JP2005156808A - Electrophoretic multicolor display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophoretic multicolor display device, having a porous layer and an insulating liquid with coloring electrophoretic particles dispersed therein. <P>SOLUTION: The electrophoretic multicolor display device is provided, having the porous layer and the insulating liquid with at least one kind or more of the coloring electrophoretic particles dispersed therein between two sheets of substrates which have electrodes, of which at least one is transparent and which are placed opposite to each other with the electrodes being kept in the inside. The porous layer has a coloring part colored with two or more kinds of colors with an optical reflection characteristic different from those of the coloring electrophoretic particles. The multicolor display is carried out, by using one state in which the coloring part is hidden with the coloring electrophoretic particles and the other state, in which the coloring part is not hidden. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  In the present invention, a colored electrophoretic particle is electrophoresed through the pores of the porous layer by applying an electric field to a display device including the electrophoretic colored electrophoretic particle and a porous layer. The present invention relates to an electrophoretic display device that performs display by changing the optical reflection characteristics from the viewing surface by changing the relative distribution positions of particles and a porous layer.

  With the development of an advanced information society, there is an increasing need for display media for visualizing digital information. As a technology for realizing these, self-luminous display technologies such as CRT, liquid crystal, EL, and LED have been developed. In addition to these self-luminous systems, the development of reflective display systems that have low power consumption and little discomfort to the human eye has been studied. As a reflective system, reflective liquid crystal technology was developed as a leading technology. However, there is a great need for a display system that is less uncomfortable in visibility, inexpensive, and lightweight and flexible, such as portability. However, there are currently no promising technologies to achieve this. It is. As candidate techniques, techniques such as electrophoresis, electro-oxidation reduction, and twist ball are known. In particular, the electrophoretic display device is one of the powerful reflective display devices with excellent low power and high-speed response.

  As one of the electrophoretic display devices, an electrophoretic display device comprising electrophoretic colored particles dispersed in a medium and a porous layer having different optical reflection characteristics from the particles is known (for example, (See Patent Document 1). In this method, the colored electrophoretic particles are electrophoresed to change their spatial distribution state, and 1) a state in which the porous layer is concealed by the particles, and 2) a state in which the particles are concealed by the porous layer. Display is performed by changing the optical reflection characteristics in two states.

However, the above-mentioned method can obtain only two color displays, that is, the color of the colored particles and the color of the porous layer, and cannot cope with the recent demand for colorization of display materials. there were.
Japanese Patent Publication No. 50-15120

  The present invention relates to an electrophoretic display device comprising electrophoretic colored particles dispersed in a medium and a porous layer having optical reflection characteristics different from those of the particles. An object is to provide an electrophoretic multicolor display device.

  As a result of studying the porous film, the present inventors have used a porous film having two or more colored portions having different optical reflection characteristics from the colored electrophoretic particles, and the colored portion is the colored electrophoretic particle. It has been found that the object of the present invention can be achieved by performing multicolor display in a state where it is concealed by electrophoretic particles and in a state where it is not concealed, and the present invention has been completed.

  That is, according to the present invention, a porous layer and at least one kind of colored electrophoretic particles are dispersed between two substrates having electrodes that are transparent at least one of them and facing each other with the electrodes facing inside. The porous layer has two or more colored portions having optical reflection characteristics different from those of the colored electrophoretic particles, and the colored portion is the colored electrophoretic display device. Provided is an electrophoretic multicolor display device which performs multicolor display in a state where it is concealed by electrophoretic particles and a state where it is not concealed.

  The present invention enables multicolor display by coloring portions of two or more porous layers in addition to at least the particle color. Furthermore, the particles are colored white, the porous layer is colored cyan, yellow and magenta. An electrophoretic multicolor display device capable of displaying colors can be provided.

