WO2008041290A1 - Élément d'affichage, papier électronique utilisant ledit élément, dispositif de terminal électronique utilisant ledit papier, système d'affichage utilisant ledit dispositif et procédé de traitement d'images de l'élément d'affichage - Google Patents

Élément d'affichage, papier électronique utilisant ledit élément, dispositif de terminal électronique utilisant ledit papier, système d'affichage utilisant ledit dispositif et procédé de traitement d'images de l'élément d'affichage Download PDF

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Publication number
WO2008041290A1
WO2008041290A1 PCT/JP2006/319526 JP2006319526W WO2008041290A1 WO 2008041290 A1 WO2008041290 A1 WO 2008041290A1 JP 2006319526 W JP2006319526 W JP 2006319526W WO 2008041290 A1 WO2008041290 A1 WO 2008041290A1
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WO
WIPO (PCT)
Prior art keywords
display
display element
liquid crystal
state
pixels
Prior art date
Application number
PCT/JP2006/319526
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English (en)
Japanese (ja)
Inventor
Masaki Nose
Hisashi Yamaguchi
Tsuneo Watanuki
Makoto Fukuda
Toshiaki Yoshihara
Original Assignee
Fujitsu Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fujitsu Limited filed Critical Fujitsu Limited
Priority to PCT/JP2006/319526 priority Critical patent/WO2008041290A1/fr
Priority to JP2008537348A priority patent/JP4924610B2/ja
Publication of WO2008041290A1 publication Critical patent/WO2008041290A1/fr

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Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611—Control of matrices with row and column drivers
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1347—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
    • G02F1/13478—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells based on selective reflection
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G02F1/13718—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on a change of the texture state of a cholesteric liquid crystal
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2300/00—Aspects of the constitution of display devices
    • G09G2300/02—Composition of display devices
    • G09G2300/023—Display panel composed of stacked panels
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/06—Details of flat display driving waveforms
    • G09G2310/061—Details of flat display driving waveforms for resetting or blanking

Definitions

  • Display device electronic paper including the same, electronic terminal device including the display device, display system including the display device, and image processing method for the display device
  • the present invention relates to a display element in which a plurality of display units are stacked, an electronic paper including the display element, an electronic terminal device including the display element, a display system including the display device, and an image processing method for the display element.
  • FIG. 12 schematically shows a cross-sectional configuration of a liquid crystal display element 51 capable of full color display using a cholesteric liquid crystal.
  • the liquid crystal display element 51 has a structure in which a blue (B) display unit 46b, a green (G) display unit 46g, and a red (R) display unit 46r are stacked in order as well.
  • the upper substrate 47b side is the display surface, and external light (solid arrow) is incident on the display surface as well as the force above the substrate 47b.
  • the observer's eyes and the observation direction are schematically shown above the substrate 47b.
  • the B display section 46b includes a blue (B) liquid crystal layer 43b sealed between a pair of upper and lower substrates 47b and 49b, and a pulse voltage source 41b that applies a predetermined pulse voltage to the B liquid crystal layer 43b.
  • the G display unit 46g has a green (G) liquid crystal layer 43g sealed between a pair of upper and lower substrates 47g and 49g, and a pulse voltage source 41g that applies a predetermined pulse voltage to the G liquid crystal layer 43g. is doing.
  • the R display unit 46r includes a red (R) liquid crystal layer 43r sealed between a pair of upper and lower substrates 47r and 49r, and a pulse voltage source 41r that applies a predetermined pulse voltage to the R liquid crystal layer 43r.
  • the RU A light absorption layer 45 is disposed on the back surface of the lower substrate 49r of the R display portion 46r.
  • the cholesteric liquid crystal used in each of the B, G, and R liquid crystal layers 43b, 43g, and 43r has a content of several tens wt% of a chiral additive (both chiral materials) in the nematic liquid crystal. It is a liquid crystal mixture added in a relatively large amount. When a relatively large amount of chiral material is contained in the nematic liquid crystal, a cholesteric phase in which the nematic liquid crystal molecular layer is strongly twisted can be formed. Cholesteric liquid crystals are also called chiral nematic liquid crystals.
  • Cholesteric liquid crystal has bistability (memory property), and is in an intermediate state in which a planar state, a focal conic state, or a planar state and a focal conic state are mixed by adjusting the electric field strength applied to the liquid crystal. Either state can be taken. Once the planar state or the focal conic state is reached, the state is stably maintained even in the absence of an electric field.
  • the planar state is obtained by applying a predetermined high voltage between the upper and lower substrates 47 and 49 to give a strong electric field to the liquid crystal layer 43 and then suddenly reducing the electric field to zero.
  • the focal conic state can be obtained, for example, by applying a predetermined voltage lower than the above high voltage between the upper and lower substrates 47 and 49 to apply an electric field to the liquid crystal layer 43 and then suddenly reducing the electric field to zero.
  • a voltage lower than the voltage at which the focal conic state is obtained is applied between the upper and lower substrates 47 and 49 to apply an electric field to the liquid crystal layer 43. After that, the electric field is suddenly made zero.
  • FIG. 13 (a) shows the alignment state of the liquid crystal molecules 33 of the cholesteric liquid crystal when the B liquid crystal layer 43b of the B display section 46b is in the planar state.
  • FIG. 13 (b) shows the alignment state of the liquid crystal molecules 33 of the cholesteric liquid crystal when the B liquid crystal layer 43b of the B display section 46b is in the focal conic state.
  • the liquid crystal molecules 33 in the planar state are sequentially rotated in the substrate thickness direction to form a spiral structure, and the spiral axis of the spiral structure is substantially perpendicular to the substrate surface.
  • light having a predetermined wavelength corresponding to the helical pitch of the liquid crystal molecules is selectively reflected by the liquid crystal layer.
  • the average refractive index n and the helical pitch p are determined so as to be equal to 480 nm.
  • the average refractive index n can be adjusted by selecting a liquid crystal material and a chiral material, and the spiral pitch p can be adjusted by adjusting the content of the chiral material.
  • the liquid crystal molecules 33 in the focal conic state are sequentially rotated in the in-plane direction of the substrate to form a spiral structure, and the spiral axis of the spiral structure is substantially on the substrate surface. Become parallel.
  • the selectivity of the reflected wavelength is lost in the B liquid crystal layer 43b, and most of the incident light is transmitted. Since the transmitted light is absorbed by the light absorption layer 45 disposed on the back surface of the lower substrate 49r of the R display portion 46r, a dark (black) display can be realized.
