JP2006058653A - Electronic book display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device in which an excellent display performance is stably obtained because of a fast response performance and a simple structure, which is suited for displaying electronic book information, and which is low-cost. <P>SOLUTION: In the electronic book display device having a display part to display information derived from a storage medium, the display part is constructed with a display plate forming an image by sealing an image display medium 30 in the closed space between two substrates 10, 20 of which at least one is transparent and which are placed opposite to each other, with a gas as a dispersion medium, and making the image display medium be transferred by applying an electric field to the image display medium 30. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention displays built-in semiconductor storage devices, information recorded on external storage media such as so-called PC cards, smart media, optical storage disks such as CD-ROMs, and magnetic storage disks such as MOs, particularly character information. The present invention relates to an electronic book display device having a display unit.

  Here, an electronic book is a general term for digital data of characters and figures included in a book, and books such as novels and dictionaries recorded on a recording medium such as a CD-ROM are widely used. However, with the remarkable progress of information communication forms such as the spread of the Internet in recent years, computerized book information in various forms has begun to circulate as information media replacing conventional books.

  As a method of using such an electronic book, information recorded in the electronic book is generally displayed and browsed using a personal computer or a dedicated display device. In consideration of portability as a book, a dedicated display device specialized for a multifunctional personal computer is advantageous, and various devices have been proposed.

That is, a transmissive liquid crystal panel as a display device is unsuitable for an electronic book display device that requires a backlight and portability is important. Therefore, most of conventional display devices for electronic books have a display portion. A reflective liquid crystal display device is used. However, in this reflection type liquid crystal display device, since the glass substrate of the liquid crystal cell exists between the liquid crystal layer serving as an optical shutter and the reflection plate, a parallax occurs between the real image by the liquid crystal and the virtual image by the reflection plate. There is a problem in that a shadow is generated in the display image, and there is a viewing angle characteristic peculiar to the liquid crystal display device, and the display contrast changes greatly depending on the angle formed between the display screen and the user's line of sight. From such a background, Patent Document 1 proposes a display device for an electronic book using a liquid crystal excellent in display quality using a polymer film.
JP 2001-92383 A

By the way, a display device for an electronic book is required to bring the shape and weight close to the original book, that is, to be thin and light in weight in order to suppress a sense of incongruity with the original book as much as possible. Smallness and excellent display quality are also demanded. However, since the liquid crystal panel faces the glass substrate provided with electrodes and holds the liquid crystal between these two substrates, there is a limit to reducing the thickness and there is no memory property. In order to continue displaying the power, it is necessary to always supply power. Therefore, the demand for a display device for an electronic book that is thin and light in weight and has low power consumption cannot be sufficiently answered.
Further, regarding the display quality, it is a matter of course that the viewing angle is narrow and the contrast does not reach a level comparable to the original book.

Here, as an image display device replacing the liquid crystal, an image display device using a technique such as an electrophoretic method, an electrochromic method, a thermal method, or a two-color particle rotation method has been proposed.
Compared with liquid crystal, these conventional technologies have advantages such as a wide viewing angle that is close to that of ordinary printed materials, low power consumption, and a memory function. Suitable for equipment. Recently, an electrophoretic method in which a dispersion liquid composed of dispersed particles and a colored solution is encapsulated and disposed between opposing substrates has been proposed and commercialized as a display device for electronic books.

  However, the electrophoresis method has a problem that the response speed becomes slow due to the viscous resistance of the liquid because the particles migrate in the liquid. Furthermore, since particles with high specific gravity such as titanium oxide are dispersed in a solution with low specific gravity, it is easy to settle, it is difficult to maintain the stability of the dispersed state, and the response when displaying information repeatedly is lacking. Have a problem. Even when microencapsulation is performed, the cell size is set to the microcapsule level, and the above-described drawbacks are hardly made to appear, so that the essential problem is not solved at all.

