JP4985507B2 - Image forming apparatus, image forming method, and image display medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method and apparatus, capable of satisfying safety and high-speed response and is capable of forming images on a repeated rewritable image display medium, and to provide the image display medium. <P>SOLUTION: The image display medium 10 is constituted, by encapsulating black particles 18 and white particles 20 between a display substrate 14 that consists of dielectric, and a non-display substrate 16. First, a printing electrode 11 applies an AC voltage and brings black particles 18, and white particles 20 is subjected to tribo-charging. Next, a DC voltage according to an image is applied between the substrates. The black particles, deposited on the part of the display substrate 14 (non-image part) where a voltage is applied, move to the non-display substrate 16 side. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus, an image forming method, and an image display medium, and in particular, an image forming method, an image forming apparatus, and an image display medium capable of forming an image on an image display medium that can be rewritten repeatedly. About.

  Conventionally, as image display technology called so-called electronic paper that can be repeatedly rewritten, there are known technologies such as rotation of colored particles (Twisting Ball Display), electrophoresis, thermal rewritable, liquid crystal having memory properties, and electrochromy. Yes. Among the display technologies, thermal rewritable media, memory liquid crystal, etc. are excellent in image memory properties, but the display surface cannot be made sufficiently white display like paper, and therefore when displaying an image. There is a problem in that it is difficult to visually distinguish between a portion where an image is displayed and a portion where an image is not displayed, that is, the image quality is deteriorated.

  In addition, Twisting Ball Display has a display memory property, and oil is present only in the cavity around the particle inside the image display medium. However, since it is almost solid, it is relatively easy to form a sheet. However, even if the white-coated hemisphere is perfectly aligned on the display side, the light that enters the gap between the spheres is not reflected and is lost internally, so in principle white display with 100% coverage There is a problem that it is not possible to do so, and it becomes slightly grayish. In addition, since the particle size is required to be smaller than the pixel size, fine particles with different colors must be manufactured for high-resolution display, which requires advanced manufacturing techniques. There is also a problem.

  In such a technique, as an image display medium to be displayed using toner, conductive colored toner and white particles are sealed as air medium between a display substrate and a non-display substrate facing each other. There is an image display medium in which a charge transport layer and an electrode are formed inside (Non-patent Document 1). In such an image display medium, a charge is injected into the conductive colored toner through the charge transport layer, and the charged conductive conductive toner is moved by an electric field between the substrates formed according to the image by the electrodes. Adhere to the display substrate. As a result, an image as a contrast between the conductive colored toner and the white particles is displayed on the display substrate side.

An image display medium using electrophoresis is known as an image display medium that can be rewritten repeatedly (Non-patent Document 2).
Toner Display, Imaging Society of Japan, Japan Hardcopy '99 Proceedings p249-p251, Japan Hardcopy '99fall Proceedings p10-p13 Kawai: Development of electrophoretic display using microcapsules, Imaging Society of Japan, Electronic Imaging Study Group, p31, 1999

  However, the image display technology using the toner described above has a low contrast between black and white, and has not obtained excellent results as compared with other image display technologies. As a cause of this, a reporter of this technology has a conductive colored toner that is not in contact with the charge transport layer provided on the inner surface of the electrode of the non-display substrate and is isolated from other conductive colored particles, These isolated conductive colored particles are presumed to have a low contrast because they are not injected by electric charge and are randomly moved in the substrate without being moved by an electric field. There was also a problem with high-speed response.

  Further, since the image display medium using the above toner uses electrodes, the electrostatic latent image formed on the conventional image carrier is developed with toner, and the image is transferred by transferring the toner image onto recording paper. It cannot be used as it is for an image forming apparatus such as a copying machine or a printer to be formed.

  On the other hand, the display technology using electrophoresis or magnetophoresis is superior in white display but black (color) display because it has image memory properties and is a technology in which colored particles are dispersed in a white liquid. Since the white liquid always enters the gaps between the colored particles, the portion is grayish and the contrast is deteriorated.

  The present invention has been made in view of the above-described facts, and satisfies the high contrast, safety, and high-speed response, and can form an image on an image display medium that can be repeatedly rewritten, An object of the present invention is to provide an image forming apparatus and an image display medium, and to provide an image forming method and an image forming apparatus that can be shared with a copying machine and a printer that form an image on a recording sheet at low cost. It is.

  In order to achieve the above object, the invention described in claim 1 is a plurality of substrates having a plurality of colors and charging characteristics that are enclosed between the substrates so as to be movable between the substrates by an applied electric field. An image forming apparatus for forming an image on an image display medium comprising a kind of particle group and a photoconductive layer formed on one of the pair of substrates, wherein a voltage is applied between the pair of substrates. And a transmissive panel formed in a pattern corresponding to an image, and a light source for irradiating the transmissive panel with light.

  According to the first aspect of the present invention, the voltage applying means applies a voltage between the pair of substrates. For example, an image display medium in which a photoconductive layer is formed on one of a pair of substrates, or an image display medium in which at least one of the particle groups includes a photoconductive material is sandwiched between substrates with electrodes. For example, a DC voltage is applied. A transmissive panel formed in a pattern corresponding to an image is applied to the substrate on the side on which the photoconductive layer is formed, and the transmissive panel is irradiated with light from a light source, that is, exposed. Here, the photoconductive layer acts as a dielectric layer in the non-exposed state, and acts as a conductive layer in the exposed state. Therefore, in the exposure state, the particles applied between the substrates move according to the image by the voltage applied by the voltage applying means, and an image is formed.

  The invention according to claim 2 includes a pair of substrates, and a plurality of types of particle groups that are enclosed between the substrates so as to be movable between the substrates by an applied electric field, and that have different colors and charging characteristics. An image forming apparatus for forming an image on an image display medium, comprising: a latent image carrier; an electrostatic latent image forming unit that forms an electrostatic latent image according to an image on the latent image carrier; and the image display A counter electrode for generating an electric field between the medium and the latent image carrier, the charging means for precharging the particle group; It is provided with.

  According to the second aspect of the present invention, the particles can be sufficiently moved between the substrates by charging the particle group in advance by the charging means, and an image can be stably displayed.

  The charging means applies at least one of a DC voltage and an AC voltage to the substrate as described in claim 3. Here, when a DC voltage is applied to the substrate, it is not necessary to apply a bias to the counter electrode because the particle group can be uniformly attached to one substrate side. In addition, when an alternating voltage is applied, the particle group can be sufficiently charged. According to a fourth aspect of the present invention, the charging unit may be a vibrating unit that vibrates the substrate. Further, as described in claim 5, when the image display medium in which at least one of the particle groups is magnetic is charged in advance, the charging means applies an alternating magnetic field to the substrate. May be.

  According to the invention described in claim 6, it includes a pair of substrates and a plurality of types of particle groups that are enclosed between the substrates so as to be movable between the substrates by an applied electric field and that have different colors and charging characteristics. By applying an alternating electric field immediately before applying an electric field according to image information to an image display medium characterized in that at least two kinds of particle groups are different from each other in chargeability, In addition, since the particles are forcibly vibrated between the substrates, the particles adhering to the substrate surface can be peeled off to facilitate the movement of the particles according to the image.

  According to the seventh aspect of the invention, immediately before applying the electric field according to the image information, the alternating electric field is simultaneously applied to the entire surface of the image display medium, thereby moving the particles in the substrate in a short time. can do. This is effective when the particles are moved by applying an electric field between the substrates by using electrodes of characters or patterns, or when the particles are moved by applying an electric field between the substrates by using an electrode having a matrix structure.

  According to the eighth aspect of the present invention, in the sequence for applying the electric field in units of rows by the matrix electrode, the alternating electric field is applied immediately before the electric field corresponding to the image information is applied, thereby sending a signal for simultaneous driving of the entire surface. Without forcing a new sequence or wiring, the particles are forcibly vibrated on the entire surface immediately before the image display, so that only the devices necessary for image display can move the particles according to the image without increasing the number of special devices. Can be promoted.

  According to the ninth aspect of the invention, by gradually reducing the amplitude of the alternating electric field with time, an increase in the moving speed accompanying an increase in the amount of charge due to frictional charging of the particles is prevented, and the moving speed of the reciprocating particles is gradually increased. The adhesion between the particles and between the particles and the substrate is reduced, so that the particles can easily move according to the electric field.

  According to the invention of claim 10, by making the voltage waveform of the alternating electric field rectangular, the force acting on the particles by the electric field per unit time increases, so that the responsiveness to the electric field is increased, and the particles are formed in a shorter time. It can move to the opposite surface.

  By the way, in the process of making the present invention, the present inventors presume the following problems of the display medium using the toner. That is, the image display medium using the toner described above is configured such that the white particles are handled as a static medium that does not react with an electric field, and the black conductive particles migrate in the white medium. For this reason, only one of the two types of particle groups (black conductive particles) can move between the substrates. Specifically, the structure in which the white particles are sufficiently packed between the substrates makes it possible to fix the white particles in a substantially stationary state. However, in this configuration, one of the black conductive particles must move in the high-density white particles, and furthermore, it is difficult for the black conductive particles to exclude the white particles that have stayed near the substrate surface. It is assumed that only the grayish color can be displayed and the contrast is lowered.

  In addition, when using conductive particles, particles that do not touch the electrode for direct charge injection have no opportunity for charge injection unless there is an opportunity to make contact with other charged conductive particles. Should not react. In other words, even if black conductive particles with good chargeability are used as individual characteristics, most black conductive particles cannot move in the state where white particles that do not move exist, contributing to image display. It is assumed that there was not.

  Therefore, in the present invention, the image display medium is configured such that particles belonging to different particle groups can move between the substrates in opposite directions by the applied electric field. Furthermore, since these particles have different charging characteristics depending on the particle group, the movement characteristics by the electric field are also different.

  When using reverse-polarity insulating particles, each particle group is in a state of being mixed by the Coulomb force between the substrates immediately after encapsulation, and by applying an electric field greater than the Coulomb force between these particles, The polar particles are separated and move in the direction of the electric field of opposite polarity and adhere to the substrate surface. Even if the electric field is cut off, the particles are held on the substrate side by the image force and van der Waals force. Note that each particle group is deposited on the substrate side, and in practice, the applied voltage at the time of rewriting may be an external force greater than the image force and the van der waals force.

  When conductive particles are used, if each type of particle group can move between the substrates, the movement of the conductive particles will be good, and the probability that the particles will be in contact with each other increases and exists between the substrates. The number of charges supplied to the charged non-charged particles increases, and these particles can also start to move by an electric field.

  In the case of particles with the same polarity but different charging characteristics and different responsiveness to the electric field, the particles should have high fluidity between the particles because they are the same polarity in the first place. If it is too much, it may also aggregate due to van der Waals force. In the present invention, the particles are sealed so as to be movable between the substrates in accordance with the direction of the electric field, so that the particles can be moved smoothly and an image display with good responsiveness can be performed. In this case, it is possible to change the color by first attaching particles having a large charge amount and further attaching particles having a low charge amount by further increasing the electric field.

  As other combinations, it is also possible to use a combination of conductive particles and insulating particles, and two types of conductive particles having conductive characteristics of different conductivity types such as a hole type and an electronic type.

  However, even when any combination of particles is used, it is preferable that at least two types of particle groups have charging characteristics of different polarities. As described above, since the polarities are opposite, each moves in the opposite electric field direction and the response is extremely good. Furthermore, since the particles are clearly separated depending on the polarity, the contrast and sharpness of the image are improved. In particular, when white particles that are oppositely charged to each other and particles that exhibit other colors are used, it is possible to display an image as if it were printed on paper.

  Further, if the opposite polarity particles are insulating particles, frictional charge between the particles is generated during movement by the electric field and the charge amount is increased, so that the effect of improving the image memory characteristics when there is no electric field is also achieved.

  Here, “movable between the substrates” means that particles existing on one substrate side can move to the other substrate side by applying an electric field. In addition to the case of moving, particles of a certain particle group do not move depending on a certain electric field strength, but include cases where the particles can move if the electric field strength is increased. That is, as long as the particles are sealed in such a state, the movement of the particles is not substantially hindered by the presence of particles of other types of particle groups.

  In addition, in order to allow each type of particles to move between the substrates, the filling rate of the particles in the substrate, the fluidity between the particles, the particle shape, the particle diameter, the material of the particle, the inner surface of the substrate (the particle and the electrode are in direct contact) In this case, any one or a plurality of electrode surfaces may be set in combination.

  An image can be displayed if the filling rate of all particles contained between the substrates is 0.1% or more and 50 vol% or less, but 40% or less, particularly 25% or less, is preferable because the image contrast is good. If it exceeds 50%, the particles suddenly become dense and their movement begins to be inhibited, and the proportion of particles that remain on one substrate side increases, leading to a decrease in contrast. If it is 50% or less, each particle can move between the substrates.

  A higher fluidity between particles is preferred. For this reason, the outer shape of the particle is preferably a curved surface. A spherical shape such as an elliptical sphere is more preferable, and a true sphere is more preferable. In order to increase the fluidity, addition of an external additive that reduces the frictional force may be combined.