  • the cholesteric liquid crystal As described above, in the cholesteric liquid crystal, reflection and transmission of light can be controlled by the alignment state of the liquid crystal molecules 33 twisted in a spiral shape. In the same manner as the above-mentioned liquid crystal layer 43b for B, full-color display is performed by sealing the cholesteric liquid crystal that selectively reflects green or red light in the planar state to the liquid crystal layer 43g for G and the liquid crystal layer 43r for R respectively.
  • the liquid crystal display element 51 is manufactured.
  • FIG. 14 shows an example of the reflection spectrum of each liquid crystal layer 43b, 43g, 43r in the planar state.
  • the horizontal axis represents the wavelength (nm) of the reflected light, and the vertical axis represents the reflectance (white plate ratio;%).
  • the reflection spectrum at the liquid crystal layer 43b for B is shown by the curve connecting the ⁇ marks in the figure.
  • the reflection spectrum at the G liquid crystal layer 43g is indicated by a curve connecting the country marks
  • the reflection spectrum at the R liquid crystal layer 43r is indicated by a curve connecting the ⁇ marks.
  • the center wavelength of the reflection spectrum in the planar state of each of the liquid crystal layers 43b, 43g, and 43r becomes longer in the order of B, G, and R. Therefore, the spiral pitch of the cholesteric liquid crystal is Layers 43b, 43g, and 43r become longer in this order. Therefore, the chiral material content of the cholesteric liquid crystals in the liquid crystal layers 43b, 43g, and 43r needs to be decreased in the order of the liquid crystal layers 43b, 43g, and 43r.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2004-219715
  • Patent Document 2 JP 2002-139746
  • a liquid crystal display element using cholesteric liquid crystal has a strong effect of “burn-in” when a still image is displayed for a long period of time, even if it is updated to a different image. ”Occurs.
  • Various factors such as moisture, ionic impurities, or compatibility between the liquid crystal and the substrate interface are speculated as causes of seizure.
  • extremely high stability is required for the purity of the material and the interface state.
  • a liquid crystal display element is provided with a timer and a light sensor, and the entire screen is in a standby state by detecting the passage of continuous operation time or the liquid crystal display element being placed in a dark environment.
  • Patent Document 1 since the seizure phenomenon is more intense as the environmental temperature is higher, when the temperature sensor detects a temperature higher than a predetermined temperature, for example, a seizure prevention pattern in which the entire screen becomes black is displayed. Thus, a method for preventing image sticking by bringing the liquid crystal into a focal conic state is disclosed. However, if an anti-seize pattern is displayed on the display screen, the image displayed up to that point will disappear temporarily. For this reason, the problem that the convenience of a display element falls remarkably arises.
  • Patent Document 2 discloses a method of reducing power consumption by dividing a common electrode at each digit in a 7-segment monochrome display. Patent Document 2 discloses that a display element is initialized to prevent image sticking. However, Patent Document 2 discloses only a 7-segment monochrome display, and there is no idea about a dot matrix type display device capable of color display.
  • An object of the present invention is to provide a display element that provides a display image with excellent display quality and improves convenience, an electronic paper using the display element, an electronic terminal device using the display element, and a display system using the display element. It is to provide. Furthermore, an object of the present invention is to provide an image processing method for a display element, in which a display image with excellent display quality is obtained and convenience is improved.
  • the above object includes a first display unit including a plurality of first pixels, and a plurality of second pixels stacked with the first display unit and arranged to correspond to the plurality of pixels.
  • the second display unit starts rewriting processing on the first display unit and rewrites image data that has already been written while scanning a plurality of pixels.
  • a display element characterized by having a display control unit that controls to start the rewriting process is achieved.
  • the display control unit performs control so that voltage pulses having substantially the same waveform are sequentially applied to the plurality of first or second pixels, so that the first or second The rewriting process is performed on the second display unit.
  • the display element of the present invention together with the first and second display units that reflect light of different colors by showing a light reflecting state, a transmitting state, or an intermediate state thereof, respectively.
  • a plurality of third pixels stacked and arranged corresponding to the plurality of first and second pixels, showing a state of reflecting light, a state of transmitting light, or an intermediate state thereof;
  • the display device further includes a third display portion that reflects light of a different color from the light reflected by the second display portion.
  • the display control unit may select one of the first to third display units that reflects the color closest to the color tone of the display image at a timing independent of the others. Control is performed to start the rewriting process.
  • the display element of the present invention is characterized by further comprising a detection unit that detects a start time of the rewriting process.
  • the detection unit includes a measurement unit for measuring a time interval in which the pixel burn-in can be avoided.
  • the detection unit includes a light detection unit that detects illuminance in an external environment.
  • the display control unit is detected by the light detection unit.
  • the illuminance is lower than a predetermined value, the rewriting process of the first display unit is controlled to start.
  • the first to third display portions have a memory property.
  • each of the first to third display portions includes a pair of substrates arranged opposite to each other and a liquid crystal that is sealed between the substrates and forms a cholesteric phase. It is characterized by.
  • the display control unit resets the already-displayed state of the pixel temporarily to a different display state in the rewriting process, and the reset process.
  • a writing process for writing image data to the pixels so as to be in the same display state as the already-displayed state later is performed.
  • each of the plurality of first and second pixels is a display segment of a segment type display system.
  • an electronic terminal device that displays an image and includes the display element of the present invention.
  • the above object is achieved by a display system characterized in that the display system for displaying an image includes the electronic terminal device of the present invention.
  • the above object is to provide a first display unit including a plurality of first pixels, and a plurality of second pixels stacked with the first display unit and arranged to correspond to the plurality of first pixels.
  • the image processing method of the display element that displays the image by driving the second display unit equipped with the !, rewriting to rewrite the already written image data while scanning a plurality of pixels.
  • the first or second display is performed by controlling so that a voltage pulse having substantially the same waveform is sequentially applied to the plurality of first or second pixels.
  • the rewriting process is performed on the part.
  • the rewriting process is started at a time interval that can avoid the pixel burn-in.
  • the rewriting process of the first display unit is started when the illuminance of the external environment becomes lower than a predetermined value.
  • the reset process is performed to temporarily change the display state of the pixel to a different display state in the rewriting process.
  • a writing process for writing image data to the pixels so as to be in the same display state as the already-displayed state is performed.
  • a display element with excellent display quality can be obtained and convenience can be improved, an electronic paper using the display element, an electronic terminal device using the display element, and a display system using the display element. realizable.
  • FIG. 1 is a diagram showing a schematic configuration of a liquid crystal display element 1 as a display element according to an embodiment of the present invention.
