JP4012729B2 - Multicolor image display method and multicolor image display apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multicolor image display method and a multicolor image display device, and more particularly to a multicolor image display method and a multicolor image display device capable of repeatedly writing and erasing a color image by light irradiation.
[0002]
[Prior art]
Although there have been some researches on rewritable image display media using photochromic compounds that cause reversible color changes by light irradiation, practical multicolor image display methods that can reversibly display full-color images many times. There is still no example that proposed.
As a means for forming a color image using a photochromic compound, for example, in JP-A-5-271649, yellow-orange is irradiated with ultraviolet light of 254 nm, red is irradiated with ultraviolet light of 313 nm, and blue-violet is irradiated with ultraviolet light of 365 nm. Techniques have been proposed in which three types of photochromic diarylethene compounds that develop color are mixed and irradiated with ultraviolet light corresponding to each.
In order to form a full-color image, at least three kinds of photochromic compounds that develop three primary colors (blue, green, red, or yellow, magenta, and cyan) must be controlled by light. There is a problem.
[0003]
One is a problem regarding the material characteristics of the photochromic compound, and it is necessary to collect compounds that absorb three different kinds of ultraviolet rays and develop three primary colors. Even in the above technique, blue, yellow, etc. are not colored, so full color cannot be displayed. In addition, in order to put it into practical use, not only the coloring properties but also the repeated durability, heat / humidity stability, etc. must be considered, and it is very difficult to develop a material that satisfies all of these.
The second relates to the irradiation light source. In the embodiments of the above technique, a high-pressure mercury lamp is used as an irradiation light source. However, in order to form an image pattern, it is necessary to write with a small and highly directional light source such as a semiconductor laser (LD) or a light emitting diode (LED). It is. In this case, it is difficult to develop LDs and LEDs in the ultraviolet region, and at this stage, 372 nm LEDs are partly commercialized, and 342 nm LEDs are in the development stage to some extent. Accordingly, it is very difficult to develop three types of ultraviolet light, particularly 300 nm short wavelength LDs and LEDs, and an image display method based on the use of these light sources is not practical.
[0004]
In Japanese Patent Application Laid-Open No. 7-199401, a mixture of three types of photochromic fulgide compounds showing yellow, magenta, and cyan in a colored state is developed by coloring all types of photochromic compounds with ultraviolet light of 366 nm, and then color positive. A method of selectively erasing with white light passing through a film has been proposed. Although this technology has the advantage of only one type of ultraviolet light, it requires three types of photochromic compounds with almost the same sensitivity in the vicinity of 366 nm, so it is not easy to control the color tone and material development is difficult. difficult. In addition, the compounds shown in the examples have a maximum of 30 durability cycles, which is not practical.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the situation and problems of the prior art described above, and the problem is that the existing photochromic compound and a highly practical light source are used, and the storage stability of written image information and writing It is an object of the present invention to provide a rewritable multicolor image display method and multicolor image display apparatus that are excellent in repeated erasure durability.
[0006]
[Problems to be solved by the invention]
In order to solve the above problems, the present invention described in claim 1 is directed to an image display medium in which a photosensitive layer containing two or more types of photochromic compounds having different maximum absorption wavelengths in a colored state is formed on a support substrate. ,wavelength of After irradiating two different kinds of ultraviolet light to develop all kinds of photochromic compounds contained in the photosensitive layer, the visible light in the wavelength region corresponding to the maximum absorption wavelength of each of the colored photochromic compounds is determined in advance. The multicolor image display method is characterized in that an image is formed by irradiating the selected region and selectively decoloring each photochromic compound.
[0007]
The present invention described in claim 2 irradiates at least one of the two types of ultraviolet light onto the entire image display portion of the image display medium. And The present invention according to claim 3 includes two types of ultraviolet light. The 2. The multicolor image display method according to claim 1, wherein irradiation is performed only on a predetermined area. According to the fourth aspect of the present invention, the photosensitive layer has a photochromic compound having a maximum absorption wavelength in a colored state of 400 nm or more and less than 500 nm, a photochromic compound in a range of 500 nm or more and less than 600 nm, and 600 nm or more and less than 700 nm. 4. The multicolor image display method according to claim 1, wherein all the photochromic compounds in the range are contained. The present invention described in claim 5 provides the multicolor image display method according to any one of claims 1 to 4, wherein the protective layer is formed on the surface of the photosensitive layer.
