JP2016083886A - Image formation device, image formation method, and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device and an image formation method, capable of forming an image having a wanted texture by changing a UV curing process according to a shape, especially tilting, of a printed surface.SOLUTION: An image formation device includes a print head 209 for discharging ink to a printed surface of a printed medium, light radiating means which radiates light to an ink that has hit the printed surface from the print head 209 for curing on the printed surface, acquiring means 208a which acquires information about tilting of the printed surface relative to discharging direction of the ink, and control means 208 which variably controls light radiation of the light radiating means based on the acquired information about tilting.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming apparatus and an image forming method, and more particularly to an image forming apparatus and an image forming method for forming an image on a printing medium having a planar shape and a printing medium having a three-dimensional shape.

  In general, when an image is printed / recorded on a print medium (for example, printing paper) by a printer, image signal values (for example, red (R), green (G), blue (B), Cyan (C), magenta (M), yellow (Y), black (K), etc.) are input from an external device (for example, an imaging device such as a camera or a personal computer) to the printer. The printer applies a color matching process or the like to the input image signal value, for example, so that the color material signal value corresponding to the amount of application of each color material (for example, ink) mounted on the printer to the print medium. Then, an image is formed on the print medium using a color material corresponding to the color material signal value.

In order to form an image on a printing medium, for example, a coloring material is attached to printing paper as a printing medium, for example, in units of dots, and the attached ink penetrates or is absorbed in the printing medium, or is covered. By sufficiently drying the surface of the printing medium and the ink, the ink is fixed to the printing medium.
Recently, a UV curable printer using a UV curable ink that is cured by ultraviolet rays (UV) has been proposed. When printing with this UV curable printer, the UV curable ink is adhered to the print medium in dot units, and then the UV curable ink on the print medium is irradiated with ultraviolet light (UV light), thereby producing an ink component. When the UV curable resin therein is cured, the UV curable ink is fixed on the print medium. When this UV curable ink is used, it is possible to form irregularities on the medium to be printed. For example, in a UV curable printer using this UV curable ink, the UV curable ink is thickly applied by repeating discharge and curing on the print medium, and is, for example, about several mm to several cm from the flat print medium. By forming the swell, it is possible to express surface irregularities enough to be understood by hand or visually.

In addition, unlike water-based dyes and pigments, the UV curable ink does not contain much water, and therefore does not require special paper that has been subjected to hydrophilic processing as a printing medium. For this reason, it is also possible to print on a printing medium (for example, plastic or metal) of various materials and shapes other than paper by using UV curable ink.
An example of a UV curable printer is described in Patent Document 1. In Patent Document 1, a printing medium is placed on a table, and when performing printing, the relative movement speed of the print head with respect to the table is adjusted. By adjusting the relative movement speed of the print head with respect to the table, the curing timing (irradiation timing) of the UV curable ink that has landed on the print medium is controlled to obtain the desired leveling (smoothing) of the ink. . The relative movement speed of the print head is adjusted (controlled) according to the type and temperature of ink used. Since ink is a liquid, when it reaches the print medium, it spreads over the print medium as time passes. In Patent Document 1, the spread of ink is adjusted and the surface is smoothed by delaying the timing of UV curing.

JP 2006-110443 A

  By the way, in general, prior to the image forming process, a difference in output image color is not caused by a difference between output devices to which an image is to be output (display and printer, etc.), a device type or individual difference. Color matching is performed to adjust color reproducibility. In this color matching, a color patch in which signal values are discretely printed on a flat printing medium is generally measured, and color development when an image is actually printed is predicted using a technique such as interpolation. Yes. That is, the prediction of color development under the condition (premise) that the printing surface of the printing medium for printing the color patch is flat and the printing surface of the printing medium for actually printing the image is also flat. I am doing.

  However, in printing using UV curable ink, it is possible to express irregularities on the printing medium as described above, so that the printing surface of the printing medium that actually prints the image is flat. Is not limited. In other words, in a UV curable printer, an uneven shape is formed on the print medium by repeating the process of ejecting ink onto the print medium and UV curing, so the printing surface changes during the formation of the uneven shape. In some cases, the surface is not flat, that is, the printing surface can be inclined.

Further, as described above, since the printing medium of the UV curable printer is not limited to paper, printing may be performed on a printing medium that is not flat from the beginning, such as plastic or metal having a curved surface.
Here, since the ink such as UV curable ink is a liquid, the behavior is different when the surface to be printed is flat (when it is not inclined) and when it is inclined. FIG. 15A shows the cross-sectional shape of the ink (ink dot) 17a that has landed on the printing surface 16a when the printing surface 16a of the printing medium 16 is flat, and FIG. The cross-sectional shape of the landing ink 17b when the printing surface 16b is inclined is shown. FIG. 15B is a plan view (top view) of FIG. 15A, and FIG. 15D is a plan view (top view) of FIG. 15C.

  As shown in FIG. 15C, when the printing surface 16b is an inclined surface, the ink 17b that is a liquid slides on the inclined surface (the printing surface 16b) after landing on the printing surface 16b. (Slide in the lower right direction in FIG. 15C). As can be seen from a comparison between FIG. 15B and FIG. 15D, the ink 17b that has landed on the inclined surface has an increased adhesion area on the print surface 16b. That is, the coverage of the printed surfaces 16a and 16b by the landed ink (dots) 17a and 17b is different between FIG. 15B and FIG. 15D (FIG. 15A and FIG. 15C). For this reason, if the UV curable inks 17a and 17b are cured by irradiating UV light at the same timing in the state of FIG. 15A and FIG. 15C, the shape of the UV curable ink and the coating of the printed surface The rate is also different between FIG. 15 (a) and FIG. 15 (c). Accordingly, the color, gloss, and shape of the dot 17b in FIG. 15C are different from the dot 17a in the case of FIG.

