JP5906749B2 - Display device, display device manufacturing method, and electronic apparatus - Google Patents

Description

  The present invention relates to a display device, a method for manufacturing the display device, and an electronic apparatus.

For example, an electrophoretic display using particle electrophoresis is known as an image display unit of electronic paper (see, for example, Patent Document 1). The electrophoretic display has excellent portability and power saving, and is particularly suitable as an image display unit for electronic paper.
The electrophoretic display has a pair of electrodes arranged opposite to each other and a display layer provided between them, and the display layer includes, for example, positively charged white particles and negatively charged black particles. Are dispersed in a liquid phase dispersion medium. Such an electrophoretic display is configured to display a desired image by applying a voltage between a pair of electrodes and causing white particles and black particles to migrate in a desired direction.

By the way, when a display device equipped with such an electrophoretic display is stood up, that is, when the display surface is set to be parallel to the vertical direction, white particles or black particles may move vertically downward by their own weight. There is. When the particles move in this way, the displayed image is disturbed.
Also, such a display device is often provided with a partition that defines a moving space for white particles and black particles. However, when the arrangement density of the partition walls is lowered, the rigidity of the display device is relatively lowered. Therefore, there is a problem that the displayed image is disturbed when the display device is bent.

JP 2010-44114 A

  An object of the present invention is to provide a display device excellent in mechanical strength while reducing deterioration in display characteristics, a method of manufacturing a display device capable of efficiently manufacturing the display device, and a highly reliable electronic device including the display device. To provide equipment.

The above object is achieved by the present invention described below.
The display device of the present invention includes a first substrate provided on the display surface side,
A second substrate disposed opposite the first substrate;
A display layer provided between the first substrate and the second substrate,
The display layer includes
A first fiber layer provided on the first substrate side and including an aggregate of fibers;
A dispersion in which at least one kind of positively or negatively charged particles is dispersed in a dispersion medium;
And air bubbles.
Thereby, it is possible to obtain a display device having excellent mechanical strength while reducing deterioration of display characteristics. Further, even when the volume of the dispersion liquid expands due to heat, the bubbles serve as a buffer material, and the pressure on the display device due to the volume expansion can be relieved.

In the display device of the present invention, it is preferable that the relationship of A / B ≦ 1 is satisfied when the volume of the bubbles is A [cm ³ ] and the volume of the dispersion is B [cm ³ ].
Thereby, mechanical strength can be made more excellent, without preventing movement of particles.
In the display device of the present invention, it is preferable that the bubbles are made of an inert gas.
Thereby, the influence which the gas contained in a bubble has with respect to a dispersion liquid can be made small.

In the display device of the present invention, the humidity in the bubbles is preferably 10% RH or less.
Thereby, aggregation of the charged particles due to moisture can be prevented, and the influence of moisture on the dispersion can be made smaller.
In the display device according to the aspect of the invention, it is preferable that the first fiber layer includes a space in which the particles can enter.
Thereby, the particles are sufficiently close to the display surface, and the color exhibited by the particles can be clearly displayed.

In the display device according to the aspect of the invention, it is preferable that movement of the particles due to their own weight is restricted by being held in the space of the first fiber layer.
Accordingly, for example, even when the display device is placed in a posture such that the display surface is parallel to the vertical direction, it is possible to prevent the image displayed on the display device from being disturbed.
In the display device of the present invention, the fibers are preferably inorganic fibers.
As a result, the fiber has a relatively high hardness, and the first fiber layer can easily maintain its sparse shape. As a result, the effect of retaining the particles can be reliably maintained over a long period of time.

In the display device according to the aspect of the invention, it is preferable that the fibers have conductivity.
As a result, an electric field acts on every corner of the first fiber layer, and the amount of particles that can be held increases, so that the color exhibited by the particles is highlighted and displayed with high contrast. . In addition, since the electric field concentrates on the fiber, the electric field strength can be increased, so that the electrophoretic properties (response speed, etc.) of the particles can be improved.

In the display device according to the aspect of the invention, it is preferable that the first fiber layer is formed by binding the fibers with an organic binder.
Thereby, the aggregate of fibers is reliably fixed to the first substrate via the organic binder. Moreover, since a softness | flexibility and a stretching property are provided to a 1st fiber layer by an organic binder, fixation of fibers becomes difficult to cancel | release and it becomes easy to maintain the shape as a 1st fiber layer. As a result, even when the display device is curved, for example, the first fiber layer is rich in shape followability.

In the display device according to the aspect of the invention, it is preferable that the organic binder has at least one of a thermoplastic resin and a thermally crosslinkable resin as a main component.
Thereby, the organic binder becomes rich in flexibility.
In the display device of the present invention, the display layer further includes a partition wall provided so as to surround the dispersion.
It is preferable that the first fiber layer and the partition wall are fixed.
Thereby, the mechanical strength of the display device can be further increased.

In the display device according to the aspect of the invention, it is preferable that the display layer further includes a second fiber layer provided on the second substrate side and including an aggregate of fibers.
Thereby, since a bubble does not touch both the 1st board | substrate and the 2nd board | substrate, the further fall prevention of the display characteristic of a display apparatus can be aimed at. Further, the mechanical strength of the display device can be further improved.

The display device manufacturing method of the present invention is a manufacturing method of manufacturing the display device of the present invention,
Depositing the first fiber layer on one surface of the first substrate;
Supplying the dispersion on the second substrate;
A step of obtaining a laminate while forming the bubbles by superimposing the first substrate and the second substrate so that the first fiber layer and the dispersion face each other;
A step of bonding the first substrate and the second substrate by pressing the laminated body in the thickness direction while heating.
Thereby, it is possible to efficiently manufacture a display device having excellent mechanical strength while reducing deterioration of display characteristics.
An electronic apparatus according to the present invention includes the display device according to the present invention.
Thereby, the electronic device excellent in reliability is obtained.

