JP2005221953A - Optical writing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical writing device capable of preventing a write image from deteriorating owing to external light when the image is written by using a both-surface light emitting display element and simultaneously and excellently performing image display and image writing by the both-surface light emitting display element. <P>SOLUTION: An optical write display medium 10 is constituted by sandwiching a display layer and a photoconductive layer, having memory property, between a couple of substrates where electrodes are formed. A 1st polarizing means 62 and a 2nd polarizing means 63 are composed of linear polarizers and arranged at extinction positions. Images are emitted from both the surfaces of the both-surface light emitting display element 61; the image emitted from the surface is viewed by an observer and the optical write display medium 10 is irradiated with the inverted image emitted from the backside. At this point, external light is transmitted through the 1st polarizing means 62 and both-surface light emitting display element 61, but absorbed by the 2nd polarizing means 63 and never reaches the optical write display medium 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical writing device, and more particularly to an optical writing device that writes an image on an optical writing display medium having a memory property.

  In recent years, optical writing display media capable of repeatedly recording and erasing images have attracted attention as environmentally friendly display recording media.

  FIG. 6 shows a cross-sectional view of such an optical writing display medium. As shown in FIG. 6, the optical writable display medium 10 has a display layer 30 having a memory property and a photoconductivity whose electric resistance changes according to the irradiated light. The photoconductive layer 40 having the structure is sandwiched between the substrate 11 on which the electrode 21 is formed and the substrate 12 on which the electrode 22 is formed. A voltage applying means 50 for applying a predetermined voltage for image writing is connected to the electrode 21 and the electrode 22.

  As shown in FIG. 7, the writing of the image to the optical writing display medium 10 is performed by applying the voltage from the voltage applying unit 50 while exposing the optical writing display medium 10 using the exposure unit 60. This is done by applying a pulse. Since the electrical resistance of the photoconductive layer 40 decreases in the bright part of the exposed image, a high voltage is divided on the display layer 30, and in the dark part of the exposed image, the electrical resistance of the photoconductive layer 40 is high. Only a low voltage is divided into the layer 30. Therefore, the exposed image can be recorded on the display layer 30 by setting the threshold voltage at which the brightness of the display layer 30 changes to the middle of the partial pressure fluctuation.

  Then, by applying a display element that responds to an electric field and has a memory property, such as an electrophoretic element, a ferroelectric liquid crystal element, or a cholesteric liquid crystal element, to the display layer 30, even after the image exposure and voltage application are finished Can be maintained.

  Incidentally, since the exposure means 60 is a device that emits an image as a light image, it can also be used as a display device. Accordingly, in FIG. 7, normally, the optical writing display medium 10 is not mounted, but the exposure means 60 is used as a display device, and the optical writing display medium 10 is mounted and an image is recorded only when recording is necessary. It can be used in the form of

  In this case, as shown in FIG. 8, the optical writing display medium 10 is loaded on the stocker 82, and the optical writing display medium 10 is moved to the exposure position, that is, the exposure means 60 by the conveying means 81 only when recording is necessary. Transport to the position directly above. Then, while exposing the image to the optical writing display medium 10 by the exposure unit 60, a voltage pulse is applied by the voltage application unit 50 to record the image, and the image is discharged to the stocker 83. By automatically performing such a series of steps, it is possible to save the trouble of manually mounting the optical writing display medium 10 one by one when it is desired to record an image on the optical writing display medium 10. .

  However, in the configuration shown in FIG. 8, when the optical writing display medium 10 is at the exposure position, the display image of the exposure unit 60 as a display device is blocked by the optical writing display medium 10 and cannot be seen. was there. In addition, it is not preferable as a product design to dispose the conveying unit 81 in front of the exposure unit 60 as a display device, and there is a problem that a display image is difficult to see because the display position is deepened.

Therefore, for example, a double-sided light emitting display element capable of displaying images on both sides described in Patent Document 1 is used as the exposure unit, whereby the optical writing display medium 10 is arranged below the exposure unit, and both sides are arranged. It is conceivable that the image displayed on the front surface of the light emitting display element is made visible from the viewer side, and at the same time, the image is written on the optical writing display medium 10 by the image displayed on the back surface of the double light emitting display element.
JP 2001-332392 A

  However, in the configuration using the double-sided light emitting display element as described above, there is a problem that the image written on the optical writing display medium 10 may be deteriorated by the external light transmitted through the double-sided light emitting display element. .

