JP2011059433A - Electrophoretic display device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophoretic display device that suppresses formation of an air layer between a protective substrate and that an electrophoretic sheet and also suppresses absorption of external moisture and oxygen by an electrophoretic element. <P>SOLUTION: The electrophoretic display device includes an element substrate (10), the electrophoretic sheet (200) provided on the element substrate, a water glass member (300) formed of water glass so as to cover surfaces (200a, 200b) of the electrophoretic sheet that do not face the element substrate, and the protective substrate (50) provided so as to oppositely face to the element substrate with the electrophoretic sheet and water glass member and to be in contact with the water glass member. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to the technical fields of electrophoretic display devices and electronic devices.

  As an electrophoretic display device of this type, an electrophoretic sheet including an electrophoretic element is known which is provided on an element substrate provided with a pixel electrode and a pixel switching element for driving the pixel electrode. Yes. In such an electrophoretic display device, when the electrophoretic element absorbs external moisture and oxygen, the electrical characteristics of the electrophoretic element may change and display quality may deteriorate. Therefore, a protective substrate having a size larger than that of the electrophoretic sheet (or sometimes referred to as “sealing substrate”) is provided on the side of the electrophoretic sheet that does not face the element substrate, and between the element substrate and the protective substrate. A resin member may be provided so as to surround the electrophoretic sheet.

  For example, in Patent Document 1, in an organic EL (Electro-Luminescence) light-emitting device, an organic EL element is hermetically sealed and stored by an element substrate and a sealing substrate that are anodically bonded through a silicate glass containing alkali metal atoms. Techniques to do this are disclosed.

JP 2008-10246 A

  In the electrophoretic display device as described above, an air layer is interposed between the electrophoretic sheet and the protective substrate, and display quality deteriorates due to a difference in refractive index between the protective substrate and the air layer. There is a technical problem that there is a risk of it.

  The present invention has been made in view of the above-described problems, for example, and can suppress the formation of an air layer between the protective substrate and the electrophoretic sheet, and the electrophoretic element absorbs external moisture and oxygen. It is an object of the present invention to provide an electrophoretic display device capable of suppressing the above and capable of performing high-quality display and an electronic apparatus including such an electrophoretic display device.

  In order to solve the above problems, an electrophoretic display device of the present invention covers an element substrate, an electrophoretic sheet provided on the element substrate, and a surface of the electrophoretic sheet that does not face the element substrate. A water glass member formed of water glass, and a protective substrate provided so as to face the element substrate through the electrophoresis sheet and the water glass member and to be in contact with the water glass member. .

  According to the electrophoretic display device of the present invention, during the operation, for example, a voltage corresponding to an image signal is applied to the electrophoretic element included in the electrophoretic sheet, so that an image is displayed, for example, in the display area.

  The element substrate includes, for example, a pixel electrode and a pixel switching element such as a transistor for driving the pixel electrode provided for each pixel in the display region on a glass substrate.

The electrophoretic sheet includes, for example, a resin substrate on which a common electrode is formed, and an electrophoretic element fixed on the resin substrate. The electrophoretic sheet typically has a resin substrate facing the element substrate via the electrophoretic element (that is, the common electrode on the resin substrate faces the pixel electrode on the element substrate via the electrophoretic element). As provided) on the element substrate. During operation of the electrophoretic display device, for example, a voltage corresponding to an image signal is applied between the pixel electrode and the common electrode. For example, an electrophoretic element that is a microcapsule includes, for example, a plurality of negatively charged white particles and a plurality of positively charged black particles as electrophoretic particles. In the electrophoretic element, one of a plurality of negatively charged white particles and a plurality of positively charged black particles moves to the pixel electrode side according to a voltage applied between the pixel electrode and the common electrode (that is, the pixel electrode side). ), And the other moves to the common electrode side. Thereby, an image corresponding to the moved electrophoretic particles is displayed on the common electrode side (that is, the protective substrate side of the element substrate and the protective substrate). In the present invention, in particular, the surface that does not face the element substrate in the electrophoretic sheet A water glass member formed of water glass is provided so as to cover the protective substrate, and the protective substrate is provided so as to face the element substrate through the electrophoresis sheet and the water glass member and to be in contact with the water glass member. . Specifically, the water glass member is, for example, on the surface of the electrophoresis sheet that does not face the element substrate (that is, the protective substrate facing surface that faces the protective substrate and the side surface that intersects the protective substrate facing surface). It is formed by applying water glass (that is, an aqueous solution containing sodium silicate (Na2SiO3)). The protective substrate is typically a glass substrate. The protective substrate is provided in contact with the water glass member, and is adhered to the electrophoretic sheet by the water glass member.