  • FIG. 2 is a diagram schematically showing a cross-sectional configuration of a liquid crystal display element 1 as a display element according to an embodiment of the present invention.
  • FIG. 3 is a diagram showing an example of a driving waveform of a liquid crystal display element 1 as a display element according to an embodiment of the present invention.
  • FIG. 4 is a diagram showing an example of voltage reflectance characteristics of a liquid crystal composition of a liquid crystal display element 1 as a display element according to an embodiment of the present invention.
  • FIG. 5 is a flowchart of an image processing method for a display element according to an embodiment of the present invention.
  • FIG. 6 shows a refresh process using an image processing method for a display element according to an embodiment of the present invention.
  • FIG. 6 is a diagram schematically showing the display unit 6 that is executing the processing.
  • FIG. 7 is a diagram of an example showing a driving method capable of maintaining a relatively high scanning speed in the image processing method for a display element according to an embodiment of the present invention.
  • FIG. 8 is a diagram of an example showing a driving method capable of maintaining a relatively high scanning speed in the image processing method for a display element according to an embodiment of the present invention.
  • FIG. 9 is a diagram of an example showing a driving method capable of maintaining a relatively high scanning speed in the image processing method for a display element according to an embodiment of the present invention.
  • FIG. 10 is a diagram illustrating a method for evaluating burn-in of a display area in an image processing method for a display element according to an embodiment of the present invention.
  • FIG. 11 is a diagram for explaining a method for evaluating burn-in of a display area in an image processing method for a display element according to an embodiment of the present invention.
  • FIG. 12 is a diagram schematically showing a cross-sectional configuration of a conventional liquid crystal display element capable of full color display.
  • FIG. 13 is a diagram schematically showing a cross-sectional configuration of one liquid crystal layer of a conventional liquid crystal display element.
  • FIG. 14 is a diagram showing an example of a reflection spectrum in a planar state of a conventional liquid crystal display element.
  • FIG. 1 to FIG. 11 show a display device, an electronic paper using the display device, an electronic terminal device using the display device, a display system using the display device, and an image processing method of the display device according to an embodiment of the present invention. It explains using.
  • a liquid crystal display element 1 using blue (B), green (G), and red (R) cholesteric liquid crystals will be described as an example of the display element.
  • FIGS. 1 and 2 schematically shows a cross-sectional configuration of the liquid crystal display element 1 cut along a straight line parallel to the horizontal direction in FIG.
  • the liquid crystal display element 1 has a circuit block la and a display block lb.
  • the display block lb is a liquid crystal layer for B that reflects blue light in the planar state 3 B display section 6b with b, G display section 6g with G liquid crystal layer 3g that reflects green light in the planar state, and R liquid crystal layer 3r with red light reflection in the planar state
  • the display unit 6 is composed of an R display unit 6r.
  • the B, G, and R display units 6b, 6g, and 6r are stacked in this order from the light incident surface (display surface) side.
  • the display block lb includes a scan electrode driving circuit 20 and a data electrode driving circuit 21 for driving the display unit 6.
  • the circuit block la has a power supply unit 28 that converts, for example, a DC voltage of 3 to 5 V input from the system side (not shown) into a DC voltage necessary for driving the display block lb.
  • the circuit block la starts rewriting processing for rewriting the already written image data while scanning a plurality of pixels with respect to at least one of the R, G, and B display units 6r, 6g, and 6b.
  • the display control circuit (display control unit) 29 for controlling the remaining display unit to start the rewriting process and generating a predetermined control signal for displaying an image on the display unit 6 Have.
  • the circuit block la includes an image data memory 30 that stores input image data to which system side force is also input, and a detection unit 25 that detects the start timing of the rewriting process of the display unit 6.
  • the power supply unit 28 includes a booster unit 22, a display element drive voltage generation unit 23, and a regulator 24.
  • the step-up unit 22 includes, for example, a DC-DC converter, and boosts the input voltage of 3 to 5 VDC input to the system side force to a voltage of about 30 to 40 VDC necessary for driving the display unit 6.
  • the display element drive voltage generation unit 23 uses the voltage boosted by the boosting unit 22 and the input voltage to generate a plurality of levels of necessary voltages depending on the gradation value of each pixel and whether the selection Z is not selected.
  • the regulator 24 has a Zener diode, an operational amplifier, etc., stabilizes the voltage generated by the voltage generator 23, and supplies it to the scan electrode drive circuit 20 and the data electrode drive circuit 21 provided in the display block lb. It becomes like this.
  • the detection unit 25 includes a timer (measurement unit) 27 and an optical sensor (light detection unit) 26.
  • the timer 27 is used to measure a time interval that can avoid burn-in of the display area of the display unit 6.
  • the optical sensor 26 detects the illuminance of the external environment where the liquid crystal display element 1 is placed.
  • the detection unit 25 outputs the time data measured by the timer 27 and the illuminance data detected by the optical sensor 26 to the display control circuit 29.
  • the display control circuit 29 uses the time data and illuminance data output from the detection unit 25. Thus, a control signal for starting the rewriting process of the display unit 6 is output to the scan electrode driving circuit 20 and the data electrode driving circuit 21.
  • the display control circuit 29 also generates drive data based on the image data for each of the R, G, and B display units 6r, 6g, and 6b read from the image data memory 30 and the preset drive waveform data.
  • the display control circuit 29 outputs the generated drive data to the scan electrode drive circuit 20 and the data electrode drive circuit 21 in accordance with the data fetch clock.
  • the display control circuit 29 outputs control signals such as a scan direction signal, a pulse polarity control signal, a frame start signal, a data latch 'scan shift, and a driver output OFF to both circuits 20 and 21.
  • the B display section 6b provided in the display block lb includes a pair of upper and lower substrates 7b and 9b arranged opposite to each other, and a B liquid crystal sealed between the substrates 7b and 9b.
  • the B liquid crystal layer 3b includes B cholesteric liquid crystal in which the average refractive index n and the helical pitch p are adjusted so as to selectively reflect blue.
  • the G display section 6g includes a pair of upper and lower substrates 7g and 9g arranged opposite to each other, and a G liquid crystal layer 3g sealed between the substrates 7g and 9g.
  • the G liquid crystal layer 3g has a G cholesteric liquid crystal in which the average refractive index n and the helical pitch p are adjusted so as to selectively reflect green.
  • the R display section 6r has a pair of upper and lower substrates 7r, 9r arranged opposite to each other, and an R liquid crystal layer 3r sealed between the substrates 7r, 9r.