  The present invention has been made to solve the above-described problems, and prevents deterioration of a written image due to external light when an image is written using a double-sided light emitting display element, and allows image display using a double-sided light emitting display element. It is an object of the present invention to provide an optical writing device that can be well performed simultaneously with image writing.

  In order to achieve the above object, the invention described in claim 1 has a display layer whose display state changes according to an electric field and has a memory property, and photoconductivity whose electric resistance changes according to incident light. An optical writing device for writing an image on an optical writing display medium comprising a photoconductive layer exhibiting photoconductivity sandwiched between a pair of substrates each having an electrode formed thereon, and applying a voltage to the electrode A voltage applying unit; a first polarizing unit configured to polarize incident light in a predetermined polarization state; a second polarizing unit disposed to be in an extinction position with respect to the first polarizing unit; and the first polarizing unit An exposure display unit that is disposed between a polarization unit and the second polarization unit, and that can transmit incident light while maintaining a polarization state, and that includes a double-sided light emitting display element that emits an image on both sides; and It is provided with.

  The optical writing display medium has a configuration in which a display layer and a photoconductive layer are sandwiched between a pair of substrates each having an electrode formed thereon.

  The display layer changes its display state according to an electric field and has memory properties, and the photoconductive layer has photoconductivity whose electric resistance changes according to incident light. Therefore, by irradiating the image on the optical writing display medium and applying a predetermined voltage for writing the image between the electrodes, the electrical resistance of the photoconductive layer changes according to the image and the display state of the display layer is the image. And the irradiated image is written. Since the display layer has a memory property, image display is maintained even after application of voltage is stopped.

  Such an optical writing device for writing an image on the optical writing display medium includes voltage applying means for applying a voltage to the electrodes formed on the pair of substrates of the optical writing display medium.

  In addition, the optical writing apparatus includes an exposure display unit that displays an image for display and an image writing for the optical writing display medium.

  The exposure display unit includes a first polarizing unit, a second polarizing unit, and a double-sided light emitting display element.

  The first polarization means polarizes incident light into a predetermined polarization state. The second polarizing means is for polarizing incident light into a predetermined polarization state, and is disposed so as to be in an extinction position with respect to the first polarizing means.

  The double-sided light emitting display element is disposed between the first polarizing means and the second polarizing means, can transmit incident light while maintaining the polarization state, and emits images on both sides.

  In this way, since the double-sided light emitting display element emits images from both sides, the image emitted from the front surface of the double-sided light emitting display element is used for display, and the image emitted from the back surface is used as an optical writing display medium. Can be used for writing.

  In addition, as the double-sided light emitting display element, for example, an organic electroluminescence (EL) element, an inorganic EL element, a plasma display, or the like can be used. It has the property of transmitting incident light from

  For this reason, when such a double-sided light emitting display element is used as it is for image writing on an optical writing display medium, external light incident from the observer side enters the photoconductive layer of the optical writing display medium. As a result, image quality deterioration called “fogging” occurs.

  On the other hand, in the present invention, since the double-sided light emitting display element is arranged between the first polarizing means and the second polarizing means as described above, the external light incident from the observer side is Although the first polarizing means and the double-sided light emitting display element are transmitted, they are absorbed by the second polarizing means and can be prevented from entering the photoconductive layer. Therefore, it is possible to prevent an image deteriorated due to so-called “fogging” from being written on the optical writing display medium.

  In addition, since it becomes possible to arrange an optical writing display medium on the back side of the double-sided light emitting display element, it is possible to simultaneously write an image while displaying an image, and an exposure display means is arranged on the front side. By doing so, the visibility of the image can be improved.

  According to a second aspect of the present invention, the first polarizing means and the second polarizing means are each composed of a linear polarizer, and are arranged so that the polarization direction of each linear polarizer is an extinction position. Can be configured.

  According to a third aspect of the present invention, the first polarizing means includes a first linear polarizer, a first unit disposed between the first linear polarizer and the double-sided light emitting display element. A retardation plate, the slow axis of the first retardation plate and the transmission axis of the first linear polarizer are arranged at a predetermined angle, and the second polarizing means is A second retardation plate disposed between the second linear polarizer, the second linear polarizer and the double-sided light emitting display element; and a slow axis of the second retardation plate and the second retardation plate It is good also as a structure arrange | positioned so that the transmission axis of a 2nd linear polarizer may become a predetermined predetermined angle.

