WO2012030198A2 - Electrophoretic particles, multi-color display device, and image sheet - Google Patents

Abstract

The present invention relates to electrophoretic particles for a multi-color display, and an image sheet and an electrophoretic display device including the same. According to one embodiment of the present invention, the electrophoretic particles for a multi-color display comprise: light reflective sub particles and color layer which encloses said light reflective sub particles.

Description

Electrophoretic Particles, Multi Color Display and Image Sheet

TECHNICAL FIELD The present invention relates to display technology, and more particularly, to electrophoretic particles, electrophoretic display devices, and image sheets for multi-color displays.

An information display device for replacing a liquid crystal display device, the display device using a technique such as electrophoresis, electro-chromic, dichroic particles rotary method, dry powder transfer method Has been proposed. These techniques have been extensively studied as next generation display devices that can replace liquid crystal display devices due to advantages such as wide viewing angle, low power consumption, and memory effect in proximity to conventional print media such as paper.

Among these display devices, an electrophoretic display device uses a phenomenon in which charged particles move by an electric field applied between two electrodes. In order to display a color image, the electrophoretic display device implements a color subpixel by using a monochrome electrophoretic image sheet in which a color filter is combined or by using two or more kinds of color particles having different colors. In general, it may be desirable to implement color subpixels using two or more types of charged color particles, since using a color filter may result in a decrease in brightness or a reduction in color saturation.

An object of the present invention is to provide electrophoretic particles capable of improving display quality such as color reproducibility and contrast of displayed information as color particles for electrophoretic display capable of multi-color implementation.

Another technical problem to be achieved by the present invention is to provide an image sheet using electrophoretic particles having the aforementioned advantages.

Another object of the present invention is to provide a multi-color electrophoretic display device using electrophoretic particles having the aforementioned advantages.

Electrophoretic particles for multi-color display according to an embodiment of the present invention for achieving the above technical problem is a light reflective sub-particles; And a color layer surrounding the light reflective subparticles. The electrophoretic particles may have a size ranging from 0.05 μm to 2 μm.

The light reflective subparticles may have a size adjusted to achieve light shielding. The light reflective subparticles may comprise a single particle core. The single particle core may have a size of 0.01 μm to 1 μm. Preferably, the single particle core may have a size of 0.05 μm to 0.8 μm, and more preferably, the single particle core may have a size of 0.2 μm to 0.8 μm.

In some embodiments, the light reflective sub-particle includes a plurality of reflective particles, wherein the size of the plurality of reflective particles is equal to the cross-sectional area S1 in the radial direction of the particle and the cross-sectional area S2 in the radial direction of the reflective particles. The ratio S1 / S2 may be selected to be 2 or more and 100 or less. In addition, the light reflective subparticles may include white inorganic particles. The white inorganic particles include titanium oxide, antimony trioxide, zinc sulfide, zinc oxide, barium sulfate, barium titanium oxide, kaolin (kaolun), silicon oxide (silica), calcium oxide (calcium oxide), calcium carbonate (CaCO ₃ ), or a mixed composition thereof may be included. In another embodiment, the light reflective subparticles may include metal particles. The metallic particles may be any one or combination of silver nanoparticles, platinum nanoparticles, and aluminum nanoparticles.

The color layer comprises a composition comprising a binder resin and a dye having a predetermined color dispersed in the binder resin. The said binder resin contains the reactive group which has affinity with respect to the surface of the said light reflective subparticle. The reactive group may be an epoxy group, a thioepoxy group, a silanol group, a alkylamino group, an aziridin group, an oxazin group, an isocyanate group. ) Or a combination thereof. The density | concentration of the said dye with respect to the said binder resin is 1 weight% or more and 70 weight% or less.

The color layer may include a layer of dye material adsorbed to have physical, chemical, or both properties of the surface of the light reflective subparticles. The light reflective subparticles may comprise light shielding pigment particles. The color of the color layer and the pigment single particle may be the same.

According to an aspect of the present invention, there is provided a multi-color electrophoretic display device, comprising: a plurality of cavities disposed between substrates facing each other; A dielectric fluid defined within the plurality of cavities; And electrophoretic particles having at least one of the foregoing features dispersed within the dielectric fluid. In this case, the dielectric fluid may be transparent.

In some embodiments, only the electrophoretic particles having any one color may be commonly dispersed in adjacent cavities of the plurality of cavities. The color of the commonly dispersed electrophoretic particles may be green.

In accordance with another aspect of the present invention, an image sheet includes: a plurality of cavities disposed between support substrates facing each other; A dielectric fluid defined within the plurality of cavities; And electrophoretic particles having at least one of the foregoing features dispersed within the dielectric fluid. The dielectric fluid may be transparent.

Electrophoretic particles for multi-color display according to embodiments of the present invention, while improving the shielding power to the external light transmitted by the light reflective sub-particles to ensure excellent light reflectivity, to improve the color reproduction of the electrophoretic display device You can. In addition, according to the embodiment of the present invention, due to the excellent light shielding power, it is possible to use a transparent dielectric fluid in the cavity, there is an advantage that can improve the contrast of the display information. In addition, according to the embodiment of the present invention, even if the total particles having a size of a few micro to submicron, it is possible to increase the bistable stability while ensuring excellent electrophoretic mobility.

