JP2003186062A - Electrophoretic display device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophoretic display device improved in contrast and a method of manufacturing the same. <P>SOLUTION: The electrophoretic display device is provided with display layers 41 and 42 having at least dispersion media 50 and display particle bodies 60 dispersed in the dispersion media 50, and the dispersion media 50 are formed of a solvent mixture composed of silicone oil and denatured silicone oil. As a result, not only the contrast higher than that of the conventional electrophoretic display device can be obtained but a higher rewriting speed (transfer speed) can be obtained as well. <P>COPYRIGHT: (C)2003,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 device and a manufacturing method thereof, and more particularly to an electrophoretic display device having improved visibility (contrast) and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, an electrophoretic display device utilizing an electrophoretic phenomenon has been known (Japanese Patent Laid-Open No. 11-21913).
(See Japanese Patent Publication No. 5). An electrophoretic display device generally includes an electrophoretic display panel in which a medium composed of an organic solvent such as benzene, toluene, xylene, or silicone oil, and electrophoretic particles (display particles) having positive or negative charges are enclosed. By having an electric field applied to such electrophoretic particles, they are collected on the display surface side of the electrophoretic display panel, or are moved away from the display surface side of the electrophoretic display panel to display the desired characters and figures. Can be made.

Such an electrophoretic display device is a conventional CRT (Cathode Ray Tub).
Unlike e) and liquid crystal displays, the display contents can be maintained for a long time in the state of no power supply, and the display panel itself does not require a light source, so that a feeling similar to paper can be obtained. It has an excellent feature that it can be used. Therefore, the electrophoretic display device is expected to be applied as electronic paper.

On the other hand, the electrophoretic display device is different from a printed matter in that the display content can be appropriately changed by applying an electric field. Therefore, the electrophoretic display device is typified by a conventional paper display (so-called hard copy) and a CRT or a liquid crystal. It can be positioned in the middle of the electronic display (so-called soft copy). Therefore, if a desired character, figure, or the like is displayed on the electrophoretic display device by using a dedicated writing device as if printing on paper using a printer, it can be used as, for example, an electronic newspaper.

[0005]

Visibility (contrast) is one of the important characteristics required for an electrophoretic display device. In order to increase the contrast, it is effective to increase the dispersibility of display particles in the medium.

However, since the display particles are generally hydrophilic, when a hydrophobic silicone oil is used as the medium as in the conventional electrophoretic display device described in the above publication, the display particles are referred to as the medium. There is a problem that the display particles are not sufficiently dispersed in the medium because of low affinity with the particles.

Therefore, an object of the present invention is to provide an electrophoretic display device having improved contrast and a method of manufacturing the same.

Another object of the present invention is to provide an electrophoretic display device having improved dispersibility of display particles and a method for manufacturing the same.

[0009]

The object of the present invention is to:
An electrophoretic display device comprising a display layer having at least a dispersion solvent and display particles dispersed in the dispersion solvent, wherein the dispersion solvent comprises a mixed solvent of silicone oil and modified silicone oil. It is achieved by an electrophoretic display device.

According to the present invention, since the dispersion solvent is a mixed solvent of silicone oil and modified silicone oil, the dispersibility of the display particles is greatly improved as compared with the conventional electrophoretic display device. Therefore, not only a high contrast can be obtained, but also a high rewriting speed (transfer speed) can be obtained.

In a preferred embodiment of the present invention, the modified silicone oil is one or more selected from the group consisting of alcohol-modified silicone oil, polyether-modified silicone oil, carboxyl-modified silicone oil and amino-modified silicone oil. It is a modified silicone oil.

According to the preferred embodiment of the present invention, since the hydrophilicity of the dispersion solvent is effectively enhanced, the dispersibility of the display particles can be effectively enhanced.

[0013] In a further preferred aspect of the present invention, the amount of the modified silicone oil added is 0.1 to 100% by weight of the display particles.

According to a further preferred embodiment of the present invention, it is possible to effectively improve the dispersibility of the display particles while effectively suppressing the current flowing through the dispersion solvent when a voltage is applied. .

[0015] In a further preferred aspect of the present invention, the amount of the modified silicone oil added is 0.5 to 30% by weight of the display particles.

According to a further preferred embodiment of the present invention, while more effectively improving the dispersibility of the display particles,
It becomes possible to more effectively suppress the current flowing through the dispersion solvent when a voltage is applied.

[0017] In a further preferred aspect of the present invention, at least a part of the silicone oil is fluorosilicone oil.

According to a further preferred embodiment of the present invention, the moving speed of the display particles can be increased.

[0019] In a further preferred aspect of the present invention, the dispersion solvent is subjected to degassing under reduced pressure.

According to a further preferred embodiment of the present invention, the insulating property is sufficiently enhanced.

[0021] In a further preferred aspect of the present invention, the display layer is provided in two layers, whereby double-sided display is possible.

According to a further preferred embodiment of the present invention, it is possible to obtain a feeling of use closer to that of actual paper.

The object of the present invention is also to perform a degassing under reduced pressure on a dispersion solvent in which display particles are dispersed, which is composed of a silicone oil and a modified silicone oil, and the above degassed dispersion solvent is used as a substrate. This is achieved by a method for manufacturing an electrophoretic display device, which includes a step of forming a display layer by applying the coating layer on the display layer and a step of forming a transparent layer on the display layer.

In a preferred embodiment of the present invention, a step of subjecting the display layer to a degassing under reduced pressure after applying the dispersion solvent onto a substrate and before forming a transparent layer on the display layer. Further prepare.

[0025]

DETAILED DESCRIPTION OF THE INVENTION Referring to the accompanying drawings,
A preferred embodiment of the present invention will be described in detail.

FIG. 1 is a perspective sectional view partially showing an electrophoretic display device 10 according to a preferred embodiment of the present invention.

As shown in FIG. 1, an electrophoretic display device 10 according to this embodiment is provided on an intermediate substrate 20 partially or wholly made of a conductive material, and one and the other sides of the intermediate substrate 20, respectively. Transparent layers 31 and 32, and display layers 41 and 42 provided between the intermediate substrate 20 and the transparent layers 31 and 32, respectively. That is, the electrophoretic display device according to this embodiment can perform double-sided display, and (A) and (B) shown in FIG. 1 are the viewing directions. However, the electrophoretic display device according to the present invention is not limited to the double-sided display type, and may be applied to a single-sided display type electrophoretic display device. The transparent layer 32 and the display layer 42 may be deleted to provide a single-sided display type.

The intermediate substrate 20 is a base 2 made of an insulating material.
1 and conductive layers 22 and 23 provided on both sides of the base 21.
Consists of. However, the intermediate substrate 20 is not limited to such a structure as long as the display layer 41 and the display layer 42 can be reliably separated and a conductive layer is present. Details of the intermediate substrate 20 will be described later.

The transparent layers 31 and 32 not only seal the display layers 41 and 42 but also serve as a display surface. Therefore, the transparent layers 31 and 32 are required to have high transparency and be resistant to scratches on the surface. Transparent layer 3
The details of 1 and 32 will also be described later.

