WO2017159075A1

WO2017159075A1 - Reflective display device and electronic device

Info

Publication number: WO2017159075A1
Application number: PCT/JP2017/003175
Authority: WO
Inventors: 英彦高梨
Original assignee: ソニー株式会社
Priority date: 2016-03-16
Filing date: 2017-01-30
Publication date: 2017-09-21
Also published as: JP2017167344A

Abstract

The objective of the present invention is to provide: a reflective display device which is capable of having improved reliability and display characteristics; and an electronic device. A reflective display device (1) according to one embodiment of the present disclosure is provided with: a reflective display element (30); and a wavelength conversion layer (24) which is arranged closer to the display surface than the reflective display element (30), and which converts a wavelength in a non-visible range into a wavelength in a visible range.

Description

Reflective display device and electronic device

The present disclosure relates to, for example, a reflective display device using an electrophoretic element and an electronic apparatus including the same.

In a reflective display, particularly an electrophoretic display utilizing an electrophoretic phenomenon, low reliability is a problem. This is due to the deterioration of the constituent members due to the ultraviolet rays contained in the ambient light, and the deterioration due to the ultraviolet rays is prevented by providing the ultraviolet absorbing layer on the display surface side. The ultraviolet absorbing layer reduces the light intensity in a wavelength region corresponding to ultraviolet rays. For example, Patent Document 1 discloses a microcapsule type electrophoretic display panel in which a transparent prevention film containing an ultraviolet absorber is provided on the display surface side.

JP 2006-189582 A

However, when a transparent protective film containing an ultraviolet absorber is provided on the display surface side as in the microcapsule type electrophoretic display panel described in Patent Document 1, as a result, the display characteristics (specifically, the electrophoretic display) Has a problem of reducing the reflectance. This is because the amount of incident light on the display layer and the amount of reflected light from the display layer are reduced due to interface reflection between the anti-transparent film and the display panel, the base material, and the adhesive layer.

It is desirable to provide a reflective display device and electronic equipment that can improve reliability and display characteristics.

A reflective display device according to an embodiment of the present disclosure includes a reflective display element and a wavelength conversion layer that is disposed closer to the display surface than the reflective display element and converts a wavelength in a non-visible region to a wavelength in a visible region It is equipped with.

An electronic apparatus according to an embodiment of the present disclosure includes the reflective display device according to the embodiment of the present disclosure.

In the reflective display device according to an embodiment of the present disclosure and the electronic device according to the embodiment, a wavelength conversion layer that converts the wavelength of the non-visible region into the wavelength of the visible region is disposed closer to the display surface than the reflective display element. This makes it possible to reduce the incidence of light in the non-visible region without reducing the amount of incident light on the reflective display element.

According to the reflective display device of one embodiment of the present disclosure and the electronic apparatus of one embodiment, the wavelength conversion layer that converts the wavelength of the non-visible region into the wavelength of the visible region on the display surface side of the reflective display element. Since it is arranged, incidence of light in the non-visible region to the reflective display element is reduced, and deterioration of the reflective display device due to light in the non-visible region is reduced. In addition, since the wavelength in the non-visible region is converted into the wavelength in the visible region, it is possible to suppress a decrease in the amount of incident light. Therefore, it is possible to prevent a decrease in reflectivity and improve reliability and display characteristics. Note that the effects described here are not necessarily limited, and may be any effects described in the present disclosure.

It is sectional drawing showing an example of a structure of the reflection type display apparatus which concerns on one embodiment of this indication. FIG. 2 is a schematic plan view of the reflective display device shown in FIG. 1. It is sectional drawing showing the other example of a structure of the reflection type display apparatus which concerns on embodiment of this indication. It is a schematic diagram explaining the electrophoretic element shown in FIG. FIG. 2 is a cross-sectional view for explaining the operation of the display device shown in FIG. 1. FIG. 2 is a cross-sectional view for explaining the operation of the display device shown in FIG. 1. It is sectional drawing showing the other example of a structure of the reflection type display apparatus which concerns on embodiment of this indication. It is sectional drawing showing the structure of the reflection type display apparatus which concerns on the modification of this indication. 12 is a perspective view illustrating an example of an appearance of application example 1. FIG. 12 is a perspective view illustrating another example of the appearance of application example 1. FIG. 12 is a perspective view illustrating an appearance of application example 2. FIG. 14 is a perspective view illustrating an example of an appearance of application example 3. FIG. 22 is a perspective view illustrating another example of the appearance of application example 3. FIG.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order.
1. Embodiment (example in which a wavelength conversion layer is provided on the display surface side of the counter substrate)
1-1. Configuration of reflection type display device 1-2. Operation of the reflective display device 1-3. Action / Effect Modification (example using a liquid crystal element as a reflective display element)
3. Application example 4. Example

<1. Embodiment>
FIG. 1 illustrates an example of a cross-sectional configuration of a reflective display device (reflective display device 1) according to an embodiment of the present disclosure. FIG. 2 schematically shows a planar configuration of the reflective display device 1. FIG. 1 shows a cross section taken along line II in FIG. The reflective display device 1 is an electrophoretic display that generates contrast using an electrophoretic phenomenon, and an electrophoretic element (electrophoresis) is provided on a display layer provided between the driving substrate 10 and the counter substrate 20. Element 30) is used. The electrophoretic element 30 corresponds to a specific example of the reflective display element of the present disclosure. The reflective display device 1 according to the present embodiment includes a wavelength conversion layer on the outermost surface of the counter substrate 20 disposed on the display surface side, out of the drive substrate 10 and the counter substrate 20 disposed to face each other with the electrophoretic element 30 therebetween. 24 is arranged. FIG. 1 schematically shows the configuration of the reflective display device 1 and may differ from actual dimensions and shapes.

(1-1. Configuration of Reflective Display Device)
In the reflective display device 1, for example, as shown in FIG. 1, the drive substrate 10 and the counter substrate 20 are arranged to face each other via the electrophoretic element 30, and the display surface is provided on the counter substrate 20 side. is doing. The phrase “having a display surface on the counter substrate 20 side” means that an image is displayed toward the counter substrate 20 (the user can visually recognize an image from the counter substrate 20 side). Further, a seal layer 16 is provided between the drive substrate 10 and the electrophoretic element 30, thereby sealing the electrophoretic element 30 in the surface direction, and at the same time, the drive substrate 10 and the electrophoretic element 30. Are pasted together. The counter substrate 20 is provided with a partition unit 38 that also serves as an adhesive layer, whereby the counter substrate 20 and the electrophoretic element 30 are bonded together.

For example, the driving substrate 10 has a thin film transistor (TFT) 12, a protective layer 13, a planarization insulating layer 14, and a pixel electrode 15 formed in this order on one surface of a support base 11. For example, the TFT 12 and the pixel electrode 15 are divided and formed in a matrix or segment according to a pixel pattern or the like.