On the other hand, as described above, in image quality adjustment such as color matching, it is premised that the printing surface is flat. In other words, the color patch printed on the flat print surface is measured, and the color development when the image is actually printed is predicted based on the result of the side color. When printing on the printing surface), even if the same color matching is performed, a correct color matching result cannot be obtained.
As described above, conventionally, when the printing surface of the printing medium is uneven, such as an uneven shape, an image of a desired color development, glossiness, surface shape, etc., that is, an image having a desired texture can be formed. There wasn't.

Here, in the above-mentioned patent document 1, only the case where the printing surface of the printing medium is a flat surface is assumed, and it is not disclosed that the uneven shape is formed by thick coating.
The present invention has been made in view of the above problems, and one object of the present invention is to form an image having a desired texture even when forming an image on an uneven printing surface having an uneven shape. An image forming apparatus, an image forming method, and a computer program are provided.

  According to one aspect of the present invention, a print head that ejects ink onto a print surface of a print medium, and light that irradiates the ink that has landed on the print surface from the print head on the print surface. Light irradiation means for curing, acquisition means for acquiring inclination information of the printing surface with respect to the ink ejection direction, and variably controlling light irradiation of the light irradiation means based on the acquired inclination information And an image forming apparatus.

  According to the present invention, an image having a desired texture can be formed by variably controlling the light irradiation of the light irradiation unit based on the inclination of the printing surface, and the printing surface has various shapes. High-accuracy image quality control is also realized in image formation on a printing medium.

1 is a block diagram illustrating a configuration of an image forming system including an image forming apparatus according to a first embodiment of the present invention. It is a figure which shows an example of the relationship between UV irradiation time and glossiness in 1st embodiment. It is a figure which shows an example of the relationship between the inclination of the to-be-printed surface and ink landing in 1st embodiment. It is a figure which shows an example of the dot diameter of the discharged ink in 1st embodiment. It is a figure which shows an example of the relationship of the inclination of the to-be-printed surface, UV irradiation time, and an ink dot diameter in 1st embodiment. 2A and 2B are diagrams illustrating an example of a configuration of a print head according to the first embodiment, in which FIG. 1A illustrates an outline of an arrangement of nozzle groups and LED arrays, and FIG. 2B illustrates a division of the nozzle group of FIG. It shows how it was done. It is a figure which shows the relationship between the nozzle group of the print head of FIG. 6, and the irradiation time of an LED array. It is a figure which shows the example of the other structure of the print head in 1st embodiment. It is a flowchart of the image formation process of 1st embodiment. 2 is a hardware block diagram of the image forming apparatus according to the first embodiment. FIG. It is a block diagram which shows the structure of the image forming system containing the image forming apparatus in 2nd embodiment of this invention. It is a figure explaining an example of an STL binary format. It is a flowchart of the image formation process of 2nd embodiment of this invention. It is a figure which shows an example of the structure for acquiring the information of the solid shape of a to-be-printed medium. It is a figure which shows an example of the difference in behavior of UV hardening ink by the inclination of a to-be-printed surface, (a) shows the case where a to-be-printed surface is flat, (b) is a top view of (a), (c ) Shows a case where the printing surface is inclined, and (d) is a plan view of (c).

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the different drawings, the same components will be described with the same reference numerals.
The embodiment described below is an example as means for realizing the present invention, and should be appropriately modified or changed according to the configuration and various conditions of the apparatus to which the present invention is applied. It is not limited to the embodiment.

(Embodiment 1)
In the first embodiment, a process for forming a printed matter having an uneven shape by thickly applying UV curable ink to an initially flat print medium will be described as an example. However, the print medium on which an image can be formed by the image forming apparatus according to the first embodiment is not limited to this, and the same applies to a print medium having a non-flat print surface such as an uneven shape from the beginning. Can do.
The image forming apparatus according to the first embodiment can form an image that reproduces the texture of an object having a concavo-convex shape on the surface (reproduction target) such as an oil painting. Information on the texture of the object to be reproduced is input to the image input apparatus, and the image input apparatus generates image formation information necessary for image formation in the image forming apparatus and outputs the information to the image forming apparatus.
Here, the texture of the object to be reproduced includes at least one or more of the uneven shape, color development (discolored color), and gloss of the object to be reproduced. For example, the concavo-convex shape in the reproduced image is the same as the concavo-convex shape of the object to be reproduced, or at least approximated (or pseudo-shaped).

  Information on the uneven shape of the object to be reproduced can be acquired by an image input device such as a stereo camera, a scanner, or a three-dimensional shape measuring instrument that can measure the three-dimensional shape. Information on the color of the object to be reproduced can be acquired by an image input device such as a multi-lighting device capable of measuring a variable color and a camera such as a hyperspectral camera. Similarly, information on the gloss of the object to be reproduced is input to an image such as a multi-lighting device capable of measuring glossiness, a camera, a BRDF (Bidirectional Reflectance Distribution Function), and a BTF (Bidirectional Texture Function) estimation engine that is a planar distribution thereof. It can be acquired by the device.

