CN1564060A - Liquid crystal display panel protection circuit and liquid crystal display - Google Patents

Abstract

A liquid crystal display panel protection circuit is suitable for a liquid crystal display panel. The liquid crystal display panel includes a plurality of display cells respectively connected between the data electrodes, the gate electrodes, and the common electrode. A switching device having a first terminal connected to at least one of the data electrode and the gate electrode, and a second terminal, the switching device being turned on when a level of one of the first terminal and the second terminal exceeds a threshold voltage level. The ESD protection device is connected between the second terminal of the switch device and the common electrode, and has a capacitive load and a resistive load.

Description

LCD panel holding circuit and LCD

Technical field

The present invention is relevant for a kind of LCD and holding circuit thereof, particularly relevant for a kind of LCD panel holding circuit and LCD with Electrostatic Discharge protection circuit.

Background technology

At present conventional LCD comprised a plurality of pixels (pixel) of lining up the array shape, the voltage that applies that the liquid crystal in each pixel is subjected on it is controlled, and can change the transmissivity of liquid crystal, to show required gray scale on the screen.

Fig. 1 represents the schematic equivalent circuit of conventional LCD panel (liquid crystal display panel is hereinafter to be referred as the LCD panel) and peripheral drive circuit thereof.As shown in the figure, on the LCD panel 1 be by crisscross data electrode (with D1, D2 ... Dm represents) with gate electrode (with G1, G2 ... Gn represents) be interwoven, staggered data electrode and the gate electrode of each group can be used for controlling a display unit (display unit), and for example data electrode D1 and gate electrode G1 can be used for controlling display unit 100.As shown in the figure, the equivalent electrical circuit of each display unit mainly comprise control data enter the thin film transistor (TFT) of usefulness (Q11-Q1m, Q21-Q2m ..., Qn1-Qnm) and memory capacitance (C11-C1m, C21-C2m ..., Cn1-Cnm).The grid of thin film transistor (TFT) is connected gate electrode (G1-Gn) and data electrode (D1-Dm) respectively with drain electrode, by the sweep signal on the gate electrode (G1-Gn), can conducting turn-off all thin film transistor (TFT)s in the same delegation (that is same sweep trace), whether can be written in the corresponding display unit with the vision signal (video signal) on this control data electrode (D1-Dm).And memory capacitance to be connected to corresponding thin film transistor (TFT) and voltage level be thecommon electrode 14 of common electrode voltage VCOM.

In addition, in Fig. 1, express the driving circuit section of LCD panel 1 simultaneously.Gate drivers (gate driver) 10 be according to set scanning sequency, send each gate electrode G1, G2 ..., the sweep signal on the Gn.When being loaded with sweep signal on a certain gate electrode, can make with being conducting state in the delegation or with the thin film transistor (TFT) in online all display units of one scan.When a certain sweep trace was selected,data driver 12 was according to view data to be shown, via data electrode D1, D2 ... Dm, send corresponding vision signal to m display unit of these row.Aftergate drivers 10 is finished once the online scan operation of all n line scannings, i.e. the display operation of single frame (frame) is finished in expression.Therefore, each sweep trace of multiple scanning and send vision signal just can reach the purpose of continuous display image.Wherein, signal CTR represents the scan control information thatgate drivers 10 is received; Signal LD represents data latching (latch) signal ofdata driver 12, and signal DATA then represents input image information.

Generally data electrode D1, D2 ..., the vision signal that transmitted on the Dm, relation according to using together between the electrode voltage VCOM can be divided into two kinds of positive video signal (positive video signal) and negative video signals (negative video signal).Positive video signal is meant that its current potential is higher than common electrode voltage VCOM, and has corresponding voltage level, general healing near common electrode voltage VCOM person corresponding to lower gray-scale value according to the gray-scale value difference of its representative.Relatively, negative video signal is meant that its current potential is lower than common electrode voltage VCOM, and has corresponding voltage level according to the gray-scale value difference of its representative.Similarly, heal near common electrode voltage VCOM person corresponding to lower gray-scale value.When same gray-scale value was represented with positive video signal and negative video signal respectively, display effect was the same in principle, but some difference in fact still.In addition, be subjected to single polarity electric field bias constantly, cause the liquid crystal molecule life-span to shorten, so the single display unit can receive the vision signal of opposite polarity respectively when odd-numbered frame and even frame in order to prevent liquid crystal molecule.

