JP2009096011A - Image rewriting method and its apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable information such as an image to be rewritten at a high speed to a reversible thermosensitive recording medium by using an inexpensive low-output laser light source, and also to achieve recording of a large-angle solid image. <P>SOLUTION: The recording medium 2 is heated to a color developable temperature band. The recording medium 2 is uniformly colored by cooling after heating. Then, when the temperature of the recording medium 2 to uniformly colored decreases to either one of within a temperature band in which color fading is possible or the outside of the temperature band which is within a temperature band lower by a predetermined lower temperature than a lower limit temperature of the temperature band, the recording medium 2 is heated and decolored like an image. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention converts light energy applied to a reversible thermosensitive recording medium into heat energy, and enables color development and decoloring by controlling the heat energy, and is non-contact with the reversible thermosensitive recording medium. The present invention relates to an image rewriting method and apparatus for recording and erasing data such as images.

  The reversible thermosensitive recording medium is heated to a color development temperature range higher than normal temperature, and develops color by cooling at a predetermined cooling rate, and maintains a color development state at normal temperature in a decolorable temperature range lower than the color development possible temperature range. Discolors when heated. For example, Patent Documents 1 to 3 disclose techniques for recording and erasing images and the like on such a reversible thermosensitive recording medium. For example, in Patent Document 1, a light-absorbing heat conversion layer is formed on a reversible thermosensitive recording medium, or a light-absorbing heat conversion material is mixed in a recording layer containing a leuco dye and a developer. Disclosed is a method in which a laser beam is focused on and scanned on a reversible thermosensitive recording medium, and light energy is converted into thermal energy to form data such as images in a non-contact manner.

  A technique relating to the reversible thermosensitive recording medium is disclosed in, for example, Patent Document 4. This patent document 4 discloses a reversible thermosensitive recording medium having a color development temperature of 130 ° C., a decolorization temperature of 60 to 70 ° C., a heating time required for color development of 1.2 msec, and a heating time required for decoloring of 20 sec. . As described above, the color development temperature is higher than the color erase temperature, and the heating time required for color erase is longer than the heat time required for color development. 2. Description of the Related Art There is an image rewriting apparatus that erases a color portion of a reversible thermosensitive recording medium in the previous image formation and forms data such as a new image by color development. In such an image rewriting apparatus, the image forming speed is dominated by the decoloring process, and high-speed image formation is difficult.

  For example, Patent Document 5 discloses a reversible thermosensitive recording medium that can be erased at a high speed in contrast to the reversible thermosensitive recording medium that requires heating for erasing for a long time. It is known that such a reversible thermosensitive recording medium that can be erased at high speed instantaneously changes from a colored state to a decolored state with a small amount of heat energy. In addition, a reversible thermosensitive recording medium having high-speed decoloring property is heated and melted to a melting point of the reversible developer or higher, and then the cooling rate is compared with a reversible thermosensitive recording medium not having high-speed decoloring property. Need to be fast.

For example, Patent Document 1, Patent Document 4, and Patent Documents 6 and 7 disclose techniques related to a method for rewriting an image or the like on a reversible thermosensitive recording medium. As a method of rewriting data such as an image on such a reversible thermosensitive recording medium, a positive image formation in which the reversible thermosensitive recording medium is completely erased and then heated in an image-like manner, and a reversible thermosensitive recording medium is used. It is known to form a negative image in which the entire surface is colored and then image-like, that is, the background portion is heated and decolored. Regardless of the image rewriting method, the finally obtained image is the same.
Japanese Patent No. 3446316 JP 2004-345273 A JP-A-11-151856 JP-A-5-124360 JP 2001-162941 A JP 59-120492 A JP 2001-341429 A

  The image rewriting method using a reversible thermosensitive recording medium mixes a light-absorbing heat conversion material with a reversible thermosensitive recording medium, converts light energy into heat energy, and forms image data in a non-contact manner. This is suitable for extending the life of the heat-sensitive recording medium and the life of the image rewriting apparatus itself, and maintaining good image quality over a long period of time. Since such an image rewriting device is non-contact, it has an advantage over an image rewriting device using, for example, a thermal head.

  However, in the current state of such an image rewriting apparatus, there is no choice other than a laser beam as a light source for image formation because of the relationship between resolution and light intensity, and therefore an expensive and high output laser light source is required. For example, when forming an image having a width of 100 mm at a speed of about 76 mm / sec in a direction orthogonal to the image width, assuming that the pixel size is, for example, 0.125 mm × 0.125 mm, the surface of the reversible thermosensitive recording medium is about A laser beam having a light intensity of 45 to 60 W is required. For example, if there is one laser beam, the power is 50 W per laser beam, but in the case of n laser beams, the power is 50 W / n per laser beam. For this reason, a laser light source of 50 W per laser beam is not preferable in terms of cost. Similarly, a laser beam array in which a plurality of laser elements are arranged is also more expensive than a thermal head.

  Therefore, at present, a relatively low-power and low-cost laser light source is used, and image rewriting for recording and erasing on a reversible thermosensitive recording medium is performed at a low image forming speed. However, since the image forming speed is slow, raster scanning that scans the entire reversible thermosensitive recording medium cannot be performed, and scanning using one laser beam, that is, vector scanning that uses one laser beam for writing is employed.

  When an image is formed by scanning one reversible thermosensitive recording medium with a laser beam, for example, data such as an image having a width of 100 mm is transferred at a speed of, for example, about 76 mm / sec in a direction orthogonal to the image width of the data. When scanning with a pixel size of 0.125 mm × 0.125 mm, for example, the exposure time per pixel is about 1 to 2 μsec.

  The light absorption heat conversion material mixed with the reversible thermosensitive recording medium is used by being dispersed in an organic polymer binder. When the heat conduction of the light-absorbing heat converting material or other materials constituting the reversible thermosensitive recording medium is insufficient with respect to the exposure time, the light-absorbing heat converting material and its surroundings are 300 when using a high-power laser beam. ~ 400 ° C or higher. For this reason, there is a possibility that the light-absorbing heat converting material and other materials constituting the reversible thermosensitive recording medium are thermally decomposed and melted. For this reason, for recording and erasing data such as images on a reversible thermosensitive recording medium, it is possible to employ a high-power laser beam such as that used for laser markers that melt and stamp plastic or metal surfaces. However, the light intensity of the laser beam that can be used is limited. Therefore, there is a limit to improving the image forming speed.

  Further, when an image is formed by scanning one laser beam on the reversible thermosensitive recording medium, there are two limitations: cost restrictions and thermal decomposition of the material constituting the reversible thermosensitive recording medium as described above. For this reason, it is difficult to employ a high-power laser light source. For this reason, when positive image formation is employed, it becomes difficult to form a color development pattern with a large area, that is, a solid image with a large angle of view.

  Specifically, one laser beam is main-scanned on the reversible thermosensitive recording medium, and at the same time, the reversible thermosensitive recording medium is moved in the sub-scanning direction perpendicular to the main scanning direction or the scanning line of the main scanning is moved. When raster scanning is used, if a laser beam with sufficient light intensity is employed and a required exposure time cannot be ensured, the temperature rise in the color development region of the reversible thermosensitive recording medium will be insufficient. For this reason, if the time interval between the scanning lines when the main scanning of the laser beam is long, the color development area heated and melted by the laser beam irradiated on one scanning line on the reversible thermosensitive recording medium is cooled. Therefore, a part of the previous color development area is erased by the main scanning of the laser beam onto the next scanning line adjacent to the previous scanning line.

  Such decoloring of the color-scanned area that has been scanned first is due to the fact that the bottom of the Gaussian distribution is applied to a part of the color-developed area because the light intensity of the laser beam follows a Gaussian distribution. This is because the temperature erasable temperature range of the thermal recording medium is lower than the temperature range where color development is possible, and the color is erased even if the light intensity of the laser beam is low.

  In addition, when the light intensity of the laser beam is high, not only the light intensity distribution but also the heat conduction of the reversible thermosensitive recording medium may satisfy the color erasing condition of the previous color development region. In order to prevent such a phenomenon, the temperature of the entire reversible thermosensitive recording medium is increased with a required exposure time using a laser beam with sufficient light intensity, and the color development temperature range lower limit or higher and the color erasable temperature range upper limit higher than, It is necessary to maintain the temperature of the reversible thermosensitive recording medium after color development. For this reason, in the current image rewriting apparatus, since the main scanning width of the raster scan is set short in order to shorten the time interval of the scanning lines of the main scanning, it is difficult to form a solid image with a large angle of view.

Patent Document 4 discloses a color developing temperature of 130 ° C. and a color erasing temperature of 60 to 70 ° C. of a reversible thermosensitive recording medium. When a negative image formation is used in which the entire surface of the reversible thermosensitive recording medium is colored and then image-like, that is, the background portion is heated and decolored, the required light energy corresponding to the decoloring temperature is certainly Decrease.
However, since the color development temperature in the negative image formation is the same as in the positive image formation, the light intensity of the necessary laser beam is the same. Further, when the image printing ratio (color development area / total recording area) is less than 50%, the negative image formation that requires color development on the entire surface has a higher total power consumption than the positive image formation that requires only partial color development. However, negative image formation does not lead to low light intensity of the laser beam.

  Further, Patent Document 5 discloses a reversible thermosensitive recording medium having high-speed decoloring properties, but even when this reversible thermosensitive recording medium is used, the time required for decoloring, which was a conventional rate-determining step, is shortened. The light intensity required for color development is the same. However, the high-speed decoloring and reversible thermosensitive recording medium does not lead to a low light intensity of the laser beam.

  An object of the present invention is to use an inexpensive and low-power laser light source, to rewrite information such as an image on a reversible thermosensitive recording medium at high speed, and to realize recording of a large angle of view image and its To provide an apparatus.

  The image rewriting method according to the main aspect of the present invention is such that the color is developed by cooling to a color development temperature range higher than normal temperature, cooling at a predetermined cooling rate, and lower than the color development temperature range while maintaining the color development state at normal temperature. In an image rewriting method in which information is rewritten on a reversible thermosensitive recording medium that is decolored when heated to a decolorable temperature range, the reversible thermosensitive recording medium is heated to a color developable temperature range, and cooling after this heating is performed. The color development step for uniformly coloring the reversible thermosensitive recording medium by the above, and the temperature of the uniformly reversible thermosensitive recording medium within or outside the decolorable temperature range and the decolorizable temperature range A decoloring step of heating the reversible thermosensitive recording medium and decolorizing the reversible thermosensitive recording medium like information when the temperature falls to any one of the temperature bands lower than the lower limit temperature by a predetermined temperature.

  The image rewriting device according to the main aspect of the present invention is heated to a color development temperature range higher than normal temperature, and develops color by cooling at a predetermined cooling rate, and is lower than the color development possible temperature range while maintaining a color development state at normal temperature. In an image rewriting device that rewrites information on a reversible thermosensitive recording medium that loses its color when heated to a decolorable temperature range, the reversible thermosensitive recording medium is heated to a color developable temperature range, and cooling after this heating is performed. A color development system that uniformly colors the reversible thermosensitive recording medium, and the temperature of the uniformly reversible thermosensitive recording medium within or outside the decolorable temperature range and the decolorable temperature range. And a decoloring system that heats the reversible thermosensitive recording medium and decolorizes the reversible thermosensitive recording medium in an information-like manner when the temperature falls to one of the temperature bands lower than the lower limit temperature by a predetermined temperature.

  According to the present invention, an image rewriting method capable of rewriting information such as an image on a reversible thermosensitive recording medium at a high speed using a low-cost and low-power laser light source, and capable of recording an image with a large angle of view, and its Equipment can be provided.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a basic configuration diagram of an image rewriting apparatus, and FIG. 2 shows a schematic perspective view of the apparatus. On the recording medium conveying apparatus 1, a photothermal conversion type reversible thermosensitive recording medium (hereinafter referred to as recording medium) 2 is placed. The recording medium transport apparatus 1 transports the recording medium 2 in the medium transport direction Y at a constant speed. A direction perpendicular to the medium transport direction Y is a line exposure direction X described later. The recording medium transport apparatus 1 includes a plurality of transport rollers 3a and 3b and an endless transport belt 4 hung on the transport rollers 3a and 3b. For example, the transport belt 4 is driven by rotating the transport roller 3a. The recording medium 2 is moved and conveyed in the medium conveyance direction Y. The recording medium 2 is formed with a pre-recorded image 2a in which data such as an image has been recorded in the previous use, a uniform colored image 2b that is uniformly colored, and a rewritten recorded image 2c.

  FIG. 3 is a schematic sectional view of the recording medium 2. The recording medium 2 has a layer structure in which a support 2-1 is provided, and a reversible thermosensitive recording layer 2-2 in which a light-absorbing heat conversion material is mixed on the support 2-1 and a protective layer 2-3. Formed. Of these, the reversible thermosensitive recording layer 2-2 comprises at least a leuco dye, a reversible developer, and a light-absorbing heat conversion material.

  As the layer structure of the recording medium 2, for example, a reversible thermosensitive recording layer 2-2 is formed from a leuco dye and a reversible developer, and a light absorption heat conversion material is formed on the reversible thermosensitive recording layer 2-2. It is also possible to laminate a photothermal conversion layer. The recording medium 2 is formed with a reversible thermosensitive recording layer 2-2 from a leuco dye, a reversible developer, and a light absorption heat conversion material, and further a light absorption heat conversion on the reversible heat sensitive recording layer 2-2. It is also possible to laminate a photothermal conversion layer made of a material. Further, there is a reversible thermosensitive recording layer 2-2 containing a light absorption heat conversion material. In this reversible thermosensitive recording layer 2-2, when the average transmittance of light having the absorption wavelength of the light-absorbing heat-converting material is, for example, 30% or more, the light-absorbing heat-converting layer is directly below the reversible thermosensitive recording layer 2-2. It is also possible to laminate a photothermal conversion layer made of a material.

Hereinafter, materials used for each layer of the recording medium 2 will be described.
As specific examples of the leuco dye, those disclosed in Patent Documents 2, 3, and 5 can be used. It is not limited to this. Specific examples of the leuco dye include 3-diethylamino-7-o-chlorophenylaminofluorane, 3-diethylamino-7-m-chlorophenylaminofluorane, 3-diethylamino-7-p-chlorophenylaminofluorane, and the like. It is.

As the reversible developer, a phenol compound having a long-chain alkyl group is used. This reversible developer is disclosed in, for example, Patent Documents 2, 3, and 5. In this embodiment, it is necessary to limit to a reversible developer having high-speed decoloring property, and it is particularly desirable to use a specific reversible developer disclosed in Patent Document 5. For example, the reversible developer is preferably a compound represented by the following general formula (1), but is not limited thereto.

  In the compound represented by the general formula (1), X1 and X2 may be the same or different from each other, and oxygen atom, sulfur atom, or —CONH— bond that does not contain a hydrocarbon atom group at both ends is the minimum constituent Represents a divalent group as a unit. R1 represents a single bond or a divalent hydrocarbon group having 1 to 12 carbon atoms. R2 represents a divalent hydrocarbon group having 1 to 18 carbon atoms. Preferably it is a C1-C4 divalent hydrocarbon group. R3 represents a monovalent hydrocarbon group having 1 to 24 carbon atoms, preferably a hydrocarbon group having 6 to 24 carbon atoms, and more preferably a hydrocarbon group having 8 to 24 carbon atoms. Furthermore, the case where the sum of the carbon number of R1, R2 and R3 is 11 or more and 35 or less is particularly preferable. R1, R2 and R3 mainly represent an alkylene group and an alkyl group, respectively. In the case of R1, an aromatic ring may be included. f represents an integer of 0 to 4, and when f is 2 or more, R2 and X2 that are repeated may be the same or different.

