JP2010091916A - Optical writing device and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the void of an image, when the image is written and to easily visually recognize the image, when the image except when the image is written is visually recognized. <P>SOLUTION: An optical writing device includes: an irradiation part 32 as a writing means which irradiates the photoconductor layer 10 of an optical writing type image display medium 1 with writing light from the side of the photoconductor layer 10, to write the image on a display layer 7; a platen cover 16 as a light quantity adjusting means which is provided so as to adjust the light quantity of reflected light reflected from the display layer 7 and incident light made incident on the display layer 7; and a control part 30 as a control means which controls the platen cover 16 as the light quantity adjusting means, so that the light quantity of the incident light made incident on the display layer 7 is a predetermined light quantity Q or less, when the image is written and the light quantity with which the image of the display layer 7 is visible by the reflected light reflected from the display layer 7 is obtained, when the written image is visually recognized. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical writing device and a program.

  Conventionally, electronic paper is known as an optical writing type image display medium (see, for example, Patent Document 1). Further, a technique of an optical writing device that writes an image on such an image display medium is known (see, for example, Patent Document 2).

Here, an optical writing type image display medium having a light shielding film between the display layer and the photoconductor layer is conceivable.
JP 2000-180888 A JP 2001-1000066 A

  The present invention provides an optical writing device and a program capable of preventing an overexposure of an image at the time of image writing and easily viewing an image when an image other than the time of image writing is viewed. Objective.

  In order to achieve the above object, an optical writing device according to the first aspect of the present invention includes a photoconductor layer whose magnitude of electrical resistance changes according to the amount of irradiated write light, and the photoconductor layer; And a light-shielding layer that shields light of less than a predetermined intensity between them, and light having a wavelength according to the magnitude of the voltage applied through the photoconductor layer and the light-shielding layer. An image is displayed on the display layer by irradiating the photoconductor layer of the photo-writing type image display medium having a display layer that displays an image by reflection and transmission with the writing light from the photoconductor layer side. Writing means, light amount adjusting means provided to adjust the amount of reflected light reflected from the display layer and incident light incident on the display layer, and when writing an image to the display layer Incident light Is less than a predetermined light amount, and when the written image is viewed, the light amount adjusting means is controlled so that the image on the display layer becomes a visible light amount by the reflected light reflected from the display layer. And control means.

  In the optical writing device according to the second aspect of the present invention, the light amount adjusting means is disposed at a light shielding position for blocking incident light incident on the display layer and a transmission position for transmitting reflected light reflected from the display layer. In the case of comprising a light-shielding member provided on the display layer side so as to be movable, and when the control means moves the light-shielding member to the light-shielding position when writing an image and visually recognizes the written image. The light shielding member is controlled to move the light shielding member to the transmission position.

  According to a third aspect of the present invention, in the optical writing device according to the third aspect of the invention, the light amount adjusting means is reflected from the display layer, the first transmittance that blocks incident light incident on the display layer, and the display layer. The light control member can be changed to the second transmittance that transmits the reflected light, and when the image is written, the transmittance becomes the first transmittance, and the written image is visually recognized. In this case, the light control member is controlled so that the transmittance of the light control member becomes the second transmittance.

  According to a fourth aspect of the present invention, in the optical writing apparatus according to the fourth aspect, the writing means controls the writing means so that the writing light is applied to the photoconductor layer based on image information when writing the image. It is what you do.

  In order to achieve the above object, a program according to a fifth aspect of the invention provides a computer comprising: a photoconductor layer whose magnitude of electrical resistance changes according to the amount of irradiated write light; A wavelength corresponding to the magnitude of the voltage applied through the photoconductor layer and the light shielding layer, with a light shielding layer that shields light of less than a predetermined intensity between the body layer and the light shielding layer. By irradiating the photoconductor layer of the photo-writing type image display medium provided with a display layer that displays an image by reflecting and transmitting the light of the light from the photoconductor layer side, the display When an image is written by a writing means for writing an image to the layer, the amount of incident light incident on the display layer is equal to or less than a predetermined amount, and when the written image is viewed, the light is reflected from the display layer. The light amount adjustment provided to adjust the light amount of the reflected light reflected from the display layer and the incident light incident on the display layer so that the image of the display layer can be visually recognized by the reflected light. It is for functioning as control means for controlling the means.

  According to each of the first to fifth aspects of the invention, it is possible to prevent overexposure of an image at the time of writing the image and to easily view the image when viewing an image other than the time of writing the image. Has the effect.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a cross-sectional view of an optically writable display medium 1 according to this embodiment. The display medium 1 is a display medium capable of recording an image by applying address light according to the image and applying a bias signal (voltage).

  As shown in FIG. 1, a display medium (optical writing type image display medium) 1 includes, in order from the display surface side, a transparent substrate 3, a transparent electrode 5, a display layer (liquid crystal layer) 7, a laminate layer 8, and a light shielding layer (colored). Layer) 9, the photoconductor layer 10, the transparent electrode 6, and the transparent substrate 4 are laminated.

  The transparent substrates 3 and 4 are for holding each functional layer on the inner surface and maintaining the structure of the display medium. The transparent substrates 3 and 4 are made of a sheet-shaped member having a strength that can withstand external force. The transparent substrate 3 on the display surface side receives at least incident light, and the transparent substrate 4 on the writing surface side receives at least address light (writing light). , Respectively. It is preferable that the transparent substrates 3 and 4 have flexibility. Specific examples of the material include an inorganic sheet (for example, glass / silicon) and a polymer film (for example, polyethylene terephthalate, polysulfone, polyethersulfone, polycarbonate, polyethylene naphthalate). A known functional film such as an antifouling film, an anti-abrasion film, a light antireflection film, or a gas barrier film may be formed on the outer surface.

  The transparent substrates 3 and 4 have transparency over the entire visible light range in this embodiment, but may have transparency only in the wavelength range to be displayed.