  The particle diameter is not limited as long as it can be moved by the applied electric field, but the average particle diameter is preferably 1 μm or more. If it is 1 μm or less, the bond force between particles or particle / substrate becomes more dominant than van der Waals force than coulomb force, and it becomes difficult to separate particles of opposite polarity by an electric field. End up. However, if particles can be separated by combining a force other than an electric field such as ultrasonic vibration, it may be used even if it is smaller than 1 μm. In particular, when it is required to have a high memory property of an image, it is better to make it smaller than 1 μm, and it is better to make it 1 μm or more if the rewriting device is simplified or rewriting is performed at high speed.

  As the combination of the particle and the part that contacts the particle such as the substrate material or the electrode, it is preferable to select the one having a small mutual adhesion force, so that the movement of the particle between the substrates is facilitated. . The substrate surface may be flat or may be a scattering surface (particularly the observation surface side of the back side substrate).

  It is also possible to enclose a transparent insulating solvent between the substrates and move two or more kinds of colored particles electrophoretically. That is, the contrast of the image can be increased as compared with the case where the colored particles are electrophoresed in the conventional white insulating liquid.

  However, since the movement of the particles is hindered by the viscosity of the solvent, the high-speed response is inferior, and the color of the colored particles on the back side may deteriorate due to refraction and scattering of incident light by the solvent. Therefore, it is most preferable that each type of particle group is sealed in a vacuum or in particular in a gas such as air in consideration of ease of handling in use and manufacturing.

  As a charging method of each particle, in addition to a method of charging by an electric field after encapsulation, charging can be performed by previously mixing a plurality of types of particle groups, and then encapsulating between the substrates. Further, in the case of insulating particles, it is possible to charge the particles with opposite polarities by shaking the display medium itself after encapsulating and stirring and frictionally charging the particles.

Also, the average charge amount (fC / number) of particles is roughly proportional to the square of the average particle diameter 2r of the particles, and the smaller the average particle size, the smaller the average charge amount (fC / number). It was found that the preferable range of the average charge amount is also different. That is, the average amount of charge of each particle ^{± 5 × (r 2/10} 2) fC / ^{FOB, ± 150 × (r 2/} 10 2) fC / number less. When the average charge amount ^{5 × (r 2/10 2} ) fC / Pieces smaller, but the particles are transported between the substrates and separated into different directions, do not exhibit sufficient display density. Also, when ^{150 × (r 2/10 2} ) fC / number greater than, the particles do not separate, moving in the same direction becomes aggregate, display density contrast also becomes smaller. The charging characteristics of the particles can be controlled by the material constituting the particles, the external and internal additives added to the particles, the layer structure of the particles, the shape of the particles, and the like.

At least one kind of particles in the particle group contains an additive on the surface thereof, and the additive contains a titanium compound obtained by a reaction between TiO (OH) ₂ and a silane compound. Since stable charge maintenance and good fluidity are given to the particle group, the electric field applied between the substrates can smoothly and stably move between the substrates without the particles firmly adhering to the inner surface of the substrate. An image can be displayed with high contrast.

  Therefore, by applying an electric field according to the image, the particle group moves according to the image, and the image can be displayed with the color contrast of the particle group. In addition, even when the electric field disappears, the particles that have moved onto the substrate remain in place by the image force and the adhesion force, and can retain an image. After a lapse of time, when the electric field is applied again, the particles can move again. Thus, an image can be repeatedly displayed by applying an electric field from the outside according to the image. Note that there may be at least two kinds of colors of the particle group. Note that the particle group may have a charge transport property. For the pair of substrates, an insulating material such as a dielectric, a conductive material, or a charge transport material can be used. That is, as the image display medium, for example, one having the configuration described in claims 11 to 27 can be used. Here, FIG. 43 shows a table of combinations of particles and substrates capable of obtaining contrast, that is, capable of image display.

  Here, each code | symbol in a table | surface shows the following content. A blank in the table indicates that the contrast cannot be obtained, that is, the image display cannot be displayed.

  Next, symbols in the table will be described. The alphabet represents the particle charging process.

  A: The first particles and the second particles are charged according to the electric field between the members by being charged in the opposite direction by frictional charging in advance, and adhere to the opposite members to obtain contrast.

  B: Either one of the particles is charged by being charged from the substrate and moves according to the electric field between the members. The other particle is charged by friction caused by movement of one particle or friction caused by stirring or vibration in advance, and moves according to the electric field between the members.

  C: Both the first particles and the second particles are charged by being charged by the substrate and move according to the electric field between the members.

  Next, dashes (B ′, C ′) given to the alphabet indicate from which member particles are charged.

  No dashes (B, C): Charges are injected into the particles from both the first and second members.

  One with a dash (B ', C'): Charge is injected into the particle from only one member.

  Further, the encircled numbers indicate how the particles behave when the electric field is applied between the members to obtain the contrast.

  Circle 1: The first particle and the second particle adhere to the opposite members to obtain a contrast.

  Circle 2: Conductive particles injected with charge from members receive charge injection from both members and are charged to vibrate between the members. At the same time as the electric field is lost, the particles adhere to both members, so half of them adhere to both members. However, since the other particle receives charge injection only from one member, it adheres to the one member by an electric field. Therefore, contrast can be taken.

  Circle 3: The conductive particles always adhere to the same member regardless of the electric field polarity. The other particle moves according to the electric field polarity between the members. Therefore, contrast can be obtained depending on the amount of adhesion of the other particle.

  In addition, in the particles showing the hole transport property, electron transport property, and conductivity of the front hollow column part, triboelectric charge is generated by mixing and stirring the first particle and the second particle, and charged to different polarities, In the case where the charge of each particle is not neutralized or charged to the same polarity by the charge injection received from the substrate or the contact between the particles, this is not the case and the contrast can be obtained.

  As described above, according to the present invention, an image is formed by moving a plurality of types of particles having different colors and charging characteristics, which are movably enclosed between a pair of substrates by an applied electric field, according to an image. Therefore, it is possible to repeatedly rewrite and to have an effect of excellent display image contrast, safety and responsiveness.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an image display medium and an image forming apparatus for forming an image on the image display medium according to the present embodiment.

  The image forming apparatus 12 according to the first embodiment includes a voltage applying unit 201 as shown in FIG. The image display medium 10 has a configuration in which a spacer 204, black particles 18, and white particles 20 are sealed between a display substrate 14 on the image display side and a non-display substrate 16 facing the display substrate 14. It has become. The display substrate 14 and the non-display substrate 16 are provided with a transparent electrode 205 as will be described later. However, the transparent electrode 205 of the non-display substrate 16 is grounded, and the transparent electrode 205 of the display substrate 14 is a voltage applying unit. 201 is connected.

  Next, details of the image display medium 10 will be described. For the display substrate 14 and the non-display substrate 16 constituting the outside of the image display medium 10, for example, a 7059 glass substrate with a transparent electrode ITO of 50 × 50 × 1.1 mm is used. The inner surface 206 that contacts the glass substrate particles is coated with polycarbonate resin (PC-Z) to a thickness of 5 μm. A central portion of a 40 × 40 × 0.3 mm silicon rubber plate 204 is cut into a 15 × 15 mm square to form a space, and this silicon rubber plate is placed on the non-display substrate 16. Spherical fine particles of titanium oxide-containing crosslinked polymethylmethacrylate having a volume average particle size of 20 μm mixed with titania fine powder treated with isopropyltrimethoxysilane at a ratio of 100 to 0.4 (Techpolymer MBX- manufactured by Sekisui Plastics Co., Ltd.) 20-white) and spherical fine particles of carbon-containing crosslinked polymethyl methacrylate having a volume average particle size of 20 μm (classified by Sekisui Plastics Co., Ltd. Techpolymer MBX-20-Black), a weight ratio of 2 to 1. Then, about 15 mg of the mixed particles are shaken off through a screen into a space cut out into a square of the silicon rubber plate. Thereafter, the display substrate 202 is brought into intimate contact with the silicon rubber plate, the two substrates are pressed and held with a double clip, and the silicon rubber plate and the two substrates are brought into intimate contact to form the image display medium 10.

  The driving state of the image display medium 10 will be described with reference to FIG. When a DC voltage of 200 V is applied to the transparent electrode of the display substrate 14, some of the negatively charged white particles present on the non-display substrate 16 side move to the display substrate 14 side due to the action of an electric field, and a DC voltage of 500 V or more is applied. When applied, many white particles move to the display substrate 14 side and the display density is almost saturated. At this time, the positively charged black particles move to the non-display substrate 16 side. Here, even when the voltage was set to 0, the particles on the display substrate did not move and the display density did not change.

  Next, even if a DC voltage of −100 V is applied on the transparent electrode of the display substrate 14, the particles do not move. When a DC voltage of −200 V is applied to the transparent electrode of the display substrate 14, some of the positively charged black particles on the non-display substrate 16 side move to the display substrate 14 side due to the action of an electric field, and the DC voltage − When 500 V or more is applied, many black particles move to the display substrate 14 side and the display density is almost saturated. At this time, the negatively charged white particles move to the non-display substrate 16 side. Here, even when the voltage was set to 0, the particles on the display substrate did not move and the display density did not change.

  As described above, there is a dead zone where particles do not move with respect to the magnitude of the applied voltage, and there is a voltage threshold for particle movement. This characteristic is suitable for simple matrix driving.

  Next, the operation of the first embodiment will be described.

  The white particles 20 added with and mixed with titania fine powder treated with isopropyltrimethoxysilane are charged to an appropriate negative polarity by frictional charging between the black particles 18 and the substrate inner surface 206. The average charge amount of the white particles 20 was −16 fC, and the average charge amount of the black particles 18 was +16 fC. The substrate inner surface at this time is polycarbonate resin (PC-Z). The material of the substrate inner surface 206 has a great influence on the charging polarity of the particles, and must be selected as appropriate. The fine powder of titania treated with silane has the effect of suppressing the chargeability of the particles to an appropriate level that is not too high and maintaining the fluidity of the particles at a high level.

  The addition amount of the titanium compound is appropriately adjusted based on the balance between the particle size of the particles and the particle size of the fine powder. If the amount added is too large, fine powder released from the surface of the white particles is generated, which adheres to the surface of some of the black particles 18, and the charged polarity of the black particles 18 and the white particles 20 becomes the same. Moving in the same direction. The amount of the titanium compound varies depending on the particle size of the particles, but is 0.05 to 1.0 parts by weight, more preferably 0.1 to 0.5 parts by weight with respect to 100 parts by weight of the particles.

  Moreover, it is desirable to add the fine powder to the particles only to either the white particles 20 or the black particles 18. When externally added fine powders of different polarities to a plurality of particles, the released fine powders of different polarity are strongly aggregated and easily form particle aggregates. Deteriorating. When adding a fine powder to two or more kinds of particles, it is desirable that the fine powder be applied to the particle surface with an impact force, or the particle surface is heated to fix the fine particles to the particle surface so that they are not easily released.

  In addition, since the shape of the particles used in this embodiment is a true sphere, the contact between the particles is almost a point contact, and the contact between the particle and the inner surface of the substrate is also almost a point contact. Adhesion based on van der Walls force with surface 206 is small. Therefore, even if the substrate inner surface 206 is a dielectric, the charged particles can move smoothly in the substrate by the electric field.

  In addition, since particles containing titanium oxide, which is one of the inorganic pigments with high hiding power, are used, the white particles 20 covering almost the entire surface of the substrate inner surface 206 with an area ratio of 70% can give a high white density. FIG. 32 shows the relationship between the area ratio of the white particles 20, the area ratio of the black particles 18, and the display density. The mixing ratio of the white particles 20 and the black particles 18 at this time is 2: 1. It covers almost the entire surface with an area ratio of 70% and is close to the saturated concentration.

  Further, by making the particle diameters of the white particles 20 and the black particles 18 substantially equal, adhesion and aggregation between the particles can be avoided, so that a high white density and black density can be obtained. When one particle size is small, it adheres to the periphery of large particles and lowers the original color density. The contrast also changes depending on the mixing ratio of black and white particles. The vicinity of the mixing ratio in which the surface areas of the two particles are equal is desirable. If it deviates greatly from this, the color of the particles having a large ratio becomes strong. However, this is not the case when it is desired to provide contrast by displaying the same color with a dark color tone and a light color tone, or when it is desired to display with a color created by mixing two kinds of colored particles.

Next, other substances are listed. Known fine powders to be mixed with the particles include silicon oxide (silica) and titanium oxide. These are modified by reacting and drying a silane compound, a silane coupling agent, or silicone oil to adjust the positive and negative chargeability, fluidity, environment dependency, and the like. Well-known hydrophobic silica and hydrophobic titanium oxide can be used. In particular, a titanium compound obtained by a reaction of TiO (OH) ₂ and a silane compound such as a silane coupling agent described in JP-A-10-3177 is suitable. This titanium compound is produced by reacting TiO (OH) ₂ produced in a wet process with a silane compound or silicone oil and drying it. Since it does not pass through the firing step of several hundred degrees, a strong bond between Ti is not formed, there is no aggregation, and the particles are almost primary particles. Furthermore, since the silane compound or silicone oil is directly reacted with TiO (OH) ₂ , the amount of treatment can be increased, the charge can be controlled by the amount of the silane compound treated, and the chargeability that can be imparted is also conventional. This is a significant improvement over titanium oxide.

