WO2018145031A1

WO2018145031A1 - Lateral migration mitigation in tir-based image displays

Info

Publication number: WO2018145031A1
Application number: PCT/US2018/016909
Authority: WO
Inventors: Bram M. SADLIK; Robert J. Fleming; Steven Gou; Scott W. Ferguson; Rob HANNEBAUER; Alex Henzen
Original assignee: Clearink Displays Inc
Priority date: 2017-02-06
Filing date: 2018-02-05
Publication date: 2018-08-09
Also published as: CN110476109A

Abstract

The disclosed embodiments relate to lateral migration of particles in a totally internally reflective displays. In certain embodiments, the reflective image displays include partial and full walls to form partitions within the display. The walls mitigate diffusion and lateral migration or drift of electrophoretically mobile particles due to lateral electric fields at adjacent pixels. This improves image quality, bistability and long-term display performance.

Description

Lateral Migration Mitigation in TIR-Based Image Displays

The instant specification claims priority to the United States Provisional Application Serial No. 62/455,271 (filed February 6, 2017).

Field

This disclosure is directed to total internal reflection-based image displays. In one embodiment, the disclosure relates to mitigation of lateral migration of electrophoretically mobile particles by incorporating partition walls. The partition walls may be partial or full walls.

BACKGROUND

Conventional total internal reflection (TIR) based displays include, among others, a transparent high refractive index front sheet in contact with a low refractive index fluid. The front sheet and fluid may have different refractive indices that may be characterized by a critical angle 9_C. The critical angle characterizes the interface between the surface of the transparent front sheet (with refractive index ηί) and the low refractive index fluid (with refractive index r\i). Light rays incident upon the interface at angles less than Q_c may be transmitted through the interface. Light rays incident upon the interface at angles greater than Q_c may undergo TIR at the interface. A small critical angle (e.g. , less than about 50°) is preferred at the TIR interface since this affords a large range of angles over which TIR may occur. It may be prudent to have a fluid medium with preferably as small a refractive index (ηι) as possible and to have a transparent front sheet composed of a material having a refractive index (ηι) preferably as large as possible. The critical angle, Q_c, is calculated by the following equation (Eq. 1):

Conventional TIR-based reflective image displays further include electrophoretically mobile, light absorbing particles. The electrophoretically mobile particles move in response to a bias between two opposing electrodes. When particles are moved by a voltage bias source to the surface of the front sheet they may enter the evanescent wave region where TIR may be frustrated. The depth of the evanescent wave region is typically about 0.25 Dm, though this can vary with wavelength of incident light and the refractive indices of the front sheet and medium. Incident light may be absorbed by the electrophoretically mobile particles to create a dark state observed by the viewer. Under such conditions, the display surface may appear dark or black or other color depending on the color of the particles to the viewer. When the particles are moved out of the evanescent wave region (e.g., by reverse biasing), light may be reflected by TIR. This creates a white or bright state that may be observed by the viewer. An array of pixelated electrodes may be used to drive the particles into and out of the evanescent wave region to form combinations of white and dark states. This may be used to create images or to convey information to the viewer.

The front sheet in conventional TIR-based displays typically includes a plurality of close- packed convex structures on the inward side facing the low refractive index medium and electrophoretically mobile particles (i.e., the surface of the front sheet which faces away from the viewer). The convex structures may be hemispherically-shaped but other shapes may be used. The hemispherically-shaped convex structures may also be referred to as lenses. A conventional TIR-based display 100 is illustrated in Fig. 1. Display 100 is shown with a transparent front sheet 102 further comprising a layer of a plurality of hemispherical protrusions 104, a rear support sheet 106, a transparent front electrode 108 on the surface of the hemispherical protrusions and a rear electrode 110. Fig. 1 also shows low refractive index fluid 112 which is disposed within the cavity or gap formed between the surface of protrusions 104 and the rear support sheet. The fluid 112 contains a plurality of light absorbing electrophoretically mobile particles 114. Display 100 includes a voltage source 116 capable of creating a bias across the cavity. When particles 114 are electrophoretically moved near the front electrode 108, they may frustrate TIR. This is shown to the right of dotted line 118 and is illustrated by incident light rays 120 and 122 being absorbed by the particles 114. This area of the display will appear as a dark state to viewer 124.

When particles are moved away from front sheet 102 towards rear electrode 110 (as shown to the left of dotted line 118) incident light rays may be totally internally reflected at the interface of the surface of electrode 108 on hemispherical array 104 and medium 112. This is represented by incident light ray 126, which is totally internally reflected and exits the display towards viewer 124 as reflected light ray 128. The display appears white or bright to the viewer.

Pulse and DC (direct current) driving schemes may be utilized to derive and maintain desired optical state (i.e. gray state) levels within the pixels of the display. The driving schemes may comprise one or more of variable applied positive or negative voltages, variable voltage ON times (i.e. ON state pulse widths) and variable voltage OFF times (i.e. OFF state pulse widths).

The most dominant movement principle by which electrophoretically charged particles flow is along the electric field lines as imposed by the electrodes in the display. The movement of these particles under the influence of an electric field is called drift. A second movement principle, diffusion, is one of equalization of concentration gradients. A third movement principle is gravity. One general issue with electrophoretic displays is that when two adjacent electrodes are charged oppositely, there exists lateral electric field components. These lateral electric field components may pull the electrophoretically mobile particles laterally into the neighboring pixel. This situation arises when the two adjacent pixels are driven to different states (such as black and white). This effect may lower the quality of the display image.

Additionally, the particles may segregate and/or migrate over time further degrading the performance of the display. This disclosure describes an approach to mitigate the lateral migration of the mobile particles in the presence of lateral electric fields in reflective

electrophoretic image displays.

BRIEF DESCRIPTION OF DRAWINGS

These and other embodiments of the disclosure will be discussed with reference to the following exemplary and non-limiting illustrations, in which like elements are numbered similarly, and where:

Fig. 1 schematically illustrates a cross-section of a portion of a prior art TIR-based display;

Fig. 2A schematically illustrates electric field lines in a cross-section of a portion of a TIR- based display;

Fig. 2B schematically illustrates electric field lines in a cross-section of a portion of a TIR- based display;

Fig. 3 schematically illustrates electric field lines in a cross-section of a portion of a TIR- based display comprising a partial wall;

Fig. 4 schematically illustrates electric field lines in a cross-section of a portion of a TIR- based display comprising partial walls;

Fig. 5 schematically illustrates an embodiment of the disclosure having multiple partial walls;

Fig. 6 schematically illustrates a cross-section of a portion of a reflective display 600 comprising partial walls;

Fig. 7 schematically illustrates a cross-section of a portion of a reflective display 800 comprising partial walls;

Fig. 8 schematically illustrates a cross-section of a portion of one embodiment of a reflective display comprising full walls; Fig. 9 schematically illustrates a cross-section of a portion of one embodiment of a reflective display comprising full walls;

Fig. 10A schematically illustrates a cross-section of a portion of a TIR-based display with rounded walls;

Fig. 10B schematically illustrates a cross-section of a portion of a TIR-based display with rounded walls and base;

Fig. IOC schematically illustrates a cross-section of a portion of a TIR-based display with rounded walls;

Fig. 11 schematically illustrates a cross-section of an embodiment to assemble a TIR-based display with a full wall;

Fig. 12A schematically illustrates a portion of a front sheet comprising walls on the surface of convex protrusions;

Fig. 12B schematically illustrates a portion of a front sheet comprising walls between rows of convex protrusions;

Fig. 12C schematically illustrates a portion of a front sheet comprising walls on the surface of the convex protrusions and between rows of convex protrusions;

Fig. 13 A schematically illustrates a portion of a front sheet comprising walls and color filter sub-pixels on the surface of convex protrusions that may be integrated into a reflective image display;

Fig. 13B schematically illustrates a portion of a front sheet comprising walls and color filter sub-pixels on the surface of convex protrusions that may be integrated into a reflective image display;

Fig. 13C schematically illustrates a portion of a front sheet comprising walls and color filter sub-pixels on the surface of convex protrusions that may be integrated into a reflective image display;

Fig. 13D schematically illustrates a portion of a front sheet comprising full walls with interruptions and color filter sub-pixels on the surface of convex protrusions that may be integrated into a reflective image display;

Fig. 14 schematically illustrates a portion of a color filter sub-pixel array comprising walls that are positioned between specific sub-pixel colors that may be integrated into a reflective image display; Fig. 15 schematically illustrates an embodiment of a TFT array to drive a display;

Fig. 16A schematically illustrates a cross-section of a TFT array on a transparent sheet;

Fig. 16B schematically illustrates a cross-section of a TFT array on a transparent sheet comprising a photoresist layer; Fig. 16C schematically illustrates a cross-section of a TFT array on a transparent sheet comprising a photoresist layer exposed to UV light;

Fig. 16D schematically illustrates a cross-section of a TFT array on a transparent sheet comprising self-aligned pixel walls;

Fig. 17A schematically illustrates a cross-section of a TFT array on a transparent sheet comprising a planarization layer;

Fig. 17B schematically illustrates a cross-section of a TFT array on a transparent sheet comprising a planarization layer and a photoresist layer;

Fig. 17C schematically illustrates a cross-section of a TFT array on a transparent sheet comprising a planarization layer and a photoresist layer exposed to UV light;

Fig. 17D schematically illustrates a cross-section of a TFT array on a transparent sheet comprising a planarization layer and self-aligned pixel walls;

Fig. 17E schematically illustrates a cross-section of a portion of a TIR-based reflective image display comprising self-aligned pixel walls; and

Fig. 18 schematically illustrates an exemplary system for implementing an embodiment of the disclosure.

DETAILED DESCRIPTION

Throughout the following description specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well-known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense.

The disclosure generally relates to migration mitigation of electrophoretically mobile particles in reflective image displays. According to certain embodiments of the disclosure, a TIR based image display comprises an array of inward convex protrusions and one or both of partial or full walls forming compartments. The compartments formed from walls confine the electrophoretically mobile particles either fully or partially within the partition formed by the walls.

In an exemplary embodiment, the walls further comprise a dielectric layer. The compartments may be substantially aligned with one or more color filter sub-pixels and one or more thin film transistors (TFTs).

In certain embodiments, the compartments are substantially aligned with a respective one of the color filter sub-pixels. In other embodiments, the compartments are not be substantially aligned with the color filter sub-pixels. The color filter sub-pixels may be substantially aligned with TFTs. A TIR image display may comprise walls that are formed on the convex protrusions or between the convex protrusions or a combination of both. In some embodiments, a TIR image display may comprise one or more dielectric layers on one or more of the front electrode, rear electrode and walls. A TIR image display may comprise a continuous array of convex protrusions and walls. The continuous array of protrusions and walls may be formed simultaneously by one or more of embossing, thermal embossing, injection molding, photolithography, micro-fabrication or micro-replication from a metal shim master. In certain embodiments, walls may be placed on a planarized rear electrode layer. In certain embodiments, using the backplane TFT array as a photo-mask, self-aligned walls may be formed by a photolithographic method.

Fig. 2A schematically illustrates electric field lines in a cross-section of a portion of a TIR- based display 200. Display 200 is similar to display 100 in Fig. 1 but with certain omissions for clarity of the illustration. A voltage source and electrophoretically mobile particles are not shown but may be included in exemplary embodiments of an operating display. Display 200 comprises transparent outward sheet 202, plurality of convex protrusions 204, front surface 206 facing viewer 208, transparent front electrode 210 and dielectric layer 21 1 located on the surface of convex protrusions 204, rear support 212, first rear pixel electrode 214, second rear pixel electrode 216, gap 218 between said first and second rear pixel electrodes, cavity 220 formed by the outward sheet 202 and rear support 212 and an air or liquid medium 222.

Fig. 2A illustrates a representative cross-section and the effect of adjacent pixels 214, 216 driven to different states, such as black and white, on the electric field lines. The ground electrode 210, the first pixelated rear or back electrode 214 (denoted by "+V") and second adjacent pixelated rear or back electrode 216 (denoted by "-V") in display 200 in Fig. 2, are assumed to each be substantially equipotentials. An equipotential is where the magnitude of the voltage bias may be about the same. This is imposed by the conductivity of the material but may have a positive or negative bias. The electric field lines (represented by directional arrows) located within cavity 220 flow from a higher potential (+V) to a lower potential (-V). It should be noted that electrical conductors that make up the front and rear electrodes may have field lines that leave the surface at right angles (normal) to their surface. This means that near the surface of the electrodes, there may be minimal or very low lateral components to the electric field, thus there are no lateral fields that drive the drift of particles immediately adjacent to the electrode. This is true of the locations 224, 226, 228 marked by dotted line boxes in Fig. 2A.

Near gap 218 (marked by dotted line box 230 in Fig. 2A) the electric fields near electrode 214 are still vertical but they may rapidly turn and point to the lower voltage electrode 216 that lies nearby. This is because the ground electrode 210, being much further away, may have little or no influence. The field lines may terminate at the adjacent electrode instead of crossing gap 220 to the ground electrode 210.

Fig. 2B schematically illustrates electric field lines in a cross-section of a portion of a TIR- based display 200. Fig. 2B illustrates the greatest effect of the electric field lines on

electrophoretically mobile particles in display 200. Suspended in medium 222 are pluralities of positively charged electrophoretically mobile particles in shaded areas 224, 226. Shaded areas 224, 226 represent aggregation of particles in each locations. In this and other example displays in this disclosure, particles 224, 226 may comprise a positive charge polarity for illustrative purposes only. In some embodiments one or more of the particles may instead comprise a negative polarity. Particles represented by shaded area 224 denote where the layer of positively charged particles may be attracted to and reside if attracted to a negative voltage bias at front electrode 210. Particles represented by shaded area 226 denote where the layer of particles may be attracted to and reside if attracted to a negative voltage bias at rear electrodes 216.