  The transparent electrodes 5 and 6 are for applying a bias voltage applied from the optical writing device (optical recording device) 2 shown in FIG. 2 to each functional layer in the display medium 1. In the present embodiment, the transparent electrode 5 is composed of, for example, three divided electrodes 5A, 5B, and 5C having substantially the same shape (for example, a rectangular shape), and the transparent electrode 6 has an area corresponding to substantially the entire surface of the display medium 1. It is comprised with the single transparent electrode which has. The transparent electrodes 5 and 6 have surface-uniform conductivity, the transparent electrode 5 on the display surface side transmits at least incident light, and the transparent electrode 6 on the writing surface side transmits at least address light. Specifically, it is formed of metal (for example, gold, aluminum), metal oxide (for example, indium oxide, tin oxide, indium tin oxide (ITO)), conductive organic polymer (for example, polythiophene-based / polyaniline-based), etc. An electroconductive thin film can be mentioned. A known functional film such as an adhesion improving film, an antireflection film, or a gas barrier film may be formed on the surface.

  The transparent electrodes 5 and 6 have transparency over the entire visible light range in this embodiment, but may have transparency only in the wavelength range to be displayed.

  The display layer 7 has a function of modulating a reflection / transmission state of specific color light of incident light by an electric field, and has a property of maintaining the selected state with no electric field. The display layer 7 preferably has a structure that is not deformed by an external force such as bending or pressure. The display layer 7 is disposed with the light shielding layer 9 interposed between the display layer 7 and the photoconductor layer 10 described in detail below, and reflects and transmits light having a wavelength corresponding to the magnitude of the applied voltage. To display an image.

  In the present embodiment, the display layer 7 is constituted by a liquid crystal layer of a self-holding type liquid crystal composite made of cholesteric liquid crystal and transparent resin as an example. That is, although it is a liquid crystal layer that does not require a spacer or the like because it has a self-holding property as a composite, it is not limited to this. In the present embodiment, as shown in FIG. 1, cholesteric liquid crystal 12 is dispersed in a polymer matrix (transparent resin) 11.

  The cholesteric liquid crystal 12 has a function of modulating the reflection / transmission state of specific color light of incident light, and liquid crystal molecules are twisted and aligned in a spiral shape. Interference reflection of specific light depending on The orientation is changed by the electric field, and the reflection state can be changed. In the case of color display, it is preferable that the drop size is uniform and the single layer is densely arranged.

  Specific liquid crystals that can be used as the cholesteric liquid crystal 12 include nematic liquid crystals and smectic liquid crystals (for example, Schiff base, azo, azoxy, benzoate, biphenyl, terphenyl, cyclohexylcarboxylate, phenyl). Cyclohexane, biphenylcyclohexane, pyrimidine, dioxane, cyclohexylcyclohexane ester, cyclohexylethane, cyclohexane, tolan, alkenyl, stilbene, condensed polycyclic), or a mixture thereof with a chiral agent (for example, And steroidal cholesterol derivatives, Schiff bases, azos, esters, and biphenyls).

  The helical pitch of the cholesteric liquid crystal is adjusted by the amount of chiral agent added to the nematic liquid crystal. For example, when the display colors are blue, green, and red, the center wavelengths of selective reflection are in the range of 400 nm to 500 nm, 500 nm to 600 nm, and 600 nm to 700 nm, respectively. Further, in order to compensate the temperature dependence of the helical pitch of the cholesteric liquid crystal, a known method of adding a plurality of chiral agents having different twisting directions or opposite temperature dependences may be used.

  As a form in which the display layer 7 forms a self-supporting liquid crystal composite composed of a cholesteric liquid crystal 12 and a polymer matrix (transparent resin) 11, a PNLC (Polymer Network Liquid Crystal) containing a network-like resin in the continuous phase of the cholesteric liquid crystal. ) Structure and PDLC (Polymer Dispersed Liquid Crystal) structure (including microencapsulated) in which cholesteric liquid crystal is dispersed in the form of droplets in a polymer skeleton. By doing so, an anchoring effect is produced at the interface between the cholesteric liquid crystal and the polymer, and the planar state or the focal conic phase holding state without an electric field can be made more stable.

  The PNLC structure or PDLC structure is a known method for phase-separating a polymer and a liquid crystal, for example, an acrylic, thiol, or epoxy-based polymer precursor that is polymerized by heat, light, electron beam, or the like. Polymers having low liquid crystal solubility such as PIPS (Polymerization Induced Phase Separation) method, polyvinyl alcohol, and the like, which are mixed, polymerized from a homogeneous phase, and phase-separated, are mixed, and suspended by stirring to increase the liquid crystal. Emulsion method in which droplets are dispersed in a molecule, TIPS (Thermally Induced Phase Separation) method in which a thermoplastic polymer and liquid crystal are mixed, cooled to a homogeneous phase, and then phase-separated, and the polymer and liquid crystal are mixed with chloroform. Evaporate the solvent Allowed can be formed by a polymer and liquid crystal and SIPS for phase separation (Solvent Induced Phase Separation) method, and is not particularly limited.

  The polymer matrix 11 holds the cholesteric liquid crystal 12 and has a function of suppressing the flow of liquid crystal (change in image) due to deformation of the display medium. The polymer matrix 11 does not dissolve in the liquid crystal material and does not dissolve in the liquid crystal. A polymer material using as a solvent is preferably used. The polymer matrix 11 is desirably a material that has strength to withstand external force and exhibits high transparency at least for reflected light and address light.

  Examples of materials that can be used as the polymer matrix 11 include water-soluble polymer materials (eg, gelatin, polyvinyl alcohol, cellulose derivatives, polyacrylic acid polymers, ethyleneimine, polyethylene oxide, polyacrylamide, polystyrene sulfonate, polyamidine, isoprene). Sulfonic acid polymers) or materials that can be emulsified in water (for example, fluororesin, silicone resin, acrylic resin, urethane resin, epoxy resin).

