JP2007127763A - Electrophoretic display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophoretic display device in which no local stress is added to the EPD display device in sealing a laminate with a protective sheet and the occurrence of air bubbles by sealing is reduced, and which has excellent display quality and electric characteristics. <P>SOLUTION: The electrophoretic display device includes at least: the laminate composed of a transparent substrate with a transparent electrode layer mounted thereon, a rear substrate with a semiconductor circuit layer mounted thereon, and an electrophoretic display layer disposed between the transparent electrode layer and the semiconductor circuit layer; and the protective sheet to cover and seal the laminate, wherein the film thickness of the transparent substrate is reduced on at least a portion of the outer circumferential section of its surface opposite to the surface on which the transparent electrode layer is mounted. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophoretic display device using electrophoresis in which charged particles in a medium move by applying a voltage for image formation, and more particularly to an electrophoretic display device provided with a protective sheet.

An electrophoretic display device (so-called EPD display device) is a display device using electrophoresis in which particles dispersed in a solvent move by application of a voltage, and includes a microcapsule electrophoresis method, a horizontal movement electrophoresis method, Vertical electrophoresis systems have been developed. EPD display devices are easier to process and handle than LCDs, and are expected to be used for portable devices and information devices.
For example, in order to protect the display layer against impact, a substrate, a microcapsule display layer disposed on the substrate, a transparent electrode layer deposited on the microcapsule display layer, on the microcapsule display layer side There has been proposed a microcapsule type electrophoretic display panel including a transparent resin film having a transparent resin protective film deposited on the transparent resin film (Patent Document 1).
JP 2003-295235 A

However, it is necessary not only to protect the display layer against impact resistance but also to prevent water and the like from being mixed.
For this reason, the countermeasure which coat | covers and seals the laminated body containing a display layer with a protective sheet can be considered. However, when sealing with a protective sheet, local stress is applied to the EPD display part by heating and pressurization, and the EPD particles may be destroyed. In particular, the application of local stress was significant at the outer periphery of the EPD display.
In addition, there is a problem that large bubbles remain in the EPD display device due to the sealing with the protective sheet, and the electrical characteristics are deteriorated.

  Therefore, the present invention provides an electrophoretic display device that does not apply local stress to the EPD display device during sealing with a protective sheet, reduces the amount of bubbles generated by sealing, and has excellent display quality and electrical characteristics. The purpose is to provide.

  As a result of intensive studies, the present inventor has conducted a transparent substrate provided with a transparent electrode layer, a back substrate provided with a back electrode layer, and electrophoresis disposed between the transparent electrode layer and the back electrode layer. An electrophoretic display device comprising at least a laminate comprising a layer and a protective sheet covering and sealing the laminate, wherein the transparent substrate is a surface on which the transparent electrode layer is provided. It has been found that an electrophoretic display device having excellent display quality and electrical characteristics can be obtained by adopting an electrophoretic display device in which the film thickness is reduced at least at a part of the outer peripheral portion of the opposite surface. The present invention has been completed.

  That is, the present invention includes (1) a transparent substrate provided with a transparent electrode layer, a back substrate provided with a back electrode layer, and an electrophoretic layer disposed between the transparent electrode layer and the back electrode layer An electrophoretic display device comprising: a laminate comprising: a laminate comprising: a protective sheet covering and sealing the laminate; wherein the transparent substrate is opposite to the surface on which the transparent electrode layer is provided. An electrophoretic display device in which the film thickness is reduced in at least a part of the outer peripheral portion of the side surface; (2) The outer periphery of the surface opposite to the surface on which the transparent electrode layer is provided on the transparent substrate The electrophoretic display device according to (1), wherein at least a part of the part is chamfered; (3) the chamfered surface is inclined by 5 ° or more and 45 ° or less with respect to a surface direction of the transparent substrate. The electrophoretic display device according to the above (2), which is a plane forming The electrophoretic display device according to (2), wherein a chamfered surface is a curved surface; (5) the protective sheet is in contact with part or all of the chamfered surface (2) to (4) (6) The transparent substrate according to (1), wherein the transparent substrate has a thickness of at least a part of an outer peripheral portion that is 0.1 mm or more smaller than a thickness of a portion other than the outer peripheral portion. (7) The electrophoretic display device according to any one of (1) to (6), wherein the outer peripheral portion is an outer peripheral portion that does not overlap a display area of the electrophoretic display layer; 8) An electronic apparatus comprising the electrophoretic display device according to any one of (1) to (7).

  According to the present invention, there is provided an electrophoretic display device that does not apply local stress to the EPD display device at the time of sealing with a protective sheet, reduces the generation of bubbles due to sealing, and has excellent display quality and electrical characteristics. Can be provided.

Next, an embodiment of the present invention will be described. The following embodiment is an example for explaining the present invention, and is not intended to limit the present invention only to this embodiment. The present invention can be implemented in various forms without departing from the gist thereof.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Example 1
FIG. 1 is a partial sectional view of an electrophoretic display device according to an embodiment of the present invention. As shown in FIG. 1, the electrophoretic display device 1 includes a flexible semiconductor circuit substrate 10, a flexible transparent electrode substrate 30, an electrophoretic display layer 20, and protection for covering and sealing these. And the sheet 2.