  The present invention has been made by paying attention to the above-described problems, and has a quick response performance and a simple structure, so that excellent display performance can be stably obtained, and it is suitable for displaying electronic book information. It is an object to provide a simple device.

  In addition, as an electronic book display device, the power source is usually a battery when it is assumed to be carried, but it is difficult to guarantee a reading environment for a long time or a long time. This was a problem of the display device. Therefore, it is another object of the present invention to provide an electronic book display device with a function that guarantees a continuous operating environment.

The gist of the present invention is as follows.
(1) An electronic book display device having a display unit for displaying information from a storage medium, wherein the display unit disperses gas in a sealed space between two opposing substrates at least one of which is transparent An electronic book display device comprising: a display plate that encloses an image display medium as a medium and forms an image by moving the image display medium by applying an electric field to the image display medium.

(2) The electronic book display device as described in (1) above, wherein two systems of a battery and a household power source are provided as a driving power source.

(3) The electronic book display device according to (1) or (2), wherein the image display medium is a particle group or a powder fluid.

  According to the present invention, since display of electronic book information is realized by moving an image display medium in which gas is sealed as a dispersion medium in a sealed space between both substrates, a display with a fast response and a high contrast ratio is achieved. Since it is possible and has a simple structure and low power consumption, an electronic book display device that is inexpensive and excellent in stability can be provided.

  In addition, when the two-power supply method is employed, battery consumption can be avoided in a place where a household power supply can be used, so that it is possible to provide an electronic book display device that guarantees long-time operation.

Hereinafter, an electronic book display device of the present invention will be described in detail with reference to the drawings.
The electronic book display device shown in FIG. 1 has a display unit 2 for displaying information from an external or internal storage medium on the top surface of a thin plate-like housing 1, and the housing 1 further includes a battery (not shown). Z). In addition, the display unit 2 has means for updating display contents. As the updating means, for example, there is a page turning means for displaying the previous page or the next page of the displayed page, and this page turning is performed by operating the operation unit 3 on the upper surface of the housing 1.

  Moreover, when using a household power source as a power source other than the battery, as shown in FIG. 2, a terminal 5 for connecting to the household power source via a connection cord 4 with a transformer is provided on the side surface of the housing 1. It is possible to supply power with two systems of a battery and a household power source. Reference numeral 6 denotes a switch for switching between these two power sources.

Next, the basic structure of the display board which comprises this display part 2 is demonstrated about the above-mentioned display part 2. FIG.
The display panel used in the present invention is an image display medium (particle group or powder fluid) having at least two kinds of particles having different colors and charging characteristics composed of at least one kind of particles sealed between two opposing substrates. Information is formed by applying an electric field. That is, along the applied electric field direction, the image display medium charged at a low potential toward the high potential side is attracted by the force of the electric field or Coulomb force, and at the high potential toward the low potential side. The charged image display medium is attracted by an electric field force, a Coulomb force, or the like, and the image display medium is reciprocated by a change in the electric field direction due to a potential change, thereby displaying an image. Therefore, it is necessary to design the display plate so that the image display medium can move uniformly and maintain stability during repetition or storage. Here, the force applied to the particles or powder fluid used as the image display medium is not only the force attracted by the Coulomb force between the particles or powder fluid, but also the image power, intermolecular force, liquid crosslinking force with the electrode or substrate. , Gravity and so on.

The example of the display board of this invention is demonstrated based on Fig.3 (a), (b) and Fig.4 (a), (b).
In the example shown in FIGS. 3A and 3B, at least two colors composed of at least one particle in which a gas, for example, dry air is sealed as a dispersion medium in a sealed space between the substrates 10 and 20. Image display medium 30 (here, white particles 30W and black particles 30B are shown) are moved in a direction perpendicular to the substrates 10 and 20 in accordance with the electric field applied from the outside of the substrates 10 and 20, and the black particles 30B are moved. The black color is displayed by visually recognizing the observer, or the white particles 30W are visually recognized by the observer. In the example shown in FIG. 3B, in addition to the example shown in FIG. 3A, a partition 40 is provided between the substrates 10 and 20 to form a display cell, for example, in a lattice shape.

