Face image recording medium

Abstract

To provide a face image recording medium for recording a face image by irradiation with a laser beam, which can clearly record the face image compared to a conventional configuration, by a simple constitution.SOLUTION: A face image recording part 2 is configured so that a first color developing layer which can develop a color with a yellow-based hue, a second color developing layer which can develop a color with a magenta-based hue, and a third color developing layer which can develop with a cyan-based hue are stacked on a base material layer, and the first color developing layer and the second color developing layer are stacked on the third color developing layer.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a face image recording medium used for issuing an identity certificate with a face image.

Background Art

[0002] It has been proposed to record a face image to be displayed on an identity certificate with laser light (for example, Patent Document 1). Such a conventional recording medium includes, in a portion for recording a face image, three-layer color developing layers capable of developing colors in three different primary colors by irradiation with laser light, and is configured to be able to record a face image as a full-color image by individually controlling the color development of the three-layer color developing layers and mixing the colors.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the face image recorded on the face image recording medium of Patent Document 1 above can be used for identity verification etc., sharpness is required.

[0005] The present invention has been made in view of such a situation, and aims to provide a configuration of a face image recording medium that records a face image by irradiating laser light, and that can record a face image more clearly with a simpler configuration than the conventional configuration.

Means for Solving the Problems

[0006] The inventor focused on the fact that, in the conventional configuration, although the color developing layer before face image color development is substantially transparent, it tends to be thicker than the printing layer of process ink, and it is difficult to obtain a material with sufficient transparency in terms of technology and cost. After intensive studies, the present invention was completed.

[0007] The present invention relates to a face image recording medium including a face image recording unit for recording a face image by irradiating laser light. In the face image recording unit, a first color developing layer capable of developing a color in a yellow hue, a second color developing layer capable of developing a color in a magenta hue, and a third color developing layer capable of developing a color in a cyan hue are laminated on a base material layer. By irradiating laser light to record images individually on the three color developing layers of the face image recording unit and mixing the recorded images, a color face image can be recorded. The face image recording medium is characterized in that the first color developing layer and the second color developing layer are laminated on the third color developing layer.

[0008] According to the inventor's research, since the colors of the skin, hair, etc. included in the face image are composed of the colors of main pigments (melanin and hemoglobin) containing a large amount of yellow and red components, the face image recorded in the face image recording unit is mainly recorded in the color of the first color developing layer in the yellow system and the second color developing layer in the magenta system. As described above, since the color developing layer of the conventional configuration does not have sufficient transparency, the recorded image of the lower color developing layer is likely to be unclear. However, if the cyan-based third color developing layer with a low contribution to the recording of the face image is arranged in the lower layer as in the present invention, the sharpness of the face image recorded in the face image recording unit can be improved with a simple configuration compared to the conventional configuration.

[0009] Further, as another aspect of the present invention, there is proposed a face image recording medium including a face image recording unit for recording a face image by irradiating laser light. In the face image recording unit, a first color developing layer capable of developing a color in a red hue and a second color developing layer capable of developing a color in a green hue are laminated on a base material layer. By irradiating laser light to record images individually on the two color developing layers of the face image recording unit and mixing the recorded images, a color face image can be recorded. The face image recording medium is characterized in that the first color developing layer is laminated on the second color developing layer.

[0010] According to the inventor's research, since the main pigments that make up the color of the skin, hair, etc. are limited, a face image can be recorded with a color reproducibility comparable to that when recorded with a CMY three-color color development layer even by a two-layer color development layer that develops colors in red and green color hues. And, in this way, when recording a face image by mixing two images of red and green colors, by arranging the first color development layer of red color containing more color components of the skin, hair, etc. on top of the second color development layer that develops colors in green color, the sharpness of the face image recorded in the face image recording unit can be improved with a simple configuration.

Advantages of the Invention

[0011] As described above, according to the face image recording medium of the present invention, a face image can be recorded more clearly with a simple configuration compared to the conventional configuration.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0013] Embodiments of the present invention will be described by the following examples. In the following Examples 1 to 3, the first color developing layer according to the present invention corresponds to the upper color developing layer, the second color developing layer according to the present invention corresponds to the intermediate color developing layer, and the third color developing layer according to the present invention corresponds to the lower color developing layer.