  For example, the angle formed by the slow axis of the first retardation plate and the transmission axis of the first linear polarizer, and the angle formed by the slow axis of the second retardation plate and the transmission axis of the second linear polarizer And each polarizer and the phase difference plate are arranged so that each becomes 45 degrees. Thereby, since the first polarizing means and the second polarizing means act as a circularly polarizing plate, it is possible to block the light reflected on each surface and inside of the double-sided light emitting display element, and increase the display contrast. Can do.

  At this time, as described in claim 4, it is preferable that the slow axis of the first retardation plate and the slow axis of the second retardation plate are arranged so as to be orthogonal to each other. . Thereby, coloring due to wavelength dispersion characteristics can be prevented.

  Further, as described in claim 5, it is preferable that the first polarizing means, the double-sided light emitting display element, and the second polarizing means are arranged in close contact with each other. Thereby, deterioration of the display image and exposure image by surface reflection can be reduced.

  According to a sixth aspect of the present invention, it is preferable that an imaging lens is further provided between the exposure display unit and the optical writing display medium. This can prevent the image from being blurred.

  As described above, according to the present invention, it is possible to prevent deterioration of a written image due to external light when an image is written using a double-sided light emitting display element, and to simultaneously perform image display using a double-sided light emitting display element. It has the effect that it can be performed satisfactorily.

(First embodiment)
The first embodiment of the present invention will be described below.

  FIG. 1 shows a side view of an exposure display device 20 that displays an image and irradiates the image to write the image on the optical writing display medium 10 as shown in FIG.

  The exposure display device 20 has a configuration in which a double-sided light emitting display element 61 is disposed between a first polarizing means 62 and a second polarizing means 63.

  As the double-sided light emitting display element 61, a display element is used in which incident light from the outside can be transmitted while maintaining the polarization state, and images can be displayed on both sides. That is, the double-sided light emitting display element 61 displays an image on the surface and an image obtained by inverting the image displayed on the surface on the top surface. As such a dual emission type display element, for example, an organic EL, an inorganic EL, a plasma display, a fluorescent display tube (VFD), a field emission display (FED), or the like is used.

  An organic EL has a structure in which an electrode as a cathode, an electron transport layer, a light-emitting layer, a hole transport layer, and an electrode as an anode are stacked. Electrons injected from the cathode and positive electrodes injected from the anode are stacked. It is a kind of LED (Light Emitting Diode) that emits light by recombination with holes in the light emitting layer.

  The number of layers of the electron transport layer, the light emitting layer, and the hole transport layer can be reduced by providing two or more functions in one layer. In these functional layers, since the thickness of each layer is usually as thin as about 100 nm, there is almost no change in the polarization state due to light scattering, optical rotation, and birefringence. Therefore, if a material that does not absorb light is selected, a display element that is transparent and transmits external light while maintaining a polarization state can be manufactured.

  Further, as the cathode, an opaque low work function metal such as MgAg has been used to reduce the electron injection voltage, but it has been difficult to realize double-sided light emission. It has become possible to use a transparent conductive material such as indium tin oxide by inserting a carrier injection layer between them. Thereby, a double-sided light emitting display element can be realized.

  Inorganic EL is a high-bandgap semiconductor with an emission center element added. Electrons are injected from the interface state under a high electric field, and the electric field is accelerated to cause collisional excitation to the emission center to emit light. is there.

  Inorganic EL includes a dispersion type EL in which semiconductor particles are dispersed in a resin binder and a double insulation type EL in which an electrode, an insulating layer, a semiconductor layer, an insulating layer, and an electrode are stacked. The double insulating structure type EL is preferable because of its high property and low birefringence. By using a transparent conductive material such as indium tin oxide as an electrode, a double-sided light emitting display element can be realized.

  A plasma display has a rare gas sealed between a pair of electrodes, and uses a visible light emission when a voltage is applied between the electrodes to cause glow discharge, and a phosphor layer is formed on one substrate. In some cases, display is performed by exciting phosphors using ultraviolet light emitted when glow discharge is performed.

  In the former case, a double-sided light emitting display element can be easily realized by using a transparent conductive material such as indium tin oxide for the electrode. In the latter case, a double-sided light emitting display device is realized by using a transparent conductive material such as indium tin oxide for the electrode using materials with low light scattering and birefringence, such as ultrafine phosphors and vapor-deposited phosphors. it can.

