unevenness test, all pixels on the liquid crystal display panel are displayed at the same brightness, and the detection result is obtained by visually checking whether the entire surface of the liquid crystal display panel is uniformly displayed at the same brightness. There is.

(Problem to be solved by the invention) In this way, the display panel is composed of a large number of pixels (50,000 to 300,000) and the size is 300 μm on one side.
~100 μm, so inspection is performed visually by an operator. For this reason,
Currently, it is not possible to quantitatively test for brightness unevenness, crosstalk, etc., and the test results are uneven.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a highly reliable liquid crystal display panel inspection device that can automatically and quantitatively perform each inspection item.

[Structure of the Invention] (Means for Solving the Problems) The present invention displays an image by arranging a plurality of pixels on a plane, emitting light from one side, and selectively driving the pixels. In an inspection device for a liquid crystal display panel, the display control means drives and controls each pixel of the liquid crystal display panel according to each inspection item of pixel defects, brightness unevenness inspection, crosstalk inspection, and afterimage inspection for the liquid crystal display panel; Issues inspection commands for each inspection item of pixel defect, brightness unevenness inspection, crosstalk inspection, and afterimage inspection to the imaging device that captures the image displayed on the display panel and the display control means, and also issues inspection commands for each of these inspection items. When an inspection command is issued, each image signal output from the imaging device is received, and each image processing according to each inspection item is executed to inspect the liquid crystal display panel.The location and location of pixel defects are determined from the image signals. Detection of pixel defects by calculating the number and comparing it with the judgment standard data; Brightness unevenness inspection which calculates the average gray level from the image signal and comparing it with the judgment standard; Each image signal when the liquid crystal display panel changes from white to black. A crosstalk test that determines the difference in each average gray level in , compares the gray level in the image signal when the liquid crystal display panel suddenly changes from white to black, and detects the change from white gray level to black gray level within a predetermined time. This is a display panel inspection device that attempts to achieve the above object, and is equipped with an afterimage inspection for determining whether the image has been removed, and an inspection means for executing the following image processing.

(Function) By providing such a means, the inspection means can send inspection commands for each inspection item to the display control means that drives and controls each pixel of the liquid crystal display panel, that is, pixel defect, brightness unevenness inspection, and crosstalk. When each inspection command for inspection and afterimage inspection is issued, the liquid crystal display panel is driven according to the inspection item.

In this state, the display control means receives each image signal output from the imaging device and processes each image according to each inspection item, that is, calculates the position and number of pixel defects from the image signal and compares it with judgment data. Detection of pixel defects, Brightness unevenness inspection that calculates the average gray level from image signals and compares it with judgment standards, Crosstalk that calculates the difference in average gray level of each image signal when the liquid crystal display panel changes from white to black Inspection: An afterimage test is performed to compare the gray level of the image signal when the liquid crystal display panel suddenly changes from white to black, and to determine whether the gray level changes from white to black within a predetermined time.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a liquid crystal display panel inspection apparatus. In the figure, 20 is a color liquid crystal display panel, and this color liquid crystal display panel 20 is held by an arm (not shown) of a transport mechanism 21 and taken out from a box 22 that stores color liquid crystal display panels 20 that have not been inspected. The test result is placed on the driver board 23, and after the test is completed, it is gripped by the arm again and stored in a box 24 for a "good" test result or a box 25 for a "bad" test result. The driver board 23 has a window 23a formed in a portion on which the color liquid crystal display panel 20 is placed, and electrically connects each pixel electrode and common electrode of the color liquid crystal display panel 20 to the display control unit 26. be. Below this driver board 23 are light sources 27 that function as backlights,
28 and a reflecting mirror 29 are also arranged. In addition, the driver board 23 and each light source 27,
A light-transmitting diffuser plate 30 is disposed between the light sources 27 and 28 so that the light emitted from each light source 27 and 28 is irradiated onto the color liquid crystal display panel 20 with uniform illuminance.

