Electrophoretic display layer with thin film electrode

Abstract

A method for manufacturing an electrophoretic display layer including various thin films deposited directly on a microcapsule layer of an electrophoretic medium. In one embodiment, a thin film of light-transmissive conductive material is deposited to produce a transparent front electrode for an electrophoretic display. In some embodiments, both a dielectric layer and a thin film of light-transmissive conductive material are deposited on the microcapsules.

Description

[0001] Related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 971,285, filed February 7, 2020. All patents and publications described herein are incorporated herein by reference in their entirety. Background of the Invention

[0004] In typical encapsulated electrophoretic displays found in most e-readers, a slurry is coated onto a pre-fabricated polyethylene terephthalate (PET) sheet on which indium tin oxide (ITO) has been deposited. The coated PET-ITO material is then incorporated into a stack including another electrode to fabricate the electrophoretic display. The electrophoretic medium generally comprises electrophoretic particles in a nonpolar liquid, charge control agents, image stabilizers, and flocculants, typically encapsulated in a flexible organic matrix such as a gelatin / gum arabic coagulation layer. The PET-ITO material is conductive, transparent, and possesses excellent barrier properties. In most commercial implementations, the PET-ITO layer acts as the "top electrode" because the user sees through it to see the pattern (e.g., text) displayed in the electrophoretic medium. Additionally, an adhesive layer is typically applied to the PET-ITO before coating the slurry to improve slurry adhesion and create a more uniform encapsulation coating on the substrate, preferably a single-layer encapsulation. The adhesive layer is typically at least 1 μm thick, and more often about 5 μm thick. Often, the adhesive layer is doped to improve conductivity compared to general adhesives, which are mostly dielectric. Generally, the encapsulation electrophoretic medium is coated onto the substrate using slot coating, in which a slurry in a carrier medium is forcibly advanced through a slot onto the substrate, which moves relative to the slot. During commercial manufacturing, after the slurry has cured, a second adhesive is applied to the opposite side of the slurry layer, and a release sheet is then applied to create a front plane laminate (FPL). At a later time, the release sheet is removed, and the front plane laminate is adhered to a backplane, such as an active matrix thin-film transistor (AM-TFT). This method is described in several issued patents of E Ink Corporation, including, for example, U.S. Patent No. 6,982,178, which is incorporated herein by reference in its entirety.

[0005] However, this standard method of manufacturing front panel laminates does have some limitations. Because at least one adhesive layer is used in the stack encapsulating the electrophoretic media, the electric field across the capsule is not as strong as it would be in the case where the capsule is directly between two electrode layers. This increases the display's switching time. Additionally, the adhesive layer can be a source of failure, such as peeling and fading. In some cases, dopants used in the adhesive become mobile at high temperatures, leading to inconsistent switching of the electrophoretic media across the display and potentially causing pixelation of the image to blend together, a condition known as "blooming." Invention Overview

[0007] As described herein, an alternative and improved method for fabricating planar electrodes is provided. Because it is feasible to introduce an encapsulated electrophoretic medium into a vacuum chamber, thin-film deposition methods can be used to coat the electrode layer directly on top of the encapsulated electrophoretic medium, thereby resulting in a thinner material stack and achieving a high local electric field while providing the same voltage and using approximately the same energy. Furthermore, these thin-film deposition techniques can be extended to coating encapsulated materials with dielectric thin films, which may be beneficial in preventing moisture ingress, preventing short circuits caused by gaps between capsules and pinholes in, for example, cured adhesives, and improving the optical responsiveness of the electrophoretic medium.

[0008] Therefore, in one aspect, the electrophoretic display layer includes a first substrate; a capsule layer containing an electrophoretic medium, the capsule layer having a planar surface and a corrugated surface; and a light-transmitting conductive material layer in direct contact with the corrugated surfaces of a plurality of capsules, wherein the capsule layer is disposed between the first substrate and the light-transmitting conductive material layer. In some embodiments, the electrophoretic medium contains at least one type of charged particles that move within the capsules in response to an applied electric field. In some embodiments, the capsule layer further includes a polyurethane adhesive between at least some of the capsules within the capsule layer. In some embodiments, the first substrate is a release sheet. In some embodiments, an adhesive layer is present between the first substrate and the capsule layer. In some embodiments, a planarization layer is disposed on the light-transmitting conductive material layer. In some embodiments, a second substrate is disposed on the planarization layer such that the planarization layer is disposed between the light-transmitting conductive material layer and the second substrate. In some embodiments, a first dielectric material layer is disposed between the capsule layer and the light-transmitting conductive material layer. In some embodiments, the first dielectric material layer comprises Si3N4, SiO2, Al2O3, HFO2, ZrO2, or a polymer. In some embodiments, a second conductive material layer is disposed between the first substrate and the encapsulation layer comprising an electrophoretic dielectric. In some embodiments, the second dielectric material layer is disposed between the second conductive material layer and the encapsulation layer. In some embodiments, the light-transmitting conductive material comprises indium tin oxide or zinc oxide. In some embodiments, the first substrate is substantially planar. In some embodiments, the first substrate is entirely non-planar but partially planar. In some embodiments, the second substrate is substantially planar.

[0009] In another aspect, a method for manufacturing an electrophoretic display layer includes providing a first substrate; depositing an encapsulation layer comprising an electrophoretic medium on the first substrate, thereby forming a wavy surface of the encapsulation layer on a surface of the encapsulation layer opposite to the first substrate; and depositing a light-transmitting conductive material layer on the wavy surface of the encapsulation layer. In some embodiments, the step of depositing the light-transmitting conductive material layer is performed at a vacuum pressure below 133 Pascals (1 Torr). In some embodiments, the step of depositing the light-transmitting conductive material layer is performed at a vacuum pressure below 13 Pascals (100 millitors). In some embodiments, the deposition step is performed using a chemical vapor deposition method. In some embodiments, indium tin oxide or zinc oxide is deposited as the light-transmitting conductive layer. In some embodiments, the method further includes depositing a first dielectric layer on the substrate, and then depositing the encapsulation layer comprising the electrophoretic medium. In some embodiments, the dielectric layer comprises Si3N4, SiO2, Al2O3, HFO2, ZrO2, or a polymer. In some embodiments, the method further includes depositing a second dielectric layer on the waveform surface of the capsule containing the electrophoretic medium, and then depositing the light-transmitting conductive material layer over the second dielectric layer and on the waveform surface of the capsule containing the electrophoretic medium. Brief description of the attached diagram

[0011] Figures 1A to 1E This invention describes a method for producing an electrophoretic display layer using indium tin oxide (ITO) vapor deposition under reduced ambient pressure. Figure 1A The image shows the coating of a slurry onto a substrate including electrodes. Figure 1B The experiment demonstrates that ITO can be deposited directly onto the top of the coated capsule under reduced environmental pressure to create an upper transparent electrode. Figure 1C This demonstrates the provision of voltage sources between the electrodes and throughout the encapsulated electrophoretic dielectric. Figure 1D The image shows a close-up view where the capsule has been switched to a white state and the upper transparent electrode is invisible. When the polarity is switched, the close-up view turns black because dark particles with opposite charges are driven to the viewing surface.