  Here, as the silane compound, any of chlorosilane, alkoxysilane, silazane, and a special silylating agent can be used. Examples of the silicone oil include dimethyl silicone oil, alkyl-modified silicone oil, α-methylsulfone-modified silicone oil, chlorophenyl silicone oil, fluorine-modified silicone oil, and amino-modified silicone oil. As the white particles 20, in addition to the above spherical fine particles of titanium oxide-containing cross-linked polymethyl methacrylate (MBX-white manufactured by Sekisui Plastics Co., Ltd.), spherical fine particles of cross-linked polymethyl methacrylate (Chemisnow manufactured by Soken Chemical Co., Ltd.) MX) with fine powder of titanium oxide pigment added and mixed, with white powder fine powder implanted into the spherical fine particles by impact force and fixed on the fine particle surface, styrene resin, phenol resin, silicone resin, glass, etc. Examples thereof include particles in which fine powder of white pigment is adhered or embedded on the surface of mother particles made of various materials. Spherical fine particles of cross-linked polymethylmethacrylate (Kemisnow MX manufactured by Soken Chemical Co., Ltd.) are monodispersed and have a uniform particle size, the chargeability of each particle is uniform, and the threshold of particle movement relative to the electric field becomes sharper At the same time, high contrast can be obtained. Examples of the white pigment include titanium oxide, magnesium oxide, and zinc oxide. Further, examples of white particles include porous sponge-like particles enclosing air and hollow particles. Further, toners used in copying machines and printers, particularly spherical particles produced by a wet method such as a polymerization method or a suspension method are also included.

  As the black particles 18, in addition to the above-mentioned spherical fine particles of crosslinked polymethyl methacrylate (MBX-black manufactured by Sekisui Plastics Co., Ltd.), true spherical particles (Sekisui Co., Ltd.) made of a crosslinked copolymer mainly composed of divinylbenzene. Chemical Industry Co., Ltd. Micropearl BB, Micropearl BBP), Amorphous carbon fine particles (Unitika Unibex GCP) fired from phenol resin particles, Spherical fine particles of carbon and graphite (Nika Beads ICB, Nippon Carbon Co., Ltd., Nika Beads) MC, Nikabeads PC). Furthermore, in addition to white and black particles, colored particles such as red, blue, green, magenta, cyan, yellow, gold, and silver can be used. For example, spherical microparticles of crosslinked polymethylmethacrylate (MBX-Red, manufactured by Sekisui Plastics Co., Ltd.), microparticles made of a crosslinked copolymer containing divinylbenzene as the main component, electroless nickel plating, and gold substitution There are plated spherical conductive particles (Micropearl AU (trade name) manufactured by Sekisui Chemical Co., Ltd.). Further, toners used in copying machines and printers, particularly spherical particles produced by a wet method such as a polymerization method or a suspension method are also included.

  As an example, magenta colored spherical particles are prepared as follows. 100 parts by weight of polyester resin, C.I. I. 4 parts by weight of Pigment Red 57 and 110 parts by weight of ethyl acetate are dispersed in a ball mill for 48 hours to prepare Liquid A, while 100 parts by weight of a 2% aqueous solution of carboxymethylcellulose is prepared to prepare Liquid B. Next, 100 parts by weight of Liquid B was stirred with an emulsifier, and 50 parts by weight of Liquid A was slowly added to suspend the liquid mixture. Thereafter, ethyl acetate was removed under reduced pressure, washed with water, dried and classified to obtain magenta colored particles. The average particle size of the particles was 7 μm. The red particles and the white particles were mixed at a weight ratio of 1: 5, sealed between the substrates, and an electric field was applied to obtain a display with red and white contrast.

  By the above, a particle group having excellent chargeability, fluidity, and environmental stability is obtained, and an electric field is applied between the substrates in which the particle group is encapsulated, and the particle group is moved, so that a high black density is obtained. White density and high contrast display.

Example 1
Next, examples of the first embodiment will be described.

  With respect to the image display medium 10 according to the first embodiment, the dependence of the filling rate and the movement characteristics between the white particles 20 and the black particles 18 between the substrates was tested, and the results shown in Table 1 were obtained. The average particle diameter of the black particles 18 is 20 μm, the average particle diameter of the white particles 20 is 20 μm, and the mixing ratio of the black particles 18 and the white particles 20 is 1: 2 (weight ratio). At this time, the true specific gravity of the black particles 18 was 1.23, and the true specific gravity of the white particles 20 was 1.85. The filling rate is expressed by (total particle volume / inter-substrate volume).

表１の結果から、粒子の充填率を５０％以下となるように粒子群の粒子を封入するとすれば各粒子が基板間を移動可能となることがわかった。また、充填率を４０％以下とすることで画像のコントラストをとることできる程度に粒子を移動させることが可能となり、特に充填率を２５％以下とすることにより、粒子をより移動しやすくすることができることがわかった。

From the results in Table 1, it was found that each particle can move between the substrates if the particles of the particle group are sealed so that the particle filling rate is 50% or less. In addition, by setting the filling rate to 40% or less, it becomes possible to move the particles to such an extent that the contrast of the image can be taken. In particular, by making the filling rate 25% or less, the particles can be moved more easily. I found out that

Further, when the filling amount is less than 3 mg / cm ² , the black density is slightly lowered to 1.2 as in Example 7. When the filling amount is 3.8 mg / cm ² or more, as shown in FIG. 41, the projected area ratio of particles adhering to the display substrate surface becomes 70% or more, and approximately one particle layer is formed on the inner surface of the substrate. Sufficient black density (1.4 or more) is formed. A more preferable filling amount is 6 to 12 mg / cm ² . Therefore, the filling amount is required to be approximately 3 mg / cm ² or more from the viewpoint of concentration. As shown in FIG. 42, if the inter-substrate gap is enlarged, a sufficient concentration can be obtained even at a lower filling rate, so the lower limit of the filling rate depends on the size of the inter-substrate gap. When the distance between the substrates is 15 mm as in Example 12, the filling rate is about 3 mg / cm ² at a filling rate of 0.12%. Therefore, the filling rate is required to be approximately 0.1% or more from the viewpoint of concentration.

  Further, from the viewpoint of display density, a preferable filling state of the particles filled between the substrates is that the projected area ratio of the particles adhering to the display substrate surface is 30% or more (display black density is 0.8 or more), preferably 50%. It is above (display black density is 1.2 or more), more preferably 60% or more (display black density is 1.3 or more) (see FIG. 41).

  Note that the filling amounts shown in Table 1 and FIG. 42 are values in the image display medium 10 of the first embodiment, and are values that vary depending on the specific gravity of the particles used.

(Example 2)
Next, the mixed particles are sealed in a sample bottle having an inner wall coated with a display substrate inner surface material (polycarbonate resin) and sufficiently stirred until the charge amount is saturated with a stirrer. The average charge amount of each particle measured with a spectrograph was measured. Further, the particle group was sealed between the substrates, and a voltage was applied between the substrates to investigate the electric field mobility and display concentration of the particles. The results are shown below.

平均粒子径２０μmの各粒子の平均帯電量が５〜６０fC/個で、粒子は分離して異方向へ基板間を移動し、十分な表示濃度を示した。一方平均帯電量が３fC/個では、粒子は分離して異方向へ基板間を移動するものの、十分な表示濃度を示さなかった。また、粒子の帯電極性が同極性で平均帯電量も同等の場合はやはり分離せず、同じ方向へ移動し表示濃度コントラストが取れなかった。さらに、帯電量が１６５fC/個では粒子は分離せず、凝集体となり同じ方向へ移動し、表示濃度コントラストも小さくなってしまった。

The average charge amount of each particle having an average particle diameter of 20 μm was 5 to 60 fC / particle, and the particles were separated and moved between the substrates in different directions, showing a sufficient display density. On the other hand, when the average charge amount was 3 fC / particle, the particles separated and moved between the substrates in different directions, but did not show a sufficient display density. Further, when the charged polarity of the particles was the same polarity and the average charge amount was the same, the particles were not separated and moved in the same direction, and the display density contrast could not be obtained. Further, when the charge amount is 165 fC / particle, the particles are not separated, become aggregates, move in the same direction, and display density contrast becomes small.

The average charge amount (fC / piece) of each particle is approximately proportional to the square of the average particle diameter 2r of the particle, and the average charge amount (fC / piece) decreases as the average particle diameter decreases. Accordingly, when considering this, generally the average charge amount of the particles is ^{5 × (r 2/10 2} ) fC / FOB, be a ^{150 × (r 2/10 2} ) fC / number less, necessary for image display It was found that it is preferable to obtain a high display density contrast.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 33 shows an image display medium 401 using a simple matrix and an image forming apparatus 12 for forming an image on the image display medium 10 according to the present embodiment. The electrodes 403An and 404Bn (n is a positive number) have a simple matrix structure, a plurality of particle groups having different charging properties are enclosed in a space between the electrodes 403An and 404Bn, and an electric field configured by a waveform generator 405B and a power source 405A. The generator 405 generates a potential at each of the electrodes 403An and 404Bn, and the sequencer 406 controls the potential driving timing of the electrodes to control the driving of the voltage of each electrode. The electrodes 403A1 to An on one side have 1 An electric field capable of driving particles in units of rows can be applied, and an electric field corresponding to image information can be applied simultaneously to the electrodes B1 to Bn on the other surface in the surface.

  34, 35, and 36 show cross sections of the image forming unit on an arbitrary surface of FIG. The particles are in contact with the electrode surface or the substrate surface, and at least one surface of the substrate is transparent so that the color of the particles can be seen from the outside. The electrodes 403A and 404B may be embedded in the substrate and integrated as shown in FIGS. 34 and 35, or may be separated from the substrate as shown in FIG.

With reference to FIG. 37, the operation will be described with reference to FIG. An example in which black colored particles are used as the colored particles, the white particles 20 are negatively charged, the black particles 18 are positively charged, and monochrome display is shown. The threshold value of the electric field in which the particles move is defined as ± E ₀ . That is, a particle group showing the relationship between display density and electric field as shown in FIG. 38 is used. The display surface is on the column side, and the electric field toward the display surface side is positive. A row to be driven is A _k , and an arbitrary column is B _k . The drive voltage V _Ak is applied to the electrode 403A, but the particles are acted on by the charge amount of the particles and the electric field between the substrates. Therefore, the surface potential of the inner surface of the substrate in contact with the particles is defined, and the row that contributes to driving is the surface potential V _{A +} , and the row that does not perform is the surface potential V _A− . Similarly, the driving voltage V _Bk of the electrode 404B defines the surface potential of the inner surface of the substrate that is in contact with the particles, and the column that performs white display is the surface potential V _{B +} and the column that does not perform the display is the surface potential V _B− . The distance between the substrates is d.

Next, the mechanism of particle movement in each electric field is shown. In the row to be driven, the potential of V _{A +} is generated in the row stripe, and the potential of V _{B +} and V _B− is generated in the column stripe according to the display content of the drive row. At that time, the electric field applied between the substrates is shown below.

_{E 1 = (V B + -V} A +) / d, E 2 = (V B- -V A +) / d ... (1)
In order to perform white display, the electric field must be larger than the positive threshold value, so the following conditions are required.

E ₁ > E ₀ (2)
Similarly, in black display, since the electric field must be smaller than the negative threshold value, the following conditions are required: E ₂ <−E ₀ (3)
Here, when the black display is provided on the entire surface in advance, it is sufficient that the white particles do not move, so that a strong positive electric field is not generated on the column side. That is, the following conditions may be used.

E ₁ > E ₀ > E ₂ (4)
As shown in FIG. 39, in the row where driving is not performed, the potential of V _A− is generated in the stripe of the row, and the potential of V _{B +} and V _B− is generated in the stripe of the column according to the display content of the driving row. At that time, the electric field applied between the substrates is shown below.

E ₃ = (V _{B +} −V _A− ) / d, E ₄ = (V _B− −V _A− ) / d (5)
In order not to drive, the particles must be fixed regardless of the display color.

  Therefore, the electric field must be smaller than the threshold value regardless of whether it is positive or negative. That is, it is as follows.

| E ₃ | <E ₀ , | E ₄ | <E ₀ (6)
From the above, by setting the electric field to satisfy ((2), (3) or (4)) and (6), display by simple matrix driving becomes possible.

  The particles can be driven as long as they have a threshold value for movement with respect to the electric field, and are not limited by the color, charge polarity, charge amount, shape, etc. of the particles.

Example 1
Next, an example of the second embodiment will be described.