  The photoconductor layer 10 is a layer having an internal photoelectric effect and a characteristic that impedance characteristics change according to the irradiation intensity of address light. AC operation is possible, and it is preferable to drive symmetrically with respect to the address light, and a three-layer structure in which a charge generation layer (CGL) is stacked above and below a charge transport layer (CTL) is preferable. In the present embodiment, as an example of the photoconductor layer 10, an upper charge generation layer 13, a charge transport layer 14, and a lower charge generation layer 15 are stacked in order from the upper layer in FIG. The photoconductor layer 10 changes its electrical resistance in accordance with the amount of write light irradiated.

  The charge generation layers 13 and 15 are layers having a function of generating address carriers by absorbing address light. The amount of photocarriers that the charge generation layer 13 mainly flows in the direction from the transparent electrode 5 on the display surface side (display layer 7 side) to the transparent electrode 6 on the writing surface side (photoconductor layer 10 side) is mainly determined by the charge generation layer 15. , Respectively, influences the amount of light carriers flowing from the transparent electrode 6 on the writing surface side to the transparent electrode 5 on the display surface side. The charge generation layers 13 and 15 are preferably those that absorb address light to generate excitons and are efficiently separated into free carriers inside the charge generation layer or at the charge generation layer / charge transport layer interface.

  The charge generation layers 13 and 15 include charge generation materials (for example, metal or metal-free phthalocyanine, squalium compound, azurenium compound, perylene pigment, indigo pigment, azo pigment such as bis and tris, quinacridone pigment, pyrrolopyrrole dye, polycyclic quinone pigment, A dry method of directly forming a film of a condensed ring aromatic pigment such as dibromoanthanthrone, a cyanine dye, a xanthene pigment, a charge transfer complex such as polyvinylcarbazole and nitrofluorene, or a symbiotic complex composed of a pyrylium salt dye and a polycarbonate resin) Charge generating materials are polymer binders (eg, polyvinyl butyral resin, polyarylate resin, polyester resin, phenol resin, vinyl carbazole resin, vinyl formal resin, partially modified vinyl acetal resin, carbonate resin, acrylic resin. Oil, vinyl chloride resin, styrene resin, vinyl acetate resin, vinyl acetate resin, silicone resin, etc.) in a suitable solvent to prepare a coating solution, which is applied and dried to form a film. Or the like.

  The charge transport layer 14 is a layer having a function of drifting in the direction of the electric field applied by the bias signal when the photocarriers generated in the charge generation layers 13 and 15 are injected. Since the charge transport layer generally has a thickness several tens of times that of the charge generation layer, the capacitance of the charge transport layer 14, the dark current of the charge transport layer 14, and the photocarrier current inside the charge transport layer 14 are reduced by the photoconductor layer. The overall light / dark impedance of 10 is determined.

  The charge transport layer 14 efficiently injects free carriers from the charge generation layers 13 and 15 (preferably close to the ionization potential of the charge generation layers 13 and 15), and the injected free carriers hop as fast as possible. Those that move are preferred. In order to increase the dark impedance, it is preferable that the dark current due to the heat carrier is low.

  The charge transport layer 14 is composed of a low molecular hole transport material (for example, trinitrofluorene compound, polyvinylcarbazole compound, oxadiazole compound, hydrazone compound such as benzylamino hydrazone or quinoline hydrazone, stilbene compound, Triphenylamine compounds, triphenylmethane compounds, benzidine compounds) or low molecular electron transport materials (eg quinone compounds, tetracyanoquinodimethane compounds, fluorenone compounds, xanthone compounds, benzophenone compounds) , Dispersed or dissolved in an appropriate solvent together with a polymer binder (for example, polycarbonate resin, polyarylate resin, polyester resin, polyimide resin, polyamide resin, polystyrene resin, silicon-containing crosslinked resin, etc.) The hole transport material and electron transport material were prepared are dispersed or dissolved in a suitable solvent polymerized material may be formed by this coating drying.

  The light shielding layer (colored layer) 9 optically separates the address light and the incident light at the time of writing, prevents malfunction due to mutual interference, and optically separates the external light incident from the non-display surface side of the display medium and the display image at the time of display. This is a layer provided for the purpose of preventing deterioration of image quality. For this purpose, the light shielding layer 9 is required to have a function of absorbing at least light in the absorption wavelength region of the charge generation layer and light in the reflection wavelength region of the display layer. The light shielding layer 9 shields the incident light if the light intensity of the light incident on the light shielding layer 9 is less than a predetermined value K, but the light intensity of the light incident on the light shielding layer 9 is When the light is equal to or greater than a predetermined value K, the incident light is transmitted. That is, when the optical writing type image display medium 1 is arranged so as to be optically writable to the optical writing device 2, the intensity of light incident from the display surface side is determined in advance when light is written to the image display medium 1. If the value is equal to or greater than the value K, this light may leak into the photoconductor layer 10 and the photoconductor layer 10 may be irradiated with light having an intensity higher than that of the writing light.

  Specifically, the colored layer 9 is an inorganic pigment (for example, cadmium-based, chromium-based, cobalt-based, manganese-based, or carbon-based), or an organic dye or organic pigment (azo-based, anthraquinone-based, indigo-based, or triphenylmethane-based). Nitro, phthalocyanine, perylene, pyrrolopyrrole, quinacridone, polycyclic quinone, squalium, azurenium, cyanine, pyrylium, anthrone) on the charge generation layer 13 side of the photoconductor layer 10 Either a dry method in which a film is formed directly on the surface, or these are dispersed or dissolved in a suitable solvent together with a polymer binder (for example, polyvinyl alcohol resin, polyacrylic resin, etc.) to prepare a coating solution, which is applied and dried. The film can be formed by a wet coating method for forming a film.

