JP4945127B2 - Information display panel - Google Patents

Description

  The present invention relates to an information display panel for displaying information such as an image by moving a display medium by enclosing a display medium between two opposing substrates, at least one of which is transparent, and applying an electric field to the display medium. It is about.

  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 problems, a display medium is sealed between two substrates, at least one of which is transparent, and an electric field is applied to the display medium, whereby the display medium is moved to display information such as an image. An information display panel to be displayed is known.
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

  In the information display panel described above, the particles constituting the substrate and the display medium, or the particles constituting the display medium are electrically represented by non-electric force such as intermolecular force and liquid crosslinking force and mirror image force. It adheres due to mechanical force. In particular, it is considered that adhesion by electric force is larger than adhesion by non-electric force, and reducing this adhesion is one means for facilitating movement of particles. However, the movement of the particles occurs according to the amount of electric charge that the particles have due to the electric field applied between the substrates, and simply reducing the amount of electric charge does not necessarily achieve good movement. In other words, it is desirable to reduce electrical adhesion while ensuring an appropriate charge amount of particles, but there is still no technology that satisfies such a requirement, and homogeneous and high-quality display is performed on the information display panel. I couldn't.

  The object of the present invention is to solve the above-mentioned problems and to reduce the electric adhesion while ensuring an appropriate charge amount of particles, and as a result, information that can provide a homogeneous and high-quality display. It is intended to provide a display panel.

According to a first aspect of the information display panel of the present invention, at least one kind of display medium is sealed between two opposing substrates, at least one of which is transparent, and the display medium is moved by applying an electric field to the display medium. in the information display panel that displays information such as images, display media, it is composed of a particle for display media having at least optical reflectance and charging property, and the particles having a semiconductor electrical properties on the particle surface, the display medium The ratio of the particles having the electrical characteristics of the semiconductor to the surface of the particles is 0.5% to 10% with respect to the total weight .

According to a second aspect of the information display panel of the present invention, at least two or more types of display media having different optical reflectivities and charging polarities are sealed between two opposing substrates, at least one of which is transparent, In the information display panel for displaying information such as images by moving the display medium by applying an electric field to the display medium, in addition to at least two kinds of display media, particles having semiconductor electrical characteristics on the particle surface are used . proportion of particles having a semiconductor electrical properties the particle surface relative to the total weight and is characterized in Rukoto Do 0.5% to 10%.

Incidentally, as the information a preferred embodiment of the display panel of the present invention, it semiconductor material particle element surface is a hole transporting semiconductor or electron transporting semiconductor, there is.

  According to 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, the display medium is composed of particles for display medium having at least an optical reflectance and chargeability, and particles having semiconductor electrical characteristics on the particle surface. While securing the amount of charge, electrical adhesion can be reduced, and as a result, an information display panel capable of performing homogeneous and high-quality display can be obtained.

  First, the basic configuration of the information display panel of the present invention will be described. In the information display panel 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 an information display panel so that the display medium can move uniformly and 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 attracting each other by the Coulomb force between the particles, an electric mirror image force between the electrode and the substrate, an intermolecular force, a liquid crosslinking force, gravity, and the like can be considered.

  An example of an information display panel that is an object of the present invention will be described with reference to FIGS. 1 (a) and (b) to FIGS. 3 (a) and 3 (b).

  In the example shown in FIGS. 1A and 1B, at least two kinds of display media 3 (here, white display medium particles 3Wa) having at least one kind of particles and having different optical reflectance and charging characteristics. A white display medium 3W composed of a group of particles and a black display medium 3B composed of a group of particles 3Ba for black display medium) are perpendicular to the substrates 1 and 2 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 black display is performed, or the white display medium 3W is visually recognized by the observer and 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 or more types of display media 3 (here, white display medium particles 3Wa) having different optical reflectance and charging characteristics composed of at least one type of particles. Between the electrode 5 provided on the substrate 1 and the electrode 6 provided on the substrate 2 is a voltage between the electrode 5 provided on the substrate 1 and the electrode 6 provided on the substrate 2. In accordance with the electric field generated by applying, the substrate is moved perpendicularly to the substrates 1 and 2 so that the black display medium 3B is visually recognized by the observer and black display is performed, or the white display medium 3W is provided to the observer. A white display is made by visual recognition. In the example shown in FIG. 2B, a cell is formed by providing partition walls 4 between the substrates 1 and 2, for example, in a lattice shape. Further, in FIG. 2 (b), the front partition is omitted.

