JPH08190352A - Color display - Google Patents

Abstract

(57) [Summary] [Object] To obtain a color display device capable of controlling an image by applying an electric field arrangement effect of an electro-sensitive optical functional fluid composition. An image element 10 of a color display device is an electrical device in which a transparent electrically insulating medium 5 contains solid particles 6 having an electric field array effect between two opposing transparent electrode plates 1a and 1b. It is filled with the sensitive optical functional fluid composition 4, and the solid particles 6 and the electrically insulating medium 5 are colored in different colors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses an electrosensitive optical functional fluid composition (hereinafter referred to as "EA fluid") and applies an electric field array effect (hereinafter referred to as "EA effect") to display an image. The present invention relates to a color display device that can be controlled.

[0002]

2. Description of the Related Art A liquid crystal display device has been well known as a display device for displaying a color moving image by using backlight illumination. In this liquid crystal display device, a large number of image elements each having a liquid crystal composition filled between two transparent electrode plates are juxtaposed on the same surface. In the case of a color liquid crystal display device, one of the transparent electrode plates is a color electrode. The transparent electrode plates of adjacent image elements which are colored by a filter or the like are colored in mutually different colors.

[0003]

However, liquid crystal display devices have various problems and their applications are limited. To give an example of these problems, for example, the contrast of light and dark is generally low, the expression of pure black is insufficient, the clear viewing angle is narrow, and a large screen cannot be obtained due to structural difficulties in manufacturing. It is not good for outdoor use. Therefore, there is a strong demand for a color display device that overcomes these problems.

On the other hand, the inventors of the present invention are conducting research on an EA fluid having a novel electric field arranging property which has hitherto been unknown. This EA fluid is a fluid obtained by dispersing solid particles having an EA effect (hereinafter referred to as “EA particles”) in an electrically insulating medium, and when an electric field is applied to the EA fluid, the EA particles cause dielectric polarization, Further, they have the property of exhibiting a chain structure by being coordinated and aligned with each other in the direction of the electric field by electrostatic attraction due to dielectric polarization. In addition, some EA particles have electrophoretic properties, and thus have a property of exhibiting an array lump structure by being electrophoresed and arrayed on the electrode plate portion when an electric field is applied.

Therefore, when the EA fluid is filled between two transparent electrode plates, the EA particles are randomly dispersed in the medium when an electric field is not applied to the both transparent electrode plates, so that they are opaque. However, it was found that when an electric field is applied, EA particles are arranged between both electrode plates to form a chain body perpendicular to the electrode plate surface, and as a result, light is transmitted through this EA fluid. Therefore, this system can be used as an image element of a display device in which the screen changes to transparent / opaque in response to turning on / off of an electric field. The present invention has been achieved as a result of earnest research based on the above findings, and therefore an object of the present invention is to provide a liquid crystal display as described above, which is capable of controlling a color image by applying the characteristics of an EA fluid. An object of the present invention is to provide a display device that solves the problems of the device and the like.

[0006]

The above object is to fill an EA fluid containing EA particles in a transparent electrically insulating medium between two transparent electrode plates facing each other.
The problem can be solved by providing a color display device (hereinafter, simply referred to as “display device”) having an image element in which particles and an electrically insulating medium are colored in different colors. At least one of the electrode plates preferably has two or more transparent electrode layers arranged in a non-contact manner with each other.

According to the present invention, two or more of the above-mentioned image elements are arranged in parallel on the same plane, and at least one of the EA particles and the electrically insulating medium of each adjacent image element has a different color. A colored display device is provided. The EA particles in the EA fluid include a core made of an organic polymer compound and an inorganic substance having an EA effect (hereinafter referred to as “E”).
It is preferable that the inorganic-organic composite particles are formed by a surface layer containing "A inorganic substance"). Where EA
The color of the particles includes white and black, and coloring includes the use of the color of the material itself.

[0008]

When the electric field is not applied between the transparent electrode plates, the image element looks colored and opaque because the colored EA particles are randomly dispersed in the medium. When an electric field is applied, the EA particles are arranged between the electrode plates to form a chain or array lump (hereinafter, these are collectively referred to as “chain”) perpendicular to the electrode plate surface. Light will be transmitted. At this time, if the electrically insulating medium is colored, the backlight light is colored by transmitting the light, and color transmitted light is obtained. Therefore, in this image element, the screen changes to colored transparent / colored opaque in response to the turning on / off of the electric field. On at least one of the transparent electrode plates,
If two or more transparent electrode layers arranged in non-contact with each other are formed, when an electric field is applied between the electrode layers on the same plane, a chain-like body parallel to the electrode plate surface is formed. As a result, the image element changes to colored opaque.

[0009]

The present invention will be described in more detail with reference to the following examples. (Embodiment 1) The display device of Embodiment 1 is shown in FIGS.
The image element 10 shown in FIG. In FIG. 1A, the image device 10 includes two opposing transparent electrode plates 1a-1b.
It consists of a cell filled with EA fluid 4 between. The transparent electrode plates 1a and 1b each consist of two layers, the inner layers in contact with the EA fluid 4 are transparent electrode layers 2a and 2b, respectively, and the outer layers are transparent glass layers 3a and 3b, respectively. The EA fluid 4 is composed of EA particles 6 colored in blue dispersed in a transparent electrically insulating medium 5 colored in yellow. Wirings 7a and 7b are respectively drawn from the electrode layers 2a and 2b, and these wirings are connected to the switch 8
And a switching circuit composed of a power supply 9. Further, a backlight BL is provided on one transparent electrode plate 1b side of the image element 10.

FIG. 1A shows a state in which the switch 8 is off. When the switch 8 is off, the blue EA particles 6 are randomly dispersed in the EA fluid 4, so even if the backlight BL is turned on, the light is blocked by the EA particles 6 and the image element 10 is blocked. To the observer obs who does not transmit and sees from the transparent electrode plate 1a side, a green-blue color in which the blue color of the EA particles 6 and the yellow color of the electrically insulating medium 5 are mixed is seen.

When the switch 8 is turned on, both electrode layers 2a
When an electric field is applied between −2b, the EA particles 6 are vertically arranged between the electrode layers 2a and 2b due to the EA effect due to the electric field, and the chain-shaped bodies 11 are spaced apart from each other, as shown in FIG. 1 (b). To form. As a result, the gap portion of the chain 11 is E
Since the A particles do not exist and only the yellow transparent electrically insulating medium 5 is present, the light of the backlight BL can be transmitted through the image element 10.

