CN1794322A - Image display device and display drive method - Google Patents
Image display device and display drive method Download PDFInfo
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Abstract
A potential of a data signal line (S) during a non-scanning period is charged to a substantially intermediate potential of a data signal at a corresponding frame, wherein the data signal line is in a floating state because the output of a data signal line driving circuit (SD) is changed into high impedance by a charging circuit. Thus, extremely large dispersion does not occur in a potential of each pixel capacitor with respect to a potential of the data signal line (S), so that it is possible to restrict dispersion of a leak current flowing via an active element of each pixel. Thus, potential variation of a pixel (PIX) is reduced, so that it is possible to improve display quality during a non-scanning period. That is, in an active-matrix-type liquid crystal display, when a frame frequency is reduced by setting the non-scanning period to be sufficiently larger than a scanning period while a standby image is being displayed so as to realize low power consumption, the display quality is improved.
Description
The application be the applicant on September 25th, 2002 submit to, application number for " 02151490.9 ", denomination of invention divides an application for the application for a patent for invention of " image display apparatus and display drive method ".
Technical field
The present invention relates to be suitable as most enforcement such as liquid crystal indicator and be included in each zone of being divided by cross one another a plurality of scan signal lines and data signal line go up electrooptic element of forming and with its active component that forms in pairs and the active matric image display apparatus and the driving method thereof of pixel capacitance.Particularly relate to the long enough of when standby picture, non-scan period being set with respect to scan period, thereby realize the image display apparatus and the display drive method of low frame rate and low-power consumption.
Background technology
Fig. 8 is the image display apparatus of the typical prior art of expression active matric, is the block scheme that expression constitutes the electrical structure of liquid crystal indicator 1.This liquid crystal indicator 1 roughly comprises display part 2, scan signal line drive circuit gd, data signal wire driving circuit sd, control signal generation circuit ct1.Such as mentioned above, display part 2 is by cross one another a plurality of scan signal line g1, g2 ... gm is (when following general name, to represent with reference symbol g) and data signal line s1, s2 ... sn (when general name, below representing with reference symbol s) is divided into each rectangular zone and goes up configuration pixel PIX.
As shown in Figure 9, above-mentioned each pixel PIX comprises active component SW and pixel capacitance Cp.When the selected scanning of said scanning signals line g, active component SW is taken into the picture intelligence DAT of data signal line s among the above-mentioned visual capacitor C p, also keeps this picture intelligence DAT to proceed to show during non-selection.Above-mentioned pixel capacitance Cp is made of liquid crystal capacitance CL and auxiliary capacitor Cs.
Above-mentioned data signal wire driving circuit Sd is made of shift register 3 and sample circuit 4.The effect of above-mentioned data signal wire driving circuit sd is, make shift register 3 with synchronous from the clock signal of clock signal C KS, its reverse signal CKSB of above-mentioned control signal generation circuit ct1 and data scanning start signal SPS etc., the picture intelligence DAT that inputs to the analog switch of sample circuit 4 is sampled, be written in each data signal line s as required.
Said scanning signals line drive circuit gd is made of shift register 5, with synchronous from the clock signal of the clock signal C KG of above-mentioned control signal generation circuit ct1, scanning start signal SPG etc., select each scan signal line g of scanning successively, be controlled at the ON/OFF of the active component SW in the pixel PIX.When active component SW is ON, write the picture intelligence DAT of each data signal line s, write each pixel PIX as described above, kept by the visual capacitor C p in each pixel PIX.By repeating above action, can be on display part 2 displayed image.
Figure 10 is the oscillogram of the drive waveform examples used of the above-mentioned write activity of expression.Drive in the example at this, adopt the driving method of horizontal line inversion mode.Import and clock signal C KS, CKSB and the synchronous input image signal DAT of data scanning start signal SPS to data signal wire driving circuit Sd from above-mentioned control generation circuit ct1.Respond above-mentioned clock signal C KS, CKSB and data scanning start signal SPS, successively to odd number scan signal line gi (g1, g3 ...) and even-line interlace signal wire gj+1 (g2, g4 ...) the output strobe pulse, and above-mentioned picture signal DAT write each data signal line si (s1, s2 successively ...) pixel in.In this embodiment, the picture intelligence of positive polarity is write odd number scan signal line gi (g1, g3 ...) pixel in, and even-line interlace signal wire gj+1 (g2, g4 ...) pixel in write the picture intelligence of negative polarity.
; in recent years; requirement to the low consumption electric power of image display apparatus is strong; as one of them countermeasure; consideration shows the occasion of the dynamic image that still image and refresh rate are low on standby picture; by non-scan period being set longer fully, thereby realize the frame frequency driving method of low consumption electric power than scan period.Use the low frame rate driving method, can frame resemble and image is write among the pixel PIX above-mentioned, make number stop scanning (2～8) image durations, set non-scan period longer fully than scan period.The action that utilizes this low frame rate to drive the data signal wire driving circuit sd of method is shown among Figure 11.
In scan period, said scanning signals line g1, g2 ... on, derive strobe pulse in order.Corresponding, in order to adopt the driving method of above-mentioned horizontal line reversible type, picture intelligence DAT from each horizontal scan period reversal of poles of above-mentioned control signal generation circuit ct1 input, to data signal line si arbitrarily, by the level of the corresponding i data signal line si of above-mentioned sample circuit 4 outputs.To each pixel PIX1, PIX2 ..., write the level of the above-mentioned data signal line si on edge behind the above-mentioned strobe pulse, keep in the whole non-scan period more than an above-mentioned image duration later on.
