JPWO2020189021A1 - Printing method, printed matter, and printing system - Google Patents

Abstract

Provided are a printing method and a printing system capable of performing printing at high speed and appropriately in order to satisfactorily reproduce the optical texture of an object. Further, the present invention provides a printed matter (1) in which abnormal propagation of light in the white layer (7) formed in the printed matter is suppressed. In the present invention, a print layer forming process for forming a multi-layered printed layer (5) on the base material (2) is performed based on data on the texture of the surface of the object, and the print layer forming process is transparent and transparent. A layer (8), a white layer (7) composed of a white fluid and arranged at a position corresponding to data in the print layer (5), and a white layer composed of a black fluid and in the print layer (5). A print layer (5) having a black layer (9) arranged between the white layer (7) and the base material (2) in the region where (7) exists is formed.

Description

The present invention relates to a printing method and a printing system, and more particularly to a printing method and a printing system for reproducing the texture of the surface of an object.
The present invention also relates to a printed matter in which the texture of the surface of the object is reproduced.

In recent years, with the development of printing technology, it has become possible to reproduce the texture of an object to be reproduced (hereinafter, simply referred to as "object"). For example, with the development of three-dimensional printing technology, the texture (specifically, thickness, etc.) of an object can be reproduced satisfactorily. In addition, the texture of the object, especially the optical texture on the surface of the object, is improved by the printing technology using clear ink having curability (hereinafter, referred to as "2.5-dimensional printing" for convenience). It can be reproduced. Here, the optical texture specifically corresponds to the internal scattering characteristics of light, the sense of depth of the transparent portion exposed on the surface of the object (in other words, the thickness of the transparent portion), and the like.

In order to adjust the optical texture of each part of the printed matter in 2.5-dimensional printing, it is necessary to change the thickness of the transparent layer (for example, the clear ink layer) in each part. In order to change the thickness of the transparent layer for each place, ejection and curing of clear ink are repeated at each place according to the thickness. Printing with such a procedure takes a long time to generate printed matter.

As a method for solving the above-mentioned 2.5-dimensional printing problem, for example, the technique described in Patent Document 1 can be mentioned. According to the technique described in Patent Document 1 (particularly, the technique described in Example 2 of Patent Document 1), the transparent layer has a certain thickness in the printed matter, and the white ink is applied above or below the transparent layer. A layer (hereinafter, also referred to as a “white layer”) is provided. This white layer is provided in a portion of the printed matter where light scattering is suppressed (that is, a portion where light internal scattering is small). By using the technique described in Patent Document 1 in this way, it is possible to adjust the optical texture only by forming the white layer without changing the thickness of the transparent layer depending on the location. As a result, printing for reproducing the optical texture of the object can be performed at higher speed.

Japanese Unexamined Patent Publication No. 2018-12242

However, if a white layer is provided in the vicinity of the transparent layer as described in Patent Document 1, the light incident on the printed matter may abnormally propagate through the white layer, and for example, the light may wrap around the white layer. be. Therefore, when a white layer is provided, it is necessary to suppress anomalous propagation of light around it.

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to solve the following object.
Specifically, the present invention provides a printing method and a printing system capable of solving the problems of the above-mentioned prior art and performing printing at high speed and appropriately for reproducing the optical texture of an object well. The purpose is to provide.
Another object of the present invention is to provide a printed matter in which anomalous propagation of light in a white layer formed in the printed matter is suppressed.

In order to achieve the above object, the printing method of the present invention is a printing method that reproduces the texture of the surface of an object, and prints to form a multi-layered printing layer on a substrate based on data on the texture. A layer forming process is carried out, and in the print layer forming process, a transparent transparent layer, a white layer composed of a white fluid and arranged at a position corresponding to data in the print layer, and a black fluid are composed and printed. It is characterized by forming a print layer having a black layer arranged between the white layer and the base material in a region where the white layer exists in the layer.

According to the printing method of the present invention described above, the black layer is arranged between the white layer and the base material in the region where the white layer exists in the printing layer. By suppressing the abnormal propagation of light around the white layer, the black layer makes it possible to perform printing at high speed and appropriately in order to satisfactorily reproduce the optical texture of the object.

Further, in the print layer forming process, it is preferable to prepare a base material having a white medium having a uniform thickness and an internal scattering member superimposed on the white medium, and form a print layer on the surface of the internal scattering member.
With the above configuration, the light scattering characteristics of the internal scattering member can be utilized when reproducing the texture of the object by printing.

Further, in the print layer forming process, it is preferable to form a print layer on the surface of the internal scattering member having a uniform thickness.
With the above configuration, since the thickness of the internal scattering member is uniform, the light scattering characteristics in each portion of the internal scattering member are also substantially uniform. In this case, in order to set the formation conditions (specifically, the layer configuration, etc.) of the printed layer capable of reproducing the desired light scattering characteristics as compared with the case where the light scattering characteristics of the internal scattering member differ between parts. Is easier to calculate and faster. Further, if the internal scattering members having a uniform thickness are stacked instead of the printing process in which the thickness differs for each part, the texture reproduction process becomes easier.

Further, in the print layer forming process, it is preferable to form a print layer having a transparent layer having a uniform thickness.
According to the above configuration, the print layer can be formed more easily and the print layer formation speed can be further increased as compared with the case where the thickness of the transparent layer is changed depending on the location. Become.

Further, in the print layer forming process, it is preferable to form a print layer having a white layer arranged between the transparent layer and the base material.
According to the above configuration, since the white layer exists under the transparent layer, the light reflection from the lower layer of the transparent layer can be visually recognized more clearly. This makes it possible to satisfactorily reproduce the optical texture of the object (strictly speaking, the sense of depth of the transparent portion of the object) even with a thinner transparent layer. As a result, when the transparent layer is formed, the thickness of the transparent layer can be made thinner, so that the formation speed of the print layer can be increased.

Further, in the print layer forming process, it is preferable to form a print layer having a white layer adjacent to the transparent layer.
According to the above configuration, the formation of the white layer makes it easier to control light scattering. As a result, the effect that the optical texture of the object is well reproduced even if the thickness of the transparent layer is reduced can be more effectively exhibited.

Further, in the print layer forming process, it is preferable to form a print layer having a black layer adjacent to the white layer.
According to the above configuration, the effect of suppressing the abnormal propagation of light to the periphery of the white layer by the black layer can be more effectively exhibited.

Further, in the print layer forming process, it is preferable to form a print layer having a color layer composed of a color fluid and a white layer adjacent to the color layer between the color layer and the transparent layer.
In the above case, in the portion of the print layer having the color layer, since the white layer is interposed between the color layer and the transparent layer, it is possible to satisfactorily reproduce the surface color of the object.

Further, in the print layer forming process, the thickness data regarding the thickness of the transparent portion exposed on the surface of the object and the light scattering characteristic data regarding the light scattering characteristic of the object with respect to the incident light on the surface of the object are used. It is preferable to form the printed layer on the base material in the form of an image according to the formation conditions set in the above.
In the above configuration, the formation conditions of the print layer are set based on the data regarding the texture of the object (specifically, the thickness data and the light scattering characteristic data). If the print layer is formed according to this formation condition, it is possible to satisfactorily reproduce the optical texture of the object.

Further, in the print layer forming process, it is preferable to form a print layer having a white layer arranged in an image according to the formation conditions set for each region of the surface of the base material.
In the above configuration, when the print layer is formed according to the formation conditions, the white layer can be arranged in an image-like manner. As a result, the optical texture of the object (particularly, the sense of depth of the transparent portion) can be reproduced well.

Further, in order to solve the above-mentioned problems, the printed matter of the present invention has a base material and a multi-layered printed layer formed on the base material based on data on the texture of the surface of the object, and is a printed layer. Is composed of a transparent transparent layer, a white layer composed of a white fluid and arranged at a position corresponding to data in the print layer, and a white layer in a region composed of a black fluid and having a white layer in the print layer. It is characterized by comprising a black layer disposed between the substrate and the substrate.
With the printed matter of the present invention configured as described above, the abnormal propagation of light around the white layer formed therein can be suppressed.

Further, in order to solve the above-mentioned problems, the printing system of the present invention is a printing system that reproduces the texture of the surface of an object, and is a printing layer forming apparatus that forms a printing layer having a multilayer structure on a base material and a texture. The print control device comprises a print control device for forming a print layer on the print layer forming device based on the data relating to the above, and the print control device is composed of a transparent transparent layer and a white fluid on the print layer forming device, and prints. It has a white layer arranged at a position corresponding to data in the layer, and a black layer composed of a black fluid and arranged between the white layer and the substrate in a region where the white layer exists in the print layer. It is characterized by forming a print layer.
By using the printing system of the present invention configured as described above, it is possible to perform printing at high speed and appropriately in order to satisfactorily reproduce the optical texture of the object.

According to the present invention, it is possible to perform printing at high speed and appropriately in order to satisfactorily reproduce the optical texture of an object.
Further, according to the present invention, it is possible to provide a printed matter in which abnormal propagation of light to the periphery of a white layer formed in the printed matter is suppressed.

