KR20080041842A - Lcd and detection method thereof - Google Patents

Abstract

An LCD device and an inspecting method thereof are provided to inspect the short of a common voltage line connected to the common electrode of each pixel and a storage line connected to the storage capacitor of each pixel automatically, thereby improving user's convenience and not allocating a separate inspection time to the short inspection. An LCD(Liquid Crystal Display) device comprises an LCD panel and a short inspector(190). Plural pixels are formed in the LCD panel. The plural pixels have a storage capacitor for receiving a storage voltage(Vcst) through a storage line and a common electrode for receiving a common voltage(Vcom) through a common voltage line. The short inspector compares the common voltage with the storage voltage to inspect the short of the storage line and the common voltage line. The short inspector comprises a comparing unit(191), a short determining unit(192), and a display unit(193). The comparing unit compares the sizes of the storage voltage and the common voltage. The short determining unit determines the short of the common voltage line and the storage line by using the determination result of the comparing unit. The display unit displays the short of the common voltage line and the storage line according to the determination result of the short determining unit.

Description

Liquid crystal display and inspection method thereof

1 is an equivalent circuit diagram of a pixel formed in a general liquid crystal display device.

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

3 is a block diagram of the short tester shown in FIG.

4 is a circuit diagram of a comparison unit shown in FIG. 3.

5 is a circuit diagram of a display unit illustrated in FIG. 3.

6 is a flowchart illustrating a test method of a liquid crystal display according to an exemplary embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

100: liquid crystal display device 110: liquid crystal display panel

120: data driver 130: gate driver

140: gamma reference voltage generator 150: common voltage generator

160: storage voltage generator 170: gate driving voltage generator

180: timing controller 190: short checker

191: comparison unit 192: short discrimination unit

193: display unit 191-1: comparator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display capable of automatically checking whether a common voltage line connected to a common electrode of each pixel and a storage line connected to a storage capacitor of each pixel are short. It is about the inspection method.

A liquid crystal display device displays an image by adjusting light transmittance of liquid crystal cells according to a video signal, and an active matrix type liquid crystal display device in which a switching element is formed for each liquid crystal cell enables active control of the switching element. This is advantageous for video implementation. As the switching element used in the active matrix liquid crystal display device, a thin film transistor (hereinafter referred to as TFT) is mainly used as shown in FIG. 1.

Referring to FIG. 1, an active matrix type liquid crystal display converts digital input data into an analog data voltage based on a gamma reference voltage and supplies it to the data line DL and simultaneously supplies scan pulses to the gate line GL. The liquid crystal cell Clc is charged.

The gate electrode of the TFT is connected to the gate line GL, the source electrode is connected to the data line DL, and the drain electrode of the TFT is a pixel electrode of the liquid crystal cell Clc and one electrode of the storage capacitor Cst. The storage line Lcst is connected to the other electrode of the storage capacitor Cst. Here, the storage voltage Vcst is supplied to the other electrode of the storage capacitor Cst through the storage line Lcst.

The common voltage line Lcom is connected to the common electrode of the liquid crystal cell Clc, and the common voltage Vcom is supplied to the common electrode through the common voltage line Lcom.

The storage capacitor Cst charges a data voltage applied from the data line DL when the TFT is turned on, thereby maintaining a constant voltage of the liquid crystal cell Clc. The voltage charged in the storage capacitor Cst is maintained for a predetermined time by the storage voltage Vcst supplied through the storage line Lcst.

When the scan pulse is applied to the gate line GL, the TFT is turned on to form a channel between the source electrode and the drain electrode so that the voltage on the data line DL is applied to the pixel electrode of the liquid crystal cell Clc. Supply. At this time, the liquid crystal molecules of the liquid crystal cell Clc modulate the incident light by changing the arrangement by the electric field between the pixel electrode and the common electrode.

As described above, the common voltage Vcom and the storage voltage Vcst are supplied to each pixel. If the storage line Lcst and the common voltage line Lcom are shorted, the same voltage is supplied to the common electrode and the storage capacitor Cst. There is a problem in that accurate gradation is not achieved.

In order to improve this problem, the user conventionally checks whether the storage line Lcst and the common voltage line Lcom are short by using a short test apparatus, and repairs them when a short occurs. Here, the short inspection device is a product manufactured separately from the liquid crystal display device.

By manually inspecting whether the storage line Lcst and the common voltage line Lcom are short by using the short test device, the user is not only troublesome to check the short but also takes a lot of test time. In addition, by purchasing the short inspection device separately from the liquid crystal display device, a large cost is consumed.