At this, as shown in Figure 12, when being conceived to pixel PIX1, the PIX2 corresponding with the above-mentioned si of data signal line arbitrarily and scan signal line g1, g2, carrying out the occasion that above-mentioned low frame rate drives, the electric charge that is kept in scan period by the above-mentioned visual capacitor C p of pixel PIX1, PIX2 after finishing scan period utilizes among above-mentioned active component SW and the data signal line si and separates., in fact between source electrode one drain electrode of above-mentioned active component SW, be applied with voltage VDS.And the capacity ratio pixel capacitance Cp of data signal line si is much bigger.
Therefore, after scan period finishes, when scan signal line si is in the current potential in its end of scan moment, voltage VDS is that the difference of current potential of the current potential of pixel capacitance Cp and data signal line si is big more between above-mentioned source drain, easy more generation leakage current, and the electric charge that remains among the pixel capacitance Cp is flowed out.About this point, the above-mentioned auxiliary capacitor Cs of employing increase etc. are to reduce the influence of above-mentioned leakage current to showing as far as possible.
Yet, as mentioned above, above-mentioned leakage current changes along with voltage VDS between source drain, and usually keeps the quantity of electric charge (current potential) that has nothing in common with each other by the response displayed image on each pixel PIX, so voltage VDS is different for each pixel PIX between above-mentioned source drain.Therefore the leakage current of each pixel PIX is different, so might damage display quality.
Particularly in liquid crystal indicator, because necessary AC driving so utilize for example above-mentioned horizontal line inversion driving mode, keeps the mutually different electric charge of polarity of positive polarity and negative polarity in neighbouring pixel.Therefore as shown in Figure 13, after finishing above-mentioned scan period, transfer to the moment of non-scan period, at the charged current potential of data signal line si during for negative polarity for example, for the pixel PIX2 of maintenance negative polarity electric charge, voltage VDS2 diminishes between above-mentioned source-drain electrode, and leakage current also diminishes.In contrast, on the pixel PIX1 that keeps the positive polarity electric charge, voltage VDS1 becomes big between above-mentioned source drain, and leakage current also becomes greatly, exists the problem in the pixel display density reduction (normally white occasion) of this positive polarity electric charge of non-scan period.
Summary of the invention
Even the object of the present invention is to provide a kind of under situations such as standby picture, reduce frame frequency, realization low-power consumption, also can make the image display apparatus and the display drive method of the display quality raising of non-scan period.
Image display apparatus of the present invention is characterised in that: be included in each zone of being divided by cross one another a plurality of scan signal lines and data signal line go up electrooptic element of forming and with its active component and pixel capacitance that forms in pairs, according to during the said scanning signals line sweep, being taken into electric charge in the above-mentioned pixel capacitance by above-mentioned active component, make the electrooptic element display driver, in image display apparatus, also comprise:, make above-mentioned data signal line be charged to the charging unit of the roughly intermediate potential of the data-signal in this frame in said scanning signals line non-scan period.
According to above-mentioned formation, the intersection point of cross one another a plurality of scan signal line and data signal line is provided with the source element, in the scan period of scan signal line, this active component is taken into data-signal in the pixel capacitance, electric charge according to this data-signal that is taken into, electrooptic element is carried out display driver, also can keep demonstration in the non-scan period of scan signal line whereby, in the display device of such active matric, in above-mentioned non-scan period, make from the output of data signal wire driving circuit to become the current potential that is in the data signal line of quick condition for high impedance, be charged to the roughly intermediate potential of this frame at the above-mentioned data-signal of scan period by charging unit.After charging finished, at least before next scan period begins, above-mentioned charging part became and is high impedance, and above-mentioned data signal line becomes and is quick condition.
Therefore, when the current potential of the data signal line of non-scan period places the maximum potential minimum level of the above-mentioned data-signal of above-mentioned scan period for example, the current potential of each pixel capacitance is at the possibility that may produce very big deviation between the current potential of the current potential of this data signal line and each pixel capacitance, transfer to the roughly intermediate potential of data-signal, whereby can be do not produce very large difference on the current potential of each relative pixel capacitance, thereby can suppress from the deviation of the leakage current of active component at the current potential of relative data signal wire.Therefore on standby picture etc., non-scan period set sufficiently longlyer and frame rate is reduced, and produce the low consumption electric power and the potential change of pixel is reduced, thereby improve display quality in above-mentioned non-scan period than scan period.
Image display apparatus of the present invention is characterised in that: be included in that electrooptic element of forming is gone up in each zone of being divided by cross one another a plurality of scan signal lines and data signal line and at its active component and electric capacity that forms in pairs, it utilizes during the said scanning signals line sweep by above-mentioned active component and is taken into electric charge in the above-mentioned pixel capacitance, electrooptic element is carried out display driver, in this image display apparatus, also comprise: at the potential change parts of the potential change of the above-mentioned data signal line of non-chien shih sweep time of said scanning signals line.
According to above-mentioned formation, the intersection point of cross one another a plurality of scan signal line and data signal line is provided with the source element, the scan period of sweep signal this active component data-signal is taken in the pixel capacitance, electric charge by this data-signal that is taken into carries out display driver to electrooptic element, also can keep demonstration in the non-scan period of scan signal line whereby, in the display device of this active matric, in above-mentioned non-scan period, by potential change portion.Make from the output high impedance of data-signal drive wire circuit to become current potential for the data signal line of quick condition, at least before next time, scan period began, above-mentioned potential change portion becomes and is high impedance, and data signal line becomes quick condition.
