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
  • G09G3/3433—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 light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices
  • G09G3/344—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 light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices based on particles moving in a fluid or in a gas, e.g. electrophoretic devices
  • G09G3/3446—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 light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices based on particles moving in a fluid or in a gas, e.g. electrophoretic devices with more than two electrodes controlling the modulating element
• • 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
  • G09G3/3433—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 light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices
  • G09G3/3453—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 light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices based on rotating particles or microelements
• • 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
  • G09G2300/04—Structural and physical details of display devices
  • G09G2300/0439—Pixel structures
  • G09G2300/0452—Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• • 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
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
  • G09G2340/00—Aspects of display data processing
  • G09G2340/04—Changes in size, position or resolution of an image
  • G09G2340/0457—Improvement of perceived resolution by subpixel rendering

Definitions

• the invention relates to a display panel for displaying a picture.
• the invention also relates to a display device comprising such a display panel.
• the invention further relates to a method of driving such a display panel.
• a display panel for displaying a picture is disclosed in US 5,389,945.
• the disclosed display panel is a gyricon display, also called the twisting ball display, which offers a technology for making a form, of electronic paper.
• a gyricon display is an addressable display made up of a multiplicity of optically anisotropic balls, each of which can be selectively rotated to present a desired face to an observer.
• the disclosed display panel comprises a host layer loaded with small balls rotatable in cavities therein.
• the host layer may be an elastomer, such as silicone rubber, in sheet form, having dispersed therein a high density of dielectric balls.
• Each ball is fabricated so that its hemispheres bear contrasting colors, preferably black on one. side and white on the other, and will exhibit differential surface charges in an electrical field.
• Each ball is contained in a spherical cavity, slightly larger than the ball, with the space between the ball and the cavity filled with a dielectric liquid so that the ball is free to rotate therein.
• the balls Upon the application of an electric field of a given polarity and of a potential higher than a threshold value, the balls will line up so that their black sides all face in one direction. When viewed from that direction, the display panel will appear to be black. Conversely, reversing the polarity of " the electric field will cause the balls to rotate 180 degrees, so that their white sides face in the viewing direction and the display panel will appear to be white.
• the display panel has a relatively low number of attainable optical states.
• the invention provides an electrophoretic display panel for displaying a picture comprising
• a pixel having - an electrophoretic medium comprising particles, each particle having in operation an electrical multipole for being able to be moved and rotated and at least two surface portions having dissimilar optical properties, and - an optical state depending on a position and an orientation of the particles, and
• the particles can both move and rotate in the medium.
• the particle controller is able to move the particles because each particle has, in operation, an electrical multipole.
• the particle controller is able to apply an electrical field having a spatially non-uniform gradient.
• the electrical multipole may be permanent or the multipole may be induced in operation for example by an alternating electric field.
• the particle controller is able to rotate the particles because each particle has, in operation, an electrical multipole.
• the optical state of the pixel depends on the orientation of the particles, each particle having at least two surface portions having dissimilar optical properties, as well as on the position of the particles. As a result of these dependencies the number of attainable optical states for displaying the picture is relatively large. As an example: for a given orientation of the particles, the optical state of the pixel can be changed by changing the position of the particles. This is in contrast to the display panel disclosed in US 5,389,945, where for a given orientation of the particles, the optical state of the pixel can not be changed as the position of the particles is fixed.
• the particle controller is able to rotate each particle by applying an electrical field having a spatially uniform gradient, which can relatively simply be achieved. If, furthermore, each particle has a net charge for contributing to the ability of the particle to move, the particle controller is able to move each particle by applying an electrical field having a spatially uniform gradient, which can relatively simply be achieved.