It is a figure which shows the example of an object. It is a schematic diagram which shows the internal scattering phenomenon of light. It is a schematic diagram which shows the structure of the printed matter. It is a figure which shows the structure of a printing system. It is a schematic diagram which shows the structure of the print layer forming apparatus. It is a figure which shows the nozzle surface of the ejection mechanism which a print layer forming apparatus has. It is a figure which shows the sample pattern. It is a figure which shows the surface of an object, and the formation region of the print layer on the print surface of a base material. It is a figure which shows the rectangular wave chart. It is a figure which shows an example of a light scattering characteristic data. It is a flow chart of texture reproduction printing. It is a figure which shows the flow of the light scattering characteristic estimation processing. It is a figure which shows the 1st pattern about the BSSRDF characteristic. It is a figure which shows the 2nd pattern about the BSSRDF characteristic. It is a figure which shows the 3rd pattern about the BSSRDF characteristic. It is a figure which shows the 4th pattern about the BSSRDF characteristic. It is a figure which shows the arithmetic matrix. It is a figure which shows the flow of the formation condition setting process. It is a schematic diagram which shows the structure of the printed matter which concerns on the modification.

A printing method, a printed matter, and a printing system according to an embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail below with reference to the accompanying drawings as appropriate.
It should be noted that the embodiments described below are merely examples for facilitating the understanding of the present invention, and do not limit the present invention. That is, the present invention may be modified or improved from the embodiments described below as long as it does not deviate from the gist thereof. Further, as a matter of course, the present invention includes the equivalent thereof.

Further, in the present specification, the numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
Further, in the present specification, unless otherwise specified, the stacking direction of the print layer described later is the vertical direction, the side closer to the base material is referred to as "lower side", and the side farther from the base material is referred to as "upper side". I decided to.

<Outline of this embodiment>
First, the outline of the present embodiment will be described.
The printing method and printing system according to the present embodiment are used to generate a printed matter that reproduces the texture of the surface of the object. Here, the "object" is a member that is the target of texture reproduction. An example of an object is a material whose surface texture (strictly speaking, optical texture) differs depending on the part, and specifically, rocks such as granite and marble, stones, wood, hair, bones, etc. Examples include natural materials such as skin (skin), teeth, cotton and silk.

In the following, a case where the granite T shown in FIG. 1 is the object will be described as an example. However, the present embodiment is, of course, applicable to the case where other materials are the objects.

Further, in the present embodiment, the "texture" is, for example, a light scattering characteristic and a sense of depth. The sense of depth is the thickness of the transparent portion (for example, quartz Tc appearing on the surface of the granite T shown in FIG. 1) exposed on the surface of the object. Here, the thickness of the transparent portion is the length from the surface of the object to the interface between the transparent portion and the portion adjacent to the transparent portion (specifically, the colored portion immediately below the transparent portion).

The light scattering characteristic is an internal scattering characteristic of light (also referred to as subsurface scattering). Internal scattering means that when light is applied to an object, as shown in FIG. 2, the light repeatedly reflects and scatters inside the object, so that the light is emitted from a position distant from the incident position of the light on the surface of the object. Is emitted. Further, the internal scattering characteristic of light is specified based on the distance from the incident position of light to the emission position (distance d shown in FIG. 2) and the intensity of light at the emission position.

In the present embodiment, in order to reproduce the texture of the surface of the object described above, texture reproduction printing is performed in which a print layer made of ink is formed on a substrate. By this texture reproduction printing, the printed matter 1 shown in FIG. 3 is generated. The surface of the printed matter 1 (the surface on the side to be visually recognized) reproduces the color, pattern, and texture of the surface of the object.

<About the printed matter generated in this embodiment>
Next, the printed matter 1 produced in the present embodiment will be described with reference to FIG. Note that FIG. 3 schematically illustrates the configuration of the printed matter 1, and for convenience of illustration, the thickness, size, and the like of each portion are different from the actual contents.

The printed matter 1 is composed of the base material 2 shown in FIG. 3 and the printed layer 5 formed on the surface (printed surface) of the base material 2. The base material 2 used for texture reproduction printing is a base material 2 for texture reproduction printing.

The base material 2 for reproducing the texture is a laminated body formed by laminating a thin plate-shaped internal scattering member 4 on white paper which is a white medium 3. Here, the internal scattering member 4 is a translucent (for example, semi-turbid or milky semi-colored) light-transmitting member, and the difference between the total light transmittance and the scattered light transmittance is 0% to 10%. Is. Specific examples of the internal scattering member 4 include a base material used for inkjet printing using an ultraviolet curable ink, such as a milky semi-colored or white acrylic plate, a vinyl chloride material, or a PET (polyethylene terephthalate) material. The internal scattering member 4 is more preferably a member having a total light transmittance of 10% to 80% or less and a transmitted light transmittance of 10% to 80%. Further, for the internal scattering member 4, the Haze value is preferably 1 to 90%, and more preferably the Haze value is 30 to 60%.
In the present embodiment, the thickness of each portion of the internal scattering member 4 is uniform, but the thickness is not limited to this, and the thickness of each portion of the internal scattering member 4 may vary.

The white paper, which is the white medium 3, constitutes the bottom layer of the printed matter 1. The white medium 3 is in close contact with the internal scattering member 4, and is adhered to, for example, on the surface of the internal scattering member 4. However, the white medium 3 is not limited to the case where it is adhered to the internal scattering member 4, and may be in contact with the internal scattering member 4. Further, it is preferable that the white medium 3 has the highest light reflectance in the printed matter 1 and is set so that the reflectance is 90% or more. Further, the white medium 3 is not limited to white paper, but is a white sheet, film, plate material, fiber body (cloth), plastic base material (for example, acrylic material, PET (polyethylene terephthalate) material, vinyl chloride material) and the like. Can be substituted.
The base material 2 for reproducing the texture is not limited to the base material having the white medium 3 and the internal scattering member 4, and may be, for example, the internal scattering member 4 alone, or the white medium 3 and the internal scattering member 4. It may have a member other than 4. Further, in the present embodiment, the thickness of each portion of the white medium 3 is uniform, but the thickness is not limited to this, and the thickness of each portion of the white medium 3 may vary.

The print layer 5 has a multi-layer structure in which a layer of ink landed (adhered) is laminated on the surface of the base material 2 which is a printing surface. Further, the print layer 5 is formed on the printed surface of the base material 2 based on the data regarding the texture of the surface of the object (specifically, the thickness data and the light scattering characteristic data described later).

The inks used in this embodiment are YMC (yellow, magenta, and cyan) three-color ink, which is a color fluid, black (K) ink, which is a black fluid, white ink, which is a white fluid, and clear ink. be. The color ink contains a colored pigment or dye and is a general ink used for color printing. The black ink is a black ink containing carbon black at a high concentration. The white ink contains a white pigment or dye and is a white ink used for, for example, underprinting. Clear ink is an ultraviolet curable fluid that cures when it receives light (specifically, ultraviolet rays). The clear ink used to form the print layer 5 in the present invention may be a transparent fluid that can be cured by irradiation with light. Further, examples of the irradiation light include ultraviolet rays, infrared rays, visible light and the like.

Further, in the present embodiment, the formation range of the print layer 5 on the print surface is divided into a plurality of unit areas, and the print layer 5 is imagewise according to the position of each unit area as shown in FIG. It is formed. As a result, the texture reproduced in the printed matter 1 changes according to each part of the printed matter 1. In other words, the texture of each part of the printed matter 1 is determined according to the structure (layer structure) of each part in the printed matter 5.

Here, the unit region, which is a unit for partitioning the formation range of the print layer 5 on the print surface, is a minute rectangular region, which is a divided region set when defining the light scattering characteristics of the object. More specifically, the unit area is set to a size corresponding to the resolution (pixels) when the surface of the object is photographed by the camera when the light scattering characteristic is measured by using a camera or the like, for example. A region, or a wider sized region obtained by averaging its size.

To explain the print layer 5 in detail, as shown in FIG. 3, the print layer 5 has a transparent layer 8 over the entire area (that is, the entire print surface). The transparent layer 8 is an ink layer formed by curing the clear ink that has landed on the base material 2, and is a layer in which light is most easily propagated and has a great influence on the texture. The transparent layer 8 is formed for the purpose of reproducing the sense of depth of the transparent portion exposed on the surface of the object. Therefore, in the portion 1a of the printed matter 1 corresponding to the transparent portion, the transparent layer 8 is arranged on the outermost surface layer of the printed matter 5 as shown in FIG.

The formation of the transparent layer 8 is not limited to the case where the transparent layer 8 is formed, and for example, a transparent acrylic plate, a vinyl chloride plate, or the like may be arranged as the transparent layer 8.

As a supplement to the transparent layer 8, in the present embodiment, the transparent layer 8 is formed over the entire printed layer 5 (in other words, all unit regions) as described above. Then, as shown in FIG. 3, each portion of the transparent layer 8 is located at substantially the same position in the thickness direction (vertical direction) of the printed matter 1. Further, the thickness of each portion of the transparent layer 8 is uniform as shown in FIG. However, the thickness is not limited to this, and the thickness of each portion of the transparent layer 8 may vary from non-uniformity. Further, the positions (upper and lower positions) of the respective parts of the transparent layer 8 in the thickness direction of the printed matter 1 may be different for each part.

