KR101086133B1 - Apparatous for test of liquis crystal display device and method for test of liquid crystal display device using thereof - Google Patents

Abstract

The present invention relates to an autoprobe inspection apparatus for a liquid crystal display panel and an inspection method using the same. The autoprobe inspection apparatus according to the present invention includes a liquid crystal display panel; A line scan CCD camera arranged on said liquid crystal display panel; A display device for displaying defect information of the liquid crystal display panel obtained through the line scan CCD camera; An area scan CCD camera scanning the entire liquid crystal display panel to detect defects; And a polarizing plate formed between the liquid crystal display panel and the area scan CCD camera, wherein the line scan CCD camera moves forward and backward on the liquid crystal display panel to detect light point defects and dark point defects. It is possible to prevent a mistake in class determination that occurs during the operation, and to improve the production capacity by quickly determining the grade of the liquid crystal display panel.

Line Scan CCD Camera, Area Scan CCD Camera, Auto Probe Inspection System

Description

Liquid crystal display panel inspection device and liquid crystal display panel inspection method using the same {APPARATOUS FOR TEST OF LIQUIS CRYSTAL DISPLAY DEVICE AND METHOD FOR TEST OF LIQUID CRYSTAL DISPLAY DEVICE USING THEREOF}

1 is a plan view showing the structure of a general liquid crystal display panel.

Fig. 2A is a schematic block diagram of a liquid crystal display panel inspection apparatus including a line scan CCD camera and an area scan CCD camera of the present invention.

2B is a conceptual diagram showing the operation principle of a line scan CCD camera.

3A is a graph for analyzing defect information collected by a CCD camera.

3B is a plan view showing defect information to be analyzed.

4 is a cross-sectional view showing types of defects existing in a liquid crystal display panel.

5 is a conceptual diagram showing optical characteristics of a defect of a liquid crystal display panel.

Fig. 6 is a sectional view showing an arrangement of an area scan CCD camera and a liquid crystal display panel of the present invention.

7 is a flowchart showing the operation of the liquid crystal display panel inspection apparatus of the present invention.

***** Explanation of symbols for main parts of drawing *****

201: line scan CCD camera 202: liquid crystal display panel

203: data collection means 204: data analysis means                 

205: Display means 601: Area scan CCD camera

401: true defect 402: false defect

602 liquid crystal display panel 603 polarizing plate

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection apparatus for a liquid crystal display device, and more particularly, to an auto-probe test apparatus including a camera for checking defects and determining whether a defect occurs in a liquid crystal display panel and a display using the same. It relates to a defect inspection method of the device.

In general, among the screen display devices for displaying the image information on the screen, the thin film type flat panel display device has been actively researched and developed in recent years due to its light and small size and excellent portability. In particular, liquid crystal display devices have been studied most actively because they have high resolution and fast reaction speeds sufficient to realize moving images.

The liquid crystal display device displays an image by using the optical anisotropy and polarization property of the liquid crystal. That is, when the alignment direction of the liquid crystal molecules having optical anisotropy is adjusted, light is transmitted and blocked according to the alignment direction of the liquid crystal, and an image can be displayed by applying such a phenomenon.

The liquid crystal display device comprises: a liquid crystal display panel in which pixels are arranged in a matrix form; A gate driver and a data driver for driving the pixels are provided.                         

The liquid crystal display panel is filled in a thin film transistor array substrate and a color filter substrate bonded to maintain a uniform cell gap, and a cell gap of the color filter substrate and the thin film transistor array substrate. It consists of the liquid crystal layer.

A common electrode and a pixel electrode are formed on the liquid crystal display panel where the thin film transistor array substrate and the color filter substrate are bonded to apply an electric field to the liquid crystal layer.

Therefore, when the voltage of the image information applied to the pixel electrode is controlled while the voltage is applied to the common electrode, the liquid crystal molecules having dielectric anisotropy are rotated according to the electric field between the common electrode and the pixel electrode. Characters or images are displayed by transmitting or blocking light.

The liquid crystal display device is inspected in the state of the liquid crystal display panel before the gate driver and the data driver are combined to check for defects. Such a test is commonly referred to as an auto-probe test.

1 is an exemplary view showing a schematic planar structure of the liquid crystal display panel.

