JP2008250039A - Optical writing type display medium and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent display image quality from being degraded due to degradation in sensitivity of a photoconductive layer, which is caused by pollution of the photoconductive layer with impurities such as ions included in a color layer, in a light writing type display medium to be written from a browsing surface side. <P>SOLUTION: The light writing type display medium 10 includes: a display layer 30 which changes the optical characteristics selectively in accordance with an applied voltage and selectively transmits or reflects light impinging from the browsing surface side; a photoconductive layer 32 which changes the electric resistance in accordance with irradiation of light transmitted through the display layer; a pair of light-transmissive electrode layers 28 and 32 disposed with the display layer 30 and the photoconductive layer 32 therebetween; and a color layer 38 which is disposed on a rear side of the electrode layer 32 disposed on the rear side, out of the pair of electrode layers 28 and 32 and is colored so as to absorb or reflect light transmitted through the electrode layer 32 on the rear side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical writable display medium and a manufacturing method thereof.

  In recent years, electronic paper for the purpose of temporarily browsing electronic information has attracted attention as a display medium. One of the electronic papers is an optical writing type. The optical writable electronic paper is configured by laminating a display layer made of, for example, liquid crystal and a photoconductive layer whose electric resistance is changed by light. Such optically writable electronic paper includes one that forms an image by irradiating light from the viewing surface side and one that forms an image by irradiating light from the opposite side (back side) of the viewing surface. is there. Japanese Patent Application Laid-Open No. HEI 10-110826 discloses an optical writable display medium that forms an image by irradiating light from the back side, and when reading light incident from the viewing surface side passes through the display layer and enters the photoconductive layer, Since characteristics may change, a technique is disclosed in which a colored layer colored so as to absorb light is provided between the display layer and the photoconductive layer so that reading light does not enter the photoconductive layer.

JP 2003-005210 A

  An object of the present invention is to improve display image quality based on sensitivity deterioration of a photoconductive layer due to contamination of the photoconductive layer by impurities such as ions contained in a colored layer in an optical writable display medium written from the viewing surface side. It is to prevent deterioration.

  According to the first aspect of the present invention, the optical characteristics selectively change according to the applied voltage, and the display layer that selectively transmits or reflects the light incident from the viewing surface side, and the display layer is transmitted. A photoconductive layer whose electrical resistance changes in response to light irradiation, a pair of electrode layers disposed so as to sandwich the display layer and the photoconductive layer, and a back side of the pair of electrode layers And a colored layer that is disposed on the back side of the electrode layer and is colored so as to absorb or reflect the light transmitted through the electrode layer on the back side.

  The present invention according to claim 2 is the optically writable display medium according to claim 1, wherein the pair of electrode layers are made of a metal oxide.

  The present invention according to claim 3 is the optically writable display medium according to claim 1 or 2, wherein the colored layer is formed by dispersing a colorant in a polymer resin.

  The present invention according to claim 4 is the optical writable display medium according to any one of claims 1 to 3, further comprising a substrate that supports the electrode layer on the back side, and the substrate constitutes the colored layer.

  The optical writing type display medium according to any one of claims 1 to 3, wherein the present invention according to claim 5 includes a substrate that supports the back side electrode layer, and the colored layer is further provided on the back side of the substrate. It is.

  6. The optical writing display medium according to claim 5, wherein the present invention according to claim 6 further comprises a coating layer covering the back side of the substrate, and the colored layer is provided between the substrate and the coating layer. It is.

  The present invention according to claim 7 is the optical writable display medium according to claim 6, wherein the colored layer is formed by bonding the substrate and the coating layer.

  The present invention according to claim 8 is provided with a water vapor intrusion prevention layer that is disposed between the photoconductive layer and the colored layer and prevents water vapor from entering the photoconductive layer. The optical writing type display medium according to any one of the above.

  The present invention according to claim 9 is the optically writable display medium according to any one of claims 1 to 8, wherein the colored layer has a color of at least a part different from that of the other part.

  According to the tenth aspect of the present invention, a display layer whose optical characteristics are selectively changed according to an applied voltage is formed on a first electrode layer having light transmittance, and a second layer having light transmittance. A photoconductive layer whose electrical resistance changes in response to light irradiation is formed on the electrode layer, and the display layer and the photoconductive layer are provided between the first electrode layer and the second electrode layer. An optically writable display medium in which a colored layer that is bonded so as to be sandwiched and colored so as to absorb or reflect light transmitted through the second electrode layer is disposed further on the back side than the second electrode layer. It is a manufacturing method.

  The present invention according to claim 11 is the method for producing an optically writable display medium according to claim 10, wherein the colored layer contains a colorant in advance.

