CN102456320A

CN102456320A - Electrophoretic display and picture updating method thereof

Info

Publication number: CN102456320A
Application number: CN2010105116580A
Authority: CN
Inventors: 魏嘉宏; 郭文源; 庄翔琮
Original assignee: EUREKA MICROELECTRONICS Inc
Current assignee: EUREKA MICROELECTRONICS Inc
Priority date: 2010-10-19
Filing date: 2010-10-19
Publication date: 2012-05-16

Abstract

The invention discloses an electrophoretic display. When a picture is updated, the ghost shadow of an old picture is erased at first, then a plurality of frames are continuously opened, and all pixels are gradually regulated to own required grayscales in a way that each frame is changed only by a grayscale. By the electrophoretic display, the update of the picture can be simplified, picture updating speed can be increased and the capacity of an identification key can be decreased. The time length of the frame is regulated, so that the regulation of brightness further can be simplified.

Description

Electrophoretic display device (EPD) and menu renewal method thereof

Technical field

The present invention is relevant a kind of electrophoretic display device (EPD) (Electro Phoretic Display; EPD), particularly about the menu renewal method of a kind of EPD.

Background technology

With the display in comparison of other kinds, EPD has the advantage of lower power consumption, but the complicated shortcoming of type of drive is arranged.As far as EPD; To a pixel be changed into another GTG from certain GTG; Its drive signal is not as long as consider final GTG; Also to consider initial GTG, people's such as M.Johnson " High Quality Images on Electronic PaperDisplays " for example, SID 05Digest 1666 (2005) references.

Active-matrix formula EPD with shown in Figure 1 is an example; When control EPD 10 frame update, main frame 12 is sent to time schedule controller 14 with new picture, and time schedule controller 14 utilizes storer 16 to store new, old picture respectively; Find corresponding drive waveforms according to new, the old GTG value of each pixel from flash memory 18 again; Produce control signal then and give EPD panel 20, drive row electrode 24 in proper order by row driver 22, line driver 26 provides specific voltage to column electrode 28.In EPD panel 20; Each bar row electrode 24 has a pixel 30 with each bar column electrode 28 intersection; Thin film transistor (TFT) 32 of each pixel 30 configuration, its grid, source electrode are connected row electrode 24, column electrode 28 and the pixel electrode of this pixel 30 respectively with drain electrode, so optionally apply voltage to this pixel 30; Electrophoresis particle to produce this pixel 30 of electric field driven moves, thereby this pixel 30 is brightened or deepening.Microcapsules double base particIe system with shown in Figure 2 is an example; Between two

parallel poles

34 and 36, clip microcapsules 38; Black track producing particle 40 and white particle 42 that suspension is arranged in it; The two carries opposite electrical electric charge, applies therefore that voltage V can drive black track producing particle 40 on

electrode

34 and 36 and white particle 42 moves toward opposite direction respectively.Look side when black track producing particle 40 more approaching sights, for example in that side of electrode 34, the color that pixel 30 is appeared is black more; Otherwise; Look side when white particle 42 more approaching sights, the color that pixel 30 is appeared is white more, but thereby the displacement performance different gray levels of mat control black track producing particle 40 and white particle 42.The displacement of black track producing particle 40 and white particle 42; And thereby the variation of the optical states of deriving; With voltage V be positive correlation to the integration (being called potential pulse) of time; People's such as R.Zehner " Drive waveforms for active matrix electrophoretic displays " for example, SID 03Digest 842 (2003) references.Get back to Fig. 1; Change into the drive waveforms of another GTG from any GTG; System with the stores of key in storer 18; Supply time schedule controller 14 to read, people's such as H.Gates " High Performance ActiveMatrix Electrophoretic Display Controller " for example, SID 08Digest 693 (2008) references.16 GTG systems with shown in Figure 3 are example, and initial GTG has 16 kinds, and final GTG also has 16 kinds, therefore have 16 * 16=256 kind GTG and shift gears, that is need 256 kinds of drive waveforms.In existing EPD; As shown in Figure 4; The corresponding position of target gray scale is moved to electrophoresis particle from present position through the driving of a plurality of frameworks in its type of drive system, comprises in the process to drive electrophoresis particle repeatedly, makes it arrive the corresponding position of target gray scale gradually.This type of drive is very complicated and consuming time, and causes power consumption more because framework quantity.

