Electrophoretic or electromagnetophoretic display device with several layers of display cells, and manufacturing method

a) Field of invention The present application relates to electrophoretic displays having improved contrast ratio, switching performance, reflectance (or reflectivity) in the Dmin state, and structural integrity, and methods of manufacturing the same.

b) Explanation of related technologies An electrophoretic display is a non-emissive device based on the electrophoretic phenomenon of charged dye particles suspended in a solvent. This was first proposed in 1969. The display usually comprises two plates with electrodes facing each other and spaced apart by spacers. One electrode is usually transparent. A suspension consisting of a colored (or colored) solvent and charged dye particles is encapsulated between the two electrodes. When a voltage difference is applied between the two electrodes, the dye particles move to one side, and depending on the polarity of the voltage difference, either the color of the dye particles or the color of the solvent can be seen.

It has been proposed to provide a partition (or partition) between the two electrodes to divide the space into smaller cells to prevent unwanted movement of the particles, eg sedimentation (MA Hopper and V. Novotny, Eye). E.E.E.E.Electr. Dev., Vol. 26, No. 8, pp. 1148-1152 (1979)). However, in the case of partition-type electrophoresis displays, the process of partition formation and suspension encapsulation has been difficult. Furthermore, it has also been difficult to keep suspensions of different colors separated from each other in a partitioned electrophoresis display.

Another type of EPD (see US Pat. No. 3,612,758) has an electrophoretic cell formed from parallel linear reservoirs (channel or groove type). Filling and sealing of the electrophoretic fluid channels is performed in a batch process. In addition, the problem of undesired movement or sedimentation of particles, especially in the length (or longitude) direction, remains a challenge.

Attempts were then made to enclose the suspension in microcapsules. US Pat. Nos. 5,961,804, 5,930,026 and 6,017,584 describe microencapsulated electrophoresis displays. The display of this reference is a substantially two-dimensional arrangement (or arrangement) of microcapsules, each of which has an electrophoretic composition of a dielectric solvent and a suspension of charged dye particles that visually contrasts with it. Has. Microcapsules can be formed by interfacial polymerization, in-situ polymerization or other known methods such as physical processes, in-liquid curing or simple / complex coacervation. After formation, the microcapsules may be injected into cells containing two separate electrodes, or "printed" or coated on a transparent conductor film. The microcapsules may also be immobilized in a transparent matrix or binder sandwiched between the two electrodes.

These methods, in particular electrophoretic displays made by microencapsulation methods as disclosed in US Pat. Nos. 5,961,804, 5,930,026 and 6,017,584, have many drawbacks. For example, electrophoretic displays made by the microencapsulation method are sensitive to changes in the environment (especially to humidity and temperature) due to the chemistry of the walls of the microcapsules. Second, electrophoretic displays based on microcapsules have poor scratch resistance due to the thin walls of the microcapsules and the large particle size. Embedding microcapsules in a large amount of polymer matrix for better display handling results in slower response times due to greater distance between the two electrodes and lower dye particle fill (or payload). The contrast ratio becomes smaller. It is also difficult to increase the surface charge density of the dye particles because the charge control agent tends to diffuse to the water / oil interface during the microencapsulation process. The low charge density or zeta potential of the dye particles in the microcapsules is also a factor in slowing the response rate. In addition, due to the large particle size of the microcapsules and the wide size distribution, this type of electrophoresis display lacks addressability and resolution when applying color.

Recently improved EPD technology has been filed on March 3, 2000, a co-pending application, US Application 09 / 518,488 (corresponding to International Publication No. 01/67170), June 28, 2000. US application 09 / 606,654 filed (corresponding to international publication 02/01280) and US application 09 / 784,972 filed February 15, 2001 (corresponding to international publication 02/65215) Disclosed in. All of these are incorporated herein by reference in their entirety. The improved EPD includes isolated cells, which are formed from microcups with properly defined shapes, dimensions and aspect ratios and are dielectric solvents or solvent mixtures (preferably fluorinated solvents or solvent mixtures). It is filled with charged dye particles or dye-containing microparticles dispersed therein. Filled cells are individually sealed with a polymer encapsulating layer, which is preferably formed from a composition comprising a material selected from the group consisting of thermoplastics, thermoplastic elastomers, thermosettings and precursors thereof. It has been stopped.

The microcup construction is flexible to the format and enables an efficient roll-to-roll continuous process for manufacturing EPDs. The display can be made on a continuous web of conductor film such as ITO / PET, which can be, for example, (1) coated with a radiation curable composition on ITO / PET film and (2) microembossed or A microcup structure is formed by the photolithography method, (3) the electrophoretic fluid is filled in the microcup, and the filled microcup is sealed, and (4) another conductor film is laminated on the sealed microcup. And (5) by slicing or cutting the display to the desired dimensions or format for assembly.

One advantage of this type of EPD is that the microcup wall is effectively a built-in (or built-in) spacer that keeps the top and bottom substrates separated by a certain distance. The mechanical properties and structural integrity of microcup displays are significantly superior to any conventionally known display, including those manufactured with spacer particles. In addition, displays containing microcups have desirable mechanical properties, including reliable display performance when the display is bent, rolled, or under compressive pressure, such as when applied to a touch screen. Also, the edge seal adhesive, which limits and predetermines the dimensions of the display panel and limits the display fluid within a predetermined area, becomes unnecessary by using the microcup technology. The display fluid in a conventional display manufactured by the edge seal bonding method leaks completely when the display is cut or punctured by something. Damaged displays no longer work. On the other hand, the display fluid in the display manufactured by the microcup technology is sealed and isolated in each cell. The microcup display can be cut to almost any size without the risk of loss of display fluid in the active region, which can compromise display performance. In other words, this microcup structure provides a format-flexible display manufacturing method that allows continuous production of displays in large area sheet formats that can be cut into any desired format. An isolated microcup or cell structure is particularly important when the cell is filled with fluids that differ in certain properties, such as color and switching speed. Without the microcup structure, it would be extremely difficult to prevent fluids in adjacent regions from mixing with each other or crosstalk during operation.

To obtain a higher contrast ratio, one of the following two techniques is adopted: (1) using a dark background to reduce light leaking through the inactive partition wall, or (2) Use microcups with wider openings and narrower partitions to increase filling (or payload). However, dark backgrounds usually result in reduced reflectance in the Dmin state. On the other hand, display cells formed from wider microcups and narrower partition walls are less capable of withstanding the compressive and / or shear forces exerted by, for example, pointed pens for touch screen panels.

Abstract of the invention

The present application is directed to a novel multilayer EPD structure that exhibits improved contrast ratio, switching performance, reflectance in the Dmin state, and structural integrity. In this type of multilayer EPD structure, shallower microcups can be used to improve reflectance in the Dmin state while obtaining an acceptable contrast ratio. As a result, the manufacturing cost is significantly reduced, and the release (or mold release) characteristics during microembossing are also significantly improved.

The first gist of the present invention is directed to an electrophoretic display having two or more stacked display cell layers. The display cell is filled with an electrophoretic display fluid and individually sealed (or sealed).

A second gist of the present invention is directed to an electrophoretic display with two or more stacked display cell layers, which cells are filled with electrophoretic fluids having different colors, optical densities or switching speeds. To.

