CN100487542C - Common voltage regulating circuit and liquid crystal display panel - Google Patents

Abstract

The invention provides a common voltage regulating circuit, which is suitable for a liquid crystal display panel, wherein the liquid crystal display panel is provided with a plurality of display units, and each display unit is coupled to a common electrode. The common voltage regulating circuit includes at least: the digital-to-analog converter comprises a first buffer, a second buffer, a first digital-to-analog converter, a second digital-to-analog converter and a regulator. The common voltage regulating circuit regulates the DC voltage and the AC voltage of the common voltage in a programming mode and transmits the regulated common voltage to the common electrode.

Description

Common voltage regulating circuit and display panels

Technical field

The present invention is applicable to display panels relevant for a kind of common voltage regulating circuit, utilizes programming mode to regulate common voltage, can save external module and increase governing speed.

Background technology

Fig. 1 represents the schematic equivalent circuit of Thin Film Transistor-LCD (thinfilm transistor liquid crystaldisplay is hereinafter to be referred as TFT-LCD).As shown in the figure, be (with D11, D12, D13 on the liquidcrystal display array 1 by parallel crisscross data line at least in twos ... Dly represents) and sweep trace (with G11, G12, G13 ... G1x represents), each staggered data line and sweep trace then forms a display unit (Di splay unit pixel), for example thecorresponding display unit 100 of data line D11 and sweep trace G11.As shown in the figure, the equivalent electrical circuit of display unit 100 (other display unit is also identical) comprises thin film transistor (TFT) 10, memory capacitance Cs10 and the liquid crystal capacitance C1c10 that controls usefulness.Wherein, the end of liquid crystal capacitance C1c10 is coupled to common electrode.

Generally at data line (D11, D12, D13 ... D1y) vision signal that is transmitted on, the relation between the common voltage VCOM of foundation and common electrode can be divided into two kinds of positive video signal and negative video signals.As shown in Figure 2, common voltage VCOM can be divided into two voltage Vcdc and Vcac, and wherein voltage Vcdc is the DC voltage of common voltage VCOM, and voltage Vcac is the alternating voltage of common voltage VCOM.If voltage Vcdc and Vcac are not adjusted to suitable value, can cause the vision signal mistake of display unit, and can't show correct picture.

Fig. 3 is the regulatingcircuit 30 of the conventional common voltage of expression.The resistance value of wherein regulatingvariohm 301 can change the level of DC voltage Vcdc, and the resistance value of regulatingvariohm 302 can change the amplitude of alternating voltage Vcac, and then is adjusted to suitable common voltage VCOM.Because the regulatingcircuit 30 of conventional common electrode voltage is for being arranged at the outside line outside the TFT-LCD panel, so increased the area and the cost of manufacture of printed circuit board (PCB).In addition,variable resistor 301 and 302 is regulated by manual type, and its adjusting time is long and do not meet economic benefit.

Summary of the invention

In view of this, in order to address the above problem, fundamental purpose of the present invention is to provide a kind of the present invention relevant for a kind of common voltage regulating circuit, is applicable to LCD.

For realizing above-mentioned purpose, the present invention proposes a kind of common voltage regulating circuit, is applicable to display panels, and this display panels has a plurality of display units, and each this display unit is coupled to common electrode.This common voltage regulating circuit comprises at least: first buffer, second buffer, first digital analog converter, second digital analog converter and regulator.First buffer is stored a plurality of DC digital data, and according to first indicator signal, the DC digital data that output is corresponding.Second buffer is stored a plurality of ac digital data, and according to second indicator signal, the ac digital data that output is corresponding.First and second digital analog converter is converted to first and second numerical value with direct current and the ac digital data that receive respectively.Regulator is coupled to first and second digital analog converter, in order to according to first and second numerical value regulating corresponding first voltage signal and second voltage signal respectively, and output first and second voltage signal after regulating.Wherein, first voltage signal is the d. c. voltage signal with a magnitude of voltage, and this magnitude of voltage changes according to first numerical value; Second voltage signal is the ac voltage signal with an amplitude, and this amplitude changes according to second value.

Description of drawings

For above-mentioned 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 display panels.

Fig. 2 represents the common voltage signal.

Fig. 3 represents the regulating circuit of conventional common voltage.

Fig. 4 represents the display panels of regulating the common voltage circuit that has of the present invention.

Fig. 5 represents common voltage regulating circuit of the present invention.

