CN1849639A

CN1849639A - Driving method for an electrophoretic display with high frame rate and low peak power consumption

Info

Publication number: CN1849639A
Application number: CN 200480025683
Authority: CN
Inventors: G·周; A·V·亨岑; J·范德卡默; M·T·约翰逊
Original assignee: Koninklijke Philips Electronics NV
Current assignee: Koninklijke Philips NV
Priority date: 2003-09-08
Filing date: 2004-08-30
Publication date: 2006-10-18

Abstract

An image is updated on a bi-stable display (310) such as an electrophoretic display by using voltage waveforms ( 600, 620, 640, 660; 700, 720, 740, 760; 800, 820, 840, 860 ) that are configured such that voltage changes are constrained to a subset of possible voltage levels during specific frame times. The specific frame times may occur during datadependent portions of the waveforms, such as a reset portion (R) and/or a drive portion (D, D 1 , D 2 ). Due to the reduced voltage swing, the supply voltage can be reduced, resulting in reduced power consumption. Moreover, the frame time (FT') can be shortened during the data-dependent portions of the waveforms to increase the greyscale accuracy and number of grey levels. At other frames times, the voltage levels can vary throughout the full range of possible voltage levels, while a standard frame time (FT) is used.

Description

Driving method with electrophoretic display device (EPD) of high frame frequency and low peak power consumption

The present invention relates generally to more specifically, relate to a kind of method and apparatus, be used to the such bistable display of driving such as electrophoretic display device (EPD) that set of drive waveforms is provided, reduce power consumption simultaneously such as e-book and the such electronic reading device of electronic newspaper.

Nearest technical progress provides the electronic reading device of " user friendly ", the e-book that for example has a lot of chances to open.For example, electrophoretic display device (EPD) has been promised a lot of application prospects.This display has intrinsic memory property, can keep the long relatively time of image and does not have power consumption.Consumed power just when display need refresh or upgrade fresh information only.So the power consumption of this display is very low, be applicable to the portable electronic reading device of picture e-book and electronic newspaper and so on.Electrophoresis refers to the motion of charged particle in the electric field that is applied.When electrophoresis takes place in liquid when, the viscosity resistance that particle movement speed is mainly suffered by particle, their electric charge (nonvolatil or induct), the dielectric properties of liquid and the size decision of institute's applied field.Electrophoretic display device (EPD) is a kind of type of bi-stable display, and this display is basic behind image update to keep image and non-consumed power.

For example, by E Ink Corporation, Cambridge, Massachusetts, the name that US delivered on April 9th, 1999 is called in the International Patent Application WO 99/53373 of Full Color Reflective DisplayWith Multichromatic Sub-Pixes has described this display device.WO 99/53373 has discussed the electronic ink display with two substrates.A substrate is transparent, and another is provided with embarks on journey into the electrode that row are arranged.Display element or pixel are associated with the point of crossing of column electrode and row electrode.Display element uses thin film transistor (TFT) (TFT) to be coupled to the row electrode, and the gate coupled of this thin film transistor (TFT) is to column electrode.This structure of display element, TFT transistor, row and column electrode has formed active matrix together.And this display element comprises pixel electrode.Line driver is selected delegation's display element, and row or Source drive provide data-signal to arrive selected row of display elements by row electrode and TFT transistor.The graph data that this data-signal shows corresponding to needs, for example text or image.

Between the common electrode on pixel electrode and the transparent substrates, provide electric ink.Electric ink comprises that a plurality of diameters are about 10 to 50 microns micro-capsule.In one approach, each micro-capsule has the white particles and the electronegative black particles of the positively charged in liquid carrier medium of being suspended in or the fluid.When positive voltage was applied on the pixel electrode, white particles was to a side shifting of the micro-capsule that points to transparent substrates, and the observer can see white display element.Simultaneously, black particles moves to the pixel electrode of micro-capsule opposite side, and they are not observer's finding herein.Be pressed onto pixel electrode by applying negative electricity, black particles is shifted to the public electrode at the micro-capsule one side place that points to transparent substrates, and display element shows dead color to the observer.Simultaneously, white particles moves to the pixel electrode at the opposite side place of micro-capsule, and they are not observer's finding herein.When cancelling voltage, display device is retained in the state that it obtains, and presents bistable characteristic like this.In another kind of scheme, in dyeing liquid, provide particle.For example, can in white liquid, provide black particles, or white particles is provided in black liquor.Perhaps, can in the liquid of other color, provide the particle of different colours, for example, in blue liquid, provide white particles.