A third gist of the present invention is directed to an electrophoretic display with two or more stacked display cell layers, the cells having different shapes, dimensions (or sizes) or openings for the entire area. Have a ratio.<u style="single">In this gist, one display cell layer may contain cells with different shapes or dimensions (or sizes), or one layer may have an opening for a different shape, size or total area than cells in another layer. It may include cells having a part ratio.</u>

A fourth gist of the present invention is directed to an electrophoretic display having two or more stacked display cell layers, in which one layer is inactive (or stacked) in this stack (or stack). The partition region (which does not contribute to image formation) overlaps at least partially, preferably completely, with the active (or image-forming) cell region of the layer above or below it. the term"<u style="single">Stagger (type)</u>(staggere<u style="single">d)</u>Is used to explain this arrangement throughout the present application. In order for the color (caused by the reflection or absorption of light) from the cells in the lower layer to be visible through the partition area of the upper layer<u style="single">Stagger type</u>Placement is required.

A fifth gist of the present invention is directed to an electrophoretic display having two or more stacked display cell layers, in which the bottom layer is white dispersed in a black solvent or solvent mixture. Includes cells filled with an electrophoretic fluid containing the dye particles or dye-containing microparticles of.

A sixth gist of the present invention is directed to a full-color or multi-color electrophoretic display with two stacked display cell layers, with the top layer dispersed in a red, green or blue solvent or solvent mixture, respectively. Includes red, green or blue cells filled with an electrophoretic display fluid containing white dye particles or dye-containing microparticles.

A seventh gist of the present invention is directed to a full-color or multi-color electrophoretic display with two stacked display cell layers, the bottom layer being white dye particles dispersed in a black solvent or solvent mixture. Alternatively, it contains a black cell filled with an electrophoretic fluid containing dye-containing microparticles, and the black cell is the inactive partition region of the upper layer.<u style="single">With a staggered type that at least partially overlaps with</u>Have been placed.

The eighth gist of the present invention is directed to a full-color or multi-color electrophoretic display having two stacked display cell layers. The bottom layer contains red, green, blue and black cells filled with an electrophoretic display fluid containing white dye particles or dye-containing microparticles dispersed in a red, green, blue and black solvent or solvent mixture, respectively. .. The upper layer contains red, green and blue cells filled with an electrophoretic display fluid containing white dye particles or dye-containing microparticles dispersed in a red, green and blue solvent or solvent mixture, respectively. The two layers of colored (or colored) cells and inactive dividers are the bottom layer of black cells and the top layer of inactive dividers.<u style="single">With a staggered type that at least partially overlaps with</u>Be placed.

The dye particles or the dye-containing microparticles may be magnetic (or magnetic).

A ninth gist of the present invention is directed to an electromagnetophoretic display having two or more stacked display cell layers. The bottom layer contains a display cell filled with an electromagnetic running fluid containing a mixture of black magnetic particles and white non-magnetic particles dispersed in a clear, colorless solvent or solvent mixture. The upper layer may contain red, green and blue cells filled with an electrophoretic fluid containing white particles dispersed in a red, green and blue solvent or solvent mixture, respectively. Alternatively, the top layer may include a display cell filled with an electrophoretic fluid containing a mixture of white particles and colored particles dispersed in a clear, colorless solvent or solvent mixture.

The tenth gist of the present invention directed a method for producing an electrophoretic display having two or more stacked display cell layers as described in the first to ninth gist of the present invention. It is a thing.

The term "display cell" is used herein, but the term is a partition type display cell, a microgroove or microchannel type display cell (US Pat. No. 3,612,758), a microcapsule type display cell (US Pat. No. 5,961,804, the same). It is understood to broadly include display cells manufactured by microcup technology as described in Nos. 5,930,026 and 6,017,584) and WO 01/67170.

When the term "microcup" is used herein, the multilayer display of the present invention may also apply to other display cells such as partitioned display cells, microgrooves or microchannel display cells and microcapsule display cells. Understood.

In a multi-layer EPD, the top (or top) layer is usually the viewing side, while the bottom (or bottom) layer is the non-display side.

Detailed description of the invention

<u style="single">Definition</u> Unless otherwise noted herein, all technical terms are used herein based on conventional definitions, as they are commonly used and understood by those skilled in the art. To do. The term "microcup" refers to a cup-shaped depression (or indentation) formed by micro-embossing or imagewise exposure. When the term "well-defined" is used to describe a microcup or cell, the microcup or cell has a well-defined shape, dimension and aspect ratio that are predetermined based on specific parameters of the manufacturing process. Is intended to mean having. The term "aspect ratio" is a commonly known term in the field of electrophoretic displays. In the present application, it is the depth-to-width ratio or the depth-to-length ratio (or the ratio of the depth to the length or the depth to the width) of the cell. The term "Dmax" refers to the maximum achievable optical density of a display. The term "Dmin" refers to the minimum optical density of the display background (or background). The term "contrast ratio" is defined as the ratio of the% reflectance of the display in the Dmin state to the% reflectance of the electrophoretic display in the Dmax state.

I.<u style="single">Preferred embodiment</u> Electrophoretic display made by microcup technology<u style="single">Lee</u>, At least one (10) was housed between two transparent conductor films (10, 11) and the two conductor films, as shown in FIG.<u style="single">display</u>Includes layer of cell (12). The cell is filled with charged dye particles or dye-containing microparticles dispersed in a colored dielectric solvent and sealed with a sealing layer (13). Although not shown in FIG. 1, it is preferred that the sealing layer extends over the partition wall (16) and forms a contiguous layer on top of it. Sealed<u style="single">display</u>cell<u style="single">layer</u>It is laminated by an adhesive layer (14) to the second conductor film (10), optionally (or superimposed is). When a voltage difference is applied between the two conductor films, the charged particles move to one side, which allows either the dye color or the solvent color to be seen through the transparent conductor film (10). In addition, at least one of the two conductor films is patterned. To improve the contrast ratio of EPD, one of the following two methods is commonly adopted: (a) Larger fill (or payload) (higher aspect ratio and / or relative to total area) Use a microcup (with a larger opening area ratio), or (b) use a dark conductor film (11) on the non-display side. Since there are no light-scattering particles in the inactive partition region (16), the observer sees the background color through the partition region in both the "on" and "off" states. The dark background of such a single layer EPD provides higher Dmax and contrast ratio, but lower reflectance in the Dmin state. On the other hand, it is not only more difficult to use a cell with a large filling amount, but also the manufacturing cost is increased.

The trade-off between the contrast ratio and the reflectance in the Dmin state is shown in Figures 2a and 2b.<u style="single">Staga</u>This is solved with the type two-layer structure. In these two figures, the display has an upper cell layer (21) and a lower cell layer (22). The two-layer cells are individually sealed with a sealing layer (23). Two layers<u style="single">With stagger type</u>Arranged, the sealing sides of the two layers face each other. The two-layer structure is sandwiched between the top transparent conductor film (24) and the bottom conductor film (25).