At this time, since the color of the electrically insulating medium 5 is yellow, the observer obs can see yellow light. That is, when viewed from the observer obs side, the display element 10 lights up in yellow by turning on the switch 8. When the switch 8 is turned off, the EA particles 6 are returned to the random dispersion state again, the light of the backlight BL is blocked, the display element 1 is turned off, and when the observer obs side also has a light source, the EA fluid It returns to the green-blue opaque surface that exhibits the green-blue color of the reflected light. As described above, the display device of Example 1 having the display element 10 can repeat the change of the yellow light surface / green-blue opaque surface by turning on / off the electric field, and can be used, for example, as a display device of a caution signal. You can

The yellow electrically insulating medium 5 used in the display device of Example 1 is obtained by dissolving a yellow oil-soluble dye in dimethyl silicone oil which is an electrically insulating medium.
As shown in FIG. 2, the A particles 6 are inorganic / organic composite particles (6) formed by a core body 6a made of an organic polymer compound and a surface layer 6b containing an EA inorganic substance 6c and a blue pigment 6d. Since the core body 6a of the inorganic-organic composite particles 6 is made of an organic polymer compound, even if the specific gravity of the EA inorganic substance 6c is relatively large, the weight ratio of the core body 6a and the EA inorganic substance 6c can be adjusted at the time of production. The specific gravity can be approximated to the specific gravity of the electrically insulating medium 5, so that it can be well dispersed in this medium. Further, since the surface layer 6b contains a blue pigment, the EA inorganic substance 6c
Can be, for example, white particles even if they are white.

(Embodiment 2) The image element in the display device of embodiment 2 is the same as that of embodiment 1 except that the structure of the transparent electrode plate and the electric circuit associated therewith are different. Therefore, here, the configurations of the transparent electrode plate and the electric circuit will be mainly described.
FIG. 3 shows the configuration of the transparent electrode plate of the image element 20 and the electric circuit in this embodiment. On one transparent electrode plate 21a of the image element 20, a comb-shaped transparent electrode layer (hereinafter referred to as "first electrode layer") 22a and transparent electrode layers (hereinafter, referred to as "transparent electrode layers") arranged in non-contact with each other. 22 c of “second electrode layers” are formed in a mutually nested manner, and the other transparent electrode plate 21 b has an electrode layer (hereinafter,
A “counter electrode layer” 22b is formed. Both the transparent electrode plate 21a and the transparent electrode plate 21b are colorless. Although not shown between the two transparent electrode plates, Example 1
Similar to the above, an EA fluid in which blue EA particles are dispersed in a yellow electrically insulating medium is filled.

The electric circuit of the picture element 20 is constructed as follows. The first electrode layer 22a is connected to the (+) side of the power supply 26. The second electrode layer 22c and the counter electrode layer 22b are connected to the respective fixed terminals 23c and 23b of the changeover switch 23. The movable terminal 23 a of the changeover switch 23 is connected to the (−) side of the power supply 26. That is, this electric circuit has a structure in which the first electrode layer 22a is formed by switching the changeover switch 23.
The electric field can be switched and applied between the second electrode layer 22c and the second electrode layer 22c or between the first electrode layer 22a and the counter electrode layer 22b.

The display element 20 operates as follows in combination with the switching circuit. First, when the changeover switch 23 is connected to the counter electrode layer 22b side, an electric field is applied between the first electrode layer 22a and the counter electrode layer 22b. Then, the EA fluid present between the electrode layers forms an electric field between the transparent electrode plates 21a-21b to form a vertical chain, and the display element 20 has a backlight (not shown).
And transmits the illumination light from the device, and lights up in yellow because the electrically insulating medium is colored in yellow.

Next, as shown in FIG. 4, the changeover switch 2
3 is switched to the second electrode layer 22c side, the first electrode layer 2
An electric field is applied between 2a and the second electrode layer 22c. At this time, the EA particles 6 eliminate the vertical chain formed between the transparent electrode plates 21a-21b, and the first electrode layer 22 is removed.
An electric field is arranged between a and the second electrode layer 22c. As a result, the chain-like body 25 parallel to the transparent electrode plate 21a is formed like a blind and serves as a shutter that covers the transparent electrode plate 21a, so that the illumination light from the backlight BL is blocked and the display element 20 is provided.
Looks like green-blue, which is a mixture of the blue color of the EA particles 6 and the yellow color of the electrically insulating medium 5. Further, when the blending amount of the blue particles in the EA fluid is sufficient to cover the transparent electrode plate 21a, the display element 20 exhibits the blue color of the EA particles 6, that is, a blue opaque surface. is there. As described above, in the display device of the second embodiment, the angle of the chain-like body formed in the display element 20 with respect to the transparent electrode plate immediately changes to vertical / horizontal in response to the switching operation of the changeover switch 23. The display device has a rapid change in the light surface / green-blue to blue-opaque surface and a good electric field response.

It goes without saying that the polarities of the first electrode layer 22a, the second electrode layer 22c and the counter electrode layer 22b in Example 2 may be opposite. Although the patterns of the first electrode layer 22a and the second electrode layer 22c are comb-shaped in the second embodiment, the pattern is not limited to this, and two or more transparent electrode layers arranged in a non-contact manner may be used. As long as it has a stripe shape, a spiral shape, or a dendritic shape, any shape may be used. Further, the electric circuit for switching is not limited to that of the second embodiment.

(Embodiment 3) The display device of Embodiment 3 is shown in FIG.
A large number of pixel units 30 shown in (a) and (b) are arranged adjacent to each other on the same plane. As shown in FIG. 5A, the pixel unit 30 includes three image elements 31, 32 and 3 each having an electrode layer having the same structure as that of the second embodiment.
3 are arranged in parallel, and the transparent electrically insulating media contained in these image elements are colored red (R), blue (B), and green (G), respectively. All the EA particles in the three image elements are colored black.

As shown in FIG. 5B, the image element 31,
On one of the transparent electrode plates 34a of 32 and 33,
Comb-shaped transparent first electrode layer 36a for each image element
And transparent second electrode layers 36b that are arranged in non-contact with each other are formed in a nested manner, and on the other transparent electrode plate 34b, a counter electrode layer 36c that is independent for each image element is formed. ing.

Each of the image elements 31, 32 and 33 has a switching circuit independently. In FIG. 5 (b),
Although only the switching circuit of the image element 33 is shown to avoid complication, the same applies to the other image elements 31 and 32. In FIG. 5B, the switching circuits of the image element 33 include changeover switches 37a-37b which are interlocked with each other.
And a power source 38. The first electrode layer 36a is always connected to the (+) side of the power source 38. Changeover switch 37a
Has its movable terminal connected to the (+) side of the power supply 38 to turn on / off the (+) potential supply to the second electrode layer 36b.
The changeover switch 37b has its movable terminal connected to the (−) side of the power source 38, and while the changeover switch 37a is supplying the (+) potential to the second electrode layer 36b, supplies the (−) potential to the counter electrode layer 36c, When the changeover switch 37a cuts off the potential supply to the second electrode layer 36b, the second electrode layer 36
A (-) potential is supplied to b.

Now, in the image element 33, when the changeover switch 37a supplies the (+) potential to the second electrode layer 36b as shown in FIG. 5B, the (-) potential is applied to the counter electrode layer 36c. Black EA particles in the cell 3 as supplied
9 forms a chain 40 perpendicular to the electrode plate between the counter electrode layer 36c and the first electrode layer 36a and the second electrode layer 36b. Therefore, the light of the backlight BL arranged on the transparent electrode plate 34b side passes through the image element 33 and is turned on in green depending on the color of the electrically insulating medium. Image element 31 (R)
Also, if the same switching mode is selected, the image element 31 lights up in red.

