KR101327857B1 - Apparatus and method of measuring a defect of display device - Google Patents

Abstract

The present invention relates to an apparatus and method for measuring defects of a display device, which enables accurate and fast detection of defects in a regular arrangement of cells.

The defect measuring apparatus of this display apparatus may include a microscope for photographing the display apparatus; A regular period detecting unit detecting a regular period of the image photographed through the microscope; A copy image generating unit generating a copy image by shifting the image by the regular period; An image processing unit for comparing the image with the copy image and detecting a different portion through an exclusive OR; And a display unit for displaying the output of the image processing unit.

Description

Defective measuring device and method of display device {APPARATUS AND METHOD OF MEASURING A DEFECT OF DISPLAY DEVICE}

1 is a view schematically illustrating a failure measuring apparatus of a display device according to an exemplary embodiment of the present disclosure.

2 is a view of photographing a display device through a microscope of the present invention.

3 is a flowchart illustrating a method of measuring a failure of a display device according to an exemplary embodiment of the present invention.

4 is a diagram for detecting a regular period of an image photographed through a microscope.

5A and 5B are diagrams showing copy images in which the original image is shifted by one X axis period to the left and right of the X axis.

6A and 6B are diagrams showing copy images in which the original image is shifted by one Y-axis period to the upper side and the lower side of the Y axis.

7A to 7D are diagrams showing copy images in which the original image is shifted in both the X and Y axes.

8 is a diagram illustrating a comparison result of outputting through an exclusive OR after comparing an original image illustrated in FIG. 4 with a copy image generated by the method illustrated in FIGS. 5A and 5B.

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

2: LCD 4: microscope

6: Rule cycle detector 8: Copy image generator

10: image processing unit 12: display unit

14: Computer 15: Cell

16: original image

Copy image: 18a, 18b, 20a, 20b, 22a to 22d

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring defects of a display device, and more particularly, to a device and method for measuring defects of a display device, which enables accurate and fast detection of defects in a regular array of cells.

2. Description of the Related Art In recent years, various display devices capable of reducing weight and volume, which are disadvantages of cathode ray tubes (CRTs), have been developed. Among them, a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP) and a light emitting diode display (Light Emitting) Diodes Display).

Such display devices are manufactured to include a plurality of cells arranged regularly, and after manufacturing, the display devices undergo a step of measuring defects such as defects through a microscope. First, the entire area of the display device is searched through the microscope in the low magnification state, and as the magnification of the microscope is gradually increased to high magnification, the partial area is searched to measure the defective position of the display device. This method is difficult to measure because the defective part appears small in the low magnification state, and it takes a long time because the display device must be divided and searched by the section in the high magnification state. In addition, such a defect measuring method is difficult to detect the defect precisely because the regular arrangement must be checked with the naked eye and may cause confusion in the human eye recognition due to the regular arrangement of the same pattern.

Accordingly, an object of the present invention is to provide an apparatus and method for measuring defects of a display device, which enables accurate and rapid detection of defects in a regular array of cells.

In order to achieve the above object, the defect measuring apparatus of the display device according to an embodiment of the present invention includes a microscope for photographing the display device; A regular period detecting unit detecting a regular period of the image photographed through the microscope; A copy image generating unit generating a copy image by shifting the image by the regular period; An image processing unit comparing the image and the copy image and detecting a different portion through an exclusive OR; And a display unit for displaying the output of the image processing unit.

The regular period includes an X axis period that is a period in which the gray scale measured on the X axis of the image is repeated, and a Y axis period that is a period in which the gray scale measured on the Y axis of the image is repeated.

The copy image includes a first copy image of shifting the image to one side of the X axis by the X axis period, and a second copy image of shifting the image to the other side of the X axis by the X axis period.

The copy image includes a first copy image in which the image is shifted by one Y-axis period to one side of the Y axis, and a second copy image by shifting the image by the Y-axis period to the other side of the Y axis.

The copy image may include: a first copy image shifting the image by one period of the X axis to one side of the X axis, and shifting the image by one period of the Y axis to one side of the Y axis; A second copy image shifted to the other side of the X-axis by the X-axis period and shifted to the other side of the Y-axis by the Y-axis period; A third copy image shifted to the other side of the X axis by the X axis period and shifted to the one side of the Y axis by the Y axis period; And a fourth copy image which is shifted by the X axis period to one side of the X axis and shifted by the Y axis period to the other side of the Y axis.

The image processor compares the gray level of the image and the copy image to modulate a portion having the same gray level as the first gray level and modulate a portion having a different gray level to the second gray level.

The first gray level is a black value, and the second gray level is a white value.

The microscope photographs the different portions at high magnification, and the display portion displays the different portions photographed at the high magnification.