The support base 11 is made of, for example, an inorganic material, a metal material, a plastic material, or the like. Examples of the inorganic material include silicon (Si), silicon oxide (SiO _x ), silicon nitride (SiN _x ), and aluminum oxide (AlO _x ). Silicon oxide includes glass or spin-on-glass (SOG). Examples of the metal material include aluminum (Al), nickel (Ni), and stainless steel, and examples of the plastic material include polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyethyl ether. Ketone (PEEK) etc. are mentioned.

The support substrate 11 may be light transmissive or non-light transmissive. This is because the image is displayed on the counter substrate 20 side, and thus the support base 11 does not necessarily need to be light transmissive. The support base 11 may be a rigid substrate such as a wafer, or may be composed of a flexible thin glass or film. By using a flexible material for the support base 11, the flexible reflective display device 1 can be realized.

TFT 12 is a switching element for selecting a pixel. The TFT 12 may be an inorganic TFT using an inorganic semiconductor layer as a channel layer or an organic TFT using an organic semiconductor layer. The protective layer 13 and the planarization insulating layer 14 are made of an insulating resin material such as polyimide, for example. If the surface of the protective layer 13 is sufficiently flat, the planarization insulating layer 14 can be omitted. The pixel electrode 15 is formed of a metal material such as gold (Au), silver (Ag), or copper (Cu), for example. The pixel electrode 15 is connected to the TFT 12 through a contact hole (not shown) provided in the protective layer 13 and the planarization insulating layer 14.

Note that FIG. 1 shows a case where, for example, the TFT 12 is arranged for each cell 36 described later (one TFT 12 is provided for one cell 36). However, the present invention is not necessarily limited to this, and the numbers and positional relationships of the cells 36 and the TFTs 12 may be arbitrary. For example, two TFTs 12 may be arranged for three cells 36, or a boundary between two adjacent TFTs 12 may be located within the range of the cell 36.

The seal layer 16 is made of an insulating resin material such as polyimide, for example, similarly to the protective layer 13 and the planarization insulating layer 14. The sealing layer 16 can be omitted as appropriate.

The counter substrate 20 includes, for example, a support base 21, a counter electrode 22, and a wavelength conversion layer 24. A counter electrode 22 is provided on the surface of the support base 21 facing the drive substrate 10, and a wavelength conversion layer 24 is provided on the surface (display surface) opposite to the surface facing the drive substrate 10. The counter electrode 22 may be arranged in a matrix or segment like the pixel electrode 15.

The support base 21 is made of the same material as the support base 11 except that it is light transmissive. For the counter electrode 22, for example, a light-transmitting conductive material such as indium oxide-tin oxide (ITO), antimony oxide-tin oxide (ATO), fluorine-doped tin oxide (FTO), or aluminum-doped zinc oxide (AZO). (Transparent electrode material).

When an image is displayed on the counter substrate 20 side, the reflective display device (electrophoretic element 30) is seen through the counter electrode 22, so that the light transmittance (transmittance) of the counter electrode 22 is as much as possible. High is preferable, for example, 80% or more. Further, the electrical resistance of the counter electrode 22 is preferably as low as possible, for example, 100Ω / □ or less.

The wavelength conversion layer 24 converts a wavelength in a non-visible region into a wavelength in a visible region, and is provided on the display surface side of the counter substrate 20 in the present embodiment. The wavelength in the non-visible region is specifically a wavelength in the ultraviolet region (ultraviolet rays, for example, 300 nm or more and less than 400 nm), and the wavelength conversion layer 24 of the present embodiment uses ultraviolet rays, for example, wavelengths of 400 nm or more and 700 nm or less. It is to convert to. Accordingly, it is possible to prevent a decrease in the amount of reflected light by the electrophoretic element 30 and to increase the amount of reflected light by the electrophoretic element 30 while reducing the incidence of ultraviolet rays that deteriorate the constituent members of the electrophoretic element 30.

The wavelength conversion layer 24 may be provided at least on the display surface side with respect to the electrophoretic element 30, for example, between the support base 21 and the counter electrode 22, or between the counter electrode 22 and the partition unit 38. You may make it arrange | position to. However, in order to prevent a decrease in the amount of light incident on the electrophoretic element 30 due to interface reflection, it is preferable to provide the counter substrate 20 on the display surface side as in the present embodiment.

For example, the following characteristics are required for the material of the wavelength conversion layer 24. First, it is transparent in the wavelength range (visible range) that can be detected by humans, has high absorption efficiency for ultraviolet light, can convert absorbed light into visible light with high efficiency, and converted light Are effectively collected on the display surface side (does not scatter visible light). Examples of such materials include organic dyes including phosphor materials, rare earth ions / complexes, quantum dots, and the like. These wavelength conversion materials can be used alone or as a mixture of plural kinds.

Examples of organic dyes that can be used as wavelength conversion materials include cyanine dyes, pyridine dyes, rhodamine dyes, coumarin dyes, perylene dyes, naphthalimide dyes, triazole dyes, and oxadiazole dyes. And dyes, thiophene dyes, xanthine dyes, styrylbenzene dyes, anthraquinone dyes, anthrapyridone dyes, perinone dyes, quinophthalone dyes, aminobenzopyranoxanthene dyes, and the like.

Examples of rare earth ions and complexes include complexes of rare earth elements such as europium (Eu), terbium (Tb), dysprosium (Dy), and those in which ions of these rare earth elements are doped into transparent single crystals or glasses. It is done. Examples of the former include [Eu (phen) ₂ ] Cl ₃ (where phen is 1,10-phenanthroline), [Tb (bpy) ₂ ] Cl ₃ (where bpy is 2,2′-dipyridine) ) And the like. The latter includes, for example, ^ions such as Eu ²⁺ , Eu ³⁺ , Tb ³⁺ , Cr ³⁺ , Sm ²⁺ , Sm ³⁺ , which are aluminum oxide, calcium fluoride, barium fluoride, magnesium potassium fluoride. And transparent crystals such as those doped in glass. Other wavelength conversion materials using rare earth elements include fluorescent particles such as Y ₂ O ₂ S: Eu, Mg, Ti, YVO 4: Bi ³⁺ , Eu ³⁺ , and compounds composed of strontium oxide and aluminum oxide, Eu and Dy. Inorganic fluorescent materials such as SrAl ₂ O ₄ : Eu, Dy, Sr ₄ Al ₁₄ O ₂₅ : Eu, Dy, CaAl ₂ O ₄ : Eu, Dy, ZnS: Cu, and the like added.

Quantum dots include semiconductor materials such as CdSe, Si, CdS, ZnS, GaAs, InAs, InS, PbSe, PbS, CuCl, and CIS (Cu-In-Se) with a particle size of several nanometers to several tens of nanometers. Is mentioned.

It is desirable that the wavelength conversion material is contained in a transparent host material that satisfies the above-described characteristics. Here, the term “transparent” means that the transmittance of light having a wavelength of 400 nm to 800 nm at an optical path length of 100 μm is 90% or more. Examples of such host materials include acrylic resins, methacrylic resins, urethane resins, epoxy resins, polyesters, polyethylene, polyvinyl chloride and other resins, and copolymers of these resins such as ethylene vinyl acetate copolymers, oxidation Examples thereof include transparent crystals and glasses such as aluminum, calcium fluoride, barium fluoride, and magnesium fluoride fluoride.