The switching circuit of the image element 32 (B) is not shown, but this will be explained by that of the image element 33. The changeover switch 37a connected to the image element 32 (B) is changed over to the second electrode layer 36b (+).
When the potential supply is cut off, the changeover switch 37b supplies the (-) potential to the second electrode layer 36b, and the counter electrode layer 36c is released from the electric field. As a result, an electric field is formed between the first electrode layer 36a and the second electrode layer 36b, so that the EA particles 39 form a chain 41 between them to block light. Therefore, the image element 32 (B) is turned off in black.

When the pixel unit 30 is observed from a sufficient distance when the respective image elements 31, 32 and 33 are in the above switching state, the red light from the image element 31 and the green light from the image element 33 are mixed. And looks yellow. In this way, by combining lighting and extinction of each of the three image elements 31, 32, and 33, the pixel unit 30 can express eight colors including white light color of all lights and black color of all lights. . Therefore, the display device of Example 3 in which a large number of pixel units 30 are arranged can be used as a full-color display device.

In this pixel unit 30, when the switching circuit is provided with means for changing the strength of the electric field applied to each electrode layer, the amount of light transmitted from the backlight BL can be controlled independently for each image element. . As a result, the gradation of each image element can be changed continuously or digitally, so that the pixel unit 30 of the third embodiment can express more colors. The arrangement pattern of each image element in the pixel unit is free. Further, the screen shape of each image element is not limited to a rectangle, and any shape such as a square, a circle, a regular triangle, and a regular hexagon can be adopted.
In the display device of Example 3, the pixel unit is composed of image elements of three colors of R, G and B, and although this combination is preferable for full color display, R, G, and
It may be a combination of three colors other than B, or, in some cases, a combination of two colors or four or more colors.

Next, a preparation example of the EA fluid used in the above-mentioned embodiment will be shown. (Preparation Example 1-EA fluids of Examples 1 and 2) 32 g of titanium hydroxide (general name; hydrous titanium oxide, C-II manufactured by Ishihara Sangyo Co., Ltd.) which is an inorganic ion exchanger, and phthalocyanine blue which is a blue pigment. A mixture with 8 g was used as a surface layer material, and this mixture with 300 g of butyl acrylate, 100 g of 1,3-butylene glycol dimethacrylate and a polymerization initiator was dispersed in 1800 ml of water containing tricalcium phosphate as a dispersion stabilizer. Then, suspension polymerization was carried out at 60 ° C. for 1 hour with stirring. The obtained product was filtered, washed with acid, washed with water and dried to obtain inorganic / organic composite particles. The obtained inorganic / organic composite particles are jet stream agitator (Hybridizer manufactured by Nara Machinery Co., Ltd.)
Agitated with a jet stream at 4000 rpm for 3 minutes,
The surface was polished to obtain blue EA particles composed of inorganic / organic composite particles. The average particle size of the EA particles was 14.0 μm. The EA particles were uniformly dispersed in an electrically insulating medium composed of silicone oil (TSF451 series manufactured by Toshiba Silicone Co., Ltd.) and a yellow oil-soluble dye so as to be 5.0% by weight to obtain an EA fluid.

(Preparation Example 2-EA fluid of Example 3) Black E
A particles were produced in the same manner except that a black pigment was used instead of the blue pigment shown in Preparation Example 1. The EA fluid used for the image element 31 was manufactured by uniformly dispersing the black EA particles in an electrically insulating medium composed of silicone oil and a red oil-soluble dye so as to be 5.0% by weight. Image element 3
2. The EA fluid used for the image element 33 was manufactured in the same manner except that green and blue oil-soluble dyes were used instead of the above red oil-soluble dye.

The EA fluid suitable for use in the display device of the present invention will be described in detail below. This EA fluid is basically a colored solid particle (EA) that has the EA effect.
Any particles may be used as long as they are contained in a colored and transparent electrically insulating medium. But EA
As particularly preferable particles, as shown in FIG. 2, inorganic / organic composite particles formed by a core body made of an organic polymer compound and a surface layer containing an inorganic substance having an EA effect (EA inorganic substance) and a pigment. Is. Since the surface layer of these inorganic / organic composite particles contains EA inorganic material, the EA as a whole particle
Since the core body is made of an organic polymer compound having an effect and the EA inorganic substance has a large specific gravity, the specific gravity of the EA particles can be approximated to that of an electrically insulating medium. An EA fluid having good dispersion stability can be obtained.

Examples of the organic polymer compound that can be used as the above core include, for example, poly (meth) acrylic acid ester, (meth) acrylic acid ester-styrene copolymer, polystyrene, polyethylene, polypropylene, nitrile rubber, Butyl rubber, ABS resin, nylon, polyvinyl butyrate, ionomer, ethylene-vinyl acetate copolymer, vinyl acetate resin, polycarbonate resin, and the like, or a mixture of two or more thereof, or their monomers or oligomers with each other, or other Examples thereof include copolymers and copolycondensates with monomers or oligomers. Further, as the above organic polymer compound, a compound containing a functional group such as a hydroxyl group, a carboxyl group or an amino group can be used, and such an organic polymer compound containing a functional group can enhance the EA effect. Therefore, it is preferable.

The EA inorganic material suitable for use as the surface layer of the inorganic / organic composite particles is an electric semiconductor inorganic material, an inorganic ion exchanger, silica gel, or at least one of these metal-doped, or metal-doped. Regardless of the presence or absence of the above, at least one of these is applied as an electric semiconductor layer on another support.

Examples of preferable electrically semiconductive inorganic substances include (1) metal oxides such as SnO ₂ and amorphous titanium dioxide (manufactured by Idemitsu Petrochemical Co., Ltd.), and (2) metal hydroxides such as (3) Metal oxide hydroxides such as titanium hydroxide and niobium hydroxide, eg FeO
(OH) (goethite) and the like, and inorganic ion exchangers described below can be mentioned. Here, titanium hydroxide means hydrous titanium oxide (made by Ishihara Sangyo Co., Ltd.),
Metatitanic acid (also known as β-titanic acid, TiO (OH) ₂ ) and orthotitanic acid (also known as α-titanic acid, Ti (OH) 2
₄ ) is included.

Examples of inorganic ion exchangers include (4) polyvalent metal hydroxides, (5) hydrotalcites, (6) polyvalent metal acid salts, (7) hydroxyapatite, and (8). ) Nasicon type compound, (9) clay mineral, (1
Mention may be made of 0) potassium titanates, (11) heteropolyacid salts, and (12) insoluble ferrocyanide. These details will be described below.

(4) Hydroxide of polyvalent metal. These compounds are represented by the general formula MO _x (OH) _y (M is a polyvalent metal, x is a number of 0 or more, and y is a positive number), and examples thereof include titanium hydroxide and hydroxide. Zirconium, bismuth hydroxide, tin hydroxide, lead hydroxide, aluminum hydroxide, tantalum hydroxide, niobium hydroxide, molybdenum hydroxide, magnesium hydroxide, manganese hydroxide, iron hydroxide and the like. Here, for example, titanium hydroxide means hydrous titanium oxide (also known as metatitanic acid or β
Titanic acid, TiO (OH) ₂ ) and titanium hydroxide (also known as orthotitanic acid or α-titanic acid, Ti (OH) ₄ )
Both are included, and the same applies to other compounds.