[0008]
According to a sixth aspect of the present invention, there is provided the multicolor image display method according to any one of the first to fifth aspects, wherein the irradiation intensity or irradiation time of ultraviolet light is controlled.
A seventh aspect of the present invention provides the multicolor image display method according to any one of the first to sixth aspects, wherein the irradiation intensity or irradiation time of visible light is controlled.
The present invention described in claim 8 includes the step of irradiating the entire surface of the image display portion of the image display medium with white light, wherein the multicolor image display method according to any one of claims 1 to 7 is provided. .
[0009]
The present invention described in claim 9 is the multicolor image display method according to any one of claims 1 to 8, wherein the visible light source includes a white light source and an optical filter.
A tenth aspect of the present invention is the multicolor image display method according to any one of the first to eighth aspects, wherein the visible light source is a plurality of types of light emitting elements having different emission wavelengths. .
The present invention described in claim 11 is provided with a linear ultraviolet light source and a visible light source, and the multicolor according to any one of claims 1 to 10 while relatively moving the image display medium and the light source. A multicolor image display device is characterized by forming an image using an image forming method.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In order to form a full-color image, at least three types of photochromic compounds corresponding to the three primary colors must be controlled by light. In the present invention, the ultraviolet light source used for color development corresponds to the absorption wavelength of at least one type of photochromic compound. The ultraviolet light (I) and the ultraviolet light (II) corresponding to the absorption wavelength of the remaining photochromic compound are shared.
A configuration example of an image display medium used in the present invention is shown in FIG.
In FIG. 1, a photochromic compound (X) that develops cyan by absorbing ultraviolet light (I), and a photochromic compound (Y) that develops magenta and yellow by absorbing ultraviolet light (II), respectively ( Z) are layered to form a photosensitive layer. The image display medium includes a photosensitive layer and a support substrate that supports the photosensitive layer.
As the multicolor image display method for displaying a full color image on the image display medium, the following three methods are mainly described in the present invention.
[0011]
First, as shown in FIG. 2, all types of photochromic compounds were colored by irradiating the entire surface of the image display portion of the image display medium using a lamp light source with both ultraviolet light (I) and (II). After that, it is a method of selectively erasing with three types of visible laser diodes (LD) or light emitting diodes (LEDs) corresponding to the respective colors. When all kinds of photochromic compounds are colored, the entire surface is black.
Here, in order to decolorize cyan, visible light with a wavelength of 600 nm or more and less than 700 nm, preferably visible light in the vicinity of 650 nm may be irradiated. Similarly, in order to erase magenta, visible light having a wavelength of 500 nm or more and less than 600 nm may be irradiated, preferably in the vicinity of 550 nm, and in order to erase yellow, visible light having a wavelength of 400 nm or more and less than 500 nm may be used. Light, preferably visible light around 450 nm may be irradiated.
As a method for performing selective erasing using LD and LED, for example, a method of performing on / off control while scanning laser light with a rotating mirror or the like, or an array of LEDs arranged in an array according to an image signal A method of performing on / off control can be considered, but any method may be used.
[0012]
As a light source for irradiating ultraviolet light, a mercury lamp or a xenon lamp may be used in combination with an optical filter to extract ultraviolet light in a desired wavelength range, or light emission that emits light in a specific wavelength range such as an LED or LD. An element may be used. For example, in the case of manufacturing a display device in which a light source system for writing / erasing is made as compact as possible, a light emitting element such as an LED is preferable, and light emission that can control on / off of irradiation for each minute region is preferable. You may comprise the light source array formed by arranging the surface continuously.
[0013]
As a light source for irradiating visible light, lamps having a configuration in which an optical filter is combined with a white light source may be used, or a light emitting element that emits light in a specific wavelength region such as an LED or an LD may be used. For example, in the case of manufacturing a display device in which a light source system for writing / erasing is made as compact as possible, a light emitting element such as an LED is preferable, and light emission that can control on / off of irradiation for each minute region is preferable. You may comprise the light source array formed by arranging the surface continuously. In particular, when irradiating only a desired region, the irradiation of each light emitting surface of the light source array is turned on / off while relatively moving the light source array and the image display medium having the photosensitive layer formed on the support substrate. This can also be achieved by controlling off.