In Figs. 2-5, the electric fields shown indicate the initial forces that are imposed on the particle once the voltage bias is applied. The addition of particles may influence the local electric fields. It must be noted that the electric fields within the cell and the redistribution of charge through electrophoretic motion may be dictated by Gauss's Law. In the differential form, Gauss's Law is expressed in Equation (2) as follows: - £ = (2)

Where VE is the divergence of the electric field, p is the total electric charge density and so is the electric constant. This shows that the presence of charge directly affects the divergence of the electric field. The end state electric field may be different than those shown herein once the particles are in position against the electrodes. Fig. 2B illustrates where positively charged particles may be ideally located when electrodes 214 and 216 are driven to opposing voltages. If a positive voltage (+V) is applied at rear pixel electrode 214, the opposing ground electrode 210 would be at a negative voltage bias. This would attract the positively charged particles to approximately the shaded region 224. If a negative voltage bias (-V) is applied at rear pixel electrode 216, the opposing ground electrode 210 would be at a positive voltage bias. The positively charged particles would be attracted to the rear electrode surface 216 and may be located approximately in shaded region 226.

The lateral electric fields may have the most effect on the drift of particles located at rear electrode 216 in region 228 (highlighted by a dotted line box). Thus, the drift of the particles may be most affected where pixels are adjacent and are driven to opposite voltages. Charged particles located at the surface may also affect the electric field lines differently than what is illustrated in the Figures. For example, location 228 in Fig. 2B shows where particle lateral migration into the bulk of cavity 220 may be greatest. To a lesser extent, particles may laterally migrate away from location 230 at front electrode 210 and into the bulk of cavity 220. The particle migration may be due to particle diffusion. The particles may remain in place at all other locations within the cell where the electric field lines are substantially normal to the front and rear electrodes. The particles may also move slightly where the electric field lines are substantially normal to the front and rear electrodes.

Fig. 3 schematically illustrates electric field lines in a cross-section of a portion of a TIR- based display 300 comprising a partial wall. Display 300 embodiment comprises a transparent outward sheet 302 with an inward array of convex protrusions 304. In some embodiments, sheet 302 and protrusions 304 may be a continuous sheet of the same material. In other embodiments, sheet 302 and protrusions 304 may be separate layers and comprise different materials. In an exemplary embodiment, sheet 302 and protrusions 304 may comprise different refractive indices. In an exemplary embodiment, sheet 302 may comprise a flexible glass. In an exemplary embodiment, sheet 302 may comprise glass of thickness in the range of about 20-250 D m. Sheet 302 may comprise a flexible glass such as SCHOTT AF 32® eco or D 263® T eco ultra-thin glass. Sheet 302 may comprise a polymer such as polycarbonate. In an exemplary embodiment, sheet 302 may comprise a flexible polymer. In an exemplary embodiment, protrusions 304 may comprise a high refractive index polymer. In some embodiments, convex protrusions 304 may be in the shape of hemispheres or cones or a combination thereof. Protrusions 304 may be of any shape or size or a mixture of shapes and sizes. Protrusions 304 may be elongated hemispheres or hexagonally shaped or a combination thereof. In other embodiments the convex protrusions may be microbeads embedded in sheet 302. Protrusions 304 may have a refractive index of about 1.5 or higher. In an exemplary embodiment, protrusions 304 may have a refractive index of about 1.5-1.9. The protrusions may have a diameter of at least about 0.5 microns. The protrusions may have a diameter of at least about 2 microns. In some embodiments the protrusions may have a diameter in the range of about 0.5-5000 microns. In other embodiments the protrusions may have a diameter in the range of about 0.5-500 microns. In still other embodiments the protrusions may have a diameter in the range of about 0.5-100 microns. The protrusions may have a height of at least about 0.5 microns. In some embodiments the protrusions may have a height in the range of about 0.5-5000 microns. In other embodiments the protrusions may have a height in the range of about 0.5-500 microns. In still other embodiments the protrusions may have a height in the range of about 0.5- 100 microns. In certain embodiments, the protrusions may include materials having a refractive index in the range of about 1.5 to 2.2. In certain other embodiments, the high refractive index protrusions may be a material having a refractive index of about 1.6 to about 1.9.

In some embodiments, sheet 302 and protrusions 304 may be a continuous sheet of substantially the same material. In other embodiments, sheet 302 and protrusions 304 may be formed of different materials having similar or different refractive indices. In some

embodiments, sheet 302 may comprise glass. Sheet 302 may comprise a polymer such as polycarbonate. In an exemplary embodiment, protrusions 304 may comprise a high refractive index polymer. Protrusions 304 may be comprise a substantially rigid, high index material. High refractive index polymers that may be used may comprise high refractive index additives such as metal oxides. The metal oxides may comprise one or more of SiC , ZrC , ZnC , ZnO or TiC . In some embodiments, the convex protrusions may be randomly sized and shaped. In some embodiments the protrusions may be faceted at the base and morph into a smooth hemispherical or circular shape at the top. In other embodiments, protrusions 304 may be hemispherical or circular in one plane and elongated in another plane. In some embodiments, sheet 302 and layer of convex protrusions 304 may be a continuous layer. In an exemplary embodiment, the convex protrusions 304 may be manufactured by micro-replication. In an exemplary embodiment, sheet 302 may be a flexible, stretchable or impact resistant material while protrusions 304 may comprise a rigid, high index material.

Display 300 further comprises outward front surface 306 facing a viewer 308. Display 300 may further comprise a transparent front electrode 310 located on the inward surface of protrusions 304. Front electrode layer 310 may be flexible or conformable. Front electrode layer 310 may comprise a transparent conductive material such as indium tin oxide (ITO), Baytron™, or conductive nanoparticles, silver wires, metal nanowires, graphene, nanotubes or other conductive carbon allotropes or a combination of these materials dispersed in a substantially transparent polymer. Front electrode layer 310 may comprise a transparent conductive material further comprising silver nano-wires manufactured by C3Nano (Hay ward, CA, USA). Front electrode layer 310 may comprise C3Nano ActiveGrid™ conductive ink.

Display 300 may further comprise a rear support 312. Rear support 312 may be one or more of a metal, polymer, wood or other material. Rear support 312 may be one or more of glass, polycarbonate, polymethylmethacrylate (PMMA), polyurethane, acrylic, polyvinylchloride (PVC), polyimide or polyethylene terephthalate (PET).

Display 300 may further comprise a rear electrode lay er 31 1. Rear electrode layer 311 may comprise a plurality of pixels. For illustrative purposes, two pixels are shown in Fig. 3, first rear pixel electrode 314 and second rear pixel electrode 316. In some embodiments, there may also be a gap 318 between first and second rear pixel electrodes 314, 316. A cavity 320 may be formed by the outward sheet 302 and rear support 312. Rear electrode layer 311 may be located on the inner surface of rear support layer 312. Rear electrode layer 311 may be flexible or conformable. Rear electrode layer 311 may comprise transparent conductive material or non- transparent conductive material such as aluminum, gold or copper. Rear electrode layer 311 may be vapor deposited or electroplated. Rear electrode layer 311 may be continuous or patterned. Rear electrode layer 31 1 may be integrated with rear support layer 312. Alternatively, rear electrode layer 311 may be positioned proximal to rear support 312. In another embodiment, rear electrode layer 31 1 may be laminated or attached to rear support 312. Rear electrode layer 311 may comprise a thin film transistor (TFT) array or a passive matrix array. Rear electrode layer 311 may comprise a direct drive patterned array of electrodes or a segmented array of electrodes. Rear electrode layer 311 may comprise an active matrix of organic field-effect transistors (FETs). The organic FETs may comprise an active semiconducting layer of a conjugated polymer or a small conjugated molecule. The organic FETs may comprise an organic dielectric layer in the form of either a solution processed dielectric or a chemical vapor deposited dielectric. Layer 311 may comprise aluminum, ITO, copper, gold or other electrically conductive material. In one embodiment, layer 311 may comprise organic TFTs. In other embodiments, layer 311 may comprise indium gallium zinc oxide (IGZO) TFTs. Layer 311 may comprise low temperature polysilicon, low temperature polysilicon manufactured by a polyimide "lift-off process, amorphous silicon on a flexible substrate or TFTs on flexible substrates manufactured by FlexEnable (Cambridge, United Kingdom) or those manufactured by

FlexEnable and Merck (Darmstadt, Germany). In an exemplary embodiment, each TFT of rear electrode layer 311 may be substantially aligned or registered with at least one single color filter sub-pixel. In an exemplary embodiment, layer 31 1 may comprise a planarization layer. A planarization layer may be used to smooth the surface of the backplane drive electronics. This may allow complete walls or partial walls to be placed or formed on top of the planarization layer. The planarization layer may comprise a polymer. The planarization layer may be deposited using a slot die coating process or flexo-print process. The planarization layer may comprise a photoresist. The planarization layer may comprise at least one dielectric. The planarization layer may comprise a polyimide.

Display 300 further comprises a fluid or air medium 322. Medium 322 may be located in cavity 320 between front electrode layer 310 and rear electrode layer 31 1. Medium 322 may comprise a low refractive index. Medium 322 may be an inert, low refractive index fluid medium. Medium 322 may be a hydrocarbon or water. In other embodiments, the refractive index of medium 322 may be about 1 to 1.5. In still other embodiments the refractive index of medium 322 may be about 1.1 to 1.4. In an exemplary embodiment, medium 322 may be a fluorinated hydrocarbon. In another exemplary embodiment, medium 322 may be a

perfluorinated hydrocarbon. In an exemplary embodiment, medium 322 has a lower refractive index than the refractive index of convex protrusions 304. In other embodiments, medium 322 may be a mixture of a hydrocarbon and a fluorinated hydrocarbon. In an exemplary

embodiment, medium 322 may comprise one or more of Fluorinert™, Novec™ 7000, Novec™ 7100, Novec™ 7300, Novec™ 7500, Novec™ 7700, Novec™ 8200, Teflon™ AF, CYTOP™ or Fluoropel™.

In other embodiments, medium 322 may also comprise an electrowetting fluid. In an exemplary embodiment, the electrowetting fluid may comprise a dye. The electrowetting fluid may move towards protrusions 304 into the evanescent wave region to frustrate TIR. The electrowetting fluid may move away from protrusions 304 and out of the evanescent wave region to allow for TIR. The electrowetting fluid may be a silicone oil that may be pumped via small channels into and out of the wells formed by the walls.

In an exemplary embodiment, display 300 may further comprise an optional dielectric layer 324 located on the surface of the transparent front electrode 310. In some embodiments, display 300 may further comprise an optional dielectric layer 325 located on the surface of rear electrode layer 311. The one or more optional dielectric layers may be used to protect one or both of the front electrode layer 310 and/or rear electrode layer 31 1. In some embodiments, the dielectric layer on the front electrode layer may comprise a different composition than the dielectric layer on the rear electrode layer. The dielectric layers may be substantially uniform, continuous and substantially free of surface defects. The dielectric layer may be at least about 5 nm in thickness or more. In some embodiments, the dielectric layer thickness may be about 5 to 300 nm. In other embodiments, the dielectric layer thickness may be about 5 to 200 nm. In still other embodiments, the dielectric layer thickness may be about 5 to 100 nm. The dielectric layers may each have a thickness of at least about 30 nanometers. In an exemplary embodiment, the thickness may be about 30-200 nanometers.

In other embodiments, parylene may have a thickness of about 20 nanometers. The dielectric layers may comprise at least one pin hole. The dielectric layer may define a conformal coating and may be free of pin holes or may have minimal pin holes. The dielectric layer may also be a structured layer. The dielectric layer may also act as a barrier layer to prevent moisture or gas ingress. The dielectric layers may have a high or low dielectric constant. The dielectric layers may have a dielectric constant in the range of about 1-15. Dielectric compounds may be organic or inorganic in type. The most common inorganic dielectric material is SiC commonly used in integrated chips. The dielectric layer may be one or more of SiN, SiNx or SiON. The dielectric layer may be AI2O3. The dielectric layer may be a ceramic. Organic dielectric materials are typically polymers such as polyimides, fiuoropolymers, polynorbornenes and hydrocarbon-based polymers lacking polar groups. The dielectric layers may be a single polymer or a combination of polymers. The dielectric layers may comprise one or more of the following polyimide-based dielectrics Dalton DL-5260T, TC-139, DL-2193, Nissan SE-150, SE- 410, SE-610, SE-3140N, SE-3310, SE-3510, SE-5661, SE-5811, SE-6414, SE-6514, SE-7492, SE-7992 or JSR AL-1054, AL-3046, AL22620, AL16301, AL60720. The dielectric layers may be combinations of polymers, metal oxides and ceramics. In an exemplary embodiment, the dielectric layers comprise parylene. In other embodiments the dielectric layers may comprise a halogenated parylene. The dielectric layers may comprise parylene C, parylene N, parylene HT or parylene HTX. Other inorganic or organic dielectric materials or combinations thereof may also be used for the dielectric layers. One or more of the dielectric layers may be CVD or sputter coated. One or more of the dielectric layers may be a solution coated polymer, flexo-printed polymer, vapor deposited dielectric or sputter deposited dielectric. Dielectric layer 325 may be conformal to electrode structures or could be used to planarize the electrode structures.

Display 300 in Fig. 3 may comprise a voltage bias source 326. Voltage bias source 326 may be used to create a bias within cavity 320 between front electrode 310 and rear electrode layer 311. A bias may be applied to move electrophoretically mobile particles 328 within cavity 320. Bias source 326 may be coupled to one or more processor circuitry and memory circuitry configured to change or switch the applied bias in a predefined manner and/or for predetermined durations.