Referring to FIG. 1, the liquid crystal display panel 100 includes an image display unit 113 in which pixels are arranged in a matrix form, a gate pad unit 114 and data lines connected to gate lines of the image display unit 113. And a data pad unit 115 connected to the data pad unit. In this case, the gate pad part 114 and the data pad part 115 are formed outside the thin film transistor array substrate 101 not overlapping the color filter substrate 102, and the gate pad part 114 is formed from the gate driver. The supplied scanning signal is supplied to the gate lines of the image display unit 113, and the data pad unit 115 supplies the image information supplied from the data driver to the data lines of the image display unit 113.

The thin film transistor array substrate 101 and the color filter substrate 102 are bonded to each other so that a constant cell-gap is maintained by a seal pattern 116 formed on the outer side of the image display unit 113. The liquid crystal display panel 100 is formed.

As described above, the liquid crystal display device is inspected in the state of the liquid crystal display panel 100 before the gate driver and the data driver are coupled to check whether there is a defect.

In order to inspect the liquid crystal display panel 100, needles are contacted to correspond to all the pads of the gate pad part 114 and the data pad part 115, so that the gate lines and the data of the liquid crystal display panel 100 are contacted. By applying a driving signal to the lines, a test pattern is displayed on the liquid crystal display panel 100, and it is checked whether or not a defect occurs from the displayed test pattern. Point defects, line defects, and luminance defects of the liquid crystal display panel 100 are inspected by the test pattern.

However, although the operation of applying the test pattern to the liquid crystal display panel using the auto probe inspection device is automatically performed, the inspection of the test pattern to determine whether the defect is made by the naked eye.

Manual inspection by the operator may cause a defect may occur, and also because the operator visually inspects the very fine pixels in the tension state causes a problem of poor vision or health. Furthermore, in recent years, liquid crystal display panels having finer pixels have been produced according to demands for clearer image quality. In the liquid crystal display panels of such fine pixels, there is a limit to inspection by visual inspection.

It is therefore an object of the present invention to provide an autoprobe inspection apparatus for inspecting defect inspection of a liquid crystal display panel using a CCD camera in the inspection step of the liquid crystal display panel. Another object of the present invention is to provide an autoprobe inspection apparatus capable of distinguishing between a false defect and a true defect detected by the autoprobe inspection apparatus having a CCD camera and a liquid crystal display panel inspection method using the same. do.

In order to achieve the above object, the auto probe inspection device of the present invention includes a liquid crystal display panel; A line scan CCD camera arranged on said liquid crystal display panel; A display device for displaying defect information of the liquid crystal display panel obtained through the line scan CCD camera; An area scan CCD camera scanning the entire liquid crystal display panel to detect defects; And a polarizing plate formed between the liquid crystal display panel and the area scan CCD camera, wherein the line scan CCD camera moves forward and backward on the liquid crystal display panel to detect bright spot and dark spot defect.

In addition, the liquid crystal display panel inspection method using the inspection device comprises the steps of arranging a line scan CCD camera on the liquid crystal display panel; Photographing the liquid crystal display panel by the line scan CCD camera; Displaying defect information using the photographed information; Photographing the liquid crystal display panel by the area scan CCD camera through an area scan CCD camera disposed above the liquid crystal display panel and a rotating polarizing plate formed between the liquid crystal display panel; Displaying information photographed by the area scan CCD camera; And comparing the defect information of the liquid crystal display panel photographed by the area scan CCD camera and the line scan CCD camera, and classifying the types of defects.

When the liquid crystal display panel is completed, the liquid crystal display panel is combined with a driving driver for driving the pixel portion. However, a test process is performed to check whether the LCD panel is defective before being combined with the driving driver.

The test process inspects point defects, line defects, and luminance defects that may exist in the liquid crystal display panel.

The liquid crystal display panel includes a unit pixel arranged in a matrix on a substrate, and a gate line or data line defining a unit pixel or a defect caused by a malfunction such as a thin film transistor for driving the unit pixel or a liquid crystal molecule for driving a pixel. Predecessors due to such defects account for a large part of the defects.

