CN101727853A - Liquid crystal display and control method thereof - Google Patents
Liquid crystal display and control method thereof Download PDFInfo
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- CN101727853A CN101727853A CN200810173924A CN200810173924A CN101727853A CN 101727853 A CN101727853 A CN 101727853A CN 200810173924 A CN200810173924 A CN 200810173924A CN 200810173924 A CN200810173924 A CN 200810173924A CN 101727853 A CN101727853 A CN 101727853A
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Abstract
The invention discloses a liquid crystal display and a control method thereof. A time schedule controller is used for detecting an external frequency signal of the liquid crystal display, and a switching control signal is output according to the external frequency signal to start a power-off switching circuit, so that the power-off switching circuit controls the output voltages of a gamma voltage generator and a common voltage circuit according one of the messages of the switch control signal respectively; thus, the voltage difference between a pixel electrode of a pixel and a common electrode is regulated to reach zero to completely release the pixel loads after the power off so as to realize the aim of instantly eliminating shutdown images.
Description
Technical field
The present invention relates to kind of LCD and control method thereof, particularly relate to a kind of LCD and the control method thereof that can effectively eliminate afterimage.
Background technology
LCD uses occupation rate quite high in each application because of its frivolous, no width of cloth is penetrated, the soft characteristic such as eye of not hindering of low power consumption, long service life, picture.Be main flow on the market wherein with the tft type liquid crystal display (TFT-LCD) of active-matrix type.
The synoptic diagram of general TFT-LCD driving circuit is with reference to shown in Figure 1, in whole liquid crystal display panel 10 frameworks, have a plurality of pixels 11 that are arranged, each pixel 11 has thin film transistor (TFT) (TFT) 12 as switch, its grid is connected to the sweep trace 13 of horizontal direction, drain electrode is connected to the data line 14 of vertical direction, and source electrode is connected to the electrode tip (for example pixel electrode) of liquid crystal capacitance 8 and storage capacitors 9, as shown in Figure 1, wherein, another electrode tip (for example common electrode) of liquid crystal capacitance 8 and storage capacitors 9 is connected common voltage Vcom (also being Cs on common type) jointly usually; Yet in the display panels of another type (not shown), another electrode tip of liquid crystal capacitance 8 connects common voltage Vcom, and the voltage of another electrode tip of storage capacitors 9 provides (also being Cs on gate type) by the voltage on the sweep trace 13.Many data lines 14 are driven by source electrode driver 15, and 13 on multi-strip scanning line is driven by gate drivers 16.Simultaneously with reference to shown in Figure 2, LCD 23 has comprised display panels 10 and in order to drive the control system of this display panels 10, in the operation of LCD 23, usually give dc power converter 18 by input interface 17 supply powers, then, dc power converter 18 is supplied required operating voltage such as gamma voltage generator 19, time schedule controller 21 and common potential circuit 20 respectively.Gamma voltage generator 19 output reference voltages (reference voltage) are given source electrode driver 15, make that source electrode driver 15 can be according to this reference voltage and the pixel data signal that is provided by time schedule controller 21, produce corresponding pixel grey scale voltage and give the pixel electrode of the pixel in the display panels 10, common voltage circuit 20 then produces the common electrode of common voltage (Vcom) to pixel, so that the liquid crystal capacitance two ends produce pressure reduction, cause the liquid crystal rotation, and then produce image; 21 outside clock signals that provide according to input interface 17 of time schedule controller (external clock) and pixel data signal come control gate driver 16 and source electrode driver 15 operations.So be that each pixel 11 is operated and image is presented on the display panels 10 according to the data-signal of input in the may command display panels 10.
In detail, TFT-LCD mainly utilizes the switch of grid, to the pixel electrode charge or discharge of liquid crystal capacitance; When a certain sweep trace was applied in enough big voltage (for example Vgh), transistor gates all on it all were opened, and each pixel electrode will be write corresponding pixel grey scale voltage by individual other data line this moment; Through after the charging of appropriate time, this sweep trace then is applied in enough little voltage (for example Vgl), with closeall grid, and with the maintenance of pixel electrode electric charge within a certain period of time, this is a kind of current potential maintenance display (Holding type display).In the general normal operation time, grid is constantly opened and is closed, and pixel data constantly upgrades; When closing tester in power-down state, all voltages are closed and are returned to 0 volt, and all grids on the sweep trace will no longer be opened, and pixel electrode will keep the voltage data of preceding last picture of shutdown, until the effect of leaking electricity naturally all electric charges are discharged.At this moment, because the electric charge of each pixel electrode discharges inhomogeneous and release rate is slow on the display panels, the visual appearance of shutdown back picture will present afterimage, contrast changes white by black, ghost position, area size and colourity differ, and this power-off ghost shadow phenomenon is with the electric charge hold facility of the plain electrode of video.
