CN100582903C - Liquid crystal display apparatus and drive circuit as well as drive method - Google Patents

Abstract

The invention relates to a liquid crystal display (LCD) device, a driving circuit thereof and a driving method. The driving circuit comprises a plurality of scanning lines, a plurality of data lines which vertically intersect with the scanning lines in an insulated way, a plurality of pixel units defined by the scanning lines and the data lines, a scan driver circuit used for driving the scanning lines and a data driver circuit used for driving the data lines, a sequence control circuit, a benchmark voltage control circuit and a comparer. The comparer compares pulse signal voltage input to the scan driver circuit with the benchmark voltage output by the benchmark voltage control circuit and inputs comparing result to the sequence control circuit; the sequence control circuit outputs an enabling signal which controls output according to the comparing result so as to control the scan driver circuit to output the scan signal. The LCD device of the invention effectively overcomes the problem of flickering display pictures of the LCD device when the scan signals switch among different scanning lines.

Description

Liquid crystal indicator and driving circuit thereof and driving method

Technical field

The present invention relates to a kind of liquid crystal indicator and driving circuit thereof and driving method.

Background technology

Liquid crystal indicator is because of having characteristics such as low radiation, thin thickness, and is widely used in electronic display units such as mobile phone, TV, notebook computer.

Seeing also Fig. 1, is a kind of structural representation of prior art liquid crystal indicator.This liquid crystal indicator 10 comprises second substrate (figure does not show) that one first substrate (figure do not show), is oppositely arranged with this first substrate, is clipped in liquid crystal layer (scheming not show), scan driving circuit 15, a data drive circuit 16 and a sequential control circuit 17 between this two substrate.

This first substrate comprises a public electrode (figure do not show), data line 12 and a plurality of pixel cell (indicating) that is positioned at this sweep trace 11 and this data line 12 infalls that this second substrate comprises that many sweep traces that are parallel to each other 11, many are parallel to each other and intersects vertically with these sweep trace 11 insulation respectively.

This scan drive circuit 15 is used to export a plurality of sweep signals to this sweep trace 11, and this data drive circuit 16 is used to export a plurality of data-signals to this data line 12.The vertical clock signal of first output terminal, 171 outputs of this sequential control circuit 17, this vertical clock signal is sent to the beginning that this data drive circuit 16 is used to refer to a new two field picture, the horizontal clock signal of second output terminal, 172 outputs of this sequential control circuit 17, this horizontal clock signal is sent to the beginning that this scan drive circuit 15 is used to refer to a new line scan signals.

Seeing also Fig. 2, is the pixel cell equivalent circuit diagram of liquid crystal indicator 10 shown in Figure 1, and wherein first sweep trace 111, second sweep trace 113 are two adjacent sweep traces.This pixel cell comprises a memory capacitance 101, a pixel electrode 103, a public electrode 105 and a thin film transistor (TFT) 13.This pixel electrode 103 is oppositely arranged with the public electrode of this first substrate, and this public electrode 105 is electrically connected with the public electrode of this first substrate.Produce a stray capacitance 107 between this pixel electrode 103 and this first sweep trace 111, the public electrode of this pixel electrode 103, this first substrate and be clipped in that liquid crystal forms a liquid crystal capacitance 109 between the two.The grid of this thin film transistor (TFT) 13 (not indicating) is electrically connected this first sweep trace 111, and its source electrode (not indicating) is electrically connected this data line 12, and its drain electrode (not indicating) is electrically connected this pixel electrode 103.This memory capacitance 101 is connected electrically between this pixel electrode 103 and this public electrode 105.