  Therefore, an air layer is formed between the protective substrate and the electrophoretic sheet by the water glass member (more specifically, a portion of the water glass member formed on the surface of the electrophoretic sheet facing the protective substrate). This can be suppressed. Therefore, an air layer is interposed between the electrophoretic sheet and the protective substrate, and deterioration of display quality due to a difference in refractive index between the protective substrate and the air layer can be suppressed or prevented.

  Furthermore, the electrophoretic element absorbs external moisture and oxygen by the protective substrate and the water glass member (more specifically, the portion formed on the side surface of the electrophoretic sheet of the water glass member) (in other words, the portion of the water glass member). , External moisture and oxygen can intrude into the electrophoretic element contained in the electrophoretic sheet). That is, the moisture resistance and oxygen resistance with respect to the electrophoretic sheet can be enhanced by the protective substrate and the water glass member. Therefore, it can be suppressed or prevented that the electrophoretic element absorbs external moisture and oxygen to change the electrical characteristics of the electrophoretic element and deteriorate the display quality.

  As a result, according to the electrophoretic display device of the present invention, high-quality display can be performed.

  In addition, as described above, the water glass member can be manufactured by a relatively simple method of applying water glass to the surface of the electrophoretic sheet that does not face the element substrate, which complicates the manufacturing process. The reliability of the electrophoretic display device can be improved without inviting. It is also possible to reduce the manufacturing cost of the electrophoretic display device.

  In addition, when a water glass member (more specifically, a portion of the water glass member formed on the surface facing the protective substrate of the electrophoretic sheet) is applied to the protective substrate from the outside, for example, It is possible to suppress or prevent the electrophoretic element included in the electrophoretic sheet from being damaged. That is, since the water glass member is made of water glass and has elasticity, the water glass member can also function as an impact relaxation material (that is, a cushion) that reduces the impact applied to the electrophoretic sheet from the protective substrate side. it can.

  In addition, it is preferable that the water glass which comprises a water glass member is neutral (namely, a state which is neither acidic nor alkaline), or is close to neutrality. In this case, the electrophoretic element contained in the electrophoretic sheet can be almost completely or practically eliminated from being corroded by the water glass member.

  As described above, according to the electrophoretic display device of the present invention, it is possible to suppress the formation of an air layer between the protective substrate and the electrophoretic sheet, and the electrophoretic element absorbs external moisture and oxygen. Can be suppressed. As a result, high-quality display can be performed.

  In one aspect of the electrophoretic display device of the present invention, the electrophoretic display device is provided between the element substrate and the protective substrate so as to cover a side surface portion of the water glass member that faces the side surface of the electrophoretic sheet, and is formed from a resin. A resin member is provided.

  According to this aspect, since the side surface portion of the water glass member is covered by the resin member, it is possible to prevent external moisture from adhering to the water glass member. Therefore, it is possible to prevent the water glass member from being eroded by moisture. Thereby, the function of the water glass member that suppresses or prevents external moisture and oxygen from entering the electrophoretic element can be reliably maintained, and the reliability of the electrophoretic display device can be improved.