The display layers 41 and 42 are both formed of the dispersion solvent 5
0, the display particle body 60 dispersed in the dispersion solvent 50,
The display particles 6 are arranged almost regularly in the dispersion solvent 50.
And a spherical body 70 having a diameter sufficiently larger than 0, preferably 10 times or more. The display particle body 60 needs to be electrically charged positively or negatively. The spherical body 70 is not particularly limited, but is preferably charged with the same electric charge as that of the display particle body 60. The spherical body 70 includes the intermediate substrate 20 and the transparent layers 31, 3
It plays a role as a spacer for keeping the space between the display particle body 2 and the display particle body 60 moved to the side of the intermediate substrate 20 and a hiding material for hindering the visual recognition of the display particle body 60.

In the electrophoretic display device according to this embodiment, the display particle body 60 is moved to the transparent layers 31 and 32 located in the viewing direction, or the display particles are provided to the intermediate substrate 20 side located substantially in the center. Depending on whether the body 60 is moved, desired characters / figures can be displayed. That is, in the region where a large number of display particle bodies 60 are concentrated on the transparent layers 31 and 32 side, the brightness and color of the display particle body 60 are observed on the display surface, and conversely, a large number of display particle bodies 60 are displayed. In the region existing on the intermediate substrate 20 side, the brightness and color of the spherical body 70 are observed on the display surface. Therefore, the display particle body 60 and at least one of the spherical body 70 and the dispersion solvent 50 have different brightness.
Must have color and the like. In particular, the display particle body 60
It is preferable that the spherical solvent 70 and the spherical body 70 have different brightness and color, and the dispersion solvent 50 is colorless and transparent. In this case, the display particle body 60 is preferably colored with a pigment.

As described above, since the display particle body 60 is electrically charged positively or negatively, an external electric field is applied to the display particle body 60 so that the display particle body 60 side or the intermediate substrate 20 side. Can be moved to. When the spherical body 70 is charged with the same electric charge as that of the display particle body 60, the Coulomb force also acts on the spherical body 70 due to the electric field applied from the outside, but the spherical body 70 is sufficiently more than the display particle body 60. Since it is large, the moving speed is significantly slower than that of the display particle body 60. Therefore, even if the spherical body 70 is not fixed to the intermediate substrate 20, its movement does not substantially affect the display.

Here, when the display particle body 60 is moved to the transparent layer 31 (32) side by applying an electric field from the outside and then the electric field is removed, the display particle body 60 is moved to the intermediate substrate 20 side due to the influence of gravity. Although there is a possibility that the display particles 60 may fall, since most of the display particles 60 that have fallen remain on the surface of the spherical body 70, the number of display particles 60 that reach the intermediate substrate 20 is very small. It can be suppressed to the limit. Similarly, after moving the display particle body 60 to the intermediate substrate 20 side by applying an electric field from the outside,
When the electric field is removed, the display particle body 60 is affected by gravity.
May fall to the transparent layer 31 (32) side, but most of the dropped display particle bodies 60 remain on the surface of the spherical body 70, so that the display particle bodies 60 reaching the transparent layer 31 (32) It is very low, so that contrast degradation is minimized.

Details of the dispersion solvent 50, the display particle body 60 and the spherical body 70 will be described later.

In the present embodiment, the intermediate substrate 2
It is preferable that the electrophoretic display device 10 is made of electronic paper by making the transparent layers 31, 32 and the display layers 41, 42 flexible. In this case, it is possible to obtain a feeling of use very close to that of actual paper.

Next, the electrophoretic display device 10 shown in FIG.
A writing device for displaying characters and figures on the screen will be described.

FIG. 2 is a cross-sectional view schematically showing the structure of the writing device 100 for displaying characters, figures, etc. on the electrophoretic display device 10.

As shown in FIG. 2, the writing device 100.
Is an electric field applying mechanism 110 for applying an electric field to the electrophoretic display device 10, a carry-in mechanism 120 for carrying the electrophoretic display device 10 into the electric field applying mechanism 110, and an electric field applying mechanism for the electrophoretic display device 10. And a carry-out mechanism 130 for carrying out from 110. FIG. 2 shows the loading mechanism 1
The case where both 20 and the carry-out mechanism 130 are rollers is shown, but it is not essential that these are rollers, and other mechanisms may be provided.

Further, in the writing device 100 shown in FIG. 2, the electrophoretic display device 10 is configured to be kept in a horizontal state from the carry-in mechanism 120 to the carry-out mechanism 130. If the electronic paper has flexibility, it is not always necessary to convey the electronic paper while keeping it horizontal, and the electronic paper may be curved while being wrapped around a roller to be conveyed.

FIG. 3 is a diagram showing the structure of the electric field applying mechanism 110 in more detail.

As shown in FIG. 3, the electric field applying mechanism 110.
Is composed of a first electric field applying head 111 for applying an electric field to the display layer 41 and a second electric field applying head 112 for applying an electric field to the display layer 42. Each of the electric field applying heads 111 and 112 is composed of a plurality of electrodes 113 and a switch 114 provided corresponding to each electrode 113. The plurality of electrodes 113 may be arranged in a line, or 2
It may be arranged in a dimension.

When writing characters, figures, etc. on the electrophoretic display device 10 by using the writing device 100, first, the electrophoretic display device 10 is carried in to the electric field applying mechanism 110 by using the carry-in mechanism 120. Intermediate substrate 20
While fixing the electric potentials of the conductive layers 21 and 22 constituting the above, each switch 114 is turned on or off based on the content to be displayed. When the switch 114 is turned on, the display layer 4
An electric field is generated at the corresponding positions of 1 and 42, and the display particle body 60 moves to the transparent layer 31 (32) side or the intermediate substrate 20 side. By performing such an operation on a necessary portion of the display surface of the electrophoretic display device 10, it is possible to display desired characters, figures, etc. on the display surface.

When the electrodes 113 are arranged in a line, the relative positional relationship between the electrophoretic display device 10 and the first and second electric field applying heads 111 and 112 is changed in one direction. As a result, the entire display surface can be scanned and desired characters, figures, etc. can be written. in this case,
By providing a plurality of lines each including the electrode 113, the writing speed can be improved.

When the electrodes 113 are arranged two-dimensionally over the same area as or more than the display surface of the electrophoretic display device 10, the electrophoretic display device 10 and the first and second electrodes are arranged. It is possible to write desired characters, figures, etc. in a state where the relative positional relationship with the electric field application heads 111, 112 is fixed.

Further, when the electrodes 113 are two-dimensionally arranged over an area smaller than the display surface of the electrophoretic display device 10, the electrophoretic display device 10 and the first and second electric field applying heads. By changing the relative positional relationship with 111 and 112 in the X and Y directions, it is possible to scan the entire display surface and write desired characters, figures, and the like.