As described above, according to the present invention, multicolor image display is possible only by light irradiation, so that the energy used is smaller than that of the thermal method, and high-resolution image formation is possible as compared with the electric field method. Furthermore, since a large number of photochromic compounds can be used, this is a multicolor image display method that is stable to heat and moisture and is durable repeatedly.
[0014]
Second, as shown in FIG. 3, by using ultraviolet LD and LED as ultraviolet light (I), cyan is selectively colored, and ultraviolet light (II) is irradiated onto the entire surface of the image display unit with a lamp light source. In this method, magenta and yellow are completely colored, and then the color is selectively erased by using two types of visible LDs and LEDs corresponding to magenta and yellow. As a light source of at least one of the two types of ultraviolet light, it is not necessary to irradiate a fine spot unit corresponding to the pixel size, so that the configuration of the light source element is facilitated and the cost is reduced. It is advantageous.
[0015]
Third, as shown in FIG. 4, both ultraviolet light (I) and (II) are irradiated with ultraviolet LD and LED to selectively develop cyan and magenta and yellow aggregate parts, and then, This is a method of selectively erasing the magenta and yellow coloring portions with two types of visible LDs and LEDs corresponding to the respective colors.
In particular, the second and third methods do not require the entire surface to be colored once, so they are useful from the standpoints of reducing energy consumption and writing time when displaying images with many white parts such as text documents. is there.
[0016]
In any of the above methods, the multicolor image display method of the present invention using two types of ultraviolet light sources having different wavelengths and visible light solves the problems of the prior art.
First, compared with a multicolor image display method using three kinds of ultraviolet light, the present invention has an advantage that only two kinds of ultraviolet light are required. Looking at the development trend of ultraviolet light sources, it is very difficult to develop three types of ultraviolet LD and LED at different wavelengths (at least the wavelengths must be several tens of nanometers apart from each other in order to avoid overlapping of absorption regions). Although it is conceivable, it is sufficiently possible to develop only two types of ultraviolet LD and LED. Since LDs and LEDs in the visible range are small in size and high in output, devices with two types of ultraviolet light wavelengths are highly practical.
[0017]
Next, compared to a method using one ultraviolet light and three types of visible light, there is an advantage that many photochromic compounds can be used. The extinction wavelength of existing photochromic compounds is in the range of less than 350 nm and mainly in the range of 350 nm to less than 400 nm, but in the case of one ultraviolet light (for example, 366 nm or 313 nm) Then, only one of these compounds can be used. However, in the present invention using two types of ultraviolet light, both can be used, so the range of selection of photochromic compounds is expanded. The practical application of photochromic compounds has many problems such as thermal stability and repeated durability. By selecting from a wide range of compounds, those having a molecular structure that can overcome these problems can be used.
Typical photochromic compounds include spiropyran, spirooxazine, fulgide, diarylethene and the like.
[0018]
The photosensitive layer used in the present invention includes a photochromic compound having a maximum absorption wavelength in a colored state of 400 nm or more and less than 500 nm, a photochromic compound having a maximum absorption wavelength in a colored state of 500 nm or more and less than 600 nm, and a color developing state. All the photochromic compounds having a maximum absorption wavelength in the range of 600 nm or more and less than 700 nm are contained.
The colors recognized in the colored state of each of the photochromic compounds correspond to approximately yellow, magenta, and cyan, respectively, and these constitute three primary colors. These photochromic compounds preferably have no overlapping of absorption bands in their respective visible regions.
[0019]
Examples of the diarylethene compound having a photochromic property having a maximum absorption wavelength in the range of 400 nm to less than 500 nm in a colored state include, for example, 1,2-bis (2-phenyl-4-trifluoromethylthiazole) -3,3,4, 4,5,5-hexafluorocyclopentene, dimethyl 2,3-di (2-methylbenzothienyl) maleate, 1,2-bis (5-ethoxy-2-methylthiazol) -3,3,4,4 , 5,5-hexafluorocyclopentene, and the like.