  As the display substrate electrode 403A and the non-display substrate electrode 404B constituting the outside of the image display medium 10, a 7059 glass substrate (40 × 50 × 1.1 mm) with transparent electrodes ITO composed of eight 4 mm pitch stripes was used. The interior surface in contact with the particles of the glass substrate is coated with polycarbonate resin to a thickness of 5 μm. A central portion of a 40 × 40 × 0.3 mm silicon rubber plate is cut into a 15 × 15 mm square to form a space, and this silicon rubber plate is placed on the non-display substrate 403. Spherical fine particles of titanium oxide-containing crosslinked polymethyl methacrylate having a volume average particle size of 20 μm mixed with titania fine powder treated with isopropyltrimethoxysilane in a ratio of 100 to 0.1 by weight (Techpolymer MBX- manufactured by Sekisui Plastics Co., Ltd.) 20-white) and spherical fine particles of carbon-containing crosslinked polymethyl methacrylate having a volume average particle size of 20 μm (classified by Sekisui Plastics Co., Ltd. Techpolymer MBX-20-Black), a weight ratio of 2 to 1. And about 25 mg of the mixed particles are shaken through a screen into a space cut out in a square of the silicon rubber plate. Thereafter, the display substrate electrode 403A and the non-display substrate electrode 404B are arranged in close contact with the silicon rubber plate so as to form a matrix, and the two substrates are pressed and held with a double clip. Are closely attached to form the image display medium 10. At this time, the distance between the electrodes is 0.3 mm.

  Next, potential setting necessary for driving is shown by an example corresponding to the mechanism described above.

Matrix driving was performed with V _{A +} = −400 V for driving contribution, V _A− = 0 V for non-contributing, V _{B +} = + 400 V for white display, and V _B− = 0 V for black display. . In the configuration of this example, the threshold value for particle movement is ± 500 V, so E ₀ = 1.67 MV / m. Similarly, E ₁ = 2.67 MV / m, E ₂ = 1.33 MV / m, E ₃ = 1.33 MV / m, and E ₄ = 0 MV / m.

Since the expressions (4) and (6) are satisfied, matrix driving is possible. Here, since the method satisfying the equation (4) is used, the display driving is performed after the entire surface is driven so that the electric field E _x = −2.67 MV / m for displaying the entire surface black.

  As a result, an arbitrary pattern having the same density contrast as that of a single pixel could be created with a driving time of 0.1 second per line.

(Example 2)
Next, a drive example in which the drive voltage is reduced using an ITO transparent substrate with a reduced number of stripes and the distance between the electrodes will be described.

  The combination of particles was the same as in Example 1, and ITO electrodes were embedded with 0.4 mm pitch 480 stripes on the row side and those with 0.4 mm pitch 640 electrodes embedded on the column side. As drive drivers, 15 ECN2112s made by Hitachi on the row side and 20 ECN2001s on the column side were arranged in parallel. The distance between the electrodes is 0.12 mm.

As in Example 1, the experiment was performed with V _{A +} = −160 V, V _A− = 0V, V _{B +} = + 50 V, and V _B− = 0V. E ₁ = 1.75 MV / m, E ₂ = 1.33 MV / m, E ₃ = 0.42 MV / m, E ₄ = 0 MV / m, satisfying the expressions (4) and (6). Since the method satisfying the equation (4) was used, the display drive was performed after the entire surface was driven so that the electric field E _x = −1.75 MV / m for displaying the entire surface black. As a result, it was confirmed that images were displayed with a driving time of 5 msec per line.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described in detail with reference to the drawings.

  Here, a method of applying an alternating electric field to an image display medium immediately before applying an electric field according to image information will be described with reference to FIG. The electrodes 403A and 404B have a simple matrix structure, and a plurality of particle groups having different charging properties are enclosed in a space sandwiched between both electrodes. The electric field generator 402 generates potentials on the electrodes 403A and 404B, and the sequencer 406 controls the potentials of the electrodes. An electric field corresponding to image information is simultaneously applied to the electrode 403A on one side in the plane, and an electric field capable of driving particles in units of one row is applied to the electrode 404B on the other side. At that time, the electric field generator includes an amplifier 407, a waveform generator 405B, and a relay 409. The relay 409 can short-circuit all the electrodes 404B by an ON signal. The waveform generator 405B generates a waveform determined by the trigger ON signal.

  Next, the effect | action which applies an alternating electric field to the whole surface is demonstrated. When the relay 409 is turned on, the entire surface of the one electrode 404B becomes the same potential, and the potential for initialization is input from the sequencer 406. The power source 405A created by the waveform generator 405B on the A surface or the B surface, for example, amplifies the waveform coming from the waveform generator (manufactured by Wavetek) with a high voltage power source to apply an alternating electric field between the substrates, forcing the particles Vibrate. As a result, the particles are charged and easily moved by the electric field.

  At that time, since it is necessary to peel off the adhesion between the particles and the substrate or between the particles, it is necessary to give an impact force close to that for peeling. When the particles are stationary, the state where the particles are attached by the force of the electric field must be removed. At that time, if the method of gradually increasing the electric field is used, that is, if the waveform of the electric field is gradually increased, such as a sine wave, the firmly attached particles cannot be removed. Therefore, by making the waveform of the electric field a rectangular wave, a force that peels off the stuck particles in a state where a kind of shock wave is generated is generated. Here, as can be seen from the fact that the alternating electric field to be generated is a rectangular wave, a part of the rectangle may be grounded. In this case, an intermittent DC electric field is generated, but the action is not changed at all.

Next, when the particles exist in the air, the force applied to the particles adheres to the opposing surface while applying only the mirror image force qE due to the electric field. Since the adhesion force F _{v1 at} this time is a resistance against the mirror image force, a force equal to or greater than the force qE ₁ given by the electric field at the time of adhesion is required to separate the adhered particles again. That is, if an electric field of E ₁ or higher is applied, the movement becomes possible.

  Therefore, by gradually reducing the amplitude of the alternating electric field, the adhesion force due to the movement of the particles between the substrates is reduced, and the alternating electric field promotes frictional charging due to the contact between the particles and the particles and the substrate, thereby increasing the charge amount of the particles. Thus, the particles can be easily moved by the electric field.

[Fourth Embodiment]
Hereinafter, a fourth embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an image display medium 10 and an image forming apparatus 12 for forming an image on the image display medium 10 according to the present embodiment.

  The image display medium 10 has a configuration in which particles 18 and particles 20 having different colors are sealed between a display substrate 14 on the image display side and a non-display substrate 16 facing the display substrate 14. . The display substrate 14 and the non-display substrate 16 are made of a dielectric material.

  Here, the dielectric used for the display substrate 14 and the non-display substrate 16 may be an insulating resin. Self-supporting films are desirable, and examples include polyester, polypropylene, and polyethylene.

In addition, as long as one of the particles 18 and 20 is insulating, the other particle may have any property of conductivity, hole transporting property, electron transporting property, and insulating property. Examples of the conductive particle material include metals such as carbon black, nickel, silver, gold, tin, and stainless steel, alloys such as ITO, and inorganic pigments such as titanium oxide. The conductive particles include these as components. Particles or particles obtained by coating or containing the surface of other fine particles. Specifically, true spherical conductive particles (Micropearl NI (trade name) manufactured by Sekisui Chemical Co., Ltd.) obtained by electroless nickel plating on the surface of fine particles composed of a cross-linked copolymer mainly composed of divinylbenzene, and then And spherical conductive particles (Micropearl AU (trade name) manufactured by Sekisui Chemical Co., Ltd.) subjected to gold displacement plating. In addition, amorphous carbon true spherical conductive particles obtained by carbonizing and baking thermosetting phenol resin (Unibex GCP, H-Type (trade name) manufactured by Unitika Ltd.): Volume resistivity ≦ 10 ⁻² Ω · cm ), Spherical conductive particles coated with a metal such as gold or silver (Unibex GCP (trade name) manufactured by Unitika Ltd .: volume resistivity ≦ 10 ⁻⁴ Ω · cm), spherical oxidation of silica and alumina Spherical conductive particles (admafine (trade name) manufactured by Admatechs Co., Ltd.) coated with Ag and tin oxide on the surface of the fine particles, or a mother made of various materials such as styrene, acrylic, phenolic resin, silicone resin and glass Examples thereof include particles in which conductive fine powder is adhered or embedded on the surface of the particles. In addition to colored particles such as cyan, magenta, yellow, red, green, and blue, white or black colorless particles are also included as different color particles. As white or black particles, spherical particles (micropearl SP, micropearl BB (trade name) manufactured by Sekisui Chemical Co., Ltd.) made of a cross-linked copolymer containing divinylbenzene as a main component, cross-linked polymethyl methacrylate (cross-linked polymethacrylic). Methyl acid) fine particles (MBX-20 black, white (trade name) manufactured by Sekisui Plastics Co., Ltd.), cross-linked polyacrylic acid ester fine particles (ARX-15 black, white (produced by Sekisui Chemicals Co., Ltd.) Trade name), cross-linked polybutyl methacrylate fine particles (BMX-15 Black, White (trade name), etc., manufactured by Sekisui Plastics Co., Ltd.), polytetrafluoroethylene fine particles (Lebron L, manufactured by Daikin Industries, Ltd.) SST-2 (trade name) manufactured by Shamrock Technologies Inc.), silicone resin fine particles (Tospearl (trade name) manufactured by Toshiba Silicone Co., Ltd.) Etc.

  Insulating particles include insulating resins and inorganic substances. For example, there are inorganic substances such as resins such as polystyrene, polyester, acrylic and silicone, engineering plastics, glass and ceramics.

  Examples of materials having a hole transport function include hydrazone compounds, stilbene compounds, pyrazoline compounds, and arylamine compounds. Examples of the material having an electron transport function include a fluorenone compound, a diphenoquinone derivative, a pyran compound, and zinc oxide.

  In the present embodiment, the particles 18 are black black particles 18 and the particles 20 are white white particles 20, and have the following characteristics.

また、基板間に黒色粒子１８と白色粒子２０とがほぼ等量で、かつ空隙中の体積充填率が５０％以下となるように封入されれば画像表示が可能となるが、４０％以下とした方が画像のコントラストがよくとれるため好ましい。また、それぞれの粒子は仕事関数が異なり、仕事関数の大きい黒色粒子１８は相互の接触により正帯電し、仕事関数の小さい白色粒子は相互の接触により負帯電する。

Further, if the black particles 18 and the white particles 20 are enclosed between the substrates so as to have substantially the same amount and the volume filling rate in the voids is 50% or less, an image can be displayed. This is preferable because the contrast of the image can be improved. Each particle has a different work function. The black particles 18 having a large work function are positively charged by mutual contact, and the white particles having a small work function are negatively charged by mutual contact.

  Moreover, particles having respective functions can be produced by coating the surface of the conductive particles with a material having a hole transport function or an electron transport function.

  When the particles are insulative, the electric properties of the substrate are any of the properties of insulation, conductivity, hole transport, and electron transport, and no charge injection is performed on the particles, depending on the polarity of the frictional harm of the particles, It was moved by the electric field between the substrates. For example, when two types of insulating spherical fine particles of cross-linked polymethylmethacrylate (MBX-black and white manufactured by Sekisui Plastics Industry) are enclosed in a space sandwiched between electrodes coated with an insulating polycarbonate resin, Regardless of the nature, the two types of particles moved to different substrates depending on the electric field. Further, when charge injection was not performed from the substrate to the particle even with a substrate or particle having a charge transporting property, the same result as above was obtained (see the example of the A circle 1 shown in FIG. 44).

  In addition, even when one of the particles is subjected to charge injection from the substrate, the insulating particles are charged by contact between the particles because the difference in the work function exists between the particles. For example, spherical conductive particles (Micropearl AU manufactured by Sekisui Chemical Co., Ltd.) and cross-linked polymethyl are sandwiched between an electrode having a hole transporting property on one substrate and an electrode coated with an insulating polycarbonate resin on the other substrate. In the example in which the insulating spherical fine particles (MBX White manufactured by Sekisui Chemical Co., Ltd.) of methacrylate are mixed and encapsulated, the negatively charged insulating particles follow the electric field between the substrates. moved. On the other hand, the conductive particles were positively charged by hole injection from an electrode having a hole transporting property, and moved to and adhered to the negative insulating substrate. When the electric field was switched, each particle moved in the opposite direction.

  Therefore, looking at the state of the particles from the insulating substrate surface (display surface), gold is displayed by the conductive particles when the display surface is a negative electrode, and the insulating particles adhere to the display surface when the display surface is a positive electrode. White color was displayed (see the example of B ′ circle 1 shown in FIG. 45).

  In addition, even when one of the particles is subjected to charge injection from the substrate, the insulating particles are charged by contact between the particles because the difference in the work function exists between the particles. For example, spherical conductive particles (Micropearl AU manufactured by Sekisui Chemical Co., Ltd.) and insulating spherical fine particles of crosslinked polymethylmethacrylate (in the space sandwiched between one substrate with an ITO electrode and the other substrate coated with a polycarbonate resin) On the side on which Sekisui Plastics Co., Ltd. MBX-Black) was mixed and sealed, the charged insulating particles moved according to the electric field between the substrates. In this example, the insulating particles were positively charged and moved to the negative electrode. On the other hand, the conductive particles were injected from the conductive electrode by the charge injection received from the electrode, and all the particles adhered to the insulating substrate.

