KR20070107469A - Testing device of liquid cristal display and testing method thereof - Google Patents

Abstract

A device and a method for testing a liquid crystal display device are provided to detect a defective pixel in which a particle occurs in advance and control a storage voltage applied to the detected defective pixel, thereby removing luminance difference caused by the defective pixel. A device for testing a liquid crystal display device includes an LCD(Liquid Crystal Display) panel having storage capacitors formed by insulating-overlapping between storage lines(Vst) and pixel electrodes, and storage voltage generating parts for supplying a storage voltage to the storage lines for activating liquid crystal of defective pixel areas by a voltage difference from a common voltage(Vcom), which is applied to common electrodes. An absolute value of the voltage difference between the storage voltage and the common voltage is 1V or higher when the LCD panel is in a normally black mode, and 1V or lower when the LCD panel is in a normally white mode. The defective pixels are pixels of which electrodes are electrically short by generation of a particle. The storage voltage generating part has distributing resistors(R1,R2) for distributing an input voltage to generate the storage voltage, and a comparator(77) for generating the storage voltage, which is the difference voltage between the common voltage and the storage input voltage.

Description

Inspection apparatus of liquid crystal display device and its inspection method {TESTING DEVICE OF LIQUID CRISTAL DISPLAY AND TESTING METHOD THEREOF}

1 is a view illustrating a liquid crystal display panel in which bad particles are generated according to an exemplary embodiment of the present invention.

2 is an equivalent view of a liquid crystal display panel according to an exemplary embodiment of the present invention.

3 is a graph showing a change in transmittance of the liquid crystal for each voltage applied thereto.

4 is a circuit diagram illustrating a storage power supply unit according to an exemplary embodiment of the present invention.

 <Description of Symbols for Main Parts of Drawings>

8 gate electrode 10 source electrode

12 drain electrode 14 active layer

16 contact hole 18 pixel electrode

20 liquid crystal display panel 30 gate insulating film

50: protective film 52: organic film

70: Particle 77: Comparator

98: color filter array substrate 99: thin film transistor substrate

BM: Black Matrix CF: Color Filter

GL: Gate Line DL: Data Line

CLc: Liquid Crystal Vcom: Common Voltage

Vst: Storage Line

The present invention relates to an inspection apparatus for a liquid crystal display device and an inspection method thereof, wherein the inspection apparatus for a liquid crystal display panel capable of improving a yield by detecting particle defects occurring in a storage line region and adjusting a voltage supplied to a defective pixel. It is about the inspection method.

The liquid crystal display device displays an image by adjusting the light transmittance of the liquid crystal using an electric field. To this end, the liquid crystal display includes a liquid crystal display panel in which liquid crystal cells are arranged in a matrix, and a driving circuit for driving the liquid crystal display panel.

In the liquid crystal display panel having such a structure, particle defects are frequently generated when various signal lines connected to the TFT and the TFT are connected to the substrate. As a result, such particle defects cause serious losses due to the disposal of the liquid crystal display panel. Accordingly, there is an urgent need for a method of improving particle yield by improving particle defects occurring in a liquid crystal display panel.

Accordingly, an object of the present invention is to provide an inspection apparatus for a liquid crystal display device and an inspection method thereof, which can improve yield by detecting particle defects occurring in a liquid crystal display panel and adjusting a voltage supplied to the detected pixel. It is.

In order to achieve the above technical problem, an inspection apparatus of a liquid crystal display according to an exemplary embodiment of the present invention may include a thin film transistor connected to a gate line and a data line, a pixel electrode connected to the thin film transistor and formed in a pixel region, and a pixel electrode. A liquid crystal display panel including a common electrode constituting an electric field, a storage capacitor formed in parallel with the gate line, and a storage capacitor formed to insulate the pixel electrode; And a storage voltage generator configured to supply a storage voltage to the storage line such that the liquid crystal of the defective pixel region is activated by a difference voltage with the common voltage supplied to the common electrode.

Here, when the liquid crystal display panel is in the normally black mode, an absolute value of a voltage difference between the storage voltage and the common voltage is 1 V or more, and when the liquid crystal display panel is in the normally white mode, the storage voltage and the common voltage The absolute value of the voltage difference is characterized in that less than 1V.

