WO2007116448A1

WO2007116448A1 - Method for driving display element and display device

Info

Publication number: WO2007116448A1
Application number: PCT/JP2006/306693
Authority: WO
Inventors: Masaki Nose; Toshiaki Yoshihara; Hisashi Yamaguchi
Original assignee: Fujitsu Limited
Priority date: 2006-03-30
Filing date: 2006-03-30
Publication date: 2007-10-18
Also published as: TW200737088A; JPWO2007116448A1; JP4680297B2

Abstract

In a display element driving method, a plurality of scan electrodes intersecting in a confronting state with a plurality of data electrodes are selected in a predetermined order, and a pulsating voltage is applied to a display medium between each of the scan electrodes and each of the data electrodes, thereby to perform an image rewriting operation of a display screen. In this image rewriting operation, reset pulses for initializing the display medium and rewrite pulses for rewriting the display medium according to image data are continuously applied, thereby to perform the partial rewrite in an existing display image. In this case, the scan direction is switched according to the position of the area of the partial rewrite in the display screen.

Description

Display element driving method and display device

Technical field

The present invention relates to a display element driving method and a display device, and more particularly, to a display element driving technique for still image display including cholesteric liquid crystal.

Background art

[0002] In recent years, development of electronic paper has been actively promoted at research institutions such as companies and universities. In the application market where electronic paper is expected, various application forms such as sub-displays for mopile terminals and display units for IC cards have been proposed.

Conventionally, a cholesteric liquid crystal is known as a prominent electronic paper. This cholesteric liquid crystal has excellent characteristics such as semi-permanent display retention (memory property), vivid color display, high contrast and high resolution. Sarakuko and cholesteric liquid crystals can also display vivid full-color images by stacking display layers that exhibit RGB colors.

[0004] Cholesteric liquid crystals are also sometimes referred to as chiral nematic liquid crystals, and a relatively large amount (several tens of percent) of a chiral additive (also referred to as chiral material) is added to nematic liquid crystals. As a result, nematic liquid crystal molecules form a spiral cholesteric phase.

By the way, since the cholesteric liquid crystal is a liquid crystal having a memory property, it can be driven by a simple simple matrix, and for example, it is relatively easy to increase the size of A4 size or larger. The cholesteric liquid crystal consumes power only when the display content is updated (image is rewritten). When the image rewriting is completed, the image is held as it is even if the power is turned off.

First, an example of driving a cholesteric liquid crystal as an example of a display element according to the present invention will be described.

1A and 1B are diagrams for explaining the alignment state of the cholesteric liquid crystal. A shows the planar state, and Figure 1B shows the focal conic state.

[0008] The cholesteric liquid crystal can take two stable states, a planar state and a focal conic state, under no electric field.

That is, as shown in FIG. 1A, in the planar state, the incident light is reflected by the liquid crystal, so that the human eye can see the reflected light.

In addition, as shown in FIG. 1B, in the focal conic state, incident light passes through the liquid crystal. Further, by providing a light absorption layer separately from the liquid crystal layer, black can be displayed in the focal conic state.

[0011] Here, in the planar state, light having a wavelength corresponding to the helical pitch of the liquid crystal molecules is reflected, and the wavelength at which the reflection is maximized is defined as the average refractive index of the liquid crystal is n, and the helical pitch is p. Then, λ = η · ρ. Note that the reflection band Δλ increases with the refractive index anisotropy Δη of the liquid crystal, and the color of the wavelength λ is displayed in the planar state by selecting the average refractive index η and the helical pitch ρ of the liquid crystal. be able to.

[0012] Fig. 2 (b), Fig. 2 (b) and Fig. 2C are graphs showing the voltage characteristics (relationship between time and voltage) for driving the cholesteric liquid crystal. It shows how the state and the planar state change. Here, Η is the homeopic pick state, FC is the focal conic state, and P is the planar state.

[0013] First, when a strong electric field is applied to a cholesteric liquid crystal, the helical structure of the liquid crystal molecules is completely unwound, and a homeotopic picking state H in which all molecules follow the direction of the electric field is obtained.

[0014] As shown in FIG. 2B, the homeotopic pick state H force When the electric field is suddenly reduced to zero, the spiral axis of the liquid crystal becomes perpendicular to the electrode, and the planar state selectively reflects light according to the spiral pitch. Become P.

On the other hand, as shown in FIG. 2A, when the electric field is removed after formation of a weak electric field that can barely unwind the liquid crystal molecules, or when a strong electric field is applied as shown in FIG. 2C. When the electric field is gently removed, the spiral axis of the liquid crystal is parallel to the electrode, resulting in a focal conic state FC that transmits incident light.

[0016] Further, when an electric field having an intermediate strength is applied and rapidly removed, the liquid crystal in the planar state P and the focal conic state FC is mixed, and halftone display becomes possible. [0017] Thus, cholesteric liquid crystal is bistable, and information can be displayed using this phenomenon.

[0018] FIG. 3 is a diagram showing the reflectance characteristics (relationship between voltage and reflectance) of cholesteric liquid crystal, and collectively shows the voltage responsiveness of cholesteric liquid crystal described with reference to FIGS. 2A to 2C. is there.

[0019] As shown in Fig. 3, if the initial state is the planar state P (the portion with high reflectivity at the left end of Fig. 3), the pulse voltage is raised to a certain range, and the drive band to the focal conic state FC is reached. When the pulse voltage is further increased, the driving band for the planar state P (the portion with the highest voltage at the right end) is reached again.

[0020] When the initial state is the focal conic state FC (the left end of the reflectance is low !, part), the driving band for the planar state P gradually becomes higher as the pulse voltage is increased.

[0021] In the planar state P, only the right circularly polarized light or the left circularly polarized light is reflected, and the remaining circularly polarized light is transmitted. Therefore, the maximum theoretical reflectance is 50%.

[0022] Conventionally, in a driving method of a liquid crystal display element that displays information by selecting a planar state and a focal conic state, in the fast-forward mode, the display element is operated quickly by phase transition driving (for example, Patent Document 1).

[0023] Further, as a conventional method of driving a display element in a display device using cholesteric liquid crystal, resetting is performed with a predetermined number of scan lines before an image is actually written, and further after a pause is provided. A writing sequence for performing writing has been proposed (see, for example, Patent Document 2). The prior art described in Patent Document 2 and its problems will be described in detail later.

Patent Document 1: Japanese Patent Laid-Open No. 2000-171837

Patent Document 2: Pamphlet of International Publication No. 2005Z024774 (Fig. 55, Fig. 56, and Example 4)

Disclosure of the invention

Problems to be solved by the invention

[0025] As described above, in recent years, electronic paper has been put into practical use, for example, using cholesteric liquid crystal. By the way, in the electronic paper, for example, a specific area in the display area Only rewriting function (partial rewriting function) is required.