  • the R liquid crystal layer 3r has R cholesteric liquid crystal in which the average refractive index n and the helical pitch p are adjusted so as to selectively reflect red.
  • the liquid crystal composition constituting the B, G, R liquid crystal layers 3b, 3g, 3r is a cholesteric liquid crystal in which 10 to 40 wt% of a chiral material is added to a nematic liquid crystal mixture.
  • the additive rate of chiral material is the value when the total amount of nematic liquid crystal component and chiral material is 100 wt%.
  • As the nematic liquid crystal various conventionally known liquid crystals can be used.
  • the dielectric anisotropy of the cholesteric liquid crystal composition ⁇ force 20 ⁇ ⁇ ⁇ 50 is preferable. If the dielectric anisotropy ⁇ is 20 or more, the selection range of usable chiral materials is widened.
  • the dielectric anisotropy ⁇ is too lower than the above range, the driving voltage of each liquid crystal layer 3b, 3g, 3r becomes high. On the other hand, if the dielectric anisotropy ⁇ is too high, the liquid crystal surface The stability and reliability of the display element 1 are reduced, and image defects and image noise are likely to occur.
  • the refractive index anisotropy ⁇ of cholesteric liquid crystal is an important physical property that governs image quality.
  • the value of refractive index anisotropy ⁇ is preferably 0.18 ⁇ 0.24. If the refractive index anisotropy ⁇ force is smaller than the range, the reflectivity of each of the liquid crystal layers 3b, 3g and 3r in the planar state becomes low, resulting in a dark display with insufficient brightness. On the other hand, if the refractive index anisotropy ⁇ is larger than the above range, the liquid crystal layers 3b, 3g, and 3r have a large scattering reflection in the focal conic state. become. Further, when the refractive index anisotropy ⁇ is larger than the above range, the viscosity increases, so that the response speed of the cholesteric liquid crystal decreases.
  • the specific resistance of the cholesteric liquid crystal is preferably 10 1 (> ⁇ p ⁇ 10 13 ( ⁇ -cm).
  • the upper substrates 7b, 7g, 7r and the lower substrates 9b, 9g, 9r are required to have translucency.
  • the upper substrates 7b, 7g, 7r and the lower substrates 9b, 9g, 9r are all translucent, but are arranged on the bottom layer of the R display unit 6r. 9r may be opaque.
  • a plurality of strip-shaped data electrodes 19b extending in the vertical direction in FIG. 1 are formed in parallel on the B liquid crystal layer 3b side of the lower substrate 9b of the B display portion 6b.
  • a plurality of strip-shaped scanning electrodes 17b extending in the left-right direction in FIG. 1 are arranged in parallel on the B liquid crystal layer 3b side of the upper substrate 9b. Is formed.
  • a plurality of stripe-shaped scanning electrodes 17b and a plurality of data electrodes 19b are formed by patterning a transparent electrode made of indium tin oxide (ITO).
  • ITO is a representative force
  • other transparent conductive films such as Indium Zic Oxide (IZO), and photoconductive films such as amorphous silicon are used. Can do.
  • both the electrodes 17b and 19b are arranged to face each other.
  • Each crossing region of both electrodes 17b and 19b is a pixel.
  • a plurality of pixels are defined by both electrodes 17b and 19b and arranged in a matrix form to form a display screen.
  • the numbers 17b and 19b shown in FIG. 2 indicate the existence regions of both electrodes 17b and 19b, and their shapes are not suggested.
  • both electrodes 17b and 19b are coated with an insulating thin film and a liquid crystal molecule orientation stabilizing film (both not shown) as functional films, respectively.
  • the insulating thin film has a function of preventing a short circuit between the electrodes 17b and 19b and improving the reliability of the liquid crystal display element 1 as a gas noria layer.
  • a polyimide resin, a acryl resin, or the like can be used for the alignment stability film.
  • an alignment stability film is applied (coated) to the entire surface of each substrate on the electrodes 17b and 19b.
  • the alignment stability film may be used also as an insulating thin film.
  • the liquid crystal layer 3b for B is sealed between the two substrates 7b and 9b by the sealing material 18b applied to the outer periphery of the upper and lower substrates 7b and 9b.
  • the thickness (cell gap) of the liquid crystal layer 3b for B must be kept uniform.
  • a spherical spacer made of resin or inorganic oxide is dispersed in the liquid crystal layer 3b for B, or a columnar spacer whose surface is coated with thermoplastic resin.
  • a plurality of substrates are formed in the B liquid crystal layer 3b.
  • a spacer (not shown) is inserted into the B liquid crystal layer 3b to maintain the cell gap uniformity.
  • the cell gap d of the B liquid crystal layer 3b is preferably in the range of 3 ⁇ 6 ⁇ m.
  • the visible light absorbing layer 15 is provided on the outer surface (back surface) of the lower substrate 9r of the R display portion 6r. ing. Therefore, when all of the B, G, and R liquid crystal layers 3b, 3g, and 3r are in the focal conic state, black is displayed on the display screen of the liquid crystal display element 1. Note that the visible light absorption layer 15 may be provided as necessary.
  • the upper substrate 7b, 7g, 7r is connected to a scan electrode drive circuit 20 on which a scan electrode driver IC for individually driving the plurality of scan electrodes 17b, 17g, 17r is mounted. Further, a data electrode driving circuit 21 on which a data electrode driver IC for individually driving the plurality of data electrodes 19b, 19g, 19r is mounted is connected to the lower substrates 9b, 9g, 9r.
  • These drive circuits 20 and 21 generate pulse-like scanning signals and data signals based on predetermined signals output from the display control circuit 29, and predetermined scanning electrodes 17b, 17g, and 17r or data electrodes 19b, 19g, and 19r ⁇ Let ’s output.
  • An electronic paper is configured by providing the liquid crystal display element 1 shown in FIG. 1 with an input / output device and a control device (not shown) for overall control.
  • the electronic paper can be used as a display device of an electronic terminal device.
  • the electronic terminal device can be used as a display device of a display system.
  • FIG. 3 shows an example of the drive waveform of the drive data of the liquid crystal display element 1.
  • Fig. 3 (a) shows the drive waveform for driving the cholesteric liquid crystal to the planar state
  • Fig. 3 (b) shows the drive waveform for driving the cholesteric liquid crystal to the focal conic state.
  • 3 (a) and 3 (b) the upper part of the figure shows the waveform of the data signal voltage Vd output from the data electrode drive circuit 20, and the middle part of the figure shows the scan output from the scan electrode drive circuit 21.