The present invention is described in detail below.
[Basic configuration of electrophoretic display]
FIG. 1 shows the basic configuration of the present invention.
The basic configuration of the electrophoretic display device of the present invention is an electrophoresis which is a colored particle that is electrophoresed between two substrates having matrix driving electrodes 2 and 3 which are at least one transparent on a base material 1. Colored particles 5, an insulating liquid 4 in which the electrophoretic colored particles are dispersed, and a porous layer 6 having two or more colored portions (a cyan colored portion 8, a yellow colored 9, a magenta colored 10 colored portion) Having). The electrophoretic multicolor display device of the present invention can be obtained by adhering and sealing the porous layer (spacer and seal 7) via an insulating material serving as a spacer.
A multicolor display method when electrophoretic colored particles are positively charged white particles will be described using this apparatus. FIG. 2 shows a state where the electrode 2 is a cathode. That is, the colored electrophoretic particles that are positively charged white particles migrate to the electrode 2 that is the cathode, and the colored electrophoretic particles between the porous layer 6 and the electrode 3 pass through the holes of the porous layer 6. Gather on electrode 2 which is the cathode. Since the colored electrophoretic particles are white, the colored portions (8, 9, 10) of the porous layer 6 behind the viewing surface are concealed, and from the viewing surface (upper in FIG. 2), the electrode 2 is passed through. Looks white.

Next, FIG. 3 shows a state in which the polarity of only the matrix electrode corresponding to the cyan colored portion is reversed and the electrode 3 is used as a cathode. Since the electrode 3 serves as a cathode, the colored electrophoretic particles (white particles) move to the electrode 3 through the porous layer 6. At that time, only the cyan portion is observed through the electrode 2 from the viewing surface (upper side in FIG. 3), and the yellow coloring portion and the magenta portion, which are other coloring portions, are hidden by the white particles. As a result, only the cyan colored portion is displayed, and blue is seen from the viewing surface. Thus, it is possible to provide a multicolor display system capable of greatly changing the brightness from white to multicolor by driving the electrode corresponding to the colored portion of the porous layer so that a voltage can be applied. it can.
As a driving method for applying a voltage to the matrix electrode, a publicly known method can be applied. Regardless of a static driving method or a time-division driving method, an active driving represented by a TFT using a non-linear element. It may be.

[Electrophoretic colored particles]
The electrophoretic colored particles 5 used in the present invention may be either positive or negative, but can be electrophoresed by having any charge. In addition, when the electrophoretic colored particles are arranged on the upper surface of the porous layer, it is required that the porous layer can be concealed by the particles because the color of the particles needs to be the display color of the display surface. Therefore, the electrophoretic colored particle group used in the present invention is required to have a coloring power enough to conceal the porous layer.

(Particle size)
Moreover, since the particle diameter of the electrophoretic colored particles goes back and forth in the porous layer, it must be smaller than the opening diameter of the porous layer. Since the aperture diameter of the porous layer that also falls within the meaning of the present invention is too large, the reflected light of the porous layer does not sufficiently reflect the color of the porous layer. According to the same, it is desirable that it is smaller. Furthermore, from the viewpoint of dispersion stability in the medium, it is desirable that the particle diameter of the electrophoretic colored particles is smaller. Therefore, the particle diameter of the electrophoretic colored particles is preferably smaller as long as the concealability can be maintained, specifically 10 n (nano) m to 10 μm, more preferably 50 nm to 1 μm.

(Coloring)
The color of the electrophoretic colored particles is not particularly limited. However, since the particle color becomes the ground color, white is preferable from the viewpoint of visibility.

(concentration)
The concentration of the electrophoretic colored particles used in the present invention in the dispersion medium is preferably 0.5 to 50% by mass. When the concentration in the dispersion medium is less than 0.5% by mass, it becomes difficult to conceal the porous layer. On the other hand, when the concentration of the electrophoretic colored particles in the dispersion medium exceeds 50% by mass, the dispersion stability is lowered, and problems such as difficulty in migration and aggregation of the particles occur.

(type)
The electrophoretic colored particles used in practice are not particularly limited, but organic pigments, inorganic pigments, dyes, metal powders, colored glass, colored fine powders such as resins, or resins containing these colorants. Examples thereof include solid pulverized colored particles and capsule particles. Examples of the organic pigment include azo pigments, polycondensed azo pigments, metal complex azo pigments, flavanthrone pigments, benzimidazolone pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, anthrapyridines. Pigments, pyranthrone pigments, dioxazine pigments, perylene pigments, perinone pigments, isoindolinone pigments, quinophthalone pigments, thioindigo pigments, and indanthrene pigments.
Examples of inorganic pigments include zinc white, titanium oxide, zinc oxide, zirconium oxide, antimony white, carbon black, iron black, titanium boride, bengara, mapico yellow, red lead, cadmium yellow, zinc sulfide, lithopone, barium sulfide, Examples thereof include cadmium selenide, barium sulfate, lead chromate, lead sulfate, barium carbonate, calcium carbonate, lead white, and alumina white. In particular, titanium oxide is preferred as the white particle pigment particularly preferred in the present invention.

