JP2733678B2 - Electrophoretic display device and method of manufacturing the same - Google Patents

Description

The present invention relates to a display device using electrophoretic particles,
By using a flexible substrate made of a resin film or the like for one of the electrode plates, the dispersion system is securely sealed in each hole of the elastic porous spacer to divide the dispersion system into small continuous phases. TECHNICAL FIELD The present invention relates to an electrophoretic display device configured to be capable of being manufactured and a method for manufacturing the same.

2. Description of the Related Art As shown in FIG. 3, this type of electrophoretic display device using electrophoretic particles has a required display electrode pattern using an appropriate transparent conductive member such as indium tin oxide on the opposing surfaces. Two transparent glass plates 1 and 3 formed separately from each other
And a sealing member 5 also serving as a spacer function is provided at an outer peripheral portion so as to enclose a dispersion system 7 in which electrophoretic particles 6 are dispersed in a liquid dispersion medium between the opposing gaps. The electrophoretic display device having such a structure includes electrode patterns 2 and 4
A voltage is applied to the display system to apply a display driving voltage, and an electric field is applied to the dispersion system 7 to change the distribution state of the electrophoresis particles 6 so that the electrophoretic particles 6 can be adsorbed and separated from the electrode patterns 2 and 4. The optical characteristics are changed to perform desired display operations of characters, symbols, figures, and the like.

In the case where the dispersion system 7 is formed in a continuous phase by the sealing member 5 provided at the end as described above, the dispersion system 7 is caused by non-uniform electric field strength due to unevenness in the gap between the two electrode patterns 2 and 4. As a result, the electrophoretic particles 6 move in a direction parallel to the electrode pattern surface, causing a bias in the concentration distribution of the electrophoretic particles. As a result, when the electrophoretic display device is used repeatedly for a long time, the concentration of the electrophoretic particles locally increases. There is a problem that the display becomes uneven or display unevenness occurs.

Therefore, as a means for solving such inconvenience, as shown in FIG. 4, a dispersion system is sealed in each through-hole by using a porous spacer 8 having a large number of through-holes. A structure in which a section is divided into discontinuous phases is also disclosed in JP-A-49-32038.
And JP-A-59-34518 and JP-A-59-171930.

"Problems to be Solved by the Invention" However, in the above prior art relating to a dispersion-division-type electrophoretic display device in which a dispersion is divided into discontinuous phases into small sections using a porous spacer, When a substrate film is used, a gap is easily formed between the porous spacer and the electrode plate due to deformation of the film or the like, which may cause uneven distribution of electrophoretic particles. In addition, when both electrode plates are made of a glass plate base material, a portion where a gap is left between the porous spacer and the electrode plate is determined by the relationship between the flatness of the glass plate and the distribution of the thickness of the porous spacer. However, it is not easy to prevent the electrophoretic particles from being unevenly distributed even in such a structure.

Furthermore, in the case of a cell structure in which both electrode plates and the interposed porous spacer are bonded in advance, it is extremely difficult to uniformly inject the dispersion into each hole of the porous spacer. In addition to various manufacturing difficulties associated with the above, there is a possibility that incomplete portions of the dispersion injection may occur and display defects may occur, and a problem to be solved in obtaining a highly reliable display device is: Many.

[Means for Solving the Problems] The present invention relates to a dispersion-separated type electrophoretic display device using a porous spacer, wherein the porous spacer is formed of an elastic member and one of the electrode plates is flexible. The present invention provides an electrophoretic display device capable of easily and reliably injecting a dispersion system into each hole of an elastic porous spacer, and a method of manufacturing the same.

Therefore, in the electrophoretic display device of the present invention, a dispersion system in which electrophoretic particles are dispersed through a porous spacer between a pair of opposedly arranged electrode plates at least one of which is transparent is discontinuous. In an electrophoretic display device having a structure in which the porous spacer is divided into phases and sealed, the porous spacer is formed of an elastic member, and the one electrode plate is made of a flexible material which can be in close contact with the elastic porous spacer. And the other electrode plate is formed of a transparent rigid body, and the flexible electrode plate is held so that the dispersion in the elastic porous spacer is maintained at a negative pressure by the elasticity of the spacer. The elastic porous spacer is configured to partially bend toward each through hole side.

