KR20070076711A - Method for defect inspection in flat-panel display and apparatus - Google Patents

Abstract

A method and an apparatus for inspecting defects in a flat panel display are provided to easily detect dot defects in a pixel region by using image information extracted during the optical inspection of an FPD(Flat Panel Display). A method for inspecting defects in a flat panel display includes the steps of extracting image information of a pixel region(102), dividing the extracted image into at least one pixel region according to pixel design characteristics(104), searching and selecting reference image similar to the image information(106), overlapping the image information with the reference image(108); and extracting defects existing in the image information(110). The pixel region is divided into lines and boundary regions of the lines.

Description

Method for defect inspection in Flat-panel display and Apparatus

1 is a block diagram of a FPD defect inspection apparatus according to an embodiment of the present invention.

2 is a flow chart of a flat panel display defect inspection method of the present invention.

3 is an exemplary diagram illustrating a defect inspection process of FIG. 2;

4 illustrates a state in which a pixel region is defined by a line boundary in accordance with the present invention.

<Explanation of symbols for the main parts of the drawings>

1: Flat panel display (FPD) 10: Camera

20: control logic section 22: graphics program

24: pattern processing section 26: memory

30: memory

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat-panel display (FPD). In particular, the present invention relates to a flat-panel display defect inspection that checks the position of a defect area and whether or not a defect occurs by using image information extracted during optical inspection of the FPD. A method and apparatus are disclosed.

The demand for display is increasing according to the development of information and communication technology and the demand of diversified information society, and as the display device, compactness, energy saving, etc. instead of the cathode-ray tube (CRT) device, which is conventionally used as most display devices. According to the needs of the FPD, a flat panel display device is being developed. Commonly used FPDs include electroluminescent display (ELD), liquid crystal display (LCD: TFT-LCD, TN / STN), plasma display panel, organic EL, and the like.

In order to maintain the stable quality of these FPDs, the development of materials, the development of processes, etc. are also important, but there should be no defects in panels such as glass or plastic used for manufacturing. As a method of inspecting the defect of the panel for FPD, the method of irradiating light to the panel surface and a defect of the panel surface from the optical change of the irradiated light is used normally. That is, the light emitted from the light source is sequentially irradiated to the FPD panel, which is a test object, through a path such as a mirror / lens / liquid crystal plate, and the inspector determines whether there is a defect such as a scratch or a stain.

However, when the brightness of the light is unstable, there is a problem in that it is not possible to accurately determine the presence or absence of defects due to uneven brightness in the FPD panel.

In addition, a method of automatically inspecting a defect of the FPD panel using a low resolution camera is also used. However, when the image of the FPD panel is taken / analyzed by the low resolution camera, inspection of all the pixels requires a lot of inspection time, which is insufficient. It was difficult to detect. In the case of using the camera, in the end, it is only an inspection method that the inspector visually confirms it. Therefore, there is generally no significant difference from performing an FPD by visual inspection. The visual inspection also has a problem in maintaining a certain quality because the inspection criteria may vary depending on the skill of the operator, subjective judgment or emotion.

Accordingly, an object of the present invention is to provide a flat panel display defect inspection method and apparatus for inspecting the defect area / defect presence of the FPD by comparing the image information extracted during the optical inspection of the FPD with the reference image information.

According to an aspect of the present invention, there is provided a flat display defect inspection method of the present invention, the method comprising: extracting image information of a pixel region, dividing the image information into one or more pixel regions according to the pixel design characteristics, and the image And searching for and selecting a reference image similar to the information, overlapping the image information with the reference image, and extracting a defect present in the image information. do.

In the reference image search / selection step, it is preferable to select a reference image having the highest similarity value by a similarity algorithm among a plurality of reference images.

The pixel region is divided into a figure region or a boundary region between a line and a line, which is a polygon or an irregular closed curve.

The overlap of the image information and the reference image uses a correlation value or a one-dimensional projection result value.

Each pixel area is given a different or identical label.

Flat display defect inspection apparatus of the present invention for achieving the above object, a graphical work tool for dividing the image information of the extracted pixel into one or more pixel areas, search for a reference image similar to the image information divided by the area / A control logic unit having an image search / selection tool for selecting, an image matching tool for automatically overlapping the selected reference image and the extracted image information on one screen, and a defect extraction tool for extracting defects from the extracted image information It is characterized by including the technical features.

It further comprises a memory for storing one or more of the reference image.

The pixel region is divided into a figure region or a boundary region between a line and a line, which is a polygon or an irregular closed curve.

The pixel area is provided with different or identical labels.

The present invention having the configuration as described above, it is possible to easily inspect the presence of the defect and the position where the defect occurs through the image information extracted during the optical inspection of the FPD.