Example

[0014] As shown in Fig. 1(A), the face image recording medium 1 of this example is a certificate paper used for issuing a card-type identity certificate. A color information recording section 2 is provided in a rectangular area on the left side of the front side of the face image recording medium 1. The color information recording section 2 is a white plain area, and when the identity certificate is issued, as shown in Fig. 1(B), the face image F of the person to be certified is recorded as a color image by laser light. That is, the color information recording section 2 corresponds to the face image recording section according to the present invention. Further, a monochrome information recording section 3 for recording and displaying the attribute information of the person to be certified is provided in a rectangular area on the right side of the front side of the face image recording medium 1. As shown in Fig. 1(A), only the item names of the attribute information are pre-printed in a white plain area in the monochrome information recording section 3, and when the identity certificate is issued as shown in Fig. 1(B), the attribute information is recorded as black characters by laser light.

[0015] Figure 2 shows the layer structure of the face image recording medium 1. The face image recording medium 1 includes a base material layer and a protective layer that covers the front side (the upper side in Figure 2) of the base material layer. As shown in Figure 2(A), in the color information recording section 2, three color developing layers and two heat insulating layers are disposed between the protective layer and the base material layer. The color developing layer is a layer for recording the face image F in color by laser light. As will be described later, the three color developing layers are configured to be capable of developing in different vivid colors by irradiation with laser light. The heat insulating layer is provided between the color developing layers. On the other hand, as shown in Figure 2(B), in the monochrome information recording section 3, a black developing layer capable of recording information in black by laser light is disposed between the protective layer and the base material layer. Although not shown, the pre-printing of the monochrome information recording section 3 is formed between the surface of the base material layer (the base material layer and the black developing layer). Also, although not shown, the portions other than the color information recording section 2 and the monochrome information recording section 3 have a two-layer structure of only the base material layer and the protective layer.

[0016] The base material layer supports the color developing layer and the black developing layer from the back side. The thickness of the base material layer is not particularly limited, but is preferably about 50 μm to 1000 μm. The base material layer may be a single sheet or a laminate of a plurality of sheets. Specific examples of the material of the base material layer include paper, resin sheets, or combinations thereof. The surface of the base material layer is desirably a color that does not affect the color of the face image F recorded in the color information recording section 2. Specific colors include white, light colors, and colorless.

[0017] The protective layer is provided for the purpose of preventing damage or deterioration of the color developing layer or black color developing layer and forgery of the recorded information. The protective layer is composed of a substantially transparent material that transmits the recording laser light used for information recording and enables the recorded information to be visible. Further, the protective layer can be preferably composed of a material that does not transmit water or air. Desirable film materials for constituting the protective layer include polyvinyl chloride (PVC), glycol-modified polyethylene terephthalate (PETG), polyethylene terephthalate (PET), polypropylene (PP), and the like. The thickness of the protective layer is not particularly limited, but is preferably about 1 μm to 100 μm. The protective layer can be composed of one or a plurality of films. When the protective layer is a film, it is proposed to bond it to the base material layer, color developing layer, etc. with an adhesive or the like.

[0018] The three-layer color developing layer is substantially transparent before the recording of the face image F and is configured to develop colors in different hues of chromatic colors by irradiation with laser light. Each color developing layer contains a photothermal conversion agent that absorbs laser light of a predetermined wavelength and generates heat, a thermosensitive color developing component that develops color when the temperature reaches a predetermined color developing threshold temperature or higher, and a binder resin. That is, each color developing layer generates heat by irradiation with laser light having a wavelength that can be absorbed by the photothermal conversion agent, and develops color when the irradiated portion rises to the color developing threshold temperature. The three-layer color developing layer develops colors in different primary colors respectively due to the difference in the thermosensitive color developing components contained therein. Specifically, as shown in FIG. 2(A), the upper color developing layer in the upper layer (surface side) develops color in yellow (Y), the middle color developing layer in the middle layer develops color in magenta (M), and the lower color developing layer in the lower layer (base material layer side) develops color in cyan (C). That is, in this embodiment, a yellow image, a magenta image, and a cyan image are individually recorded on each color developing layer, and the full-color face image F can be recorded and displayed in the color information recording unit 2 by overlapping and mixing these images.