Examples of the dye include nigrosine dyes, phthalocyanine dyes, azo dyes, anthraquinone dyes, quinophthalone dyes, and methine dyes.
In addition, a mixed system of additives such as these dyes, pigments and dispersants, or encapsulated fine particles made of a mixture of pigments, dyes and resins is also useful.

[Porous layer]
The porous layer of the present invention has two or more colored portions having optical reflection characteristics different from those of the colored particles. Three or more colors can be displayed, but one display picture element uses a porous layer having colored portions divided and colored by three colors of cyan, yellow, and magenta, and is applied to a matrix electrode corresponding to each colored portion. By applying a voltage, the three colors are concealed or not by concealing the three colors with colored electrophoretic particles, thereby enabling multicolor or full color display.

  For example, in the case where the electrophoretic colored particles are arranged on the lower surface of the porous layer, the porous layer 6 is formed of the porous colored layer so that the color of the porous layer becomes the display color of the display surface. Must be concealed. That is, the porous layer must be concealable at a concentration that conceals electrophoretic colored particles.

(Pore diameter)
The porous layer requires an infinite number of pores. The pore size should be such that the porous layer does not impair the color of the layer visually and hides the electrophoretic colored particles. In addition, it is necessary to have a pore size that allows electrophoretic colored particles to smoothly migrate through the pores. The diameter of the porous layer is not particularly limited as long as these conditions are satisfied. However, in order to clearly display the color of the colored portion of the porous film, the pore diameter of the porous layer is preferably 40 μm or less, more preferably 10 μm or less, which is the viewing limit. In addition, the arrangement of the pores is such that even if the pore interval is narrow and the number of pores is too large, the color of the colored portion of the porous layer is impaired. Electrophoretic particles accumulate, and the color of the colored portion of the porous layer is impaired.
Therefore, it is desirable that the pores of the porous layer be spaced apart by 20 to 500 μm in the vertical and horizontal directions.
By reducing the pore diameter according to the present invention, when the number of pores is the same, the total area of the pores can be reduced, so the total reflectance of the porous layer is improved, and the color development of the porous layer is improves.
Moreover, it is preferable that the inner wall of the hole is smooth so that the electrophoretic coloring particles do not get caught on the inner wall of the hole when going through the hole. For this reason, it is preferable that it is an orthogonal through-hole. Furthermore, since it is possible to reduce the adhesion of the colored particles, it is preferable that the hole has an inclined structure in which the shape of the hole is inclined downward on the mortar.

(Layer thickness)
As the thickness of the porous layer used in the present invention increases, the hiding property of the electrophoretic colored particles increases. However, if the thickness is too thick, the electrophoretic colored particles migrate slowly through the pores and adhere to the porous layer. 10 to 500 μm is preferable.

(Production method of porous layer)
The production method is not particularly limited as long as the porous layer of the present invention has two or more colored portions having different optical reflection characteristics from the colored electrophoretic particles. For example, the porous layer is printed on a transparent or colored film. For example, a method of processing micropores with a laser beam or the like in a color film obtained by printing the ink in several times by a technique, and the like can be mentioned. The polymer film before forming the colored portion is preferably colored with a white background or the like in order to develop a sharp color when forming the multicolored colored portion.
A method for producing a porous layer having pores having a pore diameter of 40 μm or less is not particularly limited, but laser processing using an excimer laser or the like is suitable.
Although the material which forms a porous layer is not specifically limited, Resin etc. which can form a film | membrane are mentioned. Examples of the resin polymer actually used include acrylic (styrene) resin, urethane resin, polyether sulfone resin, and polyester resin.
Colorants such as pigments and dyes are kneaded in advance with these resins to form a film, which is then colored by a printing method or the like, and then a desired porous layer is obtained by opening 40 μm holes with a laser processing machine.

(Sheet)
In the multicolor display device of the present invention, since the surface of the porous layer having a colored portion becomes a multicolor display surface, if the gap thickness between the porous layer and the electrode is too wide, only when viewed from an oblique direction, Due to the fact that the colored portion of the porous layer that should have been concealed with the colored electrophoretic particles can be seen, the display image is disturbed. Therefore, it is preferable that the distance between the porous layer and the electrode is as narrow as possible with a thickness within a range in which the colored electrophoretic particles can be concealed.