Be head it off, be between input interface 17 and gate drivers 16, to set up replacement IC 22 at present, as shown in Figure 2, it is to shut down moment in LCD, the decline of using replacement IC 22 to detect the Vdd voltage of input interface 17 changes, after the change triggers of Vdd voltage should replacement IC, its with the XAO signal sets to low level, gate drivers 16 with reference to this XAO signal after, make all sweep traces export Vgh voltage simultaneously, the grid of all thin film transistor (TFT)s is opened simultaneously, allowed the electric charge of pixel electrode of all pixels of display panels 10 derive discharge, to accelerate the speed that power-off ghost shadow disappears by data line.
In addition, it is directly to utilize time schedule controller (TCON IC) to detect the action of shutdown that another kind is done rule, successively each row pixel is inserted black picture then, release after going to same angle with liquid crystal, to solve the power-off ghost shadow problem with liquid crystal capacitance in all pixels of panel.
Yet, though above-mentioned utilization replacement IC can solve the problem of power-off ghost shadow, but need to increase material cost, and all sweep traces are exported Vgh voltage simultaneously when shutdown, will be owing to Vgh voltage instantaneous electric current be excessive, the bad phenomenon of normal generating electrodes puncture between the panel Vgh pin (pad) that causes glass flip chip substrate (COG) design and the COG IC conductive projection; Or be in the switching on and shutting down operation of short time, cause the problem of the white picture of start (Power Dip).In addition, utilize successively each row pixel is write black picture to eliminate the method for power-off ghost shadow, then also have ghost to eliminate the problem that speed slowly reaches discharge rate inequality between each pixel.
Therefore, the present invention proposes a kind of LCD and control method thereof, with the problem of effective elimination afterimage.
Summary of the invention
Fundamental purpose of the present invention is to provide a kind of LCD and control method thereof, it is under the function that does not influence the available circuit framework, utilize the effect of shutdown commutation circuit, when LCD is shut down, control data line voltage and common voltage are output as the mode of identical voltage, postboost pixel electric charge is discharged, to reach the purpose of moment elimination power-off ghost shadow.
Another object of the present invention is to provide a kind of LCD and control method thereof, the action of the XAO signal of its IC that avoids resetting is to export the mode of Vgh voltage simultaneously with gate-drive IC, so can reduce material cost, solve the problem that there is the white picture of start in replacement IC, and solve the electrode breakdown problem that causes because of the Vgh transient voltage is excessive.
A further object of the present invention is to provide a kind of LCD and control method thereof, it is continued to use existing time schedule controller (TCON IC) and detects off signal, so can existing display control system framework be done under the situation of significantly change design not needing, reach relevant control purpose and function.
In order to achieve the above object, one embodiment of the present of invention propose a kind of LCD, comprise time schedule controller, are used for the foreign frequency signal of detection LCD monitor, and give the shutdown commutation circuit according to this foreign frequency signal output switch-over control signal; Dc power converter is used to provide first operating voltage to this time schedule controller and second operating voltage; The shutdown commutation circuit, it connects this time schedule controller and receives this second operating voltage; Make the shutdown commutation circuit can according to the information of this switch-over control signal one of them, control the output voltage of gamma voltage generator and common voltage circuit respectively, so that the pixel electrode of pixel and the voltage difference of common electrode are adjusted to zero.
In addition, another embodiment of the present invention proposes a kind of control method of LCD, and it provides earlier first operating voltage and second operating voltage to time schedule controller and shutdown commutation circuit respectively; Whether have foreign frequency signal, and export switch-over control signal in view of the above and give the shutdown commutation circuit if utilizing this time schedule controller to detect again; Make gamma voltage generator and common voltage circuit produce first reference voltage and first common voltage respectively or produce the second group of reference voltage and second common voltage respectively according to this control switching circuit, wherein the pixel electrode of pixel and the voltage difference of common electrode are adjusted to zero, make all liquid crystal pixel cross-pressure vanishing by second reference voltage and second common voltage.