The defective pixel may be a pixel in which the storage line and the pixel electrode are electrically shorted.

The storage voltage generation unit divides the input voltage supplied from the outside with a voltage distribution resistor for generating a storage input voltage; And a comparator for generating the storage voltage which is a difference between the common voltage and the storage input voltage.

In order to achieve the above object, an inspection method of a liquid crystal display according to an exemplary embodiment of the present invention includes a thin film transistor connected to a gate line and a data line, a pixel electrode connected to the thin film transistor and formed in a pixel region, and the pixel electrode and an electric field. 10. A method of inspecting a liquid crystal display panel comprising: a common electrode constituting a common electrode, a storage capacitor formed parallel to the gate line, and a storage capacitor formed to insulate the pixel electrode, the method comprising: supplying a common voltage to the common electrode; Supplying a storage voltage to the storage line such that a liquid crystal in a bad pixel region is activated by a difference voltage with a common voltage supplied to the common electrode; Examining the transmittance of the liquid crystal; And detecting a bad pixel according to the liquid crystal transmittance.

The supplying of the storage voltage to the storage line may include supplying the storage line to the storage line having an absolute value of 1 V or more, when the liquid crystal display panel is normally black. Characterized in that.

The supplying of the storage voltage to the storage line may include supplying the storage line to the storage line having an absolute value of 1 V or less in comparison with the common voltage when the liquid crystal display panel is in a normally white mode. Characterized in that.

Other technical problems and advantages of the present invention in addition to the above technical problem will be apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.

1 is a cross-sectional view of a portion of a liquid crystal display panel according to an exemplary embodiment of the present invention, and FIG. 2 is an equivalent circuit diagram of each component of the liquid crystal display panel.

The liquid crystal display panel 20 illustrated in FIGS. 1 and 2 includes a thin film transistor substrate 99 and a color filter substrate 98 facing each other, and a liquid crystal CLc injected between the two substrates.

The color filter substrate 98 includes color filters CF formed in units of the liquid crystal cell CLc, a black matrix BM for distinguishing between the color filters CF and reflecting external light, and the liquid crystal cells CLc. A color filter array including a common electrode 40 for supplying a reference voltage Vcom in common to the substrate and an alignment layer applied thereon is formed on the upper substrate 98a.

The thin film transistor substrate 99 may include gate lines GL, data lines DL, and storage lines Vst, thin film transistors TFT formed of switch elements at respective intersections thereof, and a liquid crystal cell CLc. A thin film transistor array including a pixel electrode 18 formed and connected to the thin film transistor TFT and an alignment film coated thereon is formed on the lower substrate 99a.

The thin film transistor TFT supplies the pixel signal supplied to the data line DL to the pixel electrode 18 in response to the scan signal supplied to the gate line GL. To this end, the thin film transistor TFT allows the pixel signal supplied to the data line DL to be charged and held in the pixel electrode 18 in response to the scan signal supplied to the gate line GL. To this end, the thin film transistor TFT includes a gate electrode 8 connected to the gate line GL, a source electrode 10 connected to the data line DL, and a drain electrode connected to the pixel electrode 18. 12 and an active layer 14 overlapping the gate electrode 8 and forming a channel between the source electrode 10 and the drain electrode 12. In addition, an ohmic contact layer 48 is further provided between the active layer 14, the source electrode 10, and the active layer 14 and the drain electrode 12, and the exposed active layer with the source electrode 10 and the drain electrode 12. A passivation layer 50 is formed to protect 14, an organic layer 52 is formed on the passivation layer 50, and the pixel electrode 18 is overlapped on the organic layer 52. As the gate metal, chromium (Cr), molybdenum (Mo), aluminum-based metal, etc. are used in a single layer or a double layer structure. As the material of the protective film 50, an inorganic insulating material such as the gate insulating film 30, an organic insulating material such as an acryl-based organic compound having a low dielectric constant, BCB or PFCB, or the like is used.

The pixel electrode 18 is connected to the drain electrode 12 of the thin film transistor TFT through a contact hole 16 penetrating through the passivation layer 50. The pixel electrode 18 generates a potential difference with the common electrode 40 formed thereon by the charged pixel signal. Due to this potential difference, the liquid crystal CLc positioned between the thin film transistor substrate 99 and the upper substrate 98a is rotated by dielectric anisotropy and receives light incident through the pixel electrode 18 from a light source (not shown). It is transmitted toward the upper substrate 98a. Molybdenum (Mo), molybdenum alloy (Mo alloy), etc. are used as a source / drain metal.