Suspended in medium 322 are one or more pluralities of positively charged

electrophoretically mobile particles. In other embodiments, particles 328, 330 may comprise a negative charge polarity. Particles are represented by shaded areas 328, 330 to denote where the particles would be attracted to and reside if attracted to a negative voltage bias (-V) at the front 310 or rear pixel electrode 316. Particles 328, 330 may be formed of an organic material or an inorganic material or a combination of an organic and inorganic material. The particles may have a polymer coating. Particles 328, 330 may comprise a coating of an organic material or an inorganic material or a combination of an organic and inorganic material. Particles 328, 330 may be a dye or a pigment or a combination thereof. Particles 328, 330 may be at least one of carbon black, a metal or metal oxide. Particles 328, 330 may comprise weakly charged or uncharged particles. Particles 328, 330 may be light absorbing or light reflecting or a combination thereof. Particles 328, 330 may also have any light absorption characteristics such that they may impart any color of the visible spectrum or a combination of colors to give a specific shade or hue.

Display 300 may further comprise a plurality of light reflecting particles suspended in medium 322. The light reflective particles may comprise a white reflective particle such as titanium dioxide (TiCh). The light reflective particles may comprise a positive charge polarity, negative charge polarity or neutral charge polarity or a combination thereof. The light reflective particles may be around 200-300nm. This is a typical size of TiCh particles used in the paint industry to maximize light reflectance properties. Particles of larger or smaller sizes may also be used. The light reflective particles may further comprise a coating (not shown). The coating on the light reflecting materials may comprise an organic material or an inorganic material such as a metal oxide. The coating may comprise of an effective refractive index that is substantially similar to the refractive index of medium 322. In some embodiments, the difference between the refractive indices of the coating on the light reflecting particles and medium 322 may be about 40% or less. In other embodiments, the difference between the refractive indices of the coating on the light reflecting particles and medium 322 may be about 0.5-40%.

Transparent front electrode 310 may be a conformal coating on the surface of the convex protrusions 304. Electrode layer 310 may not affect the total internal reflection of light rays at the surface of the convex protrusions 304. In some embodiments electrode 310 may be one or more of indium tin oxide (ITO), a conductive polymer such as BAYTRON™, conductive nanoparticles dispersed in a clear polymer or other transparent conductor. In some embodiments, rear electrodes 314, 316 may be part of a passive matrix array of electrodes. In other embodiments, rear electrodes 314, 316 may be part of a patterned array of direct drive electrodes. In other embodiments, rear electrodes 314, 316 may be part of a thin film transistor (TFT) array of electrodes.

In order to mitigate, retard or diminish, lateral particle migration, walls 332 (represented by cross hatched lines in Fig. 3) may be added. Walls may also be referred to as partition walls, sidewalls or cross walls. In this embodiment, partial walls may be added to the rear of the cell nearest the location between adjacent pixel electrodes 314, 316. In one embodiment, partial walls do not completely bridge rear sheet 312 to front sheet 302. As shown in Fig. 3, the partial wall 332 may be located between adjacent pixels to limit, reduce and retard drift-induced lateral migration of the particles.

In an exemplary embodiment, the rear electrodes and rear support may be planarized with a planarization layer. A planarization layer may comprise a dielectric. The wall may be formed on top of the planarization layer. In an exemplary embodiment, the surface of partial walls may be coated with a dielectric layer 333. The walls may be formed in a periodic or random array. The walls may comprise one or more of the following materials: AZ Electronic Materials (Charlotte, NC, USA) AX series, DX series, EXP series, HiR 1075, MiR 701, MiR 703, MiR 900, N6000, nLOF 2000, nLOF 5000, 3300, 3300-F, 1500, N4000, P4000 series, 4500 series, 9200 series, 10XT, 50XT, PLP-30, PLP-40, 5XT series, 12XT series, 40XT series, 125nXT series, 5nXT/15nXT, TX 1311 ; DOW® (Midland, MI, US) Laminar series, Eagle 2100 ED, Photoposit series, Epic 2135, UVN 2300, UV series, MCPR i7010N, Megaposit SPR 955-CM; DuPont® (Wilmington, DE, USA) Riston Etchmaster 213/830, Riston Goldmaster GM100, Riston MultiMaster MM100i/MM500, Riston PlateMaster PM200/PM300, Riston TentMaster TM200i, Riston Laser LDI 300/500/7000/7200/8000, Riston FX 250/500/900; Eternal Materials Co. (Kaohsiung City, Taiwan) Etertec Series, Laminar Series; Fujifilm (Tokyo, Japan) FEP-100, FEN-100, GAR series, GKR series, SC series, HNR series, HR series, IC series, HPR 500 series, OCG 825, HiPR 6500 series, OiR series, FHi series, GiR 1102, PMMA; Hitachi (Chiyoda, Tokyo, Japan) RD series, DL series, SL series, RY series, H series, HM series, FR series, FZ series; HTP HiTech Photopolymere AG (Basel, Switzerland) DiaEtch 101, DiaEtch 102, DiaEtch 120, DiaEtch 122, DiaPlate; JSR Micro (Sunnyvale, CA, USA) ARX series, M series, V series, NDS series; KOLON Industries (Gyeonggi-do, South Korea) Trumask; MacDermid (Waterbury, CT, USA) PMGI, LOR; MicroChem Corp. (Westborough, MA, USA) SU-8 series, KMPR 1000, PMMA, PermiNex; Sumitomo Chemical (Tokyo, Japan) Sumiresist. In display 300 in Fig. 3, particle drift may occur in region 334 denoted by a dotted line box. This is where the lateral component of the electric field may be the highest. Particles that lie close to top electrode 310, near region 336, may not see a very large lateral component to the electric field. Region 336 is where diffusion may have a larger impact on particle migration than drift. Partial walls 332, as illustrated in Fig. 3, form partial micro-segregated regions. They may not completely bridge the rear support 312 to the front transparent sheet 302.

Micro-segregation using partial walls plays different roles depending on whether they are near or away from the rear electrode(s). The partial walls may be particle diffusion blocking or drift blocking. In some embodiments, partial walls may be used on the front sheet only. In other embodiments partial walls may be on the rear sheet located at the rear TFT layer. In still some other embodiments, each of the front or the rear sheet may have partial walls. In an exemplary embodiment, there is a complete seal of the wall to the TFT near location 430 that may comprise the highest lateral electric field.

The top of wall 332 may not be completely sealed to the outward sheet 302 if the viscosity of medium 322 is high enough to prevent diffusion of the electrophoretically mobile particles. In some embodiments, a viscosity enhancement material may prevent diffusion driven particle migration. In another embodiment, a viscosity enhancement material that undergoes shear thickening may prevent diffusion driven particle migration. In other embodiments, the tops of the walls may also contain gettering materials. Gettering materials may consume and trap the particles thus suppressing subsequent diffusion driven migration such as in region 336 in Fig. 3.

Display embodiment 300 may further comprise a color filter layer 338. Color filter layer 338 may further comprise sub-pixels wherein each sub-pixel may comprise a color. The color of each sub-pixel may be selected from at least one of red, green, blue, cyan, magenta, yellow, white, clear or black. In an exemplary embodiment, each color filter sub-pixel may be substantially aligned with a pixel electrode in rear electrode layer 311. In an exemplary embodiment, color filter layer 338 may be located between array of convex protrusions 304 and front sheet 302. In other embodiments, color filter layer 338 may be located on the outward side of sheet 302 facing viewer 308.

Fig. 4 schematically illustrates electric field lines in a cross-section of a portion of a TIR- based display 400 comprising partial walls. Display 400 comprises a transparent outward sheet 402 with convex protrusions 404, outward front surface 406 facing viewer 408, transparent front electrode 410 located on the inward surface of protrusions 404, rear support 412, first rear pixel electrode 414, second rear pixel electrode 416, gap 418 between said first and second rear pixel electrodes and cavity 420 formed by the outward sheet 402 and rear support 412. Display 400 further comprises a fluid or air medium 422.

In an exemplary embodiment, at least one dielectric layer 424 may be located on the surface of transparent front electrode 410. In some embodiments, at least one dielectric layer 426 may be located on the surface of rear electrodes 414, 416. Display embodiment 400 may further comprise a voltage bias source 428.

Suspended in medium 422 may be pluralities of electrophoretically mobile particles (not shown) comprising a positive charge polarity. In some embodiments, the particles may instead comprise a negative charge polarity. In other embodiments, pluralities of particles of both positive and negative charge may be suspended in medium 422. Particle aggregations are represented by shaded areas 430, 432 to denote where the particles may be attracted to and reside if attracted to a negative voltage bias (-V) at the front 410 or rear pixel electrodes 414, 416.

In order to mitigate the lateral particle migration, multiple partial walls may be added. In this embodiment, partial walls may be added to the rear of the cell nearest the location between adjacent pixel electrodes. Additionally, partial walls may be added at the front of the cell and approximately across from the rear wall. As shown in Fig. 4, the rear partial walls 434 may be located between adjacent pixels 414, 416 to limit drift-induced lateral migration of the particles. In an exemplary embodiment, the rear electrodes and rear support may be planarized with a planarization layer. A planarization layer may comprise a dielectric. The wall may be formed on top of the planarization layer. Particle drift may most likely occur in region 436 (denoted by a dotted line box) where the lateral component of the electric field may be the highest.

The embodiment illustrated in display 400 further comprises a second partial wall 438 that extends from the front sheet 402 towards the rear partial wall 434. Wall 438 may further limit particle diffusion in region 440 for particles 430 attracted to the front electrode 410. In some embodiments, there may not be a perfect alignment between the top wall 438 with and the rear wall 434. In certain other embodiment, an alignment may be optionally provided. The rear partial wall 434 may only need to extend out a small distance to disrupt particle diffusion. In one embodiment the gap between the rear and front walls may be small enough to prevent diffusion of particles to adjacent pixels. The combination of partial walls 434, 438 extending from the front and rear sheets, 402, 412, respectively, may decrease particle migration. This may prevent the need for walls that completely extend from the rear to the front sheet. This may also increase the manufacturability of the display and lower the manufacturing costs.

In other embodiments, at least one dielectric layer 442 may be located on the surface of partial walls 434, 438. The dielectric layers formed on partial walls 434, 438 from top sheet 402 and bottom sheet 412 may be comprise substantially the same material or may be different materials.

Display embodiment 400 may further comprise a color filter layer 444. Color filter layer 444 may further comprise sub-pixels wherein each sub-pixel may comprise a color. The color of each sub-pixel may be selected from at least one of red, green, blue, cyan, magenta, yellow, white, clear or black. In an exemplary embodiment, each color filter sub-pixel may be substantially aligned with pixel electrodes 414, 416. In an exemplary embodiment, color filter layer 444 may be located between array of convex protrusions 404 and front sheet 402. In other embodiments, color filter layer 444 may be located on the outward side of sheet 402 facing viewer 408.

Fig. 5 schematically illustrates an embodiment of the disclosure having multiple partial walls. Display 500 comprises a transparent outward sheet 502 with convex protrusions 504, outward front surface 506 facing viewer 508, transparent front electrode 510 located on the inward surface of protrusions 504, rear support 512, first rear pixel electrode 514, second rear pixel electrode 516, gap 518 between said first and second rear pixel electrodes and cavity 520 formed by the outward sheet 502 and rear support 512. Display 500 further includes a fluid or air medium 522. In an exemplary embodiment, at least one dielectric layer 524 may be located on the surface of transparent front electrode 510. In some embodiments, at least one dielectric layer 526 may be located on the surface of rear electrodes 514, 516. Display embodiment 500 may further comprise a voltage bias source 528.

Suspended in medium 522 may be pluralities of electrophoretically mobile particles comprising a positive charge polarity. In some embodiments, the particles may instead comprise a negative charge polarity. In other embodiments, pluralities of particles of both positive and negative charge may be suspended in medium 522. An aggregation of particles is represented by shaded areas 530, 532 to denote where the particles may be attracted to and reside if attracted to a negative voltage bias (-V) at the front 510 or rear pixel electrodes 514, 516.

In the embodiment of Fig. 5, partial walls are added to the rear of the cell closest to the location between adjacent pixel electrodes. As shown in Fig. 5, the rear partial walls 534 is located between adjacent pixels 514, 516 to limit drift-induced lateral migration of the particles. In an exemplary embodiment, the rear electrodes and rear support may be planarized with a planarization layer. A planarization layer may comprise a dielectric. The wall may be formed on top of the planarization layer. Particle drift may most likely occur in region 536 (denoted by a dotted line box) where the lateral component of the electric field may be the highest. Display 500 embodiment may further include a plurality of small walls, partitions or riffles 538. Riffles 538 extend inward into cavity 520 from front sheet 502 to limit particle diffusion in region 540. In some embodiments, riffles 538 may be in a regular array. In other embodiments, riffles 538 may be in an irregular spaced array. In other embodiments, riffles 538 may have varying widths. In other embodiments, riffles 538 may have varying lengths. In some embodiments, riffles 538 with a high spatial frequency may not be necessary to be aligned with rear walls 534, rear TFT, rear passive matrix or other patterned electrode layers 514, 516. In some embodiments, the display may comprise a combination of riffles, partial walls and full walls.

In other embodiments, at least one dielectric layer 542 may be located on the surface of partial walls 534, 538. The dielectric layers formed on partial walls 534, 538 from top sheet 502 and bottom sheet 512 may be comprise substantially the same material or may be different materials.