In the manufacture process of LCD panel, the glass substrate of insulation exists the problem that static discharge disturbs.The existence of static discharge can cause the impaired of LCD panel circuit.Therefore, in the design of circuit, the design that must add buffering ESD voltage just can be avoided the destruction of ESD.

United States Patent (USP) numbering 6,175,394 discloses a kind of LCD panel of the ESD of having protection circuit.The ESD protection circuit is connected between gate electrode or data electrode and the protective ring, and it is the thin film transistor (TFT) of a grid suspension joint.

United States Patent (USP) numbering 6,493,047 discloses a kind of LCD panel of the ESD of having protection circuit.The control end that the ESD protection circuit has a switchgear and is coupled to switchgear is connected between gate electrode or data electrode and the common electrode.

Conventional art is to add the design of a short-circuited conducting sleeve 15 (short ring), so that the ESD electric current is released intocommon electrode 14 via short-circuited conducting sleeve between the gate electrode and data electrode andcommon electrode 14 of LCD panel.

Fig. 2 is the circuit diagram that shows traditional short-circuited conducting sleeve 15.Short-circuited conducting sleeve comprises positive terminal and negative pole end twodiodes 16 and 18 that join inverting each other, and the tie point of the positive terminal ofdiode 16 and 18 and negative pole end is connected to gate electrode (G1-Gn) and data electrode (D1-Dm) leads on the circuit paths ofdisplay unit 100 and between the common electrode 14.When the voltage level of gate electrode (G1-Gn) or data electrode (D1-Dm) surpasses the forward voltage ofdiode 16 because ESD intensifies, thendiode 16 conductings, so the ESD electric current of gate electrode (G1-Gn) or data electrode (D1-Dm) flow tocommon electrode 14 via thediode 16 of conducting.Because the volume ofcommon electrode 14 is bigger, is enough to bear described ESD electric current, therefore can avoiddisplay unit 100 to be subjected to the destruction of ESD electric current, reach the purpose that ESD protects.

Yet in the manufacture process of LCD panel, the source of esd event also may take place in common electrode 14.When esd event took place oncommon electrode 14, a large amount of ESD electric currents flow to displayunit 100 with conductingdiode 18, and therefore traditional short-circuited conductingsleeve 15 and can't preventing is originated and is the esd event of the common electrode destruction to display unit.In addition, conventional art is considered ascommon electrode 14 electrical ground, yet in fact common electrode itself is also unearthed, and therefore the magnitude of current that can load is limited, when the ESD electric current is big, the danger of re-injection to other signal circuit is arranged.

Summary of the invention

In view of this, in order to solve described problem, fundamental purpose of the present invention is to provide a kind of LCD panel protection circuit, and a buffer circuit is set between short-circuited conducting sleeve and common electrode, can slow down the influence that esd event changes the display unit circuit level.

For realizing described purpose, the present invention proposes a kind of LCD panel holding circuit, is suitable for LCD panel.LCD panel comprises display unit, is connected between data electrode, gate electrode and the common electrode.Switchgear, have be connected to data electrode with gate electrode at least one first end, and second end, when the level of one in first end and second end surpasses threshold voltage levels, then switchgear conducting.Electrostatic discharge protective device is connected between second end and common electrode of switchgear, has capacity load and resistive load.

Moreover the present invention proposes a kind of LCD.LCD panel comprises a plurality of display units, is connected between the corresponding a plurality of data electrodes and a plurality of gate electrode and common electrode.Gate drivers is in order to send sweep signal to gate electrode.Data driver in order to outputting video signal to data electrode.A plurality of switchgears have first end that is connected to corresponding data electrode respectively, and second end, when the level of one in first end and second end surpasses threshold voltage levels, and then switchgear conducting.Electrostatic discharge protective device is connected between second end and common electrode of switchgear, has capacity load and resistive load.