X1 and X2 in the general formula (1) include a divalent group having a —CONH— bond that does not include a hydrocarbon atom group at both ends as a minimum structural unit. Specific examples thereof include, for example, diacylamine (— CONHCO-), diacyl hydrazine (-CONHNHCO-) and the like can be mentioned, and diacyl hydrazine, oxalic acid diamide, and acyl semicarbazide are preferable. A specific example of the reversible developer according to the present embodiment is, for example, Structural Formula (2), but is not limited thereto.

  Further, as disclosed in Patent Document 5, a reversible thermosensitive recording material produced by mixing with a leuco dye even if other reversible developer is used. When the reversible thermosensitive recording material transitions to a decolored state without showing an exothermic peak in the temperature rising process by differential scanning calorimetry or differential thermal analysis, it is used as a reversible thermosensitive recording material having high-speed decoloring properties. Is possible. That is, in this case, it is possible to instantaneously shift from the colored state to the decolored state with a small amount of heat energy. Therefore, the reversible thermosensitive recording material that can be used in the present embodiment is required to have high-speed decoloring properties, and is not limited to leuco dyes and reversible color developers suitable therefor.

  For example, a photothermal conversion dye is used as the light absorption heat conversion material used in the present embodiment. Specific examples of the light-absorbing heat conversion material include, for example, phthalocyanine compounds, metal complex compounds, polymethine compounds, naphthoquinone compounds, and the like, which are contained in the reversible thermosensitive recording layer 2-2 in a dispersed state or a molecular state. Can do. The light-absorbing heat conversion material is preferably a phthalocyanine compound metal complex compound from the viewpoint of photothermal conversion efficiency, solubility in a solvent, dispersibility in a resin, and light resistance to ultraviolet rays, and a phthalocyanine compound is particularly preferable. As the light absorption heat conversion material, those disclosed in Patent Documents 2, 3, and 5 can be used in more detail. Examples of phthalocyanine compounds include naphthalocyanine compounds, metal-free phthalocyanine compounds, iron phthalocyanine compounds, and the like. In the present embodiment, a material having an absorption peak in the vicinity of a wavelength of 808 nm to 830 mm of the laser light source 21 to be used is selected as the light absorption heat conversion material.

  In the reversible thermosensitive recording layer 2-2, various binders, additives and the like can be used for improving the performance. These binders, additives and the like are disclosed in, for example, Patent Documents 2, 3, and 5. For example, in Patent Documents 2, 3, and 5, the strength of the reversible thermosensitive recording layer 2-2 is improved, and each material of the composition of the reversible thermosensitive recording layer 2-2 is not unevenly distributed due to heating, cooling, or the like. A binder such as a heat resistant resin for uniformly dispersing is mentioned. Further, for example, Patent Documents 2, 3, and 5 include thermofusible substances for adjusting the color development sensitivity and the erasing temperature.

  The support 2-1 used in this embodiment not only supports the reversible thermosensitive recording layer 2-2, but also functions as a heat absorber in the cooling step after heating during color development. In particular, in the first embodiment, since natural cooling is adopted, the support body 2-1 controls most of the cooling rate. Therefore, a synthetic resin film such as polyethylene terephthalate or polypropylene having a predetermined thermal conductivity and specific heat is used for the support 2-1. The material of the support 2-1 that can be specifically used is disclosed in Patent Documents 2, 3, and 5, for example.

  As a layer structure of the recording medium 2, it is desirable to laminate a protective layer 2-3 as an outermost layer on the reversible thermosensitive recording layer 2-2. This apparatus can rewrite an image or the like in a non-contact manner with respect to the recording medium 2, and basically does not damage the recording medium 2 other than heating and cooling. However, when viewed from the entire life cycle of the recording medium 2, after the rewriting by this apparatus, it becomes a use stage that plays the original role of the recording medium 2.

  In the use stage of the recording medium 2, the recording medium 2 receives various damages such as rubbing, striking, bending, and ultraviolet irradiation. For this reason, the protective layer 2-3 which is a hard-coat layer is needed. In particular, since the photothermal conversion dye or leuco dye as the light absorption heat conversion material is highly likely to be damaged by ultraviolet absorption, various ultraviolet absorbers are mixed in the protective layer 2-3. The materials of the protective layer 2-3 including various usable UV absorbers are disclosed in, for example, Patent Documents 2 and 3. Generally, as the light absorption heat conversion material, a material having an absorption wavelength in the near-infrared region is used, and since the coloring wavelength region of the leuco dye is a visible region, the uppermost protective layer 2-3 absorbs only ultraviolet rays. In some cases, neither the light-absorbing heat converting material nor the leuco dye can affect its function.

  A coloring station 10 serving as a coloring system is provided above the recording medium conveying apparatus 1. The coloring station 10 heats the recording medium 2 to a colorable temperature band, and uniformly cools the recording medium 2 by cooling after the heating. That is, the coloring station 10 line-exposes the recording medium 2 in the line exposure direction X substantially perpendicular to the medium conveyance direction Y, and colors the recording medium 2 over the entire width of the predetermined effective coloring width W1 within the recording medium 2 width. Let At this time, the pre-recorded image 2a recorded by the previous use in the recording medium 2 becomes a uniform color image 2b.

  A decoloring station 20 as a decoloring system is provided above the recording medium conveying apparatus 1 and downstream of the coloring station 10. As shown in FIG. 5, which will be described later, the decoloring station 20 has the temperature of the recording medium 2 uniformly colored by the coloring station 10 within the decolorable temperature band S or outside the decolorable temperature band S and the decoloring. When the temperature falls to any one of the temperature zones lower than the lower limit temperature of the possible temperature zone S by a predetermined temperature, for example, when the temperature falls to a temperature Tc5 shown in FIG. Is erased like an image.

  In other words, the erasing station 20 is a recording medium 2 that is uniformly colored with a beam scanning exposure direction X that is substantially perpendicular to the medium conveyance direction Y and with a predetermined effective erasing width W2 within the width of the recording medium 2. The necessary portion of the uniform color image 2b is erased like an image by beam scanning exposure. Thereby, the uniform color image 2b recorded on the recording medium 2 is rewritten to the recorded image 2c. That is, in the uniform color image 2b, the portion corresponding to the background portion of data such as an image is erased and rewritten to the recorded image 2c.

Further, the decoloring station 20 has a heating time for the recording medium 2 shorter than a heating time for the recording medium 2 by the coloring station 10 and a heating energy given to the recording medium 2 by a heating energy given to the recording medium 2 by the coloring station 10. Is also small.
The time interval between the line exposure at the coloring station 10 and the beam scanning exposure at the decoloring station 20 is kept constant at any part on the recording medium 2. For this reason, the line exposure direction X in the coloring station 10 and the scanning exposure direction X in the decoloring station 20 are set at the same angle with respect to the medium transport direction Y. That is, the irradiation angle of the line-shaped light bar 15 with respect to the recording medium 2 by the coloring station 10 with respect to the medium conveyance direction Y is the same as the scanning angle of the laser beam 21a with respect to the recording medium 2 by the decoloring station 20 with respect to the medium conveyance direction Y. Is set to

  However, when the allowable range of the erasable temperature condition and the temperature change speed condition is large, the line exposure direction X in the coloring station 10 and the line exposure direction X in the erasing station 30 are slightly different angles, for example, the angle θ. Then, tan θ = 1/1000 may be set.

Here, the width of each exposure by the coloring station 10 and the decoloring station 20 is usually as follows:
Width W0 of recording medium 2> effective decoloring width W2> effective color developing width W1
It is set so that
Further, the exposure width with respect to the medium transport direction Y by the coloring station 10 and the erasing station 20 is as follows.
Length L0 of recording medium 2> effective decoloring length L2> effective color developing length L1
The exposure timings of the coloring station 10 and the erasing station 20 are set so that the above relationship is established.

  The coloring station 10 and the erasing station 20 operate in the same manner as described above on an unused portion in the recording medium 2 where data such as an image is not recorded. That is, the coloring station 10 heats the recording medium 2 to a colorable temperature zone K, and uniformly cools the recording medium 2 by cooling after the heating.

  The decoloring station 20 is such that the temperature of the recording medium 2 that is uniformly colored by the coloring station 10 is within the decolorable temperature band S or outside the decolorable temperature band S and lower than the lower limit temperature of the decolorable temperature band S. When the temperature falls to any one of the temperature ranges lower than the predetermined temperature, the recording medium 2 is heated to erase the recording medium 2 like an image. When the exposure positions of the coloring station 10 and the erasing station 20 move, or when the whole of the coloring station 10 and the erasing station 20 move, the recording medium 2 can be fixed. In this case, the recording medium transport apparatus 1 is not necessary.

  The interval between the coloring station 10 and the erasing station 20 is such that at least the conveyance speed of the recording medium 2 by the conveyance mechanism and the temperature of the recording medium 2 are heated to the color development possible temperature range by the color development station 10 and the color erasable temperature range. It is set based on the time required for the temperature to fall to any one of the temperature bands within S or outside the decolorable temperature band S and within a temperature band lower than the lower limit temperature of the decolorizable temperature band S by a predetermined temperature.

Next, a specific configuration of the coloring station 10 will be described.
The coloring station 10 includes a halogen lamp 11 that emits infrared rays (hereinafter simply referred to as light rays) as a light source. In the halogen lamp 11, a filament 12 is provided in a glass tube, and a reflective film 13 is formed on the outside of the glass tube. The length of the halogen lamp 11 is set longer than the effective color development width W1. Thus, the halogen lamp 11 is set so that the light intensity distribution of the filament 12 is slightly stronger at both ends so that the surface of the recording medium 2 has a uniform light intensity distribution over the entire effective color development width W1. The reflective film 13 reflects light rays traveling in the opposite direction to the recording medium 2 out of the light rays emitted from the filament 12, and increases the utilization efficiency of the light rays emitted from the filament 12.

  A condensing optical system 14 for a halogen lamp is provided on the optical path of the light beam emitted from the halogen lamp 11. The halogen lamp condensing optical system 14 includes a plurality of optical lenses. The condensing optical system 14 for halogen lamp focuses the light beam emitted from the halogen lamp 11 on the recording medium 2 by a lens, and forms it on a linear light bar 15 having a narrow width in the medium transport direction Y for recording. Line exposure is performed on the medium 2.

  The light bar 15 is absorbed by the light absorption heat conversion material contained in the recording medium 2 and converted into heat, generates a temperature condition necessary for color development, and colors the reversible thermosensitive recording material contained in the recording medium 2. . For this color development, it is necessary to satisfy a predetermined range of cooling rate. In the present embodiment, since the temperature of the portion exposed by the light bar 15 in the recording medium 2 is higher than the surroundings, the heat transfer inside the recording medium 2 and the outside air from the recording medium 2 to the recording medium conveying device 1 are performed. Natural cooling by heat transfer satisfies the cooling rate necessary for color development and is used as a cooling process.

  For example, when an image having a width of 100 mm is formed at a conveyance speed of the recording medium 2 of about 76 mm / sec, the halogen lamp 11 outputs an exposure length 0 in the medium conveyance direction Y of the optical bar 15 on the surface of the recording medium 2. The light intensity of the light bar 15 of about 25 to 30 W with respect to 125 mm is required as the maximum value. At this time, the halogen lamp 11 requires power consumption of about 250 to 500 W, for example. This value is about 10 larger than the light intensity of about 25 to 30 W on the surface of the recording medium 2, but the wavelength distribution of the halogen lamp 11 is wide, and there are few regions that coincide with the absorption wavelength of the light-absorbing heat conversion material. This is because the concentration of light energy is weak because it is not coherent like light.

  The spectral distribution of the halogen lamp 11 has a peak around 0.8 to 1.0 μm in the near infrared region, and has a wide intensity distribution on the long wavelength side. On the other hand, since the input power source of the halogen lamp 11 can be used without converting the 100 VAC power source into a direct current, a direct current power source or the like is not required, and a high-performance cooling device necessary for a high-power laser is not necessary. As a result, the total power consumption of the halogen lamp 11 is not much different from that of a high-power laser. Accordingly, the halogen lamp 11 is much cheaper than a laser light source even at about 500 to 1000 W, including low cost.

  The light beam emitted from the filament 12 is condensed by the reflective film 13 and the condensing optical system 14 for the halogen lamp. Condensation of the light beam emitted from the filament 12 can be performed by a known mirror such as a paraboloid or an ellipsoid, or a combination of these mirrors and lenses.

  When the diameter of the filament 12 is, for example, about 1 mm and the image forming speed, that is, the medium transport speed is about 76 mm / sec, the exposure length of the light bar 15 in the medium transport direction Y is desirably 1 mm or less, and the light is condensed. The lateral magnification of the optical system 14 is set to 1 or less. The value of the exposure length of the optical bar 15 in the medium conveyance direction Y is set in relation to not only the medium conveyance speed but also the light intensity of the optical bar 15, the specific heat of the recording medium 2, the thermal conductivity ambient temperature, and the like. When the exposure length of the light bar 15 in the medium transport direction Y exceeds 1 mm and the exposure time is long, heat moves from the exposed portion to the entire recording medium 2, and natural cooling may not provide a cooling rate necessary for color development. is there. At that time, forced cooling means is used. The slits are provided to prevent exposure from the surroundings and the like, and to secure the exposure length of the light bar 15 in the medium transport direction Y.

  The temperature adjustment of the recording medium 2 will be described. The temperature when the recording medium 2 comes to the exposure position of the coloring station 20 differs depending on the use environment and the storage environment. Since the color development temperature range can be considerably wide, for example, 160 to 240 ° C., the temperature variation of the recording medium 2 can be dealt with in a fairly wide range. However, if the usage environment is extremely low temperature or intense temperature cycle, the temperature of the recording medium 2 and the temperature of the surrounding environment are measured by the temperature sensor, and the light quantity of the halogen lamp 11 is determined according to the measured temperature. It becomes necessary to control. In addition, a heater or the like may be incorporated in the recording medium conveying apparatus 1 and the recording medium 2 may be heated by the heater or the like to keep the temperature of the recording medium 2 constant.

A specific configuration of the erasing station 20 will be described.
The erasing station 20 includes a semiconductor laser 21 as a light source. The semiconductor laser 21 emits a laser beam 21a. On the optical path of the laser beam 21a emitted from the semiconductor laser 21, a laser condensing optical system 22 and a polygon mirror 23 are provided. The laser condensing optical system 22 includes a plurality of optical lenses. The laser beam 21a emitted from the decoloring station 20 is focused on the recording medium 2 by the laser condensing optical system 22, and is irradiated onto the recording medium 2 as a laser beam 21a having a predetermined diameter. The medium 2 is exposed. The polygon mirror 23 is provided with a polygon motor 24. The polygon mirror 23 rotates at a constant rotational speed by driving the motor 24. Thereby, the laser beam 21a is scanned on the surface of the recording medium 2.

  An effective decoloring width W2 is set within the scanning width of the laser beam 21a. The effective decoloring width W2 is longer than the effective color developing width W1. The light intensity of the laser beam 21a is controlled so that the light intensity becomes uniform on the surface of the recording medium 2 over the entire width of the effective decoloring width W2 when the entire surface of the recording medium 2 is decolored. Alternatively, the light emission time of the laser beam 21a is controlled so that the light intensity becomes uniform on the surface of the recording medium 2 over the entire width of the effective decoloring width W2 when the entire surface of the recording medium 2 is decolored.