Hereinafter, with reference to the accompanying drawings a preferred embodiment of a method for inspecting a defect during the optical inspection of the FPD in accordance with the present invention will be described in detail.

1 is a block diagram of a FPD defect inspection apparatus proposed to explain the flat display defect inspection method of the present invention.

Referring to the drawings, the FPD panel 1 is fixed to the panel fixing unit 3, and the camera 10 is mounted above the FPD panel 1 vertically. The camera 10 may be moved back, front, left, and right by the X-axis motor 14 and the Y-axis motor 16 to capture a predetermined portion of the FPD panel 1 to obtain image information. A driving unit 18 for driving control of the X-axis motor 14 and the Y-axis motor 16 is provided.

A condition for driving the driving unit 18 is set to move the camera 10 to a designated position, and the image X (referred to as a reference image) of the unit structure region provided by the user in advance and the camera 10 are provided. The control logic unit 20 is provided to compare the image information Y photographed by the PPD panel 1 and determine whether there is a defect in the FPD panel 1.

The control logic unit 20 includes a graphic work tool 21 for dividing / displaying the image information Y into a plurality of graphic information areas, and the image information Y displayed by the graphic work tool 21. And an image search / selection tool 22 for searching and comparing the reference image X having high similarity. And an image matching tool 23 for overlapping the selected reference image X and the image information Y, and a defect extraction tool 24 for extracting defects from the image information Y. The control logic unit 20 is provided as one program, and includes a photoshop, a CAD program, and the like as a program capable of general graphic work. Accordingly, the graphic program of the present invention is not limited to any particular program.

In addition, the image search / selection tool 22 is provided with a similarity algorithm for searching the reference image X having the figure area information having a high similarity with the figure area information of the image information Y. In addition, the image matching tool 23 allows the two images (X, Y) to match exactly using a correlation value.

The memory 25 in which the reference image X is stored is provided. At least one reference image having a different area pattern is preferably stored in the memory 25 so that the image search / selection tool 22 detects a reference image having a high similarity with the image information Y.

Reference numeral 30 denotes a monitor that displays the reference image X and the image information Y. The monitor 30 may selectively display menus for the tools 21 to 24 of the control logic unit 20.

On the other hand, the reference image (X) refers to an image in which no defect exists. The reference image (X) is also divided into a plurality of graphic information areas as described above, and the graphic information area is divided into several areas or randomly divided into a plurality of areas according to pixel design characteristics. Determined area information. In the present embodiment, the area is composed of polygons or irregular closed curves of triangles or more.

Next, the flat panel display defect inspection method of the present invention according to the configuration as described above in detail.

In step 100, when light of a certain intensity is irradiated from a light source (not shown) to inspect a defect of the FPD, the control logic unit 20 controls the camera 10 through a control direction of the driving unit 18 in a predetermined direction. The pixel area of the FPD panel 1 is photographed while moving to. The pixel region image information Y photographed by the camera 10 is temporarily stored in a buffer (not shown) by the control logic unit 20 and displayed on the monitor 30 so that it can be visually confirmed. step).

Once the image information Y for the pixel region is displayed on the monitor 30, the user draws the figure region using the graphic work tool 21 on the image information Y as in step 104. . The figure area may be set to a plurality of areas for one pixel or a plurality of pixels. In addition, it is preferable that the figure area is designated based on information in which the area is divided to some extent according to the pixel design characteristics of the FPD panel 1 rather than drawn by the user arbitrarily.

As described above, when a plurality of figure regions are determined for the image information Y, a label for identifying the figure region is assigned to each figure region. The delimiter setting is for easily indicating in which region a defect occurred at the end of the defect inspection of the present invention.

After the graphic area tool has completed the graphic area information operation on the image information Y, the image search / selection tool 22, the image matching tool 23, and the defect extraction tool 24 will be described later. Defects are automatically extracted according to the processing routine.

First, in step 106, the image search / selection tool 22 accesses the memory 26 to search for a reference image X having figure area information having a high similarity to the figure area information of the image information Y. do. The memory 26 stores one or more reference images represented by figure area information, and the image retrieval / selection tool 22 uses image information Y for each reference image X through a similarity algorithm known in the art. ), Respectively. The reference image X having the most similar figure area information is searched and selected.

In this case, if similar figure area information is not searched in the search operation of the image search / selection tool 22, the reliability is deteriorated in defect inspection. Therefore, the control logic unit 20 displays an error message on the monitor 30. can do. Alternatively, the user may separately receive the reference image X similar to the figure area information of the image information Y and proceed with the defect inspection.

In addition, when searching the reference image X having a high similarity, the defect inspection operation is stopped even when the reference image X having a predetermined value or less is searched by the similarity algorithm. For example, if the level is set to be searched by the similarity algorithm only when the level value is 80% or more, search / select the searched reference image X only when the level value is 80% or more, and when the value is lower than that, the defect inspection operation is stopped or The reference image as described above is separately provided and executed.