• each particle has a substantially spherical shape and two hemispheres, which have dissimilar optical properties and substantially opposite charges. Then, the particles can relatively easily be manufactured.
• An example is the Gyricon particles from the Xerox company.
• the particle controller is arranged to enable the movement of the particles so as to locally control the density of the particles.
• the particles are moved and rotated in the electrophoretic medium, e.g. the movement and rotation may be simultaneously, or the particles may be rotated prior to the movement. If the particle controller is arranged to enable the movement of the particles prior to the rotation of the particles, then the accuracy of the picture is improved. If, furthermore,
• the pixel comprises a reservoir portion substantially non-contributing to the optical state of pixel, - the pixel comprises an optical active portion substantially contributing to the optical state of pixel,
• the particles in the optical active portion are able to rotate between extreme orientations
• the movement of the particles con ⁇ prises - a reset-movement of the particles into the reservoir portion, and subsequently - a picture-movement of the particles to the position for displaying the picture, and
• each particle has more than two surface portions having dissimilar optical properties;, for instance each particle has a red, a green and a blue surface portion, each particle has a ⁇ vhite, a black and a colored surface portion or each particle has a red, a green, a blue and a white surface portion.
• the surface portions on each particle have substantially equal areas.
• the electrophoretic medium also has a second type of particles being able to be moved and rotated.
• Each particle of the second type of particles has one or more surface portions having dissimilar optical properties with respect to the first type of particles, for instance the first type of particles have a green and a red surface portion;, whereas the second type of particles have a blue and a black surface portion.
• the surface portions Preferably have substantially equal areas.
• the display panel comprises a super pixel comprising
• the pixel - a further pixel having particles having at least two surface portions having dissimilar optical properties and dissimilar optical properties with respect to the surface portions of the particles of the pixel, and.
• the display panel is an active matrix display panel.
• Another aspect of the invention provides a display device comprising an electrophoretic display panel as claimed in claim 10.
• Yet another aspect of the invention provides a method of driving an electrophoretic display panel as claimed in claim 11.
• Figure 1 shows diagrammatically a front view of an embodiment of the display panel
• Figure 2 shows diagrammatically a cross-sectional view along II-II in Figure 1
• Figure 3 shows several options of coloring of the surface portions
• Figure 4 shows diagrammatically a cross-sectional view along II-II in Figure 1 of another embodiment of " the display panel
• Figure 5 shows diagrammatically a cross-sectional view along II-II in Figure 1 of another embodiment of the display panel
• Figure 6 shows diagrammatically a cross-sectional view along VI- VI in Figure 1 of another embodiment of the display panel.
• corresponding parts are referenced to by the same reference numerals.
• Figures 1 and 2 show an example of the display panel 1 having a first substrate 8, a second transparent opposed substrate 9 and a plurality of pixels 2.
• the pixels 2 are arranged along substantially straight lines in a two-dimensional structure. Other arrangements of the pixels 2 are alternatively possible, e.g. a honeycomb arrangement.
• the pixels 2 may further comprise switching electronics, for example, thin film transistors (TFTs), diodes, MIM devices or the like.
• An electrophoretic medium 5, having particles 6 in a transparant fluid, is present between the substrates 8,9.
• Each particle 6 has in operation an electrical multipole for being able to be moved and rotated.
• the multipole results from differential surface charges in an electrical field.
• the particles 6 may be dielectric balls, e.g. each about 15 to 30 microns in diameter.
• Each ball is fabricated to have at least two surface portions having dissimilar optical properties.
• a first one of the surface portions may have any color, whereas another one of the surface portions may have any color different from the color of the first one.
• the color of the first one of the surface portions is for instance red, green, blue, yellow, cyan, magenta, white or black.
• each particle has a red (al) and a green (a2) surface portion
• each particle has a white (bl, cl), a black (b2,c2) and a colored (b3,c3) surface portion
• each particle has a red (dl), a green (d2), a blue (d3) and a white (d4) surface portion.
• the particles 6 may e.g. have hemispheres 50,51 bearing contrasting colors, e.g. back on one side and white on the other.
• the particles 6 occupy a position in the pixel 2, and are able to move.
• the pixel 2 has a viewing surface 91 for being viewed by a viewer.
• the optical state of the pixel 2 depends on a position and an orientation of the particles 6.
• the particle controller having electrodes 10,11,20,21 for receiving potentials from the drive means 100, is arranged to enable a movement and a rotation of the particles 6 to one of the positions and one of the orientations, respectively, for displaying the picture.