For example other such fluids of air also can use in medium, wherein charged black and white particle (for example moves around in electric field, Bfidgestone SID2003-Symposium on Information Displays.May 18-23,2003 ,-digest20.3).Also can use colored particle.

In order to form electronic console, electric ink can be printed onto one on the plastic sheeting of circuit layer superimposed layer.This circuit forms the pixel graphics that can be shown driver control.Because microcapsule suspension in liquid carrier medium, so in fact they can use existing silk-screen printing technique to be printed onto any surface, comprises glass, plastics, fiber even paper.And the use of flexible sheets allows the electronic reading device of the approximate conventional books of design outward appearance.

Yet when frame was updated, when particularly using higher frame frequency to upgrade, owing to the variation of the voltage that is applied to pixel is big and quick, so the power of electronic console consumption may become high as can not to receive.For example, higher frame frequency can be used for higher temperature, or is used to increase the quantity or the greyscale accuracy of gray level.

The present invention solves above-mentioned and other problems by a kind of method and apparatus is provided, and this method and apparatus provides set of drive waveforms to drive bistable display such as electrophoretic display device (EPD), reduces power consumption simultaneously.

In a special aspects of the present invention, a kind of method provides set of voltage waveforms, is used for upgrading in the successive frame cycle at least a portion of bistable display.This method comprises access data, this data definition be used for the described set of voltage waveforms in described successive frame cycle, and, produce the described set of voltage waveforms that is used in this at least a portion of described successive frame cycle drive bistable display according to the data of institute's access.In the duration in successive frame cycle, each voltage waveforms spans first value scope.And at least one in the cycle of described successive frame aimed in time with the data relevant portion of each voltage waveform of the second value scope of leap, and this second value scope is the subclass of the first value scope.

Relevant electronic reading device and program storage device also is provided.

In the accompanying drawing:

Fig. 1 schematically shows the front elevation of an embodiment of a part of the display screen of electronic reading device;

Fig. 2 schematically shows among Fig. 1 the sectional view along 2-2;

Fig. 3 schematically shows the skeleton diagram of electronic reading device;

Fig. 4 schematically shows has two display screens of viewing area separately;

Fig. 5 shows the example waveform that is used for image transitions, wherein high-peak power be desirably in t0 to t1, t1 between the t2.

Fig. 6 shows the example waveform that image changes that is used for according to the first embodiment of the present invention, and wherein the part of the driving pulse in the transformation from B to G2 is delayed three frame periods.

Fig. 7 shows the example waveform that is used for image transitions according to a second embodiment of the present invention, and wherein the part of the driving pulse in the transformation from W to G1 and from G2 to G1 is delayed two frame periods.

Fig. 8 shows the example waveform that image changes that is used for of a third embodiment in accordance with the invention, and wherein the part of the driving pulse in the transformation from W to G1 and from G2 to G1 is delayed three frame periods.

In all accompanying drawings, corresponding part is represented by identical reference number.

Quote following each document herein as a reference:

European patent application EP 02078823.8, name is called " Electrophoretic DisplayPanel ", submits on September 16th, 2002 (attorney no.PHNL 020844);

European patent application EP 03100133.2, name is called " Electrophoretic DisplayPanel ", submits on January 23rd, 2003 (attorney no.PHNL 030091);

European patent application EP 02077017.8, name is called " Display Device ", submit on May 24th, 2002, or WO 03/079323, " Electrophoretic ActiveMatrix Display Device ", on February 6th, 2003 open (attorney no.PHNL 020441); And

European patent application EP 03101705.6, name is called " Electrophoretic DisplayUnit ", submits on June 11st, 2003 (attorney no.PHNL 030661).