  • the waveform of the signal voltage Vs is shown, and the lower part of the figure shows the waveform of the liquid crystal application voltage Vic applied to one of the B, G, and R liquid crystal layers 3b, 3g, and 3r.
  • the left force in the figure also represents the passage of time to the right, and the vertical direction in the figure represents the voltage.
  • FIG. 4 shows an example of voltage-reflectance characteristics of the cholesteric liquid crystal.
  • the horizontal axis represents the voltage value (V) applied to the cholesterol liquid crystal
  • the vertical axis represents the reflectance (%) of the cholesteric liquid crystal.
  • the solid curve P shown in Fig. 4 shows the voltage reflectance characteristics of the cholesteric liquid crystal when the initial state is the planar state
  • the dashed curve FC shows the voltage-reflectance characteristics of the cholesteric liquid crystal when the initial state is the focal conic state.
  • the data signal voltage Vd becomes + 32V in the first half of the selection period T1 during which the scanning electrode 17b in the first row is selected, while the scanning signal voltage Vs Becomes OV, and in the period of about 1Z2 in the second half, the scanning signal voltage Vs becomes + 32V while the data signal voltage Vd becomes OV. Therefore, a pulse voltage of ⁇ 32V is applied to the B liquid crystal layer 3b of the B pixel (1, 1) during the selection period T1. As shown in Fig.
  • the data signal voltage Vd becomes 24VZ8V in the first half of the selection period T1 in the period of about 1Z2 and the latter half of the period of about 1Z2, whereas the scanning signal voltage When Vs becomes OVZ + 32V, a pulse voltage of ⁇ 24V is applied to the B liquid crystal layer 3b of the B pixel (1, 1).
  • the cholesteric liquid crystal has a predetermined low voltage VFlOOb (for example, For example, when 24V) is applied and a weak electric field is generated, the helical structure of liquid crystal molecules cannot be completely solved.
  • a voltage of, for example, + 28V / + 4V is applied to the scan electrode 17b in the first row at a cycle of 1Z2 in the selection period T1, and a predetermined data signal voltage Vd is applied to the data electrode 19b.
  • a voltage of (for example, + 24VZ8V) is applied with a period of 1Z2 in the selection period T1. Therefore, a pulse voltage of 4VZ + 4V is applied to the B liquid crystal layer 3b of the B pixel (1, 1) during the non-selection period T2. As a result, the electric field generated in the B liquid crystal layer 3b of the B pixel (1, 1) becomes substantially zero during the non-selection period T2.
  • the above driving voltage is an example.
  • a pulse voltage of 30 to 35 V is applied between the electrodes 17b and 19b for 20 ms at the room temperature, the cholesteric liquid crystal in the liquid crystal layer 3b for B is in a selective reflection state. (Planar state), and when a voltage of 15 to 22V on the nose is applied for an effective time of 20ms, a good transmission state (focal conic state) is obtained.
  • the green (G) pixel (1, 1) and red (R) pixel (1, 1) arranged corresponding to the B pixel (1, 1) are driven by the B pixel (1, 1).
  • color display can be performed on the pixel (1, 1) in which the three B, G, R pixels (1, 1) are stacked.
  • the first row force is also driven from the pixel (1, 1) by rewriting the data voltage of each data electrode 19 for each row by driving the scan electrodes 17b, 17g, and 17r up to the nth row in a line-sequential manner.
  • Display data can be output to all (n, m) and color display for one frame (display screen) can be realized.
  • FIG. 1 The image processing method of the display element according to the present embodiment starts the rewriting process for rewriting the already written image data while scanning a plurality of pixels on the first display unit. Control to start the rewrite process for the display part. As a result, the display unit can be rewritten while maintaining the visibility of the display element as much as possible.
  • the rewriting process includes a reset process for temporarily changing the display state of the pixels to a different display state in the same frame, and the same display as the existing display state after the reset process. And a writing process for writing image data to the pixels so as to be in a state.
  • the image data is written so as to be in the already displayed state after the reset process for changing to the home port pick state as a display state temporarily different from the already displayed state.
  • the deterioration of the visibility of the display element in the standby state or initialization can be minimized.
  • performing rewrite processing on all display portions of the display element is referred to as refresh processing.
  • the rewriting process is started at a time interval that can avoid burn-in of the display area of the display unit. As a result, it is possible to effectively prevent the display element from being seized and maintain a good display state.
  • FIG. 5 shows a flowchart of the image processing method of the display element according to the present embodiment.
  • FIG. 6 schematically shows the display unit 6 that is executing the refresh process by the image processing method of the display element according to the present embodiment. 6 (a) shows the display unit 6 before and after the start of the refresh process, and FIGS. 6 (b) and 6 (d) show the display unit 6 during the rewrite process. ) Shows the display unit 6 in a state where the rewriting process of the G display unit 6g as the first display unit has been completed.
  • FIG. 6 (a) to 6 (d) the upper diagram schematically shows a cross section of the display unit 6, and the lower diagram shows a display image of the display unit 6.
  • FIG. 1 the state where the display unit reflects or transmits the incident light L indicates a normal display state, and the display unit displays the light L.
  • a state where only transmission is performed without reflection indicates a state where rewriting is performed.
  • FIG. 6 (a) a circular figure r filled in red, a triangle figure g filled in green, and a square figure b filled in blue are obtained.
  • the image processing method of the display element will be described taking a display image in which the upper half is white and the lower half is arranged on a gray background as an example. Note that the figure r is arranged in the white background area, the figure g is arranged over the white and gray background areas, and the figure b is arranged in the gray background area.
  • the order and combination of the display units for performing the reset process are changed according to the color tone of the display image so that the visibility of the display image is more maintained during the rewriting process. .
  • the color tone of the entire display image can be judged based on the average value of pixel values (gradation values) of RGB image data, for example! /, And is displayed at the center of the screen.
  • a display image may be extracted and the extracted display image color may be determined.
  • the display control circuit 29 determines the color tone of the entire display image.
  • step Sl it is first determined whether or not the display image is monochrome display.
  • step 1 the image data written in the plurality of correspondingly arranged pixels of the R, G, B display units 6r, 6g, and 6b are compared with each other, and the image data of the correspondingly arranged pixels is all pixels. If they are the same, the monochrome display is determined. As shown in Fig.
  • B pixels (1, 2) to (n, m), G pixels (1, 2) to (n, m), and R pixels (1, 2) ) To (n, m) are determined to be monochrome display when the image data are the same.
  • FIG. 6 (a) since it is a color display, it is determined that the display is not a monochrome display (N in step S1).