Below by be described with reference to the accompanying drawings the effect that can be easier to understand purpose of the present invention, technology contents, characteristics and be reached by specific embodiment.
Description of drawings
Fig. 1 is the circuit diagram of general LCD;
Fig. 2 solves the control circuit block diagram of ghost problem for prior art;
Fig. 3 is the block diagram of control device of the present invention;
Fig. 4 is the pixel equivalent circuit synoptic diagram in the display panels of the present invention's use;
Fig. 5 is the detailed circuit diagram of the embodiment of shutdown commutation circuit of the present invention;
Fig. 6 is the sequential chart of control device of the present invention when start;
Fig. 7 is the time sequential routine figure of control device of the present invention during shutting down;
Fig. 8 is the time sequential routine figure of control device of the present invention during not having shutdown;
Display panels the practical photograph synoptic diagram when shutting down of Fig. 9 (a) for using control device of the present invention;
Practical photograph synoptic diagram when Fig. 9 (b) is the shutdown of general display panels.
[primary clustering symbol description]
8 liquid crystal capacitances, 9 storage capacitors
10 display panels, 11 pixels
12 thin film transistor (TFT)s, 13 sweep traces
14 data lines, 15 source electrode drivers
16 gate drivers, 17 input interfaces
18 dc power converter, 19 gamma voltage generators
20 common voltage circuit, 21 time schedule controllers
22 replacement IC, 23 LCD
30 input interfaces, 32 dc power converter
33 LCD
34 time schedule controllers, 36 gate drivers
38 gamma voltage generators, 40 source electrode drivers
42 common voltage circuit, 44 display panels
46 shutdown commutation circuits, 48 liquid crystal pixels
50 switch modules
Embodiment
The generation of power-off ghost shadow mainly is because the pixel electrode voltage of pixel and the difference of common voltage (Vcom) velocity of discharge, pixel electrode voltage can be slower than the common voltage velocity of discharge when discharge, cause liquid crystal capacitance in the process of releasing because of cross-pressure changes the variation cause light penetration, thereby human eye is seen ghost.The shutdown commutation circuit that the present invention utilizes time schedule controller (for example Tcon IC) and cooperates, making its pixel electrode voltage and common voltage of offering pixel when shutdown is the mode of same voltage level, make that no cross-pressure produces between two electrodes of liquid crystal capacitance, also just directly reach the effect of eliminating ghost.
Fig. 3 is the block diagram of control device of the present invention, as shown in the figure, includes input interface 30 in the control device of LCD 33, and it provides voltage source V dd to dc power converter 32, with power source conversion to serve as the required operating voltage of inner each assembly; Time schedule controller 34, it can connect 30 by input and receive foreign frequency signal (external clock) and pixel data signal, operation with control gate driver 36 and source electrode driver 40, wherein, generally speaking, the foreign frequency signal packet is contained in differential wave (for example: low-voltage differential (LVDS) signal, short arc differential (RSDS) signal etc.) or transistor-transistor logic (TTL) signal.Whether time schedule controller 34 can according to detecting the foreign frequency signal, and also promptly according to the input that has or not of foreign frequency signal, correspondence produces switch-over control signal; Gamma voltage generator (Gamma generator) 38, generating reference voltages (comprising one or more voltages) is given source electrode driver 40, makes it produce corresponding pixel grey scale voltage according to pixel data signal and gives corresponding pixel electrode; And common voltage circuit 42, can produce common voltage (Vcom) to each pixel in the display panels 44; Wherein, in this control device, be provided with shutdown commutation circuit 46, its input end is connected to time schedule controller 34 and dc power converter 32, and output terminal is connected to gamma voltage generator 38 and common voltage circuit 42, make gamma voltage generator 38 and common voltage circuit 40 be coupled to dc power converter 32, to obtain required separately operating voltage by shutdown commutation circuit 46.This shutdown commutation circuit 46 is subjected to the control of the switch-over control signal of time schedule controller 34, when the foreign frequency signal inputs to LCD (being that LCD is in open state) by the outside or when time schedule controller 34 can detect existing of foreign frequency signal, time schedule controller 34 will select the output first control voltage (Vdda_out as shown in the figure) to give gamma voltage generator 38 and common voltage circuit 42 by switch-over control signal control shutdown commutation circuit 46, make its generating reference voltages and common voltage respectively, wherein make source electrode driver 40 produce pixel grey scale voltage according to the pixel data signal that receives by this reference voltage and write to corresponding pixel electrode, pixel is able to display image thus; Or can't detect foreign frequency signal (foreign frequency abnormal signal for example when time schedule controller 34, faint etc.) or foreign frequency signal when stopping to input to this LCD 33 (for example LCD is in off-mode etc.), time schedule controller 34 will be controlled shutdown commutation circuit 46 and select the output second control voltage (Vdda_out) to gamma voltage generator 38 and common voltage circuit 42, make it produce another reference voltage and common voltage respectively, wherein make source electrode driver 40 produce corresponding pixel grey scale voltage by this reference voltage, make pixel grey scale voltage (being pixel electrode voltage) equate with the magnitude of voltage of common voltage, and then make the liquid crystal capacitance cross-pressure vanishing of pixel, eliminate power-off ghost shadow thus fast.