The inspection of such defects is performed by an auto probe inspection apparatus. The auto probe inspection apparatus includes a shelf on which a liquid crystal display panel is placed, and a needle on the pad portion formed at the edge of the liquid crystal display panel is defective, thereby deciding a predetermined value in the liquid crystal display panel. And a pattern generator for applying a pattern of.

When the liquid crystal display panel to be tested is placed on the autoprobe device, the needle of the pattern generator is in contact with the pad portion of the liquid crystal display panel to apply a signal to perform auto probe inspection.                     

The auto probe inspection determines various types of patterns and displays luminance, color implementation, point defects, predecessors, and defects of the liquid crystal display panel. This determination is made while the operator visually inspects the displayed pattern. As the size of the pixel becomes smaller, the manual inspection is limited, and the present invention proposes a method for automating the inspection.

First, when a predetermined pattern is displayed on the liquid crystal display panel by the auto probe inspection device, the surface of the liquid crystal display panel is photographed using a line scan CCD camera.

The photographed data of the liquid crystal display panel is collected by the data collector and undergoes an analysis step of distinguishing only defects. Subsequently, the analyzed data is converted into coordinate values and displayed on the display device so as to correspond to each position of the liquid crystal display panel. In other words, the display device is a map displaying a defect.

However, the defects of the liquid crystal display panel inspected by the line scan CCD camera are false defects due to foreign matters such as true defects present in the liquid crystal display panel and dust present outside the liquid crystal display panel. There may be a problem with everything. In fact, the number of defects detected by the line scan CCD camera is much higher than during visual inspection.

Therefore, another configuration of the present invention distinguishes between true and false defects among the defects detected by the line scan CCD camera, and provides a method for inspecting a liquid crystal display panel through an autoprobe inspection device including the configuration.

The means for distinguishing between the true defect and the false defect further includes an area scan CCD camera capable of capturing the entire liquid crystal display panel, and a polarizing plate formed between the area scan CCD camera and the liquid crystal display panel. do. The polarizer may rotate at a constant speed, and the area scan CCD camera photographs the liquid crystal display panel through the polarizer.

In addition, the defect data of the liquid crystal display panel photographed by the area scan CCD camera is further analyzed and displayed to compare the defect information displayed by the line scan CCD camera to distinguish between true and false defects. do.

Hereinafter, an autoprobe inspection apparatus according to an exemplary embodiment using a line scan CCD camera will be described with reference to FIG. 2A.

Referring to FIG. 2, in the auto probe inspection apparatus of the present invention, a plurality of line scan CCD cameras 201 are disposed above the liquid crystal display panel 202 adjacent to each other. Only one line scan CCD camera 201 may be used, or a plurality of line scan CCD cameras 201 may be used. The line scan CCD camera 201 may have various kinds of photo effective cells for detecting light, such as 2k, 4k, and 8k (k is a thousand units), depending on which line scan CCD camera is used. Multiple or only one scan CCD camera may be used.

Since the photosensitive cell of the line scan CCD camera 201 is finer than each unit pixel of the liquid crystal display panel, the unit cell of the liquid crystal display panel can be divided into several parts and photographed finely.

Therefore, almost all defects present in the liquid crystal display panel can be detected by the line scan CCD camera 201 and the information is analyzed by the data analyzing means 204 via the data collecting means 203. The operation of the data analysis means 204 will be described with reference to FIG. 3A.

Subsequently, the defect information analyzed by the data analyzing means 204 is displayed to coincide with each pixel array of the liquid crystal display panel. That is, the defects are converted into coordinate values and displayed by the display device 205.

Hereinafter, the principle of photographing a defect of the liquid crystal display panel by the line scan CCD camera will be described. The CCD sensor in charge of photographing has a structure that converts a change in the amount of free charge in each cell due to the amount of light into an electrical signal. CCD sensors are largely divided into a photo effective region in which charge is accumulated by an actual amount of light, and a shift register, which serves as a path for sequentially transferring the stored charge. Depending on how each cell is arranged to produce an image, the cells may be divided into an area scan and a line scan.

The area scan method is an arrangement method in which exposure and transmission by one shot are performed in a frame or field unit, and the line scan method is an arrangement method in which exposure and transmission are performed one line at a time.