The semiconductor circuit substrate 10 includes a flexible back substrate 11 as an insulating base substrate for forming a circuit and a thin semiconductor circuit layer 13. The back substrate 11 is, for example, a polycarbonate substrate having a film thickness of 200 μm. A semiconductor circuit layer 13 is laminated on the back substrate 11 via a UV (ultraviolet) curable adhesive.
For example, Japanese Patent Application Laid-Open No. 10-125931, Japanese Patent Application Laid-Open No. 11-26733, Japanese Patent Application Laid-Open No. 2004-327836, etc. have introduced a mode of forming a thin film semiconductor circuit on such a semiconductor circuit substrate. A thin film circuit transfer method can be used in which a thin film semiconductor circuit is formed on a heat-resistant substrate (glass substrate) and the thin film semiconductor circuit is transferred entirely or partially onto a resin substrate.

In the semiconductor circuit layer 13, a plurality of wiring groups, pixel electrode (drive electrode) groups, pixel drive circuits, and the like arranged in the row direction and the column direction are formed (not shown). A TFT (thin film transistor) is used for the drive circuit. The semiconductor circuit substrate 10 is also formed with a row decoder, a column decoder, etc. (not shown) for selecting drive pixels. The pixel electrode groups arranged in a matrix form a display area 5 for displaying an image (two-dimensional information).
The film thickness of the semiconductor circuit substrate 10 is preferably 25 μm or more from the viewpoint of physical strength of the substrate when forming a thin film circuit, for example, and is 200 μm or less from the viewpoint of ensuring the flexibility of the substrate. It is desirable.

The transparent electrode substrate 30 is composed of a transparent substrate 31 having a transparent electrode layer 32 formed on the lower surface. The transparent substrate 31 is a transparent insulating synthetic resin, for example, a polyethylene terephthalate (PET) film, and the film thickness of the transparent electrode substrate 30 is, for example, 100 μm. The transparent electrode layer 32 is, for example, an indium oxide film (ITO film) doped with tin.
In this embodiment, the transparent substrate 31 has a structure in which the film thickness is reduced at least at a part of the outer peripheral portion of the surface opposite to the surface on which the transparent electrode layer 32 is provided. That is, the outer peripheral part on the upper surface side of the transparent substrate 31 has a shape chamfered by a plane having an angle α. The angle α is preferably 5 ° or more and 45 ° or less.
The chamfering substantially overlaps with the display area 5 so that when the display area 5 of the electrophoretic display layer 20 is projected onto the transparent substrate 31, the chamfering or the like is visible on the display unit or the display is not refracted. It is preferable that it is provided in the outer peripheral part which does not become.

  An electrophoretic display layer 20 is disposed between the semiconductor circuit layer 13 and the transparent electrode layer 32. The electrophoretic display layer 20 includes a microcapsule made of a transparent resin in which an electrophoretic dispersion is sealed. The electrophoretic dispersion is configured by enclosing a transparent insulating liquid, positively charged white particles, and negatively charged black pigment. The electrophoretic particles have a property of moving in the electrophoretic dispersion medium according to the applied voltage. The film thickness of the electrophoretic display layer 20 is, for example, 50 to 75 μm.

The laminate composed of the flexible semiconductor circuit substrate 10, the flexible transparent electrode substrate 30, and the electrophoretic display layer 20 is covered and sealed with the protective sheet 2. The protective sheet 2 is preferably in contact with part or all of the chamfered surface of the transparent substrate 31.
The protective sheet 2 is an anaerobic / waterproof sheet made of a transparent resin. For example, polyethylene terephthalate (PET), polymethyl methacrylate, polycarbonate, or the like is used.

  A hot melt adhesive or UV adhesive is preliminarily provided on the inner surface of the protective sheet 2 covering the laminated body, and after coating the laminated body with the protective sheet 2, by applying heat or UV under vacuum, The protective sheet 2 is in close contact with the back substrate 11 and the transparent substrate 31 via an adhesive, and seals the laminate.

In the present embodiment, since the outer peripheral portion on the upper surface side of the transparent substrate 31 is chamfered at an angle α, local stress applied to the outer peripheral portion of the laminate can be reduced when the protective sheet 2 is installed, which is excellent. Display quality and electrical characteristics can be realized. Moreover, according to the said structure, since the whole thickness of the electrophoretic display device 1 does not become large in an outer peripheral part, the electrophoretic display device which has uniform thickness is obtained.
Moreover, by setting it as the said structure, the sealing width t which is a clearance gap between the protection sheets 2 of the surface side and a back side can be narrowed. Since the sealing width t can be reduced, the effect of preventing water and the like is improved. Further, even when a protective sheet having a certain elasticity is used, the sealing width t can be narrowed because the sealing bending position is dispersed by the chamfered portion. Further, since the protective sheet is gently bent, there is little partial damage to the protective sheet.
Furthermore, since the cross section of the sealing portion near the outer peripheral portion of the laminate is reduced by reducing the sealing width t, the size of the generated bubbles 3 can be reduced, and excellent display quality and electrical characteristics can be achieved. Is obtained.
Since the amount of the back substrate 11 protruding from the transparent substrate 31 greatly affects the generation of bubbles, it is desirable to reduce it to the same surface as much as possible.