  The light emission control of the semiconductor laser 21 is performed alone or in combination such as ON / OFF control according to an image signal including data such as an image, modulation control of the ON / OFF time width, or modulation control of the output light intensity of the laser beam 21a. Done. As a result, in the uniform color image 2b, the portion corresponding to the background portion of the image is erased and rewritten to the recorded image 2c.

  The laser beam 21a is absorbed by the light-absorbing heat conversion material contained in the recording medium 2 and converted into heat, thereby generating a temperature condition necessary for decoloring. The reversible thermosensitive recording material contained in the recording medium 2 Discolor. The temperature of the recording medium 2 irradiated with the laser beam 21a by the erasing station 20 is higher than the initial temperature of the recording medium 2 irradiated with the light bar 15 by the coloring station 10, and the erasable temperature band of the recording medium 2 It is set near the lower limit of S. That is, after heating by the coloring station 10, the laser beam 21 a is irradiated by the decoloring station 20 before the recording medium 2 colored by being cooled at a predetermined cooling rate is not completely cooled down.

  However, the positional relationship in the medium transport direction Y between the coloring station 10 and the erasing station 20 is such that the recording medium 2 that has been colored by being cooled at a predetermined cooling rate after being heated by the coloring station 10 is not completely cooled. The color station 20 is set to satisfy the condition that the laser beam 21a is irradiated. At this time, when erasing the colored portion of the recording medium 2, heating is started by the laser beam 25, the temperature rise curve is made to enter the erasable temperature zone S from the low temperature side, and then the surroundings of the recording medium 2 are Therefore, it is sufficient to apply the thermal energy that moves due to the temperature difference to the laser beam 25 for a short time. Accordingly, the amount of heat energy required for erasing at the erasing station 20 is only a small amount compared to the case of heating from the initial temperature, so that the semiconductor laser 21 having an inexpensive and relatively low output is sufficient.

  Next, the semiconductor laser 21 emits a laser beam 21a having a wavelength of 808 nm or 830 nm, for example. The output of the laser beam 21a emitted from the semiconductor laser 21 is, for example, scanned by a polygon mirror 23, the utilization efficiency of the laser beam 21a is 50%, and data such as an image having a width of 100 mm is recorded on a recording medium of about 76 mm / sec. In the case of negative image formation in which image formation is performed by decoloring at a conveyance speed of 2, if the pixel size is 0.125 mm × 0.125 mm, a light intensity of about 2 to 3 W on the recording medium 2 surface is required. Become. This value is 1/10 or less compared to the case of positive image formation in which an image is formed by color development.

  Furthermore, if the temperature of the recording medium 2 immediately before the irradiation of the laser beam 21a, that is, the decoloring heating start temperature is set near the lower limit of the decolorable temperature band S, for example, a temperature difference of 1 to 5 ° C., the recording medium 2 under favorable conditions. The light intensity on the surface can be reduced to about 0.2 to 0.3 W. As a result, a photothermal conversion type image rewriting apparatus using an inexpensive low-power semiconductor laser 21 instead of a YAG laser or a C02 laser becomes possible.

  Next, the condensing optical system / scanning system will be described. The laser beam 21 a emitted from the semiconductor laser 21 passes through the condensing optical system 22, is reflected by the polygon mirror 23, and is focused on the recording medium 2. The polygon mirror 23 is rotated at a predetermined speed by driving the polygon motor 24, and scans the recording medium 2 while changing the reflection angle of the laser beam 21 a emitted from the semiconductor laser 21.

The size and shape of the laser beam 21a on the recording medium 2 vary depending on the decolorization sensitivity with respect to the light intensity of the laser beam 21a of the recording medium 2. For example, the pixel size is 0.125 mm × 0.125 mm, If the beam diameter is 1 / e ² of the light intensity at the center of the laser beam 21a, the beam diameter of the laser beam 21a in the case of a circle is, for example, about 0.125 to 0.180 mm on the surface of the recording medium 2. The beam diameter of the laser beam 21a in the case of an ellipse is, for example, about 0.04 to 0.09 mm in the line exposure direction X, and is about 0.130 to 0.180 mm in the medium conveyance direction Y, for example.

  When a plurality of laser light sources such as the semiconductor laser 21 are used, for example, a combination pattern of various laser light beams such as overlapping of laser light beams and temperature distribution due to heat conduction as disclosed in Patent Document 1 is used. Is possible. Such a condensing / scanning system in Patent Document 1 is simple, but when applied to the present embodiment, since the surface of the recording medium 2 is a flat surface, as is well known, from the reflection point of the polygon mirror 23. The distance to the exposure point of the laser beam 25 on the recording medium 2 varies depending on the rotation angle of the polygon mirror 23. For this reason, the diameter of the laser beam 25 in the line exposure direction X increases as the distance from the center to the periphery of the recording medium 2 with respect to the line exposure direction X increases, and the scanning speed increases, and the unit area on the recording medium 2 increases. The hit light intensity is not uniform.

  On the other hand, in the present embodiment, several well-known methods can be used in addition to the method of modulating the laser beam 21a output from the semiconductor laser 21 to obtain a uniform light intensity per unit area. For example, an fθ lens is inserted in the optical path between the polygon mirror 23 and the recording medium 2. There is a method in which the recording medium 2 is curved about the reflection point of the polygon mirror 23 and the distance from the reflection point of the polygon mirror 23 to the exposure point of the laser beam 21a on the recording medium 2 is constant.

Next, an operation of rewriting data such as an image by the apparatus configured as described above will be described.
The rewriting of data such as an image is performed by heating the recording medium 2 to a color development possible temperature range, and cooling the heated recording medium 2 to uniformly color the recording medium 2 and the uniformly colored recording medium 2. When the temperature falls to one of the temperature range within the decolorable temperature range S or outside the decolorable temperature range S and within a temperature range lower than the lower limit temperature of the decolorable temperature range S by a predetermined temperature. And a color erasing step for erasing the recording medium 2 like an image.

  4 to 6 are diagrams showing the relationship between temperature / density and time based on the characteristics of the recording medium 2 in the flow from the coloring process to the erasing process. Each of the relationship diagrams of temperature, concentration, and time in FIGS. 4 to 6 represents the time change of temperature and concentration in the reversible thermosensitive recording layer 2-2 mixed with the light absorption heat conversion material of the recording medium 2, respectively. The right vertical axis represents temperature, the left vertical axis represents concentration, and the horizontal axis represents time. Further, the numerical values such as temperature, density, and time exemplified are, for example, a case where an image having a width of 100 mm is transported at a recording medium 2 of about 76 mm / sec and a pixel size is about 0.125 mm × 0.125 mm, for example. Image formation.

  This condition includes the light bar 15, the shape and light intensity pattern of the laser beam 21a, the color development / decoloration sensitivity with respect to the light intensity of the laser beam 21a applied to the recording medium 2, and the heat in and around the recording medium 2. Since it varies depending on the conductivity, thermal conductivity, specific heat, etc., it is not necessarily limited to the numerical values.

First, the coloring process will be described.
Temperature curve _{Tc 0 -Tc 1 -Tc 2 -Tc 3} -Tc 4 -Tc 6 in FIG. 4, the temperature - shows the time curve. A concentration curve Dc ₀ -Dc ₃ -Dc ₄ -Dc ₆ shows a concentration-time curve. The density indicates the reflection density.
It is an initial state.
As an initial state, the recording medium 2 is in a state where the temperature T ₀ (25 ° C.) = Tc ₀ which is room temperature and the density D ₀ (0.2 to 0.3) = Dc _{0 in} the decolored state.

Next, it is a pre-coloring heating step.
A recording medium 2 is placed on the recording medium conveying apparatus 1. The recording medium transport apparatus 1 transports the recording medium 2 in the medium transport direction Y at a constant speed.
In the coloring station 10, when the halogen lamp 11 emits a light beam, the light beam including the light beam reflected by the reflecting film 13 enters the condensing optical system 14 for the halogen lamp. The condensing optical system 14 for halogen lamp focuses the light beam emitted from the halogen lamp 11 on the recording medium 2 by a lens, and forms it on a linear light bar 15 having a narrow width in the medium transport direction Y for recording. Line exposure is performed on the medium 2.

However, when the recording medium 2 enters the exposure position of the light bar 15 irradiated on the surface of the recording medium 2 from the coloring station 10, a pre-coloring heating process is performed. That is, when the recording medium 2 is exposed by the light bar 15, the color development possible temperature corresponding to the melting temperature of the composition comprising the leuco dye and the reversible developer in the recording medium 2, or the melting temperature of either component, etc. Passes Tc ₁ = Tm (180 ° C.). Then, the temperature of the recording medium 2 rises to the peak temperature Tc ₂ (200 ° C.) via the temperature curve Tc ₀ -Tc ₁ -Tc ₂ .

The color development temperature of the recording medium 2 has an upper limit, and is set by the thermal decomposition temperature of each material of the reversible thermosensitive recording layer 2-2. The color development possible temperature of the recording medium 2 is outside the temperature rise range shown in FIG. For example, the time required for the pre-coloring heating process between the temperature curves Tc ₀ -Tc ₁ -Tc ₂ , that is, the exposure time at the coloring station 10 is, for example, that the exposure length of the light bar 15 in the medium transport direction Y is about 1.25 mm. Then, it is about 15-30 msec. Preferably, by changing the setting of the condensing optical system 14 for the halogen lamp, the exposure length of the light bar 15 in the medium transport direction Y is set to about 0.125 mm, for example. In an actual apparatus, an intermediate value of about 15 to 30 msec is selected as the exposure time at the color forming station 10.

  Further, the energy required to develop an area corresponding to one pixel is, for example, about 60 to 600 μJ. This energy value is related to the light absorption of the light absorption heat conversion material of the reversible thermosensitive recording layer 2-2 and the heat transfer characteristics of the entire recording medium 2. The light intensity is about 40 to 50 W on the surface of the recording medium 2 with respect to the light absorption wavelength of the recording medium 2.

Next, a color development cooling step.
Since the recording medium 2 is conveyed by the recording medium conveying apparatus 1 in the medium conveying direction Y, the recording medium 2 deviates from the exposure position of the light bar 15 irradiated from the coloring station 10 and becomes a coloring cooling process. In this color the cooling step, the temperature of the recording medium 2 by natural cooling is lowered to a temperature _Tc 4 (150 ℃) as shown in a temperature curve _{Tc 2 -Tc 3 (180 ℃)} -Tc 4 (150 ℃). At this time, the cooling rate is set to be, for example, −100 to −200 ° C./sec or more.
The density changes to the density Dc ₄ indicated by the density curve Dc ₃ -Dc ₄ by this color cooling process. At the density Dc ₃ , the minimum density Dc ₀ = D ₀ (0.2 to 0.3), and at the density Dc ₄ , the color is developed up to the maximum density D ₁ (1.0 to 1.2). The concentration change curve shown in the concentration curve Dc ₃ -Dc ₄ at this time depends on the combination of the leuco dye and the reversible developer. Figure 4 definitive color at the start of the concentration Dc ₃ corresponds to the temperature Tc ₃ temperature, for example, Patent Document 7 discloses a case of coloring from the temperature Tc _1. In any case, a predetermined cooling rate is required to maintain the color development state at room temperature (25 ° C.). This apparatus is not limited to the color development start conditions.

Next, it is a post-cooling step.
The recording medium transport apparatus 1 transports the recording medium 2 in the medium transport direction Y at a constant speed. As a result, the recording medium 2 passes through the coloring station 10, is conveyed toward the erasing station 20, reaches the erasing station 20, and further passes through the erasing station 20. At this time, the recording medium 2 is not started to be exposed by the laser beam 21a to the color maintaining portion for image rewriting, and the color developing state is maintained and the post cooling process is performed. Due to natural cooling, the temperature of the recording medium 2 drops to a temperature Tc ₆ (30 ° C.) as shown by a temperature curve Tc ₄ -Tc ₆ . Thus, concentration, maximum density _D 1 (1.0 to 1.2) is maintained until the concentration Dc _6, post-cooling process is completed. Preferably, in order to increase the utilization efficiency of the apparatus, the post-cooling step is performed at a temperature of 40 to 60 ° C. without cooling to the temperature Tc6 ₆ (30 ° C.), without causing the user to burn, and at which the recording medium 2 is not thermally deformed. finish.

Next, the low energy decoloring step will be described with reference to FIG.
FIG. 5 is a diagram showing the relationship between the temperature / density and time based on the characteristics of the recording medium in the flow from the coloring process to the erasing process by the apparatus. In the figure, a temperature curve Tc ₀ -Tc ₁ -Tc ₂ -Tc ₃ -Tc ₄ -Tc ₅ -Te ₁ -Te ₂ -Te ₃ -Te ₄ shows a temperature-one hour curve. The concentration curve Dc ₀ -Dc ₃ -Dc ₄ -De ₁ -De ₂ -De ₄ shows a concentration-time curve. The density indicates the reflection density. In FIG. 5, the color development process up to the temperature-time curve Tc ₀ -Tc ₁ -Tc ₂ -Tc ₃ -Tc ₄ and the density-time curve Dc ₀ -Dc ₃ -Dc _4, that is, the color development cooling process is shown in FIG. Since it is the same process as a process, the description is abbreviate | omitted.

First, it is a cooling process before decoloring.
Following the color cooling step, the recording medium 2 is naturally cooled to a temperature Tc ₅ (115 ° C.) indicated by a temperature curve Tc ₄ -Tc ₅ . The temperature Tc ₅ is close to the lower limit of the decolorable temperature zone S. The distance between the line exposure position at the coloring station 10 and the scanning exposure position of the laser beam 21a at the decoloring station 20 is constant at any part of the recording medium 2 so as to keep the temperature Tc ₅ constant. Accordingly, the cooling time is also constant under the condition that the conveyance speed of the recording medium 2 is constant.

In the present embodiment, the decoloring is not started in the range up to the temperature curve Tc ₄ -Tc ₅ (115 ° C.). The temperature curve Tc ₄ -Tc ₅ passes through the decolorable temperature band S (120 to 180 ° C.), but the decolorable temperature change rate is zero or more, and at this time, the temperature change rate is under cooling. Since it is less than zero, erasing is not started. Therefore, the colored state is maintained up to the temperature Tc ₄ = Tc ₅ = maximum density D ₁ (1.0 to 1.2). That is, erasing is started only within the erasable temperature range S (120 to 180 ° C.) and when the temperature rises.

Next, it is a heating process before decoloring.
The recording medium 2 reaches the decoloring station 20 by the transport operation of the recording medium transport apparatus 1. In the erasing station 20, the semiconductor laser 21 emits a laser beam 21a. The laser beam 21a emitted from the semiconductor laser 21 is focused on the recording medium 2 by the laser condensing optical system 22 and irradiated onto the recording medium 2 as a laser beam 21a having a predetermined diameter, and a polygon mirror. The surface of the recording medium 2 is scanned by rotation at a constant rotational speed of 23.

In this state, when the recording medium 2 enters the exposure position by the laser beam 21a emitted from the decoloring station 20, a pre-decoloring heating process is performed. When the recording medium 2 is exposed to the laser beam 12a, the temperature of the recording medium 2 rises to Te ₁ (120 ° C.) according to the temperature curve Tc ₅ -Te ₁ as shown in FIG. At this time, since the recording medium 2 has not reached the decolorable temperature band S (120 to 180 ° C.), decoloring is not started.