  In the example shown in FIGS. 3A and 3B, the display medium 3 (in this case, from the particle group of white display medium particles 3Wa) having at least an optical reflectance and a charging property composed of at least one kind of particles. The white display medium 3W is moved in a direction parallel to the substrates 1 and 2 in accordance with an electric field generated by applying a voltage between the electrode 5 and the electrode 6 provided on the substrate 1 to display a white color. The medium 3W is visually recognized by the observer and white display is performed, 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, for example, a lattice-shaped 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.

  The present invention is characterized in that in the information display panel having the above-described configuration, as shown in FIG. 4, the display medium 3 has display medium particles (3Wa, 3Ba) having at least optical reflectance and chargeability. And particles 11 having semiconductor electrical characteristics on the particle surface. Hereinafter, the background of the achievement of the present invention will be described.

  In order to solve the above-described problems, the present inventors have considered in more detail the mirror image force, which is an electric adhesion force. The image force is inversely proportional to the square from the center distance of the charge of the particle (the center of charge of the particle). For example, if the center distance is doubled, the adhesive force is 1/4. Therefore, if the position of the adhering particles is tilted by some kind of stimulus, the center distance of the charge becomes large, and the adhesion force can be greatly reduced while maintaining the charge amount.

  Therefore, if encapsulating using particles other than the display medium particles for image display having the performance of ensuring more stable movement, and driving the display medium particles with the impact accompanying the movement, It is possible to obtain particles for a display medium that exhibits a high-quality image that is more stable in the long term. In order to ensure a more stable movement, it is preferable to have a charging mechanism different from that for the display medium particles.

  The display medium particles retain electric charge by a charging phenomenon caused by contact and friction. However, it is important that the display medium particles are particles having an effect of injecting electric charges from the substrate. The reason is that even when the contact and triboelectric charging properties have deteriorated due to long-term use, it is possible to move particles more stably if charge injection from the substrate is performed. In the present invention, in consideration of this point, the display medium is composed of particles for display medium having at least optical reflectance and chargeability, and particles having semiconductor electrical characteristics on the particle surface. Charge injection from the substrate can be developed using the characteristics of particles having the electrical characteristics of a semiconductor.

  As a suitable specific example, as materials having electrical characteristics of semiconductors, materials having different electrical characteristics and materials having hole transporting semiconductor electrical characteristics and materials having electron transporting semiconductor electrical characteristics are displayed as information. Use either alone or in combination depending on the panel configuration. Further, at least one of two particles facing each other, a particle provided with a material having an electrical property of a hole transporting semiconductor on the surface, or a particle provided with a material having an electrical property of an electron transporting semiconductor on the surface The particle contact surface is electrically in a rectifying contact relationship. Below, the effect at the time of using these materials is demonstrated.

The rectifying contact is a contact in which the electric characteristics do not follow Ohm's law when a foreign substance comes into contact, and the direction of charge flow is directional. A lot of charge flows in the forward direction, and less charge flows in the reverse direction. It is applied to transistors and solar cells. Taking the contact between a hole transporting semiconductor and a metal as an example, the relationship between the two is
A rectifying contact is obtained when the relationship of the Fermi level of the hole-transporting semiconductor <the work function of the metal.

  The present invention has a rectifying effect when the relation Fermi level of hole transporting semiconductor <Fermi level of particle contact surface is satisfied. When the particle contact surface (substrate) becomes positive, it is in the reverse direction, so there is little positive charge flowing into the hole transporting semiconductor particles from the contact surface, while when the particle contact surface (substrate) becomes negative, Therefore, since there are many positive charges flowing from the hole transporting semiconductor particles to the contact surface side, negative charges accumulate in the particles and the particles are negatively charged. The case of the hole transporting semiconductor has been described above as an example, but the phenomenon is exactly the same in the case of the electron transporting semiconductor, only the characteristics are reversed.

  Two-particle type image display when particles having a surface having a material having electrical characteristics of a hole transporting semiconductor and particles having a surface having an electrical property of an electron transporting semiconductor are used as different chargeable particles. It can be suitably used as an apparatus. In this case, the relative relationship of each Fermi level may be (particles having electrical characteristics of a hole transporting semiconductor) <(contact surface) <(particles having electrical characteristics of an electron transporting semiconductor). In order to achieve a stable charge amount and a good electrode surface adhesion state, it is preferable. As a result, charges are always injected from the electrodes into the particles, and a stable charge amount of the particles can be secured even after long-term use and long-term storage, and stable display is possible.