[0019] The thickness of the color developing layer is not particularly limited, but is preferably about 1 μm to 50 μm. As the constituent material of the color developing layer, known materials can be preferably used. For example, as a suitable photothermal conversion agent that absorbs laser light in the near-infrared region and generates heat, cyanine dyes can be mentioned. As the heat-sensitive color developing component, a combination of a leuco dye and a developer can be used. The leuco dye and the developer can be selected from known materials according to the color to be developed. As the binder resin, a colorless resin material such as polyvinyl alcohol can be used.

[0020] The photothermal conversion agents contained in each color developing layer have different wavelength ranges of the laser light to be absorbed. Thereby, the face image recording medium 1 is configured to selectively heat the three-layer color developing layer by selectively irradiating three types of recording laser lights with different wavelengths from the front side, so that the color development of each color developing layer can be individually controlled. Specifically, the upper color developing layer is configured to absorb the recording laser light of the first wavelength, generate heat and develop color, and transmit the recording laser lights of the second wavelength and the third wavelength. Then, the intermediate color developing layer is configured to absorb the recording laser light of the second wavelength, generate heat and develop color, and transmit the recording laser light of the third wavelength. Then, the lower color developing layer is configured to absorb the recording laser light of the third wavelength and generate heat and develop color.

[0021] The three-wavelength recording laser lights used for recording on the face image recording medium 1 are not particularly limited, but it is desirable that all of them are recording laser lights in the near-infrared region. Specific laser lights include YAG laser light, CO 2 laser light, YVO 4 laser light, fiber laser light, semiconductor laser light, etc. As specific wavelengths, it is proposed to use three types of 785 nm, 860 nm, and 1064 nm. In this embodiment, the absorption characteristics of the laser light of each color developing layer are set so that the first wavelength, which is the shortest wavelength among the three wavelengths, is used as the recording laser light for the upper color developing layer, and the third wavelength, which is the longest wavelength among the three wavelengths, is used as the recording laser light for the lower color developing layer.

[0022] The heat insulation layer is disposed between the color developing layers to suppress heat conduction between the color developing layers. That is, when heating and developing the target color developing layer with the recording laser beam, the heat insulation layer prevents other color developing layers from rising to the color development threshold temperature due to the heat of the color developing layer. The heat insulation layer is made of a substantially transparent material that transmits the recording laser beam and does not block the information recorded on the color developing layer. Suitable materials for the heat insulation layer include polyvinyl alcohol, polyvinyl acetate, and polyacryl. The thickness of the heat insulation layer is not particularly limited, but a suitable thickness for suppressing heat conduction between the color developing layers is 1 μm to 50 μm.

[0023] The color developing layer and the heat insulation layer constituting the color information recording unit 2 can be formed by applying a paint containing the material of each layer to the front side of the base material layer or the back side of the protective layer and drying and laminating them.

[0024] The black color developing layer is substantially transparent before recording and is configured to develop a black color upon irradiation with a laser beam having a predetermined wavelength. Examples of the black color developing layer include a composition comprising a photothermal conversion agent that absorbs a laser beam having a predetermined wavelength and generates heat, and a resin that is carbonized black by the heat generated by the photothermal conversion agent. A widely known composition can be widely adopted for the composition of the black color developing layer. The black color developing layer is made of a material that absorbs all of the three-wavelength recording laser beams used for recording in the color information recording unit 2. The thickness of the black color developing layer is not particularly limited, but is preferably about 1 μm to 200 μm. When the color information recording unit 2 and the monochrome information recording unit 3 are adjacent to each other as in this embodiment, it is preferable to set the thickness of the black color developing layer so that the step at the boundary between the color information recording unit 2 and the monochrome information recording unit 3 is reduced. The black color developing layer can be preferably formed by applying a material to the front side of the base material layer or the back side of the protective layer.

[0025] When issuing an identity certificate using the face image recording medium 1, as shown in FIGS. 1(A)→1(B), a face image F is recorded on the color information recording unit 2 and characters indicating attribute information are recorded on the monochrome information recording unit 3 using a laser recording apparatus capable of irradiating the above-described three-wavelength recording laser beam.