[0012] Figure 2 A flowchart illustrating the method described herein is provided, wherein the substrate is optionally coated with a very thin layer of dielectric material to prevent the device from short-circuiting if some of the deposited ITO finds a channel through the encapsulation layer during deposition. Figure 2 Additionally, consider depositing a dielectric layer on top of the coated capsule, a moisture barrier layer on top of the deposited transparent conductor, and a planarization layer on top of the moisture barrier layer.

[0013] Figures 3A to 3E Various steps for producing an electrophoretic display layer are described, including depositing a light-transmitting conductive material directly onto a capsule containing an electrophoretic medium.

[0014] Figures 4A to 4E The various steps for producing the electrophoretic display layer are described, including the direct deposition of a light-transmitting conductive material onto a capsule containing an electrophoretic medium. Figures 4A to 4E In this design, the substrate, including the second electrode, is coated with a dielectric to prevent short circuits from the coated transparent conductive material to the second electrode. See circled area 405.

[0015] Figures 5A to 5F Various steps for producing an electrophoretic display layer are described, including depositing a light-transmitting conductive material over a dielectric layer deposited directly on a capsule containing an electrophoretic medium. The dielectric layer can be very thin (e.g., 100 nm, 50 nm, 20 nm, or thinner), but serves as a moisture barrier and also prevents short circuits between electrodes in the resulting electrophoretic display.

[0016] Figure 6 This describes a nozzle that can be used to deposit capsules of electrophoretic media onto a substrate.

[0017] Figure 7The optical backlash of the display stack, which consists of only a PET / ITO layer, a microcapsule layer sprayed onto PET / ITO, and a thin ITO layer deposited on the microcapsule, is shown at three operating temperatures.

[0018] Figure 8 The recoil of two simple microcapsule displays is shown as a function of temperature. By including an intermediate dielectric layer, recoil is reduced over a wide temperature range.

[0019] Figure 9 show Figure 8 The total contrast between the white and black states of two simple microcapsule displays and a comparison with a "conventional" microcapsule electrophoretic display, which includes a doped binder layer between the microcapsule and at least one PET / ITO layer.

[0020] Figures 10A to 10E This invention describes a method for forming an active matrix electrophoretic display suitable for use as an e-reader by encapsulating an electrophoretic material onto an active matrix backplane and then directly sputtering a transparent conductor onto the encapsulation. Figure 10A The image is displayed on a standard 6" thin-film transistor (TFT) substrate, which includes 1448 × 1072 electrodes and an image controller bonded to the substrate. Figure 10B The experiment demonstrates that ITO can be deposited directly onto the top of a sprayed capsule under reduced environmental pressure to create an upper transparent electrode. Figure 10C The top-plane interconnect (TPC) driving electrode on the display substrate is connected to the deposited ITO layer via a top-plane connection. When the image controller is connected to an external driver, producing very sharp text and moving between pages is commonplace. Figure 10D and 10E As shown.

[0021] Detailed Explanation

[0022] This invention particularly includes an electrophoretic display layer comprising various thin films deposited directly on a capsule layer of an electrophoretic medium. For example, a thin film of a transparent conductive material can be deposited to create a transparent front electrode for an electrophoretic display. For example, a thin film of a dielectric material can be deposited to create a barrier layer that prevents moisture ingress. Alternatively, both a dielectric layer and a transparent conductive material thin film can be deposited over the capsule layer of the electrophoretic medium. In some configurations, the dielectric layer is deposited on the capsule before the transparent conductive material thin film is deposited. In other configurations, the transparent conductive material thin film is deposited before the dielectric layer is deposited. Various thin film deposition methods can be used to deposit these materials, such as sputtering, ablation, and vapor deposition or solution deposition. In some embodiments, deposition is performed at pressures less than atmospheric pressure, for example, at 100 Torr or less.

[0023] An encapsulated electrophoretic display generally does not suffer from the clustering and settling failure modes of conventional electrophoretic devices and offers additional advantages such as the ability to print or coat the display on a variety of flexible substrates. The term "printing" is intended to encompass all forms of printing and coating, including but not limited to: pre-metered coatings such as patch die coating, slotor extrusion coating, slide or cascade coating, and screen coating; roll coatings such as knife over roll coating and forward and reverse rollcoating; gravure coating; dip coating; spray coating; meniscus coating; spin coating; brush coating; air knife coating; screen printing methods; electrostatic printing methods; thermal printing methods; inkjet printing methods; electrophoretic deposition (see U.S. Patent No. 7,339,715); and other similar techniques. Therefore, the resulting display can be large and flexible. Furthermore, because the display medium can be printed (using various methods), the display itself can be manufactured inexpensively.

[0024] Some electro-optic materials are solid in the sense that they have a solid outer surface, but these materials may, and often do, have internal spaces filled with liquid or gas. In the following text, for convenience, such a display using solid electro-optic materials may be referred to as a "solid-state electro-optic display." Therefore, the term "solid-state electro-optic display" includes rotating dual-color component displays, encapsulated electrophoretic displays, microporous electrophoretic displays, and encapsulated liquid crystal displays.

[0025] The terms “bistable” and “bistable” are used herein in their conventional sense in the art to refer to a display comprising display elements having a first display state and a second display state that differ in at least one optical property, such that after any given element has been driven to present its first or second display state by means of an addressing pulse of finite duration, the state will persist after the addressing pulse terminates for at least several times, for example, at least four times, the minimum duration of the addressing pulse required to change the state of the display element. U.S. Patent No. 7,170,670 shows that some particle-based electrophoretic displays with grayscale capability are stable not only in their extreme black and white states but also in their intermediate gray states, and so are some other types of electro-optical displays. This type of display is properly referred to as multistable rather than bistable; however, for convenience, the term “bistable” may be used herein to encompass both bistable and multistable displays.

[0026] One type of electro-optic display that has been the subject of intensive research and development for several years is the particle-based electrophoretic display, in which multiple charged particles move through a fluid under the influence of an electric field. Compared to liquid crystal displays (LCDs), electrophoretic displays offer advantages such as good brightness and contrast, wide viewing angles, state bistability, and low power consumption. However, issues concerning the long-term image quality of these displays have hindered their widespread use. For example, the particles constituting an electrophoretic display are prone to settling, leading to a short lifespan for these displays.

