JPH06308047A - Color liquid crystal panel defect inspection device - Google Patents

Abstract

PURPOSE:To improve inspection accuracy by performing smoothing processing with different smoothness for differential image data, producing smoothed differential image data from two smoothed processing image data and clarifying the judgment criteria of binary processing. CONSTITUTION:A monochrome camera 11 photographs a light controlled color liquid crystal panel A and sends the original image data to an image processor 12. The device 12 processes the original image and detects the interference fringe and indicates it on a display 13. The panel A is lighted with different brightness and differential image data of the original image data is produced, which causes unevenness in density value in the peripheral part in the imteference fringe. So, smoothing processing is performed with different smoothness for the differential image data to produce two smoothed processing image data and then smoothed differential image data. If this smoothed differential image data is binary processed with a predetermined binarizing threshold value, binary processed image data clearly discriminated interference fringe from the peripheral part are obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color liquid crystal panel defect inspection apparatus for inspecting a color liquid crystal panel for the presence of interference fringe defects.

[0002]

2. Description of the Related Art Conventionally, the following two methods are generally used as methods for detecting interference fringes of a color liquid crystal panel.
The first method is a visual inspection method for observing interference fringes by observing a color liquid crystal panel from a vertical direction or an oblique direction. A second method is a method of inspecting interference fringes by photographing a color liquid crystal panel with a camera and binarizing the photographed image.

[0003]

[Problems to be Solved by the Invention]
In the case of the above method, due to the nature of the liquid crystal panel inspection, the inspection must be performed in a dark place, and the fatigue of the inspection operator is considerable in the inspection for a long time. Further, since the color liquid crystal panels are moved one by one so that the interference fringes can be observed well, the appearance may be different for each panel, and the determination standard may be ambiguous.

Further, in the case of the second method of subjecting the image picked up by the camera to the binarization processing, there is not much difference in brightness between the portion where interference fringes appear and the portion where interference fringes do not appear, and the color liquid crystal is further used. The brightness varies slightly depending on the panel. Also, since the color liquid crystal panel has a structure in which the brightness changes depending on the viewing angle, in the image taken by the camera,
The brightness varies depending on the upper position, the lower position, the left position, and the right position. For these reasons, it is extremely difficult to uniquely determine the binarization threshold value, which is the criterion for the binarization process on the captured image, and the inspection accuracy of the interference fringe defect is reduced. There is.

The present invention was devised in view of such circumstances, and in a color liquid crystal panel defect inspection apparatus of a system for inspecting interference fringe defects by subjecting a photographed image to binarization, It is an object of the present invention to improve the inspection accuracy of interference fringe defects by clarifying the criterion for the binarization process.

[0006]

A color liquid crystal panel defect inspection apparatus according to the present invention comprises means for illuminating and displaying the entire surface of a color liquid crystal panel with a certain brightness, and a whole surface of the color liquid crystal panel having a brightness different from that described above. Means for lighting up and displaying, means for photographing the color liquid crystal panel, means for temporarily storing the photographed original image data, and means for obtaining difference image data by taking a difference between two original image data having different brightness. A means for temporarily storing the difference image data with a certain smoothness, a means for smoothing the difference image data with a different smoothness from the above, and two smoothers with different smoothness. And a means for binarizing the smoothed difference image data with a predetermined binarization threshold. It is an butterfly.

[0007]

When the color liquid crystal panel is lit and displayed with different brightness and the difference image data of the original image data of both is created, the density value of the interference fringe portion becomes almost 0, while the noise around the interference fringe portion becomes noise. As a result, the density value becomes uneven. Further, the boundary between the interference fringe portion and the peripheral portion of the interference fringe is unclear. In this state, it is almost impossible to binarize and clearly determine the interference fringes. Therefore, smoothing processing is performed with different smoothness for the difference image data, two smoothing processed image data are created, and the difference between the two smoothed processed image data is calculated to obtain the smoothed difference image data. When created, the noise unevenness is almost completely removed, and the interference fringe portion is clearly separated from the interference fringe peripheral portion. When the smoothed difference image data is binarized with a predetermined binarization threshold value, binarized image data in a state where the interference fringe portion is very clearly identified from the peripheral portion of the interference fringe is obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a color liquid crystal panel defect inspection apparatus according to the present invention will be described in detail below with reference to the drawings.