See also Fig. 1, Fig. 2 and Fig. 3, wherein, Fig. 3 is the drive waveforms figure of liquid crystal indicator 10 shown in Figure 1, and " G1-Gn " is a plurality of sweep signal waveforms of these scan drive circuit 15 outputs.After the consecutive pulses signal is input to this scan drive circuit 15, in the time T 1 of a frame, this scan drive circuit 15 produce a plurality of sweep signal G1, G2 ..., Gn, and be applied to this multi-strip scanning line 11 successively, this sweep signal is a potential pulse, its high voltage is Vgh, and its low-voltage is Vgl.When sweep signal was loaded on this first sweep trace 111, this high voltage Vgh made the thin film transistor (TFT) 13 that is connected on this first sweep trace 111 all be in conducting state.Simultaneously, this data drive circuit 16 produces data-signal, and this data-signal is loaded on these many data lines 12, and source electrode, the drain electrode of this thin film transistor (TFT) 13 of process are loaded on this pixel electrode 103 successively.This voltage data signal makes this memory capacitance 101 begin charging, and the final charging voltage in its two ends is directly proportional with voltage data signal on this data line 12.When sweep signal is loaded on this second sweep trace 113, become low-voltage Vgl on this first sweep trace 111, the thin film transistor (TFT) 13 that is connected on this first sweep trace 111 all is in cut-off state, the charging voltage at these memory capacitance 101 two ends remains unchanged the voltage of this pixel electrode 103 substantially, thereby this data-signal is carried on this pixel electrode 103 in the time T 1 of a frame all the time.

, when these thin film transistor (TFT) 13 conductings, promptly when sweep signal is loaded on this first sweep trace 111, this memory capacitance 101, this stray capacitance 107 and 109 electrically charged total amounts of this liquid crystal capacitance

Q1＝(Vgh-Vd1)Cgd+(Vd1-Vcom)*(Clc+Cs)，

Wherein, Vgh, Vd1 are respectively when 13 conductings of this thin film transistor (TFT), be carried in the magnitude of voltage on this first sweep trace 111, this pixel electrode 103, Vcom is the magnitude of voltage on this public electrode 105, and Cgd, Clc, Cs are respectively the capacitance of this stray capacitance 107, this liquid crystal capacitance 109 and this memory capacitance 101.In the moment that this thin film transistor (TFT) 13 ends, promptly be loaded on moment on this second sweep trace 113, this memory capacitance 101, this stray capacitance 107 and 109 electrically charged total amounts of this liquid crystal capacitance when sweep signal

Q2＝(Vgl-Vd2)Cgd+(Vd2-Vcom)*(Clc+Cs)，

Wherein, Vgl, Vd2 are carried in the magnitude of voltage on this first sweep trace 111, this pixel electrode 103 for when this thin film transistor (TFT) 13 ends.According to the electric charge principle of not going out

Q1＝Q2

(Vgh-Vd1)Cgd+(Vd1-Vcom)*(Clc+Cs)

Promptly

＝(Vgl-Vd2)Cgd+(Vd2-Vcom)*(Clc+Cs)，

Thereby draw at 13 conductings of this thin film transistor (TFT) and the moment that ends, the variable quantity of voltage on this pixel electrode 103

$\mathrm{\ΔV}=\mathrm{Vd}1-\mathrm{Vd}2=\frac{(\mathrm{Vgh}-\mathrm{Vgl})*\mathrm{Cgd}}{\mathrm{Cgd}+\mathrm{Clc}+\mathrm{Cs}}.$

By following formula as can be known, under the certain situation of the capacitance value of this stray capacitance 107, this liquid crystal capacitance 109, this memory capacitance 101, these thin film transistor (TFT) 13 conductings and the moment that ends, the size of the variation delta V of voltage only depends on the variable quantity Vgh-Vgl that is loaded on the voltage on this first sweep trace 111 on this pixel electrode 103.Usually, Cgd=0.05pf, Clc=0.1pF, Cs=0.5pF, Vgh-Vgl=35V, then

$\mathrm{\ΔV}=\frac{35\×0.05}{0.05+0.1+0.5}=2.69V.$

Because in these thin film transistor (TFT) 13 conductings and the moment that ends, the variable quantity of voltage reaches 2.69V on this pixel electrode 103, and the voltage difference between adjacent two GTGs is 30-50mV, the variable quantity of voltage is much larger than the voltage difference between adjacent two GTGs on this pixel electrode 103, so when sweep signal is switched on different sweep trace 11, these liquid crystal indicator 10 picture displayed have scintillation, cause the user to have sense of discomfort when watching picture, are unfavorable for vision health.

