Drawing system and drawing method

Abstract

A drawing system according to one embodiment of the present invention comprises a light source unit and a scanning unit. The light source unit generates multiple laser beams including wavelengths that are different from each other and that correspond to absorption wavelengths of a photothermal converter contained in a recording medium. The scanning unit scans the laser beams over the surface of the recording medium in a state in which spots irradiated by the multiple laser beams are lined up at a predetermined spacing in a direction orthogonal to or obliquely intersecting the directions in which the laser beams are scanned.

Description

Drawing system and drawing method

[0001] The present disclosure relates to a drawing system and a drawing method.

[0002] As a display medium to replace printed matter, so-called reversible thermosensitive recording media, which record and erase information reversibly using heat, have been developed. In a reversible thermosensitive recording medium, for example, multiple reversible thermosensitive recording layers with different photothermal conversion wavelengths are stacked via a heat-insulating layer. Information is recorded and erased by irradiating the reversible thermosensitive recording medium with laser light of a predetermined wavelength, selectively generating heat in a specific reversible thermosensitive recording layer, and the generated heat causes coloring or decoloring (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2004-188827

[0004] However, when writing or erasing is performed simultaneously on the same pixel in each reversible thermosensitive recording layer, thermal crosstalk may occur between two reversible thermosensitive recording layers adjacent in the stacking direction, which may result in unexpected writing or erasing. Therefore, it is desirable to provide an imaging system and imaging method that are less likely to cause unexpected writing or erasing.

[0005] An imaging system according to an embodiment of the present disclosure is a system for performing imaging on a recording medium having multiple recording layers stacked via a heat-insulating layer, each recording layer including a different color-developing compound and a different photothermal conversion agent. The imaging system includes a light source unit and a scanning unit. The light source unit generates multiple laser beams having different wavelengths that correspond to the absorption wavelengths of the photothermal conversion agents. The scanning unit irradiates the surface of the recording medium with the multiple laser beams generated by the light source unit via a predetermined gap, and synchronously scans the multiple laser beams in the same direction on the surface of the recording medium. The scanning unit scans the surface of the recording medium with the multiple laser beams, with irradiation spots formed by the multiple laser beams aligned at predetermined intervals in a direction perpendicular to or obliquely intersecting the scanning direction of the multiple laser beams.

[0006] In an imaging system according to an embodiment of the present disclosure, a plurality of laser beams are generated by a light source, and the laser beams are scanned on the surface of the recording medium with irradiation spots aligned at predetermined intervals in a direction perpendicular to or diagonally intersecting the scanning direction of the laser beams. This reduces thermal crosstalk between adjacent recording layers in the stacking direction. As a result, the possibility of unexpected writing or erasure can be reduced.

[0007] A drawing method according to an embodiment of the present disclosure is a method for drawing on a recording medium having a plurality of recording layers, each containing a different color-developing compound and a different photothermal conversion agent, stacked via a heat-insulating layer. This drawing method includes the following three steps: (1) generating a plurality of laser beams having different wavelengths that correspond to the absorption wavelengths of the photothermal conversion agents; (2) irradiating the surface of the recording medium with the generated laser beams via a predetermined gap, and synchronously scanning the surface of the recording medium with the plurality of laser beams in the same direction; and (3) scanning the surface of the recording medium with the plurality of laser beams, with irradiation spots formed by the plurality of laser beams aligned at predetermined gaps in a direction perpendicular to or obliquely intersecting the scanning direction of the plurality of laser beams.

[0008] In a writing method according to an embodiment of the present disclosure, a plurality of laser beams are scanned on the surface of a recording medium, with the irradiation spots of the plurality of laser beams aligned at predetermined intervals in a direction perpendicular to or diagonally intersecting the scanning direction of the plurality of laser beams. This reduces thermal crosstalk between adjacent recording layers in the stacking direction. As a result, the possibility of unexpected writing or erasure can be reduced.

[0009] FIG. 1 is a diagram illustrating an example of a schematic configuration of a drawing system according to an embodiment of the present disclosure. FIG. 1 is a diagram illustrating an example of a schematic configuration of the drawing unit of FIG. 1. FIG. 2 is a diagram illustrating an example of a cross-sectional configuration of the recording medium of FIG. 2. FIG. 3 is a diagram illustrating a state of drawing in the drawing system of FIG. 1. FIG. 4 is a diagram illustrating a state of drawing in the drawing system of FIG. 1. FIG. 5 is a diagram illustrating an example of a drawing method according to a comparative example. FIG. 6 is a diagram illustrating an example of a drawing method according to a comparative example. FIG. 7 is a diagram illustrating a modified example of the schematic configuration of the drawing system of FIG. 1. FIG. 8 is a diagram illustrating a modified example of the schematic configuration of the drawing system of FIG. 1. FIG. 9 is a diagram illustrating a modified example of the schematic configuration of the drawing system of FIG. 1. FIG. 10 is a diagram illustrating a modified example of the schematic configuration of the drawing system of FIG. 1. FIG. 11 is a diagram illustrating a modified example of the drawing method in the drawing systems of FIGS. 1 and 7 to 11. FIG. 12 is a diagram illustrating an example of a drawing procedure in the drawing method of FIG. 12. FIG. 13 is a diagram illustrating an example of a drawing procedure in the drawing method of FIG. 12. FIG. 14 is a diagram illustrating evaluation results of an image drawn using the drawing method of FIG. 12. FIG. 15 is a diagram illustrating a modified example of the drawing method of FIG. 12.

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following description is a specific example of the present disclosure, and the present disclosure is not limited to the following aspects.

[0011] 1. Embodiment [Configuration] A drawing system 100 according to an embodiment of the present disclosure will be described. FIG. 1 illustrates a schematic configuration example of the drawing system 100 according to the present embodiment. The drawing system 100 writes (draws) and erases information on a recording medium 10 (described below). The drawing system 100 converts, for example, image data input from an external device and described in a device-dependent color space (hereinafter referred to as "input image data") into image data described in the color space of the recording medium 10 (hereinafter referred to as "drawing image data"). Here, the device-dependent color space is, for example, an RGB color space such as sRGB or Adobe® RGB. The color space of the recording medium 10 is a color space that the recording medium 10 possesses as a characteristic. The drawing system 100 further converts the drawing image data obtained by the conversion into output setting values ​​of a drawing unit 150 (described below), and inputs the output setting values ​​obtained by the conversion to the drawing unit 150, thereby performing drawing on the recording medium 10. In the following, the drawing system 100 will be first described, and then the recording medium 10 will be described.

[0012] (Drawing system 100) The drawing system 100 includes, for example, a communication unit 110, an input unit 120, a display unit 130, a storage unit 140, a drawing unit 150, and an information processing unit 160. The drawing system 100 is connected to a network, for example, via the communication unit 110. The network is, for example, a communication line such as a LAN or a WAN. For example, a terminal device is connected to the network. The drawing system 100 is configured, for example, to be able to communicate with the terminal device via the network. The terminal device is, for example, a mobile terminal, and is configured to be able to communicate with the drawing system 100 via the network.

[0013] The communication unit 110 communicates with external devices such as terminal devices. The communication unit 110 transmits input image data received from an external device such as a mobile terminal to the information processing unit 160. The input image data is data in which the gradation values ​​of each drawing coordinate are described in a device-dependent color space. In the input image data, the gradation values ​​of each drawing coordinate are composed of, for example, an 8-bit red gradation value, an 8-bit green gradation value, and an 8-bit blue gradation value.

[0014] The input unit 120 accepts input (e.g., execution instructions, data input, etc.) from the user. The input unit 120 transmits the information input by the user to the information processing unit 160. The display unit 130 displays a screen based on various screen data created by the information processing unit 160. The display unit 130 is configured by, for example, a liquid crystal panel or an organic EL (Electro Luminescence) panel.

[0015] The storage unit 140 stores, for example, various programs. The storage unit 140 stores, for example, a program that converts input image data described in a device-dependent color space into drawing image data described in the color space of the recording medium 10. The drawing image data is, for example, data in which the gradation values ​​of each drawing coordinate are described in the color space of the recording medium 10. If the color space of the recording medium 10 is a leuco color space, the gradation values ​​of each drawing coordinate in the drawing image data are composed of, for example, an 8-bit magenta gradation value, an 8-bit cyan gradation value, and an 8-bit yellow gradation value. The storage unit 140 also stores, for example, a program that derives output setting values ​​for the drawing unit 150 for each drawing coordinate based on the gradation values ​​of the drawing image data obtained by conversion. In FIG. 1, these programs are collectively referred to as program 141.

[0016] The information processing unit 160 includes, for example, a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit), and executes various programs (for example, program 141) stored in the storage unit 140. For example, when the program 141 is loaded, the information processing unit 160 executes a series of procedures described in the program 141.

[0017] Next, the drawing unit 150 will be described. Fig. 2 shows an example of a schematic configuration of the drawing unit 150. The drawing unit 150 has, for example, a signal processing circuit 51, a laser driving circuit 52, a light source unit 53, a scanner driving circuit 54, an X scanner unit 55, a Y stage driving circuit 56, and a Y stage 57. The drawing unit 150 performs drawing on the recording medium 10 by controlling the output of the light source unit 53 based on a voltage value file (a list of command voltage values) input from the information processing unit 160.

[0018] The signal processing circuit 51 acquires a voltage value file (a list of command voltage values) input from the information processing unit 160 as an image signal Din. For example, the signal processing circuit 51 generates a pixel signal Dout from the image signal Din in accordance with the scanner operation of the X scanner unit 55. The pixel signal Dout causes the light source unit 53 (e.g., each of the light sources 53A, 53B, and 53C described below) to output laser light with a power corresponding to the command voltage value. Together with the laser driving circuit 52, the signal processing circuit 51 controls the peak value of a current pulse applied to the light source unit 53 (e.g., each of the light sources 53A, 53B, and 53C) in accordance with the pixel signal Dout.

[0019] The laser driving circuit 52 drives the light sources 53A, 53B, and 53C of the light source unit 53, for example, in accordance with the pixel signal Dout. The laser driving circuit 52 controls the brightness (brightness) of the laser light to draw an image corresponding to the pixel signal Dout. The laser driving circuit 52 includes, for example, a driving circuit 52A for driving the light source 53A, a driving circuit 52B for driving the light source 53B, and a driving circuit 52C for driving the light source 53C. The light sources 53A, 53B, and 53C output laser light of a power corresponding to a command voltage value to the recording medium 10, thereby drawing an image on the recording medium 10. The light sources 53A, 53B, and 53C emit laser light in the near-infrared range. The light source 53A is, for example, a semiconductor laser that emits laser light La with an emission wavelength λ1. The light source 53B is, for example, a semiconductor laser that emits laser light Lb with an emission wavelength λ2. The light source 53C is, for example, a semiconductor laser that emits laser light Lc with an emission wavelength λ3.