It is sectional drawing which shows 1st Embodiment of the display apparatus of this invention. It is a top view (top view) of the display apparatus shown in FIG. It is sectional drawing explaining the manufacturing method of the display apparatus shown in FIG. It is sectional drawing explaining the manufacturing method of the display apparatus shown in FIG. It is sectional drawing which shows 2nd Embodiment of the display apparatus of this invention. It is a top view which shows the wall part of 3rd Embodiment of the display apparatus of this invention. It is a top view which shows the wall part of 3rd Embodiment of the display apparatus of this invention. It is a perspective view which shows embodiment at the time of applying the electronic device of this invention to electronic paper. It is a figure which shows embodiment at the time of applying the electronic device of this invention to a display.

Hereinafter, a display device, a method for manufacturing the display device, and an electronic apparatus according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
<First Embodiment>
≪Display device≫
First, a first embodiment of the display device of the present invention will be described.

  1 is a cross-sectional view showing a first embodiment of the display device of the present invention, FIG. 2 is a plan view (top view) of the display device shown in FIG. 1, and FIGS. 3 and 4 are views of the display device shown in FIG. It is sectional drawing explaining a manufacturing method. In the following description, for convenience of explanation, the upper side in FIGS. 1, 3 and 4 will be described as “upper” and the lower side will be described as “lower”. Further, as shown in FIG. 1, two directions orthogonal to each other in a plan view of the display device are referred to as “X direction” and “Y direction”. In FIG. 2, illustration of the substrate 11 and the first fiber layer 62 is omitted for convenience of explanation.

A display device 20 (display device of the present invention) shown in FIG. 1 is an electrophoretic display device that displays a desired image using particle migration. The display device 20 includes a display sheet (front plane) 21 and a circuit board (back plane) 22.
As shown in FIG. 1, the display sheet 21 is provided under a substrate (first substrate) 11 including a flat base 1 and a first electrode 3 provided on the lower surface of the base 1, and below the substrate 11. And a wall portion (partition wall) 92 that divides the display layer 400 into a plurality of sections. In such a display sheet 21, the upper surface of the substrate 11 constitutes the display surface 111. The display layer 400 is provided on the substrate 11 side, and includes a first fiber layer 62 including an aggregate of fibers 620, a dispersion liquid 100 in which particles B and W are dispersed in the dispersion medium 7, and bubbles 8. doing.

On the other hand, the circuit board 22 is a board (second board) 12 provided with a flat base 2 and a plurality of second electrodes 4 provided on the upper surface of the base 2, and is not shown provided on the board 12. Circuit.
The circuit includes, for example, TFTs (switching elements) arranged in a matrix, gate lines and data lines formed corresponding to the TFTs, a gate driver that applies a desired voltage to the gate lines, and a desired data line. A data driver for applying the voltage of the gate driver, and a control unit for controlling the driving of the gate driver and the data driver.

Hereinafter, the structure of each part is demonstrated sequentially.
(substrate)
The base 1 and the base 2 are each composed of a sheet-like (flat plate) member, and have a function of supporting and protecting each member disposed therebetween. Each of the base portions 1 and 2 may be either flexible or hard, but is preferably flexible. By using the bases 1 and 2 having flexibility, it is possible to obtain a display device 20 having flexibility, that is, for example, a display device 20 useful in constructing electronic paper.

  In the case where the bases 1 and 2 are flexible, the constituent materials include highly transparent glass or resin. Examples of the resin include polyesters such as PET (polyethylene terephthalate) and PEN (polyethylene naphthalate), polyolefins such as polyethylene, modified polyolefins, cyclic olefins (COP), polyamides, thermoplastic polyimides, polyethers, polyether ether ketones, and polycarbonates. (PC), polyurethane-based, chlorinated polyethylene-based various thermoplastic elastomers, etc., or copolymers, blends, polymer alloys, etc. mainly comprising these, including one or more of these It can be used by mixing.

  The average thicknesses of the bases 1 and 2 are appropriately set depending on the constituent materials, applications, and the like, and are not particularly limited. However, when having flexibility, it is preferably about 20 μm to 500 μm, preferably 25 μm to 250 μm. It is more preferable that the thickness is about 50 μm or more and 200 μm or less. Thereby, size reduction (especially thickness reduction) of the display apparatus 20 can be achieved, aiming at harmony with the softness | flexibility and intensity | strength of the display apparatus 20. FIG.

  A film-like first electrode 3 and second electrode 4 are provided on the surfaces of the bases 1 and 2 on the display layer 400 side, that is, on the lower surface of the base 1 and the upper surface of the base 2, respectively. In the present embodiment, the first electrode 3 is a common electrode, and the second electrode 4 is an individual electrode (pixel electrode connected to a TFT) divided in a matrix in the X and Y directions. . In the display device 20, one second electrode 4 is arranged in one region surrounded by a wall portion 92 to be described later, and a region in which one second electrode 4 and the first electrode 3 overlap ( A region surrounded by the wall portion 92) constitutes one pixel. For this reason, by appropriately controlling the voltage applied to the second electrode 4, the color emitted by each pixel section can be controlled, and an image visually recognized from the display surface 111 can be freely generated.

