JP4172933B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus for forming an image on a reversible recording medium that can be repeatedly written and erased by light irradiation.
[0002]
[Prior art]
Although there have been some researches on color reversible recording media using photochromic compounds that cause reversible color changes when irradiated with light, an example of a practical image forming device that can reversibly display full-color images many times has been proposed. Yes still not.
For example, in Japanese Patent Application Laid-Open No. 5-271649, three kinds of photochromic diarylethene compounds that develop yellow-orange when irradiated with ultraviolet light at 254 nm, red when irradiated with ultraviolet light at 313 nm, and blue-purple when irradiated with ultraviolet light at 365 nm are mixed, Techniques for irradiating ultraviolet light corresponding to each have been proposed.
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. Photochromic compounds that absorb three kinds of ultraviolet light and develop three primary colors must be collected. Most photochromic compounds have an absorption wavelength band of at least 300 nm or less, and in order to be put into practical use, not only the coloring properties but also the repeated durability, thermal / humid stability, etc. must be considered. It is very difficult to develop a material that satisfies all of the above.
[0003]
In JP-A-7-199401, after coloring all kinds of photochromic compounds with a 366 nm ultraviolet lamp against a mixture of three kinds of photochromic fulgide compounds showing yellow, magenta and cyan in a colored state, the color is developed. A technique for selectively erasing by irradiating visible light in a wavelength region corresponding to the maximum absorption wavelength of each photochromic compound has been proposed. However, with the above technique, it is not easy to control the color tone, and practical application to an image forming apparatus is difficult.
[0004]
[Problems to be solved by the invention]
In view of the above problems, an object of the present invention is to provide an image forming apparatus that performs color reversible recording using an existing projector.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has the following features .
[0006]
According to the first aspect of the present invention, at least ultraviolet light is irradiated to a reversible recording 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. Step of developing all kinds of photochromic compounds contained in the photosensitive layer, and irradiating each predetermined region with visible light in a wavelength range corresponding to the maximum absorption wavelength of each of the developed photochromic compounds. An image forming apparatus that forms an image by performing a process of selectively erasing a photochromic compound, and a white light source that includes an ultraviolet wavelength region in an emission wavelength band, and an ultraviolet wavelength region and a colored portion, respectively. Spectroscopic process for spectrally separating a white light source for each wavelength region corresponding to the maximum absorption wavelength of the photochromic compound, and the spectroscopic ultraviolet wavelength A projection process for projecting the image onto a reversible recording medium, a light modulation process that is provided for each dispersed wavelength region and modulates the dispersed light in each wavelength region for each pixel according to image data, and light modulation A projection step of synthesizing and projecting the light of each wavelength region modulated in the step onto a reversible recording medium. According to the second aspect of the present invention, at least ultraviolet light is irradiated to a reversible recording 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. Step of developing all kinds of photochromic compounds contained in the photosensitive layer, and irradiating each predetermined region with visible light in a wavelength range corresponding to the maximum absorption wavelength of each of the developed photochromic compounds. An image forming apparatus that forms an image by performing a process of selectively erasing a photochromic compound, and a white light source that includes an ultraviolet wavelength region in an emission wavelength band, and an ultraviolet wavelength region and a colored portion, respectively. a spectroscopic process that splits white light source for each wavelength region which corresponds to the maximum absorption wavelength of the photochromic compound, spectrally separated ultraviolet wave A projection step of projecting a band on the reversible recording medium, a light modulation step of sequentially modulated for each pixel in accordance with light of each wavelength region is split into image data, for each wavelength region modulated by the light modulation step A projection process of sequentially projecting light onto a reversible recording medium.
[0007]
According to a third aspect of the present invention, there is provided the image forming apparatus according to the first or second aspect, which has a function of controlling an area to be projected in accordance with image data. According to a fourth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to third aspects, which has a function of controlling an area to be projected according to a surface area of the reversible recording medium. The present invention of claim 5, the optical modulation process, according to any one of 4 to claims 1, characterized in that a liquid crystal panel for controlling the transmission amount of light from the light source in accordance with image data An image forming apparatus is assumed. According to a sixth aspect of the present invention, the light modulation step is a digital micromirror device having a plurality of micromirrors that control the reflection direction of light from the light source in accordance with image data. Item 5. The image forming apparatus according to any one of Items 1 to 4 . The present invention of claim 7 includes an image forming apparatus according to any one of claims 1 to 6, characterized in that it comprises a light source for all types of photochromic compound in the photosensitive layer in decolored state To do.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A feature of the image forming apparatus of the present invention is that a reversible recording medium in which a photosensitive layer containing a photochromic compound is formed on a support substrate is enlarged in the same way as an existing projector, that is, light modulated by a small light modulation element. Then, an image is formed by irradiation. An example of an image forming method by the image forming apparatus of the present invention is shown in FIG.