  A VFD is a structure in which a structure comprising a hot cathode, a control grid electrode, a phosphor layer, and an anode is formed in a vacuum cell, and hot electrons are emitted by energizing and heating the hot cathode. Display is performed by accelerating by the electric field applied between the electrodes and causing collisional excitation to the phosphor. The on / off control of display is performed by controlling the passage amount of thermoelectrons with the voltage of the control grid electrode. The hot cathode and the control grid electrode are usually formed in a mesh shape and have translucency. For this reason, a double-sided light emitting display element can be realized by using a transparent conductive material for the anode and a material having little light scattering and birefringence for the phosphor layer.

  The FED is obtained by replacing the hot cathode of the VFD with a cold cathode such as a Spindt type field emission device or a carbon nanotube field emission device. By forming the cold cathode in a mesh shape, a double-sided light emitting display element can be realized as in the case of VFD.

  A control device (not shown) corresponding to the display element is connected to the double-sided light emitting display element 61, and this control device is controlled to display a desired image on the double-sided light emitting display element 61.

  The first polarizing means 62 and the second polarizing means 63 use linear polarizers, respectively, and are arranged so that these linear polarizers are in the extinction position. For example, the transmission axis of the first polarization unit 62 and the transmission axis of the second polarization unit 63 are arranged so as to be orthogonal to each other. As a result, as shown in FIG. 1, external light incident on the exposure display device 20 from the observer side is converted into linearly polarized light along the transmission axis by the first polarizing means 62, and a double-sided light emitting display element is obtained. 61, but the transmission axis of the second polarizing means 63 is orthogonal to the transmission axis of the first polarizing means 62, so that it is converted into linearly polarized light by the first polarizing means 62 and is a double-sided light emitting type. The light that has passed through the display element 61 is not transmitted, and the optical writing display medium 10 can be prevented from being irradiated with external light. Therefore, the optical writing display medium 10 is irradiated only with the image displayed by the double-sided light emitting display element 61.

  Further, the display image emitted on the front surface side of the double-sided light emitting display element 61 is observed by the observer through the first polarizing means 62, and the display image emitted on the back surface side of the double-sided light emitting display element 61. Of the optical writing display medium 10 is irradiated through the second polarizing means 63.

  As described above, the double-sided light emitting display element 61 is sandwiched between the first polarizing means 62 and the second polarizing means 63 whose transmission axes are orthogonal to each other, so that external light is irradiated onto the optical writing display medium 10. Therefore, it is possible to irradiate only the image from the double-sided light emitting display element 61, and it is possible to prevent the image written on the optical writing display medium 10 from being deteriorated by so-called fogging.

  Here, the extinction position does not mean that the transmission axis of the first polarizing means 62 and the transmission axis of the second polarizing means 63 are strictly orthogonal, and is written into the optical writing display medium 10. As long as the deterioration of the image is within an allowable range, the transmission axes of the two may be deviated from the orthogonal position. An allowable range of deviation from a position where the transmission axes of the two are orthogonal to each other is determined by, for example, the relationship with the reflectance of the optical writing display medium 10.

  As the linear polarizer, a known film polarizer of iodine type or dye type can be used.

  In FIG. 1, the first polarizing means 62 and the second polarizing means 63 are separated from the double-sided light emitting display element 61. However, the display image and optical document of the double-sided light emitting display element 61 by surface reflection are used. In order to reduce the deterioration of the exposure image with respect to the embedded display medium 10, the first polarizing means 62 and the second polarizing means 63 are preferably in close contact with or adhered to the double-sided light emitting display element 61.

  In the optical writing display medium 10, as shown in FIG. 6 described above, the display layer 30 and the photoconductive layer 40 are sandwiched between the substrate 11 on which the electrode 21 is formed and the substrate 12 on which the electrode 22 is formed. It is the structure which was made.

For the electrodes 21 and 22, a light-transmitting conductor such as a metal thin film such as Au, an oxide conductor such as ITO (Indium Tin Oxide), SnO ₂ , or ZnO, or a conductive polymer such as polypyrrole or PEDOT is used. . Since the electrodes 21 and 22 are generally thin and cannot be handled as a free-standing film, they are formed on the substrates 11 and 12 in advance.

  A transparent dielectric is used for the substrates 11 and 12. For example, glass, ceramic, resin (for example, polyethylene terephthalate, polycarbonate, polyether sulfone, polyolefin) or the like is used.