In the "on" state (Figure 2a), the white particles in both the upper and lower layers are attracted to the top of the cell (towards the display side). The partition region (26) of the upper layer appears to be "white" because the light is reflected back by the particles in the lower layer. In contrast, in the "off" state (Figure 2b), the white particles in both layers are attracted to the bottom of the cell (towards the non-display side). Since the light is absorbed by the colored dielectric solvent in the lower layer, the partition region of the upper layer appears to be "colored (or colored)". As a result, the Dmax and contrast ratio of the display can be improved without sacrificing reflectance in the Dmin state.

Also, dual-layer or multi-layer EPDs have smaller fills (smaller aspect ratios and smaller ratio of opening area to total area) in order to achieve a high contrast ratio with high reflectance in the Dmin state. A cell can also be used. This also significantly improves the release characteristics of the micro-embossing process and reduces the cost and difficulty of manufacturing molds for micro-embossing.

<u style="single">Making micro cups</u> A display cell based on a microcup is a co-pending patent application filed on March 3, 2000, either by microembossing, photolithography, or pre-drilled (or pre-punched) holes. No. 09 / 518,488 (corresponding to International Publication No. 01/67170), US Application No. 09 / 942,532 filed on August 29, 2002 (US Application Publication No. 2002-75556 published on June 20, 2002) No.), US Application No. 09 / 606,654 filed on June 28, 2000 (corresponding to International Publication No. 02/01280), and US Application No. 09 / 784,972 filed on February 15, 2001. It can be prepared as described in (Compatible with International Publication No. 02/65215). All of these are incorporated herein by reference in their entirety.

In general, cells based on microcups may have any shape and may vary in size and shape. The cells may have substantially uniform dimensions and shapes in one system. However, in order to maximize the optical effect, cells with a mixture of different shapes and dimensions may be manufactured. For example, a cell filled with a red dispersion may have a different shape or size than a green cell or a blue cell. In addition, a pixel may consist of a different number of cells of different colors. For example, a pixel may consist of some small green cells, some large red cells and some small blue cells. The three colors do not have to have the same shape and number.

The opening of the microcup may be circular (or round), square, rectangular, hexagonal or any other shape. The partition area between the openings is preferably kept small to achieve high saturation and contrast ratio while maintaining the desired mechanical properties. Therefore, a honeycomb-shaped opening is preferable to, for example, a circular opening.

For reflective electrophoresis displays, each microcup has a size of about 10²~ About 10⁶μm², Preferably about 10³~ About 10⁵μm²Can be within the range of. The depth of the microcup is in the range of about 3 to about 100 microns, preferably about 10 to about 50 microns. The ratio of the opening area to the total area is in the range of about 0.1 to about 0.95, preferably about 0.4 to about 0.90. The width of the partition between the microcups is in the range of about 2 to about 50 microns, preferably about 5 to about 20 microns.

II.<u style="single">Preparation of electrophoretic fluid</u> Electrophoretic display fluids are known in the art (eg, US Pat. Nos. 6,017,584, 5,914,806, 5,573,711, 5,403,518, 5,380,362, 4,680,103, 4,285,801, 4,093,534, 4,071,430 , No. 3,668,106 and IEEE Trans. Electron Devices, ED-24, p. 827 (1977) and the Journal of Applied Physics (J. Appl.). It can also be prepared by (Phys.) 49 (9), p. 4820 (1978)). The charged dye particles visually contrast with the medium in which the particles are suspended. This medium is a dielectric solvent and preferably has a small viscosity and a dielectric constant in the range of about 2 to about 30, preferably about 2 to about 15, due to the high mobility of the particles. Examples of suitable dielectric solvents include: hydrocarbons such as decahydronaphthalene (DECALIN), 5-ethylidene-2-norbornene, fatty oils, paraffin oils; aromatic hydrocarbons such as Toluene, xylene, phenylxysilyl ethane, dodecylbenzene and alkylnaphthalen; halogenating solvents such as perfluorodecalin, perfluorotoluene, perfluoroxylene, dichlorobenzotrifluoride, 3,4,5-trichlorobenzotrifluoride, chloropenta Fluoro-benzene, dichlorononane, pentachlorobenzene, and perfluorosolvents such as FC-43, FC-70 and FC-5060 (3M (3M)) Company, St. Paul, Minnesota); Low molecular weight halogen-containing polymers such as poly (perfluoropropylene oxide) (TCI America, Portland, Oregon), poly (chlorotrifluoroethylene), For example, Halocarbon Oils (Halocarbon Product Corp., River Edge, New Jersey), perfluoropolyalkyl ethers, such as Garden (Solvay Solexis). Or Krytox Oils and Greases K-Fluid Series (DuPont, Delaware). In one preferred embodiment, poly (chlorotrifluoroethylene) is used as the dielectric solvent. In another preferred embodiment, poly (perfluoropropylene oxide) is used as the dielectric solvent.

The suspension medium can be colored with a dye or dye (pigment). Nonionic azo and anthraquinone dyes are particularly favorable. Examples of favorable dyes include, but are not limited to: Oil Red EGN, Sudan Red, Sudan Blue, Oil. -Blue (Oil Blue), Macrolex Blue (Macrolex Blue), Solvent Blue (Solvent Blue) 35, Pylam Spirit Black (Pylam Spirit Black) and Fast Spirit Black (Pyram Products) (Pylam Products Co., Arizona), Sudan Black B (Aldrich), Thermoplastic Black X-70 (BASF), Anthraquinone Blue (anthraquinone blue), anthraquinone yellow (anthraquinone) yellow 114, anthraquinone red 111, 135, anthraquinone green 28 (made by Aldrich). In the case of insoluble dyes, the dye particles that provide the color of the medium may be dispersed in the dielectric medium. It is preferable that these colored particles are not charged. When the dye particles that give rise to color in the medium are charged, they preferably have a charge opposite to that of the charged dye particles. If both types of dye particles carry the same charge, they need to have different charge densities or different electrophoretic mobilities. In any case, the dye or dye that gives rise to the color of the medium must be chemically stable and compatible (or compatible) with the other components in the suspension.

The charged dye particles may be organic or inorganic dyes, for example TiO₂, Phthalocyanine blue, phthalocyanine green, diarylide yellow, diarylide AAOT yellow, and quinacridone, azo, rhodamine , Perylene pigment series (made by Sun Chemical), Hansa yellow G particles (made by Kanto Chemical), and carbon lamp black (Fisher) ) May be. Submicron particle size is preferred. The particles must have acceptable optical properties, must not be swollen or softened by a dielectric solvent, and must be chemically stable. Also, the resulting suspension needs to be stable against sedimentation, creaming or agglomeration under normal conditions of use.

The dye particles may originally exhibit an electric charge, may be charged so as to be manifested with a charge control agent, or may be charged when suspended in a dielectric solvent. Suitable charge control agents are well known in the art and may be essentially polymeric, non-polymeric, ionic or non-ionic. , Including the following ionic surfactants: Aerosol OT, sodium dodecylbenzene sulfonate, metal soap, polybutene succinimide, maleic anhydride copolymer, vinylpyridine copolymer, vinylpyrrolidone copolymer (eg Ganex, International Specialty Products (International Specialty Products))), (meth) acrylic acid copolymer, or N, N-dimethylaminoethyl (meth) acrylate copolymer. Fluorosurfactants are particularly convenient as charge control agents in perfluorocarbon solvents. These include FC fluorosurfactants such as FC-170C, FC-171, FC-176, FC430, FC431 and FC-740 (3M) and Zonyl fluorosurfactants such as Zonyl FSA, FSE, FSN. , FSN-100, FSO, FSO-100, FSD and UR (manufactured by DuPont) are included.

