CN102789758B

CN102789758B - Drive the method for bistable electro-optic displays

Info

Publication number: CN102789758B
Application number: CN201210168851.8A
Authority: CN
Inventors: R·W·泽赫纳; H·G·加特斯; A·C·阿兰戈; K·R·阿穆德森; J·F·欧; A·N·克奈安; J·L·扎勒斯基
Original assignee: E Ink Corp
Current assignee: E Ink Corp
Priority date: 2001-11-20
Filing date: 2002-11-20
Publication date: 2016-05-18
Anticipated expiration: 2022-11-20
Also published as: JP4615860B2; EP2916312B1; JP2007249230A; JP2015064588A; CN102789764A; CN1589462A; JP2012098733A; EP2916312A1; JP5618811B2; CN101676980B; JP5758440B2; JP5905061B2; WO2003044765A2; JP2011128625A; HK1175287A1; JP4852478B2; JP2007249231A; AU2002366174A1; HK1176454A1; EP1446791A2

Abstract

A kind of bistable electro-optic displays, has multiple pixels, and each pixel can at least show three gray levels. Drive the method for this display to comprise the following steps: storage one comprises and represents the question blank to the data of the required pulse of final gray scale by initial gradation conversion, and storage represents the data of at least one original state of each pixel of display; Receive an input signal of the end-state that represents at least one pixel expectation of display; And generation output signal, represent as determined for be transformed into the necessary pulse of its desired end-state from the original state of a pixel from question blank. It is a kind of for reducing the method for residual voltage of electro-optic displays that the present invention also provides.

Description

Drive the method for bistable electro-optic displays

The application is to be on November 20th, 2002 applying date, and application number is 200910163444.6,Denomination of invention is the divisional application of the application of " method that drives bistable electro-optic displays ".

The present invention relates to a kind of method of bistable electro-optic displays and dress that this method is used of drivingPut. More properly, the present invention relates to a kind of for more accurately controlling the ash of electro-optic displays pixelThe driving method of degree state and device controller. The invention still further relates to one and make to be provided to electrophoresis showedThe driving pulse of device keeps the method for long-term direct current (DC) balance. The present invention is especially used for and baseElectrophoretic display device (EPD) in particle uses together, but is not limited to this, in this display, and Yi ZhonghuoPolytype charged particle is suspended in liquid and under the impact of electric field mobile to change in liquidThe demonstration of display.

On the one hand, the present invention relates to can be with driving for institute for the circuit that drives liquid crystal displayThe device of the electro-optical medium of the polar sensitive of electric field is provided, and wherein liquid crystal material is insensitive to polarity.

Here used as the term for material or display " electric light ", at image techniqueIn the implication of its routine relate to and a kind ofly have at least in a kind of optical characteristics different first and secondThe material of show state, by applying electric field to this material, this material becomes from its first show stateChange to its second show state. Although the normally color identified of human eye of this optical characteristics, itAlso can be other optical characteristics, for example light transmission, reflectivity, brightness or for machine-readable demonstrationPseudo-colours in electromagnetic wavelength reflectance varies meaning in the situation of device outside visible-range.

The term " grey states " that here used implication of its routine in image technique relates toA state in the middle of two extreme (extreme) optical states of pixel, and needn't meanHei-Bai conversion between two extremities. For example, several patents of speaking of below and open ShenPlease describe its extremity is white and dark blue electrophoretic display device (EPD), so middle " grey states "In fact be exactly pale blue. In fact, as already noted, the conversion between two extremities canColor transformed not to be one.

They are normal in this technology for the term " bistable state " that here used and " bistability "The implication of rule relates to a kind of display, and this display comprises at least and has not in a kind of optical characteristicsThe display unit of the first and second same show states, like this when relying on the addressing pulse of finite timeComplete arbitrary driving to limiting-members with after presenting its first or second show state, in addressingAfter end-of-pulsing, this state can continue at least several times of times (severaltimes), for example, for changingBecome display unit state at least four times of times of required addressing pulse shortest time. Be 2002The common pending application of the patent application serial numbers 10/063236 of submitting on April 2, in (is shown in corresponding simultaneouslyThe open NO.WO02/079869 of international application) shown in, some gray levels that have based on particleElectrophoretic display device (EPD) not only at their extreme black and white state, and at their middle gray stateAlso be stable, this is suitable for the electro-optic displays of some other types equally. Such aobviousShow that it is more suitable for being called " multistable " to device with respect to bistable state, although term " bistable state " can conventionallyWith here for containing bistable state and multistable display.

The term " gamma electric voltage " here using is that finger actuator is used for determining to displayer pixelThe external voltage reference of voltage is provided. Can be appreciated that bistable state electric light medium be not shown as corresponding toThe type of one-one relationship between the voltage providing and liquid crystal optics status flag, here to artThe use of language " gamma electric voltage " is accurate unlike in conventional liquid crystal display, at conventional liquid crystalIn display, gamma electric voltage is determined the flex point in electric pressure/output voltage curve.

The term " pulse " that here used refers to that by its conventional implication voltage is with respect to the timeIntegration. But some bistable state electric light media are as charge sensor, and for such JieMatter, can be used the definition of an alternative paired pulses, i.e. electric current integration (its in timeEqual provided total charge dosage). The suitable definition of paired pulses depends on that medium is as voltage-timeBetween pulse transducer or charge pulse sensor.

The bistable electro-optic displays of known several types. The electro-optic displays of one type is rotationDouble-colored first type, for example, at U.S. Patent number 5808783; 5777782; 5760761; 6054071;6055091; 6097531; 6128124; 6137467; With (although this described in 6147791The display of type is often called as " rotation twin color ball " display, but term " rotates double-colored unit "More accurate, because rotation unit is not spherical in more above-mentioned patents). So a kind of displayUse has two or more in a large number different optical characteristic part (section) and an interior dipoleThe corpusculum (being generally spherical or cylindrical) of son. These corpusculums are suspended in the liquid that is full of that is arranged in matrixIn the vacuole of body, because vacuole is full of liquid, so corpusculum can rotate freely. This displayPresentation become by applying electric field to it, and then corpusculum rotate to various positions and change from oneThe part of the corpusculum that individual sightingpiston is seen.

The electro-optical medium of another kind of type uses a kind of electrochromic media, for example a kind of with receiving lookThe electrochromic media of form membrane, described film comprises that at least a portion is by metal oxide semiconductorThe electrode forming and multiple depend on electrode can reversible color dye molecule; Referring to for exampleO ' Regan, B., waits people's Nature1991,353,737; And Wood, D., InformationDisplay, 18 (3), 24 (in March, 2002). Also can be referring to Bach, U., waits people'sAdv.Mater., 2002,14 (11), 845. Such receiving look film also has introduction, for example,At U.S. Patent number 6301038, the open NO.WO01/27690 of international application with and jointly unsettledAll on March 18th, 2002 submit to series application NO.60/365368; 60/365369 He60/365385; The series application NO.60/319279 all submitting on May 31st, 2002;60/319280 and 60/319281 and on July 31st, 2002 submit to series applicationNO.60/319438。

Another kind electro-optic displays of conscientiously having studied and develop is for many years the electrophoresis based on particleDisplay, wherein multiple charged particles move through suspension under the impact of electric field. Same liquid crystalShow that device compares, electrophoretic display device (EPD) has good brightness and contrast, wide visual angle, bistable state shapeThe characteristic of state and low-power consumption. But, the problem of these displays on long-term image quality hindersHinder being widely used of they. For example, the particle of composition electrophoretic display device (EPD) is easy to precipitation, causes thisThe deficiency in service life of a little displays.

Under the Massachusetts Institute of Technology (MIT) and EInk exabyte or transfer its multiple descriptionsThe patent of the electrophoretic medium of encapsulation and application are disclosing in the recent period. Such encapsulation medium comprisesMultiple little endosomes (capsule), each endosome itself comprises that one includes and is suspended in liquid suspensionThe improved interior phase (internalphase) of electrophoresis in medium, and an interior body wall is round interiorPhase. Conventionally, endosome is positioned at itself remain in polymer adhesive in two electrodes to form oneBetween binder course (coherentlayer). In following file, having described such encapsulation is situated betweenMatter, for example U.S. Patent number 5930026; 5961804; 6017584; 6067185; 6118426;6120588；6120839；6124851；6130773；6130774；6172798；6177921；6232950；6249721；6252564；6262706；6262833；6300932；6312304；6312971；6323989；6327072；6376828；6377387；6392785；6392786；6413790; 6422687; 6445374; 6445489 and 6459418; And U.S. Patent applicationPublication number 2001/0045934; 2002/0019081; 2002/0021270; 2002/0053900;2002/0060321；2002/0063661；2002/0063677；2002/0090980；2002/106847; 2002/0113770; 2002/0130832; 2002/0131147 He2002/0154382, and International Publication No. WO99/53373; WO99/59101;WO99/67678；WO00/05704；WO00/20922；WO00/38000；WO00/38001；WO00/36560；WO00/20922；WO00/36666；WO00/67110；WO00/67327；WO01/07961; WO01/08241; WO01/17029 and WO01/17041.

Multiple patents of above mentioning and application are recognized and can be substituted in by a kind of continuous phaseIn the electrophoretic medium of encapsulation, round the wall of discrete microbody (microcapsule), manufacture thus a kind ofSo-called dispersin polymerization body electrophoretic display device (EPD), in this display, electrophoretic medium comprises many electrophoresisThe discrete droplet of liquid and the continuous phase of polymeric material, even and discrete endosome film each list of getting along wellSolely droplet combination, the discrete droplet of the electrophoresis liquid in such dispersin polymerization volumetric display can be seenMake endosome or microbody; For example, referring to WO01/02899, the 10th page of 6-19 is capable. Also can be referring toThe common unsettled series application NO.09/683903 submitting on February 28th, 2002, and correspondingInternational Application PCT/US02/06393. Therefore, for the application's object, such dispersin polymerizationBody electrophoretic medium is counted as subspecies of the electrophoretic medium of encapsulation.

The electrophoretic display device (EPD) of encapsulation can not suffer the grumeleuse of conventional electrophoretic equipment and precipitation to damage mould conventionallyFormula, and further advantage is provided, for example on various flexibilities and rigid substrates, printing or coating are aobviousShow the ability of device. (use of word " printing " is to comprise the printing of whole forms and coating, comprises(but not limiting to so): for example post-chip mouth mould applies, slit or Extrusion Coating, slide or classification is coated withCover, the metering in advance that curtain applies applies; For example roller coat on cutter, the forward or oppositely roller coat of roller coat,Notch board applies; Immersion coating; Spraying; Meniscus applies; Spin coating; Brush; Air knife applies; SilkReticulated printing processing; Electrostatic printing processing; Temperature-sensitive printing treatment; Ink jet printing processing; With other classLike technology. ) display that obtained thus can be flexible. In addition, because display medium can(making in all sorts of ways) printing, therefore display itself can become cheap.

A kind of electrophoretic display device (EPD) of respective type is so-called " microcell electrophoretic display ". At micro-listIn unit's electrophoretic display device (EPD), charged particle and suspension are not to be encapsulated in microbody but to remain on formationIn multiple cavitys in the mounting medium of polymer film normally. For example,, referring to all transferringThe open NO.WO02/01281 of international application of SipixImaging company, and disclosed U.S. ShenPlease NO.2002-0075556.

The bistable state of the electrophoretic display device (EPD) based on particle or multistable characteristic and other electro-optic displays tableThe formation of existing similar characteristics and traditional liquid crystal (" LC ") display striking contrast. Distortion toRow liquid crystal is not bistable state or multistable but as voltage sensor, so no matter be originally present inGray level on pixel and the electric field of a setting is provided to the pixel of this display, on pixelProduce the gray level of an appointment. In addition, liquid crystal display only drive in a direction (fromNon-transmissive or " black " arrives transmissive or " bright "), the reverse transformation from bright state to black state is logicalCross and reduce or remove that electric field realizes. Finally, the gray level of liquid crystal display pixel is to electric fieldPolarity is insensitive, and only to its magnitude, and in fact for technical reason, business liquid crystalDisplay often drives the polarity of electric field with the upset of interval frequently.

By comparison, first approximate part, bistable electro-optic displays is as pulse transducer,So the end-state of pixel not only depends on the time of applied field and applied field, but also complies withLai Yu applies the electric field state of pixel before. In addition, have been found that now at least many based onIn the electro-optic displays of particle, by gray level (as sentenced by eyes or normalized optical instrumentDisconnected) equal change change the required pulse of a given pixel and need not to be constant, they also needn'tInterchangeable. For example, imagine a kind of display, its each pixel can show for 0 (in vain),The gray level of 1,2,3 (black), relatively good at certain intervals. (interval between gray level canTo be linear in reflectance factor percentage, as surveyed by eyes or instrument, but also canTo use other distribution. For example, it is linear that distribution can be in L*, or can select to carryFor a specific gamma value; 2.2 gamma value, through being usually used in monitor, is wherein used this display conductThe alternative of monitor, can use similar gamma value as required. ) have been found that by pixel fromThe required pulse warp of variation (being hereinafter called for simplicity " 0-1 conversion ") of 0 grade to 1 gradeNormal and 1-2 or 2-3 change required different. And 1-0 changes required pulse needn'tIdentical with contrary 0-1 conversion. In addition, some system performances show a kind of " storage " effect,Like this (such as) 0-1 changes required pulse and depend on whether particular pixels experiences 0-0-1,1-0-1 or 3-0-1 change and change a little. (wherein, symbol " x-y-z " represents on timeBetween the sequence of optical states of sequential access, x here, y, z is optical states 0,1,2 or 3. )Although can by by required pixel driving to before another state with a basic cycle by displayAll pixel driving alleviate or overcome these problems to one of extremity, but producePure color " flicker " is often unacceptable; For example, the reader of e-book may need booksText under screen, roll, if display needs black or pure white with interval flashing frequently,That reader may be made or be lost dizzy his position. In addition, this flicker of display has increasedPower consumption and can reduce service life of display. Finally, have been found that at least in certain situationUnder, a certain particular conversion required pulse is subject to temperature and shows total operating time, and particular pixels existsBefore given conversion, remain on the impact of the time of a certain particular optical state, in order to ensure accuratelyHalf tone reproduction, need to compensate these factors.