(5) Hydrotalcites. These compounds are represented by the general formula M ₁₃ Al ₆ (OH) ₄₃ (CO) ₃ · 12H ₂ O (M is a divalent metal). For example, the divalent metal M is Mg, Ca or Ni. Some are. (6) Acid salts of polyvalent metals. These are, for example, titanium phosphate, zirconium phosphate, tin phosphate, cerium phosphate,
Chromium phosphate, zirconium arsenate, titanium arsenate, tin arsenate, cerium arsenate, titanium antimonate, tin antimonate, tantalum antimonate, niobium antimonate, zirconium tungstate, titanium vanadate, zirconium molybdate, selenate Examples include titanium and tin molybdate.

(7) Hydroxyapatite. These are, for example, calcium apatite, lead apatite, strontium apatite, cadmium apatite and the like. (8) Nasicon type compound. These include, for example, (H ₃ O) Zr ₂ (PO ₄ ) _{3 and the} like, but in the present invention, a Nasicon type compound in which H ₃ O is replaced with Na can also be used. (9) Clay mineral. These are, for example, montmorillonite, sepiolite, bentonite and the like, with sepiolite being particularly preferred.

(10) Potassium titanates. These are represented by the general formula aK ₂ O · bTiO ₂ · nH ₂ O (a is a positive number satisfying 0 <a ≦ 1 and b is 1 ≦ b ≦ 6.
Is a positive number satisfying n, and n is a positive number), for example, K ₂ · TiO ₂ · 2H ₂ O, K ₂ O · 2TiO ₂ · 2H
_{2 O, 0.5K 2 O · TiO} 2 · 2H 2 O, and K ₂ O ·
2.5 TiO ₂ .2H ₂ O and the like are included. In addition, among the above compounds, a compound in which a or b is not an integer can be easily synthesized by acid-treating a compound in which a or b is an appropriate integer and replacing K with H. (11) Heteropolyacid salt. These are represented by the general formula H ₃ AE ₁₂ O ₄₀ .nH ₂ O (A is phosphorus, arsenic, germanium, or silicon, E is molybdenum, tungsten, or vanadium, and n is a positive number), For example, ammonium molybdophosphate, ammonium tungstophosphate, and the like.

(12) Insoluble ferrocyanide. These are represented by the following general formula M _b-pxa A [E (CN) ₆ ] (M is an alkali metal or hydrogen ion, A is zinc, copper,
Nickel, cobalt, manganese, cadmium, iron (II
I) or heavy metal ions such as titanium, E is iron (I
I), iron (III), cobalt (II) or the like, b is 4 or 3, a is a valence of A, and p is a positive number of 0 to b / a) , For example Cs ₂ Zn
Insoluble ferrocyanine compounds such as [Fe (CN) ₆ ] and K ₂ Co [Fe (CN) ₆ ] are included.

The inorganic ion exchangers (4) to (12) each have an OH group, and some or all of the ions present at the ion exchange sites of these inorganic ion exchangers are different. Those substituted with (hereinafter, referred to as a substitutional inorganic ion exchanger) are also included in the inorganic ion exchanger of the present invention. That, R-M ¹ inorganic ion exchanger described above (M ¹ represents an ion species of the ion exchange sites) is expressed as a part or all of M ¹ in the R-M ^1, the ion exchange reaction below The substitutional type inorganic ion exchanger in which the ion species M ² different from M ¹ is substituted by is also the inorganic ion exchanger in the present invention. xR−M ¹ + yM ² → Rx− (M ² ) y + xM ¹ (where x and y represent the valences of the ion species M ² and M ¹ , respectively). This M ¹ varies depending on the type of the inorganic ion exchanger having an OH group, but when the inorganic ion exchanger exhibits a cation exchange property, M ¹ is generally H ⁺ , and M ² in this case is an alkali metal, Any of the metal ions other than H ⁺ , such as alkaline earth metals, polyvalent typical metals, transition metals or rare earth metals. When the inorganic ion exchanger having an OH group exhibits anion exchange property, M ¹ is generally OH ⁻ , in which case M ² is, for example, I, Cl or S.
CN, NO ₂ , Br, F, CH ₃ COO, SO ₄ or C
It is an arbitrary one selected from general anions other than OH ⁻ such as rO ₄ and complex ions.

Further, regarding the inorganic ion exchanger which has once lost the OH group due to the high temperature heat treatment but becomes to have the OH group again by an operation such as immersion in water, the inorganic ion after the high temperature heat treatment is used. Exchangers and the like are also a kind of inorganic ion exchangers that can be used in the present invention, and specific examples thereof include a Nasicon type compound such as (H ₃ O) Zr ₂
(PO ₄₎ obtained by heating ₃ HZR ₂ (PO _{4) 3} and high-temperature heat treatment of hydrotalcite (500 to 700 ° C.
Those that have been heat treated in). These inorganic ion exchangers can be used not only in one kind but also in many kinds simultaneously as a surface layer. It is particularly preferable to use a hydroxide of a polyvalent metal and an acid salt of a polyvalent metal as the above inorganic ion exchanger.

Examples of the metal-doped EA inorganic material (13) include antimony-doped tin oxide. Metal doping is performed when it is desired to increase the electric conductivity of the EA inorganic material. In addition, examples of (14) in which an EA inorganic substance is applied to another support as an electric semiconductor layer include, for example, inorganic particles such as titanium oxide, silica, alumina, silica-alumina, or polyethylene, polypropylene as a support. Examples of the organic polymer particles described in (1) above, to which antimony-doped tin oxide is applied as an electric semiconductor layer, and the like.

These EA inorganic substances may be used alone or in combination of two or more. E particularly suitable for use as the surface layer of inorganic / organic composite particles
A inorganic substances include (1) metal oxides, (2) metal hydroxides,
(3) metal oxide hydroxide, (4) polyvalent metal hydroxide,
(13) metal-doped EA inorganic material, or (14) another support on which EA inorganic material is applied as an electric semiconductor layer.

When the EA inorganic material is used, its electric conductivity is 10 ³ Ω ^-1 / cm to 10 ^-11 Ω ^-1 / c at room temperature.
It is preferable to select one within the range of m. When the electric conductivity exceeds 10 ³ Ω ^-1 / cm, EA containing this
Excessive current can flow through the fluid, resulting in high power consumption as well as device overheating. 10 ^-11 Ω ^-1 / cm
If it is less than the above range, the EA effect is weak, so that a sufficient effect may not be obtained in some cases.

In the inorganic / organic composite particles, the weight ratio (%) of the EA inorganic substance forming the surface layer and the organic polymer compound forming the core is not particularly limited, but for example, (EA inorganic substance): The weight ratio of the (organic polymer compound) is within the range of (1-60) :( 99-40), particularly (4-3).
0): It is preferably within the range of (96 to 70).
If the weight ratio of the EA inorganic substance is less than 1%, the EA effect of the obtained EA fluid is insufficient, and if it exceeds 60%, the specific gravity becomes large and it becomes difficult to obtain dispersion stability of the EA particles, and An excessive current will flow through the EA fluid.

For coloring the EA particles, a dye or a pigment may be included in the core, but the color of the EA particles mainly depends on the surface layer color. Therefore, as shown in FIG. Preferably. This can be achieved by using any organic or inorganic pigment with the EA inorganics during the formation of the surface layer. Further, if the EA inorganic substance itself is colored in a desired color, it is not always necessary to use the additional dye. For example, if an inorganic substance forming the surface layer such as black triiron tetroxide (Fe ₃ O ₄ ) or carbon black, which is black and has the EA effect itself, is used, a black pigment is not used. EA particles are obtained.