The reversible recording medium shown in FIG. 1 includes a support substrate 101, a first photosensitive layer 102 containing a photochromic compound having a maximum absorption wavelength in a colored state of about 400 to 500 nm, and a maximum absorption wavelength in a colored state of about 500 to 600 nm. And a third photosensitive layer 104 containing a photochromic compound having a maximum absorption wavelength in a colored state of about 600 to 700 nm. These photochromic compounds exhibit yellow, magenta, and cyan colors, respectively, in a colored state.
[0009]
As an image forming method, first, the entire surface of the reversible recording medium is irradiated with ultraviolet light in an ultraviolet light irradiation step, whereby all types of photosensitive layers 101, 102, 103 are colored on the entire surface. Next, blue light (B, wavelength of about 450 nm), green light (G, wavelength of about 550 nm), and red light (R, wavelength of about 650 nm) are supplied from the projector unit 105 to the surface of the reversible recording medium according to each image signal. Irradiate. At this time, only the photochromic compound that develops yellow in the portion irradiated with blue light exhibits a decoloring reaction. Similarly, only the photochromic compound that develops magenta in the portion irradiated with green light and only the photochromic compound that develops cyan in the portion irradiated with red light show a decoloring reaction. Therefore, the light modulation element of the projector unit 105 is controlled so as to erase the color other than the color desired to be recorded on the reversible recording medium, thereby forming an image. In addition, although the example of FIG. 1 showed the full-color image formation method by yellow, magenta, and cyan, it is not restricted to this, The projector part which irradiates the light of the wavelength corresponding to the absorption wavelength of arbitrary photochromic compounds and photochromic compounds. By using it, an image of two or more colors can be recorded.
[0010]
Configuration examples of the projector unit are shown in FIGS. Although it may be exactly the same as an existing projector, it is desirable to optimize the projection lens and the like because the projection size is as small as the size of the reversible recording medium (about A6 to A3). FIG. 2 shows an example in which three transmissive liquid crystal panels 207 are used in the projector unit as a light modulation process . The light emitted from the light source 201 is made uniform by the optical integrator 202 and is polarized by the polarizing element 203. This polarized light is split into blue light (B), green light (G), and red light (R) by a dichroic mirror 205 as a spectroscopic process , and then is incident on a liquid crystal panel 207 via a condenser lens 206 and modulated. . Light modulated by each liquid crystal panel is combined by a cross dichroic prism 208 and enlarged and projected onto a reversible recording medium by a projection lens 209. Here, the light source 201 includes a discharge lamp such as a halogen lamp and a metal halide lamp, a reflector, a lens, and the like. Although the transmissive liquid crystal panel is used in the present configuration example in FIG. 2, light can be similarly irradiated even when a reflective liquid crystal panel is used. In the case of the configuration example of FIG. 2, R, G, and B light are simultaneously irradiated, so that high-speed image recording can be performed and light use efficiency is high. Further, since the liquid crystal panel can be manufactured at a relatively low cost, the image forming apparatus can be manufactured at low cost.
[0011]
FIG. 3 shows an example in which three digital micromirror devices (hereinafter abbreviated as DMD) having a plurality of micromirrors that control the light reflection direction are used in the projector unit as the light modulation process . The light emitted from the light source 301 is made uniform by the light integrator 302, passes through the total reflection prism 305, and is converted into blue light (B), green light (G), and red light (R) by the color separation / color combination prism 306. Spectroscopic. Each of the split lights is modulated by the DMD 307, and then again synthesized by the color separation / color combination prism 306, and enlarged and projected onto the reversible recording medium by the projection lens 308. The configuration of the light source 301 and the like may be the same as that of the liquid crystal panel shown in FIG. In the case of the configuration example of FIG. 3, since light of R, G, and B is irradiated at the same time, high-speed image recording can be performed, and light utilization efficiency is very high because it is not necessary to polarize the light.