Examples of the diarylethene compound having a photochromic property in which the maximum absorption wavelength in a colored state is in the range of 500 nm to less than 600 nm include 1- (3- (2-methyl-6- (2- (4-methoxyphenyl) ethynyl) benzo Thienyl))-2- (3- (2,4-dimethyl-5- (2- (4-methoxyphenyl) ethynyl) thienyl))-3,3,4,4,5,5-hexafluorocyclopentene, 1 , 2-bis (5-methyl-2-phenylthiazol) -3,3,4,4,5,5-hexafluorocyclopentene, 1- (1,2-dimethyl-3-indolyl) -2- (2 -Methyl-3-benzothienyl) -3,3,4,4,5,5-hexafluorocyclopentene, and the like.
As a diarylethene compound having a photochromic property having a maximum absorption wavelength in a colored state in the range of 600 nm or more and less than 700 nm, for example, 1- (5-methoxy-1,2-dimethyl-3-indolyl) -2- (5-cyano -2,4-dimethyl-3-thienyl) -3,3,4,4,5,5-hexafluorocyclopentene, 1- (5-methoxy-1,2-dimethyl-3-indolyl) -2- (6 -Carboxyl-2-methyl-3-benzothienyl) -3,3,4,4,5,5-hexafluorocyclopentene, 1- (6-cyano-2-methyl-3-benzothienyl) -2- (5 -Methoxy-1,2-dimethyl-3-indolyl) -3,3,4,4,5,5-hexafluorocyclopentene, and the like.
[0020]
The photosensitive layer used in the present invention may be only a photochromic compound, but the maximum absorption wavelength in a colored state is greatly different. Therefore, these photochromic compounds recognized almost as yellow, magenta, and cyan may be uniformly mixed at a predetermined mixing ratio to form a single photosensitive layer together with the binder material. A plurality of photosensitive layers may be formed by laminating photosensitive layers made of a binder material.
Further, it may be dispersed in a resin such as acrylic resin, vinyl chloride resin, polyester resin, polyamide resin, polyolefin resin, or urethane resin.
Moreover, although the laminated structure is shown in the example of FIG. 1, each photochromic compound may be mixed. Moreover, you may enclose a photochromic compound in a microcapsule.
The photosensitive layer is preferably formed on a white support substrate. The support substrate is preferably a thin film such as paper or film, but is not limited thereto.
[0021]
As a method for forming the photosensitive layer, an evaporation method may be mentioned in addition to the coating method. However, the coating method is simple, and both the photochromic compound and the binder material are dissolved in a solvent, and a method such as a printing method or a spin coating method is used. The film may be applied and dried to form a film. The photosensitive layer may be either a single layer or a plurality of layers, but when a plurality of layers are formed, it is preferable to form a separation layer between the layers so that adjacent layers do not mix. The separation layer can be formed by applying a film-forming solution using a solvent that does not dissolve the binder material and the photochromic compound in the photosensitive layer.
[0022]
A protective layer can be formed on the surface of the photosensitive layer used in the present invention. The cause of the deterioration of the photochromic compound is oxygen bonding during the photochemical reaction. If the atmosphere is blocked by the protective layer, repeated durability is improved.
As a material for the protective layer, a transparent resin such as polyvinyl alcohol, polycarbonate, and acrylic resin is desirable. Examples of the film forming method include a vacuum deposition method, a coating method, a spin coating method, a dipping method, and a casting method.
[0023]
In order to display a full-color image, an intermediate color must be developed. The color change of the photochromic compound is determined by the number of photoreacted molecules, and the number of photoreactive molecules corresponds to the number of photons of the irradiated light, so the color density can be easily adjusted by changing the intensity of the irradiated light or the irradiation time. .
The color density in the colored state may be changed by changing the intensity of the ultraviolet light or the irradiation time, or the color density may be changed by adjusting the degree of color development by changing the intensity of the visible light or the irradiation time. . Of course, you may combine both.
[0024]
An image created by the multicolor image display method of the present invention can be easily rewritten by irradiating ultraviolet light and visible light again, but if it is necessary to return to blank paper once, irradiate the entire surface with white light. Is simple. By irradiating all wavelengths in the visible region at once with white light, all the photochromic compounds that are in a colored state become decolored and become blank.