In one aspect, the present invention seeks to provide a kind of method and controller, can be without showingOn device, carry out pure color flicker and provide gray level accurately to electro-optic displays with interval frequently.

In addition,, as being easy to find out from describe above, the driving of bistable state electric light medium requires to makeMust for drive AMLCD (AMLCD) design driver do not revise be unsuitable for forBased on the display of bistable state electric light medium. But such AMLCD driver is commercially easyIn acquisition, there is large allowable voltage scope and high pin count encapsulation, there is the base can be purchased off the shelfPlinth, low price, therefore such AMLCD driver is for driving bistable electro-optic displays to beAttractive, and customization is similarly the driver reality based on bistable state electric light medium displayCan be more expensive on border, also to take Basic Design and manufacturing time. Therefore, amendment AMLCD drivesDevice has the advantage on cost and construction cycle for bistable electro-optic displays, and the present invention seeks to carryEnergy supply meets a kind of method of this point and the driver of amendment.

Equally, as already mentioned, the present invention relates to the method for drive cataphoresis display, making providesKeep long-term direct current (DC) balance to the driving pulse of electrophoretic display device (EPD). Have been found that encapsulation andOther electrophoretic display device (EPD) need to drive and (, have a high regard for for demonstration with the waveform of accurate DC balanceOne particular pixels electric current will remain the integration of time in the whole expanded period that shows operationZero), to keep image stabilization, maintain symmetrical switching characteristic and provide the maximum of display to useLife-span. For the power supply supply that keeps the conventional method needs of accurate DC balance accurately to control, useIn the precise voltage modulating driver of gray scale and for crystal oscillator regularly, top and likeThe cost that has greatly increased display is provided.

And, even if increased the parts of such costliness, still do not realize real DC balance.Empirically find, many electrophoretic mediums have asymmetric current/voltage (I/V curve),Although the present invention is not subject to any restriction of this understanding, believe that this skew curve is attributed toElectrochemical voltage source in medium. Even if meaning, this skew curve in both cases willVoltage is careful to be controlled when being accurate consistent, (vacation when medium is addressed to an extreme optical stateIf black) electric current and this medium while being addressed to relative extreme optical state (supposing white)Not identical.

Have been found that now the unbalanced degree of direct current in the electrophoretic medium using in displayCan (hereinafter be called for convenience " the residual voltage of medium by measuring open electrochemical current potential(remnantvoltage) ") find out. In the time that the residual voltage of pixel is zero, it is justGood DC balance. If it is non-equilibrium that residual voltage for just, is exactly direct current in positive direction.It is non-equilibrium if residual voltage for negative, is exactly direct current in negative direction. The present invention uses remaining electricityPress data to keep the long-term DC balance of display.

Therefore, in one aspect, the invention provides a kind of method that drives bistable electro-optic displays,Described display has multiple pixels, wherein each can show at least three gray levels (asIn conventional Display Technique, extremely black and white state is considered for for calculating two of gray levelGray level). This method comprises:

Store a question blank, it is preserved and indicates to change the final gray level of an initial grey levels toThe data of required pulse;

Storage represents the data of at least one original state of each pixel of display;

Receive the input signal of an expectation end-state of at least one pixel that represents display; With

Produce an output signal, represent the original state of described pixel to be transformed into the final of its expectationThe pulse that state is required, as from as described in determine question blank.

This method is for simplicity hereinafter referred to as " question blank method " of the present invention.

The present invention also provides a kind of device controller making in this way. This controller comprises:

Storage device, preserves and indicates to change the final gray scale of an initial grey levels to for storageThe question blank of level required pulse data and represent at least one original state of each pixel of displayData;

Input unit, for receiving an expectation end-state of at least one pixel that represents displayInput signal;

Calculation element, for the original state from input signal, the described pixel of expression storedData and question blank are identified for the original state of a described pixel to change expire and hope finalThe pulse that state is required; And

For generation of the output device of output signal that represents described pulse.

The present invention also provides a kind of method that drives bistable electro-optic displays, and described display hasMultiple pixels, wherein each can show at least three gray levels. The method comprises:

Produce an output signal, represent that the original state of described pixel is transformed into it expects final shapeThe pulse that state is required, as from as described in determine question blank, described in output signal indicates to offerThe time cycle of the substantially invariable driving voltage of pixel.

Calculation element, for the original state from input signal, the described pixel of expression storedData and question blank are identified for the original state of a described pixel to change to expire to hope final shapeThe pulse that state is required; And

For generation of the output device of output signal that represents described pulse, output signal indicates to carrySupply with the time cycle of the substantially invariable driving voltage of described pixel.

In yet another aspect, the invention provides a kind of device controller that uses the inventive method. ShouldController comprises:

Storage device, preserves and indicates to change the final gray scale of an initial grey levels to for storageAt least one original state of the question blank of level required pulse data and each pixel of expression displayThe question blank of data;

For generation of the output device of output signal that represents described pulse, output signal represents multipleThe pulse changing at least one of voltage and duration, a predetermined period of time at the expiration afterOutput signal is expressed as no-voltage.

In yet another aspect, the invention provides a kind of driving having for being connected to electro-optic displaysThe drive circuit of the output line of electrode. This drive circuit comprises the first input unit, for connecingReceive multiple indicate to be placed on signal voltage on drive electrode and (n+1) bit digital of polarity; AndFor the secondary input device of receive clock signal. One receives clock signal, and drive circuit justSelected voltage is presented on its output line. In a preferred form of this drive circuit, instituteSelecting voltage can be between R and R+V 2ⁿAny in individual discrete voltage or at R and R-VBetween 2ⁿAny in individual discrete voltage, wherein R is predetermined reference voltage (normally active squareThe voltage of the public front electrode of battle array display, as be described in more detail below), V is this driverCircuit is determined (assert) and maximum differential pressure reference voltage. These selected voltages can be linesProperty is distributed within the scope of R ± V, can be also nonlinear way distribute, this non-linear can be by twoGamma electric voltage individual or that be more positioned at particular range is controlled, one of each gamma electric voltage definitionLinear conditions (regime) between gamma electric voltage and adjacent gamma value or reference voltage.

In yet another aspect, the invention provides a kind of driving having for being connected to electro-optic displaysThe drive circuit of the output line of electrode. This drive circuit comprises the first input unit, for connecingReceive multiple indicate to be placed on signal voltage on drive electrode and 2 bit digital (2-bit of polarityNumber); And for the secondary input device of receive clock signal. One receives clock signal,Drive circuit is just from R+V, selected voltage in R and R-V (wherein R and V as above define)Be presented on its output line.

In yet another aspect, the invention provides a kind of bistable electro-optic displays method that drives, specialBe the method for drive cataphoresis display, described display shows a residual voltage. The method comprises:

(a) provide the first driving pulse to the pixel of display;

(b) after the first driving pulse, measure the residual voltage of pixel; And

(c) after the measurement of residual voltage, provide the second driving pulse to pixel, rely on measuredResidual voltage control the second driving pulse size to reduce the residual voltage of pixel.

This method can be called " residual voltage " of the present invention method hereinafter for convenience's sake.

Fig. 1 represents apparatus of the present invention, the showing of the display being driven by this device and associated apparatusBe intended to, be designed to show the structure of whole system;

Fig. 2 is the schematic block diagram of the controller unit shown in Fig. 1, and has illustrated by producing this unitRaw output signal;

Fig. 3 represents that the controller unit shown in Fig. 1 and 2 produces a certain output letter shown in Fig. 2Number the schematic block diagram of mode;

Figure 4 and 5 represent can be for two of display shown in Fig. a kind of different reference voltage setting;

Fig. 6 be illustrated in look-up-table method of the present invention pulsewidth modulation and voltage modulated method itBetween balance schematic diagram;

Fig. 7 is the block diagram of customization (custom) driver for look-up-table method of the present invention;

Fig. 8 is that explanation can be by the flow chart of the program of the operation of controller unit shown in Fig. 1 and 2;

Fig. 9 and 10 has shown two kinds of drive arrangements of the present invention;

Figure 11 A and 11B have shown two parts of the third drive arrangements of the present invention.

As pointed out above, question blank part of the present invention provides for driving electric light to showThe method of device and controller, described display has multiple pixels, and wherein each can showAt least three gray levels. The present invention can show for the electric light with greater number gray level certainlyDevice, for example 4,8,16 or more.

Similarly, as described above, drive bistable electro-optic displays need to be generally used for driving liquid crystalShow the method that device (LCD) is entirely different. In conventional (non-cholesteric) LCD, apply to pixelThe specific voltage in enough cycle, can make pixel obtain a particular gray level. And, liquidThe only magnitude to electric field of brilliant material, and insensitive to its polarity. By comparison, bistable electroOptical display unit is as pulse transducer, so do not applying voltage and obtaining between grey states a pair ofOne mapping; Must be applied to pixel for obtain a given grey states pulse (with thusVoltage) change with " initially " grey states of corresponding pixel. In addition, due to bistable state electric lightDisplay need to be on both direction (arrive in vain black, and black in white) drives, so need to specify instituteNeed polarity and the size of pulse.

Here need to consider that the conventional sense in Display Technique defines some and makes at this according to it,With term. Most of discussion below concentrate on experience from " initially " state to " finally " shapeThe one or more elephant of the single gradation conversion (, from a kind of gray scale to alternative variation) of stateElement. Obviously, original state and end-state are appointed as and are only considered the single conversion of studying, andIn most of the cases, pixel has lived through conversion before " initially " state, and " finally "Also will be through conversion after state. As explanation below, some embodiments of the present invention not only can be consideredInitial and the end-state of pixel, also can consider pixel reach existing before original state "Before " state. Here need between front state, distinguish multiple, " first at front shape for termState " be used in reference to corresponding pixel and exist the state of one (non-zero) before original state conversion,Term " second at front state " be used in reference to corresponding pixel exist one first before front stateThe state of (non-zero) conversion, the like. Term " non-zero conversion " be used in reference to realize at least one" conversion " of individual gray scale unit change; Term " zero conversion " is used in reference to and does not produce selected pixel ash" conversion " of any variation of degree (turns although other pixel of while display can experience non-zeroChange).

As those skilled in the art are easy to find out, a simple embodiment of method of the present inventionOriginal state and the end-state that can only consider each pixel, in this case, question blank isTwo dimension. But as already noted, some electro-optical mediums show storage effect, and thisThe medium of sample needs, and in the time producing output signal, need to not only consider often for this mediumThe original state of individual pixel, but also will (at least) consider this pixel first at front state,In this situation, question blank is three-dimensional. In some cases, may need to consider each pixelMore than one at front state, cause thus in question blank, having four (if only consider firstWith second at front state) or various dimensions more.

From form mathematical terms, the present invention can regard as and comprise an algorithm, provides relevant electric lightInitial and final and (optionally) of pixel is in the information of front state, and (optional-ginsengIn seeing below, discuss in more detail) about the information of the physical state of display, can produce one canThe function V (t) changing to be implemented to the end-state of expectation for pixel. Go out from this form viewpointSend out, controller of the present invention can be regarded in fact a physical embodiments of this algorithm as, controlsDevice is as the interface between equipment and the electro-optic displays of desired display information.

Temporarily ignore physical state information, according to the present invention, be question blank this algorithm coding or turnChange matrix. This matrix has each one dimension for the end-state expected, and makes in calculatingBy the each dimension for other state (initial and any at front state). The key element of matrix can be wrappedDraw together to be used for electro-optical medium function V (t).

The key element of question blank or transition matrix can have various ways. In some cases, Mei GeyaoElement can comprise single number. For example, electro-optic displays can use can export multiple at a baseThe high-accuracy voltage modulating driver circuit of the upper and lower different voltages of accurate voltage, and simply with oneThe predetermined period of standard provides required voltage to pixel. In this case, every in question blankIndividual entry can simply have the form of individual integer, and this integer is specified will provide which to given pixelIndividual voltage. In another case, each key element can comprise relate to waveform diverse location one beColumns. For example, the embodiments of the invention that are described below use single or double prepulses waveform,And specify such required pulse to it may be noted that several numbers of the diverse location of waveform. Equally belowWhat talk about is embodiments of the invention, and it selects multiple son scanning weeks in a complete scanIn interim several process, by a predetermined voltage is provided to pixel, effectively apply pulse is longDegree modulation. In such embodiments, the key element of transition matrix can have several and indicates whether in phaseIn every sub-scan period should changing, apply the form of predetermined voltage. Finally, as more detailed belowDescription, in some cases, for example temperature-compensating display, can be for the key element of question blankBe that (or what in fact more definite was in such function is each for the form of function more easilyPlant the coefficient of item).