As a difference between the above schemes, for example, an area scan scheme requires 4 megapixels in order to obtain a frame size of 2048 x 2048, but according to the line scan scheme, only 2k pixels are possible. In the line scan method, a frame having a size of 2048 × 100000 may also be photographed by a scan method.                     

In this regard, the price of the line scan CCD camera is much lower than that of the area scan CCD camera. In addition, by forming a plurality of the line scan type CCD camera in parallel, it is possible to more accurately photograph the unit pixels of the liquid crystal display panel.

For this reason, in the present embodiment, a first scan of the liquid crystal display panel uses a line scan CCD camera. However, the imaging is not limited to using only a line scan CCD camera.

2B illustrates a relationship in which pixel information of a liquid crystal display panel is photographed and transmitted by a line scan CCD camera.

When a portion of the liquid crystal display panel is photographed by the line scan CCD camera, the input light quantity information is converted into an electrical signal in the unit cell 210 and accumulated. The principle in which the amount of light accumulates in charge can be explained by the photoelectric effect theory. That is, when a photon is input, electric charges that receive the energy of the photon are excited, and the unit cell accumulates the charged charge.

Charges accumulated as described above are transferred by shift resistors 211 arranged on both sides of the CCD sensor 220. The analog information transmitted is digitalized by an analog to digital converter (AD convertor). Depending on how many unit cells the CCD sensor has, it can be divided into 2K, 4K, and 8K CCD cameras.

The line scan CCD camera 201 is installed on the upper portion of the liquid crystal display panel 202, and photographs the entire liquid crystal display panel while moving the liquid crystal display panel by moving means (not shown).

Many of the defects appearing on the liquid crystal panel are point defects and line defects. Therefore, when the line scan CCD camera 201 inspects the liquid crystal display panel while advancing, the defect can be inspected while driving the liquid crystal display panel in the black mode. In the black mode, a bright point defect of the liquid crystal display panel is easily detected. In addition, when the line scan CCD camera 201 is reversed, the liquid crystal display panel may be driven in a white mode to detect a dark point.

The bright spot detection when the line scan CCD camera moves forward and the dark spot detection when the reverse scan may be reversed. This is because driving the liquid crystal in the black mode or the white mode is for easily detecting a dark point or a bright point defect.

However, the driving of the liquid crystal display panel may not only be inspected in the black mode or the white mode, but may be divided into a dark background and a light background.

The dark background can range from 0 to 127 gray levels, and the bright background can range from 127 to 255 grain levels.

Each gray level may be divided into n equal parts, and a plurality of images may be taken. That is, by dividing the dark background into three, the photographs may be divided into 90, 180, and 127 grain levels. The same is true for a light background.

Defect information of the liquid crystal display panel collected by the line scan CCD camera is collected by the data collecting unit 203 and analyzed by the data analyzing unit 204.                     

That is, when the information of the CCD camera is displayed for each unit cell information, the bright point defect or the dark point defect forms a specific peak of the data.

3A shows a defect distribution of the liquid crystal display panel shown by the data analyzing means. The peaks in FIG. 3A represent dark spots or bright spots, respectively.

Defect information of the liquid crystal display panel analyzed by the data analyzing means 204 is converted into coordinate values and displayed on the display device. That is, the data value is coordinated to display at a glance which position of the defect exists in the liquid crystal display panel.

3B shows the distribution of the defects 302 by the display means 301. Reference numeral 303 denotes an enlarged portion of the defect so as to discriminate the defective pixel of the liquid crystal display panel.

However, the defects inspected by the line scan CCD camera may include both a true defect existing in the liquid crystal display panel and a virtual defect caused by foreign matter on the outside of the liquid crystal display panel, that is, the surface. Since the defects existing on the upper part of the liquid crystal display panel cannot be treated as a defect of the liquid crystal display panel, it is a problem to classify the defect.

The area scan CCD camera of the present invention provides a method for classifying the two defects and a defect classification step used in the method.

4 and 5 will be described with reference to FIGS. 4 and 5 to classify true defects existing in the liquid crystal display panel and virtual defects existing in the outside of the liquid crystal display panel.                     