The present invention has been made to solve the above problems, and an object of the present invention is to automatically check whether the common voltage line connected to the common electrode of each pixel and the storage line connected to the storage capacitor of each pixel are automatically checked. The present invention provides a liquid crystal display device and an inspection method thereof.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device and an inspection method thereof by automatically checking whether a common voltage line and a storage line are short, so as to facilitate the user's convenience and not to set aside inspection time.

An object of the present invention is to provide a liquid crystal display device and an inspection method thereof that can reduce the cost of purchasing a short inspection device by inspecting whether the common voltage line and the storage line are short.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display and an inspection method thereof in which a short generation is automatically displayed when a common voltage line and a storage line are shorted, so that a user can recognize the short in real time.

According to an exemplary embodiment of the present invention, a liquid crystal display panel includes a storage capacitor configured to receive a storage voltage through a storage line and a plurality of pixels having a common electrode supplied through a common voltage line. ; And a short tester comparing the common voltage and the storage voltage to check whether the storage line and the common voltage line are short.

The short checker may include a comparator configured to compare the magnitudes of the storage voltage and the common voltage; A short determination unit determining whether the common voltage line and the storage line are short by using the comparison result of the comparison unit; And a display unit which displays whether the common voltage line and the storage line are shorted according to the determination result of the short discrimination unit.

According to an aspect of the present invention, there is provided a liquid crystal display device comprising: a liquid crystal display panel including a plurality of pixels including a storage capacitor receiving a storage voltage through a storage line and a common electrode receiving a common voltage through a common voltage line; A comparison unit comparing the magnitudes of the storage voltage and the common voltage; A short determination unit determining whether the common voltage line and the storage line are short by using the comparison result of the comparison unit; And a display unit which displays whether the common voltage line and the storage line are shorted according to the determination result of the short discrimination unit.

The comparator includes a comparator comparing the magnitude of the storage voltage input to the inverting input terminal and the common voltage input to the non-inverting input terminal and outputting a comparison result to the short discriminator connected to the output terminal.

The short determiner determines that the common voltage line and the storage line are not shorted when the low signal is input from the comparator, and outputs a normal signal to the display unit. When the high signal is input from the comparator, the common voltage line and the storage line are determined. It is determined that the short circuit is detected and an error signal is output to the display unit.

The display unit includes a light emitting diode that maintains an off state when the normal signal is input from the short discriminator and emits light when the error signal is input from the short discriminator.

An inspection method of a liquid crystal display according to an embodiment of the present invention includes a liquid crystal display panel having a liquid crystal display panel having a plurality of pixels including a storage capacitor receiving a storage voltage through a storage line and a common electrode receiving a common voltage through a common voltage line. A method of inspecting a display device, the method comprising: comparing a magnitude of the storage voltage and a common voltage; Determining whether the common voltage line and the storage line are short by using the comparison result; And displaying whether the common voltage line and the storage line are short based on the short determination result.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

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

Referring to FIG. 2, in the liquid crystal display device 100 of the present invention, the data lines DL1 through DLm and the gate lines GL1 through GLn cross each other and drive the liquid crystal cell Clc at an intersection thereof. A liquid crystal display panel 110 having a thin film transistor (TFT), a data driver 120 for supplying data to the data lines DL1 to DLm of the liquid crystal display panel 110, and a liquid crystal display panel. A gate driver 130 for supplying scan pulses to the gate lines GL1 to GLn of 110, a gamma reference voltage generator 140 for generating a gamma reference voltage and supplying the gamma reference voltage to the data driver 120; And a common voltage generator 150 for generating a common voltage Vcom to supply the common electrode of the liquid crystal cell Clc of the liquid crystal display panel 110, and a storage voltage generator for generating a storage voltage Vcst. The gate driver 160 generates a gate high voltage VGH and a gate low voltage VGL. The gate driving voltage generation unit 170 for supplying to the 130, the timing controller 180 for controlling the data driver 120 and the gate driver 130, the common voltage line Lcom, and the storage line Lcst. ) Is provided with a short tester 190 for inspecting whether or not the short.

The liquid crystal display device 100 of the present invention includes a backlight assembly (not shown) for irradiating light to the liquid crystal display panel 110 and an inverter (not shown) for applying an alternating voltage and current to the backlight assembly 150. C).