The storage capacitor Cst has a structure of a storage line Vst disposed with the gate insulating layer 30 interposed therebetween, and a drain electrode 12 overlapping the storage line Vst. The storage capacitor Cst allows the pixel signal charged in the pixel electrode 18 to be stably maintained until the next pixel signal is charged. Here, an inorganic insulating material such as silicon oxide (SiOx) or silicon nitride (SiNx) is used as the material of the gate insulating film 30.

Meanwhile, in the liquid crystal display panel 20 according to the exemplary embodiment of the present invention, the particles 70 are formed in the storage line Vst region so that the drain electrode 12 and the storage line Vst are electrically energized with each other. The defect will be described as an example. When the particle 70 is defective, the particle defect may be detected according to the transmittance of the liquid crystal measured in the normally black mode and the normally white mode. This will be described in detail with reference to FIG. 3.

3 is a graph showing the change in transmittance of the liquid crystal for each voltage applied.

In the normal black mode, it is assumed that the voltage difference between the common electrode 40 and the pixel electrode 18, which may exhibit the maximum liquid crystal transmittance, that is, the maximum luminance, is 6.77 V. In this case, the maximum luminance value is 0.5 and the normally white In the mode, when the voltage difference is 0V, the lowest luminance, that is, the minimum transmittance value of the liquid crystal is assumed to be zero.

Referring to FIG. 3, the failure detection method according to the exemplary embodiment of the present invention first supplies 6.77 V to the common electrode 40 in the normally black mode, and applies a voltage of 5.27 V to the entire pixel electrode 18. Supplies a ground voltage to the storage line Vst. In this case, in the case of the normal pixel in which the particle 70 does not occur, the luminance value is about 0.35, which is the luminance corresponding to the voltage difference between the common electrode 40 and the pixel electrode 18. However, in the case of the defective pixel in which the particle 70 is generated, the pixel electrode 18 and the storage line Vst line are electrically connected to each other, so that the voltage of the pixel electrode 18 is substantially the voltage of the storage line Vst. Will be equal to As a result, the voltage difference between the common electrode 40 and the pixel electrode 18 is 6.77V. Therefore, the pixel in which the particle defect occurs has a maximum luminance value which is higher than that of the normal pixel. That is, in the normally black mode, the defective pixel detection method according to the present invention sets the absolute value of the difference between the storage voltage and the common voltage Vcom to 1 V or more to detect conductive foreign matter.

Next, in the normally white mode, 6.77 V is supplied to the common electrode 40, 5.27 V is supplied to the entire pixel electrode 18, and the storage line Vst has the same voltage as that of the common electrode 40. Provides 6.77V. In this case, in the case of the normal pixel in which the particle 70 does not occur, the luminance value is about 0.1, which is the luminance corresponding to the voltage difference between the common electrode 40 and the pixel electrode 18. However, in the case of the defective pixel in which the particle 70 is generated, the pixel electrode 18 and the storage line Vst line are electrically connected to each other, so that the voltage of the pixel electrode 18 is substantially the voltage of the storage line Vst. Will be equal to As a result, the voltage difference between the common electrode 40 and the pixel electrode 18 becomes 0V. Therefore, the pixel in which the particle defect occurs has the lowest luminance value, which is lower than the normal pixel. That is, in the normally white mode, the defective pixel detection method according to the present invention sets the absolute value of the difference between the storage voltage and the common voltage Vcom to 1 V or less to detect conductive foreign matter.

In this manner, the defective pixel in which the particle 70 is generated may have a different luminance value from that of the surrounding pixels, and thus may be easily detected.

As described above, it can be seen that the change of the liquid crystal Clc operates regardless of the storage line Vst since the liquid crystal Clc does not change regardless of the voltage applied to the storage line Vst voltage under normal conditions. have.

Meanwhile, the liquid crystal display panel 20 in which the particle 70 defect is generated may generate the luminance value of the defective pixel similarly to the luminance value of the surrounding normal pixel by adjusting the signal supply as shown in FIG. 4. .

