JP2612471B2 - Electrophoretic display device and method of manufacturing the same - Google Patents

Description

The present invention relates to a display device using electrophoretic particles,
The present invention relates to an electrophoretic display device configured to reliably enclose a dispersion system in each hole of a porous spacer for dividing the dispersion system into discontinuous phases into small sections, and a method of manufacturing the same.

"Prior art" This type of electrophoretic display device using electrophoretic particles, as shown in FIG. 4, uses a suitable transparent conductive member such as indium oxide or tin on the opposing surface to perform required display. Two transparent glass plates 1 and 3 on which electrode patterns 2 and 4 are separately formed are provided, and a spacer 7 is also used as a spacer so that a dispersion system 7 in which electrophoretic particles 6 are dispersed in a liquid dispersion medium is sealed between the opposing gaps. It has a structure in which the sealing member 5 is provided on the outer peripheral portion. In such a display device, an electrophoresis is performed by applying a display driving voltage to the electrode patterns 2 and 4 and applying an electric field to the dispersion system 7 so that the electrophoretic particles 6 can be adsorbed and separated from the electrode patterns 2 and 4. By changing the distribution state of the particles 6, the dispersion system 7
The optical characteristics are changed to perform a desired display operation. 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 may have a non-uniform electric field strength due to uneven spacing between the electrode patterns 2 and 4 and the like. 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. For this reason, 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 the above inconvenience, as shown in FIG. 5, the dispersion system 7 is reduced by encapsulating the dispersion system in each of the through holes 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 known.

"Problems to be Solved by the Invention" Such electrophoretic display devices have been studied intensively because of their characteristics such as a wide viewing angle, a long-term memory property and low power consumption. Many studies are concerned with the dispersibility of migrating particles in a liquid dispersion medium and the stabilization of the dispersion system. However, in the case of a dispersion-division-type electrophoretic display device in which a dispersion system is divided into discontinuous phases by using a porous spacer, it is not possible to uniformly inject the dispersion system into each hole of the porous spacer. It is very difficult, and there is a possibility that an incomplete portion of the dispersion injection may occur to cause a display defect.

[Means for Solving the Problems] The present invention makes it possible to easily and surely inject a dispersion system into each hole of a porous spacer in a dispersed system type electrophoretic display device using a porous spacer. And a method for manufacturing the same.

In order to achieve this object, in the electrophoretic display device according to the present invention, at least one of the electrophoretic particles is dispersed by interposing a porous spacer between a pair of opposedly arranged electrode plates configured to be transparent. An electrophoretic display device of the type in which the dispersed system is divided into discrete phases and sealed, wherein a sealable opening formed in one of the electrode plates for injecting and overflowing the dispersed system is provided. In the peripheral region of each of the opposed ends of the electrode plate, a stretchable end sealing member for finally sealing the dispersion with an adhesive is provided.

In such an electrophoretic display device, a pair of electrode plates, at least one of which is made transparent, are arranged to face each other with a porous spacer interposed therebetween, and extendable and contractible ends are provided around respective opposite end portions of the two electrode plates. The sealing member is joined and the end sealing member is expanded and contracted to expand and contract the electrophoretic particles. By enclosing the above-mentioned dispersion system in each hole of the spacer, it is possible to easily manufacture a dispersion-division-type electrophoretic display device using a porous spacer.

[Embodiment] Hereinafter, the present invention will be described in more detail with reference to the illustrated embodiment. In FIG. 1, reference numerals 1 and 2 denote a transparent glass plate and an electrode pattern constituting one electrode plate. And 4 show a transparent glass plate and an electrode pattern for constituting another electrode plate, and both electrode patterns 2 and 4 can be formed of a transparent conductive material such as indium tin oxide. The pair of electrode plates are arranged to face each other such that the electrode patterns 2 and 4 face each other, and a porous spacer 8 for dividing the dispersion system is interposed therebetween. The porous spacer 8 can be formed in advance on one of the electrode plates in a mesh shape or the like at a required height by printing means using a material such as silicon rubber.

Reference numeral 9 denotes a stretchable end sealing member joined to the periphery of each of the opposite end portions of the two electrode plates, and the end sealing member 9 is
As shown in the drawing, in the extended state, the interval between the two electrode plates is sufficiently formed to be equal to or greater than the height of the porous spacer 8, and oxidation is performed from an appropriate number of openings 10 formed near the both ends of one of the electrode plates. By injecting a dispersion of a required amount or more containing electrophoretic particles such as titanium in a continuous phase between the two electrode plates, the dispersion is reliably and quickly performed without fear of leaving holes in each hole of the porous spacer 8. As shown in the figure, the upper and lower peripheral surfaces of the end sealing member 9 are coated with an adhesive or the like in the peripheral region of each opposite end of both electrode plates as shown in the figure. Closely joined.