[0027] Numerous patents and applications assigned to or registered with the Massachusetts Institute of Technology (MIT) and E Ink Corporation describe various techniques used in encapsulating electrophoretic media and other electro-optic media. Such encapsulation media comprise a plurality of small capsules, each capsule itself comprising an inner phase containing electrophoretically moving particles in a fluid medium and a capsule wall surrounding the inner phase. Typically, the capsules themselves are held in a polymer binder to form a coherent layer located between two electrodes. The techniques described in these patents and applications include:

[0028] (a) Electrophoretic particles, fluids, and fluid additives; see, for example, U.S. Patents 7,002,728 and 7,679,814;

[0029] (b) Encapsulation, adhesives, and encapsulation methods; see, for example, U.S. Patents 6,922,276 and 7,411,719;

[0030] (c) Films and sub-assemblies containing electro-optic materials; see, for example, 6,825,829; 6,982,178; 7,236,292; 7,443,571; 7,513,813; 7,561,324; 7,636,191; 7,649,666; 7,728,811; 7,729,039; 7,791,782; 7,839,564; 7,843,621; 7,843,624; 8,034,209; 8,068,2 U.S. Patent Nos. 72; 8,077,381; 8,177,942; 8,390,301; 8,482,835; 8,786,929; 8,830,553; 8,854,721; and 9,075,280; and U.S. Patent Application Publications Nos. 2009 / 0109519; 2009 / 0168067; 2011 / 0164301; 2014 / 0027044; 2014 / 0115884; and 2014 / 0340738;

[0031] (d) Backplanes, adhesive layers, and other auxiliary layers used in displays, and methods thereof; see, for example, D485,294; 6,124,851; 6,130,773; 6,177,921; 6,232,950; 6,252,564; 6,312,304; 6,312,971; 6,376,828; 6,392,786; 6,413,790; 6,422,687; 6,445,374; 6,480,182; 6,498,114; 6,506,438; 6,518,949; 6,521,489; 6,535,197; 6,545,291; 6,639,578; 6,657 772; 6,664,944; 6,680,725; 6,683,333; 6,724,519; 6,750,473; 6,816,147; 6,819,471; 6,825,068; 6,831,769; 6,842,167; 6,842,279; 6,842,657; 6,865,010;6,967,640;6,980,196;7,012,735;7,030,412;7,075,703;7,106,296;7,110,163;7,116,318;7,148,128;7,167,155;7,173,752;7,17 6,880; 7,190,008; 7,206,119; 7,223,672; 7,230,751; 7,256,766; 7,259,744; 7,280,094; 7,327,511; 7,349,148; 7,352,353; 7,365,394; 7,365,73 3; 7,382,363; 7,388,572; 7,442,587; 7,492,497; 7,535,624; 7,551,346; 7,554,712; 7,583,427; 7,598,173; 7,605,799; 7,636,191; 7,649,674; 7, 667,886;7,672,040;7,688,497;7,733,335;7,785,988;7,843,626;7,859,637;7,893,435;7,898,717;7,957,053;7,986,450;8,009,344;8,027 081; 8,049,947; 8,077,141; 8,089,453; 8,208,193; 8,373,211; 8,389,381; 8,498,042; 8,610,988; 8,728,266; 8,754,859; 8,830,560; 8,891,155;U.S. Patents Nos. 8,989,886; 9,152,003; and 9,152,004; and Nos. 2002 / 0060321; 2004 / 0105036; 2005 / 0122306; 2005 / 0122563; 2007 / 0052757; 2007 / 0097489; 2007 / 0109219; 2009 / 0122389; 2009 / 0315044; 2011 / 0026101; 2011 / 0140744; 2 U.S. Patent Application Publications Nos. 011 / 0187683; 2011 / 0187689; 2011 / 0292319; 2013 / 0278900; 2014 / 0078024; 2014 / 0139501; 2014 / 0300837; 2015 / 0171112; 2015 / 0205178; 2015 / 0226986; 2015 / 0227018; 2015 / 0228666; and 2015 / 0261057; and International Application Publication No. WO 00 / 38000; European Patents Nos. 1,099,207B1 and 1,145,072B1;

[0032] (e) Color formation and color adjustment; see, for example, U.S. Patents 7,075,502 and 7,839,564;

[0033] (f) A method for driving a display; see, for example, U.S. Patents 7,012,600 and 7,453,445;

[0034] (g) Applications of the display; see, for example, U.S. Patents 7,312,784 and 8,009,348; and

[0035] (h) Non-electrophoretic displays, as described in U.S. Patent Nos. 6,241,921; 6,950,220; 7,420,549; 8,319,759; and 8,994,705; and U.S. Patent Application Publication No. 2012 / 0293858.

[0036] Many of the aforementioned patents and applications recognize that the walls surrounding discrete microcapsules in an encapsulated electrophoretic medium can be replaced by a continuous phase, thereby producing a so-called polymer-dispersed electrophoretic display, wherein the electrophoretic medium comprises a plurality of discrete electrophoretic fluid droplets and a continuous phase of polymeric material, and the discrete electrophoretic fluid droplets within such a polymer-dispersed electrophoretic display can be considered as capsules or microcapsules even without a discrete membrane associated with each individual droplet; see, for example, the aforementioned U.S. Patent No. 6,866,760. Therefore, for the purposes of this application, such a polymer-dispersed electrophoretic medium is considered a subgenre of encapsulated electrophoretic media.

[0037] Although electrophoretic media are typically opaque (because, for example, in many electrophoretic media, particles substantially block the transmission of visible light through the display) and operate in reflective mode, many electrophoretic displays can operate in a so-called "shutter mode," in which one display state is substantially opaque and another display state is transparent. See, for example, U.S. Patents 5,872,552; 6,130,774; 6,144,361; 6,172,798; 6,271,823; 6,225,971; and 6,184,856. Dielectrophoretic displays, similar to electrophoretic displays but dependent on changes in electric field strength, can operate in a similar mode; see U.S. Patent 4,418,346. Other types of electro-optic displays can also operate in shutter mode. In the multi-layered structure of a full-color display, an electro-optic medium operating in shutter mode may be useful; in such a structure, at least one layer adjacent to the viewing surface of the display operates in shutter mode to expose or hide a second layer further away from the viewing surface.