When the reference image X similar to the figure region information of the image information Y is searched / selected according to the similarity test, the image matching tool 23 performs the reference image X and the image information ( Y) is overlapped on the monitor 30 (see FIG. 3). The overlapping of the reference image (X) and the image information (Y) at the same coordinates is performed using a correlation value. For example, a correlation value is extracted as a result of correlation analysis to match the two images (X, Y).

When the two images (X, Y) are matched and displayed on the monitor (30) by the image matching tool (23), the defect extraction tool (24) checks whether the image information (Y) is defective. As the inspection proceeds, if there is no defect in the image information Y, no display appears on the screen.

However, if a point defect or the like occurs in a certain figure area according to the comparison of the reference image X and the image information Y, the defect extraction tool 24 displays the area where the defect has occurred on the monitor 30. (Step 110). For example, according to the exemplary embodiment of FIG. 3, a point defect is generated in a region 'C' as an example. Accordingly, it is easy to know which part of the region of the FPD panel 1 has a defect.

Meanwhile, in the above-described embodiment, the image photographed by the camera 10 of the FPD panel 1 is divided into a figure area to check whether a defect occurs, but the area is divided by a simple straight line according to the pixel design. Defects can be inspected (FIG. 4).

4 illustrates a state in which pixel region image information Z overlaps with reference image X. FIG. Similarly, when the pixel area image information Z photographed by the camera 10 is displayed on the monitor 30 (step 120), the user can use the graphic work tool 21 one-dimensionally only in the horizontal and vertical directions. Specify an area (step 122). This may correspond to the pattern of the pixel region being repeatedly configured so that the region can be divided by the line and the boundary of the line. Of course, even a simple pixel area may be designated as the above-described figure area information without specifying the area in one dimension.

If pixel area information is specified in the monitor 30, the user assigns a separator to the area. After that, the control logic unit 20 performs a process of automatically checking whether the defect of the image information Z is compared with the reference image X stored in the memory 25, and the process is performed. It proceeds similarly to the defect detection for the above-described figure region information. That is, referring back to FIG. 2, as in steps 124 and 126, the image search / selection tool 22 may have a reference image X having line region information that is highly similar to the line region information of the image Z. Is detected from the memory 25. The image matching tool 23 overlaps the detected reference image X and the image Z. Defects are then extracted by the defect extraction tool 24, which shows that there are defects in the 'D * B' pixel region.

As described above, the present invention described in the above embodiment has an advantage that it is easy to know in which area of the pixel the point defect exists when the point defect exists in the pixel which is the unit structure constituting the FPD.

As described in detail above, according to the present invention, it is possible to easily detect specific defects such as point defects existing in the pixel region by using image information extracted during FPD optical inspection.

In addition, by allowing the user to easily identify in which region of the pixel the singular defect is located, there is an effect that the response according to the defect detection can be quickened.

Claims (12)

Extracting image information of the pixel region; Dividing the image information into one or more pixel regions according to the pixel design characteristics; Searching / selecting a reference image similar to the image information; Overlapping the image information with the reference image, and And extracting a defect present in the image information. The method of claim 1, The reference image search / selection step, A flat panel display defect inspection method comprising selecting a reference image having the highest similarity value by a similarity algorithm among a plurality of reference images. The method of claim 1, And the pixel area is divided into a graphic area that is a polygon or an irregular closed curve. The method of claim 1, The pixel area, Flat display defect inspection method characterized in that divided into a line and a boundary area of the line (line). The method according to claim 1 or 3, The overlap of the image information and the reference image, Flat display defect inspection method characterized in that using the correlation value (Correlation Value). The method according to claim 1 or 4, The overlap of the image information and the reference image, A flat panel display defect inspection method characterized by using a one-dimensional projection result value. The method according to claim 3 or 4, Flat panel display defect inspection method, characterized in that the pixel area is given a different or the same label. Graphical work tools that divide the image information of the extracted pixels into one or more pixel regions, An image search / selection tool for searching / selecting a reference image similar to the area-divided image information; An image matching tool for automatically overlapping the selected reference image and the extracted image information on one screen; and And a control logic unit having a defect extraction tool for extracting defects from the extracted image information. The method of claim 8, And a memory for storing at least one of said reference images. The method of claim 8, The pixel area, A flat panel display defect inspection apparatus, characterized in that the figure is a polygonal or irregular closed curve. The method of claim 8, The pixel area, A flat panel display defect inspection apparatus, wherein the flat display is present in a boundary region between a line and a line. The method according to claim 10 or 11, wherein And a label is provided in the pixel area.

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