Summary of the invention

In order to solve the problem of liquid crystal indicator display frame flicker in the prior art, the invention provides a kind of liquid crystal indicator driving circuit that improves film flicker.

A kind of liquid crystal indicator that adopts above-mentioned driving circuit is provided simultaneously.

A kind of liquid crystal display apparatus driving circuit that improves film flicker also is provided.

A kind of liquid crystal indicator driving circuit, it comprises many sweep traces that are parallel to each other, many the data lines that are parallel to each other and intersect vertically with the insulation of this sweep trace, a plurality of pixel cells that this sweep trace and this data line define, scan driving circuit, one data drive circuit, one sequential control circuit, an one reference voltage control circuit and a comparer, this scan drive circuit is used to drive this sweep trace, this data drive circuit is used to drive this data line, this comparer will be transferred to the pulse signal voltage of this scan drive circuit and the reference voltage of this reference voltage control circuit output compares, and comparative result outputed to this sequential control circuit, this sequential control circuit is output as high level or low level according to the enable signal of this comparative result output one control output to control this scan drive circuit sweep signal.

Further improvement as above-mentioned liquid crystal indicator driving circuit: be input to the pulse signal of this scan drive circuit, in its lower edge, magnitude of voltage slowly descends.

A kind of liquid crystal indicator, it comprises one first substrate, one second substrate that is oppositely arranged with this first substrate, one is sandwiched in the liquid crystal layer between this first substrate and second substrate, scan driving circuit, one data drive circuit, one sequential control circuit, an one reference voltage control circuit and a comparer, this second substrate comprises many sweep traces that are parallel to each other, many the data lines that are parallel to each other and intersect vertically with the insulation of this sweep trace, a plurality of pixel cells that this sweep trace and this data line define, this scan drive circuit is used to drive this sweep trace, this data drive circuit is used to drive this data line, this comparer will be transferred to the pulse signal voltage of this scan drive circuit and the reference voltage of this reference voltage control circuit output compares, and comparative result outputed to this sequential control circuit, this sequential control circuit is output as high level or low level according to the enable signal of this comparative result output one control output to control this scan drive circuit sweep signal.

The driving method of above-mentioned liquid crystal indicator comprises the steps: that pulse signal is input to this scan drive circuit, and this scan drive circuit produces a plurality of sweep signals, and is applied to successively on this multi-strip scanning line; This comparer compares the scanning voltage signal of this scan drive circuit output and the reference voltage of this reference voltage control circuit output, and comparative result is outputed to this sequential control circuit; The enable signal of this sequential control circuit comparative result output one control output in rapid according to this previous step is high level or low level to control this scan drive circuit output scanning signal.

Compared with prior art, liquid crystal indicator of the present invention increases a comparer and a reference voltage control circuit, and the pulse signal that is input to this scan drive circuit is that magnitude of voltage slowly descends in the process of low-voltage by high-voltage variable at it.At this sweep trace by being conducting to the moment that ends, voltage variety on this sweep trace reduces, thereby when effectively having overcome sweep signal and on different sweep traces, having switched, the problem of liquid crystal indicator display frame flicker, the user is when watching picture displayed, can not produce sense of discomfort, can not influence user's vision health yet.Simultaneously, situation according to liquid crystal indicator actual displayed image, reasonably adjust the value of the reference voltage of this reference voltage control circuit, thereby adjust the voltage variety on this sweep trace, the easier optimum condition that reaches of this liquid crystal indicator picture displayed.

Description of drawings

Fig. 1 is a kind of structural representation of prior art liquid crystal indicator.

Fig. 2 is the pixel cell equivalent circuit diagram of liquid crystal indicator shown in Figure 1.

Fig. 3 is the drive waveforms figure of liquid crystal indicator shown in Figure 1

Fig. 4 is the structural representation of liquid crystal indicator of the present invention.

Fig. 5 is the pixel cell equivalent circuit diagram of liquid crystal indicator shown in Figure 4.

Fig. 6 is the drive signal waveform figure of liquid crystal indicator shown in Figure 4.