Obviously the question blank that used in some embodiments of the invention can become very large. Lift oneIndividual extreme example, imagination considers that by a kind of two of initial, the final sums algorithm at front state is used for256(2⁸) operation of the present invention of gray level display. Required four-dimensional question blank has 2³²Individual barOrder. If each entry needs (hypothesis) 64 (8 byte), the total amount of question blank can be soApproximately 32G byte. Although what the data of the so large quantity of storage do not have and ask on desktop computerTopic, but in portable equipment, just may have problems. But, in fact so large question blankSize can greatly reduce. Under many circumstances, have been found that the ripple that only has little numberShape type needs a large amount of different switching, and the length of the independent pulse of for example common waveform is in differenceBetween conversion, change. Therefore, can be by making each entry comprise that following part reduces in inquiryThe length of independent entry in table: (a) sensing is used to specify the peanut type of waveform that will useOne of at the second table discal patch object pointer; And (b) one specify common waveform how for relevantThe parameter of the peanut that conversion changes.

Can pre-determine in question blank discal patch object value by an experience optimal processing. SubstantiallyUpper, pixel is set to corresponding original state, provide one to need the expectation that obtains according to estimationThe roughly the same pulse of whole state, and the end-state of measuring pixel is to determine actual and to expect finalDeviation between state, if this deviation exists. Then this processing meeting repeats with modulating pulseCarry out until deviation is less than predetermined value, this can be come by the function of the instrument for measuring end-stateDetermine. Considering in the situation of the method at front state of one or more pixels, except initiallyOutside state, when pixel state is in the original state for determining pulse and whole in front stateFor constant time, generally first determine the required pulse of particular conversion, then consider differentIt is easily that front state carries out " accurate adjustment " to this pulse.

The present invention expects to provide in the time of the variation of total operating time of considering temperature and/or displayPaired pulses modulation, and due to " aging " of some electro-optical mediums and after long period of operation their shapesThe compensation to the operating time that the variation of state may need. Such modulation can one or both sidesMethod realizes. First, can adding by every kind of variable for considering in the time calculating output signalDimension is carried out extended look-up table. Obviously, when processing example is during as the continuous variable of temperature and operation, forQuestion blank is remained in a specific finite size, need to quantize continuous variable. ForFind out the waveform that will be applied to pixel, calculation element can be selected the conduct of question blank entry simplyApproach most the form of measured temperature. Alternatively, for temperature-compensating is more accurately provided, calculate dressPut can find in the continuous variable both sides that record two in abutting connection with question blank entry, and apply oneSuitable interpolation algorithm obtains the required entry at the variable median place recording. For example, supposeMatrix comprises the temperature entry increasing progressively with 10 DEG C. If actual display temperature is 25 DEG C, soCalculating can be found the entry of 20 DEG C and 30 DEG C and use this median of two. Notice due to and temperatureThe characteristic variations of degree electro-optical medium is not together often linear, so question blank storage is temperatureThe entry that degree arranges can be by linear distribution; For example, the variation of many electro-optical medium temperatureMostly accelerate at high temperature place, be therefore in question blank the spacing of 20 DEG C at low temperature just enough, andAt high temperature place, the spacing of 5 DEG C can meet the demands.

A kind of can system of selection be the letter using with physical descriptor for the compensation of temperature/operating timeNumber form formula or perhaps in the question blank entry of the more severity factor of such function Plays item. ForThe situation that the display of drive scheme is modulated in simple consideration service time, wherein passes through to each pixelProvide the constant voltage (arbitrary polarity) of a variable time span to control each conversion, because ofThis, the correction of saving any environmental variance, each entry in question blank can only comprise tableShow the duration of the constant voltage that will apply and the single signed number of its polarity. If neededFor the such demonstration of variations in temperature correction, so in temperature t for particular conversion need to applyThe time T of constant voltage_tProvided by following formula:

T_t＝T₀+AΔt+B(Δt)²

Wherein T₀Be the time needing in some normal temperature places, normally display is estimated operating temperature modelThe mid point enclosing, Δ t is at t with at T₀Poor between measured temperature, the entry in question blank canTo comprise T₀And for relating to the A of particular conversion and the value of B of given entry, and calculation elementCan calculate the T at measured temperature place with these coefficients_t. Be pushed into more at large, calculatedDevice is found out the question blank entry that is suitable for corresponding initial and end-state, then uses by this entry calmlyThe function of justice calculates the suitable output signal of having considered other variable that need to consider.

The associated temperature of calculating for temperature-compensating is the temperature of the electro-optical medium in corresponding pixel,And this temperature can be obviously different with environment temperature, particularly to be used for outdoor application at displaySituation under, for example sunlight causes the temperature of electro-optical medium layer real by front fender effect thereWill be higher than environment temperature on border. In fact, in the situation of the huge outdoor mark of bulletin template,For example, if the part of display falls under the shade of adjacent building, other parts are at sunlightIn, the temperature on so same display between different pixels can be different. Therefore, may needIn electrooptic layer or contiguous its embed one or more electric heating occasionally other temperature sensor to surveyThe actual temperature of this layer. In the situation of large display, may also need to be defined in by many temperatureInterpolation method between the temperature that degree sensor records is to estimate the temperature of each particular pixels. Finally, existIn situation by the large display of the many module compositions that can replace separately, method of the present invention andController can specify the different operating times for the pixel in disparate modules.

Method of the present invention and controller it is also conceivable that the residence time of the particular pixels that will drive(being the cycle that pixel maintains a non-zero conversion). Have been found that at least in some cases, for givingSurely change required pulse along with the residence time of pixel in its optical states changes. Like this, justExpect or must be using the pulse for given conversion as pixel in the time of its initial optical state residentBetween function and change. In order to complete it, question blank can comprise that one by a counter indexThe additional dimension that is used to indicate the residence time of pixel in its initial optical state. In addition control,Device processed need to contain an additional storage of the counter that is useful on each pixel in display. This alsoNeed a read clock, it is increased so that interval to be set by the count value that is stored in each pixel. BetweenEvery length must be the integral multiple of display frame-period, therefore must be not less than a frame period.The size of counter and clock frequency can be by pulse elapsed time length and necessity of variation usedTemporal resolution decide. For example,, for 4 digit counters of each pixel storage can allowPulse in 4 second cycle (4 seconds × 4 times counting/second=16 times counting=4) with 0.25The interval variation of second. For example, once particular event this counter occurs can zero clearing, the conversion of pixelArrive a kind of new state. Once reach its maximum, can counter be set to " upset " and arriveZero count, or keep its maximum until it be cleared.

Certainly can be according to the pulse of any or more particular conversion that need to produce electro-optical mediumConsider that any physical parameter that other has detectable effect changes question blank method of the present invention. ExampleAs, if find that electro-optical medium, to humidity sensitive, can change this method wet with combining environmentalThe correction of degree.

For bistable state electric light medium, question blank can have following characteristics, at the beginning of any pixelZero conversion identical with end-state of beginning, entry is zero, or in other words, does not have voltage and executeBe added on pixel. As an inevitable outcome, if do not resembled on display in given intervalElement changes, and just needn't apply pulse. This can realize super low-power consumption operation, has also guaranteed showingWhen still image, electro-optical medium can excessively not drive. Generally, question blank only can retain about non-zero and turnThe information of changing. In other words, for two images, I and I+1, if given pixel at I andIn I+1, in identical state, state I+1 just can not be stored in front state table so, andAnd until just can store again information after the conversion of pixel experience.

As being apparent for the professional in modern electronic technology field, of the present inventionController can have various physical form. And can use any routine data processing unit.For example, can realize this method with general purpose digital computer, this computer with for will be fromThe numeral output of computer be converted to suitable pixel voltage suitable equipment (for example, one orMore multiple digital analog converter, " DAC ") combine. Optionally, method of the present invention can be passed throughUse special IC (ASIC) to realize. Especially, controller of the present invention can haveThe form of video card, it can be inserted into and in PC, make the image being produced by computer be presented atReplace on the existing display screen of for example LCD or the supplementary electric light screen as existing display screen. ByIn the structure of controller of the present invention just in the technical merit in image processing techniques, so needn'tDescribe its circuit details in detail at this.

The preferred physical embodiments of controller of the present invention is a kind of timing controller integrated circuit(IC). This IC receives input image data and output is used for Data Collection and the control of selecting drive ICSignal processed, produces the image of expectation to produce suitable voltage on pixel. This IC can pass throughAccess is preserved the storage buffer of view data and is received view data, or can receive and be used for drivingThe signal of moving traditional LC D panel, therefrom extracts view data. It can also receive arbitrarily and preserveThe serial signal of its necessary pulse computing information that need to carry out. On the other hand, this timing controllerAvailable software realizes, or is combined into a part of CPU. This timing controller can also have surveyAny impact of measuring for example temperature shows the ability of the external parameter of operation.

Controller can operate as follows. The question blank that storage control can obtain in memory.For each pixel successively, initial, the final sum (optionally) being necessary is at front and thingReason status information all provides as input. Then these status informations are for calculating question blankIndex. In the situation of the temperature quantizing or other correction, from the return of value of this inquiry can beA voltage, or the array of voltages of a relative time. Controller can be in question blank twoIndividual bracketing temperature repeats this operation, then between these values, carries out interpolation. For algorithm temperatureDegree is revised, and the return of value of question blank has one or more parameters, then described above, can be byEquation of the synthermal substitution together of these parameters is to determine the appropriate format of driving pulse. This programCan realize in a similar fashion for the system variable of other any demand motive pulse real-time change.One or more such system variables can be by for example constructing for the performance of optimizing displayIn time, is arranged on the value of the programmable resistance on display floater or is stored in the memory in EPROMDetermine.

An important feature of this display controller is that it does not resemble most of displays, at great majorityIn actual conditions, need several complete reading scans in order to complete an image update. Be a figureThe required several scannings of picture renewal should form one and can not be interrupted unit. If display controller andImage source simultaneously operating, this controller must ensure that the data for provided pulse is provided exist soIn whole scanning, keep constant. This can realize with one or both methods. First, input pictureData can be stored in an independent buffer (alternatively, if show control by display controllerDevice processed is accessed display buffer by dual-ported memory, and it should block the visit from CPUAsk). Secondly,, in scanning for the first time, controller can be stored in the pulse of calculating a pulseIn buffer. The benefit of this second option is the house-keeping of each conversion for scanning panel(overhead) only carry out once, and can be directly defeated from buffer for the data that keep scanningGo out.

Optionally, image update can be with a kind of synchronous mode processing. In general, although oneAs produce the once complete conversion between two images and can spend several times scanning, but pixel can separatelyStart the conversion that conversion or upset have started in the centre of frame. In order to realize this, controller mustMust remember for which part of the whole conversion of given pixel to have completed. If receive changeThe not request of the optical states of the pixel in current conversion, so a counter for this pixelCan be cleared, and this pixel can start conversion in next frame. If when receiving new askingWhile asking, pixel is effectively in conversion, and controller can provide an algorithm to determine how from currentFrame intermediateness arrive new state. For the normal image stream of 1, a kind of possible algorithmThe pulse that a upset polarity is provided simply, its through amplifies and have with provideThe duration that prepulse part is identical.

In order to make the required minimum power of operation display, and make the picture steadiness of electro-optical mediumMaximize, in the time not having pixel to change in display, this display controller can stopStop the scanning of display and reduce to be applied to the voltage of all pixels or make it approach zero. Highly beneficialBe that this display controller can be closed to its corresponding line when display is during in " maintenance " stateWith the power supply of row driver, can make like this minimise power consumption. In this scheme, when under requestWhen a pixel conversion, this driver can be reactivated.

Accompanying drawing 1 schematically shows the device of the present invention using together with associated apparatus. Institute in Fig. 1The whole devices (be often referred to and be shown 10) that show comprise an image source, as shown in one in dataOn line 14, output represents the PC 12 of view data. Data wire 14 can be anyGeneral type and can be an independent data wire or bus; For example, data wire 14 can wrapDraw together USB (USB), serial, parallel, IEEE-1394 or other line. On online 14The data of placing can be conventional bit map as form, for example bitmap (BMP), label imageFile format (TIF), GIF (GIF) or associating (Jooint) motion picture expert group version(JPEG) file. But optional, the data of placing on online 14 can be to look for drivingFrequently the signal form of equipment; For example, many computers provide a kind of for driving looking of external displayFrequently output, and signal in this output can be for the present invention. In the technology of image processing fieldPersonnel can recognize the present invention's device described below carry out possibly constituent instruments format conversion and/ or decoding, to use dissimilar available input signal, but such conversion and/or decode rightThose skilled in the art are known, therefore, only can retouch device of the present invention from this pointState: as the view data of its original input be transformed into into device of the present invention manageableForm.

As described in detail later, data wire 14 extends to controller unit 16 of the present invention. This controlDevice processed unit 16 produces one group of output signal and on independent data/address bus 20 on data/address bus 18Produce second group of signal. Data/address bus 18 is connected to two row (or grid) driver 22, andData/address bus 20 is connected to multiple row (or source) driver 24 and (drives at the row shown in Fig. 1The number of moving device is for the ease of representing greatly minimizing). Row and column driver control bistable electro light display is shownThe operation of device 26.