Description of drawings

For described purpose of the present invention, feature and advantage can be become apparent, a preferred embodiment cited below particularly, and conjunction with figs. are described in detail as follows:

Fig. 1 represents the schematic equivalent circuit of conventional tft liquid crystal display board and peripheral drive circuit thereof.

Fig. 2 is the circuit diagram of the traditional short-circuited conducting sleeve of expression.

Fig. 3 is the schematic equivalent circuit of expression according to the described LCD of the embodiment of the invention.

Fig. 4 is the circuit diagram of expression according to described switchgear 26,27 of the embodiment of the invention and ESD protection circuit 28.

Symbol description:

1,3-LCD panel

10,20-gate drivers

12,22-data driver

14,24-common electrode

15～short-circuited conducting sleeve

26,27～switchgear

16,18,261,262～diode

28～ESD protection circuit

100,200-display unit

281～resistive load

282～capacity load

2611,2621～positive terminal

2612,2622～negative pole end

A～first end

B～second end

C11-C1m, C21-C2m ..., Cn1-Cnm～memory capacitance

D1, D2 ... Dm～data electrode

G1, G2 ... Gn～gate electrode

Q11-Q1m, Q21-Q2m ..., Qn1-Qnm～thin film transistor (TFT)

VCOM～common electrode voltage

Embodiment

Embodiment:

Fig. 3 is the schematic equivalent circuit of expression according to the described LCD of the embodiment of the invention.As shown in the figure, LCD panel 3 be by crisscross data electrode (with D1, D2 ... Dm represents) with gate electrode (with G1, G2 ... Gn represents) be interwoven, staggered data electrode and the gate electrode of each group can be used for controlling a display unit (display unit), and for example data electrode D1 and gate electrode G1 can be used for controlling display unit 200.As shown in the figure, the equivalent electrical circuit of each display unit mainly comprise control data enter the thin film transistor (TFT) of usefulness (Q11-Q1m, Q21-Q2m ..., Qn1-Qnm) and memory capacitance (C11-C1m, C21-C2m ..., Cn1-Cnm).The grid of thin film transistor (TFT) is connected gate electrode (G1-Gn) and data electrode (D1-Dm) respectively with drain electrode, by the sweep signal on the gate electrode (G1-Gn), can conducting turn-off all thin film transistor (TFT)s in the same delegation (that is same sweep trace), whether can be written in the corresponding display unit with the vision signal (video signal) on this control data electrode (D1-Dm).And memory capacitance to be connected to corresponding thin film transistor (TFT) and voltage level be the common electrode 24 of common electrode voltage VCOM.

In addition, in Fig. 3, express the driving circuit section of LCD panel 3 simultaneously.Gate drivers (gate driver) the 20th, according to set scanning sequency, send each gate electrode G1, G2 ..., the sweep signal on the Gn.When being loaded with sweep signal on a certain gate electrode, can make with being conducting state in the delegation or with the thin film transistor (TFT) in online all display units of one scan.When a certain sweep trace was selected, data driver 22 was according to view data to be shown, via data electrode D1, D2 ... Dm, send corresponding vision signal to m display unit of these row.After gate drivers 20 is finished once the online scan operation of all n column scans, i.e. the display operation of single frame (frame) is finished in expression.Therefore, each sweep trace of multiple scanning and send vision signal just can reach the purpose of continuous display image.Wherein, signal CTR represents the scan control information that gate drivers 20 is received; Signal LD represents data latching (latch) signal of data driver 22, and signal DATA then represents input image information.

In order to prevent in the ESD of data electrode, gate electrode or common electrode electric current to the damage that display unit caused, LCD according to the present invention in common electrode and data electrode with and gate electrode between added the design of switchgear (traditional short-circuited conducting sleeve) 26,27 and ESD protection circuit 28.