[0020] The light source unit 53 has multiple light sources (e.g., three light sources 53A, 53B, and 53C) with different emission wavelengths in the near-infrared range. Each light source (e.g., each light source 53A, 53B, and 53C) generates laser light having a wavelength corresponding to the absorption wavelength of a photothermal conversion agent (described below) contained in the recording medium 10. The light source unit 53 further has, for example, an optical system that outputs multiple laser beams (e.g., three laser beams La, Lb, and Lc) emitted from the multiple light sources (e.g., three light sources 53A, 53B, and 53C) aligned in a predetermined direction with a predetermined gap between them. This optical system outputs the multiple laser beams La, Lb, and Lc to the X scanner unit 55, for example, so that multiple irradiation spots Pa, Pb, and Pc generated on the recording medium 10 by the multiple laser beams La, Lb, and Lc are aligned in the X-axis direction on the Y stage 57 with a predetermined gap between them. The X-axis direction is perpendicular to the movement direction (Y-axis direction) of the Y-stage 57 and is parallel to the scanning direction of the uniaxial scanner 55a (described later). The light source unit 63 has, as such an optical system, for example, two reflecting mirrors 53a and 53d and two dichroic mirrors 53b and 53c.

[0021] The laser beams La and Lb emitted from the two light sources 53A and 53B are converted into nearly parallel beams (collimated beams) by, for example, a collimating lens. Thereafter, for example, the laser beam La is reflected by the reflecting mirror 53a and the dichroic mirror 53b, and the laser beam Lb passes through the dichroic mirror 53b. As a result, the laser beams La and Lb are output side by side in a predetermined direction. The laser beams La and Lb pass through the dichroic mirror 53c.

[0022] The laser beam Lc emitted from the light source 53C is converted into a substantially parallel beam (collimated beam) by, for example, a collimating lens. The laser beam Lc is then reflected by, for example, a reflecting mirror 53d and a dichroic mirror 53c. As a result, the laser beams La and Lb transmitted through the dichroic mirror 53c and the laser beam Lc reflected by the dichroic mirror 53c are output aligned in a predetermined direction. The light source unit 53 outputs the laser beams La, Lb, and Lc aligned in a predetermined direction by, for example, the optical system described above to the X scanner unit 55.

[0023] Here, on the dichroic mirror 53b, the spot where the laser beam La is reflected and the spot where the laser beam Lb is transmitted may overlap each other. In this case, the optical system is configured so that the optical axis of the laser beam La reflected by the dichroic mirror 53b and the optical axis of the laser beam Lb transmitted through the dichroic mirror 53b intersect at a predetermined angle. Furthermore, on the dichroic mirror 53b, the spot where the laser beam La is reflected and the spot where the laser beam Lb is transmitted may not completely overlap each other but may be shifted from each other. Furthermore, on the dichroic mirror 53b, the spot where the laser beam La is reflected and the spot where the laser beam Lb is transmitted may be separated from each other. In these cases, the optical system may be configured so that the optical axis of the laser beam La reflected by the dichroic mirror 53b and the optical axis of the laser beam Lb transmitted through the dichroic mirror 53b intersect at a predetermined angle, or so that they are parallel to each other.

[0024] The optical system is configured such that the spots on the dichroic mirror 53c where the laser beam La or Lb passes and the spots on which the laser beam Lc is reflected do not completely overlap but are shifted from one another. In this case, the spots on the dichroic mirror 53c where the laser beam La passes, the spots on the dichroic mirror 53c where the laser beam Lb passes, and the spots on which the laser beam Lc is reflected may be aligned with a slight shift in a predetermined direction. In the dichroic mirror 53c, the spots on the dichroic mirror 53c where the laser beam La passes, the spots on the dichroic mirror 53c where the laser beam Lb passes, and the spots on which the laser beam Lc is reflected may be aligned with a predetermined gap therebetween.

[0025] In these cases, the optical system may be configured so that the optical axis of laser beam La transmitted through dichroic mirror 53 c, ​​the optical axis of laser beam Lb transmitted through dichroic mirror 53 c, ​​and the optical axis of laser beam Lc reflected by dichroic mirror 53 c intersect with one another at a predetermined angle. In this case, light source unit 53 outputs the multiple laser beams La, Lb, and Lc to X scanner unit 55 with the optical axes of the multiple laser beams La, Lb, and Lc shifted from one another, and outputs the multiple laser beams La, Lb, and Lc to X scanner unit 55 so that the optical axes of the multiple laser beams La, Lb, and Lc intersect with one another at a predetermined angle.

[0026] Furthermore, the optical system may be configured so that the optical axis of laser beam La transmitted through dichroic mirror 53c, the optical axis of laser beam Lb transmitted through dichroic mirror 53c, and the optical axis of laser beam Lc reflected by dichroic mirror 53c are parallel to one another. In this case, light source unit 53 outputs the plurality of laser beams La, Lb, and Lc to X scanner unit 55 with the optical axes of the plurality of laser beams La, Lb, and Lc shifted from one another, and outputs the plurality of laser beams La, Lb, and Lc to X scanner unit 55 so that the optical axes of the plurality of laser beams La, Lb, and Lc are parallel to one another with a predetermined gap therebetween.

[0027] Scanner drive circuit 54 drives X scanner unit 55 based on, for example, a control signal input from signal processing circuit 51. Furthermore, when a signal regarding the irradiation angle of a uniaxial scanner 55a (described later) or the like is input from X scanner unit 55, scanner drive circuit 54 drives X scanner unit 55 based on the signal so that the desired irradiation angle is achieved.

[0028] The X-scanner unit 55, for example, scans the surface of the recording medium 10 in the X-axis direction with multiple laser beams La, Lb, and Lc incident from the light source unit 53. The X-scanner unit 55 has, for example, a uniaxial scanner 55a and an fθ lens 55b. The uniaxial scanner 55a is, for example, a galvanometer mirror that scans the laser beams La, Lb, and Lc incident from the light source unit 53 in the X-axis direction on the surface of the recording medium 10 based on a drive signal input from the scanner drive circuit 54. The fθ lens 55b converts the uniform rotational motion of the uniaxial scanner 55a into uniform linear motion of a spot moving on the focal plane (the surface of the recording medium 10).

[0029] Y stage drive circuit 56 drives Y stage 57 based on, for example, a control signal input from signal processing circuit 51. Y stage 57 displaces Y stage 57 in the Y-axis direction at a predetermined speed, thereby moving recording medium 10 placed on Y stage 57 in the Y-axis direction at a predetermined speed relative to X scanner unit 55. Cooperative operation of X scanner unit 55 and Y stage 57 causes laser beams La, Lb, and Lc to raster scan the surface of recording medium 10.

[0030] (Recording Medium 10) Next, the recording medium 10 will be described.

[0031] FIG. 3 shows an example of the configuration of each layer included in the recording medium 10. The recording medium 10 is, for example, a reversible recording medium on which information can be written (drawn) and erased. The recording medium 10 may also be, for example, an irreversible recording medium on which information can be written (drawn) only once and cannot be erased. The recording medium 10 includes multiple recording layers 13, 15, and 17 that have different color tones. The recording medium 10 has a structure in which, for example, an underlayer 12, a recording layer 13, a heat insulating layer 14, a recording layer 15, a heat insulating layer 16, a recording layer 17, and a protective layer 18 are stacked in this order on a substrate 11. The protective layer 18 is positioned opposite the substrate 11, with the underlayer 12, the recording layer 13, the heat insulating layer 14, the recording layer 15, the heat insulating layer 16, and the recording layer 17 interposed therebetween. The protective layer 18 may be disposed on the outermost surface of the recording medium 10, or a layer other than the protective layer 18 may be disposed on the outermost surface of the recording medium 10.

[0032] The three recording layers 13, 15, and 17 are arranged in the order of recording layer 13, recording layer 15, and recording layer 17 from the substrate 11 side. The two heat insulating layers 14 and 16 are arranged in the order of heat insulating layer 114a and heat insulating layer 16 from the substrate 11 side. The underlayer 12 is formed in contact with the surface of the substrate 11. The protective layer 18 is formed on the outermost surface of the recording medium 10.

[0033] The substrate 11 supports the recording layers 13, 15, and 17 and the heat insulating layers 14 and 16. The substrate 11 functions as a substrate for forming each layer on its surface. The substrate 11 may be light-transmitting or light-opaque. If the substrate 11 is light-opaque, the surface color of the substrate 11 may be, for example, white or a color other than white.

[0034] The substrate 11 may be a card or a film. The substrate 11 may have a design, a picture, a photograph, text, or a combination of two or more thereof printed on one main surface on which the recording layer 13 and the like are provided. The substrate 11 includes, for example, plastic. The substrate 11 may contain at least one selected from the group consisting of a colorant, an antistatic agent, a flame retardant, a surface modifier, and the like, as necessary.

[0035] The plastic used for the substrate 11 includes, for example, at least one selected from the group consisting of ester-based resins, amide-based resins, olefin-based resins, vinyl-based resins, acrylic-based resins, imide-based resins, styrene-based resins, engineering plastics, etc. When the substrate 11 includes two or more types of resins, the two or more types of resins may be mixed, copolymerized, or laminated.

[0036] The ester resin includes, for example, at least one selected from the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyethylene terephthalate-isophthalate copolymer, and terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer. The amide resin includes, for example, at least one selected from the group consisting of nylon 6, nylon 66, and nylon 610. The olefin resin includes, for example, at least one selected from the group consisting of polyethylene (PE), polypropylene (PP), and polymethylpentene (PMP). The vinyl resin includes, for example, polyvinyl chloride (PVC).

[0037] The acrylic resin includes, for example, at least one selected from the group consisting of polyacrylate, polymethacrylate, and polymethyl methacrylate (PMMA). The imide resin includes, for example, at least one selected from the group consisting of polyimide (PI), polyamideimide (PAI), and polyetherimide (PEI). The styrene resin includes, for example, at least one selected from the group consisting of polystyrene (PS), high-impact polystyrene, acrylonitrile-styrene resin (AS resin), and acrylonitrile-butadiene-styrene resin (ABS resin). The engineering plastic includes, for example, at least one selected from the group consisting of polycarbonate (PC), polyarylate (PAR), polysulfone (PSF), polyethersulfone (PES), polyphenylene ether (PPE), polyphenylene sulfide (PPS), polyetherketone (PEK), polyether-etherketone (PEEK), polyphenylene oxide (PPO), and polyether sulfite.

[0038] The underlayer 12 has the function of improving the adhesion between the recording layer 13 and the substrate 11. The underlayer 12 is made of, for example, a light-transmitting material. A moisture-resistant barrier layer or a light-resistant barrier layer may be provided above or below the underlayer 12 or the substrate 11. A heat-insulating layer may also be provided between the underlayer 12 and the recording layer 13.

[0039] The three recording layers 13, 15, and 17 can, for example, reversibly change between a colored state and a colorless state. The three recording layers 13, 15, and 17 may, for example, be irreversible, i.e., once they change from a colorless state to a colored state, they do not return to the colorless state. The three recording layers 13, 15, and 17 are configured to have different colors in the colored state. The three recording layers 13, 15, and 17 each contain a color former, a photothermal conversion agent, and a color developer / reduction agent. The three recording layers 13, 15, and 17 each contain a different color former and a different photothermal conversion agent. In the three recording layers 13, 15, and 17, the color former, the photothermal conversion agent, and the color developer / reduction agent are dispersed in a polymer material.

