KR100842460B1 - Method for detecting dot defects in flat display panel - Google Patents

Abstract

A method of detecting dot defects in a flat panel display panel is disclosed. The pixel defect detection method according to the present invention comprises the steps of acquiring an image for each color pattern using a photographing apparatus, performing a calibration on the acquired image, detecting a dot position for each color pattern; Comparing the luminance value of each dot with a reference value to detect dot defects.

Fault detection, calibration, luminance, luminance correction, high dot defects, off dot defects, line defects

Description

How to detect dot defects on flat panel display panel {METHOD FOR DETECTING DOT DEFECTS IN FLAT DISPLAY PANEL}

1 is a flow chart of a dot defect detection method according to the method of the present invention.

2 is a conceptual diagram of a calibration process according to the method of the present invention.

3 is a conceptual diagram of a luminance correction process according to the method of the present invention.

The present invention relates to a dot defect detection method of a flat panel display panel, and more particularly, to a dot defect detection method having a calibration process and a luminance correction process using a transformation matrix.

BACKGROUND With the popularization of products such as portable media players (PMPs), notebook computers, high definition televisions, communication terminals, portable receivers, flat panel display panels are widely used as displays of such products. Such a flat panel display panel controls light through a plurality of dots (pixels). The light control method includes a method of generating light from each pixel and a reflection or transmission process without generating light by itself. There is a way to adjust the amount of light. The former is called an active display, and the LED (Light Emitting Diode) belongs to this, and the latter is a passive display, and an LCD (Liquid Crystal Display) belongs to this.

As one of the inspection items of such a flat panel display panel, an inspection is performed as to whether light emission is normally performed from each dot. In the past, this dot defect detection process was performed in a manner that is mainly dependent on the human eye, so that the work result is very subjective, there is a high possibility of a problem caused by mistakes, and the quality of various manufacturing processes is monitored, controlled and improved. This was an obstacle to the use of consistent and efficient systems.

Therefore, there is a need for an automated dot defect detection method for solving various problems by subjective judgment of an operator and for automating manufacturing process monitoring and more efficient mass production of products.

It is an object of the present invention to provide an automated dot defect detection method for automated production process monitoring and for more efficient production of a product.

Another object of the present invention is to prevent an error from occurring during a dot defect detection process due to an existing dot defect.

It is another object of the present invention to provide a more accurate and efficient calibration procedure.

According to an embodiment of the present invention, a method for detecting a defect includes obtaining an image of each color pattern using a photographing apparatus, performing a calibration on the obtained image, and dots for at least one of each color pattern. Detecting a position and detecting a dot defect by comparing the luminance value of the dot with a reference value.

Preferably, the defect detection method according to the present invention includes at least one column of pixels constituting the opposite adjacent dot of the high dot adjacent to the test dot when the adjacent dot of the test target dot is a high dot, and the luminance is high. The method further includes the step of obtaining a corrected luminance value.

More preferably, the calibration step of the defect detection method according to the present invention comprises the steps of photographing a calibration image including reference points, calculating and transforming a transformation matrix for converting the reference points of the calibration image to the reference points of the target image The method may further include converting the obtained image into a calibrated image by applying the transformation matrix to the corrected image.

The defect detection method using these steps further includes comparing the luminance of the test subject dot with a predefined first or second threshold value and determining it as an off dot defect or a high dot defect in each case.

The defect detection method according to the present invention further includes the step of detecting a dot defect using the steps described above, and then determining the line defect if the dot defect continues in a horizontal or vertical direction more than a predetermined number. do.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description, specific details such as specific process flows or configurations are provided to provide a more general understanding of the present invention. In addition, it will be apparent to those skilled in the art that some of these details may be easily changed and modified. In addition, in the following description, detailed descriptions of well-known and common technologies that may unnecessarily obscure the subject matter of the present invention will be omitted.

1 is a flowchart showing a dot defect detection method of the present invention.

As a preparation step of the dot defect detection method according to the present invention, an image for each color pattern of R, G, and B is obtained using a camera (step 102).

In the next step, a calibration process is performed to correct the dot position state of the acquired image (step 104). The calibration process used in the automated dot defect detection method according to the present invention will be described with reference to FIG.

In the calibration process according to the present invention, the image is corrected using the transformation matrix 206. That is, the transformation matrix 206 for capturing the calibration image 202 including the reference points using a camera and taking the target image 204 to convert the reference points of the calibration image into the reference points of the target image. Calculate The corrected image 210 is obtained by applying the transformation matrix 206 obtained in this manner to the color pattern-specific image 208 obtained in the previous step. In the present exemplary embodiment, a separate calibration image is used, but a person skilled in the art will recognize that a similar calibration process can be performed using an image for each color pattern and a target image.

