JP2003315845A - Electrophoretic display panel and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophoretic display panel which has excellent contrast and which is capable of plural color display or full color display of high precision and high grade since there is a problem of insufficient contrast due to presence of only one particle in a partition wall in a conventional electrophoretic display body. <P>SOLUTION: In the electrophoretic display panel which has an electrophoretic liquid constituted of an electrophoretic particle and an insulating liquid in a region surrounded by the partition wall formed on a base material, the electrophoretic liquid in each region consists of two or more kinds thereof. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophoretic display panel utilizing an electrophoretic phenomenon caused by application of an electric field of electrophoretic particles dispersed in an insulating liquid, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Portable information devices such as mobile phones and portable information terminals have been developed in various forms. Among them, a display body using a liquid crystal is often used as an information display system. However, the display using this liquid crystal has problems such as a narrow viewing angle, difficulty in viewing information contents due to flickering of the backlight, and a burden on the viewing angle. On the other hand, a reflective liquid crystal display that does not use a backlight has a problem that the display screen becomes dark due to the use of a polarizing plate and thus the visibility is lowered.

In the future development of mobile phones, personal digital assistants, and electronic books, there is a demand for a display having good visibility and low power consumption without burdening the viewing angle even when used for a long time. ing.

As one of the means for solving these problems, an electrophoretic phenomenon generated by applying an electric field to electrophoretic particles dispersed in a dispersion medium as disclosed in Japanese Patent Publication No. 50-15115 is utilized. Electrophoretic display bodies are generally known.

Most of the conventional electrophoretic displays are monochrome displays.
In the case of multicolor, it is necessary to arrange electrophoretic particles in arbitrary pixels, and it is difficult to manufacture a multicolor electrophoretic display body.

As a multicolor display body, a structure in which color filters are stacked on monochromatic electrophoretic particles is known.
Further, as an electrophoretic display member capable of multicolor display, there is one as disclosed in Japanese Patent Laid-Open No. 2001-235771.

In this electrophoretic display, colored barrier particles formed on the substrate are filled with colored electrophoretic particles and a colored insulating liquid, and the electrophoretic particles have an insulating property. A multicolor display is provided by coloring the liquid in any color.

[0008]

However, the above electrophoretic display has a problem that there is no contrast because the number of particles present in the partition is one. The present invention has been made in view of solving the above problems, and an object thereof is to provide an electrophoretic display panel capable of high-definition and high-quality multi-color or full-color display with excellent contrast. It is in.

[0009]

As means for solving the above-mentioned problems, in the present invention according to claim 1, an electrophoretic liquid composed of electrophoretic particles and a liquid having an insulating property is provided on a substrate. In an electrophoretic display panel having an area surrounded by partition walls formed in, an electrophoretic display panel characterized in that each area has two or more kinds of electrophoretic particles is provided. is there.

In the present invention according to claim 2, the electrophoretic particles in each of the regions are composed of two kinds,
The electrophoretic display panel according to claim 1, wherein the electrophoretic display panels have opposite polarities.

In the present invention according to claim 3, the electrophoretic particles in each of the regions are composed of two kinds,
3. The electrophoretic display panel according to claim 1, wherein one of the liquids has a white color and the other has a color other than white, and the insulating liquid is colorless.

In the present invention according to claim 4, the electrophoretic particles in each of the regions are composed of two kinds,
3. An electrophoretic display panel according to claim 1, wherein one is black and the other is a color other than black.

Further, in the present invention according to claim 5, an electrophoretic liquid composed of a liquid having an insulating property with electrophoretic particles is provided in a region surrounded by partition walls formed on a substrate. A method for manufacturing an electrophoretic display panel, which comprises filling two different types of electrophoretic liquids in respective regions surrounded by the base material and the partition wall. It is a thing.

Further, in the present invention according to claim 6, two kinds of electrophoretic liquids having different properties filled in one region surrounded by the base material and the partition wall are dispersed in the liquids. The method for manufacturing an electrophoretic display panel according to claim 5, wherein the particles have opposite polarities, and the liquid having an insulating property is the same liquid.

Further, in the present invention according to claim 7, in the two kinds of electrophoretic particles in each of the regions, one having a white color and the other having a color other than white and having an insulating property is A method for manufacturing an electrophoretic display panel according to claim 5 or 6, which is colorless.