On the other hand, in the portion 1b of the printed matter 1 corresponding to the portion different from the transparent portion of the object (that is, the colored portion of the object), as shown in FIG. 3, the color layer 6 is the outermost layer of the printed matter 5. Be placed. The color layer 6 is an ink layer composed of three YMC color inks.

Further, in the present embodiment, the white layer 7 composed of white ink is arranged in the print layer 5. The white layer 7 is arranged at a position on the print layer 5 according to the data regarding the texture of the surface of the object (specifically, the thickness data and the light scattering characteristic data described later). More specifically, the formation conditions of the print layer 5 are set based on the above data, and as a result of the formation of the print layer 5 according to the formation conditions, the white layer 7 is arranged in an image-wise manner in the print layer 5. To.

Explaining in more detail with reference to FIG. 3, in the printed matter 1, in the portion 1a corresponding to the transparent portion, the white layer 7 is arranged between the transparent layer 8 and the base material 2, and in the present embodiment, the transparent layer 7 is arranged. Immediately below 8, the white layer 7 is adjacent to the transparent layer 8. By providing the white layer 7 directly under the transparent layer 8 in this way, the light reflection from the lower layer of the transparent layer 8 can be visually recognized more clearly. Thereby, for example, in reproducing the sense of depth of the transparent portion having a relatively thick thickness, even if the thickness of the transparent layer 8 is made relatively thin, the above-mentioned sense of depth is satisfactorily reproduced by the white layer 7.

On the other hand, in the portion 1b of the printed matter 1 corresponding to the colored portion, the white layer 7 is arranged between the color layer 6 and the transparent layer 8 as shown in FIG. 3, and in the present embodiment, the white layer 7 is directly below the color layer 6. The white layer 7 is adjacent to the color layer 6. By providing the white layer 7 directly below the color layer 6 in this way, the light incident from above the color layer 6 is transmitted by the color layer 6 and then reflected by the white layer 7. As a result, the light that has passed through the color layer 6 is efficiently reflected without being scattered and absorbed, so that the light can be seen relatively clearly by the viewer. As a result, in the portion 1b corresponding to the colored portion, for example, when the light incident on the portion is reflected at a position distant from the incident position due to internal scattering, the distance between the incident position and the reflected position is not so far. The scattering characteristics are reproduced.

Further, in the present embodiment, the black layer 9 composed of the black (K) ink is arranged in the print layer 5. As shown in FIG. 3, the black layer 9 is arranged between the white layer 7 and the base material 2 in the region where the white layer 7 exists in the print layer 5. More specifically, when the print layer 5 is viewed from the visual side, the black layer 9 has the outer edge of the white layer 7 and the outer edge of the black layer 9 at the same place where the white layer 7 is arranged. (That is, in this embodiment, the white layer 7 and the black layer 9 completely overlap each other).

Explaining in more detail with reference to FIG. 3, in both the portion 1a corresponding to the transparent portion and the portion 1b corresponding to the colored portion of the printed matter 1, the black layer 9 is between the white layer 7 and the base material 2. Is arranged, and in the present embodiment, the black layer 9 is adjacent to the white layer 7 directly under the white layer 7. In particular, in the portion 1b corresponding to the colored portion, as shown in FIG. 3, a black layer 9 is further provided at a position directly below the transparent layer 8, and the black layer 9 is adjacent to the transparent layer 8.

In the present embodiment, since the black layer 9 is arranged below the white layer 7 as described above, the light reflected by the white layer 7 spreads (diffuses) toward the periphery of the white layer 7. At that time, the black layer 9 absorbs the light. As a result, the abnormal propagation of light to the periphery of the white layer 7 is suppressed. Such an effect is more effectively exhibited when the black layer 9 is adjacent to the white layer 7 at a position directly below the white layer 7.

As described above, in the present embodiment, the white layer 7 and the black layer 9 completely overlap each other. In other words, when the print layer 5 is viewed from the visual recognition side, the entire surface of the black layer 9 is a white layer. It is obscured by 7. This makes it possible to prevent the black layer 9 from being noticed by the viewer.

Incidentally, when the print layer 5 is viewed from the visual recognition side, the entire surface of the black layer 9 may be covered by the white layer 7. For example, the plane size of the black layer 9 is the white layer 7 located directly above the white layer 7. It may be smaller than the plane size of. However, from the viewpoint of suppressing the abnormal propagation of light to the periphery of the white layer 7, it is better that the plane size of the black layer 9 and the plane size of the white layer 7 are the same and the black layer 9 and the white layer 7 completely overlap. , More preferred.

<Structure of printing system according to this embodiment>
Next, the configuration of the printing system 10 according to the present embodiment will be described. The printing system 10 is a facility that reproduces the texture of the surface of an object, and strictly speaking, produces a printed matter 1 that reproduces the texture. As shown in FIG. 4, the printing system 10 has a print layer forming device 20, a thickness data acquisition device 30, a light scattering characteristic data acquisition device 40, and a print control device 50 as main constituent devices. Hereinafter, each component device of the printing system 10 will be described individually.

(Print layer forming device)
The print layer forming apparatus 20 ejects ink as a fluid toward the printed surface of the base material 2 (that is, the upper surface of the internal scattering member 4) to form the printed layer 5 having a multilayer structure on the printed surface. It is a device. In the present embodiment, the print layer forming apparatus 20 is configured by, for example, an inkjet printer.

Specifically, the print layer forming apparatus 20 sequentially ejects various inks toward each unit area of the print surface of the base material 2 (strictly speaking, the range in which the print layer 5 is formed on the print surface). .. In each unit area, the dots of the landed ink form an ink layer, and a plurality of ink layers of each ink type are overlapped. As a result, the printed layer 5 having a multilayer structure is formed on the printed surface.

As shown in FIGS. 4 and 5, the print layer forming apparatus 20 includes a moving mechanism 21, a ejection mechanism 22, a curing mechanism 23, and a control mechanism 24. The moving mechanism 21 moves the base material 2 along the moving path 21R in the print layer forming apparatus 20. The moving mechanism 21 may be configured by a drive roller as shown in FIG. 5, or may be configured by a drive belt.

The moving mechanism 21 is a one-way transport type moving mechanism that moves the base material 2 only in the forward direction from the viewpoint of further increasing the printing speed. However, the present invention is not limited to this, and the base material 2 is reversibly moved to the downstream side by a certain distance along the movement path 21R, then reversely traveled to the upstream side by the same distance, and then moved to the downstream side again. It may be a transport type moving mechanism.

The ejection mechanism 22 is composed of a recording head that ejects various inks by driving a piezo element. The ejection mechanism 22 ejects various inks toward the printing surface as shown in FIG. 5 while the lower surface thereof faces the printing surface of the base material 2. More specifically, the discharge mechanism 22 can move in the scanning direction intersecting the moving direction of the base material 2. Further, as shown in FIG. 6, the lower surface of the ejection mechanism 22 is a nozzle surface 22S in which nozzle rows are formed for each ink type. The nozzle surface 22S has a nozzle row Nw for ejecting white ink, a nozzle row Ny for ejecting yellow ink, a nozzle row Nm for ejecting magenta ink, and a nozzle row for ejecting cyan ink in order from one end side in the scanning direction. Nc, a nozzle row Nk for ejecting black ink, and a nozzle row Nh for ejecting clear ink are provided in one row each. However, the number of nozzle rows for ejecting various inks, the arrangement position, and the like can be arbitrarily set, and a configuration other than the configuration shown in FIG. 6 may be used.

Then, while the nozzle surface 22S faces the printing surface of the base material 2, the ejection mechanism 22 moves in the scanning direction at a position directly above the printing surface by a carriage (not shown) by the shuttle scanning method, while the printing surface The type of ink corresponding to each unit area is ejected toward each unit area inside. Various types of ink land on the unit area of the ejection destination to form dots. As a result, on the surface of the base material 2, the print layer 5 in which the color layer 6, the white layer 7, the transparent layer 8 and the black layer 9 are arranged in an imagewise manner according to the position of each unit region is formed. It is formed.

The method of ejecting ink from the ejection mechanism 22 is not limited to the piezo element drive method. For example, various ejection methods can be used, including a thermal jet method in which ink droplets are blown by the pressure of bubbles generated by heating ink with a heating element such as a heater. Further, in the present embodiment, the ejection mechanism 22 is composed of a serial type head and ejects ink by a shuttle scan method, but the present invention is not limited to this. For example, the ejection mechanism 22 is configured by a full-line type head, and may eject ink by a single-pass method. Further, in the present embodiment, all the nozzle rows of various inks are formed on the same nozzle surface 22S, but the present invention is not limited to this. For example, the ejection mechanism 22 may be composed of a plurality of recording heads, and each recording head may eject inks of different types from each other.