[0040] The color-developing compound may be, for example, a leuco dye. The leuco dye combines with the color-developing / color-reducing agent to develop a color or separates from the color-developing / color-reducing agent to develop a colorless state when exposed to heat. The color tone of the leuco dye contained in each recording layer 13, 15, and 17 differs for each recording layer 13, 15, and 17. The leuco dye contained in recording layer 13 develops a magenta color when combined with the color-developing / color-reducing agent when exposed to heat. The leuco dye contained in recording layer 15 develops a cyan color when combined with the color-developing / color-reducing agent when exposed to heat. The leuco dye contained in recording layer 17 develops a yellow color when combined with the color-developing / color-reducing agent when exposed to heat. The positional relationship between the three recording layers 13, 15, and 17 is not limited to the example described above. Furthermore, the three recording layers 13, 15, and 17 are transparent when in the color-reduced state. This allows the recording medium 10 to record images using a wide color gamut.

[0041] The photothermal conversion agent generates heat by absorbing light in a predetermined wavelength range in the near-infrared region, for example. In this specification, the near-infrared region refers to the wavelength range of 700 nm to 2500 nm. It is preferable to select a photothermal conversion agent that has a narrow light absorption band in the near-infrared region, for example, and whose light absorption bands do not overlap with each other in the recording layers 13, 15, and 17.

[0042] The heat insulating layer 14 is intended to prevent heat transfer between the recording layer 13 and the recording layer 15. The heat insulating layer 16 is intended to prevent heat transfer between the recording layer 15 and the recording layer 17. The protective layer 18 is intended to protect the surface of the recording medium 10 and functions as an overcoat layer for the recording medium 10. The heat insulating layers 14, 16 and the protective layer 18 are made of a transparent material. The recording medium 10 may include, for example, a relatively rigid resin layer (e.g., a PEN resin layer) directly below the protective layer 18. The protective layer 18 may include a moisture-resistant barrier layer or a light-resistant barrier layer. The protective layer 18 may also include any other functional layer.

[0043] Examples of leuco dyes include existing dyes for thermal paper, specifically, compounds containing an electron-donating group in the molecule, such as those shown in Chemical Formula 1 below.

[0044] The color former is not particularly limited and can be appropriately selected depending on the purpose. Specific examples of the color former include the compounds shown in Chemical Formula 1 above, as well as fluoran compounds, triphenylmethanephthalide compounds, azaphthalide compounds, phenothiazine compounds, leucoauramine compounds, and indolinophthalide compounds. Other examples include 2-anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-di(n-butylamino)fluoran, 2-anilino-3-methyl-6-(N-n-propyl-N-methylamino)fluoran, 2-anilino-3-methyl-6-(N-isopropyl-N-methylamino)fluoran, 2-anilino-3-methyl-6-(N-isobutyl-N-methylamino)fluoran, 2-anilino-3-methyl-6-(N-n-amyl-N-methylamino)fluoran, 2-anilino-3-methyl-6-(N-sec-butyl-N-methylamino)fluoran, 2-anilino-3-methyl-6-(N-n-amyl-N-ethylamino)fluoran, 2-anilino-3-methyl-6- (N-iso-amyl-N-ethylamino)fluoran, 2-anilino-3-methyl-6-(N-n-propyl-N-isopropylamino)fluoran, 2-anilino-3-methyl-6-(N-cyclohexyl-N-methylamino)fluoran, 2-anilino-3-methyl-6-(N-ethyl-p-toluidino)fluoran, 2-anilino-3-methyl-6-(N-methyl-p-toluidino)fluoran, 2-(m-trichloromethylanilino)-3-methyl-6-diethylaminofluoran, 2-(m-trifluoromethylanilino)-3-methyl-6-diethylaminofluoran, 2-(m-trichloromethylanilino)-3-methyl-6-(N-cyclohexyl-N-methylamino)fluoran, 2-(2,4-dimethylanilino)-3-methyl-6-diethylaminofluoran, 2-(N-ethyl-p-toluidino)-3-methyl-6-(N-ethylanilino)fluoran, 2-(N-ethyl-p-toluidino)-3-methyl-6-(N-propyl-p-toluidino)fluoran, 2-anilino-6-(N-n-hexyl-N-ethylamino)fluoran, 2-(o-chloroanilino)-6-diethylaminofluoran, 2-(o-chloroanilino)-6-dibutylaminofluoran, 2-(m-trifluoromethylanilino)-6-diethylaminofluoran, 2,3-dimethyl-6-dimethylaminofluoran, 3-methyl-6-(N-ethyl-p-toluidino)fluoran, 2-chloro-6 -diethylaminofluoran, 2-bromo-6-diethylaminofluoran, 2-chloro-6-dipropylaminofluoran, 3-chloro-6-cyclohexylaminofluoran, 3-bromo-6-cyclohexylaminofluoran, 2-chloro-6-(N-ethyl-N-isoamylamino)fluoran, 2-chloro-3-methyl-6-diethylaminofluoran, 2-anilino-3-chloro-6-diethylaminofluoran, 2-(o-chloroanilino)-3-chloro-6-cyclohexylaminofluoran, 2-(m-trifluoromethylanilino)-3-chloro-6-diethylaminofluoran, 2-(2,3-dichloroanilino)-3-chloro-6-diethylaminofluoran, 1,2-benzo-6-diethylaminofluoran, 3-diethylamino-6-(m-trifluoromethylanilino)fluoran, 3-(1-ethyl-2-methylindol-3-yl)-3-(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, 3-(1-ethyl-2-methylindol-3-yl)-3-(2-ethoxy-4-diethylaminophenyl)-7-azaphthalide, 3-(1-octyl- 2-methylindol-3-yl)-3-(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, 3-(1-ethyl-2-methylindol-3-yl)-3-(2-methyl-4-diethylaminophenyl)-4-azaphthalide, 3-(1-ethyl-2-methylindol-3-yl)-3-(2-methyl-4-diethylaminophenyl)-7-azaphthalide, 3-(1-ethyl-2-methylindol-3-yl)-3-(2-methyl-4-diethylaminophenyl)-7-azaphthalide 3-(1-ethyl-2-methylindol-3-yl)-3-(4-diethylaminophenyl)-4-azaphthalide, 3-(1-ethyl-2-methylindol-3-yl)-3-(4-N-n-amyl-N-methylaminophenyl)-4-azaphthalide, 3-(1-methyl-2-methylindol-3-yl)-3-(2-hexyloxy-4-diethylaminophenyl)-4-azaphthalide, 3,3-bis(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide nyl)-4-azaphthalide, 3,3-bis(2-ethoxy-4-diethylaminophenyl)-7-azaphthalide, 2-(p-acetylanilino)-6-(N-n-amyl-N-n-butylamino)fluoran, 2-benzylamino-6-(N-ethyl-p-toluidino)fluoran, 2-benzylamino-6-(N-methyl-2,4-dimethylanilino)fluoran, 2-benzylamino-6-(N-ethyl-2,4-dimethylanilino)fluoran, 2-benzylamino-6-(N-methyl-p-toluidino)fluoran, 2-benzylamino-6-(N-ethyl-p-toluidino)fluoran, 2-(di-p-methylbenzylamino)-6-(N-ethyl-p-toluidino)fluoran, 2-(α-phenylethylamino)-6-(N-ethyl-p-toluidino)fluoran, 2-methylamino-6-(N-methylanilino)fluoran, 2-methylamino-6-(N-ethylanilino)fluoran, 2-methylamino-6-(N-propylanilino)fluoran , 2-ethylamino-6-(N-methyl-p-toluidino)fluoran, 2-methylamino-6-(N-methyl-2,4-dimethylanilino)fluoran, 2-ethylamino-6-(N-ethyl-2,4-dimethylanilino)fluoran, 2-dimethylamino-6-(N-methylanilino)fluoran, 2-dimethylamino-6-(N-ethylanilino)fluoran, 2-diethylamino-6-(N-methyl-p-toluidino)fluoran, 2-diethylamino-6-(N-ethyl-p-toluidino)fluoran, 2-dipropylamino-6-(N-methyl p-toluidino)fluoran, 2-dipropylamino-6-(N-ethylanilino)fluoran, 2-amino-6-(N-methylanilino)fluoran, 2-amino-6-(N-ethylanilino)fluoran, 2-amino-6-(N-propylanilino)fluoran, 2-amino-6-(N-methyl-p-toluidino)fluoran, 2-amino-6-(N-ethyl-p-toluidino)fluoran, 2-amino-6-(N-propyl-p-toluidino)fluoran, 2-amino-6-(N-methyl-p-ethylanilino)fluoran, 2-amino-6-(N-ethylanilino)fluoran 2-amino-6-(N-propyl-p-ethylanilino)fluoran, 2-amino-6-(N-methyl-2,4-dimethylanilino)fluoran, 2-amino-6-(N-ethyl-2,4-dimethylanilino)fluoran, 2-amino-6-(N-propyl-2,4-dimethylanilino)fluoran, 2-amino-6-(N-methyl-p-chloroanilino)fluoran, 2-amino-6-(N-ethyl-p-chloroanilino)fluoran, 2-amino-6-(N-propyl-p-chloroanilino)fluoran, 1,Examples of the color-developing compound include 2-benzo-6-(N-ethyl-N-isoamylamino)fluoran, 1,2-benzo-6-dibutylaminofluoran, 1,2-benzo-6-(N-methyl-N-cyclohexylamino)fluoran, and 1,2-benzo-6-(N-ethyl-N-toluidino)fluoran. The recording layers 13, 15, and 17 may contain one of the above compounds alone or two or more of them in combination as the color-developing compound.

[0045] The color developer / reducer is used, for example, to cause a colorless color former to develop a color or to cause a color former to lose a color. Examples of the color developer / reducer include phenol derivatives, salicylic acid derivatives, and urea derivatives. Specifically, the color developer / reducer may include, for example, a compound represented by Chemical Formula 2 below. (However, in formula (3), X 0 is a divalent group containing at least one benzene ring. 0 When Y contains at least two benzene rings, the at least two benzene rings may be condensed. For example, Y may be naphthalene or anthracene. 01 , Y 02 are each independently a monovalent group. n01 and n02 are each independently an integer of 0 to 5. When n01 is an integer of 2 to 5, Y 01 may be the same or different. When n02 is an integer of 2 to 5, Y 02 may be the same or different. 01 , Z 02 are each independently a hydrogen-bonding group.

[0046] The color developer may contain, for example, a compound represented by the following Chemical Formula 3. (However, in Chemical Formula 3, X 1 is a divalent group containing at least one benzene ring. 11 , Y 12 , Y 13 , Y 14 are each independently a monovalent group. 11 , Z 12are each independently a hydrogen-bonding group.

[0047] When Chemical Formula 2 and Chemical Formula 3 contain a hydrocarbon group, the hydrocarbon group is a general term for a group composed of carbon (C) and hydrogen (H), and may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. A saturated hydrocarbon group is an aliphatic hydrocarbon group that does not have a carbon-carbon multiple bond, and an unsaturated hydrocarbon group is an aliphatic hydrocarbon group that has a carbon-carbon multiple bond (a carbon-carbon double bond or a carbon-carbon triple bond).

[0048] When Chemical Formula 2 and Chemical Formula 3 contain a hydrocarbon group, the hydrocarbon group may be a chain or may contain one or more rings. The chain may be a straight chain or a branched chain having one or more side chains.

