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
  • G09G3/38—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 electrochromic devices
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G5/00—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators
  • G09G5/02—Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators characterised by the way in which colour is displayed
• • 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
• • 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
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2320/00—Control of display operating conditions
  • G09G2320/02—Improving the quality of display appearance
  • G09G2320/029—Improving the quality of display appearance by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• • 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
  • G09G3/2007—Display of intermediate tones
  • G09G3/2011—Display of intermediate tones by amplitude modulation

Definitions

• the present patent application relates to the field of electrochromic display devices and particularly to a method and apparatus for providing gray scales for such display devices. More specifically, the present patent application relates to an efficient system for providing analog gray scales for electrochromic display devices. The present patent application also relates to a computer program product comprising software code portions for achieving the system and method for providing analog gray scales for electrochromic display appliances when said product is run on a computer.
• Electrochromic display devices have recently been studied as candidates for electronic paper type displays. However, the slow switching speed and high power consumption of the electrochromic display technologies commercially available today do not meet the needs of the display market. Of late the trend for improving performance has been the use of nano-materials such as chemically modified nano-structured mesophorous films. Use of such materials has shown promising results. However, one of the remaining key issues with respect to electrochromic displays is the generation of gray scales.
• One prior art approach to providing gray scales has been to subdivide each display element (pixel) into a plurality of sub-elements using a plurality of sub-electrodes on one substrate, e.g. providing fifteen electrodes, splitting each display element into fifteen sub elements, enabling sixteen gray scale levels to be achieved by successive switching operatioi of each of the sub-elements for producing 15 gray scale levels and all sub-elements in their "off condition providing the sixteenth level.
• a further object of the invention is to provide an improved method for providing gray scales for an electrochromic display appliance.
• Yet another object of the invention is to provide an improved computer program product comprising software code portions for achieving the apparatus and method for providing gray scales for an electrochromic display appliance when said product is run on a computer.
• Fig. 1 discloses a schematic cross-sectional view of a pixel of a display device according to a first embodiment of the invention with electric field lines shown;
• Fig. 2 discloses a schematic cross-sectional view of the pixel of figure 1 with the entire electrochromic layer in a dark state
• Fig. 3 discloses a schematic cross-section of the pixel of figure 1 with a centrally located part of the electrochromic layer in a transparent (bright) state
• Fig. 4 discloses a schematic cross-section of the pixel of figure 1 with a large portion of the electrochromic layer in a dark state
• Fig. 5 discloses a schematic cross-section of the pixel of figure 1 with approximately half the electrochromic layer in a dark state
• Fig. 6 discloses a schematic cross-section of the pixel of figure 1 with a small portion of the electrochromic layer in a dark state
• Fig. 7 discloses a schematic cross-section of the pixel of figure 1 with the electrochromic layer wholly in a transparent (bright) state.
• Fig. 1 shows a schematic cross sectional view of a pixel 1 of an electrochromic display according to a first embodiment.
• Each pixel of the electrochromic display is independently addressable and can be separated from each other either electrically or physically, in order to avoid cross-talk between pixels.
• the pixel 1 comprises: a first substrate 6, which is preferably transparent and made of a material such as a glass or from a plastic plate; a second substrate 7, which can also be transparent in some cases such as for a display lit at the back; an electrochromic material 2 disposed between said first substrate 6 and said second substrate 7; at least two independent conductive electrodes 3, 4 associated with said first substrate 6, which electrodes 3, 4 are preferably transparent; an independent conductive counter-electrode 5 associated with said second substrate 7.
• the pixel 1 also comprises a transparent electrolytic material which is in contact with said electrochromic material 2 and said counter-electrode 5.
• Each respective electrode 3, 4, 5 is connected to an independently controllable voltage source (not shown).
• the display device comprises means (not shown) for controlling the voltage applied to each respective electrode 3, 4, 5, such as an electronic display control device which can comprise a microprocessor. In this way, using the display control device, non-uniform electric fields can be produced in each pixel, e.g. as illustrated in figure 1 where electric field lines are shown for a case where a voltage of approximately 2V is applied to the electrode 3, while 0V is applied to electrode 4 and counter-electrode 5.