Therefore, for example at the current potential of establishing data signal line for fixedly the time, at the possibility that between the current potential of the current potential of this data signal line and each pixel capacitance, has very large difference, current potential by each pixel capacitance, make the potential change of data signal line, scan near being preferably in intermediate potential, like this, very large difference can not take place, thereby can suppress the difference by the leakage current of active component on the current potential of each pixel capacitance relative with the current potential of data signal line.Therefore on standby picture etc., set non-scan period longlyer fully, can reduce frame rate like this, and the change of minimizing pixel current potential under the situation of low consumption electric power, thereby can improve display quality in above-mentioned non-scan period than scan period.
Other purpose of the present invention, feature and advantage can become clearer by following record.Advantage of the present invention will become more clear by following with reference to the description of the drawings.
Description of drawings
Fig. 1 is the electrical structure block scheme of expression as liquid crystal indicator in the image display apparatus of one embodiment of the present invention;
Fig. 2 is the oscillogram of an example of the drive waveforms of the above-mentioned liquid crystal indicator of expression;
Fig. 3 is the oscillogram of another example of the drive waveforms of the above-mentioned liquid crystal indicator of expression;
Fig. 4 is the block scheme of expression as the electrical structure of liquid crystal indicator in the image display apparatus of another embodiment of the present invention;
Fig. 5 is the block scheme of expression as the electrical structure of liquid crystal indicator in the image display apparatus of the another embodiment of the present invention;
Fig. 6 is the figure of output of the charging potential of concrete expression control signal generation circuit shown in Figure 5;
Fig. 7 is the block scheme of expression as liquid crystal indicator electrical structure in the image display apparatus of another embodiment of the present invention;
Fig. 8 is the block scheme of expression as the electrical structure of the liquid crystal indicator of the image display apparatus of active matric typical prior art;
Fig. 9 is the equivalent circuit diagram of each pixel of above-mentioned liquid crystal indicator;
Figure 10 is the oscillogram of an example of drive waveforms that expression is used for the write activity of the liquid crystal indicator shown in Fig. 8;
Figure 11 is the oscillogram of an example of drive waveforms of the liquid crystal indicator of prior art shown in the presentation graphs 8;
Figure 12 is the figure that is used to stress pixel;
Figure 13 is the oscillogram that is used to describe in detail the action of Figure 11.
Embodiment
One embodiment of the present of invention are described below with reference to the accompanying drawings.
Fig. 1 is the block scheme of expression as the electrical structure of the image display apparatus liquid crystal indicator 11 of one embodiment of the invention.This liquid crystal indicator 11 is active matrix type LCD devices, roughly comprises display part 12, scan signal line drive circuit GD, data signal wire driving circuit SD, charging circuit 10 and control signal generation circuit CTL.Above-mentioned data signal wire driving circuit SD is made of shift register 13 and sample circuit 14, and scan signal line drive circuit GD is made of shift register 15.Data signal wire driving circuit SD and scan signal line drive circuit GD are because have same structure with the data signal wire driving circuit sd and the scan signal line drive circuit gd of above-mentioned liquid crystal indicator 1 respectively, so omit its explanation at this.
Control signal generation circuit CTL also exports same signal CKS, CKSB, SPS, DAT, CKG, the SPG etc. with above-mentioned control signal generation circuit ct1, also exports control signal PCC, PCCB (reverse signal of PCC) and the charging potential PCV described later that is used for above-mentioned charging circuit 10 simultaneously.Each pixel PIX and above-mentioned pixel PIX shown in Figure 6 have same spline structure.
Above-mentioned charging circuit 10 is provided with analog switch ASW1～ASWn that the pair of switches element by P type and N type constitutes for the charging potential PCV that can export positive and negative polarities one by one by each data signal line, by common input above-mentioned control signal PCC, PCCB on these analog switches ASW1～ASWn, make above-mentioned charging potential PCV export to above-mentioned each data signal line S.
Fig. 2 is the oscillogram of the drive waveform examples of the above-mentioned such liquid crystal indicator that constitutes 11 of expression.Drive in the example at this, adopt the driving method of horizontal line inversion mode.In scan period, said scanning signals G1, G2 ... on derive strobe pulse successively.Corresponding, in order to realize the driving method of above-mentioned horizontal line inversion mode, and, export the level of corresponding i number data signal line Si to arbitrary data signal wire Si by above-mentioned sample circuit 14 at the picture intelligence DAT of each horizontal scan period from above-mentioned control signal generation circuit CTL input reversal of poles.The level of this data signal line Si writes by active component SW among the pixel capacitance Cp of each pixel PIX, and the point of the constant maintenance of whole non-scan period more than above-mentioned whole 1 image duration is same as the prior art later on.
Should notice being that according to the present invention, above-mentioned control signal generation circuit CTL changes control signal PCC, PCCB, makes the current potential of data signal line S be charged to charging potential PCV by charging circuit 10 when becoming non-scan period.