1A and 1B are cross-sectional views showing the structure of electrophoretic particles for multi-color display according to embodiments of the present invention.

2 is a cross-sectional view showing the structure of electrophoretic particles for multi-color display according to other embodiments of the present invention.

3 is a cross-sectional view showing the structure of electrophoretic particles for multi-color display according to another embodiment of the present invention.

4A is a cross-sectional view showing a multi-color display device using electrophoretic particles according to one embodiment of the present invention, and FIG. 4B is a cross-sectional view showing an electrophoretic display device using dyed resin-based color particles as a comparative example. to be.

5A is a cross-sectional view showing another electrophoretic display device using particles according to embodiments of the present invention, and FIG. 5B is a cross-sectional view showing another electrophoretic display device using dyed resin-based color particles as a comparative example. .

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art, and the following examples can be modified in various other forms, and the scope of the present invention is It is not limited to an Example. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the inventive concept to those skilled in the art.

In addition, the thickness or size of each layer in the drawings is exaggerated for convenience and clarity, the same reference numerals in the drawings refer to the same elements. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. Also, as used herein, "comprise" and / or "comprising" specifies the presence of the mentioned shapes, numbers, steps, actions, members, elements and / or groups of these. It is not intended to exclude the presence or the addition of one or more other shapes, numbers, acts, members, elements and / or groups.

Although the terms first, second, etc. are used herein to describe various members, parts, regions, and / or parts, these members, parts, regions, and / or parts should not be limited by these terms. do. These terms are only used to distinguish one member, part, region or part from another region or part. Thus, the first member, part, region, or portion, which will be described below, may refer to the second member, component, region, or portion without departing from the teachings of the present invention.

Embodiments of the present invention will now be described with reference to the drawings, which schematically illustrate ideal embodiments of the present invention. In the drawings, for example, the size and shape of the members may be exaggerated for convenience and clarity of description, and in actual implementation, variations of the illustrated shape may be expected. Accordingly, embodiments of the present invention should not be construed as limited to the specific shapes of the regions shown herein.

Structure and manufacturing method of colored particles

1A and 1B are cross-sectional views showing the structure of the particles 100A and 100B for a multi-color electrophoretic display device according to embodiments of the present invention.

Referring to FIG. 1A, particle 100A includes a light reflective subparticle 101A and a color layer 102 surrounding the light reflective subparticle. Particles 100A are generally spherical, but the present invention is not limited thereto. The particles 100A may have various shapes such as elliptical or amorphous potato shapes. In the implementation of the actual display device, it was observed that the light shielding properties of the particles 100A are better when the particles 100A do not have a perfect sphere.

Particle 100A preferably has light reflectivity while increasing light shielding to ensure faithful color reproduction. In addition, in order to ensure excellent electrophoretic mobility, the size of the entire particles 100A is 0.02 μm to 10 μm, and preferably, 0.05 μm to 2 μm. Within this range, the particles have the advantage of increased bistableness and increased density of the particle layer collected on the electrode. When the overall size of particles 100A is thus several micrometers or submicron in dimension, the light shielding properties of particles 100A can have a significant impact on display quality, which will be described later.

The light reflective subparticle 101A may include single solid particles having a predetermined controlled size, as shown. The single particle may have a size d1 of 0.01 μm to 1 μm, preferably, a size of 0.05 μm to 0.8 μm, and more preferably, a size d1 of 0.2 μm to 0.8 μm. Can have Within the aforementioned range, light reflectance of 90% or more and a suitable level of particle mobility could be obtained.

Experimentally, less than 0.01 μm, sufficient light shielding effect was not obtained due to the skin depth of visible light or ultraviolet light, and thus the reflectivity sharply decreased to obtain sufficient brightness. In addition, when the size d1 of the light reflective sub-particles exceeds 1 μm, the specific gravity of the whole particle increases relative to the unit surface area, making it difficult to secure sufficient electrophoretic mobility.

The light reflective subparticles 101 may be white inorganic particles. The white inorganic particles include titanium oxide, antimony trioxide, zinc sulfide, zinc oxide, barium sulfate, barium titanium oxide, kaolin (kaolun), silicon oxide (silica), calcium oxide (calcium oxide), calcium carbonate (CaCO ₃ ), or a combination thereof may be included. The materials listed are exemplary and the present invention is not limited thereto. In another embodiment, the light reflective subparticles 101 may be metal particles. The metallic particles may be, for example, silver nanoparticles, platinum nanoparticles, or aluminum nanoparticles.

In another embodiment, the light reflective sub-particles may be composed of a plurality of particles 101B made of the reflective material described above as shown in FIG. 1B. The size of the whole particles 100B is 0.02 μm to 10 μm, preferably 0.05 μm to 2 μm.

The size d3 of the plurality of particles 101B has a ratio S1 / S2 of the cross-sectional area S1 in the radial direction of the entire particle 100B and the cross-sectional area S2 in the radial direction of the reflective particles 101B. It may be selected to be more than 100. If the size of the plurality of particles 101B with respect to the size of the whole particle 100A is smaller than 100, the color reproduction power is reduced, which is understood to be because the shielding property is weakened. Preferably, the size of the plurality of particles 101B may be selected such that the ratio S1 / S2 is 2 or more and 50 or less, and more preferably, the ratio S1 / S2 is 2 or more and 10 or less. The size of the plurality of particles 101B may be selected as such. The size d3 of the plurality of particles 101B is densely packed in the entire particle 100B by having a predetermined particle size distribution within the above range, thereby securing the same level of light shielding as the single particle core 101A. can do.

