WO2006108285A1 - Amélioration de la brillance dans les affichages d’image réfléchissants électrophorétiques modulés tir - Google Patents

Amélioration de la brillance dans les affichages d’image réfléchissants électrophorétiques modulés tir Download PDF

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Publication number
WO2006108285A1
WO2006108285A1 PCT/CA2006/000559 CA2006000559W WO2006108285A1 WO 2006108285 A1 WO2006108285 A1 WO 2006108285A1 CA 2006000559 W CA2006000559 W CA 2006000559W WO 2006108285 A1 WO2006108285 A1 WO 2006108285A1
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Prior art keywords
reflective
hemi
beads
particles
regions
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PCT/CA2006/000559
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English (en)
Inventor
Lorne A. Whitehead
Michele Ann Mossman
Helge Seetzen
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The University Of British Columbia
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Priority to JP2008503340A priority Critical patent/JP2008535005A/ja
Publication of WO2006108285A1 publication Critical patent/WO2006108285A1/fr

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    • 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 
    • G02F1/165—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 translational movement of particles in a fluid under the influence of an applied field
    • G02F1/166—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 translational movement of particles in a fluid under the influence of an applied field characterised by the electro-optical or magneto-optical effect
    • G02F1/167—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 translational movement of particles in a fluid under the influence of an applied field characterised by the electro-optical or magneto-optical effect by electrophoresis
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/004—Scattering dots or dot-like elements, e.g. microbeads, scattering particles, nanoparticles
    • 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 
    • G02F1/165—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 translational movement of particles in a fluid under the influence of an applied field
    • G02F1/1675—Constructional details
    • G02F1/1677—Structural association of cells with optical devices, e.g. reflectors or illuminating devices
    • 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
    • G02F1/29—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 position or the direction of light beams, i.e. deflection
    • G02F1/31—Digital deflection, i.e. optical switching
    • G02F1/315—Digital deflection, i.e. optical switching based on the use of controlled internal reflection
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/12—Reflex reflectors
    • G02B5/126—Reflex reflectors including curved refracting surface
    • G02B5/128—Reflex reflectors including curved refracting surface transparent spheres being embedded in matrix

Definitions

  • This application pertains to brightness enhancement of reflective image displays of the type described in United States Patent Nos. 5,999,307; 6,064,784; 6,215,920; 6,865,011; 6,885,496 and 6,891 ,658; all of which are incorporated herein by reference.
  • FIG. 1A depicts a portion of a prior art reflective (i.e. front-lit) electrophoretically frustrated total internal reflection (TIR) modulated display 10 of the type described in United States Patent Nos. 6,885,496 and 6,891,658.
  • Display 10 includes a transparent outward sheet 12 formed by partially embedding a large plurality of high refractive index (e.g. ⁇ y > ⁇ 1.90) transparent spherical or approximately spherical beads 14 in the inward surface of a high refractive index (e.g. ⁇ 2 > - 1.75) polymeric material 16 having a flat outward viewing surface 17 which viewer V observes through an angular range of viewing directions Y.
  • high refractive index e.g. ⁇ y > ⁇ 1.90
  • a high refractive index e.g. ⁇ 2 > - 1.75
  • Beads 14 are packed closely together to form an inwardly projecting monolayer 18 having a thickness approximately equal to the diameter of one of beads 14. Ideally, each one of beads 14 touches all of the beads immediately adjacent to that one bead. Minimal interstitial gaps (ideally, no gaps) remain between adjacent beads. [0004] An electrophoresis medium 20 is maintained adjacent the portions of beads 14 which protrude inwardly from material 16 by containment of medium 20 within a reservoir 22 defined by lower sheet 24. An inert, low refractive index (i.e.
  • medium 20 contains a finely dispersed suspension of light scattering and/or absorptive particles 26 such as pigments, dyed or otherwise scattering/absorptive silica or latex particles, etc.