[0049] (X containing one benzene ring 0 , X １ ) X in Chemical Formula 2 0 and X in Chemical Formula 3 1 is, for example, a divalent group containing one benzene ring. The divalent group is, for example, represented by the following Chemical Formula 4. (However, in Chemical Formula 4, X 21 It doesn't matter if it's there or not, X 21 If there is X 21 is a divalent group. 22 It doesn't matter if it's there or not, X 22 If there is X 22 is a divalent group. 21 is a monovalent group. n21 is an integer of 0 to 4. When n21 is an integer of 2 to 4, R 21 may be the same or different. * indicates a bond.)

[0050] In Chemical Formula 4, X to the benzene ring 21 and X 22 The bonding position of X to the benzene ring is not limited. 21 and X 22 The bonding position may be any of the ortho, meta and para positions.

[0051] The divalent group containing one benzene ring is preferably represented by the following formula 5 from the viewpoint of improving storage properties under high temperature and humidity. (However, in Chemical Formula 5, R 22 is a monovalent group. n22 is an integer of 0 to 4. When n22 is an integer of 2 to 4, R 22 may be the same or different. * indicates a bond.)

[0052] X in Chemical Formula 2 0 is a divalent group containing one benzene ring, in Chemical Formula 5, Z 01 and Z 02 The bonding position of Z to the benzene ring is not limited. 01 and Z 02 The bonding position may be any of the ortho, meta and para positions.

[0053] X in Chemical Formula 3 1 is a divalent group containing one benzene ring, in Chemical Formula 5, Z 11 and Z 12 The bonding position of Z to the benzene ring is not limited. 11 and Z 12 The bonding position may be any of the ortho, meta and para positions.

[0054] (X 21 , X 22 ) X in Chemical Formula 4 21 , X 22 are each independently a divalent group, and are not particularly limited, but an example thereof is a hydrocarbon group which may have a substituent. The hydrocarbon group is preferably a chain, and a normal alkyl chain is particularly preferred.

[0055] The hydrocarbon group which may have a substituent has, for example, 1 to 15 carbon atoms, 1 to 13 carbon atoms, 1 to 12 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 3 carbon atoms.

[0056] X in Chemical Formula 4 21 , X 22When is a normal alkyl group, the number of carbon atoms in the normal alkyl group is preferably 8 or less, more preferably 6 or less, even more preferably 5 or less, and particularly preferably 3 or less, from the viewpoint of high-temperature storage stability. When the normal alkyl group has 8 or less carbon atoms, the normal alkyl group is short in length, so that thermal disturbance is unlikely to occur in the color developer during high-temperature storage, and it is thought that the site that interacted with the color former such as a leuco dye during color development is unlikely to be dissociated. Therefore, the color former such as a leuco dye is unlikely to fade during high-temperature storage, improving high-temperature storage stability.

[0057] Examples of the substituent that may have a hydrocarbon group include a halogen group (e.g., a fluorine group) and an alkyl group having a halogen group (e.g., a fluorine group). The hydrocarbon group that may have a substituent may be one in which some of the carbon atoms of the hydrocarbon group (e.g., some of the carbon atoms contained in the main chain of the hydrocarbon group) are substituted with an element such as oxygen.

[0058] (R 21 ) R in Chemical Formula 4 21 is not particularly limited as long as it is a monovalent group, but examples thereof include a halogen group or a hydrocarbon group which may have a substituent.

[0059] The halogen group is, for example, a fluorine group (--F), a chlorine group (--Cl), a bromine group (--Br), or an iodine group (--I).

[0060] The hydrocarbon group which may have a substituent has, for example, 1 to 15 carbon atoms, 1 to 13 carbon atoms, 1 to 12 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 3 carbon atoms.

[0061] Examples of the substituent that may have a hydrocarbon group include a halogen group (e.g., a fluorine group) and an alkyl group having a halogen group (e.g., a fluorine group). The hydrocarbon group that may have a substituent may be one in which some of the carbon atoms of the hydrocarbon group (e.g., some of the carbon atoms contained in the main chain of the hydrocarbon group) are substituted with an element such as oxygen.

[0062] (R 22 ) R in Chemical Formula 5 22is not particularly limited as long as it is a monovalent group, but examples thereof include a halogen group and a hydrocarbon group which may have a substituent. The halogen group and the hydrocarbon group which may have a substituent are respectively represented by R in Chemical Formula 2. 21 is the same as:

[0063] (X containing two benzene rings 0 , X 1 ) X in Chemical Formula 2 0 and X in Chemical Formula 3 1 is, for example, a divalent group containing two benzene rings. The divalent group is, for example, represented by the following Chemical Formula 6. (However, in Chemical Formula 6, X 31 It doesn't matter if it's there or not, X 31 If there is X 31 is a divalent group. 32 It doesn't matter if it's there or not, X 32 If there is X 32 is a divalent group. 33 It doesn't matter if it's there or not, X 33 If there is X 33 is a divalent group. 31 , R 32 are each independently a monovalent group. n31 and n32 are each independently an integer of 0 to 4. When n31 is an integer of 2 to 4, R 31 may be the same or different. When n32 is an integer of 2 to 4, R 32 may be the same or different. * indicates a bond.)

[0064] In Chemical Formula 6, X to the benzene ring 31 and X 32 The bonding position of X to the benzene ring is not limited. 31 and X 32 The bonding position of may be any of the ortho, meta and para positions. 32 and X 33 The bonding position of X to the benzene ring is not limited. 32 and X 33The bonding position may be any of the ortho, meta and para positions.

[0065] The divalent group containing two benzene rings is preferably represented by the following formula 7 from the viewpoint of improving storage properties under high temperature and humidity. (However, in Chemical Formula 7, X 34 is a divalent group. 33 , R 34 are each independently a monovalent group. n33 and n34 are each independently an integer of 0 to 4. When n33 is an integer of 2 to 4, R 33 may be the same or different. When n34 is an integer of 2 to 4, R 34 may be the same or different. * indicates a bond.)

[0066] X in Chemical Formula 2 0 is a divalent group containing two benzene rings, Z relative to the benzene rings in Chemical Formula 7 01 and X 34 The bonding position of Z to the benzene ring is not limited. 01 and X 34 The bonding position of may be any of the ortho, meta and para positions. 02 and X 34 The bonding position of Z to the benzene ring is not limited. 02 and X 34 The bonding position may be any of the ortho, meta and para positions.

[0067] X in Chemical Formula 3 1 is a divalent group containing two benzene rings, Z relative to the benzene rings in Chemical Formula 7 11 and X 34 The bonding position of Z to the benzene ring is not limited. 11 and X 34 The bonding position of may be any of the ortho, meta and para positions. 12 and X 34The bonding position of Z to the benzene ring is not limited. 12 and X 34 The bonding position may be any of the ortho, meta and para positions.

[0068] (X 31 , X 32 , X 33 ) X in Chemical Formula 6 31 , X 32 , X 33 are each independently a divalent group, and are not particularly limited, but an example thereof is a hydrocarbon group which may have a substituent. 21 , X 22 is the same as:

[0069] (X 34 ) X in Chemical Formula 7 34 is not particularly limited as long as it is a divalent group, but an example thereof is a hydrocarbon group which may have a substituent. 21 , X 22 is the same as:

[0070] (R 31 , R 32 ) R in Chemical Formula 6 31 , R 32 is a monovalent group and is not particularly limited, but examples thereof include a halogen group and a hydrocarbon group which may have a substituent. The halogen group and the hydrocarbon group which may have a substituent are each represented by R in Chemical Formula 4 above. 21 is the same as:

[0071] (R 33 , R 34 ) R in Chemical Formula 7 33 , R 34 is a monovalent group and is not particularly limited, but examples thereof include a halogen group and a hydrocarbon group which may have a substituent. The halogen group and the hydrocarbon group which may have a substituent are each represented by R in Chemical Formula 4 above. 21 is the same as:

[0072] (Y 01 , Y 02 ) Y in Chemical Formula 201 , Y 02 are each independently, for example, a hydrogen group (-H), a hydroxy group (-OH), a halogen group (-X), a carboxy group (-COOH), an ester group (-COOR), or a hydrocarbon group which may have a substituent.

[0073] The halogen group is, for example, a fluorine group (--F), a chlorine group (--Cl), a bromine group (--Br), or an iodine group (--I).

[0074] The hydrocarbon group which may have a substituent has, for example, 1 to 15 carbon atoms, 1 to 13 carbon atoms, 1 to 12 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 3 carbon atoms.

[0075] Examples of the substituent that may have a hydrocarbon group include a halogen group (e.g., a fluorine group) and an alkyl group having a halogen group (e.g., a fluorine group). The hydrocarbon group that may have a substituent may be one in which some of the carbon atoms of the hydrocarbon group (e.g., some of the carbon atoms contained in the main chain of the hydrocarbon group) are substituted with an element such as oxygen.

[0076] In Chemical Formula 2, (Y 01 ) n01 and / or (Y 02 ) n02 Preferably, one of the groups Y is a hydroxy group (—OH). 01 ) n01 and / or (Y 02 ) n02 When one of the groups is a hydroxy group (—OH), the display quality and light resistance can be improved.

[0077] (Y 11 , Y 12 , Y 13 , Y 14 In Chemical Formula 3, Y relative to the benzene ring 11 and Y 12 The bonding position of Y to the benzene ring is not limited. 11 and Y 12 The bonding position of may be any of the ortho, meta and para positions. 13 and Y14 The bonding position of Y to the benzene ring is not limited. 13 and Y 14 The bonding position of Y may be any of the ortho, meta and para positions. 11 and Y 12 and the bonding position of Y to the other benzene 13 and Y 14 may be the same as or different from the binding position of

[0078] Y in Chemical Formula 3 11 , Y 12 , Y 13 , Y 14 are each independently, for example, a hydrogen group (-H), a hydroxy group (-OH), a halogen group, a carboxy group (-COOH), an ester group (-COOR), or a hydrocarbon group which may have a substituent. The halogen group and the hydrocarbon group which may have a substituent are each represented by Y 01 , Y 02 is the same as:

[0079] In Chemical Formula 3, Y 11 and / or Y 13 is preferably a hydroxy group (—OH). 11 and / or Y 13 When the group is a hydroxy group (—OH), the display quality and light resistance can be improved.

[0080] (Z 01 , Z 02 ) Z in Chemical Formula 2 01 , Z 02 are each independently, for example, a urea bond (-NHCONH-), an amide bond (-NHCO-, -OCHN-) or a hydrazide bond (-NHCOCONH-). 01 , Z 02 is preferably a urea bond. 01 When Z is an amide bond, the nitrogen contained in the amide bond may be bonded to benzene, or the carbon contained in the amide bond may be bonded to benzene. 02is an amide bond, the nitrogen contained in the amide bond may be bonded to benzene, or the carbon contained in the amide bond may be bonded to benzene.

[0081] (Z 11 , Z 12 ) Z in Chemical Formula 3 11 , Z 12 are each independently, for example, a urea bond (-NHCONH-), an amide bond (-NHCO-, -OCHN-) or a hydrazide bond (-NHCOCONH-). 11 , Z 12 is preferably a urea bond. 11 When Z is an amide bond, the nitrogen contained in the amide bond may be bonded to benzene, or the carbon contained in the amide bond may be bonded to benzene. 12 is an amide bond, the nitrogen contained in the amide bond may be bonded to benzene, or the carbon contained in the amide bond may be bonded to benzene.

