JP2007148009A - Electrophoresis display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin electrophoresis display device which has flexibility. <P>SOLUTION: The electrophoresis display device A has at least insulating liquid, one or more kinds of charged particles, and a structure material formed between substrates arranged opposite each other, between the substrates, and a part of the structure material 20 which is present at least at a display part is not fixed to the substrates. Mutual condensation and maldistribution of particles of the electrophoresis display device are therefore suppressed to prevent display quality and driving characteristics from being impaired, and even the electrophoresis display device having flexibility can maintain a stable substrate gap against deformation and can be manufactured at a low cost. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophoretic display device capable of reversibly changing a visual state by the action of an electric field or the like, and more particularly to a thin electrophoretic display device having flexibility.

  In recent years, with the development of information equipment, the demand for low power consumption, thinning, and flexibility of display devices has increased, and research and development of display devices that meet these demands have been actively conducted. .

  As one of such display devices, an electrophoretic display device invented by Harold D. Lees et al. (For example, see Patent Document 1) is known. In this electrophoretic display device, two electrode substrates, at least one of which is transparent, are arranged to face each other via a suitable spacer, and between these electrode substrates, electrophoretic particles (pigment particles, etc.) having either positive or negative charge are placed. The display particles are dispersed in a solvent colored in a different color and the dispersion is filled between the substrates to form a display panel. An electric field is applied to the display panel to obtain a display on the transparent electrode surface.

  The electrophoretic display liquid filled between the electrode substrates is low in xylene, tetrachloroethylene, paraffin, silicone oil or the like in which electrophoretic particles such as titanium dioxide and a dye for contrasting the electrophoretic particles are dissolved. It is composed of a dispersion solvent of dielectric constant, a dispersant such as a surfactant, and an additive such as a charge imparting agent. By applying an electric field to the electrophoretic display liquid, the electrophoretic particles in the ink move to the transparent electrode side, and the color of the fine particles appears on the display surface. By applying an electric field in the opposite direction, the electrophoretic particles are It moves to the opposite side, and the color of the dispersion colored with the dye appears on the display surface.

  Such an electrophoretic display device is a display device that can obtain a desired display by controlling the direction of an electric field, is low in cost, has a viewing angle as wide as that of a normal printed material, consumes less power, and displays. It has attracted attention as an inexpensive display device because of its advantages such as having a memory property.

  However, the fine particles used in the electrophoretic display liquid may deteriorate due to the aggregation of the particles when stored for a long time, or the uneven distribution of particles during repeated display. Has the problem that it is easy to occur.

  As a method for preventing display non-uniformity due to uneven distribution of electrophoretic display fine particles on the display surface, particles can be obtained by filling an electrophoretic display liquid in a number of small chambers (cells) that have been finely isolated. Many methods for suppressing aggregation and uneven distribution of each other, a configuration of a small room (cell), a manufacturing method, and the like have been proposed (see, for example, Patent Documents 2 to 8).

  According to the above method and the like, it is possible to suppress aggregation and uneven distribution of particles, but walls and the like that form a large number of small cells (cells) are formed in a state of being fixed, adhered, or the like to the substrate. Therefore, when it is curved as a thin electrophoretic display device, there is a problem that stress acts between the wall and the substrate, and the wall is easily broken or the display is deteriorated.

  Further, in order to keep the distance between the electrodes constant, or to keep the thickness of the dispersion constant, a display device having a blocking substance made of an insulating porous layer has been proposed (for example, (See Patent Document 9). According to this method, the short circuit is prevented, the thickness can be kept uniform, the lateral flow of the dispersion is prevented, etc., but at least when the portion existing in the display is not fixed to the substrate Is not specifically mentioned.