In detail, when time schedule controller 34 can detect the existence of foreign frequency signal or foreign frequency signal and inputs to LCD 33 by the outside, the input interface 30 of LCD 33 will receive foreign frequency signal and pixel data signal, and transmit it to time schedule controller 34, time schedule controller 34 is after detecting this foreign frequency signal, the switch-over control signal that output is had first level voltage is given shutdown commutation circuit 46, then, the operating voltage of shutdown commutation circuit 46 by dc power converter 32 supplies (for example Vdda_in etc.) and by its inner circuit operation, send out the first control voltage (Vdda_out) to gamma voltage generator 38 and common voltage circuit 42, as working voltage source separately, make it produce reference voltage and common voltage common electrode separately respectively to source electrode driver 40 and display panels 44.And when time schedule controller 34 can't detect foreign frequency signal or foreign frequency signal and stops to input to this LCD 33, time schedule controller 34 can't detect the foreign frequency signal, this moment, time schedule controller 34 was given shutdown commutation circuit 46 with the switch-over control signal that output has second level voltage, 46 of commutation circuits of shutdown are exported the second control voltage (Vdda_out) in view of the above and are given this gamma voltage generator 38 and this common voltage circuit 42, as its working voltage source separately, preferably, this second control magnitude of voltage is 0 volt (Ground); Simultaneously with reference to pixel equivalent circuit synoptic diagram shown in Figure 4, when making gamma voltage generator 38 and common voltage circuit 42 all receive 0 volt of voltage (when the Vdda_out of the commutation circuit of shutting down output is 0 volt), gamma voltage generator 38 also will produce one group 0 volt reference voltage by the divider resistance in it this moment, and when source electrode driver 40 receives 0 volt reference voltage, divider resistance in the source electrode driver 40 also will produce 0 volt pixel grey scale voltage to all corresponding data line, therefore, pixel electrode will be written into 0 volt of voltage; Simultaneously, because at this moment the working voltage source of common voltage circuit also is 0 volt, so it also will export 0 volt common voltage.Be 0 volt because the magnitude of voltage of pixel grey scale voltage and common voltage is identical, so the voltage of pixel electrode will all become identical 0 volt with the magnitude of voltage of the voltage of common electrode, also at this moment promptly, the picture that no matter shuts down why, the liquid crystal capacitance cross-pressure of all pixels will become zero, and then the pixel electric charge is all discharged, thereby eliminate ghost fast.In addition, what deserves to be mentioned is that be that example is done explanation though Fig. 4 is a dot structure with Cs on common, yet be not limited to this, control architecture of the present invention and its method also are applicable to the panel of the dot structure of Cs on gate.