The charging potential PCV of this non-scan period is set in the current potential of data signal line S that constitutes the scan period of 1 frame with this non-scan period, promptly on the roughly intermediate potential of data-signal.According to above-mentioned horizontal line inversion mode, because on the pixel of corresponding each the scan signal line G of positive polarity current potential and the alternative supply of negative polarity current potential, so becoming, the charging potential PCV of above-mentioned non-scan period is the maximal value of positive polarity current potential and the peaked intermediate value of negative polarity current potential, i.e. the current potential VCOM of opposite electrode.In addition,, also not necessarily become above-mentioned intermediate value exactly, so in present specification, establish this value and be intermediate value roughly because the stray capacitance of the analog switch of the sample circuit 14 of active component SW and data signal wire driving circuit SD etc. are different.
Like this, according to the present invention, in non-scan period, make output from data signal wire driving circuit SD become current potential by charging circuit 10, and in the scan period of this frame, be charged to the roughly intermediate potential of above-mentioned data-signal for the data signal line S that becomes quick condition behind the high impedance.Then at least before next scan period begins, charging circuit 10 becomes behind the high impedance and makes data signal line S return to quick condition.Therefore liquid crystal indicator 11 not can with the current potential of corresponding each the pixel capacitance Cp of the current potential of data signal line S on very large deviation takes place, so can suppress deviation by the leakage current of active component SW.Therefore on standby picture by non-scan period being set longer fully than scan period, frame rate is reduced, and under the situation of reduction consumption of electric power the potential change of minimizing pixel PIX, thereby can improve the display quality of above-mentioned non-scan period.
In addition, as shown in Figure 2, above-mentioned control circuit CTL is in each horizontal cycle, before scan signal line G output strobe pulse, above-mentioned control signal PCC, PCCB are changed, make the current potential of data signal line S be pre-charged to charging potential PCV by charging circuit 10.The charging potential PCV of this scan period, when the current potential of positive polarity being supplied with to pixel that should scan signal line G is the predetermined current potential of positive polarity, when supplying with the negative polarity current potential is the predetermined current potential of negative polarity, for example is chosen as in the maximal value of each polarity and the intermediate value of minimum value.
Thereby, owing to need to write the current potential of former data signal line S of the picture intelligence DAT of previous row, before the scanning of next line, be pre-charged to the predetermined potential of polarity of the picture intelligence DAT of its next line, so data signal wire driving circuit SD can be easy to write the current potential of desirable picture intelligence DAT, thereby the current capacity of this data signal wire driving circuit SD is reduced.
Like this, charging circuit 10 of the present invention can be by realizing the circuit of the enterprising line precharge of data signal line S, so pre-charge circuit that can public prior art.In this case, can not cause the increase of structure, only need to reappraise the order of control signal generation circuit CTL.In addition, though can consider to utilize data signal wire driving circuit SD to realize the present invention, but data signal wire driving circuit SD has the labyrinth that picture intelligence DAT is sampled, and above-mentioned charging circuit 10 is compared with this labyrinth and is had simpler structure, so with the situation of data signal wire driving circuit SD with, can reduce electric power consumption.
In addition, in liquid crystal indicator 11 of the present invention, data signal wire driving circuit SD, scan signal line drive circuit GD and active component SW are made of polycrystalline SiTFT, and they are formed on the same substrate.Because polysilicon membrane is compared easy increase area with monocrystalline silicon thin film, thus foregoing circuit and element formed with polycrystalline SiTFT, and make them on same substrate, form monolithic integrated circuit, can increase area whereby.
In addition, in liquid crystal indicator 11 of the present invention, above-mentioned data signal wire driving circuit SD, scan signal line drive circuit GD and each pixel circuit are included in the active component that the technological temperature below 600 ℃ is made down.Like this when being set in the technological temperature of active component below 600 ℃, even use the substrate of common glass substrate (strain point is the glass plate below 600 ℃) as each active component, the bending that causes because of the above technology of strain point can not take place yet and scratched, be more prone to so install, and can large tracts of landization.
In addition, of the present invention non-scan period to carrying out once like that the charging of data signal line S is not limited to that control signal PCC with Fig. 2 represents, also can carry out repeatedly.And also can almost, carry out continuously as shown in the control signal PCC of Fig. 3 in whole non-scan period.Duration of charging is long more, and above-mentioned display quality is stable more.And when becoming non-scan period, the mode effect that begins to charge from fast as far as possible timing is more obvious.
And with a some inversion mode is that the perpendicular line inversion mode is also identical with above-mentioned horizontal line inversion mode, owing to be charged to roughly intermediate potential at the data-signal of scan period of this frame, so applicable the present invention.And use the frame inversion mode, because when becoming non-scan period, be charged to the maximal value of the data-signal in scan period of this frame and the intermediate potential of minimum value, so can be suitable for the present invention.But above-mentioned horizontal line inversion mode and the some inversion mode in, the data of the data of positive polarity and negative polarity are mixed equably in a frame, so if the timing range of picture intelligence DAT changes, then above-mentioned charging potential PCV becomes on entire frame about equally, can on this charging potential PCV, use the current potential VCOM of above-mentioned opposite electrode, make than being easier to like this.In contrast, in the frame inversion mode, because total pixel PIX is charged as identical polar in the frame, thus the polarity of above-mentioned charging potential PCV, the roughly intermediate potential that is changed to positive polarity on every frame and the roughly intermediate potential of negative polarity.