4 is a circuit diagram illustrating a storage power supply unit supplying a voltage to a storage line Vst according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the storage power supply unit according to the present invention uses a comparator 77 and an input voltage AVDD connected between the common voltage source Vcom and the storage line Vst to receive the input voltage AVDD through a distribution resistor. And a storage input voltage source Vst_in provided to the second input of the comparator 77 and electrically connected to the common voltage source Vcom and the storage line Vst to form a feedback circuit.

The comparator 77 generates an output voltage Vst_out, which is a difference voltage between the voltage of the common voltage source Vcom and the storage input voltage source Vst_in voltage, and supplies it to the storage line Vst.

The storage input voltage source Vst_in divides the input voltage AVDD input from the outside by using the first and second resistors R1 and R2 and supplies the voltage to the comparator 77.

The storage power supply unit according to the embodiment of the present invention opens the first resistor R1 in the normally black mode, and the second resistor R2 is 0 ohm and the voltage of the storage input voltage source Vst_in. By setting the voltage to the ground voltage it is possible to detect the failure of the liquid crystal display panel 20 as described with reference to FIG. Even in the normally white mode, the first and second resistors 1 and 2 may be adjusted to set the output voltage Vst_out to meet the above-described conditions.

On the other hand, when the liquid crystal display panel 20 having pixels in which particle defects are formed as a real product, the particles 70 are generated so that the first and second resistors do not appear as a high pixel representing a maximum luminance value. The output voltage Vst_out of the storage power supply unit is set by adjusting the values of (R1, R2).

That is, the mass production liquid crystal display panel having pixels in which particle defects are generated supplies a storage voltage Vst that satisfies Equation 1 to the storage line in the normally black mode.

Vcom-Vst | <1V

However, Vcom is a common voltage.

The liquid crystal display according to the present invention and a method for detecting a bad pixel thereof can remove a luminance difference due to a bad pixel by detecting a bad pixel in which particles are generated in advance and adjusting a storage voltage supplied to the detected bad pixel. have.

As described above, the inspection apparatus of the liquid crystal display device and the inspection method thereof according to the present invention can improve the yield by detecting particle defects occurring in the liquid crystal display panel and adjusting the voltage supplied to the detected pixels.

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

Claims (8)

A thin film transistor connected to the gate line and the data line, a pixel electrode connected to the thin film transistor, a common electrode forming an electric field with the pixel electrode, a storage line formed parallel to the gate line, and the pixel electrode insulated from each other A liquid crystal display panel including a storage capacitor; And a storage voltage generator configured to supply a storage voltage to the storage line so that the liquid crystal in the defective pixel region is activated by a difference voltage with the common voltage supplied to the common electrode. The method of claim 1, And the absolute value of the voltage difference between the storage voltage and the common voltage is 1 V or more when the liquid crystal display panel is in normally black mode. The method of claim 1, And the absolute value of the voltage difference between the storage voltage and the common voltage is 1 V or less when the liquid crystal display panel is in a normally white mode. The method of claim 1, And the bad pixel is a pixel in which the storage line and the pixel electrode are electrically shorted. The method of claim 1, The storage voltage generator A divider resistor for dividing the input voltage supplied from the outside to generate a storage input voltage; And a comparator for generating the storage voltage which is a difference between the common voltage and the storage input voltage. A thin film transistor connected to the gate line and the data line, a pixel electrode connected to the thin film transistor, a common electrode forming an electric field with the pixel electrode, a storage line formed parallel to the gate line, and the pixel electrode insulated from each other In the inspection method of the liquid crystal display panel comprising a storage capacitor is formed, Supplying a common voltage to the common electrode; Supplying a storage voltage to the storage line such that a liquid crystal in a bad pixel region is activated by a difference voltage with a common voltage supplied to the common electrode; Examining the transmittance of the liquid crystal; And detecting a bad pixel according to the liquid crystal transmittance. The method of claim 6, Supplying a storage voltage to the storage line And supplying the storage line to the storage line in which the absolute value of the voltage difference with respect to the common voltage is 1 V or more when the liquid crystal display panel is normally black mode. The method of claim 6, Supplying a storage voltage to the storage line And supplying the storage voltage to the storage line in which the absolute value of the voltage difference with respect to the common voltage is 1 V or less when the liquid crystal display panel is in a normally white mode.

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