The constituent materials of the electrodes 3 and 4 are not particularly limited as long as they are substantially conductive, for example, metal materials such as gold, silver, copper, aluminum or alloys containing these, carbon black, In a carbon-based material such as graphene, carbon nanotube, and fullerene, an electroconductive polymer material such as polyacetylene, polyfluorene, polythiophene, or a derivative thereof, or a polymer such as polyvinyl alcohol or polycarbonate, NaCl, Cu (CF ₃ SO ₃ ) Conductive materials such as ion conductive polymer materials in which ionic substances such as ₂ are dispersed, indium oxide (IO), indium tin oxide (ITO), fluorine-doped tin oxide (FTO), zinc oxide (ZnO), etc. Examples include various conductive materials such as oxide materials, and one or more of these It can be used in conjunction seen.
The average thicknesses of the electrodes 3 and 4 are appropriately set depending on the constituent material, application, etc., and are not particularly limited, but are preferably about 0.01 μm to 10 μm, preferably about 0.02 μm to 1 μm. It is more preferable from the viewpoint of balance between conductivity and transparency.

  Here, among the bases 1 and 2 and the electrodes 3 and 4, the base and the electrode arranged on the display surface 111 side are each transparent, that is, substantially transparent (colorless and transparent, colored and transparent). Or translucent). In the present embodiment, since the upper surface of the substrate 11 constitutes the display surface 111, at least the base 1 and the first electrode 3 are substantially transparent. Thereby, the image displayed on the display device 20 can be easily recognized visually from the display surface 111 side.

(Sealing part)
Between the board | substrate 11 and the board | substrate 12, the sealing part (sealing part) 5 is provided along those edge parts. The display layer 400 is hermetically sealed by the sealing portion 5. As a result, it is possible to prevent moisture from entering the display device 20, prevent aggregation of the particles A due to moisture, and more reliably prevent deterioration in display performance of the display device 20.

The constituent material of the sealing portion 5 is not particularly limited. For example, thermoplastic resins such as acrylic resins, urethane resins, and olefin resins, epoxy resins, melamine resins, phenol resins, and silicone resins. Various resin materials such as a thermosetting resin can be used, and one or more of these can be used in combination.
Further, the height of the sealing portion 5 is not particularly limited, but is preferably about 5 μm or more and 50 μm or less. By setting the height of the sealing portion 5 within the above range, the particles A can move in a short time according to the electric field, and the particles A can be prevented from being seen through in a non-display state.

(Wall)
As shown in FIGS. 1 and 2, the display layer 400 is divided into a plurality of compartments by a wall portion 92, and each compartment contains a dispersion 100 and bubbles 8 as described later. . In the present embodiment, the wall 92 has a lattice shape as shown in FIG. The wall portion 92 is fixed to the base portion 2.

The surface of the wall 92 is preferably subjected to various water repellent treatments such as a fluorocarbon plasma treatment. Thereby, as will be described later, the display device 20 can be manufactured more easily, and the display device 20 capable of exhibiting more excellent display characteristics and reliability can be obtained.
The constituent material of the wall portion 92 is not particularly limited. For example, various thermoplastics such as epoxy resin, acrylic resin, phenol resin, urea resin, melamine resin, polyester (unsaturated polyester), polyimide, silicone resin, and urethane resin. A resin or a thermosetting resin can be used, and one or more of these can be mixed and used.

The height of the wall portion 92 is not particularly limited, but is preferably about 5 μm or more and 50 μm or less. By setting the height of the wall portion 92 within the above range, the particles B (or particles W) can move in a short time according to the electric field, and the particles A are prevented from being seen through in the non-display state. be able to.
The average width of the wall portion 92 is appropriately set in consideration of mechanical strength required for the wall portion 92, but is preferably about 1 μm or more and 5 μm or less. And it is preferable that the aspect ratio (average height / average width) of the wall part 92 is about 1-50.

In the present embodiment, the cross-sectional shape of the wall 92 is an inversely tapered shape in which the width gradually decreases from the substrate 12 toward the substrate 11 side. Thereby, the visibility of the image can be improved, and the tip of the wall 92 can bite into the first fiber layer 62 described later, and the adhesion between the substrate 11 and the wall 92 can be improved. In addition, it is not limited to this shape, For example, a rectangle (rectangle) may be sufficient.
Moreover, the cross-sectional shape of the wall part 92 may not be constant over the whole, and a partially different shape may be sufficient as it.

(First fiber layer)
In the display layer 400, as shown in FIG. 1, the 1st fiber layer 62 is provided in the board | substrate 11 side. The first fiber layer 62 includes a collection of fibers 620. Specifically, the first fiber layer 62 is formed by binding the first fibers 620 with an organic binder. The first fiber layer 62 has a large amount of space formed therein, and is filled with the dispersion liquid 100 so as to penetrate into the inside.

  Further, since the first fiber layer 62 has a large surface area, the particles B and the particles W in the dispersion 100 enter the inside or the surface thereof and are easily held at the position. When the particles B and the particles W enter and are held in the first fiber layer 62, the particles B and the particles W are sufficiently close to the display surface 111, and the color exhibited by the particles A is clearly displayed. In addition, the particles B and the particles W can be prevented from settling due to their own weight, and the particles B and the particles W can be prevented from moving to unintended positions. As a result, for example, even when the display surface 111 is in a posture parallel to the vertical direction, it is possible to prevent the image displayed on the display device 20 from being disturbed.

Moreover, since the 1st fiber layer 62 mainly consists of the aggregate | assembly of the fiber 620, it is hard to inhibit transmitted light. For this reason, when an image formed by particles B and particles W, which will be described later, is viewed through the first fiber layer 62, the image is hardly disturbed. Therefore, clear display is possible.
For the above reason, the color exhibited by the fiber 620 is preferably transparent, light or white, and more preferably transparent.

  In addition to the above function, the first fiber layer 62 also has a function of preventing the gas contained in the bubbles 8 from spreading toward or in contact with the lower surface of the substrate 11. If the gas contained in the bubbles 8 spreads in close proximity to or in contact with the substrate 11, it exists between the particle B or particle W and the first electrode 3, and the particle B and the particle are transferred to the first electrode 3. W cannot sufficiently approach and cannot be held. That is, the bubble 8 becomes a display defect, and a clear display cannot be performed and the image is disturbed.