[0038] The term “transparent” is used in this patent and herein to mean that a layer so indicated allows sufficient light to pass through so that an observer can see through the layer to observe changes in the display state of the electro-optic medium, which would generally be visible through the conductive layer and adjacent substrate (if present); where the electro-optic medium displays changes in reflectivity at invisible wavelengths, the term “transparent” should of course be interpreted as meaning the transmission at the relevant invisible wavelengths.

[0039] The methods described herein are generally applicable to coating a substrate with an encapsulating electrophoretic dielectric layer, followed by coating the encapsulating electrophoretic dielectric layer with a thin, transparent conductive material layer. In many cases, the substrate will be substantially planar, for example, a polymer film having a thickness ranging from about 1 to about 25 mils (25 to 634 μm), preferably from about 2 to about 10 mils (51 to 254 μm). The substrate can be, for example, a release sheet designed to be removed from the electrophoretic display material layer before the electrophoretic display material is laminated to, for example, a backplane. In other embodiments, the substrate can be the backplane itself, for example, a thin-film transistor (TFT) backplane including pixel electrodes. However, in other embodiments, the substrate can be flexible, for example, a polymer film coated with a transparent conductor such as indium tin oxide, which can be bent to some extent before the transparent conductor is damaged. In other embodiments, a polymer impregnated with a unique flexible transparent conductive material such as graphene or carbon nanotubes can be used as the substrate. In other embodiments, the substrate can be a simple conductive electrode such as a metal film or a graphite layer. In other embodiments, the substrate can be substantially transparent, for example, glass. The substrate need not be a film or a substantially planar material; for example, the substrate can be part of an object with an irregular surface, such as a vehicle body. In this case, the substrate will generally be partially planar because the microcapsule layers are deposited substantially flat against the substrate, creating a relatively wavy surface on which a transparent conductive film can be deposited. However, the substrate itself is entirely non-planar. Due to the very small scale of the microcapsules, a partially planar substrate might be substantially planar for a distance of only one centimeter, for example, only five centimeters.

[0040] In electrophoretic displays, one or more binder layers are often present in the layer stack. For example, a binder layer may exist between the electrophoretic layer and the electrodes, and this binder layer remains in the final display. This binder layer naturally has a significant impact on the electro-optic properties of the display. Inevitably, some voltage drop occurs within the binder layer between the electrodes, thereby reducing the voltage available to drive the electrophoretic layer. The effect of the binder tends to become more pronounced at lower temperatures, and this temperature variation of the binder's effect complicates the driving of the display. By increasing the conductivity of the binder layer, for example by doping the layer with tetrabutylammonium hexafluorophosphate or other materials as described in U.S. Patents 7,012,735 and 7,173,752, the voltage drop in the binder can be reduced, and the low-temperature operation of the display can be improved.

[0041] Figure 1 illustrates a general method for fabricating electrodes on a thin film. A substrate 110 is provided, on which an encapsulation electrophoretic dielectric layer 120 is deposited, for example, using slit coating, dip coating, brushing, spraying, etc. The substrate 110 may be flexible or non-flexible, and may include electrode layers; for example, the substrate 110 may be a TFT array. Alternatively, the substrate may include transparent, translucent, or opaque continuous or segmented electrode layers. For example, as described in the above patent, the encapsulation electrophoretic dielectric layer 120 may include more than one type of charged pigment particles. Thus, the encapsulation electrophoretic dielectric layer 120 may alternate between, for example, white and black. Alternatively, the encapsulation electrophoretic dielectric layer 140 may contain three types of particles, wherein a first group of charged pigment particles is red, a second group of charged pigment particles is green, and a third group of charged pigment particles is blue. Alternatively, the encapsulation electrophoretic dielectric layer 120 may contain three types of particles, wherein a first group of charged pigment particles is red, a second group of charged pigment particles is black, and a third group of charged pigment particles is white. Alternatively, the encapsulating electrophoretic dielectric layer 120 may contain four types of particles, wherein the first group of charged pigment particles is white, the second group of charged pigment particles is cyan, the third group of charged pigment particles is yellow, and the fourth group of charged pigment particles is magenta. Alternatively, the encapsulating electrophoretic dielectric layer may contain four types of particles, wherein the first group of charged pigment particles is red, the second group of charged pigment particles is green, the third group of charged pigment particles is blue, and the fourth group of charged pigment particles is black. Alternatively, the encapsulating electrophoretic dielectric layer may contain four types of particles, wherein the first group of charged pigment particles is red, the second group of charged pigment particles is yellow, the third group of charged pigment particles is blue, and the fourth group of charged pigment particles is black.

[0042] After the encapsulation electrophoretic material layer 120 is coated onto the substrate 110 and cured, the assembly is placed in a vacuum chamber suitable for thin film deposition. After the back pressure has been reduced, a thin film of the light-transmitting conductive material 140 is directly deposited onto the encapsulation electrophoretic material layer 120 using a deposition apparatus 130 to form the light-transmitting conductive material layer 150, i.e., as shown... Figure 1B and Figure 1C As shown. The deposition apparatus 130 can be a sputtering apparatus, an ablation apparatus, a chemical vapor deposition apparatus, or an atomic layer deposition apparatus. For example, various thin film deposition solutions can be obtained from Veeco Corporation, Plainview, NY. Thin film deposition methods are generally performed at pressures below atmospheric pressure, for example, less than 100 Torr, less than 50 Torr, less than 10 Torr, less than 1 Torr, or less than 100 m Torr. In some cases, it may be necessary to slowly reduce the atmosphere over the encapsulated electrophoretic material layer 120 to avoid capsule rupture. In some cases, it may be necessary to deliberately dehydrate the encapsulated electrophoretic material layer 120, for example, by storing it under dry nitrogen for a period of time.

[0043] Once the transparent conductive material layer 150 has been deposited, it can be connected to a voltage source 180, thereby providing an electric field across the encapsulation electrophoretic material layer 120, thus generating... Figure 1C The electrophoretic display shown. The viewer will see through the photoconductive material layer 150 to observe the state of the encapsulated electrophoretic material layer 120. For example, when the substrate 110 is a graphite-coated glass sheet, as... Figure 1D As shown, under an optical microscope, the white state appears as multiple circles. When the polarity of the voltage source is reversed by 180 degrees, as... Figure 1E As shown, the field of vision appears to be completely black.

[0044] It should be understood that the substrate 110 does not need to be rigid and can be flexible enough not to cause rupture of the capsule within the encapsulation electrophoretic dielectric layer or to cause failure of the transparent conductive material layer 150 or the subsequent electrode material. For example, the substrate 110 may comprise a transparent polymer such as polyethylene terephthalate (PET), polycarbonate, polypropylene, acrylic acid, or a cyclic olefin copolymer (COC). The integrity of the transparent conductive material layer 150 can be enhanced by coating a barrier layer such as a polyurethane layer onto the transparent conductive material layer 150.