Display embodiment 500 may further comprise a color filter layer 544. Color filter layer 544 may further comprise sub-pixels wherein each sub-pixel may comprise a color. The color of each sub-pixel may be selected from at least one of red, green, blue, cyan, magenta, yellow, white, clear or black. In an exemplary embodiment, each color filter sub-pixel may be substantially aligned with pixel electrodes 514, 516. In an exemplary embodiment, color filter layer 544 may be located between array of convex protrusions 504 and front sheet 502. In other embodiments, color filter layer 544 may be located on the outward side of sheet 502 facing viewer 508.

In the embodiments disclosed and illustrated herein, the walls have been depicted as rectangles. This is for illustrative purposes only. The walls may be of any size or shape. Walls that are in contact with the transparent front sheet may frustrate TIR and lower the reflectance of the display in the bright state. This may create locations on the front sheet where the optical activity is "dead" resulting in overall lower brightness of the display. Walls may be designed to mitigate lateral migration of the particles and limit the impact on the brightness. In some embodiments, at least one wall may only come in contact with one convex protrusion. In an exemplary embodiment, the walls come into contact with the fewest number of convex protrusions. In an exemplary embodiment, the refractive index of the walls is about the same as the refractive index of the convex protrusions. In certain exemplary embodiments, the walls may be located between adjacent protrusions.

Fig. 6 schematically illustrates a cross-section of a portion of a reflective display 600 comprising partial partition walls. Display 600 comprises a transparent outward sheet 602 with outward front surface 604 facing viewer 606, transparent front electrode 608 located on the inward surface of sheet 604, rear support 610, first rear pixel electrode 612, second rear pixel electrode 614, gap 616 between the first 612 and second 614 rear pixel electrodes and cavity 618 formed by the outward sheet 602 and rear support 610. Display 600 further comprises a fluid or air medium 620 residing in cavity 618. Display 600 may further comprise at least one dielectric layer 622 located on the surface of front electrode layer 608. Display 600 may further comprise at least one dielectric layer 624 located on the surface of rear electrode layers 612, 614. Display embodiment 600 may further comprise a voltage bias source 626.

Suspended in medium 620 has a plurality of electrophoretically mobile particles 628 of a positive charge polarity of one color and a plurality of electrophoretically mobile particles of a negative charge polarity 632 and a second color. Particles 628 may be attracted to a negative voltage bias (-V) at front electrode 608 on the left side of dotted line 630 or rear pixel electrode 614 on right side of dotted line 630 when the bias was reversed. This is represented by negatively charged particles 628 located near rear pixel electrode 614. The field lines may be different than what is illustrated in Fig. 6 due to the presence of the charge particles.

The reflective display embodiment 600 in Fig. 6 may operate differently than the display embodiments in Figs. 1 -5. Display 600 is not a TIR-based display. Instead, this display 600 uses particles of different charge and color. By attracting a plurality of particles comprising a negative charge polarity to front electrode surface 608, viewer 606 may observe the color of the negatively charged particles 632. By attracting a plurality of particles comprising a positive charge polarity to front electrode surface 608, viewer 606 may observe the color of the positively charged particles 628. Two color images may be produced and observed by viewer 606. By attracting different combinations of the particles with positive and negative charge polarity to the surface by the rear electrodes an image may be produced. Gray states may also be displayed and observed by viewer 606. This may be done by driving a combination of positively charged particles 628 and negatively charged particles 632 to the front surface.

In order to mitigate lateral particle migration, multiple partial walls may be added. Partial walls 634 may be added to the rear of the cell nearest the location between adjacent pixel electrodes 612, 614.

Additionally, partial walls may be added at the front of the display in cavity 618. The embodiment illustrated in display 600 further includes a second partial wall 636 that extends inward from front sheet 602 towards rear partial wall 634. Wall 636 may limit particle diffusion in regions near front electrode 608. It may not be necessary that there is perfect alignment of the top wall 636 with the rear wall 634. Front partial walls 636 may only need to extend out a small distance to disrupt particle diffusion. In one embodiment the gap between the rear and front walls may be small enough to prevent diffusion of particles to adjacent pixels. The combination of partial walls 636, 634 extending from the front and rear sheets, 602, 610, respectively, may decrease particle migration. One or more dielectric layers 638 may be located on the surface of walls 634, 636.

Display embodiment 600 may further comprise a color filter layer 640. Color filter layer 640 may further comprise sub-pixels wherein each sub-pixel may comprise a color. The color of each sub-pixel may be selected from at least one of red, green, blue, cyan, magenta, yellow, white, clear or black. In an exemplary embodiment, each color filter sub-pixel may be substantially aligned with pixel electrodes 612, 614. In an exemplary embodiment, color filter layer 640 may be located between front electrode layer 608 and front sheet 602. In other embodiments, color filter layer 640 may be located on the outward side of sheet 602 facing viewer 606.

Fig. 7 schematically illustrates a cross-section of a portion of a reflective display 700 comprising partial partition walls according to one embodiment of the disclosure. Display 700 comprises a transparent outward sheet 702 with a front surface 704 facing viewer 706, transparent front electrode 708 located on the inward surface of sheet 702, rear support 710, first rear pixel electrode 712, second rear pixel electrode 714, gap 716 between first 712 and second 714 rear pixel electrodes and cavity 718 formed by the outward sheet 702 and rear support 710. Display 700 further contains a fluid or air medium 720. One or more dielectric layers 722 may be located on transparent front electrode 708. One or more dielectric layers 724 may be located on rear electrodes 712, 714. Display 700 may further comprise a voltage bias source 726.

Suspended in medium 720 are pluralities of electrophoretically mobile particles comprising of a positive charge polarity of one color (e.g., dark particles) and electrophoretically mobile particles of a negative charge polarity of a second color (e.g., light particles). Positively charged particles 728 of a first color are located near front electrode 708 where a negative bias has been applied as shown to the left of dotted line 730. On the right side of dotted line 730 positively charged particles 728 reside near rear pixel 714 where a negative bias has been applied.

Negatively charged particles 732 of a second color are attracted to rear pixel electrode 712 where a positive bias has been applied on left side of dotted line 730. To the right of dotted line 730, negatively charged particles 732 are attracted to front electrode 708 where a positive bias has been applied.

In order to mitigate lateral particle migration, multiple partial walls may be added in display embodiment 700. In this embodiment, partial walls 734 may be added to the rear of the display within cavity 718 nearest the location between adjacent pixel electrodes 712, 714.

Additionally, partial walls 734 may be added at the front of the display approximately across from a rear wall. It is not necessary that the front and rear walls be perfectly aligned.

Display 700 further includes a plurality of small walls or riffles 736 that extend inward into cavity 718 from front sheet 702. These are to limit particle diffusion at regions near front sheet 702. In some embodiments the riffles 736 may be in a regular array. In other embodiments, riffles 736 may be in an irregular spaced array. In some embodiments, riffles 736 may have varying widths. In other embodiments, riffles 736 may have varying lengths. In some embodiments, riffles 736 may not be aligned with rear walls 734, the rear TFT, passive matrix or other patterned electrode layers 712, 714. In some embodiments, one or more dielectric layers 738 may be located on the surface of walls 734, 736.

Display 700 may further comprise a color filter layer 740. Color filter layer 740 may further comprise sub-pixels wherein each sub-pixel may comprise a color. The color of each sub-pixel may be selected from at least one of red, green, blue, cyan, magenta, yellow, white, clear or black. In an exemplary embodiment, each color filter sub-pixel may be substantially aligned with pixel electrodes 712, 714. In an exemplary embodiment, color filter layer 740 may be located between front electrode layer 708 and front sheet 702. In other embodiments, color filter layer 740 may be located on the outward side of sheet 702 facing viewer 706.

In some embodiments, the front partial walls only need to extend out a small distance to disrupt particle diffusion. In some embodiments, the gap between the rear and front walls may be small enough to prevent diffusion of particles to adjacent pixels. The combination of partial walls extending from the front and rear sheets, 702 and 710, respectively, may decrease particle migration.

In another embodiment, dual particle displays 600 and 700 may optionally have walls located on the sheet comprising the pixelated electrodes. Thus, there may be no opposing walls.

In some TIR and dual particle-based display embodiments with both front and rear partial walls, the walls nearest adjacent pixelated electrodes may be longer in length than the opposing walls. In other embodiments, the front and rear walls may be approximately the same length. In other display embodiments with both front and rear walls, the walls nearest adjacent pixelated electrodes may be shorter in length than the opposing walls. In some embodiments, the partial walls may comprise a length in the range of about 1 -40 D m. In other embodiments, the partial walls may comprise a length in the range of about 5-30D m. In still other embodiments, the partial walls may comprise a length in the range of about 5-25 Dm. In an exemplary

embodiment, the partial walls may comprise a length in the range of about 10-25 Dm. In some TIR and dual particle-based display embodiments described herein the front and rear partial walls may be approximately the same width. In other embodiments, the rear walls may be narrower in width than the front walls. In other embodiments, the front walls may be narrower in width than the rear walls. In some embodiments, the partial walls may comprise a thickness in the range of about 0.1 -30 D m. In other embodiments, the partial walls may comprise a thickness in the range of about 1 -20 D m. In still other embodiments, the partial walls may comprise a thickness in the range of about 1-10 D m. In an exemplary embodiment, the partial walls may comprise a thickness in the range of about 3-1 OD m.

In some TIR and dual particle-based display embodiments described herein the partial walls may be square in shape. In other embodiments, the partial walls may be rectangular in shape. In other embodiments, the partial walls may be trapezoidal in shape. In other embodiments, the partial walls may be triangular in shape. In other embodiments, the partial walls may be oval in shape. In other embodiments, the partial walls may be tapered or other rounded shape. In other embodiments, the partial walls may be prism shaped. It should be noted that while different sizes and shapes are presented herein, the disclosed principles are not exclusive to these exemplary embodiments and other shapes and sizes may be applied without departing from the disclosed principles.

In certain embodiments, full walls substantially bridge the rear support to the front sheet to form individual wells or cells such that there are no gaps within the walls between the wells. Each well may segregate one pixel. In certain embodiments, a pixel may comprise a plurality (e.g., three) of sub-pixels.

Fig. 8 schematically illustrates a cross-section of a portion of one embodiment of a reflective display comprising full walls. Display embodiment 800 in Fig. 8 comprises a transparent front sheet 802 further comprising a front or outer surface 804 facing viewer 806. Display embodiment 800 may further comprise an array of convex protrusions 808 on the inward surface of sheet 802. Protrusions 808 may have a high refractive index. Protrusions 808 may have a refractive index in the range of about 1.5-1.9. An optional color filter layer 810 may be located between sheet 802 and protrusions 808. In other embodiments, color filter layer 810 may be located on the outward surface of sheet 802. In an exemplary embodiment, color filter layer 810 may comprise one or more of a white, black, clear, red, green, blue, cyan, magenta or yellow sub-filters.

Display embodiment 800 may further comprise a rear support sheet 812 where front sheet 802 and rear sheet form a cavity 814. Within cavity 814 may be air or other low refractive index medium 816. In an exemplary embodiment, medium 816 may have a refractive index in the range of about 1-1.5. On the surface of convex protrusions 808 is transparent front electrode layer 818 and optional front dielectric layer 820 located on the surface of layer 818. Display 800 comprises a rear electrode layer 822 on the inward side of rear sheet 812. In an exemplary embodiment, rear electrode layer 822 may comprise one or more pixel electrodes. Two pixel electrodes, 824, 826, are shown for illustrative purposes. Pixel electrode 824 is located to the left of dotted line 828 while a second pixel electrode 826 is located to the right of dotted line 828. Display 800 in Fig. 8 may comprise a plurality of electrophoretically mobile particles 830 suspended in medium 816. Particles 830 may comprise a positive or negative charge polarity. For illustrative purposes only, particles 830 in Fig. 8 comprise a positive charge polarity.

Display 800 may also comprise one or more full walls 832 located in cavity 814. Walls may completely bridge rear support 812 to front sheet 802. In some embodiments, full walls 832 may be formed on top of the front transparent electrode layer 818. In an exemplary embodiment, as illustrated in display embodiment 800 in Fig. 8, full walls 832 may be formed on top of front electrode layer 818 and dielectric layer 820. In some embodiments, full walls 832 formed on top of front electrode layer 818 may comprise one or more dielectric layers 834. In some embodiments, walls 832 may be coated with an electrode layer and one or more dielectric layers.

Display 800 may comprise one or more dielectric layers 836 on the surface of rear electrode layer 822. One or more dielectric layers may located on individual pixel electrodes 824, 826. Rear electrode 822 may comprise a planarization material 838 to planarize and smooth rear electrode layer 822. A smooth rear electrode layer 822 may make it easier to completely form full walls 832 and make it easier to manufacture the display.

Display 800 may comprise a bias (e.g., voltage) source 840. Voltage source 840 may be used to create a bias between front electrode 818 and rear electrode layer 822. A bias may be applied to move electrophoretically mobile particles 830 within cavity 814.

Display 800 may comprise an optional directional front light system 842. Front light system 842 may comprise multiple layers. Front light system 842 may comprise a light guide wherein the light guide may comprise a first outer layer 844, bottom layer 846 and central core layer 848. Layers 844, 846, 848 may be adhered by one or more optically clear adhesives. Front light system 842 may comprise one or more light extractor elements 850 (denoted as cross hatched lines). Front light system 842 may comprise a plurality of light extractor elements.

Front light system 842 may comprise a light source 852. Light source 852 may inject light into one or more of layers 844, 846, 848. Light extractor elements 850 may aid in re-directing light in a substantially perpendicular direction towards the front surface 804 of transparent front sheet 802. Front light source 852 (or any other light source) may be positioned to illuminate an edge of light system 842. For example, light rays may be transmitted to an edge of light system 842.

Display 800 may comprise a light diffuser layer 854. In some embodiments, light diffuser layer 854 may be located on the outer surface of directional front light system 842 facing viewer 806. In other embodiments, light diffuser layer may be located on the outer or inner surface of front sheet 802.