Referring to FIG. 1A together with FIG. 1B, the color layer 102 may be a composition including a binder resin and a dye having a predetermined color dispersed in the binder resin. The binder resin is, for example, urethane resin (ureethane resin), urea resin (urea resin), acrylic resin (acrylic resin), polyester resin (polyester resin), acrylic urethane resin (acryl urethane resin), acrylic urethane silicone resin (acryl urethane silicone resin), acrylic urethane fluoro-carbon polymers, acrylic fluorocarbon polymers, silicone resins, acrylic silicone resins, polystyrene resins ( polystyrene resin, styrene acrylic resin, polyolefin resin, butyral resin, vinylylidene chloride resin, melamine resin, phenolic resin ( phenolic resins, fluorocarbon polymers, polycarbonate resins, polysulfon resins, polyether resins, poly May be a polymer resin material such as ethylene resin (polyethylene resin) and polyimide resin (polyamide resin), these materials may be used in combination of two or more materials. However, this is exemplary and the present invention is not limited thereto. For example, the binder resin may be gelatin, alginic acid, latex polymer, polystyrene, polyvinyl formal, polyvinyl butyral, polymethyl acrylate, polybutyl acrylate, polymethyl. It may be formed in any one of methacrylate, polybutyl methacrylate or in combination with those described above.

In some embodiments, the binder resin may have reactive groups having good affinity for the surfaces of the light reflective subparticles 101A, 101B. For example, an epoxy group, a thioepoxy group, a silanol group, an alkylamino group, an aziridin group, an oxazin group, an isocyanate group It may be a material containing a reactive group such as). These reactive groups can be applied independently or in combination.

The color layer 102 is colored to have the corresponding color by the dye dispersed in the binder resin. The color of the color layer 102 may be any one of red, green, and blue, or one of magenta, cyan, and yellow. Alternatively, the color of the color layer 102 may be black or white. The color layer 102 may be formed of a composite layer including two or more layers. In this case, the composition of the binder resin constituting each layer and the color of the dye may be different. In addition, the composite layer may provide particles having any one of red, green, and blue, or one of magenta, cyan, and yellow by mixing different colors.

The dye for forming the color layer 102 may be a compound with a suitable solvent. Such dyes may be commercial acid dyes, oil-soluble dyes, disperse dyes, reactive dyes or direct dyes and the like. For example, the dye may be azo dyes, benzoquinone dyes, naphthoquinone dyes, anthraquinone dyes, cyanine dyes, or squary. Squamium dyes, croconium dyes, melocyanine dyes, stilbene dyes, diphenylmethane dyes, triphenylmethane dyes, Fluororane dyes, spiropyran dyes, phthalocyanine dyes, indigo dyes, flugide dyes, nickel complex dyes and sub- It may be any one or a combination of azulene dyes.

In the case of using the pigment as a pigment, since the pigment itself has a particle diameter of about 0.05 μm to several μm, it may itself be a foreign matter in the binder resin, or the dispersion may not be stabilized and cause aggregation. Thus, when the particles 100A and 100B have a size of several micrometers to submicron, they are adsorbed and / or reacted with the binder resin instead of the pigment in order to obtain a uniform coating thickness d2 and excellent color uniformity over the entire surface. It is preferable to implement the color layer 102 by means of a dye.

An organic solvent in which the resin material and dye to be the color layer 102 is dissolved, for example, acetone, methanol, ethanol, isopropylalcohol, and methoxymethylmethylpentanol pentanol, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone (methyl isopropyl ketone), methyl cellosolve (methyl cellosolve), ethyl cellosolve (ethyl cellosolve), methyl cellosolve acetate (methyl cellosolve acetate), the optical semi-finished core particles (101A, 101B) is put into a, using a mixer By mixing, or by dyeing the binder resin layer on the photo-reflective core particles (101A, 101B) in a wet manner using a dry solvent such as thermocompression or a predetermined pH. In another embodiment, the binder resin layer may be first coated on the light reflective sub-particles, and then the resultant is impregnated in a solvent in which the dye is dissolved, and the binder resin layer may be dyed to form the color layer 102.

The concentration of the dye with respect to the binder resin may be 1% by weight or more and 70% by weight or less. Preferably, it may be 3 to 40% by weight. When the concentration of the dye is less than 1% by weight, faithful color purity cannot be obtained. When the concentration of the dye is more than 70% by weight, the crystallinity of the dye molecules is not only high, but also precipitated to form the color layer 102 having a uniform thickness. Not.