In the liquid crystal display panel 110, liquid crystal is injected between two glass substrates. The data lines DL1 to DLm and the gate lines GL1 to GLn are orthogonal to the lower glass substrate of the liquid crystal display panel 110. TFTs are formed at intersections of the data lines DL1 to DLm and the gate lines GL1 to GLn. The TFT supplies the data on the data lines DL1 to DLm to the liquid crystal cell Clc in response to the scan pulse. The gate electrodes of the TFTs are connected to the gate lines GL1 to GLn, and the source electrodes of the TFTs are connected to the data lines DL1 to DLm. The drain electrode of the TFT is connected to the pixel electrode of the liquid crystal cell Clc and the storage capacitor Cst.

The TFT is turned on in response to the scan pulse supplied to the gate terminal via the gate lines GL1 to GLn. When the TFT is turned on, video data on the data lines DL1 to DLm is supplied to the pixel electrode of the liquid crystal cell Clc.

The data driver 120 supplies data to the data lines DL1 to DLm in response to the data driving control signal DDC supplied from the timing controller 180. Here, the data driver 120 samples and latches the digital video data RGB supplied from the timing controller 180, and then the liquid crystal display panel 110 based on the gamma reference voltage supplied from the gamma reference voltage generator 140. In the liquid crystal cell Clc of FIG. 1, the grayscale is converted into an analog data voltage that can express gray levels, and is supplied to the data lines DL1 to DLm.

The gate driver 130 sequentially generates scan pulses, that is, gate pulses, in response to the gate driving control signal GDC and the gate shift clock GSC supplied from the timing controller 180, thereby providing the gate lines GL1 to GLn. To feed. In this case, the gate driver 130 determines the high level voltage and the low level voltage of the scan pulse according to the gate high voltage VGH and the gate low voltage VGL supplied from the gate driving voltage generator 170.

The gamma reference voltage generator 140 receives a high potential power supply voltage VDD to generate a positive gamma reference voltage and a negative gamma reference voltage and output the same to the data driver 120.

The common voltage generator 150 receives the high potential power voltage VDD to generate the common voltage Vcom and supplies the common voltage Vcom to the common electrodes of the liquid crystal cells Clc of each pixel of the liquid crystal display panel 110.

The storage voltage generator 160 receives the high potential power voltage VDD to generate the storage voltage Vcst, and supplies the storage voltage Vcst to the storage capacitor Cst through the storage line Lcst.

The gate driving voltage generator 170 receives the high potential power voltage VDD to generate the gate high voltage VGH and the gate low voltage VGL to supply the gate driver 130 to the gate driver 130. Here, the gate driving voltage generation unit 170 generates a gate high voltage VGH that is greater than or equal to the threshold voltage of the TFT provided in each pixel of the liquid crystal display panel 110, and a gate low voltage (below the threshold voltage of the TFT). VGL). The gate high voltage VGH and the gate low voltage VGL generated in this way are used to determine the high level voltage and the low level voltage of the scan pulse generated by the gate driver 130, respectively.

The timing controller 180 supplies the digital video data RGB supplied from the system to the data driver 120 and controls the data driving using the horizontal / vertical synchronization signals H and V according to the clock signal CLK. The signal DDC and the gate driving control signal GDC are generated and supplied to the data driver 120 and the gate driver 130, respectively. The data driving control signal DDC includes a source shift clock SSC, a source start pulse SSP, a polarity control signal POL, a source output enable signal SOE, and a gate driving control signal GDC. ) Includes a gate start pulse (GSP) and a gate output enable (GOE).

The short checker 190 compares the common voltage Vcom output from the common voltage generator 150 and the storage voltage Vcst output from the storage voltage generator 160 to compare the common voltage line Lcom and the storage line (S). Lcst) is checked for short. When a short occurs as a result of the test, the short tester 190 turns on to notify the user of a short of the common voltage line Lcom and the storage line Lcst. If no short is generated as a result of the test, the short tester 190 maintains an unlit state.

The backlight assembly is disposed on the rear surface of the liquid crystal display panel 110, and emits light by AC voltage and current supplied from the inverter to irradiate light to each pixel of the liquid crystal display panel 110.

The inverter converts a square wave signal generated therein into a triangular wave signal and compares the triangular wave signal with a DC power supply voltage VCC supplied from the system to generate a burst dimming signal proportional to the comparison result. When a burst dimming signal determined according to an internal square wave signal is generated, a driving IC (not shown) for controlling the generation of an AC voltage and a current in the inverter is connected to an AC voltage supplied to the backlight assembly according to a burst dimming signal. Control the generation of current.

3 is a block diagram of the short tester illustrated in FIG. 2.