The first fiber layer 62 is prevented from invading the gas in the bubbles 8 due to surface tension and the like, but the fibers 620 and the organic binder constituting the first fiber layer 62 In contrast, by performing lyophilic treatment (for example, O ₂ plasma treatment or the like), the permeability of the dispersion liquid 100 can be improved, and the gas in the bubbles 8 enters the first fiber layer 62. This can be prevented more effectively.

  The average fiber length of the fibers 620 is not particularly limited, but is preferably about 0.1 μm to 100 μm, and more preferably about 1 μm to 80 μm. The average fiber diameter of the fibers 620 is not particularly limited, but is preferably about 0.01 μm or more and 10 μm or less, and more preferably about 0.1 μm or more and 5 μm or less. By setting the fiber length and the fiber diameter of the fiber 620 within the above ranges, the particle B or the particle B due to convection of the dispersion that occurs due to a change in the temperature of gravity or outside air while securing a sufficient space for the particle B or the particle W to enter and exit Alternatively, the particles B or W can be smoothly electrophoresed by the action of an electric field while securing the retentivity by preventing the re-peeling of the particles W.

The fiber length and the fiber diameter of the fiber 620 are the maximum length and the maximum diameter of the projected image of the fiber 620 on the observation image of the cross section of the first fiber layer 62, and the average value of each is 100 pieces. The fiber length and fiber diameter measured for the fiber 620 are averaged.
In addition, by making the fiber diameter particularly shorter than the lower limit of the wavelength of visible light (for example, 400 nm), transparency can be secured as the first fiber layer 62 even if the fiber 620 itself is not transparent.

  The average thickness of the first fiber layer 62 is not particularly limited, but is preferably about 0.1 μm to 20 μm, and more preferably about 0.2 μm to 10 μm. By setting the average thickness of the first fiber layer 62 within the above range, the first fiber layer 62 has sufficient mechanical strength and sufficient retention of the particles B or W, while maintaining the first thickness. When an electric field is applied to the particles B or W held on the fiber layer 62, the particles B or W can be smoothly electrophoresed. In addition, sufficient transparency of the first fiber layer 62 can be ensured. That is, the mechanical strength and the retention of the particles B or W can be highly compatible with the migration and transparency of the particles B or W.

The first fiber layer 62 is uncharged, that is, not substantially charged. For this reason, an electrical action (repulsion or adsorption) does not work between particles B or W described later. Therefore, the particles B or W can be smoothly moved in the dispersion medium 7, and excellent display characteristics, particularly excellent response speed can be exhibited.
The first fiber layer 62 includes an aggregate of fibers 620. The density (occupancy) of the fibers 620 in the first fiber layer 62 is preferably 50% by volume to 99% by volume, more preferably It is set as 60 volume% or more and 95 volume% or less. With such a density, the mechanical strength of the first fiber layer 62 and the retention of the particles B or W, the migration of the particles B or W, and the transparency of the first fiber layer 62 are highly compatible. be able to.

  For the fibers 620, for example, organic fibers such as resin fibers, glass fibers, ceramic fibers, carbon fibers, and inorganic fibers such as metal fibers are used alone or as a mixture of a plurality of types. Among these, examples of the resin fiber include polyethylene fiber, polyester fiber, vinylon fiber, nylon fiber, and acrylic fiber. Examples of the glass fiber include borosilicate glass fiber and quartz glass fiber. Moreover, as a ceramic fiber, a potassium titanate fiber, a tin oxide fiber, an alumina fiber, a silica fiber etc. are mentioned, for example. Examples of carbon fibers include PAN-based carbon fibers and carbon nanotubes. Moreover, as a metal fiber, an aluminum whisker, a silver whisker, etc. are mentioned, for example.

In addition, as the fiber 620, an inorganic fiber is particularly preferably used. Since the inorganic fiber has a relatively high hardness, the first fiber layer 62 can easily maintain its sparse shape. Therefore, it is possible to obtain the display device 20 that can surely exhibit the effect of the first fiber layer 62 described above over a long period of time.
In addition, the first fiber layer 62 may be one in which the fibers 620 are simply gathered together, but is preferably formed by binding with an organic binder so that the fibers 620 are fixed to each other. Note that the organic binder also has a function of fixing the aggregate of fibers 620 to the substrate 11 and the wall portion 92. Furthermore, when the constituent material of the fibers 620 is a material having high hardness, the first fiber layer 62 can be provided with flexibility and stretchability, so that the fixation between the fibers 620 is difficult to be released. It is easy to maintain the shape as one fiber layer 62. Even when the display device 20 is curved, the first fiber layer 62 is rich in shape following ability.

  As the constituent material of the organic binder, materials that are relatively easy to soften are preferably used. For example, urethane resin, urea resin, ester resin, ether resin, olefin resin such as polyethylene and polypropylene, ethylene vinyl acetate copolymer (EVA) ) And ethylene methyl methacrylate copolymer (EMMA), ethylene cyclic olefin copolymer (COC resin), thermoplastic resins such as acrylic resin and butadiene elastomer, epoxy resin, isocyanate resin, cyanoacrylate Examples thereof include heat-crosslinkable resins such as resins, melamine resins, and phenol resins, and those containing one or a mixture of two or more of these as a main component are used. Such an organic binder is rich in flexibility.

In addition, as a subcomponent of an organic binder, a plasticizer, a lubricant, an antioxidant, a dispersing agent, etc. are added as needed.
In addition, the elastic modulus at 25 ° C. of the organic binder is preferably 0.01 MPa or more and 1000 MPa or less, and more preferably 0.1 MPa or more and 500 MPa or less. Thereby, sufficient flexibility and stretchability can be imparted to the first fiber layer 62.