  The laminate layer 8 is a layer provided for the purpose of absorbing irregularities and bonding when the functional layers formed on the inner surfaces of the upper and lower substrates are bonded to each other, and is not an essential component in the present embodiment. The laminate layer 8 is made of a polymer material having a low glass transition point, and a material that can adhere and bond the display layer 7 and the colored layer 9 by heat or pressure is selected. In addition, it is necessary to have transparency to at least incident light.

  As a material suitable for the laminate layer 8, an adhesive polymer material (for example, urethane resin, epoxy resin, acrylic resin, silicone resin) can be used.

  FIG. 3 is a circuit diagram showing an equivalent circuit of the display medium (liquid crystal device) 1 having the structure shown in FIG. Clc, Copc, Rlc, and Ropc are the capacitance and resistance values of the display layer 7 and the photoconductor layer 10, respectively. Ce and Re are equivalent capacitances and equivalent resistance values of components other than the display layer 7 and the photoconductor layer 10.

  Assuming that the voltage applied from the external writing device 2 between the transparent electrode 5 and the transparent electrode 6 of the display medium 1 is V, each component includes divided voltages Vlc, Vopc and Ve determined by the impedance ratio between the components. Is applied. More specifically, immediately after the voltage is applied, a partial pressure determined by the capacity ratio of each component is generated, and as time passes, the partial pressure is determined by the resistance value ratio of each component. Go.

  Here, since the resistance value Ropc of the photoconductor layer 10 changes according to the intensity (light quantity) of the address light, the effective voltage applied to the display layer 7 by exposure and non-exposure can be controlled. At the time of exposure, the resistance value Ropc of the photoconductor layer 10 becomes small and the effective voltage applied to the display layer 7 becomes large. Conversely, at the time of non-exposure, the resistance value Ropc of the photoconductor layer 10 becomes large and becomes on the display layer 7. The effective voltage applied is small.

  Next, the cholesteric liquid crystal (chiral nematic liquid crystal) 12 will be specifically described. The planar phase shown by the cholesteric liquid crystal 12 divides light incident parallel to the helical axis into right-handed rotation and left-handed rotation, Bragg-reflects circularly polarized light components that coincide with the twisted direction of the spiral, and selectively reflects the remaining light. Cause a phenomenon. The central wavelength λ and the reflection wavelength width Δλ of the reflected light are λ = n · p and Δλ =, where p is the helical pitch, n is the average refractive index in the plane orthogonal to the helical axis, and Δn is the birefringence. The light reflected by the cholesteric liquid crystal layer in the planar phase expressed by Δn · p exhibits a bright color depending on the helical pitch.

  As shown in FIG. 4A, the cholesteric liquid crystal having positive dielectric anisotropy has a planar phase in which the helical axis is perpendicular to the cell surface and causes the above-described selective reflection phenomenon with respect to incident light. As shown in (B), the spiral axis is almost parallel to the cell surface, and the focal conic phase that transmits incident light while being slightly scattered forward, and the spiral structure is unwound as shown in FIG. The director shows three states: a homeotropic phase in which the director is directed in the direction of the electric field and almost completely transmits the incident light.

  Among the above three states, the planar phase and the focal conic phase can exist bistable without an electric field. Therefore, the phase state of the cholesteric liquid crystal is not uniquely determined with respect to the electric field strength applied to the liquid crystal layer. When the planar phase is in the initial state, the planar phase and the focal conic phase are increased as the electric field strength increases. When the focal conic phase is in the initial state, the focal conic phase and the homeotropic phase change in this order as the electric field strength increases.

  On the other hand, when the electric field strength applied to the liquid crystal layer is suddenly reduced to zero, the planar phase and the focal conic phase are maintained as they are, and the homeotropic phase is changed to the planar phase.

  Therefore, the cholesteric liquid crystal layer immediately after the pulse signal is applied exhibits a switching behavior as shown in FIG. 5, and when the applied pulse signal voltage is equal to or higher than Vfh, the selective reflection is changed from the homeotropic phase to the planar phase. When it is between Vpf and Vfh, it becomes a transmission state due to the focal conic phase, and when it is equal to or lower than Vpf, the state before the pulse signal application is continued, that is, a selective reflection state due to the planar phase or a transmission state due to the focal conic phase. Become.

  In the figure, the vertical axis represents the normalized reflectance, and the reflectance is normalized with the maximum reflectance being 100 and the minimum reflectance being 0. In addition, since there are transition regions between the states of the planar phase, the focal conic phase, and the homeotropic phase, the case where the normalized reflectance is 50 or more is the selective reflection state, and the case where the normalized reflectance is less than 50. The transmission state is defined, and the phase change threshold voltage between the planar phase and the focal conic phase is Vpf, and the phase change threshold voltage between the focal conic phase and the homeotropic phase is Vfh.

  In particular, a PNLC (Polymer Network Liquid Crystal) structure including a network-like resin in a continuous phase of cholesteric liquid crystal, or a PDLC (Polymer Dispersed Liquid Crystal) structure in which cholesteric liquid crystal is dispersed in a droplet shape in a polymer skeleton ( In the liquid crystal layer (including those encapsulated), the bistability of the planar phase and the focal conic phase in the absence of an electric field is improved due to interference at the interface between the cholesteric liquid crystal and the polymer (anchoring effect). It is possible to maintain the state immediately after the pulse signal is applied.

  In the display medium 1 using such a cholesteric liquid crystal 12, (A) a selective reflection state by the planar phase and (B) a transmission state by the focal conic phase are switched using the bistable phenomenon of the cholesteric liquid crystal. Thus, black and white monochrome display having a memory property without an electric field or a color display having a memory property without an electric field is performed.

  Depending on the magnitude of the externally applied voltage, the cholesteric liquid crystal 12 has a P state, a focal conic phase state (F state), a planar phase state (P state) or a homeotropic phase state (H state). When the F state is changed to the H state and the F state is the initial state, the state changes to the F state and the H state. In the P state and the F state, the final state is maintained even after the applied voltage is removed. Then, the phase changes to the P state. Therefore, regardless of exposure / non-exposure, the P state or the F state is selected as the final phase state depending on the magnitude of the applied voltage. As shown in FIG. 5, the light is reflected in the P state and the light is transmitted in the F state.