Be selected to represent various available cell at the device shown in Fig. 1, it is suitable for a kind of examination most" breadboard " unit of the property tested. In actual business is manufactured, just as the tradition at assembling LCDTake in formula computer and personal digital assistant, controller 16 can become the same thing of display 26 conventionallyThe part of reason unit, and image source also can become the part of this physical location. Same, the present inventionBe illustrated in Fig. 1 and mainly describe in conjunction with a kind of Active Matrix Display structure below, thisDisplay device structure has the independent common transparent electrode in a side of electrooptic layer, this public electrodeExtend through whole pixels of display. Conventionally, this public electrode be positioned at electrooptic layer and observer itBetween and form an observer and watch the sightingpiston of display by it. In a contrary side of electrooptic layerPlacing the pixel capacitors matrix of arranging with row and column, like this by independent row and the independent infall being listed asUnique definite each pixel capacitors. Thus, by changing with respect to the electricity that is provided to public front electrodePress the voltage that is provided to corresponding pixel electrode of (being generally expressed as " Vcom "), control by electrooptic layerThe electric field that stands of each pixel. At least with one transistor of each pixel capacitors is connected, conventionallyIt is thin film transistor (TFT). On every row, transistorized grid is connected to go through independent prolongation column electrode and drivesOn one of moving device 22. often list transistorized source electrode through independent prolongation row electrode be connected to row driveOn one of moving device 24. Each transistorized drain electrode is directly connected in pixel capacitors. Be appreciated thatGrid is random to row and source electrode to the distribution of row, just as the distribution of source electrode and drain electrode, isCan reverse. But below describing can the conventional distribution of hypothesis.

In operation, line driver 22 applies voltage to grid, has one like this in arbitrary preset timeIndividual and to only have the transistor of a line be conducting. Meanwhile, row driver 24 provides predetermined voltage to arriveEach row electrode. Thus, the voltage that is applied to row driver is only provided in a line of pixel capacitors,On electro-optical medium, write like this image that (or writing at least partly) a line is expected. Then row drivesMoving device switches the transistor turns making in next line, and a different set of voltage is applied to row electricityThe utmost point, writes next line image.

It is emphasized that and the invention is not restricted to such Active Matrix Display. As long as according to thisClearly make the precision waveform for the each pixel of image, can be with any handover scheme to resemblingElement provides waveform. For example, the present invention can use the scheme of a kind of so-called " directly driving ",Wherein independent drive wire offers each pixel. In principle, the present invention can also use oneFor the passive-matrix drive scheme of some LCD, but it should be noted that due to many bistablesState electro-optical medium lacks switching threshold and (,, as long as provide one to prolong macrocyclic very little electric field, is somebody's turn to doMedium will change optical states), so being unsuitable for passive-matrix, such medium drives. But,Owing to it seems that the present invention finds that it is mainly used in Active Matrix Display, so the present invention is at thisMainly to be described with reference to such display.

Controller unit 16 (Fig. 1) has two major functions. The first, use side of the present inventionMethod, controller calculates and will change to final image from initial pictures and must be applied to displayer pixelOn a two-dimensional matrix of pulse (or waveform). The second, use the routine designing for LCD to driveMoving device drives bistable electro-optic displays, and controller 16 calculates and will resemble from this dither matrixOn element electrode, apply and expect the required whole timing signals of pulse.

As shown in Figure 2, there are two major parts at the controller unit 16 shown in Fig. 1,Buffer memory represents that controller 16B will be written to the final image data of display 26 (Fig. 1)Frame buffer 16A, and controller itself, be designated as 16B. Controller 16B is from buffer 16AIn pixel reading out data produce various signals as described below on data/address bus 18 and 20 one by one.

Signal shown in Fig. 2 is as follows:

(obviously, the figure place in this signal can be according to used for six magnitudes of voltage of D0:D5-pixelParticular row and column driver and change)

POL-is with respect to the pixel polarity of Vcom (vide infra)

START-places a start bit to start the loading of pixel value in row driver 24

The horizontal-drive signal of HSYNC-breech lock row driver

PCLK-switches the pixel clock of start bit along line driver

VSYNC-is loaded into start bit the vertical synchronizing signal of line driver

The output enabling signal of OE-breech lock line driver.

In these signals, although the definite timing of these signals certainly can be according to used precision electricityLight medium and changing, due to line scanning method in device shown in Fig. 1 in principle and LCD sweepThe method of retouching is identical, substantially and in routine has so be provided to VSYNC and the OE of line driver 22The corresponding signal that is provided to line driver in the matrix LCD of source is the same. Similarly, for START,HSYNC and PCLK, although their timing meeting changes according to the accurate electro-optical medium using,These signals that are provided to row driver substantially and in conventional thin film transistor，Bao Mojingtiguan, be provided to row and driveThe corresponding signal of moving device is the same. Therefore, can think and there is no need to further describe these output lettersNumber.

Fig. 3 is illustrated in the controller 16B shown in Fig. 2 in highly schematic mode and produces D0:D5Method with POL signal. As mentioned above, controller 16B storage represents that final image 120 (shouldImage is to expect to write display), write in advance the initial pictures 122 of display and can selectOne or more data at front image 123 that write display before initial pictures. ?Embodiments of the invention shown in Fig. 3 stored two such at front image 123. (obviously, mustWant the storage of data can be at controller 16B or in an external data storage device. Controller16B uses particular pixels (as shown at Fig. 3 shade, being expressed as first pixel of the first row)Initial, final and in the data of front image 120,122 and 123 as entering question blank 124Pointer, this question blank provides the state that will change this pixel to the expectation gray scale in final imageLevel must be applied to the value of the pulse of particular pixels. By the synthetic output from question blank 124 withAnd be provided to a voltage v. who produces D0:D5 and POL signal from the output of frame counter 126Frame array 128.

Controller 16B is designed to use together with TFTLCD driver, and this driver is equipped with logicalOften change the pixel reverse circuit of adjacent image point polarity with respect to end face. The pixel at interval can designFor by even number and odd number and be connected in the two opposite sides of voltage ladder. In addition be labeled as, " polarity "Driver input for switching the polarity of even number and odd number pixel. Driver is together with four or moreGamma electric voltage grade provides together, can determine voltage-grade song to arranging of above-mentioned electric pressureThe slope local of line. The exemplary with the commercial integrated circuit (IC) of these features is SamsungsKS0652300/309 passage TFT-LCD Source drive. The display that drive as mentioned above, makesBe used in the public electrode in electro-optical medium one side, be applied to the Voltage Reference of this public electrode as " topFace voltage " or " Vcom ".

In an embodiment as shown in Figure 4, the reference voltage of driver is arranged as end face electricityPressure is positioned in the half of the maximum voltage (Vmax) that driver can provide,

Vcom＝Vmax/2

And gamma electric voltage is arranged as in the upper and lower linear change of end face voltage. (Figure 4 and 5 are odd numbers of hypothesisGamma electric voltage draw, so for example gamma electric voltage VGMA (n/2+1/2) etc. in Fig. 4In Vcom. If there is the gamma electric voltage of an even number, VGMA (n/2) and VGMA (n/2+1)All arrange and equal Vcom. Similarly, in Fig. 5, if there is the gamma electric voltage of an even number,VGMA (n/2) and VGMA (n/2+1) arrange and equal ground voltage Vss). Obtain all conversions instituteThe pulse length needing is set up the required maximum impulse of new images by Vmax/2 and is decided by distributing. ShouldPulse can be converted into frame number by being multiplied by reading scan rate. Then necessary frame number be multiplied by 2 with toGo out even number and the odd-numbered frame of a great deal of. These even numbers and odd-numbered frame can corresponding to polarity position with respect toThis frame is to be set to height or low. For the each pixel in every frame, controller 16B must provideA kind of algorithm is even number or odd number with (1) pixel; (2) for considered frame, polarity positionHigh or low; (3) desired pulse is just or bears; And (4) expect the size of pulseAs its input. Then algorithm determines that can this pixel addressed with the polarity of expecting in this frame again.If so, just provide suitable driving voltage (pulse length) to this pixel. If not, willThis pixel is parked in end face voltage (Vmax/2) to be located at hold mode, wherein in this frame, does not haveThere is electric field to be applied to pixel.

For example, consider two adjacent image points in display, an odd image element 1 and an icon element 2.And, suppose that (odd image element can access positive drive voltage range when polarity position is when being highOn end face voltage), icon element can be accessed negative voltage (below end face voltage). IfPixel 1 and 2 all need to drive with positive pulse, must have so following order:

(a) in positive polarity frame, drive pixel 1 with positive voltage, pixel 2 remains on end face voltageOn; With

(b) in negative polarity frame, pixel 1 remains on end face voltage, and drives pixel with positive voltage2。

Although general frame can be with alternately (that is, the replacing) of positive-negative polarity of 1: 1 mutually, this is notEssential; For example, all odd-numbered frame can flock together, and are and then all even frame.This can cause the alternate column of meeting driving display in the group of two separation.

The major advantage of the present embodiment is needn't switch during operation public front electrode. This is mainAdvantage is that the maximum drive voltage of available electro-optical medium is one of driver maximum voltageHalf, and every a line can only drive for 50% time. Like this, under identical maximum drive voltage,The refresh time of this display is four times of electro-optical medium switching time.

In the second embodiment of this form of the present invention, the gamma electric voltage of driver is as Fig. 5 instituteShow layout, public electrode switches between V=0 and V=Vmax. The gamma electricity of in this way arrangingPress and allow to drive icon element and odd image element with single direction simultaneously, but public electrode need to be switchedTo approaching contrary driving polarity. In addition, because this layout is about end face voltage symmetry,Therefore can cause identical voltage to be provided on odd image element or icon element to the specific input of driver.In this case, the input of algorithm is size and the symbol of desired pulse, and the utmost point of end faceProperty. If current public electrode is set corresponding to the symbol of expecting pulse, this value is exported exactly.If expect that pulse is in contrary direction, so this pixel is arranged on to end face voltage, exist like thisIn this frame, do not have electric field to be applied on this pixel.

As described in last embodiment, in the present embodiment can by with maximum drive voltage divided byThe necessary length of driving pulse is calculated in large pulse, and this value is converted into by being multiplied by display refresh ratesFrame number. Frame number must be double to illustrate that display at every turn can only be corresponding to end face in one direction againThe fact driving.

The major advantage of the second embodiment is to use the full voltage of driver, and can standCarve and drive all output. But two frames need to drive in the opposite direction. Thus, in phaseUnder same maximum drive voltage, the refresh time of this display is the switching time of electro-optical mediumTwice. Its major defect is to switch public electrode, and this may cause at electro-optical medium, and resemblesThe transistor that element electrode is connected or the less desirable voltage noise in both.

In arbitrary embodiment, gamma electric voltage is generally all distributed in the maximum of driver with linear gradientBetween voltage and end face voltage. Depend on the design of driver, can be in output in order to ensure driverOn really produce top voltage, may need one or more gamma electric voltages in end face value.

Above to making method of the present invention be suitable for for driving for the routine of LCD designReference has been made in the restriction of device. More specifically, the row driver of conventional LCD, and particularly surpass and turn roundQu Xianglie (STN) LCD (voltage that can be higher than the row driver control of other type), in officeIn one preset time, can only apply one of two voltages to drive wire, non-sensitive to polarity because Here it isWhole needs of liquid crystal material. Contrary, for driving the electro-optic displays to polar sensitive,Need less three actuator electrical voltage levels. These three required actuator voltages are with relative end face electricityPress the V-for negative driving pixel, the V+ taking relative end face voltage as positive driving pixel, andKeep the voltage that pixel is 0V at the relative end face voltage of identical show state.

But method of the present invention can realize with such conventional lcd driver, forTo provide necessary pulse to the pixel of electro-optic displays, arrange the controller that provides to oneOr more multiple row driver and relative line driver provide a suitable contact potential series.

This method has two primary variables. In the first variable, all provided pulses mustMust have+I, one of-I or 0 three values, wherein:

+I＝-(-I)＝Vapp×t_pulse

Wherein Vapp is the provided voltage on end face voltage, and t_pulseIn secondsPulse length. This variable only allows display to operate with binary system (black/white) pattern. SecondIn individual variable, the pulse providing can be from+change to-I of I, but must be Vapp/freqIntegral multiple, wherein freq is the refreshing frequency of display.

The following fact that this aspect utilization of the present invention has been pointed out, conventional lcd driver is designed toAvoid some not expect but the effect that may produce in display with frequency interval upset polarityShould. Therefore, such driver is designed to receive the polarity of self-controller or control voltage, itsCan be high or for low. In the time being shown to be a low control voltage, defeated at arbitrary given driverOutput voltage in outlet can adopt one of two outside three required voltages of possibility, analogySay V1 or V2, and in the time being shown to be a high control voltage, at arbitrary given driver output lineOn output voltage can adopt one of different in three voltages that may need two, for exampleV2 or V3. Thus, only two outside three required voltages can be sought at arbitrary special timeLocation, three whole voltages just can obtain in different time. These three required voltages conventionally canMeet following relational expression:

V2＝(V3+V1)/2

V1 can or approach logically.

In this method of the present invention, display can be scanned 2 × t_pulse× freq time. For thisThe half of a little scannings is (, for t_pulse× the scanning of freq time), the output of driver can be establishedBe set to V1 or V2, its conventionally can equal respectively-V and Vcom. Thus, in these scannings,Pixel or driving are negative, or remain on identical show state. For scanning second half,Can driver be outputted to V2 or V3, its conventionally can equal respectively Vcom and+V. ?In these scannings, pixel or drive as just, or remain on identical show state. BelowThese options of table 1 explanation are driving or maintenance shapes that how to combine to be created in either directionState; The negative driving that just drives and can obtain bright state that certainly can obtain accordingly black state is usedA kind of function of specific electro-optical medium.

Table 1 obtains the drive sequences of bi-directional drive pulse with the maintenance of STN driver

Have multiple distinct methods arrange this drive scheme two parts (, two dissimilarScanning or " frame "). For example, the frame of two types can replace. In fact when the frame replacingIn when driving in the opposite direction, if carried out with high refresh rate, electro-optical medium meeting soShow luminous and dimmed simultaneously. Optionally, all frames of a type can be at Second Type frameAny before occur; This can cause a kind of driving external behavior of two steps. Certainly other layoutAlso be fine; For example follow two or more opposite types with the frame of more a type for twoFrame. In addition,, if there is no pixel demand motive in one of both direction, can cancel so thisThe frame of polarity, 50% ground reduces driving time.