The thickness of the wavelength conversion layer 24 in the Z-axis direction (hereinafter simply referred to as thickness) varies depending on the light emission efficiency (conversion efficiency) of the phosphor material contained, but prevents a decrease in the amount of light incident on the electrophoretic element 30. Therefore, the thinner one is preferable, and for example, it is preferably 1 μm or more and 100 μm or less. Note that 1 μm is the particle size of a general particulate phosphor material. The wavelength conversion layer 24 is obtained, for example, by applying a wavelength conversion material including a phosphor material on a film base material, and is commercially available from, for example, Hitachi Chemical, Batel Japan, Nitto Denko and the like.

Also, the reflective display device 1 of the present embodiment can adjust the chromaticity in display by increasing the light intensity in a specific wavelength region by appropriately selecting the phosphor material to be used. Further, fluorescent display is possible by particularly increasing the light intensity in a specific wavelength region.

Note that the wavelength conversion layer 24 does not have to be in the form of a film, and may be formed by, for example, coating directly on the counter substrate 20. In this case, it is preferable to provide an antireflection layer 25 on the wavelength conversion layer 24 as in the reflective display device 2 shown in FIG. Thereby, interface reflection (specifically, surface reflection of the wavelength conversion layer 24) can be reduced. The antireflection layer 25 is formed, for example, by vacuum-depositing magnesium fluoride on the outermost surface of the reflective display device 2, here, the wavelength conversion layer 24.

The electrophoretic element 30 includes electrophoretic particles 32 and a porous layer 33 in an insulating liquid 31, as shown in FIGS. The migrating particles 32 are dispersed in the insulating liquid 31, and the porous layer 33 includes a fibrous structure 331 and non-migrating particles 332, and has a plurality of pores 333. One or more partition walls 35 are adjacent to the porous layer 33 from the opposite side of the display surface (the drive substrate 10 side).

The insulating liquid 31 is filled in a space between the drive substrate 10 and the counter substrate 20, for example. The insulating liquid 31 is composed of, for example, any one kind or two or more kinds of non-aqueous solvents such as an organic solvent, and specifically includes hydrocarbon solvents such as paraffin or isoparaffin. It is preferable to make the viscosity and refractive index of the insulating liquid 31 as low as possible. When the viscosity of the insulating liquid 31 is lowered, the mobility (response speed) of the migrating particles 32 is improved. In accordance with this, the energy (power consumption) required to move the migrating particles 32 is reduced. When the refractive index of the insulating liquid 31 is lowered, the difference in refractive index between the insulating liquid 31 and the porous layer 33 is increased, and the reflectance of the porous layer 33 is increased.

The insulating liquid 31 may contain other various materials as necessary. For example, a colorant, a charge adjusting agent, a dispersion stabilizer, a viscosity adjusting agent, a surfactant or a resin may be added.

The electrophoretic particles 32 are one or more charged particles (electrophoretic particles) that migrate electrically, and are displayed by moving in the insulating liquid 31 toward the pixel electrode 15 or the counter electrode 22 in accordance with an electric field. An image is displayed on the surface. The migrating particles 32 are made of particles (powder) such as organic pigments, inorganic pigments, pigments, carbon materials, metal materials, metal oxides, glass, or polymer materials (resins). As the electrophoretic particles 32, one of these may be used, or two or more of them may be used. The electrophoretic particles 32 may be pulverized particles or capsule particles of resin solids containing the above particles. Note that materials corresponding to the carbon material, metal material, metal oxide, glass, or polymer material are excluded from materials corresponding to organic pigments, inorganic pigments, or pigments. The particle size of the migrating particles 32 is, for example, 30 nm to 300 nm.

Examples of the organic pigments include azo pigments, metal complex azo pigments, polycondensed azo pigments, flavanthrone pigments, benzimidazolone pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, and perylene pigments. Perinone pigments, anthrapyridine pigments, pyranthrone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments or indanthrene pigments. Inorganic pigments include, for example, zinc white, antimony white, iron black, titanium boride, bengara, mapico yellow, red lead, cadmium yellow, zinc sulfide, lithopone, barium sulfide, cadmium selenide, calcium carbonate, barium sulfate, lead chromate Lead sulfate, barium carbonate, lead white or alumina white. Examples of the pigment include a nigrosine pigment, an azo pigment, a phthalocyanine pigment, a quinophthalone pigment, an anthraquinone pigment, and a methine pigment. The carbon material is, for example, carbon black. The metal material is, for example, gold, silver or copper. Examples of metal oxides include titanium oxide, zinc oxide, zirconium oxide, barium titanate, potassium titanate, copper-chromium oxide, copper-manganese oxide, copper-iron-manganese oxide, and copper-chromium-manganese oxide. Or copper-iron-chromium oxide. The polymer material is, for example, a polymer compound in which a functional group having a light absorption region in the visible region is introduced. If it is a high molecular compound which has a light absorption area | region in a visible region, the kind will not be specifically limited. These series of materials may be used singly or as a mixture of two or more.

The content (concentration) of the migrating particles 32 in the insulating liquid 31 is not particularly limited, and is, for example, 0.1 wt% to 10 wt%. In this concentration range, the shielding and mobility of the migrating particles 32 are ensured. Specifically, if the content of the migrating particles 32 is less than 0.1% by weight, the migrating particles 32 are less likely to shield (conceal) the porous layer 33, and there is a possibility that sufficient contrast cannot be generated. is there. On the other hand, if the content of the migrating particles 32 is more than 10% by weight, the dispersibility of the migrating particles 32 is lowered, so that the migrating particles 32 are difficult to migrate and may aggregate.

The migrating particles 32 have arbitrary optical reflection characteristics (light reflectivity). The light reflectance of the migrating particles 32 is not particularly limited, but is preferably set so that at least the migrating particles 32 can shield the porous layer 33. This is because contrast is generated by utilizing the difference between the light reflectance of the migrating particles 32 and the light reflectance of the porous layer 33.

Here, the specific material of the migrating particles 32 is selected according to, for example, the role that the migrating particles 32 play in causing contrast. When the migrating particles 32 display brightly, for example, a metal oxide such as titanium oxide, zinc oxide, zirconium oxide, barium titanate or potassium titanate is used for the migrating particles 32. Among these, titanium oxide is preferable because it is excellent in electrochemical stability and dispersibility and can provide high reflectance. When the migrating particles 32 display in the dark, the migrating particles 32 may be, for example, a carbon material such as carbon black or copper-chromium oxide, copper-manganese oxide, copper-iron-manganese oxide, copper-chromium-manganese oxide. In addition, metal oxides such as copper-iron-chromium oxide are used. Among these, it is preferable to use a carbon material for the migrating particles 32. Electrophoretic particles 32 made of a carbon material exhibit excellent chemical stability, mobility and light absorption.

In the case of bright display by the migrating particles 32, the color of the migrating particles 32 visually recognized from the outside is not particularly limited as long as a contrast can be generated, but among them, a color close to white is preferable, and white is more preferable. On the other hand, when the dark display is performed by the migrating particles 32, the color of the migrating particles 32 visually recognized from the outside is not particularly limited as long as a contrast can be generated, but among them, a color close to black is preferable, and black is more preferable. This is because in either case, high contrast can be obtained.