First, the structure of the color liquid crystal panel A to be inspected will be conceptually described with reference to FIG. The color liquid crystal panel A is one in which a liquid crystal 3 is enclosed between two glass plates 1 and 2, and the surface tension of the liquid crystal 3 draws the glass plates 1 and 2 together to make the gap size non-uniform. To prevent this, a spacer 4 is placed between the glass plates 1 and 2 in the liquid crystal 3.
Are interspersed in a distributed manner. In addition, here, the pixel electrode,
Common electrode, RGB three primary color filters, deflector,
Driving transistors and the like are omitted.

By the way, the interference fringe defect appears in the color liquid crystal panel A because the distribution of the spacers 4 becomes nonuniform and the gap size between the glass plates 1 and 2 becomes slightly nonuniform. Is.

FIG. 1 is a block diagram showing the schematic arrangement of a color liquid crystal panel defect inspection apparatus according to an embodiment. In FIG. 1, 10 is a color liquid crystal panel lighting control device, 11 is a monochrome camera, 12 is an image processing device, 13 is an image display, and 14 is a host computer. The lighting control device 10 controls lighting of the color liquid crystal panel A under various conditions based on a command from the host computer 14. The monochrome camera 11 photographs the color liquid crystal panel A whose lighting is controlled, and sends the original image data to the image processing device 12. The image processing device 12 detects various interference fringes appearing on the color liquid crystal panel A by performing various processes described below on the original image data sent from the monochrome camera 11. The display 13 displays an image of the original image data sent to the image processing device 12 and a processed image that has been subjected to image processing by the image processing device 12. The host computer 14 gives commands of various lighting conditions to the lighting control device 10 and, at the same time, processes the interference fringe defect data obtained by the image processing device 12 to determine the position, size and degree of the interference fringe defect. And so on.

FIG. 3 shows an image displayed on the display 13. The displayed image includes an original image of the color liquid crystal panel A captured by the monochrome camera 11 and a processed image obtained by image-processing the data of the original image by the image processing device 12. FIG. 3A shows an original image when the entire surface of the color liquid crystal panel A is illuminated and displayed in white by using the graphic function of the host computer 14. Interference fringes 21 appear in this original image. The interference fringe 21 appears darker than the peripheral portion 20.

FIG. 3B shows an original image when the entire surface of the color liquid crystal panel A is illuminated and displayed in white in a slightly darker state than the case of FIG. The interference fringe 23 also appears darker than the peripheral portion 22. The interference fringe peripheral portion 22 in FIG. 9B is darker than the interference fringe peripheral portion 20 in FIG. However, there is almost no difference in brightness between the interference fringes 23 in FIG. 7B and the interference fringes 21 in FIG.

As described above, the lighting control device 10 changes the brightness when the entire surface of the color liquid crystal panel A is lit and displayed in white to obtain the original image data of FIGS. Keep them in memory. Next, the image processing device 12 creates difference image data by taking the difference between the two original image data, and displays the difference image on the display 13 as shown in FIG. Taking the difference between two original image data is to compare the density values of pixels at the same position between the original image data of FIG. (A) and the original image data of FIG. (B). The density value obtained as a result of subtracting the density value of FIG. 6B from the density value of is used as the density value of the difference image data at the same position. However,
When the density value resulting from the subtraction becomes negative, the density value at that pixel position is replaced with 0.

In FIG. 2C, the interference fringe portion 25 is the difference between the interference fringe 21 in FIG. 1A and the interference fringe 23 in FIG. 2B, and there is almost no difference in brightness.
The density value of the interference fringe portion 25 is almost zero. The interference fringe peripheral portion 24 is the difference between the interference fringe peripheral portion 20 in FIG. 7A and the interference fringe peripheral portion 22 in FIG. Is also big.

