CN101136184A

CN101136184A - Electric charge recycling circuit Thin-film transistor type LCD source drive chip

Info

Publication number: CN101136184A
Application number: CNA2007100184787A
Authority: CN
Inventors: 魏廷存; 李丹; 丁行波
Original assignee: Xi'an Longteng Micro-Electronics Tech Development Co Ltd
Current assignee: Xi'an Longteng Micro-Electronics Tech Development Co Ltd
Priority date: 2007-08-15
Filing date: 2007-08-15
Publication date: 2008-03-05

Abstract

A thin-film transistor liquid-crystal display screen (TFT-LCD) source-drive chip charge recovering circuit is disclosed. Six output passages to which each two adjacent pixels of the chip are corresponding form a group, two source-drive wires with same color property in each group are used as a charge recovering pair, so that(Ri,Ri+1),(Gi,Gi+1),(Bi,Bi+1) form three charge recovering pairs. In effective period of the TFT-LCD charge recovering control signal, the chip drive circuit and the load are isolated, and every charge revering pair is short connected. Based on the space relative and time relative properties displayed by TFT-LCD, the voltage of all sub pixel points is neutralized to VCOM which is half of simulated power supply voltage VDD so that dynamic power consumption is saved 50%.

Description

The electric charge recycling circuit of Thin-film transistor type LCD source drive chip

Technical field

The present invention relates to a kind of electric charge recycling circuit of Thin-film transistor type LCD source drive chip.

Background technology

The function of the electric charge recycling circuit of the source drive chip of Thin-film transistor type LCD (TFT-LCD:Thin Film Transistor-Liquid Crystal Display) is to reduce the dynamic power consumption of source drive chip.

With reference to Fig. 2, document " S.S.Yang; P.L.Guo; T.Y. Chang and J.H.Hong; " Alow-power TFT-LCDColumn driver design for dot-inversion Method; " IEICE Trans.Fundamentals, vol.E87-A, no.2, pp.364-369, Feb.2004. " disclose a kind of electric charge recycling circuit of Thin-film transistor type LCD source drive chip, wherein source driving circuit is represented the part of other except that electric charge recycling circuit in the source drive chip, and the equivalence of TFT-LCD display screen becomes the RC load of series connection.According to the drive principle of a upset, the driving voltage polarity of neighbor pixel is opposite.Utilize this characteristic, it is right that two adjacent source drive wires are reclaimed as electric charge, is about to R1 and G1, B1 and R2, and difference short circuits such as G2 and B2 are in the same place.In the time will loading the driving voltage of next line, at first TFT-LCD load and source drive chip are disconnected, and with two adjacent source drive wire short circuits, because its polarity is opposite, so a part of voltage that can neutralize.The chip voltage amplitude that need discharge and recharge reduces like this, has reached the purpose of saving dynamic power consumption.When the data of neighbor pixel were identical, voltage can neutralize just, its control timing and discharge and recharge waveform as shown in Figure 3.Can save 50% dynamic power consumption in this case.

Yet in most cases, display image is not pure color but coloured image, the video data that is adjacent subpixels point is unequal, causes R1 and G1, B1 and R2, the voltage magnitude of G2 and B2 is unequal, and voltage can not fully be neutralized, and the dynamic power consumption that can save is less than 50%.

Summary of the invention

In order to overcome in the prior art voltage and inadequate deficiency, the invention provides a kind of electric charge recycling circuit of Thin-film transistor type LCD source drive chip.As shown in Figure 1, at per two neighbor pixel (R _i, G _i, B _i) and (R _I+1, G _I+1, B _I+1), form three electric charges and reclaim (R _i, R _I+1), (G _i, G _I+1), (B _i, B _I+1), i=1 wherein, 2 ..., N-1.Before each amplifier drives load, at first disconnect the transmission gate switch between amplifier and load, promptly separate amplifier and load, it is right to reclaim with all electric charges of transmission gate switch short circuit simultaneously.Based on space correlation and time correlation characteristic that TFT-LCD shows, the voltage of all sub-pixel points is neutralized to VCOM, and promptly half of analog power voltage VDD can be saved 50% dynamic power consumption.

The technical solution adopted for the present invention to solve the technical problems: a kind of electric charge recycling circuit of Thin-film transistor type LCD source drive chip, be characterized in one group of pairing six output channel of per two neighbors of chip, it is right that two the every group source drive wires with same color attribute are reclaimed as an electric charge, i.e. (R _i, G _i, B _i) and (R _I+1, G _I+1, B _I+1), form three electric charges altogether and reclaim rightly, reclaim the control signal valid period at the electric charge of TFT-LCD, the source driving circuit of isolating chip and load, and each electric charge reclaimed short circuit.