[0045] pass Figure 2 The flowchart illustrates a method for fabricating an electrophoretic display layer that includes a layer of transparent conductive material. It will be clear, relative to Figures 3-5, Figure 2 The flowchart in the diagram is exemplary and other variations can be used to produce an electrophoretic display layer with fewer or more layers. Starting at step 210, a substrate is provided. As discussed above, the substrate may comprise a polymer; however, other materials such as metal or glass are also suitable. The substrate may be shaped before the process begins with methods such as thermoforming, casting, injection molding, blow molding, grinding, etching, or cutting. The substrate may be part of a larger component, such as a window, in a vehicle or building material. The substrate may comprise a conductive material. After the substrate is provided in step 210, an optional dielectric layer is applied in step 220. The dielectric layer may comprise any suitable material. In some cases, thin films of high-dielectric materials such as Si3N4, SiO2, Al2O3, HFO2, ZrO2, or polymers are preferred. The thickness of such a film may be less than 1 μm, for example, less than 500 nm, less than 200 nm, less than 100 nm, less than 50 nm, less than 20 nm, or less than 10 nm. For example, the thickness of the thin-film dielectric layer can be from 1 nm to 500 nm, such as from 10 nm to 100 nm. Other dielectric materials can be, for example, thin polymer coatings, which can be achieved by vapor deposition.

[0046] Suitable polymers for thin films include polyurethane, polyimide, and polyacrylate. The dielectric polymer layer between the capsule layer and the observation-side electrode must be transparent and have a refractive index that does not distort the optical properties of the capsule layer, as follows. Specifically, a polymer layer with low conductivity (<5000 pS / cm at 25°C) and a moderate relative permittivity (preferably in the range of 1.8-10) provides the desired combination of dielectric separation between the electrophoretic medium and the transparent electrode. Generally, the thickness of such a layer is less than 0.5 μm, preferably less than 300 nm, preferably less than 200 nm, and preferably less than 100 nm. The polymer layer can be formed from polyimide, polycarbonate, polyether, polyester, polyquinoline, polyquinoxaline, polyoxadiazole, polynorbornene, cyclic olefins and cyclic olefin copolymers, polytetrafluoroethylene, polyperfluorocyclobutene, polybenzocyclobutene, polybenzoxazole, and fluorocarbon compounds such as polytetrafluoroethylene, for example, Teflon AF (poly[4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene]). In some embodiments, the dielectric can also be used as an adhesive such as polyurethane adhesives, vinyl acetate adhesives, epoxy resins, and acrylic adhesives, such as those described in U.S. Patent No. 7,012,735, which is incorporated herein by reference.

[0047] In step 230, the resulting structure (substrate and optional dielectric layer) is coated with an encapsulating electrophoretic dielectric layer. This step can be performed using methods such as slot coating, spraying, dip coating, electrodeposition, powder coating, screen printing, or brush coating. The encapsulating electrophoretic dielectric can be delivered in the form of a slurry of capsules and polyurethane adhesive, or the encapsulating electrophoretic dielectric can be delivered by "freeze-drying," i.e., delivered after freeze-drying. Generally, the coated material will be cured, for example, by heat and / or pressure to solidify the adhesive, or by radiation curing with ultraviolet radiation. The solid electro-optic layer is generally an encapsulating electrophoretic layer, but it can also be a polymer-dispersed electrophoretic layer, a rotating bicolor component, or an electrochromic layer.

[0048] After the encapsulation electrophoretic dielectric layer has been coated, the coated substrate may need to be adjusted before proceeding to the next step. In some cases, as shown in step 235, an intermediate dielectric layer is deposited onto the encapsulation layer. Any dielectric material previously discussed with respect to step 220 can be used in step 235. After depositing the dielectric layer, or if no dielectric layer is used, a thin-film conductor is deposited in step 240. In some cases, it may be useful to mask the substrate and / or a portion of the encapsulation electrophoretic dielectric layer with, for example, masking tape before coating the assembly with the thin-film conductor. This allows clear access to the rear conductor once the masking is removed, facilitating easy connection of the front and rear conductors to a voltage source. Polymer films found to be usable as masking layers include... Adhesive tape (polyimide tape available from du Pont de Nemours & Company, Wilmington, DE) and RP301 film (acrylic film available from Nitto America, Inc., Fremont, CA).

[0049] As described with respect to Figure 1, in step 240, a transparent conductive material film is applied to the encapsulation electrophoretic material layer. This method may include sputtering, ablation, chemical vapor deposition, or solution deposition. The material can be any suitable transparent conductive material capable of forming a film, such as indium tin oxide, zinc oxide, cadmium oxide, doped indium tin oxide, doped zinc oxide, or doped cadmium oxide. After depositing the transparent conductive material layer, an optional moisture barrier layer may be deposited on top of the transparent conductive material layer in step 250. The moisture barrier layer will prevent water from entering the encapsulation layer, where water would degrade the performance of the encapsulation electrophoretic medium. The moisture barrier layer can be a thin film dielectric as described above with respect to step 220. The moisture barrier layer can also be a low water vapor transmission rate (WVTR) polymer such as polyurethane, polypropylene, polyethylene, for example, HDPE or PET, or ethylene-vinyl alcohol. The moisture barrier layer should be substantially transparent. The thickness of the moisture barrier layer can range from 1 nm (film) to 20 μm (coated polymer film). For example, the thickness of a thin moisture-proof layer material can be less than 1 μm, for example, less than 500 nm, for example, less than 200 nm, for example, less than 100 nm, for example, less than 50 nm. For example, the thickness of a thin-film dielectric layer can be from 1 nm to 500 nm, for example, from 10 nm to 100 nm. Although not in Figure 2 The flowchart can be described in the above, but it can also be considered in other ways. Figure 5C Before the deposition of the transparent conductive material film shown, such as Figure 5B As shown, the thin film moisture barrier is directly deposited on the encapsulation electrophoretic dielectric layer.

[0050] Finally, after the optional moisture barrier has been applied, an optional planarization layer can be deposited in step 260. The planarization layer is best deposited in… Figure 3D ,4D As seen in 5E, the planarization layer "smooths out" the surface morphology produced by the coating step and ensures a more uniform bond with the upper substrate, such as a protective sheet, a UV filter layer, or some other sealing layer. In other words, the composition can be spread on an irregular surface and cured to form a thin, smooth adhesive layer with virtually no gaps between the irregular surface and the composition. The planarization layer may comprise polyester, urethane, or acrylic, and may contain dopants, crosslinking agents, and / or adhesion promoters. In some embodiments, the planarization layer may be less than 25 μm thick, i.e., less than 10 μm thick, i.e., less than 5 μm thick, i.e., less than 3 μm thick. The planarization layer may have a thickness of less than 10 μm. 10 Ohm·cm, which is approximately 10 9 Total volume resistivity (Ohm·cm).