Referring to FIG. 3, the short tester 190 compares the magnitude of the common voltage Vcom output from the common voltage generator 150 and the storage voltage Vcst output from the storage voltage generator 160. Determination of the short discriminating unit 192 and the short discriminating unit 192 for determining a short between the common voltage line Lcom and the storage line Lcst by using the comparison result of the unit 191 and the comparator 191. According to the result, the display part 193 which maintains a light-off state or lights up is provided.

The comparator 191 compares the magnitude of the common voltage Vcom output from the common voltage generator 150 and the storage voltage Vcst output from the storage voltage generator 160 to indicate a high signal or a low value indicating a comparison result. Output the signal. As a result of the comparison, when the storage voltage Vcst and the common voltage Vcom are different in size, the comparator 191 outputs a low signal to the short determiner 192. As a result of the comparison, when the storage voltage Vcst and the common voltage Vcom have the same magnitude, the comparator 191 outputs a high signal to the short determiner 192.

The short determiner 192 determines that the common voltage line Lcom and the storage line Lcst are not shorted when the low signal is input from the comparator 191, and outputs a normal signal 3.3V to the display unit 193. On the contrary, when the high signal is input from the comparator 191, it is determined that the common voltage line Lcom and the storage line Lcst are shorted, and outputs an error signal 0V to the display unit 193.

The display unit 193 lights up when an error signal 0V indicating a short between the common voltage line Lcom and the storage line Lcst is input from the short discrimination unit 192 to indicate a short generation to the user. In contrast, the display unit 193 maintains an unlit state when the normal signal 3.3V indicating that the short of the common voltage line Lcom and the storage line Lcst has not been generated is input from the short discriminating unit 192.

4 is a circuit diagram of the comparator shown in FIG. 3.

Referring to FIG. 4, the comparator 191 includes a comparator 191-1 having an inverting input terminal (-), a non-inverting input terminal (+), and an output terminal, and an inverting input terminal (-) of the comparator 191-1. Resistor R1 connected to the resistor R1 connected to the non-inverting input terminal (+) of the comparator 191-1, a negative terminal connected to the non-inverting input terminal (+) and the output terminal of the comparator 191-1. Feedback resistor R3.

The comparator 191-1 compares the magnitude of the storage voltage Vcst input to the inverting input terminal (−) and the common voltage Vcom input to the non-inverting input terminal (+) and outputs a comparison result through the output terminal. As a result of the comparison, when the storage voltage Vcst and the common voltage Vcom are different in size, the comparator 191-1 outputs a low signal to the short discriminator 192 connected to the output terminal. As a result of the comparison, when the storage voltage Vcst and the common voltage Vcom have the same magnitude, the comparator 191-1 outputs a high signal to the short determiner 192 through an output terminal.

FIG. 5 is a circuit diagram of the display unit illustrated in FIG. 3.

Referring to FIG. 5, the display unit 193 includes a light emitting diode LED having an anode and a cathode, and a resistor R4 connected between a cathode of the light emitting diode LED and an output terminal of the short discriminating unit 192. do. Here, the anode of the light emitting diode (LED) is connected to a power supply for supplying a power supply voltage of 3.3V.

When the normal signal 3.3V output from the short discrimination unit 192 is applied to the cathode of the light emitting diode LED, the potential difference is applied to both sides of the light emitting diode LED by applying 3.3V to both the anode and the cathode of the light emitting diode LED. Since it is not generated, the light emitting diode LED remains in an OFF state (off state).

When the error signal 0V output from the short determining unit 192 is applied to the cathode of the light emitting diode LED, a potential difference is generated between both sides of the light emitting diode LED due to different voltages applied to the anode and the cathode of the light emitting diode LED. The light emitting diodes (LEDs) emit light. That is, the light emitting diode LED emits light to display a short of the common voltage line Lcom and the storage line Lcst.

6 is a flowchart illustrating a test method of a liquid crystal display according to an exemplary embodiment of the present invention.

Referring to FIG. 6, when the common voltage Vcom and the storage voltage Vcst are input (S601), the comparison unit 191 compares whether the storage voltage Vcst and the common voltage Vcom have the same magnitude (S601). S602).

As a result of the comparison, when the storage voltage Vcst and the common voltage Vcom are different in size, the comparator 191 outputs a low signal to the short determiner 192 (S603). Subsequently, as the low signal is input, the short determination unit 192 determines that the common voltage line Lcom and the storage line Lcst are not shorted, and outputs a normal signal to the display unit 193 (S604). In response to the display unit 193 maintains an unlit state (S605).