  Therefore, when the state of the particles is viewed from the insulating substrate surface (display surface), the insulating particles and the conductive particles are mixed and displayed black when the display surface is the negative electrode, and the conductive particles when the display surface is the positive electrode. Attached to the display surface and displayed a gold color (see the example of the B ′ circle 3 shown in FIG. 46).

  In addition, when the substrates are both conductive, as shown in FIG. 47, the conductive particles oscillate upon charge injection from both substrates by applying an electric field, but since the movement of the particles also stops at the same time as stopping the electric field, The conductive particles adhered evenly to both substrates. However, since the insulating particles adhere to one substrate in accordance with the electric field, black and gold were displayed on the display surface (see the example of the B circle 2 shown in FIG. 47).

  When the two types of particles are charged by charge injection and the charging polarity is not fixed, the charging polarity of the particles is not constant, so it is indeterminate which substrate is directed and the contrast cannot be obtained. In addition, the particles of different colors exchanged charges and were neutralized, so they did not move (an example of a blank shown in FIG. 43).

  The image forming apparatus 12 includes a printing electrode 11, a counter electrode 26, a power source 28, and the like.

  As shown in FIGS. 1 and 2A, the print electrode 11 includes a substrate 13 and a plurality of electrodes 15 having a diameter of, for example, 100 μm.

  Further, as shown in FIG. 2A, the plurality of electrodes 15 are formed on one surface of the substrate 34 in a direction (that is, the main scanning direction) substantially orthogonal to the transport direction of the image display medium 10 (the arrow B direction in the figure). ) Along a predetermined interval according to the resolution of the image. The electrodes 15 may be square as shown in FIG. 2B or may be arranged in a matrix as shown in FIG.

  As shown in FIG. 3, an AC power source 17 </ b> A and a DC power source 17 </ b> B are connected to each electrode 15 via a connection control unit 19. The connection control unit 19 has one end connected to the electrode 15 and the other end connected to the AC power source 17A, and once connected to the electrode 15 and the other end connected to the DC power source 17B. It is composed of a plurality of switches including the switch 21B.

  This switch is ON / OFF controlled by the control unit 60 and electrically connects the AC power supply 17 </ b> A and the DC power supply 17 </ b> B to the electrode 15. Thereby, it is possible to apply an AC voltage, a DC voltage, or a voltage obtained by superimposing the AC voltage and the DC voltage.

  Next, the operation of the fourth embodiment will be described.

  First, when the image display medium 10 is transported in the direction of arrow B in the drawing by a transport means (not shown) and transported between the print electrode 11 and the counter electrode 26, the control unit 60 instructs the connection control unit 19. All the switches 21A are turned on. Thereby, an AC voltage is applied to all the electrodes 15 from the AC power source 17A.

  When an AC voltage is applied to the electrode 15, the black particles 18 and the white particles 20 in the image display medium 10 reciprocate between the display substrate 14 and the non-display substrate 16. Thereby, the black particles 18 and the white particles 20 are frictionally charged by friction between particles or friction between the particles and the substrate. For example, the black particles 18 are positively charged and the white particles 20 are not charged or negatively charged. The In the following description, it is assumed that the white particles 20 are negatively charged.

  Then, the control unit 60 instructs the connection control unit 19 to turn on only the switch 17B corresponding to the electrode 15 at the position corresponding to the image data, and applies a DC voltage to the electrode 15 at the position corresponding to the image data. For example, a DC voltage is applied to the non-image area, and no DC voltage is applied to the image area.

  As a result, when a DC voltage is applied to the electrode 15, the positively charged black particles 18 in the portion where the print electrode 11 is opposed to the display substrate 14 as shown in FIG. Move to the display substrate 16 side. Further, the negatively charged white particles 20 on the non-display substrate 16 side move to the display substrate 14 side by the action of an electric field. Therefore, since only the white particles 20 appear on the display substrate 14 side, no image is displayed in a portion corresponding to the non-image portion.

  On the other hand, when a DC voltage is not applied to the electrode 15, the positively charged black particles 18 in the portion where the print electrode 11 faces the display substrate 14 are maintained as they are on the display substrate 14 side due to the action of the electric field. The Further, the positively charged black particles 20 on the non-display substrate 16 side move to the display substrate 14 side by the action of an electric field. Accordingly, since only the black particles 20 appear on the display substrate 14 side, an image is displayed in a portion corresponding to the image portion.

  Thereby, since only the black particles 18 appear on the display substrate 14 side, an image is displayed in a portion corresponding to the image portion.

  In this way, the black particles 18 and the white particles 20 move according to the image, and the image is displayed on the display substrate 14 side. Note that when the white particles 20 are not charged, only the black particles 18 move under the influence of the electric field. Since the black particles 18 at the portion where the image is not displayed move to the non-display substrate 16 and are hidden by the white particles 20 from the display substrate 14 side, the image can be displayed. Further, even after the electric field generated between the substrates of the image display medium 10 disappears, the displayed image is maintained by the inherent adhesion force of the particles. Further, since these particles can move again when an electric field is generated between the substrates, the image forming apparatus 12 can repeatedly display images.

In this way, since charged particles are moved by an electric field using air as a medium, safety is high. In addition, since air has a low viscous resistance, high-speed response can be satisfied.
[Fifth Embodiment]
Next, a fifth embodiment will be described.

  The image forming apparatus 12 illustrated in FIG. 4 includes an initializer 40 for charging the black particles 18 and the white particles 20 in the image display medium 10 and uniformly attaching the black particles 18 to the display substrate 14 side. Except for the points described above, the image forming apparatus 12 is the same as that of the first embodiment, and a detailed description thereof will be omitted.

  As shown in FIG. 5, the initializer 40 includes a pair of electrodes 23, and an AC power supply 25 is connected to these electrodes.

The AC power supply 25 applies an AC voltage to the electrode 23. Thereby, the black particles 18 and the white particles 20 in the image display medium 10 reciprocate between the display substrate 14 and the non-display substrate 16. Thereby, the black particles 18 and the white particles 20 are frictionally charged by friction between particles or friction between the particles and the substrate. For example, the black particles 18 are positively charged and the white particles 20 are not charged or negatively charged. The In the following description, it is assumed that the white particles 20 are negatively charged.
Moreover, you may make it apply the voltage which superimposed the alternating voltage and the direct-current voltage. In addition, when the particles are charged at the time of encapsulating between the substrates, or when the particles are charged before image formation due to repeated rewriting, friction between particles or friction between particles and the substrate. Is sufficiently charged.

  Further, as shown in FIG. 6, a pair of vibrators 27 are brought into contact with the opposing display substrate 14 and non-display substrate 16, and an alternating voltage is applied to the vibrators 27 to vibrate the vibrators 27. May be frictionally charged by vibrating.

  In addition, as shown in FIG. 7, particles may be stirred by an alternating magnetic field by a pair of magnetic plates 31 to induce friction between particles and friction between the particles and the substrate surface to charge the particles. The magnetic plate 31 has magnetic poles that change one after another according to the traveling direction of the image display medium 10. For this reason, the magnetically attracted black particles 18 are repeatedly attracted and separated for each magnetic pole, move around the substrate, and the particles come into contact with each other, and electrostatic charges are imparted to the particles. Any magnetic plate 31 may be used as long as it exhibits magnetism and promotes magnetic attraction of particles. For example, by using a coil instead of the magnetic plate 31 and passing a current when the image display medium 10 is passed, A magnetic field may be formed by using the action of an electromagnet, and thereby frictionally charged. Further, by making the direction of the magnetic field constant at a position where the image display medium 10 leaves the magnetic field, for example, the black particles 18 can be attached to one desired substrate side, and image omission during image formation due to an electric field is prevented. can do. Further, by making one surface of the magnetic plate 31 longer than the other surface, particles that are magnetically attracted to one surface may be finally collected.

  In the above case, for example, at least the black particles 18 or the white particles 20 need to be magnetized. As the particles, for example, particles having a magnetic property in the core and particles made of a resin colored with a pigment having a hiding power in the shell can be used. Examples of substances that give magnetism include magnetite, ferrite, iron and other ferromagnetic metals, alloys or oxide powders, black magnetite, γ-hematite, chromium dioxide, ferrite and other oxide magnetic materials, cobalt, nickel, etc. If an alloy-based metal magnetic material is used in the form of powder or flakes and carbon black is used as a concealing colorant, black particles, white pigments such as titanium oxide can be used to obtain white particles.

  Here, it is desirable that the black particles 18 and the white particles 20 are charged with opposite polarities. By charging with opposite polarities, it is possible to prevent particles from moving to and adhering to a substrate opposite to the substrate to be moved when an image is formed by moving by an electric field. Further, since the particles forming the image area and the particles forming the non-image area move in opposite directions by the electric field, an image with high contrast and sharpness can be formed.

  Next, the operation of the fifth embodiment will be described.

  When the image display medium 10 shown in FIG. 4 is conveyed in the direction of arrow B in the figure by a conveying means (not shown) and is conveyed between the electrodes 23 of the initializer 40 as shown in FIG. Is done.

  As a result, the black particles 18 and the white particles 20 in the image display medium 10 reciprocate between the display substrate 14 and the non-display substrate 16, and the black particles 18 and the white particles 20 are caused by the friction between the particles and the friction between the particles and the substrate. The particles 20 are frictionally charged, for example, the black particles 18 are positively charged and the white particles 20 are negatively charged.

  When the image display medium 10 is conveyed to the position of the print electrode 11, the control unit 60 instructs the connection control unit 19 to turn on only the switch 21B corresponding to the electrode 15 at the position corresponding to the image data. A DC voltage is applied to the electrode 15 at a position corresponding to the image data. For example, a DC voltage is applied to the non-image area, and no DC voltage is applied to the image area.

  As a result, when a DC voltage is applied to the electrode 15, the positively charged black particles 18 in the portion where the print electrode 11 is opposed to the display substrate 14 as shown in FIG. Move to the display substrate 16 side. Further, the negatively charged white particles 20 on the non-display substrate 16 side move to the display substrate 14 side by the action of an electric field. Therefore, since only the white particles 20 appear on the display substrate 14 side, no image is displayed in a portion corresponding to the non-image portion.

  On the other hand, when a DC voltage is not applied to the electrode 15, the positively charged black particles 18 in the portion where the print electrode 11 faces the display substrate 14 are maintained as they are on the display substrate 14 side due to the action of the electric field. The Further, the positively charged black particles 20 on the non-display substrate 16 side move to the display substrate 14 side by the action of an electric field. Accordingly, since only the black particles 20 appear on the display substrate 14 side, an image is displayed in a portion corresponding to the image portion.

  In this way, the black particles 18 and the white particles 20 move according to the image, and the image is displayed on the display substrate 14 side. Note that when the white particles 20 are not charged, only the black particles 18 move under the influence of the electric field. Since the black particles 18 at the portion where the image is not displayed move to the non-display substrate 16 and are hidden by the white particles 20 from the display substrate 14 side, the image can be displayed. Further, even after the electric field generated between the substrates of the image display medium 10 disappears, the displayed image is maintained by the inherent adhesion force of the particles. Further, since these particles can move again when an electric field is generated between the substrates, the image forming apparatus 12 can repeatedly display images.

  In this way, since charged particles are moved by an electric field using air as a medium, safety is high. In addition, since air has a low viscous resistance, high-speed response can be satisfied.

  Instead of the printing electrode 11, a voltage may be applied by a matrix electrode 33 as shown in FIG. 8, or a voltage may be applied by a pixel electrode 35 as shown in FIG. So-called active matrix drive).

[Sixth Embodiment]
Hereinafter, a sixth embodiment will be described with reference to the drawings.

  In the sixth embodiment, a case where an ion irradiation head 41 as shown in FIG. 10 is used will be described.

  The ion irradiation head 41 irradiates the image display medium 10 with airborne ions generated at a position away from the image display medium 10 according to the image information. As shown in FIG. 10, the ion irradiation head 41 includes an air ion generation unit 92 and an ion flow control unit 94, and the air ion generation unit 92 applies a high voltage to the electrode wire 96 as shown in FIG. Is applied to cause a corona discharge with the shield member 98 to generate air ions. The ion flow control unit 94 has a control electrode 100 that is divided into a desired resolution in the recording width direction and an opening 102 that irradiates the image display medium 10 with ions generated by the air ion generation unit. Therefore, the passage of the generated ions through the opening 102 is controlled by the polarity of the voltage applied to the control electrode 100.

  The ion flow control unit 94 is arranged to face the image display medium 10, and ions that have passed through the opening 102 are on the image display medium 10 according to an electric field formed between the ion irradiation head 41 and the counter electrode 26. Adhere to. A voltage is applied to each control electrode 100 according to image information, and an image is formed on the image display medium 10.

  Further, a stylus electrode 43 as shown in FIG. 11 may be used. The stylus electrode 43 is formed by arranging a large number of needle-like electrodes so as to obtain a desired image resolution. As shown in FIG. 11, when the stylus electrode 39 is disposed close to the image display medium 10 and a high voltage is applied between the counter electrode 26 in accordance with the image signal, the tip of the stylus electrode 104 is particularly formed. A high electric field acts on this, and a corona charge is generated here. The generated corona charge is attached on the image display medium 10 by an electric field formed between the needle electrode 104 and the counter electrode 26. As a result, an image is formed on the image display medium 10.