  In another aspect of the electrophoretic display device of the present invention, the electrophoretic sheet includes a resin substrate and an electrophoretic element, the protective substrate is made of glass, and the resin substrate and the protective substrate are the water. The glass members are bonded to each other.

  According to this aspect, since the resin substrate constituting the electrophoretic sheet and the protective substrate made of glass are bonded to each other by the water glass member, an air layer is interposed between the electrophoretic sheet and the protective substrate. Can be reliably suppressed or prevented. Further, since the protective substrate is made of glass and the refractive index is closer to the water glass member than air, the display quality is hardly deteriorated due to the difference in the refractive index between the protective substrate and the water glass member. There is nothing in practice.

  In order to solve the above problems, an electronic apparatus of the present invention includes the above-described electrophoretic display device of the present invention.

  According to the electronic device of the present invention, since the above-described electrophoretic display device of the present invention is provided, a high-quality display can be performed, for example, wristwatch, electronic paper, electronic notebook, mobile phone, portable audio device. Various electronic devices such as can be realized.

  The effect | action and other gain of this invention are clarified from the form for implementing invention demonstrated below.

1 is a plan view illustrating a schematic configuration of an electrophoretic display device according to a first embodiment. It is sectional drawing in the II-II 'line | wire of FIG. It is a perspective view which shows the structure of the electronic paper which is an example of the electronic device to which the electrophoretic display apparatus is applied. It is a perspective view which shows the structure of the electronic notebook which is an example of the electronic device to which the electrophoretic display apparatus is applied.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
The electrophoretic display device according to the first embodiment will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a plan view showing a schematic configuration of the electrophoretic display device according to the present embodiment, and FIG. 2 is a cross-sectional view taken along the line II-II ′ of FIG.

  1 and 2, the electrophoretic display device 1 according to the present embodiment includes an electrophoresis included in an electrophoretic sheet 200 provided between a TFT substrate 10 and a protective substrate 50 that are arranged to face each other. This is an electrophoretic display device capable of displaying in the display region 10a by applying a voltage corresponding to an image signal to the microcapsule 80 which is an element.

  The TFT substrate 10 is an example of the “element substrate” according to the present invention. On the glass substrate, pixel electrodes and thin film transistors (TFTs) for driving the pixel electrodes are arranged in a matrix in the display region 10a. It is provided for each pixel arranged in the. Note that the TFT substrate 10 may have flexibility or may not have flexibility. By forming a thin glass substrate that constitutes the TFT substrate 10 by, for example, polishing, the TFT substrate 10 having flexibility can be formed. The TFT substrate 10 may be, for example, a plastic substrate, a stainless steel substrate, an aluminum substrate, or the like.

  The electrophoretic sheet 200 is provided on the TFT substrate 10 and includes the counter substrate 20 and a plurality of microcapsules 80 fixed on the counter substrate 20 by a binder 85.

  The counter substrate 20 is made of a PET (polyethylene terephthalate) substrate as an example of the “resin substrate” according to the present invention. The counter substrate 20 has a smaller substrate size than the TFT substrate 10 and is disposed so as to face the TFT substrate 10 via the microcapsules 80 in the display region 10a. On the surface of the counter substrate 20 facing the TFT substrate 10, a common electrode is formed in a solid shape so as to face a plurality of pixel electrodes provided on the TFT substrate 10. The common electrode is made of a transparent conductive material such as magnesium silver (MgAg), indium tin oxide (ITO), indium zinc oxide (IZO), or the like.

  In the electrophoretic display device 1 according to the present embodiment, in the manufacturing process, an electrophoretic sheet 200 in which a plurality of microcapsules 80 are fixed to the counter substrate 20 side in advance by a binder 85 is separately manufactured. Etc. are adhered to the TFT substrate 10 side on which the etc. are formed by an adhesive layer.

  The microcapsule 80 is sandwiched between the pixel electrode on the TFT substrate 10 and the common electrode on the counter substrate 20, and one or a plurality of microcapsules 80 are arranged in one pixel (in other words, for one pixel electrode). Yes.