In addition, if the drive waveforms of a framework needs 2 bits to store, key just needs the capacity of 256 * N * 2 ÷ 8=64N bit group (byte) so, and can significantly increase along with the increase of grey exponent number.Secondly; Properties of materials can be along with temperature change; Therefore key need store the drive waveforms under the multiple different temperatures; People's such as H.Gates " High Performance Active Matrix Electrophoretic Display Controller " for example, SID 08Digest693 (2008) reference causes key huger.

Because the difference of material, the drive waveforms of same GTG adjustment can't be suitable for whole EPD panels, so each batch product all will reset key, is not suitable for a large amount of productions.

Above-mentioned type of drive also has adverse influence to the brightness adjustment of EPD panel, and this is because of the determining positions of brightness by electrophoresis particle, in case will change the luminance difference of each GTG, then all drive waveforms all must be upgraded.

Summary of the invention

One of the object of the invention is to propose a kind of EPD and menu renewal method thereof.

One of the object of the invention is to propose a kind of frame updating EPD and menu renewal method thereof faster.

One of the object of the invention is to propose a kind of EPD and menu renewal method thereof than power saving.

One of the object of the invention is to propose a kind of EPD and menu renewal method thereof that reduces the key capacity.

One of the object of the invention is to propose a kind of EPD and menu renewal method thereof of simplifying the brightness adjustment.

According to the present invention, a kind of EPD comprises the EPD panel, and time schedule controller connects this EPD panel, and flash memory connects this time schedule controller, and this flash memory is with the drive waveforms of a GTG of stores change of key.When frame update, the ghost of old picture on this EPD panel of erasing is earlier opened a plurality of frameworks more continuously, and each framework only changes a GTG, progressively all pixels are adjusted to its desired separately GTG.

Because each framework only changes a GTG, therefore simplify the renewal of picture, also reduce the quantity of framework, thereby accelerate the speed of frame update, and reduce power consumption.Owing to only store the drive waveforms of a GTG of change, therefore significantly reduce the capacity of key.Further, use this type of drive, the frequency of Adjustment System clock pulse can be adjusted the luminance difference of each GTG.

Description of drawings

The synoptic diagram of Fig. 1 owner's kinetic moment configuration EPD;

The synoptic diagram of Fig. 2 system microcapsule double base particIe system;

Fig. 3 is the synoptic diagram that the GTG of 16 GTG systems shifts gears;

Fig. 4 is the synoptic diagram of the EPD type of drive of convention;

Fig. 5 is the graph of a relation between different voltages and pulse length and the brightness variation;

Fig. 6 system is according to a method embodiment of the present invention;

Fig. 7 system is adjusted to all pixels the synoptic diagram of same gray level;

Fig. 8 system adjusts to pixel the process of GTG 15;

Fig. 9 system adjusts to pixel the process of GTG 3;

Figure 10 system adjusts to pixel the process of GTG 0;

Figure 11 system is with the process of two-way adjustment GTG;

Figure 12 system can adjust the synoptic diagram of EPD of the change brightness of GTG; And

Figure 13 is the synoptic diagram of two kinds of system's clock pulse frequencies.