In the time that the first variable can only produce binary picture, the second variable can provide has many gray scalesThe image of level. This is by realizing in conjunction with the drive scheme of the above-mentioned pulsewidth modulation to different pixels. In this case, again to scanning of a display 2 × t_pulse× freq time, but at footIn these enough scannings, only provide driving voltage to ensure to obtain particular pixels institute to arbitrary particular pixelsThe pulse of expecting. For example, for each pixel, can record provided total pulse, whenWhen pixel reaches the pulse of its expectation, in the scanning below all, this pixel can remain on end face electricityPress. For the pixel that need to drive to be less than total scanning time, the time of drive part (, existsFor a change the show state of pixel provides the time portion of pulse, simply maintains with provided voltageThe retaining part of the show state of pixel is relative) can be distributed in total time with diverse ways.For example, whole drive parts can be set to start in beginning place of total time, or allDrive part can change in the end timing of total time and completing. As in the first variable, ifThe pulse that arbitrary time in the second variable no longer includes particular polarity need to offer arbitrary pixel,Can cancel so the scanning that this polar impulse is provided. This may mean whole pulse meeting shortening,For example,, if the maximum impulse providing with positive and negative direction is less than the maximum pulse that allows.

Take for illustrative purposes the situation of Simplification, suppose the above-mentioned gray scale for displayScheme has four gray levels, i.e. black (0 grade), dark gray (1 grade), bright gray scale (2 grades) withAnd white (3 grades). In table 2 below overview a kind of possible drive scheme of such display.

Table 2

Frame No.	1	2	3	4	5	6
							Parity	Very	Even	Very	Even	Very	Even
Conversion
							0-3	+	0	+	0	+	0
0-2	+	0	+	0	0	0
							0-1	+	0	0	0	0	0
0-0	0	0	0	0	0	0
							3-0	0	-	0	-	0	-
2-0	0	-	0	-	0	0
							1-0	0	-	0	0	0	0

Although conventionally can use in practice the more frame of more number, for convenience of description, supposeIn this drive scheme, only use six frames. These frames are alternately odd and even number. Be tending towards white conversion (,The conversion that gray level increases) only in odd-numbered frame, drive, and be tending towards black conversion (, ashThe conversion that degree level reduces) only in even frame, drive. In arbitrary frame that does not drive pixel,It remains on the voltage identical with public front electrode, at table 2, is indicated by " 0 ". For0-3 (Hei-Bai) conversion, in each odd-numbered frame, can provide one to be tending towards white in frame 1,3 and 5Pulse (, pixel capacitors is remained on to one and trends towards increasing pixel with respect to public front electrodeThe voltage of gray scale). On the other hand, for 0-2 (black in bright gray scale) conversion, only at frame 1With 3 in provide one to be tending towards white pulse, and in frame 5, do not provide pulse; This yes withMachine, for example, can in frame 1 and 5, apply one and be tending towards white pulse and do not execute in frame 3Add pulse. For 0-1 (black in dark gray) conversion, only applying one at frame 1 frame is tending towards whitePulse, and do not apply pulse at frame 3 and 5 frames; In addition, this is also random, for example can beIn frame 3, apply one and be tending towards white pulse, and do not apply pulse at frame 1 and 5 frames.

Being tending towards black conversion is to process with a kind of method that is very similar to the conversion that is tending towards accordingly white, except being tending towards black pulse, this only in the even frame of this drive scheme, applies. Believe and drive electricityThe technical staff in optical display unit field can be readily appreciated that in table 2 and not shown by description aboveThe method of the conversion going out.

Above-mentioned pulse group can be independence (stand-along) conversion between two images, or itCan be also designed for completing image conversion (as with magic lantern (slide-show) waveform)The part of pulse train.

Although emphasis has been placed on permission of the present invention above and has used as using and design together with LCDThe method of conventional driver on, but the present invention also can use driver and a kind of the using of customizationIn the driver that can accurately control grey states in electro-optic displays, and now with reference to Fig. 6 and7 introduce the realization of the no write de-lay of display.

As mentioned above, first, many electro-optical mediums are in response to a potential pulse, and this pulse canBe expressed as V timing t (or more conventional, the integration by V with respect to t), wherein V is applied toThe voltage of pixel, and t applies this voltage institute elapsed time. Thus, can be by applyingTo the modulation of the potential pulse length of display, or by executing alive modulation, or itBoth combination obtain grey states.

In the situation of the pulsewidth modulation of Active Matrix Display, available pulse width resolution ratioThe just inverse of display refresh rate. In other words, for the display of 100Hz refresh rate, pulseLength can be sub-divided into the interval of 10ms. This is because of each pixel in display in each scanningAddressing once, exactly in the time that in that a line, the selection line of pixel is activated. In all the other timesIn, described at above-mentioned WO01/07961, the voltage on pixel can be by memory capacitanceDevice maintains. Along with the response speed of electro-optical medium accelerates, with respect to the reflectance curve of timeSlope can be more and more precipitous. Thus, in order to maintain identical gray level resolution, the refreshing of displayRate must corresponding increase. The increase of refresh rate causes higher power consumption, final as expect transistor andDriver becomes like that impossible to the charging of pixel and line capacitance within the shorter and shorter time.

In yet another aspect, in voltage modulated display, pulse resolution is just by voltage levelNumber determines, and is independent of the speed of electro-optical medium. By utilizing non-linear point of electric pressureCloth can increase effective resolution, and it is the most precipitous that they concentrate on the voltage/reflectivity responses of electro-optical mediumPlace.

Accompanying drawing 6 has schematically shown in pulsewidth modulation (PWM) and voltage modulated (VM) modeBetween balance. Trunnion axis represents pulse width, and vertical axes representative voltage. As these two ginsengsThe reflectivity of the electrophoretic display device (EPD) based on particle of the function of number is expressed as one with being illustrated in demonstrationThe contour map at 1L*Cha district and interval in device reflecting brightness, wherein L* has conventional ICE'sDefinition:

L*＝116(R/R₀)^1/3-16

Wherein R is reflectivity, and R0 is the value of a standard reflectivity. (empirically find at 1L*Difference in brightness is significant just for mean value theme in two excitation tests. ) total in Fig. 6The specific electrophoretic medium based on particle using in this test of knot has as shown in the figure in maximumThe response time of the 200ms that voltage (16V) is located.

The effect of pulsewidth modulation can be determined by the segment crossing along top level separately, and individual voltage is adjustedThe effect of system is found out by the vertical edge that checks right side. Can be clear that from this segment, asIt is refreshing with 100Hz in pulsewidth modulation (PWM) pattern that fruit is used the display of this particular mediumRate drives, and can not obtain the reflection in ± 1L* so in the middle gray region of profile steepestRate. In voltage modulated (VM) pattern, obtaining reflectivity in ± 1L* can need 128 grades etc.The voltage level of spacing, with the low operation of the frame frequency to 5Hz, (certainly, supposing is provided by capacitor simultaneouslyVoltage hold facility be sufficiently high). In addition these two kinds of methods can be combined with less,Voltage level obtains same precision. In order further to reduce required voltage progression, can be by themIn the precipitous segment set in the centre of curve shown in Fig. 6 and sparse in exterior lateral area. This can be with littleThe input gamma electric voltage of number completes. In order further to reduce required voltage progression, can be byThey concentrate in favourable value. For example,, if use very little within the distributed addressing timeVoltage can not meet the grey states conversion of any expectation, so such small voltage is for realizationConversion is otiose. Select the voltage distribution of getting rid of such small voltage can make allowed voltageThere is more favourable distribution.

As noted above, because bistable electro-optic displays is for the polar sensitive of the electric field applying, instituteWith the polarity of the driving voltage that overturns in continuous frame (image) unlike being done in LCD,And frame, pixel and line upset are all unnecessary, and in fact can have the opposite effect. For example,The lcd driver with pixel upset is carried the voltage that changes polarity in the frame replacing. Like this,Only may in the frame of half, carry the pulse of suitable polarity. This is not problem in LCD, becauseLiquid crystal material is insensitive to polarity, but in bistable electro-optic displays, needs the time of twiceAddressing electro-optical medium.

Similarly, because bistable electro-optic displays is pulse transducer instead of voltage sensor, instituteWith display integral voltage error in time, this can cause the pixel of display to depart from their phaseHope the large skew of optical states. This makes to use the driver with high voltage precision to become very heavyWant recommendation ± 3mV or less tolerance.

In order to make driver can carry out with the refresh rate of 75Hz the demonstration of the monochromatic XGA of addressing (1024*768)Panel, the maximum pixel clock rate of a 60Hz of needs; Obtaining such clock frequency is to work asIn front technical merit.

As already mentioned, one of the electrophoresis based on particle and other similar bistable electro-optic displaysMajor advantage is the stability of their images, and then has an opportunity with extremely low power consumption operation display.Utilize substantially this chance, in the time that image does not change, can disable to the power supply of driver. CauseThis, driver can be designed as the in the situation that of not producing any stray voltage on output line with oneControllable mode is carried out power down. Can become one because enter and leave such " sleep " patternCommon event, so power down and the order that powers on are fast as much as possible, and will be in the use of driverOn life-span, there is minimum influence.

In addition, should have one to make the input pin that all output pins of driver are Vcom, it can beIn the situation of not power down of driver, all pixels are remained on their current optical states.

Driver of the present invention is useful, wherein in particular for driving high-resolution medium, Gao XinThe portable display of breath capacity, for example 7 inches of (178mm) diagonal XGA monochrome displays. ForIn such high resolution panel the number of required integrated circuit minimize, need to make apparatusThere is the driver of the every high number of encapsulation (for example, 324) output. Also need this driver to have oneIndividually operate in the option under one or more of other patterns and there is less output enable. CollectionThe method for optimizing that becomes circuit to be placed on display floater is that band carries encapsulation (TCP), so just needs to arrangeThe size of driver output and placement are beneficial to the use of this method.

This driver is typically used in the little voltage to 30V left and right and carrys out drive medium active matrix board.Therefore, this driver needs to drive the capacitive load of about 100PF.

In accompanying drawing 7, provide the block diagram of preferred driver of the present invention (being conventionally designated as 200). DriveDevice 200 comprises shift register 202, data register 204, data latches 206, digital mouldIntend converter (DAC) 208 and output buffer 210. This driver is different from those and conventionally usesBe that in the place that drives LCD it provides a polarity relevant to each pixel of displayPosition, and produce one in the upper and lower output of end face voltage by the control of corresponding polarity position.

In the signal description of this preferred driver table 3 below, provide:

Driver 200 operates in the following manner. First be, high next by setting (for example) DIO1Provide a starting impulse to make shift register 202 reset to an initial state. (for demonstrationTechnical staff in device actuation techniques field can be readily understood that, what provide to shift register is eachKind of DIOx input can make driver and have together with the display of varying number row to use, still forArbitrary given display only uses in these inputs, and being forever restricted to otherLow. ) now shift register will operate with the usual manner of using in LCD; At each CLK1Pulse place, has one and only have one to uprise in 162 outputs of shift register 202, otherMaintenance low level, and in the time of each CLK1 pulse position of this high level output conversion. As figure7 schematically show, and each in 162 outputs of shift register 202 is connected to numberAccording to two inputs of register 204, a strange input and an even input.

Display controller (comparison diagram 2) provides two six arteries and veins in the input of data register 204Polar signal D0POL and the D1POL of punching value D0 (0:5) and D1 (0:5) and two single positions. ?The rising edge of each clock pulses CLK1, defeated in conjunction with shift register 202 selected (high level)Go out, two seven figure places (D0POL+D0 (0:5) and D1POL+D1 (0:5)) are written to data and postIn the register of storage 204. Thus, after 162 clock pulses CLK1,324Individual seven figure places (with respect to the pulse value for complete a line in a frame demonstration) are written in data and postIn 324 registers in storage 204.

At the rising edge of each clock pulses LCK2, by these 324 seven figure places from data register 204Be sent to data latches 206. These numbers that are placed in data latches 206 are read by DAC208Get, and in a usual manner, the corresponding analogue value is placed on to the output of DAC208, and through bufferingDevice 210 is fed to the row electrode of display, there they is offered by line driver and (is not shownGo out) in the usual way select a line in pixel capacitors. But, it is pointed out that by writingEnter that to control each row electrode to the polarity position D0POL in data latches 206 or D1POL correspondingIn the polarity of Vcom, these polarity can be if the usual manner using in LCD be in adjacent columns like thisBetween electrode, change.

Fig. 8 is that one of explanation can be by the flow process of the program of the controller unit operation shown in Fig. 1 and 2Figure. This program (being generally designated as 300) is for (hereinafter having with look-up-table method of the present inventionMore detailed description) use together, wherein when each image writes or refreshes, displayAll pixels are wiped free of and addressing again.

Program starts from controller initialized " powering on " step 302, and this is that a user is defeated conventionallyThe result entering, for example user presses the power button of personal digital assistant (PDA). Step 302Also can be caused by following mode, for example, the opening of PDA box (can be by mechanical pick-up device orPhotoelectric sensor is surveyed this opening), input pen leaves the movement of its shelf on PDA, whenUser pick up PDA survey mobile, or in the time that user's hand approaches PDA, survey approach detection.Next step 304 is " reset " steps, wherein all pixel driven of display is arrivedTheir black and white state. Have been found that at least in some electro-optical mediums, right on displayIn the writing successively of image, this " flicker " of pixel is for guaranteeing that accurate grey states is mustNeed. (calculating each time continuously black and white state is one also to find conventionally at least to need 5 flickersInferior flicker), or in some cases more times. The number of times of flicker is more, in this step, spendsTime and energy are just more, simultaneously thus user can on display, see expectation image itFront necessary elapsed time is also just longer. Therefore, just wish meet write image subsequently in accuratelyGrey states supply with situation under make flicker number of times as much as possible little. Tie in reset process 304Shu Shi, all pixel of display is all at identical black or white state.