Next, it is a decoloring heating process.
The exposure on the recording medium 2 by the irradiation with the laser beam 12a is continued. The temperature of the recording medium 2 rises to a temperature Te ₂ (125 ° C.) as indicated by a temperature curve Te ₁ -Te ₂ . Here, the decoloring heating step is performed at the decolorization start temperature Te ₁ (120 ° C.) or higher, and the density changes to the density De _{2 as} shown in the density curve De ₁ -De ₂ . The density De ₁ is the highest density D ₁ (1 · 0 to 1.2), and the temperature Te ₂ is erased at the lowest density D ₀ (0.2 to 0.3).

The erasing pattern at this time is an image, and the background portion of data such as an image is erased and the image is rewritten. Preceding heating start temperature Tc ₅ in the decoloring preheating process of the process is close to the lower limit of the color erasable temperature zone S (120 to 180 ° C.), is set in a range of, for example, 90 to 130 ° C.. Accordingly, the erasing of the recording medium 2 is started slightly after the start of the pre-decoloring heating process.

The decoloring before the heating step and the decolorization heating step is a continuous process in a unit exposure time for one pixel by the laser beam 21a, are classified based on the decolorization initiation temperature Te ₁ of the recording medium 2. The total time required for the pre-decoloring heating step and the decoloring heating step between the temperature curves Tc ₅ -Te ₂ , that is, the total exposure time of the decoloring station 20 is, for example, about 1 to 1.3 μsec. In addition, the energy required to erase one pixel is, for example, about 2 to 5 μJ. This energy value is largely related to the setting of the decoloring heating start temperature, and is further related to the light absorption of the light absorption heat conversion material of the reversible thermosensitive recording layer 2-2 and the heat transfer characteristics of the entire recording medium 2. .

The light intensity of the laser beam 21a on the surface of the recording medium 2 is, for example, about 2 to 3 W. Thereby, data such as an image can be rewritten by the laser beam 21a having a small light intensity. Furthermore, when the decolorization heating start temperature, the shape of the laser beam 21a, the characteristics of the recording medium 2, and the like are optimized, the light intensity can be set to about 0.2 to 0.3 W, for example. In this case, the range of the rate of change of the color erasable temperature was set at about -20 ℃ ~0 ℃ / sec, further decoloring heating start temperature, the temperature Tc ₅ the decoloring possible temperature range S (120 to 180 ℃). At this time, if the temperature change rate satisfies the decolorable temperature change rate, the decoloration is started immediately. Thereby, the heating process before decoloring can be omitted. In particular, when the range of the temperature erasable change rate is a temperature drop gradient such as −20 ° C./sec, the temperature Tc ₅ is set in the range of 125 to 140 ° C. The pre-color heating step can be omitted.

Next, it is a post-cooling step.
The recording medium 2 passes through the erasing station 20 and leaves the erasing station 20 by the conveying operation of the recording medium conveying apparatus 1. As a result, the recording medium 2 is removed from the exposure position by the light bar 15 emitted from the decoloring station 20, and the post-cooling process is performed. Thereafter, in the cooling step, the temperature of the recording medium 2 is lowered to Te ₂ -Te ₃ (120 ° C.)-Te ₄ (40 ° C.) as shown in the temperature curve by natural cooling.

At this time, the temperature change rate is not more than zero because it is being cooled, and erasing is not started. The concentration is kept at the minimum concentration D ₀ (0.2 to 0.3) until De ₄ and the post-cooling step is completed. Preferably, in order to increase the utilization efficiency of the apparatus, the cooling is not performed to the temperature Te ₄ (40 ° C.), the user is not burned, and the post-cooling is performed at a temperature of 40 to 60 ° C. at which the recording medium 2 is not thermally deformed. The process ends.

Next, a comparative example for rewriting data such as an image by this apparatus will be described.
This comparative example is a decoloring process with high energy. FIG. 6 shows a relationship diagram of temperature / concentration and time when the decoloring heating start temperature is set to near room temperature T ₀ (30 ° C.) as a comparative example. In this comparative example, the position of the decoloring station 20 is set with a sufficient interval from the coloring station 10, for example. That is, in the comparative example, the interval between the erasing station 20 and the coloring station 10 is set longer than the interval between the erasing station 20 and the coloring station 10 in this apparatus.

Curve _{Tc 0 -Tc 1 -Tc 2 -Tc 3} -Tc 4 -Te 0 -Te 1 -Te 2 -Te 3 -Te 4 6 temperature - a time curve. Curve _{Dc 0 -Dc 3 -Dc 4 -De 0} -De 1 -De 2 -De 4 is at a concentration one hour curve. The density indicates the reflection density. The color development process up to the temperature-time curve Tc ₀ -Tc ₁ -Tc ₂ -Tc ₃ -Tc ₄ and the density-time curve Dc ₀ -Dc ₃ -Dc _4, that is, the color development cooling process is the same as the above process, so the explanation is as follows. Omitted.

First, it is a heating process before decoloring.
When the decoloring heating start temperature is set to Te ₀ (35 ° C.) near room temperature, the recording medium 2 enters the exposure position by the laser beam 21 a output from the decoloring station 20, thereby performing the pre-decoloring heating process. When the recording medium 2 is exposed by irradiation of laser beam 21a, the temperature rises to _Te 1 (120 ℃) as shown in a temperature curve _Te 0 -Te _1. At this time, since the recording medium 2 has not yet reached the erasable temperature range S (180 to 120 ° C.), erasing is not started.

Next, it is a decoloring heating process.
Exposure by the laser beam 21a continues, and the temperature of the recording medium 1 rises to Te ₂ (125 ° C.) as shown by a temperature curve Te ₁ -Te ₂ . Here, the decoloring heating step is performed at the decolorization start temperature Te ₁ (120 ° C.) or higher, and the density changes to the density De _{2 as} shown in the density curve De ₁ -De ₂ . The temperature Te ₁ is the highest density D ₁ (1.0 to 1.2), and the temperature Te ₂ is erased at the lowest density D ₀ (0.2 to 0.3). The erasing pattern at this time is image-like, and the data such as the image is rewritten by erasing the background portion of the data such as the image.

The time required for the pre-decoloring heating step and the decoloring heating step between the temperature curves Te _{0 to} Te ₂ , that is, the total exposure time of the decoloring station 20 is, for example, about 1 to 1.3 μsec. The energy required to erase one pixel is, for example, about 20 to 40 μJ. The light intensity of the laser beam 21a is, for example, about 15 to 20 W. Therefore, if the scanning condition of the laser beam 21a is made constant and the total required exposure time is the same as that of this apparatus, when the decoloring heating start temperature is about room temperature, it is close to the lower limit of the decolorable temperature band as in this apparatus. The energy of about 10 in the case of the set low energy decoloring process is required. For this reason, a comparative example turns into a high energy decoloring process.

Next, it is a post-cooling step.
The recording medium 2 is removed from the exposure position by the laser beam 21 a emitted from the decoloring station 20 and is subjected to a post-cooling process. Natural temperature of the recording medium 2 by the cooling is lowered to _Te 4 (40 ℃) as shown in a temperature curve _{Te 2 -Te 3 (120 ℃)} -Te 4 (40 ℃). At this time, the temperature change rate is not more than zero because it is being cooled, and erasing is not started. The minimum concentration D ₀ (0.2 to 0.3) is maintained until the temperature DTe ₄ , and the post-cooling process ends. Thus, the post-cooling step is the same as the low energy decoloring step.

Next, a modification of the first embodiment will be described.

When the conveyance speed of the recording medium 1 is high, the halogen lamp 11 used as the light source of the coloring station 10 cannot be turned on / off at a high speed corresponding to the conveyance speed.

Therefore, the relationship with respect to the medium transport direction Y used by known thermal printers, laser beam printers, inkjet printers, etc.
Recording medium length> Effective image length
In order to establish the above, a shutter or the like for turning on / off the light bar 15 at high speed is required.

As a simple device,
Recording medium length L ₀ <effective color developing length L ₁ <effective decoloring length L ₂
The exposure timings by the coloring station 10 and the erasing station 20 are set so that the above relationship is established. That is, color development and decolorization are possible up to both end portions with respect to the medium conveyance direction Y of the recording medium 2. However, the range in which the image quality is guaranteed may be shorter than the length L ₀ of the recording medium 2.

  The coloring station 10 irradiates the recording medium 2 with the light bar 15 formed in a line shape from the light emitted from the halogen lamp 11 to heat the recording medium. You may use the contact heating means to heat. Since this apparatus is intended to reduce the output of, for example, the semiconductor laser 21 as a light source in the decoloring station 20, a contact heating means can be used in the coloring station 10. For example, a movable endless heat-resistant film made of polyimide having a built-in halogen lamp 11 and having a surface coated with a fluororesin or an aluminum heat roller or a heating resistor and having a surface coated with a fluororesin Etc. can be used. Since these heat roller and endless heat-resistant film rotate or move, the speed difference from the surface of the recording medium 2 is zero. Thereby, there is no rubbing as in the case of heating with a thermal head, for example, and the damage to the surface of the recording medium 2 is much smaller than in the case of heating with the thermal head.

  Further, as the coloring heating means in the decoloring station 20, a semiconductor laser or a high-intensity LED arranged in an array, an electric resistor that emits infrared rays, a high-frequency heating device, or the like can be used. As a result, the life of the recording medium 2 can be extended without damaging the recording medium 2 even if rewriting of data such as images on the recording medium 2 is repeated a plurality of times.

  As described above, according to the first embodiment, the recording medium 2 is heated to a color developable temperature band, and the recording medium 2 is uniformly colored by cooling after the heating, and then uniformly. When the color of the recording medium 2 that has developed color falls to either one of the temperature range within the decolorable temperature range or outside the decolorable temperature range and within the temperature range lower than the lower limit temperature of the decolorable temperature range, The recording medium 2 is heated to erase the recording medium 2 like an image. Thereby, it is possible to rewrite information such as an image on the recording medium 2 at a high speed and to record an image with a large angle of view by using an inexpensive and low-power semiconductor laser 21.

  Further, negative image formation can be realized by using the recording medium 2 having high-speed decoloring property. That is, conventionally, it has been known that the light energy required for image-like erasing is reduced when a negative image formation in which the recording medium 2 is uniformly colored and then erased like an image is adopted. For reversible thermosensitive recording media that do not have high-speed color erasability, there is no effective image-like color erasing method because high-speed color erasing cannot be performed. Therefore, an inexpensive and high-speed negative image forming apparatus is disclosed. Was not. On the other hand, this apparatus can realize low-speed and high-speed negative image formation by adopting the photothermal conversion type reversible thermosensitive recording medium 2 having high-speed decoloring property and further having a photothermal conversion function.

  An inexpensive and low-power semiconductor laser 21 is used as a light source for image formation, and the reversible thermosensitive recording medium 2 having high-speed decoloring property instantaneously shifts from a colored state to a decolored state by receiving and receiving less heat energy. By utilizing the characteristic that the decoloring heating start temperature is set close to the lower limit of the decolorable temperature band, it is possible to further reduce the output of the image-forming pattern forming light source.

  In the heating by the conventional thermal head, a larger input power is required as the image forming speed becomes faster. For this reason, even if the temperature of the entire thermal head rises and energization is turned off according to pulse control, as long as the recording medium 2 and the thermal head are in contact, the heat retained according to the heat capacity of the thermal head is recorded on the recording medium. 2 is transmitted forward in the conveyance direction, and the cooling rate of the recording medium 2 is reduced.

  On the other hand, in the heating method using the laser beam 21a as in the present apparatus, the color can be erased in a non-contact manner in a short heating time of, for example, about 1/1000 compared to a thermal head according to pulse control. A constant cooling rate is ensured. Thereby, according to this apparatus, since the decoloring heating start temperature is set close to the lower limit of the decolorable temperature range, a certain stable cooling rate is ensured, and image-like decoloring by non-contact heating is suitable. Become.

  It is possible to record an image with a large angle of view by forming a negative image. That is, the light intensity of the laser beam 21a has a Gaussian distribution. Since the decoloring temperature band of the recording medium 2 is lower than the coloring temperature band, the tail of the Gaussian distribution of the laser beam 21a is applied to the previous coloring area, and the color is erased even in the light intensity region where the bottom of the Gaussian distribution is small. There is a case. Alternatively, the previous color development region may satisfy the decoloring condition even in the heat conduction of the recording medium 2. For this reason, the previous image is erased due to the proximity of exposure, and it has been difficult to realize a solid image with a conventional device. On the other hand, this apparatus is a negative image formation, and since the image pattern is formed by decolorization, the previous image decoloration due to the proximity of exposure does not occur.

  In the first embodiment, the output of a light source such as the semiconductor laser 21 for image formation can be reduced, that is, the output and cost of the semiconductor laser 21 used for image-like erasing can be reduced. If a laser light source with a high output and high price is used, a high-speed image rewriting device that has been difficult to realize with a device using a conventional thermal head can be provided. For example, if a laser light source of about 2 to 3 W is used, an image having a width of 100 mm can be formed by decoloring at a medium conveyance speed of about 760 mm / sec. Alternatively, it is possible to provide an image rewriting device suitable for image formation with a large image width without increasing the medium conveyance speed so much.

Next, a second embodiment of the present invention will be described with reference to the drawings. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted.
FIG. 7 shows a basic configuration diagram of the image rewriting apparatus, and FIG. 8 shows a schematic perspective view of the apparatus.

As a specific example, it is assumed that an image having a width of 100 mm is formed with, for example, 0.125 mm × 0.125 mm pixels at a medium conveyance speed of, for example, about 380 mm / sec.

The coloring station 10 is basically the same as the coloring station 10 in the first embodiment, except that the condensing optical system 14 has an exposure length in the medium transport direction Y of, for example, 0.725 mm. It is a point changed to.

  In this change, the exposure length in the medium transport direction Y is set to 0.725 mm, which is 5 times the medium transport speed, and the heating required time before color development is 1.5 to 3 which is the same as that in the first embodiment. It is set to about 0.0 msec so that the same halogen lamp 11 with power consumption of about 250 to 500 W, for example, as in the first embodiment can be used. Further, when the exposure length in the medium transport direction Y is about 0.125 mm, the medium transport speed is simply five times that of the first embodiment, so that the output of the halogen lamp 11 is, for example, a power consumption of 1250 to 2500 W. A degree is required. However, the input power source of the halogen lamp 11 requires, for example, 144 to 250 VAC power source.

  A decoloring station (hereinafter referred to as a laser array module) 30 as a decoloring system is provided above the recording medium conveying apparatus 1 and downstream of the coloring station 10. The laser array module 30 includes a semiconductor laser array 31 and a laser array condensing optical system 32. The semiconductor laser array 31 is formed by arranging a plurality of semiconductor laser chips, for example, 800 semiconductor laser chips, that output a unit laser beam 33 having a wavelength of, for example, 808 mm or 830 mm as light energy. The semiconductor laser array 31 is arranged in the same direction as the line exposure direction X. The arrangement direction of the plurality of laser elements of the semiconductor laser array 31 is referred to as an array integration direction X.

  The laser array condensing optical system 32 shapes each unit laser beam 33 output from each laser element of the semiconductor laser array 31 into a line shape, and irradiates the recording medium 2 as the laser beam array 34. Each laser element of the semiconductor laser array 31 is individually driven by a laser ray driver 35.