Further, the first and second electric field applying heads 11
Two kinds of electrodes 113 having a large surface area and an electrode 113 having a small surface area are provided in 1 and 112, and an electrode 113 having a large surface area is first used to draw an approximate pattern such as a character or figure to be written, and thereafter, a surface area is small. Electrode 11
It is also preferable to use 3 to draw the final pattern. By doing so, not only writing can be performed at a higher speed, but also a short circuit between the electrodes 113 is less likely to occur.

Further, the first and second electric field applying heads 1
Separately from 11, 112, a large-area initialization electrode is provided, and before the writing using the first and second electric field application heads 111, 112, the initializing electrode is used to display data on the electrophoretic display device 10. It is also preferable to erase the contents. In this case, a positive voltage and a negative voltage may be alternately applied to the initializing electrode, and finally the display particle body 60 may be moved to the intermediate substrate 20 side. By performing such an operation, the arrangement of the display particle bodies 60 after writing becomes constant regardless of the state before writing, so that it is possible to stably obtain a high contrast.

The conductive layers 22 and 23 included in the intermediate substrate 20 can be used without using the writing device 100.
It is also possible to write directly by hand using a writing pen to which a potential difference is applied. In this case, by making the tip of the writing pen into an arc shape having a radius of 50 to 1000 μm, it is possible to effectively prevent damage to the transparent layers 31 and 32.

Next, each element constituting the electrophoretic display device according to this embodiment will be described in more detail.

[0050]Dispersion solvent 50 The dispersion solvent 50 is composed of silicone oil and modified silicone oil.
It is composed of a mixed solvent of yl. In addition, in this specification
And simply "silicone oil" means dimethyl silicone
Oil (dimethylpolysiloxane), methylpheny
Silicone oil and fluorine-substituted alkyl-modified silico
Fluorosilicone oil such as silane, dispersion solvent 5
The silicone oil used for 0 is one of these
It may be one type of silicone oil, or two types
It may be a mixture of two or more kinds.

Silicone oil has the advantage that it is less harmful than other insulating solvents such as organic solvents, but since it is hydrophobic, the silicone oil alone can make the display particles 60 uniform. It is difficult to disperse and hold. That is, when the dispersion solvent is composed of silicone oil alone, the display particles 60 are not uniformly dispersed, so that sedimentation or aggregation occurs, and not only the contrast decreases with the passage of time, but in the worst case, the display content is It will change.

Therefore, in this embodiment, a liquid obtained by adding modified silicone oil to silicone oil is used as the dispersion solvent 50. The modified silicone oil functions as a surfactant and / or a specific gravity adjusting agent, improves the dispersibility of the display particle body 60, and prevents the formation of precipitates. Further, it also has an effect of improving the moving speed of the display particle body 60. It is also considered that the moving speed of the display particle body 60 is improved because the dispersibility is improved by the addition of the modified silicone oil and the particles move as individual particles. However, when the dispersibility is improved by using an organic solvent as a dispersion solvent and adding a surfactant thereto, the moving speed of the display particles is improved as compared with the case where the modified silicone oil is added. In consideration of the small ratio of the above, the fact that the functional group of the modified silicone oil is adsorbed to the display particle body 60 to form a [particle + modified silicone] structure having a high migration speed is It is believed that this has greatly contributed to the improvement of

As described above, by using the dispersion solvent 50 in which the modified silicone oil is added to the silicone oil, it is possible to manufacture an electrophoretic display device having a high contrast and a high rewriting speed.

In the present specification, the modified silicone oil refers to one having a structure in which a part of the methyl group of dimethyl silicone oil (dimethyl polysiloxane) or methylphenyl silicone oil is replaced with various functional groups (excluding fluorine). It is known to have properties such as compatibility with other solvents, affinity for fibers, hydrophilicity, emulsifying property, antistatic property, lubricity, and further chemical reactivity. As the modified silicone oil, it is preferable to use one or more of alcohol-modified silicone oil, polyether-modified silicone oil, carboxyl-modified silicone oil and amino-modified silicone oil, and among them, polyether-modified silicone oil is used. Particularly preferred. There is also a classification method in which fluorosilicone oil is one type of modified silicone oil, but in the present specification, modified silicone oil does not include fluorosilicone oil.

The alcohol-modified silicone oil has a structure in which one or both of the methyl groups of dimethyl silicone oil is replaced by a hydroxyl group-containing alkyl group, and the polyether-modified silicone oil is a hydrophilic polyoxyalkylene which is replaced by a hydrophobic dimethyl group. It has a structure introduced into silicone oil, a carboxyl-modified silicone oil has a structure in which one or both of the methyl groups of dimethyl silicone oil is replaced with a carboxyl group, and an amino-modified silicone oil is a methyl group of dimethyl silicone oil. It has a structure in which one or both are replaced with an aminoalkyl group.

The content of the modified silicone oil is preferably 0.1 to 100% by weight, more preferably 0.5 to 30% by weight, based on the display particle body 60. If the content of the modified silicone oil is less than 0.1% by weight with respect to the display particle body 60, the effect of the present invention is not remarkable. Further, the content of the modified silicone oil is 3 with respect to the display particle body 60.
If it exceeds 0% by weight, the current flowing through the dispersion solvent 50 increases, and the insulation resistance decreases, and if it exceeds 100% by weight, the service life is drastically shortened, and the practical standard of 500 times cannot be achieved. Further, since modified silicone oils are generally highly reactive, they cause various problems. For example, when the amino-modified silicone oil is left in the air, a film is formed on the surface of the display particle body 60.
It is not preferable to add more than 100% by weight to the above. However, when the display layers 41 and 42 are treated so as to be completely shielded from the outside air and the display particle body 60 having a particularly low dispersibility is used, the display particle body 60 exceeds 100% by weight. The amount may be added.

The modified silicone oil may be added not by directly adding it to the silicone oil but by subjecting the display particles 60 to surface treatment with the modified silicone oil in advance. For example, when alcohol-modified silicone oil and toluene are mixed, the display particle body 60 is put therein, heated and refluxed, and then unreacted substances are removed, the surface of the display particle body 60 is esterified with the alcohol-modified silicone oil. It is possible to bind them by a reaction or the like.

Fluorosilicone oil has a characteristic that its dielectric constant is, for example, about 6.8, which is significantly higher than the dielectric constant of about 2.8 which is a typical dimethylsilicone oil. Therefore, when part or all of the silicone oil is fluorosilicone oil, the moving speed of the display particles 60 can be increased.

Further, it is also preferable to add 1 to 20% by weight of an organic solvent such as dodecene, ethylbiphenyl, toluene, xylene and hexane to the mixed solvent of the silicone oil and the modified silicone oil. These hydrocarbon solvents may be used alone or in combination of two or more.

The dispersion solvent 50 is preferably degassed under reduced pressure and water is removed in advance. Decompression deaeration and water removal are preferably carried out by heating and decompression treatment accompanied by stirring at 40 ° C to 80 ° C. If the vacuum degassing and water removal are not performed, the insulation characteristics will deteriorate and
This causes the display particle body 60 to contain excessive water.