Suitable charged dye dispersions may be produced by any of the well-known methods, such as grinding, milling, friction, microfluidizing and ultrasound. Includes technology that utilizes. For example, the dye particles in the form of fine powder are added to the suspension solvent and the resulting mixture is ground or abraded in a ball mill for several hours to crush the highly aggregated dry dye powder into primary particles. Less preferred, dyes or dyes that add color to the suspension medium may be added to the suspension during the ball milling process.

Precipitation or creaming of the dye particles can be eliminated by microencapsulating the particles with a polymer suitable for adapting the specific gravity to the dielectric solvent. Microencapsulation of dye particles can be done chemically or physically. Typical microencapsulation methods include interfacial polymerization, in-situ polymerization, phase separation, core selvation, electrostatic coating, spray drying, fluidized bed coating and solvent evaporation.

Density-adapted dye-containing microparticles are co-pending the United States<u style="single">Special</u>US application No. 10 / 335,210 (corresponding to International Publication No. 03/58335) filed on December 31, 2002, which is a license application, and US application No. 10 / 335,051 filed on December 31, 2002. Issue (international release<u style="single">No.</u>Corresponds to 03/57360), US Application No. 10 / 632,171 filed on July 30, 2003, and US Application No. 10 / 364,270 filed on February 10, 2003 (International Publication).<u style="single">No.</u>It can be manufactured by the method described in (corresponding to 03/69403). All of these contents are incorporated herein by reference in their entirety.

For black / white electrophoresis displays, the suspension is titanium oxide (TiO) dispersed in a blackened dielectric solvent containing a black dye or dye mixture or charged black particles.₂) Contains charged white particles. Black dyes or dye mixtures such as Pilum Spirit Black and Fast Spirit Black (Pilum Products (Arizona)), Sudan Black B (Aldrich), Thermoplastic Black X-70 (Basuf) Alternatively, an insoluble black dye, such as carbon black, can be used to develop the black color of the solvent. For other colored suspensions, there are many possibilities. In the case of subtractive color mixing, charged TiO₂Particles or TiO₂The containing particles may be suspended in a cyan, yellow or magenta dielectric solvent. Cyan, yellow or magenta colors can be expressed by using dyes or dyes. In the case of additive color mixing, charged TiO₂Particles or TiO₂The containing particles may be suspended in a red, green or blue dielectric solvent similarly developed by using a dye or dye. Red, green and blue are preferred for most applications.

III.<u style="single">Microcup sealing</u> Cells based on Microcups include WO 01/67170 and US application 09 / 874,391 (corresponding to WO 02/98977), which is a co-pending US application filed on June 4, 2001. US Application No. 10 / 618,257 filed on July 10, 2003, US Application No. 10 / 665,898 filed on September 18, 2003, US Application No. 10 filed on August 29, 2003. The electrophoretic fluid can be filled and sealed as described in / 651,540. All of these contents are incorporated herein by reference in their entirety. Sealing (or sealing) of microcups can be performed by many methods. For example, the filled microcup is overcoated with a sealing composition containing a solvent and a sealing material.<u style="single">To do</u>This encapsulating material can be implemented by thermoplastic elastomer, polyurethane, polyvalent acrylate or methacrylate, cyanoacrylate, polyvalent vinyl (including vinylbenzene, vinylsilane, vinyl ether), polyhydric epoxide, polyhydric isocyanate, polyvalent allyl. , And selected from the group consisting of oligomers or polymers containing crosslinkable functional groups. Compositions containing additives such as polymeric binders or thickeners (or thickeners), photoinitiators, catalysts, fillers, colorants or surfactants to improve the physical and optical properties of the display. May be added to. The encapsulating composition is inherently incompatible (or incompatible) with the electrophoretic fluid and has a lower specific gravity than the electrophoretic fluid. Upon solvent evaporation, the encapsulating composition forms a conform seamless encapsulation on top of the filled microcup. The sealing layer may be further cured by heat, radiation, electron (e) beam, moisture, interfacial cross-linking or other curing methods. Interfacial polymerization and subsequent UV curing are very advantageous for sealing methods. Mixing between the electrophoresis layer and the overcoat is significantly suppressed by the formation of a thin barrier layer at the interface by interfacial polymerization. The sealing is then completed by a post-curing step (preferably by UV irradiation). It is highly desirable that the specific gravity of the overcoat is significantly smaller than the specific gravity of the electrophoretic fluid in order to further reduce the degree of mixing. Volatile organic solvents can be used to adjust the viscosity and thickness of the coating. When a volatile solvent is used for overcoating, the volatile solvent is preferably immiscible with the dielectric solvent. This two-pass overcoat process is particularly advantageous if the dye used is at least partially dissolved in the encapsulation composition.

Sealing with a composition comprising a thermoplastic elastomer or polyurethane copolymer is particularly preferred. Examples of thermoplastic elastomers include styrene and isoprene, butadiene or ethylene / butylene triblock or diblock copolymers, such as the Kraton D and G series (Kraton Polymer Company). Is done. Crystalline rubbers such as poly (ethylene-co-propylene-co-5-methylene-2-norbornene) and other EPDMs (ethylene propylene diene rubber terpolymers) (made by Exxon Mobil) are also extremely convenient. I found out.

Alternatively, the sealing composition is dispersed in an electrophoretic fluid, for example with an in-line mixer, and micron by a precision coating mechanism, such as Myrad bar, gravure printing, doctor blades, slot coatings or slit coatings. Immediately coat on the cup. Volatile organic solvents can be used to control the viscosity and coverage of the electrophoretic fluid. Excess fluid may be scraped off with a wiper blade or similar device. A small amount of a weak solvent or solvent mixture, such as isopropanol, methanol or an aqueous solution thereof, may be used to remove the electrophoretic fluid remaining on the top surface of the partition wall of the microcup. The sealing composition is essentially incompatible with the electrophoretic fluid and is lighter than the electrophoretic fluid. Upon phase separation and solvent evaporation, the encapsulating composition floats on top of the filled microcup, forming a seamless encapsulating layer on it. The sealing layer may be further cured by heat, radiation or other curing method. This is the one-pass sealing process.

In both of these two sealing processes, the polymer sealing layer<u style="single">Electrophoresis</u>Contact the top surface of the fluid. The sealing layer is<u style="single">Electrophoresis</u>The fluid is sealed in each cell and adheres to the surface of the partition wall in a sealing manner (or sealing manner). Finally, the sealed microcup is laminated with a second conductor film (10), which is optionally pre-coated with an adhesive layer (14).

A preferred group of dielectric solvents that exhibit the desired density and solubility differences for the most commonly used polymers and their precursors are halogenated (particularly fluorinated) hydrocarbons and their derivatives. Surfactants can be used to improve wetting and adhesion at the interface between the electrophoretic fluid and the sealing composition. Useful surfactants include FC surfactants (3M), zonylfluorosurfactants (DuPont), fluoroacrylates, fluoromethacrylates, fluorine-substituted long-chain alcohols, perfluoro-substituted long-chain carboxylic acids and their derivatives. included.