  When particles having semiconductor characteristics are mixed on the surface of the display medium in addition to the display medium particles, the display medium particles aggregate or adhere to the substrate, making it difficult to move. Moreover, the present particles can still exhibit good migration. As a result, even when there are aggregated particles or display particles attached to the substrate, a small amount of semiconductor surface particles move and collide with these particles, and the display medium particles tilt due to mechanical stress. Can weaken the adhesion. In addition, even when the charge has been attenuated, the semiconductor surface particles move and collide with each other, so that triboelectric charging occurs and an appropriate amount of charge can be given. That is, by providing a small amount of semiconductor surface particles, stable movement of the particles can be achieved over a long period of time, and thus high-quality display can be obtained over a long period of time.

  Although it is possible to use all the particles for display medium as semiconductor surface particles, in that case, the production cost of the particles becomes high. Alternatively, particles having a very high conductivity may be used instead of the semiconductor surface particles. In this case, however, when a voltage is continuously applied to the substrate, this time, the polarity is reversed from that of the moved substrate. In some cases, the electric charge is injected and the charged polarity of the conductive particles is reversed, so that the particles are moved to the opposite side again. In order to prevent this, it is necessary to set an appropriate voltage application time and application pattern to the substrate, which leads to an increase in cost of the drive circuit.

  As a method for producing particles having semiconductor electrical characteristics on the surface, the technique is not particularly limited as long as the electrical characteristics of the hole transporting or electron transporting semiconductor described above can be expressed. Used. First, a method of preparing particles (mother particles) as a base and coating the surface with a hole-transporting or electron-transporting semiconductor substance can be presented. Surface coating methods include dry coating by evaporation or sputtering on the surface of the mother particles, or drying and solidifying by introducing the mother particles into a hole-transporting or electron-transporting semiconductor material that has been dissolved or melted. Method, a method of fixing a hole transporting or electron transporting semiconductor substance dissolved and melted in a mother particle into a particle stirring apparatus such as a Henschel mixer, stirring, and further, Examples thereof include a method in which an electron transporting semiconductor substance is dispersed in another resin, and the mixture is coated on the surface of the mother particles by the above-described method.

In order to achieve good charge injection and charge retention, the mother particles preferably have a certain degree of conductivity. Specifically, the volume resistivity is 1 × 10 ¹⁴ Ωcm or less, and further 1 × 10 ¹² Ωcm or less. Preferably there is. There is no restriction | limiting in particular as a base particle material, 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 mother particles, and it is necessary to make particles of a color tone with good visibility.

  As an example of the semiconductor material, 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 (III), copper oxide (I), zinc oxide, and tin oxide (IV).

Furthermore, the low molecular weight organic semiconductors 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-phenylenevinylene), and derivatives thereof.
Furthermore, the thing which doped the impurity to the said substance is also included.

  There are no particular restrictions on the selection of these materials, but the Fermi level should be in the above range, a stable material should be selected, the cost should be low, and there should be no impact on the global environment. It is preferable to select. In the Fermi level, more efficient charge injection can be achieved when the energy gap with the Fermi level of the electrode is larger.

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

  As an addition amount of particles having semiconductor electrical characteristics on the surface added as display medium constituting particles, the mixing ratio is 10% or less, particularly 5% or less, based on the total weight of the other display medium particles. It is preferable that If the mixing ratio exceeds 10%, the semiconductor surface particles affect the display of information such as images, and a high-quality image cannot be obtained. Further, if the mixing ratio is less than 0.5%, a sufficient effect may not be obtained, so the mixing ratio is preferably 0.5% or more.

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

  As for the substrate, at least one substrate is the transparent substrate 2 from which the color of the display medium can be confirmed from the outside of the information display panel, and a material having high visible light transmittance and good heat resistance is preferable. 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 from 2 to 5000 μm, more preferably from 5 to 2000 μm. If it is too thin, it will be difficult to maintain the strength and the spacing uniformity between the substrates, and if it is thicker than 5000 μm, it will be a thin information display panel. Is inconvenient.