[Seventh Embodiment]
The seventh embodiment will be described below with reference to the drawings.

  In the seventh embodiment, as shown in FIG. 12, a photoconductive layer 45 that exhibits conductivity by being irradiated with light is laminated on at least one side, for example, the outside of the non-display substrate 16, and is further uniformly formed thereon. An electrode-equipped substrate 47 capable of applying various voltages is formed, and a uniform voltage is applied to the electrode-equipped substrate 47 by a direct current power source 49, while an exposure device 55 comprising a liquid crystal transmission panel 51 and a flat light source 53 is used based on an image signal. An image-like exposure is performed to give an electric field having a distribution according to the pattern. In addition, before performing image formation by light exposure, each particle is moved to one of the substrates depending on the color (initialization).

  When this configuration is used, the photoconductive layer 45 substantially acts as a dielectric layer when exposure is not performed, and substantially acts as a conductive layer in the exposed state. Accordingly, the uniform DC voltage applied from the power source 49 is such that the voltage applied to the photoconductive layer 47 in the non-exposure region is at a level where the voltage acting between the substrates is less than the movement of the particles, and in the exposure region. The voltage value is set so that almost all the applied voltage acts between the substrates and the particles can move. Such a configuration has an inherent effect that a high-resolution image display can be performed without requiring fine electrode processing. The photoconductive layer 47 is made of triphenylamine-based hole transport material Ae-18 and polycarbonate (PC-Z) as a charge transport layer, like the organic photoconductive layer used in general electrophotographic photoreceptors. Dip-coat a solid component tetrahydrofuran solution mixed with a binder in a 1: 1 ratio, and a VMCH (vinyl chloride / vinyl acetate copolymer) resin / acetic acid-n-butyl solution dispersion of aluminum chloride phthalocyanine as a charge generating material Can be produced by dip coating. The order of stacking may be reversed. Other examples of the organic charge generating material constituting the photoconductive layer 47 include azo pigments, quinone pigments, perylene pigments, indigo pigments, thioindigo pigments, bisbenzimidazole pigments, phthalocyanine pigments, Quinacridone pigments, quinoline pigments, lake pigments, azo lake pigments, anthraquinone pigments, oxazine pigments, dioxazine pigments, triphenylmethane pigments, azurenium dyes, squalium dyes, pyrylium dyes, triallylmethane Pigments, dyes, etc., such as dyes, xanthene dyes, thiazine dyes, cyanine dyes, and the like, and as charge transport materials, pyrenes, carbazoles, hydrazones, oxazoles that are holey charge transport materials , Oxadiazole, pyrazoline, arylamine Low molecular compounds such as arylmethane, benzidine, thiazole, stilbene, butadiene, and the like, and high molecular compounds include, for example, poly-N-vinylcarbazole, halogenated poly-N-vinylcarbazole, and polyvinyl. Pyrene, polyvinylanthracene, polyvinylacridine, pyrene-formaldehyde resin, ethylcarbazole-formaldehyde resin, ethylcarbazole-formaldehyde resin, triphenylmethane polymer, polysilane and electron transport materials such as benzoquinone, tetracyanoethylene, tetracyanoquino Dimethane, fluorenone, xanthone, phenanthraquinone, phthalic anhydride, diphenoquinone and the like can also be used. In addition to the organic photoconductive material, inorganic materials such as amorphous silicon, amorphous selenium, tellurium, selenium-tellurium alloy, cadmium sulfide, antimony sulfide, titanium oxide, zinc oxide, and zinc sulfide can be used.

  Further, as the exposure device 55, a liquid crystal transmission panel 51 placed on a flat light source 53 (Color Illuminator Pro ST (trade name) manufactured by Fuji Color Sales) is used. Such an exposure device 55 is brought into close contact with the image display medium 10, and a voltage is applied while directly irradiating the photoconductive layer 47 of the image display medium 10 with light that has passed through the liquid crystal transmission panel 51. Is formed on the surface of the image display medium 10.

  In addition to the above, the exposure apparatus 55 is a combination of a surface light emitting device such as a CRT and a fiber optical system or an imaging optical system, a fluorescent display tube, a plasma light emitting element, an EL light emitting element, an LED light emitting element, or the like. That are arranged in a line or plane to form a one-dimensional optical writing or two-dimensional optical writing device, and a method of scanning a laser light source in a one-dimensional or two-dimensional manner using a scanning optical system Can do. In addition, the light emitted from a fluorescent lamp, a halogen lamp, or the like is directly radiated to the photoconductive layer 47 with transmitted light that has passed through a transmissive film such as an OHP film, reflected light that illuminates a reflecting object, etc. You may use what was imaged using.

[Eighth Embodiment]
The eighth embodiment will be described below with reference to the drawings.

  In the eighth embodiment, as shown in FIG. 13, the charged black particles 18 contain a photoconductive material that exhibits conductivity by light irradiation, and particles in a region according to the image-like exposure pattern are selectively selected. An uncharged state is set, and charged particles in the substrate are moved according to a uniform electric field between the substrates.

  Photoelectric particles containing a photoconductive material can be prepared as follows. First, 100 parts by weight of a polyester resin, 5 parts by weight of gallium chloride phthalocyanine, 20 parts by weight of triphenylamine, and 110 parts by weight of ethyl acetate are dispersed in a ball mill for 48 hours to form Liquid A. On the other hand, prepare 100 parts by weight of a 2% aqueous solution of carboxymethylcellulose to make solution B. Next, 100 parts by weight of Liquid B is stirred with an emulsifier, and 50 parts by weight of Liquid A is slowly added to suspend the liquid mixture. Thereafter, ethyl acetate is removed under reduced pressure, washed with water, dried and classified to produce blue photoconductive particles.

  Next, a case where an image is formed on the image display medium 10 using the thus produced photosensitive particles will be described. The photoconductive particles 18 and the insulating particles 20 of different colors (here, white) are agitated and collided in a non-exposed state by a charging method using an alternating electric field shown in FIG. Here, the photoconductive particles 18 are charged with a positive polarity. Next, exposure is performed by an exposure apparatus 55 shown in FIG. Note that the display pattern of the liquid crystal transmission panel 51 of the exposure apparatus 55 is obtained by inverting the display pattern of the liquid crystal transmission panel 51 of the exposure apparatus 55 shown in FIG. This is because electrons and hole carriers are generated in the photoconductive particles 18 in the region irradiated with light, and the positive surface charge due to charging is offset by the electrons generated by the exposure, and after the exposure is completed, it becomes an uncharged state. This is because the particles in the exposure area do not move.

  The substrate of the image display medium 10 may be a plastic substrate having flexibility in addition to a glass substrate, but is plastic because it has flexibility close to paper hard copy and excellent mechanical strength that can withstand rough handling. It is desirable to use materials. Examples of such a plastic substrate include polyester films such as polyethylene terephthalate, polycarbonate, and polyimide.

  Further, as shown in FIG. 14, exposure may be performed using a laser scanning exposure device 57 used in an electrophotographic apparatus as the exposure apparatus 55. In this case, the image display medium 10 using the flexible substrate is wound around the drum 61 so that the surface opposite to the display surface is the surface, and laser exposure is performed while applying a DC voltage to the image display medium 10 from the DC power source 59. By performing two-dimensional exposure by rotating the drum 61, an image can be formed on the image display medium 10. Note that initialization is performed before image exposure.

[Ninth Embodiment]
Next, a ninth embodiment will be described.

  FIG. 15 shows an image forming apparatus 12 according to the ninth embodiment. The image forming apparatus 12 includes an electrostatic latent image forming unit 22, a drum-shaped electrostatic latent image carrier 24, a counter electrode 26, a DC voltage power supply 28, and the like.

The electrostatic latent image forming unit 22 includes a charging device 80 and a light beam scanning device 82. In this case, the photosensitive drum 24 can be used as the electrostatic latent image carrier 24. The photosensitive drum 24 is formed by forming a photoconductive layer on a drum-like conductive base such as aluminum or SUS, and various known materials can be used as the photoconductive layer. For example, an inorganic photoconductive material such as α-Si, α-Se, As ₂ Se ₃ or an organic photoconductive material such as PVK / TNF can be used. These can be obtained by plasma CVD, vapor deposition or dipping. Can be formed. Moreover, you may form a charge transport layer, an overcoat layer, etc. as needed.

  The charging device 80 uniformly charges the surface of the electrostatic latent image carrier 24 to a desired potential. The charging device 80 may be any device as long as the surface of the photosensitive drum 24 can be charged to an arbitrary potential. In this embodiment, a high voltage is applied to the electrode wire and the electrostatic latent image carrier 24 is connected to the charging device 80. It is assumed that a corotron that generates corona discharge and uniformly charges the surface of the photosensitive drum 24 is used. In addition to this, various known chargers such as a conductive roll member, a brush, a film member, etc. are brought into contact with the photosensitive drum 24 and a voltage is applied to the photosensitive drum 24 to charge the surface of the photosensitive drum. can do.

  The light beam scanning device 82 irradiates the surface of the charged electrostatic latent image carrier 24 with a minute spot light based on the image signal to form an electrostatic latent image on the electrostatic latent image carrier 24. The light beam scanning device 82 may be any device that irradiates the surface of the photosensitive drum 24 with a light beam in accordance with image information and forms an electrostatic latent image on the uniformly charged photosensitive drum 24. In this embodiment, the polygon mirror 84 and the folding mirror 86, and an image forming optical system including a light source and a lens (not shown) are sensitized by the polygon mirror 84 while turning on and off the laser beam adjusted to a predetermined spot diameter according to the image signal. A ROS (Raster Output Scanner) device that optically scans the surface of the body drum 24 is used. In addition, an LED head or the like in which LEDs are arranged according to a desired resolution may be used.

  The conductive support 24A of the electrostatic latent image carrier 24 is grounded. The electrostatic latent image carrier 24 rotates in the direction of arrow A in the figure.

The counter electrode 26 is made of a conductive roll member having elasticity, for example. As a result, the image display medium 10 can be more closely attached. Further, the counter electrode 26 is disposed at a position facing the electrostatic latent image carrier 24 with the image display medium 10 conveyed by a conveying means (not shown) in the direction of arrow B in the figure. The counter electrode 26 is connected to a DC voltage power supply 28. The counter electrode 26 is applied with a bias voltage V _B by the DC voltage power supply 28. For example, as shown in FIG. 2, the bias voltage V _{B to be} applied is set such that the potential of the portion where the positive charge is charged on the electrostatic latent image carrier 24 is V _H , and the potential of the uncharged portion is V _L. In such a case, the voltage is set to an intermediate potential between the two. Further, the counter electrode 26 rotates in the direction of arrow C in FIG.

  Next, the operation in the ninth embodiment will be described.

  When the electrostatic latent image carrier 24 starts to rotate in the direction of arrow A in FIG. 15, the electrostatic latent image forming unit 22 forms an electrostatic latent image on the electrostatic latent image carrier 24.

  On the other hand, the image display medium 10 is conveyed in the direction of arrow B in the figure by a conveying means (not shown), and is conveyed between the electrostatic latent image carrier 24 and the counter electrode 26.

Here, a bias voltage V _B as shown in FIG. 16 is applied to the counter electrode 26, and the potential of the electrostatic latent image carrier 24 at a position facing the counter electrode 26 is V _H. Therefore, when the portion of the electrostatic latent image carrier 24 facing the display substrate 14 is charged with a positive charge (non-image portion), it faces the electrostatic latent image carrier 24 of the display substrate 14. When the black particles 18 are attached to the portion, the positively charged black particles 18 move from the display substrate 14 side to the non-display substrate 16 side and adhere to the non-display substrate 16. Thereby, since only the white insulating particles 20 appear on the display substrate 14 side, an image is not displayed in a portion corresponding to the non-image portion.

On the other hand, when the portion facing the display substrate 14 of the electrostatic latent image carrier 24 is not charged with a positive charge (image portion), the black particles 18 are formed on the portion facing the counter electrode 26 of the non-display substrate 16. Is attached, the potential of the electrostatic latent image carrier 24 at the position facing the counter electrode 26 is _VL , so that the charged black particles 18 are displayed from the non-display substrate 16 side. It moves to the substrate 14 side and adheres to the display substrate 14. Thereby, since only the black particles 18 appear on the display substrate 14 side, an image is displayed in a portion corresponding to the image portion.

  In this way, the black particles 18 move according to the image, and the image is displayed on the display substrate 14 side. Even after the electric field generated between the substrates of the image display medium 10 disappears, the displayed image is maintained by the inherent adhesion force of the particles and the mirror image force between the particles and the substrate. Further, since the black particles 18 and the white particles 20 can move again when an electric field is generated between the substrates, the image forming apparatus 12 can repeatedly display images.

  As described above, since the bias voltage is applied to the counter electrode 26, the black particles 18 are moved regardless of whether the black particles 18 are attached to the display substrate 14 or the non-display substrate 16. Can do. For this reason, it is not necessary to adhere the black particles 18 to one substrate side in advance. In addition, an image with high contrast and sharpness can be formed. Furthermore, since particles charged with air as a medium are moved by an electric field, safety is high. In addition, since air has a low viscous resistance, high-speed response can be satisfied.

