CN102005197B - Liquid crystal display driving circuit and related driving method - Google Patents

Abstract

The invention relates to a liquid crystal display driving circuit and a related driving method. The driving circuit of the liquid crystal display comprises a temperature sensor and a power integrated circuit. The temperature sensor is used for detecting the operating environment temperature of the liquid crystal display and generating a corresponding temperature signal according to the operating environment temperature. The power integrated circuit is used for providing a plurality of groups of clock pulse signals to drive a grid driving circuit of the liquid crystal display and adjusting the effective pulse width of the plurality of groups of clock pulse signals according to the temperature signal.

Description

Liquid crystal display drive circuit and drive method thereof

Technical field

The present invention relates to a kind of liquid crystal display drive circuit and drive method thereof mutually, the espespecially a kind of initial bad liquid crystal display drive circuit of low temperature and drive method thereof of improving.

Background technology

Liquid crystal display (liquid crystal display, LCD) have low radiation, volume is little and the advantage such as low power consuming, replace gradually traditional cathode-ray tube display (cathode ray tube display, CRT), thereby be widely used in notebook computer, personal digital assistant (personal digital assistant, PDA), flat-surface television, or on the information product such as mobile phone.

Please refer to Fig. 1 and Fig. 2, Fig. 1 is the synoptic diagram of a liquid crystal display 100 in the prior art, and Fig. 2 is the synoptic diagram of a liquid crystal display 200 in the prior art.Liquid crystal display 100 and 200 respectively comprises a display panels 110, time schedule controller (timing controller) 120, one source pole driving circuit (source driver) 130, one gate driver circuit (gate driver) 140, many data line DL ₁～DL _m, many gate lines G L ₁～GL _n, and a picture element matrix.Picture element matrix is located on the display panels 110 and is comprised a plurality of pixel cell PX, and each pixel cell comprises a thin film transistor (TFT) (thin film transistor, TFT) switching TFT, a liquid crystal capacitance C _LCWith a storage capacitors C _ST, be respectively coupled to corresponding data line, corresponding gate line, and a common voltage V _COM Time schedule controller 120 can produce source electrode drive circuit 130 and required control signal and the clock pulse signal of gate driver circuit 140 runnings, so that source electrode drive circuit 130 can produce the data drive signal SD corresponding to show image according to this ₁～SD _m, and so that gate driver circuit 140 can produce the required gate drive signal SG of unlatching thin film transistor switch TFT according to this ₁～SG _n

In liquid crystal display shown in Figure 1 100, gate driver circuit 140 is external drive circuit, and it exports gate drive signal SG by many group grid-driving integrated circuits (gate driver IC) 142 ₁～SG _nIn liquid crystal display shown in Figure 2 200, gate driver circuit 140 utilizes and is integrated in liquid crystal panel (gate on array, GOA) technology is made, also be about to gate driver circuit 140 and be integrated on the display panels 110 that pixel cell PX is set, and by many group shift LD (shift register) cell S R ₁～SR _nExport respectively gate drive signal SG ₁～SG _n, therefore can reduce chip use amount and signal lead.

Tradition grid-driving integrated circuit framework and GOA framework all need shifting deposit unit and level shifter (level shifter), and level shifter is used for carrying collection of letters current potential to increase its driving force.The tradition grid-driving integrated circuit uses CMOS technique that shifting deposit unit and voltage potential shift unit are incorporated into one chip.In the GOA framework, shifting deposit unit utilizes TFT technique to make, and level shifter is incorporated in the pulse width modulation integrated circuit (PWM IC).Because On current ION and its grid voltage VGH of thin film transistor switch are directly proportional, and can diminish along with the external environment drop in temperature, that is the opening speed of thin film transistor (TFT) can Yin Wendu reduces and slack-off, so the problem of low temperature initial bad (cold-start) occurs under low temperature environment the GOA liquid crystal display easily.Under the low-temperature operation environment, prior art generally can increase by the grid voltage VGH that draws high thin film transistor switch the On current ION of thin film transistor switch, so can cause extra power consumption.

Summary of the invention

The invention provides a kind of driving circuit of liquid crystal display, it comprises a temperature-sensitive sticker, is used for detecting the operating environment temperature of this liquid crystal display and produces according to this a corresponding temperature signal; And a power integrated circuit, be used to provide many group clock pulse signals driving a gate driver circuit of this liquid crystal display, and adjust the effective pulse widths of this many group clock pulse signals according to this temperature signal.