Moreover, as the fiber 620, one having conductivity is preferably used. By using such fibers 620, an electric field acts on every corner of the first fiber layer 62, so that the particles B or W can be reliably held in the entire first fiber layer 62. Further, since the amount of particles B or W that can be held increases, the color exhibited by the particles B or W is easily emphasized, and a high-contrast display is possible. Furthermore, since the electric field concentrates on the fibers 620 and the electric field intensity applied to the particles B or W can be increased, the electrophoretic properties (response speed, etc.) of the particles B or W can be increased.
Examples of the conductive fibers 620 include those in which the fibers themselves have conductivity, and those in which a conductive coating is formed on the fibers.
The fiber 620 (first fiber layer 62) is bonded and fixed to the upper surface of the partition wall 92. Thereby, the mechanical strength of the display device 20 can be further increased.

(Dispersion)
Next, the dispersion liquid 100 will be described.
In the display device 20, as described above, the display layer 400 is divided into a plurality of sections by the wall portion 92, and each section is filled with the dispersion liquid 100.
The dispersion liquid 100 is obtained by dispersing in a dispersion medium 7 particles B that are positively charged and exhibit a black color tone, and particles W that are negatively charged and exhibit a white color tone. By including the white particles W, the contrast of the displayed image can be improved.

  Note that the particles dispersed in the dispersion liquid 100 are not limited to the above color, and a color image can be displayed by using particles such as yellow, magenta, and cyan. In the case of monochrome display, only black particles may be used. In the case of color display, in addition to the black particles, particles of three colors (yellow, magenta, and cyan) are divided for each pixel. It is necessary to paint separately. Further, it is necessary to change the charge between black and other colors. For example, when black particles are positively charged, the other color particles are negatively charged.

  As the particles B and W, any particles can be used as long as they have electric charges. For example, oxide particles such as titanium oxide, zinc oxide, iron oxide, chromium oxide, zirconium oxide, silicon nitride, , Nitride particles such as titanium nitride, sulfide particles such as zinc sulfide, boride particles such as titanium boride, inorganic pigment particles such as strontium chromate, cobalt aluminate, cuprous copper, ultramarine, etc. Organic pigment particles such as quinacridone, anthraquinone, dioxazine, and perylene can be used. Alternatively, composite particles obtained by applying a pigment to the surface of resin particles made of acrylic resin, urethane resin, urea resin, epoxy resin, polystyrene, polyester, or the like can be used.

  The average particle diameter of the particles B and W is not particularly limited, but is preferably 10 nm or more and 1 μm or less, more preferably 10 nm or more and 500 nm or less, and further preferably 20 nm or more and 300 nm or less. By setting the average particle diameter of the particles B and W within the above range, it is possible to achieve both sufficient chromaticity display by the particles B and W and rapid electrophoresis of the particles B and W. As a result, both high contrast display and high response speed can be achieved.

In addition, the average particle diameter of particle | grains B and W means the volume average particle diameter measured with the dynamic light-scattering type particle size distribution measuring apparatus (For example, product name: LB-500, Co., Ltd. Horiba Ltd.).
Further, in order to prevent charging of particles B and W and aggregation between particles, positively charged materials such as amine compounds and alumina, negatively charged materials such as carboxyl groups, sulfo groups and silicon oxides on the surfaces of particles B and W, silane cups A coupling treatment such as a ring agent or a titanium coupling agent, a coating treatment such as a surfactant surface treatment, or the like may be performed.

  As the dispersion medium 7, a medium having a boiling point higher than 100 ° C. and having a relatively high insulating property is preferably used. Examples of the dispersion medium 7 include various water (eg, distilled water, pure water), alcohols such as butanol and glycerin, cellosolves such as butyl cellosolve, esters such as butyl acetate, ketones such as dibutyl ketone, Aliphatic hydrocarbons such as pentane (liquid paraffin), alicyclic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as xylene, halogenated hydrocarbons such as methylene chloride, and aromatic heterocycles such as pyridine , Nitriles such as acetonitrile, amides such as N, N-dimethylformamide, carboxylate, silicone oil or other various oils, and the like can be used alone or as a mixture.

  Among these, as the dispersion medium 7, an aliphatic hydrocarbon (liquid paraffin) or a material mainly composed of silicone oil is preferable. The dispersion medium 7 containing liquid paraffin or silicone oil as a main component is preferable because it has a high aggregation suppressing effect on the particles A. Thereby, it can prevent or suppress more reliably that the display performance of the display apparatus 20 deteriorates with time. In addition, liquid paraffin or silicone oil is preferable from the viewpoint of excellent weather resistance and high safety because it does not have an unsaturated bond.

(Bubbles)
Next, the bubble 8 will be described.
The display layer 400 includes bubbles 8 in addition to the first fiber layer 62 and the dispersion liquid 100 described above.
By providing such bubbles 8, even when the volume of the dispersion liquid 100 is expanded by heat, the bubbles serve as a buffer material, and the pressure on the display device 20 due to the volume expansion can be relieved. Further, even when external pressure is applied to the display device 20, the external pressure can be absorbed by the bubbles 8, and the mechanical strength can be made particularly excellent. In addition, since the first fiber layer 62 is provided at the same time as the bubbles 8, the bubbles 8 do not approach or come into contact with the display surface 111 side, and display characteristics are prevented from deteriorating.