The thickness of the color layer 102 may be appropriately selected in consideration of the sizes of the entire particles 100A and 100B. The thickness d2 of the color layer 102 is several μm or less, preferably 0.05 μm to 2 μm or less. The reflective subparticles 101A and 101B generally have a relatively large specific gravity compared to the dielectric solution (see U in FIG. 4A) described below in which the particles 100A and 1000B will be dispersed. If the specific gravity of the dielectric solution and the specific gravity of the particles (00A, 100B) is the same, since the particles are not affected by gravity in the dielectric solution (U), there is an advantage that the displayed information can be maintained even if the power is removed. . Thus, by adjusting the thickness d2 of the color layer 102, the particles 100A and 100B can be healed to have the same specific gravity as the dielectric solution U.

In some embodiments, particles 100A, 100B may further include at least one or more additives, such as charge control agents, additives to improve fluidity, photoinitiators and photoamplifiers in or on color layer 102. These additives may be dispersed in the color layer 102 or copolymerized with a binder resin material, and may have a configuration that is adsorbed or chemically bonded on the surface of the color layer 102.

Although the binder resin material of the color layer 102 may have an inherent charge, the total charge of the particles 100A and 100B may be actively controlled by the charge control agent. The charge control agent may include, for example, a negative or positive charge control agent. Negative charge control agents are, for example, salicylic acid metal complexes, metal containing azo dyes, oil-soluble dyes of metal-containing, quaternary ammonium The fourth grade ammonium salt-based compound, calixarene compound, boron-containing compound (e.g., benzyl acid boron complex), and nitroimi It may be a nitroimidazole derivative. The positive charge control agent may be, for example, a nigrosine dye, a trih-enylmethane compound, the fourth grade ammonium salt-based compound, It may be any one or combination of polyamine resins and imidazole derivatives. In another embodiment, the charge of the particles 100a, 100b may be provided by charging between particles having different kinds of binder resin layers.

As an additive for improving the fluidity, for example, Tween-based, SPAN-based dispersant, polyisobutylene succimide (PIBSI) series, ((M9 8ZS, Manchester, UK, obtained from Noveon Division Lubrizol Limited of Blakeley Hexagon House) Possible) Solsperse series products may be used The photoinitiator and the optical amplification agent may be known according to the binder resin used, but the present invention is not limited thereto.

Although not shown, an additional protective layer made of, for example, a polymer may be further formed at the outermost part of the particles 100A, 100B to protect the particles from externally applied mechanical, photochemical and / or electrical stresses. have.

2 is a cross-sectional view showing the structure of the particles 200 for a multi-color electrophoretic display device according to other embodiments of the present invention.

Referring to FIG. 2, the particle 200, similar to the particle 100 described with reference to FIG. 1A, has a color layer 202 surrounding the light reflective subparticle 201 and the light reflective subparticle 201. Include. However, the color layer 202 may be a layer of dye material 202 physically and / or chemically adsorbed to the surface of the light reflective subparticle 201, unlike the color layer 102 disclosed in FIG. 1A.

In order to ensure proper mobility, the size of the whole particles 200 is 0.02 ㎛ to 10 ㎛, preferably, 0.05 ㎛ to 2 ㎛. . The light reflective subparticle 201 may be a single particle, and the single particle may have a size d1 of 0.01 μm to 1 μm. Preferably, the single particle may have a size d1 of 0.05 μm to 0.8 μm, and more preferably, may have a size d1 of 0.2 μm to 0.8 μm.

In another embodiment, the light reflective subparticle 201 may comprise a plurality of particles of light reflective material (see 101B in FIG. 1B). In this case, the size (d3) of the plurality of particles is a ratio (S1 / S2) of the cross-sectional area (S1) in the radial direction of the entire particle 200 and the cross-sectional area (S2) in the radial direction of the plurality of particles is 2 or more 100 It may be selected to be as follows. In fact, if the size of the plurality of particles is smaller than 100, the shielding is weakened and color reproduction power is reduced. Preferably, the size of the plurality of particles may be selected such that the ratio S1 / S2 is 2 or more and 50 or less, and more preferably, the plurality of particles such that the ratio S1 / S2 is 2 or more and 10 or less. The size of the particles of can be chosen. The plurality of particles are densely packed in the whole particle 200 within the above range, thereby obtaining the same level of light shielding as the single particle core.

In order to adsorb the dye material layer 202 on the light reflective subparticle 201, the light reflective subparticles 201 are immersed in a solution in which the dye material is dispersed for a few minutes to several hours, so that the dye material is light reflective. It adsorbs on the surface of the sub particle 201. As a solvent for dispersing the dye material, acetonitrile, dichloromethane or an alcohol solvent may be used. The particle 200 can then be prepared by removing the unadsorbed dye material from the surface of the light reflective subparticles 201 using a suitable cleaning solution.

The color layer 202 made of the dye material adsorbed to the light reflective subparticle 201 may have red, green or blue color, or may have magenta, cyan or yellow color. Alternatively, the color layer 202 may have black or white. When the color layer 202 is a composite layer composed of two or more dye material layers, the colors of each dye material layer may be different from each other, and may be red, green, blue or magenta, cyan, yellow by mixing different colors. It is also possible to provide particles having a color of. With regard to suitable dye materials, reference may be made to the dye materials described above.

The thickness of the color layer 201 may be several μm or less, and may be appropriately selected in consideration of the sizes of the whole particles 100A and 100B, preferably 0.05 μm to 2 μm or less. In addition, the thickness of the color layer 201 may preferably be selected such that the particles 200 have a specific gravity substantially the same as the dielectric solution U.