  The present invention according to claim 12 is the method for producing an optically writable display medium according to claim 10, wherein the colored layer is formed by coating.

  According to the first aspect of the present invention, in the optical writable display medium on which an image is written from the viewing surface side, it is possible to prevent the migration of impurities such as ions contained in the colored layer to the photoconductive layer. It is possible to provide an optical writable display medium that can prevent deterioration in display image quality based on sensitivity deterioration of the photoconductive layer due to contamination of the layer.

  According to the second aspect of the present invention, it is possible to more reliably prevent impurities such as ions contained in the colored layer from moving to the photoconductive layer as compared with the electrode layer made of an organic conductive material or the like. There is an effect that can be done.

  According to the third aspect of the present invention, in addition to the effect of the present invention described in the first or second aspect, even if the colored layer is formed of a polymer material, ions contained in the colored layer, etc. There is an effect that the movement of the impurities to the photoconductive layer can be more reliably prevented.

  According to the fourth aspect of the present invention, in addition to the effects of the present invention described in the first to third aspects, the configuration can be simplified as compared with the case where the colored layer is provided as a single layer. There is an effect.

  According to the fifth aspect of the present invention, it is possible to more reliably prevent migration of impurities such as ions contained in the colored layer to the photoconductive layer as compared with the case where the colored layer is provided inside the substrate. There is an effect that can be done.

  According to the sixth aspect of the present invention, the photoconductivity of impurities such as ions contained in the colored layer is compared with that in which the colored layer is provided inside the coating layer covering the back side of the substrate supporting the electrode layer. There exists an effect that the movement to a layer can be prevented more reliably.

  According to the present invention of claim 7, in addition to the effect of the present invention described in claim 6, the configuration can be simplified as compared with the case where the colored layer is provided as a single layer. Play.

  According to the eighth aspect of the present invention, the photoconductive layer of impurities such as ions contained in the colored layer as compared with the case where the water vapor intrusion preventing layer is not provided between the photoconductive layer and the photocolored layer. There is an effect that it is possible to more reliably prevent the movement to.

  According to the ninth aspect of the present invention, in addition to the effect of the present invention according to any one of the first to eighth aspects, there is an effect that it is possible to provide an optically writable display medium that exhibits different colors depending on parts.

  According to the tenth aspect of the present invention, in the optical writable display medium written from the viewing surface side, it is possible to prevent the migration of impurities such as ions contained in the colored layer to the photoconductive layer. It is possible to provide a method for manufacturing a photo-writing type display medium that can prevent deterioration in display image quality based on sensitivity deterioration of the photoconductive layer due to contamination.

  According to the eleventh aspect of the present invention, in addition to the effect of the present invention described in the tenth aspect, the manufacturing process can be simplified.

  According to the present invention of claim 12, in addition to the effect of the present invention of claim 10, there is an effect that the colored layer can be easily formed.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing an optical writing type display medium 10 and an optical writing device 12 according to the first embodiment of the present invention. FIG. 2 is a plan view showing the optical writable display medium 10 according to the first embodiment of the present invention.
1 and 2, the optical writing display medium 10 is, for example, flexible electronic paper. An image is displayed on one surface and writing light corresponding to the displayed image is incident. . One surface is referred to as a viewing surface, and the other surface is referred to as a back surface.

  The optical writable display medium 10 has a main body 14, and the periphery of the main body 14 is surrounded by a peripheral edge 16. The viewing surface side of the main body portion 14 and the peripheral edge portion 16 is covered with the first covering layer 18 via the first adhesive layer 20, and the back side of the main body portion 14 and the peripheral edge portion 16 is covered with the second covering layer 22. It is covered via the second adhesive layer 24.

  The first coating layer 18 and the second coating layer 22 are made of an insulating material, and are made of, for example, glass, silicon, or a polymer film such as polyvinyl alcohol, polyethylene terephthalate, polysulfone, polyethersulfone, or polycarbonate. . The first coating layer 18 is transmissive to writing light and reading light. The second coating layer 22 may be formed from the same material as the first coating layer 18, but may be formed from another material, and is not necessarily transparent to the writing light and the reading light. Absent.

  The first adhesive layer 20 and the second adhesive layer 24 are made of an adhesive material such as polyurethane or polyester. The first adhesive layer 20 is transmissive to writing light and reading light. The second adhesive layer 24 may be formed from the same material as the first adhesive layer 20, but may be formed from other materials and is not necessarily transparent to the writing light and the reading light. Absent.

  The main body 14 includes a first substrate 26, a first electrode layer 28, a display layer 30, a photoconductive layer 32, a second electrode layer 34, a second substrate 36, and a colored layer 38 from the viewing surface side. Has been.