Internal defects inside the liquid crystal display panel may be caused by malfunction of the thin film transistors driving the unit pixels, disconnection of gate lines or data lines, misalignment and malfunction of liquid crystals, and the like. In addition, defects outside the liquid crystal display panel are mainly caused by foreign matter, that is, dust or the like, which occurs while the liquid crystal display panel is handled in the air.

However, defects inside the liquid crystal display panel are usually fixed inside the panel and thus do not scatter light traveling from the backlight. However, foreign matters and the like present on the surface of the liquid crystal display panel may scatter backlight light traveling from below the liquid crystal display panel. That is, the linearly polarized light passing through the polarizing plate and the liquid crystal display panel may be scattered by a foreign material present on the surface of the liquid crystal display panel or may show a change in phase.

As described above, the present invention focuses on the fact that defects existing inside and outside the liquid crystal display panel exhibit different reactions to light, and distinguishes them as true defects using the difference.

FIG. 4 shows a true defect 401 inside the liquid crystal display panel and a false defect 402 on the surface of the liquid crystal display panel, and FIG. 5 shows the response that the defect exhibits to light, i. While not scattering, false defects show scattering of light, indicating a phase change.

Referring to FIG. 6, a means for discriminating the kind of defects of the liquid crystal display panel may include an area scan CCD camera 601 for photographing the liquid crystal display panel, and an area scan CCD camera 601 between the liquid crystal display panel 602. A polarizing plate 603 is formed. The polarizer 603 may be located in front of the lens of the area scan CCD camera. In addition, the polarizer 603 is configured to rotate at a constant speed or angle unit.

Using an area scan CCD camera as a camera for capturing the liquid crystal display panel is firstly, since the area scan camera has a square pixel structure, it is suitable for capturing a square liquid crystal display panel, and secondly, a photosensitive cell of mega units or more. This is because it is possible to take pictures even in a liquid crystal display panel having mega pixels, and thirdly, it is suitable for directly photographing the entire liquid crystal display panel and comparing it directly with defect information photographed by a line scan CCD camera. . The area scan CCD camera may use a highly integrated CCD sensor having a pixel number of mega units or more.

The principle of a method for distinguishing between true and false defects using the area scan CCD camera will be described.

While rotating the polarizer 603 at a constant angle, the area scan CCD camera 601 captures the liquid crystal display panel 602 through the polarizer 603.

The photographing may be performed by the area scan CCD camera 601 while rotating the polarizing plate 603 by 5 degrees or 10 degrees.

After rotating the polarizing plate 603 at a predetermined angle and photographing the liquid crystal display panel through the area scan CCD camera 601, defects in which the phase change is caused by foreign matter on the surface of the liquid crystal display panel are filtered by the polarizing plate to display the display device. May appear flashing in. That is, a dark spot or bright spot appearing in the photographing using the polarizing plate 603 rotated by 5 degrees may not appear in the photographing using the polarizing plate rotated by 10 degrees.

This blinking defect is a defect represented by a false defect present on the surface of the liquid crystal display panel. Therefore, true defects can be found by comparing defect information taken by an area scan CCD camera with defects inspected by a line scan CCD camera.

Therefore, referring to FIG. 7, the method for detecting a defect of a liquid crystal display panel according to the present invention is mounted on the autoprobe inspection apparatus (S101).

Subsequently, a line scan CCD camera is arranged on the liquid crystal display panel (S102). After arranging the line scan CCD camera, a pattern having a predetermined gray level is displayed on the liquid crystal display panel (S103), and the liquid crystal display panel is scanned with the line scan CCD camera (S104). In this case, when the LCD panel moves forward or backward, different gray levels may be displayed on the flat panel.

Subsequently, defect information is collected by repeating the gray level adjustment and the scan operation of the liquid crystal display panel such that the gray level reaches the Nth gray level.

Next, the defect information is analyzed by the scan information (S105), and the coordinate value is displayed by the display device (S106).

Next, the polarizing plate formed on the upper portion of the liquid crystal display panel and the area scan CCD camera are aligned (S107), and the liquid crystal display panel is photographed by the area scan CCD camera (S108).

The polarizing plate repeats the rotation of the polarizing plate and the imaging of the area scan CCD camera until it reaches an N angle which is arbitrarily determined to rotate by a predetermined angle unit.

False information is analyzed and image is displayed using the obtained information (S109).                     