  Next, the image display device 20 shown in FIG. 2 will be described. The image display device 20 includes a display medium 1 and an optical writing device (optical recording device) 2.

  The optical writing device 2 is a device that writes (records) an image on the display medium 1, and a light irradiation unit (exposure device) 32 that irradiates the display medium 1 with writing light (address light), and a light irradiation unit 32. Drive unit 24 for moving the light irradiation unit 32 in the direction of arrow A so that the display medium 1 and the display medium 1 move relative to each other, and high-voltage pulse generators 26A and 26B for generating a bias voltage (high-voltage pulse) applied to the display medium 1 The voltage application unit 26, the switching unit 28 for switching the divided electrodes to which the bias voltage generated by the high voltage pulse generation units 26A and 26B is applied, the platen cover 16 as the light amount adjusting means in this embodiment, and the drive unit 24, switching The control part 30 which controls the part 28 and the cover 16 (more specifically, motor 18a, 18b with which the platen cover 16 is provided) is comprised.

  The light irradiation unit 32 outputs a reset light source 32A that emits reset light for resetting (initializing) the display medium 1, and an address light pattern (light image pattern) based on an input signal corresponding to an image from the control unit 30. And an image light source 32B that irradiates the display medium 1 (specifically, on the photoconductor layer 10). The reset light source 32A may be provided separately from the image light source 32B. In this case, reset light may be irradiated from the reset light source 32A all at once. The reset light source 32A and the image light source 32B may be a fixed two-dimensional light source or a plurality of point light sources.

  Note that resetting (initializing) the display medium 1 specifically means, for example, initializing the orientation of the liquid crystal of the cholesteric liquid crystal 12, for example, setting it to the F state or the P state.

  The address light (write light) irradiated by the image light source 32B is preferably light having a peak intensity in the absorption wavelength region of the photoconductor layer 10 and a bandwidth as narrow as possible.

  Examples of the image light source 32B include a light source such as a cold cathode tube, a xenon lamp, a halogen lamp, a light emitting diode (LED), an EL, and a laser arranged in a one-dimensional array, a combination with a polygon mirror, For example, a device capable of forming an arbitrary two-dimensional light emission pattern by a scanning operation is used. The image light source 32B writes an image on the display layer 7 by irradiating write light from the photoconductor layer 10 side.

  As the reset light source 32A, for example, a light source capable of irradiating the display medium 1 with uniform light such as an array of light sources as described above or a combination with a light guide plate is used. In addition, the light irradiation part 32 is not restricted to what was mentioned above. For example, a known irradiation unit that irradiates writing light may be used for the light irradiation unit 32.

  The high voltage pulse generator 26A is a circuit that generates a reset voltage, and the high voltage pulse generator 26B is a circuit that generates an image writing voltage. For the high-voltage pulse generators 26A and 26B, for example, high voltage amplifiers or the like that generate voltages of opposite polarities are used.

  In the present embodiment, as shown in FIG. 2, the transparent electrode 6 of the display medium 1 is grounded, the high voltage pulse generator 26A outputs a DC voltage having a positive polarity, and the high voltage pulse generator 26B is negative. A DC voltage having polarity is applied. That is, the reset voltage applied to the grounded transparent electrode 6 with respect to the divided electrodes 5A, 5B, and 5C is a DC voltage having a negative polarity, and is grounded with respect to the divided electrodes 5A, 5B, and 5C. The image writing voltage applied to the transparent electrode 6 is a DC voltage having a positive polarity.

  Here, the voltage value of the reset voltage is reset (initialized) when the reset voltage is applied between the transparent electrodes in a state where the reset light is irradiated onto the display medium 1 by the reset light source 32A. The voltage value that can be set, specifically, for example, a voltage value that can initialize the alignment of the liquid crystal of the cholesteric liquid crystal 12 is set. For example, in the case of initializing to the F state, as shown in FIG. 5, the voltage value (voltage division) applied to the display layer 7 is a voltage value that falls within a voltage range greater than Vpf and less than Vfh. If it is initialized to the P state, the voltage value (voltage division) applied to the display layer 7 is such a voltage value that is equal to or higher than Vfh.

  The voltage value of the image writing voltage is determined when the image writing voltage is applied between the transparent electrodes in a state where image light corresponding to the image is applied to the display medium 1 by at least the image light source 32B. 1 is set to a voltage value at which an image can be recorded. For example, when an image is written by changing the alignment of the liquid crystal of the cholesteric liquid crystal 12 from the P state to the F state, the voltage (partial pressure) applied to the display layer 7 at the site irradiated with the image light is larger than Vpf. If the voltage value is within a voltage range smaller than Vfh and the state is changed from the P state to the F state, the voltage (partial pressure) applied to the display layer 7 at the site irradiated with the image light is Vfh. The voltage value is the above voltage.

  The reset voltage may be a DC voltage having a positive polarity, and the image writing voltage may be a DC voltage having a negative polarity.

  Moreover, the voltage application part 26 is not restricted to what was mentioned above. For example, a known voltage applying unit that applies an image writing voltage may be used for the voltage applying unit 26.

  The switching unit 28 selects a divided electrode to which a reset voltage is applied and a divided electrode to which an image writing voltage is applied in accordance with an instruction from the control unit 30, and for the divided electrode selected as an electrode to which the reset voltage is applied. In addition, the reset voltage output from the high voltage pulse generator 26A is applied, and the image writing voltage output from the high voltage pulse generator 26B is applied to the divided electrodes selected as the electrodes to which the image write voltage is applied. Apply.