The inorganic / organic composite particles may contain components other than the above. As an example, for example, an antioxidant, a filler, a coupling agent, carbon black, etc. in the core,
Further, the surface layer may contain a charge adjusting material such as carbon black or an amine compound.

The specific gravity of the EA particles is preferably close to the specific gravity of the electrically insulating medium used in order to stably disperse it in the electrically insulating medium. Considering the specific gravity of a general electric insulating medium, the specific gravity of EA particles is preferably about 1.0 to 2.0. If the difference in specific gravity between the EA particles and the electrically insulating medium is large, the EA particles may settle by gravity in the medium and uniform dispersion may not be possible. From this viewpoint, the inorganic-organic composite particles using an organic polymer compound having a relatively small specific gravity for the core can have a relatively small specific gravity even if the specific gravity of the EA inorganic material forming the surface layer is large. It is advantageous. The specific gravity of the inorganic / organic composite particles can be adjusted to some extent by selecting the type and ratio of the organic polymer compound and the EA inorganic material to be used.

E in the EA fluid used in the display device of the present invention
The A particles have a particle size of 0.1 μm to 500 μm, especially 5
It is preferably in the range of about μm to 200 μm.
If the particle size is less than 0.1 μm, not only is it inconvenient because the diffuse reflection of light on the surface of the particles decreases and the particles appear transparent, but the viscosity of the EA fluid containing a certain weight of these particles increases and the electric field response increases. Inconveniences such as deterioration of the property and easy inclusion of air bubbles. If it exceeds 500 μm, the particle diameter becomes excessively large, and the EA fluid containing a certain weight of the particle group has a reduced opacity when no electric field is applied, and the dispersion stability also deteriorates.

The shape of the EA particles is not particularly limited, but is preferably spherical. If it is spherical, not only can light be diffusely reflected in all directions uniformly, but also the flow viscosity of the EA fluid is reduced, so that the electric field response can be improved. From this point of view, in the above-mentioned inorganic / organic composite particles, the core body is made of an organic polymer compound, and when the core body particles are produced by a controlled emulsion / suspension polymerization method, they can be formed into a substantially spherical shape. It is extremely useful as EA particles used in the display device of the present invention.

The inorganic / organic composite particles can be manufactured by various methods. As an example thereof, there is a method in which particles of a core body made of an organic polymer compound, fine particles of an EA inorganic material and, if necessary, pigment particles are conveyed by a jet stream and collided with each other. In this case, the EA inorganic fine particles collide with the surface of the core particles at a high speed and are fixed to form a surface layer. Another example of the production method is a method in which the core particles are suspended in a gas, and a solution or dispersion liquid of the EA inorganic substance and, if necessary, a dye is atomized and sprayed on the surface. This solution or dispersion may contain a suitable paste. In this case, the surface layer is formed by drying the solution or dispersion after adhering to the surface of the core particles.

A preferable example of the method for producing the inorganic / organic composite particles is a method of simultaneously forming the core and the surface layer. This method is, for example, when emulsion-polymerization, suspension-polymerization or dispersion-polymerization of a monomer or oligomer (hereinafter, simply referred to as “monomer”) of an organic polymer compound forming a core is performed in a polymerization medium. If necessary, it is a method in which pigment particles are present in the above-mentioned monomer or polymerization medium. Water is preferred as the polymerization medium, but a mixture of water and a water-soluble organic solvent can also be used, and an organic poor solvent can also be used. According to this method, the monomers are polymerized in the polymerization medium to form core particles, and at the same time, the EA inorganic fine particles and the pigment are layered on the surfaces of the core particles to coat the core particles to form a surface layer. .

When the inorganic / organic composite particles are produced by emulsion polymerization or suspension polymerization, most of the fine particles of the EA inorganic substance can be obtained by combining the hydrophobic property of the monomer with the hydrophilic property of the EA inorganic substance. It can be oriented on the surface of the core particles. According to the simultaneous formation method of the core and the surface layer, the EA inorganic particles and the pigment are densely and firmly adhered to the surface of the core particles made of the organic polymer compound, and the robust inorganic / organic composite particles are formed. .

The shape of the inorganic-organic composite particles used in the present invention is not always spherical depending on the production method,
When the core particles are produced by the controlled emulsion / suspension polymerization method, the resulting inorganic / organic composite particles have a substantially spherical shape. Since the spherical shape is obtained, the EA fluid having high diffuse reflection of light and high electric field response can be obtained as described above.

Inorganic / organic composite particles produced by the above-mentioned various production methods, particularly the production method of simultaneously forming the core and the surface layer, the whole or a part of the surface layer is generally used in the organic polymer substance or the production process. In some cases, the EA effect may not be sufficiently exhibited due to being covered with a thin film of a dispersant, an emulsifier, and other added substances. Thin films of these inert substances can be removed by polishing the surface of the surface layer. Therefore, in the EA fluid used in the preferred display device of the present invention, the inorganic / organic composite particles whose surfaces are polished are used.

The surface of the inorganic / organic composite particles can be polished by various methods. For example, the inorganic / organic composite particles may be dispersed in a dispersion medium such as water and the mixture may be stirred. At this time, it is also possible to carry out by a method of mixing abrasives such as sand grains or balls into the dispersion medium and stirring with inorganic / organic composite particles, or by a method using a grinding wheel. For example, again
It is also possible to dry-stir with inorganic-organic composite particles, the above-mentioned abrasive, and a grinding wheel without using a dispersion medium.

A more preferable polishing method is a method in which the inorganic / organic composite particles are agitated by a jet stream or the like. This is a method in which the EA particles themselves are violently collided with each other in a gas phase to polish, and a preferable method in that an inert substance exfoliated from the particle surface can be easily separated by classification without the need for other abrasives. Is. The polishing conditions in the above jet stream agitation vary depending on the type of equipment used, the agitation speed, the material of the inorganic / organic composite particles, etc.
It is preferable to stir in a jet stream for about 5 to 15 minutes.

The EA fluid used in the present invention can be produced by uniformly stirring and mixing the above-mentioned inorganic / organic composite particles with other components such as a dispersant in an electrically insulating medium. As the stirrer, any stirrer normally used for dispersing solid particles in a liquid dispersion medium can be used.

As the electrically insulating medium used for the EA fluid, any of those conventionally known as suitable for the EA fluid can be used. For example, diphenyl chloride, butyl sebacate, aromatic polycarboxylic acid higher alcohol ester, halophenyl alkyl ether, trans oil, chlorinated paraffin, fluorine-based oil, silicone oil or fluorosilicone oil, etc. Any fluid can be used as long as it has a high electric breakdown strength, is chemically stable, and can stably disperse the inorganic / organic composite particles. It is also possible to use mixtures thereof.