Fig. 1 and 2 shows a kind of embodiment of a part of display panel 1 of electronic reading device, and this electronic reading device has first substrate, 8, second opposed substrate 9 and a plurality of image component 2.Image component 2 can be substantially along the line spread in the two-dimensional structure.The image component 2 that for clarity sake illustrates is mutually away from placement, but in fact, image component 2 can be very close to each other to form continuous images.And, only show the part of full display screen.Can use other structures of image component, for example honeycomb.Electrophoretic medium 5 with charged particle 6 is present between substrate 8 and 9.First electrode 3 is relevant with each image component 2 with second electrode 4.Electrode 3 and 4 can receive electric potential difference.In Fig. 2, have 3, the second substrates 9 of first electrode for each image component 2, the first substrate and have second electrode 4.Charged particle 6 can occupy near electrode 3 or electrode 4 or the position between them.The outward appearance of each image component 2 is by the determining positions of the charged particle between electrode 3 and 46.Electrophoretic medium 5 is from United States Patent (USP) 5,961, and 804,6,120,839 and 6,130,744 know, and for example, can obtain from EInk Corporation.

For instance, electrophoretic medium 5 can comprise electronegative black particles 6 in the white fluid.When for example because+electric potential difference of 15V, charged particle 6 is during near first electrode 3, the outward appearance of image component 2 is white.When for example because-the opposite polarity electric potential difference of 15V, charged particle 6 is near second electrode 4 time, the outward appearance of image component 2 is a black.When charged particle 6 was between electrode 3 and 4, image component had the intermediate appearance such as gray level between the black and white.The electric potential difference of each image component 2 of special IC (ASIC) 100 control to be to produce required image on entire display screen, for example image and/or text.Entire display screen is made up of numerous image components, and image component is corresponding to the pixel in the display.

Fig. 3 schematically shows a kind of skeleton diagram of electronic reading device.This electronic reading device 300 comprises demonstration ASIC 100.For example, this ASIC 100 can be " Apollo " ASIC electric ink display controller of Philips company.Show ASIC 100 by the one or more display screens 310 of addressing circuit 305 controls, electrophoretic screens for example is to produce text to be shown or image.Addressing circuit 305 comprises drive integrated circult (IC).For example, show that ASIC 100 can be used as voltage source, it provides voltage waveform by addressing circuit 305 for the different pixels in the display screen 310.Addressing circuit 305 is provided for the information of addressing specific pixel (for example row or column) with display image or text.Demonstration ASIC 100 makes and begins to show continuous page or leaf at different row and/or row.Image or text data can be stored in the storer 320, the one or more memory storages of storer 320 representatives, and visited by ASIC 100 as required.(small form factoroptical, SFFO) disc system in other system, can use non-volatile flash memory to the little form factor light that example is Philips Electronics.Electronic reading device 300 also comprises reading device controller 330 or console controller, and it can respond user's activating software or hardware button 322, and this software or pushbutton enable user command are for example descended one page order or prevpage order.

Reading device controller 330 can be the part of computing machine, and it carries out the computer code devices of any kind, and for example software, firmware, microcode etc. are to obtain function described herein.Therefore, the computer program that comprises this computer code devices can provide in the conspicuous mode of those skilled in the art.Reading device controller 330 can also comprise the storer (not shown), and it is program storage device and can comprises the instruction repertorie of being carried out by machine (for example reading device controller 330 or computing machine), to carry out the method that obtains function described here.This program storage device can provide in the conspicuous mode of those skilled in the art.

Show that ASIC can have the logic that forced resetting periodically is provided for the viewing area of e-book, for example after showing at every x page or leaf, after every y minute (for example 10 minutes), when electronic reading device 300 is unlocked for the first time, and/or when luminance deviation during greater than a certain value (for example 3% reflection).For automatically reseting, can determine acceptable frequency with experience based on the low-limit frequency that produces the acceptable image quality.And, for example, when the user begins to read this electronic reading device or when picture quality is reduced to unacceptable level, resets and can be manually booted by function button or other interface devices by the user.

ASIC 100 provides instructions to display addressing circuit 305 to be stored in information in the storer 320 by access and driving display 310.

The present invention can be used for the electronic reading device of any kind.Fig. 4 shows a possibility example of the electronic reading device 400 with two separate display screens.Particularly, on first screen 440, provide first viewing area 442, second viewing area 452 is provided on second screen 450.Screen 440 can link to each other by junction button (binding) 445 with 450, and it allows screen folding mutually or at a unfolded surface and pave.This structure is desired, because it is near duplicating the process of reading conventional books.