  • step S4 the color for which the rewriting process is executed independently is determined (step S4).
  • the display control circuit 29 reads each image data of RGB from the image data memory 30, and obtains an average value of gradation of the entire display image for each RGB.
  • the display control circuit 29 determines that the color having the largest gradation average value is the color closest to the color tone of the entire display image. As shown in Fig. 6 (a), in this example, the figure g is larger than the other figures r and figures, so the average value of the gradation data for green is larger than that for the other colors. Therefore, the display system The control circuit 29 determines that the color tone of the display image is green.
  • the display unit that reflects the color closest to the color tone of the display image is independent of the other display units.
  • Rewrite processing is performed at the timing (step S5).
  • the rewriting process is started at an independent timing for the G display unit 6g as the first display unit.
  • the display control circuit 29 performs control so that the rewriting process for the G display unit 6g is started, shifted from the R and B display units 6r and 6b.
  • FIGS. 7 to 9 show an embodiment showing a driving method capable of resetting the display screen with lower power consumption than the method of collectively resetting the display screen at the time of screen rewriting.
  • the liquid crystal is sequentially reset to the homeotopic state or the focal conic state by several lines in the reset process in the rewriting process. As shown in Fig. 7, for example, reset processing is performed every four lines, and data writing processing for one line is performed simultaneously for the number of lines, and screen rewriting is performed to rewrite display 6 with low power consumption. Processing can be performed.
  • FIG. 8 shows voltages applied to each pixel on one scan electrode 17 at the time of screen rewriting.
  • a positive and negative AC pulse is applied to each pixel once.
  • a reset pulse is applied to the liquid crystal of one pixel a plurality of times, for example, four times during the reset period shown in FIG. 8, and a write voltage is applied during the write period after a pause period.
  • FIG. 7 the lower half of the screen shows the screen for the previous display, and the upper half shows the screen of the new display!
  • the common mode shown in FIG. 7 is a line sequential scanning mode in which the scanning electrodes 17 are sequentially selected, and the segment mode is a mode in which an applied voltage can be selected for each data electrode 19.
  • the scan side driver sequentially selects scan electrodes (scan lines) and outputs ON scan pulses, and the data electrode side driver outputs ON data or OFF data pulses according to the data to be displayed.
  • Figure 7 shows the top scanning line force for the first time, the first writing line, that is, the above-mentioned writing line for each line. This indicates that the IN has almost reached the center of the screen. Data on this line is written and the reset line, for example 4 lines, is reset using the written data. This operation will be further described with reference to FIG.
  • the Eio signal which is the scan start signal on the scan side
  • the Lp signal that gives the timing of the data side latch and the scan side shift
  • the first line is selected and data can be written to that line.
  • the second pulse of Eio signal and Lp signal is input together, the first selected line is shifted by the Lp signal, the second line is selected, and Eio is input at the same time.
  • the first line is also selected at the same time, and the first and second lines are selected. This operation is repeated, and in the reset line setting section, the first line and the fourth line are selected, and data can be written to the four lines.
  • next pause line setting section only the Lp signal is input, and by this pulse, one line is shifted, and the second to fifth lines on the screen are selected.
  • the Eio signal and the Lp signal are input simultaneously, and the second line force selected before that is also shifted by one line for the fifth line.
  • the third line and the sixth line are selected, and the first line on the screen, that is, the first line is also selected by the input of the Eio signal.
  • the first line data is the data for resetting by the third line power by the sixth line.
  • the last displayed data is reset.
  • the second line is the pause line set in the pause line setting section, and no data is written.
  • the third line and fifth line force are similarly selected as the eighth line, and the data of the third line is written.
  • the force on which the data on the first line is written when the second Lp pulse is input on the third line Generally, the response time of cholesteric liquid crystal is on the order of several tens of ms depending on the physical properties of the material.
  • the third line is a pause period, and during this period (for example, 50 ms or less), the pixel on the third line is a force conic.
  • the 5th to 8th lines that are the reset period are synchronized with the 3rd line that is the write line.
  • the reset driving method described above takes a longer time to leave the liquid crystal molecules in a homeotropic state as compared to the case where there is no reset period as in the driving method shown in FIG. 4, so the liquid crystal layer is in a favorable focal conic state. can do. Thereby, the liquid crystal display element 1 can obtain an excellent contrast ratio.
  • the above reset driving method can drive a cholesteric liquid crystal using a general-purpose driver IC, and thus can realize simple and power saving.
  • a general-purpose driver IC used for the above reset driving method, for example, when the data electrode is turned on, the homeotopic state is changed to the planar state, and when the data electrode is turned off, the homeotopic state force is also changed to the force force conic state. Thus, each pixel can be driven.
  • FIG. 6 (b) shows the display unit 6 that has been rewritten using the reset driving method described above. In the lower part of Fig. 6 (b), the scanning electrode 17g (see Fig.
  • the rewriting process is executed by using the reset driving method for six scan electrodes 17g included in oc.
  • the reset process of the rewrite process is executed in the reset section shown in FIG. 7, and the write process of the rewrite process is executed in the write section shown in FIG.
  • the display control unit 29 causes the scan electrode driving circuit 20 and the data electrode driving circuit 21 to sequentially apply voltage pulses having substantially the same waveform to a plurality of pixels (a plurality of first pixels) of the G display unit 6g. Control and rewrite the G display 6g. For example, the display control unit 29 outputs the signal shown in FIG. 9 to the scan electrode drive circuit 20 and the data electrode drive circuit 21. Since the reset process of the rewrite process is performed, the liquid crystal layer is in the homeotope pick state or the focal conic state, and therefore the region ⁇ of the G display portion 6g as the first display portion transmits the light L. It becomes a state.
  • the R and B display units 6r and 6b as the second and third display units maintain a normal display state in which the light L is reflected or transmitted.
  • the liquid crystal display element 1 has a triangular figure g that is black on the scanning electrode 17g on which the rewriting process is performed and green in the other areas, and Red circle figure r and blue square figure b, which are the same as normal display, and rewriting process are performed! /,
  • the scanning electrode 17g is halftone magenta, and the other is white like normal display Or display with a gray background.
  • the liquid crystal display element 1 can maintain a display that can sufficiently recognize the image information at the time of normal display although the display screen on the scanning line subjected to the rewriting process has a color different from that of the normal display.
  • a plurality of pixels (a plurality of first pixels) respectively arranged on the first row force n-th row scanning electrode 17g are used.
  • the scanning is sequentially performed, and the rewriting process of the G display unit 6g as the first display unit is completed.