In the above description, the flexible electrophoretic display device 1 has been described. However, when flexibility is not required, the back substrate 11 may be a glass substrate.
In the above description, a display device including a microcapsule-type electrophoresis display layer has been described. However, the present invention is not limited to this, and the display device is a horizontally-moving electrophoresis type or a vertical electrophoresis type display device. May be.
Further, the portion provided with the chamfer may be at least a part of the outer peripheral portion of the transparent substrate, or the entire outer peripheral portion may be chamfered.

(Example 2)
The second embodiment differs from the first embodiment only in that the chamfered surface is not a flat surface but a curved surface. 2, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.
Also in the present embodiment, the protective sheet 2 is preferably in contact with a part or all of the chamfered surface that forms a curved surface.
Also in the present embodiment, when the protective sheet 2 is installed, local stress is not applied to the outer peripheral portion of the laminated body, the entire thickness of the electrophoretic display device 1 ′ can be made uniform, and the sealing width t is narrowed. And excellent display quality and electrical characteristics can be realized.
The shape of the curved surface may be a shape that forms a part of the circumference, or may be an arbitrary curved surface.

(Example 3)
In Example 3, the transparent substrate 31 has a configuration in which the film thickness is reduced in at least a part of the outer periphery of the surface opposite to the surface on which the transparent electrode phase 32 is provided, that is, the upper surface side of the transparent substrate 31. The only difference from Example 1 is that the film thickness of the outer peripheral part of the film is made s smaller than the film thickness of the part other than the outer peripheral part. 3, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The film thickness difference s is preferably 0.1 mm or more.
Also in this embodiment, when the protective sheet 2 is installed, local stress is not applied to the outer peripheral portion of the laminated body, the entire thickness of the electrophoretic display device 1 '' can be made uniform, and the sealing width t is narrowed. It is possible to achieve excellent display quality and electrical characteristics.

(Electronics)
An electronic apparatus of the present invention includes the above-described electrophoretic display device. Here, the “electronic device” includes any device including a display unit that uses display by an electrophoretic material, and includes a display device, a television device, an electronic book, an electronic paper, a wristwatch, an electronic notebook, a calculator, and a mobile phone. Mobile information terminals and the like. Also, things that deviate from the concept of “equipment”, for example, flexible paper / film-like objects, belonging to real estate such as wall surfaces to which these objects are attached, moving objects such as vehicles, flying objects, ships, etc. Including those belonging to.

FIG. 1 is a partial cross-sectional view of an electrophoretic display device according to Embodiment 1 of the present invention. FIG. 2 is a partial cross-sectional view of the electrophoretic display device according to the second embodiment. FIG. 3 is a partial cross-sectional view of the electrophoretic display device according to the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Semiconductor circuit board, 11 Back substrate, 13 Semiconductor circuit layer, 20 Electrophoretic display layer, 30 Transparent electrode substrate, 31 Transparent substrate, 32 Transparent electrode layer, 2 Protective sheet, 5 Display area, 1 Electrophoretic display device

Claims (8)

A laminate comprising a transparent substrate provided with a transparent electrode layer, a back substrate provided with a semiconductor circuit layer, and an electrophoretic display layer disposed between the transparent electrode layer and the semiconductor circuit layer;
A protective sheet covering and sealing the laminate,
An electrophoretic display device comprising at least
The electrophoretic display device, wherein the transparent substrate has a reduced film thickness in at least a part of an outer peripheral portion of a surface opposite to a surface on which the transparent electrode layer is provided.   2. The electrophoretic display device according to claim 1, wherein at least a part of an outer peripheral portion of a surface of the transparent substrate opposite to a surface on which the transparent electrode layer is provided is chamfered.   The electrophoretic display device according to claim 2, wherein the chamfered surface is a flat surface inclined at an angle of 5 ° to 45 ° with respect to a surface direction of the transparent substrate.   The electrophoretic display device according to claim 2, wherein the chamfered surface is a curved surface.   The electrophoretic display device according to claim 2, wherein the protective sheet is in contact with part or all of the chamfered surface.   2. The electrophoretic display device according to claim 1, wherein the transparent substrate has a thickness of at least a part of the outer peripheral portion being 0.1 mm or more smaller than a thickness of a portion other than the outer peripheral portion.   The electrophoretic display device according to claim 1, wherein the outer peripheral portion is an outer peripheral portion that does not overlap a display area of the electrophoretic display layer. An electronic apparatus comprising the electrophoretic display device according to claim 1.

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