CN100529923C - Leaping voltage measuring for thin film transistor liquid crystal display screen and automatic regulator for public electrode voltage - Google Patents

Abstract

The disclosed regulating device includes following parts: thin film transistor (TFT) array connected to multiple data lines and multiple grid pole lines in intercross; pixel pole connected to source pole of TFT; common pole corresponding to pixel pole; sampling part, leaping voltage measurement part, and common voltage compensation and feedback part for measuring leaping voltage. Sampling pixel poles, measuring leaping voltages from pixel poles, the invention feeds back the values of leaping voltages to common poles. The invention regulates voltages of common poles automatically. Comparing with traditional method for regulating voltages of common poles in manual mode, the invention raises production efficiency.

Description

Measure the public electrode voltages self-checking device of the leaping voltage of thin film transistor liquid crystal display screen

Technical field

This invention belongs to the liquid crystal display device field, relates in particular to the public electrode voltages self-checking device of measurement of the leaping voltage of thin film transistor liquid crystal display screen (TFT-LCD).

Background technology

In the display mode of current thin film transistor liquid crystal display screen (TFT-LCD) module, generally adopt dot matrix way to come display image.For example, if the lattice structure that piece image is resolved into 6 row 8 row has 6 * 8=48 and puts and show, for the energy display image, need can both control separately each pixel, if simply each pixel is controlled with single line, need 48 lines to add 1 ground wire so, for the display screen of smaller screen low resolution, can solve the problem that shows, but for the high-resolution display screen of large-size screen monitors, resolution for XGA has 1024 * 3 * 768=2359296 point, need so many lead-in wires in display screen, this is obviously unrealistic.In order to reduce the pin count of input signal, the array way of pressing that we will show is arranged, as shown in Figure 1.

So, the lead-in wire that is connected with the outside among Fig. 1 has only the 6+8=14 root, that is to say that pin count has dropped to 14 by 48.For the signal that can will show can be delivered to corresponding point, each row of entire image need be opened successively by the regular hour order, our said scanning just, at first give the 1st row G1 signal, then all thin film transistor (TFT)s (TFT) of the 1st row are all opened, then the S1 signal has been delivered to the first row place pixel of first row, and the signal of S2 has been delivered to the secondary series place pixel of first row, and the like; After the data of first row have been sent, turn-off the G1 signal of first row, give the 2nd row G2 a signal simultaneously, then the 1st all thin film transistor (TFT)s of row (TFT) all turn-off, and all thin film transistor (TFT)s (TFT) of the 2nd row are all opened, and the signal of S1 has just been delivered to the pixel at the 2nd row the 1st row place at this moment, and the signal of S2 has been delivered to the pixel at the 2nd row the 2nd row place, the rest may be inferred for other, and the addressing of video data is illustrated in fig. 2 shown below.

In the drives process of thin film transistor liquid crystal display screen (TFT-LCD), in order to guarantee that thin film transistor (TFT) (TFT) can provide sufficient electric current to liquid crystal display pixel in limited write time in delegation, usually need sufficiently high voltage open and guarantee thin film transistor (TFT) (TFT), generally need the high pressure of 20V-30V to be added in grid and open and guarantee thin film transistor (TFT) (TFT); In order to guarantee thin film transistor (TFT) (TFT) minimum cut-off current in the turn-off time, the voltage of use pact-5--10V is added in to turn-off on the grid and guarantees thin film transistor (TFT) (TFT) usually in addition.When guaranteeing the conducting of thin film transistor (TFT) (TFT) like this and the voltage difference in when shutoff just reach about 30-40V.

The thin film transistor (TFT) (TFT) of thin film transistor liquid crystal display screen (TFT-LCD) is to adopt large-scale voltage-controlled type field effect transistor technology to make, for very thin insulation silicon dioxide or the silicon nitride of deposit one deck between the grid of field effect transistor and the source electrode (or drain electrode), so there is a bigger electric capacity between grid and the source electrode.Guarantee thin film transistor (TFT) (TFT) when opening and turn-off to shown in the following Fig. 3 .1 of principle of the charging of liquid crystal pixel, Fig. 3 .2, Fig. 3 .3.