  • Sheet 24 's optical characteristics are relatively unimportant: sheet 24 need only form a reservoir for containment of electrophoresis medium 20 and particles 26, and serve as a support for backplane electrode 48.
  • the TIR interface between two media having different refractive indices is characterized by a critical angle ⁇ c . Light rays incident upon the interface at angles less than ⁇ c are transmitted through the interface. Light rays incident upon the interface at angles greater than ⁇ c undergo TIR at the interface. A small critical angle is preferred at the TIR interface since this affords a large range of angles over which TIR may occur.
  • a voltage can be applied across medium 20 via electrodes 46, 48 (shown as dashed lines) which can for example be applied by vapour-deposition to the inwardly protruding surface portion of beads 14 and to the outward surface of sheet 24.
  • Electrode 46 is transparent and substantially thin to minimize its interference with light rays at the bead: liquid TIR interface.
  • Backplane electrode 48 need not be transparent. If electrophoresis medium 20 is activated by actuating voltage source 50 to apply a voltage between electrodes 46, 48 as illustrated to the left of dashed line 28, suspended particles 26 are electrophoretically moved into the region where the evanescent wave is relatively intense (i.e. within 0.25 micron of the inward surfaces of inwardly protruding beads 14, or closer).
  • Particles 26 need only be moved outside the thin evanescent wave region, by suitably actuating voltage source 50, in order to restore the TIR capability of the bead: liquid TIR interface and convert each "dark" non-reflective absorption region or pixel to a "white” reflection region or pixel.
  • the net optical characteristics of outward sheet 12 can be controlled by controlling the voltage applied across medium 20 via electrodes 46, 48.
  • the electrodes can be seg- mented to control the electrophoretic activation of medium 20 across separate regions or pixels of sheet 12, thus forming an image.
  • Figure 2 depicts, in enlarged cross-section, an inward hemispherical or "hemi-bead" portion 60 of one of spherical beads 14.
  • a light ray 62 perpendicularly incident (through material 16) on hemi- bead 60 at a radial distance a from hemi-bead 60 's centre C encounters the inward surface of hemi-bead 60 at an angle O 1 relative to radial axis 66.
  • Ray 68 encounters the inward surface of hemi-bead 60 at the critical angle ⁇ c (relative to radial axis 70), the minimum required angle for TIR to occur.
  • Ray 68 is accordingly totally internally reflected, as ray 72, which again encounters the inward surface of hemi-bead 60 at the critical angle ⁇ c .
  • Ray 72 is accordingly totally internally reflected, as ray 74, which also encounters the inward surface of hemi-bead 60 at the critical angle ⁇ c .
  • Ray 74 is accordingly totally internally reflected, as ray 76, which passes perpendicularly through hemi-bead 60 into the embedded portion of bead 14 and into material 16.
  • Ray 68 is thus reflected back as ray 76 in a direction approximately opposite that of incident ray 68.
  • ⁇ x is the refractive index of hemi-bead 60 and 77 3 is the refractive index of the medium adjacent the surface of hemi-bead 60 at which TIR occurs.
  • hemi-bead 60 is formed of a lower refractive index material such as polycarbonate (7Z 1 - 1.59) and if the adjacent medium is Fluorinert (T7 3 ⁇ 1.27), a reflectance R of about 36% is attained, whereas if hemi-bead 60 is formed of a high refractive index nano-composite material ( ⁇ ⁇ ⁇ 1.92) a reflectance R of about 56% is attained.
  • illumination source S ( Figure IB) is positioned behind viewer Vs head, the apparent brightness of display 10 is further enhanced by the aforemen- tioned semi-retro-reflective characteristic.
  • FIG. 4 A shows hemi-bead 60 as seen from perpen- dicular incidence—that is, from an incidence angle offset 0° from the perpendicular.
  • the annulus is depicted as white, corresponding to the fact that this is the region of hemi-bead 60 which reflects incident light rays by TIR, as aforesaid.