  The drive unit 24 moves the light irradiation unit 32 in the arrow A direction (sub-scanning direction) in FIG. 2 in accordance with an instruction from the control unit 30. The drive unit 24 includes a pulse motor, for example, and moves the light irradiation unit 32 in the direction of arrow A in the figure by driving the pulse motor. As a result, the reset light source 32A and the image light source 32B integrally move in the direction of arrow A in the figure. By adopting a configuration in which the light irradiation unit 32 is moved, a configuration for detecting the transparent electrode of the display medium 1 is unnecessary, and the connection configuration with the voltage application unit 26 is simplified as compared with the case where the display medium 1 is moved.

  The control unit 30 includes a CPU (Central Processing Unit) (not shown), a ROM (Read Only Memory) (not shown), a RAM (Random Access Memory) (not shown), and an I / O (input / output) port (not shown). The CPU, ROM, RAM, and I / O port are connected to each other via a bus. The ROM stores a basic program such as an OS and a program for executing a light amount adjusting means control process described in detail below. The CPU reads the program from the ROM and executes it. Various data are temporarily stored in the RAM. The drive unit 24, the switching unit 28, the motors 18a and 18b, the reset light source 32A, and the image light source 32B are connected to the I / O port.

  As illustrated in FIG. 2, the platen cover 16 is provided so as to be movable in the C direction and the D direction. For example, when the display medium 1 is to be arranged in the optical writing device 2, the platen cover 16 can be moved in the C direction to the position m shown in FIG. Further, when performing an image writing operation with the optical writing device 2, it is necessary to close the platen cover 16. Therefore, the platen cover 16 may be moved in the D direction to the position n shown in FIG. 2. it can.

  The platen cover 16 includes motors 18 a and 18 b and a film 17. The casing of the platen cover 16 is made of a transparent member. As shown in FIG. 2, the motors 18 a and 18 b are provided apart by a distance L. Each of the motors 18a and 18b can be driven to rotate under the control of the control unit 30 to wind up the film 17 described in detail below. As described in detail below, the display layer 7 can be covered with either the transparent film 17a or the light-shielding film 17b (see FIG. 6), and the display layer 7 is covered with the transparent film 17a. The amount of reflected light reflected and transmitted from the display layer 7 is such that the image on the display layer 7 can be visually recognized by the reflected light reflected from the display layer 7, and the display layer 7 is covered by the light shielding film 17b. In this case, the amount of incident light incident on the display layer 7 is not more than a predetermined amount Q. The light quantity Q is the quantity of incident light incident on the display layer 7 when the intensity of the light transmitted through the display layer 7 and incident on the light shielding layer 9 is less than the value K described above. It is a value obtained in advance by experiments.

  As shown in FIG. 6A, the film 17 is composed of a predetermined number, for example, two films (transparent film 17a and light-shielding film 17b) having different transmittances. In the present embodiment, the transparent film 17a is a transparent film, and is inserted between the outside and the display layer 7 (that is, arranged so as to cover the display layer 7). The image written in the display layer 7 can be visually recognized by the light that is transmitted and incident on the display layer 7 and is reflected and transmitted from the display layer 7. The light shielding film 17b is a film having a light shielding function, and when inserted between the outside and the display layer 7, it shields light from the outside.

  The length of each of the films 17a and 17b is L. This length L is long enough to cover the display layer 7. As shown in FIG. 6B, the position of the film 17b at which incident light incident on the display layer 7 can be blocked by the film 17b as the light blocking member is referred to as a light blocking position in this embodiment. Called. As shown in FIG. 6C, the position of the film 17b when the reflected light reflected from the display layer 7 can be transmitted by the film 17a as a transparent member is transmitted in this embodiment. This is called a position. That is, the film 17 in the platen cover 16 as the light amount adjusting means of the present embodiment is provided so as to adjust the amount of reflected light reflected from the display layer 7 and incident light incident on the display layer 7. . More specifically, the film 17 is movable to the display layer 7 side so as to be movable to a light shielding position for shielding incident light displayed on the display layer 7 and a transmission position for transmitting reflected light reflected from the display layer 7. The film 17b is provided.

  For example, the control unit 30 instructs the drive unit 24 so that the light irradiation unit 32 moves in the direction of arrow A in FIG. 2 at a predetermined speed, and reset light is emitted at a later-described timing based on the input image data. Each light source is controlled so that the display medium 1 is irradiated by the reset light source 32A and image light based on the input image data is irradiated to the display medium 1 by the image light source 32B. The switching unit 28 is controlled so that the reset voltage and the image writing voltage are applied to the divided electrodes 5A to 5C.

  Next, an image writing operation on the display medium 1 will be described. In the following, the electrode width W of the divided electrodes 5A, 5B, and 5C is the same, and a case where W <Ta × Va is described. The high voltage pulse generator 26A outputs the reset voltage V1-A, and the high voltage pulse generator 26B outputs the image writing voltage V2. It is assumed that the time when the integrated reflectance starts to rapidly decrease is Ta (s), and the moving speed (sub-scanning speed) of the light irradiation unit 32 is Va (mm / s).

  FIG. 7 shows the timing of irradiating the display medium 1 with reset light and image light, and the timing of applying a voltage to the display medium 1.

  First, the control unit 30 instructs the drive unit 24 to start moving the light irradiation unit 32 in the direction of arrow A in FIG. The light irradiation unit 32 is disposed at a predetermined standby position before the image writing operation is started. This standby position is located further upstream than the end of the display medium 1 on the upstream side in the arrow A direction.

  When the control unit 30 instructs the drive unit 24 to start moving the light irradiation unit 32, the drive unit 24 starts moving the light irradiation unit 32. Thereby, the light irradiation part 32 starts a movement in the arrow A direction in FIG.

  Then, the control unit 30 divides the reset voltage V1-A at time T1 when the reset light source 32A reaches the region of the divided electrode 5A and can irradiate at least a part of the divided electrode 5A with the reset light. The switching unit 28 is instructed to be applied to the electrode 5A for a predetermined time Tx, and the reset light source 32A is instructed so that the reset light L1 is applied to the region of the divided electrode 5A for the predetermined time Tx. The predetermined time Tx is set to a time during which the reset light is irradiated to the entire area of the divided electrode 5A.

