JP2006301616A - Information display panel and information display device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information display panel capable of stably holding surface charges and stabilizing an information display state of an image etc., for a long period, and an information display device using the same. <P>SOLUTION: The information display panel which is constituted by charging at least one or more kinds of display media between two opposite substrates at least one of which is transparent and moves the display media by applying an electric field to the display media to display information of an image etc., is characterized in that particle surfaces of particles constituting the display media and substrate surfaces coming into contact with the particles are made of the same material, preferably, an electron transport material or positive hole transport material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides an information display in which at least one display medium is sealed between two opposing substrates, at least one of which is transparent, and an electric field is applied to the display medium to move the display medium to display information such as an image. The present invention relates to a panel and an information display device using the panel.

  2. Description of the Related Art Conventionally, information display devices using techniques such as electrophoresis, electrochromic, thermal, and two-color particle rotation have been proposed as information display devices that replace liquid crystal (LCD).

  Compared to LCDs, these conventional technologies have advantages such as a wide viewing angle close to that of ordinary printed materials, low power consumption, and a memory function. It is considered as a technology that can be used for mobile phones, and is expected to expand to information display for mobile terminals, electronic paper, and the like. Particularly 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 is expected.

  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. In addition, since particles with high specific gravity such as titanium oxide are dispersed in a solution with low specific gravity, it is easy to settle, and it is difficult to maintain the stability of the dispersed state, and there is a problem that the stability of repeated information display is lacking. ing. Even when microencapsulation is performed, the cell size is set to the microcapsule level, and the above-described drawbacks are hardly made to appear, and the essential problems are not solved at all.

As a method for solving the above-described problem of the electrophoresis method utilizing the behavior in a solution, after sealing a display medium between two opposing substrates at least one of which is transparent, or a partition wall There is known an information display panel in which cells isolated from each other are formed, a display medium is sealed in the cell, an electric field is applied to the display medium, and the display medium is moved to display information such as an image.
趙 Kuniori and three others, “New Toner Display Device (I)”, July 21, 1999, Annual Meeting of the Imaging Society of Japan (83 times in total) “Japan Hardcopy'99” Proceedings, p.249-252

  The basis of these display mechanisms is the surface charge of the particles, and in order to obtain a stable high-definition display, it is necessary to keep the particle surface charges stable. However, the surface charge is very unstable and easily attenuates due to, for example, an environment such as humidity, and easily changes due to contact with or friction with other substances. Also, if some mass transfer or deformation occurs in the particles, the surface charge changes. As is apparent from the display mechanism described above, these changes in surface charge lead to changes in the display state, and there is a problem that the display state becomes unstable due to long-term storage and long-term use of the information display panel. It was.

  An object of the present invention is to provide an information display panel and an information display device using the same, which can solve the above-mentioned problems, can stably maintain surface charges, and can stabilize an information display state of an image or the like for a long period of time. It is what.

  In the information display panel of the present invention, at least one type of display medium is sealed between two opposing substrates, at least one of which is transparent, and an electric field is applied to the display medium to move the display medium to display information such as an image. In the information display panel to be displayed, the particle surface of the particles constituting the display medium and the substrate surface in contact with the particles are formed of the same material.

  As a suitable example of the information display panel of the present invention, the material constituting the particle surface and the substrate surface is an electron transporting material, and the material constituting the particle surface and the substrate surface is a hole transporting material. There is, there is.

  The information display device of the present invention is characterized in that the information display panel having the above-described configuration is used as an information display unit.

  According to the present invention, since the particle surface of the particles constituting the display medium and the substrate surface in contact with the particles are made of the same material, the surface charge of the display medium particles can be stably held. As a result, an information display panel having a stable information display state such as an image can be obtained.

