CN1564075A - Common voltage regulation 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 (thin film transistor liquid crystaldisplay is hereinafter to be referred as TFT-LCD).As shown in the figure, be (with D11, D12, D13 on the liquid crystal display array 1 by parallel crisscross data line at least in twos ... D1y represents) and sweep trace (with G11, G12, G13 ... G1x represents), each staggered data line and sweep trace then forms a display unit (Display unit pixel), for example the corresponding 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 regulating variohm 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; C1c10, C1c40～liquid crystal capacitance; Cs10, C1c40～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, andregulator 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 (10)

1. a common voltage regulating circuit is applicable to a display panels, and this display panels has a plurality of display units, and each this display unit is coupled to and uses electrode altogether, and this common voltage regulating circuit comprises at least:

One first buffer in order to store a plurality of DC digital data, according to one first indicator signal, is exported these DC digital data of a correspondence;

One second buffer in order to store a plurality of ac digital data, according to one second indicator signal, is exported the ac digital data of a correspondence;

One first digital analog converter is converted to one first numerical value with these DC digital data that receive;

One second digital analog converter is converted to a second value with these ac digital data that receive;

One regulator, be coupled to this first and second digital analog converter, according to one first voltage signal and second voltage signal of this first and second numerical value with adjusting correspondence respectively, and this first and second voltage signal after the output adjusting, electricity consumption is depressed into this common electrode to provide altogether, wherein, this first voltage signal is the d. c. voltage signal with a magnitude of voltage, and this magnitude of voltage changes according to this first numerical value, this second voltage signal is the ac voltage signal with an amplitude, and this amplitude changes according to this second value.

2. common voltage regulating circuit as claimed in claim 1 also comprises:

One compositor is coupled to this regulator, in order to this first and second voltage signal is synthesized this common voltage.

3. common voltage regulating circuit as claimed in claim 2 also comprises:

One amplifier is coupled to this compositor, in order to amplify the magnitude of voltage of this common voltage.

4. common voltage regulating circuit as claimed in claim 1, wherein, this display panels comprises a gate drivers, and this common voltage regulating circuit is arranged at this gate drivers.

5. common voltage regulating circuit as claimed in claim 1, wherein, this display panels comprises a data driver, and this common voltage regulating circuit is arranged at this data driver.

6. display panels comprises at least:

One gate drivers;

One data driver:

A plurality of display units are formed in this panel, and each this display unit is coupled to and uses electrode altogether; And

Use voltage regulator circuit altogether;

This common voltage regulating circuit comprises:

One first buffer, in order to store a plurality of DC digital data, according to one first indicator signal, these DC digital data that output is corresponding;

One second buffer, in order to store a plurality of ac digital data, according to one second indicator signal, these ac digital data that output is corresponding;

One first digital analog converter is converted to one first numerical value with these DC digital data that receive;

One second digital analog converter is converted to a second value with these ac digital data that receive; And

One regulator, be coupled to this first and second digital analog converter, according to one first voltage signal and second voltage signal of this first and second numerical value with adjusting correspondence respectively, and this first and second voltage signal after the output adjusting, electricity consumption is depressed into this common electrode to provide altogether, wherein, this first voltage signal is the d. c. voltage signal with a magnitude of voltage, and this magnitude of voltage changes according to this first numerical value, this second voltage signal is the ac voltage signal with an amplitude, and this amplitude changes according to this second value.

7. display panels as claimed in claim 6, wherein this common voltage regulating circuit also comprises:

One compositor is coupled to this regulator, in order to this first and second voltage signal is synthesized this common voltage.

8. display panels as claimed in claim 7, wherein this common voltage regulating circuit also comprises:

One amplifier is coupled to this compositor, in order to amplify the magnitude of voltage of this common voltage.

9. display panels as claimed in claim 6, wherein, this common voltage regulating circuit places in this gate drivers.

10. display panels as claimed in claim 6, wherein, this common voltage regulating circuit places in this data driver.

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