In addition, even control signal generation circuit CTL constitutes the structure of the charging potential PCV variation that can make in above-mentioned non-scan period, also can obtain same effect.Promptly as described above, when making charging potential PCV be fixed on any current potential, when not becoming the roughly intermediate potential of the maximal value of the data-signal during this frame scan and minimum value, may between the charging potential PCV of the current potential of each pixel PIX and data signal line S very large difference take place.In contrast, if the charging potential PCV that makes in non-scan period is with change quiveringly between the maximal value of the data-signal during this frame scan and minimum value, vibrate near being preferably in intermediate potential, just not can with the current potential of corresponding each the pixel PIX of the current potential of data signal line S on very large difference takes place, can suppress to pass through the difference of the leakage current of active component SW like this.
Below with reference to Fig. 4 another embodiment of the present invention is described.
Fig. 4 is the electric block diagram of expression as liquid crystal indicator 21 in the image display apparatus of another embodiment of the present invention.This liquid crystal indicator 21 and above-mentioned liquid crystal indicator 11 are similar, attached identical reference symbol on the part of correspondence, and omit its explanation.
It should be noted that this liquid crystal indicator 21 shared two-value data signal-line driving circuit BD are as charging part.That is to say that above-mentioned data signal wire driving circuit SD is to the picture intelligence DAT of data signal line S output multi-grey level, and two-value data signal-line driving circuit BD is to the picture intelligence RGB of two gray levels of data signal line S output.This liquid crystal indicator 21 is used on the display device that resembles portable phone etc., demanding in use display performance, and when standby, carry out necessary MIN demonstration with lower display performance.
Above-mentioned two-value data signal-line driving circuit BD roughly comprises the structure of shift register 22, latch cicuit 23, selector switch 24.Above-mentioned shift register 22 is identical with the shift register 3,13 of above-mentioned data signal wire driving circuit Sd, SD, by the trigger of plural serial stage constitute when clock signal CKS, CKSB and data scanning start signal SPS when control signal generation circuit CTLa imports, become behind the above-mentioned data scanning start signal SPS from output between above-mentioned each trigger adjacent each other and to be latch pulse, latch cicuit 23 these pulses of response are latched successively from the binary image signal RGB of the demonstration usefulness of control signal generation circuit CTLa input.Selector switch 24 responses are from the control signal TRF of above-mentioned control signal generation circuit CTLa input, select to export to each data signal line S according to above-mentioned picture intelligence RGB from the liquid crystal applied voltages VB of above-mentioned control signal generation circuit CTLa input and the some voltage the VW.By correspondingly selecting scanning said scanning signals line G therewith, can carry out the driving of two gray levels.
In above-mentioned such two-value data signal-line driving circuit BD that constitutes, above-mentioned control signal PCC is inputed to selector switch 24, and respond this input, by a liquid crystal applied voltages, for example the VW under normal white liquid crystal occasion exports to each data signal line S, can realize the action same with above-mentioned charging circuit 10.Therefore special circuit need not be set as above-mentioned current potential holding device, just can be in the present invention the two-value data signal-line driving circuit BD dual-purpose of having realized the low consumption electric power.
In addition, because in the above-mentioned control signal TRF of change order, by reset signal being inputed to latch cicuit 23,, also can realize same action even just can above-mentioned control signal PCC.Promptly when latch cicuit 23 resets, select an above-mentioned liquid crystal applied voltages VW, when becoming above-mentioned precharge timing and non-scan period, also can be all scan signal line G, as non-selection scanning mode, get final product from selector switch 24 this liquid crystal applied voltages of output VW by above-mentioned control signal TRT.
Below with reference to Fig. 5 and Fig. 6 another embodiment of the present invention is described.
Fig. 5 is the block scheme of expression as the electrical structure of liquid crystal indicator 31 in the image display apparatus of the another embodiment of the present invention.This liquid crystal indicator 31 is similar with above-mentioned liquid crystal indicator 11, and corresponding part is given identical reference symbol, and omits its explanation.
It should be noted, according to this liquid crystal indicator 31, control signal generation circuit CTLb is when becoming non-scan period, control signal PCC, PCCB are changed, make the current potential of data signal line S be charged to charging potential PCV by charging circuit 10, make simultaneously from this control signal generation circuit CTLb and also be charged to above-mentioned charging potential PCV to the signal wire 32 of sample circuit 14 output image signal DAT.
Fig. 6 is the diagrammatic sketch of the output of the above-mentioned charging potential PCV of concrete expression in above-mentioned control signal generation circuit CTLb.This control signal take place electricity slightly CTLb comprise the structure of the timing generator 33 formed by digital circuit, simulated block 34, analog switch SWV1, SWV2, SWP1, SWP2.
Above-mentioned timing generator 33 is corresponding with the picture intelligence from the outside, generates above-mentioned signal CKS, CKSB, SPS, CKG, SPG, PWC, also generates above-mentioned control signal PCC, PCCB simultaneously.Corresponding, above-mentioned simulated block 34 generates picture intelligence VDAT and charging voltage VPCV, generates the electric VCOM of above-mentioned opposite electrode simultaneously.
, according to above-mentioned control signal generation circuit CTLb, the current potential VCOM of above-mentioned opposite electrode only directly exports to opposed electrode, and above-mentioned picture intelligence VDAT and charging potential VPCV are respectively by analog switch SWV1, SWP1 output.Analog switch SWV2, SWP2 these two analog switch SWV1, SWP1 relatively form in pairs, and output simultaneously after interconnecting, and analog switch SWV1, SWP1 and analog switch SWV2, SWP2 carry out the control of opposite action ground by above-mentioned timing generator 33.The current potential VCOM of the above-mentioned opposite electrode of common input on above-mentioned analog switch XWV2, SWP2.