Next step is to write or " sending image " step, and its middle controller 16 was to have saidMethod is sent signal to row and column driver 22 and 24 (Fig. 1 and Fig. 2) respectively, is showing thusOn device, write the image of expectation. Because display is bistable, so once image write, noNeed to rewrite at once, and write after image thus, controller is conventionally by arranging blankingSignal (for example signal BL is set to height in Fig. 7) interrupts row and column driver to displayWrite.

Controller has entered one by step 308 now, the 310 and 312 judgement circulations that form. In stepIn rapid 308, controller 16 checks whether computer 12 (Fig. 1) asks the demonstration of a new images.If so, controller continues, and will in step 306, be written to aobvious in an erase step 314Show the image wipe of device, when thus display being turned back to reset process 304 substantially and finishing, arriveState. Controller turns back to step 304 from erase step 314, foregoing reset, and continueContinue into new image.

If there is no to be written to the new images of display in step 308, controller advances to step310, determine there when the image having kept exceedes a predetermined week on displayPhase. Known to the technical staff in Display Technique, be written to image on bistable state medium notTo keep indefinite duration, image can gradually fade away (, contrast reduce). In addition, in some classesIn the electro-optical medium of type, particularly electrophoretic medium, often can be in writing speed and the bistable state of mediumBetween balance because several hours and within several days, keep bistable medium substantially than only keeping several seconds orA few minutes, bistable medium had the longer write time. Therefore, resemble at LCD although do not needIn situation in such continuous rewriting electro-optical medium, but for the figure with good contrast is providedPicture, need to carry out refreshed image with the interval of (for example) a few minutes. Thus, in step 310Controller judges since write the time that image starts to pass by step 306 whether exceededPredetermined refresh interval, if so, controller proceeds to erase step 314 and then arrives reset process304, reset as mentioned above, and continue identical image to be rewritten on display.

(can become simultaneously and to use local and overall rewriting in the program shown in Fig. 8, as hereinafter moreDetailed description. Step 310 whether needs part or totally rewrites if like this, will change decision into.If in the program of conversion, judge that in step 310 place program predetermined time do not expire, generalDo not operate. If but the scheduled time arrive, step 310 is the wiping of calling graph picture at once notRemove and rewrite, but an instruction is only set generally to the renewal ratio of next image partlyMore effective mark (term aspect computer conventionally). Program arrives step in the next time306, certification mark, if be provided with this mark, the overall rewriting to image and then remove thisMark. But if this mark is not set, be with effect to the Local Gravity And of image. )

If judge that in step 310 refresh interval does not also exceed, controller advances to step 312,Judge whether there to close the time of display and/or image source. For at mancarried deviceMiddle preservation energy, controller can not allow a single image to refresh down indefinitely, as Fig. 8Shown in can a prolongation without the operation cycle after terminator. Therefore, control in step 310Device judge the image new since the rewriting of front image (instead of) be written to display itWhether rear predetermined " closing " cycle (being greater than refresh interval above-mentioned) expires, asFruit is, as 314 represented, program stops. Step 314 can comprise the power down of image source., after such program stops, user can also access the slowly image of desalination on display.Close the cycle if also do not exceed this, controller turns back to step 308 from step 312.

Method by way of example is only introduced may for carrying out the various of look-up-table method of the present inventionWaveform. But, first will introduce the general provisions of some waveforms used in the present invention.

The waveform that shows the bistable display of foregoing storage effect can be divided into main twoClass, i.e. offset-type and non-compensated. In offset-type waveform, consider arbitrary the depositing in pixelStorage effect is carried out fine adjustment to whole pulses. For example, an experience gray level 1-3-4-2The pixel of series conversion can receive one compared with the pixel of experience 1-2-4-2 conversion slightlyThe different pulses for 4-2 conversion. Such impulse compensation can be by regulating impulse length,Voltage or the V (t) by pulse distribute other change to carry out. In non-compensated waveform,Any in the behave of (being different from original state) of front status information without any considering. In non-compensationIn waveform, the pixel of all experience 2-4 conversion can be received identical pulse. In order to make non-benefitRepay waveform and successfully work, must meet one of two conditions. One is that electro-optical medium switches behaviour at itPerformance storage effect not in work, or any the depositing in pixel must be effectively eliminated in each conversionStorage effect.

Generally, non-compensation waveform is best suited for the system that can only carry out thick pulse resolution. It is for example toolThere is the display of three grades of drivers, or only have the display of 2-3 position voltage conversion capabilities. CompensationWaveform needs accurate pulse regulation, with such system be impossible. Obviously, when rough arteries and veinsWhen flushing system is preferably limited to non-compensation waveform, the system with Precision Pulse adjusting can realize thisThe waveform of two types.

The simplest non-compensation waveform is 1 normal image stream (1 GIF). In 1 GIF, aobviousShow that conversion arrives the next one reposefully from a pure black white image. Transformation rule to this sequence canTo carry out as follows simply: black if image is changed to from white cut, pulse I is provided. If its fromBlackly be switched to whitely, provide the pulse of opposite polarity ,-I. If image keeps identical state,Do not provide pulse to pixel. As specified above, pulse polarity is for the polarity of voltage of systemMapping can rely on the respective function (function) of material.

The another kind of non-compensation waveform that can produce gray level image is non-offset-type n prepulsing magic lantern (n-PPSS). This non-compensation magic lantern (slideshow) waveform has three essential parts. First, wipePixel to one unique optical states is normally white or black. Then, by pixel backward orBetween two optical states, drive forward, conventionally still white and black. Finally, pixel is soughtLocation to one can be the new optical states of grey states more than. Finally (or writing) pulseBe called as addressing pulse, and other pulse (the first (or wiping) pulse and centre (or blanking)Pulse) be collectively referred to as prepulsing. Such waveform can be described with reference to Fig. 9 and 10 below.

Prepulsing magic lantern waveform can be divided into two citation forms, have odd number prepulsing and have an idolNumber prepulsing. For the situation of odd number prepulsing, erasing pulse meeting equates with relative in pulseThe contrary polarity of direct preceding write pulse (or referring to Fig. 9 and following description). Change speechIt, if pixel from the black ash that is written to, erasing pulse meeting makes pixel turn back to black state. At even numberIn the situation of prepulsing, erasing pulse meeting have with the identical polarity of direct preceding write pulse andAnd it is required to equal complete conversion from black to white in the pulse sum of front write pulse and erasing pulsePulse. In other words, if pixel writes from black in the situation of even number prepulsing, so necessaryBe erased to white.

After erasing pulse, waveform comprises zero or even number blanking pulse. These blanking pulses are commonBe to equate but opposite polarity pulse, being arranged to first pulse is the polarity contrary with erasing pulse.These pulses be generally equal to whole black-white pulse, but this is not necessary condition. Also can only needPulse equates but opposite polarity pulse-can be the paired very large change linking together havingThe pulse of changing ,+I ,-I ,+0.1I ,-0.1I ,+4I ,-4I.

The pulse finally providing is write pulse. The optical states based on desired only to the selection of this pulse(do not rely on current state, or any at front state). Generally, this pulse meeting is with grey states valueMonotone increasing or minimizing, but this is optional. Because this waveform is to be in particular rough pulse systemUse and design, thus generally can be included in peanut to the selection of write pulse can energy impulseIn selection one group expect the mapping of grey states, for example in 9 kinds of pulses that may apply 4Individual grey states.

The inspection of n the prepulsing magic lantern waveform of non-compensation of dual numbers or odd number form can demonstrate to be writeEnter pulse always from identical direction, from black or from vain. This is the important of this waveformFeature. Because the principle of non-compensation waveform is cannot be for guaranteeing that pixel reaches identical optical statesPaired pulses length compensates accurately, so can not look to when (black from contrary extreme optical stateWhile setting about or in vain), reach consistent optical states. Therefore, for can be designated as " from black " and, there are two kinds of possible polarity in one of these forms of " making clear one's meaning and position ".

A major defect of this type waveforms is to have between image the optics greatly amplifyingFlicker. As with reference to Fig. 9 and 10 hereinafter as described in, can by the superframe time be half pixel becomeChange renewal order, and improve with high-resolution interlacing scan pixel. Possible pattern comprises oftenEvery (every) other row, every other row, or inspection plate pattern. Note, this does not also mean thatUse relative polarity, " from black " is to " confession ", because this can cause at adjacent image pointNot mating of upper gray scale. As an alternative, can be by with to half pixel (, first group of pixelComplete erasing pulse, then second group of pixel starts erasing pulse and first group of pixel starts first disappearsBlind vein punching) postpone with one " superframe " (one equals the frame group of the maximum length of Hei-Bai renewal)More NEW BEGINNING is realized. Consider synchronously, this need to be for increasing a superframe total update time.

First can find out that Perfected process of the present invention can be called " common grayscale image flow ", wherein controlDevice processed arranges writing of each image, and each like this pixel can be directly from its initial grey levels conversionTo its final gray level. But in fact, common grayscale image flow faces from the accumulation of errorProblem. Due to following practical work, for example, by driver, the variation of the production of electro-optical medium on thicknessOn Voltage-output, be difficult to Deng causing the variation avoided, be applied to the arteries and veins in arbitrary given gradation conversionNeed to there is difference in punching certainty and theory. Suppose that the mean error in every kind of conversion is expressed as demonstrationDevice in the difference terms of theoretical and actual frame reflectivity is ± 0.2L*. Through 100 conversions continuously, resembleElement can demonstrate a mean deviation from their desirable 2L* states; This skew is at someIn the image of type, be obvious for general viewers. For fear of this problem, need handleThe drive scheme using is in the present invention arranged to through an extreme optical state (black or white)Before, arbitrary given pixel can only experience the gradation conversion of a predetermined maximum number. ExistingAfter having applied certain pulses on electro-optical medium, these extreme optical state are as " fence ", and medium is notCan become more black or whiter. Thus, the always conversion next time from extreme optical state can be fromThe optical states of accurately knowing starts, and has effectively compensated for any error in front accumulation. By extremelyOptical states will be described below the minimized various technology of the optical effect of such one section of pixel.

First, there is black (0 grade) referring now to one, dull gray (1 grade), bright ash (2 grades)With white (3 grades) optical states, use pulse modulation technology and as the conversion as shown in following table 4Question blank is realized simple two gray scale systems of conversion, introduces usefully in the present invention simply to driveMoving scheme.

Table 4

Conversion	Pulse	Conversion	Pulse
				0-0	0	0-0	0
0-1	n	1-0	-n
				0-2	2n	2-0	-2n
0-3	3n	3-0	-3n

Wherein n is a number according to particular display, and-n represents that one has identical with pulse nBut the pulse of length opposite polarity. Also further suppose the end of the reset pulse 304 in Fig. 8End, all pixels of display are all black (0 grades). Therefore, as described below, all conversions allOccur by a black state in centre, only have those to this grey states or from this grey statesConversion be effective. Like this, required question blank size obviously reduces, and obviously foundation reducesThe scale factor of question blank size can increase along with the number of display gray level.

Fig. 9 has shown a pixel conversion relevant with the drive scheme of Fig. 8. In reset process 304Beginning, pixel is in a certain random greyscale. In reset process 304, pixel is alternately drivenMove three black states and two white states in centre, finish at its black state. Then at 306 places toPixel writes the gray level suitable for the first image, supposes it is 1 grade. Show in this identical imageThis pixel keeps a period of time in this level during this time; Display cycle for convenience of explanation in Fig. 9Length greatly reduced. Sometimes a new images need to write, and in this, pixel is being wipedTurn back to black (0 grade), then warp in the second reset process of being appointed as 304 ' except in step 308Cross and replace 6 times white and black reset pulses, in this reset process 304 ' end, pixel like thisThrough having turned back to black state. Finally, in the second write state of being appointed as 306 ', write to pixelEnter one for the suitable gray level of the second image, suppose it is 2 grades.

That yes is possible for many different drive scheme in Fig. 9. Figure 10 illustrates one hasWith variation. In the step 304 shown in Figure 10,306 with 308 the same with in Fig. 9. ButBe, in step 304 ' in, used 5 reset pulses (obviously also can use one differentOdd number impulse), like this in step 304 ' end, pixel is at white state (3 grades), and secondIn write step 306 ', pixel write be from white state realization instead of from resembling among Fig. 9In described black state, realize. Consecutive image just replaces black state and the white state from pixel like thisWrite.

In the variation of the another drive scheme shown in Fig. 9 and 10, erase step 308 is not according to drivingInvoluntary movements element black but white (3 grades) realize. Then in reset process under white state even numberIndividual reset pulse is added to pixel end, writes the second image from white state. As the driving side at Figure 10Case, in this programme, alternately black state and the white state from pixel writes continuous image.

Be appreciated that in all above schemes, according to the characteristic of the electro-optical medium using, reset arteries and veinsNumber and the duration of punching can change. Similarly, can use voltage modulated instead of arteries and veinsWide modulation changes the pulse that is applied to pixel.