  The microcapsule 80 includes a dispersion medium, a plurality of white particles that are electrophoretic particles, and a plurality of black particles enclosed therein. The microcapsule 80 is formed in a spherical shape having a particle size of about 50 μm, for example.

  The coating film functioning as the outer shell of the microcapsule 80 is formed of a translucent polymer resin such as an acrylic resin such as polymethyl methacrylate or polyethyl methacrylate, a urea resin, or gum arabic.

  The dispersion medium is a medium in which white particles and black particles are dispersed in the microcapsule 80 (in other words, in the coating). As a dispersion medium, water, alcohol solvents such as methanol, ethanol, isopropanol, butanol, octanol and methyl cellosolve, various esters such as ethyl acetate and butyl acetate, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, Aliphatic hydrocarbons such as pentane, hexane and octane, cycloaliphatic hydrocarbons such as cyclohexane and methylcyclohexane, benzene, toluene, xylene, hexylbenzene, hebutylbenzene, octylbenzene, nonylbenzene, decylbenzene, undecylbenzene , Aromatic hydrocarbons such as benzenes having a long-chain alkyl group such as dodecylbenzene, tridecylbenzene, tetradecylbenzene, and halogens such as methylene chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane Hydrocarbons, carboxylate or other oils may be used singly or as a mixture. Further, a surfactant may be blended in the dispersion medium.

  The white particles are particles (polymer or colloid) made of a white pigment such as titanium dioxide, zinc white (zinc oxide), and antimony trioxide, and are negatively charged, for example.

  The black particles are particles (polymer or colloid) made of a black pigment such as aniline black or carbon black, and are positively charged, for example.

  For this reason, the white particles and the black particles can move in the dispersion medium by the electric field generated by the potential difference between the pixel electrode and the common electrode.

  These pigments include electrolytes, surfactants, metal soaps, resins, rubbers, oils, varnishes, charge control agents composed of particles such as compounds, titanium-based coupling agents, aluminum-based coupling agents, silanes as necessary. A dispersant such as a system coupling agent, a lubricant, a stabilizer, and the like can be added.

  When a voltage is applied between the pixel electrode and the common electrode so that the potential of the common electrode is relatively high, the positively charged black particles are separated from the pixel electrode side in the microcapsule 80 by the Coulomb force. At the same time, the negatively charged white particles are attracted to the common electrode side in the microcapsule 80 by the Coulomb force. As a result, white particles gather on the display surface side (that is, the common electrode side) in the microcapsule 80, and this white color is displayed on the display surface (that is, the display region 10a of the counter substrate 20 that does not face the TFT substrate 10). The color of the particles (ie white) can be displayed. Conversely, when a voltage is applied between the pixel electrode and the common electrode so that the potential of the pixel electrode is relatively high, negatively charged white particles are attracted to the pixel electrode side by Coulomb force. At the same time, the positively charged black particles are attracted to the common electrode side by the Coulomb force. As a result, the black particles gather on the display surface side of the microcapsule 80, so that the color of the black particles (that is, black) can be displayed on the display surface.

  Depending on the distribution state of white particles and black particles between the pixel electrode and the common electrode, it is also possible to display gray such as light gray, gray, dark gray and the like, which is an intermediate gradation between white and black. Further, by replacing the pigment used for the white particles and the black particles with pigments such as red, green and blue, for example, color display such as red, green and blue can be performed.