[0026] Figure 3 shows the configuration of a laser recording apparatus 10 capable of recording a face image F and attribute information on the face image recording medium 1 of the present embodiment. The laser recording apparatus 10 includes laser oscillators 11a, 11b, 11c that output recording laser light, a condensing unit 12 that condenses the recording laser light onto the face image recording medium 1, an optical fiber 13 that guides the recording laser light from the laser oscillators 11a, 11b, 11c to the condensing unit 12, a stage 14 that holds the face image recording medium 1, a stage moving mechanism 15 that moves the stage 14, an output control unit 16 that controls the operation of the laser oscillators 11a, 11b, 11c and the condensing unit 12, a position control unit 17 that controls the operation of the stage moving mechanism 15, and a calculation unit 18 that comprehensively controls the laser recording apparatus 10.

[0027] Such a laser recording apparatus 10 can record information with recording laser light of three wavelengths, and one type of each of the laser oscillators 11a, 11b, 11c that output recording laser light of each wavelength is arranged. The condensing unit 12 includes a single condensing lens 19, and the recording laser light of three wavelengths output by the laser oscillators 11a, 11b, 11c and guided by the optical fiber 13 is condensed by the same condensing lens 19. Further, the condensing unit 12 includes a height detection mechanism capable of detecting the surface height of the face image recording medium 1 and a lens moving mechanism that moves the condensing lens 19 up and down to adjust the focal position of the recording laser light. Since the configuration of such a laser recording apparatus 10 is well-known, a detailed description thereof will be omitted.

[0028] The above laser recording apparatus 10 records the face image F and the attribute information on the face image recording medium 1 mainly by sequentially executing the following steps (1) to (7). (1) Set the face image recording medium 1 before recording at a predetermined position on the stage 14. (2) Detect the surface height of the face image recording medium 1 by the height detection mechanism of the condensing unit 12. (3) Adjust the focal position by moving the condensing lens 19 up and down based on the surface height of the face image recording medium 1. (4) The data of the face image F to be recorded and the attribute information are taken into the calculation unit 18. (5) The face image F is recorded in the color information recording unit 2. (6) The attribute information is recorded in the monochrome information recording unit 3. (7) After the recording is completed, the face image recording medium 1 is carried out from the stage 14.

[0029] In the step of recording the face image F in the color information recording unit 2 (step (5) described above), the calculation unit 18 decomposes the full-color digital data of the face image F into the three primary colors of CMY. Then, the cyan plate image, the magenta plate image, and the yellow plate image obtained by the color decomposition are respectively recorded on the three-layer color developing layer using laser light of three wavelengths. Specifically, the calculation unit 18 cooperatively operates the laser oscillator 11c and the stage moving mechanism 15 via the output control unit 16 and the position control unit 17 to irradiate the required position of the face image recording medium 1 with the recording laser light of the third wavelength under the required conditions (irradiation time · irradiation intensity) to record the cyan plate image on the lower color developing layer. Thereafter, similarly, the recording laser light of the second wavelength is irradiated to record the magenta plate image on the intermediate color developing layer, and further, the recording laser light of the first wavelength is irradiated to record the yellow plate image on the upper color developing layer.

[0030] In this way, the face image recording medium 1 of this embodiment selectively irradiates the recording laser light of three types of wavelengths from the front side of the color information recording unit 2 to individually record the cyan, magenta, and yellow images on the three-layer color developing layer, and by overlapping the images recorded on each color developing layer, a full-color face image F can be recorded in the color information recording unit 2.

[0031] In the step of recording the attribute information in the monochrome information recording unit 3 (step (6) described above), The calculation unit 18 operates the laser oscillator 11c and the stage movement mechanism 15 in a coordinated manner to irradiate the required position of the monochrome information recording unit 3 with recording laser light from the front side under required conditions, thereby carbonizing the required part of the black color developing layer. At this time, if the energy of the recording laser light irradiated onto the monochrome information recording unit 3 is relatively high, not only can the recording part be made to develop black by carbonization, but it can also be raised to the front side by the foaming of the binder resin. Since the black color developing layer can absorb the recording laser light of the above three wavelengths, the recording laser light used for recording by the color information recording unit 2 can be used during recording of the monochrome information recording unit 3.