Method of measuring a defect of a display device according to an embodiment of the present invention comprises the steps of disposing a microscope and the display device; Photographing the entire area of the display device by setting the microscope at a low magnification; Detecting a regular period of the image photographed with the microscope through a regular period detection unit; Generating a copy image by shifting the image by the regular period through a copy image generator; Comparing the copy image with the copy image through an image processing unit and detecting a different portion through an exclusive OR; Displaying an output of the image processor through a display unit; And photographing the different portions by setting the microscope at high magnification.

Other objects and advantages of the present invention will become apparent from the following description of preferred embodiments of the present invention with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 1 to 8.

1 is a view schematically illustrating a failure measuring apparatus of a display device according to an exemplary embodiment of the present disclosure. In the exemplary embodiment of the present invention, a liquid crystal display device (LCD) will be described.

Referring to FIG. 1, a defect measuring apparatus according to an exemplary embodiment of the present invention may include a microscope 4 for photographing an LCD 2 and a computer 14 for measuring a defect area through an LCD image photographed from a microscope 4. It is provided.

The LCD 2 includes a liquid crystal display panel and a backlight unit.

The liquid crystal display panel includes a thin film transistor (TFT) substrate and a color filter substrate. A liquid crystal layer is formed between the TFT substrate and the color filter substrate. In the TFT substrate, the data lines and the gate lines are formed to be orthogonal to each other on the lower glass substrate, and the liquid crystal cells are arranged in a matrix form in the cell regions defined by the data lines and the gate lines. The TFT formed at the intersection of the data lines and the gate lines supplies the data voltage from the data lines to the liquid crystal cell in response to the scan pulse from the gate line. For this purpose, the gate electrode of the TFT is connected to the gate line, the source electrode is connected to the data line, and the drain electrode is connected to the pixel electrode of the liquid crystal cell. The common voltage is supplied to the common electrode facing the pixel electrode. The color filter substrate includes a black matrix and a color filter formed on the upper glass substrate.

The common electrode is formed on the upper glass substrate in the vertical electric field driving method such as twisted nematic (TN) mode and vertical alignment (VA) mode, and the horizontal electric field such as IPS (In Plane Switching) mode and FFS (Fringe Field Switching) mode. In the driving method, the pixel electrode is formed on the lower glass substrate together with the pixel electrode.

The backlight unit includes a lamp and an optical sheet, and is divided into a direct type and an edge type according to the arrangement of the lamp. Taking a direct type backlight unit as an example, a plurality of lamps are formed directly under the liquid crystal display panel, and emit light to irradiate the liquid crystal display panel. As the lamp, a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), and a light emitting diode (LED) are used. The optical member includes a diffusion plate and an optical sheet. The diffusion plate includes a plurality of beads and scatters the light incident through the lamp using the beads so that there is no difference in luminance at the positions of the lamps and the positions of the lamps on the display surface of the LCD panel. do. The optical sheet includes one or more diffusion sheets and one or more prism sheets to uniformly irradiate the light incident from the diffusion plate onto the entire liquid crystal display panel and to fold the path of light in a direction perpendicular to the display surface to the front of the display surface. It serves to condense light.

The microscope 4 captures an image of the LCD 2 and transmits the captured image to the computer 14 through an image transmission standard such as Toolkit Without An Indicated Name (TWAIN). The image transmitted to the computer 14 is displayed through a monitor or the like as shown in FIG. 2, so that the image can be observed without going through a separate eyepiece.

The computer 14 includes a rule period detection unit 6, a copy image generation unit 8, an image processing unit 10, and a display unit 12.

The regular period detection unit 6 measures the gray level on the horizontal axis and the vertical axis of the image taken at low magnification through the microscope 4 and detects the regular period of the image through the repeated period of gray level. Since the display device including the LCD 2 is formed by regularly arranging a plurality of cells, the regular period of the image photographing the display device is usually one cell area.

The copy image generating unit 8 generates a plurality of copy images obtained by shifting the image photographed through the microscope 4 by a regular period detected by the regular period detecting unit 6. In this case, the copy image is an image shifted by one rule period in the horizontal or vertical axis direction, or an image shifted by one rule period in both the horizontal and vertical axis directions.

The image processing unit 10 compares the image photographed through the microscope 4, that is, the original image and the copy image generated by the copy image generating unit 8, and outputs a comparison result using an exclusive OR. Since the copy image is an image shifted by one rule period from the original image as described above, comparing the copy image with the original image compares the cells of the original image with adjacent cells. The portion that is modulated with the first gradation and the gradation is different is modulated with the second gradation. Therefore, the region represented by the second gray scale is an irregular region, that is, an region where defects appear. The first and second gradations are different gradations, respectively, to increase the difference between the first and second gradations in order to increase the visibility of the defective area represented by the second gradations. For example, when the first gray level is a black value, the second gray level may be set to a white value.