Fig. 3 .1 writes the circuit theory diagrams of data for guaranteeing thin film transistor (TFT) (TFT) to liquid crystal display pixel.Fig. 3 .2 and Fig. 3 .3 guarantee that thin film transistor (TFT) (TFT) is opened and the equivalent circuit diagram of liquid crystal display pixel when ending.Among Fig. 3 .2, the grid of guaranteed thin film transistor (TFT) (TFT) adds is+high pressure of 20V, and the voltage of general liquid crystal pixel is about+8-13V, assemble positive charge so guarantee capacitor C gs grid one side between the grid source electrode of thin film transistor (TFT) (TFT), and pixel electrode one end assembled negative charge; After this data line has been write, the assurance thin film transistor (TFT) (TFT) of this delegation needs the voltage of Jia Yue-10V to turn-off, at this moment guarantee that the capacitor C gs grid between the grid source of thin film transistor (TFT) (TFT) assembles negative charge, and pixel one lateral electrode is assembled positive charge, owing to guarantee the shutoff of thin film transistor (TFT) (TFT), data-signal and pixel separate, grid voltage changes to-10V from+20V, so liquid crystal capacitance just occurred, electric charge on memory capacitance and assurance thin film transistor (TFT) (TFT) the grid source capacitance need be redistributed, voltage on the liquid crystal pixel has a saltus step when guaranteeing that thin film transistor (TFT) (TFT) turn-offs like this, is referred to as leaping voltage (Δ VP) usually.The numerical value of leaping voltage (Δ VP) can calculate by following formula.

$\mathrm{\ΔVP}=\frac{C_{\mathrm{gs}}}{C_{\mathrm{LC}}+C_{\mathrm{stg}}+C_{\mathrm{gs}}}\×(V_{\mathrm{GH}}-V_{\mathrm{GL}})$

Fig. 4 has represented the change in voltage of liquid crystal pixel at charging stage and maintenance stage liquid crystal two ends, clearly when guaranteeing that thin film transistor (TFT) (TFT) grid forwards off status to by the state of opening, the voltage at liquid crystal two ends has produced saltus step, and this saltus step is exactly leaping voltage (Δ VP).The size of leaping voltage (Δ VP) numerical value directly influences the flicker of LCDs, so this value is one of important parameter of LCDs.Can analyze the characteristic of liquid crystal display better by test leaping voltage (Δ VP).

The LCD MODULE manufacturer of current thin film transistor liquid crystal display screen (TFT-LCD) is when the flicker of regulator solution crystal display screen, generally all regulate public electrode voltages (VCOM) by the mode of manual adjustments adjustable resistance, this greatly reduces production efficiency.

Summary of the invention

The present invention proposes a kind of public electrode voltages self-checking device that measures the leaping voltage of thin film transistor liquid crystal display screen for solving the inefficient problem of above-mentioned manual adjustments public electrode voltages.

For achieving the above object, the invention provides a kind of public electrode voltages self-checking device that measures the leaping voltage of thin film transistor liquid crystal display screen, comprising: the thin film transistor (TFT) array that is connected to cross one another a plurality of data line and a plurality of gate lines; Be connected to the pixel electrode of the source electrode of above-mentioned thin film transistor (TFT); The public electrode corresponding with described pixel electrode; Also comprise the sampling part, the leaping voltage that measure leaping voltage and measure part and common electrode voltage compensation and feedback fraction.

Wherein, two sampling thin film transistor (TFT)s that described measurement leaping voltage sampling part comprises pixels sampled and makes respectively on the grid line of the adjacent lines that pixels sampled is expert at and is expert at, the grid of described two sampling thin film transistor (TFT)s is received respectively on the grid line of the described adjacent lines that described pixels sampled is expert at and is expert at, and the source electrode of sampling thin film transistor (TFT) is all received on the pixel electrode of pixels sampled, drain electrode measures part with leaping voltage and links to each other; Pixels sampled preferably is positioned at the edge of liquid crystal panel, also can be positioned at other position certainly.Described leaping voltage measures part and comprises two homophase transport and placing devices that link to each other with the sampling part that measures leaping voltage, the electrode input end of described two homophase transport and placing devices links to each other with the drain electrode end of two sampling thin film transistor (TFT)s of the sampling part that measures leaping voltage respectively, is used for the voltage that homophase is followed the thin film transistor (TFT) drain electrode end of taking a sample; Be connected two gauge tap with homophase transport and placing device output terminal, make the grid line control that the control of a switch is expert at by pixels sampled, the grid line control of the described adjacent lines that the control of another switch is expert at by pixels sampled; Two memory capacitance that link to each other with the gauge tap other end, the pixel voltage value of pixels sampled when keeping the grid of pixels sampled to be high pressure and low pressure respectively; The difference discharge circuit that links to each other with gauge tap and memory capacitance is used to obtain the leaping voltage of pixels sampled.Herein, the control signal of two gauge tap can produce control signal by time schedule controller (TCON), the ON time that only needs a switch is consistent with the grid line ON time that pixels sampled is expert at, and the ON time of another switch is consistent with the described adjacent lines grid line ON time that pixels sampled is expert at.Described common electrode voltage compensation and feedback fraction are the leaping voltages by measurement is obtained, with compare the generation public electrode voltages at the gamma reference voltage of just distinguishing and on liquid crystal pixel, filling the minus zone of negative charge that fills positive charge on the liquid crystal pixel by discharge circuit under the same gray scale of expression, and this Voltage Feedback realized to the public electrode.Gamma reference voltage is VGMA ₁To VGMA _n, n is even number, wherein VGMA ₁To VGMA _N/2Be the gamma reference voltage of just distinguishing,

