KR20060071674A - Method for detecting bad pixels of liquid crystal display - Google Patents

Abstract

A test method of a liquid crystal display device for detecting pixel defects is provided. The test method of the liquid crystal display for detecting pixel defects includes a first region including dots in (odd rows and odd columns), a second region including dots in (odd rows and even columns), (even rows and odd rows). Providing a liquid crystal panel comprising a third region comprising dots of a column) and a fourth region comprising dots of (even rows, even columns), the first and fourth regions representing a predetermined color and The second and third regions represent black, the first and fourth regions represent black, and the second and third regions represent a predetermined color.

Liquid crystal display, test, dot off, high dot

Description

Method for detecting bad pixels of liquid crystal display

1 is a block diagram of a tester of a liquid crystal display according to an exemplary embodiment of the present invention.

2 is a perspective view of a probe unit and a liquid crystal panel of the tester of the liquid crystal display according to the exemplary embodiment of the present invention.

3A and 3B are conceptual views of a liquid crystal panel for explaining a test method of a liquid crystal display according to a first embodiment of the present invention.

4A and 4B are conceptual views illustrating a liquid crystal panel for explaining a test method of a liquid crystal display according to a second exemplary embodiment of the present invention.

5A and 5B are conceptual views of a liquid crystal panel for explaining a test method of a liquid crystal display according to a third exemplary embodiment of the present invention.

6A and 6B are conceptual views of a liquid crystal panel for explaining a test method of a liquid crystal display according to a fourth exemplary embodiment of the present invention.

 (Explanation of symbols for the main parts of the drawing)

1: tester of liquid crystal display 10: control unit

20: pattern storage unit 30: signal generator                 

40: probe unit 50: liquid crystal panel

60: detector

The present invention relates to a test method for a liquid crystal display device for detecting pixel defects, and more particularly, to provide a test method for a liquid crystal display device for detecting pixel defects with high reliability.

A liquid crystal display (LCD) includes a liquid crystal layer having dielectric anisotropy in which the arrangement direction is changed by a voltage applied from the outside. The liquid crystal display device displays an image such as letters, numbers, arbitrary icons, etc. by applying a voltage to the liquid crystal layer, and adjusting the intensity of the voltage to adjust the transmittance of light passing through the liquid crystal layer.

Liquid crystal displays are representative of flat panel displays (FPDs), and have advantages such as small size, light weight, and low power consumption compared to cathode ray tubes. Therefore, the liquid crystal display device is widely applied to the general industry, for example, the computer industry, the electronic industry, the information and communication industry, etc. due to such unique advantages. In addition, the liquid crystal display device has been applied to various fields such as a display device of a portable computer, a monitor of a desktop computer, and a monitor of a high-definition video device.

The liquid crystal display includes a liquid crystal panel composed of a TFT substrate and a color filter substrate, an integrated circuit (IC) for providing a control signal to display a predetermined image on the liquid crystal panel, and a backlight for backlighting the liquid crystal panel. Unit (Back Light Unit; BLU) and the like. Here, a process of manufacturing a liquid crystal panel using a glass mother substrate is briefly described.

A sealant is printed along the edge of the TFT substrate or color filter substrate, and then the two glass mother substrates are aligned and attached to each other. The TFT substrate and the color filter substrate are separated from the glass mother substrates by cutting along the cutting schedule lines appearing on the two glass mother substrates. After that, the liquid crystal is injected into the space formed between the TFT substrate and the color filter substrate due to the sealant, and the liquid crystal injection port is completely sealed to prevent the liquid crystal from leaking out.

The liquid crystal panel thus manufactured is subjected to a plurality of operating characteristics tests at the time of shipment. In particular, the gross test refers to determining an operating characteristic of a liquid crystal panel and a defect of dots / pixels in the same environment as a module in which the backlight unit and the driving ICs are assembled. Hereinafter, a dot is described as a unit expressing one mixed color by juxtaposing mixing of pixels such as R (red), G (green), and B (blue).