  • step S5 the rewriting process of the R and B display units 6r and 6b as the second and third display units is started (step S5).
  • the R and B display units 6r and 6b are rewritten by the reset driving method in the same manner as the G display unit 6g.
  • the lower part of Fig. 6 (d) shows R and B display sections 6r and 6b.
  • Scan electrodes 17r and 17b are sequentially scanned from the upper side of the screen until the rewriting process is completed up to approximately 2Z3 on the screen (arrows Sr and Sb).
  • six scan electrodes 17 r included in the region 17b shows a state where the rewrite process is executed using the reset driving method.
  • the display control unit 29 has a scan electrode drive circuit so that voltage pulses having substantially the same waveform are sequentially applied to a plurality of pixels (a plurality of second and third pixels) of the R and B display units 6r and 6b. 20 and the data electrode drive circuit 21 are controlled to rewrite the R and B display sections 6r and 6b. The reset process of the rewrite process is performed, and the liquid crystal layer becomes a homeo mouth pick state or a force conic state. Therefore, as shown in the upper part of FIG. 6D, the region a of the R and B display units 6r and 6b is in a state of transmitting the light L. On the other hand, the G display unit 6g maintains a normal display state in which the light L is reflected or transmitted.
  • the liquid crystal display element 1 is subjected to the rewriting process with the red circular figure r and the green triangular figure g similar to the normal display.
  • Scan electrode 17r, 17b is black and blue in other areas is blue figure b, and scan electrode 17r, 17b being rewritten is halftone green, and others are the same as normal display With a white or gray background.
  • the liquid crystal display element 1 has a different color from the normal display on the scanning lines 17r and 17b of the R and B display units 6r and 6b that have been rewritten. Therefore, it is possible to maintain a display that can sufficiently recognize image information during normal display.
  • a plurality of pixels (a plurality of second and second pixels) arranged on the scanning electrodes 17r and 17b of the first row force and the nth row, respectively.
  • the third pixel is sequentially scanned, and the rewriting process of the R and B display units 6r and 6b as the second and third display units is completed and the refresh process of the display unit 6 is completed.
  • step S4 the B display unit 6b serving as the first display unit is selected.
  • the rewriting process is started with the R and G display units 6r and 6g reflecting other colors.
  • step S5 a rewriting process is performed on the R and G display units 6r and 6g as the second and third display units that reflect the remaining colors.
  • the color tone is red
  • step S4 the R display section 6r as the first display section reflects other colors G
  • B The rewriting process is started by shifting to the display units 6g and 6b.
  • step S5 a rewriting process is performed on the G and B display units 6g and 6b as the second and third display units that reflect the remaining colors.
  • the rewriting process for 6r and 6b is started after the rewriting process for one frame of G display section 6g is completed.
  • the displayed image is different from the normal part of the full screen during the rewriting process.
  • the R and B display units 6r and 6b as the second and third display units will be
  • the writing process may be started before the rewriting process for one frame of the G display unit 6g as the first display unit is completed.
  • the area where the display image differs from normal during the rewriting process is larger than the area shown in the lower part of FIG. 6B, but the area for the entire display area is narrow.
  • the display can be maintained to the extent that information can be fully recognized.
  • step S1 If it is determined in step S1 that the display is monochrome (Y in step S1), the G display unit 6g as the first display unit is rewritten (step S2). Since green has the greatest effect on the appearance of the display image with the highest visibility among RGB, the rewriting process is executed independently for the G display unit 6g.
  • step S3 the R and B display units 6r and 6b as the second and third display units are rewritten (step S3). Thereby, the rewriting process of the R and B display units 6r and 6b is completed, and the refresh process of the display unit 6 is completed. Since each process of steps S2 and S3 is the same as each process of steps S5 and S6, description thereof is omitted.
  • step S2 may be processed after step S3, and step S5 may be processed after step S6.
  • step S3 or step S6 becomes the first display unit
  • the display unit processed in step S2 or step S5 is the second display unit. It becomes a display part.
  • steps S3 and S6 the display units 6r and 6b may be processed independently without processing the R and B display units 6r and 6b at the same time.
  • steps S9 and S10 the remaining colors are not processed at the same time, and the display unit is changed for each color.
  • Each may be processed alone.
  • the rewriting process may be sequentially performed independently for each of the R, G, and B display units 6r, 6g, and 6b without performing the process of step S4.
  • FIGS. 10 and 11 are diagrams for explaining a method for evaluating burn-in in the display area.
  • FIG. 10 shows an example of a display image at the time of image sticking evaluation and after the evaluation is completed.
  • the diagram on the left side of the figure illustrates the display unit 6 at the time of pixel burn-in evaluation, and the diagram on the right side of the diagram illustrates the display unit 6 after the pixel burn-in evaluation.
  • FIG. 10 shows an example of a display image at the time of image sticking evaluation and after the evaluation is completed.
  • the diagram on the left side of the figure illustrates the display unit 6 at the time of pixel burn-in evaluation, and the diagram on the right side of the diagram illustrates the display unit 6 after the pixel burn-in evaluation.
  • FIG. 10 shows an example of a display image at the time of image sticking evaluation and after the evaluation is completed.
  • the diagram on the left side of the figure illustrates the display unit 6 at the time of pixel burn-in evaluation, and the diagram on the right side of the diagram illustrates the display
  • FIG. 11 is a graph showing the relationship between the display time of the pine pattern (checker pattern) shown in FIG. 10 and the seizure degree ⁇ .
  • the horizontal axis in FIG. 11 represents the display time (h) of the pine pattern, and the vertical axis represents the seizure degree ⁇ .
  • a broken straight line extending in the left-right direction in the figure indicates the boundary of the seizure visual recognition limit, and a dotted straight line extending in the vertical direction in the figure indicates the time interval of the refresh process in the present embodiment.
  • the thick arrows shown in the figure indicate the range of the seizure degree ⁇ Y where the seizure can be visually recognized.
  • the pixel burn-in increases as ⁇ ⁇ increases as the display time increases.
  • the dashed straight line in the figure if ⁇ 0.5 (when the standard white plate's ⁇ value is 100), it can be said that the display screen will not be burned. Therefore, this form of implementation In the state, the allowable range of pixel burn-in is set to ⁇ 0.5.
  • the characteristic of ⁇ with respect to the display time differs depending on the liquid crystal material used. In the present embodiment, when the same image is displayed for about 13.5 hours, ⁇ > 0.5, and the image sticking phenomenon is observed on the display screen.
  • the refresh process is set to be performed in a 12-hour cycle for the purpose of securing a predetermined margin against pixel burn-in.