In an exemplary mode, display 800 may be operated in the following manner.

Electrophoretically mobile particles 830 may be moved away from surface of convex protrusions 808 and out of the evanescent wave region by application of a bias of opposite charge as particles 830 at rear electrode 822. This is illustrated in Fig. 8 to the left of dotted line 828.

Particles have been moved toward rear pixel electrode 824. Light may then be totally internally reflected at the interface of dielectric layer 820 and low refractive index medium 816. This is schematically represented by incident light ray 856. Incident light ray may then be reflected and exit display 800 towards viewer 806. This is schematically represented by reflected light ray 858. This creates a bright or light state of the display. A light or bright state of the display illustrated in Fig. 8 may also be formed from incident ambient light rays. For example, in some instances on bright sunny days or in a well-lit office, a light from a front light system may not be necessary. Ambient light may be sufficient to view the display. Display embodiment 800 may further comprise an ambient light sensor (not shown).

A dark state of the display may be formed by moving electrophoretically mobile particles

830 into the evanescent wave region near the surface of convex protrusions 808. By application of a bias by voltage source 840 of opposite charge as particles 830, particles may be moved near protrusions 808. The dark state is schematically illustrated to the right of dotted line 828.

Movement of particles 830 into the evanescent wave region may absorb light rays and frustrate total internal reflection of light to create a dark state. This is represented by incident light rays 860, 862. Light ray 860 illustrates emission by front light system 842. Light ray 862 illustrates incident ambient light.

Fig. 9 schematically illustrates a cross-section of a portion of one embodiment of a reflective display comprising full walls. Display embodiment 900 in Fig. 9 comprises a transparent front sheet 902 further comprising a front or outer surface 904 facing viewer 906. Display embodiment 900 may include an array of convex protrusions 908 on the inward surface of sheet 902. Protrusions 908 may have a high refractive index. Protrusions 908 may have a refractive index in the range of about 1.5-1.9. An optional color filter layer 910 may be located between sheet 902 and protrusions 908. In other embodiments, color filter layer 910 may be located on the outward surface of sheet 902. Color filter layer 910 may comprise one or more of a white, black, clear, red, green, blue, cyan, magenta or yellow sub-filters.

Display embodiment 900 may further comprise a rear support sheet 912 where front sheet 902 and rear sheet form a cavity 914. Within cavity 914 may be air or other low refractive index medium 916. In an exemplary embodiment, medium 916 may have a refractive index in the range of about 1-1.5. The surface of convex protrusions 908 may include a transparent front electrode layer 918. Display embodiment 900 may comprise an optional front dielectric layer 920 located on the surface of layer 918. Display 900 in Fig. 9 may comprise a rear electrode layer 922 on the inward side of rear sheet 912. In an exemplary embodiment, rear electrode layer 922 may comprise one or more pixel electrodes. Two pixel electrodes, 924, 926, are shown for illustrative purposes. Pixel electrode 924 is located to the left of dotted line 928 while a second pixel electrode 926 is located to the right of dotted line 928. Display 900 in Fig. 9 may comprise a plurality of electrophoretically mobile particles 930 suspended in medium 916.

Particles 930 may comprise a negative or positive charge polarity. For illustrative purposes only, particles 930 in Fig. 9 comprise a positive charge polarity. Display embodiment 900 may further comprise an ambient light sensor (not shown).

Displays 800 (Fig. 8) and 900 (Fig. 9) may comprise a plurality of light reflecting particles. The light reflective particles may comprise a white reflective particle such as titanium dioxide (TiCh). The light reflective particles may be around 200-300nm. This is a typical size of TiCh particles used in the paint industry to maximize light reflectance properties. Particles of larger or smaller sizes may also be used. The light reflective particles may further comprise a coating (not shown). The coating on the light reflecting materials may comprise an organic material or an inorganic material such as a metal oxide. The coating may comprise of an effective refractive index that is substantially similar to the refractive index of medium 816, 916. In some embodiments, the difference between the refractive indices of the coating on the light reflecting particles and medium 816, 916 may be about 40% or less. In other embodiments, the difference between the refractive indices of the coating on the light reflecting particles and medium 816, 916 may be about 0.5-40%.

Display 900 of Fig. 9 may comprise one or more full walls 932 located in cavity 914. In this embodiment, walls may be formed as continuous part of the protrusions 908. This is in contrast to display embodiment 800 in Fig. 8 where walls 832 and protrusions 808 are discontinuous and are formed separately. In an exemplary embodiment, walls 932 and protrusions 908 may be a continuous sheet or material. In some embodiments, front sheet 902, convex protrusions 908 and walls 932 may be a continuous sheet or material. The continuous sheet or material may comprise a polymer. Walls 932 may completely bridge front sheet 902 or protrusions 908 to rear support sheet 912. Continuous walls 932 and protrusions 908 may be formed together into a continuous structure using one or more methods of embossing, thermal embossing, injection molding, photolithography, micro-fabrication and micro-replication from a metal shim master. Walls 932 may be included in a master with protrusions 908 so they may be molded and replicated the same time.

In some embodiments, a transparent front electrode layer 918 may be formed on both the surface of convex protrusions 908 and walls 932. In other embodiments, front electrode layer 918 may only be deposited on protrusions 908. In still other embodiments, at least one optional dielectric layer 920 may be located on the surface of front electrode layer 918 where front electrode 918 is located on both the protrusions 908 and walls 932. In an exemplary

embodiment, at least one optional dielectric layer 920 may be located on the surface of walls 932 and on the surface of front electrode layer 918 wherein front electrode layer 918 is located only the surface of the protrusions 908.

Display 900 may comprise one or more dielectric layers 934 on the surface of rear electrode layer 922. The one or more dielectric layers may be positioned on individual pixel electrodes 924, 926. Rear electrode 922 may comprise a planarization material 936 to planarize and smooth rear electrode layer 922. Smooth rear electrode layer 922 may make it easier for walls 932 to completely bridge to rear layer 912 and make it easier to manufacture the display.

Display 900 may also comprise a voltage source 938. Voltage source 938 may be used to create a bias between front electrode 918 and rear electrode layer 922. A bias may be applied to move electrophoretically mobile particles 930 within cavity 914 into and out of the evanescent wave region.

In certain embodiments, display 900 may comprise an optional directional front light system 940. Front light system 940 may comprise multiple layers. Front light system 940 may comprise a light guide wherein the light guide may comprise a first outer layer 942, bottom layer 944 and central core layer 946. Layers 942, 944, 946 may be adhered together by one or more optically clear adhesives. Front light system 940 may comprise one or more light extractor elements 948 (denoted as cross hatched lines). Front light system 940 may comprise a light source 950. Light source 950 may inject light into one or more of layers 942, 944, 946. Light extractor elements 948 may aid in re-directing light in a substantially perpendicular direction towards front surface 904 of transparent front sheet 902.

Display 900 is shown with light diffuser layer 952. In some embodiments, light diffuser layer 952 may be located on the outer surface of directional front light system 940 facing viewer 906. In other embodiments, light diffuser layer 952 may be located on the outer or inner surface of front sheet 902.

Display embodiment 900 includes continuous walls 932 and protrusions 908 which may be operated in a similar manner as previously described in relation to Fig. 8.

Fig. 10A schematically illustrates a cross-section of a portion of a TIR-based display 1000 with rounded walls. Display 1000 comprises a transparent outward sheet 1002 with plurality of convex protrusions 1004, front surface 1006 facing viewer 1008, transparent front electrode 1010 located on the inward surface of protrusions 1004, rear support 1012, rear electrode 1014 and cavity 1016 formed by the outward sheet 1002 and rear support 1012. Display 1000 further includes a fluid or air medium 1018. Display 1000 may further comprise electrophoretically mobile particles suspended in medium 1018. A front light system, voltage bias source and one or more dielectric layers on front electrode 1010, rear electrode 1014 or walls 1020 and a voltage bias source have been omitted for simplicity. Display 1000 comprises walls 1020 with a rounded cross-section. In an exemplary embodiment, the rounded cross-section may be in the shape of a pendant drop. The rounded cross-section of the walls allows under certain lighting conditions for incident light to be totally internally reflected back towards viewer 1008. This may enhance the brightness of the display as opposed to using rectangular walls. To prevent shorting between the front 1010 and rear 1014 electrodes, a dielectric layer (not shown) may be added to the surface of rear electrode 1014.

Fig. 10B schematically illustrates a cross-section of a portion of a TIR-based display 1030 with rounded walls and base. Display embodiment 1030 in Fig. 10B is similar to display 1000 in Fig. 10A except that the display further comprises bases 1032 for walls 1020 with a rounded cross-section. In an exemplary embodiment, base 1032 has a refractive index substantially the same as the rounded walls 1020. To prevent shorting, display 1030 in Fig. 10B may further comprise a dielectric layer (not shown) located on the surface of one or more of the rear electrode layer 1014, walls 1020 and base 1032. The base may be located on top of the dielectric layer such that the dielectric layer may be interposed between the rear electrode 1014 and base 1032. In an exemplary embodiment, base material 1032 that is in contact with the wall 1020 has a lower refractive index than the rounded wall to limit frustration of TIR. Base material 1032 may have a refractive index that is about 0.2 or less than the refractive index of medium 1018.

Fig. IOC schematically illustrates a cross-section of a portion of a TIR-based display 1060 with rounded walls. Display 1060 in Fig. I OC is similar to display 1000 in Fig. 10A except that display 1060 further comprises inverted walls 1062 with a rounded cross-section. In certain embodiments, the top of inverted walls 1062 may contact hemispherical portions while in other embodiments they may not. Walls 1062 are upside down or inverted when compared to walls 1020 in Fig. 10A. The tip of wall 1062 may come in contact with the surface of the convex protrusions 1004. This may limit the amount of surface area that is in contact with the convex protrusions which further limits the amount of frustration of TIR leading to a brighter display. The embodiment in Fig. IOC may further include a dielectric layer (not shown) on the surface of walls 1062. The dielectric layer may prevent shorting of the display by walls 1062. Walls 1062 may be of other shapes such as prisms to limit the contact with the layer of protrusions 1004. Any of the walls illustrated in Figs. l OA-C may be formed from materials previously listed herein.

In some embodiments, walls 1020, 1062 may have a refractive index similar to medium

1018 in the range of about 1-1.5. In other embodiments, walls 1020, 1062 may have a refractive index similar to front sheet 1002 and/or in the range of about 1.5-1.9.

Fig. 11 schematically illustrates a cross-section of an embodiment to assemble a TIR-based display with a full wall. In this embodiment of a method, display 1 100 comprises of a front sheet 1102 that further comprises a layer of a plurality of convex protrusions 1104 and front surface 1106 facing viewer 1108. Display embodiment 1000 further comprises a rear sheet 1 110 and rear electrode layer 11 12. A gap 11 14 may be formed between the front and rear sheets where a low refractive index medium 1 116 may be located. A front electrode layer, voltage source, front light, electrophoretically mobile particles, dielectric layers and other components of the display are not shown for clarity of illustration. Within gap 1 114 may be walls 1 118. In an exemplary embodiment, front sheet 1 102 may comprise a slit or trench 1120 where the top of wall 11 18 may nestle or fit into to form a substantially sealed full wall. The full wall may completely bridge the rear sheet to the front sheet. The creation of an array of full walls in a reflective image display, such as a TIR-based display, may be formed this way. This may further aid in aligning front sheet 1 102 to rear sheet 1 1 10 where rear sheet may comprise an array of pixel electrodes. This may also further aid in aligning color filter sub-pixels on a front sheet to the pixel electrodes on a rear sheet. In other embodiments, walls 11 18 may be formed with front sheet 1102 and may be continuous with front sheet 1 102. A slit or trench may be formed at the rear of the display near rear electrode layer 11 12 where walls may fit or nestle into.

In other embodiments, the front sheet may not comprise a layer of convex protrusions such as that found in display embodiments 600, 700 in Figs. 6-7. Front sheets 602 and 702 may comprise a slit or trench such that walls may fit into to form a complete wall that bridges the rear sheet to the front sheet. In certain embodiments, the walls may be arranged with respect to the convex protrusions in multiple ways. Fig. 12A schematically illustrates a portion of a front sheet comprising walls on the surface of convex protrusions. Wall design embodiment 1200 in Fig. 12A is a portion of a front sheet 1202 comprising of an array of convex protrusions 1204. This view is a perpendicular view of a sheet 1202 of protrusions 1204. Previously described herein, such as in Figs. 1-5, 8-1 1, the view was a cross section of a sheet of protrusions. Protrusions 1204 are hemispherically shaped for illustrative purposes, though they may be other shapes. Protrusions of other shapes and form may be contemplated without departing from the principles disclosed herein. Protrusions 1204 are arranged in rows 1206 and are in a close packed arrangement with space 1208 in between. Though other arrangements are possible, the close packed arrangement is preferred to maximize the density of protrusions on sheet 1202. Walls 1210 are denoted by thick black lines. In an exemplary embodiment, walls 1210 may be formed on rows of protrusions 1204 (as illustrated in Fig. 12A). Walls 120 may be used to form compartments or wells to confine electrophoretically mobile particles (not shown for clarity).

An example of a compartment 1212 is highlighted by a dotted line. Compartment 1212 in

Fig. 12A is in the shape of a parallelogram but may comprise other shapes. Compartments 1212 may include one or more convex protrusions. This is illustrated in Fig. 12A where compartment 1212 includes two central protrusions and ten partial protrusions 1204 over which wall 1210 is formed and surrounds. In some embodiments, walls 1210 that are formed on protrusions 1204 may be partial walls. In an exemplary embodiment, walls 1210 that are formed on protrusions 1204 may be full walls. In some embodiments, walls 1210 that are formed on protrusions 1204 may comprise a combination of both partial and full walls.