In the conventional gross test, mainly R, G, B, and W (white) patterns are used to determine whether a dot / pixel is defective. For example, in the W pattern, an off dot may appear darker than other dots around it, and thus may be detected as a bad dot. However, in recent years, as the resolution becomes higher and the size of the pixel becomes smaller, it becomes difficult to find a defective dot / pixel. This is because the defective dot is covered by the color represented by the adjacent normal dot.

An object of the present invention is to provide a test method of a liquid crystal display device for detecting a pixel defect having high reliability.

The technical problem of the present invention is not limited to the technical problem mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

According to a test method of a liquid crystal display according to a first exemplary embodiment of the present invention, the dots of a first region including (odd rows and odd columns) and dots of (odd rows and even columns) may be obtained. Providing a liquid crystal panel comprising a second region comprising, a third region comprising dots of (even rows, odd columns), and a fourth region comprising dots of (even rows, even columns), first and The fourth region representing a predetermined color and the second and third regions representing black, the first and fourth regions representing black, and the second and third regions representing a predetermined color. do.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and only the embodiments are to make the disclosure of the present invention complete, and the general knowledge in the technical field to which the present invention belongs. It is provided to fully convey the scope of the invention to those skilled in the art, and the invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

1 is a block diagram illustrating a tester of a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the tester 1 of the liquid crystal display according to the exemplary embodiment may include a controller 10, a pattern storage unit 20, a signal generator 30, a probe unit 40, and a detector ( 60).

The controller 10 controls a plurality of components installed in the tester 1 of the liquid crystal display. For example, although not shown in the drawing, the liquid crystal panel 50 is adsorbed using a vacuum to be loaded into the probe unit 40, or the loaded liquid crystal panel 50 is aligned with the probe unit 40. Control the operation of the back. In particular, the controller 10 loads the pattern information stored in the pattern storage unit 20 and provides a predetermined control signal to the signal generator 20.

The pattern storage unit 20 stores a plurality of pattern information to be used in a test process of the liquid crystal display, and mainly uses a ROM (Read Only Memory). The plurality of pattern information may include, for example, a 64 gradation pattern (RGB) of a residual pattern and a black pattern for testing an afterimage defect, and a red (R), green (G), and blue (B) pattern for testing a driving defect. H / V 64 gray), and R, G, B, and W (White) patterns for detecting off dots.

In particular, the pattern storage unit 20 according to an embodiment of the present invention includes an area including dots of off dots (odd rows, odd columns), dots of (even rows, even columns) and (odd rows, even columns). ) Further includes first pattern information (see 51a and 51b of FIG. 3) in which an area including dots of () and dots of (even rows, odd columns) alternately displays a predetermined color.

The apparatus further includes second pattern information (see 53a and 53b of FIG. 5) indicating a predetermined color by alternately including an area including dots of odd rows and an area including dots of even rows. The apparatus further includes third pattern information (see 54a and 54b of FIG. 6) indicating a predetermined color by alternately including an area including dots of odd columns and an area including dots of even columns. .

The signal generator 30 receives a predetermined control signal from the controller 10 and provides a predetermined driving signal to the probe unit 40. In detail, a gate signal such as a gate on / off signal is sequentially provided to the gate line of the liquid crystal panel, and a data signal such as a gray voltage corresponding to the pattern information of the pattern storage unit 20 is provided to the data line. Hereinafter, the gate signal and the data signal are collectively referred to as driving signals.

The probe unit 40 is a device for applying a driving signal to the liquid crystal panel 50. The probe unit 40 includes a plurality of probe pins, which are in 1: 1 contact with the input pads of the liquid crystal panel 50.

The detection unit 60 detects an operating characteristic of the liquid crystal panel 50 displaying an image according to a driving signal applied through the probe unit 40. In addition, a separate comparison unit (not shown) may be provided to determine whether there is a defect by comparing the result detected by the detection unit 60 with a pre-stored reference result.

In general, patterns used to determine whether a dot / pixel is defective are R (red), G (green), B (blue), and W (white) pattern. For example, to determine whether the pixel representing R is defective, all the dots of the liquid crystal panel 50 express R. At this time, since the defective pixel cannot express R and becomes an off dot, it becomes dark compared with other dots around. However, as the resolution becomes higher recently, it is difficult to determine whether or not the defective dot is covered by the color represented by the adjacent normal dot.