In the example shown in FIGS. 4A and 4B, at least two different color image display media 30 (here, white particles 30W and black particles 30B are shown) composed of at least one kind of particles are used as substrates. 10 and the electrode 60 provided on the substrate 20 are moved vertically with respect to the substrates 10 and 20 according to the electric field generated by applying a voltage between them, and the black particles 30B are visually recognized by the observer. Thus, black display is performed, or white particles 30W are visually recognized by an observer to perform white display. In the example shown in FIG. 4B, in addition to the example shown in FIG. 4A, partition walls 40 are provided, for example, in a lattice shape between the substrates 10 and 20 to define display cells.
The above description can be similarly applied to the case where the white particles 30W are replaced with the white powder fluid and the black particles 30B are replaced with the black powder fluid.

Hereinafter, each member which comprises the image display board of this invention is demonstrated.
Regarding the substrate, at least one of the substrates is a transparent substrate 20 on which the color of the image display medium can be confirmed from the outside of the panel, and a material having high visible light transmittance and good heat resistance is preferable. The substrate 10 may be transparent or opaque. Examples of substrate materials include polymer sheets such as polyethylene terephthalate, polyethersulfone, polyethylene, polycarbonate, polyimide, and acrylic, flexible materials such as metal sheets, and flexible materials such as glass and quartz. There are no inorganic sheets. The thickness of the substrate is preferably 2 to 5000 μm, more preferably 5 to 2000 μm. If it is too thin, it will be difficult to maintain the strength and the uniformity of the distance between the substrates, and if it is thicker than 5000 μm, a thin image display board will be obtained. Is inconvenient.

  Electrode forming materials for electrodes provided on the substrate as necessary include metals such as aluminum, silver, nickel, copper, and gold, and conductive metal oxides such as ITO, indium oxide, conductive tin oxide, and conductive zinc oxide , Conductive polymers such as polyaniline, polypyrrole, polythiophene and the like are exemplified, and are appropriately selected and used. As a method for forming an electrode, a method of forming the above-described materials into a thin film by sputtering, vacuum deposition, CVD (chemical vapor deposition), coating, or the like, or mixing a conductive agent with a solvent or a synthetic resin binder. The method of apply | coating is used. The electrode provided on the viewing side substrate needs to be transparent, but the electrode provided on the back side substrate does not need to be transparent. In any case, the above-mentioned material that is conductive and capable of pattern formation can be suitably used. Note that the electrode thickness is not particularly limited as long as the conductivity can be secured and the light transmittance is not hindered, and is preferably 3 to 1000 nm, preferably 5 to 400 nm. The material and thickness of the electrode provided on the back side substrate are the same as those of the electrode provided on the viewing side substrate described above, but need not be transparent. In this case, the external voltage input may be superimposed with direct current or alternating current.

  About the partition 40 provided as needed, the shape is appropriately set appropriately depending on the type of image display medium involved in the display, and is not limited in general, but the width of the partition is 2 to 100 μm, preferably 3 to 50 μm. The height of the partition wall is adjusted to 10 to 500 μm, preferably 10 to 200 μm. In forming the partition walls, a both-rib method in which ribs are formed on each of the opposing substrates and then bonded, and a one-rib method in which ribs are formed only on one substrate are conceivable. In the present invention, any method is preferably used.

  As shown in FIG. 5, the display cells formed by the partition walls made up of these ribs are exemplified by a square shape, a triangular shape, a line shape, a circular shape, and a hexagonal shape as viewed from the substrate plane direction. The shape and the mesh shape are exemplified. It is better to make the portion corresponding to the cross section of the partition wall visible from the display side (the area of the frame portion of the display cell) as small as possible, and the sharpness of the image display increases. Here, examples of the method for forming the partition include a mold transfer method, a screen printing method, a sand blast method, a photolithography method, and an additive method. Among these, a photolithography method using a resist film and a mold transfer method are preferably used. In any method, the present invention can be suitably used.