As the gas contained in the bubbles 8, for example, air, oxygen, or an inert gas such as nitrogen or argon can be used. Among these, it is preferable to use an inert gas. Thereby, the influence which the gas in the bubble 8 has with respect to the dispersion liquid 100 can be made small.
Further, the humidity in the bubble 8 is preferably 10% RH or less, more preferably 1% RH or less. Thereby, by reducing the water content contained in the bubbles 8 with respect to the dispersion liquid 100, it is possible to prevent agglomeration of charged particles due to the water and to exhibit high-definition display performance.

When the volume of the bubbles 8 in the display layer 400 is A [cm ³ ] and the volume of the dispersion 100 is B [cm ³ ], it is preferable that the relationship of A / B ≦ 1 is satisfied. Thereby, the mechanical strength can be further improved without hindering the movement of the particles B or W by electrophoresis.
While the configuration of the display device 20 has been described above, such a display device 20 is driven as follows, for example. In the following description, a case where a voltage is applied to one of the plurality of second electrodes 4 illustrated in FIG. 1 will be described.

  When a voltage is applied between the first electrode 3 and the second electrode 4 so that the first electrode 3 has a negative potential and the second electrode 4 has a positive potential, the electric field generated by the voltage application is displayed on the display layer. Acts on particles B and W in 400. Then, the particles B migrate and gather on the first electrode 3 side, and the particles W migrate and gather on the second electrode 4 side. Thereby, the color which the particle | grains B exhibit on the display surface 111, ie, black, is displayed.

On the other hand, when a voltage is applied such that the first electrode 3 has a positive potential and the second electrode 4 has a negative potential, the electric field generated by the voltage application acts on the particles B and W in the display layer 400. Then, the particles B migrate and gather on the second electrode 4 side, and the particles W migrate and gather on the first electrode 3 side. Thereby, the color which the particle | grains W exhibit, ie, white, is mainly displayed on the display surface 111. FIG.
A desired image can be displayed on the display surface 111 by driving the particles B and W as described above for each pixel.

≪Method for manufacturing display device≫
Next, a method for manufacturing the display device 20 will be described.
The manufacturing method of the display device 20 includes a fiber layer forming step of forming the first fiber layer 62 on the upper surface of the substrate 11, a partition wall forming step of forming the wall portion 92 on the upper surface of the substrate 12, and the wall portion 92. A particle supplying step of supplying the dispersion liquid 100 to the region, and the substrate 11 and the substrate 12 are overlapped so that the first fiber layer 62 and the wall portion 92 are in contact with each other, thereby forming bubbles 8 in the dispersion liquid 100. And a laminate forming step for obtaining a laminate, and a joining step for joining the first fiber layer 62 and the wall portion 92 by pressing the laminate in the thickness direction while heating the laminate. . Hereinafter, each process will be described sequentially.

  [1] First, a substrate 11 shown in FIG. Next, as shown in FIG. 3B, the first fiber layer 62 is formed on the first electrode 3 of the substrate 11. The first fiber layer 62 can be formed by, for example, preparing a dispersion by dispersing fibers 620 and an organic binder in a volatile dispersion medium, applying the dispersion on the first electrode 3, and then applying a coating film. The method of drying is used. As the coating method, for example, various coating methods such as gravure coating, comma coating, lip coating, die coating, screen printing, and inkjet coating are used. For forming the first fiber layer 62, a method of forming a non-woven body obtained by gathering the fibers 620 in advance and placing the non-woven body is also used.

  Moreover, you may make it perform a hot roll process etc. after drying. When the hot roll treatment is performed, the coating film is foamed and the density of the first fiber layer 62 is decreased. Therefore, the density of the first fiber layer 62 can be controlled by adjusting the foaming amount. In particular, when the treatment is performed in a reduced pressure atmosphere, the amount of foaming on the surface of the coating film is increased, and the density of the upper part of the coating film can be relatively lowered. In the first fiber layer 62 formed in this manner, a density gradient is formed, and the particles B and W enter the first fiber layer 62 or the first fiber layer 62. The movement to escape from becomes smoother. Furthermore, since the fibers 620 easily protrude from the surface of the first fiber layer 62, the first fiber layer 62 and the partition wall 92 are more firmly fixed.

[2] On the other hand, the substrate 12 is prepared, and the wall 92 is formed on the surface on the second electrode 4 side (see FIG. 3C). As a method for forming the wall portion 92, for example, a printing method such as screen printing, an imprint method for forming irregularities with a mold, a photolithography method, or the like is used.
[3] Next, as shown in FIG. 3D, the dispersion 100 is supplied to a region surrounded by the wall 92 (hereinafter also simply referred to as a cell). At this time, as shown in FIG. 3 (d), the dispersion liquid 100 is supplied so that the liquid surface of the dispersion liquid 100 is lower than the top of the wall portion 92. Thereby, the bubble 8 is formed in the laminated body formation process mentioned later. In addition, since a suitable volume of the bubbles 8 to be formed has a certain width, the liquid level of the dispersion 100 is lower than the top of the wall 92 compared to the case where it is supplied to the top of the wall 92. If there is, a certain range can be given to the increase or decrease of the supply amount of the dispersion liquid 100. As a result, the supply accuracy of the dispersion liquid 100 can be lowered to some extent, and the productivity of the display device 20 can be improved. In addition, when the dispersion liquid 100 is supplied to the top of the wall 92, the dispersion liquid 100 overflows and the dispersion liquid 100 may be lost. However, according to the above method, the dispersion liquid 100 overflows. Can be suppressed, and loss of the dispersion 100 can be prevented. In addition, when performing color display, the dispersion liquid 100 corresponding to a different color is supplied to each adjacent cell. However, since the dispersion liquid 100 is suppressed from overflowing as described above, color mixing occurs. Can be prevented.
A method for supplying the dispersion liquid 100 is not particularly limited, and methods such as supply by a droplet discharge method and supply using a dispenser are used.