  More specifically, the laser array module 30 has, for example, an image having a width of 100 mm and a pixel size of, for example, 0.125 mm × 0.125 mm, and arranges, for example, 800 unit laser beams 33 in the array integration direction X. A beam array 34 is formed. The laser beam array 34 can be individually controlled by the laser ray driver 35 as described above, and ON / OFF control, power modulation, and the like according to the pulse width are possible.

  The size and shape of one unit laser beam 33 on the surface of the recording medium 2 are as follows. For example, when the unit laser beam 33 is circular, the beam diameter is, for example, about 0.125 to 0.180 mm on the recording medium 2 surface. When the unit laser beam 33 is elliptical, the beam diameter is about 0.130 to 0.180 mm in the line exposure direction X and about 0.04 to 0.09 mm in the medium transport direction Y, for example.

The light intensity of one unit laser beam 33 on the surface of the recording medium 2 is required to be about 50 to 70 mW, for example. As a result, the entire laser array module 30 requires a light output of about 40 to 56 W, for example. When the semiconductor laser array 31 is driven by the laser array driver 35 in a known time-division drive, for example, the drive time of the unit laser beam 33 is set to one third, and conversely, the light intensity of one unit laser beam 33 is, for example, About 150 to 210 mW. Also at this time, 40 to 56 W of the optical output of the entire laser ray module 30 is maintained, and necessary energy per unit recording area is secured.
As in the first embodiment, if the decoloring heating start temperature is set near the lower limit of the decoloring temperature zone S, for example, a temperature difference of 1 to 5 ° C., the output of the unit laser beam 33 is, for example, under favorable conditions. It can be about 5 to 7 mW.

Next, an operation of rewriting data such as an image by the apparatus configured as described above will be described.
A recording medium 2 is placed on the recording medium conveying apparatus 1. The recording medium transport apparatus 1 transports the recording medium 2 in the medium transport direction Y at a constant speed.
In the coloring station 10, when the halogen lamp 11 emits a light beam as in the first embodiment, the light beam including the light beam reflected by the reflective film 13 enters the halogen lamp condensing optical system 14. . The condensing optical system 14 for halogen lamp focuses the light beam emitted from the halogen lamp 11 on the recording medium 2 by a lens, and forms it on a linear light bar 15 having a narrow width in the medium transport direction Y for recording. Line exposure is performed on the medium 2. Thus, the recording medium 2 is colored in a predetermined effective color width W ₁ of the total width. At this time, the pre-recorded image 2a recorded by the previous use of the recording medium 2 is formed as a uniform color image 2b.

  The recording medium transport apparatus 1 transports the recording medium 2 in the medium transport direction Y at a constant speed. As a result, the recording medium 2 passes through the coloring station 10, is conveyed toward the laser array module 30, reaches the laser array module 30, and further passes through the laser array module 30.

  The semiconductor laser array 31 in the laser array module 30 outputs a unit laser beam 33 having a wavelength of, for example, 808 mm or 830 mm from, for example, 800 semiconductor laser chips. The laser array condensing optical system 32 shapes each unit laser beam 33 output from each semiconductor laser chip of the semiconductor laser array 31 into a line shape, and irradiates the recording medium 2 as the laser beam array 34. The laser beam array 34 irradiates the recording medium 2 along the array integration direction X substantially perpendicular to the medium transport direction Y.

Thus, for a given effective Shoirohaba W ₂ on the recording medium 2, uniform coloring was necessary part of the recording medium 2 is decolorized imagewise. In other words, the uniform color image 2b on the recording medium 2 is formed in the current recording image 2c that is required by erasing the portion corresponding to the background portion of the data such as the image.

The change in temperature and density on the recording medium 2 from the color development step to the color erasing step in the present embodiment is the temperature shown in FIG. 5 used in the description of the color development step to the color erasing step in the first embodiment. Temperature-time curve Tc ₀ -Tc ₁ -Tc ₂ -Tc ₃ -Tc ₄ -Tc ₅ -Te ₁ -Te ₂ -Te ₃ -Te _{4 in the} concentration curve-time relationship diagram, and concentration-time curve Dc _{0- Dc 3 -Dc 4 -De 1 -De 2} -De 4 is basically the same. However, since the image forming speed is 5 times, the heating required time before color development between the temperature curves Tc ₀ -Tc ₁ -Tc ₂ is about 1/5 to about 3 to 6 msec. In addition, since the decoloring step is irradiation of the laser beam array 34 from the semiconductor laser array 31 fixedly arranged from the scanning of the laser beam 21a, the time required for the decoloring heating between the temperature curves Tc ₅ -Te ₂ is as follows. Under the condition that each semiconductor laser chip of the laser array 31 is not time-division driven, it becomes about 0.3 to 0.6 msec, for example.

Next, a modified sequence of the second embodiment will be described.
If the output of the unit laser beam 33 of the laser array module 30 is set to, for example, about 100 to 200 mW and the decoloring heating start temperature is set near the lower limit of the decoloring temperature band S in order to realize ultra high speed, for example, 760 to 1520 mm / Sec media transport speed (image forming speed) can be achieved. In this case, it is necessary to use a plurality of halogen lamps 11 in the coloring station 10 as well.

  Instead of the laser array module 30, a high brightness LED array module can be used. In such a high-intensity LED array module, if the medium conveyance speed (image formation speed) is set to about 76 mm / sec, for example, the output of the light source can be reduced, and the module using the high-intensity LED array can be used. It is. In this case, for example, an output of about 3 to 15 mW per unit beam 33 is required.

  As described above, according to the second embodiment, the laser array module 30 having the semiconductor laser array 31 and the laser array condensing optical system 32 is provided, and output from the plurality of semiconductor laser chips of the semiconductor laser array 31. A plurality of unit laser beams 33 are formed into a line shape by a laser array condensing optical system 32 and irradiated onto the recording medium 2 as a laser beam array 34. Thus, it goes without saying that the same effect as that of the first embodiment is obtained, and further, a medium conveyance speed (image formation speed) of about 380 mm / sec, which is five times that of the first embodiment, is obtained. Can be achieved. If the output of the plurality of unit laser beams 33 is made larger, the speed can be further increased.

  The output of the halogen lamp 1 in the coloring station 10 is insufficient to further increase the image forming speed for increasing the angle of view of the image rewriting device. Therefore, practically, an image rewriting device with a large angle of view is easier to realize than an increase in speed at an image width of 100 mm, for example, and an image forming area per unit time is increased. For example, when an image having a width of 300 mm is formed at a medium conveyance speed (image forming speed) of 380 mm / sec, a halogen lamp of, for example, 750 to 1500 W (power supply 100 to 120 VAC) is easily available. In this case, the image forming area per unit time is, for example, three times that when forming an image having a width of 100 mm. Further, the laser array module 30 is provided as a unit including 32: a laser array condensing optical system 32, a laser ray driver 35, and the like. Thereby, the laser array module 30 can be easily installed in an image rewriting device having a large image width.

Next, a third embodiment of the present invention will be described with reference to the drawings. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted.
FIG. 9 shows a basic configuration diagram of the image rewriting apparatus, and FIG. 10 shows a schematic perspective view of the apparatus. The recording medium 2 is stuck on the surface of the container 40 to which the recording medium 2 has been attached. The container 40 is transferred to a predetermined image forming position at the start of image formation by a transfer system (not shown), is positioned and installed, and is transferred from the image forming position to another position at the end of image formation.

A coloring / decoloring station 50 is disposed above the container 40 transferred at the start of image formation. The coloring / decoloring station 50 includes a first semiconductor laser 51 as a coloring system and a second semiconductor laser 52 as a erasing system.
The first semiconductor laser 51 outputs a first laser beam 51a for coloring. On the optical path of the first laser beam 51a output from the first semiconductor laser 51, a coloring laser condensing optical system 53 is disposed. The coloring laser condensing optical system 53 combines the first laser beam 51a output from the first semiconductor laser 51 on the recording medium 2 via a polarization beam splitter 54 and a two-dimensional scanning system 60 described later. The recording medium 2 is irradiated as a coloring laser beam 55 that is focused and has a predetermined diameter to expose the recording medium 2.

  The second semiconductor laser 52 outputs a second laser beam for erasing. On the optical path of the second laser beam 52a output from the second semiconductor laser 52, an erasing laser condensing optical system 56 is disposed. The decoloring laser condensing optical system 56 receives the second laser beam 52a output from the second semiconductor laser 52 on the recording medium 2 via a polarization beam splitter 54 and a two-dimensional scanning system 60 described later. The recording medium 2 is irradiated as a decoloring laser beam 57 which is focused and has a predetermined diameter, and the recording medium 2 is exposed.

  A polarization beam splitter 54 is provided on the intersection of the optical path of the first laser beam 51 a output from the first semiconductor laser 51 and the optical path of the second laser beam 52 a output from the second semiconductor laser 52. It has been.

Since the first laser beam 51a and the second laser beam 52a are linearly polarized light and orthogonal to each other, the polarization beam splitter 54 causes the first laser beam 51a and the second laser beam 52a to be separated at a predetermined interval. Synthesized.

The two-dimensional scanning system 60 scans the recording medium 2 with the first laser beam 51 a output from the first semiconductor laser 51 to uniformly color the recording medium 2, and the second semiconductor laser 52. The second laser beam 52a output from is scanned on the recording medium 2 to erase the recording medium 2 like an image.
The two-dimensional scanning system 60 includes a two-dimensional galvanometer mirror 61, a high-speed scanning rotary shaft 62, and a low-speed scanning rotary shaft 63. The two-dimensional scanning system 60 is independent in two rotational directions by a drive mechanism such as an electromagnetic drive coil (not shown). Vibrate. The high-speed scanning rotating shaft 62 rotates the two-dimensional galvanometer mirror 61 in the rotation direction ωx at high speed to scan the first laser beam 51a and the second laser beam 52a in the X direction at high speed. The low-speed scanning rotation shaft 63 rotates the two-dimensional galvanometer mirror 61 in the rotation direction ωy at a low speed to scan the first laser beam 51a and the second laser beam 52a in the Y direction at low speed. The two-dimensional galvanometer mirror 61 has a color developing laser beam 55 and a color erasing laser beam 57 in an effective image forming range on the recording medium 2 by a combination of two rotational movements of a high speed scanning rotary shaft 62 and a low speed scanning rotary shaft 63. And raster scan.

  In this case, the two-dimensional scanning system 60 scans the first laser beam 51 a onto the recording medium 2 before scanning the second laser beam 52 a onto the recording medium 2.

  However, after the two-dimensional scanning system 60 scans the recording medium 2 with the first laser beam 51a, the temperature of the recording medium 2 is within the decolorable temperature band S or the decolorable temperature as shown in FIG. The second laser beam 52a is scanned onto the recording medium 2 when the temperature falls to either one outside the band S and within a temperature band lower than the lower limit temperature of the decolorizable temperature band S by a predetermined temperature.

  Accordingly, the scanning position of the first laser beam 51a and the scanning position of the second laser beam 52a on the recording medium 2 are separated by an interval H in the low-speed scanning direction Y. This interval H is determined when the first laser beam 51a is scanned on the recording medium 2 and when the temperature of the recording medium 2 is within the decolorable temperature band S or outside the decolorable temperature band S as shown in FIG. And a time difference from the time when the second laser beam 52a is scanned onto the recording medium 2 after the temperature falls to one of the temperature ranges lower than the lower limit temperature of the decolorizable temperature zone S by a predetermined temperature. The first laser beam 51a and the second laser beam 52a are determined according to the scanning speed when scanning the recording medium 2 in the low-speed scanning direction Y.

  Specifically, the first semiconductor laser 51 in the coloring / decoloring station 50 outputs a first laser beam 51a having a wavelength of, for example, 808 mm or 830 mm, and has a light intensity of, for example, about 20 to 30 W on the surface of the recording medium 2. Have. On the other hand, the second semiconductor laser 52 outputs a second laser beam 52a having a wavelength of 808 mm or 830 mm, for example, and has a light intensity of, for example, about 0.2 to 0.3 W on the surface of the recording medium 2.

  The first laser beam 51 a and the second laser beam 52 a emitted from the polarization beam splitter 54 are reflected by the two-dimensional galvanometer mirror 61 and focused on the recording medium 2. At this time, the first laser beam 51a is formed in an elliptical shape, the beam diameter in the high speed scanning direction X is, for example, about 4 to 10 mm, and the beam diameter in the low speed scanning direction Y is, for example, about 0.130 to 0.180 mm. . On the other hand, the second laser beam 52a is formed in an elliptical shape, the beam diameter in the high speed scanning direction X is, for example, about 0.04 to 0.09 mm, and the beam system in the low speed scanning direction Y is, for example, 0.130 to 0.180 mm. Degree.

  The color developing laser beam 55 and the erasing laser beam 57 have the same center axis in the low speed scanning direction Y, and the center axis interval in the high speed scanning direction X, that is, the interval H is, for example, 0.25 mm apart for two pixels. . The high-speed scanning speed is about 62.5 m / sec, for example. The line formation period in the high-speed scanning direction X is, for example, about 3.3 msec. Accordingly, the low speed scanning speed is, for example, about 39 mm / sec. Therefore, the exposure time interval between the color developing laser beam 55 and the decoloring laser beam 57 is, for example, about 6.6 msec. As a result, the coloring laser beam 55 is at a position preceding the erasing laser beam 57 in the low-speed scanning direction Y by, for example, 0.25 mm for two pixels.

  As shown in FIGS. 9 and 10, in the two-dimensional scanning system 60 using the simple two-dimensional galvanometer mirror 61, the interval between the exposure times of the coloring laser beam 55 and the erasing laser beam 57 is not constant. In this case, an optical system using a known fθ lens or the like is added so that the scanning speed is constant. Further, known laser emission pulse width modulation, laser emission power modulation, etc. so that the temperature change rate of the recording medium 2 is constant even if the exposure time interval between the coloring laser beam 55 and the decoloring laser beam 57 is different. Is used to adjust the exposure energy of the coloring laser beam 55 and the erasing laser beam 57.

Next, a description will be given of how to increase the depth of focus of the coloring laser beam 55. Since the coloring station 10 in the first and second embodiments uses the halogen lamp 11 as a light source, the lateral magnification of the condensing optical system is set to 1 or less, so that the depth of focus cannot be increased. For this reason, for example, when the surface of the recording medium 2 has a large undulation, it is difficult to focus the light bar 15 on the recording medium 2.
On the other hand, in the third embodiment, the lateral magnification of the optical system can be set to, for example, about 10 with respect to the erasing laser light beam 57 in the low-speed scanning direction Y with respect to the coloring laser beam 55. Large focal depth can be obtained.

  When the lateral magnification of the optical system is, for example, about 10, the distance between the coloring laser condensing optical system 53 and the recording medium 2 and the distance between the erasing laser condensing optical system 56 and the recording medium 2 may be increased. it can. As a result, even when the recording medium 2 has a large angle of view, the two-dimensional scanning mirror 61 is placed at a predetermined distance from the surface of the recording medium 2 to enable two-dimensional scanning.

  Next, the coloring laser beam 55 will be described. The color development laser beam 55 can form a large exposure area. That is, the color developing laser beam 55 has a beam diameter in the high speed scanning direction X of about 4 to 10 mm, for example, and a beam system in the low speed scanning direction Y of about 0.130 to 0.180 mm, for example. Compared to 57, it has a large exposure area. Thereby, the color development laser beam 55 disperses the light intensity of 20 to 30 W, and the light intensity per unit area is about 10 times that of the color development laser beam 55. When a high-power laser beam is used, the light-absorbing heat conversion material and its surroundings reach 300 to 400 ° C or higher, and the light-absorbing heat conversion material and other reversible thermosensitive recording media are pyrolyzed and melted. Because there is a risk of doing.