Can provide various user interface devices to start page on, page back order etc. to allow the user.For example, first area 442 can comprise button 424, contact activation, PDA pen or other known technologies on the screen that can use mouse or the activation of other pointing devices, to advance between the page or leaf of this electronic reading device.Except page on and page back order, can be provided in the function of rolling up or down on the same page.Replace or extraly, can provide hardware button 422 to provide page on and page back order to allow the user.Second area 452 also can comprise screen upward button 414 and/or hardware button 412.Attention is unwanted around the frame of first and second viewing areas 422 and 452, because the viewing area can be no frame.Also can use for example voice command interface of other interfaces.Note button 412,414; 422,424 is not that two viewing areas all need.That is, can provide single group page on and page back button.Perhaps, can start single button or for example rocker switch other the device so that page on and page back order to be provided.Also can provide function button or other interface arrangements to reset to allow the user to manually boot.

In other possible designs, e-book has single display screen, and it has the single viewing area that once shows one page.Perhaps, for example single display screen two or more viewing areas that can be divided into flatly or vertically arrange.And, when using a plurality of viewing area, can show continuous page or leaf with any desired order.For example, in Fig. 4, first page can 442 demonstrations in the viewing area, second page of 452 demonstration in the viewing area simultaneously.When the user need see down one page, the 3rd page can show first page of replacement in first viewing area 442, and second page of maintenance simultaneously is presented at second viewing area 452.Similarly, the 4th page can show in second viewing area 452, by that analogy.In other method, when one page was seen down in user's request, two viewing areas were all upgraded, and made the 3rd page in first page of demonstration of first viewing area, 442 replacements, and the 4th page in second page of demonstration of second viewing area, 452 replacements.When using single viewing area, can show first page, when the user keyed in down one page order, then second page rewrote first page, by that analogy.This process reverse operation is used for the page back order.And this process is applicable to the language that text reads from right to left too, and for example Hebrew, and text is the language that vertically reads rather than laterally read, for example Chinese.

In addition, note need not showing whole page or leaf in the viewing area.Can show the part of this page, and rolling function is provided, allow the user to roll up or down, to the left or to the right and read other parts of this page.Can provide and amplify and reduction capability, change the size of text or image to allow the user.For example this user for visual deterioration is desirable.

The problem that solves

Have been found that pulse-length modulation (PWM) is the low-cost technologies that drives bistable display (for example electrophoretic display device (EPD)), because the driver price is low.Use drive waveforms, grey level accuracy is by the minimum frame time restriction, and this minimum frame time is the standard time of 20ms normally.Yet, obtained littler frame time recently, approximately 8ms.

Such as the motion of the bistable display of electrophoretic display device (EPD) based on charged particle under the external electrical field.Because particle mobility changes with the viscosity with temperature of temperature change and/or fluid, so switching time and temperature correlation.Use existing electronic ink material, reduce along with the rising of temperature switching time, and the driving voltage waveform that develops for room temperature must extend to higher temperature.A kind of possible method is for example to reduce the frame period (in European patent application EP 02078823.8, discussing among the docket no.PHNL 020844) by convergent-divergent, wherein needs very short frame time.In addition, need shorter frame time with the quantity that improves gray level and further improve greyscale accuracy.Yet the use of Duan frame time causes higher power consumption relatively.Particularly, must be in identical short frame scan during when Source drive integrated circuit (IC) in whole range of voltage values work, need unacceptable high-peak power.The invention solves this problem.

The solution that proposes

A kind of technology has been discussed, and it is used for reducing bistable device when using high frame frequency power consumption obtains gray level, increase number of grey levels accurately simultaneously.