  As a configuration of the image display medium 10, for example, as shown in FIG. 17, a cell structure may be formed between the opposing substrates of the image display medium 10, and particles may be enclosed in each cell 37. Thereby, the partial bias of the particles enclosed between the substrates is suppressed, and more stable image display can be performed. In addition, since the gap between the opposing substrates is regulated by the cell wall 39, image display by electrostatic force can be performed more stably. Furthermore, when pressure is applied to the image display medium 10, the image display medium 10 is crushed and the encapsulated particles are not packed, and the particles cannot be moved due to electrostatic force. can do.

  The image display medium 10 having the above cell structure is formed by forming a cell pattern of an arbitrary size by pressing, printing, or the like using an etching process, laser processing, or a prefabricated mold on at least one substrate. It can be formed by putting desired particles in each cell and adhering the opposing substrate from above.

  The image display medium 10 having the above-described cell structure is formed by sandwiching a sheet having a large number of openings between a display substrate and a non-display substrate, putting desired particles in each cell, and bonding the opposing substrate from above. can do. As a sheet having a large number of openings, for example, there is a net, the net is easily available and inexpensive, and the thickness and the like are relatively uniform, which is effective when manufacturing a display medium at a low cost. This method is not a display medium for fine display but a technique for a large display device that does not require much resolution. As another example of the sheet having a large number of openings, there is a sheet in which holes are formed by etching or laser processing, and this sheet has a greater degree of freedom in the thickness of the sheet and the shape of the hole than the above-described net. large. For this reason, it is effective for a display medium for performing fine display or for increasing the contrast.

  Further, in order to regulate the gap between the opposing substrates, as shown in FIG. 18, in addition to the cell structure, spacer particles 38 having the same size as the desired gap are enclosed, thereby regulating the gap. You can also. In this method, there is no effect of preventing partial deviation of the particles, but the image display medium 10 can be formed much more easily and cheaply than when the cell structure is formed. As the spacer particles, it is preferable to use transparent particles having little influence on the display image. For example, glass particles, transparent resin particles such as polystyrene, polyester, and acrylic can be used.

  Further, in the present embodiment, the case where the black particles 18 are not uniformly attached to the display substrate 14 side in advance has been described as an example. However, the present invention is not limited to this. You may make it adhere like.

  In the present embodiment, the positively charged portion on the electrostatic latent image carrier 24 is described as a non-image portion, and the non-charged portion is an image portion. The image formation may be performed by appropriately combining the polarities of the image portion and the non-image portion and the polarity of the particles. For example, a positively charged portion on the electrostatic latent image carrier 24 is an image portion, and an uncharged portion is a non-image portion. Black particles 18 are negatively charged and white particles 20 are positively charged. You may make it do.

[Tenth embodiment]
Next, a tenth embodiment will be described. In the tenth embodiment, an image forming apparatus that can form an image on a reusable image display medium 10 and can also form an image on a normal recording sheet will be described.

  FIG. 19 shows an image forming apparatus 12 capable of forming an image on both the image display medium 10 and ordinary recording paper. The same parts as those of the image forming apparatus 12 shown in the fourth embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 18, the image forming apparatus 12 includes a developing device 50, a transfer device 52, a cleaning device 54, a fixing device 56, a medium detection sensor 58, and a control unit 60.

  The developing device 50 develops the electrostatic latent image formed on the electrostatic latent image carrier 24 by the electrostatic latent image forming unit 22 with toner. For the image formation of a toner image, a method generally used in electrophotography can be used. For example, a magnetic one-component, non-magnetic one-component, two-component development, and a developing roll can be contacted or non-contacted. It may be used.

  The transfer unit 52 is connected to a DC voltage power source 62. The transfer unit 52 transfers the toner image formed on the electrostatic latent image carrier 24 to the recording paper 64 by applying a voltage from the DC voltage power source 62. As the transfer member, any member may be used as long as it is a member that performs transfer by an electric field such as corotron and roll.

  Further, since the transfer of the toner image onto the recording paper 64 and the image formation onto the image display medium 10 are both performed by applying a voltage, the transfer device 52 is shared with the counter electrode 26 as shown in FIG. Also good. In this case, the DC voltage power supply 28 may be a power supply that can control the voltage to be applied.

  The cleaning device 54 removes the toner remaining on the electrostatic latent image carrier 24 after the transfer. Moreover, about a cleaning member, members, such as a brush, a roll, a braid | blade, can be used.

  The fixing device 56 includes a pair of fixing rollers 66 that can be heated to a predetermined temperature. The recording sheet 64 is nipped and conveyed by the heated fixing roller 66, whereby the toner image on the recording sheet 64 can be thermally fixed. Further, the belt is not limited to a roller, and fixing may be performed not only by heat fixing but also by pressure fixing.

  Further, although not shown in FIG. 19, the image forming apparatus 12 is provided with a conveyance path switching member 68 on the medium conveyance path and in front of the fixing device 56, as shown in FIG. The transport path switching member 68 is rotated in the direction of arrow F in the figure in response to an instruction from the control unit 60 to change the transport path of the medium. When the medium is the recording paper 64, the transport path switching member 68 is set to a position where the tip is raised upward as shown in FIG. As a result, the recording paper 64 is conveyed toward the fixing device 56. On the other hand, when the medium is the image display medium 10, it is set to a position where the tip is lowered as indicated by a dotted line in the figure by an instruction from the control unit 60. As a result, the image display medium 10 is conveyed upward without passing through the fixing device 56.

  Further, as shown in FIG. 22, without providing the transport path switching member 68, the fixing device 56 may use a pair of hot wires 70 that are not in contact with the recording paper 64 and can switch heating at high speed. Good. Thereby, when the medium to be conveyed is the recording paper 64, the heat ray 70 is heated and the fixing process is performed, and when the medium is the image display medium 10, the heat ray 70 is turned off. Thereby, the recording paper 64 and the image display medium 10 can be processed by the same conveyance path.

  Further, as shown in FIG. 23, the developing device 50 can be moved in the direction of arrow G in the figure by an instruction from the control unit 60, and can be separated from or brought into contact with the electrostatic latent image carrier 24. It is like that. As a result, when the image formation on the image display medium 10 is performed after the image formation on the recording paper 64, the electrostatic latent image carrier 24 is separated by separating the developing device 50 from the electrostatic latent image carrier 50. Therefore, no toner is supplied. Accordingly, it is possible to prevent toner from adhering to the image display medium 10. Instead of moving the entire developing device 50, as shown in FIG. 24, only the developing roll 70 may be moved (position indicated by a dotted line in the figure).

  Also, as shown in FIG. 25, the driving of the developing roll 70 is stopped by the driving device 72 in response to an instruction from the control unit 60, or the developing roll 70 is rotated in the reverse direction as shown in FIG. In addition, the developing roller 70 is electrostatically connected to the developing roller 70 using a voltage application device 76 that can stop the supply of toner to the developing roller by the damming member 74 or switch the polarity of the applied voltage as shown in FIG. The toner may be prevented from being supplied to the electrostatic latent image carrier 24 by applying a voltage having a polarity opposite to that of the latent image.

  The medium detection sensor 58 is connected to the control unit 60. The medium detection sensor 58 detects light reflected by, for example, irradiating predetermined light (for example, infrared light) to a passing medium, detects the light amount of the detected reflected light, and outputs the detected light to the control unit 60. To do. Further, the weight of the passing medium may be detected and output to the control unit 60.

  The control unit 60 determines whether the medium on which the image is to be formed is the image display medium 10 or the recording paper 64 based on the detection result output from the medium detection sensor 58. In addition, the control unit 60 determines control parameters for each unit according to the medium, and controls each unit according to the control parameter. The control parameters include, for example, an image forming parameter, an electric field generation parameter, whether or not the developing device 50 is used, whether or not the fixing device 56 is used, a medium transport path, and the like.

  Next, a control routine executed by the control unit 60 as an operation in the tenth embodiment will be described with reference to FIG.

  In step 200 shown in FIG. 28, it is determined whether or not the medium is detected by the medium detection sensor 58. The medium detection sensor 58 detects light reflected by, for example, irradiating predetermined light (for example, infrared light) to a passing medium, detects the light amount of the detected reflected light, and outputs the detected light to the control unit 60. To do.

  If the medium is detected, the result is affirmative in step 200, and in step 202, the medium conveyed from the detection result from the medium detection sensor 58, that is, the light quantity value of the reflected light, is the image display medium 10 or the recording paper 64. The image forming parameters are determined according to the determination result. The image forming parameters include, for example, an electric field generation parameter, a developing device setting, a conveyance path setting, a conveyance speed, and an exposure amount.

  The electric field generation parameter is, for example, an applied voltage value or the like in each unit. When the medium to be conveyed is the image display medium 10, the applied voltage value in each unit of the electrostatic latent image forming unit 22, the developing device 50, and the counter electrode 26. When the transported medium is the recording paper 64, the applied voltage values and the like at the electrostatic latent image forming unit 22, the developing device 50, the transfer device 52, and the cleaning device 54 are used.

  For example, when the medium to be conveyed is the image display medium 10, the developing device is set by moving the developing device 50 in the direction of arrow G in FIG. Try to keep them apart. When the medium is the recording paper 64, the developing device 50 is moved in the direction of arrow G in the figure so as to come into contact with the electrostatic latent image carrier 24.

  When the medium to be transported is the image display medium 10, the transport path is set by rotating the transport path switching member 68 in the direction of arrow F as shown in FIG. (The position of the dotted line in the figure). Thereby, the image display medium 10 can be conveyed upward without passing through the fixing device 56 after image formation. When the medium to be transported is the recording paper 64, the transport path switching member 68 is rotated in the direction of arrow F in the drawing so that the leading end is positioned on the upper side. Thereby, the recording paper 64 can be conveyed to the fixing device 56 side. In this case, the heating temperature of the fixing roller 66 is also set.

  In step 204, an image forming process is performed. That is, when the medium to be transported is the image display medium 10, as described in the third embodiment, the electrostatic latent image forming unit 22 is controlled to electrostatically move on the electrostatic latent image carrier 24. A latent image is formed, a bias voltage is applied to the counter electrode 26, and an image is formed on the image display medium 10. When the medium to be conveyed is the recording paper 64, the electrostatic latent image forming unit 22 is controlled to form an electrostatic latent image on the electrostatic latent image carrier 24, and toner development is performed by the developing device 50. . Then, the toner image is transferred to the recording paper 64 by the transfer device 52, and the toner image transferred by the fixing device 56 is fixed. In this way, an image is formed on the recording paper 64.

  As described above, since the medium is automatically detected and the image forming process is performed according to the detected medium, the image display medium 10 and the recording paper 64 that can be repeatedly used in one apparatus can be formed. In addition, various parameters are set according to each medium, and image formation is performed according to the parameters, so that the image quality is not deteriorated.

  In this embodiment, the case where the medium is automatically detected and an image is formed according to the detected medium has been described as an example. However, the user can determine whether the image is a display medium or an image recording medium by using a keyboard, Manual input may be performed by an input device such as a mouse, and image formation may be performed according to the input result.

  Further, as another example of the electrostatic latent image forming unit 22, an ion irradiation head 41 as shown in FIG. 10 may be used. In this case, as the electrostatic latent image carrier 24, a dielectric drum 24 in which a dielectric layer is formed on a conductive substrate can be used.

  As another example of the electrostatic latent image forming unit 22, a stylus electrode 43 as shown in FIG. 11 may be used. In this case, as the electrostatic latent image carrier 24, a dielectric drum 24 in which a dielectric layer is formed on a conductive substrate can be used.

[Eleventh embodiment]
Next, an eleventh embodiment will be described. In the eleventh embodiment, a case where a color image is formed on an image display medium will be described.

  As shown in FIG. 29, the image display medium 10 for forming a color image is an image display medium 10 having a cell structure as shown in FIG. 9 described above. In each cell 37, yellow (6Y) particles 106, magenta The colored particles of (6M) particles 108 and cyan (6C) 110 are sealed in the cell 37 in a predetermined arrangement. The image display medium 10 is transported between an electrostatic latent image carrier 24 that holds an electrostatic latent image formed based on an image signal of each color and the counter electrode 26, and colored particles in each cell 37 It moves to the display substrate 14 side according to the electric field formed by the electrostatic latent image. Each cell 37 may contain white particles or black particles. Here, it is important to match the position of the electrostatic latent image composed of the image signals of each color on the electrostatic latent image carrier 24 with the position of the cell 37 in which each color of the image display medium 10 is contained. Further, the color reproduction range may be adjusted by appropriately adding red (R), green (G), blue (B), black (K), etc. as the color of the colored particles.

  In particular, for black (K), instead of the movement of the charged particles due to the electric field, magnetic black particles are enclosed in each cell 37 together with other colored particles, and the display substrate 14 is moved to the side of the display substrate 14 by magnetic attraction based on an image signal. It may be moved and displayed in black. At this time, the magnetic attractive force based on the image signal can be given by, for example, a magnetic stylus.