  The first substrate 26 and the second substrate 36 are made of an insulating material, and are made of, for example, glass, silicon, or a polymer film such as polyvinyl alcohol, polyethylene terephthalate, polysulfone, polyethersulfone, or polycarbonate. The first substrate 26 and the second substrate 36 are transmissive to writing light and reading light.

  The first electrode layer 28 and the second electrode layer 34 sandwich the display layer 30 and the photoconductive layer 32 and have a light-transmitting conductive material so that a voltage is applied to the display layer 30 and the photoconductive layer 32. It is composed of That is, the first electrode layer 28 and the second electrode layer 34 are made of metal oxide such as indium oxide, tin oxide, indium tin oxide (ITO), indium zinc oxide (IZO), or polypyrrole, polyacetylene, or polyaniline. It consists of a conductive organic polymer. From the viewpoint of isolating the photoconductive layer 32 described later from the diffusion of impurities such as ions, a metal oxide having a higher material density and an excellent impurity blocking property is superior to a polymer material.

  The display layer 30 selectively changes its optical characteristics in accordance with an applied voltage and selectively transmits or reflects incident visible light. For example, a liquid crystal is used. Liquid crystals include vertical alignment nematic liquid crystal, parallel alignment nematic liquid crystal, twist nematic liquid crystal, super twist nematic liquid crystal, surface-stabilized ferroelectric liquid crystal, etc. Various liquid crystals with different optical effects, such as a method using a change in state, a method using a change in the light absorption state of a guest-host liquid crystal, or a method using a change in the light interference state of a cholesteric (chiral nematic) liquid crystal An element can be used.

  In this embodiment, the display layer 30 uses cholesteric liquid crystal. However, in addition to the structure consisting only of cholesteric liquid crystals, a structure containing a network polymer in the continuous phase of the liquid crystal, a structure in which the liquid crystal is dispersed in the form of droplets in a polymer binder skeleton, and the liquid crystal is wrapped in a polymer shell. A microencapsulated structure or a structure in which microencapsulated liquid crystal is dispersed in a polymer binder skeleton can be employed.

  Cholesteric liquid crystals include steroidal cholesterol derivatives or chiral components made of optically active materials such as Schiff bases, azos, esters or biphenyls, and Schiff bases, azos, azoxys, benzoates, biphenyls. Terphenyl, cyclohexylcarboxylic acid ester, phenylcyclohexane, biphenylcyclohexane, pyrimidine, dioxane, cyclohexylcyclohexane ester, cyclohexylethane, cyclohexane, tolan, alkenyl, stilbene, condensed polycycle A material added to a nematic liquid crystal, a smectic liquid crystal, or a mixed liquid crystal thereof can be used, and the dielectric anisotropy is configured to be positive.

  Cholesteric liquid crystal with positive dielectric anisotropy is a planar crystal whose spiral axis is almost perpendicular to the cell surface and causes the above-mentioned selective reflection phenomenon with respect to incident light. The spiral axis is almost parallel to the cell surface and incident. Three states are shown: a focal conic that transmits light while being slightly scattered forward, and a homeotropic structure in which a helical structure is unwound and the liquid crystal director is directed in the direction of the electric field and transmits incident light almost completely.

  Of these three states, the planar and focal conic can exist bistable with no voltage. Therefore, the alignment state of the cholesteric liquid crystal is not uniquely determined with respect to the applied voltage, and when the initial state is planar, it changes in the order of planar, focal conic, and homeotropic as the applied voltage increases. When the initial state is focal conic, it changes in the order of focal conic and homeotropic as the applied voltage increases. On the other hand, when the applied voltage is suddenly reduced to zero, the planar and focal conic remain as they are, and the homeotropic changes to the planar.

FIG. 3 is a schematic diagram showing optical characteristics of the cholesteric liquid crystal immediately after the pulse voltage is applied.
In FIG. 3, the vertical axis represents the normalized reflectance normalized with the maximum reflectance being 100 and the minimum reflectance being 0, and the horizontal axis is the applied pulse voltage. The curve indicated by the solid line in the figure represents the optical characteristics of the cholesteric liquid crystal immediately after the pulse voltage is applied. When the applied pulse voltage is equal to or higher than the threshold voltage Vfh, the selective reflection state changes from homeotropic to planar. When the voltage is between the voltage Vpf and the voltage Vfh, the transmission state is caused by focal conic. When the voltage is equal to or lower than the voltage Vpf, the state before the pulse voltage is applied, that is, the selective reflection state by the planar or the transmission state by the focal conic is continued. .