Fig. 4 is the circuit diagram of expression according to described switchgear 26,27 of the embodiment of the invention and ESD protection circuit 28.Switchgear 26 has the first end A and the one second end B that is connected to each data electrode (D1-Dm) and gate electrode (G1-Gn), and switchgear 27 (master switch device) is connected between each switchgear 26 and the ESD protection circuit 28.According to the embodiment of the invention, switchgear 26 is identical with 27 circuit structure, is all a two-way current-limiting apparatus, comprises diode 261 and 262.

The positive terminal 2611 of diode 261 is connected to the negative pole end 2622 of diode 262, and the negative pole end 2612 of diode 261 is connected to the positive terminal 2621 of diode 262.The positive terminal 2611 of diode 261 is the first end A with the tie point of the negative pole end 2622 of diode 262, and the tie point of the positive terminal 2621 of the negative pole end 2612 of diode 261 and diode 262 is the second end B.The first end A and the second end B are connected to gate electrode (G1-Gn) and data electrode (D1-Dm) leads on the circuit paths of display unit 200 and between the ESD protection circuit 28.

After positive terminal 2611,2621 voltage levels that received of diode 261 and 262 1 surpassed the threshold voltage of diode, then diode 261 or 262 will conducting.In addition, ESD protection circuit 28 comprises parallel resistor load 281 and capacity load 282, is connected between switchgear 27 and the common electrode 24.

When esd pulse appears at data electrode (D1-Dm), gate electrode (G1-Gn) or common electrode 24, on the current path that switchgear 26,27 and ESD protection circuit 28 are constituted, esd pulse can be earlier to capacity load 282 chargings, therefore the current path that only has small part ESD electric current to be constituted by switchgear 26,27 and ESD protection circuit 28 via resistive load 281, subsequently capacity load 282 again slow release be stored in this energy.Therefore, when esd pulse appears at common electrode 24, can prolong esd pulse enters display unit 200 via data electrode or gate electrode time, effectively reduce the moment ESD magnitude of current that enters display unit 200 and data electrode or gate electrode, reached the peripheral driving circuit of protective liquid crystal display 3 and the purpose of inner display unit.Moreover, when if esd pulse appears at data electrode (D1-Dm) or gate electrode (G1-Gn), esd pulse can be released into common electrode 24 via the current path that switchgear 26,27 and ESD protection circuit 28 are constituted equally, has the ESD protection effect identical with conventional art.

Moreover, if esd pulse is excessive, may cause capacity load 282 to damage, this moment, LCD panel still can continue operation, but ESD protection circuit 28 may lose the ESD safeguard function, so circuit designers need design the capacity load of suitable ESD ability to bear.

Moreover, when LCD panel is carried out general operation, because the level of common electrode 24 is kept a fixed voltage, under the situation of fixing DC level, the effect of capacity load is not obvious, the usefulness in the time of therefore can not having influence on LCD panel 3 and carry out general operations.

According to the described ESD protection circuit of the embodiment of the invention, moment ESD electric current in the time of can avoiding esd event takes place or ESD change in voltage are to the impact of internal circuit, and no matter esd event betides data electrode (D1-Dm) or gate electrode (G1-Gn), or common electrode 24, all have the effect that ESD protects, effectively solved the problem of conventional art.In addition, employed protection circuit in the embodiment of the invention, not needing on the implementation increases too many assembly, is very suitable for the utilization of industry.

In sum; though the present invention with a preferred embodiment openly as above; right its is not in order to limit the present invention; any those skilled in the art; under the situation that does not break away from the spirit and scope of the present invention; can carry out various changes and modification, so protection scope of the present invention is as the criterion when looking the claim restricted portion that is proposed.