[0082] Other examples of the developing and reducing agents include 4,4'-isopropylidenebisphenol, 4,4'-isopropylidenebis(o-methylphenol), 4,4'-secondary butylidenebisphenol, 4,4'-isopropylidenebis(2-tertiary butylphenol), zinc p-nitrobenzoate, 1,3,5-tris(4-tertiary butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid, 2,2-(3,4'-dihydroxydiphenyl)propane, bis(4-hydroxy-3-methylphenyl)sulfide, 4-{β-( p-methoxyphenoxy)ethoxy}salicylic acid, 1,7-bis(4-hydroxyphenylthio)-3,5-dioxaheptane, 1,5-bis(4-hydroxyphenithio)-5-oxapentane, phthalic acid monobenzyl ester monocalcium salt, 4,4'-cyclohexylidene diphenol, 4,4'-isopropylidenebis(2-chlorophenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-butylidenebis(6-tert-butyl-2-methyl)phenol, 1,1,3-tris(2-methyl 4,4'-diphenylsulfone, 4-isopropoxy-4'-hydroxydiphenylsulfone (4-hydroxy-4'-isopropoxydiphenylsulfone), 4-benzyloxy-4'-hydroxydiphenylsulfone, 4,4'-diphenol sulfoxide, isopropyl p-hydroxybenzoate, p-hydroxybenzoic acid, 4,4'-diphenylsulfone, 4,4'-diphenylsulfone, 4,4'-diphenylsulfone, 4,4'-diphenylsulfone, 4,4'-diphenylsulfone, 4,4'-diphenylsulfone, 4,4'-diphenylsulfoxide, isopropyl p-hydroxybenzoate, Benzyl benzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,3-bis(4-hydroxyphenylthio)-propane, N,N'-diphenylthiourea, N,N'-di(m-chlorophenyl)thiourea, salicylanilide, bis(4-hydroxyphenyl)acetic acid methyl ester, bis(4-hydroxyphenyl)acetic acid benzyl ester, 1,3-bis(4-hydroxycumyl)benzene, 1,4-bis(4-hydroxycumyl)benzene, 2,4'-diphenol sulfone, 2,2'-diallyl-4,4'-Diphenol sulfone, 3,4-dihydroxyphenyl-4'-methyldiphenyl sulfone, zinc 1-acetyloxy-2-naphthoate, zinc 2-acetyloxy-1-naphthoate, zinc 2-acetyloxy-3-naphthoate, α,α-bis(4-hydroxyphenyl)-α-methyltoluene, antipyrine complex of zinc thiocyanate, tetrabromobisphenol A, tetrabromobisphenol S, 4,4'-thiobis(2-methylphenol), 4,4'-thiobis(2-chlorophenol), dodecylphosphonic acid, tetradecylphosphonic acid, hexadecylphosphonic acid, octadecylphosphonic acid, eicosylphosphonic acid, docosylphosphonic acid, tetracosylphosphonic acid, hexacosylphosphonic acid, octacosylphosphonic acid, α-hydroxydodecylphosphonic acid Examples of the compounds include α-hydroxytetradecylphosphonic acid, α-hydroxyhexadecylphosphonic acid, α-hydroxyoctadecylphosphonic acid, α-hydroxyeicosylphosphonic acid, α-hydroxydocosylphosphonic acid, α-hydroxytetracosylphosphonic acid, dihexadecyl phosphate, dioctadecyl phosphate, dieicosyl phosphate, didocosyl phosphate, monohexadecyl phosphate, monooctadecyl phosphate, monoeicosyl phosphate, monodocosyl phosphate, methylhexadecyl phosphate, methyloctadecyl phosphate, methyleicosyl phosphate, methyldocosyl phosphate, amylhexadecyl phosphate, octylhexadecyl phosphate, and laurylhexadecyl phosphate. The recording layers 13, 15, and 17 may contain the above-mentioned compounds as the developer / reduction agent either singly or in combination of two or more. ,

[0083] The photothermal conversion agent absorbs, for example, light in a predetermined wavelength range in the near-infrared region and generates heat. As the photothermal conversion agent, it is preferable to use a near-infrared absorbing dye that has an absorption peak in the wavelength range of 700 nm to 2500 nm and has almost no absorption in the visible region. Specific examples include compounds having a phthalocyanine skeleton (phthalocyanine dyes), compounds having a naphthalocyanine skeleton (naphthalocyanine dyes), compounds having a squarylium skeleton (squaryllium dyes), metal complexes such as dithio complexes, diimonium salts, aminium salts, and inorganic compounds. Examples of inorganic compounds include graphite, carbon black, metal powder particles, metal oxides such as tricobalt tetroxide, iron oxide, chromium oxide, copper oxide, titanium black, and ITO, metal nitrides such as niobium nitride, metal carbides such as tantalum carbide, metal sulfides, and various magnetic powders. In addition, compounds having a cyanine skeleton (cyanine dyes) with excellent light resistance and heat resistance may also be used.

[0084] "Excellent light resistance" means that the compound does not decompose upon laser irradiation. "Excellent heat resistance" means that the maximum absorption peak value of the absorption spectrum does not change by 20% or more when the compound is formed into a film together with a polymer material and stored at 150°C for 30 minutes. Examples of compounds having such a cyanine skeleton include those having, in the molecule, a counter ion selected from SbF6, PF6, BF4, ClO4, CF3SO3, and (CF3SO3)2N, and at least one methine chain containing a five-membered ring or a six-membered ring.

[0085] It is preferable that the cyanine dye has both one of the above counter ions and a cyclic structure such as a five-membered ring or a six-membered ring in the methine chain, but sufficient light resistance and heat resistance are ensured if it has at least one of them. Materials with excellent light resistance and heat resistance do not decompose upon laser irradiation, as described above. Light resistance can be confirmed, for example, by measuring the peak change in the absorption spectrum during a xenon lamp irradiation test. If the rate of change after 30 minutes of irradiation is 20% or less, the light resistance can be determined to be good. Heat resistance can be confirmed, for example, by measuring the peak change in the absorption spectrum during storage at 150°C. If the rate of change after 30 minutes of testing is 20% or less, the heat resistance can be determined to be good.

[0086] The polymer material is preferably one that allows the color former, color-developing / color-reducing agent, and photothermal conversion agent to be easily and homogeneously dispersed. Furthermore, the polymer material preferably has high transparency to ensure high visibility of the information written to the recording layer 11, and is preferably one that is highly soluble in organic solvents, for example. Examples of polymer materials include thermosetting resins and thermoplastic resins. Specific examples include polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymers, ethyl cellulose, polystyrene, styrene-based copolymers, phenoxy resins, polyesters, aromatic polyesters, polyurethanes, polycarbonates, polyacrylic acid esters, polymethacrylic acid esters, acrylic acid-based copolymers, maleic acid-based polymers, polyvinyl alcohol, modified polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, and starch.

[0087] The recording layers 13, 15, and 17 are each configured to contain at least one of the above-mentioned color former, color developer / reduction agent, and photothermal conversion agent. The color former and color developer / reduction agent contained in the recording layers 13, 15, and 17 preferably have a weight ratio of color former:color developer / reduction agent=1:2. The photothermal conversion agent varies depending on the film thickness of the recording layers 13, 15, and 17. In addition to the above-mentioned materials, the recording layers 13, 15, and 17 may also contain various additives such as sensitizers and ultraviolet absorbers.

[0088] The protective layer 18 may have a function of suppressing the intrusion of moisture and / or oxygen into the recording layers 13, 15, and 17. The protective layer 18 covers the surface of the recording layer 17. The protective layer 18 has a density of, for example, 0.001 g / m 2 / day or more 10g / m 2 It is preferable that the protective layer 18 has a water vapor transmission rate of 1000 kJ / day or less. Similarly to the polymeric material constituting the recording layers 13, 15, and 17, it is also preferable that the protective layer 18 has high transparency in order to obtain high visibility of information written in the recording layers 13, 15, and 17. Examples of such protective layers 18 include laminated films in which an inorganic oxide film is provided on a substrate made of a plastic film. The protective layer 18, which is constituted as a laminated film of a plastic film and an inorganic oxide film, covers the recording layer 17 so that, for example, the inorganic oxide film faces the recording layer 17 side (inside) and the plastic film faces the outside.

[0089] The plastic film used as the substrate may be, for example, an industrial plastic film, such as polyethylene terephthalate (PET), polycarbonate (PC), or polymethyl methacrylate (PMMA). The thickness of the plastic film is preferably, for example, 5 μm or more and 100 μm or less.

[0090] The inorganic oxide film may be, for example, a silicon oxide film (SiO x film), aluminum oxide film (AlO x film) and silicon nitride film (SiN x The thickness of the protective layer 18 is preferably, for example, from 10 nm to 1 μm.

[0091] Next, an example of writing information in the drawing system 100 according to the present embodiment will be described.

[0092] [Writing] First, the user prepares an uncolored recording medium 10 and places it on the Y stage 57. Next, the user transmits input image data described in the RGB color space from a terminal device via a network to the drawing system 100. Upon receiving the input image data via the network, the drawing system 100 executes the following drawing process.

[0093] First, when the information processing unit 160 receives input image data via the communication unit 110, it converts the input image data described in the RGB color space into leuco image data described in the leuco color space. Next, the information processing unit 160 derives a voltage value file (a list of command voltage values) based on the gradation values ​​of each color at each drawing coordinate of the leuco image data obtained by the conversion. The information processing unit 160 transmits the derived voltage value file (a list of command voltage values) to the drawing unit 150.

[0094] The signal processing circuit 51 of the drawing unit 60 acquires the voltage value file (list of command voltage values) input from the information processing unit 160 as an image signal Din. The signal processing circuit 51 generates an image signal from the image signal Din in synchronization with the scanner operation of the X scanner unit 55, according to characteristics such as the wavelength of the laser light. The signal processing circuit 51 generates a projection image signal that causes the laser light to be emitted in accordance with the generated image signal. The signal processing circuit 51 outputs the generated projection image signal to the laser driving circuit 52 of the drawing unit 150.

[0095] The laser driving circuit 52 drives the light sources 53A, 53B, and 53C of the light source unit 53 in accordance with the projection video signals corresponding to the respective wavelengths. At this time, the laser driving circuit 52 causes at least one of the light sources 53A, 53B, and 53C to emit laser light and scan the recording medium 10.

[0096] For example, to color the recording layer 17, laser light La having an emission wavelength λ1 is irradiated onto the recording layer 17 with enough energy to raise the recording layer 17 to its color temperature. This generates heat in the photothermal conversion agent contained in the recording layer 17, causing a color reaction (color development reaction) between the color former and the color-developing / color-reducing agent, resulting in the irradiated portion developing a color, for example, yellow. Similarly, to color the recording layer 15, laser light Lb having an emission wavelength λ2 is irradiated onto the recording layer 15 with enough energy to raise the recording layer 15 to its color temperature, resulting in the irradiated portion developing a color, for example, cyan. To color the recording layer 13, laser light Lc having an emission wavelength λ3 is irradiated onto the recording layer 13 with enough energy to raise the recording layer 13 to its color temperature, resulting in the irradiated portion developing a color, for example, cyan. In this way, by irradiating any portion with laser light of the corresponding wavelength, it is possible to record a pattern, etc. (e.g., a full-color pattern, etc.).