• the time required to switch to a desired state for the preferred type of display is less than 1 second. Erasure, i.e. reset, can easily be achieved through making a change of polarities. Such a reset can be used to define a reference state from which all possible gray levels can be generated. If no reset is used, it will be necessary to remember the previous state of the pixel before supplying the correct amount of charge (or discharge) to reach a new gray level. In such a case the electronic display control device will comprise memory storage means (not shown), where the previously generated gray level is stored and the new gray level to be achieved is compared with the previous gray level and the required charge (discharge) to be applied to reach the desired gray level is determined.
• Fig. 2 illustrates the pixel 1 when OV is applied to the electrodes 3 and 4, while a negative potential is applied to the counter-electrode 5. In this case the pixel 1 will be generated with all of its electrochromic material 2 in the dark state.
• Fig. 3 illustrates the pixel 1 when moderate positive potentials are applied for a given period of time to the electrodes 3 and 4, while 0V is applied to the counter-electrode 5.
• the pixel 1 will be generated with the regions of its electrochromic material 2 close to the positively charged electrodes 3 and 4 in the dark state and the part of its electrochromic material 2 located centrally between these electrodes 3, 4 in the transparent (bright) state.
• Fig. 4 illustrates the pixel 1 when a slightly higher positive potential, compared to that of figure 3, is applied for the same period of time to the electrode 3 while 0V is applied to the electrode 4, and 0V is applied to the counter-electrode 5.
• the pixel 1 will be generated with a slightly larger part of its electrochromic material 2 closest to the positively charged electrode 3 in the dark state and the part of its electrochromic material 2 located closest to the 0V electrode 4 in the transparent (bright) state.
• Fig. 5 illustrates the pixel 1 when a positive potential ranging between that of figure 3 and figure 4, is applied to the electrode 3 while 0V is applied to the electrode 4, and 0V is applied to the counter-electrode 5.
• the pixel 1 will be generated with approximately half of its electrochromic material 2 closest to the positively charged electrod 3 in the dark state and the half of its electrochromic material 2 located closest to the OV electrode 4 in the transparent (bright) state.
• Fig. 6 illustrates the pixel 1 when a moderate positive potential, as that of figure 2, is applied to the electrode 3 while OV is applied to the electrode 4, and OV is applied to the counter-electrode 5.
• the pixel 1 will be generated with a small part of its electrochromic material 2 closest to the positively charged electrode 3 in the dark state and the rest of its electrochromic material 2 located closest to the OV electrode 4 in the transparent (bright) state.
• the state illustrated in figure 6 essentially corresponds to the state illustrated in figure 1.
• Fig. 7 illustrates the pixel 1 when OV is applied to the electrodes 3 and 4, and a positive potential is applied to the counter-electrode 5. In this case the pixel 1 will be generated with all of its electrochromic material 2 in the transparent (bright) state.
• the use of several independently controllable electrodes in a pixel 1 of a display in accordance with the invention facilitates the possibility of achieving an analog gray level in the pixel 1 through controlling the potentials applied to the respective electrodes 3, 4, 5 and the time of application for causing an appropriate part of the electrochromic material 2 to be switched.
• a computer program product comprising software code portions can be used for controlling the potentials applied in accordance with the invention for providing gray scales to the electrochromic display appliance when said computer program product is run on the micro-processor of the control device.
• a method for generating analog gray scales in a pixel 1 of a display device having a first substrate 6, a second substrate 7, an electrochromic material 2 disposed between said first substrate 6 and said second substrate 7, comprises the following steps: providing for at least two independent electrodes 3, 4 to be associated with said first substrate 6; providing for an independent counter-electrode 5 to be associated with said second substrate 7; providing for connection of each respective electrode 3, 4, 5 to an independently controllable voltage source; providing means for controlling the voltage applied to each respective electrode 3, 4, 5 for producing non-uniform electric fields in each pixel 1, for causing partial switching of the electrochromic material 2 from a first state to a second state for generating an area ratio gray level.
• the method also allows for the step of providing means for controlling the time during which voltage is applied to each respective electrode 3. 4, 5.
• the method also suggests the steps of: providing memory storage means for storing a previously generated gray level; providing means for comparing a gray level to be achieved with a previously generated gray level; providing means for determining the required potential to be applied to each respective electrode in order to reach a desired gray level.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Control Of Indicators Other Than Cathode Ray Tubes (AREA)
• Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (8)

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Citations (4)

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• 2003
  • 2003-07-01 JP JP2004528725A patent/JP2005535932A/ja not_active Withdrawn
  • 2003-07-01 WO PCT/IB2003/003108 patent/WO2004017295A1/en not_active Ceased
  • 2003-07-01 AU AU2003285715A patent/AU2003285715A1/en not_active Abandoned
  • 2003-07-01 CN CNA038193531A patent/CN1675679A/zh active Pending
  • 2003-07-01 US US10/524,404 patent/US20050286107A1/en not_active Abandoned
  • 2003-07-01 KR KR1020057002352A patent/KR20050042148A/ko not_active Withdrawn
  • 2003-07-01 EP EP03740989A patent/EP1532616A1/en not_active Withdrawn
  • 2003-08-12 TW TW092122131A patent/TW200402589A/zh unknown

Patent Citations (4)

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