On the other hand, a method of encapsulating an electrophoretic display liquid in microcapsules and using it as display particles (for example, see Patent Document 10), or at least two types of electrophoresis in which a color tone and electrophoretic property are different from each other in a colorless dispersion medium An example in which a liquid in which a fine particle is dispersed is included in a microcapsule has been proposed (see, for example, Patent Document 11).
However, according to this technique, even if it is curved as a thin electrophoretic display device, the stress is relieved because it has a certain degree of flexibility. It is necessary to go through a process such as coating, and there is a problem that a complicated method has to be taken for manufacturing an electrophoretic display device.
US Pat. No. 3,612,758 (Claims, Examples, etc.) JP-A-49-61075 (Claims, Examples, etc.) JP-A-5-61075 (Claims, Examples, etc.) JP 2001-159765 A (Claims, Examples, etc.) JP 2002-148862 A (claims, examples, etc.) JP 2002-292736 A (Claims, Examples, etc.) JP 2004-20640 A (Claims, Examples, etc.) Japanese Patent No. 3189958 (Claims, Examples, etc.) Japanese Patent Publication No. 50-15355 (Claims, Examples, etc.) Japanese Patent No. 2551783 (Claims, Examples, etc.) WO98 / 03896 (Claims, Examples, etc.)

  The present invention is to solve this problem in view of the above-described problems of the prior art, suppresses aggregation and uneven distribution of particles in an electrophoretic display device, without impairing display quality and driving characteristics, and An object of the present invention is to provide an electrophoretic display device which can maintain a stable substrate gap (gap) corresponding to deformation even in an electrophoretic display device having flexibility, and can be manufactured at a low cost.

  As a result of intensive studies to solve the above-described conventional problems, the present inventors have found that at least an insulating liquid, at least one kind of charged particle, and a structural material formed between the substrates are disposed between the substrates arranged to face each other. In the electrophoretic display device having the above structure, it is found that the object electrophoretic display device can be obtained by making at least a portion of the structural material existing in the display portion into a specific structure, and the present invention is completed. It was.

  That is, the electrophoretic display device of the present invention is an electrophoretic display device comprising at least an insulating liquid, one or more kinds of charged particles, and a structural material formed between the substrates between the substrates arranged opposite to each other. In the structural material, at least a portion existing in the display portion is not fixed to the substrate.

  According to the present invention, aggregation and uneven distribution of particles in an electrophoretic display device are suppressed, display quality and driving characteristics are not impaired, and the electrophoretic display device having flexibility is stable in response to deformation. There is provided an electrophoretic display device that can maintain a substrate interval (gap) and can be manufactured at low cost.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a drawing showing an example of an embodiment of an electrophoretic display device of the present invention, where (a) is a schematic cross-sectional view of the electrophoretic display device, and (b) is a structural material that is the gist of the present invention between substrates. (A) The partial expanded sectional view of the round mark part which shows the state which is not fixed to (c), (c) is a perspective view of a structural material.

  The electrophoretic display device A according to the present embodiment includes at least an insulating liquid, one or more kinds of charged particles, and a structural material 20 formed between the substrates, between the substrates 10 and 15 arranged to face each other. The structural member 20 is characterized in that at least a portion existing in the display portion is not fixed to the substrate 10.

In the present invention, as the substrates 10 and 15 arranged opposite to each other, for example, a transparent conductive material such as ITO or ZnO is applied to a transparent resin film or transparent glass or the like, a vapor deposition method such as an ion plating method or a sputtering method. A light-transmitting material formed by the above, a material in which a conductive material film (layer) such as a metal is formed on the surface of a non-conductive material such as a resin film, a resin plate, glass or ceramics, or a metal plate can be used. .
These substrates 10 and 15 can be formed by patterning by a conventionally used method such as photoetching, or a TFT (Thin Film Transistor) substrate used in a liquid crystal or the like. Although it is possible to use, it is not limited to these.
Further, when used as a display device, at least one of the counter substrates is a light-transmitting substrate, but it is naturally possible to use not only the display surface side but also the back surface side as a light-transmitting substrate. is there.