The black lightning showing on display in the reset process of above-mentioned drive scheme and dodging for user in vainIt is visible that yes, and may not like for a lot of users. In order to reduce this resetThe visual effect of step, can be divided into the pixel of display two (or more) group easily, andProvide dissimilar reset pulse to different groups. More particularly, if need to use reset arteries and veinsPunching drive any given black and white between the pixel that replaces, can easily pixel be divided at leastTwo groups, and arrange drive scheme to make one group of pixel driving for white another group driving is simultaneously for black.The spatial distribution that this providing is two groups be meticulously select and also pixel all enough little, user's experienceReset process is just as the gray scale interval on display (what preferably some were slight flashes), suchGray scale interval induces one to detest unlike a series of black and white flicker conventionally.

For example, in such " two groups of resets " step of a kind of form, the pixel on odd column canTo be assigned as " very " group, and pixel in even column is assigned to second " idol " group.Then odd number pixel can use at the drive scheme shown in Fig. 9, and even number pixel can useThe mutation of this drive scheme, wherein in erase step, pixel is not to be driven to black state but whiteState. Then these two groups of pixels all can experience even number reset pulse in reset process 304 ', thisSample can separate 180 degree phase places substantially for this reset pulse of two groups, and display is whole multipleIn the step of position, be shown as ash. Finally, in step 306 ' the second image during writing, odd number pixelFrom the black end-state that is driven into them, and even number pixel is from being driven in vain their end-state.In order to ensure (and like this resetting with identical method each pixel that resets in the very long timeMethod does not cause any noise on display), between consecutive image, switch this drive scheme for controlDevice processed is favourable, and in the time that a series of new images are written to display, each pixel is to hand over like thisFor be written to its end-state from black and white state.

Obviously, can use and form first group and pixel in even number line by the pixel in odd-numbered line and formThe similar scheme of second group. In another similar drive scheme, first group be included in odd column andPixel in odd-numbered line, and even column and even number line, and second group be included in odd column and even numberPixel in row, and even column and odd-numbered line, press chessboard arranged in form for such two groups.

Replace or except pixel is divided into two groups and be arranged in reset pulse in one group and another group inDiffer 180 degree phase places, pixel can be divided into use distinct in quantity and pulse frequencyThe group of different reset pulses. For example, one group of 6 pulse reset that can use as shown in Figure 9Sequence, and second group can use 12 pulses of similar doubled frequency. A more accurate sideIn case, pixel can be divided into four groups, and but first and second groups use 6 pulse schemes mutual phaseDiffer from 180 degree phase places, and third and fourth group uses 12 pulse schemes but differs each other 180 degree phasesPosition.

Be illustrated as another program of the adverse effect that reduces reset process now with reference to Figure 11 A and 11B.In this scheme, pixel is divided into two groups again, by the first (idol of drive scheme shown in Figure 11 ANumber) group and second (odd number) group of pressing the drive scheme shown in Figure 11 B. Equally in this scheme,Be divided into first group of the contiguous dull gray level against black level in all gray levels of black and white centre, withAnd second group of the contiguous bright ash level against white level, be the same for two groups of this point-scores of pixel.Expect but not necessarily, in these two groups, there is the gray level of similar number; If there is odd numberGray level, intergrade can Random assignment be given arbitrary group so. For convenience of explanation, Figure 11 A and11B illustrates that this drive scheme provides 8 grades of gray scales to show, be appointed as 0 (black) to 7 (in vain) etc.Level; Gray level 1,2 and 3 is dull gray levels, and gray level 4,5 and 6 is bright ash levels.

In the drive scheme of Figure 11 A and 11B, control the conversion between gray scale according to following rule:

(a) first, even number set pixel, in the conversion to dull gray level, the final pulse providing is totalBeing one is tending towards white pulse (, one has and tends to pixel from its black state to itThe pulse of the polarity of white state-driven), on the contrary in the conversion to bright ash level, provideFinal pulse always one be tending towards black pulse.

(b) secondly, odd number group pixel, in the conversion to dull gray level, the final pulse providing is totalBe one and be tending towards black pulse, and in the conversion to bright ash level, the final pulse providingAlways one is tending towards white pulse.

(c), in all situations, when obtaining after white state, being tending towards black pulse can only existAfter being tending towards white pulse, and when obtaining after black state, being tending towards white pulse can be onlyAfter being tending towards black pulse.

(d) even number pixel not can by one single be tending towards black pulse be driven into from a dull gray level black,Odd number pixel can not use one to be singlely tending towards white pulse from bright ash level in vain yet. (aobviousSo, in two kinds of situations, can only use one to be finally tending towards white pulse and to obtain white state,Also can only finally be tending towards black pulse with one and obtain black state. )

In three continuous pulses of application permission use of these rules, realize gray scale for one of maximumBetween conversion. For example, Figure 11 A shows through the conversion from black (0 grade) to gray level 1An even number pixel. This be with independent be designated as 1102 be tending towards white pulse (certainly at Figure 11 AIn be expressed as a positive slope) obtain. Then, pixel driving is arrived to gray level 3. Due toGray level 3 is dull gray levels, with good grounds rule (a) it must be tending towards white arteries and veins by oneBring realization, and 1 grade thus/3 grades conversions can independent be tending towards white pulse 1104 by oneControl, it has a pulse difference with pulse 1102.

Now pixel driving is arrived to gray level 6. Because this is a bright gray level, according to rule(a) it must be tending towards black pulse by one and realizes. Therefore, rule (a) and (c) answerWith being realized by two pulse trains the conversion of 3 grades/6 grades, one is arrived pixel drivingFirst of (7 grades) is tending towards white pulse 1106 in vain, and and then one expires pixel from 7 grades of drivings6 grades one second who hopes is tending towards black pulse 1108.

Then pixel driving is arrived to gray level 4. Because this is a bright gray level, according to before oneVery similarly theoretical for 1 grade/3 grades of conversions described in face, independent is tending towards black by onePulse 1110 realizes the conversion of 6 grades/4 grades. Ensuing conversion is to 3 grades. Because this isA dull gray level, according to a foregoing very similarly theory for 3 grades/6 grades of conversions,Controlled the conversion of 4 grades/3 grades by two pulse trains, one is arrived black (0 pixel drivingLevel) first be tending towards black pulse 1112, and then one is driven into 3 of expectation pixel from 0 gradeOne second of level is tending towards white pulse 1114.

The conversion from 3 grades to 1 grade in the final conversion shown in Figure 11 A. Because this is oneDull gray level, according to rule (a), it must be tending towards white pulse by one and realizes. Therefore, applicationRule (a) and (c), must control 3 grades/1 grade conversion, this arteries and veins by a three-pulse sequenceRushing sequence comprises one pixel driving first is tending towards to white pulse 1116, to white (7 grades)Individual by pixel driving to black (0 grade) second be tending towards black pulse 1118, and one by pixelExpect that from black being driven into the 3rd of 1 grade of state is tending towards white pulse 1120.

Figure 11 B show that odd number pixel realizes as the even number pixel in Figure 11 A 0The sequence of-1-3-6-4-3-1 grey states. But, can see pulse order usedRow are very different. Rule (b) need to be tending towards black pulse by one and realize a dull gray1 grade of level. Therefore, 0-1 conversion be by one by pixel driving first being tending towards to (7 grades) in vainWhite pulse 1122, and then one is driven into the black arteries and veins that is tending towards of 1 grade of expectation by pixel from 7 gradesPunching 1124 realizes. 1-3 conversion needs a three-pulse sequence, and one is arrived black by pixel driving(0 grade) first be tending towards 1126, one of black pulses by pixel driving to white (7 grades) theTwo are tending towards white pulse, and one is driven into 3 grades of expectation the 3rd be tending towards by pixel from 7 gradesBlack pulse 1130. Ensuing conversion is to being 6 grades of bright ash level, according to rule (b) thisBe to be tending towards white pulse by one to realize, 3 grades/6 grades conversions are to comprise pixel by oneBe driven into black (0 grade) be tending towards black pulse 1132 and one by pixel driving to 6 grades that expectTwo pulse trains that are tending towards white pulse 1134 realize. 6 grades/4 grades conversions are by three arteries and veinsRush that sequence realizes, i.e. a white pulse 1136 that is tending towards in vain (7 grades) by pixel driving,A black pulse 1138 that is tending towards to black (0 grade) by pixel driving, and one driven pixelThat moves 4 grades of expecting is tending towards white pulse 1140. 4 grades/3 grades conversions be by one comprise byPixel driving is to the white pulse 1142 that is tending towards of white (7 grades), and and then one expires pixel drivingTwo pulse trains that are tending towards black pulse 1144 of 3 grades of hoping realize. Finally, 3 grades/1Level conversion is to be realized by an independent black pulse 1146 that is tending towards.

Can find out that from Figure 11 A and 11B this drive scheme guarantees that each pixel is along one " sawtooth "Shape and going, is not wherein changing in nyctitropic situation (although obviously pixel can be in arbitrary middle grayA static short or long cycle of level) each pixel is transformed into whitely from black, and do not changing subsequentlyBlack from being transformed in vain in the situation of direction. Thus, rule (c) above and (d) can by underThe single rule (e) of face replaces:

(e) once pixel by the pulse of a single polarity from an extreme optical state (,White or black) drive to contrary extreme optical state, arrive foregoing phase at it soBefore anti-extreme optical state, pixel no longer receives the pulse of opposite polarity.

This drive scheme guarantees that the maximum only experience of a pixel equal (N-1)/2 time number object and turn thusChange, wherein N is being driven into a number of grayscale levels before extreme optical state; This has preventedSlight errors in each conversion is (for example, in the voltage being provided by driver unavoidable littleFluctuation causes) the serial distortion that is ad infinitum gathered in a gray level image is obvious for observerDegree. In addition, this drive scheme being designed to even number and odd number pixel always arrives the other way aroundGiven intermediate grey scales, that is, the final pulse in sequence be in one case tending towards white andBe tending towards in another case black. If keep the even number of basic equal amount with strange oneThe effective coverage of the display of number pixel is written to a single gray level, so " rightabout "Characteristic can make the flicker in this region minimize.

In two discrete groups, drive the drive scheme of pixel for other, for above described similarlyReason, in the time of the sawtooth drive scheme of execution graph 11A and 11B, concentrate one's energy by even number andOdd number group arranges pixel. This arrangement need to guarantee that on display, want in any adjacent region substantiallyKeep the odd and even number pixel of basic equal number, the full-size of phase adjacent image point piece on the same groupWant the enough little general viewers that makes to offer an explanation easily. As mentioned above, arrange two with checker board patternIndividual group of pixels can meet these requirements. Random screen technology also can be for the arrangement of two groups of pixels.But in sawtooth drive scheme, the use of checker board pattern can be tending towards increasing the power consumption of display.In arbitrary given row in such pattern, adjacent image point can belong to contrary group, and allPixel all stands in the adjacent area of basic size of same grey level transition (general case),In arbitrary preset time, adjacent image point is tending towards needing the pulse of opposite polarity. When writing, each is newRow time, provide the pulse of opposite polarity need to be to the row of display to continuous pixel in arbitrary row(source) electrode discharge and recharging. Drive the technical staff in Active Matrix Display field all to knowRoad, the electric discharge of row electrode and to recharge be a principal element of power consumption for displays. Therefore, chessboardDistribution makes the power consumption of display be tending towards increasing.

Power consumption and expectation avoid large phase on the same group between the adjacent area of pixel reasonably compromise be by oftenPixel in group is distributed into rectangle, and the pixel in this rectangle is all only several along this row continuity in same columnIndividual pixel. With such arrangement, in the time that overwritten area has identical gray level, only have and work as from oneWhen individual rectangle is switched to another rectangle, just can need the electric discharge of row electrode and recharge. Desirable squareShape is 1 × 4 pixel, and the rectangle being arranged in adjacent columns can not finish in same a line, that is,Rectangle in adjacent columns can have different " phase places ". In each row, rectangle can to the distribution of phase placeMethod with random or circulation realizes.

A benefit at the sawtooth drive scheme shown in Figure 11 A and 11B is, as displayA part for whole updating, any monochromatic areas of image can be simply with one black to white orUpgrade to black Sing plus in vain. The maximum time of spending for rewriteeing such monochromatic areasBe rewrite need the half of the maximum time of transition region between gray scale, the use of this feature be conducive to asThe character of user's input, the quick renewal of the characteristics of image such as drop-down menu. Controller can check figurePicture upgrades the conversion whether needing between any gray scale; If do not needed, need the image-region rewriteeingCan with quick monochrome more new model rewrite. Thus, user can have input wordSymbol, the quick renewal of other of drop-down menu and display and user interaction features, itself and common ashSlow the renewal seamlessly of degree image coordinates.

Described at common pending application sequence number 09/561424 and 09/520743 above,In a lot of electro-optical mediums, the particularly electrophoretic medium based on particle, for driving such mediumDirect current (DC) balance that drive scheme has in whole expanded period meaning is desirable, passes throughThe algebraical sum of the electric current of particular pixels should be zero or approach as far as possible zero, drive scheme of the present inventionDesign to be devoted to this standard. More specifically, the question blank using in the present invention will designFor making to start or end at any conversion order of an extreme optical state (black or white) of pixelRow should be DC balances. According to mentioned above, can first find out due to this pulse, so byIt is substantially constant between this arbitrary specific gray scale by pixel, changing required electric current, so like thisDC balance may not realize. But this is just genuine for first approximation,Empirically find, at least in the situation of the electrophoretic medium based on particle, (and other electric light is situated betweenIn the situation of matter, be genuine equally), (for example) provides the 50ms pulse at 5 intervals to pixelAn effect and 250ms pulse different of identical voltage is provided to pixel. Therefore, beIn electric current to given conversion and by pixel, exist some flexible, this flexible can for participate inThe acquisition of DC balance. For example, the question blank using in the present invention can will be used for given conversionMultiple pulses together with being stored by each the total current value providing in these pulses, controlDevice can be each pixel keep one for storage from certain in the front time (for example,, since by pixelMaintaining black state rises) work the register of pulse algebraical sum that is provided to pixel. When specific oneWhen pixel is driven into black state from white or grey states, controller can check relevant to this pixelRegister, determines the whole conversion sequence from original black state to black state on the horizonThe electric current that DC balance is required, and select to store for white/ash to required some of black conversionOne of pulse, any in them can accurately be reduced to zero by corresponding registers, or at least subtractsIt is little that to as far as possible little residual value, (wherein corresponding registers can keep this residual value and in next one conversionBe added on provided electric current). The application repeatedly that can find out this process can obtain eachThe accurate long-term DC balance of pixel.