The migrating particles 32 are preferably easily dispersed and charged in the insulating liquid 31 for a long period of time, and are preferably not easily adsorbed to the porous layer 33. For this reason, a dispersing agent (or a charge adjusting agent) for dispersing the migrating particles 32 by electrostatic repulsion may be used, or the migrating particles 32 may be subjected to a surface treatment, or both may be used in combination.

This dispersing agent or charge adjusting agent has, for example, either positive or negative charge, or both, and increases the amount of charge in the insulating liquid 31. Examples of such a dispersant include Solsperce series manufactured by Lubrizol, BYK series or Anti-Terra series manufactured by BYK-Chemic, and Span series manufactured by TCI America.

The surface treatment is, for example, rosin treatment, surfactant treatment, pigment derivative treatment, coupling agent treatment, graft polymerization treatment or microencapsulation treatment. In particular, long-term dispersion stability of the migrating particles 32 can be maintained by performing a graft polymerization process, a microencapsulation process, or a combination thereof.

For such surface treatment, for example, a material (adsorbent material) having a functional group (adsorptive functional group) that can be adsorbed on the surface of the migrating particle 32 and a polymerizable functional group is used. The adsorptive functional group is determined according to the material for forming the migrating particles 32. For example, when the migrating particles 32 are made of a carbon material such as carbon black, an aniline derivative such as 4-vinylaniline, and when the migrating particles 32 are made of a metal oxide, methacrylic acid 3- Organosilane derivatives such as (trimethoxysilyl) propyl can be adsorbed respectively. Examples of the polymerizable functional group include a vinyl group, an acrylic group, and a methacryl group.

A surface treatment may be performed by introducing a polymerizable functional group onto the surface of the migrating particle 32 and grafting it onto the surface (graftable material). The graft material has, for example, a polymerizable functional group and a dispersing functional group. The functional group for dispersion disperses the migrating particles 32 in the insulating liquid 31 and retains dispersibility due to steric hindrance. For example, when the insulating liquid 31 is paraffin, a branched alkyl group or the like can be used as the functional group for dispersion. Examples of the polymerizable functional group include a vinyl group, an acrylic group, and a methacryl group. In order to polymerize and graft the graft material, for example, a polymerization initiator such as azobisisobutyronitrile (AIBN) may be used. In addition, a material having a functional group capable of being adsorbed on the surface of the migrating particle 32 and an alkyl chain for imparting dispersibility can be used. Examples of such materials include titanate coupling agents (for example, KR-TTS manufactured by Ajinomoto Fine Techno Co., Ltd.) and aluminate coupling agents.

For details of the method for dispersing the migrating particles 32 in the insulating liquid 31, see “Dispersion technology of ultrafine particles and its evaluation-surface treatment / fine pulverization and stabilization of dispersion in air / liquid / polymer— Science & Technology)).

As shown in FIGS. 1 and 4, the porous layer 33 is a three-dimensional structure (irregular network structure such as a nonwoven fabric) formed by a fibrous structure 331, and is one or two or more. Gap (pore 333). The pore 333 is filled with the insulating liquid 31, and the migrating particles 32 move between the pixel electrode 15 and the counter electrode 22 through the pore 333. The porous layer 33 may be adjacent to the counter electrode 22 or may be separated from it. The porous layer 33 may be supported by a spacer (not shown) that supports the space between the drive substrate 10 and the counter substrate 20.

The fibrous structure 331 includes one or more non-migrating particles 332, and the non-migrating particles 332 are held by the fibrous structure 331. In the porous layer 33 which is a three-dimensional structure, one fibrous structure 331 may be entangled at random, or a plurality of fibrous structures 331 may be gathered and overlap at random. However, both may be mixed. When there are a plurality of fibrous structures 331, each fibrous structure 331 preferably holds one or more non-migrating particles 332. FIG. 4 shows a case where the porous layer 33 is formed by a plurality of fibrous structures 331.

The reason why the porous layer 33 is a three-dimensional structure formed by the fibrous structure 331 is that the irregular three-dimensional structure easily causes external light to be irregularly reflected (multiple scattering). In this case, the light reflectance of the porous layer 33 is remarkably increased, and the porous layer 33 can be made thin in order to obtain the high light reflectance. This increases the contrast and reduces the energy required to move the migrating particles 32. Moreover, since the average pore diameter of the pores 333 is increased and the number thereof is increased, the migrating particles 32 can easily move through the pores 333. This shortens the time required to move the migrating particles 32 and lowers the energy required for the movement.

The reason why the non-migrating particles 332 are included in the fibrous structure 331 is that the light reflectance of the porous layer 33 becomes higher because external light is more easily diffusely reflected. Thereby, contrast becomes higher.

The fibrous structure 331 is a fibrous substance having a sufficient length with respect to the fiber diameter (diameter). The fibrous structure 331 is assembled and randomly overlapped to form the porous layer 33. One fibrous structure 331 may be entangled randomly to form the porous layer 33. Or the porous layer 33 by the one fibrous structure 331 and the porous layer 33 by the some fibrous structure 331 may be mixed.

The shape (appearance) of the fibrous structure 331 is not particularly limited as long as the fibrous structure 331 has a sufficiently long length with respect to the fiber diameter as described above. Specifically, it may be linear, may be curled, or may be bent in the middle. Moreover, you may branch to 1 or 2 or more directions on the way, not only extending in one direction. The fibrous structure 331 is formed by, for example, a phase separation method, a phase inversion method, an electrostatic (electric field) spinning method, a melt spinning method, a wet spinning method, a dry spinning method, a gel spinning method, a sol-gel method, or a spray coating method. Is done. By using such a method, the fibrous structure 331 having a sufficient length with respect to the fiber diameter can be easily and stably formed.

The minimum fiber diameter of the fibrous structure 331 is only required to hold the non-migrating particles 332, and is preferably 500 nm or less, and more preferably 300 nm or less, for example. The average fiber diameter of the fibrous structure 331 is preferably, for example, from 50 nm to 2000 nm, but may be outside the above range. The average fiber diameter can be measured, for example, by microscopic observation using a scanning electron microscope or the like. The average length of the fibrous structure 331 is arbitrary.

The pore 333 is formed by overlapping a plurality of fibrous structures 331 or entwining one fibrous structure 331. The average pore diameter of the pores 333 is not particularly limited, but is preferably as large as possible so that the migrating particles 32 can easily move through the pores 333. For this reason, the average pore diameter of the pores 333 is preferably 0.1 μm or more and 10 μm or less.

The thickness of the porous layer 33 is not particularly limited, but is, for example, 5 μm to 100 μm. This is because the shielding property of the porous layer 33 is enhanced and the migrating particles 32 are easily moved through the pores 333.