As the insulating liquid used in the present invention, various types conventionally used for electrophoretic display can be used.
Specifically, aliphatic hydrocarbons such as aromatic hydrocarbons, hexane, cyclohexane, kerosene, isopar, paraffin hydrocarbons, halogenated hydrocarbons, phosphate esters, phthalate esters, carboxylic acids Examples thereof include, but are not limited to, esters, chlorinated paraffin, N, N-dibutyl-2-butoxy-5-tertioctylaniline, and the like.

  As the charged fine particles used in the present invention, colored or colorless (white) inorganic pigment particles, organic pigment particles, polymer fine particles and the like can be used. The pigment particles defined in the present invention are those that have low solubility in an insulating liquid in combination with the insulating liquid used as a dispersion medium, and can exist in a dispersed particle state in the insulating liquid. .

  Examples of inorganic pigment particles that can be used include titanium dioxide, zinc sulfide, calcium carbonate, silica, calcium silicate, antimony oxide, kaolin, mica, barium sulfate, gloss white, alumina white, talc, cadmium yellow, and yellow oxidation. Iron, titanium yellow, cadmium orange, molybdate orange, bengara, red lead, silver vermilion, cadmium red, brown iron oxide, zinc iron, chrome brown, chrome green, chromium oxide, viridian, cobalt green, cobalt chrome green, bitumen, cobalt Examples include blue, ultramarine blue, cerulean blue, cobalt violet, carbon black, iron black, black low-order titanium oxide, aluminum powder, copper powder, lead powder, tin powder, and zinc powder.

  Examples of organic pigment particles that can be used include fast yellow, disazo yellow, condensed azo yellow, isoindoline yellow, quinophthaloin yellow, benzimidazolone yellow, monoazo yellow lake, dinitroaniline orange, perinone orange, and naphthol red. , Toluidine Red, Permanent Carmine, Brilliant Fast Scarlet, Rhodamine 6G Lake, Permanent Red, Lake Red, Priliant Carmine, Naphthol Red, Quinacridone Magenta, Condensed Azo Red, Naphthol Carmine, Berylens Car Red, Condensed Azo Scar Red, Perylene Red, Quinacridone red, diketopyrrolopyrrole red, benzimidazolone brown, phthalocyanine green, Victoria Bull Lake, Phthalocyanine Blue, Fast Sky Blue, Rhodamine B lake, methyl violet lake, dioxazine violet and the like.

  As the polymer fine particles that can be used, polymer fine particles comprising an organic polymer produced by a conventionally known method can be used. For example, a method using emulsion polymerization, a seed emulsion polymerization method, a soap-free method. Polymerization method, dispersion polymerization method, suspension polymerization method, seed polymerization method, method using seed polymerization + polymerization shrinkage, method using suspension polymerization of W / O / W emulsion, surface drying of spray-dried droplets Examples thereof include a seed agglomeration method in which a polymer emulsion is agglomerated by adding electrolyte solid particles, but is not limited to those produced by these methods.

  In addition, as the material of the polymer fine particles, a material selected from conventionally known polymer materials can be used in a combination that does not dissolve in a transparent dispersion medium used for electrophoretic display. Examples of these are styrene, styrene-acrylic, styrene-isoprene, divinylbenzene, methyl methacrylate, methacrylate, ethyl methacrylate, ethyl acrylate, n-butyl acrylate, acrylic acid, acrylonitrile , Acrylic rubber-methacrylate, ethylene, ethylene-acrylic acid, nylon, silicone, urethane, melamine, benzoguanamine, phenol, fluorine (tetrachloroethylene), vinylidene chloride, quaternary pyridinium salt, Polymer materials such as synthetic rubber, cellulose, cellulose acetate, chitosan, calcium alginate and the like, and polymer materials whose solvent resistance function has been improved by crosslinking these polymer materials can be mentioned. Material comprising a crosslinked acrylic resin component is preferred from the viewpoint of solvent resistance, but not limited to polymeric materials.