[0026] The applicant has filed a patent application relating to a method for driving a liquid crystal display element capable of rewriting a partial screen at high speed (Japanese Patent Application 2005-099711).

FIG. 4A and FIG. 4B are diagrams for explaining an example of a display element driving method of related technology proposed in Japanese Patent Application 2005-099711. 4A and 4B, reference numeral 100 is an original image (existing image), 121 is a driver IC (scan driver) on the scanning side, 122 is a driver IC (data driver) on the data side, and 200 is a partial rewrite. The later image and R0 indicate a partial rewrite area.

[0028] In the original image 100 shown in FIG. 4A, when the partially rewritten region R0 is rewritten and the partially rewritten image 200 shown in FIG. 4B is displayed, the related technique described above displays a normal image. In this case, it is not necessary to scan all areas on the scan side (all scan electrodes) S10 at normal speed and write the image. For example, the scan side area including the rewrite area R0 (rewrite area) Scan electrode corresponding to R0) Scan the S12 at normal speed to write (rewrite) the image, and also include the rewrite area R0 領域 Scan side area (Do not correspond to the rewrite area R0 !, scan electrode : Skip area) S 11 and S 13 are scanned at high speed to maintain the original image.

That is, the scan operation by the scan driver 121 first scans the V ヽ region SI 1 where partial rewriting is performed in the high-speed mode, and when reaching the region R0 where partial rewriting is performed, scans the image by scanning at a normal scanning speed. After rewriting, after scanning of the rewriting area R0, the area S13 where partial rewriting is not performed is scanned in the high speed mode. This speeds up the processing operation for partial image rewriting.

[0030] Here, the voltage output from the data driver 122 is applied to the skip areas (Sl, S13) where rewriting is not performed so as not to affect the display image already written. Although it is most preferable to turn it off, since the response of the liquid crystal becomes dull by increasing the speed, it is possible to scan without turning off the voltage output by utilizing this phenomenon.

FIG. 5 is a diagram for explaining a shift in threshold characteristics due to high-speed scanning.

In other words, in the high-speed mode that scans the region (Sl, SI 3) before and after the rewrite region RO, for example, a force to which a voltage of ± 24V or ± 32V is applied is shown in FIG. Thus, the threshold characteristic during high-speed scanning is greatly shifted (shifted to the high potential side), and specifically, the operating threshold voltage of the cholesteric liquid crystal is shifted to a high voltage of 32V or higher. For example, ± 24V or ± Even when a voltage of 32V is applied, the alignment state (display state) of the liquid crystal does not change. Therefore, in the skip regions Sl and S13, the original image can be maintained as it is by simply scanning at high speed without turning off the voltage output.

As described above, according to the related art display element driving method, when a part of the original image is partially rewritten, it is possible to perform a high-speed rewriting process.

By the way, in driving the cholesteric liquid crystal, it is preferable to apply a reset voltage before writing an actual image. In addition, as a conventional image writing method that consumes less power and can achieve stable contrast, the applicant of the present invention performs a reset with a predetermined scan line before actually writing an image, In the above-mentioned Patent Document 2, a writing sequence for performing writing after providing a pause was proposed.

FIG. 6A to FIG. 6C are diagrams for explaining an example of a conventional display element driving method proposed in the above-described prior art document 2. FIG. 6A to 6C, reference numeral 100 is the previous image (existing image), 121 is the common side driver IC (scan driver), 122 is the segment side driver IC (data driver), and 200 is the new image. Show (image after rewriting)! FIG. 6A shows a state in which the lower half is rewritten with the previous image 100 and the upper half is rewritten with the new image 200. Further, in FIG. 6C, reference symbol Eio indicates a common side selection signal for selecting a scan electrode for writing data by one line, and L p corresponds to each scan electrode (scan line). The data side latch that scans the scan line sequentially and captures the data for one line is shown.

[0035] As shown in FIGS. 6A to 6C, in the past, for example, when rewriting (writing) an image of a cholesteric liquid crystal, immediately before writing a new image, in the same frame as the writing, the reset period RS → pause It has been proposed to perform image writing in the sequence of section PS → writing section WS. In FIG. 6A, reference symbol WT indicates a write start line in the write sequence, PL indicates a pause line, and RL indicates a reset line.

[0036] Here, the reset line RL (reset section RS) has a force of 10 lines depending on the response characteristics of the liquid crystal. About 100 lines (for example, 20 lines) and the reset section WS (reset line RL) is preferably about 50: LO Omse. The pause section PS (pause line) may be about 1 line.

[0037] Since this conventional display element driving method is reset only for a specific number of lines, it can achieve overwhelming power saving compared to the case where the entire screen is reset at once. Thus, a stable and high-contrast display can be obtained.

However, the conventional display element driving method described above has problems to be solved as described below.

FIG. 7A and FIG. 7B are diagrams for explaining problems in an example of a conventional display element driving method. In FIG. 7B, reference symbol RO indicates a partial rewrite area, S21 and S23 indicate areas where high-speed skip (high-speed skip processing) is performed, and S22 indicates high-speed write (high-speed write processing). Show the area to do.

[0040] As shown in FIG. 7A, the conventional display element driving method described above requires a predetermined number of reset lines RL (for example, about 20 lines: reset section RS) preceding the line to be actually written. Therefore, for example, when a part of the display screen (rewrite area RO) as shown in FIG. 7B is rewritten, when the write line reaches near the end of the rewrite area RO, the reset is performed by the reset line RL. The region Rz protrudes outside the rewriting region RO, and the display state of the original image is impaired without performing partial rewriting.

[0041] On the other hand, although it is possible to perform partial rewriting without using the reset, for example, stable writing cannot be performed unless the partial rewriting speed is reduced to 20 m _Sec .Z line or lower. In addition, there was a risk of an unstable partial rewriting in which an afterimage of the display pattern before rewriting occurs due to the type of display pattern and some temperature fluctuations and the original contrast cannot be reached. In other words, in writing without reset processing, it is difficult to perform rewriting unless the writing speed is drastically reduced, as well as the afterimage before rewriting and the contrast decrease. There was a certain shortening of the rewriting time.

[0042] In view of the problems of the above-described conventional display element driving method, the present invention impairs the image quality and the afterimage and the decrease in contrast, compared to the driving method using the reset pulse. It is an object of the present invention to provide a display element driving method and a display device capable of realizing stable partial rewriting without any problems.

Means for solving the problem

[0043] According to the first aspect of the present invention, the apparatus includes a plurality of scan electrodes and a plurality of data electrodes that intersect with each other in an opposing state, and the scan electrodes are selected in a predetermined order and A display element driving method for performing image rewriting processing of a display screen by applying a pulsed voltage to the display medium between the data electrodes, wherein the image rewriting processing includes a reset pulse for initializing the display medium, When a rewrite pulse for rewriting the display medium according to the image data is continuously applied to perform partial rewrite on the existing display image, the partial rewrite area is positioned at the position on the display screen. Accordingly, there is provided a display element driving method characterized by switching the scan direction accordingly.