Above-mentioned timing generator 33 response above-mentioned control signal PCC, PCCB, scan period by making analog switch SWV1, SWP1 near (on), make analog switch SWV2, SWP2 disconnect (off), export above-mentioned picture intelligence VDAT and charging potential VPCV respectively, as above-mentioned picture signal DAT and charging potential PCV, in non-scan period, by making analog switch SWV2, SWP2 conducting, analog switch SWV1, SWP1 are disconnected, the current potential VCOM of above-mentioned opposite electrode is exported jointly.
Refer again to Fig. 5, this Fig. 5 has specifically represented sample circuit 14, and phase inverter INV1～INVn and the analog switch VSW1～VSWn of corresponding each data signal line S1-Sn constitute respectively thereby this sample circuit 14 is by the triggers at different levels of corresponding above-mentioned shift register 13 respectively.Analog switch VSW1～VSWn is identical with the analog switch ASW1～ASWn of above-mentioned charging circuit 10, for the picture intelligence DAT that can export positive and negative polarities and above-mentioned charging circuit PCV and be made of the on-off element of a pair of P type and N type.Therefore, above-mentioned phase inverter INV1～INVn is set, from the sampled signal SR1～SRn of above-mentioned triggers at different levels directly or by after this phase inverter INV1～INVn counter-rotating, supply with the pair of switches element of each analog switch VSW1～VSWn respectively.
In above-mentioned scan period, above-mentioned data scanning start signal SPS responds above-mentioned simulating signal CKS, CKSB, exports successively from above-mentioned trigger at different levels, as sampled signal SR1～SRn2.Therefore, make above-mentioned each analog switch VSW1～VSWn successively, above-mentioned picture intelligence DAT is exported to data signal line S, and be taken among the pixel capacitance Cp of each pixel PIX near (on).
In addition, in non-scan period, above-mentioned each analog switch VSW1～VSWn disconnects (off), such as mentioned above, make the signal wire 32 of picture intelligence DAT be charged to above-mentioned charging potential PCV (the current potential VCOM of opposite electrode) with data signal line S, therefore make between source drain voltage VDS about equally, thereby can suppress the generation of leakage current among this analog switch VSW1～VSWn.Therefore, between the current potential of the current potential of data signal line S of above-mentioned roughly intermediate potential and each pixel capacitance Cp potential difference (PD) is arranged even be at charging potential PCV, leakage current that also can suppress to cause and that supply with by this analog switch VSW1～VSWn by this difference, and can further reduce the potential change of pixel PIX, further improve the display quality of above-mentioned non-scan period.
In addition, in the above description, though so that chien shih analog switch VSW1～VSWn disconnection (off) is the example explanation in non-sweep time, if but the current potential of the signal wire 32 of picture intelligence DAT equates with the current potential of data signal line S, then because the electric current by this analog switch VSW1～VSWn is 0, institute so that its connection (ON) also have no relations.
Below with reference to Fig. 7 another embodiment of the present invention is described.
Fig. 7 is the block scheme of expression as the electrical structure of liquid crystal indicator 41 in the image display apparatus of another embodiment of the present invention.This liquid crystal indicator 41 and above-mentioned liquid crystal indicator 21,31 are similar, and the part of all correspondences is given identical reference symbol, and omits its explanation.According to this liquid crystal indicator 41, in above-mentioned liquid crystal indicator 21 shown in Figure 4, used the control signal generation circuit CTLc identical with the control signal generation circuit CTLb shown in above-mentioned Fig. 6.
This Fig. 7 has specifically illustrated selector switch 24, thus this selector switch 24 by respectively with the triggers at different levels of above-mentioned shift register 22 respectively with each data signal line S1～Sn corresponding by a pair of analog switch ASWB1～ASWBn and ASWW1～ASWWn and those analog switches ASWB1～ASWBn, and phase inverter INVB1～INVBn of using of ASWW1～ASWWn and INVW1～INVWn and OR circuit OR1～ORn constitute.Analog switch ASWB1～ASWBn, ASWW1～ASWWn are identical with above-mentioned ASW1～ASWn, VSW1～VSWn, are made of the on-off element of a pair of P type and N type.
Above-mentioned analog switch ASWB1～ASWBn and the phase inverter INVB1～INVBn corresponding with it are last and be provided with for above-mentioned liquid crystal applied voltages VB being applied to data signal line S1～Sn, and above-mentioned analog switch ASWW1～ASWWn and the phase inverter INVW1～INVWn corresponding with it are for the voltage VW that applies on the above-mentioned liquid crystal being applied to the last and setting of data signal line S1～Sn.And, according to above-mentioned control signal TRF and picture intelligence RGB, it is effective (high level) that a certain side among the selection signal SELB1～SELBn that is made of not shown logical circuit and the selection signal SELW1～SELWn is become, therefore, as mentioned above, by above-mentioned analog switch ASWB1～ASWBn or analog switch ASWW1～ASWWn the either party of liquid crystal applied voltages VB and liquid crystal applied voltages VW is exported to data signal line S1～Sn.