The curing mechanism 23 irradiates the dots of the clear ink that have landed on the printing surface of the base material 2 with light (strictly speaking, ultraviolet rays) to cure the dots of the clear ink. The curing mechanism 23 is composed of, for example, a metal halide lamp, a high-pressure mercury lamp, an ultraviolet LED (Light Emitting Diode), etc., and is arranged downstream of the ejection mechanism 22 in the moving direction of the base material 2 in the present embodiment. There is.

In this embodiment, the discharge mechanism 22 and the curing mechanism 23 are arranged apart from each other in the moving direction of the base material 2. However, the present invention is not limited to this, and the ejection mechanism 22 and the curing mechanism 23 are mounted on a common carriage (not shown), and the ejection mechanism 22 and the curing mechanism 23 are integrally moved in the scanning direction. There may be. In such a configuration, the curing mechanism 23 is arranged at a position beside the ejection mechanism 22, and immediately after the ejection mechanism 22 ejects the clear ink in one scanning operation, the curing mechanism 23 performs the clear ink (strictly speaking, the clear ink). It is preferable to irradiate ultraviolet rays toward the clear ink dots) that have landed on the printing surface.

The control mechanism 24 is a controller built in the print layer forming device 20, and controls each of the moving mechanism 21, the ejection mechanism 22, and the curing mechanism 23 via a drive circuit (not shown). More specifically, the control mechanism 24 receives the print data sent from the print control device 50. The print data is data indicating the formation conditions of the print layer 5. The print data will be described in detail later.

Immediately after receiving the print data, for example, when the predetermined base material 2 is manually inserted into the base material introduction port (not shown) of the print layer forming apparatus 20, the control mechanism 24 picks up the base material 2. The movement mechanism 21 is controlled so as to move intermittently along the movement path 21R.

Next, the control mechanism 24 controls the ejection mechanism 22 according to the print data while the nozzle surface 22S of the ejection mechanism 22 and the printing surface of the base material 2 face each other, and directs the ejection mechanism 22 toward each unit area of the printing surface. Ink is ejected from the ejection mechanism 22. At this time, the type, amount, density, and the like of the ink landing on each unit area are determined according to the formation conditions indicated by the print data.

Further, the control mechanism 24 alternately repeats the moving operation of the base material 2 by the moving mechanism 21 and the scanning operation of the ejection mechanism 22, and controls the nozzle for ejecting ink in each scanning operation. As a result, ink dots can be superposed on the same unit area on the printing surface. For example, by superimposing dots of the same type of ink, the thickness of the ink layer made of the ink can be adjusted. Will be. Further, by superimposing dots of another type of ink on the dots of one type of ink, the above-mentioned multilayer structure is formed.

The stacking order of each ink layer in the multilayer structure is as described above. For example, in the portion 1a corresponding to the transparent portion of the object, the transparent layer 8 is arranged as the outermost layer. On the other hand, in the portion 1b corresponding to the colored portion of the object, the color layer 6 is arranged as the outermost layer.

Further, the control mechanism 24 controls the curing mechanism 23 to irradiate the ultraviolet rays in parallel with the ejection of the ink to the ejection mechanism 22. As a result, in the unit region where the dots of the clear ink exist, the dots of the clear ink are cured to form the transparent layer 8.

Then, when the control mechanism 24 controls the moving mechanism 21, the ejection mechanism 22, and the curing mechanism 23 according to the formation conditions indicated by the print data, the number of laminated ink layers, the type and thickness of each ink layer are adjusted for each unit region. In other words, each part of the print layer 5 is formed in an image-wise manner according to the position of each part. As a result, the texture of the surface of the object is reproduced on the surface of the print layer 5 (the surface on the visual recognition side).

Then, the base material 2 on which the print layer 5 is formed on the printed surface, that is, the printed matter 1, is moved to the discharge port of the print layer forming device 20 by the moving mechanism 21 and discharged from the discharge port to the outside of the print layer forming device 20. Printed matter.

Further, the print layer forming apparatus 20 according to the present embodiment can form the sample patterns SP1 to SP5 shown in FIG. 7 on the base material 2. Each sample pattern SP1 to SP5 is composed of an ink layer having only one color and one layer, and is formed as a printed image necessary for the light scattering characteristic data acquisition device 40 described later to acquire light scattering characteristic data for each ink type.

Explaining the sample patterns SP1 to SP5, as shown in FIG. 7, the sample patterns SP1 to SP5 are formed by gradually changing the density of dots for each of the YMCK4 color ink and the white ink. Here, the dot density means the occupancy rate of dots in a unit area, in other words, the pattern density (shading). The dot density is determined by the dot size and the number of dots in a unit area.

When the print layer forming apparatus 20 forms the sample patterns SP1 to SP5 on the base material 2, the control mechanism 24 receives the print data for forming the sample pattern from the print control apparatus 50. The print data for forming the sample pattern defines the formation conditions of each sample pattern SP1 to SP5 (specifically, the position of each sample pattern SP1 to SP5, the type of ink used, the density of dots, etc.). .. Upon receiving the print data for forming the sample pattern, the control mechanism 24 controls the moving mechanism 21, the ejection mechanism 22, and the curing mechanism 23 according to the data. As a result, for each color of ink, each sample pattern SP1 to SP5 is formed on the base material 2 by gradually changing the density of dots. The base material 2 used for forming the sample pattern may be a base material 2 for reproducing the texture, or may be a base material 2 (for example, white paper) different from the base material 2 for reproducing the texture. ..

(Thickness data acquisition device)
The thickness data acquisition device 30 is a device that acquires thickness data regarding the thickness of the transparent portion exposed on the surface of the object. The thickness data acquisition device 30 according to the present embodiment is composed of an X-ray CT (Computed Tomography) measuring device, acquires a tomographic image of an object by an X-ray CT scan, renders the tomographic image, and performs a transparent portion. The thickness of the transparent part is measured by making it three-dimensional (for example, "Tsushi Nakano, Yoshito Nakajima, Koichi Nakamura, Susumu Ikeda," Observation and analysis method of rock internal structure by X-ray CT ", Journal of the Geological Society, No. See Vol. 106, No. 5, pp.363-378, May 2000).

Further, in the present embodiment, the surface of the object is divided into a plurality of unit surface regions, the thickness data acquisition device 30 measures the thickness for each unit surface region, and the thickness data indicating the thickness for each unit surface region is acquired. It is supposed to be. Here, the unit surface region is the same as that for dividing the surface of the object into a plurality of unit regions on the printed surface of the base material 2 (strictly speaking, the formation range of the printed layer 5 on the printed surface). It is a unit when it is divided.

Explaining in an easy-to-understand manner with reference to FIG. 8, both the printed surface of the base material 2 (indicated by the symbol 2A in FIG. 8) and the surface of the object (indicated by the symbol TA in FIG. 8) have a rectangular shape. Is. When each is divided into a plurality of minute areas, each minute area constituting the printed surface is the above-mentioned unit area (indicated by the symbol 2B in FIG. 8), and each minute area constituting the surface of the object is a unit. It is a surface region (indicated by the symbol TB in FIG. 8).
In FIG. 8, for convenience of illustration, the number of unit regions constituting the printed surface and the number of unit surface regions constituting the surface of the object are shown to be smaller than the actual number.

Further, each unit surface area on the surface of the object is associated with a unit area arranged at the same position as the arrangement position of each unit surface area on the printed surface. For example, in FIG. 8, the unit surface area surrounded by a circle frame and the unit area correspond to each other.

(Light scattering characteristic data acquisition device)
The light scattering characteristic data acquisition device 40 acquires light scattering characteristic data which is data related to the light scattering characteristic. In the present embodiment, the light scattering characteristic is a Modulated Transfer Function (hereinafter referred to as MTF) and a Bidirectional Scattering Surface Reflectance Distribution Funcition (hereinafter referred to as BSSRDF). The light scattering characteristic data acquisition device 40 acquires light scattering characteristic data indicating the light scattering characteristics represented by these functions. Further, the light scattering characteristic data acquisition device 40 according to the present embodiment light-scatters a plurality of types of light having different wavelengths, specifically, light of each color of R (red), G (green), and B (blue). Acquire characteristic data.

The method of acquiring data showing the light scattering characteristics will be roughly described. For the light scattering characteristics represented by MTF, for example, the light scattering characteristics to be measured are measured using the rectangular wave chart LP shown in FIG. Obtained at. As shown in FIG. 9, the rectangular wave chart LP is a measurement chart composed of a plurality of rectangular patterns LPx formed on a transparent substrate such as a glass plate at predetermined intervals. When measuring the light scattering characteristics, the measurement target and the square wave chart LP are brought into close contact with each other, and the light is incident from the square wave chart LP side to measure the reflected light of the measurement target. At this time, as a result of the transmitted light of the rectangular wave chart LP being scattered inside the measurement target, the edge portion of the rectangular pattern LPx is blurred and measured slightly dark. Qualitatively speaking, this degree of blurring indicates the light scattering characteristics of the object to be measured. Further, as a method for quantitatively evaluating the degree of blurring, that is, the light scattering characteristic of the measurement target, a method of calculating the MTF showing the light scattering characteristic can be used.