To VGMA _nBe the gamma reference voltage of minus zone, then the public electrode voltages that relatively produces is

$\mathrm{VCOM}=\frac{1}{2}\×({\mathrm{VGMA}}_1+{\mathrm{VGMA}}_n)-\mathrm{\ΔVP}=\frac{1}{2}\×({\mathrm{VGMA}}_2+{\mathrm{VGMA}}_{n-1})-\mathrm{\ΔVP}=......$

$=\frac{1}{2}\&times;({\mathrm{VGMA}}_{\frac{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051013242200171.png,C20051013242200191.png"\; state="\{\{state\}\}">n</figure-callout>}}{2}}+{\mathrm{VGMA}}_{\frac{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051013242200171.png,C20051013242200191.png"\; state="\{\{state\}\}">n</figure-callout>}}{2}+1})-\mathrm{\&Delta;VP},$

Wherein, Δ VP is a leaping voltage.Described common electrode voltage compensation and feedback fraction also can be by the leaping voltages that measurement is obtained, with liquid crystal pixel charging analog power voltage AVDD is compared the generation public electrode voltages by discharge circuit, and this Voltage Feedback realized to the public electrode.Liquid crystal pixel charging analog power voltage with the leaping voltage that is measured by the public electrode voltages that discharge circuit compares generation is $\mathrm{VCOM}=\frac{1}{2}\&times;\mathrm{AVDD}-\mathrm{\&Delta;VP},$ Wherein, VCOM is a public electrode voltages, and AVDD is a liquid crystal pixel charging analog power voltage, and Δ VP is a leaping voltage.

To achieve these goals, the present invention also provides the public electrode voltages self-checking device, comprising: the thin film transistor (TFT) array that is connected to cross one another a plurality of data line and a plurality of gate lines; Be connected to the pixel electrode of the source electrode of above-mentioned thin film transistor (TFT); The public electrode corresponding with described pixel electrode; Wherein, also comprise the sampling part, the leaping voltage that measure leaping voltage and measure part and common electrode voltage compensation and feedback fraction.Wherein, described sampling part can be divided into several regions according to panel, and a pixels sampled is determined in each piece zone.Two sampling thin film transistor (TFT) pipes that the sampling part of described measurement leaping voltage comprises pixels sampled and makes respectively on the grid line of the adjacent lines that pixels sampled is expert at and is expert at, the source electrode of sampling thin film transistor (TFT) pipe are all received on the pixel electrode of pixels sampled, drain electrode measures part with leaping voltage and links to each other.Pixels sampled preferably is positioned at the edge of liquid crystal panel, also can be positioned at other position.In addition, described leaping voltage measures part and comprises two homophase transport and placing devices that link to each other with the sampling part that measures leaping voltage, the electrode input end of described two homophase transport and placing devices links to each other with the drain electrode end of two sampling thin film transistor (TFT)s of the sampling part that measures leaping voltage respectively, is used for the voltage that homophase is followed the thin film transistor (TFT) drain electrode end of taking a sample; Be connected two gauge tap with homophase transport and placing device output terminal, make the grid line control that the control of a switch is expert at by pixels sampled, the grid line control of the described adjacent lines that the control of another switch is expert at by pixels sampled; Two memory capacitance that link to each other with the gauge tap other end, the pixel voltage value of pixels sampled when keeping the grid of pixels sampled to be high pressure and low pressure respectively; Herein, the control signal of two gauge tap can produce control signal by time schedule controller (TCON), the ON time that only needs a switch is consistent with the grid line ON time that pixels sampled is expert at, and the ON time of another switch is consistent with the described adjacent lines grid line ON time that pixels sampled is expert at; With corresponding gauge tap and the continuous corresponding difference discharge circuit of memory capacitance, be used to obtain the leaping voltage of corresponding sample pixel.Moreover, described common electrode voltage compensation and feedback fraction can be by each pixels sampled being measured the leaping voltage that obtains, with compare the generation public electrode voltages at the gamma reference voltage of just distinguishing and on liquid crystal pixel, filling the minus zone of negative charge that fills positive charge on the liquid crystal pixel by corresponding discharge circuit under the same gray scale of expression, and this Voltage Feedback realized to the public electrode of corresponding region.Gamma reference voltage is VGMA ₁To VGMA _n, n is even number, wherein VGMA ₁To VGMA _N/2Be the gamma reference voltage of just distinguishing,