[0051] It is possible Figures 3A to 5F Various implementation schemes and their layer-by-layer structures are shown. It is noteworthy that these layers and features are not scaled. For example, microcapsules 320 are typically on the order of approximately 30-50 μm, while the light-transmitting conductive material 330 is on the order of approximately 50-200 nm. The structure of a simple electrophoretic layer is shown... Figures 3A to 3E In. Figure 3A In this process, a simple substrate 310 is coated with a slurry containing microcapsules 320 having electrophoretic particles 325 in a hydrocarbon solvent; this substrate may be a metallized release sheet with an adhesive. Figure 3B In this process, a microcapsule layer 320 is coated with a light-transmitting conductive material 330, such as indium tin oxide (ITO). Subsequently, in Figure 3C In this process, a barrier layer 340 is applied to the light-transmitting conductive material 330 to control the entry of moisture. The barrier layer 340 can be, for example, polyethylene or some other dielectric material. Next, in Figure 3D In the process, a polyurethane planarization layer 350 is applied to the barrier layer 340. Finally, a protective sheet 360 is applied to the stack to complete the electrophoretic display layer. After completion, the substrate 310 can be removed, and the remainder of the stack can be laminated to the electrode structure, such as the active matrix of pixel electrodes.

[0052] Available locations, such as Figures 4A to 4E As shown, a simple electrophoresis display can be produced. Figure 4A In this process, substrate 410 has been coated with a lower electrode layer 412 and a dielectric layer 415. The completed substrate / electrode / dielectric can be part of a larger object, or it can be an active matrix backplane or a segmented backplane. As before, substrate 410 is coated with a slurry containing microcapsules 420 having electrophoretic particles 425 in a hydrocarbon solvent. It is worth noting that in Figure 4AIn this layer, gaps exist between some of the microcapsules 420. Due to these gaps, when the microcapsules 420 are coated with a transparent conductive material 430 such as ITO, some of the ITO may short-circuit with the lower electrode 412, but the dielectric layer 415 prevents this short-circuit. For example, see... Figure 4B The circled area 405. After applying the light-transmitting conductive material 430, in Figure 3C In the process, a barrier layer 440 is applied to the light-transmitting conductive material 430. Next, in... Figure 4D In the process, a polyurethane planarization layer 450 is applied to the barrier layer 440. Finally, a protective sheet 460 is applied to the stack to complete the electrophoretic display. This display exhibits improved contrast for a given driving voltage because the local electric field is actually quite strong due to the lack of an adhesive layer between the electrodes.

[0053] In yet another implementation plan, such as Figure 5B As shown, a dielectric layer 528 can be formed on top of the microcapsule 520 to provide a moisture barrier, and in accordance with... Figure 5C This demonstrates how depositing the transparent conductive material 530 above the moisture barrier prevents short circuits. Additionally, as discussed in the embodiments, the intermediate dielectric layer improves the overall optical performance of the display by reducing recoil. Similar to... Figures 3A to 3E and Figures 4A to 4E ,exist Figures 5A-5F In this context, the stack-up may also include a substrate 510, microcapsules 520, electrophoretic pigments 525, a light-transmitting conductive material 530, a barrier layer 540, a planarization layer 550, and a protective sheet 560.

[0054] Spraying method

[0055] As already mentioned, the present invention can be constructed by spraying an electrophoretic medium into a substrate. The method includes forming a dispersion of the capsule in a liquid; feeding the dispersion through a first orifice; and feeding a continuous gas stream through a second annular orifice surrounding the first orifice, thereby forming a spray of the capsule. This spraying method has the advantage over slot coating in that spraying typically does not require the use of rheology modifiers in the liquid to be sprayed, resulting in a final coating free of such rheology modifiers, and therefore avoiding the influence that such rheology modifiers might have on the properties of the electrophoretic medium in slot coating. Generally, in spraying, only the additives actually needed in the final product need to be added to the liquid to be sprayed.

[0056] Figure 6This is a schematic cross-sectional view of a simple spray nozzle (generally designated 600) that can be used in the spraying method of the present invention. The nozzle 600 includes a generally cylindrical body 602 having a central axial bore 604 through which an electrophoretic capsule (not shown) dispersed in a liquid (not shown) is pumped. The central bore 604 is surrounded by an annular bore 606 through which a continuous flow of air is forcibly propelled. The lower end of the central bore 604 terminates at an orifice 608, and the lower end of the annular bore 606 terminates at an annular orifice 610 surrounding the orifice 608. A cylindrical baffle 612 surrounds the annular orifice 610. The baffle 612 restricts the airflow through the annular orifice 610, causing the dispersion of the capsule to pass through the orifice 608 to form a spray or jet 614.

[0057] The nozzle 600 is also provided with forming air holes 616, the number of which can be six or eight. For example... Figure 6 As shown, the outer portion of the nozzle 600 through which the hole 616 passes extends downward to below the orifices 608 and 610 and the baffle 612, and the lower part of the hole 616 directly downward and inward. The forming air is continuously and forcefully propelled through the hole 616, causing it to impact the jet 614, thereby opening the jet into a large spray 618, which in turn impacts the substrate 620 located below the nozzle 600.

[0058] The quality of the capsule coatings is evaluated based on their reproducible particle size, average coating weight, uniformity, and defect density. Defect density is quantified by the number of non-switching capsules per unit display area in a standard display structure, defined as a backplane with a 25 μm polyethylene terephthalate film sequentially coated with a 25 μm lamination adhesive layer, a 20 μm capsule layer, and a front substrate including an ITO layer. Preferably, the ratio of the atomizing air outlet cross-section to the capsule dispersion outlet cross-section is not greater than about 8.5, and preferably from about 5.0 to about 7.0. The capsule dispersion orifice diameter preferably ranges from about 1.0 to 1.40 mm. The capsule dispersion may contain capsules, preferably in a weight fraction of about 38.0 to about 40.5 wt%; the dispersion may optionally contain up to about 4.0 wt% 1-butanol and up to about 0.04 wt% surfactant such as Triton X 100.