Embodiment

Seeing also Fig. 4, is the structural representation of liquid crystal indicator of the present invention.This liquid crystal indicator 20 comprises second substrate (figure does not show) that one first substrate (figure do not show), is oppositely arranged with this first substrate, is sandwiched in liquid crystal layer (scheming not show), scan driving circuit 25, a data drive circuit 26, a sequential control circuit 27, a comparer 28 and a reference voltage control circuit 29 between this two substrate.

This first substrate comprises a public electrode (figure do not show), and this second substrate comprises that many sweep traces that are parallel to each other 21, many are parallel to each other and the data line 22 that intersects vertically with these sweep trace 21 insulation respectively, many are positioned at the pixel cells (indicating) of this sweep trace 21 and these data line 22 infalls.

This scan drive circuit 25 comprises a plurality of sweep signal output terminals (not indicating) and a pulse input end 251.This sweep signal output terminal output scanning signal is to this sweep trace 21, and a pulse signal is imported in this pulse input 251.This data drive circuit 26 comprises a plurality of data-signal output terminals, and this data-signal output terminal outputting data signals is to this data line 22.The reference voltage V i that 29 outputs one of this reference voltage control circuit are adjustable is to the inverting input of this comparer 28, and the in-phase input end of this comparer 28 is electrically connected the pulse input end 251 of this scan drive circuit 25.

This sequential control circuit 27 comprises first, second, third output terminal 271,272,273 and an input end 274.This input end 274 receives the signal of these comparer 28 outputs, the vertical clock signal of these first output terminal, 271 outputs, this vertical clock signal is sent to the beginning that this data drive circuit 26 is used to refer to a new two field picture, the horizontal clock signal of these second output terminal, 272 outputs, this horizontal clock signal is sent to the beginning that this scan drive circuit 25 is used to refer to a new line scan signals, the enable signal of the 3rd output terminal 273 outputs one control output, the enable signal of the control output of these sequential control circuit 27 outputs also is sent to this scan drive circuit 25, to control the output of these scan drive circuit 25 signals.When the enable signal of the control output of this sequential control circuit 27 outputs was low level, the sweep signal of these scan drive circuit 25 outputs was constant; When the enable signal of the control output of this sequential control circuit 27 outputs was high level, the sweep signal of these scan drive circuit 25 outputs was forced to pull into low level.

Seeing also Fig. 5, is the pixel cell equivalent circuit diagram of liquid crystal indicator 20 shown in Figure 4, and wherein, first, second sweep trace 211,212 is two adjacent sweep traces in this multi-strip scanning line 21.This pixel cell comprises a memory capacitance 201, a pixel electrode 203, a public electrode 205 and a thin film transistor (TFT) 23.This pixel electrode 203 is oppositely arranged with the public electrode of this first substrate, and this public electrode 205 is electrically connected with the public electrode of this first substrate.Produce a stray capacitance 207 between this pixel electrode 203 and this first sweep trace 211, the public electrode of this pixel electrode 203, this first substrate and be clipped in that liquid crystal forms a liquid crystal capacitance 209 between the two.The grid of this thin film transistor (TFT) 23 is electrically connected this sweep trace 21, and its source electrode (not indicating) is electrically connected this data line 22, and its drain electrode (not indicating) is electrically connected this pixel electrode 203.This memory capacitance 201 is electrically connected between this pixel electrode 203 and the public electrode 205.

See also Fig. 4, Fig. 5 and Fig. 6, wherein Fig. 6 is the drive signal waveform figure of liquid crystal indicator 20 shown in Figure 4, " G " is the pulse signal waveform of pulse input end 251 inputs of this scan drive circuit 25, " OE " is the enable signal waveform of the control output of these sequential control circuit 27 outputs, " Gi " is the sweep signal waveform on this first sweep trace 211, and " Gi+1 " is the sweep signal waveform on this second sweep trace 212.This pulse signal G high voltage is Vgh (being generally 27V), and its low-voltage is Vcut (being generally 15V), is that its magnitude of voltage slowly descends in the process of low-voltage by high-voltage variable at it.This sweep signal Gi high voltage is Vgh (being generally 27V), its low-voltage be Vgl (be generally-6V).This pulse signal G is input to the pulse input end 251 of this scan drive circuit 25, and this scan drive circuit 25 produces a plurality of sweep signals, and is applied to successively on this multi-strip scanning line 21.