  As the display layer 30, a display element having a memory property in which a display state changes according to an electric field and display can be maintained without a power source is used. Examples of such elements include electrophoretic elements that move charged colored fine particles in water or gas by an electric field, such as memory liquid crystal elements such as cholesteric liquid crystals, ferroelectric liquid crystals, bistable nematic liquid crystals, smectic liquid crystals, and the like. There are electrochromic material elements, electroplating elements, and the like using conductive polymers, oxides such as tungsten oxide, and organic dyes such as viologen.

Examples of the photoconductive layer 40 include amorphous silicon, inorganic semiconductor materials such as compound semiconductors such as ZnSe and CdS, organic semiconductor materials such as anthracene and polyvinylcarbazole, and perylene-based, phthalocyanine-based materials that generate charges by light irradiation, Charge transfer materials such as bisazo, dithiopytoceropyrrole, squarylium, azurenium, and thiapyrylium / polycarbonate compounds generate charge transfer by electric field. For example, trinitrofluorene, polyvinylcarbazole, oxadiazole, pyralizone system, hydrazone, stilbene, triphenylamine, triphenylmethane, and diamine-based compounds, polyvinyl was added LiClO ₄ alcohol - le and the ionic conductive materials, such as polyethylene oxide Complexes such as the charge transport material can be used. In addition, a laminated body, a mixture, a microcapsule, etc. can be used as a composite form.

  Such exposure (writing) of an image to the optical writing display medium 10 can be performed from the substrate 12 side or from the substrate 11 side through the display layer 30. However, usually, the image quality is better when the display image is observed from the substrate 11 side than when the image is observed from the substrate 12 side (when the image is observed from the substrate 12 side, the photoconductive layer 40 is positioned in front of the display layer 30). Therefore, in order to arrange the exposure display device 20 and the optical writing display medium 10 in this order from the front of the observer so that the image written on the optical writing display medium 10 does not turn over, the inverted image is displayed on the substrate 11. In order to irradiate from the side, it is preferable to arrange the substrate 11 side to face the back side of the double-sided light emitting display element 61.

  In addition, since the image is blurred when the distance between the light emitting surface of the double-sided light emitting display element 61 and the optical writing display medium 10 is increased, the exposure display device 20 and the optical writing display medium 10 should be arranged as close as possible to each other. However, as shown in FIG. 2, for example, an imaging unit 70 may be provided between the exposure display device 20 and the optical writing display medium 10.

  As the image forming means 70, in addition to lenses, a micro louver or capillary plate that absorbs light other than straight light and suppresses the spread, a Selfoc lens array or a micro lens array in which lenses for forming an erect image are arranged in an array shape, and the like are used. Can be used.

  FIG. 3 shows an optical writing system 80 including an exposure display device 20 that writes an image on the optical writing display medium 10.

  As shown in FIG. 3, the optical writing system 80 includes an exposure display device 20, a voltage applying unit 50, a conveying unit 81, and stockers 82 and 83.

  An image is displayed on the double-sided light emitting display element 61 of the exposure display device 20 under the control of a control device (not shown), and this image can be viewed from the observer side.

  The stocker 82 stocks the optical writing display medium 10 before image writing. When a conveyance instruction is given to the conveyance means 81 by a conveyance control means (not shown), the conveyance means 81 conveys the optical writing display medium 10 at the top of the stocker 82 in the left direction in FIG. The conveyance is stopped when the medium 10 is positioned directly below the exposure display device 20.

  Since the reverse image of the image displayed on the front surface is displayed on the back surface of the double-sided light emitting display element 61, the reverse image is irradiated on the optical writing display medium 10 positioned immediately below the exposure display device 20. The In this state, the voltage applying unit 50 applies a predetermined voltage for image writing to the electrodes 21 and 22. As a result, the electrical resistance of the photoconductive layer 40 changes according to the inverted image irradiated from the exposure display device 20 to the display layer 30, and is thereby displayed on the surface of the double-sided light emitting display element 61 on the display layer 30. The same image as the image is displayed. Since the display layer 30 is composed of a display element having a memory property, the display of the written image is maintained even after the voltage application by the voltage application means 50 is stopped.

  When an image is written on the optical writing display medium 10, the conveyance by the conveyance unit 81 is resumed and stocked in the stocker 83.