It should be noted that at the sawtooth drive scheme shown in Figure 11 A and 11B and be very suitable for using thisThe DC balance technology of sample, because this drive scheme is guaranteed at any given pixel through black statePass through continuously between can only be through the conversion of effective quantity, and actual in the conversion of its halfOn have on an average a pixel can pass through black state.

By using part instead of overall renewal can further reduce harmful effect of reset processShould, by only rewrite the part only changing in display between consecutive image, can be in " part "The part that on the basis of region or one by one pixel, selection will rewrite. For example,, when for example at explanation machineThe figure of component movement or the figure for accident reconstruction in tool equipment, be not difficult find wherein thanThe a series of images that less object moves with respect to larger static background. In order to use part moreNewly, controller need to be compared final image and initial pictures determine which district between two figureTerritory is different and then need to rewrite. Controller can be determined one or more regional area, is generallyThere is the rectangular area that will upgrade pixel of preserving with the limit of pixel grillages row, or can be only reallyThe fixed independently pixel that needs renewal. Arbitrary drive scheme of having described thus can be for only moreThe regional area that new definite conduct need to rewrite or independently pixel. Such local updating schemeCan fully reduce the power consumption of display.

Can change above-mentioned driving with several different methods according to the feature of certain electric optical display unit usedMoving scheme. For example, can in above-mentioned drive scheme, save in some cases many reset process.For example,, if electro-optical medium used (, writes the gray level of pixel for very macrocyclic bistable stateOnly change with the very slow time), and for the pixel in its initial grey states with thisThe required pulse change of the cycle particular conversion of carrying out is little, and question blank can not be arranged to and returnsDirectly realize the conversion between grey states to the intervention of black or white state, through week substantiallyAfter phase, only when pixel can cause and work as from " skew " gradually of their nominal gray levelWhen the appreciable error of front image, just carry out the reset of display. Thus, for example, if user incite somebody to action thisThe display of invention is as electronic book reader, and before the reset that needs display, it can showShow the information of many screens, empirically, have been found that and use suitable waveform and driver, at needCan show before resetting as the information more than 1000 screens, so in fact conventionally to electronic chartBetween the read period of book reader, can not need to reset.

The personnel in Display Technique field are easy to find out that isolated system of the present invention can be at different barsUnder part for providing with many different drive schemes. For example,, due to shown in Fig. 9 and 10In drive scheme, reset pulse consumes very little part in display total power consumption, thus can withThe first drive scheme of frequency interval reset display comes together to provide controller, makes like this gray scale mistakePoor minimizing, and only with the alternative plan of longer interval reset display, allowed soLarge error has still reduced power consumption. Can manually or rely on external parameter to be realized two kinds of sidesSwitching between case; For example,, if display is as portable computer, when computer is on main power sourceWhen operation, can use the first drive scheme, and passable in the time that computer moves on internal cell power supplyUse alternative plan.

According to noted earlier, can find out and the invention provides one for electro-optic displays operation controlThe driver of system, it is very suitable for bistable electro phoretic display based on particle and similar displayFeature.

According to noted earlier, can find out and the invention provides a kind of electro-optic displays operation controlledMethod and controller, its allow do not need whole display with frequency interval to its extremityThe accurate control of gray scale in the situation of the flicker of inconvenience. The present invention is also reducing the same of power consumption for displaysTime, allow the accurate control of display regardless of the variation of temperature and its operating time. Due to controlDevice can use available parts commercially to form, so can realize at an easy rate these advantages.

In residual voltage method of the present invention, expect to realize residual by high impedance voltage measuring apparatusThe measurement of remaining voltage, for example a kind of metal-oxide semiconductor (MOS) (MOS) comparator. When display isA kind of have little pixel, for example per inch 100 point (DPI) matrix displays, wherein each an elephantElement has 10^-4Square inch or about 6 × 10mm²Area, when the electricity of so single pixelResistance arrives 10¹²When the quantitative value of ohm, comparator need to have extremely low input current. But, closeSuitable comparator is easy to commercially obtain; For example,, as thering is the only input for about 20pAThe INA111 chip of the Texas Instrument of electric current is suitable. (technical, this integrated circuit is onePlant instrumentation amplifier, if but its output enters a Schmidt trigger, and it can be used as oneMoney comparator uses. ) for the display with large single pixel, for example large for what indicateDirectly driving display (specifying below), each pixel may have the region of several square centimeters,Be not very high to the requirement of comparator, all business FET input comparators can make substantiallyWith, for example, from the LF311 comparator of National Semiconductor.

Be easy to find out for the personnel in electronic display technology field, for expense and other reason,The electronic console of large-scale production can have the driving of special IC (ASIC) form conventionallyDevice, in such display, comparator can provide as a part of ASIC conventionally.Although this approach can need to provide the feedback circuit in ASIC, this has makes ASIC'sPower supply and oscillating part less advantage more simply and on area. If need 3 grades of normal imageStream driver, this method can also make the drive part of ASIC simpler and less on area.Thus, this method can reduce the cost of ASIC conventionally.

Easily, use one that driving voltage can be provided, make pixel electrical short or unsteady drivingMoving device provides driving pulse. When using such driver, realizing DC balance correctionOn each addressing period, pixel is addressed, and then electrical short floats. (term as used herein" addressing period " conventional sense in electro-optic displays technology refers on display from the first figurePicture changes to required total cycle of the second image. As noted above, because electrophoretic display device (EPD) is lowerBe generally tens to the switch speeds of the hundreds of millisecond order of magnitude, an independent addressing period can wrapDraw together the scanning of many complete demonstrations. ) after of short duration time delay, comparator passes through for measuringThe residual voltage of pixel, and determine on symbol it is just or negative. If residual voltage is being for just, thatThe cycle that controller can be in next addressing period extends negative addressing pulse a little (or slightlyIts voltage of micro-increase). If but residual voltage is negative, controller can be in next addressing soIn cycle, extend a little the cycle (or increasing a little its voltage) of positive addressing voltage pulse.

Thus, residual voltage method of the present invention is placed on electro-optical medium a kind of feedback circulation of switching regulatorJust, by regulate the length of addressing pulse by residual voltage towards zero driving. When residual voltage approaches1 o'clock, media table revealed desirable performance and the life-span of raising. Especially, use of the present invention is permittedPermitted to improve the control to gray scale. As noted, seen and to have obtained in electro-optic displaysGray level is one gray level and the pulse that provides is provided, and display is at the function of front state.Believe this " history " effect in (although the present invention is not subject to this restriction of believing) gray levelOne of reason be that residual voltage acts on the electric field that electro-optical medium experiences; Affect medium stateActual electric field is the virtual voltage sum being applied by electrode and residual voltage. Thus, according to thisThe bright control to residual voltage has guaranteed that the electric field that experienced by electro-optical medium is accurately corresponding to through electrodeThe voltage providing, allows to improve the control of gray scale thus.

Residual voltage method of the present invention is particularly useful in the display of so-called " directly driving " type,This display is divided into each a series of pixels that separate mesh electrode is provided, and this display further comprisesFor the independent switching device shifter of controlling the voltage that is applied to each separate mesh electrode. Direct driving like thisDisplay is useful for the demonstration of the limited character group of text or other for example many numerals, andAnd especially in aforementioned International Publication No. 00/05704, be described. But,Residual voltage method of the present invention can also be used for the display of other type, for example, have transistor squareThe Active Matrix Display of battle array, wherein each pixel of at least one transistor and display is connected.The gate line of the thin film transistor (TFT) (TFT) of the driving using in such Active Matrix Display willPixel capacitors is connected to source electrode. Residual voltage is compared and is less than the grid voltage (absolute value of residual voltageGenerally can not exceed 0.5V), therefore gate drive voltage conducting TFT all the time. Then source electrode line canThink that electricity floats, and be connected to MOS comparator, allow thus to read the every of Active Matrix DisplayThe residual voltage of individual independent pixel.

Although it should be noted that residual voltage on the pixel of electrophoretic display device (EPD) can with flow throughThe degree of the electric current of the pixel of DC balance closely connects, but zero residual voltage is notMust mean desirable DC balance. But from practical point of view, this has no difference, because ofFor be residual voltage instead of DC balance history to the adverse effect of pointing out at this be responsible for.

Be easy to find out for the personnel in Display Technique field, due to residual voltage method of the present inventionObject is to reduce residual voltage and direct current imbalance, so this method needn't be sought the each of displayLocation is used in the cycle, and it is to provide to prevent to form for a long time in particular pixels with suitable frequencyDirect current imbalance. For example,, if one need to be used with interval " refreshing " or " blanking "The display of pulse, so refresh or blanking pulse in all pixels be driven to identical aobviousShowing state, normally a kind of extreme display state (or, more generally, can first will ownPixel driving one of to extreme display state, then arrive again another extreme display state),This method of invention can be only refresh or blanking pulse in use.

Although residual voltage method of the present invention has been carried out in the application of encapsulated electrophoretic displayDescription roughly, but this method also can be for non-encapsulated electrophoretic display, and other typeDisplay, for example show the electrochromic display device (ECD) of residual voltage.

Described in above, can find out that residual voltage method of the present invention provides a kind of for driving electricityThe method of swimming and other electro-optic displays, it is in the display service life that increase is provided, enhancingWhen action pane and long-term display optical performance, reduce the pixel direct current for guaranteeing displayThe expense of balance equipment needed thereby.

Claims

1. drive a method for bistable electro-optic displays, described display has at least one toolHave the pixel of two extreme optical state, described method comprises:

(a) described pixel is urged to a utmost point different from described initial grey levels from initial grey levelsEnd optical states; And

(b) described pixel is urged to and a described extreme optical from a described extreme optical stateThe final gray level that state is different,

Wherein said display is electrophoretic display device (EPD), and wherein said electro-optic displays is based on particleElectrophoretic display device (EPD), wherein multiple charged particles move through suspension under the impact of electric field.

According to the process of claim 1 wherein step (b) by by described pixel from described oneIndividual extreme optical state be driven into relative extreme optical state and thereafter by described pixel driving toWhole gray level and realizing.

According to the process of claim 1 wherein step (b) by by described pixel from a utmost pointEnd optical states is driven into relative extreme optical state, and described in thereafter described pixel driving being returnedDescribed in an extreme optical state and its rear drive, pixel is realized to described final gray level.

4. be multiplely divided into first and second according to the process of claim 1 wherein that described display comprisesThe pixel of group, and wherein, in step (a), the pixel of first group is driven to an extreme pathState and second group of pixel are driven to relative extreme optical state.

5. basis the process of claim 1 wherein that described pixel has at least 4 gray levels, that is,White extreme optical state, light gray optical states, the dark-grey optics shape darker than described light gray optical statesState, and black extreme optical state, and wherein perform step (b) so that proper described final ashDegree level is shallow or when dark-grey optical states, to specifying the last driving pulse of gray level always sameIn direction.

6. according to the method for claim 5, wherein said display comprises and is divided into first and second groupsMultiple pixels, and wherein perform step (b) so that proper final gray level is shallow or dark-grey optics shapeWhen state, for the pixel of described first and second groups, be in phase to the last driving pulse of specifying gray levelIn anti-direction.

7. according to the method for claim 5, wherein have and be tending towards institute to the last driving pulse of dark-grey levelState the polarity that pixel drives to its white extreme optical state from its black, and to the rear-guard of shallow gray levelArtery rushes to have and is tending towards the polarity from its white to its black extreme optical state driving by described pixel.

8. according to the method for claim 5, wherein have and be tending towards described to the last driving pulse of dark-grey levelThe polarity that pixel drives to its black extreme optical state from its white, the while is to the last driving of light gray levelPulse has the polarity that described pixel is driven to its white extreme optical state from its black.

Once according to the process of claim 1 wherein driving pulse setting is made describedPixel drives to contrary extreme optical state from an extreme optical state by the pulse of a polarityWhen moving, described pixel does not receive the driving pulse of opposite polarity until it has reached relative extreme opticalState.

10. according to the process of claim 1 wherein that driving pulse is set up, to make at a utmost pointAny conversion sequence of the pixel of the beginning of end in optical states and end, the electric current by described pixelAlgebraical sum is zero substantially.

11. the method for claim 1, wherein said display is the electrophoretic display device (EPD) of encapsulation.

12. the method for claim 1, wherein said display is to comprise staying mounting mediumCharged particle in multiple cavitys of interior formation and the micro unit display of suspension.

13. the method for claim 1, wherein said display is passive matrix display.

14. 1 kinds of bistable electro-optic displays, described display has at least one and has two extremelyThe pixel of optical states, and display controller, for electric field is applied to described pixel and fromAnd its optical states is changed to final gray level from initial grey levels, described display controller is establishedBe set to:

(a) described pixel is urged to different from described initial grey levels from described initial grey levelsAn extreme optical state; And

(b) described pixel is urged to and a described extreme path from a described extreme optical stateThe final gray level that state is different,