  First, the basic configuration of the information display panel of the present invention will be described. In the information display panel which is an object of the present invention, an electric field is applied to a display medium sealed between two opposing substrates. Along with the applied electric field direction, the charged display medium is attracted by the electric field force or Coulomb force, etc., and the moving direction of the display medium is changed by changing the electric field direction by switching the potential, thereby displaying information such as an image. Is made. Therefore, it is necessary to design the information display panel so that the display medium moves uniformly and can maintain the stability at the time of display rewriting or continuous display of information. Here, as the force applied to the particles constituting the display medium, in addition to the force attracted by the Coulomb force between the particles, an electric image force with the electrode and the substrate, an intermolecular force, a liquid cross-linking force, gravity and the like can be considered.

  An example of the information display panel of the present invention will be described based on FIGS. 1 (a) and (b) to FIGS. 3 (a) and 3 (b).

  In the example shown in FIGS. 1A and 1B, at least two types of display media 3 (here, white display media) each having at least one type of particles and having different optical reflectance and charging characteristics are used. White display medium 3W composed of particles composed of particles for use and black display medium 3B composed of particles composed of particles for black display medium) according to the electric field applied from the outside of the substrates 1 and 2. The black display medium 3B is visually recognized by the observer and the black display is performed, or the white display medium 3W is visually recognized by the observer and the white display is performed. . In the example shown in FIG. 1B, in addition to the example shown in FIG. 1A, a partition 4 is provided between the substrates 1 and 2, for example, in the form of a lattice to form a cell. In addition, in FIG. 1B, the partition in front is omitted.

  In the example shown in FIGS. 2A and 2B, at least two types of display media 3 (here, white display media) each having at least one type of particles and having different optical reflectivity and charging characteristics are used. The electrode 5 provided on the substrate 1 and the substrate 2 are provided with a white display medium 3W composed of particles composed of particles for use and a black display medium 3B composed of particles composed of particles for black display media). Depending on the electric field generated by applying a voltage between the electrode 6 and the electrode 6, the substrate 1 and 2 are moved vertically and the black display medium 3B is visually recognized by the observer to display black, or The white display medium 3 </ b> W is visually recognized by an observer to perform white display. In the example shown in FIG. 2B, in addition to the example shown in FIG. 2A, for example, a partition 4 is provided between the substrates 1 and 2 to form a cell. Further, in FIG. 2 (b), the front partition is omitted.

In the example shown in FIGS. 3A and 3B, one type of display medium 3 having optical reflectivity and chargeability composed of at least one kind of particles (here, composed of white display medium particles). In the direction parallel to the substrates 1 and 2 according to the electric field generated by applying a voltage between the electrode 5 and the electrode 6 provided on the substrate 1. The white display medium 3W is moved and the observer visually recognizes the white display, or the color of the electrode 6 or the substrate 1 is visually recognized by the observer and the color of the electrode 6 or the substrate 1 is displayed. . In the example shown in FIG. 3B, in addition to the example shown in FIG. 3A, for example, a grid-like partition wall 4 is provided between the substrates 1 and 2 to form a cell. Moreover, in FIG.3 (b), the partition in front is abbreviate | omitted.
Note that the electrode may be provided inside the substrate, outside the substrate, or embedded in the substrate.

  The feature of the present invention is that the particle surface of the particles constituting the display medium and the substrate surface in contact with the particles are composed of the same material, preferably, the material constituting the particle surface and the substrate surface is an electron transporting material or It is a hole transporting material.

  In the information display panel of the present invention, examples of the substance that contacts when particles move in the panel include other particles and the substrate surface. When these come into contact, some kind of charge is generated, but as the charging mechanism, contact charge, friction charge, peeling charge, collision charge, and the like are intricately intertwined. In particular, when the particles come into contact with other substances, the charge transfer almost certainly occurs, which changes the charged state of the particles. In order to prevent this, it is conceivable that each constituent member is made of the same material. In particular, if the substrate surface and the particle surface that are frequently contacted with particles are formed of the same material, the charge can be stabilized even in contact. it can.