  The uneven shape formed on the print surface by the image forming apparatus may be formed from a plurality of ink layers, for example, three ink layers (in order from the print surface, the lowermost layer, the intermediate layer, and the outermost layer may be formed). (Hereinafter, these three layers may be collectively referred to simply as “layers.”) The plurality of ink layers are formed by ejecting ink onto the printing surface and irradiating the ink landed on the printing surface with light. By repeatedly curing the ink, it can be formed to a desired thickness.Thickness coating with these multiple ink layers (formation of irregular shapes), the texture of the reproduction object such as irregular shapes, color development, gloss, etc. Can be reproduced.

  Note that each of the plurality of ink layers stacked on the print surface does not necessarily include the same components and the same color material as the other ink layers. For example, as long as the lowermost layer forms a substantially uneven shape, it may be formed of clear ink or the like that does not substantially contain a color material. Further, if the outermost layer generally defines gloss, it may be formed of clear ink or the like that substantially does not contain a color material.

(Configuration of Image Forming System in Embodiment 1)
FIG. 1 is a block diagram illustrating an example of a configuration of an image forming system according to the present embodiment, and illustrates a configuration in which an image forming apparatus 22 is connected to a host apparatus 21. The image forming apparatus 22 may be, for example, a UV curable printer. Hereinafter, the image forming apparatus will be described as a UV curable printer as a representative, but the image forming apparatus in Embodiment 1 is not limited to this. The host device 21 may be a personal computer 21, for example.

  The host device 21 acquires input image information 20 of an input image from various external image input devices. This input image information 20 includes texture information including unevenness shape (e.g., height for each pixel) color of the input image and gloss information. That is, the texture information includes information such as what kind of layer stacks form the unevenness, what color each layer is, and how much the surface is glossy. The color information input from the host apparatus 21 to the image forming apparatus 22 may be, for example, RGB image data. This RGB image data is converted into C (cyan), M (magenta), and Y (yellow) by the UV curable printer 22. ) And K (black) data, and a CMYK ink can be used to form an image of a laminated structure having, for example, a concavo-convex shape. The color material that can be used for the UV curable printer 22 is not limited to this, and may be, for example, R (red), G (green), or B (blue), or other color materials may be used.

  The host device 21 includes an application unit 201 and a color matching unit 202. The application unit 201 of the host device 21 processes input image information 20 to generate RGB image data, height data (unevenness data) H, and gloss data G. The application unit 201 outputs the generated RGB image data to the color matching unit 202 and outputs the generated height data H and gloss data G to the UV curable printer 22.

The color matching unit 202 executes color matching processing described later to convert input RGB image data into RGB image data that has been color-adjusted for the UV curable printer 22, and the converted RGB image data is converted to UV. Output to the curable printer 22.
The UV curable printer 22 includes a color separation unit 203, a halftoning 204, an overlap number determination unit 205, a temporary irradiation time setting unit 206, a pass separation processing unit 207, a UV irradiation process setting unit 208, and a print head (recording head) 209. Prepare.

The color separation unit 203 of the UV curable printer 22 calculates color separation data for UV curable inks such as CMYK from the RGB image data converted by the color matching process input from the color matching unit 202 of the host device 21. Then, the calculated color separation data (CMYK data) is output to the halftoning unit 204.
The halftoning unit 204 quantizes the color separation data (CMYK data) input from the color separation unit 203, converts the data into quantization data (CMYK data), and passes the converted quantization data (quantized CMYK data). The data is output to the decomposition processing unit 207.

The overlap number determination unit 205 determines the number of dot overlaps necessary to reproduce the height H from the unevenness height data H input from the application unit 201 of the host device 21, and sends it to the path resolution processing unit 207. Outputs the determined number of overlaps.
The temporary irradiation time setting unit 206 temporarily sets the irradiation time T from the gloss data G input from the application unit 201 of the host device 21 and outputs the temporarily set irradiation time T to the UV irradiation process setting unit 208.

The pass decomposition processing unit 207 executes a pass decomposition process from the quantized data (quantized CMYK data) input from the halftoning unit 204 and the number of overlaps input from the overlap number determination unit, and a UV irradiation process setting unit 208. Output hepas decomposition data.
The UV irradiation process setting unit 208 sets UV irradiation process data from the pass decomposition data input from the pass decomposition processing unit 207 and supplies the UV irradiation process data to the print head 209 using the set UV process data. Controls UV irradiation to image forming data (CMYK data).
With the above-described configuration, the UV curable printer 22 processes the input data to determine the thick coating process of the UV curable ink, and prints the uneven shape on the print medium. As described above, the uneven shape to be printed is the same as the uneven shape of the object to be reproduced, or at least an approximate shape (or a pseudo shape).

(Processing of each component in the host device 21)
Programs that operate in the operating system (OS) of the host device 21 include various application programs, a color matching (color conversion) program, and the like. In the first embodiment, the color matching is a color reproducibility for preventing the color of the image displayed on the display of the host device 21 from being different from the color printed by the UV curable printer 22. It is an adjustment process.

  The application unit 201 generates image data to be printed by the UV curable printer 22. Specifically, the application unit 201 acquires input image information 20 of an input image or image data to be printed via various image input devices, and executes editing, processing, and the like on these image data. . By processing such as editing and processing, for example, RGB image data (RGB color data) of sRGB (standard RGB) standard, height data H of unevenness to be formed by the UV curable printer 22, and gloss data G are included. Generate output data. Here, sRGB is an international standard for a color space defined by the International Electrotechnical Commission (IEC). The height data H is height data that can be reproduced by thick coating of UV curable ink. The gloss data G is data controlled by the UV irradiation time (details will be described later).