[0025]
In the display method of the present invention, visible light in a plurality of wavelength ranges is used. As a light source, a combination of a white light source and an optical filter for extracting each wavelength, or a plurality of light emitting elements having a specific emission wavelength range may be used. It is possible and either.
When a white light source and an optical filter for extracting each wavelength are used, there is an advantage that the wavelength can be easily adjusted depending on the formation conditions of the optical filter. When a plurality of types of light emitting elements having a specific light emission wavelength region are used, there are advantages in that light use efficiency is high and energy consumption can be reduced.
[0026]
When a multicolor image display device is manufactured using the multicolor image display method of the present invention, various configurations can be considered depending on the type and number of light sources, and may be appropriately selected depending on the application. However, in consideration of high resolution, high-speed writing, downsizing, low cost, etc., it is considered that a method in which each light source is installed in a line and writing is performed while relatively moving the image display medium and the light source is considered.
5 and 6 show a configuration example of the multicolor image display apparatus. 5 is a side view, and FIG. 6 is a plan view.
In this example, the image display medium (1) is transported by a plurality of transport rollers (2). After the image display portion of the image display medium (1) is made into a blank state with white light (3), the cyan portion is written in accordance with the image pattern with the ultraviolet LED array (4) of ultraviolet light (I). Next, the entire surface of magenta and yellow is colored by the ultraviolet lamp (5) of ultraviolet light (II). Thereafter, magenta and yellow are erased in accordance with the image pattern by the LED array (6) that is visible light of 550 nm and the LED array (7) that is visible light of 450 nm, and a full-color image is formed.
[0027]
【Example】
Example 1
As the photochromic compound, 1,2-bis (5-ethoxy-2-methylthiazole) hexafluorocyclopentene [hereinafter abbreviated as PC1], 1,2-bis (3- (2-methyl-6), which is a diarylethene compound, is used. -(2- (4-methoxyphenyl) ethynyl) benzothienyl))-3,3,4,4,5,5-hexafluorocyclopentene [hereinafter abbreviated as PC2], 1- (6- (2- (4- Dimethylaminophenyl) -1-ethenyl) -2-methyl-3-benzothionyl) -2-((5- (2- (4-cyanophenyl) -1-ethenyl))-2,4-dimethyl-3- Thienyl) -3,3,4,4,5,5-hexafluorocyclopentene [hereinafter abbreviated as PC3] was used.
When the absorption spectra of these photochromic compounds were measured, the maximum absorption wavelength before light irradiation was 330 nm for PC1, 300 nm for PC2, and 370 nm for PC3, and all were colorless. When PC1 and PC2 were irradiated with a 313 nm emission line from a high-pressure mercury lamp, the maximum absorption wavelength of PC1 was 475 nm, indicating yellow. Further, the maximum absorption wavelength of PC2 was 565 nm, showing a reddish purple color. When PC3 was irradiated with a 366-nm bright line from a high-pressure mercury lamp, the maximum absorption wavelength of PC3 was 632 nm, indicating blue.
[0028]
10 mg of PC1 was dissolved in toluene together with 100 mg of polystyrene, and blade-coated on a support substrate (thickness: 100 μm) made of white polyethylene terephthalate. Similarly, PC2 and PC3 were dissolved in toluene together with polystyrene, PC2 was laminated on the PC1 layer, and PC3 was further laminated thereon to produce a photosensitive layer. The thickness of the three-layered photosensitive layer was about 30 μm.
When the entire surface of the photosensitive layer was irradiated with 313 nm and 366 nm emission lines from a high-pressure mercury lamp for several tens of seconds, all layers of PC1 to PC3 were colored to show a dark gray color.
Next, when a 468 nm LED was irradiated to a part of the photosensitive layer for several seconds, the irradiated portion turned blue-violet. Next, when another portion of the photosensitive layer was irradiated with a 560 nm LED for several seconds, the irradiated portion turned green. Further, when another portion of the photosensitive layer was irradiated with a 660 nm LED for several seconds, the irradiated portion became light red.