[0012]
2 and 3 show the case where three light modulation elements are used, but as another feature of the image forming apparatus of the present invention, even one light modulation element can be formed. In this case, a reversible recording medium may be sequentially irradiated through a light modulation element and a projection lens by sequentially separating the light source using a movable spectral filter such as a color wheel. If the switching of the spectral filter and the switching of the image signal of the light modulation element are synchronized, a single color image can be recorded. In this configuration, an inexpensive image forming apparatus can be obtained as compared with the case where a plurality of light modulation elements are used. FIG. 4 shows an example in which one transmissive liquid crystal panel is used for the light modulation process in the projector unit. Light emitted from the light source 401 is switched to R, G, and B light by the color wheel 402. First, the light of B is made uniform by the optical integrator 403 and polarized by the polarizing element 404. After this polarized light is modulated by the liquid crystal panel 406, it is further passed through a polarizing element and enlarged and projected onto a reversible recording medium by a projection lens. After the image recording is performed on the yellow coloring compound with the B light, the color wheel 402 is switched to the G light, and the image is recorded on the reversible recording medium in the same manner. Further, the image is recorded on the reversible recording medium by switching to the R light. Although the transmissive liquid crystal panel is used in the configuration example of FIG. 4, light irradiation can be performed in the same manner using a reflective liquid crystal panel, DMD, or the like.
[0013]
FIG. 5 shows a configuration example of an image forming apparatus for a reversible recording medium using the projector unit as shown in FIGS. The reversible recording medium 506 conveyed from the paper supply unit 501 by the paper supply roller 502 and the conveyance roller 503 is colored by passing through a thin tubular ultraviolet light source 504. The reversible recording medium 506 that has developed color on the entire surface is further conveyed and stopped under the projector unit 505. In the stopped state, the projector unit 505 irradiates the entire surface of the reversible recording medium 506 with R, G, and B light to form an image.
In the configuration example of FIG. 5, the reversible recording medium 506 is directly irradiated with light from the projector unit 505, but the optical path length and the like may be adjusted by placing a mirror or lens on the optical path.
[0014]
In addition, the image forming apparatus of the present invention can also obtain ultraviolet light for coloring the photochromic compound from the light source of the projector unit. Halogen lamps and metal halide lamps used as light sources for projector units emit light in the ultraviolet wavelength region as well as in the visible wavelength region. Therefore, by using the light in the ultraviolet wavelength region as a light source for coloring the photochromic compound, only one light source is required in the image forming apparatus, resulting in a reduction in size and cost.
A specific configuration example is shown in FIG. The configuration example of FIG. 6 is almost the same as the configuration example using three transmissive liquid crystal panels shown in FIG. 2, except that a dichroic mirror 602 that reflects only the ultraviolet wavelength region is disposed next to the light source 601. This is a feature of this configuration. The ultraviolet light reflected by the dichroic mirror 602 is incident on the projection lens 611 by the mirror 605 or the like, and is irradiated on the entire reversible recording medium. Although it is necessary to stop the irradiation of ultraviolet light after the entire surface of the reversible recording medium has developed color, ON / OFF switching can be controlled by providing a movable shutter 606 on the optical path of the ultraviolet light. In the configuration example of FIG. 6, a transmissive liquid crystal panel is used as the light modulation element. However, even if a reflective liquid crystal panel or DMD is used, ultraviolet light can be irradiated in exactly the same manner. Further, in the configuration example of FIG. 6, the case where three light modulation elements are used is shown, but the same is true even when one light modulation element is used as shown in FIG. In addition, when a color wheel and a single light modulation element are used, it is easier to divide the color wheel into R, G, B light as well as ultraviolet light, and switch to irradiate light. Irradiation with ultraviolet light is possible with a simple structure.
[0015]
According to another aspect of the present invention, there is provided an image forming apparatus including a projector unit, and recording an enlarged image on a reversible recording medium. The advantages of image recording by enlarged projection are listed below.
The first is that images can be recorded all over the reversible recording medium. Since it is not necessary to record an image while transporting a reversible recording medium or a light source, a high-quality image can be obtained without causing a color shift. Another feature of the magnified projection type is that the illuminance of the light source, which is a problem when irradiating light on the entire reversible recording medium, can be easily made uniform. Secondly, by adjusting the lens so as to form an image on the surface of the reversible recording medium, a high-quality recorded image free from image blur can be easily obtained.