Furthermore, these polymer fine particles may be colored with a dye or a pigment by a known method. For example, a method of producing a monomer using the above method after coloring the monomer before the synthesis of the polymer fine particles. And a method of coloring during the production of the polymer fine particles, a method of coloring after producing the polymer fine particles, and the like.
Furthermore, as another method, it can also be obtained by physically dispersing a dye or pigment in the polymer material obtained by synthesis in advance and then pulverizing to a desired particle size, The colored polymer fine particles are not limited to those obtained by these methods.

At least one kind of these charged particles is used. However, when one kind of charged particles is used, the color of the charged particles is different from the color tone, and the color can be displayed with contrast as the particles move. It will be used in combination with a colored insulating liquid.
For example, when white particles are used as the charged particles, the color of the insulating liquid is used as a type colored with an oil-soluble dye such as oil blue.

On the other hand, when two types of charged particles are used, particles that are oppositely charged with each other and that have different color tones capable of contrast display are used in combination.
For example, when negatively charged white particles are selected as one particle, positively charged black particles can be selected and combined as the other particle. In this case, the color of the insulating liquid is preferably colorless and transparent, but the insulating liquid can be further colored and used. Further, two or more kinds of particles having different charge amounts and colors of charged particles can be used in appropriate combination.

  In the present invention, in addition to the insulating liquid constituting the electrophoretic display liquid and one or more kinds of charged particles, a charge adjusting agent, a dispersing agent, a surfactant, a hygroscopic agent and the like are conventionally used for electrophoretic display. Various types can also be used as appropriate.

The structural material 20 provided between the substrates 10 and 15 of the present invention can at least maintain an appropriate substrate spacing, prevent a short circuit due to contact with the counter substrate, and the like, and can suppress aggregation and uneven distribution of charged particles. If it has, the structure etc. will not be specifically limited.
As the structural material 20 that can be used, for example, a PET film in which holes having a square shape such as a square or a hexagon, a circular shape, or an elliptical shape are formed by laser processing, or a fiber is knitted. A thing like a textile body can be mentioned. Furthermore, it is possible to use a structure in which a cross-shaped structure is formed by a method such as hot embossing using a thermoplastic resin, but the structure having the above effect is not limited thereto. If it is.
Preferably, a structure having a high aperture ratio and capable of forming fine small cells (cells) so that aggregation and uneven distribution of charged particles can be suppressed is desirable. A plain weave formed by forming a square or hexagonal hole such as a square or hexagon on a PET film that is easy to form by laser processing, or by knitting a fiber that can be easily filled with an electrophoretic display liquid From the viewpoint of manufacturability, cost, etc., a plain weave or the like formed by knitting fibers that can be easily filled with the liquid for electrophoretic display is desirable.
FIG.1 (c) shows an example of the structural material which formed the hole of square shape in the PET film by laser processing.

  In the present invention, the structural material 20 formed between the substrates 10 and 15 has at least a portion of the structural material 20 existing in the display portion fixed to the substrate 20 as shown in FIG. It is necessary not to. In the present embodiment, the structure material 20 is not fixed by having the gap 16 between the structure material 20 and the substrate 10. The length t of the gap is preferably the distance between substrates (distance between substrates), the type / size of each structural material, the type of electrophoretic display liquid containing an insulating liquid or one or more types of charged particles, Although it varies depending on the type of filling, etc., it is desirable to adjust to 0 to 5 μm. Here, 0 μm means not a state where the substrate and the structural material are fixed by adhesion or the like, but a state where they are simply in contact with each other.

Since the structural material 20 of the present invention is not fixed to the substrate 10, even when the electrophoretic display medium is deformed to some extent by an external force, the structural body 20 can be moved according to the deformation. Stress can be released and damage to the electrophoretic display device can be suppressed.
In particular, a thin electrophoretic display device having flexibility is characterized by being deformable, but such an electrophoretic display device exerts a tremendous effect.
In addition, since at least a portion existing in the display portion is not fixed to the substrates 10 and / or 15, the display quality and driving characteristics are hardly deteriorated, and a stable substrate interval (gap) corresponding to deformation is maintained. Is also possible.