As shown in FIGS. 3 (1), (2) and (3), the end sealing member 9 configured to be stretchable is a film material made of a suitable rubber member or other synthetic resin. Or the cross section in the stretched state using a sheet material is substantially Z-shaped,
It can be formed in an arbitrary shape such as a horizontal U-shape or a bellows shape that can be freely expanded and contracted.

By providing such a stretchable end sealing member 9, after the member 9 is extended, a required amount of the dispersion is injected in a continuous phase in the above-described manner through the opening 10 between the two electrode plates in a continuous phase. When the electrode plate is pressed so that one of the electrode plates is in close contact with the porous spacer 8, the end sealing member 9 contracts in response to the pressing.
Thus, as shown in FIG. 2, the dispersion system 7 in which the electrophoretic particles 6 are dispersed can be reliably and easily encapsulated without leaving any voids in each hole of the porous spacer 8 as shown in FIG. It becomes possible. After the injection / overflow treatment process of the dispersion system 7, each opening 10 is sealed with a sealing plate 12, and an adhesive material 11 is provided on the outer periphery of the contracted end sealing member 9 to provide a gap between the two electrode plates. By performing the fixing process, a discontinuous split-type electrophoretic display device of the dispersion system 7 using the porous spacers 8 can be easily configured.

In the above display device, the porous spacer 8 for dividing the dispersion system 7 into small sections into the discontinuous phase is made of a swelling material which can be appropriately formed of a rubber member such as silicon rubber, fluorine rubber or the like. Various polymers having a shape memory function, such as isoprene rubber, nobornene-based polymer, and ethylene-propylene-based synthetic rubber, can also be used.

Such a porous spacer 8 is formed directly on one of the electrode patterns 2 or 4 so that a large number of holes can be provided by screen printing or spraying using a shape memory polymer, After forming a large number of required through-holes by means such as punching or drilling using silicon rubber or the like molded into a suitable shape, the thickness is appropriately formed by means such as hot pressing so that the thickness is equal to or less than the gap between the two electrode plates. You can also. The shape of each through-hole of the porous spacer 8 can be arbitrarily set, such as a square, a slit, or the like, a circle, a rectangle, or a polygon, and the arrangement thereof is also provided regularly or irregularly. Can be. The thickness of the porous spacer 8 can be appropriately selected by taking into consideration the restoration rate of a member to be used such as silicon rubber or shape memory polymer, the composition of the dispersion medium, the gap between the two electrode plates, and the like. Generally, it can be set to about 20 μm to 1 mm.

The electrophoretic particles 6 used for the dispersion system 7 include various kinds of organic and inorganic pigments, dyes,
Fine powder such as metal powder, glass or resin can be used as appropriate. Further, as the dispersion medium of the dispersion system, besides water, alcohols, hydrocarbons, halogenated hydrocarbons and the like, various kinds of natural or synthetic oils can be used. In addition, if necessary, in addition to electrolytes, surfactants, metal soaps, and other charge control agents consisting of particles such as resins, rubbers, oils, varnishes, and compounds, the dispersant, lubricant, An agent 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, and stabilizing the dispersion uniformly, the adsorptivity of the electrophoretic particles to the electrode patterns 2 and 4, the viscosity of the dispersion medium, etc. Can be adjusted as appropriate.

In one embodiment, a pair of electrode plates each having a required transparent electrode pattern formed using indium tin oxide on one surface of two transparent glass plates is prepared, and the electrode of one of the electrode plates is prepared. On the pattern forming side, a porous spacer was formed by printing in a mesh shape so as to have a thickness of 40 μm ± 2 using silicon rubber, and openings were formed at both ends of another electrode plate.

Next, the upper and lower ends of an end sealing member formed into a shape shown in FIG. 3 (2) using a polyimide film around each of the opposing end portions of the two electrode plates are bonded to each other with an adhesive. A display cell as shown in the figure was produced.

On the other hand, 1.5 g of dark blue dye was dissolved in a mixed solvent of 50 cc of toluene and 30 cc of tetrafluorodibromoethane, and 5 g of titanium oxide as electrophoretic particles was dispersed in the solvent together with a dispersion medium to prepare a dispersion system. After injecting this dispersion system between the two electrode plates from the opening using a syringe, an epoxy-based adhesive is applied to the outer periphery of the end sealing member so that the electrode plate having the openings adheres to the porous spacer. The gap between the two electrode plates is reduced while the end sealing member is contracted, so that excess dispersion is overflowed from the opening, then the opening is sealed with the sealing plate, and the outer periphery of the end sealing member is adhered. The agent was cured to fix the gap between the two electrode plates to obtain a dispersed-system electrophoretic display device as shown in FIG.