The invention has the beneficial effects as follows: because at every group of two neighbor pixel (R _i, G _i, B _i) and (R _I+1, G _I+1, B _I+1), form three electric charges and reclaim (R _i, R _I+1), (G _i, G _I+1), (B _i, B _I+1), i=1 wherein, 2 ..., N-1.Before each amplifier drives load, at first disconnect the transmission gate switch between amplifier and load, promptly separate amplifier and load, it is right to reclaim with all electric charges of transmission gate switch short circuit simultaneously.Based on space correlation and time correlation characteristic that TFT-LCD shows, the voltage of all sub-pixel points is neutralized to VCOM, and promptly half of analog power voltage VDD all can be saved 50% dynamic power consumption.

Below in conjunction with drawings and Examples the present invention is elaborated.

Description of drawings

Fig. 1 is the electric charge recycling circuit figure of Thin-film transistor type LCD source drive chip of the present invention.

Fig. 2 is the electric charge recycling circuit of prior art Thin-film transistor type LCD source drive chip.

Fig. 3 is the electric charge recycling circuit control timing of prior art Thin-film transistor type LCD source drive chip and discharges and recharges waveform.

Embodiment

With reference to Fig. 1, the present invention is under the prerequisite that does not increase circuit complexity and chip area, further reduce the dynamic power consumption that source drive chip discharges and recharges the TFT-LCD large capacitive load, improved the response speed of chip drives TFT-LCD simultaneously, helped the high speed dynamic menu to show.

Common display image and TFT-LCD point flip displays mode have two characteristics: space correlation and time correlation.Space correlation: adjacent two color of pixel are identical or close.Because the color in most of zones is gradual changes in the piece image, and for two adjacent pixels (each pixel comprises three continuous sub-pixel points), its color is in most of the cases approaching or consistent, it is opposite to be that the sub-pixel point that has the same color attribute in the neighbor contains polarity, the magnitude of voltage that amplitude is identical.Time correlation: the display image of adjacent two frames in front and back is identical or close.Because the liquid crystal display per second need show 60 two field pictures at least, so every width of cloth image needs to show continuously some frames; Simultaneously, very big correlativity is arranged between most of dynamic images.Like this concerning each pixel, the color basically identical of two frames before and after can thinking, concerning each sub-pixel point, its voltage magnitude is equal substantially, and polarity is opposite.

One group of pairing six output channel of per two neighbors of chip, it is right that per two the source drive wires with same color attribute are reclaimed as an electric charge, i.e. (R _i, R _I+1), (G _i, G _I+1), (B _i, B _I+1), it is right to form three electric charges recovery altogether.Before drive TFT-LCD (electric charge is between payback period for CS=1, CSN=0), the driving circuit of isolating chip and load reclaim each electric charge to short circuit.Because it is opposite that each electric charge reclaims the polarity of two right pixels, voltage magnitude is identical, so just in time can be neutralized to the intermediate value VCOM of VDD.When driving load (CS=0, CSN=1 is during the driving), because the target voltage of each sub-pixel point is identical with the previous frame size, polarity is opposite, and the voltage magnitude that all pixels need drive just is original half, can save 50% dynamic power consumption like this.And traditional method is only when showing monochrome image, and promptly identical (G2=B2) Shi Caineng reaches 50% dynamic power consumption and saves the data of all pixels for R1=G1, B1=R2, and this value is lower than 50% under general polyenergetic color display image situation.Method of the present invention all can be saved the dynamic power consumption near 50% under any display image situation, especially more effective to general polyenergetic color display image.In addition, along with reducing of charging/discharging voltage amplitude, the responsiveness of chip also has raising than before, helps to show and driving giant-screen high speed dynamic image.

Claims

1. the electric charge recycling circuit of a Thin-film transistor type LCD source drive chip, it is characterized in that: one group of pairing six output channel of per two neighbors of chip, it is right that two every group source drive wires adjacent, that have the same color attribute are reclaimed as an electric charge, i.e. (R _i, R _I+1), (G _i, G _I+1), (B _i, B _I+1), form three electric charges altogether and reclaim rightly, reclaim the control signal valid period at the electric charge of TFT-LCD, the source driving circuit of isolating chip and load, and each electric charge reclaimed short circuit.