[0032] In this embodiment, among the three-layer color developing layers, the upper upper color developing layer can develop in yellow, the middle color developing layer can develop in magenta, and the lower color developing layer is configured to be able to develop in cyan. Since the colors of the skin, hair, etc. included in the face image F are composed of the colors of the main pigments containing a large amount of yellow-based and red-based components, the face image F is mainly recorded in the colors of the color developing layer that develops in yellow and the color developing layer that develops in magenta. Therefore, as in this embodiment, if the lower lower color developing layer is made to develop in cyan, which has a low contribution to the recording of the face image F, even if the transparency of the color developing layer is insufficient and the recorded image of the lower color developing layer is somewhat unclear, a face image F with relatively high sharpness can be recorded.

[0033] Examples 2 and 3 will be described below. These examples are those in which a part of the configuration of the above Example 1 is changed, and the configurations not particularly mentioned are common to Example 1, and the same reference numerals as those in Example 1 are used in the text and drawings for explanation.

Example

[0034] While each color developing layer according to Example 1 above is a homogeneous layer containing a photothermal conversion agent and a thermosensitive color developing component, the color information recording section 2a according to this example, as shown in Fig. 4(A), has each color developing layer composed of two layers: a photothermal conversion layer containing a photothermal conversion agent and not containing a thermosensitive color developing component, and a thermosensitive color developing layer containing a thermosensitive color developing component and not containing a photothermal conversion agent. That is, in the color developing layer according to this example, the photothermal conversion layer absorbs the recording laser light and generates heat, and transfers the heat to the adjacent thermosensitive color developing layer to raise the temperature to the threshold temperature, thereby developing a color with a predetermined hue. Thus, the color developing layer according to the present invention may be composed of two layers, namely a photothermal conversion layer and a thermosensitive color developing layer. Even with such a configuration, if the cyan-developing color developing layer is disposed in the lower layer, the face image F can be recorded relatively clearly as in Example 1 above.

Example

[0035] In Example 1 above, three color developing layers are laminated in the color information recording section 2, whereas in the color information recording section 2b according to this example, as shown in Fig. 4(B), two color developing layers are laminated. Among the two color developing layers, the upper upper color developing layer is configured to develop a color with a red hue, and the lower lower color developing layer is configured to develop a color with a green hue.

[0036] Since the color developing layer of this example has only two color developing layers capable of developing different colors, the colors that can be displayed are limited. However, according to the inventor's research, since the main pigments constituting the colors of the skin, hair, etc. are limited, even with two color developing layers that develop colors with red and green hues, a face image can be recorded with a color reproducibility comparable to that when recorded with three color developing layers of CMY. Thus, the color information recording section according to the present invention can be composed of two color developing layers. With such a configuration, the color information recording section 2b can be made thinner than in Example 1, and the manufacturing cost can also be reduced. Also, since only two types of recording laser light are required for recording on the color information recording section 2b, recording can be performed with a simpler laser recording apparatus, and the time required for recording can also be shortened.

[0037] <Evaluation Test> For Example 1 above, six types of test samples 1 to 6 were produced in which the color patterns assigned to the three-layer color developing layers of the color information recording unit 2 were variously changed. Also, for Example 3 above, two types of test samples 7 and 8 were produced in which the color patterns assigned to the two-layer color developing layers of the color information recording unit 2b were changed. In all the test samples, the thickness of the protective layer was 100 μm, the thickness of each color developing layer was 50 μm, and the thickness of the heat insulating layer was 10 μm, and all other configurations were made common to all the test samples.

[0038] Using the above-described laser recording apparatus 10, a color face image F was recorded on the color information recording units of the test samples 1 to 8, and for the face image F recorded on each test sample, the sharpness of the face contour, lips, hair, pupils, etc. was visually evaluated. The results are shown in FIG. 5.