Symbol description:

1,41～liquid crystal display array; 2,42～data driver; 3,43～scanner driver; 10,40～thin film transistor (TFT); 50～common voltage regulating circuit; 100,400～display unit; 301,302～variohm; 500a, 500b～buffer; 501a, 501b～digital analog converter; 502～regulator; 503～compositor; 504～amplifier; Clcl0, Clc40～liquid crystal capacitance; Cs10, Clc40～memory capacitance; D11, D12, D13 ... D1y～data line; D41, D42, D43 ... D4y～data line; G11, G12, G13 ... G1x～sweep trace; G41, G42, G43 ... G4x～sweep trace;

Embodiment

Fig. 4 has the display panels of regulating the common voltage circuit for expression is of the present invention.Each staggered data line and sweep trace then forms a display unit (Display unit pixel), for example thecorresponding display unit 400 of data line D41 and sweep trace G41.As shown in the figure, the equivalent electrical circuit of display unit 400 (other display unit is also identical) comprises thin film transistor (TFT) 40, memory capacitance Cs40 and the liquid crystal capacitance C1c10 that controls usefulness.Wherein, the end of liquid crystal capacitance C1c10 couples the common electrode with common voltage VCOM.Commonvoltage regulating circuit 50 of the present invention is set, in order to regulate common voltage VCOM inscanner driver 43.

Fig. 5 is expression common voltage regulating circuit of the present invention.Commonvoltage regulating circuit 50 comprisesbuffer 500a and 500b, digitalanalog converter 501a and 501b,regulator 502,compositor 503 and amplifier 504.Wherein,buffer 500a stores a plurality of DC digital data and receives indicator signal S1a, andbuffer 500a exports corresponding DC digital data S2a according to indicator signal S1a.Buffer 500b stores a plurality of ac digital data and receives indicator signal S1b, andbuffer 500b exports corresponding ac digital data S2b according to indicator signal S1b.Digitalanalog converter 501a is coupled tobuffer 500a, and the DC digital data S2a that receives is converted to numerical value S3a.Digitalanalog converter 501b is coupled tobuffer 500b, and the ac digital data S2b that receives is converted to numerical value S3b.

Then,regulator 502 reception value S3a and S3b, and according to this numerical value S3a and S3b to regulate corresponding voltage signal S4a and S4b respectively, wherein, voltage signal S4a is the d. c. voltage signal with a magnitude of voltage, and this magnitude of voltage changes according to numerical value S3a; Voltage signal s4b is the ac voltage signal with an amplitude, and this amplitude changes according to numerical value S3b.

Voltage signal S4a and S4b are received bycompositor 503, andcompositor 503 synthesizes voltage signal S5 with voltage signal S4a and S4b.Then, voltage signal S5 inputs toamplifier 504, and becomes common voltage VCOM via the amplifieroperation ofamplifier 504, and exports common electrode to byamplifier 504.

In an embodiment of the present invention, common voltage regulatingcircuit 50 is arranged in thescanner driver 43, yet in the application of reality, common voltage regulatingcircuit 50 also can be arranged in the data driver 42.Moreover the value of above-mentioned setting buffer (500a and 500b) is set by I2C (3-wire) bus.Because the transmission line of I2C bus takes up space less so not, so in common voltage regulatingcircuit 50 of the present invention, the part of sequencing utilizes the I2C bus to be controlled.

Commonvoltage regulating circuit 50 of the present invention is in order to regulate DC voltage Vcdc and the alternating voltage Vcac of common voltage VCOM.When the user uses LCD screen, when perhaps testing flicker value, find that film flicker is big, can utilize common voltage regulatingcircuit 50 easily by programming mode, be appropriate voltage to regulate DC voltage Vcdc and alternating voltage Vcac, and then reduce film flicker.

In sum, common voltage regulating circuit of the present invention is arranged in the gate drivers or data driver of LCD, can reduce external module; And utilize program to regulate common voltage, can increase the speed of adjusting and improve the degree of accuracy of regulating.

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 (6)