Claims (16)

Translated fromChinese

1.一种液晶显示板保护电路，适用一液晶显示板，所述液晶显示板包含一显示单元，连接在一数据电极、一栅极电极以及一共用电极之间，所述液晶显示板保护电路包括：1. A liquid crystal display panel protection circuit is suitable for a liquid crystal display panel, and the liquid crystal display panel includes a display unit connected between a data electrode, a grid electrode and a common electrode, and the liquid crystal display panel protection circuit include:一开关装置，具有连接到所述数据电极以与栅极电极中的至少一者的一第一端，以及一第二端，当所述第一端以及第二端中的一者的电平超过一阈值电压电平时，则所述开关装置导通；以及A switching device having a first end connected to at least one of the data electrode and the gate electrode, and a second end, when the level of one of the first end and the second end is when a threshold voltage level is exceeded, the switching device is turned on; and一静电放电防护装置，连接在所述开关装置的第二端以及所述共用电极之间，具有一电容性负载以及一电阻性负载。An electrostatic discharge protection device, connected between the second end of the switch device and the common electrode, has a capacitive load and a resistive load.2.如权利要求1所述的液晶显示板保护电路，其中所述开关装置为一双向限流装置。2. The liquid crystal display panel protection circuit as claimed in claim 1, wherein the switching device is a bidirectional current limiting device.3.如权利要求1所述的液晶显示板保护电路，其中所述开关装置包括：3. The liquid crystal display panel protection circuit as claimed in claim 1, wherein said switching device comprises:一第一二极管，具有一第一正极端以及一第一负极端；以及a first diode having a first positive terminal and a first negative terminal; and一第二二极管，具有连接到所述一第一正极端的第二负极端以及连接到所述第一负极端的第二正极端，其中所述第一正极端以及第二负极端的连接点为所述第一端，而所述第一负极端以及第二正极端的连接点为所述第二端。a second diode having a second negative terminal connected to the first positive terminal and a second positive terminal connected to the first negative terminal, wherein the first positive terminal and the second negative terminal The connection point is the first terminal, and the connection point between the first negative terminal and the second positive terminal is the second terminal.4.如权利要求1所述的液晶显示板保护电路，其中所述电容性负载连接在所述开关装置以及所述共用电极之间。4. The liquid crystal display panel protection circuit as claimed in claim 1, wherein the capacitive load is connected between the switching device and the common electrode.5.如权利要求4所述的液晶显示板保护电路，其中所述电阻性负载连接到所述电容性负载的两端。5. The liquid crystal display panel protection circuit according to claim 4, wherein the resistive load is connected to both ends of the capacitive load.6.一种液晶显示器，包括：6. A liquid crystal display, comprising:一液晶显示板，包括多个显示单元，分别连接在对应的多个数据电极和多个栅极电极以及一共用电极之间；A liquid crystal display panel, including a plurality of display units, respectively connected between a plurality of corresponding data electrodes, a plurality of grid electrodes and a common electrode;一栅极驱动器，用以送出扫描信号至所述栅极电极；a gate driver, used to send a scan signal to the gate electrode;一数据驱动器，用以输出视频信号至所述数据电极；a data driver for outputting video signals to the data electrodes;多个开关装置，分别具有连接到对应的所述数据电极的一第一端，以及一第二端，当所述第一端以及第二端中的一者的电平超过一阈值电压电平时，则所述开关装置导通；以及A plurality of switch devices, respectively having a first terminal connected to the corresponding data electrode, and a second terminal, when the level of one of the first terminal and the second terminal exceeds a threshold voltage level , the switching device is turned on; and一静电放电防护装置，连接在所述开关装置的第二端以及所述共用电极之间，具有一电容性负载以及一电阻性负载。An electrostatic discharge protection device, connected between the second end of the switch device and the common electrode, has a capacitive load and a resistive load.7.如权利要求6所述的液晶显示器，其中所述开关装置为一双向限流装置。7. The liquid crystal display as claimed in claim 6, wherein the switching device is a bi-directional current limiting device.8.如权利要求7所述的液晶显示器，其中所述开关装置包括：8. The liquid crystal display of claim 7, wherein said switch means comprises:一第一二极管，具有一第一正极端以及一第一负极端；以及a first diode having a first positive terminal and a first negative terminal; and一第二二极管，具有连接到所述一第一正极端的第二负极端以及连接到所述第一负极端的第二正极端，其中所述第一正极端以及第二负极端的连接点为所述第一端，而所述第一负极端以及第二正极端的连接点为所述第二端。