  As an electrode forming material when an electrode is provided on an information display panel as required, metals such as aluminum, silver, nickel, copper, and gold, ITO, indium oxide, conductive tin oxide, conductive zinc oxide, etc. Conductive polymers such as conductive metal oxides, polyaniline, polypyrrole, and polythiophene are exemplified and 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 display surface side substrate 2 which is on the viewing side and needs to be transparent needs to be transparent, but the electrode provided on the back side substrate 1 does not need to be transparent. In any case, the above-mentioned material that can be patterned and is electrically conductive 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 1 are the same as those of the electrode provided on the display surface 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 shape of the partition 4 provided on the substrate as necessary is appropriately set according to the type of display medium involved in display, the shape and arrangement of electrodes to be arranged, and is not limited in general. The height of the partition is adjusted to 100 to 100 μm, preferably 3 to 50 μm, and the height of the partition wall to 10 to 100 μm, preferably 10 to 50 μm.
In forming the partition wall, a both-rib method in which ribs are formed on each of the opposing substrates 1 and 2 and then bonded, and a single-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 cells formed by the partition walls made 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. 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.
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. Any of these methods can be suitably used for the information display panel of the present invention, and among these, a photolithography method using a resist film and a mold transfer method are suitably used.

  The display medium of the present invention is composed of at least display medium particles and particles having semiconductor electrical characteristics on the surface. In addition, the display medium may be combined with external additive particles to form a display medium, or other particles. It can be combined to form a display medium. The display medium 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, resol 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.

As yellow colorants, yellow lead, 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 yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, Indanthrene Brilliant Orange RK, Benzidine Orange G, Indanthren 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.

  Further, the particles for display media of the present invention and the particles having semiconductor electrical characteristics on the surface (hereinafter also referred to as particles) have an average particle diameter d (0.5) in the range of 0.1 to 20 μm, and are uniform and uniform. It is preferable. 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 display medium.

Furthermore, in the present invention, regarding the particle size distribution of each particle, the particle size distribution Span represented by the following formula is 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 expressing 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 diameter of 90% or less.)
By keeping Span within a range of 5 or less, the size of each particle is uniform, and movement as a uniform display medium becomes possible.

  Furthermore, regarding the correlation between the particles, the ratio of d (0.5) of the particles having the minimum diameter to 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 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 same as the initial charge amount, the contact with the partition walls, the contact with the substrate, and the elapsed time. It was found that depending on the charge decay, 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, in the information display panel of the present invention, it is important to manage the gas in the gap 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, and preferably 50% RH or less for the humidity of the gas in the gap.
1A, 1B, 3B, 3B, and 3B, the gaps are defined as electrodes 5 and 6 (electrodes on the inner side of the substrate). 2), a gas portion in contact with a so-called display medium excluding an occupied portion of the display medium 3, an occupied portion of the partition wall 4 (when a partition wall is provided), and 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 an information display panel so that the humidity is maintained, for example, filling a display medium, assembling an information display panel, etc. in a predetermined humidity environment, It is important to apply a sealing material and a sealing method that prevent moisture from entering from the outside.

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.
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.

  In addition to the display medium, fine particles used as an external toner additive in electrophotography or the like can be suitably used as the external additive particles constituting the display medium. External additive fine particles include silica, titania, alumina, zirconia, yttria, calcium oxide, magnesium oxide, barium oxide, beryllium oxide, zinc oxide, tin oxide and other metal oxide inorganic fine particles, and a crosslinked resin. Fine particles are exemplified, and silica, titania, and crosslinked resin fine particles are particularly preferably used for this purpose. The surface of the external additive particles is preferably hydrophobized. However, as a result of detailed investigations by the inventors, it is not sufficient to simply coat the surface with a hydrophobic substance (for example, dimethylpolysiloxane). The mechanism of hydrophobic expression is not particularly limited, but it is important that the hydrophilic group on the surface of the external additive particle and the hydrophobic structure form a chemically strong bond with the reactive treatment agent. I found it. This is because the interaction between the hydrophobic substance and the surface of the external additive particle is close to or less than the interaction between the surface of the external additive particle and the hydrophobic substance, or between the substrate and the hydrophobic substance. In this case, the substance is detached from the surface of the external additive particles due to collision between the display medium particles and the display medium particles due to the movement of the display medium particles, and between the display medium particles and the substrate. It is presumed that a strong cohesive force is generated by exposing the surface of the nature.