[0097] 4 shows how information is written to the recording medium 10 by the drawing unit 150. Fig. 4 illustrates an example of the cross-sectional configuration of the recording medium 10, and further illustrates how laser beams La, Lb, and Lc are scanned from left to right on the page with predetermined gaps ΔX1 and ΔX2 between them.

[0098] In this embodiment, a mechanism consisting of scanner drive circuit 54, X scanner unit 55, Y stage drive circuit 56, and Y stage 57 functions as a scanning unit that irradiates the surface of recording medium 10 with multiple laser beams La, Lb, and Lc generated by light source unit 53 via predetermined gaps ΔX1 and ΔX2. This mechanism further scans the surface of recording medium 10 with the multiple laser beams La, Lb, and Lc in the same direction and in synchronization with each other. This mechanism scans the surface of recording medium 10 with the multiple laser beams La, Lb, and Lc in a state where multiple irradiation spots Pa, Pb, and Pc produced by the multiple laser beams La, Lb, and Lc are aligned at predetermined gaps ΔX1 and ΔX2 in the same direction as the scanning direction (X-axis direction) of the multiple laser beams La, Lb, and Lc.

[0099] The gap ΔX1 between the irradiation spot Pa of the laser beam La and the irradiation spot Pb of the laser beam Lb is preferably large enough to prevent the high-temperature region Ra generated in the recording layer 13 and its periphery by the laser beam La from overlapping with the high-temperature region Rb generated in the recording layer 15 and its periphery by the laser beam Lb. Also, the gap ΔX2 between the irradiation spot Pb of the laser beam Lb and the irradiation spot Pc of the laser beam Lc is preferably large enough to prevent the high-temperature region Rb generated in the recording layer 15 and its periphery by the laser beam Lb from overlapping with the high-temperature region Rc generated in the recording layer 17 and its periphery by the laser beam Lc.

[0100] The scanning order of the multiple laser beams La, Lb, and Lc on the surface of the recording medium 10 may be, for example, as shown in Fig. 4, an order that allows color development in the recording layers 13, 15, and 17 in order from the layer closest to the outermost surface of the recording medium 10. The scanning order of the multiple laser beams La, Lb, and Lc on the surface of the recording medium 10 may be, for example, an order that allows color development in the recording layers 13, 15, and 17 in order from the layer closest to the substrate 11 (the layer farthest from the outermost surface of the recording medium 10).

[0101] [Effects] Next, the effects of the drawing system 100 according to the present embodiment will be described in comparison with a comparative example. Figures 5 and 6 show how information is written to the recording medium 10 in the comparative example.

[0102] In the comparative example shown in Figure 5, the laser beams La, Lb, and Lc irradiate the same spot P1 (same pixel) on the recording medium 10. Therefore, the high-temperature region Ra and the high-temperature region Rb partially overlap each other, and the high-temperature region Rb and the high-temperature region Rc partially overlap each other. As a result, in the comparative example shown in Figure 5, thermal crosstalk occurs between two adjacent recording layers in the stacking direction, resulting in unexpected writing or erasure. Therefore, the comparative example shown in Figure 5 has the problem of poor image quality.

[0103] In the comparative example shown in Figure 6, the laser beams La, Lb, and Lc are sequentially irradiated onto the entire recording medium 10. This prevents the high-temperature regions Ra and Rb from overlapping, and also prevents the high-temperature regions Rb and Rc from overlapping. Therefore, the comparative example shown in Figure 6 has good image quality. However, it takes three times as long to image compared to the comparative example shown in Figure 5.

[0104] On the other hand, in this embodiment, a plurality of laser beams La, Lb, and Lc generated by the light source unit 53 are irradiated onto the surface of the recording medium 10 via predetermined gaps ΔX1 and ΔX2, and the plurality of laser beams La, Lb, and Lc are scanned synchronously in the same direction on the surface of the recording medium 10. This makes it possible to reduce the occurrence of thermal crosstalk between the recording layers 13 and 15 adjacent to each other in the stacking direction or between the recording layers 15 and 17 adjacent to each other in the stacking direction. As a result, it is possible to reduce the possibility of unexpected writing or erasure occurring.

[0105] Furthermore, in this embodiment, the multiple laser beams La, Lb, and Lc are scanned on the surface of the recording medium 10 with the irradiation spots Pa, Pb, and Pc aligned at predetermined intervals ΔX1 and ΔX2 in the same direction as the scanning direction (X-axis direction) of the multiple laser beams La, Lb, and Lc. This makes it possible to reduce thermal crosstalk between the recording layers 13 and 15 adjacent to each other in the stacking direction or between the recording layers 15 and 17 adjacent to each other in the stacking direction. As a result, it is possible to reduce the possibility of unexpected writing or erasure.

[0106] Furthermore, in this embodiment, a mechanism for scanning the multiple laser beams La, Lb, and Lc in the X-axis direction and a Y-stage 47 for moving the recording medium 10 in the Y-axis direction are provided, which makes it possible to achieve raster scanning while reducing the occurrence of thermal crosstalk.

[0107] In this embodiment, raster scanning is performed by scanning the multiple laser beams La, Lb, and Lc in the X-axis direction while moving the Y-stage 47 in the Y-axis direction, thereby achieving raster scanning while reducing the occurrence of thermal crosstalk.

[0108] Furthermore, in this embodiment, the multiple laser beams La, Lb, and Lc are output to the X scanner unit 55 with the optical axes of the multiple laser beams La, Lb, and Lc shifted from one another. As a result, the multiple laser beams La, Lb, and Lc are irradiated onto the surface of the recording medium 10 via predetermined gaps ΔX1 and ΔX2, which can reduce the occurrence of thermal crosstalk between the recording layers 13 and 15 adjacent to one another in the stacking direction, or between the recording layers 15 and 17 adjacent to one another in the stacking direction. As a result, the possibility of unexpected writing or erasure can be reduced.

[0109] Furthermore, in this embodiment, the multiple laser beams La, Lb, and Lc are output to the X scanner unit 55 so that the optical axes of the multiple laser beams La, Lb, and Lc are parallel to one another via predetermined gaps ΔX1 and ΔX2. As a result, the multiple laser beams La, Lb, and Lc are irradiated onto the surface of the recording medium 10 via the predetermined gaps ΔX1 and ΔX2, which can reduce the occurrence of thermal crosstalk between the recording layers 13 and 15 adjacent to one another in the stacking direction, or between the recording layers 15 and 17 adjacent to one another in the stacking direction. As a result, the possibility of unexpected writing or erasure can be reduced.

[0110] Furthermore, in this embodiment, the multiple laser beams La, Lb, and Lc are output to the X-scanner unit 55 so that the optical axes of the multiple laser beams La, Lb, and Lc intersect with each other at a predetermined angle. As a result, the multiple laser beams La, Lb, and Lc are irradiated onto the surface of the recording medium 10 via predetermined gaps ΔX1 and ΔX2, which reduces the occurrence of thermal crosstalk between the recording layers 13 and 15 adjacent to each other in the stacking direction, or between the recording layers 15 and 17 adjacent to each other in the stacking direction. As a result, the possibility of unexpected writing or erasure can be reduced.

[0111] 2. Modifications Modifications of the drawing system 100 according to an embodiment of the present disclosure will be described below.

[0112] [Variation A] Fig. 7 shows a variation of the schematic configuration of the drawing system 100 according to the above embodiment. In the above embodiment, raster scanning is achieved by scanning the laser beams La, Lb, and Lc in the X-axis direction using the X scanner unit 55 and moving the Y stage 57 in the Y-axis direction. However, in the above embodiment, raster scanning may be achieved by using an XY scanner driving circuit 54A, an XY scanner unit 55A, and a fixed stage 57A instead of the scanner driving circuit 54, the X scanner unit 55, the Y stage driving circuit 56, and the Y stage 57, as shown in Fig. 7, for example.

[0113] The XY scanner drive circuit 54A drives the XY scanner unit 55A based on, for example, a control signal input from the signal processing circuit 51. Furthermore, when a signal regarding the irradiation angle of a biaxial scanner 55c (described later) or the like is input from the XY scanner unit 55A, the XY scanner drive circuit 54A drives the XY scanner unit 55A based on the signal so as to achieve a desired irradiation angle.

[0114] The XY scanner unit 55A, for example, scans the laser beams La, Lb, and Lc incident from the light source unit 53 in the X-axis direction on the surface of the recording medium 10, while moving the scan line in the Y-axis direction at a predetermined step width. The XY scanner unit 55A includes, for example, a biaxial scanner 55c and an fθ lens 55b. The biaxial scanner 55c is, for example, a galvanometer mirror that scans the laser beams La, Lb, and Lc incident from the light source unit 53 in the X-axis direction on the surface of the recording medium 10 based on a drive signal input from the XY scanner drive circuit 54A, while moving the scan line in the Y-axis direction at a predetermined step width. The fθ lens 55b converts the uniform rotational motion of the biaxial scanner 55c into uniform linear motion of a spot moving on the focal plane (the surface of the recording medium 10). The fixed stage 57A simply supports the recording medium 10.

[0115] In this modification, an XY scanner unit 55A is provided that scans the plurality of laser beams La, Lb, and Lc in the X-axis direction and moves the scan lines of the plurality of laser beams La, Lb, and Lc in the Y-axis direction at predetermined step widths, thereby realizing raster scanning while reducing the occurrence of thermal crosstalk.

[0116] In this embodiment, raster scanning is performed by scanning the recording medium 10 with the laser beams La, Lb, and Lc in the X-axis direction while moving the scan lines of the laser beams La, Lb, and Lc in the Y-axis direction at predetermined step widths while keeping the recording medium 10 stationary. This makes it possible to achieve raster scanning while reducing the occurrence of thermal crosstalk.

[0117] [Variation B] Fig. 8 shows a variation of the schematic configuration of the drawing system 100 according to the above embodiment. In the above embodiment, raster scanning is achieved by scanning the laser beams La, Lb, and Lc in the X-axis direction using the X scanner unit 55 and moving the Y stage 57 in the Y-axis direction. However, in the above embodiment, raster scanning may be achieved by using a light source unit 53D instead of the light source unit 53, and by using an XY stage driving circuit 56A and an XY stage 57B instead of the scanner driving circuit 54, the X scanner unit 55, the Y stage driving circuit 56, and the Y stage 57, as shown in Fig. 8, for example.

[0118] The light source unit 53D corresponds to the light source unit 53 further equipped with a condenser lens 53e that condenses the laser beams La, Lb, and Lc. The XY stage drive circuit 56A drives the XY stage 57B based on, for example, a control signal input from the signal processing circuit 51. The XY stage 57B moves the XY stage 57B in the X-axis direction at a predetermined speed and in the Y-axis direction in predetermined step widths. The operation of the XY stage 57B causes the laser beams La, Lb, and Lc to raster scan the surface of the recording medium 10.

[0119] In this modification, an XY stage 57B is provided that scans the plurality of laser beams La, Lb, and Lc in the X-axis direction and moves the scan lines of the plurality of laser beams La, Lb, and Lc in the Y-axis direction at predetermined step widths, thereby realizing raster scanning while reducing the occurrence of thermal crosstalk.