  Furthermore, by selecting a material to be used, contact charging can be controlled with a certain degree of accuracy. That is, by using the difference in the electron energy level of each substance, it is possible to relatively control, for example, which side the negative charge easily moves when two substances come into contact with each other. When a metal and a semiconductor are in contact with each other, there may be a rectifying contact or an ohmic contact depending on the relative relationship between the energy levels. Here, the rectifying contact can be defined as a contact in which a barrier is generated in the contact portion and rectification occurs in the contact between the metal and the semiconductor. In addition, the ohmic contact can be defined as a contact in which a barrier is not generated in a contact portion and a simple resistance is generated in contact between a metal and a semiconductor. That is, by using this characteristic, the charge stored in the particles can be controlled by controlling the configuration of the substrate and the particles in the information display panel.

A specific example will be described below.
In the present invention, the case where an electron transport material is used for the particle surface of the display medium particle and the substrate surface in contact with the particle will be considered. In this case, since the particle surface and the substrate surface are the same material, no energy barrier appears at this contact surface. That is, it is considered that there is no problem with respect to charge transfer. Here, a metal material is used for the lower layer of the substrate surface, and the metal material is set so as to be in rectifying contact with the electron transport material on the substrate surface. In that case, an energy barrier is generated at the bonding surface, and the negative charge is in a forward direction in which it tends to flow into the substrate lower layer metal material rather than the electron transporting material. Become. Therefore, in such a configuration, regular rectification is exhibited. Here, when a positive potential is applied to the substrate metal, the barrier is lowered, and the extraction of electrons from the electron transporting material is accelerated, so that the contacting particles are more positively charged. On the other hand, when a negative potential is applied to the substrate, the barrier becomes high and the movement of electrons becomes very small, that is, the chargeability of the particles does not substantially change. As a result, particles with an electron transporting material on the surface can selectively extract electrons only when they come into contact with the substrate, and maintain a stable positive charge even when continuous movement between substrates is continued. It becomes possible to do.

  When a hole transporting material is used for the particle surface and the substrate surface, the same tendency as the electron transporting material is obtained except that the polarity is reversed, and the particles can maintain negative chargeability. Become.

  The method for producing the particles is not particularly limited as long as the above-described electric properties of the electron transport property or the hole transport property can be expressed, but the following method is preferably used as an example. First, it is possible to present a method of preparing particles as a base and coating the surface with a semiconductor substance having an electron transporting property or a hole transporting property. Surface coating can be performed by vapor deposition or sputtering on the surface of the base particles, or by introducing the base particles into a dissolved or melted electron transporting or hole transporting semiconductor substance. A method of drying and solidifying, and a method of immobilizing an electron-transporting or hole-transporting semiconductor substance dissolved and melted in a particle agitating device such as a Henschel mixer after stirring. Furthermore, a method in which an electron transporting or hole transporting semiconductor material is dispersed in another resin and the particle surface based on the mixture is coated by the above-described method. As other particle manufacturing methods, a method of obtaining particles by kneading and pulverizing an electron transporting or hole transporting semiconductor material with another resin, or an electron transporting or hole transporting semiconductor material itself is used as the particles. It is also possible.

  Among particles having a surface coated with a semiconductor material made of an electron transporting material or a hole transporting material, the base particle is preferably a metal or metal oxide disposed on the surface. The particle | grains comprised by particle | grains or the metal oxide simple substance may be sufficient. Alternatively, the surface of particles such as resin may be coated with metal or metal oxide, or the surface of particles such as resin may be partially disposed with metal or metal oxide. The thickness of the semiconductor material to be surface-covered (or partially disposed on the surface) is not particularly limited, but it is preferably a thin film when considering the charge injection efficiency, and is preferably 100 μm or less, preferably 50 μm or less, It is preferably 1 μm or less. When encapsulating in the panel, an appropriate amount of fine particles such as silica or titanium oxide having a particle size considerably smaller than the particles may be imparted for the purpose of improving fluidity.

  There is no restriction | limiting in particular as a material which produces particle | grains based on, A normal general purpose resin, an inorganic material, a metal material, etc. are used suitably. In this case, it is preferable to display the display color as the base particle, and it is necessary to make the color tone particles with good visibility.