Fig. 12B schematically illustrates a portion of a front sheet comprising walls between rows of convex protrusions. Wall design embodiment 1240 in Fig. 12B comprises walls 1242 that lie between rows of protrusions 1206. In this embodiment, the walls are substantially located in the space between protrusions 1204. Walls 1242 may be formed on the edges of protrusions 1242 in the space between rows 1206. Depending on the distance between the protrusions, walls 1242 may touch or may not touch adjacent protrusions 1204. Walls 1242 located between rows may form compartments 1244 (denoted by dotted line box). Compartments 1244 comprising walls between rows of protrusions 1206 may enclose one or more protrusions 1204. Walls 1242 located between rows 1206 of protrusions may be partial walls, full walls or a combination of full and partial walls.

Fig. 12C schematically illustrates a portion of a front sheet comprising walls on the surface of the convex protrusions and between rows of convex protrusions. Wall design embodiment 1260 in Fig. 12C comprises walls 1262 that lie on protrusions 1204 and walls 1264 that lie between rows of protrusions 1206. Walls 1264 that lie between rows 1206 may also touch protrusions 1204 on both sides of the wall. Walls 1264 located between rows may form compartments 1266 (denoted by dotted line box). Compartments 1266 comprising walls between rows of protrusions 1206 may enclose one or more protrusions 1204. In the example in Fig. 12C, the compartment is rectangular shaped. Walls 1262 formed on protrusions 1204 and walls 1264 located between rows 1206 of protrusions may be partial walls, full walls or a combination of full and partial walls. Compartments 1266 formed by walls 1262, 1264 may form one or more of square shaped compartments (as illustrated in Fig. 12C), rectangular shaped compartments, hexagonal shaped compartments, rhombus shaped compartments, parallelogram shaped compartments or any other shape of compartment 1266. It should be noted that the shape and/or form of the compartments are provided for illustration purposes and are not limiting the disclosure. Other shapes and forms may be used without departing from the disclosed principles.

Any of the wall design embodiments illustrated in Figs. 12A-C may be formed from materials previously listed herein. Any of the wall design embodiments illustrated in Figs. 12A- C may be formed by processes previously listed herein, such as embossing or micro-replication.

Fig. 13 A schematically illustrates a portion of a front sheet comprising walls and color filter sub-pixels on the surface of convex protrusions that may be integrated into a reflective image display. Design embodiment 1300 in Fig. 13A illustrates how walls may be aligned with respect to one or more of the convex protrusions on the inward surface of sheet 1302, color filter sub-pixels and rear thin film transistor array in a TIR-based image display. This view is a perpendicular view of a sheet 1302 of protrusions 1304 as similarly illustrated in Figs. 12A-C. Embodiment 1300 comprises a transparent sheet 1302 which further includes an array of convex protrusions 1304. Protrusions 1304 are arranged in rows 1306 in a close packed arrangement. There is space 1308 between protrusions 1304. In other embodiments, protrusions 1304 may touch. Embodiment 1300 further comprises walls 1310, 1312. Walls 1310 are aligned in vertical direction while walls 1312 are arranged in a horizontal direction. In this embodiment, walls are arranged in rectangular shaped compartments. In an exemplary embodiment, the compartments further comprise a substantially aligned color filter sub-pixel. In some embodiments, a color filter sub-pixel layer may be formed on the outward side of sheet 1302 or opposite side of sheet 1302 from where the rows of convex protrusions 1306 are formed. In an exemplary embodiment, a color filter sub-pixel layer may be located between sheet 1302 and rows of convex protrusions 1306 as illustrated in Figs. 8-9. The compartments with color filter sub-pixels are denoted by dotted line boxes 1314, 1316, 1318. Dotted line box 1314 denoting a compartment comprises horizontal lines. This represents a single red color filter sub-pixel. Dotted line box 1316 with vertical lines represents a single green color filter sub-pixel. Dotted line box 1318 denoting a shaded region represents a single blue color filter sub-pixel. In other embodiments, walls may form compartments each substantially aligned with a single color filter sub-pixel comprising one of colors red, green, blue, cyan, magenta, yellow, white, clear or black. In an exemplary embodiment, a single rear thin film transistor may be substantially aligned with a single color filter sub-pixel that may further be aligned with a single compartment formed by walls.

Fig. 13B schematically illustrates a portion of a front sheet comprising walls and color filter sub-pixels on the surface of convex protrusions that may be integrated into a reflective image display. Design embodiment 1340 in Fig. 13B illustrates how walls may aligned with respect to one or more of the convex protrusions on inward surface of sheet 1302, more than one color filter sub-pixels and rear thin film transistors. This view is a perpendicular view of a sheet 1302 comprising protrusions 1304 as similarly illustrated in Figs. 13B. Protrusions 1304 are arranged in rows 1306 in a close packed arrangement. There may be space 1308 between protrusions 1304. In other embodiments, protrusions 1304 may touch. Embodiment 1340 further comprises walls 1310 are aligned in vertical direction while walls 1312 are arranged in a horizontal direction. In this embodiment, walls are arranged in rectangular shaped

compartments. Compartment 1342 (denoted by a dotted line) highlights a compartment. In an exemplary embodiment, the compartments formed by walls further comprise more than one substantially aligned color filter sub-pixel. In some embodiments, a color filter sub-pixel layer may be formed on the outward side of sheet 1302 or opposite side of sheet 1302 from where the rows of convex protrusions 1306 are formed. In an exemplary embodiment, a color filter sub- pixel layer may be located between sheet 1302 and rows of convex protrusions 1306 as illustrated in Figs. 8-9.

In the exemplary embodiment of Fig. 13, compartment 1342 comprises three color filter sub-pixels. Each sub-pixel is hatched differently for illustrative purposes. A first color filter sub-pixel within compartment 1342 is represented by horizontal lines (represents a red color filter sub-pixel), a second color filter sub-pixel represented by vertical lines (represents a green color filter sub-pixel) and a third color filter sub-pixel is represented by a shaded region

(represents a blue color filter sub-pixel) as described in Fig. 13 A. Here, three color filter sub- pixels are aligned with a compartment. In exemplary embodiments, single compartment formed by walls may be substantially aligned with two or more color filter sub-pixels. The two or more color filter sub-pixels may include one of colors red, green, blue, cyan, magenta, yellow, white, clear or black. A single rear thin film transistor may be substantially aligned with a single color filter sub-pixel that may further be aligned with one or more color filter sub-pixels and further aligned with a single compartment formed by walls. In another embodiment, a single compartment formed by walls may be substantially aligned with a group of color filter sub-pixels wherein two or more of the color filter sub-pixels may be of the same color in a reflective image display. For example, a single compartment formed by walls may be substantially aligned with a group of four sub-pixels comprising one red, two green and one blue color filter sub-pixels. Each color filter sub-pixel may be substantially aligned with a single thin film transistor.

Fig. 13C schematically illustrates a portion of a front sheet comprising walls and color filter sub-pixels on the surface of convex protrusions that may be integrated into a reflective image display. Design embodiment 1360 in Fig. 13C illustrates how, in some embodiments, walls may not be substantially aligned with respect to one or more of the convex protrusions, more than one color filter sub-pixels and rear thin film transistors. A group of color filter sub- pixels 1362 are highlighted by a dotted line box showing how walls may be formed in some embodiments to fully enclose sub-pixels and partially enclose sub-pixels in an image display. Embodiment 1360 illustrates how walls 1364 may lie on top of a color filter sub-pixel. Walls may further lie on rows 1306 of convex protrusions 1304 or between rows 1306 of convex protrusions. In this illustration, walls lie on a red sub-pixel (horizontal lines) as highlighted by dotted line 1366. Furthermore, a rear TFT may be aligned with the red sub-pixel but may not be aligned with a wall or compartment. A TFT may form a bias with the front electrode in order to move particles to the surface of protrusions 1304 near a color filter sub-pixel on both sides of a wall and in separate compartments.

Fig. 13D schematically illustrates a portion of a front sheet comprising full walls with interruptions and color filter sub-pixels on the surface of convex protrusions that may be integrated into a reflective image display. Design embodiment 1370 in Fig. 13D illustrates how, in some embodiments, full walls that bridge the array of convex protrusions to a rear sheet may comprise gaps or interruptions in one or more directions. Embodiment 1370 in Fig. 13D comprises horizontal direction full walls 1372 and vertical direction full walls 1374. In other embodiments, the walls may be aligned in other directions. Horizontal full walls 1372 and vertical full walls 1374 may cross as highlighted by dotted line box 1376. The full walls may comprise gaps 1378 as highlighted by a dotted line box. In some embodiments, gaps in full walls may only be present in one direction 1380. In other embodiments, gaps in full walls may be present in other directions 1382. In still other embodiments, gaps in full walls may be present in two or more directions as illustrated in embodiment 1370 in Fig. 13D. The full walls with gaps may be placed between adjacent color filter sub-pixels to form a border. This is illustrated by vertical walls 1374 located between blue and red color filter sub-pixels. The full walls with gaps may be located between any adjacent color filter sub-pixels in a controlled or random fashion. In other embodiments, full walls with gaps may not be located between adjacent color filter sub-pixels. In some embodiments, full walls with gaps may be located on rows of convex protrusions or between rows of convex protrusions or a combination thereof. Full walls help to maintain a substantially constant gap distance between the front electrode layer on the surface of the convex protrusions in the front sheet and the rear electrode layer on the rear support sheet. This helps to allow for predictable switching behavior of the electrophoretically mobile particles into and out of the evanescent wave region. The walls may also restrict and minimize drift of the electrophoretically mobile particles to allow for substantially uniform distribution of particles throughout the display. The gaps in the walls allows for more efficient filling of the display with a liquid or air medium comprising electrophoretically mobile particles.

Fig. 14 schematically illustrates a portion of a color filter sub-pixel array comprising walls that are positioned between specific sub-pixel colors that may be integrated into a reflective image display. Design embodiment 1400 in Fig. 14 illustrates how, in some embodiments, walls may be positioned between specific color filter sub-pixels (it should be noted that the array of convex protrusions that are typically placed between the color filter sub-pixel array and the walls have been omitted for clarity).

Display 1400 comprises an array of color filter sub-pixels 1402. The color filter sub-pixels may be arranged in specific orders such as clear (C), red (R), green (G) blue (B) as illustrated in Fig. 14 and highlighted by dotted line box 1408. Any specific arrangement of colors may be used depending on the application and desired optical effects required. In some embodiments, the color filter sub-pixels may be arranged in columns 1404 and rows 1406 as illustrated in Fig. 14. In an exemplary embodiment, a reflective image display may comprise perimeter full wall 1410. Perimeter full wall 1410 shown in Fig. 14 substantially completely surrounds the active area of the display. A perimeter wall may be used to act as a barrier to prevent the air or liquid medium comprising electrophoretically mobile particles from contacting edge seal material during filling. Perimeter wall 1410 may also act as a barrier to prevent contamination from the edge seal into the medium comprising electrophoretically mobile particles. A perimeter full wall may be used in any of the reflective display embodiments described herein comprising full walls, partial walls or a combination of full and partial walls. In some embodiments, the walls may be positioned such that they lie intentionally between specific colored sub-pixels in a regular manner throughout the display. Embodiment 1400 in Fig. 14 illustrates this. Vertically positioned walls 1412 may lie between blue (B) and clear (C) sub-pixels only. Horizontally aligned walls 1414 in Fig. 14 may be positioned between clear (C) and green (G) sub-pixels and between red (R) and blue (B) sub-pixels only. In other embodiments, other specific arrangements of walls positioned between two or more color filter sub-pixels are possible. In other embodiments, walls may be positioned such that they lie intentionally between specific colored sub-pixels in an irregular manner throughout the display. Walls positioned between specific color filter sub-pixels in a regular or irregular manner may be used in any of the reflective display embodiments described herein comprising full walls, partial walls or a combination of full and partial walls.

Any of the front sheet, convex protrusions, color filter sub-pixels and wall designs described herein and illustrated in Figs. 13-14 may be utilized and integrated into the TIR-based image displays described herein and illustrated in Figs. 3-5, 8-9 and non-TIR-based displays illustrated in Figs. 6-7.

In any of the full or partial wall TIR and dual particle-based display embodiments described herein, the walls may comprise a color. The colors may be formed by dyes or pigments dispersed in the material comprising the walls. In one embodiment, the walls may comprise a black color. In other embodiments, the walls may comprise a white color. In an exemplary embodiment, the walls may be transparent. Walls may be optically opaque, colored or isolating improving the color saturation or purity between neighboring pixels. Walls may also be electrically isolating reducing the electrical field crosstalk between pixels and thereby improving the grayscale and/or color saturation of the display. In some embodiments, walls may comprise a refractive index in the range of about 1-2.2. In an exemplary embodiment, walls may comprise a refractive index in the range of about 1.5-2.2.