Although not shown, a person skilled in the art will appreciate that the color layer 102 composed of a colored layer 201 made of the adsorbed dye material disclosed with reference to FIG. 2 and a binder resin layer colored by the dye described above with reference to FIGS. 1A and 1B. It will be appreciated that color layers of this combined multilayer structure are also included in the embodiments of the present invention.

3 is a cross-sectional view showing the structure of a particle 300 for a multi-color electrophoretic display device according to another embodiment of the present invention.

Referring to FIG. 3, the particle 300 includes a light shielding pigment particle 301 having a first color at its center and a color layer 302 having a second color surrounding the light shielding pigment particle 301. Particle 300 may have a spherical distribution in the range of 100% to 140% shape coefficient, in order to ensure excellent electrophoretic mobility, the size of the entire particle 300 is several μm or less, to ensure the appropriate mobility In order to achieve this, the size of the whole particles 300 is 0.02 μm to 10 μm, and preferably, 0.05 μm to 2 μm. In the particles within this range, as compared with particles of several tens to hundreds of micrometers in size, the pair-safety is improved, and the packing state of the particle layer collected on any one electrode can be improved.

The light shielding pigment particle 301 may be a pigment single particle adjusted to a predetermined size to have a light shielding property. The pigment single particle may have a size (d1) of 0.01 μm to 1 μm, preferably, has a size (d1) of 0.05 μm to 0.8 μm, and more preferably, a size of 0.2 μm to 0.8 μm may have (d1). In the above-described range, light reflectance of 90% or more and particle mobility of 85% to 95% were obtained.

In other embodiments, the light shielding pigment particles 301 may comprise a plurality of pigment particles similar to the particle structure 100B of FIG. 1B. In this case, the size (d1) of the plurality of pigment particles is a ratio (S1 / S2) of the cross-sectional area (S1) in the radial direction of the whole particle 300 and the cross-sectional area (S2) in the radial direction of the plurality of pigment particles is 2 It may be selected to be more than 100. Preferably, the size of the plurality of pigment particles 301 may be selected such that the ratio S1 / S2 is 2 or more and 50 or less, and more preferably, the ratio S1 / S2 is 2 or more and 10 or less. The size of the plurality of pigment particles 301 may be selected as such. The size d1 of the plurality of pigment particles 301 may have a suitable particle size distribution within the above range, and is densely packed within the whole particle 300.

The thickness d2 of the color layer 302 may be selected in consideration of the size of the entire particle 300. Preferably, the thickness of the color layer 302 is chosen such that the total specific gravity of the particles 300 has the same specific gravity as the dielectric solution U.

The color layer 302 surrounding the light shielding pigment particles 301 may be made of a mixed composition of a suitable binder resin and a dye having that color, as described above with reference to FIGS. 1A and 1B. Optionally, the color layer 302 may comprise a layer of dye material that is physically and / or chemically adsorbed to the surface of the light shielding pigment particle 302, as described above with reference to FIG. 2. However, this is exemplary and the present invention is not limited thereto. For example, the color layer 302 may be formed in a multi-layered structure including a color layer 202 made of the adsorbed dye material of FIG. 2 and a color layer 102 colored by the dye of FIG. 1.

The color of the light shielding pigment particles 301 and the color of the color layer 302 may be the same. For example, the color of the light shielding pigment particle 301 and the color layer 302 may be either red, green, or blue, or may be either magenta, cyan, or yellow. Alternatively, the color of the light shielding pigment particle 301 and the color layer 302 may be black or white. Here, the same color means not only having completely the same color coordinates, but also clearly including a concept having color coordinates of approximately the same degree.

In other embodiments, the colors of the light shielding pigment particles 301 and the color layer 302 may be different. In this case, one of red, green, and blue colors, or one of magenta, cyan, and yellow colors may be implemented by mixing different colors.

Electrophoretic display device and driven

FIG. 4A is a cross-sectional view illustrating an electrophoretic display apparatus 1000 using particles 100R, 100G, and 100B according to one embodiment of the present invention, and FIG. 4B illustrates conventional particles PR, It is sectional drawing which shows the electrophoretic display apparatus 1000R using PG and PB.

4A and 4B, the electrophoretic display apparatuses 1000 and 1000R may include a first substrate 10 (which may be a lower substrate in this drawing) and a second substrate 20 facing the lower substrate 10. In the figure, which may be an upper substrate). In one embodiment, at least one of the lower substrate 10 and the upper substrate 20 may be formed of a transparent material. Optionally, the substrates 10 and 20 are formed of a resin-based material, which is lightweight and may be flexible.

Between the substrates 10 and 20, a plurality of partition walls 30, which are separation members, may be disposed. The space between the substrates 10 and 20 by the plurality of partition walls 30 is divided in a direction parallel to the main surfaces of the substrates 10 and 20, and the cavity V1 and V2 are divided by the divided small spaces. , V3) can be defined. Each cavity may be alone or in combination with other adjacent one or more cavities to constitute one subpixel or pixel. The partition structure defining these cavities V1, V2, V3 is exemplary, and embodiments of the present invention are not limited thereto. For example, the cavities V1, V2, V3 may also be defined by known microcapsule or microcup structures.