  As an example of the semiconductor material disposed on the surface of the particles constituting the display medium and the surface of the substrate, silicon, germanium, diamond, selenium, tellurium and the like can be given as a single semiconductor substance. Examples of the compound semiconductor include gallium arsenide, gallium phosphide, indium arsenic, gallium aluminum arsenic, gallium aluminum indium arsenide, zinc sulfide, cadmium sulfide, cadmium selenium, cadmium tellurium, silicon carbide, and the like. Furthermore, examples of the oxide semiconductor include nickel oxide (II), copper oxide (I), zinc oxide, and tin oxide (IV). In addition, nitride semiconductors, sulfide semiconductors, and the like are included, and those doped into these are also included.

  Furthermore, organic semiconductors having low molecular weight include anthracene compounds, violanthrone compounds, porphyrin compounds, phthalocyanine compounds, perylene compounds, quinone compounds, azo compounds, squarylium compounds, azulenium compounds, Bililium compounds, cyanine compounds, aromatic amine compounds, aromatic diamine compounds, oxadiazole compounds, oxazole compounds, pyrazoline compounds, aromatic methane compounds, hydrazone compounds, carbazole compounds, and these And the like. In addition, examples of the high molecular organic semiconductor include polyacetylene, poly (p-phenylene), polypyrrole, polythiophene, polyaniline, poly (p-phenylene vinylene), and derivatives thereof. Furthermore, the thing which doped the impurity to the said substance is also included.

  The layer thickness to be coated on the surface needs to be suppressed to such a level that resistance rises and the charge injection efficiency does not decrease, and is usually 10 μm or less, preferably 1 μm or less.

The basic configuration of the display medium particles (also simply referred to as particles) used in the information display panel of the present invention will be described below.
The particles are preferably spherical. 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 used in the present invention preferably have an average particle diameter d (0.5) in the range of 0.1 to 20 μm and are uniform and uniform. If the average particle diameter d (0.5) is larger than this range, the display is not clear, and if it 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. Even if the particle size distribution Span is reduced, particles with different charging characteristics move in opposite directions, so that the particle size is close to each other and each particle can be easily moved in the opposite direction by the equivalent amount. This is within this range.

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 particles of 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 display medium particles naturally depends on the measurement conditions, but the charge amount of the display medium particles in the information display panel is almost the initial charge amount, the contact with the partition wall, the contact with the substrate, the charge associated with the elapsed time. It was found that depending on the attenuation, the saturation value of the charging behavior of the particles for the display medium is a dominant factor.

  As a result of intensive studies, the present inventors have been able to evaluate the range of proper charging characteristics of display medium particles by measuring the charge amount of the particles used in the display medium using the same carrier particles in the blow-off method. I found.

Furthermore, when a display medium composed of particles for display medium is applied to a dry information display panel, it is important to manage the gas in the void surrounding the 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, with respect to the gas humidity in the void portion.
1A, 1B, 3A, and 3B, the gaps are defined as electrodes 5 and 6 (electrodes on the inner side of the substrate). ), An occupied portion of the display medium 3, an occupied portion of the partition wall 4 (when a partition wall is provided), and a gas portion in contact with a so-called display medium excluding a seal portion of the information display panel.
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 information display panel so that the humidity is maintained. For example, filling of the display medium, assembly of the information display panel, etc. are performed in a predetermined humidity environment. It is important to apply a sealing material and a sealing method that prevent moisture from entering.

The distance between the substrates in the information display panel that is the subject of the present invention is not limited as long as the 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.
When the display medium is used, the volume occupation ratio of the 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 display medium is hindered, and if it is less than 5%, the contrast tends to be unclear.

  Hereinafter, each member which comprises the information display panel used as the object of this invention is demonstrated.

  As for the substrate, at least one of the substrates has the above-mentioned characteristics of the present invention, and at least one of the substrates is a transparent substrate 2 on which the color of the display medium 3 can be confirmed from the outside of the panel, and has high visible light transmittance and heat resistance. A material with good properties is preferred. The substrate 1 may be transparent or opaque. Examples of substrate materials include polymer sheets such as polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyethylene, polycarbonate, polyimide, and acrylic, flexible materials such as metal sheets, and glass and quartz. An inorganic sheet having no flexibility is mentioned. 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, it will be a thin information display panel. There is an inconvenience.