The volume resistivity of the dispersion solvent 50 is 10
It is preferably ¹¹ Ωcm or more, and 10 ¹³ Ωcm
The above is particularly preferable. When the volume resistivity of the dispersion solvent 50 is less than 10 ¹¹ Ωcm, the amount of current for driving increases and energy loss occurs, and at the same time, the display layer 4
Since 1 and 42 generate heat, the product life is shortened.

In the dispersion solvent 50, if necessary, an electrolyte, a surfactant and a polymer dispersant (for example, having a nitrogen atom and / or an oxygen atom and containing a polymerizable unsaturated bond). Polymeric dispersant obtained by polymerizing a polymerizable polymer with a monomer component composed of a polyfunctional polymerizable monomer or other polymerizable monomer), metal soap, resin, rubber, varnish, compound, etc. Other charge control agents, lubricants, stabilizers and the like may be added. Further, an antioxidant (dibutylphenol, etc.), a corrosion inhibitor (benzotriazole, etc.), a friction modifier, an extreme pressure agent, an antifoaming agent, an ultraviolet absorber, etc. are appropriately selected, and an appropriate amount (for example, for the display particle body 60) 0.1 to 10% by weight) may be added.

In forming the display layers 41 and 42,
On the intermediate substrate 20 in which the spherical bodies 70 are arranged in advance, the dispersion in which the display particle bodies 60 are dispersed in the dispersion solvent 50 is subjected to the screen printing method, the blade coating method, the roll coating method, the spray coating method, the gap coat coating method, It is preferable to use a so-called printing method such as a bar coating method, an electrophotographic method, or an electrostatic coating method. According to these methods, it is not necessary to use an expensive vacuum device, and the electrophoretic display device 10 can be manufactured at low cost. Further, not only the display particle body 60 but also the spherical body 70 may be used as the dispersion body. In this case, it is not necessary to arrange the spherical body 70 on the intermediate substrate 20 in advance.

The specific gravity of silicone oil is about 0.90, which is smaller than that of general display particles (1.1, for example). On the other hand, since the modified silicone oil has a specific gravity of about 0.98 to 1.10, it is possible to improve the retention property.

[0065]Display particle body 60 The display particle body 60 has a volume of 20% or more and 90% or less.
It is preferably hollow. Hollow here means porous
It is a concept that also includes states. Most of this hollow part
It is necessary to communicate with the outside, not in a closed state.
In addition, it is preferable that the through holes are formed. Therefore, display
When many hollow parts exist in the particle body 60, each hollow part
There are two or more parts that communicate with the outside in a part
Preferably. With such a form, the display grain
When the child body 60 is dispersed in the dispersion solvent 50, the dispersion solvent
50 easily penetrates the hollow part, and the hollow part is almost dispersed.
Fill with solvent 50. As a result, the display particle body 60
The apparent specific gravity becomes closer to the dispersion solvent 50, and
It is possible to suppress the movement of the indicator particles 60.

FIGS. 4A and 4B are sectional views showing an example of the display particle body 60.

In the display particle body 60 shown in FIG. 4A, the central portion is entirely a cavity 61, and a plurality of openings 62 communicating with the cavity 61 are provided in the surface portion. Further, in the display particle body 60 shown in FIG. 4B, a large number of through holes 63 are provided inside.

If the hollow portion of the display particle body 60 is less than 20%, the apparent specific gravity of the display particle body 60 cannot be sufficiently brought close to the specific gravity of the dispersion solvent 50, and movement (sedimentation) due to gravity is effective. Cannot be controlled. on the other hand,
When the hollow portion of the display particle body 60 exceeds 90%, it is difficult to confirm the brightness and color of the display particle body 60, and the contrast is lowered.

Even if the display particle body 60 has a hollow portion, if there is no portion communicating with the outside, the dispersion solvent 50 does not enter the hollow portion, so that the above effect can be obtained. In addition to that, since the gas (air) remains present in the hollow portion, the apparent specific gravity becomes too light as compared with the specific gravity of the dispersion solvent 50, and the floating gravity conversely floats, which is preferable. There is no
No. 01-56653).

Examples of the material of the display particles 60 include titanium oxide, carbon black, dark blue or phthalocyanine green, well-known colored particles, and various organic / inorganic pigments.
Fine powder such as dye, metal powder, colored glass or resin, particles of polymer of aziridine compound, and the like can be appropriately used. For example, an inorganic pigment or an organic pigment can be used as the pigment, and examples of the inorganic pigment include lead white and zinc white. Examples of organic pigments include fast yellow and copper azomethine yellow.

The display particles 60 are preferably particles having a sulfonic acid group such as an ion exchange resin, and more preferably polymer particles having a sulfonic acid group.
It is particularly preferable to use sulfonic acid group-containing polystyrene polymer particles or an ionic polymer (ion exchange resin). According to this, the conductive layer 2 forming the intermediate substrate 20
By being supplied with electric charges from 2, 23, it becomes possible to move at high speed. The sulfonic acid group may be in a free state or in a neutralized state as a salt, but a monovalent (eg, lithium) and trivalent (eg, aluminum) mixed salt is particularly preferable.

The ion exchange resin is preferably a polymer of styrene and divinylbenzene to which an ion exchange group is bonded, and the ion exchange group dissociates in the presence of a slight amount of water. Here, having a sulfone group as a fixed ion causes a large charge.

The reaction for sulfonating the display particle body 60 is as follows.
The dried display particles 60 are mixed with a sulfonating agent, for example, at a temperature in the range of −20 to 250 ° C. for 0.3 to 100.
It is carried out by holding for about a time, but preferably −
It is carried out by holding at 20 to 90 ° C. for about 10 to 50 hours. For example, it is possible to introduce sulfonic acid groups on the surface by treating polystyrene particles with fuming sulfuric acid.

The sulfonating agent may be selected from known sulfonating agents, and examples thereof include sulfuric acid, fuming sulfuric acid, chlorosulfuric acid, sulfur trioxide and the like, and one or more of them may be used. You can

The average particle size of the display particles 60 is 0.
1 to 100 μm is preferable, and 0.5 to 30 μm
Particularly preferably m. If the average particle diameter of the display particle body 60 is less than 0.1 μm, aggregation or adhesion easily occurs,
If it exceeds 100 μm, sedimentation tends to occur.

Furthermore, it is preferable to adjust the water content (water content) in the display particles 60 to 0.5 to 5% by weight. The display particle body 60 according to the present embodiment has a large surface area due to the presence of the hollow portion, and therefore contains a specific amount of water on the surface and inside. This is because the water has a great influence on the moving speed, the sedimentation / aggregation, and the adhesion of the display particles 60. For this reason, it is particularly preferable that the water content in the display particle body 60 is once removed and then the water content is added again to adjust the water content. Specifically, these display particles are immersed in an appropriate organic solvent (for example, propylene carbonate (PC)) and fractionally distilled to once reduce the water to a level at which water can be removed to some extent. Then, a predetermined amount of water is added to adjust the water content. If the water content is less than 0.5% by weight, charging becomes difficult and the moving speed becomes slower. On the contrary, if the water content exceeds 5% by weight, aggregation and adhesion are likely to occur.