In a possible solution, the drive waveforms that is used for various greyscale image transitions is aimed at wittingly in time, make one or more image duration change in voltage be limited in may the subset range of magnitude of voltage in.In other words, can avoid the voltage swing of the gamut between the minimum and maximum value.For example, when may voltage range in the waveform be-15V is during to+15V, can avoid from-15V to+15V or variation for the specific part of waveform from+15V to-15V.As for flirtatious, these specific parts that allow voltage waveform change from-15V to 0V or from 0V to+15V.These waveform portion can comprise the waveform data relevant portion that uses the relatively short frame period.By reducing voltage swing or the span in one or more frames, power consumption reduces significantly.Particularly, the peak power and the square-wave voltage of bistable device consumption are varied to ratio, that is, and and P ∝ C * (Δ V) ², wherein C represents electric capacity.More specifically, the peak power that is consumed is the product of electric capacity * frequency * voltage swing * supply voltage.For example the IC of the pixel of service voltage in the bistable device or the supply voltage of chip must equal voltage swing at least in addressing circuit 305, for example can be 30V.The scope of the possible voltage that voltage swing or span are to use, for example 30V (+15V-(15V)).Like this, by reducing voltage swing to half, i.e. 15V has reduced half power consumption in the particular frame process.Yet, according to an aspect of the present invention, for example can supply voltage be reduced to for example 15V according to the voltage swing that reduces.This with power consumption be reduced to it original 1/4th.The result that supply voltage and voltage swing reduce is, can use length is 1/4th frame time of standard frame time, keeps identical low power consumption simultaneously.Because the utilization factor of short frame time is extremely useful for improving greyscale accuracy at higher temperature and increasing number of grey levels, so this point is very important.

The present invention is applicable to any driving mechanism, comprises bus stabilized driving mechanism (rail-stabilized driving schemes), and wherein driving pulse comprises reset pulse and greyscale drive pulse.Reset pulse is to make particle in the bistable display move to the potential pulse of one of two extreme optical state, and greyscale drive pulse is to make display/pixel change to the potential pulse of required final optical states.In the following embodiments, although can use other driving mechanisms, the bus stabilized driving of describing in the above-mentioned European patent application EP 03100133.2 (attorney no.PHNL030091) is used for explaining of the present invention may the execution.

Fig. 5 shows the example waveform that is used for image transitions, wherein high-peak power be expected at t0 between the t1 and t1 occur between the t2.Example waveform shows to use orbitally stable to drive to change (waveform 500), black (B) from the image of white (W) to dark-grey (G1) and changes (waveform 520), the G2 image transformation (waveform 560) to the image transformation (waveform 540) of G1 and G2 to G2 to the image of light gray (G2).These examples have been represented a subclass for 16 required waveforms of the electrophoretic display device (EPD) update image with 4 indication luminance levels.Use the bus stabilized driving, for example use reset pulse (R) in waveform 500, the mobile distance of its duration and particle (for example, from white states (W) to black state (SB)) needs between two electrodes is proportional.Reset pulse (R) can have the duration of resetting, and was used to improve picture quality.Crossing reset pulse describes in the above-mentioned common unsettled european patent application of quoting 03100133.2 (docket no.PHNL 030091) to some extent.In waveform 500, subsequent drive pulse (D) have enough energy come driving display from black state (SB) to end-state promptly dark-grey (G1) state.The energy of pulse is the product of voltage amplitude and duration.

Usually, a large amount of this waveforms are stored in the storer of electronic installation, and are used for the pixel of driving display.These waveforms can be used for the part of refresh display, for example one or more pixels, or whole display.Perpendicular line is represented frame boundaries.Frame time or frame period are the time between the frame boundaries, or the inverse of frame frequency, and it can change in waveform.These waveforms generally begin simultaneously and finish.As discussed, for example short frame time of 8-10ms can be used for the selected portion of waveform, and for example increasing accuracy and more gray level is provided, and for example standard frame time of length of 20ms can be used for other parts of waveform.

Each waveform 500,520,540 and 560 comprises 4 parts: the first shake pulse (shaking pulse) (S1), partly (R), second shake pulse (S2) and the drive part (D) reset.SB and SW indicate black or the white states that arrives by reset pulse respectively.First and second pulses can be by carrying out with " hardware " shake of data independence, and wherein all pixels of display receive dither signal simultaneously, with the data independence on each pixel.Shaking pulse S1 and S2 as can be seen is time alignment between different wave.The shake of use hardware, power consumption can minimize.Describe to some extent among common unsettled european patent application 02077017.8 that the shake pulse is quoted in the above or the WO 03/079324 (docket no.PHNL 020441).Shake pulse and the combination of mistake reset pulse in drive waveforms have improved greyscale accuracy significantly.