  Each color particle in each cell 37 can be similarly charged by the method shown in the eighth embodiment before the image forming step.

  The image formation of a color image is basically the same as the processing shown in the seventh embodiment, but in this embodiment, an electrostatic latent image for each color is converted into an electrostatic latent image based on a color image signal. It is formed once on the carrier 24. Thereby, the particles of each color encapsulated in each cell of the image display medium 10 move to the display substrate 14 side according to the electrostatic latent image for each color. Thereby, a color image can be formed in one image forming process.

  Here, for example, in a color printer having a tandem configuration, each color image is formed on four photoconductors and transferred four times on a sheet of paper, so that the pixel alignment of each color on the sheet is a major problem. Become. A color printer having a configuration of four cycles and one copy has the same problem because the image of each color formed on one photoconductor is transferred onto the paper four times. In contrast, in the present invention, since a color image can be formed by moving particles of a plurality of colors in one image forming process, the pixel position of the cell 37 on the image display medium 10 and the pixel of the electrostatic latent image The position only needs to be adjusted once, and a color image can be formed more easily and at high speed.

  The image display medium formed by the above image display device by the above image display method is a rewritable bulletin board having a memory property, a circulation version, an advertisement, a signboard, a flashing sign, an electronic paper, an electronic newspaper, an electronic book, a copying machine, It can be used for a wide variety of product forms such as temporary sheets that can be shared with printers.

It is a schematic block diagram of the image forming apparatus in 4th Embodiment. It is a figure which shows the pattern of the electrode of a printing electrode. It is a schematic block diagram of a printing electrode. It is a schematic block diagram of the image forming apparatus in 5th Embodiment. It is a schematic block diagram of an initializer. It is a schematic block diagram of an initializer. It is a schematic block diagram of an initializer. It is a schematic block diagram of a matrix electrode. It is a schematic block diagram of a pixel electrode. It is a schematic block diagram of an ion irradiation head. It is a schematic block diagram of a stylus electrode. It is a schematic block diagram of exposure apparatus. It is a schematic block diagram of exposure apparatus. It is a figure for demonstrating the image formation by a light beam scanning apparatus. It is a schematic block diagram of the image forming apparatus in 9th Embodiment. It is a figure which shows the electric potential in an electrostatic latent image carrier and a counter electrode. It is a figure which shows the other example of an image display medium. It is a figure which shows the other example of an image display medium. It is a schematic block diagram of the image forming apparatus in 10th Embodiment. This is a modification of the image forming apparatus according to the tenth embodiment. It is a schematic block diagram of a fixing device and a conveyance path switching member. It is a figure which shows a fixing means. It is a figure which shows the other example of a developing device. It is a figure which shows another example of a developing device. It is a figure which shows another example of a developing device. It is a figure which shows another example of a developing device. It is a figure which shows another example of a developing device. It is a flowchart of the control routine performed in a control part. It is a figure which shows the image display medium which can display a color image. 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment. It is a figure which shows the relationship between the drive voltage and display density in 1st Embodiment. It is a figure which shows the relationship between the particle area ratio and display density in 1st Embodiment. It is a schematic block diagram of the image forming apparatus in 2nd Embodiment. It is a figure which shows the other example of an image display medium. It is a figure which shows the other example of an image display medium. It is a figure which shows the other example of an image display medium. It is a figure which shows the effect | action of the particle movement of an image display medium. It is a schematic diagram which shows the relationship between the drive voltage and display density of an image display medium. It is a figure which shows the other effect | action of an image display medium. It is a schematic block diagram of the image forming apparatus in 3rd Embodiment. It is a diagram which shows the relationship between a filling rate and a filling amount. It is a diagram which shows the relationship between the projected area ratio of black particle | grains, and display density. It is a table | surface for demonstrating the combination of the particle | grains which can display an image, and a board | substrate. It is a figure for demonstrating the movement of the particle | grains in an image display medium. It is a figure for demonstrating the movement of the particle | grains in an image display medium. It is a figure for demonstrating the movement of the particle | grains in an image display medium. It is a figure for demonstrating the movement of the particle | grains in an image display medium.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image display medium 11 Print electrode 12 Image forming apparatus 14 Display substrate 16 Non-display substrate 18 Black particle 20 White particle 22 Electrostatic latent image formation part 24 Electrostatic latent image support body 26 Counter electrode 37 Cell 38 Spacer particle 50 Developing apparatus 52 Transfer device 56 Fixing device 58 Medium detection sensor 80 Charging device 82 Light beam scanning device

Claims (27)

A pair of substrates and a plurality of types of particles having different colors and charging characteristics are encapsulated between the substrates so as to be movable between the substrates by an applied electric field, and on one of the pair of substrates. An image forming apparatus for forming an image on an image display medium comprising a formed photoconductive layer,
Voltage applying means for applying a voltage between the pair of substrates;
A transmissive panel formed in a pattern according to the image;
A light source for irradiating the transmissive panel with light;
An image forming apparatus. An image is formed on an image display medium that includes a pair of substrates and a plurality of types of particles that are sealed between the substrates so as to be movable between the substrates by an applied electric field and that have different colors and charging characteristics. An image forming apparatus,
A latent image carrier;
An electrostatic latent image forming means for forming an electrostatic latent image corresponding to an image on the latent image carrier;
A counter electrode for generating an electric field between the image display medium and the latent image carrier;
Charging means for precharging the particle group;
An image forming apparatus comprising: An image is formed on an image display medium that includes a pair of substrates and a plurality of types of particles that are sealed between the substrates so as to be movable between the substrates by an applied electric field and that have different colors and charging characteristics. An image forming apparatus,
A latent image carrier;
An electrostatic latent image forming means for forming an electrostatic latent image corresponding to an image on the latent image carrier;
A counter electrode for generating an electric field between the image display medium and the latent image carrier;
Charging means for precharging the particle group;
With
The image forming apparatus, wherein the charging unit applies at least one of a DC voltage and an AC voltage to the substrate. An image is formed on an image display medium that includes a pair of substrates and a plurality of types of particles that are sealed between the substrates so as to be movable between the substrates by an applied electric field and that have different colors and charging characteristics. An image forming apparatus,
A latent image carrier;
An electrostatic latent image forming means for forming an electrostatic latent image corresponding to an image on the latent image carrier;
A counter electrode for generating an electric field between the image display medium and the latent image carrier;
As charging means for precharging the particle group, vibration means for vibrating the substrate;
An image forming apparatus comprising: An image is formed on an image display medium that includes a pair of substrates and a plurality of types of particles that are sealed between the substrates so as to be movable between the substrates by an applied electric field and that have different colors and charging characteristics. An image forming apparatus,
A latent image carrier;
An electrostatic latent image forming means for forming an electrostatic latent image corresponding to an image on the latent image carrier;
A counter electrode for generating an electric field between the image display medium and the latent image carrier;
Vibration means for vibrating the substrate as a charging means for precharging the particle group;
With
When the image display medium in which at least one of the particle groups is magnetized is charged in advance, the vibration unit applies an alternating magnetic field to the substrate.   The plurality of types of particles of the image display medium including a pair of substrates and a plurality of types of particle groups that are sealed between the substrates so as to be movable between the substrates by an applied electric field and have different colors and charging characteristics. An image forming method comprising applying an alternating electric field to a group immediately before applying an electric field according to image information.   The image forming method according to claim 6, wherein the alternating electric field is simultaneously applied to the entire surface of the image display medium.   7. The image forming method according to claim 6, wherein the alternating electric field is applied immediately before the electric field corresponding to the image information is applied by the sequence for applying the electric field in units of rows.   The image forming method according to claim 6, wherein the amplitude of the alternating electric field gradually decreases with time.   The image forming method according to claim 6, wherein the voltage waveform of the alternating electric field is rectangular. A first member having conductive properties;
A second member having a hole transport property, an electron transport property, and an insulating property disposed opposite to the first member;
First particles enclosed in a space provided between the first member and the second member, and having at least a surface having an insulating property;
An image display medium comprising: second particles enclosed in the space and having a color different from that of the first particles and at least a surface having an electron transporting property or a hole transporting property. A first member having a hole transporting property;
A second member having an electron transporting or insulating property disposed opposite to the first member;
First particles enclosed in a space provided between the first member and the second member, and having at least a surface having an insulating property;
An image display medium comprising: second particles enclosed in the space and having a color different from that of the first particles and at least a surface having an electron transporting property or a hole transporting property. A first member having an electron transporting property;
A second member having an insulating property disposed opposite to the first member;
First particles enclosed in a space provided between the first member and the second member, and having at least a surface having an insulating property;
An image display medium comprising: second particles enclosed in the space and having a color different from that of the first particles and at least a surface having an electron transporting property or a hole transporting property. A first member having an insulating property;
A second member having an insulating property disposed opposite to the first member;
First particles enclosed in a space provided between the first member and the second member, and having at least a surface having an insulating property;
An image display medium comprising: second particles enclosed in the space and having a color different from that of the first particles and at least a surface having an electron transporting property or a hole transporting property. A first member having an insulating property;
A second member disposed opposite the first member and having an insulating property;
First particles enclosed in a space provided between the first member and the second member, and having at least a surface having a conductive property;
An image display medium comprising: second particles encapsulated in the space and having a color different from that of the first particles and at least a surface having an insulating property, and are positively or negatively charged. A first member having an electron transporting property;
A second member disposed opposite to the first member and having an electron transporting or insulating property;
First particles encapsulated in a space provided between the first member and the second member and capable of being positively charged and having at least a surface having a property of transporting holes;
An image display medium comprising: second particles enclosed in the space and having a color different from that of the first particles and capable of being negatively charged, and at least a surface having a hole transporting property. A first member having an insulating property;
A second member disposed opposite the first member and having an insulating property;
First particles encapsulated in a space provided between the first member and the second member and capable of being positively charged and having at least a surface having a property of transporting holes;
An image display medium comprising: second particles enclosed in the space and having a color different from that of the first particles and capable of being negatively charged, and at least a surface having a hole transporting property. A first member;
A second member disposed opposite the first member;
First particles encapsulated in a space provided between the first member and the second member and having at least a surface having a property of transporting holes;
An image display medium comprising: second particles enclosed in the space and having a color different from that of the first particles and having at least a surface having an electron transporting property. A first member having an electron transporting or insulating property;
A second member disposed opposite to the first member and having an electron transporting or insulating property;
First particles encapsulated in a space provided between the first member and the second member and having at least a surface having a property of transporting holes;
An image display medium comprising: second particles enclosed in the space and having a color different from that of the first particles and at least a surface having a conductive property. A first member having a hole transporting property;
A second member disposed opposite to the first member and having a hole transporting or insulating property;
First particles encapsulated in a space provided between the first member and the second member, at least a surface having an electron transporting property and capable of being positively charged;
An image display medium comprising: second particles encapsulated in the space and having a color different from that of the first particles and at least a surface having an electron transporting property and can be negatively charged. A first member having an insulating property;
A second member disposed opposite the first member and having an insulating property;
First particles encapsulated in a space provided between the first member and the second member, at least a surface having an electron transporting property and capable of being positively charged;
An image display medium comprising: second particles encapsulated in the space and having a color different from that of the first particles and at least a surface having an electron transporting property and can be negatively charged. A first member having a hole transporting property or an insulating property;
A second member disposed opposite to the first member and having an insulating or hole transporting property;
First particles enclosed in a space provided between the first member and the second member, and having at least a surface having a conductive property;
An image display medium comprising: second particles enclosed in the space and having a color different from that of the first particles and at least a surface having an electron transporting property. A first member having conductive properties;
A second member disposed opposite to the first member and having a conductive property;
First particles enclosed in a space provided between the first member and the second member, and having at least a surface having a conductive property;
An image display medium comprising: second particles enclosed in the space and having a color different from that of the first particles and having at least a surface insulating property. A first member having a hole transporting property;
A second member disposed opposite to the first member and having an electron transporting property;
First particles enclosed in a space provided between the first member and the second member, and having at least a surface having a conductive property;
An image display medium comprising: second particles enclosed in the space and having a color different from that of the first particles and having at least a surface insulating property. A first member having conductive properties;
A second member disposed opposite to the first member and having a hole transporting property, a conductive property or an insulating property;
First particles enclosed in a space provided between the first member and the second member, and having at least a surface having a conductive property;
An image display medium comprising: second particles enclosed in the space and having a color different from that of the first particles and having at least a surface having a hole transport property. A first member having a hole transporting property;
A second member disposed opposite to the first member and having an electron transporting property;
First particles enclosed in a space provided between the first member and the second member, and having at least a surface having a conductive property;
An image display medium comprising: second particles enclosed in the space and having a color different from that of the first particles and at least a surface having a hole transporting property or an electron transporting property. A first member having conductive properties;
A second member disposed opposite to the first member and having an electron transporting property, a conductive property or an insulating property;
First particles enclosed in a space provided between the first member and the second member, and having at least a surface having a conductive property;
An image display medium comprising: second particles enclosed in the space and having a color different from that of the first particles and at least a surface having an electron transporting property.

Images