Wherein, the detailed circuit of matching timing controller 34 employed shutdown commutation circuits 46 of the present invention sees also shown in Figure 5.Fig. 5 is an embodiment of shutdown commutation circuit 46, it is made up of passive components such as simple resistance, electric capacity and transistor, its input end receives the operating voltage of dc power converter output, Vdda_in and Vgh, and the switch-over control signal of time schedule controller 34 generations; Shutdown 46 information according to switch-over control signal of commutation circuit (for example high level voltage or low level voltage etc.) and by its internal circuit operation produce control voltage Vdda_out at its output terminal and give gamma voltage generator 38 and common voltage circuit 42.Wherein, the value of each electronic package such as resistance, electric capacity or transistor that uses in the shutdown commutation circuit 42 of the present invention, those skilled in the art can be easily along with the demand of the value of voltage Vdda_in, Vgh and Vdda_out and do the optimization adjustment, do not repeat them here.Moreover, the design of this shutdown commutation circuit 42 is according to the information of switch-over control signal the input end signal of gamma voltage generator 38 and common voltage circuit 42 to be controlled, make it produce corresponding reference voltage and common voltage respectively, so can't influence other signal output and function of the control circuit framework of original LCD.Certainly, the shutdown commutation circuit that the present invention uses also can adopt any other detailed circuit of carrying out above-mentioned functions, and be not limited in this embodiment except the circuit design of this embodiment.In addition, in another embodiment, shutdown commutation circuit 46 also can directly built-inly be integrated in interior or other Control Component of dc power converter.
After control device of the present invention has been described, next will describe control method of the present invention in detail in conjunction with each signal timing diagram.
At first, when the LCD normal boot-strap, be that time schedule controller 34 is can detect the existence of foreign frequency signal or foreign frequency signal and input to LCD by the outside time, consult Fig. 6 and shown in Figure 3 simultaneously, when electric power starting, dc power converter 32 will obtain the voltage source that provided from LCD 33 outsides from input interface 30, then, dc power converter 32 provides the required operating voltage of each Control Component of LCD inside respectively, for example, provide operating voltage Vcc to time schedule controller 34 and operating voltage Vdd_in is provided and Vgh to the shutdown commutation circuit 46.As shown in Figure 6, when display power supply is opened, it (is that operating voltage Vcc transfers enabled state to by the disable state that operating voltage Vcc will start, also promptly become high level by low level as shown in the figure), and time schedule controller 34 will receive foreign frequency signal and the pixel data signal that is inputed to LCD by the outside from input interface 30, then, time schedule controller 34 transfers to source electrode driver 40 with pixel data signal, makes it convert corresponding pixel grey scale voltage to according to pixel data signal and writes pixel electrode; In the transmission pixel data signal; time schedule controller 34 is drawn high switch-over control signal becomes first level voltage; high level voltage for example; as shown in Figure 6; and during the start normal operation, keep the high level voltage state; with control shutdown commutation circuit 46; the commutation circuit 46 of also promptly shutting down is at this moment according to the information one of them (for example high level voltage) of switch-over control signal; corresponding output first control signal (Vdda_out) makes it produce source electrode driver 40 (during non-off-mode) required reference voltage when the normal pictures display operation to gamma voltage generator 38.Consult Fig. 5 at this, when switch-over control signal is high level voltage, first control signal (Vdda_out) that shutdown commutation circuit 46 is exported will be substantially equal to the input signal Vdda_in that it receives, gamma voltage generator 38 and common voltage circuit 42 are after receiving this first control signal, it will produce reference voltage and common voltage separately respectively, and after this reference voltage transfers to source electrode driver 40, source electrode driver 40 is according to the pixel data signal that receives and utilizes the divider resistance in it to produce the pixel electrode that pixel grey scale voltage writes to correspondence that pixel is able to display image thus.