In order to manufacture such an electrophoretic display device, first, a flexible electrode plate and a transparent rigid electrode plate each having a required electrode pattern formed on one surface of each of a film member and a transparent glass plate are prepared. After excessively supplying a dispersion system in which electrophoretic particles are dispersed in an elastic porous spacer disposed on the electrode pattern side of the electrode plate, the flexible electrode plate is replaced with the electrode pattern of the rigid electrode plate. Is disposed on the elastic porous spacer so as to face the flexible electrode plate, and then a pressing force is applied to the upper surface of the flexible electrode plate so that the flexible electrode is compressed in the elastic porous spacer. The plate is brought into close contact with the elastic porous spacer, and an extra dispersion system is extruded, the dispersion system is sealed in each hole of the porous spacer, and a negative pressure is applied to the encapsulated dispersion system by the restoring force of the elastic porous spacer itself. The method of maintaining the state is adopted. It is.

When manufacturing such an electrophoretic display device, an elastic porous spacer that can be formed of synthetic rubber such as silicon rubber, urethane rubber, fluorine rubber, or acrylic rubber, natural rubber, or the like is provided on the transparent rigid electrode plate in advance. Forming integrally is also a suitable technique.

"Example" Hereinafter, the present invention will be described in more detail with reference to the illustrated example. In FIG. 1, reference numeral 10 denotes a transparent glass plate as a base material for forming a transparent rigid electrode plate, and a required electrode pattern is formed on the upper surface thereof using a transparent conductive material such as indium tin oxide. 11 is appropriately formed. On the upper surface of the rigid electrode plate, an elastic porous spacer 12 for dividing and enclosing the dispersion system into small sections is provided. This porous spacer 12 is made of silicon rubber, urethane rubber, fluorine rubber,
A sheet made of a material such as synthetic rubber or natural rubber such as acrylic rubber and a number of required holes formed by punching, laser or the like are integrally formed on the side of the rigid electrode plate on which the electrode pattern 11 is formed. It is also possible to form a desired through-hole by a chemical dissolving means such as etching, or by forming a photosensitive resin on the electrode pattern 11 by coating.

As shown in FIG. 2, the elastic porous spacer 12 has a large number of through holes 12B which can be formed in the above-described manner for separately enclosing the dispersion system.
In addition to the above, it is preferable to form an adhesive fixing portion 12A indicated by oblique lines without a through hole 12B in the peripheral area of the end of the spacer 12 in relation to a flexible electrode plate described later. On the upper surface of such an elastic porous spacer 12, a flexible electrode plate composed of a film base 13 having another electrode pattern 14 formed on the surface facing the electrode pattern 11 is provided. Reference numeral 15 denotes a pressurizing member, which presses the dispersion system 7 excessively supplied to each hole 12B of the elastic porous spacer 12 from the upper surface of the flexible electrode plate to compress the spacer 12 and generate an excess. By extruding the dispersion system 7, each pore 12 of the elastic porous spacer 12 is extruded.
This is for allowing B to completely encapsulate the dispersion system 7 having no pores. At least one of a gas, a liquid and a solid can be used as appropriate for the pressure member 15, but in the illustrated case, an example using a steel roll is shown. Reference numeral 16 denotes an adhesive for fixing and joining the constituent members at their ends.

In order to fabricate the dispersion type electrophoretic display device having the above-mentioned structure, an elastic material as shown in FIG. 2 is formed on the electrode pattern 11 of the rigid electrode plate composed of the transparent glass plate 10 and the transparent electrode pattern 11. After the porous spacer 12 is formed, the dispersion system 7 prepared in advance by dispersing electrophoretic particles such as titanium oxide in an appropriate liquid dispersion medium so as to be optimal for the display purpose is applied to the elastic porous spacer 12 in an amount exceeding the required amount. Oversupply the spacer
12 is completely covered with this dispersion 7. Next, the flexible electrode plate is used as a pressing member on the upper surface side of the flexible electrode plate in a state where the flexible electrode plate is overlaid on the elastic porous spacer 12 so that the electrode pattern 14 faces the electrode pattern 11 of the rigid electrode plate. Steel roll 15 is placed. When the elastic force is sequentially applied from one end of the flexible electrode plate by the roll 15, the flexible electrode plate is sufficiently pressed against the elastic porous spacer 12 to come into close contact therewith. As a result, the excess dispersion system excessively supplied to the elastic porous spacer 12 is pushed out from each hole 12B of the spacer 12, and the elastic porous spacer 12 is pressed by the elastic force of the steel roll 15. In a compressed state, the dispersion system 7 is sealed in each of the holes 12B. Then, when the outer peripheral end portions of the rigid electrode plate, the elastic porous spacer 12, and the flexible electrode plate are bonded and fixed to each other using the adhesive 16,
Due to the restoring force of the elastic porous spacer 12, the divided and encapsulated dispersion system 7 is maintained in a negative pressure state in each of the holes 12B of the spacer 12, thereby completely filling the divided dispersion system without voids. It can be easily and quickly applied.