In the present invention according to claim 8, one of the two types of electrophoretic particles in each region is black and the other is a color other than black. A method of manufacturing the electrophoretic display panel according to item 6.

Further, in the present invention according to claim 9, when the two kinds of electrophoretic liquids having different properties are filled in one region surrounded by the base material and the partition wall, the electrophoresis to be filled is performed. A polarity opposite to that of the electrophoretic particles dispersed in the liquid is applied to the substrate side.
A method for manufacturing an electrophoretic display panel according to item 6, 7 or 8 is provided.

According to the tenth aspect of the present invention, the electrophoretic liquid is not mixed with the electrophoretic liquid as an enclosed liquid in the region surrounded by the base material filled with the two types of electrophoretic liquids having different properties and the partition wall. A method of manufacturing an electrophoretic display panel according to claim 5, 6, 7, 8 or 9, wherein a liquid is used.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 shows a substrate 4 having a transparent electrode layer 3 and a transparent electrode layer in an electrophoretic display panel according to the present invention.
It shows the step of filling two kinds of electrophoretic liquids 12, 22, 32, 42 of different properties using the discharging device 10, 20, 30, 40 in the partition wall 2 formed on 3. The manufacturing process will be described step by step.

First, in a region surrounded by partition walls 2 formed on a base material 4 provided with a transparent electrode layer 3, a liquid 1 having an insulating property and a first liquid having a positive charge at a first discharge position 13 are formed. A first electrophoretic liquid 12 containing electrophoretic particles 11 is ejected into the partition wall 2 by a first ejection device 10.

Next, at the second ejection position 23, a liquid 1 having an insulating property and a second electrophoretic particle 21 having a negative charge are included.
2 The electrophoretic liquid 22 is ejected toward the inside of the partition wall 2 by the second ejection device 20.

For example, when displaying two colors of black and white, the white first electrophoretic particles 11 dispersed in the first electrophoretic liquid 12 are, for example, titanium oxide, and the black first electrophoretic particles 11 dispersed in the second electrophoretic liquid 22 are black. Examples of the second electrophoretic particles 21 include carbon.

Further, the electrophoretic particles 11, 21, 31, 41 used in the electrophoretic display panel of the present invention are composed of two kinds of electrophoretic particles 21, 31, 41 filled in a region surrounded by partition walls. Any electrophoretic particles 11,21,31,41 can be used provided they have opposite polarities.

As used herein, the type of electrophoretic particles means that they have different properties such as electrophoretic properties in addition to polarity.

In the case of multicolor display, for example, an electrophoretic liquid having electrophoretic particles 11 colored white at the first ejection position 13.
Electrophoretic liquid 22, 32, in which 12 are filled in all partition walls 2 and electrophoretic particles 21, 31, 41 colored in any color are dispersed.
This can be realized by shooting 42 into the arbitrary partition wall 2 by the discharging devices 20, 30, 40 after the second discharging device 20.

As the discharging device 10, 20, 30, 40 used in the present invention, if the region surrounded by the partition wall 2 formed on the substrate 4 can be filled with the electrophoretic liquid 12, 22, 32, 42. Although any discharging means is possible, it is preferable to use an inkjet method capable of performing precise discharging.

After the two kinds of electrophoretic liquids 52 are filled in the partition walls 2, the encapsulating liquid 5 having the property of not mixing with the electrophoretic liquids 52 is applied by the roll coater 6. At this time, any means may be used as long as the enclosed liquid 5 can be applied uniformly.

FIG. 2 shows that when the electrophoretic liquid 12, 22, 32, 42 is filled in the region surrounded by the partition wall 2 formed on the base material 4, the electrophoretic liquid 12, 22, 32, 42 It was shown that the electrophoretic liquids 12, 22, 32, 42 are densely filled in the partition walls 2 by applying an electric charge opposite to that of the electrophoretic particles 11, 21, 31, 41, which are dispersed on the substrate 4, onto the substrate 4. It is a thing.

More specifically, first, an electric charge opposite to the electrophoretic particles 11 dispersed in the electrophoretic liquid 12 ejected at the ejection position 13 is applied on the base material 4 by the application device 14, whereby the partition 2
The electrophoretic particles 11 dispersed in the electrophoretic liquid 12 filled therein are attracted toward the base material 4 side, so that the corners between the partition walls 2 and the base material 4 are densely packed.