  In FIG. 1 and FIG. 2, in the present embodiment, in particular, the electrophoretic sheet 200 includes a water glass member 300 formed of water glass so as to cover a surface not facing the TFT substrate 10, and the protective substrate 50 includes: The electrophoretic sheet 200 and the water glass member 300 are provided so as to face the TFT substrate 10 and to be in contact with the water glass member 300. Specifically, the water glass member 300 is formed on a water glass (that is, sodium silicate (Na2SiO3) on the protective substrate facing surface 200a facing the protective substrate 50 and the side surface 200b intersecting the protective substrate facing surface 200a in the electrophoresis sheet 200. )) Is applied. That is, the water glass member 300 includes a first portion 310 formed on the protective substrate facing surface 200a of the electrophoresis sheet 200 and a second portion 320 formed on the side surface 200b of the electrophoresis sheet 200. Yes. The first portion 310 of the water glass member 300 overlaps the protective substrate facing surface 200a of the electrophoretic sheet 200 when viewed from the normal direction of the TFT substrate 10, and the second portion 320 of the water glass member 300 is the TFT substrate. As viewed from the normal direction of the number 10, the periphery of the electrophoretic sheet 200 is surrounded. The protective substrate 50 is made of a glass substrate. The protective substrate 50 is provided so as to be in contact with the water glass member 300, and is adhered to the electrophoretic sheet 200 (more specifically, the counter substrate 20) by the water glass member 300.

  Therefore, the protective substrate 50 and the electrophoretic sheet 200 (more specifically, the first portion 310 formed on the protective substrate-facing surface 200a of the electrophoretic sheet 200 in the water glass member 300). More specifically, the formation of an air layer with the counter substrate 20) can be suppressed or prevented. Accordingly, an air layer is interposed between the electrophoretic sheet 200 and the protective substrate 50, and the display quality is prevented from being deteriorated due to a difference in refractive index between the protective substrate 50 and the air layer. Can be prevented.

  That is, in this embodiment, since the counter substrate 20 made of a PET substrate and the protective substrate 50 made of glass are bonded to each other by the water glass member 300, an air layer is interposed between the electrophoretic sheet 300 and the protective substrate 50. Can be reliably suppressed or prevented. Further, since the protective substrate 50 is made of glass and has a refractive index closer to that of the water glass member 300 than that of air, the display quality deteriorates due to the difference in refractive index between the protective substrate 50 and the water glass member 300. There is little or no practice.

  Furthermore, the microcapsule 80 can be made to have external moisture or water by the protective substrate 50 and the water glass member 300 (more specifically, the second portion 320 formed on the side surface 200b of the electrophoretic sheet 200 of the water glass member 300). Absorption of oxygen (in other words, entry of external moisture and oxygen into the microcapsules 80 included in the electrophoretic sheet 200) can be suppressed or prevented. That is, the moisture resistance and oxygen resistance of the microcapsule 80 can be improved. Therefore, it can be suppressed or prevented that the microcapsule 80 absorbs external moisture and oxygen, thereby changing the electrical characteristics of the microcapsule 80 and degrading the display quality.

  As a result, according to the electrophoretic display device 1 according to the present embodiment, high-quality display can be performed.

  In addition, as described above, the water glass member 300 applies water glass to the surfaces of the electrophoresis sheet 200 that do not face the TFT substrate 10 (that is, the protective substrate facing surface 200a and the side surface 200b of the electrophoresis sheet 200). Therefore, it is possible to improve the reliability of the electrophoretic display device 1 without complicating the manufacturing process. In addition, the manufacturing cost of the electrophoretic display device 1 can be reduced.

  In addition, for example, the protection substrate 50 is externally provided by the water glass member 300 (more specifically, the first portion 310 of the water glass member 300 formed on the protection substrate facing surface 200a of the electrophoretic sheet 200). It is possible to suppress or prevent the microcapsule 80 included in the electrophoretic sheet 200 from being damaged when an impact is applied. That is, since the water glass member 300 is made of water glass and has elasticity, the water glass member 300 can also function as an impact relieving material that relieves impact applied to the electrophoretic sheet 200 from the protective substrate 50 side.