Simultaneously, this pulse signal G also is loaded on the in-phase input end of this comparer 28, reference voltage V i (Vcut＜the Vi＜Vgh) compare of the pulse voltage of this pulse signal G and 29 outputs of this reference voltage control circuit, in t1 arrives the time of t2, the in-phase input end voltage of this comparer 28 is greater than this reference voltage V i, its output terminal is exported a high level, this high level is from input end 274 inputs of this sequential control circuit 27, the enable signal OE of the control output of the 3rd output terminal 273 outputs of this sequential control circuit 27 is a low level, the sweep signal Gi of these first sweep trace, 211 outputs is constant, and the thin film transistor (TFT) 23 that is connected on this first sweep trace 211 all is in conducting state.At this moment, this data drive circuit 26 produces data-signal, and this data-signal is loaded on this many data lines 22, and source electrode, the drain electrode of this thin film transistor (TFT) 23 of process are loaded on this pixel electrode 203 successively.This voltage data signal makes this memory capacitance 201 begin charging, and the final charging voltage in its two ends is directly proportional with voltage data signal on this data line 22.

In t2 arrives the time of t3, the in-phase input end voltage of this comparer 28 is less than this reference voltage V i, its output terminal is exported a low level, this low level is from input end 274 inputs of this sequential control circuit 27, the enable signal OE of the control output of the 3rd output terminal 273 outputs of this sequential control circuit 27 is a high level, the sweep signal of these first sweep trace, 211 outputs is forced to pull into low level Vgl, and at this moment, the thin film transistor (TFT) 23 that is connected on this first sweep trace 211 all is in cut-off state.

Become the moment t2 that ends at this thin film transistor (TFT) 25 by conducting, the variable quantity of voltage on this pixel electrode 203

$\mathrm{\ΔV}=\mathrm{Vd}1-\mathrm{Vd}2=\frac{(\mathrm{Vi}-\mathrm{Vgl})*\mathrm{Cgd}}{\mathrm{Cgd}+\mathrm{Clc}+\mathrm{Cs}}$

Wherein, when Vd1, Vd2 were respectively these thin film transistor (TFT) 23 conductings and end, the magnitude of voltage on this pixel electrode 203, Cgd, Clc, Cs were respectively the capacitance of this stray capacitance 207, this liquid crystal capacitance 209, this memory capacitance 201.Because therefore this reference voltage V i value between Vcut and Vgh, becomes the moment t2 that ends at this thin film transistor (TFT) 25 by conducting, the variable quantity of voltage reduces on this pixel electrode 203.

Compared with prior art, liquid crystal indicator 20 of the present invention increases a comparer 28 and a reference voltage control circuit 29, and the pulse signal of these scan drive circuit 25 inputs is that magnitude of voltage slowly descends in the process of low-voltage by high-voltage variable at it.At this thin film transistor (TFT) 23 by being conducting to the moment t 2 that ends, voltage variety Vi-Vgl on this sweep trace 21 is less than Vgh-Vgl, reduced the variable quantity of voltage on this pixel electrode 203, thereby when effectively having overcome sweep signal and on different sweep trace 21, having switched, the problem of liquid crystal indicator 20 display frames flicker, the user can not produce sense of discomfort when watching picture, can not influence user's vision health yet.Simultaneously, situation according to liquid crystal indicator 20 actual displayed images, reasonably adjust the value of the reference voltage V i of this reference voltage control circuit 29, and then adjust the variation delta V of voltage on this pixel electrode 203, the easier optimum condition that reaches of these liquid crystal indicator 20 picture displayed.

Claims (10)

1. liquid crystal indicator driving circuit, it comprises many sweep traces that are parallel to each other, many the data lines that are parallel to each other and intersect vertically with the insulation of this sweep trace respectively, a plurality of pixel cells that this sweep trace and this data line define, one sequential control circuit, a scan driving circuit and a data drive circuit, this scan drive circuit is used to drive this sweep trace, this data drive circuit is used to drive this data line, it is characterized in that: this liquid crystal indicator driving circuit also comprises a reference voltage control circuit and a comparer, this comparer will be transferred to the pulse signal voltage of this scan drive circuit and the reference voltage of this reference voltage control circuit output compares, and comparative result outputed to this sequential control circuit, this sequential control circuit is output as high level or low level according to the enable signal of this comparative result output one control output to control this scan drive circuit sweep signal.