[0059] In the spraying method of the present invention, many different capsule dispersion feed rates and atomizing air feed rates can be used. Generally, the capsule dispersion feed rate M FThe flow rate should be no less than about 30 g / min and no more than about 70 g / min, optimally determined primarily by the appropriate residence time in the atomization zone, which is, in other words, the area where the capsule dispersion column exiting the first orifice splits into fluid sheets, which then break into bands and finally droplets. Ideally, the droplet size distribution should result in an average number of capsules per droplet of less than about 5.0, with a standard deviation of less than about 3.0 capsules per droplet. The atomizing air feed rate is set based on the critical air velocity v* measured at the second orifice, typically on the order of about 100 m / sec. In a preferred method, a total air feed rate M of about 150 to 200 g / min is used in the absence of forming air. A (Including atomizing air and shaping air), and in the case of shaping air, a total air feed rate of up to 300 g / min M is used. A .

[0060] It has also been found that the quality and uniformity of the sprayed capsule coating are strongly affected by the substrate pretreatment and additives added to the capsule dispersion. Useful pretreatments and additives include, but are not limited to:

[0061] 1) Capsule dispersion containing surfactants such as Triton X-100 and butanol to improve the wetting of the substrate surface;

[0062] 2) Pre-coat the substrate surface with a sublayer containing surfactants such as Triton X-100, 1-butanol and other substances with detergent structures and optionally polyurethane latex.

[0063] 3) Pre-treat the substrate using atmospheric pressure plasma or corona discharge; and

[0064] 4) The capsule dispersion may contain a polymer binder, such as polyurethane latex.

[0065] As already mentioned, the spraying method of the present invention may include using a masking material covering portions of the substrate such that, after the masking material is removed, the capsules remain only on those portions of the substrate where the masking material was not present. The masking material used to cover portions of the substrate should not be porous, or at least should have a sufficiently low porosity to ensure that capsules do not deposit on the masked areas of the substrate. The masking material should not significantly absorb the liquid (typically aqueous) in which the capsules are dispersed, and should be placed close enough to the surface of the substrate that lateral drafting of the capsules from the unmasked areas to the masked areas of the substrate does not occur beneath the masking material. After the capsules have been deposited on the substrate, they may be dried (or otherwise treated to form an adhesive layer, e.g., by exposure to radiation) while the masking material is still in situ, or the masking material may be removed first, followed by drying or other treatment of the capsules. In both cases, the physical properties of the masking material and the capsule dispersion should be chosen such that, during the removal of the masking material, the capsule is not introduced into the previously masked area of ​​the substrate, nor is the capsule removed from the unmasked area (e.g., by irregularly tearing the dry adhesive layer of the capsule).

[0066] The masking film may include an adhesive pre-laminated onto the surface of the capsule to be deposited and a release film exposed to the spray. After capsule deposition, the release film is removed, followed by further processing. The resulting spray-printed film can then be laminated onto a backing plate, which may be transparent or opaque. Example

[0067] Example 1

[0068] like Figure 4A As shown, an encapsulation electrophoretic dielectric layer is prepared by slit-mold coating of a polyurethane slurry of collagen / arabino capsules with black and white charged electrophoretic media onto a PET-ITO substrate. Further details of the encapsulation method, slurry formation, and slit-mold coating method can be found in U.S. Patent No. 6,982,178. Prior to coating, a process is used... The edges of the substrate were masked with tape, thereby allowing for easy electrical connection when the method was completed. After applying a thermosetting adhesive, a 100 nm indium tin oxide (ITO) conformal coating was deposited onto the monolayer of the capsule using radio frequency sputtering (Semicore Equipment, Livermore, CA). During the sputtering process, the encapsulation electrophoretic dielectric layer was exposed to a vacuum of 8 mTorr for 1500 seconds.

[0069] and Figure 1CSimilarly, an electrophoretic display was formed by providing a potential between the sputtered ITO electrode and the ITO on the substrate. When viewed from the sputtered ITO side, the white state was measured to be 81±1L* and the dark state to be 45±1L* when driven at ±30V. Both the dark and white states exhibited a glossy finish, which is likely due to light scattering from the surfaces formed by depositing ITO onto the microcapsule surface.

[0070] Although the white and dark states of a simple PET-ITO-capsule-ITO stack are quite good, however... Figure 7 As shown, the self-erasing (also known as recoil) is found to be quite significant. Particularly after sustained drive to the white state, the recoil upon reversal to the dark state is on the order of approximately 15 L*, which is very noticeable to observers and generally unacceptable for commercial applications. (See [link to documentation]) Figure 7 (The dashed circle in the image). Although it was observed that recoil was smaller at higher temperatures, the total amount of recoil was still quite high.

[0071] Example 2

[0072] A second sample was prepared as in Example 1, but the second sample additionally included a polyurethane planarization layer on top of the sputtered 100 nm ITO, and a matte PET film was laminated on top of the planarization layer for additional protection. The white state of the second sample remained almost identical, while the dark state decreased by 36% to 29 L*.

[0073] Table 1. Reflection electro-optic measurements of samples driven at ±30V.

[0074]

[0075] It is highly likely that the improved dark state achieved by the planarization layer and the matte PET film is an illusion created by the measurement technique. Because sputtered ITO is very smooth, it reflects a significant amount of incident light even when the electrophoretic medium has been driven into the dark state. Once a matte PET top protector is added, as is typical for most electrophoretic displays, there is less back reflection, and the measured L* of the dark state decreases.

[0076] Example 3

[0077] Another variation of Example 1 is produced, which includes a thin (10 nm thick) SiO2 layer deposited directly on top of the slit-coated microcapsule via radio frequency sputtering, followed by a 100 nm indium tin oxide (ITO) layer also deposited using radio frequency sputtering. The resulting component is similar to that described above. Figure 5C resemblance.

[0078] like Figure 8 As shown, especially at higher temperatures, the addition of an intermediate dielectric layer significantly improves the measured recoil. Recoil itself manifests as optical self-erasure; when an electro-optic display is driven from one extreme optical state to the opposite extreme optical state by applying a driving pulse, and then maintained for a short period without an electric field applied to the electro-optic medium, the electro-optic medium retracts from its driven optical state back towards the one extreme optical state. See, for example... Figure 7 It is worth noting that, as Figure 8 As shown, in the case of a fairly thin dielectric layer between the microcapsule and the conductive ITO layer, the recoil is about half the size.

[0079] Besides reducing the observed recoil, compared to directly sputtering ITO onto the capsule, adding an intermediate SiO2 layer only slightly reduced the overall contrast (ΔL*) between the white and black states compared to a stack of ITO directly sputtered onto the capsule. Figure 9 As shown, the overall contrast of the capsule-dielectric-ITO stack is relatively flat between the white and black states, and exhibits reduced recoil over the entire operating temperature range, with particularly good performance at 0°C to 35°C, i.e., under typical outdoor operating conditions. Therefore, it appears that adding a thin dielectric layer between the capsule layer and the upper sputtered conductor can bring the overall electrophoretic dielectric performance to specifications suitable for outdoor marking.