[Insulating liquid: colored electrophoretic particle dispersion medium]
The insulating liquid that is the dispersion medium for colored electrophoretic particles in the dispersion is a transparent and low-viscosity insulating liquid, and it is sufficient that the colored electrophoretic particles are well dispersed. Examples thereof include various animal and vegetable oils, silicone oil, organic solvents, and the like. If the viscosity of the insulating liquid is too high, the response speed decreases, and the power consumption increases to compensate for it. This greatly affects the response speed and power consumption when the particles are electrophoresed. Therefore, the viscosity is preferably from 0.5mm ² / sec~100mm ² / sec.

(Other additives)
The dispersion system is not necessarily composed only of electrodes, colored electrophoretic particles, and a porous layer. If necessary, a charge control material, a dispersion stabilizer, a viscosity adjuster, a surfactant, a resin, an electrolyte, etc. You may add.

[substrate]
The substrate is composed of an electrode and a base material.
(electrode)
In a normal display recording application, since the display only needs to be observed from one side, it is sufficient that one of the electrodes 2 and 3 is transparent. For example, the electrode 3 may be opaque. As the transparent electrode, generally known transparent electrodes such as ITO, ATO, FTO, and AZO can be used.
Further, when observing the display, since the dispersion system is viewed through the transparent electrode, it is desirable that the transparency of the transparent electrode is higher, and the transmittance is preferably 75% or more, more preferably 80% or more. is there. Further, the resistance value of the electrode is desirably smaller, preferably 100 ohms or less, more preferably 50 ohms or less.
The electrode is made porous by electrophoresing colored electrophoretic particles toward the viewing surface, concealing the colored portion of the porous layer, or electrophoresing colored electrophoretic particles onto the electrode opposite to the viewing surface. It has a role to make the colored part of the layer visible. For this reason, it is preferable that an electrode has the position and magnitude | size which can conceal the coloring part of a porous layer. Specifically, it is preferable that at least the electrode is arranged at a position where the colored portion of the porous layer on the back surface overlaps when viewed from the viewing surface.

(Base material)
In general, the base material holding the transparent conductive material of the electrode is glass or a polymer film, and any of them can be used. However, considering that the display device can be given flexibility, a polymer film or a thin film can be used. More desirable is a layer glass.
In addition, one or both of the conductive materials of the electrodes 2 and 3 may be divided and etched into a matrix shape such as a line or a point, or a segment shape. These lines or dot electrodes are combined to form a predetermined shape such as letters, numbers, images, etc., and a voltage is applied to these electrodes at the same time, or a voltage is applied in a time-division manner by scanning, and still images or moving images Can be displayed.

[spacer]
The spacer 7 needs to be an insulating material in order to be disposed between the electrodes. The material is not particularly limited, but a polymer film is desirable in consideration of flexibility and adhesiveness with an adhesive. The shape of the spacer is not particularly limited, but the role of evenly dispersing the dispersion system by, for example, forming a grid to prevent unevenness of the particle concentration due to movement of the colored electrophoretic particles in the display device, etc. A shape having it is more preferable.

In addition, since the spacer gives a thickness for disposing the dispersion system, the thickness is determined by the necessary thickness of the concealing layer of the colored electrophoretic particles and the particle concentration of the dispersion system. However, since the power consumption increases when the spacer is thick, it is desirable that the spacer is thinner.
The display recording apparatus of the present invention can be obtained by bonding the spacer to the electrode or the porous layer with an adhesive or the like, or adding the spacer to the sealing material to bond the substrate and the porous layer.