Therefore, the tester 1 of the liquid crystal display according to the exemplary embodiment of the present invention may include, for example, an area including dots of off dots (odd rows and odd columns) and dots of (even rows and even columns) and ( A liquid crystal panel includes a first pattern (see 51a and 51b of FIG. 3) in which an area including dots of odd rows and even columns and dots of (even rows and odd columns) alternately displays a predetermined color. To apply. In this manner, four dots adjacent to one dot representing R can prevent black from being covered by defective dots by adjacent normal dots. This will be described later in detail with reference to FIGS. 3A to 5B.                     

2 is a perspective view illustrating a probe unit and a liquid crystal panel of the tester of the liquid crystal display according to the exemplary embodiment of the present invention.

Referring to FIG. 2, the liquid crystal panel 50 includes a TFT substrate 55, a color filter substrate 56, a liquid crystal (not shown), a signal line 57, and input pads 58.

Although not shown in the figure, the TFT substrate 55 includes a plurality of gate lines, data lines, switching elements, and pixel electrodes when viewed in an equivalent circuit. The gate line extends in a row direction to transmit a gate signal, and the data line extends in a column direction and transmits a data signal.

A switching element having amorphous silicon or polysilicon as a channel layer is formed at an intersection point of a gate line and a data line, and a transparent pixel electrode is connected to an output terminal of the switching element. In general, a transparent pixel electrode is formed using indium tin oxide (ITO) or indium zinc oxide (IZO). The transparent pixel electrode forms a potential difference between the reference electrode on the color filter substrate and adjusts the arrangement of liquid crystals to express a desired image.

Meanwhile, in order to maintain a desired potential difference for one frame, a storage capacitor and a liquid crystal capacitor are formed. The storage capacitor is classified into a separate wire type using the transparent pixel electrode and a separate storage electrode, and a front gate type using the protrusion of the immediately above gate electrode and the transparent pixel electrode. The liquid crystal capacitor is formed using the pixel electrode and the reference electrode on the color filter. The storage capacitor and the liquid crystal capacitor are connected in parallel with each other.

The color filter substrate 56 is disposed above the polarizer and includes color filters of R, G, and B in regions corresponding to the pixel electrodes so that colors may be displayed for each pixel. The color filter may be formed above or below the pixel electrode. In addition, a reference electrode made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO) is formed on the color filter.

A liquid crystal layer (not shown) is filled between the TFT substrate 55 and the color filter substrate 56 and has dielectric anisotropy. The liquid crystal layer (not shown) has a thickness of about 5 μm and has a twisted nematic (TN) arrangement. The alignment direction of the liquid crystal layer (not shown) is changed by a voltage applied from the outside to adjust the transmittance of light passing through the liquid crystal layer (not shown).

The signal line 57 transmits a gate signal to a gate line formed on the TFT substrate 55 and a data signal to a data line.

The input pads 58 are located at one end of the signal line 57 and receive a plurality of driving signals from the tester (see 10 in FIG. 1).

The shape of the probe unit (see 40 in FIG. 1) depends on how the driving IC is connected to the liquid crystal panel 50. That is, the driving IC may be connected in a Tape Carrier Package (TCP) mounting method and a Chip On Glass (COG) mounting method. The TCP mounting method is a method of separately attaching a tape with a driving IC to a TFT substrate, and the COG mounting method is a method of forming a direct drive IC on a predetermined region of a TFT substrate. The tester of the liquid crystal display according to the exemplary embodiment of the present invention uses a COG mounting method as an example.

The probe unit (see 40 in FIG. 1) includes a probe base 41, a probe stage 42, a probe block 43, and a probe pin 44.

The probe base 41 includes an opening larger in size than the liquid crystal panel 50 so that the liquid crystal panel 50 under test is exposed. In addition, a plurality of structures, such as a probe block 43 and a probe pin 44, are formed on the probe base 41.