[0080] Example 4

[0081] By combining capsule spraying with ITO sputtering, very thin (~25 μm) e-reader stacks are produced. For example... Figures 10A to 10C As shown, a standard 6" thin-film transistor (TFT) substrate 710 (Innolux Corporation) was cleaned with isopropyl alcohol and dried. The substrate 710 includes 1448 × 1072 electrodes and an image controller bonded to the substrate. Using the above technique, a single-layer electrophoretic display capsule 720 containing black and white pigments with opposite charges was directly sprayed onto the pixel electrodes of the backplane. Next, under reduced ambient pressure, approximately 100 nm of ITO 740 was directly deposited on top of the sprayed capsule to form the upper transparent electrode 750. Then, a top-plane connection (TPC) was formed between the upper-plane driving electrode and the upper transparent electrode 750 on the substrate 710 using fine silver wires 780, thereby providing the driver chip with a reference voltage for the upper transparent electrode 750. A flexible connector (not shown) Figures 10A to 10CThe display (in the middle) provides an interface between the back panel and the commercial e-reader controller (Freescale Electronics). Without additional coatings or modifications to the driving electronics, the assembled display is able to show clear text and easily switch between pages. (However, recoil is noticeable with each page turn). The resulting display operated for several weeks before showing the non-switching area, likely due to shrinkage of the capsule layer caused by drying and subsequent cracking of the ITO layer, which reduced the electrical integrity of the upper transparent electrode 750.

[0082] Therefore, as described herein, it is evident that the electro-optic properties of standard encapsulated electrophoretic media can be improved by directly coating the capsule with a thin film of a transparent conductive material. Furthermore, if the capsule is applied, for example, by spraying or dip coating, lamination equipment is unnecessary to construct the electrophoretic display. Moreover, this technique can be used to produce electrophoretic displays with complex shapes if a thin, transparent electrode layer can be uniformly applied to the surface.

[0083] It will be apparent to those skilled in the art that many changes and modifications can be made to the specific embodiments of the invention described above without departing from the scope of the invention. Therefore, the entire foregoing description is to be interpreted in an illustrative rather than restrictive sense.

Claims

1. An electrophoretic display layer, comprising: First substrate; A capsule layer containing an electrophoretic medium, the capsule layer having a flat surface and a wavy surface; and A light-transparent conductive material layer is deposited directly on the wave surface of multiple capsules under a pressure less than atmospheric pressure, wherein the capsule layer is disposed between the first substrate and the light-transparent conductive material layer.

2. An electrophoretic display layer, comprising: First substrate; A capsule layer containing an electrophoretic medium, the capsule layer having a flat surface and a wavy surface; A first vapor-deposited dielectric material layer is directly deposited on the wave surface of multiple capsules under a pressure less than atmospheric pressure, wherein the capsule layer is disposed between the first substrate and the first vapor-deposited dielectric material layer; and A transparent conductive material layer is in direct contact with the first vapor-deposited dielectric material layer. The thickness of the first vapor-deposited dielectric material layer is less than 0.5 μm, and the size of the plurality of cysts is 30-50 μm.

3. The electrophoretic display layer of claim 1 or 2, wherein, The electrophoretic medium contains at least one type of charged particles that move within the capsule in response to an applied electric field.

4. The electrophoretic display layer of claim 1 or 2, wherein, The capsule layer further comprises a polyurethane adhesive between at least some of the capsules within the capsule layer.

5. The electrophoretic display layer according to claim 1 or 2, wherein, The first substrate is a release sheet.

6. The electrophoretic display layer of claim 5, further comprising an adhesive layer between the first substrate and the capsule layer.

7. The electrophoretic display layer according to claim 1 or 2, further comprising a planarization layer disposed on the light-transmitting conductive material layer.

8. The electrophoretic display layer of claim 7, further comprising a second substrate disposed on the planarization layer, such that the planarization layer is disposed between the light-transmitting conductive material layer and the second substrate.

9. The electrophoretic display layer according to claim 8, wherein, The second substrate is basically planar.

10. The electrophoretic display layer according to claim 2, wherein, The first vapor-deposited dielectric material layer comprises Si3N4, SiO2, Al2O3, HFO2, ZrO2, or a polymer.

11. An electrophoretic display comprising the electrophoretic display layer as described in claim 1 or 2, wherein, A second conductive material layer is disposed between the first substrate and the encapsulation layer containing the electrophoretic medium.

12. The electrophoretic display of claim 11, further comprising a second dielectric material layer disposed between the second conductive material layer and the capsule layer.

13. The electrophoretic display of claim 12, wherein, The second dielectric material layer comprises Si3N4, SiO2, Al2O3, HFO2, ZrO2, or a polymer.

14. The electrophoretic display of claim 11, wherein, The light-transmitting and conductive material contains indium tin oxide or zinc oxide.

15. The electrophoretic display of claim 11, wherein, The first substrate is substantially planar.

16. The electrophoretic display of claim 11, wherein, The first substrate is non-planar overall but partially planar.

17. A method for manufacturing an electrophoretic display layer, comprising: Provide a first substrate; A capsule containing an electrophoretic medium is deposited on the first substrate, thereby forming a wavy surface of the capsule on the surface of the capsule opposite to the first substrate; and A transparent and conductive material layer is directly deposited onto the waveform surface of the capsule layer under a pressure less than atmospheric pressure.

18. The method of claim 17, wherein, The deposition of the transparent conductive material layer was carried out under a vacuum pressure of less than 133 Pascals (1 Torr).

19. The method of claim 18, wherein, The deposition of the transparent conductive material layer was carried out under a vacuum pressure of less than 13 Pascals (100 millitors).

20. The method of claim 18, wherein, The deposition was accomplished using a chemical vapor deposition method.

21. The method of claim 20, wherein, Indium tin oxide or zinc oxide is deposited as the light-transmitting conductive material layer.

22. The method of claim 17, further comprising depositing a first dielectric layer on the substrate, and then depositing the encapsulation layer comprising an electrophoretic medium.

23. The method of claim 22, wherein, The first dielectric layer comprises Si3N4, SiO2, Al2O3, HFO2, ZrO2, or a polymer.

24. The method of claim 17, further comprising vapor-depositing a second dielectric layer on the wavy surface of the capsule containing the electrophoretic medium, and then depositing the light-transmitting conductive material layer over the second dielectric layer and on the wavy surface of the capsule.

25. The method of claim 17, wherein, The first substrate is substantially planar.

26. The method of claim 17, wherein, The first substrate is non-planar overall but partially planar.

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