  • the annulus surrounds a circu- lar region 82 which is depicted as dark, corresponding to the fact that this is the non-reflective region of hemi-bead 60 within which incident rays are absorbed and do not undergo TIR.
  • Figures 4B-4G show hemi-bead 60 as seen from incident angles which are respectively offset 15°, 30°, 45°, 60°, 75° and 90° from the perpendicular. Comparison of Figures 4B-4G with Figure 4A reveals that the observed area of reflective portion 80 of hemi-bead 60 for which a ⁇ a c decreases only gradually as the incidence angle increases. Even at near glancing incidence angles (e.g.
  • the HCP structure yields the highest packing density for hemispheres, it is not necessary to pack the hemi-beads in a regular arrangement, nor is it necessary that the hemi-beads be of uniform size.
  • a random distribution of non-uniform size hemi-beads having diameters within a range of about 1-50 ⁇ m has a packing density of approximately 80% , and has an optical appearance substantially similar to that of an HCP arrangement of uniform size hemi-beads.
  • such a randomly distributed arrangement may be more practical to manufacture, and for this reason, somewhat reduced reflectance due to less dense packing may be acceptable.
  • Hemi-bead 60's average surface reflectance, R is determined by the ratio of the area of reflective annulus 80 to the total area comprising reflective annulus 80 and dark circular region 82.
  • That ratio is in turn determined by the ratio of the refractive index, ⁇ l t of hemi- bead 60 to the refractive index, ⁇ 3 , of the medium adjacent the surface of hemi-bead 60 at which TIR occurs, in accordance with Equation (1). It is thus apparent that the average surface reflectance, R, increases with the ratio of the refractive index ⁇ l t of hemi-bead 60 to that of the adjacent medium 77 3 . For example, the average surface reflectance, R, of a hemispherical water drop (77 !
  • interstitial gaps 84 ( Figure 5) unavoidably remain between adjacent beads.
  • Light rays incident upon any of gaps 84 are "lost" in the sense that they pass directly into electro- phoretic medium 20, producing undesirable dark spots on viewing surface 17. While these spots are invisibly small, and therefore do not detract from display 10's appearance, they do detract from viewing surface 17's net average surface reflectance, R.
  • Individual hemi-beads 60 can be invisibly small, within the range of 2-50 ⁇ m in diameter, and as shown in Figure 5 they can be packed into an array to create a display surface that appears highly reflective due to the large plurality of tiny, adjacent, reflective annular regions 80.
  • regions 80 where TIR can occur, particles 26 ( Figure IA) do not impede the reflection of incident light when they are not in contact with the inward, hemispherical portions of beads 14.
  • regions 82 and 84 where TIR does not occur, particles 26 may absorb incident light rays— even if particles 26 are moved outside the evanescent wave region so that they are not in optical contact with the inward, hemispherical portions of beads 14.
  • the refractive index ratio ⁇ j / ⁇ 3 can be increased in order to increase the size of each reflective annular region 80 and thus reduce such absorption losses.
  • Non-reflective regions 82, 84 cumulatively reduce display 10's overall surface reflectance, R. Since display 10 is a reflective display, it is clearly desirable to minimize such reduction.
  • Display 10' s reflectance can be increased by decreasing such absorptive losses through the use of materials having specific selected refractive index values, optical microstructures or patterned surfaces placed on the outward or inward side(s) of monolayer 18 ( Figure IA).
  • display 10' s maximum surface reflect- ance is determined by the ratio of the refractive index values of hemi- bead 60 and electrophoretic medium 20
  • Display 10's surface reflectance can be increased, as de- scribed below, improving the appearance of the display.
  • Figure IA is a greatly enlarged, not to scale, fragmented cross-sectional side elevation view, of a portion of an electrophoretically frustrated or modulated prior art reflective image display.