[0044] According to the second embodiment of the present invention, a plurality of scan electrodes and a plurality of data electrodes intersecting each other in a state of being opposed to each other are provided, and the scan electrodes are selected in a predetermined order and A display element driving method for performing image rewriting processing of a display screen by applying a pulsed voltage to the display medium between the data electrodes, wherein the image rewriting processing includes a reset pulse for initializing the display medium, When the rewriting pulse for rewriting the display medium according to the image data is continuously applied to perform partial rewriting on the existing display image, the reset pulse is used to start the partial rewriting area. A method for driving a display element, characterized in that a time for selecting a line or a termination line is set to an application time longer than a time for not selecting the start line and the termination line. Is provided.

[0045] According to the third aspect of the present invention, a plurality of scan electrodes and a plurality of data electrodes intersecting each other in an opposing state are provided, and the scan electrodes are selected in a predetermined order and A display element that rewrites an image on a display screen by applying a pulsed voltage to a display medium between the data electrodes, a scan driver connected to the scan electrode, and a data driver connected to the data electrode; A reset pulse for initializing the display medium, an image rewrite processing unit for continuously applying a rewrite pulse for rewriting the display medium according to image data, and an existing display image When performing partial rewriting, a display device is provided, comprising: a scanning direction switching unit that switches a scanning direction in accordance with the position of the partial rewriting area on the display screen.

[0046] According to the fourth aspect of the present invention, a plurality of scan electrodes and a plurality of data electrodes intersecting each other in an opposing state are provided, and the scan electrodes are selected in a predetermined order and A display element that rewrites an image on a display screen by applying a pulsed voltage to a display medium between the data electrodes, a scan driver connected to the scan electrode, and a data driver connected to the data electrode; In an existing display image, an image rewrite processing unit that continuously applies a reset pulse for initializing the display medium, and a rewrite pulse for rewriting the display medium according to image data. In the case of performing partial rewriting, the reset pulse indicates the time during which the start line or end line of the partial rewrite area is selected as the start line. The Select end line, Do, long than the time, a processing unit for the application time, the display device according to feature in that it comprises is provided with.

[0047] According to the fifth aspect of the present invention, a plurality of scan electrodes and a plurality of data electrodes intersecting each other in an opposing state are provided, and the scan electrodes are selected in a predetermined order and A display element that rewrites an image on a display screen by applying a pulsed voltage to a display medium between the data electrodes, a scan driver connected to the scan electrode, and a data driver connected to the data electrode; In an existing display image, an image rewrite processing unit that continuously applies a reset pulse for initializing the display medium, and a rewrite pulse for rewriting the display medium according to image data. A scanning direction switching unit that switches a scanning direction in accordance with the position of the partial rewriting area on the display screen when performing partial rewriting. Electronic terminal, characterized in that the application of the display device is provided.

[0048] According to the sixth aspect of the present invention, a plurality of scan electrodes and a plurality of data electrodes intersecting each other in an opposing state are provided, and the scan electrodes are selected in a predetermined order and A display element that rewrites an image on a display screen by applying a pulsed voltage to the display medium between the data electrodes, a scan driver connected to the scan electrodes, and And a data driver connected to the data electrode, wherein the image is continuously applied with a reset pulse for initializing the display medium and a rewrite pulse for rewriting the display medium in accordance with image data. When performing a partial rewrite on an existing display image with a rewrite processing unit, the reset pulse indicates the time when the start line or the end line of the partial rewrite area is selected, the start line and the end line. There is provided an electronic terminal characterized in that a display device including a processing unit for selecting a line and setting an application time longer than the time is applied.

The invention's effect

[0049] According to the present invention, it is possible to provide a display element driving method and a display device capable of realizing stable partial rewriting without impairing image quality in a driving method using a reset pulse.

Brief Description of Drawings

[0050] FIG. 1A is a diagram (part 1) for explaining the alignment state of a cholesteric liquid crystal.

FIG. 1B is a diagram (part 2) for explaining the alignment state of the cholesteric liquid crystal.

FIG. 2A is a diagram (part 1) illustrating voltage characteristics for driving a cholesteric liquid crystal.

FIG. 2B is a diagram (part 2) illustrating voltage characteristics for driving a cholesteric liquid crystal.

FIG. 2C is a diagram (part 3) illustrating voltage characteristics for driving a cholesteric liquid crystal.

FIG. 3 is a graph showing the reflectance characteristics of cholesteric liquid crystal.

FIG. 4A is a diagram (No. 1) for explaining an example of the driving method of the display element according to the related art.

FIG. 4B is a diagram (No. 2) for explaining an example of the driving method of the display element according to the related art.

FIG. 6A is a diagram (No. 1) for explaining an example of the conventional display element driving method;

FIG. 6B is a diagram (No. 2) for explaining an example of the conventional display element driving method;

FIG. 6C is a diagram (No. 3) for explaining an example of the driving method of the conventional display element.

FIG. 7A is a diagram (No. 1) for describing a problem in an example of a conventional display element driving method.

FIG. 7B is a diagram (No. 2) for describing a problem in an example of a conventional display element driving method. FIG. 8A] is a diagram (No. 1) for explaining the principle of the first embodiment in the display element driving method according to the present invention.

FIG. 8B] is a diagram (No. 2) for explaining the principle of the first embodiment in the driving method of the display element according to the present invention.

FIG. 9A is a diagram (No. 1) for explaining the assignment of image memory in the scan direction in an example of the display element driving method according to the invention.

FIG. 9B is a diagram (No. 2) for explaining the allocation of image memory depending on the scan direction in an example of the display element driving method according to the invention.

[10] FIG. 10 is a block diagram schematically showing a first embodiment of the display device according to the present invention.

FIG. 11 is a cross-sectional view schematically showing an example of a display element in the display device shown in FIG. 10. [0112] FIG. 11A is a diagram for explaining an example of a method for driving a display element according to the present invention. FIG. 12B is a diagram for explaining a modification of the display element driving method shown in FIG. 12A. 13A] is a flowchart (No. 1) for explaining an embodiment of the display element driving method according to the present invention.

13B] is a flowchart (No. 2) for explaining an embodiment of the display element driving method according to the present invention.

13C] A flow chart (No. 3) for describing one embodiment of the display element driving method according to the present invention.

14A] A diagram for explaining another embodiment of the display element driving method according to the present invention (

1).

14B] A diagram for explaining another embodiment of the display element driving method according to the present invention

2).

FIG. 15A is a view (No. 1) for explaining still another embodiment of the display element driving method according to the present invention.