On the other hand, above the color liquid crystal display panel 20 is a CCD (solid-state image sensor) camera 31 as an imaging device.
is located. This CCD camera 31 is attached to an XY table 32 and is configured to move in an XY plane, that is, a plane parallel to the display surface of the color liquid crystal display panel 20. And this
An image signal output from the CCD camera 31 is sent to a detection means 33. This detection means 33 issues inspection commands to the display control unit 26 for each inspection item, that is, pixel defect, brightness unevenness inspection, crosstalk inspection, and afterimage inspection, and also
It has a function of receiving an image signal from the camera 31 and processing the image signal for each inspection item to obtain inspection results for the color liquid crystal display panel 20. Specifically, it is composed of an image processing section 34 and a main control section 35. The image processing unit 34 receives a command from the main control unit 35 indicating inspection items.
It has the function of image processing the image signal from the CCD camera 31 according to the inspection item.
The specific configuration is shown in the figure. As shown in the figure, an image CPU (image central processing unit) 36 is provided which is connected to a main control section 35, and an image processing processor 39 and an image memory 40 are connected to this image CPU 36 through an interface 37 and a bus line 38. There is. The image CPU 36 also has a floppy disk 4 via a main storage 41 and an I/O (input/output controller) 42 in which inspection programs for each inspection item are stored.
3. The disk 44 is connected. In addition, a CCD camera 31 is installed on the bus line 38.
and a CRT display device 45 are connected. By the way, the image CPU 36 receives an inspection command from the main control unit 35 and loads an inspection program corresponding to an inspection item from the main storage device 41 to the image processing processor 39 through the interface 37,
It also has a function of displaying the image processing results obtained by the image processing processor 39 on the CRT display device 45. In contrast, the image processing processor 39 displays the image processing result obtained by the image processing processor 39 on the image data stored in the image memory 40. It has the function of only executing processing.

The display control unit 26 also receives inspection instructions issued from the main control unit 35 for the color liquid crystal display panel 20 according to inspection items such as pixel defects, brightness unevenness inspection, crosstalk inspection, and afterimage inspection,
Color liquid crystal display panel 2 according to these inspection instructions
It has a function of driving and controlling each pixel of 0.

On the other hand, the main control unit 35 controls the operation of the image processing unit 34, the XY table drive unit 48 that drives and controls each of the X-axis drive motors 46 and Y-axis drive motors 47 of the XY table 32, the display control unit 26, and the transport mechanism 21. An inspection command indicating an inspection item is issued to the transport mechanism control section 49 to control the operation for each inspection item.

Next, the operation of the apparatus configured as described above will be explained.