IV.<u style="single">Fabrication of single-layer electrophoresis display panel</u> This process can be a continuous roll-to-roll process as described in WO 01/67170. This may include the following steps: 1. Coat a layer of precursor of thermoplastic or thermosetting product containing solvent as appropriate on the conductor film. The solvent evaporates easily if present. 2. The precursor layer of the thermoplastic or thermosetting is embossed at a temperature higher than the glass transition temperature of the precursor layer of the thermoplastic or thermosetting by the pre-patterned male mold. 3. The mold is released (or separated) from the thermoplastic or thermosetting precursor layer, preferably during or after curing by suitable means. 4. The microcup formed as described above is filled with the electrophoretic fluid, and the filled microcup is sealed by either the one-pass or two-pass process described above. 5. Laminate (or) a second conductor film on the sealed microcup array with an adhesive layer that may optionally be a pressure sensitive adhesive, hot melt adhesive, heat, moisture or radiation curable adhesive. Overlay).

When the upper conductor film is transparent to radiation, the laminated adhesive may be post-cured through the upper conductor film by radiation such as UV. The finished product may be cut into various dimensions and shapes after the lamination process.

The manufacture of the above microcups can be easily replaced by another method by photolithography as described in WO 01/67170. Full-color EPDs can be produced by sequentially filling microcups with red, green, and blue electrophoretic fluids, and then sealing the filled microcups as described above.

V.<u style="single">Electrophoretic display with multi-layer display panel and its manufacture</u> Figures 3a and 3b show how to make an electrophoretic display with two or more display cell layers.

In FIG. 3a, for example, a two-layer electrophoresis display is manufactured by laminating the top layer (31) and the bottom layer (32) including the display cell prepared by the procedure described in steps 1 to 4 in Section IV. The method is shown. Each filled display cell is sealed with a sealing layer (33). The conductor film (34) on the display side may be transparent, and the conductor film (35) on the non-display side may be black. An adhesive layer can be used to facilitate the lamination (or overlay) process. The two layers (31 and 32) have an inactive partition area (36) on one layer and an active cell area on the other layer.<u style="single">With a staggered type that at least partially overlaps</u>It is arranged so as to be.

Figure 3b shows another method of manufacturing a two-layer electrophoretic display, in which (i) the display cell layer (32) is placed on a conductor film (35), eg, the first.<u style="single">IV</u>Prepared according to the procedure described in steps 1 to 4 in the section, and (ii) another display cell layer.<u style="single">(31)</u>On the release substrate (or substrate) (37) by the same procedure as in (i), and (iii) the display cell layer (31) on the release substrate (37) on the layer (32). Laminate with an adhesive (not shown), (iv) remove the release substrate, and (v) place the resulting composite film on top of the conductor film (34), optionally with an adhesive (not shown). The method by laminating with (1) is shown. Steps (ii), (iii) and (iv) can be repeated to produce an electrophoretic display having three or more display cell layers.

In a two-layer or multi-layer electrophoresis display as manufactured above, the inactive partition region of the microcup layer is the active microcup region of another layer.<u style="single">With a staggered type that at least partially overlaps with</u>It is important to be placed. At least one of the two conductor films (34 and 35) is pre-patterned. Further, at least the conductor film (34) on the display side is transparent.

Figures 4a and 4b show a two-layer color electrophoresis display, which contains a display cell in which the top layer (41) is filled with red, green and blue electrophoresis fluid, and the bottom layer (42) is black electrophoresis. Includes a fluid-filled display cell. In both figures, the inactive partition area (46) of the upper layer (41) is the active cell area of the lower layer (42).<u style="single">In a staggered shape that at least partially overlaps</u>It has become. This two-layer structure is sandwiched between two conductor films (44) and (45). At least one of the two conductor films is transparent.

Figures 5a and 5b show a two-layer full-color electrophoresis display, in which the top layer (51) contains display cells filled with red, green and blue electrophoresis fluid, and the bottom layer (52) is red, green, Includes display cells filled with blue and black electrophoresis fluid. The two layers of colored cells and the inactive partition area (56) are the red, green, blue and inactive partition areas of the upper layer (51), red, green, blue and blue of the bottom layer (52), respectively. Overlap with respect to the position of the black microcup<u style="single">With stagger type</u>Be placed. This two-layer structure is sandwiched between two conductor films (54) and (55). At least one of the two conductor films is transparent.

In this two-layer structure, the upper microcup layer can be laminated on top of the bottom layer at an appropriate angle to avoid the formation of unwanted moire patterns. Alternatively, a less symmetric microcup array may be used for similar purposes.

The dye particles or colorant particles may be magnetic. In one embodiment, the two-layer electromagnetic display has a bottom containing a display cell filled with an electromagnetic running fluid containing a mixture of black magnetic particles and white non-magnetic particles dispersed in a clear, colorless solvent or solvent mixture. It may have layers. The upper layer is white particles dispersed in red, green and blue solvents, respectively.<u style="single">To</u>Included Electrophoretic fluids may include red, green and blue cells filled with fluid. Alternatively, the top layer may include a display cell filled with an electrophoretic fluid containing a mixture of white and black particles dispersed in a clear, colorless solvent or solvent mixture.

Details on the electrophoretic display layer are pending applications March 20, 2003<u style="single">Day</u>Disclosed in US Application No. 10 / 394,488 filed in US Application No. 10 / 394,488 and US Application No. 10 / 421,217 filed on April 22, 2003, both of which are incorporated herein by reference in their entirety. Is done.

In general, the minimum distance or cell gap between two conductor films in a multilayer display is preferably in the range of 15-200 μm, more preferably in the range of 20-50 μm. The thickness of each display cell layer may vary, preferably in the range of 10-100 μm, more preferably in the range of 12-30 μm. Also, the concentrations of particles and dyes or colorants in each display cell layer may vary for different applications.

<u style="single">Example</u> The following examples are described to enable those skilled in the art to better understand and practice the present invention. These should not be considered as limiting the scope of the invention, but merely as exemplary and representative of the invention.

<u style="single">Preparation 1</u>Polyfunctional reactive protective colloid R_f-Amine synthesis<chemistry num="1"><img file="JP4533751B2_D0001.tif" /></chemistry>

17.8 g of Krytox (registered trademark) methyl ester (DuPont, 17.8 g, MW = about 1780, g = about 10, DuPont), 12 g of 1,1,2-trichlorotrifluoroethane (manufactured by Aldrich) and It was dissolved in a solvent mixture containing 1.5 g of α, α, α-trifluorotoluene (manufactured by Aldrich). The resulting solution contains 7.3 g of tris (2-aminoethyl) amine (manufactured by Aldrich) in 25 g of α, α, α-trifluorotoluene and 30 g of 1,1,2-trichlorotrifluoroethane. Was added by dropping the mixture over 2 hours with stirring at room temperature. The mixture was then stirred for an additional 8 hours to complete the reaction. The crude product IR (infrared) spestol is 1780 cm relative to the methyl ester.^-1No C = O oscillations in, and 1695 cm for amide products^-1It is clearly shown that the C = O oscillation appears in. The solvent was removed by rotary evaporation at 100 ° C. for 4-6 hours followed by vacuum stripping. The crude product is then dissolved in 50 ml of PFS2 solvent (low molecular weight perfluoropolyether (Solvay Solexis)), extracted 3 times with 20 ml of ethyl acetate, then dried and 17 g of purified product (R)._f-Amine 1900) was obtained, which showed excellent solubility in HT200. This substance (R_f-Amine 1780) showed good solubility in HT200.