As an example of the method for calculating the MTF, the method described in Japanese Patent Application Laid-Open No. 2012-205124 can be mentioned, but the method is not limited to the method described in the same publication, and an MTF exhibiting light scattering characteristics can be used as another method. You may ask at.

Regarding the light scattering characteristics represented by BSSRDF, the intensity of the incident light in the irradiation direction to the measurement target and the intensity of the reflected light of the measurement target in the observation direction are measured by changing the irradiation direction and the observation direction, respectively. It can be obtained by. As a method for acquiring the light scattering characteristic data shown by BSSRDF, a known method can be used (for example, "Cuccia DJ,"
Bevilacqua F, Durkin AJ, Tromberg BJ (2005) Modulated imaging: quantitative analysis and tomography of turbid media in the spatial-frequency domain. Opt Lett 30 (11): 1354-1356. ”). Further, the light scattering characteristic of BSSRDF may be measured by using the measuring device described in JP-A-2017-020816.

As described above, the light scattering characteristic data acquisition device 40 acquires the light scattering characteristic data of the measurement target as shown in FIG. 10 by measuring the light scattering characteristic of the measurement target using the light of each of the three RGB colors. can do. FIG. 10 is a diagram showing MTFs showing the measured light scattering characteristics of the measurement target for each color of light. The horizontal axis of FIG. 10 shows the spatial frequency, and the vertical axis of FIG. 10 shows the intensity of the reflected light (ratio to the intensity of the incident light).

In the present embodiment, the light scattering characteristic is represented by MTF or BSSRDF, and the data showing the measurement result is acquired by the light scattering characteristic data acquisition device 40, but the present invention is not limited to this. For example, the light scattering characteristic may be represented by a point spread function (PSF), and data indicating the measurement result may be acquired.

Then, the light scattering characteristic data acquisition device 40 according to the present embodiment measures the light scattering characteristics of various members as measurement targets and acquires the light scattering characteristic data.
Specifically, the light scattering characteristic data acquisition device 40 first measures the light scattering characteristics of the object for reproducing the texture. As a result, the light scattering characteristic data acquisition device 40 acquires data regarding the light scattering characteristics with respect to the incident light on the surface of the object (hereinafter, also referred to as first light scattering characteristic data). In the present embodiment, the surface of the object is divided into a plurality of unit surface regions as described above, and the light scattering characteristic data acquisition device 40 is the first light scattering characteristic data showing the light scattering characteristics for each unit surface region. To get.

Secondly, the light scattering characteristic data acquisition device 40 acquires data on the light scattering characteristics of the various inks (hereinafter, also referred to as second light scattering characteristic data) for the various inks constituting the print layer 5. Specifically, as described above, the print layer forming apparatus 20 changes the dot density stepwise for each of the YMC three-color ink, the black (K) ink, and the white ink, and a plurality of sample patterns. Form SP1 to SP5 (see FIG. 7). The light scattering characteristic data acquisition device 40 measures the light scattering characteristics for each of the sample patterns SP1 to SP5. As a result, the light scattering characteristic data acquisition device 40 acquires the second light scattering characteristic data for each ink type for each density by changing the density of the dots.

Third, the print layer forming apparatus 20 measures the light scattering characteristics of each of the plurality of types of internal scattering members 4 constituting the base material 2 for reproducing the texture. As a result, the print layer forming apparatus 20 acquires data on the light scattering characteristics of each type of internal scattering member 4 (hereinafter, also referred to as third light scattering characteristic data). Here, it is assumed that the parameters that change according to the internal scattering performance (light scattering characteristics) are different between the internal scattering members 4 that are different from each other, and for example, the Haze value is different. In other words, the light scattering characteristics of the printed matter 1 can be changed by changing the type of the internal scattering member 4 to be used and changing the Haze value.

(Print control device)
The print control device 50 is a device for forming the print layer 5 on the print layer forming device 20 based on the data regarding the texture of the object (specifically, the above-mentioned thickness data and the light scattering characteristic data). In the present embodiment, the print control device 50 is composed of, for example, a host computer (hereinafter, simply referred to as “computer”) connected to the print layer forming device 20.

The computer forming the print control device 50 is equipped with a processor such as a CPU (Central Processing Unit) and a memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and the memory has a texture. A program for reproduction and a program such as a printer driver are stored. Then, the print control device 50 creates print data for texture reproduction for reproducing the texture of the surface of the object by the above-mentioned processor executing an application program for texture reproduction and a printer driver.

Explaining the print data for texture reproduction, the print data is data showing the formation conditions of the print layer 5 as described above. Here, the formation conditions include a layer structure including the presence or absence of the color layer 6, the thickness of each ink layer, the density (density) of dots in each ink layer, and the internal scattering member of the base material 2 for reproducing the texture. It is a combination of parameters such as 4 types. A plurality of forming conditions can be determined by changing each of the above-mentioned parameters, and among them, the one actually adopted at the time of forming the print layer is selected according to the texture to be reproduced.

The conditions for forming the print layer 5 may be any conditions relating to at least one of the above parameters, and may include conditions relating to parameters other than the above parameters.

Further, in the present embodiment, the print layer formation range on the print surface of the base material 2 is divided into a plurality of unit regions, and the formation conditions actually adopted when the print layer 5 is formed are set for each unit region. It has become.

Then, the print control device 50 creates print data indicating the formation conditions set for each unit area, and transmits the print data to the print layer forming device 20. In the print layer forming apparatus 20, the control mechanism 24 receives the print data and controls each part of the print layer forming apparatus 20 according to the print data. As a result, the print layer forming apparatus 20 forms the print layer 5 on the print surface of the base material 2. At this time, the print layer forming apparatus 20 forms each portion of the print layer 5 according to the formation conditions set for the unit region corresponding to each portion. As a result, each portion of the print layer 5 is formed in an image-wise manner according to the position of each portion.

The procedure for creating print data for texture reproduction will be described in detail in the next section "Procedure for generating printed matter".

<Procedure for generating printed matter>
Next, the flow of the texture reproduction printing described above will be described as a procedure for generating the printed matter 1 by the printing method of the present invention.
The printing method used for texture reproduction printing is a printing method for reproducing the texture of the surface of an object. Further, as shown in FIG. 11, for texture reproduction printing, thickness data acquisition processing S001, sample pattern printing processing S002, light scattering characteristic data acquisition processing S003, light scattering characteristic estimation processing S004, formation condition setting processing S005, and print data transmission. It is composed of a process S006 and a print layer forming process S007. Hereinafter, each process will be described individually.

(Thickness data acquisition process)
The thickness data acquisition process is a process in which the thickness data acquisition device 30 acquires thickness data regarding the thickness of the transparent portion exposed on the surface of the object. More specifically, the surface of the object is divided into a plurality of unit surface regions, and the thickness data acquisition device 30 measures the thickness of the transparent portion for each unit surface region. As a matter of course, the thickness in the unit surface region that does not correspond to the transparent portion is 0.
Then, when the measurement of the thickness of all the unit surface regions is completed, the thickness data acquisition device 30 acquires the thickness data indicating the thickness of each unit surface region. Further, the thickness data acquisition device 30 transmits the acquired thickness data to the print control device 50.

(Sample pattern printing process)
The sample pattern printing process is a process of forming the above-mentioned sample patterns SP1 to SP5 on the printed surface of the base material 2 by the printing layer forming apparatus 20. More specifically, the print control device 50 transmits print data for forming a sample pattern to the print layer forming device 20, and the control mechanism 24 of the print layer forming device 20 receives the print data. The print data for forming the sample pattern is created in advance and stored in the memory in the print control device 50.

The control mechanism 24 controls the moving mechanism 21, the ejection mechanism 22, and the curing mechanism 23 according to the print data for forming the sample pattern. As a result, sample patterns SP1 to SP5 are printed on the printed surface of the base material 2 by gradually changing the dot density (density) for each of the five colors of YMCK and white ink (see FIG. 7). .. Each sample pattern SP1 to SP5 is composed of a plurality of pattern pieces having different dot densities (density). Here, the number of pattern pieces constituting each sample pattern SP1 to SP5 and the dot density (density) in each pattern piece can be freely set, but in the example shown in FIG. 7, the pattern pieces The number of these is four, and the concentrations in each pattern piece are 25%, 50%, 75%, and 100%.

(Light scattering characteristic data acquisition processing)
The light scattering characteristic data acquisition process is a process in which the light scattering characteristic data acquisition device 40 acquires the first light scattering characteristic data, the second light scattering characteristic data, and the third light scattering characteristic data described above. More specifically, first, the surface of the object is divided into a plurality of unit surface regions, and the light scattering characteristic data acquisition device 40 determines the light scattering characteristics (internal scattering characteristics) of the object with respect to the incident light on the surface of the object. Measured for each unit surface area. As a result, the light scattering characteristic data acquisition device 40 acquires the first light scattering characteristic data showing the light scattering characteristics for each unit surface region of the object.