[4] Next, as shown in FIG. 4E, the substrate 11 and the substrate 12 are overlapped and bonded so that the first fiber layer 62 and the wall portion 92 are in contact with each other. By overlapping, the bubbles 8 are formed and the laminate 13 is formed.
This superposition operation is performed using, for example, a roll laminator in a gas atmosphere in the bubbles 8.

Next, pressure is applied in the thickness direction while heating the laminated body 13. Thereby, the organic binder contained in the 1st fiber layer 62, the thermoplastic resin in the wall part 92, etc. fuse | melt, and the 1st fiber layer 62 and the wall part 92 are adhere | attached. Thereafter, the laminated body 13 is cooled, so that the organic binder is solidified and the adhesion between them is completed. Further, the tip of the wall portion 92 bites into the first fiber layer 62 with the pressurization. As a result, the fixation of both based on the anchor effect is completed. That is, the first fiber layer 62 and the wall portion 92 are firmly fixed by adhesion with the organic binder and fixation due to the anchor effect.
Although it does not specifically limit as heating temperature of the laminated body 13, It is preferable that it is about 25 degreeC or more and 120 degrees C or less. Thereby, the organic binder can be melted or softened to exhibit an adhesive function, and evaporation of the dispersion medium 7 and softening of the wall portion 92 can be prevented.

[5] Next, as shown in FIG. 4F, the sealing portion 5 is formed around the display layer 400. Thereby, the display apparatus 20 is obtained.
Since a thermoplastic or thermosetting resin material is used as a constituent material of the sealing portion 5, a softened or melted material is applied and solidified or cured to apply the sealing portion 5 Is formed. For the application, for example, a syringe dispenser can be used.
According to the manufacturing method as described above, both the first fiber layer 62 and the bubbles 8 are provided, and the display device 20 having both display characteristics and mechanical strength can be efficiently manufactured.

Second Embodiment
Next, a second embodiment of the display device of the present invention will be described.
FIG. 5 is a cross-sectional view showing a second embodiment of the display device of the present invention.
Hereinafter, although 2nd Embodiment is described, it demonstrates centering around difference with embodiment mentioned above, The description is abbreviate | omitted about the same matter. In addition, the same code | symbol is attached | subjected to the structure similar to embodiment mentioned above.

The display device 20 according to the second embodiment is the same as the first embodiment except that the second fiber layer 64 different from the first fiber layer 62 is provided on the surface of the substrate 12 on the display layer 400 side. This is the same as the display device 20.
The second fiber layer 64 is provided on the upper surface of the substrate 12, and is bonded and fixed via an organic binder or the like as necessary. The configuration of the second fiber layer 64 is the same as that of the first fiber layer 62.

By providing such a second fiber layer 64, the particles B and W gathered on the substrate 12 side can also be held in the second fiber layer 64, and are not intended by the weight of the particles B and W. Movement can be suppressed. As a result, uneven distribution of the particles B and W can be prevented, and disturbance of the display image can be suppressed.
Further, the bubbles 8 can be prevented from coming into contact with the substrate 12 (second electrode 4). Thereby, it is possible to prevent or suppress the movement of the second electrode 4 from being inhibited by the gas contained in the bubbles 8.

<Third Embodiment>
Next, a third embodiment of the display device of the present invention will be described.
6 and 7 are plan views showing a wall portion of the third embodiment of the display device of the present invention.
In the following, the third embodiment will be described, but the description will focus on differences from the above-described embodiment, and description of similar matters will be omitted. In addition, the same code | symbol is attached | subjected to the structure similar to embodiment mentioned above.
Of the display device 20 according to the third embodiment, the wall 92 shown in FIG. 6 is the same as that of the first embodiment, except that the shape is different.

The wall 92 shown in FIG. 6A has a lattice shape in plan view, and the wall 92 is missing at the intersection of the wall 92 extending in the X direction and the wall 92 extending in the Y direction. It is configured to Due to the presence of such a missing part, excess dispersion liquid 100 and remaining bubbles can be discharged to the outside from this part. As a result, a highly reliable display device 20 having excellent display characteristics can be obtained.
The wall portion 92 shown in FIG. 6B has a honeycomb shape so that the pixel sections are hexagonal in plan view.
The wall portion 92 shown in FIG. 6C is configured only by the one extending in the Y direction.

On the other hand, in the display device 20 according to the third embodiment, the wall portion 92 shown in FIG. 7 is the same as the fifth embodiment except that the shape is different.
The wall portion 92 shown in FIG. 7A extends in the Y direction while reciprocating in the Y direction, and a plurality of such wall portions 92 are provided in parallel. In other words, each wall portion 92 extends in the X direction while meandering. Moreover, the wall part 92 adjacent to the one wall part 92 is satisfy | filling the mutually symmetrical relationship. As a result, the pixel space provided between the adjacent wall portions 92 has a substantially hexagonal shape.

Here, symbols Y, M, and C shown in FIG. 7A mean yellow (yellow), red (magenta), and blue (cyan), respectively. That is, the display device 20 capable of so-called full color display is obtained by filling each pixel section indicated by the symbols Y, M, and C with a dispersion liquid containing the particles Y, M, and C corresponding to the respective colors.
The wall 92 shown in FIG. 7 (b) is configured only by the one extending in the X direction, while the wall 92 shown in FIG. 7 (c) has a lattice shape in plan view, and Of the wall portion 92 extending in the Y direction, a part facing the pixel section is omitted. The symbols Y, M, and C shown in FIGS. 7B and 7C have the same meaning as the symbols in FIG. 7A. That is, so-called full-color display can be performed also by the display device 20 including the wall portion 92 shown in FIGS. 7B and 7C.