The present invention provides a kind of driving method of liquid crystal display in addition, and it comprises when the operating environment temperature of this liquid crystal display is no more than a predetermined value, provides many groups clock pulse signal of tool one first effective pulse width to drive this liquid crystal display; And when the operating environment temperature of this liquid crystal display surpasses this predetermined value, provide many groups clock pulse signal of tool one second effective pulse width to drive this liquid crystal display, wherein this first effective pulse width is greater than this second effective pulse width.

Description of drawings

Fig. 1 and Fig. 2 are the synoptic diagram of liquid crystal display in the prior art;

Fig. 3 is the synoptic diagram of liquid crystal display among the present invention;

Fig. 4 is the synoptic diagram of temperature-sensitive sticker and power integrated circuit in the embodiment of the invention;

Fig. 5 A and Fig. 5 B are the synoptic diagram of liquid crystal display driving method of the present invention.

Wherein, Reference numeral

350 temperature-sensitive stickers 110,310 display panels

360 power integrated circuits 120,320 time schedule controllers

370 potential shift unit 130,330 source electrode drive circuits

380 pulse width adjustment units 140,340 gate driver circuits

142 grid-driving integrated circuit SW1, SW2 switch

PX pixel cell SR ₁～SR _nShifting deposit unit

C _LCLiquid crystal capacitance DL ₁～DL _mData line

C _STStorage capacitors GL ₁～GL _nGate line

DTS end points R1, R2, R3 resistance

C electric capacity RT thermistor

TFT thin film transistor switch AVDD2, AVDD2 voltage source

100,200,300 liquid crystal display COMP1, COMP2 comparer

Embodiment

Fig. 3 is the synoptic diagram of a liquid crystal display 300 among the present invention.Liquid crystal display 300 comprises a display panels 310, time schedule controller 320, one source pole driving circuit 330, a gate driver circuit 340, a temperature-sensitive sticker 350, a power integrated circuit (power IC) 360, many data line DL ₁～DL _m, many gate lines G L ₁～GL _n, and a picture element matrix.Picture element matrix is located on the display panels 310 and is comprised a plurality of pixel cell PX, and each pixel cell comprises a thin film transistor switch TFT, a liquid crystal capacitance C _LCWith a storage capacitors C _ST, be respectively coupled to corresponding data line, corresponding gate line, and a common voltage V _COMTime schedule controller 320 can produce source electrode drive circuit 330, gate driver circuit 340 and required initial pulse signal VST and the reference clock pulse signal CK of power integrated circuit 360 runnings ₁～CK _nDeng, so that source electrode drive circuit 330 can produce the data drive signal SD corresponding to show image according to this ₁～SD _m, and so that power integrated circuit 360 can produce the required output clock pulse signal CK of gate driver circuit 340 runnings according to this ₁'～CK _n'.In liquid crystal display 300, gate driver circuit 340 utilizes the GOA technology to make, and also is about to gate driver circuit 340 and is integrated on the display panels 310 that pixel cell PX is set.According to initial pulse signal VST and output clock pulse signal CK ₁'～CK _n', gate driver circuit 340 can be by many group shifting deposit unit SR ₁～SR _nProduce respectively and open the required gate drive signal SG of thin film transistor switch TFT ₁～SG _n

Temperature-sensitive sticker 350 is used for detecting the operating environment temperature of liquid crystal display 300, and produces according to this a corresponding temperature signal Sg.Power integrated circuit 360 comprises a potential shift unit 370 and a pulse width adjustment unit 380.Potential shift unit 370 can promote reference clock pulse signal CK ₁～CK _nCurrent potential, and pulse width adjustment unit 380 can be adjusted reference clock pulse signal CK according to temperature signal Sg ₁～CK _nEffective pulse width.Therefore, the output clock pulse signal CK that provides of power integrated circuit 360 ₁'～CK _n' its voltage potential is than reference clock pulse signal CK ₁～CK _nBe height, and effective pulse width can be different with temperature.

In the present invention, reference clock pulse signal CK ₁～CK _nCurrent potential can between an activation current potential and a decapacitation current potential, switch with a predetermined period, the activation current potential refers to the current potential that the conducting membrane transistor switch is required, and effective pulse width refers to reference clock pulse signal CK ₁～CK _nIn fact maintain the activation current potential during.In other words, the present invention increases the ON time of thin film transistor switch under the low-temperature operation environment, with the On current of the compensation film transistor switch characteristic with drop in temperature, and then improves the initial bad situation of low temperature.