Next, the powder fluid as an image display medium used in the image display panel of the present invention will be described. As for the name of the powder fluid as the image display medium of the present invention, the present applicant has obtained the right of “Electronic Powder Fluid (registered trademark)”.
The “powder fluid” in the present invention is a substance in an intermediate state of both fluid and particle characteristics that exhibits fluidity by itself without borrowing the force of gas or liquid. For example, liquid crystal is defined as an intermediate phase between a liquid and a solid, and has fluidity that is a characteristic of liquid and anisotropy (optical properties) that is a characteristic of solid (Heibonsha: Encyclopedia) . On the other hand, the definition of particle is an object with a finite mass even if it is negligible, and is said to be affected by gravity (Maruzen: Physics Encyclopedia). Here, even in the case of particles, there are special states of gas-solid fluidized bed and liquid-solid fluids. When gas is flowed from the bottom plate to the particles, upward force is applied to the particles according to the velocity of the gas. Is a gas-solid fluidized bed that is in a state where it can easily flow when it balances with gravity, and it is also called a liquid-solid fluidized state that is fluidized by a fluid (ordinary) Company: Encyclopedia). As described above, the gas-solid fluidized bed body and the liquid-solid fluid are in a state of using a gas or liquid flow. In the present invention, it has been found that a substance in a state of fluidity can be produced specifically without borrowing the force of such gas and liquid, and this is defined as powder fluid.

  That is, the pulverulent fluid in the present invention is in an intermediate state having both the characteristics of particles and liquid, as in the definition of liquid crystal (liquid and solid intermediate phase), and is the characteristic of the above-mentioned particles. It is a substance that is extremely unaffected and exhibits a unique state with high fluidity. Such a substance can be obtained in an aerosol state, that is, a dispersion system in which a solid or liquid substance is stably suspended as a dispersoid in a gas serving as a dispersion medium, and the solid substance is dispersed in the display device of the present invention. It is what you want.

The image display panel of the present invention encloses a powder fluid exhibiting high fluidity in an aerosol state in which solid particles are stably suspended as a dispersoid in a gas as an image display medium between opposite substrates, at least one of which is transparent Such a powder fluid can be easily and stably moved by a Coulomb force or the like by applying a low voltage.
As described above, for example, the powder fluid used in the present invention is a substance in an intermediate state between fluid and particles, which exhibits fluidity by itself without borrowing the force of gas or liquid. This powder fluid can be in an aerosol state in particular, and in the image display device of the present invention, a solid substance is used in a state of relatively stably floating as a dispersoid in the gas.

  Here, the range of the aerosol state is such that the apparent volume when the pulverized fluid is floated is preferably 2 times or more, more preferably 2.5 times or more, and particularly preferably 3 times or more that when the powder fluid is not floating. Although an upper limit is not specifically limited, It is preferable that it is 12 times or less.

  If the apparent volume of the pulverized fluid is less than twice that of the unfloating state, it is difficult to control the display, and if it is more than 12 times, the powder fluid will be overloaded when sealed in the device. Inconvenience in handling occurs. The apparent volume at the maximum floating time is measured as follows. That is, the powdered fluid is put into a closed container that allows the powdered fluid to permeate, and the container itself is vibrated or dropped to create a maximum floating state, and the apparent volume at that time is measured from the outside of the container. Specifically, in a container with a lid (trade name: iBoy: manufactured by ASONE Co., Ltd.) having a diameter (inner diameter) of 6 cm and a height of 10 cm, a powder fluid equivalent to 1/5 of the volume as a powder fluid when not floating. And set the container on a shaker, and shake at a distance of 6 cm at 3 reciprocations / sec for 3 hours. The apparent volume immediately after stopping shaking is the apparent volume at the maximum floating time.