The fibrous structure 331 is preferably a nanofiber. Here, the nanofiber is a fibrous substance having a fiber diameter of 0.001 μm to 0.1 μm and a length of 100 times or more of the fiber diameter. By using such a nanofiber as the fibrous structure 331, light is easily irregularly reflected, and the reflectance of the porous layer 33 can be further improved. That is, the contrast of the electrophoretic element 30 can be improved. Further, in the fibrous structure 331 made of nanofibers, the proportion of the pores 333 in the unit volume increases, and the migrating particles 32 can easily move through the pores 333. Therefore, the energy required for moving the migrating particles 32 can be reduced. The fibrous structure 331 made of nanofibers is preferably formed by an electrostatic spinning method. By using the electrostatic spinning method, the fibrous structure 331 having a small fiber diameter can be formed easily and stably.

The fibrous structure 331 is formed of, for example, any one kind or two or more kinds of a polymer material or an inorganic material. Polymer materials include, for example, nylon, polylactic acid, polyamide, polyimide, polyethylene terephthalate, polyacrylonitrile, polyethylene oxide, polyvinyl carbazole, polyvinyl chloride, polyurethane, polystyrene, polyvinyl alcohol, polysulfone, polyvinyl pyrrolidone, polyvinylidene fluoride, polyhexa Fluoropropylene, cellulose acetate, collagen, gelatin, chitosan or copolymers thereof. The inorganic material is, for example, titanium oxide. Among these, a polymer material is preferable as a material for forming the fibrous structure 331. This is because the reactivity (photoreactivity, etc.) is low (chemically stable), so that an unintended decomposition reaction of the fibrous structure 331 is suppressed. Note that in the case where the fibrous structure 331 is formed of a highly reactive material, the surface of the fibrous structure 331 is preferably covered with an arbitrary protective layer.

The fibrous structure 331 preferably has an optical reflection characteristic different from that of the migrating particles 32. Specifically, the light reflectance of the fibrous structure 331 is not particularly limited, but is preferably set so that at least the porous layer 33 can shield the migrating particles 32 as a whole. This is because the contrast is generated by utilizing the difference between the light reflectance of the migrating particles 32 and the light reflectance of the porous layer 33. Accordingly, the fibrous structure 331 having light transparency (colorless and transparent) in the insulating liquid 31 is not preferable. However, the light reflectivity of the fibrous structure 331 hardly affects the light reflectivity of the entire porous layer 33, and the light reflectivity of the entire porous layer 33 is substantially the light reflectivity of the non-migrating particles 332. , The light reflectance of the fibrous structure 331 may be arbitrary.

The non-migrating particles 332 are one or more particles that are fixed to the fibrous structure 331 and do not migrate electrically. The non-migrating particles 332 may be embedded in the held fibrous structure 331 or may partially protrude from the fibrous structure 331.

The non-electrophoretic particle 332 has an optical reflection characteristic different from that of the electrophoretic particle 32. The light reflectance of the non-migrating particles 332 is not particularly limited, but is preferably set so that at least the porous layer 33 can shield the migrating particles 32 as a whole. This is because contrast is generated by utilizing the difference between the light reflectance of the migrating particles 32 and the light reflectance of the porous layer 33.

Here, the specific forming material of the non-migrating particles 332 is selected according to the role played by the non-migrating particles 332 in order to generate contrast, for example. Specifically, the material for the bright display by the non-migrating particles 332 is the same as the material selected for the bright display by the migrating particles 32. On the other hand, the material for the dark display by the non-migrating particles 332 is the same as the material selected for the dark display by the migrating particles 32. Among these, as a material selected when displaying brightly by the non-migrating particles 332, a metal oxide is preferable, and titanium oxide is more preferable. This is because it is excellent in electrochemical stability and fixability, and high reflectance can be obtained. As long as a contrast can be generated, the material for forming the non-migrating particles 332 may be the same type as the material for forming the migrating particles 32, or may be a different type.

It should be noted that the color visually recognized when the non-migrating particles 332 are displayed brightly or darkly is the same as the case where the color where the migrating particles 32 are visually recognized is described.

Further, the non-electrophoretic particles 332 may be used in combination of two or more kinds of particles having different particle diameters.

In addition, the porous layer 33 may be formed by forming a pore 333 by drilling a polymer film using a laser, and a cloth knitted with synthetic fibers or the like on the porous layer 33, Alternatively, open-cell porous polymer may be used.

The partition wall 35 partitions the possible range of the migrating particles 32 dispersed in the insulating liquid 31, and for example, as shown in FIGS. 1 and 2, a space (cell 36 to be described later) for accommodating the migrating particles 32. Is formed. For example, the partition wall 35 extends toward the driving substrate 10 and is adjacent to a part of the porous layer 33 from the display surface side.

The number and arrangement pattern of the cells 36 formed by the partition walls 35 are not particularly limited. However, in order to efficiently arrange the plurality of cells 36, the cells 36 are preferably arranged in a matrix (arrangement of a plurality of rows and a plurality of columns). Further, the shape (opening shape) of the cell 36 is not particularly limited, and may be a rectangular shape as shown in FIG. 2 or another shape (such as a hexagon).

The material for forming the partition wall 35 is not particularly limited as long as it does not affect the operation performance of the electrophoretic element 30, but is preferably a resin that is excellent in molding. This is because it is easy to form the partition wall 35 having a desired size and shape. This resin is, for example, a thermoplastic resin or a photo-curing resin (including a resist for photolithography), and other resins may be used.

When a resin is used as the material for forming the partition wall 35, the partition wall 35 is formed by, for example, a thermal imprint method using a thermoplastic resin or a photo imprint method using a photocurable resin. . Specifically, in the thermal imprint method, for example, after a mold (female mold) is pressed onto a resin (polymer material) heated to a glass transition temperature or higher, the mold is peeled off from the cooled resin. Thereby, since the shape of a mold is transcribe | transferred to the surface of resin, the partition 35 which has a desired shape is formed. This mold may be, for example, a photoresist film formed by a photolithography method, or a metal plate formed by machining such as a cutting tool.

The partition wall 35 may have a support body 37 that is continuous with the counter substrate 20, and the partition wall 35 may be supported by the support body 37. In this case, the partition wall 35 and the support 37 may be unitized (a partition unit 38). However, the partition wall 35 and the support body 37 may be integrated or separated. In the latter case, the support 37 may be a film or the like. Note that the support 37 may be provided on the drive substrate 10 side, and in this case, the partition wall 35 extends toward the counter substrate 20.

The width W of the partition wall 35 may be uniform or non-uniform in the extending direction. For example, the width W may gradually become smaller as the porous layer 33 is approached. The inclination angle (so-called taper angle) of the side surface of the partition wall 35 is not particularly limited, but is, for example, 60 ° to 90 °, preferably 75 ° to 85 °.

The pitch and height of the partition walls 35 are not particularly limited and can be set arbitrarily. For example, the pitch of the partition walls 35 is 30 μm to 300 μm, preferably 60 μm to 150 μm, and the height of the partition walls 35 is 10 μm to 100 μm, preferably 30 μm to 50 μm.