  When an external printing instruction, for example, an instruction from a user of the host device 21 is input to the host device 21, the application unit 201 sends RGB image data to the color matching unit 202. In addition, the application unit 201 sends unevenness height data H and gloss data G to the overlap number determination unit 205 and the irradiation time provisional setting unit 206 of the UV curable printer 22, respectively. Note that the timing at which the application unit 201 outputs data to the subsequent component is not limited to this, and the subsequent component at an appropriate timing based on a request for an application, a data volume, or the like without waiting for an external instruction. You may send data to

  The color matching unit 202 according to the first embodiment converts a color gamut reproduced by, for example, RGB image data (R, G, B image data) of the sRGB standard into a color gamut reproducible by the UV curable printer 22 ( Mapping). Specifically, the color matching unit 202 can use, for example, a three-dimensional LUT (lookup table) in this color matching. In the process using the three-dimensional LUT, the color matching unit 202 can execute an interpolation operation or the like as necessary. By these processes, for example, 8-bit image data R, G, B is converted into image data R, G, B within the color gamut of the UV curable printer 22, for example, 8 bits for the UV curable printer 22. RGB image data is generated. A three-dimensional LUT (3D-LUT) can be considered as a three-dimensional LUT in which RGB is expressed by three axes (R axis, G axis, B axis). Therefore, it is possible to express the intermediate tone color and the accuracy of gray scale is high. The color matching unit 202 appropriately maps the RGB image data into, for example, the XYZ color space or the L * a * b color space in the color gamut range of the UV curable printer 22.

  In the process using the three-dimensional LUT in the present embodiment, for example, an ICC (International Color Consortium) profile that is a standard characterizing a device or a color space can be used. When using this ICC profile, it is possible to use a well-known device link profile. In this case, it is possible to perform color separation processing and color matching described later (the subsequent color separation processing is unnecessary).

(Processing of each component in the UV curable printer 22)
The RGB image data generated by the color matching unit 202 of the host device 21 is input to the color separation unit 203 of the UV curable printer 22. In the first embodiment, a mechanism and a function for executing the processes of the color separation unit 203, the halftoning unit 204, the overlap number determination unit 205, the irradiation time temporary setting unit 206, the pass separation processing unit 207, and the UV irradiation process setting unit 208. However, Embodiment 1 is not limited to this, and for example, all or a part of them may be realized by a device external to the UV curable printer 22.

  The color separation unit 203 reproduces colors represented by these data from RGB image data mapped to a color gamut reproducible by the UV curable printer 22 input from the color matching unit 202 of the host device 21. Processing for obtaining color separation data of, for example, CMYK UV curable ink corresponding to the ink combination of the curable printer 22 is performed. In the first embodiment, this color separation process can be executed using, for example, a three-dimensional LUT, as in the color matching process, and an interpolation operation and a calibration process can be used together. Note that the color material that can be used in the UV curable printer 22 is not limited to CMYK. Instead, for example, a light-color ink having a relatively low density may be used, and an ink such as RGB is used. May be. In this case, the association by the three-dimensional LUT may be changed according to the ink attached to the UV curable printer 22.

The color separation unit 203 sends, for example, 8-bit CMYK color separation data to the halftoning unit 204.
The halftoning unit 204 performs quantization that converts the CMYK color separation data input from the color separation unit 203 into, for example, 3-bit data for each of C, M, Y, and K. Specifically, in this quantization, for example, 8-bit data can be converted into 3-bit data by using a known technique such as an error diffusion method or a threshold mask having frequency characteristics such as blue noise / green noise. it can.

  Here, the bit number of bit data is data depending on the drop size of ink dots that can be ejected by the print head (recording head) 209. For example, in the case of 3 bits, drop size control of about 8 gradations is possible. The size of the ink drop ejected from the print head 209 is determined by the halftoning unit 204. Inkjet printers express multi-level continuous gradation of images depending on whether or not ink dots are ejected onto the printing medium. (Halftone) processing is required. For example, the halftoning unit 204 performs a process of quantizing 8-bit CMYK data into 3-bit CMYK data.

  The overlap number determination unit 205 obtains, for example, 8-bit unevenness height data H input from the application unit 201, and determines the dot overlap number Kn necessary to reproduce the height. The number of times of overlapping Kn can be calculated, for example, by dividing the finally required height (height from the uneven printed surface) by the height of one dot of ink from the printed surface.

  In the first embodiment, it is possible to use a print head 209 that can change the ink drop size (ink drop diameter) as will be described later (for example, between 40 μm and 90 μm in FIG. 5 described later). In this case, the overlap number Kn may be calculated by using the height of the dot of the minimum size, and the subsequent pass separation processing unit 207 may determine the overlap number Kn according to the dot size. Instead, in the first embodiment, a print head having a fixed ink drop size may be used. In that case, for example, a process of quantizing 8-bit CMYK data into 3-bit CMYK data is performed.