If the display particles 60 are directly dried by using a vacuum dryer or the like without using an organic solvent for removing water, the display particles 60 are aggregated with each other, and the display particles 60 are uniformly dispersed in the dispersion solvent 50. Dispersion may be hindered.

Known dyes and pigments can be used for coloring the display particles 60, but pigments are preferable,
Carbon black, titanium black and the like are suitable.

[0079]Sphere 70 The spherical body 70 moves to the intermediate substrate 20 side as described above.
Function as a concealing material that hinders the visibility of the display particle body 60.
As a result, the display particle body 60 has different brightness and color.
Must have Teflon as its material
(Registered trademark) is preferably used.

As described above, the spherical body 70 functions as a spacer for maintaining the space between the intermediate substrate 20 and the transparent layers 31 and 32, so that the display layer 4 is provided.
Within 1, 42, it is preferable to take a two-dimensional closest packing structure. However, other filling structures may be used as long as the filling structure exerts an effect as a spacer. For example, when the diameter of the spherical body 70 is R, the diameter of the granular body is r, and the distance between the intermediate substrate 20 and the transparent layer 31 (32) is D, the relationship of 100r>R> 10r, 5R>D> 2R is satisfied. It is also preferable to select the sizes of the display particle bodies 60 and the spherical bodies 70 as described above, and to form the three-dimensional close-packed structure in which the spherical bodies 70 having the two-dimensional close-packed structure are laminated in the order of 2 to 6 layers. Note that FIG. 1 shows a three-dimensional close-packed structure in which two spherical bodies 70 having a two-dimensional close-packed structure are laminated.

The spherical body 70 does not have to be fixed to the intermediate substrate 20, but it must be fixed to the intermediate substrate 20 in order to reliably prevent movement of the spherical body 70 due to application of an electric field. Is preferred. As a fixing method, the spherical body 70 may be placed on the intermediate substrate 20, an ultraviolet curable resin may be applied, and then cured.

As described above, the spherical body 70 has a role as a masking material for hindering the visual recognition of the display particle body 60, but in order to assist the masking effect, the ultrafine particles are further dispersed in the dispersion solvent 50. It is also preferable to leave it. As such ultrafine particles, the particle size is preferably 0.05 μm or less, and the addition amount is preferably 1 to 10% by volume. Even though the ultrafine particles themselves are transparent, the dispersion solvent 50 in which they are dispersed appears slightly white and turbid. Therefore, for example, when the display particle body 60 is black, the display particle body 60 is
Is slightly separated from the transparent layers 31 and 32 which are the display surfaces, the blackness of the portions on the display surface is lowered.

[0083]Transparent layers 31, 32 The material of the transparent layers 31 and 32 is substantially transparent
Fine particles with lubricity in the main component consisting of resin and ceramics
Child (lubricating particles), such as fine particles of silicone rubber or TE
Freon resin (polytetrafluoroethylene (PTF
E), Polyvinylidene fluoride (PVDF), Par
Fluoroalkoxy alkane (PFA), tetrafluor
Polyethylene-hexafluoropropylene copolymer (FE
P) etc.) It is preferable to use a powder to which a powder is added.
Yes.

In this embodiment, the transparent layers 31, 32
Since the lubricative particles are added to the main component of (1), it has the advantages of good surface slipperiness and scratch resistance. Therefore, the carry-in mechanism 120 and the carry-out mechanism 13
Since it is possible to carry out the transport by 0 smoothly and it is possible to reduce the scratches generated during the transport, it is possible to prevent the deterioration of the contrast due to the scratches on the display surface. Further, when the electrophoretic display device 10 is made of electronic paper by making the intermediate substrate 20, the transparent layers 31, 32 and the display layers 41, 42 flexible, as described above, the carry-in mechanism 120 and / or the carry-out mechanism 130. It is conceivable that the roller is wound around a roller and conveyed in a curved state. In such a case, scratches are particularly likely to occur during transportation, but the electrophoretic display device 1 according to the present embodiment
In No. 0, since the lubricating particles are added to the main components forming the transparent layers 31 and 32, even in such a situation, it is possible to effectively prevent scratches on the transparent layers 31 and 32. It will be possible. Considering this, the present invention is more suitable for application to electronic paper. In particular, since double-sided display type electronic paper is used in an environment where it is extremely vulnerable to scratches, such as being piled up during use, just like actual paper,
The present invention is most preferably applied to double-sided display type electronic paper.

The particle size of the lubricating particles is 0.2 to 10
It is preferably μm. Lubricant particle size is 0.2
If it is less than μm, the lubricity is not sufficiently enhanced, so that scratches are likely to occur, and conversely, the particle size of the lubricating particles is 10 μm.
When it exceeds, the transparency of the transparent layers 31 and 32 is deteriorated and the transparency is lowered, and the voltage application by the electric field applying mechanism 110 is hindered.

The addition amount of the lubricating particles is preferably 0.5 to 5% by volume based on the resin or ceramic as the main component. If the amount of the lubricating particles added is less than 0.5% by volume, scratches are likely to occur because the lubricity cannot be sufficiently enhanced, and conversely, the amount of the lubricating particles added is 5% by volume.
If it exceeds, the transparency is lowered and the initial contrast is deteriorated.

The thickness of the transparent layers 31 and 32 is preferably 0.5 to 10 times the particle size of the lubricating particles. As described above, the particle size of the lubricating particles is 0.2 to 10
Since it is preferably μm, the transparent layers 31 and 32 are
The preferable film thickness of is 0.1 to 100 μm. When the film thickness of the transparent layers 31 and 32 is less than 0.1 μm, the lubricating particles are easily detached from the transparent layers 31 and 32. Conversely, when the film thickness of the transparent layers 31 and 32 exceeds 100 μm, the transparency is reduced. Will decrease.

As the transparent layers 31 and 32, a solid film is not used from the beginning, but a material obtained by adding the above-mentioned lubricating particles to a curable transparent liquid raw material (which may contain a solvent) is used as the display layer 41. , After coating on 42,
It is particularly preferable to form a film by carrying out a curing treatment or the like. This is because the display layers 41 and 42 contain the dispersion solvent 50 composed of a liquid,
This is because if the transparent layers 31 and 32 as the solid films are pasted onto the 42, air or the like will be mixed into the display layers 41 and 42. On the other hand, according to the method described above, it is possible to effectively prevent the entry of air or the like into the display layers 41 and 42, so that the so-called sealing and sealing processes are facilitated.

As the curable transparent liquid raw material, for example, an active energy polymerizable resin such as an ultraviolet curable or electron beam curable resin, or a ceramic raw material which is polymerized by a sol-gel reaction by heat or laser can be used. Among these, it is particularly preferable to use an ultraviolet curable resin. Further, in order to form the transparent layers 31 and 32 by the above method, as the curable transparent liquid raw material, a material having a lower specific gravity than the dispersion solvent 50 and having no mutual solubility with the dispersion solvent 50 is selected. There is a need. As described above, in this embodiment, since the dispersion solvent 50 is a mixed solvent of dimethyl silicone oil and modified silicone oil, the curable transparent liquid raw material has a lower specific gravity than silicone oil and It is necessary to select materials that are not mutually soluble. When a UV-curable resin is used as the curable transparent liquid material, in order to improve the surface properties of the UV-curable resin, a UV-transparent film or the like is brought into close contact with the uncured resin layer surface, and after curing, a UV-transparent film or the like is used. Peeling is preferable. This improves the surface properties of the ultraviolet curable resin and suppresses curing inhibition by oxygen.