Yet reset (R) and driving pulse (D) are the examples of the data relevant portion of waveform 500,520,540 and 560, because their frames are provided to each pixel with connecing a frame, therefore depend on the data of definition frame image.Reset pulse (R) is not so good as greyscale drive pulse (D) sensitivity to the selection of frame time.In fact, grey drive pulse (D) is very responsive for the selection of frame time, and middle grey level accuracy is mainly determined by the driving pulse frame time because each image changes (for example, W is to G1, B to G2 etc.).Therefore the discussion below us concentrates on drive part.Yet the selection of frame time all is important for any data relevant portion of the voltage waveform that is applied to bistable display.

In the image of Fig. 5 changes, greyscale drive pulse (D) time cycle (t _D) change to five frame times or cycle from two frame times or cycle.Especially, for waveform 500, t _D5=5FT comprises two standard frame time (FT) and three short frame times (FT ').For waveform 520, t _D4=4FT comprises two standard frame time (FT) and two short frame times (FT ').For waveform 540, t _D3=3FT comprises two standard frame time (FT) and short frame time (FT ').For waveform 560, t _D2=2FT comprises two standard frame time (FT).

Yet for the frame of some time alignments, some in the greyscale drive pulse have positive voltage, and other have negative voltage.Each drive part or pulse (D) comprise two standard frame time (FT), and they have had low relatively power consumption (although Source drive is worked) under negative, positive voltage.People even can think that these frames are to use " standard " frame of single length of single scanning keep power consumption even lower.At t ₀To t ₁Between and t ₁To t ₂Between frame period in, need have the single sweep of minimum (weak point) frame period FT ', negative, positive voltage all must be supplied with by Source drive therebetween, this causes unacceptable high-peak power.For example, at t ₀To t ₁Between, waveform 500,520,540 and 560 needs respectively-15V ,+15V ,-15V and 0V.Because minimum and maximum voltage (be respectively-15V and+15V) in identical frame, apply, when upgrading different pixels, voltage source must switching between its minimum and maximum output during the addressing different pixels in same number of frames, causes high power consumption.The waveform of discussing has below solved this problem by avoid the voltage swing of gamut at one or more particular frames of the particular data relevant portion of voltage waveform, and these frames are for example in same or more alignment in time in the multiframe.

Fig. 6 shows the example waveform that image changes that is used for according to the first embodiment of the present invention, and wherein the part of the driving pulse in the transformation from B to G2 postpones three frame periods.Waveform 600 provides from image transformation, the waveform 620 of white (W) to dark-grey (G1) provides image transitions, waveform 640 from black (B) to light gray (G2) to provide image transformation, waveform 660 from G2 to G1 to provide the image from G2 to G2 to change.Show with Fig. 5 in the identical waveform that uses, but the part of the greyscale drive pulse in the transformation (waveform 620) from B to G2 now postpones three short frames (FT ').Especially, the drive part of waveform 620 comprises first and second drive parts, is respectively D1 and D2, and wherein D2 follows D1 after postponing.

At t ₀To t ₁Between, use single sweep operation with frame time FT '.Yet the voltage level that is applied to now different pixels in same number of frames is not in-15V variation in whole (first) scope of 15V.But this voltage level is only in-15V subclass (second) range to 0V.Especially, at t ₀To t ₁Between, waveform 600,620,640 and 660 needs-15V, 0V ,-15V and 0V.Similarly, at t ₁To t ₂Between and t ₂To t ₃Between frame time in, waveform 600,620,640 and 660 needs-15V, 0V, 0V and 0V.Equally, voltage level only changes in the subset range of 0V at-15V.At t ₃To t ₄Between frame time in, waveform 600,620,640 and 660 need 0V ,+15V, 0V and 0V.Here, voltage level is only in subclass (three) range of 0V to+15V.In fact, for each short frame time (FT '), voltage swing is limited in one of subset voltage ranges.

In the example of discussing, possible magnitude of voltage changes between maximal value+15V at minimum value-15V, and wherein intermediate value 0V also uses.Yet the present invention can use the voltage of any scope, and voltage range need be not the center with zero.For example, minimum and maximum voltage can all be on the occasion of, for example from+10V to+40V.And, can constrain the voltage levels to two or more subset range in the probable value scope.Subset range can be continuously, discontinuous and/or overlapping.For example, can use two subset range, for example-15V is to 0V and 0V to+15V, they are continuous and leaps-15V arrives+first scope of the value of 15V.Reduce because be applied to the scope of the magnitude of voltage of pixel,, as discussed, cause the power consumption of particular frame time to reduce so also can be reduced to the supply voltage of voltage source.