  The coloring laser beam 55 can have a long exposure time. The exposure time of the coloring laser beam 55 is, for example, about 64 to 160 μsec, which is longer than the exposure time of the decoloring laser beam 57 of 2 to 2.6 μsec. This is because the color development laser beam 55 with sufficient light intensity is used, and the temperature of the entire recording medium 2 is raised within a required exposure time, so that it is not less than the lower limit of the color development temperature band K or the upper limit of the decolorization temperature band S. This is because it is necessary to maintain the temperature of the recording medium 2 after coloring.

With this setting, even if the gauss distribution tail part of the laser beam for color development 55 is reexposed, the reexposed part is above the lower limit of the color developable temperature band K or can be erased. Since the temperature is equal to or higher than the upper limit of the temperature band S, the color development area of the previous line is not erased by re-exposure.
As the first semiconductor laser 51, a multimode laser having a light output width of about 10 mm corresponding to a wide light output width of about 0.1 to 1 can be used. The first semiconductor laser 51 can cope with an exposure pattern having a long diameter.

  Next, an operation of rewriting data such as an image by the apparatus configured as described above will be described. Here, as a specific example, it is assumed that an image having a width of 100 mm is formed with, for example, pixels of 0.125 mm × 0.125 mm at a medium conveyance speed of, for example, about 38 mm / sec.

  The first semiconductor laser 51 in the coloring / decoloring station 50 outputs a first laser beam 51a for coloring. The first laser beam 51 a is incident on the two-dimensional scanning system 60 through the coloring laser condensing optical system 53 and the polarization beam splitter 54. At the same time, the second semiconductor laser 52 outputs a second laser beam 52a for erasing. The second laser beam 52 a enters the two-dimensional scanning system 60 through the erasing laser condensing optical system 56 and the polarization beam splitter 54.

  In the two-dimensional scanning system 60, the two-dimensional galvanometer mirror 61 is rotated at high speed in the rotation direction ωx by the high-speed scanning rotating shaft 62 to scan the first laser beam 51a and the second laser beam 52a in the X direction at high speed, At the same time, the two-dimensional galvanometer mirror 61 is rotated at a low speed in the rotation direction ωy by the low-speed scanning rotation shaft 63 to scan the first laser beam 51a and the second laser beam 52a at a low speed in the Y direction. As a result, the two-dimensional galvanometer mirror 61 has a color developing laser beam 55 and a color erasing function in an effective image forming range on the recording medium 2 by a combination of two rotational movements of the high speed scanning rotary shaft 62 and the low speed scanning rotary shaft 63. Raster scanning with the laser beam 57 is performed.

  In this two-dimensional raster scanning, for example, low-speed scanning in the Y direction is performed at a constant speed, and high-speed scanning in the X direction is performed at a constant speed or a speed distribution according to a sine curve. Assuming the The reason for adopting only the forward exposure in the high-speed scanning in the X direction is to make the temperature change speed of the recording medium 2 as constant as possible. When controlling the light output of the coloring laser beam 55 and the erasing laser beam 57, reciprocal exposure is also possible.

  In the two-dimensional raster scanning, the first laser beam 51 a output from the first semiconductor laser 51 is focused on the recording medium 2 by the color development laser condensing optical system 53. As a result, the first laser beam 51a is irradiated onto the recording medium 2 as a coloring laser beam 55 having a predetermined diameter, and the recording medium 2 is exposed. At the same time, the second laser beam 52 a output from the second semiconductor laser 52 is focused on the recording medium 2 by the decoloring laser focusing optical system 56. As a result, the second laser beam 52a is irradiated onto the recording medium 2 as a decolorizing laser beam 57 having a predetermined diameter to expose the recording medium 2.

That is, the two-dimensional scanning system 60 scans the recording medium 2 with the first laser beam 51a and then the temperature of the recording medium 2 is within the decolorable temperature band S or the decolorable temperature as shown in FIG. The second laser beam 52a is scanned on the recording medium 2 when the temperature falls outside the band S and falls within any one of the temperature bands lower than the lower limit temperature of the decolorizable temperature band S by a predetermined temperature.
However, the two-dimensional scanning system 60 scans the recording medium 2 with the first laser beam 51a output from the first semiconductor laser 51 as the coloring laser beam 55, and uniformly colors the recording medium 2. Thereafter, the second laser beam 52a output from the second semiconductor laser 52 is scanned on the recording medium 2 as a decoloring laser beam 57, and the recording medium 2 is erased like an image.

The change in temperature and density on the recording medium 2 from the color development step to the color erasing step in the present embodiment is the temperature shown in FIG. 5 used in the description of the color development step to the color erasing step in the first embodiment. Temperature-time curve Tc ₀ -Tc ₁ -Tc ₂ -Tc ₃ -Tc ₄ -Tc ₅ -Te ₁ -Te ₂ -Te ₃ -Te _{4 in the} concentration curve-time relationship diagram, and concentration-time curve Dc _{0- Dc 3 -Dc 4 -De 1 -De 2} -De 4 is basically the same. However, the time required for heating before color development between temperatures Tc ₀ -Tc ₁ -Tc ₂ corresponding to the change in the image forming speed is, for example, about 64 to 160 μsec. Further, the total time required for the pre-decoloring heating step and the decoloring heating step between the temperatures Tc _{5 and} Te ₂ is, for example, about 2 to 2.6 μsec.

  As described above, according to the third embodiment, the first semiconductor laser 51 as the coloring system and the second semiconductor laser 52 as the decoloring system are included, and the first two-dimensional scanning system 60 performs the first. The first laser beam 51 a output from the semiconductor laser 51 is scanned on the recording medium 2 to uniformly develop the recording medium 2 and the second laser beam output from the second semiconductor laser 52. 52a is scanned on the recording medium 2 to erase the recording medium 2 like an image. Thereby, it goes without saying that the same effect as that of the first embodiment can be obtained, and the following effect can be further obtained.

  It is possible to cope with the waviness of the surface of the recording medium 2. That is, in the third embodiment, since the lateral magnification of the optical system can be set to about 10, for example, a relatively large depth of focus can be obtained. Thereby, it is easy to focus on even a large surface undulation such as the recording medium 2 affixed to the surface of the container 40. Further, since the color developing and erasing light sources can be gathered in a compact manner, it is possible to add an autofocus function by controlling the positions of the color developing laser focusing optical system 53 and the erasing laser focusing optical system 56. It is easy and can cope with the larger waviness of the surface of the recording medium 2.

  It is possible to cope with the moving recording medium 2. That is, since the distance between the coloring laser condensing optical system 53 and the erasing laser condensing optical system 56 and the recording medium 2 can be increased, two-dimensional scanning with respect to the surface of the recording medium 2 is possible. . This allows the recording medium 2 attached to the surface of the moving container 40 to follow the moving speed of the container 40 with the speed of the two-dimensional scanning, and cope with the change in the distance from the reflection mirror with the autofocus function. By doing so, it is possible to rewrite data such as an image on the recording medium 2 while the container 40 is moved. This can revolutionize the use of this device in the logistics field.

  As the two-dimensional scanning system 60, for example, one using two one-dimensional galvanometer mirrors can be used.

Next, a fourth embodiment of the present invention will be described with reference to the drawings. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted.
FIG. 11 shows a basic configuration diagram of the image rewriting apparatus, and FIG. 12 shows a schematic perspective view of the apparatus. This apparatus includes a one-side cooling module 70 as a cooling system. The one-side cooling module 70 is used in the recording medium 2 in the color-cooling process with respect to the line-shaped heating means of the coloring station 10 in the first and second embodiments, particularly the uniform heating means using the halogen lamp 11 as a light source. It functions as a forced cooling means to complement the natural cooling of the heated part, and realizes more reliable color development. That is, the one-side cooling module 70 forcibly cools the portion of the recording medium 2 heated to the color development possible temperature band S by the coloring station 10. For example, cooling air 71 is used as a cooling medium for the recording medium 2. For example, one cooling nozzle 72 is provided.

  The cooling nozzle 72 is provided between the light bar 15 and the exposure position of the decoloring station 20 and at a predetermined interval from the light bar 15. The cooling nozzle 72 ejects cooling air 71 over the recording medium 2 over the entire width in the line exposure direction X, and controls the coloring cooling process following the heating process before coloring by the light bar 15 with forced cooling.

In addition, the one-side cooling module 70 also performs forced cooling for the decoloring and cooling advance process of the decoloring station 20 subsequent to the coloring cooling process, thereby realizing stable decoloring heating start temperature. In addition, the relationship of the line exposure direction X is determined by taking into account the spread of the air flow of the jetted cooling air 71 in the line exposure direction X and the heat conduction in the line exposure direction X.
Effective cooling width W ₃ > effective exposure width W ₁ = effective color development width W ₁
Is set to

  Specifically, in the one-side cooling module 70, an air supply pump 74 is connected to the cooling nozzle 72 via an air supply system pipe 73. The intake pump 74 takes in outside air directly from inside the apparatus in order to take in air as low as possible, pressurizes the taken-in air to a predetermined pressure, and passes through an air supply system pipe 73 as cooling air 71. The cooling nozzle 72 is supplied.

  The coloring station 10 is surrounded by a halogen lamp house 75. The halogen lamp house 75 has an upper end and a lower end opened. An exhaust fan 76 as a suction mechanism is provided at the upper end of the halogen lamp house 75. The exhaust fan 76 sucks the cooling air 71 ejected to the recording medium 2 and prevents the cooling air 71 from flowing directly into the heating portion of the recording medium 2 by the coloring station 10. Further, the exhaust fan 76 sucks the cooling air 71 ejected to the recording medium 2 through the coloring station 10 while cooling the coloring station 10.

  The airflow of the cooling air 71 ejected from the cooling nozzle 72 collides with the recording medium 2 after the pre-coloring heating process, forcibly cooling the recording medium 2. At this time, the airflow 77 of the cooling air 71 needs to reach the exposure site of the light bar 15 and not cool the exposure site. For this reason, the predetermined area from the vicinity of the cooling nozzle 72 to the exposed portion of the light bar 15 is in a negative pressure state from the ambient pressure by the exhaust fan 76. As a result, the airflow 77 of the cooling air 71 is sucked into the halogen lamp house 75 before reaching the exposure part of the light bar 15.

  The airflow 77 of the cooling air 71 flows from the lower end to the upper end in the halogen lamp house 75 to cool the halogen lamp condensing optical system 14 and the halogen lamp 11, and then the halogen lamp house 75 by the exhaust fan 76. Is discharged from the upper end of the apparatus to the outside of the apparatus.

  When an optical lens is used in the condensing optical system 14 for the halogen lamp, the temperature of the optical lens rises due to infrared radiation from the halogen lamp 11, and distortion occurs. The airflow 77 flowing in the halogen lamp house 75 prevents the temperature of the optical lens of the halogen lamp condensing optical system 14 from increasing, and maintains good condensing characteristics. Further, since the maximum operating temperature of the halogen lamp 11 is specified, the halogen lamp 11 is cooled by the airflow 77 flowing in the halogen lamp house 75. In order to secure the air inflow necessary for cooling the condensing optical system 14 for the halogen lamp and the halogen lamp 11, not only the cooling air 71 ejected from the cooling nozzle 72 but also from the outside and inside of the apparatus. The taken-in air can be taken into the halogen lamp house 75, for example.

  The cooling air 71 ejected from the cooling nozzle 72 can take more heat from the recording medium 2 as the temperature is lower. Thereby, the temperature of the cooling air 71 needs to be lowered. When the air sufficiently pressurized by the air supply pump 74 is ejected from the cooling nozzle 72, the temperature thereof is reduced by adiabatic expansion. In order to lower the temperature of the cooling air 71, for example, a path including an air supply system pipe 73 from the air supply pump 74 to the cooling nozzle 72, or air cooling using a known Peltier element on the outer wall of the cooling nozzle 72. Means can be used.

  Control of the cooling rate of the recording medium 2 by the one-side cooling module 70 is performed by changing values such as the opening amount of the cooling nozzle 72, the pressure in the cooling nozzle 72 by the air supply pump 74, the rotational speed of the exhaust fan 76, and the like. The control system of the apparatus measures, for example, the ambient temperature of the apparatus, the internal temperature of the apparatus, the surface temperature of the recording medium 2, and the like. The ambient temperature of the apparatus, the internal temperature of the apparatus, the surface of the recording medium 2 are measured. The values of the opening amount of the cooling nozzle 72, the pressure in the cooling nozzle 72 by the air supply pump 74, the rotational speed of the exhaust fan 76, and the like are automatically controlled according to changes in temperature and the like.

  On the other hand, in the recording medium 2, as shown in FIG. 3, the reversible thermosensitive recording layer 2-2 is the same as the reversible thermosensitive recording layer 2-2 in the first embodiment and has a low thermal conductivity. The body 2-1 is used. Alternatively, the recording medium 2 is formed by forming a heat insulating layer having a low thermal conductivity at the interface between the reversible thermosensitive recording layer 2-2 and the support 2-1. Thereby, the recording medium 2 can raise the reversible thermosensitive recording layer 2-2 to a temperature required for color development with a smaller exposure energy in the pre-coloring heating step. Such an adiabatic recording medium 2 has a small amount of heat transfer from the reversible thermosensitive recording layer 2-2 to the support 2-1 and cannot obtain a cooling rate necessary for color development by natural cooling.

  The forced cooling of the recording medium 2 by the one-side cooling module 70 is a method adopted because heat is transferred to the entire recording medium 2 in the pre-coloring heating step and the cooling rate necessary for color development cannot be obtained by natural cooling. is there. Therefore, if forced cooling by the one-side cooling module 70 is used for the heat-insulating recording medium 2, color development is possible with smaller exposure energy. As a result, the power consumption of the color heating source can be greatly reduced, or the image forming speed can be increased.

  Examples of the heat insulating layer that can be set at the interface between the support 2-1 having a low thermal conductivity and the reversible thermosensitive recording layer 2-2 and the support 2-1 include paper, various non-woven fabrics, foamed polyethylene terephthalate, A porous film made of a porous film (polyethylene, fluorine tree, cellulose acetate) or the like, or a laminate of polyethylene terephthalate, polypropylene or the like can be used.

Further, the protective layer 3-2 may be the one disclosed in the first embodiment, but the protective layer 3-2 is protected in order to reduce the heat capacity of the protective layer 3-2 itself and increase the amount of heat transfer. A layer 3-2 having a small thickness is selected.
In addition, in order to improve heat transfer with the cooling air 71 ejected from the cooling nozzle 72, there is a method of increasing the surface area by providing minute irregularities on the protective layer 3-2. In this case, the heat capacity and the amount of heat transfer are taken into consideration.

Next, a case where forced cooling by the one-side cooling module 70 is necessary will be described.
When the condensing optical system 14 for the halogen lamp with respect to the halogen lamp 11 is set to have a deep focal depth on the recording medium 2 of the light bar 15 of the color developing station 10 corresponding to the undulation of the recording medium 2, etc., or an inexpensive halogen When the condensing width of the light bar 15 is set wide using the condensing optical system 14 for the lamp, the exposure length of the light bar 15 in the medium transport direction Y exceeds 1 mm, and the exposure time in the pre-coloring heating process becomes longer. .