  Thus, the exposure display device 20 according to the present invention has a configuration in which the double-sided light emitting display element 61 is sandwiched between the first polarizing means 62 and the second polarizing means 63 arranged so that the transmission axis is in the extinction position. Therefore, it is possible to block external light from the observer side. For this reason, the optical writing display medium 10 can be disposed on the back side of the exposure display device 20 when viewed from the observer side, and the design is excellent and the displayed image can be viewed well from the observer side. Can do. Further, it is possible to write an image in a state where the image is displayed by the exposure display device 20, and it is possible to realize an image display that does not give the viewer a feeling of strangeness.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the present embodiment, modified examples of the first polarizing means 62 and the second polarizing means 63 will be described. In addition, the same code | symbol is attached | subjected to the same part as the said 1st Embodiment, and the detailed description is abbreviate | omitted.

  As shown in FIG. 4, in this embodiment, the 1st polarizing means 62 is comprised by the 1st linear polarizer 62a and the 1st 1/4 phase difference plate 62b. The first quarter retardation plate 62b is disposed between the first linear polarizer 62a and the double-sided light emitting display element 61, and the slow axis of the first quarter retardation plate 62b is The first linear polarizer 62a is disposed at an angle of 45 degrees (135 degrees) with respect to the transmission axis of the first linear polarizer 62a.

  Similar to the first polarizing means 62, the second polarizing means 63 is composed of a second linear polarizer 63a and a second 1/4 phase difference plate 63b. The second quarter retardation plate 63b is disposed between the second linear polarizer 63a and the double-sided light emitting display element 61, and the slow axis of the second quarter retardation plate 63b is The second linear polarizer 63a is disposed at an angle of 45 degrees (135 degrees) with respect to the transmission axis of the second linear polarizer 63a.

  In the case of such a configuration, the first polarizing means 62, the second linear polarizer 63a, and the second ¼ retardation plate 63b, which are composed of the first linear polarizer 62a and the first ¼ retardation plate 62b. The second polarizing means 63 comprising the above functions as a so-called circularly polarizing plate. As is well known, the circularly polarizing plate has an antireflection effect, is incident from the viewer side, is reflected on the front surface, the back surface, and the inside of the double-sided light emitting display element 61, and again from the viewer side. It has the effect of blocking the emitted light. For this reason, the display contrast of the double-sided light emitting display element 61 can be increased.

  As shown in FIG. 4, the light incident on the first linear polarizer 62a is linearly polarized by the first linear polarizer 62a, and is circularly polarized by being delayed by the first ¼ phase plate 62b. . The circularly polarized light passes through the double-sided light emitting display element 61 in the polarization state as it is, is delayed by the second quarter retardation plate 63b, and is returned to linearly polarized light. Since the polarization direction of the linearly polarized light is orthogonal to the transmission axis of the second linear polarizer 63a, the light linearly polarized by the second quarter retardation plate 63b is the second linear polarizer 63a. Permeation is prevented. As described above, the second linear polarizer 63a is arranged so that the polarization direction of the linearly polarized light by the second quarter retardation plate 63b and the transmission axis of the second linear polarizer 63a are orthogonal to each other. Transmission can be prevented.

  Further, since the light transmitted through the double-sided light emitting display element 61 is circularly polarized light, the second polarizing means 63 in FIG. 4 is rotated around an axis perpendicular to the paper surface, for example, as shown in FIG. Since the basic action of preventing the transmission of external light is not changed even when rotated by 90 degrees, a second quarter retardation plate 63b and a second linear polarizer 63a are arranged as shown in FIG. May be. However, in order to prevent coloring due to the wavelength dispersion characteristic, as shown in FIG. 4, the slow axis of the first 1/4 retardation plate 62b and the slow axis of the first 1/4 retardation plate 63b are used. It is preferable to arrange so as to be orthogonal to each other. Here, the orthogonal is not required to be strictly orthogonal.

  In addition, as a linear polarizer, as above-mentioned, the iodine-type or dye-type well-known film polarizer can be used.

  Moreover, as a 1/4 phase difference plate, the film which extended | stretched transparent resins, such as polyether sulfone, a polycarbonate, polymethyl methacrylate, polyvinyl alcohol, can be used. In order to prevent coloring of display, it is preferable to use a material in which the wavelength dispersion of retardation (= product of birefringence and thickness) is compensated.

  Next, examples of the present invention will be described.