  As shown in FIG. 4, the photoconductive layer 32 includes, for example, three layers, and has a configuration in which a charge transport layer 326 is provided between the upper charge generation layer 322 and the lower charge dispatch layer 324. In the upper charge generation layer 322 and the lower charge generation layer 324, a charge shipping substance is dispersed in a polymer binder. In the charge transport layer 326, a charge transport material is dispersed in a polymer binder.

  As the charge generation material, inorganic materials such as a-Si, ZnS, ZnO, CdS, CdSe, Se, SeTe, or TiO, or phthalocyanine, azo, polycyclic quinone, indigo, quinacridone, perylene, Organic materials such as squalium, azulenium, cyanine, pyrylium, and anthrone can be used.

  As the charge transport material, organic materials such as carbazole, triazole, oxadiazole, imidazole, pyrazoline, hydrazone, stilbene, amine, or nitrofluorenone can be used.

  As the polymer binder, polycarbonate, polyarylate, polyvinyl alcohol (PVA), polyethylene, polypropylene, polyester, polyvinyl acetate, polyvinyl butyral, acrylic, methacryl, vinyl chloride, vinyl acetate, or a copolymer thereof can be used. .

  The colored layer 38 is provided further on the back side than the second electrode layer 34. In this embodiment, the back surface of the second substrate 36 is formed by coloring it in black and is formed by dispersing a pigment or dye as a colorant in the resin. For example, carbon black, which is a black pigment, is dispersed in a polymer binder. It is inevitable that impurities such as ions remaining in the raw material or in the production process remain in the pigment or dye. Impurities diffuse over time into other layers, and if the impurities are ions, the influence of the electric field applied for writing cannot be ignored. Such impurities are relatively less leaked if the object to be dispersed is a material having a high material density such as an inorganic material. However, if the display medium is to be flexible, a material having a low density such as a polymer resin must be used, so that the isolation from the impurities becomes insufficient, and the impurities are transferred to the photoconductive layer. The effect of becomes remarkable. For this reason, when a colorant is dispersed in a flexible polymer resin, it is desirable to use a metal oxide as the electrode layer as described above.

  A water vapor intrusion prevention layer can be provided between the photoconductive layer 32 and the colored layer 38. For example, as shown in FIG. 5, the water vapor intrusion prevention layer 40 is disposed between the photoconductive layer 32 and the second electrode layer 34. As the water vapor intrusion prevention layer 40, for example, a layer formed by sputtering SiOx (x = 1.5 to 1.7) or SiON or a layer obtained by spin coating an aqueous solution of polyvinyl alcohol (PVA) is used. Here, as well as the electrode layer, an inorganic thin film such as an inorganic oxide is preferably used as the water vapor intrusion prevention layer because it is isolated from impurities by using a material of a high density inorganic material.

    In addition, as shown in FIG. 2, electrode holes 42 are formed on the front and back of the optical writable display medium 10, and the first electrode layer 28 and the second electrode layer 34 are formed through the electrode holes 42. It is exposed so that it can be connected to a voltage application unit 44 of the optical writing device 12 described later.

  The optical writing device 12 includes a voltage application unit 44, a control unit 46, and a light emitting device 48. The voltage application unit 44 is connected to the first electrode layer 28 and the second electrode layer 34 of the optical writable display medium 10 and applies a pulse voltage to the first electrode layer 28 and the second electrode layer 34.

  The control unit 46 controls the application of the pulse voltage of the voltage application unit 44 and the light emission of the light emitting device 48.

  The light emitting device 48 only needs to be capable of irradiating arbitrary writing light from the viewing surface side of the main body 14 of the optical writable display medium 10, and includes a laser beam scanning device, an LED array, a CRT display, a plasma display, an EL display, and the like. The self-luminous element or a light control element such as a liquid crystal shutter and a light source such as a fluorescent tube, a xenon lamp, a halogen lamp, a mercury lamp or an LED lamp are not particularly limited.

FIG. 6 is an equivalent circuit diagram of the main body 14 of the optical writable display medium 10.
In FIG. 6, the main body 14 of the optical writable display medium 10 includes a parallel circuit including a resistance R1 of electrode layers 28 and 34, a resistance R2 of a display layer 30 and a capacitance C2, and a resistance R3 and electrostatic capacitance of other layers. A parallel circuit composed of a capacitor C3 and a parallel circuit composed of a resistor R3 of the photoconductive layer 32 and a capacitance C3 are connected in series. The voltage V applied between the electrode layers 28 and 34 from the voltage application unit 44 is divided by the impedance of each circuit. Here, when write light is irradiated from the light emitting device 48 to the photoconductive layer 32, the resistance value R4 of the photoconductive layer 32 decreases, so that the partial pressure V2 applied to the portion of the display layer 30 irradiated with the write light. Becomes higher than the portion not irradiated with the writing light. Accordingly, the voltage distribution of the display layer 30 changes according to the light amount of the writing light, and the optical state of the display layer also changes according to the voltage distribution. Therefore, the light amount distribution of the writing light is reflected in the reflectance distribution of the reading light. Can be made.