Here, the elastic porous spacer 12 is formed by forming a large number of required through holes by means of punching, drilling or laser processing using silicon rubber or the like formed in a sheet shape, and then by means of hot pressing or the like. It can be appropriately molded so that its thickness is equal to or less than the gap between the two electrode plates. In addition, the shape of each through-hole 12B of the spacer 12 can be arbitrarily determined, such as a circular shape, a rectangular shape, or a polygonal shape, in addition to a square shape or a slit shape, and the arrangement thereof is also regular or irregular. obtain. The thickness of the elastic porous spacer 12 can be appropriately selected in consideration of the restoration rate of a member to be used such as silicon rubber or urethane rubber, the composition of the dispersion medium, the gap between the two electrode plates, and the like. To
It can be set to about 20 μm to 1 mm.

As the electrophoretic particles used in the dispersion system 7, various kinds of fine powders of organic or inorganic pigments, dyes, ceramics, resins, and the like can be used as appropriate, in addition to various known colloidal particles. Further, as the dispersion medium of the dispersion system 7, various kinds of natural or synthetic oils and the like can be arbitrarily used in addition to hydrocarbons, halogenated hydrocarbons, aromatic hydrocarbons and the like. And if necessary, an electrolyte, a surfactant, a metal soap or a resin,
In addition to a charge control agent composed of particles such as rubber, oil, varnish, and compound, a dispersant, a lubricant, a stabilizer, and the like can be appropriately added. Furthermore, in addition to unifying the charge of the electrophoretic particles to be positive or negative, increasing the zeta potential, it is also possible to appropriately adjust the adsorptivity of the electrophoretic particles to the electrode patterns 11 and 14 and the viscosity of the dispersion medium.

In one embodiment, the film substrate 13 and the transparent glass plate
A flexible electrode plate and a rigid electrode plate each having a required transparent electrode pattern 11 and 14 formed separately using indium tin oxide on one side of each of 10 are prepared, and the electrode pattern of the rigid electrode plate is prepared. An elastic porous spacer 12 having a structure as shown in FIG. 2 was formed by disposing a silicone rubber sheet having a large number of through holes on the side where 11 was formed.

On the other hand, 100 cc of hexylbenzene was prepared as a dispersion medium for the dispersion system 7, and 1 g of a dark blue dye composed of oil blue BA and 0.5 g of a surfactant composed of Sylvan S83 were dissolved therein. As a result, 5 g of titanium oxide was dispersed to prepare a dispersion system 7. The dispersion 7 was overpoured over the elastic porous spacer 12 so that no air remained, and the spacer was safely covered. Next, the flexible electrode plate is
After being arranged on the elastic porous spacer 12 as shown in the figure,
By using a steel roll 15 to apply pressure and pressure sequentially from one end to the surface side of the flexible electrode plate, excess dispersion is performed while the flexible electrode plate is in close contact with the elastic porous spacer 12. While the system 7 was pushed out, the dispersion system was completely sealed in each through hole 12B in the compressed state of the spacer 12, and then the peripheral region of the end portion of the flexible electrode plate in close contact with the spacer 12 was clamped. Finally, in this clamp portion, the ends of the components including the two electrode plates and the elastic porous spacer 12 are bonded and fixed with an epoxy-based adhesive 16 so that the dispersion system 7 as shown in FIG. An electrophoretic display device which was divided into small sections under pressure and sealed was obtained.

When a switching test was performed by repeatedly applying a voltage of 70 V DC between the electrode plates of the electrophoretic display device, 10
Even after a lapse of one million switching operations, no bias of the electrophoretic particles was observed, and a display operation with good contrast was obtained.

[Effect of the Invention] The electrophoretic display device according to the present invention is an electrophoretic display device having a structure in which a dispersion system is divided into small sections into discontinuous phases using a porous spacer and sealed therein. Since one of the electrode plates is made to be flexible, and one of the electrode plates is made to be flexible, in the case of manufacturing such a display device, the flexible electrode is placed on the elastic porous spacer to which the dispersion is excessively supplied. By applying a pressing force sequentially to the flexible electrode plate side in a state where the plate is mounted, an extra dispersion system is extruded while the flexible electrode plate is in close contact with the elastic porous spacer, and the spacer is pressed. In the compressed state, the dispersion system can be completely and easily encapsulated without leaving a hole in each through hole of the elastic porous spacer.