Further, in the present invention, it is preferable that the change in the apparent volume of the powder fluid satisfies the following formula.
V ₁₀ / V ₅ > 0.8
Here, V ₅ represents an apparent volume (cm ³ ) 5 minutes after the maximum floating time, and V ₁₀ represents an apparent volume (cm ³ ) 10 minutes after the maximum floating time. In the image display device of the present invention, the apparent volumetric change V ₁₀ / V ₅ of the powder fluid is preferably larger than 0.85, and more preferably larger than 0.9. When V ₁₀ / V ₅ is 0.8 or less, it becomes the same as when ordinary so-called particles are used, and it becomes impossible to ensure the effect of high-speed response and durability as in the present invention.

  The average particle diameter (d (0.5)) of the particulate material constituting the powder fluid is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and particularly preferably 0.9 to 8 μm. If it is smaller than 0.1 μm, it is difficult to control the display, and if it is larger than 20 μm, it is possible to display but the concealment rate is lowered and it is difficult to make the device thin. The average particle diameter (d (0.5)) of the particulate material constituting the powder fluid is the same as d (0.5) in the next particle diameter distribution Span.

The particle substance constituting the powder fluid preferably has a particle size distribution Span represented by the following formula of less than 5, more preferably less than 3.
Particle size distribution Span = (d (0.9) -d (0.1)) / d (0.5)
Here, d (0.5) is a numerical value expressed in μm of the particle diameter that 50% of the particulate material constituting the powder fluid is larger than this and 50% is smaller than this, and d (0.1) is less than this. A numerical value in which the ratio of the particle substance constituting the powder fluid is 10%, expressed in μm, and d (0.9) is the particle diameter in which the particulate substance constituting the powder fluid is 90% μm It is a numerical value expressed by By setting the particle size distribution Span of the particulate material constituting the powder fluid to 5 or less, the sizes are uniform and uniform powder fluid movement becomes possible.

  The above particle size distribution and particle size can be obtained from a laser diffraction / scattering method or the like. When laser light is irradiated to the powder fluid to be measured, a light intensity distribution pattern of diffracted / scattered light is generated spatially, and this light intensity pattern has a corresponding relationship with the particle diameter, so the particle diameter and particle diameter distribution are measured. it can. This particle size and particle size distribution are obtained from a volume-based distribution. Specifically, using a Mastersizer2000 (Malvern Instruments Ltd.) measuring machine, the powdered fluid was introduced into the nitrogen stream, and the attached analysis software (software based on volume reference distribution using Mie theory) Measurements can be made.

  Preparation of powder fluid can be done by kneading and pulverizing the necessary resin, charge control agent, colorant, and other additives, or by polymerization from monomers, and adding existing particles to resin, charge control agent, colorant, and other It may be coated with an agent. Hereinafter, the resin, charge control agent, colorant, and other additives constituting the powder fluid will be exemplified.

  Examples of the resin include urethane resin, acrylic resin, polyester resin, urethane-modified acrylic resin, silicone resin, nylon resin, epoxy resin, styrene resin, butyral resin, vinylidene chloride resin, melamine resin, phenol resin, and fluorine resin. Two or more types can also be mixed. In particular, acrylic urethane resin, acrylic urethane silicone resin, acrylic urethane fluororesin, urethane resin, and fluororesin are preferable from the viewpoint of controlling the adhesive force with the substrate.

Examples of charge control agents include quaternary ammonium salt compounds, nigrosine dyes, triphenylmethane compounds, imidazole derivatives and the like in the case of imparting positive charges, and metal-containing azo compounds in the case of imparting negative charges. Examples thereof include dyes, salicylic acid metal complexes, and nitroimidazole derivatives.
Examples of the colorant include basic and acidic dyes such as nigrosine, methylene blue, quinoline yellow, and rose bengal.
Examples of inorganic additives include titanium oxide, zinc white, zinc sulfide, antimony oxide, calcium carbonate, lead white, talc, silica, calcium silicate, alumina white, cadmium yellow, cadmium red, cadmium orange, titanium yellow, Examples include bitumen, ultramarine blue, cobalt blue, cobalt green, cobalt violet, iron oxide, carbon black, manganese ferrite black, cobalt ferrite black, copper powder, and aluminum powder.

