KR102034042B1 - Method for inspecting the exterior scratch of Flat display panel - Google Patents

Abstract

The present invention relates to an external scratch inspection method of a flat panel display panel that analyzes the positional correlation between candidate regions and detects a predetermined number of candidate regions on the same line as scratch defects. Detecting them; Measuring a vertical distance ρ and an angle θ from a reference point for each of the candidate regions; Mapping by the measured vertical distance [rho] and angle [theta]; And if a predetermined number or more is detected in the same cell as a result of the mapping, determining as a scratch.

Description

Method for inspecting the exterior scratch of Flat display panel}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting flat panel displays, and more particularly, to a method for inspecting scratches having poor connectivity in appearance defects.

In recent years, as the information age has entered, the display field for visually expressing electrical information signals has been rapidly developed, and various flat panel display devices having excellent performance of thinning, light weight, and low power consumption have been developed. Flat Display Device has been developed and is rapidly replacing the existing Cathode Ray Tube (CRT).

Specific examples of such a flat panel display device include a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), and an electroluminescent display device. (Electro luminescence Display Device, ELD) and the like, these are commonly used as an essential component of a flat panel display panel that implements an image, a flat panel display panel has a pair of light emitting or polarizing material layer in between It has a configuration in which a transparent insulating substrate is faced and bonded together.

The dual liquid crystal display converts a change in optical properties such as birefringence, photoreactivity, and light scattering characteristics of a liquid crystal cell into a visual change by applying a voltage to a specific molecular array of the liquid crystal, and converting it into another molecular array. A display device using modulation of light by a liquid crystal cell.

The liquid crystal display includes a liquid crystal panel having a liquid crystal cell, a backlight unit for irradiating light to the liquid crystal panel, and a driving circuit for driving the liquid crystal cell.

The liquid crystal panel is formed such that a plurality of unit pixel regions are defined by crossing a plurality of gate lines and a plurality of data lines. In this case, each pixel area includes a thin film transistor array substrate and a color filter array substrate facing each other, a spacer positioned to maintain a constant cell gap between the two substrates, and a liquid crystal filled in the cell gap.

The liquid crystal panel manufacturing process of such a liquid crystal display device may be divided into substrate cleaning, substrate patterning, alignment layer formation, substrate bonding, liquid crystal injection, and mounting process.

In the substrate cleaning process, foreign substances on the substrates are removed using a cleaning agent before and after patterning the upper and lower substrates.

In the substrate patterning process, the upper substrate is patterned and the lower substrate is patterned. A color filter, a common electrode, a black matrix, etc. are formed on the upper substrate, and signal wirings such as data lines and gate lines are formed on the lower substrate. A TFT is formed at the intersection of the line and the gate line, and a pixel electrode is formed in the pixel region defined by the data line and the gate line so as to be electrically connected to the drain electrode of the TFT.

In the substrate bonding and liquid crystal injection process, an alignment film is applied and rubbed onto the upper and lower substrates, respectively, and then the upper and lower substrates are bonded using a seal material, and the liquid crystal is injected between the two substrates. After encapsulation, cleaning, grinding, and inspection processes are sequentially performed to complete the liquid crystal panel.

The inspection process detects various defects such as line defects, point defects, stain defects, and appearance defects.

Such a liquid crystal panel may cause various defects including scratches on the surface due to defects in materials or errors or mistakes in manufacturing processes. Such defects on the surface may damage the value or appearance of the product. It is desirable to identify and remove products with surface defects during the manufacturing process.

For this purpose, the inspector may use a separate inspection apparatus or visually inspect the surface of an object such as a product with the naked eye, but there is a problem that a lot of manpower and time are consumed. It is common to allow surface inspection of the object to be performed.

In particular, the development of computer equipment includes a visual inspection system for detecting defects on the surface of an object by including a photographing device for photographing the surface of the object and a controller having an analysis algorithm for analyzing a surface image of a predetermined size obtained by photographing the object. Nowadays, it is being used as a standard by the popularization of video and video boards.

In the method of checking the appearance defect (scratch defect), a portion having a significant difference with respect to the normal region is detected as a candidate region, and the long and short ratios of the candidate regions are calculated to classify the elongated candidate region as the scratch defect.

The scratch inspection apparatus and inspection method of a conventional flat panel display are as follows.

1 is a configuration diagram of a scratch inspection apparatus of a conventional flat panel display.

The scratch inspection apparatus of the conventional flat panel display has the work table 2 which positions and supports the flat display apparatus 1 which displays an image, and the flat plate display put on the said work table 2, as shown in FIG. And a camera 3 for photographing the device 1 and an image processor 4 for analyzing scratched images and determining scratch defects.

The inspection method of the scratch inspection apparatus of the conventional flat panel display configured as described above is as follows.

The flat panel display 1 is positioned on the work table 2, and the flat panel display is photographed using the camera 3 to obtain an image. The ROI (region of interset) is extracted by removing unnecessary portions (eg, images of portions other than the flat panel display) from the image photographed by the camera 3.

Noise is removed from the ROI-extracted image, and a candidate region (areas with brightness differences) is detected by binarizing the extracted value to a set value in order to determine a predetermined level value or more as a scratch. Features such as long and short lengths, long and short angles, image statistical information, and location information of the candidate regions are extracted, and the candidate regions having an elongated shape are classified as scratch defects based on the extracted feature information.

However, such a scratch inspection method of the conventional flat panel display has the following problems.

FIG. 2 is an explanatory diagram of an image in which actual scratches are generated, and FIG. 3 is an explanatory diagram of a conventional detection of multiple defective candidate regions.