  • Figure IB schematically illustrates the wide angle viewing range a of the Figure IA display, and the angular range ⁇ of the illumi- nation source.
  • Figure 2 is a greatly enlarged, cross-sectional side elevation view of a hemispherical ("hemi-bead") portion of one of the spherical beads of the Figure IA apparatus.
  • Figures 3A, 3B and 3C depict semi-retro-reflection of light rays perpendicularly incident on the Figure 2 hemi-bead at increasing off- axis distances at which the incident rays undergo TIR two, three and four times respectively.
  • Figures 4A, 4B, 4C, 4D, 4E, 4F and 4G depict the Figure 2 hemi-bead, as seen from viewing angles which are offset 0°, 15°, 30°, 45°, 60°, 75° and 90° respectively from the perpendicular.
  • Figure 5 is a top plan (i.e. as seen from a viewing angle offset 0° from the perpendicular) cross-sectional view of a portion of the Figure 1 display, showing the spherical beads arranged in a hexagonal closest packed (HCP) structure.
  • Figures 6 A and 6B are top plan views, on a greatly enlarged scale, of two alternative backplane electrode patterns for use with the Figure 5 structure.
  • Figures 7A and 7B are fragmented cross-sectional side elevation views, on a greatly enlarged scale, of a portion of an electro- phoretically frustrated (i.e. modulated) reflective image display incorporating the Figure 6A backplane electrode pattern.
  • Figure 8 is a greatly enlarged, not to scale, cross-sectional side elevation view of a portion of an electrophoretically frustrated or modulated reflective image display incorporating electrophoretically suspended absorptive and reflective particles.
  • Figure 9 is a greatly enlarged, not to scale, cross-sectional side elevation view of a portion of an electrophoretically frustrated or modulated reflective image display incorporating a reflective porous membrane.
  • Figure 10 is a greatly enlarged, not to scale, cross-sectional side elevation view of a portion of an electrophoretically frustrated or modulated reflective image display incorporating excess polymer material in the interstices between adjacent hemi-beads.
  • Backplane electrode 48 can be formed on sheet 24 using either one of patterns 100 or 102 depicted in Figures 6 A or 6B respectively.
  • Black regions 104, 106 are electrically conductive regions, and may be either reflective or non-reflective.
  • White regions 108, 110, 112 are reflective regions, and may be either electrically conductive or non- conductive— provided there is no electrical conductivity between regions 108, 110, 112 on the one hand and regions 104, 106 on the other hand.
  • Reflective regions 108, 110 are each preferably circular in shape, and have a diameter greater than or equal to (preferably equal to) the diameter of one of the non-reflective, circular regions 82 of one of hemi-beads 60.
  • Pattern 100's regions 104 have an overall size and shape substantially similar to the overall size and shape of regions 80, 84 of hemi-beads 60.
  • the optical properties of regions 104, 106 are relatively unimportant, as are those of sheet 24. It may however be advantageous to provide a reflective outward surface on sheet 24 and to form regions 104 (or 106) thereon, with the remaining portions of sheet 24's reflective outward surface constituting regions 108 (or 110, 112).
  • patterned backplane electrode 100 decreases absorptive losses due to light absorption in regions 82, but does not decrease absorptive losses due to light absorption in gap regions 84.
  • patterned backplane electrode 102 decreases absorptive losses due to light absorption in both regions 82 and 84. This is achieved by forming pattern 102 with each one of reflective regions 112 having a size and shape which is substantially similar to the size and shape of one of gaps 84, with each region 112 in the same location relative to its adjacent reflective regions 110 as the location of a corresponding one of gaps 84 relative to that gap's adjacent regions 82.
  • Patterned backplane electrode 100 (or 102) is positioned with respect to monolayer 18 to align each circular reflective region 108 (or 110) with a corresponding one of non-reflective, circular regions 82; thereby also aligning electrically conductive region 104 (or 106) with reflective regions 80.