As the ultraviolet curable resin, a known one prepared by mixing a prepolymer, a monomer with a photoinitiator, a sensitizer and the like can be used. The prepolymer provides the basic physical properties of the cured product, and is an important component that forms the resin skeleton. From the structure, polyester acrylate, epoxy acrylate, urethane acrylate, silicone resin (organopolysiloxane compound), polyester methacrylate, urethane methacrylate, etc. Are known. The prepolymer used in this embodiment may be any of these prepolymers, or a blended product thereof can also be used.

Further, the transparent layers 31, 32 are formed by the above method.
In order to form, the shrinkage ratio of the ultraviolet curable resin at the time of curing is preferably 5% or less, more preferably 3% or less. When the contraction rate exceeds 5%, distortion due to stress occurs in the entire electrophoretic display device, which causes curling and lowering of contrast.

It is possible to prevent bubbles from entering the display layers 41 and 42 by degassing the dispersion solvent 50 under reduced pressure before coating the curable transparent liquid raw material. In order to perform degassing more effectively, it is preferable to reduce the pressure to 300 torr or less while applying vibration, and more preferable to reduce the pressure to 100 torr or less. In addition, in order to perform degassing more effectively,
It is preferable to bring the dispersion solvent 50 into a reduced pressure state while heating. Therefore, for example, 80 ° C., 600 seconds, 80
250H with external speaker under torr condition
The reduced pressure heat treatment may be performed while applying the sound pressure vibration of z.
It should be noted that if the decompression rate is too fast, rapid foaming will occur and the silicone oil or the like that constitutes the dispersion solvent 50 will scatter.

Further, after coating the curable transparent liquid raw material and before curing it, the dispersion solvent 50 and the uncured transparent liquid raw material are subjected to degassing under reduced pressure. It becomes possible to more effectively prevent the inclusion of air bubbles. Also in this case, it is preferable to perform the degassing under reduced pressure under the conditions described above.

Further, the transparent layers 31 and 32 are formed according to JIS K-
It is preferably H or higher in 5400 (pencil hardness test). This is because when the pencil hardness is less than H, it is easily scratched during use, especially by contact with the electrode 113 or the writing pen forming the electric field applying mechanism 110, which causes a reduction in contrast.

Further, in order to keep the transparency of the transparent layers 31 and 32 high, it is preferable that the refractive index of the lubricating particles is closer to that of the resin or ceramic which is the main component. Specifically, it is preferable that the difference in refractive index between the two is within 0.3. For example, when an epoxy-based ultraviolet curable resin (refractive index: 1.5) is used as the main component, silicone rubber (refractive index: 1.6) or amorphous fluorine-based resin (for example, refraction index) is used as the lubricating particles. It is preferable to use a ratio of 1.3).

[0096]Intermediate substrate 20 The intermediate substrate 20 includes a base 21 made of an insulating material and a base 2.
1. Conductive layers 22 and 23 provided on both sides of
It is preferable that the display layer 41 and the display layer 42 are
There is a layer that can be separated and has conductivity.
As long as it exists, it is not limited to such a structure.
Yes. Therefore, for example, the entire intermediate substrate 20 is made of metal.
Therefore, the base 21 may be made of metal.
Therefore, even if it is configured and an insulating layer is provided on both sides
I do not care.

The substrate 21 has a thickness of 10 to 500 μm.
Polymer films such as polyethylene terephthalate and polyether sulfone, or inorganic materials such as glass and quartz, or composite materials thereof can be used.
Further, as the conductive layers 22 and 23, it is preferable to use conductive resin or metal. When the entire intermediate substrate 20 is made of metal, it is preferable to use a flexible metal foil having a thickness of 1 to 100 μm, particularly a rolled copper foil. When the electrophoretic display device itself is made to be electronic paper by making it flexible, it is necessary to select a flexible material as the material of the intermediate substrate 20.

The conductive layers 22 and 23 can be formed by vapor deposition, sputtering, plating, conductive ink coating, conductive resin coating, or the like. For example, by coating a polyethylene terephthalate film with a conductive resin having a film thickness of 1 μm, the conductive layer 2 is formed on both surfaces of the base 21.
It is possible to easily make 2 and 23 conductive.

Further, the intermediate substrate 20 may include various other functional layers.

Incidentally, also on the transparent layers 31, 32, if a layer made of a conductive material is provided on the display layers 41, 42 side,
Although the display content retention property is improved, in this case, such a conductive material needs to be a substantially transparent material typified by ITO (indium tin oxide). Generally, since a conductive material having transparency is expensive, it is not always appropriate to provide a layer made of a conductive material on the surfaces of the transparent layers 31 and 32 in consideration of cost.

[0101]

【Example】Example 1 First, a polyethylene terephthalate film having a film thickness of 30 μm
Prepare a rum and put white conductive resin on both sides of 5 μm
The intermediate substrate 20 was manufactured by applying.

Next, as the spherical body 70, the diameter is 100 μm.
The white Teflon spherical body of is prepared and is used as the intermediate substrate 20.
Two layers were arranged in a close-packed structure on one surface and fixed to the intermediate substrate 20 using an ultraviolet curable resin. Here, the color of the spherical body 70 is the basic color of display in the electrophoretic display device,
That is, the display color is after initialization.

Next, a black display particle body 60 made of sulfonated polystyrene fine particles was prepared by the following method. First, 500 g of 98% by weight sulfuric acid was cooled to 0 ° C., and 50 g of commercially available carbon black-containing porous polystyrene particles was put therein. Then, raise the temperature to 100 ° C for 1
The sulfonation reaction was allowed to proceed by stirring for 2 hours, and the obtained display particles were gradually immersed repeatedly in dilute sulfuric acid to reduce the sulfuric acid concentration. Further, after neutralizing with a 10 wt% lithium hydroxide aqueous solution, it was thoroughly washed with water. Then, it was dried in a vacuum dryer at 80 ° C. for 10 hours and classified to obtain spherical sulfonated polystyrene fine particles having a diameter of 2.5 μm. The carbon black content of the obtained sulfonated polystyrene fine particles was about 10% by weight, and the hollow ratio was about 50%. Next, the obtained sulfonated polystyrene fine particles were dispersed in a PC solution, subjected to fractionation treatment at 60 ° C. for dehydration, and the water content was measured. As a result, the water content was 0.05% by weight. Then, water was added to the sulfonated polystyrene fine particles to adjust the water content to 0.75% by weight (water content adjustment treatment). Thus, a black display particle body 60 made of sulfonated polystyrene fine particles was produced.