(Preparation Example 1) <Preparation of porous layer having colored portion>
In a solution of 10 parts of SUMIKAEXCEL PES4800P (polyethersulfone, manufactured by Sumitomo Chemical Co., Ltd.) in 50 parts of n-methylpyrrolidone, 1 part of CR-24 (methyl siloxane-modified titanium oxide by Sakai Chemical: particle size 200 μm) And then kneaded with PT-3100 (KINEMATICA Polytron rotor / stator type homogenizer) for 5 minutes. The obtained kneaded material was coated on glass with a 400 μ applicator and dried at 150 ° C. for 2 hours. A white polyethersulfone film having a film thickness of 75 μm was obtained by peeling the coating film from the glass. Next, LS-34TVA (screen printing machine manufactured by Neurong Seimitsu Kogyo Co., Ltd.) was used for the obtained white film, and a mass of 3 mm in length and 1 mm in width was 3.5 mm in width and 0.5 mm in length with cyan ink. They were applied at intervals and dried at 100 ° C. for 5 minutes. The yellow ink is applied in the same manner from the colored portion to which the cyan ink is applied to the portion spaced 0.5 mm vertically, and this is applied in the same manner with magenta ink, so that 3 mm square cyan, yellow, magenta A polymer film having a multicolored colored portion in which repeated patterns of segments colored in order were arranged and colored at intervals of 0.5 mm up and down was obtained.
Film having a colored portion of the resulting multicolor using laser pro (Com Net Co. CO ₂ laser processing machine), the pore diameter of 50 [mu] m, the porous having a colored portion of the three primary colors by opening the pores of the hole pitch 200μm A layer was obtained.

(Preparation Example 2) <Preparation of white electrophoretic particle dispersion (silicon oil)>
1 part of CR-24 (manufactured by Sakai Chemical Co., Ltd., methylsiloxane modified titanium oxide: particle size 200 μm), 7 parts of KF-96-10 (methyl phenyl silicone oil manufactured by Shin-Etsu Chemical: viscosity 10 mm ² / sec), X-22 (manufactured by Shin-Etsu Chemical) 3 parts of carboxyl group-containing silicon oil), KP-545: 0.5 part of acrylic silicone dispersant (manufactured by Shin-Etsu Chemical Co., Ltd .: alkyl acrylate copolymer methylpolysiloxane) is stirred and mixed. Obtained.

(Example 1)
A PET film with a film thickness of 100 μm, in which the middle is pulled out, leaving two 2 mm wrinkles on the upper and lower sides of the porous layer having the colored portions of the three primary colors of polyethersulfone obtained in Preparation Example 1, is adhered and adhered. In addition, an ITO glass having a width of 3 mm and a linear matrix etched to a spacing of 0.5 mm is further provided below, and a linear matrix having a width of 0.8 mm and a spacing of 200 μm is spaced every 0.5 mm. It was sandwiched between etched ITO glasses and fixed by adhesion. The white electrophoretic particle silicone oil dispersion obtained in Preparation Example 3 was injected into the space, and an electrophoretic display device was obtained. The electrophoretic display device thus obtained was displayed in blue by applying a positive scanning voltage of 30 V every third to the third, and applying a negative scan every second to the third. Next, in the same manner, the second line was positively applied, and the first and third lines were negatively applied to display red. Similarly, the third line was displayed with a red color by applying a plus voltage to the first line and the minus line for the first and second lines.

  The electrophoretic display device of the present invention is very useful as a reflective display device capable of color display.

It is a schematic block diagram which shows an example of the electrophoretic multicolor display apparatus of this invention. FIG. 3 is a diagram in which colored electrophoretic particles are collected on the transparent electrode 2 of the electrophoretic multicolor display device of the present invention. It is the figure which performed blue display with the electrophoresis multi-color display apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Transparent electrode 3 Electrode 4 Insulating liquid: Colored electrophoretic particle dispersion medium 5 Colored electrophoretic particle 6 Porous layer 7 Spacer 8 Cyan colored part 9 Yellow colored part 10 Magenta colored part

Claims (5)

A porous layer, and an insulating liquid in which at least one kind of colored electrophoretic particles are dispersed, between two substrates each having at least one transparent electrode and facing each other with the electrode inside An electrophoretic display device, wherein the porous layer has two or more colored portions having different optical reflection characteristics from the colored electrophoretic particles, and the colored portions are concealed by the colored electrophoretic particles. An electrophoretic multi-color display device that performs multi-color display according to a state in which the display is not concealed. 2. The electrophoretic multicolor display device according to claim 1, wherein two or more colored portions of the porous layer have three colors of cyan, yellow, and magenta, and the colored electrophoretic particles are white. The electrophoretic multicolor display device according to claim 1, wherein the electrophoretic colored particles have an average particle diameter of 10 nm to 10 μm. The electrophoretic multicolor display device according to claim 1, wherein the pores of the porous layer are direct through-holes having a pore diameter of 40 μm or less. The electrophoretic multicolor display device according to claim 1, wherein the shape of the pores of the porous layer is an inclined structure.

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