  As an electrode forming material when an electrode is provided on an information display panel, metals such as aluminum, silver, nickel, copper, and gold, indium tin oxide (ITO), indium oxide, conductive tin oxide, antimony tin oxide (ATO) ), Conductive metal oxides such as conductive zinc oxide, and conductive polymers such as polyaniline, polypyrrole, and polythiophene are exemplified and used as appropriate. 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 (display surface 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 display 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.

  The partition 4 provided on the substrate as needed is optimally set according to the type of 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. As shown in FIG. 4, the 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 plane of the substrate. And a mesh shape. It is better to make the portion corresponding to the cross section of the partition wall visible from the display surface side (the area of the cell frame) as small as possible, and the display becomes clearer.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples.

  The information display panels of Examples 1 to 4 and Comparative Example 1 were produced as follows, and various characteristics of the produced information display panels were obtained and compared. First, in each of the following examples, the confirmation method of the rectifying contact used and the measurement method of various measurements of the information display panel will be described, and then each example will be described.

"Confirming rectifying contact"
Confirmation of rectification can be carried out by examining current-voltage characteristics. First, as shown in FIG. 5, a measurement sample is prepared by laminating a semiconductor film with an Al electrode and an Au electrode provided on one surface and an ITO electrode, an Al electrode, and an Au electrode provided on the other surface. did. The relationship of the work function of the electrode material is Al <ITO <Au. Samples were prepared by vapor deposition for electrodes, vapor deposition for semiconductor films, or by spin-coating a coating solution dissolved in an arbitrary solvent.

  When a voltage is applied between Al and Al, the current-voltage characteristic shows ohmic contact as shown in FIG. 6 as an example, and when a voltage is applied between Al and ITO, the current-voltage characteristic is shown in FIG. As an example, when the rectifying contact is shown and the polarity in which ITO becomes a positive electrode is a forward bias, this semiconductor film can be said to be an electron transporting semiconductor material that makes a rectifying contact with ITO. On the other hand, when a voltage is applied between Au and Au, the current-voltage characteristic shows an ohmic contact as shown in FIG. 6, and when a voltage is applied between Au and ITO, the current-voltage characteristic is shown in FIG. As shown in an example, when the rectifying contact is shown and the polarity in which ITO becomes a negative electrode is a forward bias, this semiconductor film can be said to be a hole transporting semiconductor material that makes a rectifying contact with ITO.

"Measuring method of various characteristics"
About average particle diameter d (0.5) and particle diameter Span, it measured according to the example mentioned above. The coating layer thickness of the surface layer was measured by observing and measuring the particles after cutting the particles using Examples 2 and 3 using SEM and Examples 1 and 4 using TEM. The chargeability and the charge amount were measured by using a suction type Faraday cage to open the panel after repeating display rewriting 100 times on the information display panel and to adsorb particles adhering to the panel substrate. Contrast was visually confirmed between the initial display state and the display state after display rewriting was repeated 5 million times by applying a voltage of ± 150V. Regarding the display quality, the initial display state and the display state after the display rewriting was repeated 5 million times by applying a voltage of ± 150 V were visually confirmed.

<Example 1>
According to Table 1 below, while sputtering the ITO substrate surface with WO _3, were prepared particles 2 composed of coated particles 1 and the insulating particles of WO ₃ on the surface. The prepared particles 1 and 2 were used to enclose between two ITO substrates each having an electrode whose surface was coated with WO ₃ to produce an information display panel. The mixing ratio of the particles 1 and the particles 2 was set to the same weight, and the filling amount of the particles between the substrates was adjusted to 30% by volume. The results are shown in Table 1 below.

<Example 2>
According to Table 2 below, while sputtering the ITO substrate surface with Cu 2 _O, were prepared particles 2 having a particle 1 and Cu 2 _O consisting of insulating particles coating the surface. The prepared particle 1 and particle 2 were used to enclose between two ITO substrates each having an electrode whose surface was coated with Cu ₂ O to produce an information display panel. The mixing ratio of the particles 1 and the particles 2 was set to the same weight, and the filling amount of the particles between the substrates was adjusted to 30% by volume. The results are shown in Table 2 below.