  • electrophoresis medium 20 When electrophoresis medium 20 is activated by actuating voltage source 50 to apply a voltage between electrodes 46 and 48, particles 26 substantially cover the inward surfaces of monolayer 18's hemi-beads 60 as shown in Figure 7 A (which depicts the non-reflective state utilizing patterned backplane electrode 100). Particles 26 absorb light rays (e.g.
  • particles 26 are attracted to the electrically conductive regions 104 of patterned backplane electrode 100 (or to the electrically conductive regions 106 of a patterned backplane electrode 102). Since regions 104 are aligned with reflective annular regions 80, particles 26 are hidden from view (i.e. because light ray 114 which would otherwise illuminate particles 26 is reflected by regions 80). Light rays 116, which do not undergo TIR, but which are instead transmitted through hemi-beads 60, strike one of reflective regions 108 and are therefore also reflected.
  • hemi-bead monolayer 18 If hemi-bead monolayer 18 is positioned an appropriate distance above reflective regions 108, the transmitted light rays are focused toward reflective annular regions 80, such that the light rays are returned approximately in the direction from which they came. This further enhances the display's semi-retro-reflective characteristic, and can result in a perceived reflectance value exceeding 100% . Even with the absorptive losses associated with a red-green-blue (RGB) colour filter array, patterned backplane electrodes 100, 102 facilitate production of reflective image displays having a brightness comparable to that of coloured ink on white paper.
  • RGB red-green-blue
  • Figure 8 depicts an alternative display brightness (i.e. reflectance) enhancement technique in which absorptive particles 26 are commingled, within electrophoretic medium 20, with a finely dispersed suspension of reflective beads or particles 118.
  • the average diameter of reflective beads 118 is substantially greater (e.g. about 10 times greater) than the average diameter of absorptive particles 26.
  • Reflective beads 118 can be electrostatically neutral so that they will not be affected by an applied electric field.
  • reflective beads 118 can have an electrostatic charge opposite to that of absorptive particles 26, such that beads 118 will move in the opposite direction from particles 26 when subjected to an applied electric field.
  • Reflective beads 118 can be any substantially reflective (e.g. white) granular material having a suitable granular size distribution, although high refractive index materials such as titanium dioxide ⁇ ⁇ 2.4) are preferred.
  • Reflective beads 118 accordingly form a porous filter, allowing absorptive particles 26 to move outwardly into contact with hemi-beads 60 in the absorptive state; and to move inwardly away from hemi-beads 60 in the reflective state, thus obscuring absorptive particles 26 from direct view in the reflective state.
  • Reflective beads 118 depicts reflective beads 118 as spherically shaped, such shape is not essential— beads 118 can be of arbitrary shape. [0050] The Figure 8 technique affords benefits besides brightness enhancement.
  • the brightness enhancement i.e. reflectance
  • reflective beads 118 are assumed to have a diffuse reflectance of about 40%
  • reflective beads 118 are also assumed to affect the entirety of the previously explained 50% absorptive loss area
  • a brightness enhancement of about 20% i.e. 50% of 40%
  • Figure 9 depicts a further alternative display brightness (i.e. reflectance) enhancement technique in which a reflective, porous, membrane 140 is provided between the inward surfaces of hemi-beads 60 and lower sheet 24.
  • the average diameter of the pores in membrane 140 is substantially greater (e.g. about 10 times greater) than the average diameter of absorptive particles 26.
  • the pores in membrane 140 constitute a sufficiently large fraction (e.g. at least 20%) of the total surface area of membrane 140 to permit substantially unimpeded passage of absorptive particles 26 through membrane 140.
  • Membrane 40 can be formed of a porous membrane material such as a polycarbonate or fibre- weave membrane.
  • Membrane 140's outward surface 142 is highly reflective, and may be either diffusely or specularly reflective.