Other reactive polyfunctional R of formula (I) with different molecular weights_f-Amine, eg R_f-Amine 4900 (g = about 30), R_f-Amine 2000 (g = about 11), R_f-Amine 800 (g = about 4) and R_f-Amine 650 (g = about 3) was also synthesized according to the same procedure.

<u style="single">Preparation 2</u>TiO₂Preparation of contained microcapsules 9.05 g of Desmodur (registered trademark) N3400 aliphatic polyisocyanate (manufactured by Bayer AG) and 0.49 g of triethanolamine (99%, manufactured by Dow) were dissolved in 3.79 g of MEK. In the resulting solution, 13 g of TiO₂Add R706 (made by DuPont) and rotor<u style="single">-</u>It was homogenized at ambient temperature for 2 minutes with a stator homogenizer (IKA ULTRA-TURRAX T25, manufactured by IKA WORKS). Solution containing 1.67 g of 1,5-pentanediol (made by BASF), 1.35 g of polypropylene oxide (molecular weight = 725, made by Aldrich), 2.47 g of MEK and 0.32 g of MEK in 2% dibutyltin dilaurate (made by Aldrich). Was added and homogenized for an additional 2 minutes. 40 in the final process<u style="single">.0</u>0.9 g R in g HT-200 (Solvay Solexis)_f-Amine 4900 (prepared in Preparation 1) was added and homogenized for 2 minutes, after which an additional 0.9 g R in 33.0 g HT-200._f-Amine 4900 was added and homogenized for 2 minutes. A low viscosity microcapsule dispersion was obtained.

The resulting microcapsule dispersion was heated at 80 ° C. overnight and stirred under low shear to post-cure the particles. The resulting microcapsule dispersion was filtered through a 400 mesh (38 micron) screen. The particle and solid content of the filtered dispersion was measured by an IR-200 moisture meter (Moisture Analyzer, manufactured by Denver Instrument Company) and found to be 29% by weight. The average particle size of the filtered dispersion was about 2 μm as measured by the Beckman Coulter LS230 Particle Analyzer.

1.0% by weight CuPc-C₈F₁₇(Structures shown below, prepared in accordance with U.S. Pat. No. 3,281,426) and various amounts of TiO obtained above.₂An EPD fluid containing the containing microcapsule dispersion in HT-200 was filled into a microcup, which was then sealed according to the procedure described in Preparation 3 and sandwiched between two ITO / PET films.

<chemistry num="2"><img file="JP4533751B2_D0002.tif" /></chemistry>

<u style="single">Preparation 3A</u>Primer-coated transparent conductor film 33.2 g EB600 (acrylic epoxy oligomer, UCB (UCB, SMANA, Georgia)), 16.12 g SR399 (pentfunctional monomer, Sartomer, Exton, Georgia), 16.12 g TMPTA (trimethylolpropane triacrylate, UCB (Sumana, Georgia)), 20.61 g HDODA (1,6-hexanediol diacrylate, UCB (Sumana, Georgia)), 2 g Irgacure, Trademarks) 369 [(2-benzyl-2- (dimethylamino) -1- [4- (4-morpholinyl) phenyl] -1-butanone), made by Ciba, Tallytown, Georgia], 0.1 g of irga Knox (Irganox, Trademark) 1035 [thiodiethylenebis (3,5-di (tert) -butyl-4-hydroxyhydrosinamate), made by Ciba], 44.35 g of poly (ethylmethacrylate) (MW) Thousandly mixed primer coating solution containing 515,000, Aldrich (Milwaukee, Wisconsin) and 399.15 g MEK (Methylethylketone), 5 mil (mil) transparent conductor film (ITO / PET film, 5 mil OC50, CP Films). (CP Films, Martinsville, VA)) coated with a # 4 drawdown bar. The coated ITO film is dried in an oven at 65 ° C for 10 minutes and 1.8 J / cm in a nitrogen atmosphere using a UV conveyor (DDU (Los Angeles, CA)).²Was exposed to UV light.

<u style="single">Preparation 3B</u>Making micro cups<tables num="1"><img file="JP4533751B2_D0003.tif" /></tables>

33.15g EB600 (acrylicized epoxy oligomer, UCB (Smyrna, Georgia)), 32.24g SR399 (pentfunctional monomer, Sartmer (Exton, Georgia)), 6g EB1360 ) (Silicone Acrylate, UCB (Smyrna, Georgia)), 8g Hycar 1300X43 (Reactive Liquid Polymer, Noveon) Inc., Cleveland, Ohio), 0.2 g Irgacure 369 [(2-benzyl-2- (dimethylamino) -1- [4- (4-morpholinyl) phenyl] -1-butanone), Ciba (Tarrytown, NY)], 0.04 g of ITX (Isopropyl-9H-thioxanthen-9-on), Aldrich (Milwaukee, Wisconsin), 0.1 g of Irganox 1035 [Thiodiethylenebis (3) , 5-Di (tert) -butyl-4-hydroxyhydrocinnamate), Ciba (Tarrytown, NY)], and 20.61 g of HDODA (1,6-hexanediol diacrylate, UCB (Smana, Georgia)) Mix well with a Stir-Pak mixer (Cole Parmer, Vernon, Illinois) for about 1 hour at room temperature, and remove with a centrifugal force device at 2000 rpm for about 15 minutes. Foamed.

This microcup composition is 4 inches x 4 inches for an array of 100 μm (length) x 100 μm (width) x 25 μm (depth) x 15 μm (width of the top surface of the partition wall between the cups) It was slowly coated on the electroformed Ni male mold. Excess fluid was removed using a plastic (or plastic) blade and gently pushed into a Ni-shaped "valley". The coated Ni mold was heated in an oven at 65 ° C. for 5 minutes, and the ITO / PET film coated with the primer prepared in Preparation 3A was laminated so that the primer layer faced the Ni mold. Laminates made by GBC Eagle 35 Laminator (GBC, Northbrook, Illinois) with 100 ° C roller temperature, 1 ft / min lamination speed and roll gap preset to "heavy gauge" ) Was used. 2.5mJ / cm²The panel was cured for 5 seconds using a UV intensity UV curing station. Then, the ITO / PET film was peeled off from the Ni mold at a peeling angle of about 30 degrees to obtain a 4 inch × 4 inch microcup array on the ITO / PET. Release (or release) of the microcup array from the mold was found to be acceptable. The microcup array thus obtained is 1.7 J / cm by a UV conveyor curing system (manufactured by DDIU (Los Angeles, CA)).²It was further post-cured at the UV exposure dose of.