  However, even if such a material is kneaded and coated without any ingenuity, a powder fluid that shows an aerosol state cannot be produced. The production method of the powder fluid showing the aerosol state is not clear, but is exemplified as follows.

  First, it is appropriate to fix inorganic fine particles having an average particle diameter of 20 to 100 nm, preferably 20 to 80 nm, to the surface of the particulate material constituting the powder fluid. Furthermore, it is appropriate that the inorganic fine particles are treated with silicone oil. Here, examples of the inorganic fine particles include silicon dioxide (silica), zinc oxide, aluminum oxide, magnesium oxide, cerium oxide, iron oxide, and copper oxide. The method of fixing the inorganic fine particles is important. For example, using a hybridizer (manufactured by Nara Machinery Co., Ltd.) or mechanofusion (manufactured by Hosokawa Micron Co., Ltd.) or the like, under certain limited conditions (for example, processing time) ), A powder fluid showing an aerosol state can be produced.

Here, in order to further improve the repeated durability, it is effective to manage the stability of the resin constituting the powder fluid, particularly the water absorption rate and the solvent insolubility rate. The water absorption rate of the resin constituting the powder fluid enclosed in the cells partitioned by the partition walls is preferably 3% by mass or less, particularly preferably 2% by mass or less. The water absorption is measured according to ASTM-D570, and the measurement condition is 23 ° C. for 24 hours. Regarding the solvent insolubility of the resin constituting the powder fluid, the solvent insolubility of the powder fluid represented by the following relational expression is preferably 50% or more, particularly 70% or more.
Solvent insolubility (%) = (B / A) × 100
(However, A represents the weight of the resin before dipping in the solvent, and B represents the weight after dipping the resin in a good solvent at 25 ° C. for 24 hours.)

  If this solvent insolubility is less than 50%, bleeding occurs on the surface of the particulate material that constitutes the powder fluid during long-term storage, which affects the adhesion with the powder fluid and hinders the movement of the powder fluid, resulting in improved image display durability. May cause problems. The solvent (good solvent) for measuring the solvent insolubility is methyl ethyl ketone, etc. for fluororesins, methanol, etc. for polyamide resins, methyl ethyl ketone, toluene, etc. for acrylic urethane resins, acetone, isopropanol, etc. for melamine resins, silicone resins, etc. In this case, toluene or the like is preferable.

  Next, the particles as the image display medium used in the image display panel of the present invention will be described. The particles can contain a charge control agent, a colorant, an inorganic additive, and the like, if necessary, in the resin as the main component, as in the conventional case. Examples of resins, charge control agents, colorants, and other additives will be given below.

  Examples of the resin include urethane resin, urea resin, acrylic resin, polyester resin, acrylic urethane resin, acrylic urethane silicone resin, acrylic urethane fluororesin, acrylic fluororesin, silicone resin, acrylic silicone resin, epoxy resin, polystyrene resin, styrene Acrylic resin, polyolefin resin, butyral resin, vinylidene chloride resin, melamine resin, phenol resin, fluororesin, polycarbonate resin, polysulfone resin, polyether resin, polyamide resin and the like can be mentioned, and two or more kinds can be mixed. In particular, acrylic urethane resin, acrylic silicone resin, acrylic fluororesin, acrylic urethane silicone resin, acrylic urethane fluororesin, fluororesin, and silicone resin are suitable from the viewpoint of controlling the adhesive force with the substrate.