2. liquid crystal indicator driving circuit as claimed in claim 1, it is characterized in that: the pulse signal that is transferred to this scan drive circuit exports the normal phase input end of this comparer to, and the reference voltage of this reference voltage control circuit output is from the inverting input input of this comparer.

3. liquid crystal indicator driving circuit as claimed in claim 2, it is characterized in that: be transferred to the reference voltage of the pulse signal voltage of this scan drive circuit greater than this reference voltage control circuit output, this comparer is exported the enable signal that a voltage signal makes this sequential control circuit output one control output, and it is high level that the enable signal of this control output makes the sweep signal of this scan drive circuit output.

4. liquid crystal indicator driving circuit as claimed in claim 2, it is characterized in that: be transferred to the reference voltage of the pulse signal voltage of this scan drive circuit less than this reference voltage control circuit output, this comparer is exported the enable signal that a voltage signal makes this sequential control circuit output one control output, and it is low level that the enable signal of this control output makes the sweep signal of this scan drive circuit output.

5. liquid crystal indicator driving circuit as claimed in claim 1 is characterized in that: be input to the pulse signal of this scan drive circuit, at its negative edge, magnitude of voltage slowly descends.

6. liquid crystal indicator driving circuit as claimed in claim 1, it is characterized in that: this sequential control circuit is also exported a vertical clock signal and a horizontal clock signal, this vertical clock signal is sent to this data drive circuit to indicate the beginning of a new two field picture, and this horizontal clock signal is sent to this scan drive circuit to indicate the beginning of a new line scan signals.

7. liquid crystal indicator driving circuit as claimed in claim 1, it is characterized in that: this pixel cell comprises a thin film transistor (TFT), a pixel electrode, a public electrode and a memory capacitance, this film crystal tube grid is electrically connected this sweep trace, its source electrode is electrically connected this data line, its drain electrode is electrically connected this pixel electrode, and this memory capacitance is electrically connected on this pixel electrode and common electrical

The utmost pointBetween.

8. liquid crystal indicator, it comprises one first substrate, one second substrate that is oppositely arranged with this first substrate, one is sandwiched in the liquid crystal layer between this first substrate and second substrate, one sequential control circuit, a scan driving circuit and a data drive circuit, this second substrate comprises many sweep traces that are parallel to each other, many the data lines that are parallel to each other and intersect vertically with the insulation of this sweep trace, a plurality of pixel cells that this sweep trace and this data line define, this scan drive circuit is used to drive this sweep trace, this data drive circuit is used to drive this data line, it is characterized in that: this liquid crystal indicator also comprises a reference voltage control circuit and a comparer, this comparer will be transferred to the pulse signal voltage of this scan drive circuit and the reference voltage of this reference voltage control circuit output compares, and comparative result outputed to this sequential control circuit, this sequential control circuit is output as high level or low level according to the enable signal of this comparative result output one control output to control this scan drive circuit sweep signal.

9. liquid crystal indicator as claimed in claim 8, it is characterized in that: the pulse signal that is transferred to this scan drive circuit exports the normal phase input end of this comparer to, and the reference voltage of this reference voltage control circuit output is from the inverting input input of this comparer.

10. driving method as liquid crystal indicator as described in the claim 8, it comprises the steps:

A. pulse signal is input to this scan drive circuit, and this scan drive circuit produces a plurality of sweep signals, and is applied to this multi-strip scanning line successively;

B. this comparer reference voltage that will be transferred to the pulse signal voltage of this scan drive circuit and the output of this reference voltage control circuit compares, and comparative result is outputed to this sequential control circuit;

C. this sequential control circuit is output as high level or low level according to the enable signal of the output of the comparative result among the step b one control output to control this scan drive circuit sweep signal.

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