Then, consult Fig. 7, when the foreign frequency signal abnormal occurrence occurs and causes time schedule controller 21 can't detect the foreign frequency signal because of LCD shutdown stops input or signal, at this moment time schedule controller 34 will detect the foreign frequency signal stop the input or in have no progeny, continue to detect one T1 period again, after for example scanning the time of two sweep traces, if after still not having the foreign frequency signal, soon export the switch-over control signal of a low level voltage and give shutdown commutation circuit 46, with control shutdown commutation circuit 46, make its output second control voltage (Vdda_out) be substantially equal to earthing potential (ground), also promptly equal 0 volt.Shown in the circuit of Fig. 5, when switch-over control signal is low level voltage, switch module 50 direct-connected with it will be closed this moment, and shutdown commutation circuit 46 has the second control voltage (Vdda_out) of earthing potential to gamma voltage generator 38 and common voltage circuit 42 with output.And gamma voltage generator 38 is after receiving this voltage source of 0 volt, it will produce one group of 0 volt reference voltages and give source electrode driver 40, then source electrode driver 40 is receiving after this organizes 0 volt reference voltages, and its inner divider resistance is also given pixel electrode with the pixel grey scale voltage signal of 0 volt of corresponding generation; On the other hand, common voltage circuit 42 is after receiving 0 volt voltage source, also will produce 0 volt common voltage and give the common voltage electrode of liquid crystal electric capacity, at this moment two electrode tip voltages of liquid crystal capacitance will be adjusted to identical voltage (for example 0 volt), also be that its cross-pressure will be zero, to reach the effect of snap-out release ghost, above-mentionedly also be, when display is in off-mode, shutdown commutation circuit 46 at this moment will be according to the information one of them (for example low level voltage) of switch-over control signal, the corresponding output second control voltage (for example 0 volt), with the output voltage of control gamma voltage generator 38 and common voltage circuit 42, thus the pixel electrode of pixel and the voltage difference of common electrode are adjusted to zero.Consult Fig. 7 once more, be noted that, in order there to be the sufficient time that coherent signal is write liquid crystal capacitance, the low level voltage state of switch-over control signal need be kept one T2 period at least, and preferably the T2 time is for being no less than a picture scan period (or vertical-scan period), yet is not limited to this.In addition, what pay special attention to is, as shown in Figure 7, for making whole display control system the time can also carry out write operation (respectively pixel electrode and common electrode being write identical voltage) as above-mentioned pixel data signal in shutdown, operating voltage Vcc will continue to keep and just close (being disable or low level state) after opening (promptly enabling or high level state) finished to the T2 time.
Moreover, generally in display, for example in time schedule controller, build the function that is equipped with built-in type self-test/free-running operation (BIST/Free Run), though the present invention has additional the operation of shutdown commutation circuit, but this will can not influence original BIST/Free Run function, also the operation of promptly newly-increased shutdown commutation circuit still can with the operation compatibility of existing BIST/Free Run.Consult Fig. 8 and shown in Figure 3, when time schedule controller 21 detects the foreign frequency signal and stops, and counting one section T3 after the time, after for example scanning the time of two sweep traces, if after still not having the foreign frequency signal, soon export the switch-over control signal of a low level voltage and give shutdown commutation circuit 46, with control shutdown commutation circuit 46, output control voltage (for example 0 volt) voltage is to gamma voltage generator 38 and common voltage circuit 42, so that it produces reference voltage and common voltage respectively, and then produce pixel electrode and the common electrode of the voltage of the identical magnitude of voltage of tool to display panel, even also the cross-pressure of liquid crystal capacitance two electrode tips of pixel is zero; Yet the situation of whether shutting down for fear of the erroneous judgement system, time schedule controller 34 at the switch-over control signal of output low level voltage through one section T4 after the time, for example through after 5+ α picture sweep time at least (α≤1 wherein, and 5 can adjust) according to time schedule controller; If at this moment still detect operating voltage (Vcc) output, operating voltage Vcc still keeps high level voltage as shown in Figure 8, the expression display power supply is not closed yet, then time schedule controller 34 will switch to high level voltage to switch-over control signal by low level voltage, as shown in Figure 8, and pixel data signal at this moment, to be provided by the display data-signal that built-in selftest/the free-running operation pattern sets, at this moment the pixel of display panels 44 will be written into the picture under selftest/free-running operation pattern.In addition, if when time schedule controller 34 detects the foreign frequency signal once more, for example the foreign frequency signal inputs in the display by the outside again or foreign frequency signal when recovering normal pulse wave state again, when behind the t1 time point as shown in FIG. the foreign frequency signal being arranged again, at this moment pixel data signal will normally be provided once more accordingly, also be that time schedule controller 34 will detect foreign frequency signal and pixel data signal once more, at this moment for this pixel data signal is write in the pixel, at this moment switch-over control signal also need switch to the high level voltage state, certainly, at this moment operating voltage Vcc also need maintain opening, just can make system carry out relevant picture element signal write operation.