  A commercially available ITO / PET resin film was prepared as the substrate 11 on which the electrode 21 was formed, and a cholesteric liquid crystal microcapsule coating was applied as a display layer 30 on the surface of the ITO electrode. On the other hand, another ITO / PET resin film is prepared as the substrate 12 on which the electrode 22 is formed. On the ITO electrode surface, a first charge generation layer using a phthalocyanine pigment, a diphenylamine-based charge transport layer, and a phthalocyanine pigment are prepared. The second charge generation layer using was sequentially applied to form a photoconductive layer 40 having a three-layer structure.

  Thus, the optical writing display medium 10 was produced by bonding together the board | substrate 11 in which the display layer 30 was formed, and the board | substrate 12 in which the photoconductive layer 40 was produced with the adhesive agent.

  Next, an inorganic EL panel (made by Denso) using ZnS: Mn as a light emitting material is prepared as the double-sided light emitting display element 61, and the first polarizing unit 62 and the second polarizing unit 63 are provided on both sides. The two linear polarizers were pasted so as to be in the extinction position, and the exposure display device 20 was obtained.

  In the double-sided light emitting display element 61 before the linear polarizer is pasted, the display image may be difficult to see because the opposite side (the back side) is seen through, but the exposure display according to the present invention with the linear polarizer pasted is sometimes present. The apparatus 20 did not have such a situation, and a clear image display could be performed.

  Further, the optical writing display medium 10 produced by the above-described method is placed in close contact with the back surface of the exposure display device 20, and a symmetrical rectangular wave having a frequency of 10 Hz and a voltage of 380 V is applied between the electrodes 21 and 22 for 200 ms. However, the display image could be recorded clearly.

It is a side view which shows the structure of an optical writing device. It is a side view which shows the other example of an optical writing device. It is a figure which shows schematic structure of an optical writing system. It is a figure which shows the other example of the exposure display apparatus. It is a figure which shows the other example of the 2nd polarizing means. It is sectional drawing of an optical writing display medium. It is a figure which shows the structure of the conventional optical writing apparatus. It is a figure which shows the structure of the conventional optical writing system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Optical writing display medium 11, 12 Board | substrate 20 Exposure display apparatus 21, 22 Electrode 22 Electrode 30 Display layer 40 Photoconductive layer 50 Voltage application means 60 Exposure means 61 Double-sided light emission type display element 62b 1st 1/4 phase difference plate 62a First linear polarizer 62 First polarizing means 63b Second quarter phase plate 63a Second linear polarizer 63 Second polarizing means 70 Imaging means 80 Optical writing system 81 Conveying means 82, 83 Stocker 83 stocker

Claims (6)

An electrode is formed on each of a display layer having a memory property and a display state that changes in response to an electric field, and a photoconductive layer having a photoconductivity in which an electric resistance changes in response to incident light. An optical writing device for writing an image on an optical writing display medium sandwiched between a pair of substrates,
Voltage applying means for applying a voltage to the electrode;
First polarizing means for polarizing incident light into a predetermined polarization state, second polarizing means arranged so as to be in an extinction position with respect to the first polarizing means, and the first polarizing means and the first polarizing means An exposure display means which is disposed between the two polarization means and is capable of transmitting incident light while maintaining the polarization state, and which comprises a double-sided light emitting display element which emits an image on both sides;
An optical writing device comprising:   2. The first polarizing means and the second polarizing means are each composed of a linear polarizer, and are arranged so that the polarization direction of each linear polarizer is an extinction position. Optical writing device. The first polarizing means includes a first linear polarizer and a first retardation plate disposed between the first linear polarizer and the double-sided light emitting display element. The slow axis of the phase difference plate and the transmission axis of the first linear polarizer are arranged at a predetermined angle,
The second polarizing means includes a second linear polarizer, a second retardation plate disposed between the second linear polarizer and the double-sided light emitting display element, and the second position plate. 2. The optical writing device according to claim 1, wherein the slow axis of the phase difference plate and the transmission axis of the second linear polarizer are arranged at a predetermined angle.   4. The optical writing device according to claim 3, wherein the slow axis of the first retardation plate and the slow axis of the second retardation plate are arranged to be orthogonal to each other.   5. The optical book according to claim 1, wherein the first polarizing unit, the double-sided light emitting display element, and the second polarizing unit are arranged in close contact with each other. Device.   6. The optical writing apparatus according to claim 1, further comprising an imaging lens between the exposure display unit and the optical writing display medium.

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