For instance, suppose to judge that the initial critical temperature of low temperature is made as 25 ℃: when the operating environment temperature that detects liquid crystal display 300 when temperature-sensitive sticker 350 was higher than 25 ℃, pulse width adjustment unit 380 can provide the output clock pulse signal CK of the less effective pulse width of tool ₁'～CK _n'; When the operating environment temperature that detects liquid crystal display 300 when temperature-sensitive sticker 350 was lower than 25 ℃, pulse width adjustment unit 380 can provide the output clock pulse signal CK of the larger effective pulse width of tool ₁'～CK _n', to strengthen the ability of driving grid driving circuit 340.Simultaneously, according to output clock pulse signal CK ₁'～CK _n', shifting deposit unit SR ₁～SR _nThe gate drive signal SG that when low temperature, produces ₁～SG _nAlso can the larger effective pulse width of tool, and then improve the initial bad situation of panel pixel low temperature.

According to temperature signal Sg, pulse width adjustment unit 380 can be adjusted reference clock pulse signal CK by the top rake mode ₁～CK _nEffective pulse width, for example at reference clock pulse signal CK ₁～CK _nThe waveform drop edge discharge, and come at reference clock pulse signal CK by adjusting discharge starting point, intensity and time span ₁～CK _nThe waveform drop edge cause different top rake effects, and then change effective pulse width.Fig. 4 is the synoptic diagram of temperature-sensitive sticker 350 and power integrated circuit 360 in the embodiment of the invention.Temperature-sensitive sticker 350 comprises a resistance R 1, a thermistor RT, a comparator C OMP1, and an interrupteur SW 1.Thermistor RT is variable-resistance a kind of, and its resistance value can change along with temperature variation.The bleeder circuit that forms by resistance R 1, thermistor RT and a voltage source AVDD1 can provide corresponding to a present reference voltage V of liquid crystal display 300 operating environment temperature _REF1To the positive input terminal of comparator C OMP1, the negative input end of comparator C OMP1 then receives the voltage V corresponding to the initial critical temperature of low temperature (for example 25 ℃) _THInterrupteur SW 1 can be a metal oxide semiconductor transistor switch: (V under the normal-temperature operation environment _REF1＞V _TH) time, the temperature signal Sg of comparator C OMP1 meeting output device activation current potential is with actuating switch SW1; (V under the low-temperature operation environment _REF1＜V _TH) time, the temperature signal Sg of comparator C OMP1 meeting output device decapacitation current potential is with closing switch SW1.

In the embodiment shown in fig. 4, pulse width adjustment unit 380 possesses the top rake function, and it comprises a capacitor C, resistance R 2 and R3, a comparator C OMP2, and an interrupteur SW 2.When interrupteur SW 1 not conducting, voltage source AVDD2 can come charging capacitor C by resistance R 2; When interrupteur SW 1 conducting, capacitor C internal memory energy can be sent to end points DTS, and is higher than reference voltage V at the current potential (positive input terminal of comparator C OMP2) of end points DTS _REF2Current potential (negative input end of comparator C OMP2) time discharge by resistance R 3, and then at reference clock pulse signal CK ₁～CK _nThe waveform drop edge begin top rake; When the current potential of end points DTS is lower than reference voltage V _REF2Current potential the time, interrupteur SW 2 not conductings and top rake stops.The value of capacitor C and resistance R 2 can determine the top rake slope, and reference voltage V _REFCan determine top rake time length with the value of capacitor C.The duration of charging T of capacitor C _CHARGEWith T discharge time _DISCHARGECan be represented by following formula:

$T_{\mathrm{CHARGE}}=-R2\×C\×\ln \left(\frac{\mathrm{AVDD}2-V_{\mathrm{REF}2}}{\mathrm{AVDD}2\×\frac{R2}{R2+R3}}\right)$

$T_{\mathrm{DISCHARGE}}=-R3\×C\×\ln \left(\frac{\mathrm{AVDD}2\×\frac{R3}{R2+R3}}{V_{\mathrm{REF}2}}\right)$

Fig. 5 A and Fig. 5 B are the synoptic diagram of liquid crystal display driving method of the present invention, and Fig. 5 A is the output clock pulse signal CK that (for example temperature is lower than 25 ℃) provides under the low-temperature operation environment ₁'～CK _n', and Fig. 5 B is the output clock pulse signal CK that (for example temperature is higher than 25 ℃) provides under the normal-temperature operation environment ₁'～CK _n'.Shown in Fig. 5 A and Fig. 5 B, by pulse width adjustment unit 380 of the present invention, output clock pulse signal CK under the low temperature ₁'～CK _n' effective width W1 greater than output clock pulse signal CK under the normal temperature ₁'～CK _n' effective width W2, therefore can increase the ON time of thin film transistor switch when low temperature.