FIG. 15B is a diagram (No. 2) for explaining still another embodiment of the display element driving method according to the present invention.

FIG. 16 is a diagram schematically showing a main part of a second embodiment of the display device according to the present invention. FIG. 17 is a diagram schematically showing a main part of a third embodiment of the display device according to the present invention.

FIG. 18A is a diagram showing an example of an input voltage to the driver in the scan mode and the data mode.

FIG. 18B is a diagram showing an example of correspondence when driving a cholesteric liquid crystal.

FIG. 18C is a diagram showing an example of the output voltage of the driver in the scan mode and the data mode.

FIG. 18D is a diagram showing an example of a composite waveform applied to the liquid crystal.

Explanation of symbols

1 Display element

3 Power supply circuit

4 Control circuit

11, 12 Finorem PCB

13, 14 Transparent electrode (ITO)

15 Liquid crystal composition (cholesteric liquid crystal)

16, 17 Sinore wood

18 Light absorption layer

19 Drive circuit

21; 211, 212, 213, 214; 2101, 2102, 2103 Scan dryer IC (scan driver)

22; 221, 222, 223, 224; 2201, 2202, 2203 Data driver IC (data driver)

31 Booster

32 Voltage generator

33 Regulator

41 Partial rewrite input section

42 Image data generator

43 Location information generator

44 Data conversion circuit (image rewrite processing section 'scan direction switching section) 100 original image (existing image)

101 Blue (B) layer

102 Green (G) layer

103 Red (R) layer

121 Scan-side driver IC

122 Data side driver IC

200 Image after partial rewriting

FC focal conic state

H

P Planar state

RO, Rl, R2, R3, R4 Partial rewrite area

BEST MODE FOR CARRYING OUT THE INVENTION

First, the principle of the first embodiment in the display element driving method according to the present invention will be described.

8A and 8B are views for explaining the principle of the first embodiment in the display element driving method according to the present invention.

In the display element driving method according to the present invention, the partial rewrite is performed from the start point to the end of the display screen by rewriting the reset pulse and the write pulse in the same frame as in the case of the full rewrite.

As shown in FIG. 8A, for example, when the position of the partial rewrite region R1 is the lower side in the display screen 300, the scanning direction is the direction in which the force is applied from the top to the bottom (S31 → S32). On the other hand, as shown in FIG. 8B, for example, when the position of the partial rewrite region R1 is the upper side in the display screen 300, the scan direction is the direction in which the force is applied from the bottom to the top (S34 → S33). Here, reference numerals S31 and S34 indicate areas where high-speed skip processing is performed, and S32 and S33 indicate areas where high-speed writing is performed!

FIG. 9A and FIG. 9B are diagrams for explaining image memory allocation according to a scan direction in an example of a display element driving method according to the present invention.

[0056] As shown in FIG. 9A, for example, when the partial rewrite region R11 "Tomorrow's weather is fine" is located in the lower part of the display screen 301, the scan direction is the direction in which the scan direction is directed from top to bottom. become. At this time, for example, the data driver 22 reads the image data of the partial rewrite area R11 stored in the memory as usual in the normal order, that is, the data read with the upper left of the image data as the address 0. Is transferred.

On the other hand, as shown in FIG. 9B, for example, when the partial rewrite area Rl 1 of “Tomorrow's weather clear” is located in the upper part of the display screen 301, the scan direction is from the bottom to the top. The direction becomes the direction of force. At this time, for example, the data read from the partial rewrite area R11 stored in the memory in the reverse direction is transferred to the data driver 22, that is, the data read with the lower left of the image data as the address 0 is transferred. Is done.

In this way, the access procedure for the address of the image data in the partial rewrite area R11 is also switched according to the switching of the scanning direction.

As described above, according to the present invention, it is possible to prevent display loss other than the rewrite region R 1 due to the protrusion of the reset line described above, and to realize stable partial rewrite without any afterimage or contrast deterioration. It becomes possible.

Example

Hereinafter, embodiments of a display element driving method and a display device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 10 is a block diagram schematically showing a first embodiment of a display device (electronic terminal) according to the present invention. In FIG. 10, reference numeral 1 is a display element, 3 is a power supply circuit, 4 is a control circuit, 5 is an inverter, 21 is a scan driver IC (scan driver), and 22 is a data driver IC (data driver). Show me! /

As shown in FIG. 10, the power supply circuit 3 includes a booster 31, a display element drive voltage generator (voltage generator) 32, and a regulator 33. For example, the booster 31 receives an input voltage of about +3 to +5 V from the battery, boosts the voltage to drive the display medium (display element 1), and supplies the boosted voltage to the voltage generator 32. The voltage generation unit 32 generates necessary voltages for the scan driver 21 and the data driver 22, respectively, and the regulator 33 stabilizes the voltage from the voltage generation unit 32 and supplies it to the scan driver 21 and the data driver 22. Supply

[0063] The control circuit 4 includes a partial rewrite input unit 41, an image data generation unit 42, and a position information generation unit 43. And a data conversion circuit 44. The control circuit 4 calculates image data and control signals supplied from the outside, and when the image pattern to be partially rewritten and the position in the display screen to which it is input are input, the data conversion circuit 44 converts the information into the information. The scanning direction of the scan driver 21 is determined accordingly, and the image data input to the driver 21 is rearranged as necessary.

That is, the partial rewriting input unit 41 recognizes partial rewriting from image data and control signals supplied from the outside, and generates image data of an area where partial rewriting is performed by the image data generating unit 42, as well as the position. The information generation unit 43 generates position information of the area to be partially rewritten (position information on the display area of the rewrite area). The image data and position information in the rewrite area are input to the data conversion circuit 44, and the scan direction signal CS1, the data capture clock CS2, the pulse polarity control signal CS3, and the frame start signal CS4 that determine the scan direction of the scan driver 21 described above. , Data latch 'scan shift signal CS5 and driver output cutoff signal CS6 are output.

[0065] Here, the data capture clock CS2 is supplied to the driver set in the data mode, and is a signal for sequentially capturing data for one line (in the case of partial rewriting, data in the area to be rewritten). The pulse polarity control signal CS3 is a signal for inversion control of the polarity of the pulse voltage applied to the display element 1, and the frame start signal CS4 is a signal indicating the start of an image of one frame. The latch 'scan shift signal CS5 is a signal for controlling the synchronization of the line in which data is stored by the data driver and the line selected by the scan driver, and the driver output cutoff signal CS6 is the data driver. This is a signal for cutting off the driver output of the bus or scan driver.

[0066] That is, when a part of the existing display image is rewritten, if the rewritten area is in the lower part of the display screen, the scan direction is the direction from the top to the bottom of the display screen. If the partial rewrite area is in the upper part of the display screen, the scan direction is the upward force direction on the lower force of the display screen. The display element driving method according to the present invention will be described in detail later.