≪Electronic equipment≫
Each of the display devices 20 described above can be incorporated into various electronic devices. Specific electronic equipment includes, for example, electronic paper, electronic book, television, viewfinder type, monitor direct-view type video tape recorder, car navigation device, pager, electronic notebook, calculator, electronic newspaper, word processor, personal computer, work Examples include a station, a videophone, a POS terminal, and a device provided with a touch panel.
Of these electronic devices, an electronic paper will be described as an example for specific description.

FIG. 8 is a perspective view showing an embodiment when the electronic apparatus of the present invention is applied to electronic paper.
An electronic paper 600 shown in FIG. 8 includes a main body 601 composed of a rewritable sheet having the same texture and flexibility as paper, and a display unit 602. In such electronic paper 600, the display unit 602 includes the display device 20 as described above.

Next, an embodiment when the electronic apparatus of the present invention is applied to a display will be described.
FIG. 9 is a diagram showing an embodiment when the electronic apparatus of the present invention is applied to a display. 9A is a cross-sectional view, and FIG. 9B is a plan view.
A display (display device) 800 illustrated in FIG. 9 includes a main body portion 801 and an electronic paper 600 that is detachably attached to the main body portion 801. The electronic paper 600 has the same configuration as described above, that is, the configuration shown in FIG.

  The main body 801 has an insertion port 805 into which the electronic paper 600 can be inserted on its side (right side in FIG. 9A), and two pairs of conveying rollers 802a and 802b are provided inside. Yes. When the electronic paper 600 is inserted into the main body 801 through the insertion port 805, the electronic paper 600 is installed in the main body 801 in a state of being sandwiched between the pair of conveyance rollers 802a and 802b.

A rectangular hole 803 is formed on the display surface side of the main body 801 (the front side in FIG. 9B), and a transparent glass plate 804 is fitted in the hole 803. . Thereby, the electronic paper 600 installed in the main body 801 can be viewed from the outside of the main body 801. That is, in the display 800, the display surface is configured by visually recognizing the electronic paper 600 installed in the main body 801 on the transparent glass plate 804.
In addition, a terminal portion 806 is provided at the leading end of the electronic paper 600 in the insertion direction (left side in FIG. 9A), and the electronic paper 600 is installed in the main body 801 inside the main body 801. A socket 807 to which the terminal portion 806 is connected in the state is provided. A controller 808 and an operation unit 809 are electrically connected to the socket 807.

In such a display 800, the electronic paper 600 is detachably installed on the main body 801, and can be carried and used while being detached from the main body 801. This improves convenience.
As described above, the display device, the manufacturing method of the display device, and the electronic apparatus of the present invention have been described based on the illustrated embodiment. However, the present invention is not limited to this, and the configuration of each part has the same function. Can be replaced with any structure having In addition, any other component may be added to the present invention. Moreover, you may combine each embodiment suitably.

  DESCRIPTION OF SYMBOLS 1 ... Base part 2 ... Base part 3 ... 1st electrode 4 ... 2nd electrode 5 ... Sealing part 62 ... 1st fiber layer 64 ... 2nd fiber layer 620, 640 ... Fiber 7 ... Dispersion medium 8 ... Bubbles 92 ... Wall part 100 ... Dispersion liquid 11 ... First substrate 12 ... Second substrate 13 ... Laminated body 111 ... Display surface 20 ... Display device 21 ... Display sheet 22 Circuit board 400 Display layer 600 Electronic paper 601 Main body 602 Display unit 800 Display 801 Main body 802a, 802b Conveying roller pair 803 Hole 804 ... Transparent glass plate 805 ... Insertion slot 806 ... Terminal part 807 ... Socket 808 ... Controller 809 ... Operation part B, W, Y, M, C ... Particles

Claims (14)

A first substrate provided on the display surface side;
A second substrate disposed opposite the first substrate;
A display layer provided between the first substrate and the second substrate,
The display layer includes
A first fiber layer provided on the first substrate side and including an aggregate of fibers;
A dispersion in which at least one kind of positively or negatively charged particles is dispersed in a dispersion medium;
A display device comprising bubbles. 2. The display device according to claim 1, wherein the relationship of A / B ≦ 1 is satisfied when the volume of the bubbles is A [cm ³ ] and the volume of the dispersion is B [cm ³ ].   The display device according to claim 1, wherein the bubbles are made of an inert gas.   The display device according to claim 1, wherein the humidity in the bubbles is 10% RH or less.   The display device according to claim 1, wherein the first fiber layer includes a space in which the particles can enter.   The display device according to claim 5, wherein the particles are held in the space of the first fiber layer to restrict movement of the particles due to their own weight.   The display device according to claim 1, wherein the fiber is an inorganic fiber.   The display device according to claim 1, wherein the fiber has conductivity.   The display device according to claim 1, wherein the first fiber layer is formed by binding the fibers with an organic binder.   The display device according to claim 9, wherein the organic binder contains at least one of a thermoplastic resin and a thermally crosslinkable resin as a main component. The display layer further includes a partition wall provided so as to surround the dispersion liquid,
The display device according to claim 1, wherein the first fiber layer and the partition are fixed.   The display device according to claim 1, wherein the display layer further includes a second fiber layer provided on the second substrate side and including an aggregate of fibers. A manufacturing method for manufacturing the display device according to any one of claims 1 to 12,
Depositing the first fiber layer on one surface of the first substrate;
Supplying the dispersion on the second substrate;
A step of obtaining a laminate while forming the bubbles by superimposing the first substrate and the second substrate so that the first fiber layer and the dispersion face each other;
And a step of bonding the first substrate and the second substrate by applying pressure in the thickness direction while heating the stacked body. An electronic apparatus comprising: a display device according to any one of claims 1 to 12.

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