Thirdly, by using a plurality of light modulation elements, it is possible to simultaneously irradiate R, G, and B light, so that high-speed image recording can be performed. Since the light use efficiency of the light source is high, the recording energy is also greatly reduced.
The fourth point is that the irradiation area can be changed by controlling the enlargement ratio. For example, when image recording is performed on only a part of a reversible recording medium, high-speed image recording can be performed by reducing the enlargement ratio and concentrating light energy. Further, if the enlargement ratio is changed according to the size of the fed reversible recording medium such as A4 and B5, it is possible to cope with various reversible recording medium sizes. The enlargement ratio can be easily controlled by providing a zoom lens.
[0016]
As the reversible recording medium used in the present invention, the following structure is suitable.
The support substrate preferably has a white surface, but may be colored according to the application. The support substrate is preferably a relatively thin medium such as paper or film, but is not limited thereto.
The photosensitive layer contains a photochromic compound that becomes colored when irradiated with ultraviolet light and decolored when irradiated with visible light. A photochromic compound includes a P-type material that is stable in heat and has a color change only by light, and a T-type material that has a color change that is unstable to heat and causes a color change not only by light but also by heat. However, it is particularly desirable to use a P-type material in the present invention. Typical examples of P-type materials include fulgide compounds and diarylethene compounds.
[0017]
The color in the colored state varies depending on the type of photochromic compound, and a desired material may be selected depending on the application. In particular, when recording a full-color image, materials that develop the three primary colors yellow, magenta, and cyan are important.
Examples of the yellow coloring material include “2- [1- (4-acetyl-2,5-dimethyl-3-furyl) ethylidene] -3-isopropylidene succinic anhydride”, “2- [1- (5 -Methyl-2-phenyl-4-oxazolyl) ethylidene] -3-isopropylidene succinic anhydride "," 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 magenta coloring material include “2- [1- (2,5-dimethyl-1-phenylpyrazolyl) ethylidene] -3-isopropylidene succinic anhydride”, “2- [1- (3- Methoxy-5-methyl-1-phenyl-4-pyrazolyl) ethylidene] -3-isopropylidene succinic anhydride "," 1,2-bis (3- (2-methyl-6- (2- (4-methoxy Phenyl) ethynyl) benzothienyl))-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 -Hexafluorocyclopen Down "and the like.
Examples of cyan coloring materials include “2- [1- (1,2,5-trimethyl-3-pyrrolyl) ethylidene] -3-isopropylidene succinic anhydride”, “2- [2,6- Dimethyl-3,5-bis (p-dimethylaminostyryl) benzylidene] -3-isopropylidene succinic anhydride "," 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- Butoxy-1,2-dimethyl-3-indolyl) -3,3,4,4,5,5- hexafluoro-cyclopentene "and the like.
The photochromic compound in the photosensitive layer may be dispersed in a resin such as an acrylic resin, a vinyl chloride resin, a polyester resin, a polyamide resin, a polyolefin resin, or a urethane resin, or encapsulated in a microcapsule. Also good. Moreover, you may form a transparent protective film on the surface of a photosensitive layer as needed.
[0018]
The image forming apparatus of the present invention can be used as a printer by connecting to a computer, and can also be applied to a copying machine by attaching a scanner unit. Further, it can be applied to a facsimile.
In the image recording method by the image forming apparatus of the present invention, since the rewrite recording can be performed even if the previous image remains on the reversible recording medium, the image erasing step is not particularly required. However, it is useful if the image forming apparatus has an image erasing function, for example, when it is desired to erase a recorded image after use in order to maintain confidentiality.
Therefore, the present invention further includes a light source for decolorizing all types of photochromic compounds in the photosensitive layer. Since the photochromic compound is decolored by visible light, for example, an erasing white light source may be provided.