The height of the partition walls 35 and the thickness of the porous layer 33 in the Z-axis direction (hereinafter simply referred to as thickness) are preferably substantially uniform. This is because the distance between the pixel electrode 15 and the counter electrode 22 (so-called gap) is constant, and the electric field strength is made uniform. Thereby, nonuniformity such as response speed is improved.

(1-2. Operation of the reflective display device)
The reflective display device 1 operates as follows. FIG. 5A and FIG. 5B are for explaining the operation of the reflective display device, and show a cross-sectional configuration corresponding to FIG. Here, in order to simplify the illustrated contents, the porous layer 33 is simplified, and the seal layer 16, the partition unit 38, and the wavelength conversion layer 24 are omitted.

In the reflective display device 1 in the initial state, the migrating particles 32 are arranged in the retreat area R1 (FIG. 5A). In this case, since the migrating particles 32 are shielded by the porous layer 33 in all the pixels, no contrast is generated when the reflective display device 1 is viewed from the counter substrate 20 side (an image is not displayed). ) State.

On the other hand, when a pixel is selected by the TFT 12 and an electric field is applied between the pixel electrode 15 and the counter electrode 22, as shown in FIG. 5B, the migrating particles 32 are moved from the retreat area R1 to the porous layer 33 for each pixel. It moves to the display area R2 via (pore 333). In this case, since the pixels where the migrating particles 32 are shielded by the porous layer 33 coexist with the pixels which are not shielded, contrast is generated when the reflective display device 1 is viewed from the counter substrate 20 side. It becomes a state. Thereby, an image is displayed.

(1-3. Action and effect)
As described above, in a reflective display typified by an electrophoretic display, deterioration of constituent members of a display element due to ultraviolet rays contained in environmental light is a problem, which causes a decrease in reliability. For this reason, in a general electrophoretic display, an ultraviolet absorbing layer is provided on the display surface side, and this ultraviolet absorbing layer reduces the light intensity in the ultraviolet region included in ambient light, thereby ensuring reliability. It has been.

However, in an electrophoretic display provided with an ultraviolet absorbing layer, although deterioration of the constituent elements of the display element due to ultraviolet rays can be prevented, there arises a problem that the reflectivity of the electrophoretic display decreases. For general UV absorbing layers, polymers in which fine particles such as titanium dioxide (titania) that scatters UV rays are dispersed, and UV absorbing compounds such as benzophenone, benzotriazole, salicylate, and cyanoacrylate are used. Yes. In an electrophoretic display provided with an ultraviolet absorbing layer, the amount of incident light on the display element and the amount of reflected light from the display element are reduced due to interface reflection between the ultraviolet absorbing layer and a substrate or an adhesive layer, for example. The reflectivity of the electrophoretic display is reduced.

On the other hand, it is conceivable to provide a new functional layer to compensate for the decrease in the amount of incident light. However, adding a new layer increases the amount of interface reflection as in the case of providing an ultraviolet absorption layer. For this reason, the effect by addition of a new functional layer is limited.

On the other hand, in the reflective display device 1 (and the reflective display device 2) of the present embodiment, the wavelength that converts the wavelength of the non-visible region into the wavelength of the visible region closer to the display surface than the electrophoretic element 30 is. The conversion layer 24 was provided. Thereby, since incidence of a non-visible region (specifically, ultraviolet rays) is reduced, it is possible to prevent deterioration of the electrophoretic element 30 due to ultraviolet rays. In addition, since the wavelength in the invisible region is converted into the wavelength in the visible region by the wavelength conversion layer 24, an interface (for example, a wavelength conversion layer) existing between the display surface of the reflective display device 1 and the electrophoretic element 30 is used. The amount of incident light that is reduced by reflection at the interface between the substrate 24 and the counter substrate 20 is compensated. Therefore, the reflectance of the reflective display device 1 (and the reflective display device 2) can be improved. That is, it is possible to provide the reflective display device 1 (and the reflective display device 2) having high reliability and display characteristics.

In the present embodiment, the present technology has been described using the reflective display device 1 including the TFT 12 on the drive substrate 10 side as an example. For example, as illustrated in FIG. Only 15 may be formed. In the reflective display device 3 shown in FIG. 6, a driving substrate 10 provided with a plurality of pixel electrodes extending in the Y-axis direction, for example, on a support base 11, and a counter electrode 22 provided on the entire surface of the support base 21. The electrophoretic element 30 is arranged between the driving substrate provided with the. The reflective display device 3 is used, for example, when displaying a fixed pattern or a single color of a dial 410 or the like in an electronic timepiece (application example 3, FIGS. 10A and 10B) described later.

Next, a modification of the above embodiment will be described. In addition, the same code | symbol is attached | subjected to the component corresponding to the said reflection type display apparatus 1, and description is abbreviate | omitted.

<2. Modification>
FIG. 7 illustrates a cross-sectional configuration of a reflective display device (reflective display device 4) according to a modification of the above embodiment. The reflective display device 4 is used as, for example, a liquid crystal panel included in a projection display device such as an electronic book described later or a projector. This modification differs from the above embodiment in that the liquid crystal element 50 is used as a display element. The liquid crystal element 50 corresponds to a specific example of the reflective display element of the present disclosure. FIG. 7 schematically shows the configuration of the reflective display device 4 and may differ from actual dimensions and shapes.

For example, as shown in FIG. 7, the reflective display device 4 includes a drive substrate 10 and a counter substrate 20 arranged to face each other with a liquid crystal element 50 interposed therebetween, and has a display surface on the counter substrate 20 side. ing.

For example, the driving substrate 10 has a TFT 12, a protective layer 13, a planarization insulating layer 14, a pixel electrode 15, a protective layer 17, and an alignment film 18 formed in this order on one surface of a support base 11. For example, the TFT 12 and the pixel electrode 15 are divided and formed in a matrix or segment according to a pixel pattern or the like. The pixel electrode 15 is formed of a reflective metal material such as gold (Au), silver (Ag), or copper (Cu), for example, as in the above embodiment. Thereby, the light incident from the counter substrate 20 side is reflected by the pixel electrode 15 and emitted to the counter substrate 20 side (display surface side).

The protective layer 17 is for suppressing the corrosion of the pixel electrode 15. The protective layer 17 is made of an inorganic material that is chemically more stable than the material forming the alignment films 18 and 26, such as silicon oxide or silicon nitride. The thickness of the protective layer 17 is, for example, 30 nm to 70 nm. The protective layer 17 is preferably formed by a method that is chemically more stable than the vapor deposition method, such as a CVD method or a sputtering method.

The alignment film 18 is for controlling the alignment of the liquid crystal element 50, and is made of, for example, an organic material such as polyimide or an inorganic material such as silicon oxide. The thickness of the alignment film 18 is, for example, 120 nm to 360 nm. The alignment film 18 is formed by, for example, a vapor deposition method. The surface shape of the film formation region of the alignment film 18 is, for example, a rectangular shape substantially the same as the surface shape of the support base 11. The alignment film 26 has a similar configuration.