[0120] 9 shows a modification of the schematic configuration of the imaging system 100 according to the above embodiment. In the above embodiment, an optical system including a dichroic mirror 53b and the like is used to output the laser beams La, Lb, and Lc aligned in a predetermined direction with a predetermined gap therebetween. However, in the above embodiment, by using a light source unit 53E instead of the light source unit 53, the laser beams La, Lb, and Lc may be output aligned in a predetermined direction with a predetermined gap therebetween.

[0121] As shown in FIG. 9, the light source unit 53E includes, for example, three light sources 53A, 53B, and 53C, three optical fibers 53f, 53g, and 53h, a fiber folder 53i, and a condenser lens 53j.

[0122] The optical fiber 53f is connected to the light source 53A and transmits the laser beam La emitted from the light source 53A. The optical fiber 53g is connected to the light source 53B and transmits the laser beam Lb emitted from the light source 53B. The optical fiber 53h is connected to the light source 53C and transmits the laser beam Lc emitted from the light source 53C. The fiber folder 53i holds the tip portions of the three optical fibers 53f, 53g, and 53h aligned in a predetermined direction. The condensing lens 53j condenses the laser beams La, Lb, and Lc emitted from the tip portions of the three optical fibers 53f, 53g, and 53h. The laser beams La, Lb, and Lc condensed by the condensing lens 53j are output to the X scanner unit 55.

[0123] In this modification, multiple laser beams La, Lb, and Lc are output to the X scanner unit 55 via optical fibers 53f, 53g, and 53h, which are provided separately for each laser beam La, Lb, and Lc. As a result, the multiple laser beams La, Lb, and Lc are irradiated onto the surface of the recording medium 10 via predetermined gaps ΔX1 and ΔX2, which reduces the occurrence of thermal crosstalk between the recording layers 13 and 15 adjacent to each other in the stacking direction and between the recording layers 15 and 17 adjacent to each other in the stacking direction. As a result, the possibility of unexpected writing or erasure can be reduced.

[0124] [Variation D] Figure 10 shows a variation of the schematic configuration of the imaging system 100 according to Variation A. In Variation A, an optical system including a dichroic mirror 53b and the like is used to output laser beams La, Lb, and Lc aligned in a predetermined direction with a predetermined gap therebetween. However, in Variation A, by using a light source unit 53E instead of the light source unit 53, laser beams La, Lb, and Lc may be output aligned in a predetermined direction with a predetermined gap therebetween. Even in this case, raster scanning can be achieved while reducing the occurrence of thermal crosstalk.

[0125] [Variation E] Figure 11 shows a variation of the schematic configuration of the imaging system 100 according to Variation B. In Variation B, an optical system including a dichroic mirror 53b and the like is used to output laser beams La, Lb, and Lc aligned in a predetermined direction with a predetermined gap therebetween. However, in Variation B, a light source unit 53F may be used instead of the light source unit 53, so that the laser beams La, Lb, and Lc are aligned in a predetermined direction with a predetermined gap therebetween. For example, as shown in Figure 11, the light source unit 53F includes three light sources 53A, 53B, and 53C, three optical fibers 53f, 53g, and 53h, a fiber folder 53i, and a condenser lens 53e. Even in this case, raster scanning can be achieved while reducing thermal crosstalk.

[0126] [Variation F] Figure 12 shows a variation of the drawing method in the drawing system 100 according to the above-described embodiment and its variations. In the above-described embodiment and its variations, the laser beams La, Lb, and Lc scan in a direction parallel to the X-axis direction with a predetermined gap therebetween. However, as shown in Figure 12, for example, the laser beams La, Lb, and Lc may be scanned in the X-axis direction while being aligned at a predetermined gap in a direction perpendicular to the X-axis direction (Y-axis direction). In this case, a mechanism capable of performing such scanning scans the surface of the recording medium 10 with the laser beams La, Lb, and Lc, generating multiple irradiation spots Pa, Pb, and Pc, aligned at a predetermined gap in a direction perpendicular to the scanning direction (X-axis direction) of the laser beams La, Lb, and Lc.

[0127] In this modification, the light source unit 53 has, for example, an optical system that outputs a plurality of laser beams (e.g., three laser beams La, Lb, and Lc) emitted from a plurality of light sources (e.g., three light sources 53A, 53B, and 53C) in a line along the Y axis direction with a predetermined gap therebetween. This optical system outputs the plurality of laser beams La, Lb, and Lc to the X scanner unit 55, for example, so that the plurality of irradiation spots Pa, Pb, and Pc are lined up in this order along the Y axis direction on the Y stage 57 with a predetermined gap therebetween.

[0128] Here, the irradiation spot Pa moves on a line L1 corresponding to a certain pixel row on the recording medium 10. The irradiation spot Pa moves on a line L1 corresponding to a certain pixel row on the recording medium 10. The irradiation spot Pb moves on a line L2 corresponding to a pixel row that is a predetermined distance away from the pixel row on the recording medium 10 along which the irradiation spot Pa moves. The irradiation spot Pc moves on a line L3 corresponding to a pixel row that is a predetermined distance away from the pixel row on the recording medium 10 along which the irradiation spot Pb moves.

[0129] 13, 14, and 15 show an example of a drawing procedure in the drawing system 100 according to this modified example.

[0130] The imaging system 100 first irradiates the recording medium 10 with the laser beam La and scans the irradiation spot Pa in the X-axis direction. After scanning one line of the irradiation spot Pa, the imaging system 100 temporarily stops irradiating the recording medium 10 with the laser beam La and moves the Y stage 47 in the Y-axis direction, thereby moving the recording medium 10 a predetermined distance in the Y-axis direction. The imaging system 100 then irradiates the recording medium 10 with the laser beam La at a location a predetermined distance away from the previously scanned line, thereby scanning the irradiation spot Pa in the X-axis direction. In this manner, the imaging system 100 scans the recording medium 10 with the laser beam La in the X-axis direction multiple times (see FIG. 13 ). At this time, a portion of the recording layer 13 of the recording medium 10 is colored in a predetermined color (Color A) due to the irradiation of the laser beam La.

[0131] Next, the drawing system 100 irradiates the recording medium 10 with laser beams La and Lb, and scans the irradiation spots Pa and Pb in the X-axis direction. At this time, the drawing system 100 irradiates the line on the recording medium 10 that has been scanned with the laser beam La with laser beam Lb, and scans the irradiation spot Pb in the X-axis direction. Then, when scanning of one line of the irradiation spots Pa and Pb is completed, the drawing system 100 temporarily stops the irradiation of the laser beams La and Pb, and moves the Y stage 47 in the Y-axis direction, thereby moving the recording medium 10 a predetermined distance in the Y-axis direction.

[0132] Next, the imaging system 100 irradiates the laser beams La and Lb at locations a predetermined distance away from the line scanned immediately before, and scans the irradiation spots Pa and Pb in the X-axis direction. At this time, the imaging system 100 also irradiates the line on the recording medium 10 that has been scanned with the laser beam La with the laser beam Lb, and scans the irradiation spot Pb in the X-axis direction. In this way, the imaging system 100 scans the recording medium 10 in the X-axis direction with the laser beams La and Lb multiple times (see FIG. 14 ).

[0133] At this time, in the recording medium 10, a part of the recording layer 13 develops a predetermined color (Color A) due to irradiation with the laser beam La, and further, a part of the recording layer 15 develops a predetermined color (Color B) due to irradiation with the laser beam Lb. In the recording medium 10, the part where both the recording layers 13 and 15 develop colors when viewed from the stacking direction develops a composite color of Color A and Color B.

[0134] Next, the drawing system 100 irradiates the recording medium 10 with laser beams La, Lb, and Lc, and scans the irradiation spots Pa, Pb, and Pc in the X-axis direction. At this time, the drawing system 100 irradiates the line on the recording medium 10 that has been scanned with the laser beam La with laser beam Lb, and scans the irradiation spot Pb in the X-axis direction. Furthermore, the drawing system 100 irradiates the line on the recording medium 10 that has been scanned with the laser beam Lb with laser beam Lc, and scans the irradiation spot Pc in the X-axis direction. Then, when scanning of one line of the irradiation spots Pa, Pb, and Pc is completed, the drawing system 100 temporarily stops irradiating the recording medium 10 with the laser beams La, Pb, and Lc, and moves the Y stage 47 in the Y-axis direction, thereby moving the recording medium 10 a predetermined distance in the Y-axis direction.

[0135] Next, the imaging system 100 irradiates the laser beams La, Lb, and Lc at locations a predetermined distance away from the line scanned immediately before, and scans the irradiation spots Pa, Pb, and Pc in the X-axis direction. At this time, the imaging system 100 also irradiates the line on the recording medium 10 scanned with the laser beam La with the laser beam Lb, and scans the irradiation spot Pb in the X-axis direction. Furthermore, the imaging system 100 irradiates the line on the recording medium 10 scanned with the laser beam Lb with the laser beam Lc, and scans the irradiation spot Pc in the X-axis direction. In this way, the imaging system 100 scans the recording medium 10 in the X-axis direction with the laser beams La, Lb, and Lc multiple times (see FIG. 15 ).

[0136] At this time, in the recording medium 10, a part of the recording layer 13 develops a predetermined color (Color A) due to irradiation with the laser beam La, and a part of the recording layer 15 develops a predetermined color (Color B) due to irradiation with the laser beam Lb, and a part of the recording layer 17 develops a predetermined color (Color C) due to irradiation with the laser beam Lc. In the recording medium 10, the parts where all of the recording layers 13, 15, and 17 develop colors when viewed from the stacking direction develop a composite color (e.g., black) of Color A, Color B, and Color C.

[0137] The distance Δy1 between the irradiation spot Pa and the irradiation spot Pb is set, for example, so that the period from when the laser beam La is irradiated onto a predetermined pixel on the recording medium 10 until the laser beam Lb is irradiated onto it (the cooling period Δt1 at the predetermined pixel) is 0.2 seconds or more. The distance Δy2 between the irradiation spot Pb and the irradiation spot Pc is set, for example, so that the period from when the laser beam Lb is irradiated onto a predetermined pixel on the recording medium 10 until the laser beam Lc is irradiated onto it (the cooling period Δt2 at the predetermined pixel) is 0.2 seconds or more. The distance Δy1 and the distance Δy2 may be equal to each other or different from each other. The cooling periods Δt1 and Δt2 may be equal to each other or different from each other.

[0138] When focusing on a specific pixel on the recording medium 10, the timings at which the laser beam La is irradiated, the timings at which the laser beam Lb is irradiated, and the timings at which the laser beam Lc is irradiated are all different. This results in cooling periods Δt1 and Δt2 being provided for each pixel on the recording medium 10. Furthermore, since the cooling periods Δt1 and Δt2 are 0.2 seconds or longer as described above, the next laser irradiation can be performed with each pixel sufficiently cooled. As a result, the thermal crosstalk that occurs in the comparative example shown in FIG. 5 can be prevented, and good drawing quality can be obtained. The cooling periods Δt1 and Δt2 do not necessarily need to be 0.2 seconds or longer and can be set according to the desired drawing quality.