Next, a method for writing an image on the optical writing type display medium 10 using the optical writing device 12 will be described.
First, the optical writing type display medium 10 is set in the optical writing device 12 arranged in a dark room or the like. When the setting of the optical writing medium 10 is completed, the control unit 46 instructs the voltage application unit 44 to apply a pulse voltage between the electrode layers 28 and 34. The pulse voltage applied by the voltage application unit 44 is set so that the partial pressure of the display layer 30 is between Vpf and Vfh. For this reason, the liquid crystal of the display layer 30 is in a transmissive state by focal conic. Next, the control unit 46 instructs the light emitting device 48 to irradiate the optical writing type display medium 10 with the writing light corresponding to the image. The optical writing light irradiated from the viewing surface side is transmitted through the first coating layer 18, the first adhesive layer 20, the first substrate 26, the first electrode layer 28, and the display layer 30 of the main body 14. The conductive layer 32 is reached. When the optical writing light reaches the photoconductive layer 32, the resistance value R4 of the photoconductive layer 32 decreases, so that the partial pressure V2 applied to the portion irradiated with the writing light in the display layer 26 becomes higher than Vfh. , That part changes homeotropic. Next, the control unit 42 commands the pulse voltage between the electrode layers 24 and 34 to suddenly become zero. When the pulse voltage between the electrode layers 28 and 34 is abruptly reduced to zero, the portion of the display layer 30 corresponding to the portion irradiated with the writing light changes to a planar portion, and the portion not irradiated with the writing light remains as a focal conic. In this state, image formation is completed. Even if the optical writing type display medium 10 is separated from the optical writing device 12, the liquid crystal state of the display layer 30 is maintained as it is, and an image is stored in the optical writing type display medium 10.

  When reading light, which is external light, is irradiated onto the optically writable display medium 10 on which an image is thus formed, the focal conic portion of the display layer 30 is the first covering layer 18 and the first adhesive layer. 20, the first electrode layer 28, the display layer 30, the photoconductive layer 32, the second electrode layer 34, and the second substrate 36, reach the colored layer 38, and the reading light is absorbed so that it appears as black. become. On the other hand, in the planar state portion of the display layer 30, the readout light is reflected by the display layer 30 and appears white.

  FIG. 7 shows an optical writable display medium 10 according to the second embodiment. In the second embodiment, the second substrate 36 constitutes a colored layer. That is, the second substrate 36 is configured by including a colorant such as carbon black in a polymer film such as polyvinyl alcohol.

  FIG. 8 shows an optical writable display medium 10 according to the third embodiment. In the third embodiment, the second adhesive layer 24 constitutes a colored layer. That is, the second adhesive layer 24 is configured by kneading a colorant such as carbon black into an adhesive material.

  FIG. 9 shows an optical writable display medium 10 according to the fourth embodiment. In the fourth embodiment, the colored layer 38 is formed by coloring the viewing surface of the second coating layer 22 with black, for example, carbon black is dispersed in a polymer binder.

  FIG. 10 shows an optically writable display medium 10 according to the fifth actual form. In the fifth embodiment, the second coating layer 22 constitutes a colored layer. That is, the second coating layer 22 is configured by including a colorant such as carbon black in a polymer film such as polyvinyl alcohol.

  FIG. 11 shows an optical writable display medium 10 according to the sixth embodiment. Compared with the first embodiment, the colored layer 38 in the first embodiment described above is black and absorbs light, whereas the colored layer 38 in the sixth embodiment is white and reflects light. For example, the color of the photoconductive layer 32 is reflected. That is, if the photoconductive layer 32 is, for example, phthalocyanine-based, the light reflected from the colored layer 38 exhibits blue, and the read light has two colors, white and blue.

FIG. 12 shows an optical writable display medium 10 according to the seventh embodiment. In the seventh embodiment, the colored layer 38 includes a first portion 38a colored in black and a second portion 38b colored in white. In the first portion 38a, the reading light becomes white and black, whereas in the second portion 38b, the color of the photoconductive layer 32 is reflected, for example, white and blue.
In addition, this invention is not limited to dividing | segmenting the colored layer 38 into two parts like this 7th Embodiment, It can divide | segment into three or more parts, and can each make a color different. In addition, the coloring color is not limited to black or white, but may be colored in other colors.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In the following, “%” means “mass%” and “parts” means “mass parts”.