In addition, the above-mentioned control signal PCC of selector switch 24 responses among Fig. 7 exports the liquid crystal applied voltages VW among above-mentioned liquid crystal applied voltages VB, the VW.Therefore above-mentioned selection signal SELW1～SELWn inputs to above-mentioned analog switch ASWW1～ASWWn and phase inverter INVW1～INVWn as selecting signal SELW ' 1～SELW ' n by each OR circuit OR1～ORn.Simultaneously above-mentioned control signal PCC is supplied with above-mentioned each OR circuit OR1～ORn, therefore when some among above-mentioned selection signal SELW1～SELWn and the control signal PCC becomes effective (high level), this selection signal SELW ' 1～SELW ' n also becomes effectively (high level), and liquid crystal applied voltages VW is applied on the data signal line S.
In addition, when control signal generation circuit CTLc is made as control signal PCC effectively (high level) in non-scan period, liquid crystal applied voltages VW is applied on the signal wire 32 of above-mentioned picture intelligence DAT, also makes liquid crystal applied voltages VB as liquid crystal applied voltages VW simultaneously.At this moment liquid crystal applied voltages VW is the current potential VCOM of above-mentioned opposite electrode.
Therefore in the time of also can being suppressed at above-mentioned control signal PCC and becoming effectively (high level) by shutoff (OFF)) the leakage current of analog switch ASWB1～ASWBn.
In addition, though be that the potential change that is conceived to data signal line S illustrates in the above description, but because possess the pixel of Presentation Function, separate with data signal line S by active component SW, so can realize the function of prior art in the same old way, and can not cause any unusually on showing, this is conspicuous.
The invention is not restricted to liquid crystal indicator, also can preferably on the image display apparatus of other active matric, implement.
Image display apparatus of the present invention is characterised in that: be included in electrooptic element that each zone of being divided by cross one another multi-strip scanning signal wire and data signal line forms and with its active component and pixel capacitance that forms in pairs, its is according to be taken into electric charge in the above-mentioned pixel capacitance by above-mentioned active component during the said scanning signals line sweep, electrooptic element is carried out display driver, in image display apparatus, also comprise:, make above-mentioned data signal line be charged to the charging part of the roughly intermediate potential of the data-signal in this frame in said scanning signals non-sweep time.
According to above-mentioned formation, the intersection point of cross one another a plurality of scan signal line and data signal line is provided with the source element, in the scan period of scan signal line, this active component is taken into data-signal in the pixel capacitance, electric charge according to this data-signal that is taken into, electrooptic element is carried out display driver, also can keep demonstration in the non-scan period of scan signal line whereby, in such active matric image display device, in above-mentioned non-scan period, make from the output of data-signal driving circuit to become to high impedance and then become the current potential of the data signal line of quick condition, be charged to the roughly intermediate potential of this frame at the above-mentioned data-signal of scan period by charging part.After charging finished, at least before next scan period begins, above-mentioned charging part became and is high impedance status, and above-mentioned data signal line becomes and is quick condition.
Therefore, when the current potential with the data signal line of non-scan period is in the maximum potential of the above-mentioned data-signal of above-mentioned scan period for example or minimum level, because the electric potential relation of each pixel capacitance, between the current potential of the current potential of this data signal line and each pixel capacitance, may produce very big deviation, and different be with above-mentioned, by being the roughly intermediate potential of data-signal, thereby can not make the current potential of each pixel capacitance relative produce very large deviation, can suppress the difference of the leakage current of active component thus with the current potential of data signal line.Therefore on standby picture etc., non-scan period set sufficiently longlyer and frame frequency is reduced, and the potential change of pixel is reduced, and then can improve display quality in above-mentioned non-scan period than scan period.
In addition, image display apparatus of the present invention is characterised in that: the image signal source of picture intelligence being supplied with above-mentioned data signal wire driving circuit, output is to the charging potential of above-mentioned charging part, also is charged to above-mentioned roughly intermediate potential at the image signal line of the driving circuit of the above-mentioned data signal line of non-chien shih sweep time of said scanning signals line.
According to above-mentioned formation, the charging part that is charged to the roughly intermediate potential of this data-signal during this frame scan by the current potential at the above-mentioned data signal line of non-chien shih sweep time of said scanning signals line is supplied with signal the charging potential of above-mentioned roughly intermediate potential from the image signal source of supplying with picture intelligence, this image signal source makes the image signal line of the driving circuit of data signal line also be charged to above-mentioned roughly intermediate potential in the non-scan period of said scanning signals line.
Therefore, in the driving circuit of data signal line, even on the active component of data signal line outputting data signals, have leakage current, because of the current potential of data signal line and the current potential of image signal line, equal above-mentioned roughly intermediate potential, thereby can suppress the generation of leakage current.Therefore even have potential difference (PD) between the current potential as the current potential of the data signal line of above-mentioned roughly intermediate potential and each pixel capacitance, also can suppress the generation of the leakage current that causes by this potential difference (PD), thereby further reduce the change of pixel current potential, the display quality of above-mentioned non-scan period is improved.
In addition, image display apparatus of the present invention is characterised in that: the driving circuit of above-mentioned data signal line carries out line inversion driving or some inversion driving, and above-mentioned roughly intermediate potential is the current potential of opposite electrode.
According to above-mentioned formation, when carrying out above-mentioned AC driving in order to prevent rotten grade of liquid crystal, by the frame inversion driving whole pixels are become and be identical polar, though becoming, above-mentioned roughly intermediate potential is current potential arbitrarily, but because pass through line inversion driving or some inversion driving, make the polarity of adjacent line or adjacent point become mutually opposite polarity, above-mentioned intermediate potential becomes the current potential for opposite electrode.