  In FIG. 1 and FIG. 2, in this embodiment, in particular, the resin member 500 is provided so as to cover the second portion 320 facing the side surface 200 b of the electrophoretic sheet 200 in the water glass member 300 between the TFT substrate 10 and the protective substrate 50. Is provided. The resin member 500 is provided between the TFT substrate 10 and the protective substrate 50 so as to surround the electrophoretic sheet 200 via the second portion 320 of the water glass member 300. That is, the resin member 500 is provided so as to surround the second portion 320 of the water glass member 300 provided so as to surround the electrophoretic sheet 200 when viewed in plan on the TFT substrate 10. In other words, the resin member 500 is provided so as to cover the outer peripheral side of the second portion 320 of the water glass member 300 (that is, the side opposite to the side facing the electrophoretic sheet 200 in the second portion 320). The resin member 500 is made of a resin such as an epoxy resin, a silicon resin, or an acrylic resin. The second portion 320 of the water glass member 300 is an example of the “side portion” according to the present invention.

  Therefore, since the second portion 320 of the water glass member 300 is covered by the resin member 500, it is possible to prevent external moisture from adhering to the water glass member 300. Therefore, the water glass member 300 can be prevented from being eroded by moisture. Thereby, the function of the water glass member 300 that suppresses or prevents external moisture and oxygen from entering the microcapsule 80 can be reliably maintained, and the reliability of the electrophoretic display device 1 can be improved. .

  As described above, according to the electrophoretic display device 1 according to the present embodiment, the formation of an air layer between the protective substrate 50 and the electrophoretic sheet 200 can be suppressed, and the microcapsule 80 that is an electrophoretic element. Can absorb external moisture and oxygen. As a result, high-quality display can be performed.

<Electronic equipment>
Next, electronic devices to which the above-described electrophoretic display device is applied will be described with reference to FIGS. Below, the case where the electrophoretic display device described above is applied to electronic paper and an electronic notebook is taken as an example.

  FIG. 3 is a perspective view illustrating a configuration of the electronic paper 1400.

  As illustrated in FIG. 3, the electronic paper 1400 includes the electrophoretic display device 1 according to the above-described embodiment as a display unit 1401. The electronic paper 1400 has flexibility, and includes a main body 1402 formed of a rewritable sheet having the same texture and flexibility as conventional paper.

  FIG. 4 is a perspective view showing the configuration of the electronic notebook 1500.

  As shown in FIG. 4, an electronic notebook 1500 is one in which a plurality of electronic papers 1400 shown in FIG. 3 are bundled and sandwiched between covers 1501. The cover 1501 includes display data input means (not shown) for inputting display data sent from an external device, for example. Thereby, according to the display data, the display content can be changed or updated while the electronic paper is bundled.

  Since the electronic paper 1400 and the electronic notebook 1500 described above include the electrophoretic display device according to the above-described embodiment, the electronic paper 1400 and the electronic notebook 1500 can display images with high reliability and high quality.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and an electrophoretic display with such a change. The apparatus and the electronic apparatus provided with the electrophoretic display device are also included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... TFT substrate, 20 ... Counter substrate, 50 ... Protective substrate, 80 ... Microcapsule, 200 ... Electrophoresis sheet, 300 ... Water glass member, 500 ... Resin member

Claims (4)

An element substrate;
An electrophoresis sheet provided on the element substrate;
A water glass member formed of water glass so as to cover a surface of the electrophoresis sheet that does not face the element substrate;
An electrophoretic display device comprising: a protective substrate provided so as to face the element substrate through the electrophoretic sheet and the water glass member and to be in contact with the water glass member.   2. The apparatus according to claim 1, further comprising a resin member that is provided between the element substrate and the protective substrate so as to cover a side surface portion of the water glass member that faces the side surface of the electrophoretic sheet. The electrophoretic display device described. The electrophoretic sheet comprises a resin substrate and an electrophoretic element,
The protective substrate is made of glass,
The electrophoretic display device according to claim 1, wherein the resin substrate and the protective substrate are bonded to each other by the water glass member.   An electronic apparatus comprising the electrophoretic display device according to claim 1.