The probe stage 42 is installed under the probe base 41, and the liquid crystal panel 50 is placed on the probe stage 42. In addition, the probe stage 42 may be raised or lowered to contact the input pads 58 and the probe blocks 43.

A plurality of probe blocks 43 are formed on the upper surface of the probe base 41, and serve to integrate the plurality of probe pins 44 into one unit.

The probe pin 44 electrically connects the liquid crystal panel 50 and the probe unit (see 40 of FIG. 1) and applies a driving signal of the tester (see 10 of FIG. 1).

Hereinafter, a test method of the liquid crystal display of the present invention will be described with reference to FIGS. 3A to 6B. In the drawing, symbol (?) Indicates that the pixel displays black, and symbol? Indicates that the pixel displays predetermined colors (R, G, B) and the like. In the drawing, the liquid crystal panel has an example in which eight dots form one row.

3A and 3B are conceptual views of a liquid crystal panel for explaining a test method of a liquid crystal display according to a first embodiment of the present invention.                     

Referring to FIGS. 3A and 3B, first, a plurality of dots of a liquid crystal panel include a first region including dots of (odd rows and odd columns), a second region including dots of (odd rows and even columns), ( A third area including dots of even rows and odd columns and a fourth area including dots of (even rows and even columns) will be described separately.

In the pattern 51a of FIG. 3A, the first and fourth regions represent white (W), and the second and third regions represent black. In the pattern 51b of FIG. 3B, the first and fourth regions represent black, and the second and third regions represent white (W). The test method of the liquid crystal display according to the first exemplary embodiment of the present invention alternately provides the patterns 51a and 51b to the liquid crystal panel.

Although the bad pixel A is not detected in the pattern 51a of FIG. 3A, the bad pixel A may be detected in the pattern 51b of FIG. 3B. That is, the dot dotA including the bad pixel A is easily noticeable since the adjacent dots represent black. Therefore, the bad pixel A becomes more likely to be detected.

As such, when the patterns 51a and 51b of FIGS. 3A and 3B are crossed and provided to the liquid crystal panel, the defective pixels / dots can be detected more easily than the conventional test method even in a liquid crystal panel having a high resolution.

Table 1 compares the case of using the conventional R, G, B and W patterns with the case of using the patterns 51a and 51b according to the first embodiment of the present invention. In the case of using the patterns 51a and 51b according to the first embodiment of the present invention, the module failure rate was reduced by 36.5% and the judgment agreement rate was increased by 4.3% compared to the case of using the conventional R, G, B, and W patterns. It can be seen.

Module failure rate Judgment Concordance Rate by Inspector Conventional pattern Pattern according to the first embodiment of the present invention Conventional pattern Pattern according to the first embodiment of the present invention 6.262PPM 3.978PPM (36.5% decrease) 82.4%                                              86.7% (4.3% increase)

4A and 4B are conceptual views illustrating a liquid crystal panel for explaining a test method of a liquid crystal display according to a second exemplary embodiment of the present invention.

4A and 4B, a plurality of dots of the liquid crystal panel are divided into a plurality of regions as shown in FIGS. 3A and 3B.

In the pattern 52a of FIG. 4A, the second and third regions represent red (R), and the first and fourth regions represent black. In the pattern 52b of FIG. 4B, the second and third regions represent black, and the first and fourth regions represent red (R). The test method of the liquid crystal display according to the second exemplary embodiment of the present invention alternately provides the patterns 52a and 52b to the liquid crystal panel. Although only red (R) is represented in the patterns 52a and 52b of FIGS. 4A and 4B, green (G) and blue (B) may also be used.

Although the bad pixel B is not detected in the pattern 52a of FIG. 4A, the bad pixel B may be detected in the pattern 52b of FIG. 4B. That is, the dot including the bad pixel B may be easily seen because adjacent dots represent black. Therefore, the bad pixel B is likely to be detected.

As such, when the patterns 52a and 52b of FIGS. 4A and 4B are crossed and provided to the liquid crystal panel, the defective pixels / dots can be detected more easily than the conventional test method even in a liquid crystal panel having a high resolution.