For example, the counter substrate 20 is formed by forming a counter electrode 22 and an alignment film 26 in this order on one surface of a support base 21. As shown in FIG. 7, the counter electrode 22 may be provided on the entire surface of the support base 21, or may be arranged in a matrix or on a segment like the pixel electrode 15. A polarizing plate 27 is provided on the back surface of the support base 21, and the wavelength conversion layer 24 is disposed on the polarizing plate 27.

The polarizing plate 27 allows only light in a certain vibration direction (polarized light) to pass therethrough.

The liquid crystal element 50 has a function of controlling the transmittance of transmitted light in accordance with the video voltage supplied through the pixel electrode 15 and the counter electrode 22. The liquid crystal element 50 is driven to display in, for example, a VA (Vertical Alignment) mode, a TN (Twisted Nematic) mode, an ECB (Electrically controlled birefringence) mode, an FFS (Fringe Field Switching) mode, or an IPS (In Plane Switching) mode. Liquid crystal.

In the present modification, the reflective display device 4 using the liquid crystal element 50 as the display element is shown. However, the technique of the present disclosure can achieve the same effects as those of the above embodiment even when the liquid crystal element 50 is used as the display element. Is obtained.

<3. Application example>
Next, application examples of the reflective display devices (reflective display devices 1 to 4) described in the above embodiments and modifications will be described. However, the configuration of the electronic device described below is merely an example, and the configuration can be changed as appropriate. The reflective display device 1 (and the reflective display devices 2 to 4) can be applied to various types of electronic devices or clothing, and the types of the electronic devices are not particularly limited.

(Application example 1)
8A and 8B show the external configuration of the electronic book. The electronic book includes, for example, a display unit 110, a non-display unit 120, and an operation unit 130. Note that the operation unit 130 may be provided on the front surface of the non-display unit 120 as illustrated in FIG. 8A, or may be provided on the upper surface as illustrated in FIG. 8B. The display unit 110 is configured by the reflective display device 1 (or the reflective display devices 2 to 4). The reflective display device 1 (and the reflective display devices 2 to 4) may be mounted on a PDA (Personal Digital Assistants) having the same configuration as the electronic book shown in FIGS. 8A and 8B.

(Application example 2)
FIG. 9 shows the appearance of a tablet personal computer. The tablet personal computer has, for example, a touch panel unit 310 and a housing 320, and the touch panel unit 310 is configured by the reflective display device 1 (or the reflective display devices 2 to 4).

(Application example 3)
The reflection type display device 1 (and the reflection type display devices 2 to 4) are applied as a so-called wearable terminal to a part of clothing such as a watch (watch), bag, clothes, hat, glasses and shoes. Is also possible. Below, an example of such an electronic device integrated with clothing is shown.

FIG. 10A and FIG. 10B represent the appearance of an electronic timepiece (a wristwatch integrated electronic device). The electronic timepiece has a dial (character information display portion) 410 and a band portion (color pattern display portion) 420, for example, and these dial 410 and band portion 420 are connected to the reflective display device 1 ( Alternatively, it includes a reflection type display device 2-4). For example, various characters and designs are displayed on the dial plate 410 as shown in FIGS. 10A and 10B by display driving using the above-described electrophoretic element. The band unit 420 is a part that can be attached to, for example, an arm. By using the reflective display device 1 in the band unit 420, various color patterns can be displayed, and the design of the band unit 420 can be changed from the example of FIG. 10A to the example of FIG. 10B. Can do. Electronic devices that are also useful in fashion applications can be realized.

<4. Example>
Next, examples of the present disclosure will be described in detail.

(Experimental example 1)
[Preparation of migrating particles and insulating liquid containing the same]
First, after preparing a mixed solution of 400 ml of tetrahydrofuran and 400 ml of methanol, 50 g of complex oxide fine particles (copper-iron-manganese oxide: Dipyroxide Color TM 9550 manufactured by Dainichi Seika Kogyo Co., Ltd.) are added to the solution. Ultrasonic stirring (at 25 ° C. to 35 ° C. for 30 minutes) was performed in an ultrasonic bath. Next, 40 ml of 28% aqueous ammonia was added dropwise to the dispersion of the composite oxide fine particles over 30 minutes, and then a solution of 10 g of preneact KR-TTS (manufactured by Ajinomoto Fine Techno Co., Ltd.) in 80 ml of tetrahydrofuran was added over 30 minutes. And dripped. Subsequently, the temperature of the ultrasonic bath was raised to 60 ° C. and held for 3 hours, and then cooled to room temperature, followed by centrifugation and decantation. Subsequently, the precipitate after decantation was redispersed in a mixed solvent of tetrahydrofuran and methanol (volume ratio of 1: 1), followed by centrifugation and decantation. The precipitate obtained by repeating this washing operation three times was dried overnight in a vacuum oven at 70 ° C. As a result, black electrophoretic particles coated with a negatively charged dispersing group in the insulating liquid were obtained.

After preparing the migrating particles, 6 g of long-chain alkyl succinic anhydride as a dispersant was dissolved in 94 g of insulating liquid to prepare solution A. 1 g of the migrating particles was added to 9 g of this solution A, and after ultrasonic dispersion, centrifugation and decantation were performed, and the dispersion was again dispersed in the insulating liquid. This operation was repeated three times, so that the electrophoretic particle component in the obtained dispersion was adjusted to 10% by weight. Next, 49.6 g of the insulating liquid, 0.25 g of the basic additive alkylamine, and 0.12 g of the acidic additive are added to 50 g of the solution B and stirred, and the migrating particles, the acidic additive, and the basic additive are respectively added. An insulating liquid containing 0.4 mmol (acidic additive) and 1.75 mmol (basic additive) was obtained.

[Preparation of porous layer]
First, titanium oxide having an average primary particle size of 250 nm was prepared as non-electrophoretic particles, which was mixed in tetrahydrofuran in which a carboxylic acid anionic surfactant A was dissolved, and stirred for 1 hour using a paint shaker. . Next, the mixture was centrifuged (5000 rpm for 10 minutes), the solvent was removed by decantation, washed 3 times, and dried overnight at 70 ° C. As a result, titanium oxide coated with a carboxylic acid anionic surfactant A was obtained. This titanium oxide (non-electrophoretic particle) is designated as T-1.

Next, polymethyl methacrylate (PMMA) was used as a constituent material of the fibrous structure. After 13 g of this polymethyl methacrylate was dissolved in 87 g of N, N′-dimethylformamide, 30 g of T-1 as non-electrophoretic particles was added to 70 g of this solution and mixed with a bead mill. As a result, a spinning solution for forming a fibrous structure was obtained. Subsequently, a counter electrode and partition walls were formed on the support substrate, and then spinning was performed using this spinning solution to produce a porous layer. Specifically, the spinning solution was put into a syringe, and spinning was performed on the counter substrate. Spinning was performed using an electrospinning apparatus (NANON manufactured by MEC Co., Ltd.).

[Bonding of drive substrate and counter substrate]
Next, an insulating liquid containing migrating particles was injected into the partition wall designed to a height of 15 μm together with the porous layer. Since the partition wall has a structure in which one side is open, the opening side was closed with a drive substrate coated with a seal layer, and the end surface portion was sealed with an ultraviolet curable resin. Finally, a wavelength conversion layer (Hitachi Chemical Co., Ltd. wavelength conversion film WCP) was attached to the surface of the counter substrate as a functional layer, to produce a display device serving as Sample 1 (Experimental Example 1).