Subsequently, a true defect is found by comparing an image displaying the information collected from the area scan CCD camera with an image displayed from the information collected from the line scan CCD camera (S110).

It is most important to produce a liquid crystal display panel without defects, but in some cases, defects below a certain degree can be tolerated. In addition, since the grade of the liquid crystal display panel is determined according to the number of true defects, it is also very important to detect the number of defects in the liquid crystal display panel.

The present invention provides a means and a method for distinguishing between true defects and false defects in a completed liquid crystal display panel, thereby making it possible to prevent a mistake in classifying a good product as a defective product. In addition, by using a CCD camera having a resolution and scanning capability that is superior to the naked eye, analyzing defects by the naked eye of the prior art can not only protect the health of the operator, but also improve the liquid crystal display panel rating. Errors in classification can be prevented. In addition, it is possible to quickly determine the grade of the liquid crystal display panel, thereby improving productivity.

Claims (16)

A liquid crystal display panel; A line scan CCD camera arranged on said liquid crystal display panel; A display device for displaying defect information of the liquid crystal display panel obtained through the line scan CCD camera; An area scan CCD camera scanning the liquid crystal display panel to detect defects; And a polarizing plate formed between the liquid crystal display panel and the area scan CCD camera. And the line scan CCD camera moves forward and backward on the liquid crystal display panel to detect bright spot and dark spot defect. The liquid crystal display panel inspection apparatus according to claim 1, wherein the line scan CCD camera is composed of a plurality of line scan CCD cameras arranged in a line. The display apparatus according to claim 1, further comprising: analysis means for converting defect information of the liquid crystal display panel collected from the line scan CCD camera into coordinate values for analyzing the display unit; It further comprises a liquid crystal display panel inspection device. delete 2. The liquid crystal display panel of claim 1, wherein the line scan CCD camera detects a bright point while advancing when the liquid crystal display panel is a dark gray level and detects a dark spot by reversing when the liquid crystal display panel is a light gray level. Inspection device. 6. The liquid crystal display panel inspection apparatus according to claim 5, wherein the dark gray level is 0 to 127 gray and the light gray level is more than 127 to 255 gray. 7. The liquid crystal display panel inspection of claim 6, wherein the line scan CCD camera detects a bright point while advancing when the liquid crystal display panel is in a black mode, and detects a dark spot while retreating when the liquid crystal display panel is in a white mode. Device. The liquid crystal display panel inspection apparatus according to claim 1, wherein the defect includes a defect due to a foreign substance formed on a surface of the liquid crystal display panel and a defect inside the liquid crystal display panel. The liquid crystal display panel inspection apparatus according to claim 1, wherein the polarizing plate is rotated. 10. The method of claim 9, wherein the foreign material formed on the surface of the liquid crystal display panel and the defects present inside the liquid crystal display panel are compared with defect information photographed while rotating the polarizer and defect information photographed by the line scan CCD camera. Liquid crystal display panel inspection apparatus, characterized in that divided by. Arranging a first CCD camera on the liquid crystal display panel; Scanning the liquid crystal display panel with the first CCD camera; Displaying defect information collected by the first CCD camera; Photographing the liquid crystal display panel through a polarizing plate with a second CCD camera formed on the liquid crystal display panel; Displaying defect information collected by the second CCD camera; And Comparing defect information displayed by the first CCD camera with defect information displayed by the second CCD camera to determine whether the defect is true, And the first CCD camera is a line scan CCD camera, and the second CCD camera is an area scan CCD camera. delete The method of claim 11, wherein photographing the liquid crystal display panel comprises: Advancing the first CCD camera when the liquid crystal display panel is on a dark background; And reversing the first CCD camera when the liquid crystal display panel is on a bright background. The method of claim 13, wherein the bright spot of the liquid crystal display panel is detected by photographing when the first CCD camera is advanced, and the dark spot of the liquid crystal display panel is detected by photographing when the first CCD camera is backward. LCD panel inspection method. 12. The method of claim 11, wherein the second CCD camera photographs the liquid crystal display panel while the polarizer is rotated at a predetermined angle. 12. The method of claim 11, wherein the defects photographed by the second CCD camera include false defects that flicker by the rotation of the polarizer and true defects that do not flash.

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