[0019]
【Example】
(Example 1)
As the photochromic compound, fulgide-based compounds such as 2- [1- (1,2,5-trimethyl-3-pyrrolyl) ethylidene] -3-isopropylidene succinic anhydride [hereinafter abbreviated as PC1], 2- [ 1- (2-cyano-1,5-dimethyl-3-pyrrolyl) ethylidene] -3-isopropylidene succinic anhydride [hereinafter abbreviated as PC2], 2- [1- (5-methyl-2-phenyl-4) -Oxazolyl) ethylidene] -3-isopropylidene succinic anhydride [hereinafter abbreviated as PC3] was used. When the absorption spectrum of PC1 was measured, the absorption wavelength band before light irradiation was 360 nm, and it was colorless. Moreover, when the 366 nm emission line of the high pressure mercury lamp was irradiated, the maximum absorption wavelength was 634 nm, showing a bluish purple color. When the absorption spectrum of PC2 was measured, the absorption wavelength band before light irradiation was 349 nm, and it was colorless. Moreover, when the 366-nm emission line of the high pressure mercury lamp was irradiated, the maximum absorption wavelength was 569 nm, showing reddish purple. When the absorption spectrum of PC3 was measured, the absorption wavelength band before light irradiation was 337 nm, and it was colorless. Moreover, when the 366 nm emission line of the high pressure mercury lamp was irradiated, the maximum absorption wavelength was 465 nm, indicating yellow. 10 mg each of PC1, PC2 and PC3 fulgide compounds were dissolved in toluene together with 100 mg of polystyrene, and spin-coated on a white polyethylene terephthalate substrate (thickness: 188 μm) in this order to produce a multilayer reversible recording medium. The formed photosensitive layer had a thickness of about 35 μm.
When the entire surface of the reversible recording medium was irradiated with black light (wavelength 365 nm, illuminance 10 mW / cm ² ), each photochromic compound developed color and turned black.
Using a commercially available transmissive liquid crystal projector (Hitachi, CP-S220J), a red, green, and blue stripe pattern is projected onto a reversible recording medium, and the red pattern portion is red and the green pattern portion is green and blue. The pattern portion changed its color to blue.
[0020]
(Example 2)
The reversible recording medium prepared in Example 1 was irradiated with black light (wavelength 365 nm, illuminance 10 mW / cm ² ). When a red, green, and blue stripe pattern is projected on a reversible recording medium using a commercially available projector (plus Co., Ltd., U3-810Z) using DMD as a light modulation element, the red pattern portion is red and the green pattern portion Changed to green and the blue pattern changed to blue.
[0021]
(Example 3)
A commercially available transmissive liquid crystal projector (Hitachi, CP-S220J) was modified, and a dichroic mirror that selectively reflects only ultraviolet light was installed in front of the lamp light source. When the reversible recording medium prepared in Example 1 was irradiated with reflected ultraviolet light, each photochromic compound was colored and turned black.
[0022]
Example 4
The reversible recording medium prepared in Example 1 was irradiated with black light (wavelength 365 nm, illuminance 10 mW / cm ² ). When a zoom function of a commercially available transmissive liquid crystal projector (Hitachi, CP-S220J) is used to project an image reduced to ¼ of the area of the first embodiment, the color change is faster than that of the first embodiment. It was observed.
[0023]
(Example 5)
When the color fluorescent images produced in Examples 1, 2, and 4 were irradiated on the entire surface with a white fluorescent lamp, the images were erased and the reversible recording medium became white.
[0024]
【The invention's effect】
As described above , according to the present invention described above , since the photosensitive layer is irradiated with light by the enlargement projection method, high-quality image recording without color shift and image blur is possible, and a plurality of wavelengths can be recorded. Therefore, it is possible to provide an image forming apparatus capable of high-speed and low-energy image recording. Further, according to the present invention described above , since color recording can be performed by one light modulation process, an inexpensive image forming apparatus can be provided. Furthermore, according to the present invention described in claim 1 or 2 , since only one irradiation light source is required, a small and inexpensive image forming apparatus can be provided. Furthermore, according to the third aspect of the present invention, since the light energy can be concentrated according to the recording image area, it is possible to provide an image forming apparatus capable of high-speed and low-energy image recording. Furthermore, according to the fourth aspect of the present invention, since the irradiation area can be freely changed, it is possible to provide an image forming apparatus that can cope with various sizes of reversible recording media. Furthermore, according to the fifth aspect of the present invention, since the manufacturing cost of the light modulation process is low, an inexpensive image forming apparatus can be provided. Further, according to the present invention described in claim 6 , since the light utilization efficiency is high, it is possible to provide an image forming apparatus that is high speed and low power consumption. Furthermore, according to the seventh aspect of the present invention, it is possible to provide an image forming apparatus capable of easily erasing a recorded image as necessary by providing a light source for batch image erasing.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an example of an image forming method by an image forming apparatus of the present invention.