Next, 4.0% by weight of the display particles 60 are
Dimethyl silicone oil (KF96-5 made by Shin-Etsu Chemical)
95.6% by weight, polyether silicone oil 0.4
After dispersing in 50% by weight dispersion solvent 50,
Degassing was performed for 30 minutes at rr to obtain a dispersion (1).

Then, the dispersion (1) was prepared by a spray method.
Was coated on the intermediate substrate 20 on which the spherical bodies 70 were spread.
Further, deaeration treatment was performed at 80 torr for 5 minutes to form the display layer 41.

Next, on the display layer 41 by a spray method,
Epoxy UV curable resin (PTFE fluororesin powder (particle size 1 μm) added at 1% by volume), 80t
Degassing was performed for 5 minutes at orr. A 100 μm-thick UV-transmissive film that had been subjected to a fluorine coating treatment was placed thereon, and then a metal halide lamp was used to irradiate the UV with an integrated light amount of 80 mJ / cm ² . As a result, the ultraviolet curable resin was cured and the transparent layer 31 having a film thickness of 3 μm was formed.

After the curing treatment, the UV transparent film was peeled off. The surface property of the cured ultraviolet curable resin was equivalent to that of a normal resin film because the surface of the ultraviolet transmissive film was transferred.

The above-mentioned steps were performed on the back surface of the intermediate substrate 20, and the electrophoretic display device according to Example 1 was completed.

When the above epoxy-based ultraviolet curable resin was separately applied to a glass substrate and cured and evaluated, the shrinkage ratio was 1.3% and the pencil hardness after curing was 2H.

[0110]Example 2 In place of the dispersion solvent of the dispersion (1) used in Example 1.
Methylphenyl silicone oil 93.6% by weight,
Dispersion consisting of 2.4% by weight of amino-modified silicone oil
Example 2 using the same method as in Example 1 except that the medium was used.
An electrophoretic display device was manufactured according to.

[0111]Example 3 In place of the dispersion solvent of the dispersion (1) used in Example 1.
Dimethyl silicone oil 94.4% by weight, carbo
Dispersion consisting of 1.6 wt% of xyl-modified silicone oil
Example 3 using the same method as in Example 1 except that the medium was used.
An electrophoretic display device was manufactured according to.

[0112]Example 4 In place of the dispersion solvent of the dispersion (1) used in Example 1.
Dimethyl silicone oil 89.8% by weight, polyethylene
Ether-modified silicone oil 1.2% by weight, fluorocarbon
Other than using dispersion medium consisting of 5.0% by weight of corn oil
Using the same method as in Example 1, swimming according to Example 4
A dynamic display device was produced.

[0113]Example 5 The black display particle body 60 used in Example 1 was
Pour into toluene containing coal-modified silicone oil and heat
After refluxing, the unreacted materials are removed to remove particles on the surface of the granular material.
The lucol-modified silicone oil is subjected to an esterification reaction, etc.
Combined. Alcohol-modified silicone according to calculations
The proportion of oil was 1% with respect to the display particles. this
Disperse the display particles 60 in the same dispersion solvent 50 as in Example 1.
After that, the same method as in Example 1 was used to obtain Example 5.
An electrophoretic display device was manufactured.

[0114]Example 6 Dispersion without the degassing treatment during the production of Dispersion (1)
The body (2) is prepared, and the dispersion (2) is used in place of the dispersion (1).
And the same method as in Example 1 is used.
An electrophoretic display device was manufactured.

[0115]Comparative example In place of the dispersion solvent of the dispersion (1) used in Example 1.
Dimethyl silicone oil (KF96- manufactured by Shin-Etsu Chemical)
5) Other than using a dispersion solvent consisting only of 96.0% by weight
Is the electrophoresis according to the comparative example using the same method as in Example 1.
A display device was manufactured.

[0116]Evaluation The electrode 113 that constitutes the electric field applying mechanism 110 is a photolithography
Consists of thin film titanium electrodes manufactured by the graphic method and is carried in
A book in which the mechanism 120 and the carry-out mechanism 130 are composed of transport rolls.
A setting device 100 was prepared. The pitch of the electrodes 113 is 2
00 μm, 50 voltage applying parts are divided into two rows and
It is arranged like an inn. That is, a 25 × 2 arrangement
Thus, it is possible to record two rows at a time. Switch 1
14 is composed of a TFT (thin film transistor)
ing.

Next, the electrophoretic display device according to each of Examples 1 to 6 and the comparative example is transported to the electric field applying mechanism 110 at a speed of 10 mm / sec using the carrying rolls constituting the carry-in mechanism 120.
While being conveyed to, the first electric field application head 111 is used to display a black and white stripe having a width of 1 cm on one display surface of the electrophoretic display device so that an intermediate portion between the electrode 113 and the electrophoretic display device is displayed. A voltage of 250 V was applied between the substrates 20. On the other display surface of the electrophoretic display device, the second electric field applying head 112 is used to display the electrode 11 so that a black and white stripe having a width of 7 mm is displayed.
A voltage of 250 V was applied between the electrode 3 and the intermediate substrate 20 of the electrophoretic display device.

At this time, the amount of current flowing through the intermediate substrate 20 through one electrode 113 was measured.

One minute after the above writing is completed, the reflectance of the portion displayed in white and the portion displayed in black on the display surface of the electrophoretic display device are respectively measured by a reflectometer. The measurement was performed, and the ratio was used as the initial contrast. One minute later was set because it was difficult to evaluate because there was a device that changed greatly immediately after writing.

Further, the transport speed of the electrophoretic display device by the transport roll is changed so that the contrast is 10 mm.
The transfer speed that decreased to half of the second / second was determined, and this was set as the limit transfer speed. The limit transfer rate is correlated with the display switching time. Further, repeated writing (conveyance) was performed, and the number of times the contrast became half of the initial contrast was defined as the life.

The measurement results are shown in Table 1. In addition, in Table 1,
The addition amount of the modified silicone oil to the display particle body 60 and the resistance value of the dispersion solvent 50 are also shown.

[0122]

[Table 1] As shown in Table 1, the electrophoretic display device according to the comparative example has
Since the dispersion solvent consists only of dimethyl silicone oil and no modified silicone oil is added, the initial contrast is low, the life is short, and the limit transfer rate is slow. On the other hand, in Examples 1 to 6 in which the modified silicone oil was added, the initial contrast was 10 or more and the life was 5
The characteristics of 100 times or more and the limit transfer rate of 100 mm / sec or more are obtained.

However, in Example 2 in which the modified silicone oil was added in a large amount, a large amount of current was passed through the dispersion solvent 50 due to the low solvent resistance, resulting in a shorter life than in Example 1. It was

Also in Example 6 in which the dispersion was not degassed in advance, the current value was higher than that in Example 1, and bubbles were adhered to the surface by repeated writing, resulting in a decrease in contrast. The decline became faster.

When 30% of the dimethyl silicone oil used in Example 1 was replaced with fluorosilicone oil, the limit transfer rate was further increased to 350 mm / sec.