  Thereby, the switching unit 28 selects the divided electrode 5A, applies the reset voltage V1-A output from the high voltage pulse generating unit 26A to the divided electrode 5A for a predetermined time Tx, and the reset light source 32A receives the reset light L1. Is irradiated to the display medium 1 for a predetermined time Tx, the display medium 1 is reset. For example, it is reset to the F state.

  When the reset is completed, the control unit 30 ends the upstream side of the divided electrode 5A in the direction of arrow A with respect to the image light source 32B at time T2 before T3 when the image light irradiation period of the image light source 32B starts. At a time before reaching the part, the switching part 28 is instructed so that the image writing voltage V2 is applied to the divided electrode 5A for a predetermined time Ty. Thus, the switching unit 28 applies the image writing voltage V2 output from the high voltage pulse generator 26B to the divided electrode 5A for a predetermined time Ty. Note that the application start of the image writing voltage V2 may be the time T3 when the image light irradiation period of the image light source 32B starts, but by starting the application of the voltage at a time T2 before T3, It is possible to prevent occurrence of a region where no image is recorded, and the image is reliably written.

  Next, the control unit 30 sets the period from the time T3 when the image light irradiation period by the image light source 32B starts to the time T4 when the image light irradiation period ends, that is, the image light source 32B is connected to the divided electrode 5A. The region of the divided electrode 5A in the input image data during the period from the time when it reaches the end on the upstream side in the arrow A direction until the image light source 32B reaches the end on the downstream side in the arrow A direction of the divided electrode 5A. The image data of the image to be written in is output to the image light source 32B. As a result, the image light is irradiated and the image is written during the image light irradiation period from T3 to T4. For example, the region irradiated with image light changes from the F state to the H state. Note that the image light irradiation period is a period during which image light can be irradiated, and it goes without saying that image light is not irradiated in a region where an image is not written.

  Here, as shown in FIG. 7, since the application of the image writing voltage V2 is continued for a predetermined time Tz after the irradiation period of the image light (period T3 to T4) is completed, Reduction is suppressed. The predetermined time Tz is set to a time during which a decrease in the integrated reflectance can be suppressed (for example, 100 ms or more). When the application of the image writing voltage V2 is finished, the H state region is changed to the P state, and an image is displayed and maintained in the region of the divided electrode 5A.

  In addition, the control part 30 controls the drive part 24, the light irradiation part 32, and the switch part 28 sequentially similarly to the above also about the divided electrodes 5B and 5C. As a result, the image is written on the entire display medium 1.

  Next, a processing routine of the light amount adjusting unit control process executed by the CPU of the control unit 30 will be described with reference to FIG. In the present embodiment, the light amount adjusting unit control process is executed at predetermined time intervals after a switch (not shown) of the optical writing device 2 is turned on and the power is turned on.

  First, in step 100, image data is input and an image is written by controlling the drive unit 24, the high voltage pulse generation unit 26, the switching unit 28, and the light irradiation unit 32 (image writing status). It is determined whether or not there is. In step 100, the determination process is repeated until it is determined that the current state is the image writing state.

  If it is determined in step 100 that the image is being written, the process proceeds to the next step 102. In the next step 102, the rotational drive of the motors 18a and 18b is controlled so that the position of the film 17b is moved to the above-described light shielding position. Thereby, the position of the film 17b is moved to the light shielding position.

  In the next step 104, it is determined whether or not the situation (image writing situation) in which image writing is performed by controlling the driving unit 24, the high-voltage pulse generating unit 26, the switching unit 28, and the light irradiation unit 32 is completed. To do. In step 104, the determination process is repeatedly performed until it is determined that the image writing condition (image writing condition) has been completed. Note that a case where the image is not written (situation) is a case where the user visually recognizes the image written on the display layer 7.

  If it is determined in step 104 that the image writing state (image writing state) has been completed, the process proceeds to the next step 106. In step 106, the rotational drive of the motors 18a and 18b is controlled so that the position of the film 17b is moved to the transmission position described above. Thereby, the position of the film 17b is moved to the transmission position. Then, the light amount adjusting means control process is terminated.

  As described above, the optical writing device 2 according to the present embodiment includes the photoconductor layer 10 whose magnitude of electrical resistance changes according to the amount of irradiated writing light, and the photoconductor layer 10. A light having a wavelength corresponding to the magnitude of the voltage applied through the photoconductor layer 10 and the light shielding layer 9 is disposed with a light shielding layer 9 that shields light having a predetermined intensity K therebetween. The display layer 7 is irradiated with writing light from the photoconductor layer 10 side onto the photoconductor layer 10 of the photo-writing type image display medium 1 having the display layer 7 that displays an image by reflecting and transmitting the image. And a platen cover 16 as a light amount adjusting means provided to adjust the amount of reflected light reflected from the display layer 7 and incident light incident on the display layer 7. And when writing the image The amount of incident light incident on the display layer 7 is less than or equal to a predetermined light amount Q, and when the written image is viewed, the image of the display layer 7 can be viewed by the reflected light reflected from the display layer 7 A control unit 30 is provided as a control means for controlling the platen cover 16 as a light quantity adjusting means so that a sufficient light quantity is obtained.

  Further, the control unit 30 of the present embodiment moves the film 17b as the light shielding member to the light shielding position when writing the image, and moves the film 17b to the transmission position when viewing the written image. The film 17b is controlled.

  In the present embodiment, the case where the image is not written (situation) is the case where the user visually recognizes the image written on the display layer 7, but an instruction receiving unit (not shown) (for example, mouse, keyboard) The case where the control unit 30 receives an instruction to display an image from the user using a touch panel or the like may be a case where the user visually recognizes the image written on the display layer 7. When the control unit 30 receives such an instruction, the control unit 30 controls the film 17b so as to move the film 17b to the transmission position.