The display unit 12 outputs the processing result output from the image processing unit 10 and enlarges and displays the defective area measured by the image processing unit 10 so that the defect can be accurately measured. For this purpose, the microscope 4 is adjusted to high magnification.

3 is a flowchart illustrating a method of measuring a failure of a display device according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the method for measuring a defect according to an exemplary embodiment of the present disclosure includes a step S1 of disposing a microscope and an LCD and a step S2 of capturing the entire area of the LCD by setting the microscope at a low magnification. In the case of a large LCD, even when shooting at a low magnification, the entire area may not be photographed at once, and thus the entire area may be divided into several areas and photographed.

Thereafter, as shown in FIG. 4, the regular period of the captured image is detected (S3).

Referring to Fig. 4, the regular period is detected by measuring the gradations of each of the horizontal axis (X axis) and the vertical axis (Y axis). The measured gradation is repeated with a constant period on each axis, which means a regular period of the image. That is, the rule period includes an X-axis period (Pitch X) and a Y-axis period (Pitch Y), and as described above, one cell 15 becomes a regular period in the LCD.

After the regular period is detected, a copy image is generated in which the original image photographed through the microscope is shifted by the regular period (S4).

The copied images 18a and 18b shown in FIGS. 5A and 5B are images in which the original image 16 is shifted by one X-axis period (Pitch X) to the left and right of the X-axis, in which case the entire area of the original image is Two copy images are created for comparison without missing areas.

The copy images 20a and 20b shown in FIGS. 6A and 6B are images in which the original image 16 is shifted by one Y-axis period (Pitch Y) to the upper side and the lower side of the Y axis. Is generated.

The copied images 22a, 22b, 22c, and 22d shown in FIGS. 7A to 7D are images obtained by shifting the original image 16 on both the X and Y axes. In detail, the copy image 22a shown in FIG. 7A is an image in which the original image 16 is shifted by 1 X-axis period (Pitch X) to the right of the X-axis and 1 Y-axis period (Pitch Y) to the lower side of the Y-axis. The copy image 22b illustrated in FIG. 7B is an image in which the original image 16 is shifted by one X-axis period (Pitch X) to the left of the X-axis and one Y-axis period (Pitch Y) to the upper side of the Y-axis. In addition, the copy image 22c illustrated in FIG. 7C is an image in which the original image 16 is shifted by 1 X-axis period (Pitch X) to the left of the X-axis and 1 Y-axis period (Pitch Y) to the lower side of the Y-axis. The copy image 22d illustrated in FIG. 7D is an image in which the original image 16 is shifted by one X-axis period (Pitch X) to the right of the X-axis and one Y-axis period (Pitch Y) to the Y-axis. In this case, four copy images are generated.

The generated copy images are compared with the original image, and the result of the comparison is subjected to an image processing process output through an exclusive OR (S5).

As described above, in the display device including the LCD, since cells having the same shape are regularly arranged and formed, a portion in which gray levels differ from each other through comparison of adjacent cells means an irregular portion, that is, a defect. Here, using the exclusive OR, the same gray level, that is, the normal area is modulated to the first gray level and the bad area is modulated to the second gray level, can easily measure the portion where the failure occurs.

The image processing result output through the exclusive OR is displayed through the display unit, and the area of the original image corresponding to the defective area shown in the image processing result is enlarged by a microscope set at high magnification and displayed again through the display unit. By viewing the displayed magnified area, the exact defect position and the cause of the defect are measured (S7).

FIG. 8 is a diagram illustrating a result of outputting through an exclusive OR after comparing an original image illustrated in FIG. 4 to a copy image generated by the method illustrated in FIGS. 5A and 5B. In FIG. 8, part A represents a defective area. Since the actual defect (C) present in the original image also appears in the copied images, if the copy image is generated to the left and right sides of the original image as shown in FIGS. 5A and 5B, the actual defect (C) is to the left and right sides of the actual defect (C) position. The same type of defects B and D are to be measured. At this time, the defects (B, D) displayed on the left and right sides of the actual defect (C) may appear due to the copy image whether the defect area (A) is actually a defect appearing in the original image by being magnified by a high magnification microscope as described above. It may be determined whether it is bad.

As described above, the apparatus and method for measuring a defect of a display device according to an exemplary embodiment of the present invention are different from those of observing the entire display device with a microscope in a low magnification state and observing all the details of the display device at high magnification. The defect can be easily measured by observing the entire display device with a microscope and then observing at high magnification only the region where the defect is measured. In addition, the apparatus and method for measuring a defect of a display device according to the present invention generates a copy image by shifting the original image by a regular period, compares the original image with the copy image, and highlights the defective area by using an exclusive OR. It can be measured.