Example 1:
FIG. 13 is a cross-sectional view illustrating the layer structure of the main body 14 according to the first embodiment. FIG. 14 is a process diagram illustrating the manufacturing process of the main body 14 according to the first embodiment. In the first embodiment, the first substrate 26, the first electrode layer 28, and the display layer 30 are used as the first film member 50, and the second substrate 36, the second electrode layer 34, the photoconductive layer 32, The isolation layer 52 and the laminate layer 54 are used as the second film member 56, the first film member 50 and the second film member 56 are collated, and the colored layer 38 is formed on the back surface of the second substrate 36. A main body 14 is configured.

(First film member 50)
1. As the 1st board | substrate 26 and the 1st electrode layer 28, a commercially available ITO vapor deposition PET resin film (High Beam: Toray) is used. The first substrate 26 and the first electrode layer 28 are washed and dried.
2. A cholesteric liquid crystal is used for the display layer 30. The cholesteric liquid crystal was obtained by adding 12.8% of the chiral agent R811 (made by Merck) and 3.2% of the chiral agent R1011 (made by Merck) to the nematic liquid crystal E7 (made by Merck). To 10 parts of this cholesteric liquid crystal, 1.2 parts of polyisocyanate compound Takenate D-110N (manufactured by Takeda Pharmaceutical Co., Ltd.) and 100 parts of ethyl acetate are added to prepare an oil phase composition, which is made of 1% polyvinyl alcohol. (Poval 217EE: manufactured by Kuraray) It was put into 1000 parts of an aqueous solution, stirred and emulsified to prepare an o / w emulsion having a diameter of about 10 μm. This was heated at 60 ° C. for 3 hours to obtain a microcapsule using polyurethane as a wall material. After the microcapsules were collected by centrifugation, a 12% polyvinyl alcohol (Poval 217C: manufactured by Kuraray) aqueous solution was added to obtain a microcapsule liquid crystal paint. First electrode layer 28 The microcapsule liquid crystal paint is applied to a dry film thickness of 30 μm and dried at 100 ° C. for 30 minutes.
3. Electrode holes 42 are formed.
4). The coating film on the electrode part is removed.

(Second film member 56)
1. As the 2nd board | substrate 36 and the 1st electrode layer 34, a commercially available ITO vapor deposition PET resin film (High Beam: Toray) is used. The second substrate 36 and the first electrode layer 34 are washed and dried.
2. As a dispersion for the lower charge generation layer, chlorogallium phthalocyanine is used as a charge generation material, polyvinyl butyral is used as a binder resin, the mass ratio of both is 6: 4, and this is dispersed in butanol (concentration 4%) Was prepared. This dispersion was applied onto the charge transport layer by spin coating and then dried to form a lower charge generation layer 324 having a thickness of 0.8 μm.
3. As a solution for the charge transport layer, a benzidine charge transport material and a binder resin PolyCarbonate bisphenol-Z (poly (4,4′-cyclohexylidene diphenylene carbonate)) are mixed at a mass ratio of 6: 4, respectively. Was dissolved in monochlorobenzene to prepare a 10% solution. A charge transport layer 326 having a thickness of 8 μm was formed on the lower charge generation layer 324 using an applicator having a gap width of 80 μm.
4). As a dispersion for the upper charge generation layer, chlorogallium phthalocyanine is used as a charge generation material, polyvinyl butyral is used as a binder resin, and the mass ratio of both is 6: 4, which is dispersed in butanol (concentration 2%) Was prepared. This dispersion was applied onto the charge transport layer 326 by spin coating and then dried to form an upper charge generation layer 322 having a thickness of 0.2 μm.
5. As the isolation layer 52, an aqueous solution in which 6% of PVA was dissolved was prepared, and this was formed on the upper charge generation layer so as to have a dry film thickness of 1 μm, and dried at 100 ° C. for 30 minutes.
6). Electrode holes 42 are formed.
7). The coating film on the electrode part is removed.
8). Masking is performed.
9. Using butyl acetate as a solvent, a two-component urethane adhesive Takelac A50 / A315 (Mitsui Chemicals Polyurethane) was used to coat the isolation layer 52 by spin coating, using a laminating ink. The laminate layer 54 was dried.