The temporary irradiation time setting unit 206 acquires, for example, 8-bit gloss data G input from the application unit 201, and the time from the landing of UV ink on the printing surface necessary for reproducing the gloss to the UV irradiation. (Irradiation timing) T is temporarily set.
FIG. 2 shows the relationship between the time from ink landing to UV irradiation, which can be referred to by the temporary irradiation time setting unit 206, and the mirror glossiness of the printed image surface. The vertical axis of the graph in FIG. 2 indicates the specular gloss, and the horizontal axis indicates the time from ink landing to UV irradiation. As shown in FIG. 2, when the time from the landing of the UV ink on the printing surface to the UV irradiation is increased, the specular gloss of the printed image surface becomes higher. In FIG. 2, time t ₀ is the minimum time required from landing to UV irradiation depending on the structure of the print head 209, and time t _n is a standard irradiation time in the printing control of this embodiment. .

The temporary irradiation time setting unit 206 preferably uses the relationship shown in FIG. 2 to temporarily calculate the irradiation timing T of the outermost (top) layer that contributes most to the specular glossiness of the printed image based on the gloss data G. Just decide. For the UV ink that forms a layer below this outermost layer, for example, all may be irradiated with UV at a uniform time t _n . If the irradiation time temporary setting unit 206 is configured in this way, the control of the UV irradiation time is facilitated.

The irradiation timing T temporarily set in the irradiation time temporary setting unit 206 is output to the UV irradiation process setting unit 208, and finally used when obtaining the optimal irradiation timing t in consideration of the inclination of the printing surface. The irradiation timing is set so that a desired gloss can be reproduced, and depends on the ink dot diameter. The graph of FIG. 2 is prepared in advance by, for example, a prior experiment and is held in the irradiation time temporary setting unit 206.
The time t _n from the ink landing to the UV irradiation is an irradiation time that is also used when printing a color patch (for example, CMYK for confirmation) on a flat planar printing medium in the color matching process described above. It's okay.

  A multi-pass printing technique can be used for printing on a printing medium in the first embodiment. In this multi-pass printing, a plurality of recording (printing) scans are performed in the same area of the printing surface. By multi-pass printing, it is possible to reduce the influence of variations in manufacturing of ink nozzles alone, non-ejection of ink droplets in the middle of printing, and fluctuations in ejection amount, thereby reducing the occurrence of density unevenness. In multi-pass printing, among a plurality of recording scans that form one line of an image, the first recording scan is referred to as one pass, and the second recording scan is referred to as two passes (the same designation is used for the third and subsequent times). .) Although the nozzle group 209a (FIG. 8) that discharges the UV curable ink will be described later, in the first embodiment, the nozzle group 209a may be divided into a plurality of, for example, four pass regions. In the first embodiment, a printing method that does not perform multi-pass decomposition may be used.

  The pass separation processing unit 207 acquires, for example, 3-bit CMYK data input from the halftoning unit 204 and also acquires the number of overlaps Kn input from the overlap number determination unit 205, and finally performs multipass printing. Perform a simple path decomposition. In this case, the pass decomposition is to reproduce the minimum number of overlaps Kn of 1 dot for each pixel. Therefore, if the height corresponding to the CMYK drop size of each pixel is added and the Mn layer is overlapped, the minimum This is a process for calculating whether or not the height H equivalent to the case where the dots are overlapped Kn times is reproducible. Since the print head 209 can form CMYK dots with a single operation, if an Mn (x) layer is required for the CMYK layer of the pixel x, an image is formed with the Mn operation. The pass decomposition processing unit 207 calculates Mn for all the pixels of the image to be formed, and the maximum number of Mn is finally the required number of scans. For example, if Mn is 3, 4 passes × 3 = 12 passes, and finally the required number of scans is 12. That is, the 12-pass decomposed image (path decomposed data) is generated by the path decomposition processing unit 207. The pass separation processing unit 207 sets which ink is used in which pass.

  In this pass decomposition, it is not necessary to form an image with CMYK ink for all ink layers. Preferably, for a layer below the outermost layer that does not contribute to color development, a transparent UV curable ink (clear ink) may be used instead of the CMYK ink. In this case, the dot height of the UV curable ink is calculated in advance, and the clear ink may be stacked from the height H to the height of one layer of CMYK on the outermost layer. Preferably, a white layer is formed between the clear ink and the CMYK ink. This white layer can improve the color of the CMYK ink.

The UV irradiation process setting unit 208 acquires the CMYK image data and the pass decomposition data Mn input from the path decomposition processing unit 207 and the temporary irradiation time T input from the irradiation time temporary setting unit 206. The UV irradiation process setting unit 208 sets the time from ink landing to UV irradiation for all the pixels of the pass decomposition data obtained by the pass decomposition control unit 207 (that is, the pass decomposition data for each scan of the print head 209). To do.
The inclination calculation unit 208a of the UV irradiation process setting unit 208 acquires the amount of inclination with respect to the ink ejection direction of the printing surface from the temporarily set UV irradiation time T input from the irradiation time temporary setting unit 206, and this inclination. The corrected UV irradiation time t is set in consideration of the amount of.

Hereinafter, a method for obtaining the UV irradiation time t in consideration of the amount of inclination of the printing surface in the first embodiment will be described.
FIG. 3 is a diagram for explaining the outline of processing by the UV irradiation process setting unit 208. With reference to FIG. 3, the print medium 16 is placed on the medium support portion 26, and two ink deposition layers (laminations) 27 and 28 having a triangular cross section are formed on the print medium 16. Yes. In this state, two ink drops (ink droplets) Drop1 and Drop2 ejected at an arbitrary number of scans Z (Z < Mn) of the print head 209 are ink deposition layers formed in the scans up to the Z-1th time. (Lamination) 27 and 28 are shown landing on the printing surfaces 27a and 28a, respectively. For example, the ink drop for forming the outermost layer on the intermediate layer may be Drop1 and Drop2. In FIG. 3, the ink drop Drop1 lands on the printing surface 27a having the inclination θ1, while the ink drop Drop2 lands on the printing surface 28a having the inclination θ2. Here, θ1 is an angle smaller than θ2.