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

[Effects of the Invention] As described above, the electrophoretic display device according to the present invention relates to an electrophoretic display device in which a dispersion system is divided into discontinuous phases by using porous spacers. Since there is provided a flexible end sealing member joined to the peripheral area of each opposing end of the electrode plate, first extend this end sealing member to sufficiently open the two electrode plates more than a required interval. In this state, the dispersion system can be rapidly and continuously injected in a continuous phase between the two electrode plates through an opening formed in one of the electrode plates in a required amount, so that the dispersion system injection processing can be performed efficiently and easily in a short time.

Then, holes are left in each hole of the porous spacer by a simple operation of shrinking the end sealing member so that the electrode plate is in close contact with the porous spacer and overflowing excess dispersion system. And completely seal the dispersion.

Therefore, it is possible to provide a highly reliable and high-performance dispersed-partition-type electrophoretic display device with good contrast, high reliability, and high reliability without the risk of display defects by reliably enclosing the dispersion in each hole of the porous spacer.

[Brief description of the drawings]

FIG. 1 shows an electrophoretic display device provided with a telescopic end sealing member according to an embodiment of the present invention, in which the end sealing member is extended and before a dispersion system is injected. FIG. 2 shows a state in which the sealing of the dispersion system is completed for each hole of the porous spacer by shrinking the end sealing member and overflowing the excess dispersion system from the opening. FIG. 3 (1) to (3) are conceptual cross-sectional configuration diagrams showing a configuration example of a stretchable end sealing member that can be employed in the present invention, and FIG. FIG. 5 is a conceptual cross-sectional configuration view of a conventional dispersed continuous phase electrophoretic display device that does not use a porous spacer, and FIG. 5 shows a conventional dispersed system split type electrophoretic display device having a porous spacer. FIG. 4 is a conceptual cross-sectional configuration diagram illustrating a conceptual main part, together with a problem associated with the dispersion injection. . 1: Transparent glass plate 2: Electrode pattern 3: Transparent glass plate 4: Electrode pattern 5: End spacer 6: Electrophoretic particles 7: Display dispersion system 8: Porous spacer 9: Elastic sealing member 10: Injection・ Overflow opening 11: Fixing adhesive 12: Opening sealing plate

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tatsuhiko Oshiro 757 Tenhoki, Kusazaki-cho, Inashiki-gun, Ibaraki Japan Inside the Metrotron Co., Ltd. Minami-Ibaraki Plant Kutron Co., Ltd.

Claims (4)

(57) [Claims] 1. A method in which 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 divided into a discontinuous phase and sealed. In the electrophoretic display device, a sealable opening formed in one of the electrode plates for injecting and overflowing the dispersion system is provided. An electrophoretic display device comprising an elastic end sealing member for finally sealing the system together with an adhesive. 2. A pair of electrode plates, at least one of which is made of a transparent material, is disposed to face each other with a porous spacer interposed therebetween, and the end seals are provided at the periphery of each of the opposite ends of the two electrode plates. For the porous spacer by the continuous phase injection and the overflow action of the dispersion in which the electrophoretic particles are dispersed by expanding and contracting the end sealing member. A method for producing an electrophoretic display device, wherein the dispersion system is sealed in a hole. 3. An electrode plate formed with an opening for injecting and overflowing a dispersion system in which electrophoretic particles are dispersed and another electrode plate made of transparent material are opposed to each other with a porous spacer interposed therebetween. Then, a stretchable end sealing member was joined to the peripheral region of each of the opposite end portions of the two electrode plates, and the end sealing member was extended to separate the two electrode plates by a required distance or more. A required amount of the dispersion system is injected between the two electrode plates in a continuous phase through the opening in a state, and then at least the one electrode plate is pressed against the porous spacer to shrink the end sealing member. After filling the dispersion system in each hole of the porous spacer by overflowing an excess dispersion system from the opening while allowing the dispersion, the opening is sealed and an adhesive is provided on the outer periphery of the end sealing member. Characterized by fixing between the two electrode plates The process of the gas-electrophoretic display device. 4. The stretchable end sealing member having a substantially Z-shaped, U-shaped or bellows-shaped cross section in an extended state. 3. The method for producing an electrophoretic display device according to item 1.