FIG. 11 is a cross-sectional view schematically showing an example of the display element (liquid crystal display element) in the display device shown in FIG. In FIG. 11, reference numerals 11 and 12 are film substrates, and 13 And 14 are transparent electrodes (for example, ITO), 15 is a liquid crystal composition (cholesteric liquid crystal), 16 and 17 are sealing materials, 18 is a light absorbing layer, and 19 is a drive circuit.

[0068] The display element 1 includes the liquid crystal composition 15, and the transparent electrodes 13 and 12 that intersect perpendicularly on the inner surfaces of the transparent film substrates 11 and 12 (the surfaces in which the liquid crystal composition 15 is sealed), respectively. 14 are formed. That is, a plurality of scan electrodes 13 and a plurality of data electrodes 14 are formed in a matrix on opposing film substrates 11 and 12. In FIG. 11, the scan electrode 13 and the data electrode 14 are drawn so as to be parallel at first glance. However, actually, for example, a plurality of data electrodes 14 intersect one scan electrode 13. Needless to say. Furthermore, the thickness of each of the film substrates 11 and 12 is, for example, about 0.2 mm, and the thickness of the layer of the liquid crystal composition 15 is, for example, about 3 μm to 6 μm. Those ratios are ignored for illustration.

[0069] Here, it is preferable that the electrodes 13 and 14 are coated with an insulating thin film or an alignment stability film. In addition, a visible light absorbing layer 18 is provided on the outer surface (back surface) of the substrate (12) opposite to the side on which light is incident, as necessary.

In this example, the liquid crystal composition 15 is a cholesteric liquid crystal that exhibits a cholesteric phase at room temperature, and these materials and combinations thereof will be specifically described by the following experimental examples.

The sealing materials 16 and 17 are for sealing the liquid crystal composition 15 between the film substrates 11 and 12. The drive circuit 19 is for applying a predetermined pulse voltage to the electrodes 13 and 14.

[0072] The film substrates 11 and 12 both have translucency. At least one of the pair of substrates that can be used as the display element 1 of this example has translucency. It is necessary. As the substrate having translucency, a glass substrate can be exemplified, but a flexible resin film substrate such as PET or PC can be used in addition to the glass substrate. In addition, as the electrodes 13 and 14, for example, ITO (Indium Tin Oxide) is a representative force. In addition, for example, a transparent conductive film such as IZO (Indium Zinc Oxide), Alternatively, a metal electrode such as aluminum or silicon, or a photoconductive film such as amorphous silicon or BSO (Bismuth Silicon Oxide) is used. It can be done.

In the liquid crystal display element shown in FIG. 11, a plurality of strip-like transparent electrodes 13 and 14 parallel to each other are formed on the inner surfaces of the transparent film substrates 11 and 12 as described above. 13 and 14 face each other so as to cross each other with reference to the direction force perpendicular to the substrate.

[0074] In the display element according to the present invention, an insulating thin film having a function of preventing a short circuit between the electrodes or improving the reliability of the liquid crystal display element as a gas barrier layer may be formed. In addition, as the orientation stabilizing film, an organic film such as polyimide resin, polyamideimide resin, polyetherimide resin, polybutylpropylene resin, and acrylic resin, or silicon oxide, acid resin An inorganic material such as aluminum can be exemplified. Note that the orientation stable film coated on the electrodes 13 and 14 can also be used as an insulating thin film.

[0075] In the liquid crystal display element according to the present invention, a spacer may be provided between the pair of substrates to keep the inter-substrate gap uniform. Examples of the spacer include spheres made of resin or inorganic acid. Further, a fixed spacer whose surface is coated with a thermoplastic resin can also be suitably used.

[0076] The substance constituting the liquid crystal composition (liquid crystal layer) 15 is, for example, cholesteric liquid crystal in which 10 to 40 wt% of a chiral agent is added to the nematic liquid crystal composition. Here, the addition amount of the chiral agent is a value when the total amount of the nematic liquid crystal component and the chiral agent is 100 wt%.

[0077] Various types of conventionally known nematic liquid crystals can be used as the nematic liquid crystal. It is preferable in view of driving voltage that the dielectric constant anisotropy is 20 or more. That is, when the dielectric anisotropy is 20 or more, the drive voltage is relatively low. The dielectric anisotropy (Δε) of the cholesteric liquid crystal composition is preferably 20 to 50. Within this range, general-purpose drivers can be used.

Further, the refractive index anisotropy (Δη) is preferably 0.18 to 0.24. If it is smaller than this range, the reflectivity in the planar state will be low, and if it is larger than this range, the scattering reflection in the focal conic state will increase, and the response speed will decrease as the viscosity increases. The thickness of this liquid crystal is about 3 111 to 6 111. The reflectance of the state becomes low, and if it is larger than this, the driving voltage becomes too high, which is not preferable.

FIG. 12A is a diagram for explaining one embodiment of a display element driving method according to the present invention, and FIGS. 13A to 13C are one embodiment of a display element driving method according to the present invention. It is a flowchart for demonstrating.

In FIG. 12A, the common side (scan driver 21) is composed of two scan drivers 211 and 212. FIG. Note that the flowcharts shown in FIGS. 13A to 13C explain the operation when only two scan drivers shown in FIG. 12A are provided.

[0081] First, in step ST1, partial rewrite conditions, that is, image data Example.dat (u, v) are set. Next, proceeding to step ST2, the image data Example.dat (u, v) is stored in the memory, and further proceeding to step ST3, the rewrite position is stored in the memory. Then, proceeding to step ST4, it is determined whether or not the position of the partially rewritten image (partially rewritten region R2) is a force straddling the two scan drivers 211 and 212.

[0082] In step ST4, when it is determined that the position of the partial rewrite region R2 crosses the two scan drivers 211 and 212, the process proceeds to step ST5, where the first scan driver 211 starts partial rewrite, Proceed to ST6. Here, when the position of the partial rewrite area R2 straddles the two scan drivers 211 and 212, it is a case where the rewrite area R2 is located below the display screen corresponding to the first scan driver 211. The scanning direction of the driver 211 is a direction in which it is directed downward from the top of the display screen. It should be noted that the scan direction that is directed from the top to the bottom is determined in advance as the basic scan direction.

[0083] In step ST6, the first scan driver 211 performs high-speed skip processing of the region S41, and further proceeds to step ST14 where the first scan driver 211 corresponds to a part of the rewrite region R2. Start image writing to S42.