In the structural material 20 of the present invention, as long as at least a portion of the structural material 20 existing in the display portion is not fixed to the substrate 10, a portion other than the display portion may be fixed to the substrate 15. The portion on the back side that is the opposite side of the display unit may be fixed to the substrate 15. On the other hand, an electrophoretic display device (FIG. 3) in which the structure 20 is disposed only in the display unit and the structural material is not disposed in any region other than the display unit.
For example, for convenience when the structure 20 is sandwiched between the substrates 10 and 15, a portion other than the display can be fixed to the substrate 10 and / or 15 with an adhesive or the like, or electrophoresis Although it is possible to fix the display liquid with a sealing material used to contain the liquid between the substrates 10 and 15, it is not limited thereto.
FIG. 3 and FIG. 4 are explanatory diagrams showing an example of the usage state and other examples of the electrophoretic display device of the present invention in a plane form (display content ABC display). FIG. 3 shows a structure in which a portion other than the display portion of the structural material 20 of the present invention is not fixed to the substrate 10, and FIG. 4 shows a structure in which a portion other than the display portion is fixed to the substrate 10. .

FIG. 5 is an explanatory diagram showing an example of a manufacturing process of an electrophoretic display device according to an embodiment of the present invention, and FIG. 6 is an explanatory diagram showing an example of a manufacturing process of an electrophoretic display device by a conventionally used photolithography method. FIG.
FIG. 5 shows that a sealing material 30 is applied on the outer periphery of the substrate 15 after placing a structural material in which a square hole is previously formed on the PET film by laser processing on the electrode surface of the substrate 15 without bonding. An electrophoretic display liquid is filled in a region surrounded by the sealing material 30, and finally the substrate 10 is covered, and the sealing material 30 is irradiated with UV light and bonded.

  On the other hand, in FIG. 6, a UV curable resin is applied on the electrode surface of the substrate 15, and a portion that is not desired to be cured (portion where the electrophoretic display liquid is filled) is covered with a photomask and irradiated with UV light. Thereafter, the non-cured portion is washed away and a UV curable adhesive is applied to the cured portion, and the sealing material 30 is applied to the outer periphery of the substrate 15, and the electrophoretic display liquid is further applied to the sealing material 30. The process is shown in which a region surrounded by is filled, and finally the substrate 10 is covered, and the sealing material 30 is irradiated with UV light and bonded together.

In the electrophoretic display device A of the present embodiment configured as shown in FIG. 5, the structural material 20 is not fixed to at least the portion of the substrate 10 serving as the display portion, so that the electrophoretic display medium is slightly deformed by an external force. In this case, since the structure 20 can move according to the deformation, the stress can be released, the electrophoretic display device can be prevented from being damaged, and the particles in the display device are aggregated or unevenly distributed. Can be maintained without sacrificing display quality and driving characteristics, and a flexible electrophoretic display device can maintain a stable substrate gap (gap) corresponding to deformation, and at low cost. An electrophoretic display device that can be manufactured is obtained.
On the other hand, in the conventional electrophoretic display device as shown in FIG. 6, the structure 20 is bonded and fixed to the substrates 10 and 15. Stress is applied to the bonding surfaces of the substrates 10 and 15 so that the bonded portion is easily broken, and stable display corresponding to deformation is difficult to be performed.

Next, the present invention will be described in more detail with reference to test examples (Examples and Comparative Examples), but the present invention is not limited to the following Examples.
An electrophoretic display medium was obtained by the following method.