In sum, the present invention is mainly by the extra shutdown commutation circuit that is provided with, maybe can't know when detecting the foreign frequency signal at off-mode in system, pixel electrode to liquid crystal capacitance writes identical voltage (for example 0 volt) respectively with common electrode, the cross-pressure that makes liquid crystal capacitance is zero, with with postboost pixel electrode electric charge snap-out release, reach the effect of quick elimination ghost; Shown in figure 9 (a) and Fig. 9 (b), wherein Fig. 9 (a) is the display panels that the uses control device of the present invention practical photograph synoptic diagram when the shutdown, as shown in the figure, can close fully immediately after 0.34 second and does not have any ghost from the shutdown beginning; Otherwise, the practical photograph synoptic diagram when the general display panels shown in Fig. 9 (b) shuts down, the shutdown beginning all had ghost to produce in 0.34 second to 1 second certainly, just eliminated until 1.2 seconds.Therefore, the present invention can reach the effect of moment elimination power-off ghost shadow really.
Moreover, the present invention can continue to use existing time schedule controller (TCON IC) and detect off signal, and one of them pin (Pin) that only needs additionally to utilize time schedule controller transmits required switch-over control signal and gets final product with control shutdown commutation circuit, also be that the present invention can do existing display control system framework under the situation of significantly change design not needing, reach relevant control purpose and function; Eliminate power-off ghost shadow compared to tradition and need to set up replacement IC more, the present invention can significantly reduce material cost, and significantly fall and eliminate the required time of ghost, and utilizing gate driving IC to open all pixel transistors to discharge the method for pixel electrode electric charge in shutdown compared to tradition, it does not have the problem that is punctured by electrode because of the excessive pixel components that causes of Vgh transient voltage yet.
The above embodiment only is explanation technological thought of the present invention and characteristics, its purpose is enabling those skilled in the art to understand content of the present invention and enforcement according to this, when not being limits claim of the present invention with this, so promptly equivalent modifications or the modification of doing according to disclosed spirit still falls in the claim of the present invention.
Claims (30)
1. LCD comprises:
Time schedule controller, it detects the foreign frequency signal of described LCD, and exports switch-over control signal in view of the above;
Dc power converter, it connects described time schedule controller and provides first operating voltage to described time schedule controller; And
The shutdown commutation circuit, it connects described time schedule controller and receives described switch-over control signal and second operating voltage that described dc power converter is provided, wherein, described shutdown commutation circuit according to the information of described switch-over control signal one of them, control the output voltage of gamma voltage generator and common voltage circuit respectively, thus the pixel electrode of pixel and the voltage difference of common electrode are adjusted to zero.
2. LCD according to claim 1, wherein, described shutdown commutation circuit select the output first control voltage and the second control voltage one of them to described gamma voltage generator and described common voltage circuit, to control the output voltage of described gamma voltage generator and described common voltage circuit.
3. LCD according to claim 2, wherein, the described first control voltage is substantially equal to described second operating voltage.
4. LCD according to claim 2, wherein, the described second control voltage is 0 volt of voltage.
5. LCD according to claim 2, wherein, when described gamma voltage generator receives described first control voltage or the described second control voltage, its corresponding respectively first reference voltage or second reference voltage of producing, and described common voltage circuit receives the described first control voltage or described second control during voltage, its corresponding respectively first common voltage or second common voltage of producing.
6. LCD according to claim 5, wherein, the magnitude of voltage of described second reference voltage equals the magnitude of voltage of described second common voltage.
7. LCD according to claim 5, wherein, the magnitude of voltage of described second reference voltage and described second common voltage is 0 volt.
8. LCD according to claim 2, wherein, the described information of described switch-over control signal comprises first level voltage and second level voltage, when described switch-over control signal is positioned at described first level voltage or described second level voltage, described shutdown commutation circuit is corresponding respectively to produce described first control voltage or the described second control voltage, and described first level voltage is not equal to described second level voltage.
9. LCD according to claim 8, wherein, when described foreign frequency signal inputs to described LCD or described time schedule controller when detecting described foreign frequency signal, described time schedule controller switches described switch-over control signal to described first level voltage.
10. LCD according to claim 8, wherein, when described foreign frequency signal stopped to input to described LCD or described time schedule controller and can't detect described foreign frequency signal, described time schedule controller switched described switch-over control signal to described second level voltage.