  In this case, heat is transferred from the exposed portion to the entire recording medium 2, and the cooling rate necessary for color development cannot be obtained by natural cooling. That is, when the exposure time in the pre-coloring heating step is increased, the entire support 2-1 in the recording medium 2 is heated, and the temperature difference between the reversible thermosensitive recording layer 2-2 and the support 2-1 is eliminated. . As a result, the natural cooling rate of the reversible thermosensitive recording layer 2-2 in the coloring cooling step does not satisfy the condition for the change in temperature at which the color develops.

  If the natural cooling rate at this time can ignore the heat conduction in the horizontal direction (plane direction) of the recording medium 2, the heat transfer from the surface of the protective layer 2-2 and the support 2-1 to the surrounding air layer dominates. Become. Since the support 2-1 is in contact with the recording medium conveyance device 1, it can be considered that an air layer exists at the interface between the support 2-1 and the recording medium conveyance device 1. The cooling rate in this state is considerably smaller than the state in which the entire support 2-1 is not heated.

  If the exposure time in the pre-coloring heating step can be increased, the output of the halogen lamp 11 of the coloring station 10 can be made smaller with respect to the same medium conveyance speed (image forming speed). For example, when an image having a width of 100 mm is formed at a medium conveyance speed of, for example, about 76 mm / sec, if the exposure length of the light bar 15 in the medium conveyance direction Y is 1.25 mm, the halogen lamp 11 has a power consumption of 25 to 25, for example. A thing of about 50W is sufficient.

Next, the operation of rewriting data such as an image by the apparatus configured as described above will be described in the difference from the first embodiment.
In the coloring station 10, when the halogen lamp 11 emits a light beam as in the first embodiment, the light beam including the light beam reflected by the reflective film 13 enters the halogen lamp condensing optical system 14. . The condensing optical system 14 for halogen lamp focuses the light beam emitted from the halogen lamp 11 on the recording medium 2 by a lens, and forms it on a linear light bar 15 having a narrow width in the medium transport direction Y for recording. Line exposure is performed on the medium 2. Thus, the recording medium 2 is colored in a predetermined effective color width W ₁ of the total width.

  In this state, the air supply pump 74 of the one-side cooling module 70 takes in the outside air directly from the outside of the apparatus, for example, pressurizes the taken-in air to a predetermined pressure, and cools the cooling nozzle through the air supply system pipe 73 as the cooling air 71. 72. The cooling nozzle 72 ejects cooling air 71 over the recording medium 2 over the entire width in the line exposure direction X, and controls the coloring cooling process following the pre-coloring heating process by the light bar 15 by forced cooling.

  On the other hand, the exhaust fan 76 sucks the cooling air 71 ejected to the recording medium 2 and prevents the cooling air 71 from flowing directly into the heating portion of the recording medium 2 by the coloring station 10. Further, the exhaust fan 76 sucks the cooling air 71 ejected to the recording medium 2 through the coloring station 10 while cooling the coloring station 10.

  However, the airflow of the cooling air 71 ejected from the cooling nozzle 72 collides with the recording medium 2 after the pre-coloring heating step, forcibly cooling the recording medium 2. The airflow 77 of the cooling air 71 flows from the lower end to the upper end in the halogen lamp house 75 to cool the halogen lamp condensing optical system 14 and the halogen lamp 11, and then the halogen lamp house 75 by the exhaust fan 76. Is discharged from the upper end of the apparatus to the outside of the apparatus.

The change in temperature and density on the recording medium 2 from the color development step to the color erasing step in the present embodiment is the temperature shown in FIG. 5 used in the description of the color development step to the color erasing step in the first embodiment. Temperature-time curve Tc ₀ -Tc ₁ -Tc ₂ -Tc ₃ -Tc ₄ -Tc ₅ -Te ₁ -Te ₂ -Te ₃ -Te _{4 in the} concentration curve-time relationship diagram, and concentration-time curve Dc _{0- Dc 3 -Dc 4 -De 1 -De 2} -De 4 is basically the same.

Note that the forced cooling by the one-side cooling module 70 acts on the temperature decrease shown in the temperature curve Tc ₂ -Tc ₃ -Tc ₄ (150 ° C.) from the maximum temperature, which is the color development cooling process. Further, the forced cooling by the one-side cooling module 70 is also effective for the decoloring cooling pre-treatment step Tc ₄ -Tc ₅ (115 ° C.). That is, the one-side cooling module 70 forcibly cools the portion of the recording medium 2 heated to the color development possible temperature band S by the coloring station 10 and complements the natural cooling of the portion of the recording medium 2 heated by the halogen lamp 11. And more reliable color development.

  As described above, according to the fourth embodiment, the one-side cooling module 70 for forcibly cooling the portion of the recording medium 2 heated to the color development possible temperature zone S by the color development station 10 is provided. Thereby, the natural cooling of the portion of the recording medium 2 heated by the halogen lamp 11 is complemented, and a reliable color development can be realized. Thereby, the long exposure time in the pre-coloring heating step can be accommodated, and the focal depth of the condensing optical system 14 for the halogen lamp of the coloring station 10 can be set deep. Alternatively, the output of the halogen lamp 11 can be made smaller with respect to the same medium conveyance speed (image forming speed).

The condition of the speed at which the color development temperature changes in the color development cooling step is an essential condition for color development. Further, the decoloring heating start temperature, which is the final temperature in the decoloring and cooling advance step, is an important point for lowering the output of the image forming light source or improving the image forming speed to be achieved by this apparatus. In this apparatus, the ambient temperature, the internal temperature of the apparatus, and the temperature of the recording medium 2 are values that can be easily converted depending on the use environment conditions. These temperature conditions and state values related to the temperature of the recording medium 2, such as specific heat, thermal conductivity thickness, surface area, etc., have a great influence on the coloring cooling process and the decoloring cooling advance process.
Therefore, if these temperatures are automatically measured, the cooling rate can be freely controlled by forced cooling by the one-side cooling module 70, and the coloration temperature change rate and the decoloring heating start temperature can always be kept optimal. The robustness of performance can be improved.

  If forced cooling is used for the adiabatic recording medium 2, color development is possible with smaller exposure energy, which can greatly contribute to the reduction of the power consumption of the color development heating source or the increase in the image forming speed. .

  Since the high-pressure cooling air 71 is ejected from the cooling nozzle 72 onto the recording medium 2, foreign matter adhering to the surface of the recording medium 2 due to static electricity or the like can be blown away by the ejected cooling air 71. As a result, the life of the recording medium 2 can be increased. Further, the light shielding by the foreign matter can be removed during the uniform exposure by the coloring station 10 and the image-like exposure by the decoloring station 20. Thereby, it can also contribute to the improvement of the image quality formed in the recording medium 2.

The fourth embodiment may be modified as follows.
The one-side cooling module 70 may be in contact with the recording medium 2. For example, as the contact type one-side cooling module 70, for example, a hollow cooling roller made of aluminum whose surface is coated with fluororesin, or a movable endless shape made of polyimide with a built-in cooling metal bar inside and coated with fluororesin on its surface It may be a heat resistant film or the like. These hollow cooling rollers or endless heat-resistant films are heated by the heat transfer from the recording medium 2. Thereby, since the heat of the heating part of the recording medium 2 moves to the hollow cooling roller or the endless heat-resistant film, the heating part of the recording medium 2 is cooled.

  The hollow cooling roller and the cooling metal bar itself are cooled by well-known cooling means such as natural cooling, well-known forced air cooling, water cooling, Peltier element, heat pump and the like. The hollow cooling roller and the endless heat-resistant film rotate or move to cool the heated portion of the recording medium 2. Thereby, the speed difference between the hollow cooling roller or the endless heat-resistant film and the surface of the recording medium 2 is zero, and the damage on the surface of the recording medium 2 is small.

  By the way, from the viewpoint of extending the life of rewriting data such as images on the recording medium 2, it is desirable that the line-like cooling by the coloring station 10 be performed in a non-contact manner. The line-like cooling by the coloring station 10 is effective with gas or liquid. When the recording medium transport apparatus 1 is required as in the first and second embodiments, a transport roller that contacts the surface of the recording medium 1 is required. In this case, it is preferable to adopt a method in which the contact cooling means that contacts and cools the recording medium 2 also serves as the recording medium transporting means so that damage to the surface of the recording medium 2 is minimized in the entire apparatus.

  The erasing station 20 may be either by scanning with the laser beam 21a in the first embodiment or by irradiation with the laser beam array 34 in the second embodiment.

Next, a fifth embodiment of the present invention will be described with reference to the drawings. The same parts as those in FIGS. 11 and 12 are denoted by the same reference numerals, and detailed description thereof is omitted.
FIG. 13 shows a basic configuration diagram of the image rewriting apparatus, and FIG. 14 shows a schematic perspective view of the apparatus. This apparatus includes a both-side cooling module 80 as a cooling system. This both-side cooling module 80 is used in the recording medium 2 in the color cooling process for the line heating means of the color forming station 10 in the first and second embodiments, particularly the uniform heating means using the halogen lamp 11 as a light source. Complements natural cooling of heated parts. Since the basic configuration of the both-side cooling module 80 is the same as that of the one-side cooling module 70 in the fourth embodiment, only the differences will be described.

  The both-side cooling module 80 includes a front cooling nozzle 81 and a cooling nozzle (hereinafter referred to as a rear cooling nozzle) 72. An air supply pump (hereinafter referred to as a double-sided cooling air supply pump) is connected to the front cooling nozzle 81 and the rear cooling nozzle 72 via an air supply system piping (hereinafter referred to as a double-sided cooling air supply system piping) 73. 74 is connected. The both-side cooling air supply pump 74 takes in air, pressurizes the introduced air to a predetermined pressure, and supplies the air to the front cooling nozzle 81 and the rear cooling nozzle 72 through the both-side cooling air supply system piping 73. Thereby, the front cooling nozzle 81 ejects the front cooling air 82 over the recording medium 2 over the entire width in the line exposure direction X. The cooling nozzle 72 ejects cooling air 71 over the recording medium 2 over the entire width in the line exposure direction X.

  The front cooling nozzle 81 and the rear cooling nozzle 72 are respectively installed on both the upstream side and the downstream side of the exposure position across the exposure position of the light bar 15 on the recording medium 30 in the coloring station 10. The air flow 83 of the front cooling air 82 ejected from the front cooling nozzle 81 forcibly cools the recording medium 2. An airflow 77 of cooling air (hereinafter referred to as rear cooling air) 71 ejected from the rear cooling nozzle 72 also forcibly cools the recording medium 2.

  It is necessary to prevent the airflow 83 of the front cooling air 82 and the airflow 77 of the rear cooling air 71 from reaching the exposure part of the light bar 15 and cooling the exposure part. However, a predetermined area from the vicinity of the front cooling nozzle 81 and the rear cooling nozzle 72 to the exposed portion of the light bar 15 is in a negative pressure state relative to the ambient pressure by an exhaust fan (hereinafter referred to as a double-side cooling exhaust fan) 76. It has become. The air flow 83 of the front cooling air 82 and the air flow 77 of the rear cooling air 71 are sucked into a halogen lamp house (hereinafter referred to as a double-side cooling halogen lamp house) 75 before reaching the exposure portion of the light bar 15. Is done. The airflows 83 and 77 in the halogen lamp house 75 during both-side cooling cool the halogen lamp condensing optical system 14 and the halogen lamp 11, and are then discharged to the outside by the both-side cooling exhaust fan 76.

  The airflows 83 and 77 in the halogen lamp house 75 at the time of both-side cooling are the airflow 83 and the rear cooling air 71 of the front cooling air 82 ejected from the two nozzles of the front cooling nozzle 81 and the rear cooling nozzle 72. The airflow 77 of the Accordingly, the double-side cooling exhaust fan 76 and the double-side cooling halogen lamp house 75 have different structures or condition settings from those when the single-side cooling module 70 is used. Similarly, the both-side cooling air supply system pipe 73 and the both-side cooling air supply pump 74 have different structures or condition settings from those when the one-side cooling module 70 is used.

Next, a case where both-side forced cooling by the both-side cooling module 80 is necessary will be described.
If the exposure time in the pre-coloring heating process is long, the heat conduction in the horizontal direction (plane direction) of the recording medium 2 cannot be ignored. Under such conditions, heat is conducted through the inside of the recording medium 2 in both the upstream side and the downstream side with respect to the exposure position of the light bar 15 on the recording medium 2 in the coloring station 10. Regarding the downstream side, similarly to the one-side cooling module 70 in the fourth embodiment, the recording medium 2 is forcibly cooled by the rear cooling air 71 ejected from the rear cooling nozzle 72, and the cooling rate in the color cooling step Can be secured.

  On the other hand, on the upstream side, if there is no front cooling nozzle 81, there is no means for forcibly cooling the recording medium 2, and the temperature in the recording medium 2 rises. For this reason, the coloring conditions in the coloring station 10 change. Further, the temperature rise in the recording medium 2 also affects the cooling by the rear cooling nozzle 72. For example, when the total amount of heat in the recording medium 2 exceeds the amount of heat removed by the rear cooling nozzle 72, a sufficient cooling rate cannot be ensured.

  Therefore, in the fifth embodiment, the front cooling nozzle 81 and the rear cooling nozzle 72 are installed in both the upstream side and the downstream side across the exposure position of the light bar 15 on the recording medium 2 in the coloring station 10. The heat that moves in both directions upstream and downstream from the exposure position of the light bar 15 on the recording medium 2 is absorbed by forced cooling by an air flow.

Next, the operation of rewriting data such as an image by the apparatus configured as described above will be described as different from the fourth embodiment.
The both-side cooling air supply pump 74 of the both-side cooling module 80 takes in outside air directly from the outside of the apparatus, for example, pressurizes the taken-in air to a predetermined pressure, and passes through the both-side cooling air supply system piping 73 as the cooling air 71. Supply to the front cooling nozzle 81 and the rear cooling nozzle 72. As a result, the rear cooling nozzle 72 ejects the cooling air 82 over the entire width in the line exposure direction X onto the recording medium 2 to forcibly cool the recording medium 2. The front cooling nozzle 81 ejects cooling air 71 over the recording medium 2 over the entire width in the line exposure direction X, and controls the coloring cooling process following the pre-coloring heating process by the light bar 15 by forced cooling.

  On the other hand, the both-side cooling exhaust fan 76 sucks the cooling air 82 and the cooling air 71 ejected to the recording medium 2 and directly cools the cooling air 82 to the heating portion of the recording medium 2 by the coloring station 10. And the inflow of the cooling air 71 is prevented. Further, the both-side cooling exhaust fan 76 passes the cooling air 82 and the cooling air 71 ejected to the recording medium 2 through the coloring station 10 and sucks them while cooling the coloring station 10.

  However, the airflows 83 and 77 of the cooling air 82 and the cooling air 71 respectively ejected from the front cooling nozzle 81 and the rear cooling nozzle 72 collide with the recording medium 2 after the pre-coloring heating process, and the recording medium 2 is forcibly cooled. Airflows 83 and 77 of the cooling air 82 and the cooling air 71 flow in the both-side cooling halogen lamp house 75 from the lower end toward the upper end, cooling the halogen lamp condensing optical system 14 and the halogen lamp 11, Thereafter, the air is exhausted from the upper end of the both-side cooling halogen lamp house 75 to the outside of the apparatus by the both-side cooling exhaust fan 76.