Fig. 7 shows the example waveform that image changes that is used for according to a second embodiment of the present invention, and wherein the part of the driving pulse in the conversion from W to G1 and from G2 to G1 is delayed two frame periods.Waveform 700 provides from image transformation, the waveform 720 of white (W) to dark-grey (G1) provides image transformation, waveform 740 from black (B) to light gray (G2) to provide image transformation and the waveform 760 of G2 to G1 to provide the image from G2 to G2 to change.Show with Fig. 5 in the identical waveform that uses, but the part of the greyscale drive pulse (D2) of W in to the transformation (waveform 700) of G1 and G2 to the transformation (waveform 740) of G1 is delayed two frames now.Especially, for waveform 700, drive part comprises first drive part (D1), then is one or more frame time time-delays, then is second drive part (D2).Similarly, waveform 740 comprises first and second drive parts, is respectively D1 and D2.

Equally, for the frame of short frame time (FT '), configure waveforms makes voltage level only change in the subset range of probable value.For example, at t ₀To t ₁And t ₁To t ₂Between, voltage level only changes between+the 15V at 0V because waveform 700,720,740 and 760 need respectively 0V ,+15V, 0V and 0V.At t ₂And t ₃Between, voltage level only changes between the 0V at-15V because waveform 700,720,740 and 760 need respectively-15V, 0V ,-15V and 0V.At t ₃And t ₄Between and t ₄To t ₅Between, voltage level only changes between the 0V at-15V, because waveform 700,720,740 and 760 needs respectively-15V, 0V, 0V and 0V.

At the third and fourth frame (t ₀And t ₂Between) in, can use two scannings, each scanning all has frame time FT ', perhaps can use the single sweep of the frame time with 2FT '.In the 5th frame, at t ₂And t ₃Between, use single sweep with minimum FT.In the 6th and the 7th frame, at t ₃And t ₅Between, can use two scannings, each scanning all has the frame time of FT ', or uses the single sweep with 2FT ' frame time.

Fig. 8 shows the example waveform of the image transformation of a third embodiment in accordance with the invention, and wherein the part of the driving pulse in the transformation from W to G1 and from G2 to G1 is delayed three frame periods.Waveform 800 provides from image transformation, the waveform 820 of white (W) to dark-grey (G1) provides image transformation, waveform 840 from black (B) to light gray (G2) to provide image transformation and waveform 860 from G2 to G1 to provide the image from G2 to G2 to change.The 3rd embodiment draws from second embodiment, but has added extra frame.Especially, relevant with the corresponding waveform of Fig. 7, B change to G2 (waveform 800) and G2 change (waveform 860) to G2 positive driving pulse finish after and before the negative driving pulse (D2) of W to G1 and G2 to G1 transformation (being respectively waveform 800 and 840) begins, the extra frame of use V=0.Especially, in waveform 800, the second portion of driving pulse (D2) postpones three frames rather than two frames from the first (D1) of driving pulse.In waveform 820, provide the extra frame of V=0 afterwards at drive part (D).In waveform 840, the second portion of driving pulse (D2) postpones three frames rather than two frames from the first (D1) of driving pulse.In waveform 860, provide the extra frame of V=0 afterwards at drive part (D).This method can further reduce the time average load of Source drive, has further reduced power consumption averaging time thus.

Notice that in above-mentioned example, pulse-length modulation (PWM) drives and is used to set forth the present invention, wherein the burst length changes in each waveform, and the voltage amplitude maintenance is constant.Yet the present invention also is applicable to other driving mechanisms, for example, drives the PWM of (VM) (wherein pulse voltage amplitude changes) or combination and the driving mechanism that VM drives based on voltage modulated in each waveform.The present invention is applicable to colour and greyscale bi-stable displays.And electrode structure is unrestricted.For example, can use the plane internal switch and the vertical switch of top/end electroplax structure, honeycomb, plane internal switch structure or other combinations.And the present invention can carry out in passive matrix and active matrix electrophoretic display device (EPD).In fact, the present invention can use in any bistable display, consumed power not when this bistable display image after the image update is retained on the display substantially.And the present invention is applicable to list and windows display device, for example, wherein has the typewriter pattern.