Next, the light scattering characteristic data acquisition device 40 measures the light scattering characteristics (internal scattering characteristics) for each of the sample patterns SP1 to SP5 printed on the base material 2 in the above-mentioned sample pattern printing process. At this time, the light scattering characteristic data acquisition device 40 measures the light scattering characteristics of each of the plurality of pattern pieces constituting the sample patterns SP1 to SP5. That is, the light scattering characteristic data acquisition device 40 measures the light scattering characteristics for each dot density by changing the dot density (concentration) of each sample pattern SP1 to SP5. As a result, the light scattering characteristic data acquisition device 40 acquires the second light scattering characteristic data showing the light scattering characteristics for each dot density (density) for each type of ink.

Next, the light scattering characteristic data acquisition device 40 measures the light scattering characteristic (internal scattering characteristic) of the internal scattering member 4 possessed by the base material 2 for reproducing the texture. At this time, if a plurality of types of internal scattering members 4 are prepared, the light scattering characteristic data acquisition device 40 measures the internal scattering characteristics of each type of internal scattering member 4. As a result, the light scattering characteristic data acquisition device 40 acquires third light scattering characteristic data indicating the light scattering characteristics of the internal scattering member 4 for each type of the internal scattering member 4.

Then, the light scattering characteristic data acquisition device 40 transmits the acquired first light scattering characteristic data, second light scattering characteristic data, and third light scattering characteristic data to the print control device 50. In addition, in this embodiment, each light scattering characteristic data is the data which shows the light scattering characteristic represented by MTF or BSSRDF.

(Light scattering characteristic estimation processing)
In the light scattering characteristic estimation process, the print control device 50 determines the light scattering characteristics of the printed matter 1 according to the formation conditions of the print layer 5 based on the second light scattering characteristic data and the third light scattering characteristic data for each ink type. It is a process to estimate. Here, the "light scattering characteristic of the printed matter 1 according to the formation condition of the print layer 5" is the light scattering characteristic of the printed matter 1 generated when the print layer 5 is tentatively formed under a certain formation condition.

Further, in the present embodiment, as described above, the formation conditions of the printed matter 5 are set for each unit region, and in accordance with this, the light scattering of the printed matter 1 is also performed in the light scattering characteristic estimation process. The characteristics are to be estimated for each unit area.

Explaining the light scattering characteristic estimation process in detail, a plurality of conditions for forming the print layer 5 are prepared at the start of this process. Specifically, the number of laminated ink layers in the print layer 5, the types of inks constituting each ink layer, the thickness of each ink layer, the dot density (density) in each ink layer, and the base material 2 for reproducing the texture are used. A plurality of combinations are prepared for the type of the internal scattering member 4 used.

After that, the print control device 50 carries out the light scattering characteristic estimation process according to the flow shown in FIG. 12. Explaining the flow of the light scattering characteristic estimation process with reference to FIG. 12, the print control device 50 first sets a plurality of combinations regarding the formation conditions of the print layer 5 (S011). In this step S011, the contents of the above-mentioned formation conditions, specifically, the number of layers of the ink layers constituting the print layer 5, the types of inks constituting each ink layer, the thickness of each ink layer, and the dots in each ink layer. Each of the density and the type of the internal scattering member 4 is used as a parameter, and a combination of each possible parameter is specified.

In the present embodiment, among the contents (parameters) relating to the formation conditions, the thickness of the transparent layer 8 is specified based on the thickness data acquired by the thickness data acquisition process, and the transparent layer is specified among all the unit regions. It is assumed that the thickness of 8 is the same.

Next, the print control device 50 estimates the light scattering characteristics reproduced under the formation conditions related to the combination for each of the plurality of combinations related to the formation conditions set in step S011 (S012). Here, when the light scattering characteristic is expressed by BSSRDF, in order to estimate the BSSRDF characteristic as the light scattering characteristic, the combination of the conditions set in step S011 and the second for each ink type acquired for each dot density. The light scattering matrix calculation is performed using the light scattering characteristic data and the third light scattering characteristic data acquired for each type of the internal scattering member 4.

The light scattering matrix calculation is a matrix calculation for reflection and transmission of light (incident light) incident on a multilayer structure in each layer. This matrix calculation is performed until the incident light passes through the multilayer structure, or the incident light is repeatedly transmitted and reflected in each layer of the multilayer structure until it is emitted from the outermost surface of the multilayer structure. For a multilayer structure having a large number of layers, the matrix calculation ends when the amount of light is sufficiently attenuated or when light passes through a predetermined number or more of layers.

Explaining the light scattering matrix calculation in detail, the BSSRDF characteristics in a certain layer (layer M shown in FIGS. 13 to 16) in the multilayer structure are classified into the following four patterns.
Pattern 1: As shown in FIG. 13, light Ix is incident from above the layer M, and light Iy travels toward the top of the layer M (that is, reflection).
Pattern 2: As shown in FIG. 14, light Ix is incident from above the layer M, and light Iy travels toward the bottom of the layer M (that is, transmission).
Pattern 3: As shown in FIG. 15, light Ix is incident from below the layer M, and light Iy advances (that is, transmitted) toward the upper side of the layer M.
Pattern 4: As shown in FIG. 16, light Ix is incident from below the layer M, and light Iy travels toward the bottom of the layer M (that is, reflection).

A corresponding arithmetic matrix R is set for each of the above four patterns. The arithmetic matrix R is an arithmetic formula (for example, a determinant) shown in FIG. 17, and the light scattering vector on the incident side is multiplied by the arithmetic matrix R of the corresponding pattern to receive light scattering in the layer M. The later light scattering vector (that is, the light scattering vector on the emitting side) can be calculated.

The definition of each variable in FIG. 17 is as follows.
I: Light scattering vector, f: Arithmetic function θi (i is a natural number from 1 to n): i-th incident angle (vector)
Φi (i is a natural number from 1 to n): i-th emission angle (vector)
xx (k is a natural number from 1 to n): kth incident position yk (k is a natural number from 1 to n): indicates the kth emission position, and xx (k is a natural number from 1 to n) is the kth. Indicates the incident position of, and yk indicates the kth emission position.
Assuming that there is no absorption, if all the elements arranged in the same row in the arithmetic matrix R are added, it becomes 1 according to the law of conservation of energy.

Here, when the arithmetic matrix R corresponding to each of the above four patterns _{is expressed as RA m} , RB _m , RC _m , and RD _m , respectively, the relationship between the light scattering vector Ii on the incident side and the light scattering vector Ir on the reflection side. Is expressed by the following relational expression F1. By the way, the subscript m attached to each calculation matrix indicates the order of the layers, "1" is given to the layer located at the uppermost point (visual side), and "1" is given to the layer located immediately below it. 2 ”is given, and serial numbers after“ 3 ”are given to the layers below it.
Relational expression F1: Ir = RA ₁ * Ii
+ RC ₁ * RA ₂ * RB ₁ * Ii
+ RC ₁ * RA ₂ * RD ₁ * RA ₂ * RB ₁ * Ii
＋ ・ ・ ・ ・ ・ ・ ・ ・

In the light scattering matrix calculation described above, the combination of the conditions set in step S011, the second light scattering characteristic data for each ink type acquired for each dot density, and the second light scattering characteristic data for each type of the internal scattering member 4 were acquired for each type. The third light scattering characteristic data and is applied. As a result, the light scattering characteristic (specifically, the BSSRDF characteristic) of each unit region is calculated. Here, the BSSRDF characteristic as a calculation result is the light of the entire printed matter 1 including the printed layer 5 formed under each formation condition and the internal scattering member 4 of the base material 2 on which the printed layer 5 is formed. It is a scattering characteristic. In other words, the BSSRDF characteristic obtained from the light scattering matrix calculation is the estimation result of the light scattering characteristic for each part of the printed matter 1 which is the final product.

Although it has been described above that the BSSRDF characteristic is calculated and estimated as the light scattering characteristic, the present invention is not limited to this. For example, when the light scattering characteristic is expressed by MTF, the MTF characteristic as the light scattering characteristic is estimated. In order to estimate the MTF characteristics, the combination of the conditions set in step S011, the second light scattering characteristic data for each ink type acquired for each dot density, and the third light acquired for each type of the internal scattering member 4 are used. The light scattering analysis calculation will be performed using the scattering characteristic data.

式（１） The light scattering analysis calculation is a calculation for obtaining the MTF characteristics of the reflection related to the laminated structure for the light (incident light) incident on the laminated structure from the MTF characteristics of the reflection and the transmission related to each layer. For example, when the underlying layer is the p layer and the number of layers above the p layer is n (n is a natural number), the MTF characteristics of reflection related to the laminated structure consisting of n layers and the p layer are as follows. Described in (1).

Equation (1)

In the formula (1), _{R i} is the MTF characteristic of the reflection of the i-layer, _{T i} is the MTF characteristic of the transmission of the i layer.

式（１−１）
上式から分かるように、ｎ番目の層とｐ層のＭＴＦ特性が得られれば、２層の積層構造に関する反射のＭＴＦ特性を記述することができる。 Here, considering the laminated structure of two layers consisting of the nth layer and the p layer, the above formula (1) becomes the following formula (1-1).