(Collation, colored layer)
1. The first film member 50 and the second film member 56 produced as described above are stacked at 90 ° C. with the display layer 30 of the first film member 50 and the laminate layer 56 of the second film member 56 overlapped. Collate through a heated laminator.
2. The colored layer 38 was formed by screen printing. Screen printing ink was kneaded 100 parts of Toyo Ink Co., Ltd. screen process ink SS16-000 series 911 black, 10 parts of SSUR100B additive, 10 parts of diluted solvent S-787, and Shintaro Awatori Kentaro ARE250 The mixture was degassed with stirring for 1 minute × 2 times and used. Printing plate is Tokyo Process Service Co., Ltd. screen mask, mesh number 180, mesh specification stainless steel, bias 30 °, emulsion thickness 10μm, ridge thickness 98μm, total thickness 106μm, tension 0.21 to 0.29mm, plate frame size 850 × 850 mm was used. The printing device is a screen printer MT-1100TVC manufactured by Micro Tech Co., Ltd., clearance 1.5 mm, squeegee hardness B70, squeegee length 300 mm, squeegee head angle 70 °, squeegee tack angle 70 °, set squeegee printing pressure 0.25 MPa. , A set scraper pressure of 0.2 MPa, a back pressure of 0.1 MPa, a squeegee speed of 50 mm / sec, and a scraper speed of 50 mm / sec. After printing, it was dried in an oven at 65 ° C. for 30 minutes to form a good colored layer having a dry film thickness of 20 to 25 μm and an optical density of 2.0 or more.
The back Bk printing is not limited to the screen printing method, and may be spray coating or gravure printing.
3. The body formed as described above was punched and molded to obtain a main body portion 14.

Example 2:
FIG. 15 is a cross-sectional view illustrating the layer structure of the main body 14 according to the second embodiment. FIG. 16 is a process diagram illustrating the manufacturing process of the main body 14 according to the second embodiment. The second embodiment is different from the first embodiment in that a water vapor intrusion preventing layer 40 is disposed between the photoconductive layer 32 and the second electrode layer 34. In the second step after the second substrate 36 provided with the second electrode layer 34 is cleaned and dried, the water vapor intrusion prevention layer 40 is formed by using a completely saponified polyvinyl alcohol (PVA) aqueous solution as the second electrode. A PVA film having a thickness of 0.2 μm and spin-coated on the layer 34 was obtained.

  FIG. 17 is a cross-sectional view showing the layer structure of the main body 14 according to the comparative example. FIG. 18 is a process diagram showing a manufacturing process of the main body 14 according to the comparative example. This comparative example is different from the first embodiment in that the colored layer 38 is disposed between the photoconductive layer 32 and the second electrode layer 34. The colored layer 38 in this comparative example is formed by the same method as in Example 1 in the second step after the second substrate 36 provided with the second electrode layer 34 is washed and dried. 34 formed.

FIG. 19 shows a state in which the comparative example was rewritten by irradiating light on the entire surface after being left at a high temperature of 50 ° C. for 5 days. In the comparative example, when rewriting is performed, a haze-like portion with blackishness appears where it should originally be white. That is, as shown in FIG. 20, initially, a predetermined reflectance can be obtained with a predetermined amount of light, but when left at a high temperature, the reflectance of a white image with respect to the same amount of light decreases.
In the comparative example, since the colored layer 38 is in direct contact with the photoconductive layer 32, the photoconductive layer 32 is contaminated by impurities such as ions contained in the colored layer 38, and the photoconductive layer 32 is deteriorated. it is conceivable that.

  On the other hand, in Example 1, the second electrode layer 34 and the second substrate 36 are interposed between the photoconductive layer 32 and the colored layer 38. In Example 2, the photoconductive layer 32 and the colored layer 38 are interposed. Since the water vapor intrusion prevention layer 40, the second electrode layer 34, and the second substrate 36 are interposed therebetween, migration of impurities such as ions contained in the colored layer 38 can be prevented.

  FIG. 21 shows the change in reflectance of Example 1, Example 2 and Comparative Example with respect to 70 ° C. heating time (the vertical axis is the ratio of the reflectance to the initial reflectance). In the comparative example, the reflectivity decreases and fog occurs in about 20 hours, whereas in Examples 1 and 2, the reflectivity does not decrease even after 90 hours, and the generation of fog occurs. I couldn't see it.

  FIG. 22 shows the change in reflectance when the image is rewritten repeatedly at 800 v / 400 μw (the vertical axis is the ratio of the reflectance to the initial reflectance). In the comparative example, the reflectivity decreased after about 1.5k times, whereas in Examples 1 and 2, the reflectivity did not decrease even when the value exceeded 2.5k times.