The electrophoretic display apparatuses 1000 and 1000R include driving electrodes 41 and 42. The illustrated electrodes 41, 42 have configurations that oppose each other so as to generate an electric field perpendicular to the major surfaces of the substrates 10, 20, but this is merely illustrative, and the electrodes are known in-plane configurations or they It may have a combined configuration. The electrodes 42 disposed on the lower substrate 10 may include individual electrodes 42R, 42G, and 42B for each cell. In addition, the electrode 41 on the upper substrate 20 is a common electrode opposite the individual electrodes 42.

At least one of these electrodes 41 and 42 may be a transparent electrode. The transparent electrode may include, for example, Indium-Tin-Oxide (ITO), Fluorinated Tin Oxide (FTO), Indium Oxide (IO), and Tin Oxide; It may be formed of any one or a combination of a transparent metal oxide such as SnO ₂ ), a transparent conductive resin such as polyacetylene, or a conductive resin containing conductive metal fine particles.

Each individual electrode 42 may be driven by a suitable switch element, for example MOS thin film transistor 50. The MOS thin film transistors 50 may be disposed on the lower substrate 10, for example, in an array of a plurality of rows by a plurality of columns. In the present embodiment, the active matrix by the MOS thin film transistors 50 for driving the individual electrodes 42 is disclosed, but this is only illustrative, and those skilled in the art will realize a passive matrix type electrode configuration, or static driving. It will be appreciated that the segmented electrode configuration is also included in the embodiment of the present invention.

A plurality of cavities (V1, V2, V3) inside the dielectric solution (U) and at least one or more electrophoretic particles (100R, 100G, 100B, 100K; PR, PG, PB, PK) is dispersed. In the illustrated embodiment, it is disclosed that two kinds of particles having different color and / or electrophoretic mobility are dispersed in the cavities V1, V2, V3. However, this is exemplary and may be filled with one kind of particles or three or more kinds of particles in the cavities V1, V2, V3. The plurality of cells V1, V2, and V3 may be closed by the sealing layer 80.

Particles 100R, 100G, 100B, 100K (PR, PG, PB, PK) dispersed in cavities V1, V2, V3 have a color corresponding to the pixel or subpixel to be implemented. For example, particles 100R, 100G, 100B, 100K; PR, PG, PB, and PK of the first to third cavities V1, V2, and V3 may be used to realize multi-color by the RGB color system. Silver may comprise red, green and blue particles, respectively. Alternatively, the multi color may be implemented by the CMY color system. In this case, the particles 100R, 100G, 100B; PR, PG, and PB of the first to third cavities V1, V2, and V3 may be cyan, respectively. It may also comprise magenta and yellow particles. Also, black or white particles 100K (PK) may be further included in each pixel.

The dielectric solution U is a fluid having high resistance and low viscosity. The dielectric solution U is a single fluid or a mixture of two or more fluids. The specific gravity of the dielectric solution U may be prepared to be substantially the same as the specific gravity of the particles 100R, 100G, 100B, and 100K dispersed in the dielectric solution U. In addition to the particles in the dielectric solution (U), a variety of charge-controlling agents, cationic or anionic surfactants, metal soaps, resin materials, metal-based coupling agents and stabilizing agents Functional additives may be added.

Conventional dielectric solutions are colored by dyes or pigments to prevent the color of the particles that should not be visible from the viewer, as described below, on the viewer side. Generally, in the case of commercially available electrophoretic display products, the dielectric solution is colored to have a gray color to suppress the immersion of the particles. However, when coloring the dielectric solution, contrast may be reduced when implementing a two-color display of black and white. In addition, in the multi-color display device, the dielectric solution colored in gray becomes a factor of reducing color gamut. Therefore, the dielectric solution is preferably transparent or colorless. The inventors have found that using a transparent dielectric solution without the immersion of these particles can be achieved through the improvement of the particles according to embodiments of the present invention. From the following description, the advantages of the particles according to the embodiments of the invention disclosed with reference to FIGS. 1A to 3 will become apparent.

4A and 4B show a state in which dispersed particles are distributed so as to express predetermined information by a signal applied to each cell. Within the cells of FIG. 4A, particles 100R, 100G, 100B, 100K according to one embodiment of the invention, for example, the particles disclosed with reference to FIGS. 1 to 3, for example, light reflective Particles comprising the subparticle and the colored layer with the controlled thickness are dispersed.

FIG. 4B is a comparative example of the embodiments of the present invention. In the cells of FIG. 4B, the dye-based color particles PR, PG, PB, and PK, that is, dyes are dispersed in a predetermined color. Particles with colored colored polymer bodies or polymer matrices are dispersed. For convenience of explanation, it is assumed that the color particles 100R, 100G, 100B (PR, PG, PB) are charged with + and have red, green, and blue colors, respectively. In addition, each cell further includes black particles 100K (PK). These black particles 100K (PK) are assumed to have a polarity.

When a scan signal is received through the gate electrode 50G and a data signal is received through the source electrode 50S, a predetermined electric field may be applied between the pixel electrodes 42R, 42G, and 42B and the common electrode 41. Can be. For example, a negative potential is applied to the pixel electrode 42R of the first subpixel V1 and a positive potential is applied to the pixel electrodes 42G and 42B of the second and third subpixels V2 and V3. A potential is applied, and a ground potential may be applied to the common electrode 41. In this case, the particles 100R, 100G, 100B, 100K; PR, PG, PB, PK will be distributed as shown.