11. LCD according to claim 8, wherein, when described foreign frequency signal stops to input to described LCD or described time schedule controller and can't detect described foreign frequency signal, after first period schedule time, the described time schedule controller beginning is switched described switch-over control signal to described second level voltage, and described second level voltage is kept second period schedule time.
12. LCD according to claim 11, wherein, after described second level voltage was kept described second period schedule time, the described dc power converter beginning stopped to provide described first operating voltage and described second operating voltage.
13. LCD according to claim 11, wherein, described first period schedule time equals to scan the time of two sweep traces.
14. LCD according to claim 11, wherein, described second period schedule time is greater than picture sweep time.
15. LCD according to claim 2, wherein, described shutdown commutation circuit is built-in to be integrated in the described dc power converter.
16. LCD according to claim 2, wherein, described foreign frequency signal packet is contained in low-voltage differential (LVDS) signal, differential (RSDS) signal of short arc or transistor-transistor logic (TTL) signal.
17. the control method of a LCD comprises the following steps:
Provide first operating voltage and second operating voltage to time schedule controller and shutdown commutation circuit respectively;
Utilize described time schedule controller to detect the foreign frequency signal of described LCD, and then export switch-over control signal to described shutdown commutation circuit; And
Make the gamma voltage generator of described LCD and common voltage circuit produce first reference voltage and first common voltage respectively or produce second reference voltage respectively and second common voltage according to described switch-over control signal, wherein the pixel electrode of pixel and the voltage difference of common electrode are adjusted to zero by described second reference voltage and described second common voltage.
18. the control method of LCD according to claim 17 wherein, by described first reference voltage and described first common voltage, writes described pixel with the pixel data signal that described LCD is received.
19. the control method of LCD according to claim 17, wherein, when described foreign frequency signal inputs to described LCD or described time schedule controller when detecting described foreign frequency signal, control described shutdown commutation circuit by described switch-over control signal, make its output first control voltage, produce described first reference voltage and described first common voltage respectively to control described gamma voltage generator and described common voltage circuit.
20. the control method of LCD according to claim 17, wherein, when described foreign frequency signal stops to input to described LCD or described time schedule controller and can't detect described foreign frequency signal, control described shutdown commutation circuit, make its output second control voltage, produce described second reference voltage and described second common voltage respectively to control described gamma voltage generator and described common voltage circuit.
21. the control method of LCD according to claim 20, wherein, the described first control voltage is substantially equal to described second operating voltage.
22. the control method of LCD according to claim 17, wherein, described second reference voltage and described second common voltage are 0 volt.
23. the control method of LCD according to claim 20, wherein, the described second control voltage equals 0 volt.
24. the control method of LCD according to claim 19, wherein, when described foreign frequency signal inputs to described LCD or described time schedule controller when detecting described foreign frequency signal, described time schedule controller switches described switch-over control signal to high level voltage.
25. the control method of LCD according to claim 20, wherein, when described foreign frequency signal stopped to input to described LCD or described time schedule controller and can't detect described foreign frequency signal, described time schedule controller switched described switch-over control signal to low level voltage.
26. the control method of LCD according to claim 20, wherein, when described foreign frequency signal stops to input to described LCD or described time schedule controller and can't detect described foreign frequency signal, after first period schedule time, the described time schedule controller beginning switches to low level voltage with described switch-over control signal, and described low level voltage is kept second period schedule time.
27. the control method of LCD according to claim 26, wherein, after described low level voltage was kept described second period schedule time, described first operating voltage and described second operating voltage beginning stopped to provide.
28. the control method of LCD according to claim 26, wherein, after described second period schedule time, and when described first operating voltage continued to provide to described time schedule controller, described time schedule controller switched to described switch-over control signal high level voltage and the pixel data signal of the selftest/free-running operation pattern of The built-in is transferred to source electrode driver.
29. the control method of LCD according to claim 28, wherein, described second period schedule time is greater than five picture sweep times.
30. the control method of LCD according to claim 28, wherein, after the pixel data signal output of described selftest/free-running operation pattern, when if described foreign frequency signal detects described foreign frequency signal again by outside input or described time schedule controller again, described time schedule controller stops to transmit the pixel data signal of described selftest/free-running operation pattern, and the pixel data signal that transmission is received by the outside is to described source electrode driver.
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