According to the temperature signal Sg corresponding to the operating environment temperature, pulse width adjustment unit 380 of the present invention can be adjusted reference clock pulse signal CK by different way ₁～CK _nEffective pulse width, the effective pulse width that shortens signal with the top rake discharge mode shown in Figure 4 for example.Yet shown in Figure 4 only is embodiments of the invention, does not limit category of the present invention.

Under the low-temperature operation environment, the present invention opens thin film transistor switch with the larger signal of effective pulse width, that is the ON time of thin film transistor switch when low temperature is longer, with the On current of the compensation film transistor switch characteristic with drop in temperature, and then improve the initial bad situation of low temperature.

Certainly; the present invention also can have other various embodiments; in the situation that does not deviate from spirit of the present invention and essence thereof; those of ordinary skill in the art work as can make according to the present invention various corresponding changes and distortion, but these corresponding changes and distortion all should belong to the protection domain of the appended claim of the present invention.

Claims (6)

1. A driving circuit for a liquid crystal display, characterized in that it comprises: A temperature sensor is used to detect the operating environment temperature of the liquid crystal display and accordingly generate a corresponding temperature signal; wherein, the temperature sensor further includes a first resistor, a thermistor, a first A comparator and a first switch, under normal temperature operating environment, the first comparator will output a temperature signal with enable potential to turn on the first switch; under low temperature operating environment, the first comparator will outputting a temperature signal with a disabling potential to close the first switch; and A power integrated circuit is used to provide multiple sets of clock pulse signals to drive a gate drive circuit of the liquid crystal display, and adjust the effective pulse width of the multiple sets of clock pulse signals according to the temperature signal; the power integrated circuit includes: a The potential shift unit is used to increase the potential of the multiple sets of clock pulse signals; and an adjustment unit is used to chamfer the multiple sets of clock pulse signals according to the temperature signal, and then adjust the effective pulses of the multiple sets of clock pulse signals width; Wherein, the adjustment unit further includes a capacitor, a second resistor and a third resistor, a second comparator, and a second switch. When the first switch is not turned on, the voltage source can pass through the second resistor to charge the capacitor; when the first switch is turned on, when the potential of the positive input terminal of the second comparator is higher than the potential of the given reference voltage, the capacitor is discharged through the third resistor, and then the multiple sets of clock pulses The falling edge of the signal waveform begins to clip; when the potential of the positive input terminal of the second comparator is lower than a given reference voltage, the second switch is not turned on and the clipping stops. the 2. The drive circuit according to claim 1, characterized in that: When the operating environment temperature of the liquid crystal display does not exceed a predetermined value, the power integrated circuit outputs the plurality of sets of clock pulse signals with a first effective pulse width; and When the operating environment temperature of the liquid crystal display exceeds the predetermined value, the power integrated circuit discharges at the falling edges of the waveforms of the plurality of sets of clock pulse signals in a chamfering manner, and then outputs the plurality of sets of clock pulse signals with a second effective pulse width A clock pulse signal, and the first effective pulse width is greater than the second effective pulse width. the 3. a driving method of the driving circuit of the liquid crystal display described in claim 1 or 2, is characterized in that, it comprises: When the operating environment temperature of the liquid crystal display does not exceed a predetermined value, providing multiple sets of clock pulse signals with a first effective pulse width to drive the liquid crystal display; and When the operating environment temperature of the liquid crystal display exceeds the predetermined value, multiple sets of clock pulse signals with a second effective pulse width are provided to drive the liquid crystal display, wherein the first effective pulse width is greater than the second effective pulse width. the 4. driving method according to claim 3, is characterized in that, it additionally comprises: When the operating environment temperature of the liquid crystal display exceeds the predetermined value, the multiple sets of clock pulse signals are cut to reduce the effective pulse width of the multiple sets of clock pulse signals. the 5. driving method according to claim 4, is characterized in that, it additionally comprises: According to the operating environment temperature of the liquid crystal display, the angle-off slope or the off-angle time length of the plurality of sets of clock pulse signals are adjusted. the 6. driving method according to claim 5, is characterized in that, it additionally comprises: The pixels of the liquid crystal display are scanned during the effective pulse widths of the plurality of sets of clock pulse signals. the

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