By the way, actually, the original image data of FIGS. 3A and 3B contains noise, and the brightness of the backlight also differs depending on the location. Also, the brightness changes depending on the viewing angle. Due to these factors, the density value of the interference fringe peripheral portion 24 and the density value of the interference fringe portion 25 are not uniform in the difference image data, and unevenness occurs over a wide range. Moreover, due to the nature of the interference fringes,
The boundary between the interference fringe peripheral portion 24 and the interference fringe portion 25 is not clear, and the density value gradually changes. This is a common phenomenon.

Due to such circumstances, as in the conventional example,
It is extremely difficult to detect the interference fringe clearly in the simple binarization in which the threshold value is fixed.

Therefore, in the present embodiment, the image processing apparatus 12 performs the smoothing process on the processed image data of FIG. 6C to obtain the smoothed image data as shown in FIG. Along with this, stronger smoothing processing is also performed on the difference image data of FIG. 6C to obtain smoothed image data as shown in FIG. Both of these smoothed image data are stored. In order to make the smoothing process stronger, it is possible to deal with it by using a filter with a larger capacity for smoothing or by increasing the number of smoothing times. As a result, the smoothed image of FIG. 6E is in a smoother state than the smoothed image of FIG.

After the smoothing processing is performed on the differential image data shown in FIG. 6C with different smoothness in this way, the smoothed image data shown in FIGS. The image processing device 12 creates smoothed difference image data that is the difference between the smoothed image data of FIG. 7D and the smoothed image data of FIG. Here again, in the pixel at the same position, the density value of the result obtained by subtracting the density value of FIG. 6E from the density value of FIG. 6D is set as the density value of the smoothed difference image data at the pixel of the same position, and An image of the smoothed difference image data based on the difference density value is displayed on the display 13 as shown in FIG. However, when the density value resulting from the subtraction becomes negative, the density value at that pixel position is replaced with 0.

In the smoothed difference image data of FIG. 6F obtained by taking the difference after the two-stage smoothing processing, the noise seen in the difference image data of FIG. 6C is almost completely removed.

That is, in the smoothed difference image data, the interference fringe portion 31 is clearly divided from the interference fringe peripheral portion 30. Therefore, the image processing device 12 further performs noise removal processing on the smoothed difference image data of FIG. 6F, and then performs simple binarization processing with a required binarization threshold value. Then, as shown in FIG. 9G, the binarized image data in a state where the interference fringe portion 33 is very clearly distinguished from the interference fringe peripheral portion 32 is obtained.

FIG. 4 shows a case where the smoothed differential image data of (f) and the binarized image data of (g) are created from the differential image data of (c) of FIG. 3 in the above image processing. 3 is a waveform diagram illustrating the operating principle of FIG. These waveform diagrams are shown one-dimensionally. In reality, it is two-dimensional. The horizontal axis represents the pixel position and the vertical axis represents the density value.

A waveform 40 shown in FIG. 4A is an image of the differential image data shown in FIG. The recessed portions 41 and 42 correspond to the portion where interference fringes appear, that is, the interference fringe portion 25 where the density value is almost zero. Wave 40
The waveform 43 shown in FIG. 4B is the waveform 43 shown in FIG. 4D, and the waveform 44 is the waveform 40 shown in FIG. Due to the smoothing process, the concave portions have a higher level and the convex portions have a lower level than the surroundings.
It is clear that waveform 44 is more smoothed than waveform 43.

Next, a waveform 45 obtained by subtracting the waveform 44 from the waveform 43 is a waveform 45 shown in FIG.
5 corresponds to (f) of FIG. The brighter portion inside the interference fringe portion has a density value of 0. Therefore, for example, when the density value 0 is used as the binarization threshold value 46 and the waveform 45 is binarized, a steep rise / fall waveform 47 is formed at the boundary as shown in FIG. This is an image of the interference fringe portion 33 in FIG. 3G, and the interference fringe portion is clearly identified.