[0139] FIG. 16 shows experimental results for the comparative example shown in FIG. 5 and multiple examples in which various distances Δy1 and Δy2 are set in this modified example. In FIG. 16, ΔE_avg represents the average color difference ΔE* of each example compared to the comparative example when a black image was printed on the recording medium 10. In FIG. 16, the judgment represents the result of whether the average color difference ΔE* is equal to or less than the upper limit of 6.5 of the B-class tolerance. If the average color difference ΔE* is equal to or less than the upper limit of 6.5 of the B-class tolerance, the judgment is ◯ (pass). On the other hand, if the average color difference ΔE* exceeds the upper limit of 6.5 of the B-class tolerance, the judgment is × (fail). In FIG. 16, the tact time represents the time required to print a black image on the recording medium 10. In FIG. 16, the tact time is expressed as a value based on the tact time of the comparative example. From FIG. 16, it can be seen that in Examples 6 to 11, the evaluation was good (passed), and that in Examples 1 to 11, the tact time was one-third of that of the comparative example.

[0140] In this modified example, raster scanning may be achieved by using an XY scanner driving circuit 54A, an XY scanner unit 55A, and a fixed stage 57A instead of the scanner driving circuit 54, the X scanner unit 55, the Y stage driving circuit 56, and the Y stage 57.

[0141] [Variation G] FIG. 17 shows a variation of the drawing method in the drawing system 100 according to Variation F. In Variation F, the laser beams La, Lb, and Lc are aligned at a predetermined interval in the direction perpendicular to the X-axis (Y-axis direction) and scanned in the X-axis direction. However, as shown in FIG. 17 , the laser beams La, Lb, and Lc may be aligned at a predetermined interval in the X-axis direction and scanned in the X-axis direction in a direction obliquely intersecting both the X-axis and Y-axis directions. That is, the irradiation spots Pa, Pb, and Pc do not have to be aligned in a straight line parallel to the Y-axis, and the irradiation spots Pb and Pc may be shifted relative to the irradiation spot Pa not only in the X-axis direction but also in the Y-axis direction. In this case, a mechanism capable of performing such scanning scans the surface of the recording medium 10 with the laser beams La, Lb, and Lc, generating multiple irradiation spots Pa, Pb, and Pc, aligned at a predetermined interval in the direction obliquely intersecting both the X-axis and Y-axis directions.

[0142] In this modification, the light source unit 53 has an optical system that outputs multiple laser beams (e.g., three laser beams La, Lb, and Lc) emitted from multiple light sources (e.g., three light sources 53A, 53B, and 53C) aligned in a direction obliquely intersecting both the X-axis and Y-axis directions with a predetermined gap therebetween. This optical system outputs the multiple laser beams La, Lb, and Lc to the X scanner unit 55 so that the multiple irradiation spots Pa, Pb, and Pc are aligned in this order on the Y stage 57 with a predetermined gap therebetween in a direction obliquely intersecting both the X-axis and Y-axis directions. Even in this case, as with the modification F, the thermal crosstalk that occurs in the comparative example shown in FIG. 5 can be prevented, and good drawing quality can be obtained.

[0143] In this modification, the irradiation spots Pa, Pb, and Pc do not have to be aligned in a straight line, and the deviation of the irradiation spots Pa, Pb, and Pc from a line parallel to the Y axis may be set to any amount. In this case, the scanning mechanism in the imaging system 100 may scan the multiple laser beams La, Lb, and Lc on the surface of the recording medium 10 in a state where the lines scanned by the laser beams La, Lb, and Lc do not overlap each other (i.e., in a state where the multiple laser beams La, Lb, and Lc do not scan the same line). Even in this case, as with the modification F, it is possible to prevent the thermal crosstalk that occurs in the comparative example shown in FIG. 5 and obtain good imaging quality.

[0144] In this modified example, raster scanning may be achieved by using an XY scanner driving circuit 54A, an XY scanner unit 55A and a fixed stage 57A instead of the scanner driving circuit 54, the X scanner unit 55, the Y stage driving circuit 56 and the Y stage 57.

[0145] In the above embodiment and its modifications, the laser driving circuit 52 may, for example, pulse-drive the light sources 53A, 53B, and 53C of the light source unit 53, or may continuously drive them while scanning one line. When continuously driving the light sources 53A, 53B, and 53C, the laser driving circuit 52 may set the power of at least one of the light sources 53A, 53B, and 53C to zero depending on the color to be expressed.

[0146] Note that the effects described in this specification are merely examples. The effects of the present disclosure are not limited to the effects described in this specification. The present disclosure may have effects other than the effects described in this specification.

[0147] Furthermore, for example, the present disclosure can be configured as follows: (1) An imaging system for performing imaging on a recording medium having multiple recording layers stacked via a heat-insulating layer, each recording layer containing a different color-developing compound and a different photothermal conversion agent, the imaging system comprising: a light source unit that generates multiple laser beams having different wavelengths that correspond to the absorption wavelengths of the photothermal conversion agents; and a scanning unit that irradiates the surface of the recording medium with the multiple laser beams generated by the light source unit via a predetermined gap and scans the multiple laser beams in the same direction on the surface of the recording medium in synchronization with each other, wherein the scanning unit scans the surface of the recording medium with the multiple laser beams in a state where irradiation spots formed by the multiple laser beams are aligned at predetermined gaps in a direction perpendicular to or obliquely intersecting with the scanning direction of the multiple laser beams. (2) The imaging system described in (1), wherein the scanning unit scans a line on the recording medium that has been scanned with a first laser beam of the multiple laser beams with a second laser beam different from the first laser beam of the multiple laser beams. (3) The drawing system according to (1) or (2), wherein the scanning unit includes an optical system that scans the plurality of laser beams in a first direction and a stage that moves the recording medium in a second direction perpendicular to the first direction. (4) The drawing system according to (1) or (2), wherein the scanning unit includes an optical system that scans the plurality of laser beams in the first direction and moves scan lines of the plurality of laser beams in a second direction perpendicular to the first direction by a predetermined step width. (5) The drawing system according to any one of (1) to (4), wherein the light source unit outputs the plurality of laser beams to the scanning unit with the optical axes of the plurality of laser beams shifted from one another. (6) The drawing system according to (5), wherein the light source unit outputs the plurality of laser beams to the scanning unit such that the optical axes of the plurality of laser beams are parallel to one another with a predetermined gap between them. (7) The drawing system according to (5), wherein the light source unit outputs the plurality of laser beams to the scanning unit such that the optical axes of the plurality of laser beams intersect with one another at a predetermined angle.(8) The drawing system described in (5), wherein the light source unit outputs the plurality of laser beams to the scanning unit via optical fibers provided separately for each laser beam. (9) A drawing method for performing drawing on a recording medium having a plurality of recording layers stacked via a heat insulating layer, each recording layer containing a different color developing compound and a different photothermal conversion agent, the drawing method including: generating a plurality of laser beams having different wavelengths that correspond to the absorption wavelengths of the photothermal conversion agents; irradiating the surface of the recording medium with the generated laser beams via a predetermined gap, and synchronously scanning the surface of the recording medium with the plurality of laser beams in the same direction; and scanning the surface of the recording medium with the plurality of laser beams in a state where irradiation spots formed by the plurality of laser beams are aligned at predetermined gaps in a direction perpendicular to or obliquely intersecting the scanning direction of the plurality of laser beams. (10) The drawing method described in (9), comprising scanning a line on the recording medium scanned with a first laser beam of the plurality of laser beams with a second laser beam different from the first laser beam of the plurality of laser beams. (11) The drawing method according to (9), which includes performing raster scanning by scanning the plurality of laser beams in a first direction and moving the recording medium in a second direction perpendicular to the first direction. (12) The drawing method according to (9), which includes performing raster scanning by scanning the plurality of laser beams in the first direction while keeping the recording medium stationary and moving scan lines of the plurality of laser beams in a second direction perpendicular to the first direction by a predetermined step width.

[0148] This application claims priority based on Japanese Patent Application No. 2021-061778, filed on March 31, 2021, in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0149] Those skilled in the art will recognize that various modifications, combinations, subcombinations, and variations may occur depending on design requirements and other factors, and are intended to be within the scope of the appended claims and their equivalents.

Claims

1. An imaging system for imaging on a recording medium in which multiple recording layers, each containing a different color developing compound and a different photothermal conversion agent, are stacked via a heat insulating layer, the imaging system comprising: a light source unit that generates multiple laser beams having different wavelengths that correspond to the absorption wavelengths of the photothermal conversion agents; and a scanning unit that irradiates the surface of the recording medium with the multiple laser beams generated by the light source unit via a predetermined gap, and scans the multiple laser beams in the same direction on the surface of the recording medium in synchronization with each other; wherein the scanning unit scans the multiple laser beams on the surface of the recording medium in a state in which irradiation spots formed by the multiple laser beams are lined up at predetermined gaps in a direction perpendicular to or diagonally intersecting the scanning direction of the multiple laser beams.

2. The drawing system according to claim 1, wherein the scanning unit scans a line on the recording medium that has been scanned by a first laser beam of the plurality of laser beams with a second laser beam that is different from the first laser beam of the plurality of laser beams.

3. The drawing system according to claim 1, wherein the scanning unit has an optical system that scans the plurality of laser beams in a first direction, and a stage that moves the recording medium in a second direction perpendicular to the first direction.

4. The drawing system according to claim 1, wherein the scanning unit has an optical system that scans the plurality of laser beams in a first direction and moves the scan lines of the plurality of laser beams in a second direction perpendicular to the first direction at a predetermined step width.

5. The drawing system according to claim 1, wherein the light source unit outputs the plurality of laser beams to the scanning unit with the optical axes of the plurality of laser beams shifted from one another.

6. The drawing system according to claim 5, wherein the light source unit outputs the plurality of laser beams to the scanning unit so that the optical axes of the plurality of laser beams are parallel to each other with a predetermined gap therebetween.

7. The drawing system according to claim 5, wherein the light source unit outputs the plurality of laser beams to the scanning unit so that the optical axes of the plurality of laser beams intersect with each other at a predetermined angle.

8. The drawing system according to claim 5, wherein the light source unit outputs the plurality of laser beams to the scanning unit via optical fibers provided separately for each of the laser beams.

9. A method for drawing on a recording medium having a plurality of recording layers, each containing a different color developing compound and a different photothermal conversion agent, stacked via a heat insulating layer, the method comprising: generating a plurality of laser beams having different wavelengths that correspond to the absorption wavelengths of the photothermal conversion agents; irradiating the surface of the recording medium with the generated laser beams via a predetermined gap, and synchronously scanning the surface of the recording medium with the plurality of laser beams in the same direction; and scanning the surface of the recording medium with the plurality of laser beams, with irradiation spots formed by the plurality of laser beams aligned at predetermined gaps in a direction perpendicular to or obliquely intersecting the scanning direction of the plurality of laser beams.

10. The drawing method according to claim 9, comprising scanning a line on the recording medium that has been scanned with a first laser beam of the plurality of laser beams with a second laser beam different from the first laser beam of the plurality of laser beams.

11. The drawing method according to claim 9, further comprising performing a raster scan by scanning the plurality of laser beams in a first direction and moving the recording medium in a second direction perpendicular to the first direction.

12. The drawing method according to claim 9, further comprising: scanning the recording medium with the plurality of laser beams in a first direction while keeping the recording medium stationary, and moving the scan lines of the plurality of laser beams in a second direction perpendicular to the first direction at predetermined step widths, thereby performing a raster scan.