Then, the dispersion system sealed in each through hole can be sealed and held in a negative pressure state by the restoring force of the elastic porous spacer.

Such an electrophoretic display device has a simple structure, and there is a remarkable method for completely enclosing a dispersion system in each through-hole of an elastic porous spacer.

Therefore, it is possible to provide an excellent dispersion-division-type electrophoretic display device having no display defects, high contrast, and high display reliability.

[Brief description of the drawings]

FIG. 1 is a diagram showing a dispersion type electrophoretic display device having an elastic porous spacer and a flexible electrode plate provided on a transparent rigid electrode plate constructed according to an embodiment of the present invention.
As a method of enclosing the dispersion system in each hole of the elastic porous spacer, an excessive dispersion system is supplied to the elastic porous spacer, and after the flexible electrode plate is arranged, a pressing force is applied to the flexible electrode plate side. FIG. 2 is a conceptual view of an elastic porous spacer formed along with an adhesive fixing portion on an outer peripheral portion on the electrode pattern forming side of a transparent rigid electrode plate according to the method of the present invention. FIG. 3 is a conceptual cross-sectional view of a dispersed continuous phase type electrophoretic display device having a conventional structure without using a porous spacer, and FIG. 4 is a conventional structure having a porous spacer. FIG. 2 is a conceptual cross-sectional configuration diagram showing the dispersion-type divided electrophoretic display device together with problems associated with the injection of the dispersion system. 1, 3: transparent glass plate 2, 4: electrode pattern 5: end spacer 6: electrophoretic particles 7: display dispersion system 8: porous spacer 10: transparent glass plate 11: electrode pattern 12: elastic porous spacer 12A: Adhesive fixing part 12B: Many through holes 13: Film substrate 14: Electrode pattern 15: Steel roller 16: Fixing adhesive

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Mori 757 Tenhoki, Kusazaki-cho, Inashiki-gun, Ibaraki Japan Nippon Mektron, Inc. KUTRON Co., Ltd. Minami-Ibaraki Factory

Claims (6)

(57) [Claims] 1. A dispersion system containing electrophoretic particles is sealed between a pair of transparent electrode plates, at least one of which is transparent, and electrophoresis in the dispersion system is controlled by a display control voltage applied between the electrode plates. In an electrophoretic display device in which the required display operation is performed by changing the optical reflection characteristic by changing the distribution state of the particles, in the electrophoretic display device, the inter-electrode plate is used as means for dividing the dispersion system discontinuously. An electrophoretic display device comprising: an elastic porous spacer interposed therebetween, wherein one of the opposed electrode plates is formed of a flexible sheet, and the other electrode plate is formed of a rigid body. 2. The electrophoretic display device according to claim 1, wherein the base material of the flexible sheet electrode plate is formed of a film member, and the base material of the rigid electrode plate is formed of a transparent glass plate. 3. The electrophoretic display device according to claim 1, wherein said elastic porous spacer has an adhesive fixing portion with said two electrode plates in a peripheral region of an end portion thereof. 4. A flexible electrode plate having a required electrode pattern formed on one surface of each of a film member and a transparent glass plate and a transparent rigid electrode plate are prepared, and are disposed on the electrode pattern side of the rigid electrode plate. After excessively supplying a dispersion system in which the electrophoretic particles are dispersed to the mounted elastic porous spacer, the flexible electrode plate is elastically moved so that its electrode pattern faces the electrode pattern of the rigid electrode plate. Disposed on the porous spacer, and then a pressurizing member is disposed on the upper surface of the flexible electrode plate, and the flexible electrode plate is brought into close contact with the elastic porous spacer, thereby forming an extra dispersion system. Extruding and compressing the elastic porous spacer to encapsulate the dispersion in each hole thereof, and maintaining the encapsulated dispersion in a negative pressure state by the restoring force of the elastic porous spacer. Manufacturing method of electrophoretic display device. 5. The method for manufacturing an electrophoretic display device according to claim 4, wherein at least one of a gas, a liquid, and a solid is used for the pressure member or the pressure applying means. 6. A method for manufacturing an electrophoretic display device according to claim 4, wherein an adhesive fixing portion for said flexible electrode plate is formed in a peripheral region of an end portion of said elastic porous spacer. .