  FIG. 4 is a diagram illustrating dot diameters with and without an inclination. FIG. 4 shows a case where the ink drop Drop3 has landed on the surface 16a of the printing medium 16 which is a flat printing surface without an inclination. Assuming that the diameter of the ink drop Drop3 is D1, with reference to FIG. 4, it is assumed that the dot diameter D2 formed by the ink drop Drop3 landing on the print medium 16 is the same as the diameter D1 of the ink drop Drop3 (assuming that To do). On the other hand, the ink drop Drop2 shows a case where the ink drop has landed on the inclined printing surface 28a. It is assumed that the diameter of the ink drop Drop2 is the same value D1 as the diameter of the ink drop Drop3. A dot diameter formed by landing on the printing surface 28a where the ink drop Drop2 is inclined is indicated by D3. In the first embodiment, as shown in FIG. 4, the dot diameter of the ink drop Drop2 is obtained by projecting the ink dot diameter on the inclined printing surface 28a onto the non-inclined surface (the surface 16a of the printing medium 16). The dot diameter is D3. That is, when Drop3 and Drop2 shown in FIG. 4 have the same drop size (diameter of one ink drop) D1, the dot diameter D2 of the ink drop Drop3 and the dot diameter D3 of the ink drop Drop2 are treated as the same.

Referring to FIG. 15, if the print surface is inclined, the ink is inclined downwardly as shown in FIG. 15C as time elapses from the landing of the ink print surface. That is, the dot diameter on the inclined surface becomes large. On the other hand, by controlling the time from ink landing to UV irradiation, the ink can be cured with the same dot diameter without being affected by the inclination of the printing surface. That is, the same dot diameter can be obtained regardless of the inclination of the printing surface.
In the graph of FIG. 5, the vertical axis indicates the time (t) from ink landing to UV irradiation, and the horizontal axis indicates the amount of inclination (θ) of the printing surface. In FIG. 5, the ink drop diameter (dot diameter) can be selected from 40 μm to 90 μm, for example, and an equivalent dot curve for a representative dot diameter in units of 10 μm is shown as an example.

  As shown in FIG. 5, it can be seen that the same dot diameter can be obtained if the time t until UV irradiation is shortened as the inclination θ of the printing surface increases. According to this relationship, if the ink is irradiated with UV after being landed on the inclined surface and then slid on the inclined surface, the dot diameter can be prevented from unintentionally increasing (the state shown in FIG. 15C). For example, assuming that an equal dot diameter curve of 40 μm in FIG. 5 is used, the UV irradiation timing of the ink drop Drop1 in FIG. 3 is determined based on θ1, and the UV irradiation timing of the ink drop Drop2 is determined based on θ2. The dot diameter (dot size) after UV curing (after fixing) of the ink drops Drop1 and Drop2 can be made the same (40 μm) as desired. For this reason, even when printing is performed on the inclined print surfaces 27a and 28a as shown in FIG. 3, if the control is performed on the equal dot diameter curve shown in FIG. It can be handled in the same way as patch printing on the print medium. That is, an image having a desired texture can be formed even on a printing surface with an inclination compared with a flat printing surface without an inclination.

  With reference to FIG. 3, how to obtain the inclination (inclination angle) θ of the printing surface will be described. In FIG. 3, the ink drop Drop1 is landed on the print surface (inclined surface) 27a having an inclination θ1, and the print surface 27a is laminated on the predetermined area 24 of the print medium 16 before the ink drop Drop1 is landed. Already formed by the ink drop (ink dot). For example, it is assumed that an inclined surface having an inclination θ1 is formed as a result of, for example, two drops of ink being stacked vertically on the region 24 before the ink drop Drop1 reaches the printing surface. On the other hand, the inclined surface on the left side of the region 24 in FIG. 3 is formed by, for example, one drop of ink drop, and the inclined surface on the right side of the region 24 is formed by, for example, three drops of ink drop. In this way, the ink drops having different numbers of drops onto the surface area of the continuous print-receiving surface are cured, whereby an inclined surface having an inclination θ is formed. Here, the data indicating how many ink drops have already been dropped is known in the UV curable printer 22. Accordingly, the inclination θ1 of the area 24 is determined by, for example, calculating the unevenness information (the height from the printing surface) of each area using the ink dot diameter from each of the area 24 and the cumulative number of drops (cumulative ejection number) of the left and right ink drops. Information) and differentiating them can be obtained. The inclination θ of the printing surface is calculated by an inclination calculation unit 208 a provided in the UV irradiation process unit 208. Alternatively, the inclination calculation unit 208 a may be provided outside the UV irradiation process setting unit 208 in the UV curable printer 22. The slope θ2 of the landing point of the ink drop Drop2 can be obtained by performing the same calculation.