To VGMA _nBe the gamma reference voltage of minus zone, then the public electrode voltages that relatively produces is

$\mathrm{VCOM}=\frac{1}{2}\&times;({\mathrm{VGMA}}_1+{\mathrm{VGMA}}_n)-\mathrm{\&Delta;VP}=\frac{1}{2}\&times;({\mathrm{VGMA}}_2+{\mathrm{VGMA}}_{n-1})-\mathrm{\&Delta;VP}=......$

$=\frac{1}{2}\&times;({\mathrm{VGMA}}_{\frac{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051013242200171.png,C20051013242200191.png"\; state="\{\{state\}\}">n</figure-callout>}}{2}}+{\mathrm{VGMA}}_{\frac{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051013242200171.png,C20051013242200191.png"\; state="\{\{state\}\}">n</figure-callout>}}{2}+1})-\mathrm{\&Delta;VP},$

Wherein, Δ VP is a leaping voltage.Described common electrode voltage compensation and feedback fraction can also be the leaping voltages by measurement is obtained, with liquid crystal pixel charging analog power voltage AVDD is compared the generation public electrode voltages by discharge circuit, and this Voltage Feedback realized to the public electrode.Liquid crystal pixel charging analog power voltage with the leaping voltage that is measured by the public electrode voltages that discharge circuit compares generation is $\mathrm{VCOM}=\frac{1}{2}\&times;\mathrm{AVDD}-\mathrm{\&Delta;VP},$ Wherein, VCOM is a public electrode voltages, and AVDD is a liquid crystal pixel charging analog power voltage, and Δ VP is a leaping voltage.

This invention is by taking a sample on pixel electrode, leaping voltage on the pixels sampled that records then (Δ VP) also feeds back to leaping voltage (Δ VP) numerical value on the public electrode, can accomplish public electrode voltages (VCOM) is automatically adjusted, do not need manual adjustments, overcome in the prior art and regulated the inefficient defect of public electrode voltages (VCOM), thereby enhanced productivity with the mode of manual adjustments adjustable resistance.

Description of drawings

Fig. 1 is a LCDs inner structure synoptic diagram.

Fig. 2 is a LCDs array structure video data addressing method.

Fig. 3 .1 is that LCDs interior pixel point discharges and recharges synoptic diagram.

Fig. 3 .2 is pixel charging stage synoptic diagram during transistor turns in the LCDs.

Fig. 3 .3 keeps the stage synoptic diagram when transistor ends in the LCDs.

Fig. 4 is that liquid crystal pixel is at charging and maintenance stage liquid crystal capacitance both end voltage waveform synoptic diagram.

Fig. 5 is a Thin Film Transistor-LCD pixel jump voltage tester schematic diagram.

Fig. 6 is that the LCD panel of thin-film transistor public electrode voltages compensates block scheme automatically.

Fig. 7 .1 is the realization to the common electrode voltage compensation circuit of gamma reference voltage and leaping voltage.

Fig. 7 .2 is the realization to the common electrode voltage compensation circuit of liquid crystal pixel charging analog power voltage and leaping voltage.

Fig. 8 is that the multiple spot public electrode voltages is regulated synoptic diagram automatically.

Embodiment

Below, with reference to accompanying drawing embodiments of the invention are described in detail.

Embodiment one

Fig. 5 is leaping voltage (Δ VP) the test philosophy figure of the thin film transistor liquid crystal display screen (TFT-LCD) that proposes of the present invention.

As shown in Figure 5, suppose that pel array is that the pixel location that the capable m of n-1 is listed as is a pixels sampled, T1 is the TFT that the capable m row of n-1 are controlled this pixel conducting and ended, T2 is the TFT on the capable m row of the T1 adjacent lines n pixel, except T1, also two TFT (T3 and T4) need made, do not influence the aperture opening ratio of this display screen for the TFT (T3, T4) that increases, optimal case is chosen in pixels sampled the marginal portion of screen, certainly, T3 and T4 can be produced on the outside of pixel or other position of LCD like this.Among this embodiment, the making of TFT T3 be chosen in the capable m row of n-1 pixel near, and grid and the T1 of T3 be connected on the n-1 gate line, T1 and T3 open simultaneously and turn-off simultaneously like this, the source electrode of T3 links to each other with the pixels sampled electrode; The same row of next line that the making of TFT T4 is chosen in pixels sampled point be the capable m row of n pixel near, and the grid of T4 and the grid of T2 all be connected on the capable gate line of n, T2 and T4 open simultaneously and turn-off simultaneously like this, and the source electrode of T4 also links to each other with the pixel electrode of pixels sampled.The electrode input end of two homophase transport and placing device OP1 and OP2 links to each other with the drain electrode end of TFT (T3 and T4) respectively, output terminal links to each other with K2 with gauge tap k1, its control signal derive from n-1 capable with n capable on the sweep signal of grid line, make T1, T3, K1 to open simultaneously and to turn-off, T2, T4, K2 can open and turn-off simultaneously.The control signal of K1 and K2 also can be by time schedule controller regularly to its input control signal, as long as it is consistent to satisfy the capable grid sweep trace of n-1 of the ON time of k1 and pixels sampled, the ON time of K2 by and consistent the getting final product of the capable grid sweep trace of pixels sampled point next line n.The other end of gauge tap k1 and K2 is connected with C2 and difference discharge circuit input end with capacitor C 1.The other end ground connection of capacitor C 1 and C2.