Further, in step ST 15, image data Example. Dat (u, v) is input to the data driver 22. In this case, the memory access order is forward, and the coordinate data (0, 0), (1, 0), (0, 0), (2, 0), ···, (u— 1, 0); (0, 1), (1, 1), (2, 1), ···, (u— 1, 1); …… ; (0, v— 1), (1, V— 1), (2, V— 1),..., (U— 1, V— 1) in order to correspond to each scan line in area S42 Write to data driver 22. Then, the process proceeds to step ST16, and the voltage pulse output (32V or 24V) is applied to the corresponding data electrode. The process proceeds to step ST17, and the writing by the first scan driver 211 is completed.

Next, proceeding to step ST 26, the scanning direction of the second scan driver 212 is switched to the direction of the upward force on the lower force of the display screen opposite to the basic scanning direction. Here, when the position of the partial rewrite area R2 straddles the two scan drivers 211 and 212, it is a case where the rewrite area R2 is located above the display screen corresponding to the second scan driver 212. The scanning direction of the driver 212 is directed from the bottom to the top of the display screen.

[0087] Further, the process proceeds to step ST27, where the second scan driver 212 performs the high-speed skip processing of the region S44, and further proceeds to step ST28, where the second scan driver 212 performs a part of the rewrite region R2. Image writing to the area S43 corresponding to is started.

Furthermore, in step ST 29, image data Example. Dat (u, v) is input to the data driver 22. In this case, the memory access order is upside down, and image data stored in memory Example.dat (u, v) Coordinate data (0, v—l), (1, v—l), (2, v—l), ···, (u- 1, v—l); (0, v- 2), (1, v— 2), (2, v— 2) , ..., (u- 1, v- 2); ... (0, 0), (1, 0), (2, 0), ..., (u-l, 0 ) Are sequentially written to the data driver 22 corresponding to each scan line in the region S43.

Then, the process proceeds to step ST30, the voltage pulse output (32V or 24V) is applied to the corresponding data electrode, the process proceeds to step ST31, the writing by the second scan driver 212 is terminated, and Proceeding to step ST32, the partial rewriting (writing of the rewriting area R2) is completed.

[0090] On the other hand, in step ST4, the position of the partial rewrite area (R2) does not cross the two scan planes 211 and 212, that is, the partial rewrite area is within the area of one scan driver. If it is determined that it is included, the process proceeds to step ST7, where it is determined whether the partial rewrite area is included in the area of the first scan driver 211 or whether it is included in the area of the second scan driver 212. Proceed to ST8. In step ST8, whether or not the partial rewrite area force has a long distance to the data driver 22, that is, whether the partial rewrite area is From the top to the top of the display screen ≥ partial rewrite area force The bottom length to the bottom of the display screen is determined.

[0091] If it is determined in step ST8 that the upper length ≥ the lower length, that is, the first or second scan driver (rewrite area) that scans the area including the partial rewrite area. If it is determined that the partial rewrite area is below the display screen corresponding to the scan driver including the rewrite area, the process proceeds to step ST9, and the partial rewrite is performed with the scan driver including the rewrite area. And proceed to step ST10.

[0092] In step ST10, high-speed skip processing is performed by the scan driver including the rewrite area, and the process proceeds to step ST18, where image writing is started by the scan driver including the rewrite area, and further, the process proceeds to step ST19. Input the image data Example.dat (u, V) to the data driver 22. In this case, the memory access order is forward as in step ST15 described above.

[0093] Then, the process proceeds to step ST20, and the voltage pulse output (32V or 24V) is applied to the corresponding data electrode. The process proceeds to step ST21, and the writing by the scan driver including the rewrite area is terminated. Proceed to and end the partial rewriting.

[0094] If it is determined in step ST8 that the upper length is not the lower length, that is, the partial rewrite area is in the display screen corresponding to the scan driver including the rewrite area. If it is determined that the position is above, the process proceeds to step ST11, and the scan direction of the scan driver including the rewrite area is switched from the bottom of the display screen to the direction opposite to the basic scan direction, and the process proceeds to step ST12. .

[0095] In step ST12, partial rewriting is started by the scan driver including the rewriting area, and the process proceeds to step ST13. The high-speed skip processing is performed by the scan driver including the rewriting area, and the process proceeds to step ST22. Image writing is started by the included scan driver.

[0096] Further, proceeding to step ST23, the image data Example.dat (u, v) is transferred to the data driver 2

Enter in 2. In this case, as in step ST29 described above, the memory access order is the upside down direction. [0097] Then, the process proceeds to step ST24, and the voltage pulse output (32V or 24V) is applied to the corresponding data electrode. The process proceeds to step ST25, and the writing by the scan driver including the rewrite area is terminated. Proceed to and end the partial rewriting.

FIG. 12B is a diagram for explaining a modification of the method for driving the display element shown in FIG. 12A. The above description is based on two scan drivers 211 and 212 on the common side as shown in FIG. 12A. The force described for a display element composed of one data driver 22 with the segment side provided at one end (upper end) of the display screen. For example, the common side as shown in FIG. The present invention can be similarly applied to a display element constituted by two data drivers 221 and 222 which are configured by the scan drivers 211 and 212 and the segment side is provided at both ends (upper and lower ends) of the display screen.

Note that in the display element having two scan drivers 211 and 212 as shown in FIG. 12B, the first write process by the first scan driver 211 and the first data driver 221 and the second It is also possible to perform the second writing process by the scan driver 212 and the second data driver 222 in parallel (simultaneously). That is, in the display element (display device) shown in FIG. 12B, the first scan driver 211 performs the high-speed skip processing in the scan direction (downward) from the top to the bottom of the region S45 and the region by the second scan driver 212. Simultaneously performs high-speed skip processing in the scan direction (upward) from the bottom to the top of area S48, and also performs high-speed write processing in the downward direction of area S46 by first scan driver 211 and second scan driver 212. By simultaneously performing the upward high-speed writing process in the area S47, the time required for partial rewriting can be further reduced.

FIG. 14A and FIG. 14B are diagrams for explaining another embodiment of the display element driving method according to the present invention.

FIG. 14A shows the common side (scan driver 21) configured with four scan drivers 211 to 214, and FIG. 14B shows the common side with four scan drivers 211 to 214 as in FIG. 14A. The segment side (data driver 22) that is simply configured is also composed of two data drivers 221 and 222 provided at the upper and lower ends of the display screen.

[0102] The first to fourth scan drivers 211 to 214 and the partial rewrite image (partial rewrite area) When the positional relationship of (R3) is as shown in FIG. 14A, for example, the high-speed skip processing of the area S51 downward by the first scan driver 211 and the downward movement of the area S52 by the second scan driver 212 are sequentially performed. Performs high-speed skip processing, downward high-speed writing processing of area S53 by the second scan driver 212, and downward high-speed writing processing of area S54 by the third scan driver 213, and then the area by the fourth scan driver 214. The upward high-speed skip processing of S5 6 and the upward high-speed writing processing of the area S55 by the fourth scan driver 214 are performed.