• Each one of the electrodes 10,11,20,21 may have a substantially flat surface facing the particles 6.
• the geometry and potentials may be chosen such that substantially homogeneous electric fields can be generated between the electrodes 10,11 and between the electrodes
• the particles 6 are red on one side and green on the other.
• the red hemisphere 50 is negatively charged and the green hemisphere 51 is positively charged.
• the particle 6 has a permanent multipole, comprising a dipole.
• the particles 6 are brought in their distributed state in the pixel 2 by appropriately changing the potentials received by the electrodes 10,11.
• the particles 6 are oriented so that their red sides all face the viewing surface 91 by appropriately changing the potentials received by the electrodes 20,21. As a result the optical state of the pixel 2 is red.
• the particles 6 are brought in their distributed state in the pixel 2 by appropriately changing the potentials received by the electrodes 10,11.
• the particles 6 are oriented so that their green sides all face the viewing surface 91 by appropriately changing the potentials received by the electrodes 20,21 ; the polarity of the electric field between the electrodes 20,21 being opposite to the polarity for obtaining a red pixel 2.
• the optical state of the pixel 2 is green.
• the particles 6 are brought in their collected state near the surface of electrode 10 or 11, by appropriately changing the potentials received by the electrodes 10,11. As a consequence, the particles 6 are substantially outside the light path.
• the optical state of the pixel 2 is blue, as the surface 15 of the first substrate 8 is blue.
• the particles 6 have a portion of their red and green hemispheres 50,51 oriented towards the viewing surface 91 which results in an optical state being intermediate between red and green, i.e. yellow, orange etc.
• only a small number of particles 6 are distributed in the pixel 2 thereby not fully covering the blue surface 15 of the first substrate 8, whereas the small number of particles 6 have their red sides facing the viewing surface 9, which results in an optical state being intermediate between red and blue, i.e. purple.
• Figure 4 shows another embodiment. This embodiment is similar to the previous embodiment shown in Figure 2.
• the pixel 2 has a reservoir portion 510 substantially non-contributing to the optical state of the pixel 2, because of the black matrix 513 shielding the reservoir 510 from the viewer.
• the reservoir 510 has a data electrode 512 and a reset electrode 511.
• the data electrode 512 may be connected via a thin film transistor TFT to data drivers in an active matrix, while the reset electrode 511 may be common for a plurality of pixels 2 or even for the entire display panel 1.
• barriers 514a,514b forming pixel walls may separate pixels 2 from each other.
• the pixel 2 has an optical active portion 530 substantially contributing to the optical state of the pixel 2.
• the orientations of the particles 6 in the optical active portion 530 comprise extreme orientations, depending on the multipole of the particles 6 and the positions of electrodes 20,21 for orienting the particles 6.
• the particles 6 in the optical active portion 530 have a first extreme orientation if the particles 6 in the optical active portion 530 are oriented, lined up, so that their red sides all face the viewing surface 91 and the particles 6 in the optical active portion 530 have a second extreme orientation if the particles 6 in the optical active portion are oriented, lined up, so that their green sides all face the viewing surface 1.
• the movement of the particles 6 has a reset-movement of the particles 6 into the reservoir 510, and subsequently a picture-movement of the particles 6 to the position for displaying the picture
• the rotation of the particles 6 in the optical active portion 530 has a reset-rotation of the particles 6 to one of the extreme orientations, and subsequently a picture-rotation of the particles 6 in the optical active portion 530 to the orientation for displaying the picture.
• the electrodes 20,21,511,512 receive 0 Volts, 0 Volts, 10 Volts and 5 Volts, respectively. Secondly, the particles 6 are brought into their position for displaying the picture (this being the picture-movement) by appropriately changing the potentials received by the electrodes 20,21,511,512, e.g. the electrodes
• the number of particles 6 brought into the optical active portion 530 can be selected by appropriate potentials received by the electrodes 20,21,511,512 and the time during which the potentials are applied.
• the particles 6 in the reservoir 510 are kept in the reservoir 510 by collecting them near the surface of electrode 511 by appropriately changing the potentials received by the electrodes 20,21,511,512, e.g. the electrodes 20,21,511,512 receive 0 Volts, 0 Volts, 2 Volts and 0 Volts, respectively.
• the particles 6 in the optical active portion 530 are rotated to one of the extreme orientations (this being the reset-rotation), e.g. red, by appropriately changing the potentials received by the electrodes 20,21 , e.g. the electrodes 20,21 receive 0 Volts and 2 Volts, respectively.
• the subsequent picture-rotation of the particles 6 in the optical active portion 530 to the orientation for displaying red may in this case be absent because as a consequence of the reset-rotation the particles 6 in the optical active portion 530 are already oriented so that their red sides all face the viewing surface 91.
• the optical state of the pixel 2 is red.