As shown in Figure 5, when high level (VGH) appears in the capable grid of n-1, T1, T3, K1 conducting, T2, T4, K2 end, and data-signal Sm charges to pixels sampled by T1, and T3 opens simultaneously, voltage is sampled OP1 on the pixel so, and amplify to capacitor C 1 charging by OP1, this moment, pixel voltage was saved on the capacitor C 1, i.e. VA voltage.After the signal of this row has been write, the grid that n-1 is capable is that high level (VGH) appears in the capable grid of low spot flat (VGL) while n, T1, T3, K1 end so, T2, T4, K2 conducting, then data-signal Sm writes video data by T2 to the capable m row of n pixel, the pixel voltage of the capable m row of while pixel n-1, promptly pixels sampled voltage is sampled OP2 by T4, and charges to capacitor C 2 by OP2.The liquid crystal voltage of pixels sampled when T1 ends has been saved on the capacitor C 2 so, i.e. VB voltage.

OP3 and 4 difference discharge circuits that resistance is formed, its output is exactly the difference that capacitor C 1 and C2 go up voltage, and promptly output is exactly VA-VB, and this voltage difference is Δ VP.

Fig. 6 is the schematic diagram that compensates public electrode voltages (VCOM) signal with leaping voltage (Δ VP).

As shown in Figure 6, determine pixels sampled at Panel in the module, by testing this pixel when grid voltage changes, the voltage of liquid crystal voltage generation saltus step (Δ VP) on the liquid crystal pixel, again this leaping voltage (Δ VP) is delivered to public electrode voltages (VCOM) compensating circuit, (VCOM) compensates to public electrode voltages, and delivers on public (Common) electrode.

The required gamma of Source drive (Gamma) reference voltage of Thin Film Transistor-LCD (TFT-LCD) is VGMA ₁, VGMA ₂VGMA _N-1, VGMA _n, AVDD is the required supply voltage of liquid crystal pixel on-load voltage, just has

AVDD＞VGMA ₁＞VGMA ₂＞…＞VGMA _n-1＞VGMA _n＞GND

Here n is an even number

If there is not saltus step in liquid crystal pixel voltage, i.e. leaping voltage Δ VP=0, then

$\mathrm{VCOM}=\frac{1}{2}\&times;({\mathrm{VGMA}}_1+{\mathrm{VGMA}}_n)=\frac{1}{2}\&times;({\mathrm{VGMA}}_2+{\mathrm{VGMA}}_{n-1})=......$

$=\frac{1}{2}\&times;({\mathrm{VGMA}}_{\frac{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051013242200171.png,C20051013242200191.png"\; state="\{\{state\}\}">n</figure-callout>}}{2}}+{\mathrm{VGMA}}_{\frac{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051013242200171.png,C20051013242200191.png"\; state="\{\{state\}\}">n</figure-callout>}}{2}+1})$

If there is voltage jump in liquid crystal pixel, i.e. leaping voltage Δ VP ≠ 0, then

$\mathrm{VCOM}=\frac{1}{2}\&times;({\mathrm{VGMA}}_1+{\mathrm{VGMA}}_n)-\mathrm{\&Delta;VP}=\frac{1}{2}\&times;({\mathrm{VGMA}}_2+{\mathrm{VGMA}}_{n-1})-\mathrm{\&Delta;VP}=......$

$=\frac{1}{2}\&times;({\mathrm{VGMA}}_{\frac{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051013242200171.png,C20051013242200191.png"\; state="\{\{state\}\}">n</figure-callout>}}{2}}+{\mathrm{VGMA}}_{\frac{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="C20051013242200171.png,C20051013242200191.png"\; state="\{\{state\}\}">n</figure-callout>}}{2}+1})-\mathrm{\&Delta;VP}$