Next, the dot position in the horizontal or vertical direction is determined with respect to the image for each color pattern (106). In the present embodiment, the step 102 of acquiring an image for each color pattern, the calibration step 104, and the dot position detection step 106 are described as being sequentially performed, but those skilled in the art perform the above three steps in any order. You will recognize that you can.

As a preparatory operation for detecting dot defects, a step 108 of properly correcting the luminance of each dot is performed. A more detailed configuration of the luminance correction will be described with reference to FIG. 3. In a typical flat panel display panel, dots 302 representing three colors of R, G, and B are alternately repeated. In such a dot array, dot defect detection for one color is performed in one test for each color. In this embodiment, dot defect detection for R dots 304, 306, and 308 is described as an example. do.

Since dot defect detection is currently being performed on the R dots 304, 306, and 308, the G dots and the B dots should exist in the off state in a normal dot arrangement. However, high defects may also occur in some of the G dots and the B dots, and FIG. 3 schematically illustrates this. As shown in Fig. 3, the G dots and B dots 310, which are marked off, and the G dots and B dots 312 in the high defect state are present together.

In the case of a normal R dot, it must have an intermediate brightness value as indicated by the reference numerals 304 and 306. However, the dot indicated by 308 is measured to have a higher luminance value than the actual one due to the high defect dot on the right side even though it is a normal R dot. When the adjacent dots are high defect dots, strong light is scattered from the adjacent dots, which affects the luminance of the inspection object dot, and as a result, the luminance of the inspection object dot is measured to be brighter than actual. Therefore, in order to correct the error of the luminance measurement, the following specific steps are performed.

In the present embodiment, one dot is displayed as 2x4 pixels, and the pixel arrangement may be changed according to the performance of the camera used and the CCD structure. In the case of the inspection target dot 308, since the high dot defect 312 is adjacent to the right side, in order to correct the actually measured luminance value, one pixel column is arranged in the opposite direction of the high dot defect 312. It moves and measures the luminance value. Therefore, the luminance of the test target dot is measured while excluding the light scattering effect due to the high dot defect as much as possible, and as a result, accurate luminance measurement close to reality can be performed. In the present exemplary embodiment, the luminance is measured by moving only one pixel column, but the luminance may be measured by moving two or more columns of pixels according to the pixel structure of the dot.

After the above luminance correction step 108, the dot defect is detected by comparing the luminance value of the inspection target pixel with a set threshold value (step 110). That is, off defects and high defects exist in the dot defects that can be detected through the dot defect detection method of the present invention, and the off defects have luminance values below (or below) a predetermined threshold. It means a defect having, and a high defect means a defect having a luminance value above (or exceeding) a predetermined threshold. In order to detect such a defect, the method may include detecting a luminance value of a normal dot and setting a threshold value in advance. Alternatively, a dot defect may be determined by separately setting an ideal luminance value.

And determining that the dot defect detected by the above steps is continuous in the horizontal or vertical direction exceeding a predetermined reference number of dots (for example, five) for the line defect determination. (Step 112).

As described above, various embodiments of the present invention have been described for the understanding of the present invention, but as will be appreciated by those skilled in the art, the present invention is not limited to the specific embodiments described herein but is not limited to the scope of the present invention. Various modifications, reconfigurations, and substitutions can be made within the scope of the invention. Accordingly, it is intended that the present invention cover all such modifications and variations as fall within the true scope of the invention.

The dot defect detection method according to the present invention automatically detects dot defects that have been subjectively performed by an operator, thereby enabling more consistent and efficient detection of dot defects, and more accurately detecting dot defects through a luminance correction process. This gives the effect to be possible.

Claims (7)

In the method for detecting a defect of a flat panel display device, Acquiring an image for each color pattern using a photographing apparatus; Performing calibration using a transformation matrix on the image of the color pattern; Determining a position of a dot included in the image of the color pattern; And Detecting a dot defect by comparing the luminance value of the dot with a reference value Including, The detecting of the dot defect may include at least one column of pixels constituting the opposite adjacent dot of the high dot adjacent to the test target dot when the adjacent dot of the test target dot is a high dot. Measuring steps Defect detection method comprising a. delete delete The method of claim 1, The detecting of the dot defect further includes determining that the dot defect is an off dot defect when the luminance of the dot under test is smaller than a minimum value of the luminance value of the normal dot. The method of claim 1, The detecting of the dot defect further includes determining that the dot defect is a high dot defect when the luminance of the dot under test is greater than the maximum value of the luminance value of the normal dot. The method of claim 4, wherein If the off-dot defects are continuous in five or more in the horizontal or vertical direction, determining the line defects. The method of claim 5, If the high dot defect is continuous in five or more in the horizontal or vertical direction, determining the line defect further.

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