The kinematic viscosity of this electrically insulating medium is 1 cSt.
It is preferably in the range of ˜3000 cSt. An electrically insulating medium having a kinematic viscosity of less than 1 cSt generally has many volatile components, which causes a problem in storage stability of the EA fluid, and a kinematic viscosity of more than 3000 cSt is not preferable because bubbles are less likely to escape. When a large amount of bubbles remain in the EA fluid, when the electric field is applied, a partial discharge occurs in the micro region inside the bubbles to cause a spark, which may deteriorate the insulating property. From this viewpoint, the kinematic viscosity is preferably in the range of 10 cSt to 1000 cSt, particularly preferably in the range of 10 cSt to 100 cSt.

The electrically insulating medium is EA in the EA fluid.
It is colored differently from the particles. For coloring, an oil-soluble dye or a disperse dye, which is soluble in the selected electrically insulating medium and does not impair its electrical characteristics and transparency, can be used. Since these dyes are widely commercially available, they can be appropriately selected and used. In addition to this, the electrically insulating medium includes a dispersant, a surfactant, a viscosity modifier,
It may contain an antioxidant, a stabilizer and the like.

The concentration of the inorganic / organic composite particles in the EA fluid is not particularly limited, but is 0.5% by weight to.
It is preferably 15% by weight. If the concentration is less than 0.5% by weight, a sufficient EA effect cannot be obtained, and if it exceeds 15% by weight, the concentration is too high and sufficient transparency may not be obtained even when an electric field is applied.

Next, the general operating principle of this EA fluid will be described. FIGS. 6A and 6B show this operation principle, in which the transparent electrode plates 101a-101b are the switches S.
It is electrically connected to the power source B via w. This system is filled with an EA fluid in which EA particles 103 are dispersed in an electrically insulating medium 102. FIG. 6A shows the switch Sw.
Shows that the transparent electrode plates 101a-101b are open and no electric field is applied (when the electric field is off). In this state, the EA particles 103 are randomly dispersed and suspended in the electrically insulating medium 102. Therefore, one electrode plate 10 of this system
When the light L enters from the 1a side, the light L is emitted from the EA particles 10
3 is diffusely reflected on the surface, and the reflected light color of the EA fluid is observed when observing this system from the light source side. Also, when the system is observed from the side opposite to the light source, the system looks dark.

Next, as shown in FIG. 6B, the switch Sw
And the electric field is applied to the transparent electrode plates 101a-101b (when the electric field is on), the EA particles 103 interposed between the electrode plates are arranged between the transparent electrode plates 101a-101b in a direction perpendicular to the electrode plates. To form a chain 104. As described above, the mixing ratio of the EA particles 103 dispersed in the electrically insulating medium 102 is set to 15% by weight or less, and particularly 10% by weight or less. Therefore, when these are arranged to form the chain 104, A gap without EA particles is formed between the chain-like bodies, and the light L incident from the electrode plate 101a side passes through this gap. Therefore, in this state, when the system is observed from the opposite side of the light source, it looks transparent. At this time, the color of the EA particles 104 is not visible, and if the electrically insulating medium is colored, the transmitted light exhibits that color.

When the switch Sw is turned off again in this state, the electric field between the transparent electrode plates 101a-101b disappears, the chain 104 collapses, and the EA particles 103 return to their original random dispersion / floating state. The system stops transmitting light. However, the speed of returning to the random state changes depending on the viscosity of the electrically insulating medium 102, the difference in specific gravity between the electrically insulating medium and the EA particles, the temperature, the presence or absence of vibration, and the like. Therefore, as shown in Example 2, by forming the first electrode layer and the second electrode layer on the surface of one electrode plate and applying the electric field between the electrode layers, the EA particles 103 at this time are formed. For example, as shown in FIG. 4, since a chain-like body parallel to the electrode plate surface is formed like a blind, it can be made electrically opaque, and the transparent / opaque conversion of the EA fluid can be performed quickly. become.

Needless to say, the electric field strength applied between the electrode plates 101a-101b changes depending on the characteristics of the EA particles 103, the electrode plate spacing, etc., but normally when this is expressed in voltage, for example, 0.1 kV / mm. ~ 5.0 kV /
It can be selected within the range of mm. When the EA particles are inorganic / organic composite particles, 0.25 to 1.5 kV /
The range of mm is preferable.

The EA particles 103 have been described as forming a chain by the application of an electric field, but when the content of the EA particles in the EA fluid exceeds 1% by weight, as shown in FIG. Instead of chain-like bodies, a plurality of chain-like bodies 104 are bonded to each other to form columns 105 and arranged.

In this column 105, the EA particles 103 of a plurality of chain-like bodies 104, 104, ... Are lined up so as to be in contact with each other, as shown in FIG. Regarding this, the present inventors have confirmed that individual Es that are dielectrically polarized to (+) and (−)
A particles 103 are arranged so as to attract each other at their opposite electrodes,
It is presumed that it is because of energy stability.

Therefore, when the content of the EA particles 103 is large, a large number of columns 105 are provided on the transparent electrode plates 101a-10.
Thus, the gap between the columns becomes wider than that when a large number of single chain bodies are formed, and the amount of transmitted light increases remarkably and the transparency further increases.

By the way, as described above, the particle size of the EA particles is within the range of 0.1 μm to 500 μm, preferably 5 μm.
The range of ˜200 μm is that the EA used in the present invention.
This is because the particles are functionally light-scattering particles or light-reflecting particles. As is well known, the wavelength of visible light is 380 nm to 780 nm, that is, 0.38 to 0.78 μm.
Therefore, in order to control the transmitted light by scattering or reflecting light of this wavelength, it is necessary that the particle diameter of the EA particles is at least 0.1 μm or more, preferably 5 μm or more. Become.

On the other hand, a particle size smaller than the wavelength of visible light that causes Brownian motion, for example, 5 nm to several 1
When ultrafine particles of 0 nm (about 0.005 to 0.02 μm) are dispersed in an electrically insulating medium, it may be possible to orient the ultrafine particles by an electric field, but the light transmission mechanism in that case. Is completely different from that in the above-mentioned example of the present invention, the ultrafine particles are dispersed and completely transmit light when no electric field is applied, and the ultrafine particles are oriented and scatter and attenuate light when an electric field is applied. , Will behave quite differently.

For example, TiBaO ₄ ultrafine particles may be considered as the ultrafine particles having dielectric properties as described above. However, since TiBaO ₄ is a substance having a specific gravity in the range of 4 to 6 and is heavy, it is assumed that TiBaO ₄ particles are used. Even if an attempt is made to increase the particle size for the purpose of making it a light-reflecting type, it becomes gravitationally settled in the electrically insulating medium due to the difference in specific gravity with the medium, and uniform dispersion is impossible at all. Further, in order to uniformly disperse the TiBaO ₄ particles in the electrically insulating medium, an electrically insulating medium having a large specific gravity is required, but an electrically insulating medium having a specific gravity of about 4 to 6 does not exist. On the other hand, the inorganic-organic composite particles used in the present invention can easily adjust the specific gravity to about 1.2 as described above, and therefore, generally known various kinds of electrically insulating media can be used. .

Next, from the viewpoint of colorability, it is practically difficult to color the ultrafine particles, and even if they can be colored, the particle diameter is too small, and therefore they are dispersed in an electrically insulating medium. It is not possible to perceptually develop the color of the generated ultrafine particles. Therefore, the on / off of the electric field cannot bring about the change between colored opacity and transparency required in the present invention.