Fig. 7 .1 is exactly the generative circuit of public electrode voltages (VCOM), in this circuit, gets VGMA ₁And VGMA _nThe public electrode voltages of medium voltage when driving (there is not saltus step in pixel voltage) as ideal.Δ VP is exactly the measured leaping voltage of display screen in the circuit, and then the value of the output public electrode voltages VCOM of difference discharge circuit OP output terminal is

$\mathrm{VCOM}=\frac{1}{2}\&times;({\mathrm{VGMA}}_1+{\mathrm{VGMA}}_n)-\mathrm{\&Delta;VP}$

Fig. 7 .2 is the another kind of generative circuit of public electrode voltages (VCOM), in this circuit, utilization is to the medium voltage of the analog power voltage of the liquid crystal pixel charging public electrode voltages as desirable (when there is not saltus step in pixel voltage), and then the output valve of public electrode voltages (VCOM) is

$\mathrm{VCOM}=\frac{1}{2}\&times;\mathrm{AVDD}-\mathrm{\&Delta;VP}$

By said method, the difference of the leaping voltage (Δ VP) of liquid crystal panel (Panel) can have been fed back in the variation of public electrode voltages (VCOM).Even the property difference of screen or the difference of display graphics have caused the variation of display pixel leaping voltage (Δ VP), can realize the automatic adjusting of public electrode voltages (VCOM) by this circuit, it is more stable that the module map picture is shown.

Embodiment two

Shown in Fig. 8 .1 and 8.2, public electrode on Thin Film Transistor-LCD (TFT-LCD) LCDs is divided into the several separate part, for example 2,4,6 ..., among Fig. 8 .1 be 2, among Fig. 8 .2 be 4, and on each part selected one or several pixels sampled, and at two thin film transistor (TFT)s of increase (TFT) of each sampling phase vegetarian refreshments correspondence, be used for the pixel voltage of this pixel is taken a sample the structure among its similar and the embodiment one; Assign to measure the leaping voltage (Δ VP) of each pixels sampled by the test department that is similar to embodiment one equally, and be sent to and be similar to embodiment one corresponding public electrode voltages (VCOM) compensating circuit and produce voltage on the public electrode that public electrode voltages (VCOM) compensates this part.

By with the public electrode piecemeal, can more accurate adjusting public electrode voltages (VCOM), prevented especially since on the large-size screen monitors difference leaping voltage (Δ VP) cause public electrode voltages (VCOM) difference.Piecemeal is many more, and public electrode voltages (VCOM) is regulated accurate more, and picture quality is good more.

Public electrode is divided 2 or 4 in this embodiment, it is only for better saying something, can be in the reality according to various composite factors, consideration is divided into some with public electrode, and in the selected pixels sampled of the pixel region of corresponding blocks, the selection of pixels sampled is the edge of tangible panel preferably, also can be positioned at other position of panel.

More than explanation and accompanying drawing illustrate specific implementations of the present invention, but it is self-evident, the present invention can carry out various distortion by those skilled in the art and implement, as the point of transform sampling locations of pixels and pixels sampled, the components and parts that change test circuit, the components and parts of conversion compensating circuit etc.The embodiment that has been out of shape like that etc. can not break away from technological thought of the present invention or prospect is individually understood, and must regard the device that comprises in the appending claims of the present invention as.

Claims (21)

1, a kind of public electrode voltages self-checking device that measures the leaping voltage of thin film transistor liquid crystal display screen comprises:

Be connected to the thin film transistor (TFT) array of cross one another a plurality of data line and a plurality of gate lines;

Be connected to the pixel electrode of above-mentioned thin film transistor (TFT) source electrode;

The public electrode corresponding with described pixel electrode;

Wherein, also comprise the sampling part, the leaping voltage that measure leaping voltage and measure part and common electrode voltage compensation and feedback fraction.

2, device according to claim 1, it is characterized in that: two sampling thin film transistor (TFT)s that the sampling part of described measurement leaping voltage comprises pixels sampled and makes respectively on the grid line of the adjacent lines that pixels sampled is expert at and is expert at, the grid of described two sampling thin film transistor (TFT)s is received respectively on the grid line of the described adjacent lines that described pixels sampled is expert at and is expert at, and the source electrode of sampling thin film transistor (TFT) is all received on the pixel electrode of pixels sampled, drain electrode measures part with leaping voltage and links to each other.

3, device according to claim 2 is characterized in that: described pixels sampled is positioned at the edge of liquid crystal panel.