[0029]
(Comparative Example 1)
After preparing a photosensitive layer using the same photochromic compound as in Example 1, the entire surface of the photosensitive layer was irradiated with only 313 nm ultraviolet light from a high-pressure mercury lamp for several tens of seconds, but PC1 and PC2 developed color, but PC3 almost developed color. Without it, it turned red.
[0030]
(Example 2)
After preparing a photosensitive layer using the same photochromic compound as in Example 1, a portion of the photosensitive layer was irradiated with a 372 nm ultraviolet LED for several tens of seconds. As a result, only PC3 was colored and turned blue. Thereafter, when the entire surface of the photosensitive layer was irradiated with a 313 nm high pressure mercury lamp, the blue portion was dark gray and the other portions were red. Furthermore, when a 468 nm LED was irradiated to a part of the red portion, it turned reddish purple.
(Example 3)
When a photosensitive layer was prepared using the same photochromic compound as in Example 1, a portion of the photosensitive layer was irradiated with a 372 nm LED. As a result, only PC3 was colored and turned blue. Furthermore, when another part of the photosensitive layer was irradiated with a He—Cd laser (325 nm), red color was shown. Furthermore, when 560 nm LED was irradiated to a part of red part, it changed to yellow.
[0031]
(Example 4)
After producing a photosensitive layer using the same photochromic compound as in Example 1, a portion of the photosensitive layer was irradiated with a 372 nm LED at half the intensity of Example 3 for the same time, resulting in a color change as compared with Example 3. There was little, and it became light blue.
(Example 5)
After producing a photosensitive layer using the same photochromic compound as in Example 1, a portion of the photosensitive layer was irradiated with a He—Cd laser (325 nm), which showed red color. Further, when a 560 nm LED was irradiated to a part of the red portion at half the intensity of Example 3, the color change was small compared to Example 3 and the color changed to light red.
(Example 6)
When the photosensitive layer whose color was changed in Examples 1 to 5 was irradiated with a xenon lamp having a wavelength of 400 nm or more for several seconds, all the compounds were decolored and white of the white polyethylene terephthalate supporting substrate.
The white polyethylene terephthalate substrate became white.
[0032]
(Example 7)
Several 372 nm LEDs were arranged in a line. At this time, the four sides of each LED were covered with reflecting mirrors so that the mutual light did not interfere. Similarly, several 468 nm and 560 nm LEDs were arranged in a line and arranged in parallel in the order of 372 nm, 468 nm, and 560 nm. In addition, a fluorescent tube (313 nm) was placed in front of the 372 nm LED.
After producing a photosensitive layer using the same photochromic compound as in Example 1, the photosensitive layer was slowly conveyed from the fluorescent tube side at a few mm / second, and each light source was turned on / off at regular intervals. As a result, the color of each part of the photosensitive layer was changed by the irradiated light source, so that yellow, blue and dark gray colors could be displayed.
[0033]
【The invention's effect】
As described above, according to the first aspect of the present invention, since multicolor image display is possible only by light irradiation, the use energy is smaller than that of the heat-sensitive method and higher than that of the electric field method. It is possible to provide a multicolor image display method that can form an image with a high resolution and that can use an image display medium that is stable against heat and moisture and can be used repeatedly because many photochromic compounds can be used. it can.
According to the second aspect of the present invention, it is not necessary to irradiate a fine spot unit corresponding to the pixel size as a light source of at least one of the two types of ultraviolet light. Thus, it is possible to provide a multicolor image display method that is easy in configuration and advantageous in cost.
Furthermore, according to the third aspect of the present invention, it is not necessary to irradiate light (writing processing) at all on a portion corresponding to white (colorless) on the image signal, and selectively only on a portion other than white. When light is irradiated but an image in which the white portion occupies most is targeted, a multicolor image display method capable of reducing writing energy and writing time can be provided.
[0034]
Furthermore, according to the present invention described in claim 4, since the three primary colors for color display are obtained by changing the wavelength of the light to be irradiated, the predetermined wavelength is set at a predetermined position on the image display medium in accordance with the image signal. A multicolor image display method capable of multicolor display can be provided by irradiating the light.