In the first and second subpixels V1 and V2, the incident light i is reflected by the particles 100R, 100G (PR, PG) and has a wavelength of red and green color to the viewer 1, respectively. Light is transmitted. On the contrary, in the third subpixel V3, all incident light i is absorbed and turned off by the black particles 100K and PK, and no light is transmitted to the observer 1. As a result, the observer 1 observes the color in which the red light (iR; iR ') and the green light (iG; iG') which are reflected light are mixed.

In the embodiment of FIG. 4A using particles according to an embodiment of the present invention, the light reflectivity of the particles is increased by the reflective sub-particles, thereby improving the color reproducibility of the reflected light by the color layer. In addition, the particles have excellent light shielding power by the reflective sub-particles and the color layer having a controlled size. As a result, even if the dielectric solution U is transparent, the black particles 100K, which should be hidden by the color particles 100R and 100G and should not be visible to the viewer 1, are not reflected to the viewer 1. Therefore, by using the particles according to the embodiment of the present invention, the non-impregnation phenomenon can be suppressed even when the dielectric solution (U) is not colored, thereby improving contrast as well as color reproduction.

On the other hand, in FIG. 4B of the comparative example, since light shielding property is weak compared with the particle | grains of this invention, some of incident light i is absorbed or transmitted, and reflection light iR ', iG' is lost. Thus, not only the contrast of the display information is reduced, but also the color reproducibility is reduced. In addition, when using the transparent dielectric solution U, black particles PK which may not be visible to the viewer 1 by the transmitted light iT may be illuminated. This immersion phenomenon may cause the color reproducibility to be reduced in the display device having two or more kinds of different color particles in the same subpixels as described below.

FIG. 5A is a cross-sectional view showing another electrophoretic display apparatus 2000 using particles 100R, 100G, and 100B according to embodiments of the present invention, and FIG. 5B is a dye-based resin particle (PR) as a comparative example. Is a cross-sectional view showing another electrophoretic display device 2000R using PG, PB. In these figures, reference may be made to the foregoing disclosure regarding constituent members having the same reference numerals as the constituent members of FIGS. 4A and 4B.

In the embodiment shown in FIGS. 5A and 5B, unlike the apparatus of FIGS. 4A and 4B, two kinds of color particles are dispersed in each of the subpixels V1 and V2. In some embodiments, as shown, particles having a predetermined color may be commonly dispersed in adjacent subpixels. For example, as shown, red and green particles 100R and 100G are dispersed together in the first subpixel V1, and blue and green particles (in the adjacent second subpixel V2). By dispersing 100B and 100G together, only green particles may be commonly dispersed in adjacent subpixels V1 and V2. Since the human eye is sensitive to green, by dispersing the green particles 100G in different cells in common, it is possible to increase the display area of the green particles compared to other colors. In this case, unlike FIG. 4A, the area required to form green pixels separately is reduced, thereby increasing the number of pixels under the same display area, thereby improving the resolution. In another embodiment, the magenta and cyan particles may be dispersed in the first subpixel V1 and the yellow and cyan particles may be dispersed in the second subpixel V2, in which case the cyan particles may be dispersed. The above-described advantages may be obtained by commonly spreading the subpixels V1 and V2 in common.

In some embodiments, the device 2000 may further include a subpixel comprising additional black or white particles adjacent to the subpixels V1, v2. In addition, one of ordinary skill in the art will appreciate from the present disclosure that these black or white particles can be selectively dispersed within each cell V1, V2 or selectively for only one cell.

For convenience of explanation, it is assumed that the red and blue particles 100R and 100B (PR and PB) are charged with + and the green particles 100G (PG) are charged with-. As in FIGS. 4A and 4B, a potential is applied to individual electrodes, and each color particle may be distributed as shown in FIGS. 5A and 5B.

As shown in FIG. 5A, when particles 100R, 100G, 100B comprising light reflective subparticles and a color layer having a controlled thickness are used in accordance with an embodiment of the invention, The light reflectivity of the particles is increased so that sufficient color reproducibility can be obtained from the dyed color layer. In addition, even if the dielectric solution U is transparent, the light immersion of the green particles 100G may be suppressed due to the light shielding force by the reflective sub-particles having the adjusted size.

On the contrary, in FIG. 5B of the comparative example, since resin-based color particles having a polymer body or a polymer matrix having a weak light shielding power were used, part of the incident light i was absorbed or transmitted by the particles, and thus reflected light ( iR ', iB') are reduced in size. Thus, not only the contrast of display information is reduced, but also the color reproducibility is lowered. In addition, when the dielectric solution U is transparent, the green particles PG, which should not be visible to the observer 1 by the transmitted light iT, may be projected to lower the color reproducibility.

In the above, the features and advantages of embodiments of the present invention have been described with respect to an electrophoretic display device having a partition structure, but the microcapsule structure, the microcup structure, or other various types of cavity structures and polymer dispersed structures are also described. It is obvious that it is included in the scope of. Also included in the present invention is a dry electrophoretic display device using a dielectric gas as well as a dielectric solution as the fluid inside the cell.