As described above, in the electrophoretic display device 10 according to the present embodiment, a mixed solvent of dimethyl silicone oil (dimethyl polysiloxane) and modified silicone oil is used as the dispersion solvent 50 contained in the display layers 41 and 42. Since it is used, the dispersibility of the display particle body 60 is significantly improved as compared with the conventional electrophoretic display device. Therefore, not only a high contrast can be obtained, but also a high rewriting speed can be obtained.

Further, in the electrophoretic display device 10 according to this embodiment, the display particle body 60 having the hollow portion communicating with the outside is used as the display particle body 60 included in the display layers 41 and 42. When the display particle body 60 is dispersed in the dispersion solvent 50, the dispersion solvent 50 easily penetrates into the hollow portion. As a result, the apparent specific gravity of the display particle body 60 becomes closer to the dispersion solvent 50, and the movement of the display particle body 60 due to gravity is suppressed, so that it is possible to obtain high contrast.

Furthermore, in the electrophoretic display device 10 according to the present embodiment, the transparent layers 31 and 32 forming the display surface.
As a material obtained by adding fine particles having lubricity (lubricant particles) to a main component made of a resin or ceramic that is substantially transparent, is used as a transparent layer 31 compared with a conventional electrophoretic display device. The lubricity is greatly improved.
Therefore, the display surface is not easily scratched, and high contrast can be obtained.

Furthermore, in the electrophoretic display device 10 according to the present embodiment, the intermediate substrate 20, the display layers 41 and 42,
Since both transparent layers 31 and 32 can be formed by a printing method, they can be manufactured at low cost.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. It goes without saying that it is a thing.

For example, in the electrophoretic display device 10 according to the above embodiment, the spherical bodies 7 are provided in the display layers 41 and 42.
Although 0 is arranged, it is not essential to use such a spherical body 70 in the present invention, and this may be omitted. Further, instead of the spherical body 70, a mesh structure having a function as a spacer is used, or the intermediate substrate 20 is used.
A large number of rod-shaped bodies such as cylinders and triangular prisms may be interposed between the transparent layers 31 and 32 and the transparent layers 31 and 32. In this case, it is preferable that the mesh structure and the rod-shaped body have different brightness and color from those of the display particle body 60. As the mesh structure, specifically, a mesh cloth, which is a cloth for industrial use, in which threads are woven in a cross shape can be preferably used.
If the aperture ratio is too high, the aperture ratio is lowered and the contrast of the display device is improved by devising such as stacking with another fabric that has been rotated in the in-plane direction of 45 degrees and stacking several fabrics. It becomes possible.

In the electrophoretic display device 10 according to the above embodiment, the display particle body 60 and the spherical body 70 can be displayed by having different brightness and color from each other. And dispersion solvent 50
Alternatively, the display may be performed by giving different lightness / color to each other, or by using two types of granular bodies having different lightness / color and being charged with opposite polarities. Further, by using display particle bodies 60 having several kinds of different electrophoretic velocities (different zeta potentials) and coloring these display particle bodies 60 respectively,
It is also possible to display in color based on the driving voltage.

Further, the transparent layers 31, 32 and the intermediate substrate 2
0 is provided with a matrix-shaped electrode, and each of these electrodes is connected to a TFT or MIM (Metal-In).
The display content may be configured to be changeable without using the writing device 100 by being driven by a switch such as a modulator-metal).

Further, between the transparent layers 31 and 32 and the intermediate substrate 20, a large number of microcapsules having a diameter of about 30 to 200 μm, in which the display particle bodies 60 and the dispersion solvent 50 are enclosed, are arrayed to form the display layers 41 and 42. May be configured.

Further, another transparent layer may be added to the surfaces of the transparent layers 31 and 32 by a printing method or a film sticking method. In this case, it is desirable that the transparent layer to be added has high abrasion resistance and lubricity. It is also desirable to have a function of blocking ultraviolet rays. If a color filter (RGB filter) is used as the transparent layer to be added, it is possible to color the display content that is originally black and white.

The writing device 100 described above is provided with a plurality of electrodes 113.
It can be individual. In this case, by scanning the electrode 113 with respect to the display surface in the X and Y directions,
You can write desired characters and figures.

Furthermore, it is possible to further enhance the function of the electrophoretic display device according to the present invention by using various known techniques. For example, energy can be supplied by forming an amorphous solar cell on the back surface and / or the peripheral portion of the display surface, wireless charging is possible by incorporating a sheet-shaped secondary battery and a plane coil, a plane antenna, etc. It is also possible to add a wireless communication function by incorporating, and control the display content by an external signal.

[0138]

As described above, according to the present invention,
It is possible to provide an electrophoretic display device having high contrast.

[Brief description of drawings]

FIG. 1 is a perspective sectional view partially showing an electrophoretic display device 10 according to a preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing the structure of a writing device 100 for displaying characters, figures, etc. on the electrophoretic display device 10.

FIG. 3 is a diagram showing the structure of an electric field applying mechanism 110 in more detail.

4A and 4B are cross-sectional views showing an example of a display particle body 60. FIG.

[Explanation of symbols]

10 Electrophoretic display device 20 Intermediate substrate 21 Base 22, 23 Conductive layer 31, 32 Transparent layer 41, 42 display layer 50 Dispersion solvent 60 display particles 61 cavity 62 opening 63 through hole 70 Spherical body 100 writing device 110 Electric field applying mechanism 111 First electric field applying head 112 Second electric field applying head 113 electrodes 114 switch 120 carry-in mechanism 130 Unloading mechanism

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Claims (9)

[Claims] 1. An electrophoretic display device comprising a display layer having at least a dispersion solvent and display particles dispersed in the dispersion solvent, wherein the dispersion solvent is a mixed solvent of silicone oil and modified silicone oil. An electrophoretic display device comprising: 2. The modified silicone oil is 1 or 2 selected from the group consisting of alcohol-modified silicone oil, polyether-modified silicone oil, carboxyl-modified silicone oil and amino-modified silicone oil.
The electrophoretic display device according to claim 1, wherein the electrophoretic display device is the modified silicone oil described above. 3. The amount of the modified silicone oil added is
The electrophoretic display device according to claim 1 or 2, wherein the content of the display particles is 0.1 to 100% by weight. 4. The amount of the modified silicone oil added is
The electrophoretic display device according to claim 3, wherein the content of the display particles is 0.5 to 30% by weight. 5. The electrophoretic display device according to claim 1, wherein at least a part of the silicone oil is fluorosilicone oil. 6. The electrophoretic display device according to claim 1, wherein the dispersion solvent is degassed under reduced pressure. 7. The double-sided display is possible by providing the two display layers.
An electrophoretic display device according to any one of items 1 to 6. 8. A step of deaeration under reduced pressure for a dispersion solvent comprising silicone oil and a modified silicone oil, in which display particles are dispersed, and applying the degassed dispersion solvent onto a substrate. A step of forming a display layer,
And a step of forming a transparent layer on the display layer. 9. The method further comprising the step of performing a vacuum degassing treatment on the display layer after applying the dispersion solvent on the substrate and before forming the transparent layer on the display layer. The method for manufacturing an electrophoretic display device according to claim 8.