(Production of electrophoretic display device)
The electrophoretic display device according to FIG. 1 was obtained by the following steps.
1) Substrates 10 and 15 used
Front substrate 10: The surface resistance value is on the surface of an ITO-PET film having a thickness of 125 μm.
Substrate formed to be 300Ω / □ Rear substrate 15: A copper thin film is formed on a polyimide film substrate having a thickness of 400 μm,
A substrate on which a 7-segment pattern was formed by etching. Substrate spacing: 50 μm
2) Structural material 20
A structural material having a mesh structure with a 0.4 mm × 0.4 mm square hole spaced by 0.1 mm is formed by laser processing of a 50 μm thick PET film as shown in FIG.
3) Display solution for electrophoresis used Resin particles (particle size: about 0.3 μm) and carbon black colored with lipophilic titanium oxide (particle size: about 0.3 μm) as charged particles in xylene as an insulating liquid 1 μm) and an ink obtained by adding hydroxylaurylamine.

4) Fabrication of electrophoretic display device As shown in FIG. 1A, the structural material of 2) above is placed on the electrode surface of the back substrate, and the UV curable type is formed on the outer periphery of the back substrate. After applying the adhesive, the holes of the structural material are filled with the electrophoretic display liquid obtained in the above 3), and then the front plate is covered, and UV light is applied to attach the display unit. An electrophoretic display device having a size of 10 cm × 10 cm and a seal portion having a width of 7 mm was produced.
On the other hand, as a comparative example, the structural material of 2) above was bonded onto the electrode surface of the back substrate by irradiating UV light using a UV curable adhesive, on the outer periphery of the back substrate and on the front substrate. After applying a UV curable adhesive to the structural material part in contact, fill the hole of the structural material with the electrophoretic display liquid obtained in 3) above, cover the front plate, and then irradiate with UV light. By bonding, an electrophoretic display device having a display portion of 10 cm × 10 cm and a seal portion width of 7 mm was produced.

The electrophoretic display devices of the obtained Examples and Comparative Examples were repeatedly subjected to deformation tests by the following method to evaluate the display performance.
(Repeated evaluation test method)
The seal part of the opposite side of the electrophoretic display device is fixed with a metal fixture so that the electrophoretic display device is not removed using a silicone rubber sheet as a cushioning material, and the curvature is R when viewed from the side. It was repeatedly deformed repeatedly 1000 times (500 times on one side) alternately on the front substrate side and the back substrate side so that = 100.

In the above 1000 times deformation test results, in the comparative example, it is not known whether the cell wall peeled off, the surrounding display deteriorated, the substrate was damaged when it was peeled off, or because the foreign material was peeled off. 60V), it was impossible to reproduce even if it was displayed again.
On the other hand, it turned out that the example which becomes this invention can display favorable even after 1000 times of repeated deformation tests.

FIG. 1 is a drawing showing an example of an embodiment of an electrophoretic display device of the present invention, where (a) is a schematic cross-sectional view of the electrophoretic display device, and (b) is a structural material that is the gist of the present invention between substrates. (A) The partial expanded sectional view of the round mark part which shows the state which is not fixed to (c), (c) is a perspective view of a structural material. (A) And (b) is a partial top view which shows the other examples of each structural material. It is explanatory drawing which shows an example of the use condition of the electrophoretic display device of this invention in a plane aspect. It is explanatory drawing which shows the other example of the use condition of the electrophoretic display device of this invention in a plane aspect. It is explanatory drawing which shows an example of the manufacturing process of the electrophoretic display device of embodiment of this invention. It is explanatory drawing which shows an example of the manufacturing process of the conventional electrophoretic display device.

Explanation of symbols

A Electrophoretic display device 10 Substrate 15 Substrate 20 Structural material 30 Sealing material 40 UV curable resin 50 Photomask

Claims (1)

An electrophoretic display device comprising at least an insulating liquid, one or more kinds of charged particles, and a structural material formed between the substrates arranged opposite to each other. An electrophoretic display device characterized in that the portion is not fixed to a substrate.

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