  • a suitably reflective membrane 140 can be formed from an intrinsically refiec- tive material such as a multilayer broadband reflector (e.g. Multilayer Optical Film available from 3M, St. Paul, MN) or aluminized MylarTM flexible film, or by coating outward surface 142 with a reflective (e.g. aluminum) film using standard vapour deposition techniques.
  • a multilayer broadband reflector e.g. Multilayer Optical Film available from 3M, St. Paul, MN
  • aluminized MylarTM flexible film e.g. aluminum film
  • ray 144) which would otherwise have been absorbed by non-reflective circular regions 82 are instead reflected (e.g. ray 146) by membrane 140's reflective outward surface 142.
  • Light rays e.g. ray 148, which are incident upon reflective annular regions 80 are totally internally reflected (e.g. ray 150) as previously explained.
  • Membrane 140's pores allow absorptive particles 26 to move outwardly into contact with hemi-beads 60 in the absorptive state; and to move inwardly away from hemi-beads 60 in the reflective state, thus obscuring absorptive particles 26 from direct view in the reflective state.
  • the brightness enhancement (i.e. reflectance) attainable via the Figure 9 technique can be estimated. For example, if membrane 140's outward surface 142 is assumed to have an overall reflectance of about 60% , and is also assumed to affect the entirety of the previously explained 50% absorptive loss area, a brightness enhancement of about 30% (i.e. 50% of 60%) is attained.
  • Figure 10 depicts another alternative display brightness (i.e. reflectance) enhancement technique in which outward sheet 12 's interstitial regions 160 between hemi-beads 60 are modified to increase reflectance. This is achieved by partially embedding spherical beads 14 in outward sheet 12 such that the reflective polymer material used to form sheet 12 protrudes inwardly, as indicated at 162, in an approximately hemispherical shape, through interstitial regions 160 and between the hemi-bead portions 60 of spherical beads 14.
  • reflective polymeric structures 162 each have a "perfect" hemispherical shape (which is theoretically ideal, but unattainable in practice), then the light reflecting and absorption characteristics of polymeric structures 162 will be identical to those of hemi-beads 60 as explained above.
  • polymeric structures 162 are preferably hemispherically shaped in order to achieve the desired reflectance characteristics, they need not be perfectly hemispherical.
  • Polymeric structures 162 need only be substantially hemispherical in that their inward surfaces should have sufficiently high curvature to cause TIR of incident light rays. TIR which occurs in polymeric structures 162 can be frustrated by absorptive particles 26 in the same manner as previously described in relation to hemi-beads 60.
  • TIR does not normally occur in interstitial regions 160, thus reducing sheet 12' s overall reflectance. If hemi-beads 60 have a hexag- onally closest packed arrangement, their overall average surface reflectance is 91 % as previously explained, with the remaining 9% being lost due to light absorption in interstitial regions 160. By facilitating TIR in interstitial regions 160, the Figure 10 brightness enhancement technique reduces this 9% loss by theoretically increasing to close to 100% the percentage of sheet 12 which bears useful light reflecting structures. [0059] Instead of partially embedding spherical beads 14 in outward sheet 12, brightness can be enhanced by minimizing the size of interstitial regions 160.

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  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Molecular Biology (AREA)
  • Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)

Abstract

L’invention concerne un affichage réfléchissant ayant une pluralité de semi-cordons transparents (60), ayant chacun une région réfléchissante (80) entourant une région non réfléchissante (82). Des particules d’absorption de lumière (26) sont suspendues dans, s’écartent et se rapprochent des semi-cordons (60), en frustrant ou facilitant de manière sélective la réflexion totale interne de rayons de lumière incidents sur les semi-cordons (60). On augmente la réflectance de l’affichage en réfléchissant de manière sélective des rayons de lumière à travers les régions non réfléchissantes des semi-cordons (82), par exemple en formant une électrode à motifs (48) avec une région électriquement conductrice (104) et une pluralité de régions réfléchissantes (108) ; en alignant les régions réfléchissantes de l’électrode (108) avec les régions non réfléchissantes des semi-cordons (82) ; et en appliquant une tension à travers l’électrode (48) de part et d’autre du milieu (20) pour déplacer par électrophorèse les particules (26) entre une position dans laquelle elles recouvrent sensiblement les semi-cordons (60), et une autre position dans laquelle elles recouvrent sensiblement la région conductrice de l’électrode (104) sans recouvrir les régions réfléchissantes de l’électrode (108).