Test Example 1 An example of the EA fluid was tested for the relationship between the electric field strength and the change in transparency. Thickness 1.0m
m pieces of ITO glass were prepared, and the ITO surfaces were set to face each other in parallel at an interval of 2 mm, and the peripheral edges were sealed with a resin sealing member to form a cell. This cell was provided with an opening so that the following EA fluid could be filled.

Titanium hydroxide (generic name; hydrous titanium oxide,
Ishihara Sangyo Kaisha, Ltd., C-II) 40 g, butyl acrylate 300 g, 1,3-butylene glycol dimethacrylate 100 g, and a mixture of a polymerization initiator, containing 25 g of tricalcium phosphate as a dispersion stabilizer.
It was dispersed in 0 ml of water, and suspension polymerization was carried out at 60 ° C. for 1 hour with stirring. The obtained product was filtered, washed with acid, further washed with water, and then dried to obtain inorganic / organic composite particles.

The obtained inorganic / organic composite particles were agitated with a jet airflow agitator (Hybridizer manufactured by Nara Machinery Co., Ltd.) to obtain surface-polished inorganic / organic composite particles. The specific gravity of this thing is 1.157,
The average particle size was 13.7 μm. The inorganic / organic composite particles are uniformly dispersed in silicone oils of various kinematic viscosities (TSF451 series manufactured by Toshiba Silicone Co., Ltd.) so that the content ratios thereof are various weight%, and various EA fluid samples are obtained. Prepared.

The above-mentioned various EA fluids were filled in the above-mentioned cells, respectively, and the electric field strength (KV /
mm) was variously changed, and the intensity of light incident on the cell and the intensity of light transmitted through the cell were detected by photosensors respectively, and the comparison value was displayed in dBm as increased light. In this case, an increase of 3.2 dBm means an increase of 2.09 times in the optical power, and an increase of 4.2 dBm in the optical power is 2.63.
It means double the increase. The measurement results are shown in FIGS.

FIG. 9 shows the concentration (% by weight) of the inorganic / organic composite particles and the applied electric field strength (KV / m) when the kinematic viscosity of the silicone oil (electrically insulating medium) is 10 cSt.
The result of measuring the increasing light (dB) corresponding to the change of m) is shown. FIG. 10 shows that the kinematic viscosity of silicone oil is 50 cS.
Similar test results for the case of t are shown. FIG. 11 shows similar test results when the kinematic viscosity of silicone oil is 100 cSt.

From the results shown in FIGS. 9 to 11, the tested particle concentrations were 0.25 kV / mm to 1.5 kV / mm.
When the electric field strength is changed in the range of
It can be seen that the dBm value of the increased light increases as the electric field strength increases. That is, the transparency of the cell increases as the electric field strength between the electrode plates increases. From this, in the display device of the present invention, the transparency / opacity of the image element can be controlled by turning on / off the electric field, and the gradation of the transparency can be continuously or intermittently changed by changing the electric field strength. It shows that it is possible.
A display device capable of changing the transparency of each image element by changing the electric field strength in this manner is also included in the present invention. Also, the particle concentration is 1.0
At weight%, the proportion of increased light is small even when the electric field strength is 3 kV / mm. Therefore, it is understood that the particle concentration is preferably 2.5% by weight or more.

FIG. 12 shows the results of measuring the increased light (dB) corresponding to changes in the kinematic viscosity and electric field strength of silicone oil when the particle concentration was fixed at 5.0% by weight. FIG. 13 shows a similar test result when the particle concentration is fixed at 7.5% by weight.

From the results shown in FIGS. 12 and 13, whether the particle concentration is 5.0% by weight or 7.5% by weight, the kinematic viscosity of the silicone oil (electrically insulating medium) is 10 cS.
This example shows that the control width of the transmitted light amount is maximized when the range is from t to 100 cSt.

Next, a test example of the electric field response of the EA fluid will be shown. The above cell was filled with the EA fluid in which 7 wt% of inorganic / organic composite particles were dispersed in silicone oil having a kinematic viscosity of 10 cSt, and the change in the amount of transmitted light after applying an electric field was measured with time. The results are shown in Fig. 14. FIG.
4, the electric field was applied about 1 second after the start of measurement.

From the results shown in FIG. 14, it is understood that the amount of transmitted light of this EA fluid starts to increase immediately after the electric field is applied, reaches its maximum in 3 to 4 seconds, and then stabilizes.

FIG. 15 shows the relationship between the amount of transmitted light and the wavelength when the amount of transmitted light is measured using an EA fluid in which 4% by weight of EA particles colored in blue is added to silicone oil having a kinematic viscosity of 10 cSt. . The coloring of the EA particles depends on the amount of the EA inorganic substance that constitutes the surface layer of the EA particles when the EA particles are manufactured.
It was carried out by substituting the blue pigment for weight%. In the figure, the curve indicated by E = 0 kV shows the transmission wavelength spectrum when the electric field is off, and the curve indicated by E = 2 kV is 2
The transmission wavelength spectrum when a potential of kV is applied to the electrode plate is shown.

As is clear from the comparison of both curves in FIG. 15, the blue-based EA fluid, which only slightly transmits blue-based light having a short wavelength when the electric field is off, emits light in a wide wavelength range when the electric field is on. It can be seen that it changed from blue opaque to colorless and transparent.

In FIG. 16, dimethyl silicone oil containing 0.1% by weight of a blue dye was used as an electrically insulating medium, and the amount of transmitted light was measured only for this electrically insulating medium (without EA particles). The transmitted light spectrum in the case is shown. The electrically insulating medium is a medium that looks blue to the naked eye. In FIG. 16, when the light source spectrum and the medium spectrum are compared, light is absorbed in a portion other than the spectrum showing blue with a short wavelength. From this it is clear that the electrically insulating medium was colored by the dye.

FIG. 17 shows the amount of transmitted light of an EA fluid in which 5% by weight of yellow colored EA particles are dispersed in dimethylsilicone oil containing 0.1% by weight of a blue dye as a colored electrically insulating medium. The transmitted light spectrum at the time of performing is shown. The means for coloring the inorganic / organic composite particles is the same as in the above example, but this time a yellow pigment is used.

This figure shows the light source spectrum and E = 0 kV / m.
The transmitted light spectrum in the case of m and the transmitted light spectrum in the case of E = 1 kV / mm are shown on the same screen. From this figure, it can be seen that what was opaque yellow-green, which is a mixed color of blue and yellow when the electric field was turned off, changed to a blue transparent state which was almost colorless and transparent when the electric field was turned on. In this way, various colors are
It has been revealed that it can be applied to both EA particles of fluid A and an electrically insulating medium, and can be reversibly changed from an opaque state of one color to a transparent state of another color by turning on / off an electric field. .

FIG. 18 relates to an image device having a first electrode layer and a second electrode layer on the same electrode plate. In this image element, a comb-shaped transparent first electrode layer and a transparent second electrode layer adjacent to the transparent comb-shaped first electrode layer are formed in a nest on one of the transparent electrode plates facing each other, and face the other transparent electrode plate. Silicone oil with a kinematic viscosity of 10 cSt was used as an electrically insulating medium in the cell in which the electrode layer was formed.
The organic composite particles were filled with an EA fluid containing 4% by weight of EA particles. FIG. 18 shows the effect of switching the application of an electric field between the first electrode layer and the counter electrode layer or between the first electrode layer and the second electrode layer in this image element.