  The charge control agent is not particularly limited. Examples of the negative charge control agent include salicylic acid metal complexes, metal-containing azo dyes, metal-containing oil-soluble dyes (including metal ions and metal atoms), and quaternary ammonium salt systems. Examples thereof include compounds, calixarene compounds, boron-containing compounds (benzyl acid boron complexes), and nitroimidazole derivatives. Examples of the positive charge control agent include nigrosine dyes, triphenylmethane compounds, quaternary ammonium salt compounds, polyamine resins, imidazole derivatives, and the like. In addition, metal oxides such as ultrafine silica, ultrafine titanium oxide, ultrafine alumina, nitrogen-containing cyclic compounds such as pyridine and derivatives and salts thereof, various organic pigments, resins containing fluorine, chlorine, nitrogen, etc. are also charged. It can also be used as a control agent.

As the colorant, various organic or inorganic pigments and dyes as exemplified below can be used.
Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon and the like.
Examples of blue colorants include C.I. I. Pigment blue 15: 3, C.I. I. Pigment Blue 15, Bituminous Blue, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Metal-free Phthalocyanine Blue, Phthalocyanine Blue Partial Chlorides, Fast Sky Blue, Indanthrene Blue BC and the like.
Examples of red colorants include bengara, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, risor red, pyrazolone red, watching red, calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, Alizarin Lake, Brilliant Carmine 3B, C.I. I. Pigment Red 2 etc.

Yellow colorants include chrome yellow, zinc yellow, cadmium yellow, yellow iron oxide, mineral first yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, C.I. I. Pigment Yellow 12 etc.
Examples of green colorants include chrome green, chromium oxide, pigment green B, C.I. I. Pigment Green 7, Malachite Green Lake, Final Yellow Green G, etc.
Examples of the orange colorant include red chrome yellow, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK, C.I. I. Pigment Orange 31 etc.
Examples of purple colorants include manganese purple, first violet B, and methyl violet lake.
Examples of white colorants include zinc white, titanium oxide, antimony white, and zinc sulfide.

  Examples of extender pigments include barite powder, barium carbonate, clay, silica, white carbon, talc, and alumina white. Examples of various dyes such as basic, acidic, disperse, and direct dyes include nigrosine, methylene blue, rose bengal, quinoline yellow, and ultramarine blue.

Examples of inorganic additives include titanium oxide, zinc white, zinc sulfide, antimony oxide, calcium carbonate, lead white, talc, silica, calcium silicate, alumina white, cadmium yellow, cadmium red, cadmium orange, titanium yellow, Examples include bitumen, ultramarine blue, cobalt blue, cobalt green, cobalt violet, iron oxide, carbon black, manganese ferrite black, cobalt ferrite black, copper powder, and aluminum powder.
These pigments and inorganic additives can be used alone or in combination. Of these, carbon black is particularly preferable as the black pigment, and titanium oxide is preferable as the white pigment.

  The particles as the image display medium of the present invention have an average particle diameter d (0.5) in the range of 0.1 to 50 μm and are preferably uniform. If the average particle diameter d (0.5) is larger than this range, the display is not clear. If the average particle diameter d (0.5) is smaller than this range, the cohesive force between the particles becomes too large, which hinders the movement of the particles.

Furthermore, in the present invention, regarding the particle size distribution of each particle, the particle size distribution Span represented by the following formula is set to less than 5, preferably less than 3.
Span = (d (0.9) −d (0.1)) / d (0.5)
(However, d (0.5) is a numerical value indicating the particle diameter in μm that 50% of the particles are larger than this, and 50% is smaller than this, and d (0.1) is a particle in which the ratio of the smaller particles is 10%. (Numerical value expressed in μm, and d (0.9) is a numerical value expressed in μm for a particle size of 90% or less.)
By keeping Span within a range of 5 or less, the size of each particle is uniform and uniform particle movement is possible.