Conventionally, when the candidate regions have a type that is inferior in connectivity, a partial detection or no detection occurs.

That is, as shown in FIG. 2, when the panel of the flat panel on which the actual scratch is generated is obtained by using a camera, the ROI is extracted, and binarized as described above, as shown in FIG. Can be detected. As such, one scratch is divided into a plurality of defective candidate regions, and features are classified by each defective candidate region without finally performing position correlation analysis between candidate regions around the defective candidate region, thereby finally classifying the defect types. If it is detected as a falling type, it is not judged to be scratch or is judged to be normal.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides an external scratch inspection method of a flat panel display panel which analyzes the positional correlation between candidate regions and detects that a predetermined number of candidate regions exist on the same line as scratch defects. The purpose is.

In accordance with another aspect of the present invention, there is provided a method of inspecting an external scratch of a flat panel display panel, the method including: detecting candidate regions having a difference in brightness from a ROI extracted image; Measuring a vertical distance ρ and an angle θ from a reference point for each of the candidate regions; Mapping by the measured vertical distance [rho] and angle [theta]; In addition, if a predetermined number or more is detected in the same cell as a result of the mapping, the method includes determining that it is a scratch.

The detecting of the candidate regions may include: placing a flat panel display device on the work table, photographing the flat panel display device using a camera, and acquiring an image; and removing unnecessary portions of the image captured by the camera. And extracting the ROI, and detecting candidate regions having brightness differences by binarizing the extracted ROI image.

The mapping of the measured vertical distance ρ and the angle θ may include: the vertical distance ρ and the same angle θ value having the same measured vertical distance ρ and angle θ. It is characterized by mapping candidate regions having a to the same cell.

In the scratch scratch inspection method of the flat panel display panel according to the present invention having the above characteristics has the following effects.

That is, candidate regions having brightness differences are detected in the ROI extracted image, and the vertical distance ρ and the angle θ are measured from the reference point for each of the candidate regions, and the candidates having the same vertical distance ρ and the same angle θ are obtained. If more than a certain number of regions are detected, it is determined as a scratch. Therefore, even if the regions are detected as having a poor connectivity, candidates may be determined as scratch.

1 is a block diagram of a scratch inspection apparatus of a conventional flat panel display
2 is a diagram illustrating an image in which actual scratches are generated
3 is an explanatory view of a conventionally detected image separated into several bad candidate regions;
4 is a flowchart illustrating an external scratch inspection method of a flat panel display panel according to an exemplary embodiment of the present invention.
5 is an explanatory diagram of detection of candidate regions according to an external scratch inspection method of a flat panel display panel of the present invention.
FIG. 6 is a diagram illustrating a configuration in which vertical distances and angles are measured and mapped from reference points of candidate regions according to an external scratch inspection method of a flat panel display panel of the present invention; FIG.

Hereinafter, the appearance scratch inspection method of the flat panel display panel according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

First, also in the present invention, the appearance scratch inspection apparatus of the flat panel display panel has the same configuration as the conventional one. However, the operation of the image processing unit is different from the conventional one. Therefore, description of another inspection apparatus is abbreviate | omitted.

4 is a flowchart illustrating an appearance scratch inspection method of a flat panel display panel according to an exemplary embodiment of the present invention, and FIG. 5 is an explanatory diagram of detection of candidate regions according to the exterior scratch inspection method of a flat panel display panel of the present invention. FIG. 6 is a diagram illustrating a configuration of measuring and mapping vertical distances and angles from reference points of candidate regions according to the scratch scratch inspection method of the flat panel display panel of the present invention.

As shown in FIG. 4, the method for inspecting scratches of the appearance of a flat panel display panel according to the present invention includes the steps of detecting candidate regions (1S), and vertical distance (ρ) and angle (θ) for each candidate region. Step 2S of measuring, Step 3S of mapping by the vertical distance ρ and the angle θ, and determining that the scratch occurs when a predetermined number or more is detected in the same cell as a result of the mapping. It consists of 4S.

This process is described in more detail as follows.

First, the step 1S of detecting candidate regions is as follows.

The flat panel display 1 is positioned on the work table 2, and the flat panel display is photographed using the camera 3 to acquire an image. The ROI (region of interest) is extracted by removing unnecessary portions (eg, images of portions other than the flat panel display) from the image photographed by the camera 3.

The noise is removed from the ROI-extracted image, and binarized to a value set in order to determine a predetermined level value or more from the extracted image as a scratch, as shown in FIG. 5, as shown in FIG. 5. ).

Next, steps (2S) of measuring the vertical distance (rho) and the angle (θ) for each candidate region to step (4S) of determining the scratch will be described.

For each of the candidate regions as shown in FIG. 5, as shown in FIG. 6, the vertical distance ρ and the angle θ are measured from the reference point (2S).

6, candidate regions having the same vertical distance ρ and the same angle θ are mapped to the same cell.

If a predetermined number of candidate regions exist in the same cell in the mapped map as described above, it is determined as a scratch failure.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

Claims (4)

Positioning a flat panel display on a work table and photographing the flat panel display using a camera to obtain an image;
Extracting ROI by removing unnecessary portions from the image photographed by the camera;
In order to remove noise from the ROI-extracted image and to determine a scratch level or more from the extracted image, the ROI-extracted image is thresholded to a set value to detect candidate regions having brightness differences. Steps,
Measuring a vertical distance ρ and an angle θ from a reference point for each of the candidate regions;
Mapping candidate regions having the same vertical distance ρ and the same angle θ to the same cell;
And determining as a scratch when a predetermined number or more of the candidate areas are detected in the same cell in the mapped map. delete delete delete

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