The line in FIG. 18 shows the transmitted light spectrum in the initial state where no electric field is applied to any of the electrode plates. The line is 2k between the first electrode layer and the counter electrode layer.
The transmitted light spectrum when an electric field of V is applied is shown. The line shows the transmitted light spectrum when the switch is switched and a 2 kV electric field is applied between the first electrode layer and the second electrode layer.

In FIG. 18, the line shows that the EA particles randomly float and disperse when the electric field is off, and are opaque in the measurement wavelength band. The line shows that by applying an electric field between the first electrode layer and the counter electrode layer, the EA particles were arranged perpendicularly to the electrode plate, and as a result, transmitted light in a wide wavelength band. The lines show that when an electric field was applied between the first and second electrode layers on the same plane, the EA particles were arranged parallel to this plane, thus blocking the transmission of light. That is, it is understood that the light transmittance can be rapidly changed by the switching operation of the electrodes.

Tables 1 and 2 show that the transmitted light when the electric field strength was changed at each wavelength by using silicone oil (electrically insulating medium) having a kinematic viscosity of 50 cSt, the concentration of EA particles being 5.0% by weight. The measurement results are shown in.

[0091]

[Table 1]

[Table 2]

From the results shown in Tables 1 and 2, when image control is performed using the display device according to the present invention, 400 to 110
Uniform light transmission was obtained in a wide wavelength range of 0 nm, and it became clear that the present invention enables uniform color tone adjustment in a wide light wavelength range. Since the wavelength range of visible light is usually set to 480 nm to 780 nm,
It has been revealed that the device of the present invention has uniform transmitted light control performance in almost the entire wavelength range of visible light and in the infrared region having a longer wavelength than that.

[0093]

The color display device of the present invention is filled with an EA fluid containing colored EA particles between two transparent electrode plates in an electrically insulating medium colored in a different color. Since it has an image element, the color of the electrically insulating medium is recognized as transmitted light when the electric field is on, and the color of the EA particles is recognized as an opaque display color when the electric field is off.

If one or more of the electrode plates are provided with two or more electrode layers arranged in a non-contact manner with each other, it is possible to arrange the electrodes between the one electrode layer and the counter electrode layer or both electrodes on the same electrode plate. By switching between the two and applying the electric field, the electric field response of the image element can be remarkably improved.
If the display device has two or more image elements arranged in parallel on the same surface and at least one of the EA particles and the electrically insulating medium of each adjacent image element is colored in a different color, this display The device is capable of multicolor expression.

The EA particles consist of an organic polymer compound core and EA
Inorganic / organic composite particles consisting of an inorganic (and pigment) surface layer have good storage stability and light resistance of the EA fluid, so a display device using this is excellent in durability and light resistance, and can be used outdoors. You can also use it. The display device of the present invention has a simple structure, a high color contrast, and there is no factor that hinders an increase in size. Therefore, there is an advantage that a large-sized color display device can be easily obtained at low cost.

[Brief description of drawings]

1A is a cross-sectional view and a circuit diagram showing a mode of an image element when an electric field is off in an embodiment of a display device of the present invention, and FIG. 1B shows a mode of the same image element when an electric field is on. Sectional drawing and circuit diagram shown.

FIG. 2 shows E contained in the EA fluid used in the example of FIG.
Sectional drawing which shows an example of A particle.

FIG. 3 is a development view and a circuit diagram showing an electrode plate configuration of an image device according to a second embodiment of the present invention.

FIG. 4 is a sectional view and a circuit diagram showing one operation mode of the image device of FIG.

5A is a plan view showing a pixel unit according to a third embodiment of the present invention, and FIG. 5B is a line X in FIG. 5A.
-A sectional view and a partial circuit diagram taken along line X '.

6A is a cross-sectional view showing the behavior of a general EA fluid when the electric field is off, and FIG. 6B is a cross-sectional view showing the behavior of the same EA fluid when the electric field is on.

FIG. 7 is a cross-sectional view showing one behavior of EA particles in a general EA fluid when an electric field is turned on.

8 is a cross-sectional view for explaining the principle of the behavior shown in FIG.

FIG. 9 is a graph showing a change in transparency of the EA fluid when the kinematic viscosity of the electrically insulating medium is fixed at 10 cSt and the EA particle concentration and the applied electric field strength are changed.

FIG. 10 is a graph showing the change in transparency of the EA fluid when the kinematic viscosity of the electrically insulating medium is fixed at 50 cSt and the EA particle concentration and the applied electric field strength are changed.

FIG. 11 is a graph showing a change in transparency of the EA fluid when the kinematic viscosity of the electrically insulating medium is fixed at 100 cSt and the EA particle concentration and the applied electric field strength are changed.

FIG. 12: EA particle concentration of EA fluid was 5.0
6 is a graph showing the change in transparency when the kinematic viscosity of the electrically insulating medium and the applied electric field strength are changed with the weight fixed to wt%.

FIG. 13: For the EA fluid, the EA particle concentration was 7.5.
6 is a graph showing the change in transparency when the kinematic viscosity of the electrically insulating medium and the applied electric field strength are changed with the weight fixed to wt%.

FIG. 14 is a graph showing an example of measurement of electric field response of EA fluid.

FIG. 15 is a graph showing transmitted light spectra of the EA fluid when the electric field is off and when the electric field is on.

FIG. 16 is a graph showing a transmitted light spectrum of an electrically insulating medium in an EA fluid.

FIG. 17 is a graph showing a transmitted light spectrum when an electric field is off and when an electric field is on for an EA fluid in which yellow colored EA particles are dispersed in a blue colored electrically insulating medium.

18 is an image element similar to that of Example 2, when the electric field is off, when an electric field is applied between the first electrode layer and the counter electrode layer, and between the first electrode layer and the second electrode layer. The graph which shows the transmitted light spectrum when an electric field is applied.

[Explanation of symbols]

1a, 1b ... Transparent electrode plate, 4 ... EA fluid, 5 ... Electrically insulating medium, 6 ... EA particles, 8 ... Switch, 9 ... Power supply, 10
… Image element, obs… Observer.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kazuya Akashi 1-5-1, Kiba, Koto-ku, Tokyo Within Fujikura Ltd. 206

Claims (4)

[Claims] 1. An electrosensitive optical functional fluid composition comprising solid particles having an electric field array effect in a transparent electrically insulating medium is filled between two opposing transparent electrode plates, and A color display device having an image element in which solid particles and an electrically insulating medium are colored in different colors. 2. The color display device according to claim 1, wherein two or more transparent electrode layers arranged in a non-contact manner with each other are formed on at least one of the electrode plates. 3. Two or more image elements according to claim 1 or 2 are arranged in parallel on the same plane, and at least one of the solid particles and the electrically insulating medium of each adjacent image element. A color display device in which one is colored in a different color. 4. The inorganic-organic composite particles, wherein the solid particles are composed of a core body made of an organic polymer compound and a surface layer containing an inorganic substance having an electric field alignment effect.
The color display device according to claim 3.