The main control section 35 issues a command according to the inspection flowchart shown in FIG. 3, and first issues a transport command to the transport mechanism control section 49 in step s1. As a result, the transport mechanism 21 is activated, and the color liquid crystal display panel 20 housed in the uninspected box 2 is gripped by the arm, taken out, and placed on the driver board 23. At the same time, the main control section 35 issues an inspection command for defect detection to the image processing section 34, the XY table driving section 48, and the display control section 26. Then, the XY table drive unit 4
8, each X and Y axis drive motor 46, 47
is driven, the XY table 32 operates, and
CCD camera 31 is set so that its field of view is area F1 on color liquid crystal display panel 20 shown in FIG. Further, the display control unit 26 applies a voltage at a predetermined level to all pixel electrodes of the color liquid crystal display panel 20. As a result, all of the three primary colors of light on the color liquid crystal display panel 20 are displayed. In this state, in step s2, the CCD
The image signal of the area F1 captured by the camera 31 is sent to the image processing processor 3 through the bus line 38.
9, the image signal is A/D converted by the image processing processor 39, and sequentially sent to the image memory 40.
is memorized. Then, all the image signals of the area F1 are A/D converted and the image data of the area F1 {6th
When the image is stored in the image memory 40 as shown in FIG. Here, defect detection is performed according to the defect inspection flowchart shown in FIG. First of all,
Pixel selection is performed in step e1. This is to extract pixels corresponding to red, green, and blue from the image data of area F1. First, the main control section 35 issues a command to this effect to the display control section 26, and the display control section 26 controls the color liquid crystal display. Only the red pixels on the display panel 20 are driven. Therefore, the image on the color liquid crystal display panel 20 becomes red, this image of the area F1 is captured by the CCD camera 31, and the image data {FIG. 6a} is stored in the image memory 40. Then, the image processing processor 39 extracts pixels corresponding to red in the image data shown in FIG. 2B from each image data shown in FIG. Next, the process moves to step e2, where a shading correction is performed. This is because the amount of light irradiated onto the color liquid crystal display panel 20 by each light source 27, 28 is often not uniform, so
0 is not placed on the driver board 23, and image data is obtained when each of the light sources 27 and 28 is turned on. FIG. 7 shows this image data, and there is uneven brightness between the center and the periphery of the image. Therefore, the image processing processor 39 corrects the gray level of each pixel using the image data shown in FIG. 7 on the image data shown in FIG. 6c. Then, in the next step e3, 2
Value conversion processing is executed, and as a result of this processing, pixels whose gray levels are below the reference level are determined as defective pixels G1 and G2, as shown in FIG. Then, in step e4, the position (coordinates) of the defective pixel is
is detected. Then, in step e5, it is determined whether defect detection for each pixel for other green and blue pixels has been completed, and if it has not been completed, the process returns to step e1.
Returning to FIG. 6A, green and blue pixels are extracted from the image data shown in FIG. 6a, and defect detection is performed in the same manner as in the case of red. When defect detection for all colors is completed, the process moves to step e6, where it is determined whether defect detection for pixels of each color has been completed for the entire surface of the color liquid crystal display panel 20, that is, the entire area from F1 to F9. At this point, if you have not finished, proceed to the step
At e7, a drive command is issued from the main control unit 35 to the XY table drive unit 48, and the CCD camera 31
is moved to a position to image the F2 area. and,
Defect detection is performed for pixels of each color in the F2 area. After the operations in steps e1 to e7 are executed and the detection of defects on the entire surface of the color liquid crystal display panel 20 is completed, the number of defects on the entire surface is determined in step e8. Then, in step e9, the quality of the color liquid crystal display panel 20 is determined. This determination is performed by storing determination criterion data corresponding to the entire surface of the color liquid crystal display panel 20 in advance in the main storage device 41 as shown in FIG.
The determination is made by comparing this data with the position and number of defective pixels obtained by defect detection. This judgment criterion data is, for example,
The number of defects in the Q1 zone is set to be "0" or less, the number of defects in the Q2 zone is set to be "1" or less, and the number of defects in the Q3 zone is set to be "1 or 2" or less. If these conditions are not met, it is considered defective. It will be judged.

After the above defect detection is completed, brightness unevenness is detected next.

After the above defect detection is completed, each area F1 to F9
Image data subjected to shading correction for each color is stored in the image memory 40. Therefore, the image processing processor 39 processes each area F1 to F9.
Find the average gray level of each color. for example,
Average red density level R1 in each area F1 to F9,
R2...R9 are each calculated. Then, the average gray level R ₀ for the entire surface of the color liquid crystal display panel 20 is determined.

R ₀ =(R1+R2+...+R9)/9 After that, the next judgment standard is created based on this average gray level R ₀ and pass/fail is judged. That is, R ₀ ×0.9≦Ri≦R ₀ ×1.1 (i=1 to 9). If each average gray level R1, R2...R9 (=Ri) of each region F1 to F9 does not satisfy the above conditions, it is determined to be defective. The above determination is then performed for green and blue as well.

After the brightness unevenness test is completed, a crosstalk test is performed next. When the main control unit 35 issues a crosstalk inspection command to the display control unit 26, the display control unit 26 displays an image of the color liquid crystal display panel 20 in which the W area is white and the B area is black, as shown in FIG. Display. Further, upon receiving the inspection command for the crosstalk inspection, the XY table driving section 48 sets the CCD camera 31 at a position to image the area F1. In this state, the display control unit 26 changes the color of the area W from white to black. At this time, the CCD camera 31 captures images in the area F1 before and after the color of the area W changes, and sends the image signals to the inspection means 33. Therefore, the image memory 40 stores image data before and after the color of the area W in the area F1 changes. The image processing processor 39 determines and compares the average gray level of the previous and subsequent image data, and sends the difference to the main control section 35. Therefore, the main control unit 35 determines that the product is defective if the average gray level difference is equal to or greater than a predetermined value. Then, such a judgment is made for each area F1 to F9.
is executed against.