Fig. 15 schematically illustrates an embodiment of a TFT array to drive a display. The TFT array is similar to the arrays used to drive conventional LCD displays. The TFT embodiment may be used to drive any of the display embodiments described herein comprising full walls, partial walls or both full and partial walls. The arrangement of particles in a cavity (e.g., particles 430, 432 in Fig. 4; particles 628, 632 in Fig. 6; particles 830 in Fig. 8; particles 930 in Fig. 9) may be controlled by TFT array embodiment 1500 in Fig. 15. In an exemplary embodiment, TFT array 1500 may be used as the rear electrode layer (e.g., electrodes 414, 416 in Fig. 4; electrodes 612, 614 in Fig. 6; electrode layer 822 in Fig. 8; electrode layer 922in Fig. 9). TFT array 1500 may comprise an array of pixels 1502 to drive the display embodiments described herein. A single pixel 1502 is highlighted by a dotted line box in Fig. 15. Pixels 1502 may be arranged in rows 1504 and columns 1506 as illustrated in Fig. 15 but other arrangements may be possible. In an exemplary embodiment, each pixel 1502 may comprise a single TFT 1508. In array embodiment 1500, each TFT 1508 may be located in the upper left of each pixel 1502. In other embodiments, the TFT 1508 may be placed in other locations within each pixel 1502. Each pixel 1502 may further comprise a conductive layer 1510 to address each pixel of the display. Layer 1510 may comprise ITO, aluminum, copper, gold, Baytron™, or conductive nanoparticles, silver wires, metal nanowires, graphene, nanotubes, or other conductive carbon allotropes or a combination of these materials dispersed in a polymer. TFT array embodiment 1500 may further comprise column 1512 and row 1514 wires. Column wires 1512 and row wires 1514 may comprise a metal such as aluminum, copper, gold or other electrically conductive metal. Column 1512 and row 1514 wires may comprise ITO. The column 1512 and row 1514 wires may be attached to the TFTs 1508. Pixels 1502 may be addressed in rows and columns. TFTs 1508 may be formed using amorphous silicon or poly crystalline silicon. The silicon layer for TFTs 1508 may be deposited using plasma-enhanced chemical vapor deposition (PECVD). In an exemplary embodiment, each pixel may be substantially aligned with a single color filter (e.g., color filter layer 444 in Fig. 4; color filter layer 640 in Fig. 6; color filter layer 810 in Fig. 8; color filter layer 910 in Fig. 9). Column 1512 and row 1514 wires may be further connected to integrated circuits and drive electronics to drive the display.

The components of TFT array 1500 may be mounted on sheet 1516. In an exemplary embodiment, sheet 1516 may be glass. In some embodiments, sheet 1516 may comprise glass of thickness in the range of about 20-2000 Dm. In an exemplary embodiment, sheet 1516 may comprise glass of thickness in the range of about 20-250 Dm. In some embodiments, sheet 1516 may comprise a flexible glass such as SCHOTT AF 32^® eco or D 263^® T eco ultra-thin glass. In other embodiments, sheet 1516 may comprise a transparent polymer such as polycarbonate or an acrylic such as poly(methyl methacrylate).

TFT array 1500 is generally opaque except for areas between pixels. In an exemplary embodiment, regions 1518 may be transparent. Transparent regions 1518 play an important role in the invention described herein. Regions 1518 between the pixels allow for UV light to pass through to cure a photoresist material. In an exemplary embodiment, TFT array 1500 may act as a photolithographic mask to assemble self-aligned pixel walls.

Fig. 16A schematically illustrates a cross-section of a TFT array on a transparent sheet. TFT cross-section 1600 in Fig. 16A illustrates transparent regions 1518 between conductive layers 1510 or pads and column wires 1512 on transparent sheet 1516. Regions 1518 may allow for UV curing light to pass through. There may also be transparent regions between conductive layers 1510 and row wires 1514.

The first step to creating self-aligned pixel walls is to coat the top surface of TFT array 1500 is with a layer of photoresist material. Fig. 16B schematically illustrates a cross-section of a TFT array on a transparent sheet comprising a photoresist layer. Cross-section 1610 in Fig. 16B comprises photoresist material 1612. In an exemplary embodiment, photoresist material 1612 is a negative photoresist material. Negative photoresist layer 1612 may fill in transparent spaces 1518 between conductive layer 1510 and column wires 1512. In an exemplary embodiment, photoresist 1612 may comprise a photo-curable polymer. In some embodiments, photoresist may comprise one or more of Norland Optical Adhesives (NO A line of products, Norland Products, Inc., Cranbury, NJ, USA) such as NOA 86 or NOA89.

Fig. 16C schematically illustrates a cross-section of a TFT array on a transparent sheet comprising a photoresist layer exposed to UV light. Photoresist layer 1612 may be exposed to a high intensity light source such as ultra-violet (UV) light or near UV light 1614 through the backside of transparent layer 1516. The UV light may be partially collimated and perpendicular to photoresist layer 1612. UV light 1614 may pass through the transparent regions 1518 between conductive layers 1510 and column wires 1512 and row wires 1514. UV light 1614 that passes through transparent regions 1518 in between the pixels may cure the exposed photoresist 1612. All other light rays 1614 not passing through transparent regions 1518 may be reflected. Resist 1612 may then be developed and rinsed with a chemical solution (i.e. developer) such that the regions not exposed to the high intensity light 1614 are washed, rinsed or stripped away and removed to leave a patterned array of pixel walls.

Fig. 16D schematically illustrates a cross-section of a TFT array on a transparent sheet comprising self-aligned pixel walls. TFT array with self-aligned pixel walls 1620 comprises pixel walls 1622 between conductive layers 1510. Photoresist 1612 may be cured with UV light 1614 and developed to leave aligned pixel walls 1622. The technique to assemble self-aligned pixel walls illustrated in Figs. 16A-D may be carried out on rigid and flexible TFT array backplanes. In one embodiment of a display assembly method, the backplane with aligned pixel walls may then be filled with electrophoretic particles (e.g. , 328 in Fig. 3; 530 in Fig. 5; 628 in Fig. 6; 830 in Fig. 8; 930 in Fig. 9), low refractive index medium (e.g., 322 in Fig. 3; 522 in Fig. 5; 620 in Fig. 6; 816 in Fig. 8; 916 in Fig. 9) and any other additives. Top sheet (e.g. , 302 in Fig. 3; 502 in Fig. 5; 602 in Fig. 6; 802 in Fig. 8; 902 in Fig. 9) may then be placed on top to seal the display. An optically clear adhesive may be used to adhere a top sheet to pixel walls 1622. Compartments may be formed by the self-aligned pixel walls when a top sheet is added.

The transparent regions between pixels on a TFT backplane are often at a lower height than the opaque regions. This may impact the uniformity of the photoresist coating. One method is to apply a planarization layer on the TFT backplane before coating with photoresist. This process flow is illustrated in Figs. 17A-D. Fig. 17A schematically illustrates a cross-section of a TFT array on a transparent sheet comprising a planarization layer. Cross-section 1700 comprises planarization layer 1702. Layer 1702 may fill gaps 1518 between conductive layers 1510 and column electrodes 1514 and row electrodes 1514 to create a substantially smooth and uniform surface to apply a photoresist layer. Planarization layer 1702 may comprise a photo-chemically or thermally curable polymer. In an exemplary embodiment, planarization layer 1702 may also act as a dielectric layer.

Fig. 17B schematically illustrates a cross-section of a TFT array on a transparent sheet comprising a planarization layer and a photoresist layer. Cross-section 1710 comprises photoresist material 1712. In an exemplary embodiment, photoresist material 1712 is a negative photoresist material. Negative photoresist layer 1712 may be coated on top of planarization layer 1702. In an exemplary embodiment, photoresist 1712 may comprise a photo-curable polymer. In some embodiments, photoresist 1712 may comprise one or more of Norland Optical Adhesives (NOA line of products, Norland Products, Inc., Cranbury, NJ, USA) such as NOA 86 or NOA89.

Fig. 17C schematically illustrates a cross-section of a TFT array on a transparent sheet comprising a planarization layer and a photoresist layer exposed to UV light. Photoresist layer 1712 may be exposed to a high intensity light source such as ultra-violet (UV) light or near UV light 1714 through the backside of transparent layer 1516. The UV light may be partially collimated and perpendicular to photoresist layer 1712. UV light 1714 may pass through the transparent regions 1518 between conductive layers 1510 and column wires 1512 and row wires 1514. UV light 1714 that passes through transparent regions 1518 in between the pixels may cure the exposed photoresist 1712. All other light rays 1714 not passing through transparent regions 1518 may be reflected. Resist 1712 may then be developed and rinsed with a chemical solution (i.e. developer) such that the regions not exposed to the high intensity light 1714 are washed, rinsed or stripped away and removed to leave a patterned array of pixel walls.

Fig. 17D schematically illustrates a cross-section of a TFT array on a transparent sheet comprising a planarization layer and self-aligned pixel walls. TFT array with self-aligned pixel walls 1720 comprises pixel walls 1722 on a planarization layer 1702. Photoresist 1712 may be cured with UV light 1714 and developed to leave aligned pixel walls 1722. The technique to assemble self-aligned pixel walls illustrated in Figs. 17A-D may be carried out on rigid and flexible TFT array backplanes with a planarization layer. In one embodiment of a display assembly method, the backplane with aligned pixel walls on a planarization layer may then be filled with electrophoretic particles (e.g. , 328 in Fig. 3; 530 in Fig. 5; 628 in Fig. 6; 830 in Fig. 8; 930 in Fig. 9), low refractive index medium (e.g. , 322 in Fig. 3; 522 in Fig. 5; 620 in Fig. 6; 816 in Fig. 8; 916 in Fig. 9) and any other additives. Top sheet (e.g., 302 in Fig. 3; 502 in Fig. 5; 602 in Fig. 6; 802 in Fig. 8; 902 in Fig. 9) may then be placed on top to seal the display. An optically clear adhesive may be used to adhere a top sheet to pixel walls 1722. Compartments may be formed by the self-aligned pixel walls when a top sheet is added.

Fig. 17E schematically illustrates a cross-section of a portion of a TIR-based reflective image display comprising self-aligned pixel walls. Display embodiment 1740 in Fig. 17E comprises front sheet 1742 facing viewer 1744 further comprising a plurality 1746 of individual convex protrusions 1748. Display 1740 includes rear support 1516 which further comprises conductive layer 1510, column wires 1512, planarization layer 1702, self-aligned pixel walls

1722. Display 1740 comprises medium 1750, electrophoretically mobile particles 1752, voltage source 1756 and color filter sub-pixel layer 1758. Pixel walls 1722 form compartments comprising medium 1750 and particles 1752 aligned with a single pixel 310. While not shown, display 1740 may further comprise other components as described herein such as a directional front light system, electrode layers, one or more dielectric layers, but have been omitted for clarity of display.

Self-aligned pixel walls may be formed in already assembled displays, such as displays 300, 400, 500, 600, 800, 900. A display such as display 100 may comprise a TFT backplane array that acts as a mask. A photo-poly merizable material may be added to medium 112 further comprising electrophoretically mobile particles 114. UV light may then be exposed through the backside of the TFT, curing the photo-polymerizable material inside the medium. This may create a self-aligned wall structure inside the display after the display has been assembled. In an exemplary embodiment, self-aligned pixel walls in formed using a TFT backplane photomask may be formed by processes and methods described in United States patent US5668651A (Sharp Kabushiki Kaisha, Osaka, Japan) and PCT applications WO 2016/206771 Al, WO 2016/206772 Al and WO 2016/206774 Al (Merck Patent GMBH, Darmstadt, Germany).

In an exemplary embodiment, the method to form self-aligned pixel walls using a TFT array photomask may be used in reflective liquid crystal (LC) displays. In some embodiments, the method to form self-aligned pixel walls using a TFT array photomask may be used in multi- particle electrophoretic displays comprising a plurality of particles of a first color and first charge polarity and a second plurality of particles of a second color and opposite charge polarity. In other embodiments, the method to form self-aligned pixel walls using a TFT array photomask may be used in multi-particle electrophoretic displays comprising more than two pluralities of particles of different color, different mobilities and charge polarities. In still other embodiments, the method to form self-aligned pixel walls using a TFT array photomask may be used in electrowetting and electrofluidic displays.

Any of the full or partial wall TIR and dual particle-based display embodiments described herein may include at least one transparent barrier layer. A barrier layer may be located in various locations within the TIR-based display embodiment described herein. A barrier layer may act as one or more of a gas barrier or moisture barrier and may be hydrolytically stable. A barrier layer may be one or more of a flexible or conformable polymer. A barrier layer may comprise one or more of polyester, polypropylene, polyethylene terephthalate, polyethylene naphthalate or copolymer, or polyethylene. A barrier layer may comprise one or more of a chemical vapor deposited (CVD) or sputter coated ceramic-based thin film on a polymer substrate. The ceramic may comprise one or more of AI2O3, S1O2 or other metal oxide. A barrier layer may comprise one or more of a Vitriflex barrier film, Invista OXYCLEAR^® barrier resin, Toppan GL™ barrier films GL-AEC-F, GX-P-F, GL-AR-DF, GL-ARH, GL-RD, Celplast Ceramis^® CPT-036, CPT-001, CPT-022, CPA-001, CPA-002, CPP-004, CPP-005 silicon oxide (SiOx) barrier films, Celplast CAMCLEAR^® aluminum oxide (AlOx) coated clear barrier films, Celplast CAMSHIELD^® T AlOx-poly ester film, Torayfan^® CBH or Torayfan^® CBLH biaxially- oriented clear barrier polypropylene films.

Any of the display embodiments described herein may further comprise a conductive cross-over. A conductive cross-over may bond to the front electrode layer and to a trace on the rear electrode layer such as a TFT. This may allow a driver integrated circuit (IC) to control the voltage at the front electrode. In an exemplary embodiment, the conductive cross-over may comprise an electrically conductive adhesive that is flexible or conformable.

Any of the full or partial wall TIR and dual particle-based display embodiments described herein may include at least one diffuser layer. A diffuser layer may be used to soften the incoming light or reflected light or to reduce glare. The diffuser layer may comprise a flexible polymer. The diffuser layer may comprise ground glass in a flexible polymer matrix. The diffuser layer may comprise a micro-structured or textured polymer. The diffuser layer may comprise 3M™ anti-sparkle or anti-glare film. The diffuser layer may comprise 3M™ GLR320 film (Maplewood, MN) or AGF6200 film. A diffuser layer may be located at one or more various locations within the display embodiments described herein.