The processing procedure of this color liquid crystal panel defect inspection apparatus will be described below with reference to the flow chart shown in FIG. First, all pixels of the color liquid crystal panel A are lit by the lighting control device 10 to display white (step S1). The lighting state at this time is relatively bright. The color liquid crystal panel A displayed in white is photographed by the monochrome camera 11, and the original image data is taken by the image processing device 12.
(Step S2, see FIG. 3A). Next, all the pixels of the color liquid crystal panel A are turned on again to display white, but at this time, it is made darker than in the case of step S1 (step S3).

The color liquid crystal panel A is photographed again by the monochrome camera 11, and the original image data is taken by the image processing apparatus 1.
2 (step S4, see FIG. 3B). In the image processing apparatus 12, the density value of the darker original image data is subtracted from the density value of the brighter original image data obtained as described above for each same pixel to create difference image data (step S5). (See FIG. 3C).

Next, the difference image data is first subjected to a smoothing process with a small smoothness to obtain smoothed image data corresponding to (d) of FIG. 3 (step S6). Further, the difference image data is subjected to smoothing processing having a higher smoothness to obtain smoothed image data corresponding to (e) of FIG. 3 (step S7). And those two
The smoothed difference image data of the difference between the two smoothed image data that have been smoothed is created (step S8,
See (f) of FIG. 3. This makes it possible to remove noise and unevenness in density value. Finally, binarization processing is performed with a required binarization threshold value 46 to create binarized image data in which the interference fringe portion 33 is clearly separated from the interference fringe peripheral portion 32 (step S9, in FIG. g)).

[0028]

As described above, according to the present invention, the difference image data of two original image data having different brightness is created, and the difference image data has two stages of different smoothness. Smoothing processing is performed to create two smoothing processed image data, and the difference is further taken to create smoothed difference image data so that the interference fringe portion can be clearly separated from the interference fringe peripheral portion. Therefore, by performing binarization processing on the smoothed image data with a predetermined binarization threshold value, the interference fringe defect can be detected with high accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a color liquid crystal panel defect inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view conceptually showing the structure of a color liquid crystal panel to be inspected.

FIG. 3 is a state diagram of an image displayed on a display for explaining the operation in the embodiment.

FIG. 4 is a waveform diagram for explaining the operation in the example.

FIG. 5 is a flowchart for explaining the operation of the embodiment.

[Explanation of symbols]

A: Color liquid crystal panel 1, 2 ... Glass plate 3 ... Liquid crystal 4 ... Spacer 10 ... Color liquid crystal panel lighting control device 11 ... Monochrome camera 12 ... Image processing device 13 ... Image display display 14 ... ... host computer 20,22 ... interference fringe peripheral part in original image data 21,23 ... interference fringe in original image data 24 ... interference fringe peripheral part in difference image data 25 ... interference fringe part 26 in difference image data 26, 28 ... Peripheral part of interference fringes in smoothed image data 27, 29 ... Interference fringe part in smoothed image data 30 ... Peripheral part of interference fringes in smoothed difference image data 31 ... Interference in smoothed difference image data Stripe part 32 ... Peripheral part of interference fringes in binarized image data 33. Interference fringes part that

Claims (1)

[Claims] 1. A means for illuminating and displaying the entire surface of a color liquid crystal panel with a certain brightness, a means for illuminating and displaying the entire surface of the color liquid crystal panel with a brightness different from the above, and a means for photographing the color liquid crystal panel. A means for temporarily storing the captured original image data and taking a difference between the two original image data having different brightnesses to create difference image data, and smoothing the difference image data with a smoothness temporarily stored. Processing means, means for smoothing the difference image data with a smoothness different from that described above, and difference between the two smoothed image data having different smoothnesses to obtain smoothed difference image data And a means for binarizing the smoothed difference image data with a predetermined binarization threshold value.