PCT/CA2006/000559 2005-04-15 2006-04-12 Amélioration de la brillance dans les affichages d’image réfléchissants électrophorétiques modulés tir WO2006108285A1 (fr)

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US60/671,538 2005-04-15
US75977206P 2006-01-17 2006-01-17
US60/759,772 2006-01-17

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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007118306A1 (fr) * 2006-04-19 2007-10-25 The University Of British Columbia Electrophorese ionique dans des affichages d'images reflechissants modules par reflexion interne totale
EP2071395A1 (fr) * 2007-12-10 2009-06-17 Konica Minolta Business Technologies, Inc. Dispositif d'affichage comprenant un filtre de couleur structurel
US7760417B2 (en) 2006-01-17 2010-07-20 The University Of British Columbia Brightness enhancement by fluid interface deformation in TIR-modulated displays
WO2014160552A1 (fr) 2013-03-26 2014-10-02 Clearink Displays Llc Électrode poreuse déplacée pour empêcher une réflexion interne totale (tir)
WO2014146937A3 (fr) * 2013-03-22 2014-12-24 Vlyte Innovations Limited Dispositif électrophorétique présentant un état lumineux transparent
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US9280029B2 (en) 2013-05-13 2016-03-08 Clearink Displays, Inc. Registered reflective element for a brightness enhanced TIR display
US9746740B2 (en) 2013-05-13 2017-08-29 Clearink Displays, Inc. Registered reflective element for a brightness enhanced TIR display
US10203436B2 (en) 2013-05-22 2019-02-12 Clearink Displays, Inc. Method and apparatus for improved color filter saturation
US9939707B2 (en) 2013-07-08 2018-04-10 Clearink Displays, Inc. TIR-modulated wide viewing angle display
US10705404B2 (en) 2013-07-08 2020-07-07 Concord (Hk) International Education Limited TIR-modulated wide viewing angle display
US9740075B2 (en) 2013-09-10 2017-08-22 Clearink Displays, Inc. Method and system for perforated reflective film display device
US9612501B2 (en) 2013-09-30 2017-04-04 Clearink Displays, Inc. Method and apparatus for front-lit semi-retro-reflective display
US10324353B2 (en) 2013-10-22 2019-06-18 Vlyte Innovations Limited Wide operating temperature range electrophoretic device
US11156893B2 (en) 2013-10-22 2021-10-26 E Ink Corporation Wide operating temperature range electrophoretic device
US11708720B2 (en) 2013-10-22 2023-07-25 E Ink Corporation Light-modulating electrophoretic device
US9897890B2 (en) 2014-10-07 2018-02-20 Clearink Displays, Inc. Reflective image display with threshold
US10304394B2 (en) 2014-10-08 2019-05-28 Clearink Displays, Inc. Color filter registered reflective display
US10509242B2 (en) 2015-04-10 2019-12-17 Vlyte Innovations Limited Micro-fastened, sealed light modulator
US10386691B2 (en) 2015-06-24 2019-08-20 CLEARink Display, Inc. Method and apparatus for a dry particle totally internally reflective image display
US10261221B2 (en) 2015-12-06 2019-04-16 Clearink Displays, Inc. Corner reflector reflective image display
US10386547B2 (en) 2015-12-06 2019-08-20 Clearink Displays, Inc. Textured high refractive index surface for reflective image displays

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