(Experimental example 2)
In this experiment, Sample 2 was prepared using the same method as in Experimental Example 1 except that a wavelength conversion layer (wavelength conversion film Rayclaire manufactured by Nitto Denko Corporation) was used as the functional layer.

(Experimental example 3)
In this experiment, instead of the wavelength conversion layer, a film that scatters the wavelength in the ultraviolet region (ultraviolet scattering film; protective film PT7-25GB1 manufactured by Oike Kogyo Co., Ltd.) as a functional layer was provided on the surface of the counter substrate. Sample 3 was prepared using the same method as in Experimental Example 1.

(Experimental example 4)
Sample 4 of this experiment was prepared without providing anything on the surface of the counter substrate. Sample 4 has no UV countermeasures and serves as a reference for the evaluation of Experimental Examples 1 to 3.

(Evaluation)
The reflection type display devices (samples 1 to 4) were subjected to light resistance test evaluation and reflectance evaluation using the following methods. First, as a reflectance evaluation, samples 1 to 4 were set in an ultraviolet-visible spectrophotometer V-560 and an integrating sphere unit ILV-471 manufactured by JASCO Corporation, and the reflectance in the visible region was measured. Subsequently, as a light resistance test evaluation, each of samples 1 to 4 was set on a sun test XLS manufactured by Toyo Seiki Co., Ltd., and CIE85 (Table 4) was irradiated as a standard sunlight spectral distribution including ultraviolet rays at an illuminance of 765 W / m 2 for 24 H. Samples 1 to 4 were visually observed. Table 1 summarizes the types of functional layers provided on the surface of the counter substrate of Samples 1 to 4, the reflectance, and the state after the light resistance test.

In sample 4 in which the functional layer was not provided on the surface of the counter substrate, yellowing was observed in the constituent members (for example, a porous layer and an insulating liquid) of the electrophoretic element after the counter test. In contrast, in Samples 1 to 3 in which a functional layer that converts or scatters the wavelength of ultraviolet light was provided on the surface of the counter substrate, yellowing was not confirmed in the constituent members of the electrophoretic element after the counter test. However, in the sample 3 in which the ultraviolet scattering film was provided as the functional layer, the reflectance was reduced as compared with the

samples

1 and 2 in which the wavelength conversion layer was provided as the functional layer. Further, when the reflectances of Sample 4 and

Samples

1 and 2 were compared,

Samples

1 and 2 obtained reflectances equivalent to or higher than Sample 4 in which nothing was provided on the surface of the counter substrate. From the above, by providing a wavelength conversion layer that converts the wavelength of the non-visible region into the wavelength of the visible region on the display surface side of the display element constituting the reflective display device, light resistance, specifically, Was found to improve the resistance to ultraviolet rays. It was also found that the reflectance can be maintained or improved.

As described above, the present disclosure has been described with reference to the embodiment and the modification. However, the present disclosure is not limited to the aspect described in the embodiment, and various modifications can be made. For example, in the above embodiment, the electrophoretic element 30 is described as a microcup type electrophoretic element. However, the electrophoretic element 30 is not limited to this, and a so-called microcapsule type electrophoretic element or twist ball type electrophoretic element is used. It may be used.

In addition, the technology of the present disclosure can be applied to all display devices including a reflective display element, and the reflective display elements other than the electrophoretic element 30 and the liquid crystal element 50 described in the above embodiments, For example, the present invention can be applied to a display device using an electrochromic (EC) element.

Furthermore, it is not necessary to provide all the constituent elements described in the above embodiment, and other constituent elements may be included. Furthermore, the materials and thicknesses of the components described above are examples, and are not limited to those described.

In addition, the effect described in this specification is an illustration to the last, and is not limited, Moreover, there may exist another effect.

In addition, this indication can also take the following structures.
(1)
A reflective display element;
A reflective display device comprising: a wavelength conversion layer that is disposed closer to the display surface than the reflective display element and converts a wavelength in a non-visible region into a wavelength in a visible region.
(2)
The said wavelength conversion layer is a reflection type display apparatus as described in said (1) which converts the wavelength of an ultraviolet region into the wavelength of a visible region.
(3)
The reflective display device according to (1) or (2), wherein the wavelength conversion layer includes a phosphor material.
(4)
The reflection type display device according to any one of (1) to (3), wherein the wavelength conversion layer converts a wavelength of 300 nm to less than 400 nm into a wavelength of 400 nm to 700 nm.
(5)
The reflective display element includes a first substrate and a second substrate disposed to face each other, the first substrate is disposed on the display surface side, and the wavelength conversion layer is formed on the second substrate of the first substrate. The reflective display device according to any one of (1) to (4), wherein the reflective display device is disposed on a surface opposite to a surface facing the substrate.
(6)
Furthermore, the reflection type display device according to any one of (1) to (5), further including an antireflection layer on the display surface side of the wavelength conversion layer.
(7)
The reflective display device according to any one of (1) to (6), wherein the reflective display element is an electrophoretic element, an electrochromic element, or a liquid crystal element.
(8)
A display device,
The display device
A reflective display element;
An electronic device having a wavelength conversion layer that is disposed closer to the display surface than the reflective display element and converts a wavelength in a non-visible region into a wavelength in a visible region.

This application claims priority on the basis of Japanese Patent Application No. 2016-052613 filed on March 16, 2016 at the Japan Patent Office. The entire contents of this application are hereby incorporated by reference. Incorporated into.

Those skilled in the art will envision various modifications, combinations, subcombinations, and changes, depending on design requirements and other factors, which are within the scope of the appended claims and their equivalents. It is understood that

Claims

A reflective display element;
A reflective display device comprising: a wavelength conversion layer that is disposed closer to the display surface than the reflective display element and converts a wavelength in a non-visible region into a wavelength in a visible region.
The reflection type display device according to claim 1, wherein the wavelength conversion layer converts a wavelength in an ultraviolet region into a wavelength in a visible region.
The reflection type display device according to claim 1, wherein the wavelength conversion layer includes a phosphor material.
The reflective display device according to claim 1, wherein the wavelength conversion layer converts a wavelength of 300 nm or more and less than 400 nm into a wavelength of 400 nm or more and 700 nm or less.
A first substrate and a second substrate disposed opposite to each other with the reflective display element interposed therebetween;
The first substrate is disposed on the display surface side,
2. The reflective display device according to claim 1, wherein the wavelength conversion layer is disposed on a surface of the first substrate opposite to a surface facing the second substrate.
The reflective display device according to claim 1, further comprising an antireflection layer on the display surface side of the wavelength conversion layer.
The reflective display device according to claim 1, wherein the reflective display element is an electrophoretic element, an electrochromic element, or a liquid crystal element.
A display device,
The display device
A reflective display element;
An electronic device having a wavelength conversion layer that is disposed closer to the display surface than the reflective display element and converts a wavelength in a non-visible region into a wavelength in a visible region.