<u style="single">Preparation 3C</u>Filling and sealing with composition 9.7% by weight (dry weight) of TiO₂Containing microcapsules (prepared according to Preparation 2), 1.0 wt% CuPc-C₈F₁₇And 0.5% by weight R_f-Amine 2000 (TiO₂An electrophoretic fluid containing (based on the total dry weight of the contained microcapsules) (prepared according to Preparation 1) in HT-200 in a 4 inch x 4 inch microcup array (prepared from Preparation 3B) # 0 Filled with a drawdown bar. Excess fluid was scraped off with a rubber blade.

Universal blade applicator on microcup filled with encapsulation composition containing 14% by weight polyurethane IROSTIC P9815-20 (manufactured by Huntsman Polyurethane) in MEK / IPAc / CHO (47.5 / 47.5 / 5) And dried at room temperature to form a seamless sealing layer with a dry thickness of about 2-3 μm with good uniformity.

Lamination of the conductor film on the sealed microcup is carried out by pressurizing the ITO side of the ITO / PET film (5 mils) on the sealing layer with a laminator at a rate of 20 cm / min at 120 ° C. did.

<u style="single">Comparative Example 1</u>Single layer micro cup EPD The single-layer microcup EPD obtained by making according to Preparation 3C was then coated with a thin layer of black coating on the outer surface of the conductor film on the sealing side (non-display side) of the display. The conductor film on the opposite side of the sealing layer is the display side, through which all electro-optic performance is measured.<u style="single">Mr</u>In various normalized field strengths<u style="single">Contrast ratio and</u>The test results including Dmin are shown in Table 2.

Example 2<u style="single">Staga</u>Type double layer micro cup EPD 6.0% by weight (dry weight) of TiO₂Containing microcapsules (prepared according to Preparation 2), 1.0 wt% CuPc-C₈F₁₇And 0.5% by weight (TiO₂R based on the total dry weight of the contained microparticles)_f-Electrophoretic fluid containing amine 2000 (according to Preparation 1) in HT200 was filled and sealed in the microcup array (lower layer) prepared in Preparation 3B. The sealed microcup layer is laminated on the second sealed microcup layer (upper layer) prepared in Comparative Example 1, and the inactive partition region of the upper microcup layer is the lower layer. Position of the active microcup area<u style="single">With a staggered type that at least partially overlaps with</u>Have been placed<u style="single">Staga</u>A mold double layer EPD film was formed. The obtained bilayer EPD film was evaluated in the same manner as in Comparative Example 1. Table 2 also summarizes the contrast ratios and Dmin at various standardized field strengths measured from the upper layer side.

Example 3<u style="single">Staga</u>Type double layer micro cup EPD 9.7% by weight (dry weight) of TiO in the upper microcup layer₂Contains microparticles (according to Preparation 2), 1.0 wt% CuPc-C₈F₁₇And 0.5% by weight (TiO₂R based on the total dry weight of the contained microparticles)_f-Filled with an electrophoretic fluid containing amine 2000 in HT200; also in the lower microcup layer 9.7% by weight TiO in HT200₂Contains microparticles, 1.5% by weight CuPc-C₈F₁₇And 0.5% by weight (TiO₂R based on the total dry weight of the contained microparticles)_f-The procedure was the same as in Example 2 except that it was filled with amine 2000. Table 2 summarizes the contrast ratios and Dmin at various standardized field strengths. It has been shown that the contrast ratio and Dmin are further improved by increasing the dye and particle concentrations in the lower layer.

Example 4<u style="single">Staga</u>Type double layer micro cup EPD The electrophoretic fluid in the upper microcup layer is 9.7% by weight TiO₂Contains microparticles (according to Preparation 2), 0.7 wt% CuPc-C₈F₁₇And 0.5% by weight (TiO₂R based on the total dry weight of the contained microparticles)_f-Amine 2000 shall be contained in HT200; and the lower microcup layer is 9.7% by weight TiO₂Contains microparticles, 1.5% by weight CuPc-C₈F₁₇And 0.5% by weight (TiO₂R based on the total dry weight of the contained microparticles)_f-The procedure was the same as in Example 2 except that amine 2000 was included in HT200. Table 2 summarizes the contrast ratios and Dmin at various standardized field strengths.

<tables num="2"><img file="JP4533751B2_D0004.tif" /></tables>

As is clear from Table 2, all of the two-layer EPDs (Examples 2 to 4) have a significantly higher contrast ratio and lower Dmin (higher reflection in the Dmin state) than the single-layer EPD (Comparative Example 1) at the same standardized electric field strength. Rate) was shown.