The main element symbol description:

10EPD

12 main frames

14 time schedule controllers

16 storeies

18 flash memories

The 20EPD panel

22 row drivers

24 row electrodes

26 line drivers

28 column electrodes

30 pixels

32 thin film transistor (TFT)s

34 electrodes

36 electrodes

38 microcapsules

40 black track producing particles

42 white particles

44 GTGs 0

46 GTGs 15

48 GTGs 7

50 voltage controlled oscillators

Embodiment

As shown in Figure 2;

Electrophoresis particle

40 and 42 displacement dL are the functions of voltage V and application time length thereof; People's such as R.Zehner " Drive waveforms for active matrix electrophoretic displays " for example; SID 03Digest842 (2003) reference, but so required potential pulse of GTG of the every change of advance planning.For example; Fig. 5 be T.Whitesides etc. the people exists " Towards video-rate microencapsulated dual-particle electrophoreticdisplays; " Disclose among the SID 04Digest 133 (2004), different voltages and pulse length and brightness change dL ^*Between relation, wherein pulse length representes to apply the time span of voltage, L ^*Tie up to brightness (lightness) unit that defines in the CIELAB standard.Can know from Fig. 2 and Fig. 5, GTG can by

DL ^*=v * t=kV * t formula 1

Decision, wherein v is the translational speed of electrophoresis particle 40 and 42.Under ideal state, brightness changes dL ^*Be directly proportional with the traveling time t of

electrophoresis particle

40 and 42, that is k is a constant.But dL in the enforcement ^*Family curve be not linear, as shown in Figure 5.DL does not associate ^*Family curve can draw up required potential pulse of GTG of every change, for example at the required pulse length t of certain voltage V.Based on this, required drive waveforms of GTG of all changes is stored in the quickflashing note body 18 of Fig. 1.When adjusting the GTG of pixel 30, open a plurality of frameworks continuously, apply corresponding drive waveforms to pixel 30, each framework only changes a GTG, reaches the GTG of wanting up to pixel 30.

Fig. 6 system is according to a method embodiment of the present invention.With reference to Fig. 1 and Fig. 6, when frame update, earlier by the erase ghost of present picture of step S1.In this step, time schedule controller 14 is opened several frameworks, all pixels 30 of EPD panel 20 is applied reset potential pulse, and the preferably comprises at least black and white alternately.Then step S2 is adjusted to identical GTG with all pixels 30, and for example with reference to Fig. 7, whole pixels 30 all are adjusted to GTG 0, shown in dotted line 44, or GTG 15, shown in dotted line 46, GTG 7 is shown in dotted line 48.Get back to Fig. 1 and Fig. 6, final step S3 opens a plurality of frameworks continuously, and each framework only changes a GTG, progressively all pixels 30 is adjusted to its desired separately GTG.For example, pixel is adjusted to GTG 15, no matter its initial GTG why with reference to Fig. 8; Through erasing, open 16 frameworks then continuously earlier, behind the 1st framework, adjust to GTG 0; Behind the 2nd framework, adjust to GTG 1, the rest may be inferred, behind the 16th framework, adjusts to GTG 15.As shown in Figure 8, in the system of one 16 GTG, at most only need 16 frameworks just can accomplish the GTG adjustment of all pixels, add the framework of before having erased, its framework sum lacks than the type of drive of convention, so the rapid speed of frame updating, also than power saving.With reference to Fig. 9, pixel is adjusted to GTG 3, its process is identical with Fig. 8, but behind the 4th framework, has reached GTG 3, and follow-up framework promptly no longer applies voltage to this pixel, and this pixel keeps GTG 3 to finish up to 16 frameworks.The pixel of other GTGs also is identical situation, and any one pixel is just no longer change after reaching its target gray scale, and have only still the pixel of miss the mark GTG can continue GTG of each framework change in follow-up framework.Because the pixel of low GTG early stops to change its GTG, therefore further power saving.Figure 10 shows another kind of situation, all adjusts to GTG 15 in the whole pixel in back of erasing, and also is GTG of each framework change then, and target is that the pixel of GTG 0 reaches GTG 0 through 16 frameworks.In Figure 11; Whole pixels all is adjusted to GTG 7 earlier after erasing; Open a plurality of frameworks then continuously; The pixel that target is lower than GTG 7 reduces a GTG through each framework, and the pixel that target is higher than GTG 7 increases a GTG through each framework, so further reduces the quantity of framework.