Furthermore, according to the present invention described in claim 5, by forming the protective layer, it is possible to reduce the adverse effect on the color development of the compound constituting the photosensitive layer due to moisture, specific gas, etc., and durability. And a multicolor image display method capable of multicolor display with high reliability can be provided.
Furthermore, according to the present invention described in claim 6 or 7, since the degree of color development can be adjusted by controlling the irradiation intensity or irradiation time of the light source, it is necessary and sufficient for the color density required for the image to be displayed. Provided is a multicolor image display method that can generate various color development, reduce the degree of decoloration by visible light irradiation, can reduce energy consumption, and is advantageous in the durability of repeated coloring and decoloring of materials. be able to.
[0035]
Furthermore, according to the present invention described in claim 8, a white light source is provided separately from the visible light source of each wavelength for selectively decoloring each photochromic material to irradiate the entire surface of the display unit with white light. By adding this process, it is possible to provide a multicolor image display method capable of erasing all display images in a short time.
Furthermore, according to the present invention described in claim 9, since the visible light source for selectively decoloring each photochromic material is constituted by the white light source and the optical filter, the formation conditions of the optical filter, or replacement installation Thus, it is possible to provide a multicolor image display device that can easily adjust the wavelength.
Furthermore, according to the present invention described in claim 10, since a light emitting element having a specific emission wavelength region is used as a visible light source, and no light absorbing member such as an optical filter is used, the light use efficiency is high and consumption A multicolor image display apparatus capable of reducing energy can be provided.
Furthermore, according to the present invention described in claim 11, it is possible to provide a rewritable multicolor image display device capable of writing and erasing a high resolution image in a short time.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration example of a photosensitive layer according to the present invention.
FIG. 2 is a diagram showing an example of a multicolor image display method of the present invention.
FIG. 3 is a diagram showing an example of a multicolor image display method of the present invention.
FIG. 4 is a diagram illustrating an example of a multicolor image display method according to the present invention.
FIG. 5 is a side view showing an example of a multicolor image display device of the present invention.
6 is a plan view of the multicolor image display device of FIG. 5. FIG.
[Explanation of symbols]
1 Image display medium
2 Transport rollers
3 White light
4 UV LED array
5 UV lamp
6 LED array (550nm)
7 LED array (450nm)

Claims (11)

For an image display medium in which a photosensitive layer containing two or more types of photochromic compounds having different maximum absorption wavelengths in a colored state is formed on a support substrate,
By irradiating two ultraviolet light of different wavelengths, after color development to all types of photochromic compound contained in the photosensitive layer, coloring the respective wavelength range which corresponds to the maximum absorption wavelength of the photochromic compounds of visible light, respectively A multicolor image display method characterized in that an image is formed by irradiating a predetermined region and selectively erasing each photochromic compound. 2. The multicolor image display method according to claim 1, wherein at least one of the two types of ultraviolet light is irradiated to the entire image display unit of the image display medium. The multicolor image display method according to claim 1, wherein each of the two types of ultraviolet light is irradiated only to a predetermined region. The photosensitive layer is
A photochromic compound having a maximum absorption wavelength in a colored state in a range of 400 nm to less than 500 nm, a photochromic compound in a range of 500 nm to less than 600 nm, and a photochromic compound in a range of 600 nm to less than 700 nm The multicolor image display method according to any one of claims 1 to 3. 5. A multicolor image display method according to claim 1, wherein the protective layer is formed on the surface of the photosensitive layer. 6. The multicolor image display method according to claim 1, wherein the irradiation intensity or irradiation time of ultraviolet light is controlled. 7. The multicolor image display method according to claim 1, wherein the irradiation intensity or irradiation time of visible light is controlled. 8. The multicolor image display method according to claim 1, further comprising a step of irradiating the entire surface of the image display portion of the image display medium with white light. The multicolor image display method according to claim 1, wherein the visible light source includes a white light source and an optical filter. The multicolor image display method according to claim 1, wherein the visible light source is a plurality of types of light emitting elements having different emission wavelengths. An image is formed using the multicolor image forming method according to claim 1, comprising a line-shaped ultraviolet light source and a visible light source, and relatively moving the image display medium and the light source. A multicolor image display device characterized by the above.

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