Translated fromChinese

1.一种共用电压调节电路，适用于一液晶显示面板，该液晶显示面板具有多个显示单元，且每一该显示单元耦接于一共用电极，而该共用电压调节电路至少包括：1. A common voltage regulating circuit, suitable for a liquid crystal display panel, the liquid crystal display panel has a plurality of display units, and each of the display units is coupled to a common electrode, and the common voltage regulating circuit at least includes:一第一缓存器，用以存储多个直流数字数据，根据一第一指示信号，输出一对应的该直流数字数据；A first register for storing a plurality of DC digital data, and outputting a corresponding DC digital data according to a first indication signal;一第二缓存器，用以存储多个交流数字数据，根据一第二指示信号，输出一对应的交流数字数据；A second register for storing a plurality of AC digital data, and outputting a corresponding AC digital data according to a second indication signal;一第一数字模拟转换器，将接收的该直流数字数据转换为一第一数值；a first digital-to-analog converter, converting the received DC digital data into a first value;一第二数字模拟转换器，将接收的该交流数字数据转换为一第二数值；a second digital-to-analog converter, converting the received AC digital data into a second value;一调节器，耦接于该第一及第二数字模拟转换器，根据该第一及第二数值以分别调节对应的一第一电压信号及第二电压信号，并输出调节后的该第一及第二电压信号，其中，该第一电压信号为具有一电压值的直流电压信号，且该电压值根据该第一数值而改变，该第二电压信号为具有一幅值的交流电压信号，且该幅值根据该第二数值而改变；A regulator, coupled to the first and second digital-to-analog converters, respectively adjusts a corresponding first voltage signal and a second voltage signal according to the first and second values, and outputs the adjusted first and a second voltage signal, wherein the first voltage signal is a DC voltage signal with a voltage value, and the voltage value changes according to the first value, and the second voltage signal is an AC voltage signal with an amplitude, and the magnitude varies according to the second value;一合成器，耦接于该调节器，用以将该第一与第二电压信号合成为一共用电压；以及a synthesizer, coupled to the regulator, for synthesizing the first and second voltage signals into a common voltage; and一放大器，耦接于该合成器，用以放大该共用电压的电压值，并且提供该共用电压至该共用电极。An amplifier, coupled to the synthesizer, is used to amplify the voltage value of the common voltage and provide the common voltage to the common electrode.2.如权利要求1所述的共用电压调节电路，其中，该液晶显示面板包括一栅极驱动器，且该共用电压调节电路设置于该栅极驱动器。2. The common voltage regulating circuit as claimed in claim 1, wherein the liquid crystal display panel comprises a gate driver, and the common voltage regulating circuit is disposed on the gate driver.3.如权利要求1所述的共用电压调节电路，其中，该液晶显示面板包括一数据极驱动器，且该共用电压调节电路设置于该数据极驱动器。3. The common voltage regulating circuit as claimed in claim 1, wherein the liquid crystal display panel comprises a data electrode driver, and the common voltage regulating circuit is disposed on the data electrode driver.4.一种液晶显示面板，至少包括：4. A liquid crystal display panel, comprising at least:一栅极驱动器；a gate driver;一数据驱动器：A data driver:多个显示单元，形成于该面板内，且每一该显示单元耦接于一共用电极；以及A plurality of display units are formed in the panel, and each display unit is coupled to a common electrode; and一共用电压调节电路；a common voltage regulation circuit;该共用电压调节电路包括：The common voltage regulation circuit includes:一第一缓存器，用以存储多个直流数字数据，根据一第一指示信号，输出对应的该直流数字数据；A first register for storing a plurality of DC digital data, and outputting the corresponding DC digital data according to a first indication signal;一第二缓存器，用以存储多个交流数字数据，根据一第二指示信号，输出对应的该交流数字数据；A second register for storing a plurality of AC digital data, and outputting the corresponding AC digital data according to a second indication signal;一第一数字模拟转换器，将接收的该直流数字数据转换为一第一数值；a first digital-to-analog converter, converting the received DC digital data into a first value;一第二数字模拟转换器，将接收的该交流数字数据转换为一第二数值；a second digital-to-analog converter, converting the received AC digital data into a second value;一调节器，耦接于该第一及第二数字模拟转换器，根据该第一及第二数值以分别调节对应的一第一电压信号及第二电压信号，并输出调节后的该第一及第二电压信号，其中，该第一电压信号为具有一电压值的直流电压信号，且该电压值根据该第一数值而改变，该第二电压信号为具有一幅值的交流电压信号，且该幅值根据该第二数值而改变；A regulator, coupled to the first and second digital-to-analog converters, respectively adjusts a corresponding first voltage signal and a second voltage signal according to the first and second values, and outputs the adjusted first and a second voltage signal, wherein the first voltage signal is a DC voltage signal with a voltage value, and the voltage value changes according to the first value, and the second voltage signal is an AC voltage signal with an amplitude, and the magnitude varies according to the second value;一合成器，耦接于该调节器，用以将该第一与第二电压信号合成为一共用电压；以及a synthesizer, coupled to the regulator, for synthesizing the first and second voltage signals into a common voltage; and一放大器，耦接于该合成器，用以放大该共用电压的电压值，并且提供该共用电压至该共用电极。An amplifier, coupled to the synthesizer, is used to amplify the voltage value of the common voltage and provide the common voltage to the common electrode.5.如权利要求4所述的液晶显示面板，其中，该共用电压调节电路置于该栅极驱动器内。5. The liquid crystal display panel as claimed in claim 4, wherein the common voltage regulating circuit is disposed in the gate driver.6.如权利要求4所述的液晶显示面板，其中，该共用电压调节电路置于该数据驱动器内。6. The liquid crystal display panel as claimed in claim 4, wherein the common voltage regulating circuit is disposed in the data driver.

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