Therefore by above-mentioned line inversion driving or some inversion driving, the current potential of using opposite electrode can generate this roughly intermediate potential easily as above-mentioned roughly intermediate potential.
Image display apparatus of the present invention is characterised in that: be included in by electrooptic element that forms on the zone of cross one another multi-strip scanning signal wire and data signal line division and active component and the pixel capacitance that forms in pairs in the above, utilization is taken into electric charge in the above-mentioned pixel capacitance by above-mentioned active component during the said scanning signals line sweep, electrooptic element is carried out display driver, in this image display apparatus, also comprise: in the potential change portion of the potential change of the above-mentioned data signal line of non-chien shih sweep time of said scanning signals line.
According to above-mentioned formation, the intersection point of cross one another multi-strip scanning signal wire and data signal line is provided with the source element, the scan period of sweep signal this active component data-signal is taken in the pixel capacitance, electric charge by this data-signal that is taken into carries out electrooptic element, display driver, also can keep demonstration in the non-scan period of scan signal line whereby, in the display device of such active matric, in above-mentioned non-scan period, by potential change portion, make from the output of data signal wire driving circuit to become to high impedance and then become the current potential of the data signal line of quick condition.At least before scan period beginning next time, above-mentioned potential change portion is become immediately be high impedance, and make data signal line become quick condition immediately.
Therefore, for example at the current potential of tentation data signal wire for fixedly the time, current potential by each pixel capacitance, at the possibility that between the current potential of the current potential of this data signal line and each pixel capacitance, has very large difference, make the potential change of data signal line, be preferably near the scanning of intermediate potential, whereby, with the current potential of corresponding each pixel capacitance of current potential of data signal line on very large difference can not take place, thereby can suppress difference by the leakage current of active component.Therefore on standby picture etc., set non-scan period longlyer fully, thereby reduce frame rate than scan period, the change of minimizing pixel current potential promptly and under the situation of reduction consumption of electric power, and then improve the display quality of above-mentioned non-scan period.
Concrete embodiment that constitutes in detailed description of the present invention or embodiment make the content of invention become clearer, content of the present invention is not limited to such object lesson, should do not explained by narrow sense ground, in the scope of design of the present invention and claims record, can carry out various changes and implement.
Claims (4)
1, a kind of image display apparatus, it is characterized in that: be included in each zone of being divided by cross one another multi-strip scanning signal wire and data signal line go up electrooptic element of forming and with its active component and pixel capacitance that forms in pairs, according to during the said scanning signals line sweep, being taken into electric charge in the above-mentioned pixel capacitance by above-mentioned active component, electrooptic element is carried out display driver
This image display apparatus also comprises: in the non-scan period of said scanning signals line, make above-mentioned data signal line be charged to the charging part of the roughly intermediate potential of the data-signal in this frame,
Picture intelligence is supplied with the image signal source of above-mentioned data signal wire driving circuit, also export charging potential to above-mentioned charging part, in the non-scan period of said scanning signals line, also make from image signal source and be charged to above-mentioned roughly intermediate potential to the signal wire (32) of above-mentioned data signal wire driving circuit output image.
2, image display apparatus as claimed in claim 1 is characterized in that: above-mentioned data signal wire driving circuit carries out line inversion driving or some inversion driving, and above-mentioned roughly intermediate potential is the current potential of opposite electrode.
3, a kind of display drive method, it is characterized in that: for the electrooptic element that on each zone of being divided by cross one another a plurality of scan signal lines and data signal line, forms and with its active component and pixel capacitance that forms in pairs, according to during the said scanning signals line sweep, being taken into electric charge in the above-mentioned pixel capacitance by above-mentioned active component, electrooptic element is carried out display driver
Described display drive method also comprises
Be charged to the roughly intermediate potential of the data-signal of this frame at the above-mentioned data signal line of non-chien shih sweep time of said scanning signals line,
In the non-scan period of said scanning signals line, the signal wire (32) of above-mentioned data signal wire driving circuit output image information also is charged to above-mentioned roughly intermediate potential from image signal source.
4, image display method as claimed in claim 3 is characterized in that: above-mentioned data signal wire driving circuit carries out line inversion driving or some inversion driving, and above-mentioned roughly intermediate potential is the current potential of opposite electrode.
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| Application Number | Priority Date | Filing Date | Title |
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| JP2001292262 | 2001-09-25 | ||
| JP2001292262 | 2001-09-25 | ||
| JP2002202978 | 2002-07-11 |
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| CNB021514909A Division CN1265336C (en) | 2001-09-25 | 2002-09-25 | Image display device and display drive method |
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| CN1794322A true CN1794322A (en) | 2006-06-28 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104094343A (en) * | 2012-02-10 | 2014-10-08 | 夏普株式会社 | Display device and display method |
| CN109584834A (en) * | 2019-01-22 | 2019-04-05 | 深圳市华星光电技术有限公司 | Liquid crystal display device and its driving method |
| CN114495850A (en) * | 2020-10-23 | 2022-05-13 | 群创光电股份有限公司 | Electronic device and electronic device driving method |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104094343A (en) * | 2012-02-10 | 2014-10-08 | 夏普株式会社 | Display device and display method |
| CN109584834A (en) * | 2019-01-22 | 2019-04-05 | 深圳市华星光电技术有限公司 | Liquid crystal display device and its driving method |
| CN114495850A (en) * | 2020-10-23 | 2022-05-13 | 群创光电股份有限公司 | Electronic device and electronic device driving method |
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