  Examples of the reactive treating agent used for the hydrophobizing treatment of the external additive particle surface include hexamethyldisilazane, octylsilane, (octyl / decyl / nonyl / (4-isopropylphenyl) / (4-tert Butylphenyl)) (trichloro / trimethoxy / triethoxy) silane, di (pentyl / hexyl / octyl / nonyl / decyl / dodecyl / (4-tert.butylphenyl) octyl / cenyl / nonenyl / -2-ethylhexyl / -3, 3-Dimethylpentyl) (dichloro / dimethoxy / diethoxy) silane, tri (isopropyl / hexyl / octyl / decyl / methyl /) (chloro / methoxy / ethoxy) silane, (dioctylmethyl / octyldimethyl / (4-isopropylphenyl) diethyl ) (Chloro / methoxy / ethoxy) silane, methyl hydrogen (poly) siloxane, methyl hydrogen (poly) siloxane and dimethyl (poly) siloxane Xanthane (random / co) (polymer / oligomer), trimethylsiloxysilicic acid, aluminum (stearate / laurate), iron stearate, acetoalkoxyaluminum diisopropylate, isopropyl (triisostearoyl / tridodecylbenzenesulfonyl) titanate, Isopropyltris (dioctylpyrophosphate) titanate, bis (dioctylpyrophosphate) (oxyacetate / ethylene) titanate, diisopropylbis (dioctylpyrophosphate) titanate, tetraisopropylbis (dioctylphosphite) titanate, tetraoctylbis (ditridecylphosphite) ) Titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl phosphite) titanate, and the like. Further, the treatment method is not particularly limited, but a solution in which the treatment agent is dispersed in a suitable solvent while stirring the external additive particles to be treated with a high-speed rotating blade type agitator such as a Henschel mixer. And after adding and dispersing the target additive particles in a solution in which the treatment agent is dispersed in an appropriate solvent, the resulting solvent is heated and dried while stirring with a mixer. A method is mentioned.

  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.

<Example 1>
As shown in Table 1 below, a white display medium (display medium 1) composed of particles for display medium in which a predetermined external additive is immobilized on the surface of particles 1 including a predetermined charge control agent, and predetermined charge control A black display medium (display medium 2) comprising display medium particles in which a predetermined external additive is immobilized on the surface of the particles 2 containing the agent was prepared. At the same time, as shown in Table 1 below, semiconductor surface particles in which the surface of the mother particle was coated with a surface semiconductor material with a predetermined thickness by a predetermined method were prepared.

  The average particle diameter d (0.5), particle diameter Span, and chargeability were determined for the prepared display medium particles and semiconductor surface particles, respectively. About average particle diameter d (0.5) and particle diameter Span, it measured according to the example mentioned above. The chargeability was measured using a suction type Faraday cage with respect to particles adhering to the panel substrate after the display was rewritten 100 times on the produced information display panel and the panel was opened. The coating thickness of the semiconductor surface particles was measured by cutting the particles and observing the cross section with an SEM. Further, the contact property of the semiconductor material with the substrate was determined according to the following method for confirming rectifying contact.

"Confirming rectifying contact"
Confirmation of rectification can be carried out by examining current-voltage characteristics. First, as shown in FIG. 6, 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. Regarding the preparation of the sample, the electrode was deposited by evaporation, the semiconductor film was deposited by evaporation, or a coating solution dissolved in an arbitrary solvent was formed by spin coating.

  When a voltage is applied between Al and Al, the current-voltage characteristic shows an ohmic contact as shown in FIG. 7, and when a voltage is applied between Al 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 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 ohmic contact as shown in FIG. 7, 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.

  Next, using the prepared white display medium (display medium 1) composed of particles for display medium, black display medium (display medium 2) composed of particles for display medium, and semiconductor surface particles, a white display medium (display medium) 1) between two ITO substrates each having an electrode so that the mixing ratio of the semiconductor surface particles to the total weight of the black display medium (display medium 2) is a predetermined value (2%) shown in Table 1 An information display panel was produced by sealing.

  For the obtained information display panel, the contrast and display quality were determined as the characteristics of the information display panel. The contrast is obtained by measuring the initial display state and the display state after repeating display rewriting 5 million times by alternately applying a voltage of ± 150 V using a reflection image densitometer (RD918, manufactured by Macbeth). It was. As for the display quality, the initial display state and the display state after repeating display rewriting 5 million times by alternately applying a voltage of ± 150 V were visually confirmed. The results are shown in Table 1 below.