Any of the full or partial wall TIR and dual particle-based display embodiments described herein may comprise at least one optically clear adhesive (OCA) layer. The OCA layer may be flexible or conformable. OCA's may be used to adhere display layers together and to optically couple the layers. Any of the display embodiments described herein may comprise optically clear adhesive layers further comprise one or more of 3M™ optically clear adhesives 3M™ 8211, 3M™ 8212, 3M™ 8213, 3M™ 8214, 3M™ 8215, 3M™ OCA 8146-X, 3M™ OCA 817X, 3M™ OCA 821X, 3M™ OCA 9483, 3M™ OCA 826XN or 3M™ OCA 8148-X, 3M™ CEF05XX, 3M™ CEF06XXN, 3M™ CEF19XX, 3M™ CEF28XX, 3M™ CEF29XX, 3M™ CEF30XX, 3M™ CEF31, 3M™ CEF71XX, Lintec MO-T020RW, Lintec MO-3015UV series, Lintec MO-T015, Lintec MO-3014UV2+, Lintec MO-3015UV.

In other embodiments, any of the reflective image display embodiments comprising at least one full or partial wall disclosed herein may further include at least one spacer structure. The spacer structures may be used to control the gap between the front and rear electrodes. Spacer structures may be used to support the various layers in the displays. The spacer structures may be in the shape of circular or oval beads, blocks, cylinders or other geometrical shapes or combinations thereof. The spacer structures may comprise glass, metal, plastic or other resin.

At least one edge seal may be employed with the disclosed display embodiments. The edge seal may prevent ingress of moisture, air or other environmental contaminants from entering the display. The edge seal may be a thermally, chemically or a radiation cured material or a combination thereof. The edge seal may comprise one or more of an epoxy, silicone, polyisobutylene, acrylate or other polymer based material. In some embodiments the edge seal may comprise a metallized foil. In some embodiments the edge sealant may comprise a filler such as S1O2 or AI2O3. In other embodiments, the edge seal may be flexible or conformable after curing. In still other embodiments, the edge seal may also act as a barrier to moisture, oxygen and other gasses. At least one edge seal may comprise one or more of Sekisui Chemical (Osaka, Japan) SUR-137, Kyoritsu Chemical (Tokyo, Japan) 723K, Nagase (Tokyo, Japan) XNR5570 or Nagase XNR5588LV.

Any of the display embodiments described herein comprising at least one partial wall or a full wall or a combination of partial and full walls may further comprise, a viscosity

enhancement material. In an exemplary embodiment, the viscosity enhancement material may be added to the medium comprising electrophoretically mobile particles to prevent diffusion driven particle migration. In other embodiments, a viscosity enhancement material that undergoes shear thickening may be added to the medium comprising electrophoretically mobile particles. Any of the display embodiments described herein comprising at least one partial wall or full wall, may further comprise a gettering material. The gettering material may consume and trap the electrophoretically mobile particles thus suppressing subsequent diffusion driven migration.

In some embodiments, any of the display embodiments described herein may comprise at least one partial wall or a full wall of height in the range of about 1 -50 D m. In other

embodiments, the height of the walls may be in the range of about 2-30 D m. In still other embodiments, the height of the walls may be in the range of about 5-25 Dm. In an exemplary embodiment, the height of the walls may be in the range of about 10-25 D m.

In some embodiments, any of the display embodiments described herein may comprise at least one partial wall or a full wall of width in the range of about 1-30 D m. In other

embodiments, the width of the walls may be in the range of about 1-20 Dm. In still other embodiments, the width of the walls may be in the range of about 2-15 Dm. In an exemplary embodiment, the width of the walls may be in the range of about 4-10 D m.

In some embodiments, the aspect ratio of wall height/wall width is in the range of about 1- 25. In other embodiments, the aspect ratio of wall height/wall width is in the range of about 1 - 15. In still other embodiments, the aspect ratio of wall height/wall width is in the range of about 1 -5. In an exemplary embodiment, the aspect ratio of wall height/wall width is in the range of about 1 -2.

Any of the full or partial wall TIR and dual particle-based display embodiments described herein may comprise a rigid or flexible front light system with an outer surface facing a viewer. The front light system may comprise a light source to emit light through an edge of a light guide. The light source may comprise one or more of a light emitting diode (LED), cold cathode fluorescent lamp (CCFL) or a surface mounted technology (SMT) incandescent lamp. In an exemplary embodiment, the light source may define an LED whose output light emanates from a refractive or reflective optical element that concentrates said diode's output emission in a condensed angular range to an edge of a light guide. In some embodiments, a light source may be optically coupled to light guide.

The light guide may comprise one or more of a flexible or conformable polymer. The light guide may comprise more than one layer. The light guide may comprise one or more contiguous layers light guiding layers parallel to each other. The light guide may comprise at least a first light guiding layer that forms a transparent bottom surface. The light guide may comprise a second layer that forms a transparent top or outer surface. The light guide may comprise a third layer that forms a central transparent core. The refractive indices of the layers of the light guide may differ by at least 0.05. The multiple layers may be optically coupled. In an exemplary embodiment, the light guide may comprise an array of light extractor elements. The light extractor elements may comprise one or more of light scattering particles, dispersed polymer particles, air pockets, tilted prismatic facets, parallel prism grooves, curvilinear prism grooves, curved cylindrical surfaces, conical indentations, spherical indentations or aspherical indentations. The light extractor elements may be arranged such that they redirect light towards a semi-retro-reflective display sheet in a substantially perpendicular direction to the front surface of the semi-retro-reflective display sheet with a non-Lambertian narrow-angle distribution. The light guide may comprise diffusive optical haze. The front light system may contain more than one active zone. A light guide system utilized in any of the display embodiments described herein may comprise of a FLEx Front Light Panel made from FLEx Lighting (Chicago, IL). The light guide may comprise an ultra-thin, flexible light guide film manufactured by Nanocomp Oy, Ltd. (Lehmo, Finland).

In some embodiments, a porous reflective layer may be used in combination with the disclosed display embodiments. The porous reflective layer may be interposed between the front and rear electrode layers. In other embodiments the rear electrode may be located on the surface of the porous electrode layer.

In some embodiments, a dielectric layer may be used in combination with the disclosed display embodiments. The dielectric layer may be located on the surface of the transparent front electrode layer. The dielectric layer may be located on the surface of the rear electrode layer. Dielectric layers may be located on the surface of the front electrode and rear electrode layers. The dielectric layer may be used to protect the transparent electrode layer. The dielectric layer may define a conformal coating and may be free of pin holes or may have minimal pin holes. The dielectric layer may also be a structured layer. The dielectric layer may be a polymer or a combination of polymers. In an exemplary embodiment, the dielectric layer may include parylene. The dielectric layer may be a polymer such as a halogenated parylene or a polyimide. The dielectric layer may be a glass such as SiC , SiN, SiON, SiN_x, or other metal oxide inorganic layer. The dielectric layer may be a combination of a polymer and a glass. The compositions of the dielectric layers may approximately be the same on both the front and rear electrode layers in a symmetric fashion. The compositions of the dielectric layers may be different on the front and rear electrode layers in an asymmetric fashion.

Various control mechanisms for the invention may be implemented fully or partially in software and/or firmware. This software and/or firmware may take the form of instructions contained in or on a non-transitory computer-readable storage medium. Those instructions may then be read and executed by one or more processors to enable performance of the operations described herein. The instructions may be in any suitable form, such as but not limited to source code, compiled code, interpreted code, executable code, static code, dynamic code, and the like. Such a computer-readable medium may include any tangible non-transitory medium for storing information in a form readable by one or more computers, such as but not limited to read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; a flash memory, etc.

In some embodiments, a tangible machine-readable non-transitory storage medium that contains instructions may be used in combination with the disclosed display embodiments. In other embodiments the tangible machine-readable non-transitory storage medium may be further used in combination with one or more processors.

Fig. 18 shows an exemplary system for controlling a display according to one embodiment of the disclosure. In Fig. 18, display 300, 400, 500, 600, 700, 800, 900, 1740 is controlled by controller 1802 having processor 1804 and memory 1806. Other control mechanisms and/or devices may be included in controller 1802 without departing from the disclosed principles. Controller 1802 may define hardware, software or a combination of hardware and software. For example, controller 1802 may define a processor programmed with instructions (e.g., firmware). Processor 1804 may be an actual processor or a virtual processor. Similarly, memory 1806 may be actual memory (i.e., hardware) or virtual memory (i.e., software).

Memory 1806 may store instructions to be executed by processor 1804 for driving display 300, 400, 500, 600, 700, 800, 900, 1740. The instructions may be configured to operate display 300, 400, 500, 600, 700, 800, 900, 1740. In one embodiment, the instructions may include biasing electrodes associated with display 300, 400, 500, 600, 700, 800, 900, 1740 (not shown) through power supply 1808. When biased, the electrodes may cause movement of

electrophoretic particles to a region proximal to the front electrode to thereby absorb light.

Absorbing the incoming light creates a dark state of display 300, 400, 500, 600, 700, 800, 900, 1740. By appropriately biasing the electrodes, mobile light absorbing particles (e.g., particles 430, 432 in Fig. 4; particles 628, 632 in Fig. 6; particles 830 in Fig. 8; particles 930 in Fig. 9; particles 1752 in Fig. 17E) may be summoned to a location away from the transparent front electrode (e.g., electrode 410 in Fig. 4; electrode 608 in Fig. 6; electrode 818 in Fig. 8; electrode 918 in Fig. 9) and out of the evanescent wave region. Moving particles out of the evanescent wave region causes light to be reflected at the surface of the plurality of convex protrusions (e.g., protrusions 404 in Fig. 4; protrusions 808 in Fig. 8; protrusions 908 in Fig. 9; protrusions 1748 in Fig. 17E) by TIR and zeroth order reflections. In Fig. 6, light may be reflected by moving reflective electrophoretically mobile particles (such as TiC ) to the front sheet. Reflecting the incoming light creates a light state of display 300, 400, 500, 600, 700, 800, 900, 1740.

In the exemplary display embodiments described herein, they may be used in Internet of Things (IoT) devices. The IoT devices may comprise a local wireless or wired communication interface to establish a local wireless or wired communication link with one or more IoT hubs or client devices. The IoT devices may further comprise a secure communication channel with an IoT service over the internet using a local wireless or wired communication link. The IoT devices comprising one or more of the display devices described herein may further comprise a sensor. Sensors may include one or more of a temperature, humidity, light, sound, motion, vibration, proximity, gas or heat sensor. The IoT devices comprising one or more of the display devices described herein may be interfaced with home appliances such as a refrigerator, freezer, television (TV), close captioned TV (CCTV), stereo system, heating, ventilation, air

conditioning (HVAC) system, robotic vacuum, air purifiers, lighting system, washing machine, drying machine, oven, fire alarms, home security system, pool equipment, dehumidifier or dishwashing machine. The IoT devices comprising one or more of the display devices described herein may be interfaced with health monitoring systems such as heart monitoring, diabetic monitoring, temperature monitoring, biochip transponders or pedometer. The IoT devices comprising one or more of the display devices described herein may be interfaced with transportation monitoring systems such as those in an automobile, motorcycle, bicycle, scooter, marine vehicle, bus or airplane.

In the exemplary display embodiments described herein, they may be used IoT and non- IoT applications such as in, but not limited to, electronic book readers, portable computers, tablet computers, cellular telephones, smart cards, signs, watches, wearables, military display applications, automotive displays, automotive license plates, shelf labels, flash drives and outdoor billboards or outdoor signs comprising a display. The displays may be powered by one or more of a battery, solar cell, wind, electrical generator, electrical outlet, AC power, DC power or other means.

While the principles of the disclosure have been illustrated in relation to the exemplary embodiments shown herein, the principles of the disclosure are not limited thereto and include any modification, variation or permutation thereof.

Claims

WHAT IS CLAIMED IS :

1. An image display device capable of limiting particle drift and diffusion, the display comprising:

a front electrode;

an optically transparent sheet having a surface with a plurality of convex protrusions extending from a surface thereof;

a rear electrode positioned opposite the plurality of convex protrusions to form a cavity therebetween;

at least one electrophoretically mobile particle suspended within the cavity; and a plurality of partitions to form one or more segments within the cavity.

2. The image display device of claim 1 , wherein the image display device defines a Totally Internally Reflective (TIR) device.

3. The image display device of claim 1 , further comprising a medium disposed in the cavity.

4. The image display device of claim 1 , wherein the at least one electrophoretically mobile

particle defines a charged particle.

5. The image display device of claim 1 , further comprising a voltage source to apply a voltage bias across the medium to form an electromagnetic field between the front electrode and the rear electrode to generate a field between the front and the rear electrodes.

6. The image display device of claim 1, wherein the plurality of partitions further comprises at least three or more partitions that form one or more partitioned space within the cavity.

7. The image display device of claim 6, wherein the three or more partitions extend from each of a respective convex protrusions towards the cavity.

8. The image display device of claim 1 , wherein at least one of the plurality of partitions extends from a region proximal to the rear electrode into the cavity.

9. The image display device of claim 1 , wherein a first of the plurality of partitions extends from a first convex protrusion towards the cavity and a second of the plurality of partitions extends from the bottom electrode towards the cavity.

10. The image display device of claim 9, wherein the first and the second partitions are

substantially aligned in a first direction.

11. The image display device of claim 9, wherein the first and the second partitions are not aligned.

12. The image display device of claim 6, wherein a first partition of the plurality of partitions extends from an abutment of two adjoining protrusions.

13. The image display device of claim 6, wherein a first partition of the plurality of partitions extends from a convex protrusion arch.