As a result of the comparison in the comparison process S602, when the storage voltage Vcst and the common voltage Vcom have the same magnitude, the comparison unit 191 outputs a high signal to the short determination unit 192 (S606). The short determination unit 192 determines that the common voltage line Lcom and the storage line Lcst are shorted as the high signal is input, and outputs an error signal to the display unit 193 (S607). In response, the display unit 193 lights to display a short generation of the common voltage line Lcom and the storage line Lcst to the user (S608).

As described above, the present invention automatically checks whether the common voltage line connected to the common electrode of each pixel and the storage line connected to the storage capacitor of each pixel are shorted for the convenience of the user and separately for the inspection time. In addition, it is possible to reduce the cost of purchasing the short inspection device. In addition, the present invention automatically displays the occurrence of a short when the storage line of the liquid crystal display is short, so that the user can be aware of the short in real time.

Although the technical spirit of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

Claims (14)

A liquid crystal display panel having a plurality of pixels including a storage capacitor receiving a storage voltage through a storage line and a common electrode receiving a common voltage through a common voltage line; And The short tester which checks whether the storage line and the common voltage line are short by comparing the common voltage and the storage voltage. Liquid crystal display comprising a. The method of claim 1, The short checker, A comparison unit comparing the magnitudes of the storage voltage and the common voltage; A short determination unit determining whether the common voltage line and the storage line are short by using the comparison result of the comparison unit; And And a display unit for displaying whether the common voltage line and the storage line are shorted according to a determination result of the short discrimination unit. The method of claim 2, The comparison unit, And a comparator for comparing the magnitude of the common voltage input to the non-inverting input terminal and outputting a comparison result to the short discrimination unit connected to the output terminal. The method of claim 3, wherein The short determiner determines that the common voltage line and the storage line are not shorted when the low signal is input from the comparator, and outputs a normal signal to the display unit. When the high signal is input from the comparator, the common voltage line and the storage line are determined. And an error signal is output to the display unit in the judgment that the short circuit has occurred. The method of claim 4, wherein The display unit, And a light emitting diode which maintains an off state when the normal signal is input from the short discriminator and emits light when the error signal is input from the short discriminator. A liquid crystal display panel having a plurality of pixels including a storage capacitor receiving a storage voltage through a storage line and a common electrode receiving a common voltage through a common voltage line; A comparison unit comparing the magnitudes of the storage voltage and the common voltage; A short determination unit determining whether the common voltage line and the storage line are short by using the comparison result of the comparison unit; And And a display unit for displaying whether the common voltage line and the storage line are shorted according to a determination result of the short discrimination unit. The method of claim 6, The comparison unit, And a comparator for comparing the magnitude of the storage voltage input to the inverting input terminal and the common voltage input to the non-inverting input terminal and outputting a comparison result to the short discrimination unit connected to the output terminal. The method of claim 7, wherein And the comparator outputs a low signal to the short discriminator when the magnitude of the storage voltage and the common voltage are different, and outputs a high signal to the short discriminator when the magnitude of the storage voltage and the common voltage are the same. The method of claim 8, The short determiner determines that the common voltage line and the storage line are not shorted when the low signal is input from the comparator, and outputs a normal signal to the display unit. When the high signal is input from the comparator, the common voltage line and the storage line. And an error signal is output to the display unit in the judgment that the short circuit has occurred. The method of claim 9, The display unit, And a light emitting diode which maintains an off state when the normal signal is input from the short discriminator and emits light when the error signal is input from the short discriminator. In the inspection method of a liquid crystal display device having a liquid crystal display panel formed with a plurality of pixels having a storage capacitor receiving a storage voltage through a storage line and a common electrode receiving a common voltage through a common voltage line, Comparing magnitudes of the storage voltage and the common voltage; Determining whether the common voltage line and the storage line are short by using the comparison result; And And determining whether the common voltage line and the storage line are short based on the short discrimination result. The method of claim 11, The comparing step, Comparing magnitudes of the storage voltage and the common voltage; Generating a low signal if the storage voltage is different from the common voltage as a result of the comparison; And And generating a high signal if the storage voltage and the common voltage have the same magnitude as a result of the comparison. The method of claim 12, The determining step, When the low signal is generated, determining that the common voltage line and the storage line are not shorted and generating a normal signal; And And when the high signal is generated, determining that the common voltage line and the storage line are short and generating an error signal. The method of claim 13, The display step, Maintaining an unlit state when the normal signal is generated; And And turning on the error signal when the error signal is generated.

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