4, according to claim 2 or 3 arbitrary described devices, it is characterized in that: described leaping voltage measures part and comprises two homophase transport and placing devices that link to each other with the sampling part that measures leaping voltage, the electrode input end of described two homophase transport and placing devices links to each other with the drain electrode end of two sampling thin film transistor (TFT)s of the sampling part that measures leaping voltage respectively, is used for the voltage that homophase is followed the thin film transistor (TFT) drain electrode end of taking a sample;

What be connected with homophase transport and placing device output terminal is two gauge tap, the grid line control that the control of a switch is expert at by pixels sampled, and the control of another switch is controlled by the grid line of the described adjacent lines that pixels sampled is expert at;

Two memory capacitance that link to each other with the gauge tap other end, the pixel voltage value of pixels sampled when keeping the grid of pixels sampled to be high pressure and low pressure respectively;

The difference discharge circuit that links to each other with gauge tap and memory capacitance is used to obtain the leaping voltage of pixels sampled.

5, according to claim 1 or 2 or 3 described devices, it is characterized in that: described common electrode voltage compensation and feedback fraction are the leaping voltages by measurement is obtained, with compare the generation public electrode voltages at the gamma reference voltage of just distinguishing and on liquid crystal pixel, filling the minus zone of negative charge that fills positive charge on the liquid crystal pixel by discharge circuit under the same gray scale of expression, and this Voltage Feedback realized to the public electrode.

6, device according to claim 4, it is characterized in that: described common electrode voltage compensation and feedback fraction are the leaping voltages by measurement is obtained, with compare the generation public electrode voltages at the gamma reference voltage of just distinguishing and on liquid crystal pixel, filling the minus zone of negative charge that fills positive charge on the liquid crystal pixel by discharge circuit under the same gray scale of expression, and this Voltage Feedback realized to the public electrode.

7, device according to claim 5 is characterized in that: described gamma reference voltage is VGMA ₁To VGMAn, n is even number, wherein VGMA ₁To VGMA _N/2Be the gamma reference voltage of just distinguishing,

To VGMA _nBe the gamma reference voltage of minus zone, then the public electrode voltages that relatively produces is

$\mathrm{VCOM}=\frac{1}{2}\&times;({\mathrm{VGMA}}_1+{\mathrm{VGMA}}_n)-\mathrm{\&Delta;VP}=\frac{1}{2}\&times;({\mathrm{VGMA}}_2+{\mathrm{VGMA}}_{n-1})-\mathrm{\&Delta;VP}=......$

$=\frac{1}{2}\&times;({\mathrm{VGMA}}_{\frac{n}{2}}+{\mathrm{VGMA}}_{\frac{n}{2}+1})-\mathrm{\&Delta;VP}$

Δ VP-leaping voltage.

8, device according to claim 6 is characterized in that: described gamma reference voltage is VGMA ₁To VGMAn, n is even number, wherein VGMA ₁To VGMA _N/2Be the gamma reference voltage of just distinguishing,

To VGMA _nBe the gamma reference voltage of minus zone, then the public electrode voltages that relatively produces is

$\mathrm{VCOM}=\frac{1}{2}\&times;({\mathrm{VGMA}}_1+{\mathrm{VGMA}}_n)-\mathrm{\&Delta;VP}=\frac{1}{2}\&times;({\mathrm{VGMA}}_2+{\mathrm{VGMA}}_{n-1})-\mathrm{\&Delta;VP}=......$

$=\frac{1}{2}\&times;({\mathrm{VGMA}}_{\frac{n}{2}}+{\mathrm{VGMA}}_{\frac{n}{2}+1})-\mathrm{\&Delta;VP}$

Δ VP-leaping voltage.

9, according to claim 1 or 2 or 3 described devices, it is characterized in that: described common electrode voltage compensation and feedback fraction are the leaping voltages by measurement is obtained, with liquid crystal pixel charging analog power voltage AVDD is compared the generation public electrode voltages by discharge circuit, and this Voltage Feedback realized to the public electrode.

10, device according to claim 4, it is characterized in that: described common electrode voltage compensation and feedback fraction are the leaping voltages by measurement is obtained, with liquid crystal pixel charging analog power voltage AVDD is compared the generation public electrode voltages by discharge circuit, and this Voltage Feedback realized to the public electrode.

11, device according to claim 9 is characterized in that: describedly to liquid crystal pixel charging analog power voltage and the leaping voltage that is measured by the public electrode voltages that discharge circuit compares generation be $\mathrm{VCOM}=\frac{1}{2}\&times;\mathrm{AVDD}-\mathrm{\&Delta;VP},$ Wherein, VCOM is a public electrode voltages, and AVDD is a liquid crystal pixel charging analog power voltage, and Δ VP is a leaping voltage.