<Example 3>
According to the following Table 3, the particle | grains 2 which consisted of the particle | grains 1 which coated the surface with the electron transport material, and insulating particle | grains were prepared. In addition, the surface treatment of the board | substrate was implemented by carrying out the thin film formation process with the spin coater of the solution equivalent to what was processed into the particle | grains 1 on the ITO board | substrate. The prepared particles 1 and particles 2 were encapsulated between ITO substrates whose surfaces were coated with an electron transporting material in the same manner as in Example 1 to produce an information display panel. The results are shown in Table 3 below.

<Example 4>
According to the following Table 4, the particle 1 of this example was prepared by keeping the particle 1 described in Example 1 as it was, and the particle 2 of this example was prepared by adding an external additive to the particle 2 described in Example 1. The external additive was added by adding the external additive shown in Table 5 and uniformly dispersing it with a Henschel mixer, and attaching the external additive to the particle surface. Note that the surface of the ITO substrate was sputtered with WO ₃ in the same manner as in Example 1. Thereafter, the prepared particles 1 and particles 2 were encapsulated between ITO substrates in the same manner as in Example 1 to produce an information display panel. The results are shown in Table 4 below.

<Comparative Example 1>
According to Table 5 below, the semiconductor treatment was eliminated from Example 1, and particles 1 and 2 and further an ITO substrate were prepared. The prepared particle 1 and particle 2 were encapsulated between ITO substrates in the same manner as in Example 1 to produce an information display panel. The results are shown in Table 5 below.

  From the above results, Examples 1 to 4 according to the present invention are good in charge amount, contrast and display quality at the initial stage and after 5 million times display rewriting, as compared with Comparative Example 1 outside the scope of the present invention. I know that there is. Further, it was found that, among the examples, Example 4 can drive (move) the display medium with a low applied voltage.

  The information display panel of the present invention includes a display unit of a mobile device such as a notebook computer, a PDA, a mobile phone, and a handy terminal, an electronic paper such as an electronic book and an electronic newspaper, a signboard, a poster, a bulletin board such as a blackboard, a calculator, a household appliance, Display unit for automobile supplies, card display unit for point cards, IC cards, etc., electronic advertisement, information board, electronic POP (Point Of Presence, Point Of Purchase advertising), electronic price tag, electronic shelf label, electronic score, RF-ID It is suitably used for a display unit of a device.

(A), (b) is a figure which shows an example of the information display panel of this invention, respectively. (A), (b) is a figure which shows the other example of the information display panel of this invention, respectively. (A), (b) is a figure which shows the further another example of the information display panel of this invention, respectively. It is a figure which shows an example of the shape of the partition in the information display panel of this invention. It is a figure for demonstrating an example of the confirmation method of the rectifying contact of the semiconductor film in this invention. It is a figure for demonstrating an example of the current-voltage characteristic which shows the ohmic contact in the confirmation method of the rectifying contact shown in FIG. It is a figure for demonstrating an example of the current-voltage characteristic which shows the rectifying contact in the confirmation method of the rectifying contact shown in FIG.

Explanation of symbols

1, 2 Substrate 3 Display medium 3W White display medium 3B Black display medium 4 Bulkhead 5, 6 Electrode

Claims (4)

  In an information display panel that displays at least one type of display medium between two opposing substrates, at least one of which is transparent, and displays information such as images by moving the display medium by applying an electric field to the display medium An information display panel, wherein a particle surface of particles constituting a medium and a substrate surface in contact with the particles are made of the same material.   2. The information display panel according to claim 1, wherein the material constituting the particle surface and the substrate surface is an electron transporting material.   2. The information display panel according to claim 1, wherein the material constituting the particle surface and the substrate surface is a hole transporting material.   An information display device using the information display panel according to claim 1 as an information display unit.

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