Equation (1-1)
As can be seen from the above equation, if the MTF characteristics of the nth layer and the p layer are obtained, the MTF characteristics of the reflection related to the laminated structure of the two layers can be described.

式（１−２）
上式から分かるように、ｎ−１番目の層、ｎ番目の層及びｐ層のそれぞれについてＭＴＦ特性が得られれば、３層の積層構造に関する反射のＭＴＦ特性を記述することができる。 Further, considering the laminated structure of three layers including the nth layer, the n-1st layer and the p layer, the above formula (1) becomes the following formula (1-2).

Equation (1-2)
As can be seen from the above equation, if the MTF characteristics are obtained for each of the n-1st layer, the nth layer and the p layer, the MTF characteristics of the reflection regarding the laminated structure of the three layers can be described.

Based on the above points, the MTF characteristic of reflection (that is, the MTF characteristic described by the equation (1)) relating to the laminated structure having n layers and the p layer is, after all, the 1st to nth. If the MTF characteristics of each of the layer and the p layer can be obtained, it can be described.

In the light scattering analysis calculation described above, the condition contents specified for each unit area in step S011, the second light scattering characteristic data for each ink type acquired for each dot density, and each type of the internal scattering member 4 The third light scattering characteristic data acquired in the above is applied. As a result, the light scattering characteristics (specifically, MTF characteristics) of each unit region are calculated. Here, the MTF characteristic as the calculation result is the estimation result of the light scattering characteristic for each part of the printed matter 1 which is the final product, as in the light scattering matrix calculation.
As a specific example of the above-mentioned light scattering analysis calculation, for example, "Kubelka P (1954) New contributions to the optics of intensely light-scattering materials. Part II: Nonhomogeneous layers. J Opt Soc Am 44 (4): 330. -335. ”.

Then, in the light scattering characteristic estimation process, the above series of steps, that is, steps S011 and S012 in FIG. 12 are repeated for all the combinations related to the plurality of set formation conditions (S013). As a result, the light scattering characteristics of the printed matter 1 generated when the printed matter 5 is formed under the forming conditions related to each combination can be estimated by changing the combination. Then, the correspondence between the combination related to the formation conditions and the estimation result of the light scattering characteristics reproduced under the conditions related to the combination is converted into data as a look-up table (LUT), and the formation condition setting process to be performed later is performed. Referenced.

(Formation condition setting process)
The formation condition setting process was selected by selecting one of the optimum combinations for reproducing the texture of the surface of the object from a plurality of combinations related to the formation conditions set in the above-mentioned light scattering characteristic estimation process. This is a process of setting the formation conditions related to the combination as the formation conditions actually adopted when the print layer 5 is formed. Further, in the present embodiment, in the formation condition setting process, the formation conditions adopted at the time of forming the print layer 5 are set for each unit area.

The formation condition setting process will be described in detail. In the formation condition setting process, the acquired first light scattering characteristic data and the thickness data are used. Further, in the formation condition setting process, the correspondence between the combinations related to the formation conditions specified in the above-mentioned light scattering characteristic estimation process and the estimation results of the light scattering characteristics reproduced under the formation conditions related to each combination ( More precisely, it refers to a lookup table (look-up table showing correspondence).

The formation condition setting process is carried out according to the flow shown in FIG. Specifically, first, the light scattering characteristic indicated by the first light scattering characteristic data is specified for one unit surface region on the surface of the object (S021). Next, the light scattering characteristics specified in step S021 are compared with the scattering results of the light scattering characteristics shown in the above lookup table (S022).

After that, in the lookup table, the estimation result of the light scattering characteristic closest to the light scattering characteristic specified in step S021 (that is, the estimation result of the light scattering characteristic that minimizes the error from the light scattering characteristic specified in step S021). Is specified, and a combination of conditions that can reproduce the estimation result of the specified light scattering characteristic is determined from the above lookup table (S023). As a result, for one unit surface area and the corresponding unit area, the optimum combination of conditions for reproducing the texture of the unit surface area is selected. Specifically, the layer structure, the thickness of each ink layer excluding the transparent layer 8, the dot density in each ink layer, and the type of the internal scattering member 4 possessed by the base material 2 to be used are selected.

The steps S021 to S023 described above are repeated until all of the plurality of unit surface regions on the surface of the object are performed (S024). Further, the thickness of the transparent layer 8 in each unit region is determined based on the thickness of each unit surface region indicated by the thickness data (S025). At this time, the thickness of the transparent layer 8 in each unit region is set to be the same among all the unit regions. Once the thickness of the transparent layer 8 is determined, the number of times the clear ink is ejected (the number of drops) required to achieve the thickness is determined.

When the series of steps S021 to S025 up to the above are completed, a combination of conditions suitable for reproducing the texture of the object is selected for each unit area, and the formation conditions related to the selected combination are the formation of the print layer 5. It is set for each unit area as a formation condition that is sometimes adopted.

(Print data transmission process)
The print data transmission process is a process in which the print control device 50 creates print data indicating the formation conditions set for each unit area in the formation condition setting process, and transmits the print data to the print layer forming device 20. be.

(Print layer formation process)
The print layer forming process is a process in which the print layer forming apparatus 20 forms (prints) a multi-layered print layer 5 on the base material 2 for texture reproduction according to print data. Here, the print data is created by the print control device 50 based on data relating to the texture of the object (specifically, thickness data and light scattering characteristic data). From this point of view, it can be said that the print layer forming process is a process of forming the printed layer 5 having a multilayer structure on the base material 2 for reproducing the texture based on the data on the texture of the object.

Further, in the present embodiment, in the print layer forming process, the print layer 5 having the transparent layer 8, the white layer 7, and the black layer 9 is formed.
The print layer forming process will be described in detail. In this process, first, a group having a base material 2 for texture reproduction (that is, a white medium 3 having a uniform thickness and an internal scattering member 4 superposed on the white medium 3). Material 2) is prepared and set in the print layer forming apparatus 20. More specifically, the base material 2 having the type of internal scattering member 4 indicated by the print data sent from the print control device 50 is set. Further, in the present embodiment, the thickness of each portion of the internal scattering member 4 is uniform. Therefore, in the present embodiment, in the print layer forming process, the print layer 5 is formed on the surface of the internal scattering member 4 having a uniform thickness.

After the setting of the base material 2 is completed, the control mechanism 24 of the print layer forming apparatus 20 controls the movement mechanism 21, the ejection mechanism 22, and the curing mechanism 23 according to the print data. Specifically, the control mechanism 24 conveys the set base material 2 to the moving mechanism 21.

Further, the control mechanism 24 controls each part of the print layer forming apparatus 20 so that the print layer 5 is formed on the base material 2 according to the formation conditions indicated by the print data. At this time, the control mechanism 24 controls each part of the print layer forming apparatus 20 so that each part of the print layer 5 is formed according to the formation conditions set for the unit area corresponding to each part. As a result, each portion of the print layer 5 is formed in an image-wise manner according to the position of each portion.

More specifically, in the present embodiment, the transparent layer 8 having a uniform thickness is formed over the entire area of the print layer 5. In the present embodiment, the clear ink is landed on the ink layer before the ink layer (for example, the white layer 7 and the black layer 9) located directly under the transparent layer 8 is cured, and the landed clear ink dots are formed. The transparent layer 8 is formed by irradiating the dots with ultraviolet rays to cure the dots. However, the present invention is not limited to this, and after the white layer 7 and the black layer 9 are formed on the base material 2, an acrylic plate or a vinyl chloride plate having a uniform thickness immediately above the white layer 7 or a vinyl chloride plate (hereinafter, acrylic plate or the like) is formed. The transparent layer 8 may be formed by arranging. In this case, a layer of clear ink is formed directly under the acrylic plate or the like, and after the acrylic plate or the like is layered on the layer, the clear ink is irradiated with light to cure the layer of the clear ink. It is good. Alternatively, clear ink or a primer or the like is applied to the lower surface of the acrylic plate or the like, and the ink layer or the like is cured after being layered on the ink layer (white layer 7 and black layer 9) located immediately below the ink layer. It may be in close contact with the ink.

Further, in the unit surface region corresponding to the transparent portion on the surface of the object and the unit region corresponding to the transparent portion, the transparent layer 8 and the adjacent white layer 7 are arranged between the transparent layer 8 and the base material 2 for reproducing the texture. To. That is, in the above unit region, the white layer 7 is formed by the white ink before the transparent layer 8 is formed, and immediately after that, the transparent layer 8 is formed so as to be superimposed on the white layer 7.

On the other hand, a color layer 6 forming the outermost layer of the print layer 5 is formed in the unit surface region corresponding to the colored portion on the surface of the object, and between the color layer 6 and the transparent layer 8. A white layer 7 adjacent to the color layer 6 is arranged at. That is, in the above unit region, the white layer 7 is formed by the white ink after the transparent layer 8 is formed, and immediately after that, the color layer 6 is formed so as to be superimposed on the white layer 7.