If the inclination θ of the printing surface is obtained by the inclination calculating unit 208a, the UV irradiation process setting unit 208 determines the final UV irradiation time (irradiation timing) t using the relationship of FIG. Specifically, the UV irradiation process setting unit 208 determines the dot diameter based on the UV irradiation time T temporarily set by the irradiation time temporary setting unit 206 with reference to FIG. This is because the desired gloss depends on the dot diameter. That is, it is possible to determine which one of the plurality of equal dot diameter curves in FIG. 5 is to be used based on the UV irradiation time T determined based on the gloss data G. If the equal dot diameter curve to be used is determined, the final UV irradiation time t can be determined from the equal dot diameter curve shown in FIG. 5 based on the inclination θ of the printing surface. In addition, the value of the equal dot diameter curve when the inclination θ of the printing surface is zero may be, for example, the UV irradiation time t _n as the standard irradiation time. The UV irradiation process setting unit 208 generates data (including irradiation time t) necessary for the UV irradiation process, for example, data including UV irradiation intensity, which UV light emitting element is used, and the like, and supplies the generated data to the print head 209. At the same time, the operation of the print head 209 is controlled.
Alternatively, the UV irradiation process setting unit 208 may obtain the UV irradiation time t using a predetermined equal dot diameter curve.

(Configuration of print head)
An example of the print head 209 in this embodiment is shown in FIG. As shown in FIG. 6A, the print head 209 includes an ink nozzle group (a plurality of ink nozzles) 209a that discharges UV curable ink, and UV-LED arrays 209b and 209c positioned on both ends thereof. To do. The UV-LED arrays 209b and 209c are examples of an ultraviolet irradiation unit (light irradiation unit). The ink nozzle group 209a and the UV-LED arrays 209b and 209c are mounted at predetermined intervals in the lateral direction of the carriage unit 25 (carriage scanning direction, left-right direction in FIG. 6). UV curable ink corresponding to the pass separation CMYK data set by the pass separation processing unit 207 is ejected from the ink nozzle group 209a to the printing surface. Further, according to the time t from ink landing to UV irradiation set by the UV irradiation process setting unit 208, adjustment of the scanning speed of the carriage unit 25 and the UV light emitting elements to be emitted in the UV-LED arrays 209b and 209c. At least one or both of the selections may be performed.

  FIG. 6 shows an example in which the ink nozzle group 209a has five nozzle rows N1 to N5. However, the number of ink nozzle rows in the first embodiment is not limited to this, and can be arbitrarily set. It may be. The nozzle rows N1 to N5 are arranged in the longitudinal direction of the carriage unit 25 (the direction orthogonal to the scanning direction). For example, the nozzle array N1 ejects cyan (C) ink, the nozzle array N2 ejects magenta (M) ink, the nozzle array N3 ejects yellow (Y) ink, and the nozzle arrays N4 and N5 are black (K ) Ink may be ejected.

In FIG. 6B, the nozzle group 209a may be divided into a 1-pass region, a 2-pass region, a 3-pass region, and a 4-pass region. For example, the unused nozzle area may be above the 4-pass area. In FIG. 6, each of the UV-LED arrays 209 b and 209 c is an array of 8 columns × 7 columns, and 56 ultraviolet light-emitting elements (hereinafter also referred to as “LED elements”) such as UV-LED elements. However, the number of ultraviolet light emitting elements on the array of the embodiment is not limited to this, and may be arbitrarily set. In FIG. 6, for example, in the UV-LED array 209c, the leftmost column is LED element column C1, and the right seven columns are sequentially LED element columns C2 to C8. The UV-LED arrays 209b and 209c correspond to light irradiating means for irradiating light onto the ink landed on the printing surface and curing the ink on the printing surface.
If both of the UV-LED arrays 209b and 209c are provided, it is possible to cope with the case where the carriage scanning direction is bidirectional. However, when the carriage scanning direction is one direction, instead of this, UV- Any one of the LED arrays 209b and 209c may be provided.

  7 shows the light emitting elements in the UV-LED array 209c and the UV irradiation time (ink ejection) when the carriage unit 25 in FIG. 6 moves at a constant speed in the scanning direction (the direction indicated by the white arrow in FIG. 7). It is a figure which shows an example with respect to time from UV to irradiation. In FIG. 7, it is assumed that the medium support portion (reference numeral 26 in FIG. 3) does not move in the scanning direction of the carriage portion 25.

As shown in FIG. 7, when the carriage unit 25 moves in the scanning direction, for example, the time until the ink ejected from the nozzle array N1 is irradiated by the LED element array C1 (the time from ink ejection to UV irradiation) is It is assumed that the time is 100 msec, the time until irradiation with the LED element array C3 is 120 msec, and the time until irradiation with the LED element array C4 is 140 msec. Similarly, the time until the ink ejected from the nozzle array N2 is irradiated by the LED element array C2 is 100 msec. In this way, it is possible to adjust the timing of UV irradiation (ink curing timing) from the distance relationship between the nozzle that ejects ink and the LED element that emits light. The irradiation time when irradiation is performed by the LED element array C1 closest to the nozzle array N1 is 100 msec. However, if the irradiation time is desired to be less than 100 msec, the moving speed in the scanning direction of the carriage unit 25 may be increased. Therefore, the timing of UV irradiation can be adjusted by a combination of which LED element array is used and the moving speed of the carriage unit 25. Since the time until irradiation is set shorter as the inclination of the printing surface is larger, an LED element close to the nozzle array may be selected (for example, C1 is selected instead of the LED element array C2).
The print head 209 receives CMYK image data for image formation, UV irradiation timing t, pass decomposition data, and the like (parameter data UVp necessary for the UV irradiation process) from the UV irradiation process setting unit 208.