5A and 5B are conceptual views of a liquid crystal panel for explaining a test method of a liquid crystal display according to a third exemplary embodiment of the present invention.

5A and 5B, first, a plurality of dots of a liquid crystal panel are divided into a fifth region including odd rows and a sixth region including even rows.

In the pattern 53a of FIG. 5A, the fifth region represents red (R) and the sixth region represents black. In the pattern 53b of FIG. 5B, the fifth region represents black and the sixth region represents red (R). The test method of the liquid crystal display according to the third exemplary embodiment of the present invention alternately provides the patterns 53a and 53b to the liquid crystal panel. Although only red (R) is represented in the patterns 53a and 53b of FIGS. 5A and 5B, green (G) and blue (B) may also be used.

Although the bad pixel C is not detected in the pattern 53a of FIG. 5A, the bad pixel C may be detected in the pattern 53b of FIG. 5B. That is, the dot C including the bad pixel C may be easily noticeable since the dots located on both sides represent black. Therefore, the bad pixel C is likely to be detected.

As such, when the patterns 53a and 53b of FIGS. 5A and 5B are crossed and provided to the liquid crystal panel, the defective pixels / dots can be detected more easily than in the conventional test method even in a liquid crystal panel having a high resolution.

6A and 6B are conceptual views illustrating a liquid crystal panel for explaining a test method of a liquid crystal display according to a fourth exemplary embodiment of the present invention.

6A and 6B, first, a plurality of dots of a liquid crystal panel are divided into seventh areas including odd rows and eighth areas including even rows.

In the pattern 54a of FIG. 6A, the seventh region represents red (R) and the eighth region represents black. In the pattern 54b of FIG. 6B, the seventh region represents black and the eighth region represents red (R). The test method of the liquid crystal display according to the fourth exemplary embodiment of the present invention alternately provides the patterns 54a and 54b to the liquid crystal panel. In the patterns 54a and 54b of FIGS. 6A and 6B, only red (R) is represented, but not limited thereto, and green (G) and blue (B) may be possible.

Although the bad pixel D is not detected in the pattern 54a of FIG. 6A, the bad pixel D may be detected in the pattern 54b of FIG. 6B. That is, the dot including the bad pixel D may be easily noticeable since the dots located on both sides represent black. Therefore, the bad pixel D is more likely to be detected.

As described above, when the patterns 54a and 54b of FIGS. 6A and 6B are crossed and provided to the liquid crystal panel, a bad pixel / dot can be detected more easily than a conventional test method even in a liquid crystal panel having a high resolution.

Although an embodiment of the present invention has been described mainly for the detection of defects of off dots, it is obvious that the present invention can be applied to the detection of defects of high dots.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

According to the test method of the liquid crystal display according to the present invention as described above has one or more of the following effects.

First, even if the size of the pixel is small, it is possible to easily detect a defective dot / pixel, thereby increasing the reliability of the test.

Second, since the defective rate of the liquid crystal display is lowered, the yield can be increased.

Claims (6)

A first region containing dots of (odd rows, odd columns), a second region containing dots of (odd rows, even columns), a third region containing dots of (even rows, odd columns), (even Providing a liquid crystal panel comprising a fourth region comprising dots of rows, even columns; The first and fourth areas representing a predetermined color, and the second and third areas representing black; And And the first and fourth regions represent black, and the second and third regions represent a predetermined color. The method of claim 1, The said predetermined color is any of R, G, B, W test method of a liquid crystal display device. Providing a liquid crystal panel comprising a first region comprising odd rows of dots and a second region comprising even rows of dots; The first region represents a predetermined color, and the second region represents black; And And the first region expresses black and the second region expresses a predetermined color. The method of claim 3, wherein The said predetermined color is any of R, G, B, W test method of a liquid crystal display device. Providing a liquid crystal panel comprising a first region comprising odd rows of dots and a second region comprising even rows of dots; The first region represents a predetermined color, and the second region represents black; And And the first region expresses black and the second region expresses a predetermined color. The method of claim 5, The said predetermined color is any of R, G, B, W test method of a liquid crystal display device.

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