FIG. 2 is a diagram illustrating a configuration example when three liquid crystal panels are used in the projector unit.
FIG. 3 is a diagram illustrating a configuration example when three digital micromirror devices (DMDs) are used in the projector unit.
FIG. 4 is a diagram illustrating a configuration example when one liquid crystal panel is used in the projector unit.
FIG. 5 is a schematic configuration diagram showing an image forming apparatus of the present invention.
FIG. 6 is a diagram illustrating a configuration example when ultraviolet light is obtained from a light source of a projector unit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 Support substrate 102 1st photosensitive layer 103 2nd photosensitive layer 104 3rd photosensitive layer 105 Projector part 201 Light source 202 Optical integrator 203 Polarizing element 204 Mirror 205 Dichroic mirror 206 Condenser lens 207 Liquid crystal panel 208 Cross dichroic prism 209 Projection lens 301 Light source 302 Optical integrator 303 Condenser lens 304 Mirror 305 Total reflection prism 306 Color separation / color combination prism 307 DMD
308 Projection lens 401 Light source 402 Color wheel 403 Optical integrator 404 Polarization element 405 Condenser lens 406 Liquid crystal panel 407 Projection lens 501 Paper feed cassette 502 Paper feed roller 503 Transport roller 504 Ultraviolet light source 505 Projector unit 506 Reversible recording medium
601 light source
602 dichroic mirror
603 light integrator
604 polarizing element
605 mirror
606 movable shutter
607 dichroic mirror
608 condenser lens
609 LCD panel
610 cross dichroic prism
611 projection lens

Claims (7)

For a reversible recording 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,
At least a step in which all types of photochromic compounds contained in the photosensitive layer are colored by irradiating with ultraviolet light, and a predetermined range of visible light in a wavelength region corresponding to the maximum absorption wavelength of each colored photochromic compound A step of selectively erasing each photochromic compound by irradiating with, an image forming apparatus for forming an image by performing,
A white light source that includes an ultraviolet wavelength region in the emission wavelength band, a spectral process for spectrally separating the white light source for each wavelength region corresponding to the ultraviolet wavelength region and the maximum absorption wavelength of each colored photochromic compound, and the dispersed ultraviolet wavelength region A projection process for projecting the image onto a reversible recording medium, a light modulation process that is provided for each dispersed wavelength region and modulates the dispersed light in each wavelength region for each pixel according to image data, and light modulation A projection step of synthesizing and projecting the light of each wavelength region modulated by the step onto a reversible recording medium. For a reversible recording 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,
At least a step in which all types of photochromic compounds contained in the photosensitive layer are colored by irradiating with ultraviolet light, and a predetermined range of visible light in a wavelength region corresponding to the maximum absorption wavelength of each colored photochromic compound A step of selectively erasing each photochromic compound by irradiating with, an image forming apparatus for forming an image by performing,
A white light source that includes an ultraviolet wavelength range in the emission wavelength band, a spectral process for spectrally separating the white light source for each wavelength range corresponding to the ultraviolet wavelength range and the maximum absorption wavelength of each colored photochromic compound, and the spectral ultraviolet wavelength range Projecting onto a reversible recording medium, a light modulation step for sequentially modulating the light in each wavelength band for each pixel according to image data, and light in each wavelength region modulated by the light modulation step An image forming apparatus comprising: a projection step of sequentially projecting images on a reversible recording medium. The image forming apparatus according to claim 1 or 2, characterized in that it comprises a function of controlling the area to be projected according to the image data. The image forming apparatus according to any one of claims 1, characterized in that it comprises a function of controlling the area to be projected according to the surface area of the reversible recording medium 3. Optical modulation process, the image forming apparatus according to any one of claims 1 to 4, characterized in that a liquid crystal panel for controlling the transmission amount of light from the light source in accordance with image data. Optical modulation process, according to any one of 4 to claims 1, characterized in that a digital micromirror device having a plurality of micro-mirrors to control the reflection direction of the light from the light source in accordance with image data Image forming apparatus. The image forming apparatus according to any one of claims 1 to 6, all types of photochromic compound in the photosensitive layer comprising: a light source for the decolored state.

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