[0103] Further, when the positional relationship between the first to fourth scan drivers 211 to 214 and the partial rewrite region R3 is as shown in Fig. 14B, for example, the first scan driver 211 sequentially moves downward in the region S61. High-speed skip processing of the area S66 by the fourth scan driver 214 and the high-speed skip processing of the area S66 by the second scan driver 212 and the fourth scan driver Simultaneously performs upward high-speed write processing of area S65 by 214 and downward high-speed write processing of area S63 by second scan driver 212 and upward high-speed write processing of area S64 by third scan driver 213 It will be.

[0104] As described above, there may be a plurality of common-side scan drivers, and the segment-side data driver may be one at one end of the display screen or two at both ends of the display screen. Good.

[0105] Note that, for example, several lines from the write start line of partial rewriting have a predetermined number of lines because there is not enough force to directly apply a write pulse without being given a reset pulse or the number of lines to which a reset pulse is given. Display characteristics may not be obtained. Therefore, for example, it is preferable to increase the pulse application time by reducing the scan speed or the force to apply the reset pulse in advance only to the line to which the J set pulse is not applied.

By the way, as described above with reference to FIG. 7B and the like, in the conventional display element driving method, when a part of the display screen (rewrite region RO) is rewritten, the write line is in the rewrite region RO. When reaching the end, the area Rz reset by the reset line RL protrudes outside the rewriting area RO, and the display state of the original image without partial rewriting is impaired. When performing partial rewrite without resetting, for example, write The speed of rewriting must be greatly reduced, and the rewriting time, which is the original merit of partial rewriting, cannot be shortened.

FIG. 15A and FIG. 15B are diagrams for explaining still another embodiment of the display element driving method according to the present invention.

[0108] The display element driving method of the present embodiment is characterized in that the reset period and the writing period are performed in different frames (frame division) at the time of partial rewriting.

That is, as shown in FIG. 15A, first, in the first frame, for example, the high-speed skip processing of region S71 is performed in the scan direction from top to bottom, and then the partial rewrite region R4 is supported. A reset process for the scan line (area S72) to be performed is performed, and a high-speed skip process for the area S73 is further performed. Thereby, for example, in a display element using cholesteric liquid crystal, the region S72 corresponding to the partial rewrite region R4 is in a planar state.

[0110] Then, in the next second frame, for example, high-speed skip processing of the region S71 is performed in the scan direction that is directed from top to bottom, and then the rewritten image of the rewritten image in the region S72 corresponding to the partial rewrite region R4. Perform high-speed write processing, and then perform high-speed skip processing for area S73.

[0111] While the partial rewrite region is scanned, the difference voltage between the scan electrode and the data electrode is set to be equal to or lower than the response value voltage of the display medium (for example, cholesteric liquid crystal).

[0112] Thus, it is possible to prevent the reset area (Rz) from protruding from the rewritten area. In addition, since the number of selected lines is limited in the reset section, the power consumption can be increased and suppressed.

[0113] Also in this case, for example, the number of lines from the beginning of partial rewriting and the number of lines at the end of writing before writing cannot obtain the predetermined display characteristics because the number of reset lines is insufficient at a certain scanning speed. It is possible. Therefore, when the reset pulse is selected by selecting the start line and end line for partial rewriting, it is effective to reduce the scan speed and increase the pulse application time to compensate for the reset effect. The reset time is the scan speed X the number of reset lines.

[0114] In FIG. 16, reference numeral 101 is a blue (B) layer that reflects blue light, 102 is a green (G) layer that reflects green light, and 103 is red (R) that reflects red light. ) Layer. In addition A black (K) layer that absorbs light may be provided under the R layer 103.

[0115] As shown in FIG. 16, the display device of the second embodiment includes scan drivers 2101, 2102 and 2103, and a data dryer 2201 for the B layer 101, the G layer 102 and the R layer 103, respectively. , 2202 and 2203 forces are provided. In each of the layers 101, 102, and 103, they are connected to the scan drivers 2101, 2102, and 2103, and the data drivers 2201, 2202, and 2203, respectively, and intersect each other with the cholesteric liquid crystal (display medium) interposed therebetween. The scan electrode and the data electrode allow the display element 1 to display near the full power error.

FIG. 17 is a diagram schematically showing the main part of a third embodiment of the display device according to the present invention.

As shown in FIG. 17, the display device of the third embodiment has a common scan driver 21 and individual data drivers 2201, 2 202 and B layer 101, G layer 102 and R layer 103. 2203 is waiting for you!

In this way, by sharing the scan driver in the B layer 101, the G layer 102, and the R layer 103, the number of drivers and the like can be reduced and the cost can be reduced.

Hereinafter, the drive voltage of the color display element of Q VGA manufactured by applying the display device of the second embodiment shown in FIG. 16 will be described with reference to FIGS. 18A to 18D. Note that general-purpose STN drivers were used as the scan drivers 2101 to 2103 and the data drivers 2201 to 2203. If necessary, an operational amplifier voltage follower may be applied to stabilize the voltage input to each driver.

FIG. 18A is a diagram showing an example of the input voltage to the driver in the scan mode and the data mode, FIG. 18B is a diagram showing an example of correspondence when driving the cholesteric liquid crystal, and FIG. 18C is a diagram in the scan mode and the data mode. FIG. 18D is a diagram showing an example of the output voltage of the driver, and FIG. 18D is a diagram showing an example of a composite waveform applied to the liquid crystal.

First, as shown in FIG. 18A and FIG. 18B, any line can be selected in the data mode (segment mode: data driver), and a high level “ The AC signal of “H” is the voltage VO (32V), the AC signal of the low level “L” is the voltage V5 (0V), and the low level “L” data signal is the high level “H”. As an AC signal, the voltage V21 (28V) and as a low-level “L” AC signal, the voltage V34 Use (4V).

[0121] Also, in scan mode (common mode: scan dry), it is not possible to select an arbitrary line. All lines are scanned, and a high level "H" is applied to a high level "H" data signal. AC signal with voltage V5 (OV) and low level “L” AC signal with voltage VO (32 V) and low level “L” data signal with high level “H” AC signal The voltage V21 (28V) and the low level “L” AC signal use the voltage V34 (4V). Here, the relationship V0≥V21≥V34≥V5 is established.

[0122] In each of the RGB elements (R layer 103, G layer 102, and B layer 101), a pulse voltage of ± 32V is stably applied to the on pixel and ± 24V is stably applied to the off pixel. A pulse voltage of ± 4V is applied to the pixel. That is, as shown in FIG. 18B, the scan driver (common driver: COM) and the data driver (segment driver: SEG) are, for example, 32V, 28V, 24V, 8V generated by the power supply circuit 3 in FIG. , 4V and 0V are input.