The change in temperature and density on the recording medium 2 from the color development step to the color erasing step in the present embodiment is the temperature shown in FIG. 5 used in the description of the color development step to the color erasing step in the first embodiment. Temperature-time curve Tc ₀ -Tc ₁ -Tc ₂ -Tc ₃ -Tc ₄ -Tc ₅ -Te ₁ -Te ₂ -Te ₃ -Te _{4 in the} concentration curve-time relationship diagram, and concentration-time curve Dc _{0- Dc 3 -Dc 4 -De 1 -De 2} -De 4 is basically the same. Note that the forced cooling by the both-side cooling module 80 acts on the temperature decrease shown in the temperature curve Tc ₂ -Tc ₃ -Tc ₄ (150 ° C.) from the maximum temperature, which is the color development cooling process. Furthermore, the forced cooling by the both-side cooling module 80 is also effective for the decoloring and cooling advance step Tc ₄ -Tc ₅ (115 ° C.). That is, the both-side cooling module 80 forcibly cools the portion of the recording medium 2 heated to the color development possible temperature band S by the coloring station 10 and complements the natural cooling of the portion of the recording medium 2 heated by the halogen lamp 11. And more reliable color development.

  As described above, according to the fifth embodiment, the front cooling air 81 and the cooling air 71 are ejected from the front cooling nozzle 81 and the rear cooling nozzle 72 of the both-side cooling module 80, respectively. This stabilizes the temperature of the recording medium 2 at the exposure position of the light bar 15 in the coloring station 10 and stabilizes the cooling rate in the coloring cooling step even if the exposure time in the pre-coloring heating step becomes long. And the speed condition of the temperature change can be kept constant. Furthermore, the cooling rate in the decoloring / cooling advance process by the decoloring station 20 can be stabilized, the decoloring heating start temperature at the exposure position of the laser beam 21a is stabilized, and the temperature of the decoloring process and the speed condition of the temperature change can be set. Can be kept constant.

  Without using the front cooling nozzle 84, the temperature of the recording medium can be sensed by a temperature sensor, and the output of the halogen lamp 11 can be lowered in conjunction with this. Also by this method, the temperature of the recording medium 2 at the exposure position of the light bar 15 in the coloring station 10 can be stably controlled.

  The fifth embodiment may be modified as follows. For example, the forced cooling means by the both-side cooling module 80 is, for example, a contact-type both-side cooling module 80, for example, a hollow cooling roller made of aluminum whose surface is coated with fluororesin, as described in the fourth embodiment. Alternatively, it may be a movable endless heat-resistant film made of polyimide having a cooling metal bar inside and a fluororesin-coated surface. In this case, it is possible to install a hollow cooling roller or an endless heat resistant film or the like in both the upstream side and the downstream side across the exposure position of the light bar 15 on the recording medium 30.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

1 is a basic configuration diagram showing a first embodiment of an image rewriting apparatus according to the present invention. The schematic perspective view of the apparatus. FIG. 2 is a schematic cross-sectional view showing a recording medium used in the apparatus. FIG. 5 is a diagram showing the relationship between temperature / density and time based on the characteristics of a recording medium, from a normal color development process to a decoloring process. FIG. 4 is a relationship diagram of temperature / density and time based on the characteristics of a recording medium in a flow from a coloring process to a decoloring process performed by the apparatus. The figure which shows the comparative example of the relationship between temperature, density, and time based on the characteristic of a recording medium about the flow from the coloring process to the decoloring process by the apparatus. The basic block diagram which shows 2nd Embodiment of the image rewriting apparatus which concerns on this invention. The schematic perspective view of the apparatus. The basic block diagram which shows 3rd Embodiment of the image rewriting apparatus which concerns on this invention. The schematic perspective view of the apparatus. The basic block diagram which shows 4th Embodiment of the image rewriting apparatus which concerns on this invention. The schematic perspective view of the apparatus. The basic block diagram which shows 5th Embodiment of the image rewriting apparatus which concerns on this invention. The schematic perspective view of the apparatus.

Explanation of symbols

  1: Recording medium transport device, 2: Photothermal conversion type reversible thermosensitive recording medium (recording medium), 2a: Pre-recorded image, 2b: Uniform color image, 2c: Recorded image, 2-1: Support, 2-2 : Reversible thermosensitive recording layer, 2-3: protective layer, 3a, 3b: transport roller, 4: transport belt, 10: coloring station, 11: halogen lamp, 12: filament, 13: reflective film, 14: for halogen lamp Condensing optical system, 15: light bar, 20: decoloring station, 21: semiconductor laser, 21a: laser beam, 22: condensing optical system for laser, 23: polygon mirror, 24: polygon motor, 30: laser array module 31: Semiconductor laser array, 32: Condensing optical system for laser array, 33: Unit laser beam, 34: Laser beam array, 35: Laser ray driver, 40: Container, 5 : Color development / erasing station, 51: First semiconductor laser, 51a: First laser beam for color development, 52: Second semiconductor laser, 52a: Second laser beam, 53: Laser focusing optical system for color development 54: Polarizing beam splitter, 55: Laser beam, 56: Laser focusing optical system for erasing, 57: Laser beam, 60: Two-dimensional scanning system, 61: Two-dimensional galvanometer mirror, 62: High-speed scanning rotation axis, 63 : Low-speed scanning rotation shaft, 70: One-side cooling module, 71: Cooling air (rear cooling air), 72: Cooling nozzle (rear cooling nozzle), 73: Air supply system piping (both-side cooling air supply system piping), 74: Air supply pump (both sides cooling air supply pump), 75: Halogen lamp house, 76: Exhaust fan (both sides cooling exhaust fan), 77: Air flow of cooling air, 80: Both sides cooling module Le, 81: front cooling nozzle, 82: front cooling air, 83: front cooling air stream.

Claims (26)

A reversible sensation that heats to a colorable temperature range higher than normal temperature, develops color by cooling at a predetermined cooling rate, and discolors when heated to a decolorable temperature range lower than the colorable temperature range while maintaining the color development state at normal temperature. In an image rewriting method for rewriting information on a thermal recording medium,
A color development step of heating the reversible thermosensitive recording medium to the color development possible temperature zone and uniformly coloring the reversible thermosensitive recording medium by cooling after the heating;
The temperature of the reversible thermosensitive recording medium that has uniformly developed color is within the decolorable temperature range or outside the decolorable temperature range and within a temperature range that is a predetermined temperature lower than the lower limit temperature of the decolorable temperature range. A decoloring step of heating the reversible thermosensitive recording medium and decoloring the reversible thermosensitive recording medium like the information when it is reduced to any one of the above,
An image rewriting method characterized by comprising:   In the decoloring step, the reversible thermosensitive recording medium is heated to increase the temperature within the decolorable temperature range, or from the temperature range lower than the lower limit temperature of the decolorable temperature range, 2. The image rewriting method according to claim 1, wherein the temperature of the reversible thermosensitive recording medium is erased like the information by raising the temperature into a possible temperature range.   The decoloring step heats the reversible thermosensitive recording medium within the decolorable temperature range and satisfies the temperature change rate at which the temperature change rate can be decolored within the decolorable temperature range. 2. The image rewriting method according to claim 1, wherein the thermal recording medium is decolored in the manner of information. The heating time for the reversible thermosensitive recording medium by the decoloring step is shorter than the heating time for the reversible thermosensitive recording medium by the coloring step,
And the heating energy given to the reversible thermosensitive recording medium by the decoloring step is smaller than the heating energy given to the reversible thermosensitive recording medium by the coloring step,
The image rewriting method according to claim 1, wherein: The reversible thermosensitive recording medium comprises a layer in which a thermosensitive recording material capable of reversible color development and decoloring and a light-absorbing heat conversion material that generates heat when irradiated with light energy, each alone or mixed,
In the coloring step and the decoloring step, the reversible thermosensitive recording medium is irradiated with the light energy to perform the heating in a non-contact manner,
The image rewriting method according to claim 1, wherein:   2. The image rewriting method according to claim 1, further comprising a cooling step of forcibly cooling the reversible thermosensitive recording medium heated to the color development possible temperature band in the color development step. A reversible sensation that heats to a colorable temperature range higher than normal temperature, develops color by cooling at a predetermined cooling rate, and discolors when heated to a decolorable temperature range lower than the colorable temperature range while maintaining the color development state at normal temperature. In an image rewriting device for rewriting information on a thermal recording medium,
A color development system in which the reversible thermosensitive recording medium is heated to the color development possible temperature zone, and the reversible thermosensitive recording medium is uniformly colored by cooling after the heating;
The temperature of the reversible thermosensitive recording medium that has uniformly developed color is within the decolorable temperature range or outside the decolorable temperature range and within a temperature range that is a predetermined temperature lower than the lower limit temperature of the decolorable temperature range. A decoloring system that heats the reversible thermosensitive recording medium and decolorizes the reversible thermosensitive recording medium like the information when it is reduced to any one of the above;
An image rewriting apparatus comprising:   The decoloring system heats the reversible thermosensitive recording medium to increase the temperature within the decolorable temperature range, or decolorize from the temperature range lower than the lower limit temperature of the decolorable temperature range. 8. The image rewriting apparatus according to claim 7, wherein the reversible thermosensitive recording medium is decolored like the information by raising the temperature into a possible temperature range.   The decoloring system heats the reversible thermosensitive recording medium within the decolorable temperature range and satisfies the temperature change rate at which the temperature change rate can be decolored within the decolorable temperature range. 8. The image rewriting apparatus according to claim 7, wherein the thermal recording medium is erased in the information-like manner.   The decoloring system has a heating time for the reversible thermosensitive recording medium shorter than a heating time for the reversible thermosensitive recording medium by the color developing system, and the heating energy applied to the reversible thermosensitive recording medium by the color developing system. 8. The image rewriting device according to claim 7, wherein the image rewriting device is smaller than the heating energy applied to the reversible thermosensitive recording medium. The reversible thermosensitive recording medium comprises a layer in which a thermosensitive recording material capable of reversible color development and decoloring and a light-absorbing heat conversion material that generates heat when irradiated with light energy, each alone or mixed,
The color development system and the color erasing system each perform the heating in a non-contact manner by irradiating the reversible thermosensitive recording medium with the light energy.
8. The image rewriting device according to claim 7, wherein A transport mechanism for transporting the reversible thermosensitive recording medium,
The coloring system is provided on the upstream side in the transport direction of the reversible thermosensitive recording medium by the transport mechanism,
The decoloring system is provided on the downstream side of the light emitting system installation position in the transport direction of the reversible thermosensitive recording medium by the transport mechanism,
The interval between the color developing system and the color erasing system is such that at least the transport speed of the reversible thermosensitive recording medium by the transport mechanism and the temperature of the reversible thermosensitive recording medium are heated to the color developable temperature band by the color developing system. Based on the time required for the temperature to fall to either one of the temperature range within the decolorizable temperature range or outside the decolorizable temperature range and lower than the lower limit temperature of the decolorable temperature range by a predetermined temperature. Set,
8. The image rewriting device according to claim 7, wherein A transport mechanism for transporting the reversible thermosensitive recording medium,
The color forming system uniformly irradiates the reversible thermosensitive recording medium by irradiating the reversible thermosensitive recording medium with light energy in a direction perpendicular to the transporting direction of the reversible thermosensitive recording medium by the transport mechanism. Color,
The color erasing system erases the reversible thermosensitive recording medium like the information by scanning light energy in a direction perpendicular to the transport direction of the reversible thermosensitive recording medium by the transport mechanism.
8. The image rewriting device according to claim 7, wherein   An irradiation angle of the linear light energy with respect to the reversible thermosensitive recording medium by the color developing system with respect to the transport direction, and a scanning angle with respect to the transport direction of the light energy with respect to the reversible thermosensitive recording medium by the decoloring system. 14. The image rewriting device according to claim 13, wherein the image rewriting devices are set to be the same. The coloring system includes a halogen lamp that emits light as the light energy;
A condensing system for forming the light beam emitted from the halogen lamp into the linear light beam and irradiating the reversible thermosensitive recording medium;
14. The image rewriting apparatus according to claim 13, further comprising: The erasing system includes a semiconductor laser that outputs a laser beam as the light energy;
A scanning system that scans the laser beam output from the semiconductor laser in a direction perpendicular to the conveyance direction of the reversible thermosensitive recording medium, and erases the reversible thermosensitive recording medium like the information. The image rewriting device according to claim 12. The decoloring system includes a semiconductor laser array in which a plurality of laser elements that output laser beams as the light energy are arranged in a line, and
A condensing system for forming each laser beam output from each laser element of the semiconductor laser array into the line shape and irradiating the reversible thermosensitive recording medium;
14. The image rewriting apparatus according to claim 13, further comprising: The coloring system includes a first semiconductor laser that outputs a first laser beam for coloring;
The erasing system has a second semiconductor laser that outputs a second laser beam for erasing,
The color development system and the color erasing system cause the reversible thermosensitive recording medium to uniformly color by scanning the first laser beam output from the first semiconductor laser onto the reversible thermosensitive recording medium. And a two-dimensional scanning system that scans the reversible thermosensitive recording medium with the second laser beam output from the second semiconductor laser and erases the reversible thermosensitive recording medium like the information. ,
The two-dimensional scanning system scans the first laser beam onto the reversible thermosensitive recording medium before scanning the second laser beam onto the reversible thermosensitive recording medium.
8. The image rewriting device according to claim 7, wherein   The two-dimensional scanning system scans the first laser beam onto the reversible thermosensitive recording medium, and then the temperature of the reversible thermosensitive recording medium is within the decolorizable temperature band or outside the decolorizable temperature band. The second laser beam is scanned onto the reversible thermosensitive recording medium when the temperature falls to one of a temperature range lower than a lower limit temperature of the decolorizable temperature range by a predetermined temperature. 18. The image rewriting device according to 18.   8. The image rewriting apparatus according to claim 7, further comprising a cooling system for forcibly cooling a portion of the reversible thermosensitive recording medium heated to the color development possible temperature range by the color development system.   21. The image rewriting apparatus according to claim 20, wherein the cooling system includes at least one cooling nozzle for ejecting a cooling medium to the reversible thermosensitive recording medium. A transport mechanism for transporting the reversible thermosensitive recording medium,
The color forming system uniformly irradiates the reversible thermosensitive recording medium by irradiating the reversible thermosensitive recording medium with light energy in a direction perpendicular to the transporting direction of the reversible thermosensitive recording medium by the transport mechanism. Let it color,
The cooling nozzle ejects the cooling medium in a line along the line-shaped light energy irradiated on the reversible thermosensitive recording medium.
The image rewriting apparatus according to claim 21, wherein   The image rewriting device according to claim 21, wherein the cooling nozzle ejects cooling air as the cooling medium.   A suction mechanism for sucking the cooling medium ejected to the reversible thermosensitive recording medium and preventing the cooling medium from flowing directly into the heating portion of the reversible thermosensitive recording medium by at least the coloring system; The image rewriting apparatus according to claim 21, wherein   The image rewriting device according to claim 21, wherein the suction mechanism sucks the cooling medium ejected to the reversible thermosensitive recording medium through the coloring system while cooling the coloring system. . A transport mechanism for transporting the reversible thermosensitive recording medium, wherein the cooling nozzle is upstream of the heating direction of the reversible thermosensitive recording medium by the coloring system in the transport direction of the reversible thermosensitive recording medium by the transport mechanism. Provided on the side and the downstream hanging side,
The image rewriting apparatus according to claim 21, wherein

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