After this crosstalk test is completed, an afterimage test is performed. During this afterimage inspection, the image on the color liquid crystal display panel 20 is changed by the display control section 26 into an image in which the W area is white and the B area is black, as shown in FIG. Further, the CCD camera 31 is set at a position to image the usage area F5, that is, the W area. In this state, the display control unit 26 suddenly changes the W area from white to black. During this sudden change, the CCD camera 31 captures an image of the W area and outputs the image signal. Therefore, the image processing processor 39 receives an image signal every 16 ms, performs A/D conversion, and sequentially stores the image data in the image memory 40, and executes this processing for about 1 s. Then, after 1 second has elapsed, the image processing processor 39 compares the gray level of each image data obtained and determines whether the white gray level has changed to the black gray level within a predetermined time. As a result of this determination, if the change from the white shading level to the black shading level takes longer than a predetermined time, it is determined to be defective.

In this manner, in the above embodiment, an image corresponding to the inspection item is displayed on the color liquid crystal display panel 20 under drive control of the display control unit 26, and this image is captured by the CCD camera 31. The configuration is such that the signal is sent to the inspection means 33, and the inspection means 33 executes image processing according to the inspection item to inspect the color liquid crystal display panel 20, so that the color liquid crystal display panel 20 can be inspected quantitatively and This will allow for more accurate inspections, and there will be no unevenness in inspections by operators. What's more, the test, which previously took an operator about three minutes, can now be completed in about one minute thanks to automation. Therefore, the quality of the color liquid crystal display panel 20 as a product can be improved, and operator fatigue can be reduced.

Note that the present invention is not limited to the above-mentioned embodiment, and may be modified without departing from the spirit thereof. For example, it can be applied to inspection of black and white liquid crystal display panels and liquid crystal display panels used in personal computers and the like.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a highly reliable liquid crystal display panel inspection apparatus that can perform each inspection item automatically and quantitatively.

[Brief explanation of the drawing]

1 and 2 are configuration diagrams showing one embodiment of a liquid crystal display panel inspection device according to the present invention, and FIG.
4 is a diagram showing the imaging area for a color liquid crystal display panel, FIG. 5 is a defect inspection flowchart of the device of the present invention, and FIGS. 6 to 9 are a flowchart of the defect inspection of the device of the present invention. FIG. 10 is a diagram for explaining the operation of defect detection, FIG. 10 is a diagram for explaining crosstalk and afterimage inspection, and FIGS. 11 and 12 are configuration diagrams of a color liquid crystal display panel. 20...Color liquid crystal display panel, 21...Transportation mechanism, 23...Driver board, 26...Display control section, 27, 28...Light source, 29...Reflector, 30
...Diffusion plate, 31...CCD camera, 32...XY
Table, 33... Inspection means, 34... Image processing unit, 35... Main control unit, 36... Image CPU, 3
9... Image processing processor, 40... Image memory, 41... Main storage device.

Claims (1)

[Scope of Claims] 1. An inspection device for a liquid crystal display panel in which a plurality of pixels are arranged on a plane, light is irradiated from one side, and the pixels are selectively driven to display an image, comprising: a display control means for driving and controlling each pixel of the liquid crystal display panel according to corner inspection items for pixel defects, brightness unevenness inspection, crosstalk inspection and afterimage inspection for the display panel; Issues inspection commands for each inspection item of the pixel defect, the brightness unevenness inspection, the crosstalk inspection, and the afterimage inspection to the imaging device that captures an image, and the display control means, and issues inspection commands for each of these inspection items. The liquid crystal display panel is inspected by receiving each image signal output from the imaging device when the image is generated and performing each image processing according to each inspection item, and detecting the pixel defect from the image signal. The pixel defect detection is performed by determining the position and number of pixel defects and comparing it with the determination standard data; the brightness unevenness inspection is determining the average gray level from the image signal and comparing it with the determination standard; the liquid crystal display panel is changed from white to black. the crosstalk test for determining the difference in the average gray level of each of the image signals when the liquid crystal display panel suddenly changes from white to black; the afterimage inspection for determining whether the gray level has changed from a gray level to a black gray level;
An inspection device for a display panel, comprising: inspection means for performing each image processing;