1 is a schematic diagram illustrating an optical writing display medium and an optical writing device according to a first embodiment of the present invention. 1 is a plan view showing an optically writable display medium according to a first embodiment of the present invention. It is a schematic diagram which shows the optical characteristic at the time of a pulse voltage being applied to the cholesteric liquid crystal used for the display layer of the 1st Embodiment of this invention. It is sectional drawing which shows the detail of the photoconductive layer used for the 1st Embodiment of this invention. It is sectional drawing which shows the modification of the 1st Embodiment of this invention. It is a circuit diagram which shows the equivalent circuit schematic of the optical writable display medium in the 1st Embodiment of this invention. It is sectional drawing which shows the optical writable display medium which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the optical writing type display medium which concerns on the 3rd Embodiment of this invention. It is sectional drawing which shows the optical writing type display medium which concerns on the 4th Embodiment of this invention. It is sectional drawing which shows the optical writable display medium which concerns on the 5th Embodiment of this invention. It is sectional drawing which shows the optical writing type display medium which concerns on the 6th Embodiment of this invention. It is sectional drawing which shows the optical writable display medium which concerns on the 7th Embodiment of this invention, and a top view which shows a colored layer. 3 is a cross-sectional view showing a layer structure of a main body according to Example 1. FIG. FIG. 6 is a process diagram illustrating a manufacturing process of the main body according to the first embodiment. 6 is a cross-sectional view showing a layer structure of a main body according to Example 2. FIG. FIG. 6 is a process diagram illustrating a manufacturing process of a main body according to a second embodiment. It is sectional drawing which shows the layer structure of the main-body part which concerns on a comparative example. It is process drawing which shows the manufacturing process of the main-body part which concerns on a comparative example. It is a top view which shows the state rewritten after leaving a comparative example to stand under high temperature. In a comparative example, it is a diagram which shows the change of the image reflectance with respect to the image writing light quantity. It is a diagram which shows the reflectance change of Example 1, Example 2, and a comparative example with respect to heating time. It is a diagram which shows the reflectance change at the time of rewriting an image repeatedly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical writing type display medium 12 Optical writing apparatus 14 Main-body part 16 Peripheral part 18 1st coating layer 20 1st contact bonding layer 22 2nd coating layer 24 2nd contact bonding layer 26 1st board | substrate 28 1st electrode Layer 30 Display layer 32 Photoconductive layer 34 Second electrode layer 36 Second substrate 38 Colored layer 40 Water vapor intrusion prevention layer

Claims (12)

A display layer that selectively changes optical characteristics according to an applied voltage and selectively transmits or reflects light incident from the viewing surface side;
A photoconductive layer whose electrical resistance changes in response to irradiation with light transmitted through the display layer;
A pair of electrode layers disposed so as to sandwich the display layer and the photoconductive layer and having light transmittance;
A colored layer disposed on the back side further than the electrode layer disposed on the back side of the pair of electrode layers, and colored to absorb or reflect light transmitted through the electrode layer on the back side;
An optically writable display medium.   The optically writable display medium according to claim 1, wherein the pair of electrode layers is made of a metal oxide.   The optically writable display medium according to claim 1, wherein the colored layer is formed by dispersing a colorant in a polymer resin.   4. The optically writable display medium according to claim 1, further comprising a substrate that supports the back side electrode layer, wherein the substrate constitutes the colored layer. 5.   4. The optically writable display medium according to claim 1, further comprising a substrate that supports the electrode layer on the back side, wherein the colored layer is further provided on the back side of the substrate.   The optical writable display medium according to claim 5, further comprising a coating layer that covers a back side of the substrate, wherein the colored layer is provided between the substrate and the coating layer.   The optically writable display medium according to claim 6, wherein the colored layer is formed by bonding the substrate and the coating layer.   8. The optical writable display medium according to claim 1, further comprising a water vapor intrusion prevention layer disposed between the photoconductive layer and the colored layer and preventing water vapor from entering the photoconductive layer. .   9. The optically writable display medium according to claim 1, wherein at least a part of the colored layer is different in color from other parts.   A display layer whose optical characteristics are selectively changed according to an applied voltage is formed on the first electrode layer having optical transparency, and light irradiation is performed on the second electrode layer having optical transparency. A photoconductive layer whose electrical resistance varies in accordance with the first electrode layer and the second electrode layer, the display layer and the photoconductive layer are joined to be sandwiched between the first electrode layer and the second electrode layer, A method for producing an optical writable display medium, wherein a colored layer colored so as to absorb or reflect light transmitted through the second electrode layer is disposed further on the back side than the second electrode layer.   The method for producing an optically writable display medium according to claim 10, wherein the colored layer contains a colorant in advance.   The method of manufacturing an optically writable display medium according to claim 10, wherein the colored layer is formed by coating.