Although the above-described embodiments disclose an electrophoretic display device as a finished product, only a layer (also referred to as an image media layer or an image sheet) referred to as 70 in FIGS. 4A to 5B may be manufactured separately from the driving element. The image media layer includes a support substrate to be an upper substrate, which is a carrier substrate, and subpixels formed of the aforementioned capsules, microcups, cavities, partitions, and the like formed on the support substrate, and within the subpixels, a dielectric fluid. And the aforementioned particles dispersed therein.

After completing the image media layer, the electrophoretic display apparatus 1000 as shown in FIG. 4A may be provided, for example, by bonding to the lower substrate 10 on which the driving element 50 is formed using an adhesive layer. have.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and alterations are possible within the scope without departing from the technical spirit of the present invention, which are common in the art. It will be apparent to those who have knowledge.

Claims (27)

1. Light reflective subparticles; And

   Electrophoretic particles for multi-color display comprising a color layer surrounding the light reflective sub-particles.
2. The method of claim 1,

   The electrophoretic particles are electrophoretic particles, characterized in that having a size in the range of 0.05 ㎛ to 2 ㎛.
3. The method of claim 1,

   And the light reflective subparticles have a size adjusted to obtain light shielding.
4. The method of claim 1,

   And the light reflective subparticles comprise a single particle core.
5. The method of claim 4, wherein

   The single particle core is electrophoretic particles, characterized in that having a size of 0.01 ㎛ to 1 ㎛.
6. The method of claim 4, wherein

   The single particle core is electrophoretic particles, characterized in that having a size of 0.05 ㎛ to 0.8 ㎛.
7. The method of claim 4, wherein

   The single particle core is electrophoretic particles, characterized in that having a size of 0.2 ㎛ to 0.8 ㎛.
8. The method of claim 1,

   The thickness of the color layer is electrophoretic particles, characterized in that the particles are selected to have a specific gravity equal to the specific gravity of the dielectric solution to be dispersed.
9. The method of claim 1,

   The light reflective subparticle includes a plurality of reflective particles,

   The size of the plurality of reflective particles, characterized in that the ratio (S1 / S2) of the cross-sectional area (S1) in the radial direction of the particle and the radial cross-sectional area (S2) of the reflective particles is selected to be 2 or more and 100 or less Electrophoretic particles.
10. The method of claim 1,

    The light reflective sub-particles are electrophoretic particles, characterized in that it comprises a white inorganic particles.
11. The method of claim 10,

    The white inorganic particles include titanium oxide, antimony trioxide, zinc sulfide, zinc oxide, barium sulfate, barium titanium oxide, kaolin (kaolun), silicon oxide (silica), calcium oxide (calcium oxide), calcium carbonate (CaCO ₃ ), or electrophoretic particles comprising a mixture composition thereof.
12. The method of claim 1,

    The light reflective subparticles are electrophoretic particles, characterized in that it comprises a metallic particle.
13. The method of claim 12,

    The metal-based particles are electrophoretic particles, characterized in that any one or a combination of silver nanoparticles, platinum nanoparticles and aluminum nanoparticles.
14. The method of claim 1,

    The color layer is electrophoretic particles comprising a composition comprising a binder resin and a dye having a predetermined color dispersed in the binder resin.
15. The method of claim 14,

    The binder resin comprises electrophoretic particles having affinity for the surface of the light reflective subparticles.
16. The method of claim 15,

    The reactive group may be an epoxy group, a thioepoxy group, a silanol group, a silylol group, an alkylamino group, an aziridin group, an oxazin group, an isocyanate group. Electrophoretic particles, characterized in that it comprises any one or a combination thereof).
17. The method of claim 14,

    The concentration of the dye with respect to the binder resin is electrophoretic particles, characterized in that 1% by weight or more and 70% by weight or less.
18. The method of claim 1,

    Wherein said color layer comprises a layer of dye material adsorbed to have physical, chemical, or both properties relative to the surface of said light reflective subparticles.
19. The method of claim 1,

    And the light reflective subparticles comprise light shielding pigment particles.
20. The method of claim 19,

    Electrophoretic particles, characterized in that the color of the color layer and the pigment single particles are the same.
21. The method of claim 1,

    The color layer is any one of red, green and blue, or any one of magenta, cyan and yellow electrophoretic particles.
22. A plurality of cavities disposed between the substrates facing each other;

    A dielectric fluid defined within the plurality of cavities; And

    A multi-color electrophoretic display device comprising the electrophoretic particles of any one of claims 1-21 dispersed in the dielectric fluid.
23. The method of claim 22,

    And said dielectric fluid is transparent.
24. The method of claim 22,

    An electrophoretic display device, characterized in that only the electrophoretic particles having any one type of color are commonly dispersed in adjacent cavities among the plurality of cavities.
25. The method of claim 24,

    Electrophoretic display device, characterized in that the color of the commonly dispersed electrophoretic particles are green.
26. A plurality of cavities disposed between the support substrates facing each other;

    A dielectric fluid defined within the plurality of cavities; And

    An image sheet comprising particles of any of the preceding claims, dispersed in the dielectric fluid.
27. The method of claim 26,

    And the dielectric fluid is transparent.

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