Similarly, by applying an electric charge having a polarity opposite to that of the electrophoretic particles 21 dispersed in the electrophoretic liquid 22 ejected at the ejection position 23 onto the base material 4 by the application device 24, The electrophoretic particles 21 dispersed in the electrophoretic liquid 22 filled in
The electrophoretic liquid 12 and the second electrophoretic liquid 22 are intimately mixed.

Further, as the material of the electrophoretic particles in the present invention, zinc white, barium sulfate, chromium oxide, calcium carbonate, gypsum, lead white, manganese violet, carbon black, iron black, navy blue, ultramarine blue, phthalocyanine blue, chromium. Yellow, cadmium yellow, lithopone, molybdate yellow, first yellow, benzimidazoline yellow, flavans yellow, naphthol yellow, benzimidazolone orange, perinone orange, red iron oxide, cadmium red, madareki,
Naphthol red, dioxazine violet red, phthalocyanine blue, alkali blue, cerulean blue,
Emerald green, phthalocyanine green, pigment green, cobalt green, aniline green and the like can be used, but titanium oxide and carbon are preferable.

As the particle size of the electrophoretic particles at this time, a range of 0.1 to 10 μm can be used, and a range of 1 to 5 μm is particularly preferable in terms of contrast.

Further, as the material of the liquid having an insulating property, water or an organic solvent can be used, but it is preferable to use water.

As the electrophoretic liquid, a dispersant can be used as a composition in addition to a liquid having an insulating property with respect to the electrophoretic particles.

In this case, the electrophoretic particles and the insulating particles may be mixed in a weight ratio of 1: 100 to 1: 2.

Further, as the base material, in addition to the structure provided with the transparent electrode layer, the structure provided with a color filter can be used.

The material of the base material itself is glass,
Transparent or opaque materials such as resins are available and preferred.

The material of the transparent electrode layer is IT
O, Sn, Ag, etc. can be used, but ITO is preferable in terms of transparency and conductivity.

As the material of the partition wall, glass, resin, silicon or the like can be used, but glass in which a black pigment is dispersed is preferable in terms of contrast.

Finally, various transparent curable resins can be used as the material of the enclosed liquid, but UV resin is preferable.

[0042]

EXAMPLES The present invention will be described in more detail below with reference to examples.

(Embodiment 1) A case where two-color display of black and white is performed will be described.

First, the transparent electrode layer (material ITO, film thickness 1
0 Å) provided on the base material (material: polyester resin, film thickness: 50 μm), a partition wall (space: 10 μm,
The first electrophoretic particles (material: titanium oxide, particles) having a positive charge and a liquid (composition water) having an insulating property at the first ejection position in a region surrounded by a height of 20 μm, a width of 5 μm, and a material of acrylic resin. A first electrophoretic liquid containing a diameter of 3 μm at a ratio of 100: 1 is ejected into the partition wall by the first ejection device in an amount of 1 × 10 −3 ml.

Next, at the second ejection position, an insulating liquid (same as above) and negative electrophoretic particles (material)
A second electrophoretic liquid containing carbon and a particle size of 3 μm (ratio same as above) is directed into the partition wall by the second discharge device (same above) and discharged in the same amount.

After the filling, an enclosed liquid (material: acrylic resin, film thickness 50 μm) is uniformly applied by a roll coater.

As a result, an electrophoretic display panel is obtained in which the base material provided with the transparent electrode layer and the two types of electrophoretic liquids having different properties are filled in the partition walls formed on the transparent electrode layer. It was

When this electrophoretic display panel is used, the properties differ in the region surrounded by the partition wall formed on the substrate.
Since two types of electrophoretic liquids are filled, the difference when either electrophoretic liquid is drawn can be used as the contrast difference. A color electrophoretic display panel can be easily provided.

(Embodiment 2) The following is the same as Embodiment 1 except that there is no particular description. When the electrophoretic liquid is filled, by applying an electric charge opposite to the electrophoretic particles dispersed in the electrophoretic liquid to the base material 5V, it is possible to densely fill the partition with the electrophoretic liquid. It was

As a result, an electric charge opposite to the electrophoretic particles dispersed in the electrophoretic liquid ejected at the ejection position is applied to the base material by the application device of 30 V, whereby the electrophoretic liquid filled in each partition wall is applied. The electrophoretic particles dispersed therein are attracted toward the base material side, whereby the corners between the partition walls and the base material are densely filled.