• the intensity is determined by the number of particles 6 in the optical active portion 530.
• the particles 6 are brought into the reseivoir 510 (this being the reset-movement) by appropriately changing the potentials received by the electrodes 20,21,511,512, e.g. the electrodes 20,21,51 1,512 receive 0 Volts, 0 Volts, 10 Nolts and 5 Volts, respectively.
• the particles 6 are brought into their position for displaying the picture (this being the picture-movement) by appropriately changing the potentials received by the electrodes 20,21,511,512, e.g. the electrodes 20,21,511 ,512 receive 5 Volts, 5 Volts, 4 Volts and 3 Volts, respectively.
• the number of particles 6 brought into the optical active portion 530 can be selected by appropriate potentials received by the electrodes 20,21,511,512.
• the particles 6 in the optical active portion 530 are rotated to one of the extreme orientations (this being the reset- rotation), e.g. red, by appropriately changing the potentials received by the electrodes 20,21.
• the particles 6 in the optical active portion 530 are rotated to the orientation for displaying green (this being the picture-rotation), by appropriately changing the potentials received by the electrodes 20,21.
• the particles 6 in the optical active portion 530 are rotated so that their green sides all face the viewing surface 91. As a result the optical state of the pixel 2 is green.
• FIG. 5 shows another embodiment. This embodiment is similar to the previous embodiment shown in Figure 4. However, in this embodiment, the electrophoretic medium has a second type of particles 7 which are able to be moved and rotated. The particles 7 having a net charge being positive.
• the pixel 2 has a second reservoir portion 520 for the second particles 7 substantially non-contributing to the optical state of the pixel 2, as the black matrix 513 shields the second reservoir 520 from the viewer.
• the second reservoir 520 has a data electrode 521 and a reset electrode 522.
• barriers 514a,514b forming pixel walls may separate pixels 2 from each other.
• the pixel 2 has an optical active portion 530 substantially contributing to the optical state of the pixel 2.
• the orientations of the particles 6,7 in the optical active portion 530 comprise extreme orientations, depending on the multipole of the particles 6,7 and the positions of electrodes 20,21 for orienting the particles 6,7.
• the first type of particles 6 have a green and a red surface portion
• the second type of particles 7 have a blue and a black surface portion.
• the surface 15 is white.
• the first and/or the second type of particles can be brought into or out of the optical active portion 530.
• Attainable optical states are red, green, blue, black and white and intermediate optical states.
• the optical state of the super pixel 600 depends on the optical states of the associated pixels 2.
• pixels 2 associated with the super pixel 600 require filling with separate fluids/particles, manufacturing methods such as ink-jet printing will be suitable.
• the super pixel 600 to consists of three adjacent pixels 2a,2b,2c, see Figure 6.
• pixels 2a,2b,2c are considered having respective particles 6a,6b,6c which have a colored hemisphere and a black hemisphere, e.g. particles 6a are blue on one side and black on the other, particles 6b are green on one side and black on the other, particles 6c are red on one side and black on the other.
• surfaces 15a, 15b, 15c are white.
• an optical state of the super pixel being between black and white, and also being colored at up to 1/3 of the maximum intensity by selectively rotating the particles 6a,6b,6c in each one of the three pixels 2a,2b,2c.
• This embodiment has the advantage that the brightness of the display panel 1 may be increased at the expense of the viewing angle by defining the degree of scattering and mirroring of the "white" surfaces 15a, 15b, 15c (as is common for the so-called diffusing reflectors used in reflective LCDs).
• particles 6a,6b,6c are considered which have a colored hemisphere and a white hemisphere.
• surfaces 15a, 15b, 15c are black.
• particles 6a,6b,6c are considered which have hemispheres of two primary colors and pixels 2a,2b,2c with either a white or a black surface 15a, 15b, 15c.
• an optical state of the super pixel 600 being colored at up to 2/3 of the maximum intensity by selectively rotating the particles in two individual pixels (i.e. create red by filling the left hand and central pixel with particles and rotating all particles so that the red side faces the viewer).
• bright mixed colors will be obtainable by filling all three pixels 2a,2b,2c with suitable amounts of particles 6a,6b,6c and rotating the particles 6a,6b,6c as required.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)

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Applications Claiming Priority (2)

Publications (1)

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Citations (4)

• 2005
  • 2005-04-06 CN CNA2005800113189A patent/CN1942919A/zh active Pending
  • 2005-04-06 KR KR1020067021228A patent/KR20070029686A/ko not_active Application Discontinuation
  • 2005-04-06 JP JP2007507888A patent/JP2007532967A/ja not_active Withdrawn
  • 2005-04-06 WO PCT/IB2005/051127 patent/WO2005101361A1/en not_active Application Discontinuation
  • 2005-04-06 EP EP05718644A patent/EP1738346A1/en not_active Withdrawn
  • 2005-04-11 TW TW094111414A patent/TW200601218A/zh unknown

Patent Citations (4)

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