  In this embodiment, the case where cholesteric liquid crystal is used as the display layer has been described. However, the present invention is not limited to this, and ferroelectric liquid crystal may be used.

  Moreover, although this embodiment demonstrated the case where the light irradiation part 32 and the display medium 1 were moved relatively by moving the light irradiation part 32 in the state where the display medium 1 was fixed, the light irradiation part 32 is fixed. In this state, the display medium 1 may be moved, or both may be moved relative to each other.

  In the present embodiment, the case where the number of divided electrodes is three has been described. However, the present invention is not limited to this, and the present invention can also be applied to the case where the number of divided electrodes is two or four or more.

  Furthermore, in this embodiment, the case where the application of the reset voltage and the irradiation of the reset light, the application of the image writing voltage, and the irradiation of the image light are sequentially performed in the predetermined direction for each divided electrode has been described. Need not be sequentially performed for adjacent divided electrodes. For example, when it is not necessary to write an image in the entire area of a certain divided electrode, it is not necessary to perform the above operation for the divided electrode, and the above operation may be performed from the next divided electrode. Further, the above operation is performed for the entire display medium 1 every n divided electrodes n (n = 1, 2, 3,...), And the same operation is repeated for the divided electrodes for which the above operation has not been performed. In other words, the image may be written by scanning the display medium 1 n + 1 times.

  Further, in the present embodiment, the platen cover 16 can be moved to a light shielding position where the incident light displayed on the display layer 7 is shielded and a transmission position where the reflected light reflected from the display layer 7 is transmitted. Although the example which comprised the film 17b provided in 7 side was demonstrated, this Embodiment is not restricted to this. For example, the transmittance of the display layer 7 is changed by the first transmittance T 1 that blocks the incident light incident on the display layer 7 and the light reflected from the display layer 7 and transmitted through the platen cover 16. You may comprise including the electrochromic material which can be changed to the transmittance | permeability T2 from which an image can be visually recognized, and the reflectance control by voltage application, light control glass (light control member), etc. In such a configuration, the control unit 30 has the first transmittance T1 when the image is written, and the second transmittance when viewing the written image. The voltage applied to the electrochromic material is controlled and the light control glass is controlled so that the rate T2 is obtained.

It is sectional drawing of a display medium. It is a schematic block diagram of an image display apparatus (optical writing apparatus). It is a circuit diagram which shows the equivalent circuit of a display medium. It is a schematic explanatory view showing the relationship between the molecular orientation and optical characteristics of cholesteric liquid crystal, wherein (A) is in the planar phase, (B) is in the focal conic phase, and (C) is in the homeotropic phase. It is a graph for demonstrating the switching behavior of a cholesteric liquid crystal. It is a schematic diagram of the film of this Embodiment. It is a timing chart of voltage application and light irradiation. It is a figure which shows the flowchart of the light quantity adjustment means control process which the control part of this Embodiment performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display medium 2 Optical recording device 3, 4 Transparent substrate 5 Transparent electrode 5A, 5B, 5C Split electrode 6 Transparent electrode 7 Display layer 8 Laminate layer 9 Light-shielding layer 10 Photoconductor layer 12 Cholesteric liquid crystal 16 Platen cover 17 Film 17a Transparent film 17b Shading films 18a and 18b Motor 20 Image display device 24 Drive unit 26 Voltage application unit 26A High voltage pulse generation unit 26B High voltage pulse generation unit 28 Switching unit 30 Control unit 32 Light irradiation unit 32A Reset light source 32B Image light source

Claims (5)

A photoconductor layer whose magnitude of electrical resistance changes in accordance with the amount of irradiated writing light, and a light-shielding layer that shields light of less than a predetermined intensity between the photoconductor layer. And a writable image display comprising a display layer for displaying an image by reflecting and transmitting light having a wavelength according to the magnitude of a voltage applied through the photoconductor layer and the light shielding layer. Writing means for writing an image on the display layer by irradiating the photoconductor layer of the medium with the writing light from the photoconductor layer side;
A light amount adjusting means provided to adjust the light amount of the reflected light reflected from the display layer and the incident light incident on the display layer;
When writing an image, the amount of incident light incident on the display layer is equal to or less than a predetermined amount, and when the written image is viewed, the reflected light reflected from the display layer Control means for controlling the light quantity adjusting means so that the image has a visible light quantity;
An optical writing device. A light shielding member provided on the display layer side so that the light amount adjusting means can be moved to a light shielding position for shielding incident light incident on the display layer and a transmission position for transmitting reflected light reflected from the display layer. Consisting of
The control means controls the light shielding member to move the light shielding member to the light shielding position when writing an image, and to move the light shielding member to the transmission position when viewing the written image. The optical writing device according to claim 1. The light amount adjusting means can change the transmittance to a first transmittance that blocks incident light incident on the display layer and a second transmittance that transmits reflected light reflected from the display layer. It consists of a light control member,
When the image is written, the control means has a first transmittance, and when the written image is viewed, the light control member has a second transmittance so that the transmittance is the second transmittance. The optical writing apparatus according to claim 1, wherein the light control member is controlled.   The said control means controls the said writing means so that the said write light may be irradiated to the said photoconductor layer based on image information, when writing an image. Optical writing device. Computer
A photoconductor layer whose magnitude of electrical resistance changes in accordance with the amount of irradiated writing light, and a light-shielding layer that shields light of less than a predetermined intensity between the photoconductor layer. And a writable image display comprising a display layer for displaying an image by reflecting and transmitting light having a wavelength according to the magnitude of a voltage applied through the photoconductor layer and the light shielding layer. By irradiating the photoconductor layer of the medium with the writing light from the photoconductor layer side, incident light incident on the display layer when writing an image by a writing means for writing an image on the display layer From the display layer so that the image of the display layer becomes a visible light amount by the reflected light reflected from the display layer when the written image is visually recognized. Reflected Program for functioning as a control means for controlling the light amount adjusting means arranged to adjust the amount of light reflected and light incident on the display layer.

Images