As previously mentioned, potential pulse is depended in the displacement of electrophoresis particle.If the voltage that applies is higher, just then required pulse length is shorter, vice versa.Again because dL ^*Characteristic non-linear, even apply identical voltage, changing a required time of GTG from different gray levels also may not be identical.Therefore, the time span of different frames may not be identical, and the driving voltage of different frames is also unnecessary identical, and the time span and the driving voltage of each framework are determined by system designer.But in a system, the time span of each framework serves as that the basis produces with system's clock pulse all, therefore can utilize these characteristics to adjust the grayscale difference of EPD panel.Because GTG of each framework change, so under identical driving voltage, the time span that changes framework promptly changes the brightness of a GTG change.For example shown in Figure 12, time schedule controller 18 comprises voltage controlled oscillator 50 provides the clock pulse CLK of system, and the clock pulse CLK of this system is the basis of the time span of decision framework.In the time will adjusting the brightness of EPD panel 20, frequency that can Adjustment System clock pulse CLK, thereby change the time span of each framework.For example shown in Figure 13, system's clock pulse becomes CLK2 from CLK1, and its frequency improves; So being applied to the time span of each framework of EPD panel 20 all can shorten; So the time that electrophoresis particle moves during each framework shortens, under identical driven, its shift shortens.With reference to formula 1, the shortening of time t will make the difference of GTG diminish, and therefore can change the fineness of each GTG by the frequency of Adjustment System clock pulse CLK.

In various embodiment, do not change the frequency of the clock pulse CLK of system, but change the quantity of the corresponding clock pulse counting of each framework.For example, originally the time span of a framework is equivalent to 50 clock pulse countings, and it is reduced to 40 clock pulse countings, promptly shortens its time length 20%.

Inspect the capacity of key now.In the system of one 16 GTG, key only need store the drive waveforms of 16 frameworks.If the pairing frequency of each framework rank store with 4 bits, then key needs the capacity of 16 * 4 a ÷ 8=8 bit group, far below the capacity of convention key.

Claims

1. an electrophoretic display device (EPD) is characterized in that, described display comprises:

Electrophoresis display panel contains a plurality of pixels;

Time schedule controller connects described electrophoresis display panel; And

Flash memory connects described time schedule controller, stores the drive waveforms of a GTG of described a plurality of pixel changes;

Wherein, when frame update, described time schedule controller reads the drive waveforms that needs from described flash memory, produces control signal and gives described electrophoresis display panel, adjusts the GTG of at least one central pixel of described a plurality of pixel.

2. the menu renewal method of an electrophoretic display device (EPD) is characterized in that, described method comprises the following steps:

The ghost of A, the old picture of erasing; And

B, open a plurality of frameworks continuously, each framework only changes a GTG, is adjusted to its desired separately GTG with the pixel that progressively will upgrade.

3. like claim 2 menu renewal method, it is characterized in that described steps A comprises that the whole pixels to described electrophoretic display device (EPD) apply and resets potential pulse.

4. like claim 2 menu renewal method, it is characterized in that described step B comprises that the whole pixels with described electrophoretic display device (EPD) are adjusted to same GTG earlier.

5. like claim 2 menu renewal method, it is characterized in that described step B comprises that the whole pixels with described electrophoretic display device (EPD) are adjusted to full grey black rank earlier.

6. like claim 2 menu renewal method, it is characterized in that described step B comprises that the whole pixels with described electrophoretic display device (EPD) are adjusted to full lime rank earlier.

7. like claim 2 menu renewal method, it is characterized in that described step B comprises that the whole pixels with described electrophoretic display device (EPD) are adjusted to a GTG between full grey black rank and full lime rank earlier.

8. like claim 2 menu renewal method, it is characterized in that described method more comprises the time span of adjusting described a plurality of frameworks.

9. like claim 2 menu renewal method, it is characterized in that described method more comprises the frequency of Adjustment System clock pulse, to adjust the time span of described a plurality of frameworks.

10. like claim 2 menu renewal method, it is characterized in that described method more comprises the quantity of the corresponding clock pulse counting of each framework of adjustment, to adjust the time span of described a plurality of frameworks.