[0039] As shown in FIG. 5, in test samples 1 and 2, the face contour, lips, hair, pupils, etc. were recorded more clearly than in test samples 3 to 6. This suggests that by assigning cyan to the lower color developing layer of the lower layer, the face image F can be recorded more clearly than when cyan is assigned to the upper color developing layer of the upper layer or the intermediate color developing layer of the middle layer. Also, for test samples 1 and 2, the sharpness of the face contour, lips, hair, and pupils was about the same. This suggests that even when the upper color developing layer is configured to develop with magenta and the intermediate color developing layer is configured to develop with yellow in Example 1 above, the face image F can be recorded with about the same sharpness.

[0040] In test samples 7 and 8, the face image F was recorded with color reproducibility comparable to that of test samples 1 and 2. Also, when comparing test samples 7 and 8, the face contour, lips, hair, pupils, etc. were recorded more clearly in test sample 7 than in test sample 8. This suggests that by assigning the red color system to the upper color developing layer of the upper layer, the face image F can be recorded more clearly than when the green color system is assigned to the upper color developing layer.

[0041] The embodiments of the present invention have been described above. However, the embodiments of the present invention are not limited to the configurations of the above embodiments and can be appropriately changed within the scope not departing from the gist of the present invention. For example, although the face image recording medium in the above embodiment is a card-type identity certificate, it may be a booklet-type identity certificate. Further, the present invention is not limited to identity certificates and is applicable to all face image recording media including a face image recording unit.

[0042] Also, the layer configurations of the color information recording unit 2 and the monochrome information recording unit 3 can be appropriately changed within the scope not departing from the gist of the present invention. For example, a layer such as a lenticular lens can be further disposed on the protective layer according to the above embodiment. Further, a primer layer for enhancing the adhesion to the color developing layer or the black developing layer, or a background pattern printing layer can be disposed on the surface of the base material layer.

[0043] Also, the plurality of color developing layers according to the above embodiment are configured such that the wavelength ranges of the laser light that can be absorbed are different and can be individually developed by recording laser light of different wavelengths. However, the plurality of color developing layers according to the present invention may be configured such that the color development threshold temperatures are different and can be individually controlled for color development by adjusting the applied energy of the recording laser light.

[0044] Note that in the face image recording medium 1 of the above embodiment, the color information recording unit 2 and the monochrome information recording unit 3 are disposed only on the front side, but a color information recording unit or a monochrome information recording unit may also be disposed on the back side of the face image recording medium 1.

[0045] Further, the base material layer may be configured of a material through which the recording laser light can pass, and the recording laser light may be irradiated from the back side of the face image recording medium 1 to the color information recording unit 2 and the monochrome information recording unit 3 on the front side.

[0046] Also, in all of the laser recording media 1 of the above embodiment, laser light in the near-infrared region is used as the recording laser light, but the recording laser light according to the present invention may be partially or entirely laser light in the ultraviolet region or the visible light region.

Explanation of Symbols

[0047] 1 Facial image recording medium 2, 2a, 2b Color information recording part (facial image recording part) 3 Monochrome information recording part 4 Color developing layer 10 Laser recording device 11a, 11b, 11c Laser oscillators 12 Condensing part 13 Optical fiber 14 Stage 15 Stage moving mechanism 16 Output control part 17 Position control part 18 Calculation part 19 Condensing lens F Facial image

Claims

1. A face image recording medium comprising a face image recording unit for recording a face image by irradiating laser light, wherein in the face image recording unit, a first color developing layer capable of developing a color in a yellow-based hue, a second color developing layer capable of developing a color in a magenta-based hue, and a third color developing layer capable of developing a color in a cyan-based hue are laminated on a base material layer, and the face image recording medium is configured to record a color face image by irradiating laser light to individually record images on the three color developing layers of the face image recording unit and mixing the recorded images, wherein the first color developing layer and the second color developing layer are laminated on the third color developing layer. A face image recording medium characterized by this.

2. A face image recording medium comprising a face image recording unit for recording a face image by irradiating laser light, wherein in the face image recording unit, a first color developing layer capable of developing a color in a red-based hue and a second color developing layer capable of developing a color in a green-based hue are laminated on a base material layer, and the face image recording medium is configured to record a color face image by irradiating laser light to individually record images on the two color developing layers of the face image recording unit and mixing the recorded images, wherein the first color developing layer is laminated on the second color developing layer. A face image recording medium characterized by this.

Images