<Example 2>
As in Example 1, as shown in Table 2 below, a white display medium (display medium 1), a black display medium (display medium 2), and semiconductor surface particles were prepared, and an information display panel was prepared using these. Was fabricated and the characteristics were examined. The results are shown in Table 2 below.

<Example 3>
As in Example 1, as shown in Table 3 below, a white display medium (display medium 1), a black display medium (display medium 2), and semiconductor surface particles were prepared, and an information display panel was prepared using these. Was fabricated and the characteristics were examined. The results are shown in Table 3 below.

<Example 4>
As in Example 1, as shown in Table 4 below, a white display medium (display medium 1), a black display medium (display medium 2), and semiconductor surface particles were prepared, and an information display panel was prepared using these. Was fabricated and the characteristics were examined. The results are shown in Table 4 below.

<Comparative Example 1>
As in Example 1, as shown in Table 5 below, a white display medium (display medium 1) and a black display medium (display medium 2) were prepared, and information on not mixing semiconductor surface particles using only these was used. A display panel was fabricated and the characteristics were examined. The results are shown in Table 5 below.

<Comparative example 2>
As in Example 1, as shown in Table 6 below, a white display medium (display medium 1), a black display medium (display medium 2), and semiconductor surface particles were prepared, and an information display panel was prepared using these. Was fabricated and the characteristics were examined. In Comparative Example 2, the mixing ratio of the semiconductor surface particles was 15%. The results are shown in Table 6 below.

<Comparative Example 3>
As in Example 1, as shown in Table 7 below, a white display medium (display medium 1), a black display medium (display medium 2), and semiconductor surface particles were prepared, and an information display panel was prepared using these. Was fabricated and the characteristics were examined. In Comparative Example 3, the mixing ratio of the semiconductor surface particles was 0.3%. The results are shown in Table 7 below.

  The following can be understood from Examples 1-4 and Comparative Examples 1-3 described above. First, about the effect of a semiconductor surface particle, the necessity for a semiconductor surface particle is understood by comparing Examples 1-4 and the comparative example 1. FIG. Moreover, it is found that the mixing ratio of the semiconductor surface particles is preferably 0.5% to 10% by comparing Examples 1 to 4 and Comparative Examples 2 and 3.

  The information display panel of the present invention can obtain a reflected image with a wide viewing angle by using the display medium of the present invention, and has a high visibility like a printed paper, such as a notebook computer, PDA, mobile phone. Display devices for mobile devices such as handy terminals, electronic paper such as electronic books and electronic newspapers, billboards such as signboards, posters and blackboards, display units for calculators, home appliances, automobiles, etc. Cards such as point cards and IC cards It is suitably used for a display unit, an electronic advertisement, an information board, an electronic POP (Point Of Presence, Point Of Purchase advertising), an electronic price tag, an electronic shelf label, an electronic score, an RF-ID device display unit, and the like.

(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 for demonstrating a semiconductor surface particle in the information display panel of this invention. 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 electric current-voltage characteristic which shows the rectifying contact in the confirmation method of the rectifying contact shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 Substrate 3 Display medium 3W White display medium 3Wa White display medium particle 3B Black display medium 3Ba Black display medium particle 4 Bulkhead 5, 6 Electrode 11 Semiconductor surface particle

Claims (3)

In an information display panel for enclosing at least one kind of display medium between two opposing substrates at least one of which is transparent and applying an electric field to the display medium to move the display medium and display information such as an image, The display medium is composed of particles for display medium having at least optical reflectance and chargeability, and particles having semiconductor electrical characteristics on the particle surface, and the electrical characteristics of the semiconductor on the particle surface with respect to the total weight of the display medium An information display panel characterized in that the proportion of particles having a ratio of 0.5 to 10% . At least two types of display media having different optical reflectance and charging polarity are sealed between two opposing substrates at least one of which is transparent, and an electric field is applied to the display media to move the display media to In an information display panel for displaying information, in addition to at least two kinds of display media, particles having semiconductor electrical characteristics on the particle surface are used , and the electrical characteristics of the semiconductor on the particle surface with respect to the total weight of the display medium. the information display panel proportion of particles having the characterized Rukoto Do 0.5% to 10%. 3. The information display panel according to claim 1, wherein the semiconductor material on the particle surface is a hole transporting semiconductor or an electron transporting semiconductor.

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