12, device according to claim 10 is characterized in that: described to liquid crystal pixel charging analog power voltage, with the leaping voltage that is measured by the public electrode voltages that discharge circuit compares generation be $\mathrm{VCOM}=\frac{1}{2}\&times;\mathrm{AVDD}-\mathrm{\&Delta;VP},$ Wherein, VCOM is a public electrode voltages, and AVDD is a liquid crystal pixel charging analog power voltage, and Δ VP is a leaping voltage.

13, device according to claim 1 is characterized in that: the sampling part of described measurement leaping voltage can be divided into several regions according to panel, and a pixels sampled is determined in each piece zone.

14, device according to claim 13 is characterized in that: described pixels sampled is positioned at the edge of liquid crystal panel.

15, according to claim 13 or 14 described devices, it is characterized in that: two sampling thin film transistor (TFT)s that the sampling part of described measurement leaping voltage comprises pixels sampled and makes respectively on the grid line of the adjacent lines that pixels sampled is expert at and is expert at, the grid of described two sampling thin film transistor (TFT)s is received respectively on the grid line of the described adjacent lines that described pixels sampled is expert at and is expert at, and source electrode is all received on the pixel electrode of pixels sampled, and drain electrode measures part with leaping voltage and links to each other.

16, device according to claim 15, it is characterized in that: described leaping voltage measures part and comprises two homophase transport and placing devices that link to each other with the sampling part that measures leaping voltage, the electrode input end of described two homophase transport and placing devices links to each other with the drain electrode end of two sampling thin film transistor (TFT)s of the sampling part that measures leaping voltage respectively, is used for the voltage that homophase is followed the thin film transistor (TFT) drain electrode end of taking a sample;

What be connected with homophase transport and placing device output terminal is two gauge tap, the grid line control that the control of a switch is expert at by pixels sampled, and the control of another switch is controlled by the grid line of the described adjacent lines that pixels sampled is expert at;

Two memory capacitance that link to each other with the gauge tap other end, the pixel voltage value of pixels sampled when keeping the grid of pixels sampled to be high pressure and low pressure respectively;

With corresponding gauge tap and the continuous corresponding difference discharge circuit of memory capacitance, be used to obtain the leaping voltage of corresponding sample pixel.

17, according to claim 13 or 14 described devices, it is characterized in that: described common electrode voltage compensation and feedback fraction are by each pixels sampled being measured the leaping voltage that obtains, with compare the generation public electrode voltages at the gamma reference voltage of just distinguishing and on liquid crystal pixel, filling the minus zone of negative charge that fills positive charge on the liquid crystal pixel by corresponding discharge circuit under the same gray scale of expression, and this Voltage Feedback realized to the public electrode of corresponding region.

18, device according to claim 16, it is characterized in that: described common electrode voltage compensation and feedback fraction are by each pixels sampled being measured the leaping voltage that obtains, with under the same gray scale of expression at the gamma reference voltage of minus zone of just distinguishing and on liquid crystal pixel, filling negative charge that fills positive charge on the liquid crystal pixel by comparing the generation public electrode voltages with the corresponding discharge circuit of this pixels sampled, and this Voltage Feedback realized to the public electrode of corresponding region.

19, device according to claim 18 is characterized in that: described gamma reference voltage is VGMA ₁To VGMAn, n is even number, wherein VGMA ₁To VGMA _N/2Be the gamma reference voltage of just distinguishing,

To VGMA _nBe the gamma reference voltage of minus zone, then the public electrode voltages that relatively produces is

$\mathrm{VCOM}=\frac{1}{2}\&times;({\mathrm{VGMA}}_1+{\mathrm{VGMA}}_n)-\mathrm{\&Delta;VP}=\frac{1}{2}\&times;({\mathrm{VGMA}}_2+{\mathrm{VGMA}}_{n-1})-\mathrm{\&Delta;VP}=......$

$=\frac{1}{2}\&times;({\mathrm{VGMA}}_{\frac{n}{2}}+{\mathrm{VGMA}}_{\frac{n}{2}+1})-\mathrm{\&Delta;VP}$

Δ VP-leaping voltage.

20, device according to claim 16, it is characterized in that: described common electrode voltage compensation and feedback fraction are the leaping voltages by measurement is obtained, with liquid crystal pixel charging analog power voltage AVDD is compared the generation public electrode voltages by discharge circuit, and this Voltage Feedback realized to the public electrode.

21, device according to claim 20 is characterized in that: described to liquid crystal pixel charging analog power voltage, with the leaping voltage that is measured by the public electrode voltages that discharge circuit compares generation be $\mathrm{VCOM}=\frac{1}{2}\&times;\mathrm{AVDD}-\mathrm{\&Delta;VP},$ Wherein, VCOM is a public electrode voltages, and AVDD is a liquid crystal pixel charging analog power voltage, and Δ VP is a leaping voltage.

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