Therefore, 32V, 28V, 4V, and 0V are input to the driver in scan mode, and 32V, 24V, 8V, and 0V are input to the driver in data mode. When switching modes, each voltage input to those drivers is also switched.

[0124] As shown in Figure 18C, the output voltage when the scan driver is on and off is ON.

COM is 0V in the first half of AC drive, 32V in the second half, and OFF— COM is 28V in the first half of AC drive and 4V in the second half, and the output voltage when the data driver is on and off is ON— The first half of AC drive is 32V and 0V in the second half, and the OFF—SEG is 24V in the first half of AC drive and 8V in the second half.

[0125] Then, as shown in FIG. 18D, for the liquid crystal (pixel) between each scan electrode and each data electrode, the first half AV11 of the AC drive is 32V and the second half AV21 is 32V The first half of AC drive AV12 is 24V and the second half AV22 is 24V, and the second half AV22 is 4V. In the second half AV23, a pulse waveform of -4V is applied, and in the non-selected off liquid crystal, the first half of AC drive AV14 is -4V and the second half AV24 is a 4V pulse. A waveform will be applied.

[0126] It should be noted that the area where partial rewriting is performed is scanned at a speed of approximately 10 msec, for example, and the non-target area where partial rewriting is not performed is instantaneously scanned at a scanning speed of, for example, about sec.Z line. Will end. Note that when scanning non-target areas, it is preferable to turn off the voltage output from the driver. However, if the voltage is lower than the response voltage of the liquid crystal (pixel) in high-speed scanning, the previous image is maintained, which is a problem. There is no.

As described above, the present invention can be applied to, for example, a display element capable of full color display in which the B layer 101, the G layer 102, and the R layer 103 are stacked, and a partially rewritten image (rewrite) For example, it is also possible to rewrite only the G layer 102 if it is possible to perform full color rewriting by rewriting all layers.

Industrial applicability

[0128] The present invention is not limited to cholesteric liquid crystals, and is widely applicable to, for example, electronic devices using other liquid crystals that require reset processing before rewriting processing, and electronic terminals having a display device using the same. Can be applied.

Claims

The scope of the claims

[1] comprising a plurality of scan electrodes and a plurality of data electrodes intersecting each other in a state of being opposed to each other, selecting the scan electrodes in a predetermined order, and applying a pulse voltage to a display medium between the scan electrodes and the data electrodes A display element driving method for applying image to rewrite the display screen image,

The image rewriting process continuously applies a reset pulse for initializing the display medium and a rewrite pulse for rewriting the display medium according to image data,

A display element driving method characterized in that, when partial rewriting of an existing display image is performed, the scanning direction is switched in accordance with the position of the partial rewriting area on the display screen.

[2] In the driving method of the display element according to claim 1,!

The display element driving method, wherein the reset pulse and the rewrite pulse are applied to the partial rewrite region within the same frame.

[3] In the display element driving method according to claim 1 or 2,

When the partial rewrite area is at the lower side in the display screen corresponding to the scan driver, the scan direction of the scan driver is set to the direction from the top to the bottom of the display screen, and the When the partial rewrite area is above the display screen corresponding to the scan driver, the scan direction of the scan driver is set to be a direction in which the downward force on the display screen is directed upward. Display element driving method.

[4] A plurality of scan electrodes and a plurality of data electrodes intersecting each other in a state of being opposed to each other, and selecting the scan electrodes in a predetermined order and applying a pulse voltage to a display medium between the scan electrodes and the data electrodes A display element driving method for applying image to rewrite the display screen image,

When performing partial rewriting in an existing display image, the reset pulse selects the start line and the end line for the time during which the start line or end line of the partial rewrite area is selected. Characterized by longer application time than no application time A display element driving method.

[5] In the display element driving method according to claim 4,

The number of selected lines of the reset pulse is equal to or less than the number of partial rewrite lines.

[6] In the display element driving method according to claim 5,

The display element driving method, wherein the reset pulse and the rewrite pulse are applied to the partial rewrite region in different frames.

[7] The method for driving a display element according to claim 1 or 4,

The display element driving method, wherein the reset pulse causes the partial rewrite region to be in a planar state.

[8] A plurality of scan electrodes and a plurality of data electrodes intersecting each other in a state of being opposed to each other, and selecting the scan electrodes in a predetermined order and applying a pulse voltage to the display medium between the scan electrodes and the data electrodes A display device that rewrites an image on a display screen by applying a scan driver, a scan driver connected to the scan electrode, and a data driver connected to the data electrode,

An image rewrite processing unit for continuously applying a reset pulse for initializing the display medium and a rewrite pulse for rewriting the display medium according to image data;

A display device, comprising: a scan direction switching unit that switches a scan direction in accordance with a position of the partial rewrite area on the display screen when performing partial rewrite on an existing display image.

[9] The display device according to claim 8,

The display device includes one scan driver,

When the partial rewrite area is located in the lower part of the display screen corresponding to the scan driver, the scan direction switching unit sets the scan direction of the scan driver to an upward or downward force of the display screen. And when the partial rewrite area is in the upper part of the display screen corresponding to the scan driver, the scan direction of the scan driver is directed upward on the lower force of the display screen. A display device characterized by that.

[10] The display device according to claim 8,

The display device includes a plurality of scan drivers,

When the partial rewrite area is below the display screen corresponding to each scan driver, the scan direction switching unit changes the scan direction of each scan driver from the top to the bottom of the display screen. In the case where the direction is to be applied and the partial rewrite area is above the display screen corresponding to each scan driver, the scan direction of each scan driver is changed from the bottom of the display screen. A display device characterized by being directed upward.

[11] The display device according to claim 10,

The display device includes first and second two data drivers provided at both ends in the display screen,

A first image rewriting process by an arbitrary first scan driver in the first data driver and the plurality of scan drivers, and another second scan in the second data driver and the plurality of scan drivers. A display device that performs a second image rewriting process by a driver at the same time.

[12] A plurality of scan electrodes and a plurality of data electrodes intersecting each other in a state of being opposed to each other, and selecting the scan electrodes in a predetermined order and applying a pulse voltage to a display medium between the scan electrodes and the data electrodes A display device that rewrites an image on a display screen by applying a scan driver, a scan driver connected to the scan electrode, and a data driver connected to the data electrode,

When performing partial rewriting in an existing display image, the reset pulse selects the start line and the end line for the time during which the start line or end line of the partial rewrite area is selected. And a processing unit for applying an application time longer than the non-application time.

[13] The display device according to claim 8 or 12,

The display device is characterized in that the display medium has a memory property.

[14] The display device according to claim 13,

The display device is a liquid crystal forming a cholesteric phase.

[15] The display device according to claim 8 or 12,

The display device has a laminated structure of a plurality of display element units having different reflected light.

[16] An electronic terminal to which the display device according to claim 8 or 12 is applied.