Although what illustrate is the preferred embodiments of the present invention with what describe, be to be understood that certainly can not depart from spirit of the present invention makes various modifications and change on form or details.Therefore, the present invention is not restricted to the concrete form that institute describes and sets forth, but should cover all modifications that belongs in all accessory claim scopes.

Claims

1. one kind is provided for upgrading the method for the set of voltage waveforms of bistable display at least a portion at successive frame in the cycle, and this method comprises:

Access data, this data definition be used for the described set of voltage waveforms in described successive frame cycle; And

According to the data of institute's access, during the described successive frame cycle, produce the described set of voltage waveforms (600,620,640,660 of at least a portion be used to drive this bistable display (310); 700,720,740,760; 800,820,840,860); Wherein:

At the duration in described successive frame cycle, each in these voltage waveforms is crossed over the first value scope; And

At least one in the cycle of described successive frame alignd with the data relevant portion of each voltage waveform of crossing over the second value scope in time, and this second value scope is the subclass of the first value scope.

2. the process of claim 1 wherein:

Described successive frame in the cycle another aligns with the data relevant portion of each voltage waveform of crossing over the 3rd value scope in time at least, the 3rd value scope is the subclass of the first value scope.

3. the method for claim 2, wherein:

The second and the 3rd value scope is continuous and crosses over the first value scope.

4. the process of claim 1 wherein:

Use the relatively short frame period at least one described successive frame cycle described (FT ').

5. the process of claim 1 wherein:

The data relevant portion of each voltage waveform comprises the part (R) that resets.

6. the process of claim 1 wherein:

The data relevant portion of each voltage waveform comprise drive part (D, D1, D2).

7. the process of claim 1 wherein:

The data relevant portion of each voltage waveform comprises first drive part (D1), then is a time-delay, then is second drive part (D2).

8. the process of claim 1 wherein:

This bistable display comprises electrophoretic display device (EPD).

9. the method for claim 1 further comprises:

The supply voltage of voltage source is reduced to the supply voltage relevant with the second value scope from the supply voltage relevant with the first value scope, and this voltage source is used for producing described set of voltage waveforms the described of described successive frame cycle during at least one.

10. program storage device is implemented the instruction repertorie carried out by machine really and a kind ofly is provided for upgrading the method for the set of voltage waveforms of bistable display at least a portion in the cycle at successive frame to carry out, and this method comprises:

11. the program storage device of claim 10, wherein:

12. the program storage device of claim 10, wherein:

13. the program storage device of claim 10, wherein:

The data relevant portion of each voltage waveform comprise at least reset part (R) and drive part (D, D1, one of D2).

14. the program storage device of claim 10, wherein:

This bistable display comprises electrophoretic display device (EPD).

15. the program storage device of claim 10, wherein this method further comprises:

16. a display device comprises:

Bistable display (310), and

Controller (100), be used for as follows being provided for upgrading the set of voltage waveforms of at least a portion of bistable display (310) in the successive frame cycle: (a) access data, this data definition be used for the described set of voltage waveforms in described successive frame cycle; And, during the described successive frame cycle, produce the described set of voltage waveforms (600,620,640,660 of at least a portion that is used to drive this bistable display (310) (b) according to the data of institute's access; 700,720,740,760; 800,820,840,860); Wherein:

17. the display device of claim 16, wherein:

Use the relatively short frame period during at least one described successive frame cycle described (FT ').

18. the display device of claim 16, wherein:

19. the display device of claim 16, wherein:

This bistable display comprises electrophoretic display device (EPD).

20. the display device of claim 16, wherein:

Controller is reduced to the supply voltage relevant with the second value scope with the supply voltage of voltage source from the supply voltage relevant with the first value scope,, this voltage source is used for producing described set of voltage waveforms the described of described successive frame cycle during at least one.

21. a controller (100) comprising: the device of access data, this data definition be used for upgrading the set of voltage waveforms (600,620,640,660 of at least a portion of bistable display (310) in the successive frame cycle; 700,720,740,760; 800,820,840,860); And comprising the arithmetic logic circuit, it is configured to the data according to institute's access, produces the described set of voltage waveforms (600,620,640,660 of at least a portion be used to drive this bistable display during the successive frame cycle; 700,720,740,760; 800,820,840,860); Wherein:

At the duration in described successive frame cycle, each voltage waveforms spans first value scope; And