  Furthermore, regarding the correlation between the particles, the ratio of the d (0.5) of the particles having the minimum diameter to the d (0.5) of the particles having the maximum diameter among the used particles is set to 50 or less, preferably 10 or less. It is essential.

The particle size distribution and the particle size can be obtained from a laser diffraction / scattering method or the like. When laser light is irradiated onto particles to be measured, a light intensity distribution pattern of diffracted / scattered light is spatially generated, and this light intensity pattern has a corresponding relationship with the particle diameter, so that the particle diameter and particle diameter distribution can be measured. .
Here, the particle size and particle size distribution in the present invention are obtained from a volume-based distribution. Specifically, using a Mastersizer2000 (Malvern Instruments Ltd.) measuring instrument, particles are introduced into a nitrogen stream, and the attached analysis software (software based on volume-based distribution using Mie theory) The diameter and particle size distribution can be measured.

  The charge amount of the particles constituting the image display medium naturally depends on the measurement conditions, but the charge amount of the particles constituting the image display medium in the image display panel is almost equal to the initial charge amount, contact with the partition walls, and the substrate. It was found that the saturation value of the charging behavior of the particles constituting the image display medium is a dominant factor, depending on the charge decay with contact and elapsed time.

Furthermore, in the present invention, when a dry image display medium is used, it is important to manage the gas in the gap surrounding the image display medium between the substrates, which contributes to improved display stability. Specifically, it is important that the relative humidity at 25 ° C. is 60% RH or less, preferably 50% RH or less, more preferably 35% RH or less with respect to the humidity of the gas in the gap.
3A, 3B, 4A, and 4B, the gap portion is defined by the electrodes 50 and 60, the image display medium (particles) from the portion sandwiched between the opposing substrate 10 and the substrate 20. A gas portion in contact with a so-called image display medium excluding an occupied portion of the group or powdered fluid 30), an occupied portion of the partition wall 40 (when a partition wall is provided), and an image display plate seal portion.
The gas in the gap is not limited as long as it is in the humidity region described above, but dry air, dry nitrogen, dry argon, dry helium, dry carbon dioxide, dry methane, and the like are preferable. This gas needs to be sealed in the image display board so that the humidity is maintained. For example, filling of the image display medium and assembly of the image display board are performed in a predetermined humidity environment. It is important to use a sealing material and a sealing method that prevent moisture from entering.

The distance between the substrates in the image display panel of the present invention is not limited as long as the image display medium can be moved and the contrast can be maintained, but is usually adjusted to 10 to 500 μm, preferably 10 to 200 μm.
The volume occupation ratio of the image display medium in the space between the opposing substrates is preferably 5 to 70%, more preferably 5 to 60%. If it exceeds 70%, the movement of the image display medium is hindered. If it is less than 5%, the contrast tends to be unclear.

It is a perspective view which shows the electronic book display apparatus of this invention. It is a perspective view which shows the state which inserted the power cord in the electronic book display apparatus of this invention. (A), (b) is a figure which shows an example of the image display board of this invention, respectively. (A), (b) is a figure which shows the other example of the image display board of this invention, respectively. It is a figure which shows an example of the shape of the partition in the image display panel of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case 2 Display part 3 Operation part 4 Connection cord with a transformer 5 Terminal 6 Changeover switch 10, 20 Substrate 30 Image display medium (particle group or powder fluid)
30W white particles (white powder fluid)
30B Black particles (black powder fluid)
40 Bulkhead 50, 60 electrodes

Claims (3)

  An electronic book display device having a display unit for displaying information from a storage medium, wherein the display unit is an image using gas as a dispersion medium in a sealed space between two opposing substrates, at least one of which is transparent. An electronic book display device comprising: a display plate which encloses a display medium and forms an image by moving the image display medium by applying an electric field to the image display medium.   The electronic book display device according to claim 1, comprising two systems of a battery and a household power source as driving power sources.   The electronic book display device according to claim 1, wherein the image display medium is a particle group or a powder fluid.

Images