  • the ⁇ of the liquid crystal display element 1 can be suppressed to less than 0.5, so that the display screen can be prevented from being burned and the display quality can be improved. If the refresh process in the present embodiment is performed in a 24-hour cycle, ⁇ exceeds 0.5, so that the display screen is burned and the display quality of the liquid crystal display element 1 is impaired.
  • the display control circuit 29 stores a time interval for starting a refresh process for preventing the occurrence of burn-in.
  • the display control circuit 29 starts the refresh process of the display unit 6 shown in FIG.
  • the display control circuit 29 resets the time data of the timer 27 after the refresh processing of the R, G, B display units 6r, 6g, and 6b is completed, and starts the time data output from the timer 27 and the refresh processing. Resume comparison with interval.
  • the liquid crystal display element 1 can spontaneously start the refresh process independently of the time interval based on the illuminance data output from the optical sensor 26 of the detection unit 25. .
  • the display control circuit 29 starts the refresh process of the display unit 6 shown in FIG. 5 when the illuminance data output from the optical sensor 26 becomes lower than a predetermined threshold value.
  • the display control circuit 29 resumes the comparison between the illuminance data output from the optical sensor 26 and the threshold value for starting the refresh process.
  • the liquid crystal display element 1 includes the optical sensor 26 and the liquid crystal display element 1 is brought into a dark place and the screen cannot be seen, the liquid crystal display element 1 does not reach the 12-hour period.
  • the refresh process of the display unit 6 can be started spontaneously. This prevents pixel burn-in and improves the convenience of the liquid crystal display element 1.
  • the threshold value for starting the refresh process is set to 50 (lx), for example. Since the liquid crystal display element 1 is a reflective display element, the visibility is significantly lowered when the ambient illuminance is 50 (lx) or less. For this reason, a brightness of 50 (lx) is suitable as an index for spontaneous refresh processing. [0107]
  • the liquid crystal display element 1 performs rewriting processing at different timing with respect to at least one of the R, G, and B display units 6r, 6g, and 6b. As a result, the display 6 can be refreshed while maintaining the visibility of the display screen as much as possible.
  • the liquid crystal display element 1 can select the combination of the R, G, and B display units 6r, 6g, and 6b to which the rewriting process is performed according to the display image, and thus affects the visibility during the rewriting process. Can be made as small as possible. Furthermore, the liquid crystal display element 1 can prevent image burn-in by performing the fresh process at intervals at which no burn-in occurs in the plurality of pixels of the display unit 6, thereby obtaining good display quality.
  • the R, G, and B display units 6r, 6g, and 6g are configured to be independently driven independently, but the present invention is not limited to this.
  • the predetermined output terminal of the scan electrode drive circuit 20 may be commonly connected to the predetermined input terminals of the scan electrodes 17b, 17g, and 17r.
  • the same voltage is applied to the scanning electrodes 17r, 17g, and 17b of the R, G, and B display units 6r, 6g, and 6g.
  • the voltage applied to the data electrode so that the voltage applied to the liquid crystal layer of the display unit that is not rewritten is approximately OV, the same as in the first and second embodiments described above. An effect is obtained.
  • the liquid crystal display element of the matrix type display system has been described as an example, but the present invention is not limited to this.
  • the liquid of segment type display method using driving method such as static type that applies voltage to only the segment to be displayed independently and dynamic (multiplex) type that drives display segment in time series. It can also be applied to a crystal display element.
  • the liquid crystal display element 1 has the optical sensor 26 and the timer 27.
  • the present invention is not limited to this. For example, even if the liquid crystal display element 1 has only the timer 27, the pixel burn-in can be prevented, so that the same effect as in the above embodiment can be obtained.
  • the present invention can be applied to a display element in which a refresh process of a display unit is executed.

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Abstract

L'invention concerne un élément d'affichage présentant une pluralité d'unités d'affichage superposées, un papier électronique utilisant l'élément d'affichage, un dispositif de terminal électronique utilisant le papier électronique, un système d'affichage utilisant le dispositif de terminal électronique, ainsi qu'un procédé de traitement d'images de l'élément d'affichage. Il est possible d'obtenir un élément d'affichage permettant d'obtenir une image d'affichage d'une excellente qualité d'affichage et d'améliorer la convivialité, un papier électronique utilisant l'élément électronique, un dispositif de terminal électronique utilisant le papier électronique, ainsi qu'un système d'affichage utilisant le dispositif de terminal électronique. Une commande est mise en oeuvre comme suit. Si l'image d'affichage est déterminée comme étant différente d'un affichage monochrome (N dans l'étape S1), l'étape 4 consiste à déterminer une couleur de réflexion de l'unité d'affichage qui exécute indépendamment un processus de réécriture pour réécrire des données d'image qui ont déjà été écrites tout en balayant une pluralité de pixels. Le processus de réécriture est lancé sur l'unité d'affichage qui reflète la couleur déterminée lors de l'étape S4 (étape S5) avant de lancer le processus de réécriture pour l'unité d'affichage reflétant les couleurs restantes.
PCT/JP2006/319526 2006-09-29 2006-09-29 Élément d'affichage, papier électronique utilisant ledit élément, dispositif de terminal électronique utilisant ledit papier, système d'affichage utilisant ledit dispositif et procédé de traitement d'images de l'élément d'affichage WO2008041290A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/JP2006/319526 WO2008041290A1 (fr) 2006-09-29 2006-09-29 Élément d'affichage, papier électronique utilisant ledit élément, dispositif de terminal électronique utilisant ledit papier, système d'affichage utilisant ledit dispositif et procédé de traitement d'images de l'élément d'affichage
JP2008537348A JP4924610B2 (ja) 2006-09-29 2006-09-29 表示素子、それを備えた電子ペーパー、それを備えた電子端末機器及びそれを備えた表示システム並びに表示素子の画像処理方法

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003241168A (ja) * 2002-02-18 2003-08-27 Minolta Co Ltd 液晶表示素子の駆動方法、駆動装置及び液晶表示装置
JP2004219715A (ja) * 2003-01-15 2004-08-05 Minolta Co Ltd 液晶表示装置

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JP2003202544A (ja) * 2001-12-28 2003-07-18 Optrex Corp 液晶表示装置の駆動方法

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003241168A (ja) * 2002-02-18 2003-08-27 Minolta Co Ltd 液晶表示素子の駆動方法、駆動装置及び液晶表示装置
JP2004219715A (ja) * 2003-01-15 2004-08-05 Minolta Co Ltd 液晶表示装置

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