Similarly, by applying an electric charge having a polarity opposite to that of the electrophoretic particles dispersed in the electrophoretic liquid ejected at another ejection position onto the base material with an application device, the barrier ribs are filled. The first electrophoretic liquid and the second electrophoretic liquid are intimately mixed by attracting the electrophoretic particles dispersed in the electrophoretic liquid to the base material side.

With this electrophoretic display panel, it is possible to easily provide a multicolor electrophoretic display panel having excellent contrast.

[0053]

As described above, by filling two kinds of electrophoretic liquids having different properties in the region surrounded by the partition wall formed on the base material, a multicolor electrophoretic having excellent contrast can be obtained. A display panel can be easily provided.

[Brief description of drawings]

FIG. 1 is a conceptual cross-sectional view showing a step of filling an electrophoretic liquid, which is one step of a method of manufacturing an electrophoretic display panel according to the present invention.

FIG. 2 is a step of filling the electrophoretic liquid in the partition wall by applying a voltage on the base material in the step of filling the electrophoretic liquid which is one step of the method for manufacturing the electrophoretic display panel of the present invention. It is a conceptual sectional view showing that.

[Explanation of symbols]

1 ... Insulating liquid 2 ... Partition 3 ... Transparent electrode layer 4 ... Base material 5 ... Sealing liquid 6 ... Roll coater 10, 20, 30, 40 ... Ejecting device 11, 21, 31, 41 ... Electrophoretic particle 12, 22, 32, 42 ... Electrophoretic liquid 13, 23, 33, 42 ... Electrophoretic liquid ejecting position 14, 24 ... Electric charge Applying device 52: Two kinds of electrophoretic liquid filled in one partition

Claims (10)

[Claims] 1. An electrophoretic display panel having an electrophoretic liquid composed of electrophoretic particles and a liquid having an insulating property in a region surrounded by partition walls formed on a substrate, in each of the regions. 2. An electrophoretic display panel, characterized in that the electrophoretic particles are composed of two or more kinds. 2. The electrophoretic display panel according to claim 1, wherein the electrophoretic particles in each region are composed of two kinds and have opposite polarities. 3. The electrophoretic particles in each region are composed of two kinds, one of which is white and the other of which has a color other than white,
The electrophoretic display panel according to claim 1 or 2, wherein the liquid having an insulating property is colorless. 4. The electrophoretic display panel according to claim 1, wherein the electrophoretic particles in each of the regions are made of two kinds, one of which is black and the other of which is a color other than black. . 5. A method of manufacturing an electrophoretic display panel, which comprises an electrophoretic liquid composed of electrophoretic particles and a liquid having an insulating property in a region surrounded by partition walls formed on a substrate, Different in each area surrounded by the base material and the partition wall
A method for manufacturing an electrophoretic display panel, which comprises filling two kinds of electrophoretic liquids. 6. Two kinds of electrophoretic liquids having different properties filled in one region surrounded by the base material and the partition wall,
The method for manufacturing an electrophoretic display panel according to claim 5, wherein the electrophoretic particles dispersed in the liquid have opposite polarities, and the liquids having insulating properties are the same liquid. 7. The two types of electrophoretic particles in each region are characterized in that one is white and the other has a color other than white, and the insulating liquid is colorless. 5. The method for manufacturing an electrophoretic display panel according to 5 or 6. 8. The electrophoretic display panel according to claim 5, wherein one of the two types of electrophoretic particles in each region is black and the other is a color other than black. Method. 9. When filling two kinds of electrophoretic liquids having different properties into one region surrounded by a base material and a partition wall, it is opposite to the electrophoretic particles dispersed in the electrophoretic liquid to be filled. 9. The method for manufacturing an electrophoretic display panel according to claim 5, 6, 7 or 8, wherein the polarity of (1) is applied to the substrate side. 10. A liquid which is immiscible with the electrophoretic liquid is used as an encapsulating liquid in a region surrounded by the base material filled with the two types of electrophoretic liquids having different properties and the partition wall. Item 10. A method for manufacturing an electrophoretic display panel according to item 5, 6, 7, 8 or 9.