The present invention is another display device in which the same pattern is regularly arranged in addition to the above-described liquid crystal display device, for example, a field emission display (FED), a plasma display panel (PDP) and a light emitting diode display It may be applied to a device (Light Emitting Diodes Display) or the like, and may also be applied to a memory device or the like in which the same pattern is regularly arranged.

As described above, the apparatus and method for measuring a failure of a display device according to the present invention captures an image of a display device having a regular period, and then compares the original image photographed with a copy image shifted by one regular period, and exclusively. By measuring the defective area through the OR, it is possible to accurately and quickly detect the defect in the regular arrangement of the cells.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

Claims (18)

A microscope for photographing the display device; A regular period detecting unit detecting a regular period of the image photographed through the microscope; A copy image generating unit generating a copy image by shifting the image by the regular period; An image processing unit for comparing the image with the copy image and detecting a different portion through an exclusive OR; And And a display unit for displaying the output of the image processing unit. The method of claim 1, The regular period includes an X axis period that is a period in which the gray scale measured on the X axis of the image is repeated, and a Y axis period that is a period in which the gray scale measured on the Y axis of the image is repeated. Defective measuring device. The method of claim 2, The copy image, A first copy image of which the image is shifted by one period of the X axis to one side of the X axis, and And a second copy image which shifts the image by the period of the X axis to the other side of the X axis. The method of claim 2, The copy image, A first copy image of shifting the image to one side of the Y axis by the Y axis period, and And a second copy image which shifts the image by the Y-axis period to the other side of the Y-axis. The method of claim 2, The copy image, A first radiant image which is shifted by the X-axis period to one side of the X-axis and shifted by the Y-axis period to one side of the Y-axis; A second copy image shifted to the other side of the X-axis by the X-axis period and shifted to the other side of the Y-axis by the Y-axis period; A third copy image shifted to the other side of the X axis by the X axis period and shifted to the one side of the Y axis by the Y axis period; And And a fourth copy image shifted to the one side of the X axis by the X-axis period and shifted to the other side of the Y-axis by the Y-axis period. The method of claim 1, And the image processor compares the gray level of the image and the copy image to modulate a portion having the same gray level to a first gray level and modulate a portion having a different gray level to a second gray level. The method of claim 6, And the second gray level is a brighter gray level than the first gray level. The method of claim 6, And the second gray level is a darker gray level than the first gray level. The method of claim 1, The microscope photographs the different portions at high magnification, And the display unit displays different portions photographed at the high magnification. Disposing a microscope and a display device; Photographing the entire area of the display device by setting the microscope at a low magnification; Detecting a regular period of the image photographed with the microscope through a regular period detection unit; Generating a copy image by shifting the image by the regular period through a copy image generator; Comparing the copy image with the copy image through an image processing unit and detecting a different portion through an exclusive OR; Displaying an output of the image processor through a display unit; And And photographing the different portions by setting the microscope at a high magnification. 11. The method of claim 10, Detecting the rule period, Measuring a gray level on the X axis of the image and detecting a repeated period as an X axis period, and Measuring a gray level on the Y axis of the image and detecting a repeated period as a Y axis period. The method of claim 11, Generating the copy image, Generating a first copy image of shifting the image to one side of the X axis by the X axis period, and And generating a second copy image of the image shifted by the period of the X axis to the other side of the X axis. The method of claim 11, Generating the copy image, Generating a first copy image of shifting the image to one side of the Y axis by the Y axis period, and And generating a second copy image obtained by shifting the image to the other side of the Y axis by the Y axis period. The method of claim 11, Generating the copy image, Shifting the image to one side of the X axis by the X-axis period and generating a first copy image shifted to the one side of the Y-axis by the Y-axis period; Shifting the image to the other side of the X-axis by the X-axis period and generating a second copy image shifted to the other side of the Y-axis by the Y-axis period; Shifting the image to the other side of the X-axis by the X-axis period and generating a third copy image shifted to the one side of the Y-axis by the Y-axis period; And And generating a fourth copy image of the image shifted by the X-axis period to one side of the X-axis and shifted by the Y-axis period to the other side of the Y-axis. 11. The method of claim 10, Comparing the image and the copy image by the image processing unit and detecting a different portion through an exclusive OR, And comparing the gray level of the image and the copy image to modulate a portion having the same gray level to a first gray level and modulating a portion having a different gray level to a second gray level. 16. The method of claim 15, And the second gray level is a brighter gray level than the first gray level. 16. The method of claim 15, And the second gray level is a darker gray level than the first gray level. 11. The method of claim 10, And displaying the different portions photographed through the microscope set at the high magnification through the display unit.

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