Although the present invention has been described with reference to its particular embodiments, those skilled in the art can make various modifications without departing from the true concept and scope of the invention and can be replaced by equivalents. Should be understood. In addition, many modifications can be made to the objects, concepts and scope of the invention for application to a particular situation, material, composition, process, process (one or more). All such modifications are intended to fall within the appended claims. The present invention includes the following aspects. (Aspect 1) An electrophoretic display that includes two or more layers of display cells filled with an electrophoretic fluid. (Aspect 2) The display according to aspect 1, wherein the filled display cell is sealed with a polymer sealing layer. (Aspect 3) The display according to aspect 2, wherein the display cells are separated by a partition wall. (Aspect 4) The display according to aspect 3, wherein the polymer sealing layer encapsulates an electrophoretic fluid in each cell and adheres to the surface of the partition wall of the cell in a sealing manner. (Aspect 5) The display according to aspect 4, wherein the cell is partially filled. (Aspect 6) The display according to aspect 2, wherein the polymer encapsulating layer is in contact with the top surface of the electrophoretic fluid. (Aspect 7) The display according to aspect 1, wherein the display cell is a partition type display cell. (Aspect 8) The display according to aspect 1, wherein the display cell is a microgroove or microchannel type display cell. (Aspect 9) The display according to aspect 1, wherein the display cell is a microcapsule having a cell size in the range of about 10 to about 200 μm. (Aspect 10) The display according to aspect 9, wherein the display cell is a microcapsule having a cell size in the range of about 30 to about 120 μm. (Aspect 11) The display according to aspect 1, wherein two or more layers of the display cell are sandwiched between the two conductor films, and the minimum distance between the two conductor films is in the range of about 15 to about 200 μm. (Aspect 12) The display according to aspect 11, wherein two or more layers of the display cell are sandwiched between the two conductor films, and the minimum distance between the two conductor films is in the range of about 20 to about 50 μm. (Aspect 13) The display according to aspect 1, wherein each layer of the display cell has a thickness in the range of about 10 to about 100 μm. (Aspect 14) 13. The display according to aspect 13, wherein each layer of the display cell has a thickness in the range of about 12 to about 30 μm. (Aspect 15) The display according to aspect 1, wherein the display cell is filled with an electrophoretic fluid having different colors, optical densities, switching speeds or magnetic properties. (Aspect 16) The display according to aspect 1, wherein one of the layers comprises a display cell having a different shape, size or ratio of openings to total area than the display cells of another layer. (Aspect 17) The display according to aspect 1, wherein the cells are separated by an inactive partition region and encapsulated by a polymeric encapsulating layer. (Aspect 18) The inactive partition area of one layer is the active cell area of another layer.<u style="single">With a staggered type that at least partially overlaps with</u>The display according to aspect 17, which is arranged. (Aspect 19) The display according to aspect 18, comprising one top layer of the display cell and one bottom layer of the display cell. (Aspect 20) 19. The display according to aspect 19, comprising a display cell filled with an electrophoretic fluid containing white dye particles or dye-containing microparticles dispersed in a black solvent or solvent mixture. (Aspect 21) The upper layer on the display side contains red, green or blue cells filled with an electrophoresis display fluid containing white dye particles or dye-containing microparticles dispersed in a red, green or blue solvent or solvent mixture, respectively. The display according to aspect 19, including. (Aspect 22) In a full-color or multicolor electrophoresis display, the bottom layer on the non-display side is a black one filled with an electrophoresis fluid containing white dye particles or dye-containing microparticles dispersed in a black solvent or solvent mixture. The display according to aspect 19, comprising cells. (Aspect 23) In a full-color or multicolor electrophoresis display, the bottom layer on the non-display side is an electrophoresis containing white dye particles or dye-containing microparticles dispersed in a red, green, blue and black solvent or solvent mixture, respectively. An electrophoresis fluid containing fluid-filled red, green, blue and black cells, and an upper layer containing white dye particles or dye-containing microparticles dispersed in a red, green and blue solvent or solvent mixture. 19. The display according to aspect 19, comprising red, green and blue cells filled with. (Aspect 24) The two layers of colored cells and inactive partition areas are the red, green, blue and blue cells of the top layer and the red, green, blue and black cells of the bottom layer of the partition area.<u style="single">To correspond with</u>The display according to aspect 23, which is arranged. (Aspect 25) One top layer of the display cell and one bottom layer containing an electromagnetism fluid containing a mixture of black magnetic particles and white non-magnetic particles dispersed in a clear, colorless solvent or solvent mixture. Including electromagnetic migration display. (Aspect 26) The display according to aspect 25, wherein the top layer comprises red, green and blue cells filled with an electrophoretic fluid containing white particles dispersed in red, green and blue solvents, respectively. (Aspect 27) The display according to aspect 25, wherein the upper layer comprises a display cell filled with an electrophoretic fluid containing a mixture of white and black particles dispersed in a colorless transparent solvent or solvent mixture. (Aspect 28) A method of manufacturing an electrophoretic display having two or more layers of display cells. a) Making two layers of display cells individually, each with a conductor film side and a sealing side, and b) Laminating one of these layers on top of the other, optionally with an adhesive layer. Including methods. (Aspect 29) A method according to aspect 28, wherein step (a) is performed by forming a display cell on a conductor film, filling the cell with an electrophoretic fluid, and sealing the filled cell with a polymer sealing layer. .. (Aspect 30) 29. The method of aspect 29, wherein the cell is made by microembossing. (Aspect 31) 29. The method of aspect 29, wherein the cell is made by photolithography or pre-drilled holes. (Aspect 32) 29. The method of aspect 29, wherein the cells in the two layers are made by different methods. (Aspect 33) 32. The method of aspect 32, wherein the (different) methods are micro-embossed, photolithographic or pre-drilled holes independently of each other. (Aspect 34) 28. The method of aspect 28, wherein step (b) is performed by laminating one layer of the display cell onto the other layer so that the sealing sides of the two layers face each other. (Aspect 35) A method of manufacturing an electrophoretic display having two or more layers of display cells. a) Forming a first layer of display cells, the first layer having a conductor film side and a sealing side. b) A second layer of display cells is formed on the transfer release layer, which has a transfer release layer side and a sealing side. c) Laminating the second layer on top of the first layer and removing the transfer release layer, d) Optionally, additional layers of display cells are formed separately on the transfer release layer, each layer having a transfer release layer side and a sealing side. e) Laminating each of the additional layers onto a laminate of layers already formed and removing the transfer release layer, and f) Laminating a second conductor film on top of the laminate Including methods. (Aspect 36) A method according to aspect 35, wherein step (a) is performed by forming a display cell on a conductor film, filling the cell with an electrophoretic fluid, and sealing the filled cell with a polymer sealing layer. .. (Aspect 37) 35. The method of aspect 36, wherein the cell is made by microembossing. (Aspect 38) 36. The method of aspect 36, wherein the cell is made by photolithography or pre-drilled holes. (Aspect 39) Steps (b) and (d) are carried out by forming a display cell on the transfer release layer, filling the cell with an electrophoretic fluid, and sealing the filled cell with a polymer sealing layer. The method according to aspect 35. (Aspect 40) The method of aspect 39, wherein the cell is made by microembossing. (Aspect 41) 39. The method of aspect 39, wherein the cell is made by photolithography or pre-drilled holes. (Aspect 42) 35. The method of aspect 35, wherein the layers of the display cell are made by different methods. (Aspect 43) 42. The method of aspect 42, wherein the (different) methods are micro-embossed, photolithographic or pre-drilled holes independently of each other. (Aspect 44) Step (c) is performed by laminating the second layer onto the first layer so that the sealing sides of the two layers face each other, and then removing the transfer release layer. The method according to aspect 35. (Aspect 45) In step (e), the additional layer is laminated on the laminated body of the already formed layers so that the sealing side of the additional layer faces the laminated body, and then the transfer release layer is removed. 35. The method of embodiment 35. (Aspect 46) 35. The method of aspect 35, wherein step (f) is performed by laminating with or without an adhesive layer.

<figref num="1">Figure 1 shows a typical electrophoretic display cell manufactured by the microcup technique using a dark background to improve the contrast ratio. The background color can be seen through the inactive partition area in both the "on" and "off" states. A display with low reflectance is obtained in the Dmin state.</figref><figref num="2">Figures 2a and 2b show the "on" (Dmin) and "off" (Dmax) states of the dual-layer electrophoresis display, respectively. In the Dmin state, the white particles in both layers are attracted to the top of the microcup. The inactive partition area of the upper layer appears white because the light is reflected back by the white particles in the bottom microcup layer. In contrast, in the Dmax state, the white particles in both layers are attracted to the bottom of the microcup and the light is absorbed by the colored solvent in the bottom microcup layer, thus the inactive partition region of the upper layer. Looks colored.</figref><figref num="3a">FIG. 3a shows a method for manufacturing an electrophoretic display having two or more display cell layers. FIG. 3a shows a method of manufacturing a two-layer electrophoresis display by laminating two microcup layers with the sealing sides of the microcups facing each other.</figref><figref num="3b">FIG. 3b shows a method for manufacturing an electrophoretic display having two or more display cell layers. Figure 3b shows another method of manufacturing a two-layer electrophoretic display: (i) transferring (or moving) a microcup layer from a release substrate onto a second microcup layer on a conductor film, and (ii) The method by laminating the obtained composite film on the conductor film (possibly by an adhesive) is shown. Step (i) can be repeated to produce an electrophoretic display having three or more display cell layers.</figref><figref num="4">Figures 4a and 4b show a two-layer color electrophoretic display containing microcups with top layers filled with red, green and blue electrophoretic fluids and bottom layers with microcups filled with black electrophoretic fluids.</figref><figref num="5">Figures 5a and 5b show a two-layer full color containing microcups with top layers filled with red, green and blue electrophoresis fluids and bottom layers with microcups filled with red, green, blue and black electrophoresis fluids. The electrophoresis display is shown. The red, green, blue and inactive partition areas of the upper layer overlap with respect to the positions of the red, green, blue and black microcups of the lower layer, respectively.</figref>