Further, in each unit region, the white layer 7 is formed according to the formation conditions set for each unit region (specifically, the dot density and the thickness set for each unit region). As a result, the white layer 7 is arranged in an image-like manner on each portion of the print layer 5 according to the position of each portion.

Further, in the region where the white layer 7 exists in the print layer 5 (that is, the unit region where the white layer 7 is formed), the white layer 7 and the base material 2 for reproducing the texture are adjacent to the white layer 7. The black layer 9 is arranged. That is, in the unit region where the white layer 7 is formed, the black layer 9 is formed by the black (K) ink, and immediately after that, the white layer 7 is formed so as to be superimposed on the black layer 9.

In the unit region where the white layer 7 is formed and which corresponds to the unit surface region corresponding to the colored portion, the transparent layer 8 is located between the transparent layer 8 and the base material 2 for reproducing the texture. The black layer 9 adjacent to the above is further arranged. That is, in the above unit region, the transparent layer 8 is formed immediately after the black layer 9 is formed by the black (K) ink, and the black layer 9 is formed again immediately above the transparent layer 8.

The print layer forming process is carried out in the above manner, and the printed matter 1 which is the final product is produced at the end of this process. The surface of the generated printed matter 1 (the surface on the visual recognition side) is a good reproduction of the texture of the surface of the object.

<About the effectiveness of this embodiment>
As described above, in the present embodiment, it is possible to perform texture reproduction printing at high speed and appropriately. Further, in the present embodiment, it is possible to provide the printed matter 1 in which the abnormal propagation of light to the periphery of the white layer 7 is suppressed in the printed layer 5. In these respects, the present embodiment is more effective than the technique described in Patent Document 1 exemplified as the prior art.

More specifically, as described in the section "Problems to be Solved by the Invention", in the technique described in Patent Document 1, the thickness of the transparent layer is made constant in the printed matter, and further below the transparent layer ( More strictly, the white layer is placed at the position directly below). The white layer is provided in a portion of the printed matter where light scattering is suppressed (that is, a portion where light internal scattering is small). As a result, the optical texture can be adjusted simply by providing the white layer without changing the thickness of the transparent layer depending on the location, so that the texture reproduction printing can be performed at higher speed.

However, there is a possibility that the light incident on the printed matter propagates abnormally through the white layer, and in particular, when the white layer is provided in the vicinity of the transparent layer as in the technique described in Patent Document 1, the abnormal propagation of light is remarkable. It becomes.

On the other hand, in the present embodiment, the black layer 9 is arranged below the white layer 7 in the print layer 5. As a result, when the light reflected by the white layer 7 spreads (diffuses) toward the periphery of the white layer 7, the black layer 9 absorbs the light. As a result, the abnormal propagation of light to the periphery of the white layer 7 is suppressed.

As described above, in the present embodiment, since it is possible to suppress the abnormal propagation of light to the periphery of the white layer 7 while taking advantage of forming the white layer 7, texture reproduction printing is performed at high speed and appropriately. Will be printed.

The above effect is achieved by arranging the black layer 9 below the white layer 7 in the print layer 5, and to the extent that the black layer 9 is arranged, another layer (for example, for example) is provided between the white layer 7 and the black layer 9. The transparent layer 8) may be arranged. However, when the black layer 9 is adjacent to the white layer 7 at a position directly below the white layer 7, the above effect is more prominently exhibited.

<Other embodiments>
Although the printing method, printed matter, and printing system of the present invention have been described above by way of example, the above-described embodiment is merely an example, and other examples are also conceivable.

More specifically, in the above embodiment, the print layer 5 having the multilayer structure shown in FIG. 3, more specifically, the print layer 5 having the color layer 6, the white layer 7, the transparent layer 8 and the black layer 9 is formed. However, ink layers other than these layers may be newly added.

Further, in the above embodiment, in the region (unit region) where the white layer 7 exists in the print layer 5, the black layer 9 is arranged below the white layer 7. However, the present invention is not limited to this, and even in a region where the white layer 7 exists, for example, in a region where the dot density (density) in the white layer 7 is relatively low, more specifically, in the white layer 7. The black layer 9 may not be arranged in the region where the light transmittance exceeds a predetermined value (for example, 10%). That is, the black layer 9 may be arranged only in the region where the white layer 7 exists and the light transmittance in the white layer 7 is suppressed to a predetermined value or less.

Further, in the above embodiment, in the print layer 5, the black layer 9 is arranged so as to be adjacent to the white layer 7 at a position directly below the white layer 7, but the present invention is not limited to this. As described above, another ink layer, for example, a transparent layer 8 may be interposed between the white layer 7 and the black layer 9. Further, as shown in FIG. 19, the black layer 9 may be arranged at at least one of the position directly above and directly below the internal scattering member 4 (in FIG. 19, both the position directly above and directly below the internal scattering member 4). .. For example, when the black layer 9 is provided directly under the internal scattering member 4, after forming the black layer 9 on the white medium 3, the internal scattering member 4 is superposed on the position directly above the black layer 9, and the lower surface of the internal scattering member 4 is provided. It is advisable to bring it into close contact with the white medium 3 with a primer or the like applied to.

Further, in the above embodiment, the apparatus for forming the print layer 5 for producing the printed matter 1 (that is, the print layer forming apparatus 20) is a digital printing type printing apparatus such as a printer. Not limited to. The print layer forming apparatus 20 may be an analog printing type printing apparatus, for example, an offset printing machine. That is, the present invention can be applied not only to digital printing technology but also to analog printing technology.

1 Printed matter 1a Part corresponding to the transparent part 1b Part corresponding to the colored part 2 Base material 3 White medium 4 Internal scattering member 5 Printing layer 6 Color layer 7 White layer 8 Transparent layer 9 Black layer 10 Printing system 20 Printing layer forming device 21 Movement mechanism 21R Movement path 22 Discharge mechanism 22S Nozzle surface 23 Curing mechanism 24 Control mechanism 30 Thickness data acquisition device 40 Light scattering characteristic data acquisition device 50 Printing control device Ix, Iy Optical LP Rectangular wave chart LPx Rectangular pattern M layer Nc, Ng , Nh, Nk, Nm, Nw, Ny Nozzle row R Arithmetic matrix SP1, SP2, SP3, SP4, SP5 Sample pattern T Granite Tc Quartz

Claims (12)

A printing method that reproduces the texture of the surface of an object.
Based on the data on the texture, a print layer forming process for forming a multi-layered print layer on the base material was performed.
In the print layer forming process,
With a transparent transparent layer,
A white layer composed of a white fluid and arranged at a position corresponding to the data in the print layer, and a white layer.
A black layer composed of a black fluid and arranged between the white layer and the base material in a region where the white layer exists in the printed layer.
A printing method comprising forming the printing layer having the above. In the print layer forming process, a base material having a white medium having a uniform thickness and an internal scattering member superimposed on the white medium is prepared, and the printing layer is formed on the surface of the internal scattering member. Item 1. The printing method according to Item 1. The printing method according to claim 2, wherein in the print layer forming process, the print layer is formed on the surface of the internal scattering member having a uniform thickness. The printing method according to any one of claims 1 to 3, wherein in the print layer forming process, the print layer having the transparent layer having a uniform thickness is formed. The printing method according to any one of claims 1 to 4, wherein in the print layer forming process, the print layer having the white layer arranged between the transparent layer and the base material is formed. The printing method according to claim 5, wherein in the print layer forming process, the print layer having the white layer adjacent to the transparent layer is formed. The printing method according to claim 5 or 6, wherein in the print layer forming process, the print layer having the black layer adjacent to the white layer is formed. In the print layer forming process, claims 1 to 1 to form the print layer having a color layer composed of a color fluid and the white layer adjacent to the color layer between the color layer and the transparent layer. The printing method according to any one of 7. In the print layer forming process, thickness data relating to the thickness of the transparent portion exposed on the surface of the object and light scattering characteristic data relating to the light scattering characteristic of the object with respect to the incident light on the surface of the object. The printing method according to any one of claims 1 to 8, wherein the printing layer is formed in an image on the substrate according to the formation conditions set based on the above. The printing according to claim 9, wherein in the print layer forming process, the print layer having the white layer arranged in an image according to the formation conditions set for each unit region on the surface of the base material is formed. Method. It has a base material and a multi-layered printed layer formed on the base material based on data on the texture of the surface of the object.
The print layer is
With a transparent transparent layer,
A white layer composed of a white fluid and arranged at a position corresponding to the data in the print layer, and a white layer.
A printed matter which is composed of a black fluid and includes a black layer arranged between the white layer and the base material in a region where the white layer exists in the printed layer. A printing system that reproduces the texture of the surface of an object.
A print layer forming apparatus that forms a multi-layered print layer on a substrate,
It has a print control device for forming the print layer in the print layer forming device based on the data regarding the texture.
The print control device is attached to the print layer forming device.
With a transparent transparent layer,
A white layer composed of a white fluid and arranged at a position corresponding to the data in the print layer, and a white layer.
A black layer composed of a black fluid and arranged between the white layer and the base material in a region where the white layer exists in the printed layer.
A printing system characterized by forming the printing layer having the above.

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