a second diode having a second negative terminal connected to the first positive terminal and a second positive terminal connected to the first negative terminal, wherein the first positive terminal and the second negative terminal The connection point is the first terminal, and the connection point between the first negative terminal and the second positive terminal is the second terminal.9.如权利要求6所述的液晶显示器，还包括一总开关装置，连接在所述开关装置的第二端以及所述静电放电防护装置之间。9. The liquid crystal display as claimed in claim 6, further comprising a main switch device connected between the second terminal of the switch device and the electrostatic discharge protection device.10.如权利要求6所述的液晶显示器，其中所述电容性负载连接在所述开关装置以及所述共用电极之间。10. The liquid crystal display of claim 6, wherein the capacitive load is connected between the switching device and the common electrode.11.如权利要求10所述的液晶显示器，其中所述电阻性负载连接到所述电容性负载的两端。11. The liquid crystal display of claim 10, wherein the resistive load is connected to both ends of the capacitive load.12.一种液晶显示器，包括：12. A liquid crystal display comprising:一液晶显示板，包括多个显示单元，分别连接对应的多个数据电极和多个栅极电极以及一共用电极之间；A liquid crystal display panel, including a plurality of display units, respectively connected between a plurality of corresponding data electrodes, a plurality of grid electrodes and a common electrode;一栅极驱动器，用以送出扫描信号至所述栅极电极；a gate driver, used to send a scan signal to the gate electrode;一数据驱动器，用以输出视频信号至所述数据电极；a data driver for outputting video signals to the data electrodes;多个开关装置，分别具有连接到对应的所述数据电极以与栅极电极的一第一端，以及一第二端，当所述第一端以及第二端中的一者的电平超过一阈值电压电平时，则所述开关装置导通；以及A plurality of switching devices, each having a first terminal connected to the corresponding data electrode and gate electrode, and a second terminal, when the level of one of the first terminal and the second terminal exceeds a threshold voltage level, the switching device is turned on; and一静电放电防护装置，连接在所述开关装置的第二端以及所述共用电极之间，包括一电容性负载以及一电阻性负载。An electrostatic discharge protection device, connected between the second end of the switch device and the common electrode, includes a capacitive load and a resistive load.13.如权利要求12所述的液晶显示器，其中所述开关装置为一双向限流装置。13. The liquid crystal display of claim 12, wherein the switching device is a bi-directional current limiting device.14.如权利要求13所述的液晶显示器，其中所述开关装置包括：14. The liquid crystal display of claim 13, wherein said switch means comprises:一第一二极管，具有一第一正极端以及一第一负极端；以及a first diode having a first positive terminal and a first negative terminal; and一第二二极管，具有连接到所述一第一正极端的第二负极端以及连接到所述第一负极端的第二正极端，其中所述第一正极端以及第二负极端的连接点为所述第一端，而所述第一负极端以及第二正极端的连接点为所述第二端。a second diode having a second negative terminal connected to the first positive terminal and a second positive terminal connected to the first negative terminal, wherein the first positive terminal and the second negative terminal The connection point is the first terminal, and the connection point between the first negative terminal and the second positive terminal is the second terminal.15.如权利要求12所述的液晶显示器，还包括一总开关装置，连接在所述开关装置的第二端以及所述静电放电防护装置之间。15. The liquid crystal display as claimed in claim 12, further comprising a main switch device connected between the second terminal of the switch device and the electrostatic discharge protection device.16.如权利要求12所述的液晶显示器，其中所述电容性负载连接在所述开关装置以及所述共用电极之间。16. The liquid crystal display of claim 12, wherein the capacitive load is connected between the switching device and the common electrode.17.如权利要求12所述的液晶显示器，其中所述电阻性负载连接到所述电容性负载的两端。17. The liquid crystal display of claim 12, wherein the resistive load is connected to both ends of the capacitive load.

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