FIG. 8 shows another example 309 of the print head according to the first embodiment. 7 and 8, the same reference numerals are assigned to the same components. As shown in FIG. 8, in the print head 309, ink nozzle groups 309a (nozzle rows N1 to N5) for discharging UV curable ink and UV-LED arrays 309b, 309c, and 309d are alternately arranged.
In FIG. 8, the UV-LED array 309 b is provided in the vicinity of the left end of the print head 309 as an array of 4 vertical columns × 7 horizontal rows, and the UV-LED array 309 d is provided in the vicinity of the right end of the print head 309 It is provided in an array of 7 rows. Between the left UV-LED array 309b and the right UV-LED array 309d, nozzle rows N1 to N5 of the ink nozzle group 309a and UV-LED arrays (a plurality of LED element rows) 309c are alternately provided. Yes. The ink nozzle rows N1 to N5 are provided at a predetermined interval, and the UVLED array 309c is located within the predetermined interval. Even when this print head 309 is used, the UV curable ink is ejected from the ink nozzle group 309a onto the surface to be printed, and the LED elements to emit light are selected and selected from the UV-LED arrays 309b, 309c, and 309d. The UV curable ink is irradiated and cured by irradiation of UV light from the LED element.

  Compared with the print head 209 in FIG. 6, in the print head 309 in FIG. 8, the UV-LED array 309c is arranged between the nozzle rows N1 to N5 of the ink nozzle group 309a. The light emission coordinate control (control for determining which LED element should emit light) can be performed more precisely. For example, when the ink discharged from the nozzle array N1 in FIG. 8 is irradiated by the UV-LED array 309c immediately adjacent to the right, the irradiation time is, for example, 100 msec in the case of FIG. ) Is shorter. When the print head 309 of FIG. 8 is used, for example, the timing of UV irradiation of the ink ejected from the nozzle array N1 can be different from that of the print head 209 of FIG. This is because, for example, the distance from the nozzle row N1 to N5 to the LED element row closest to the nozzle row N1 to N5 is different between the print head 309 in FIG. 8 and the print head 209 in FIG. The print head 309 in FIG. 8 may be used for a large-sized high-performance printer, for example.

In the print head 309 shown in FIG. 8, one or both of the UV-LED arrays 309b and 309d may not be provided in the print head 309.
In the above description, the carriage unit 25 of the print heads 209 and 309 moves relative to the print medium 16, but the first embodiment is not limited to this. For example, instead of this, or in addition to this, the medium support part 26 (FIG. 3) on which the print medium 16 is placed may be moved relative to the carriage part 25. Even in this case, it is possible to adjust the timing of ink ejection and UV irradiation according to which ink nozzle (nozzle row) is used and which UV-LED array (which LED element) is used. is there.

  The ink nozzles and LED-UV light emitting elements shown in FIGS. 6, 7 and 8 are simplified for illustration, and the total number of ink nozzles and the number of columns, and the total number and columns of the LED-UV light emitting elements are illustrated. The number is not limited. Further, the arrangement of the ink nozzles and the LED-UV light emitting elements is not limited to the illustrated arrangement. Which ink nozzle row ejects what color of ink is not limited to the above-described content.

(Image Forming Process in Embodiment 1)
FIG. 9 is a flowchart showing an operation in the image forming system of FIG. Hereinafter, image forming processing executed by the image forming apparatus (UV curable printer 22) according to the first embodiment will be described with reference to the flowchart of FIG.
First, in step S <b> 1001, the UV curable printer 22 acquires image data for image formation from the application unit 201 and the color matching unit 202 of the host device 21. The image data for image formation includes, as described above, texture data such as RGB image data for color reproduction, height data H for concavo-convex shape reproduction, and gloss data G for gloss reproduction. Image data, which is generated based on the input image data 20. When the image forming data is acquired, the process proceeds to step S1002.

In step S1002, the color matching unit 202 performs color matching processing. As described above, for example, RGB image data input from the application unit 201 to the color matching unit 202 by the color matching processing performed here is in the color reproduction range of the UV curable printer 22 using, for example, a three-dimensional LUT. Is converted into a suitable RGB value. When the color matching process ends, the process proceeds to step S1003.
In step S1003, the color separation unit 203 performs color separation processing. As described above, the color separation processing performed here is CMYK data that can be output by the UV curable printer 22 using RGB image data input from the color matching unit 202 to the color separation unit 203 using a three-dimensional LUT. It is processing to convert to. When the color separation process ends, the process proceeds to step S1004.

  In step S1004, for example, 8-bit CMYK data input from the color separation unit 203 to the halftoning unit 204 is quantized by the halftoning unit 204 into, for example, 3-bit CMYK data (halftone processing). The number of bits of CMYK data to be input is quantized according to, for example, variations (types) of ink drop sizes that can be ejected by the print head 209 (309), a desired image processing resolution, and a UV curable printer. It is determined by parameters such as area gradation when 22 reproduction resolutions are different. When the halftone process ends, the process proceeds to step S1005.

  In step S <b> 1005, the overlap number determination unit 205 determines a necessary overlap number (number of overlap coating) Kn when reproducing the height by thick coating of the UV curable resin based on the height data H input from the application unit 201. To do. The number of times of overcoating performed here is determined by dividing the height data H by the size (drop size) of one dot of UV curable ink as described above. When the print head 209 can eject ink with a plurality of drop sizes, the number of times of overlap Kn is determined using the minimum drop size (minimum dot height). By using the minimum drop size, the height data H can be reproduced with higher accuracy. When the number of overcoating Kn is determined, the process proceeds to step S1006.

In step S <b> 1006, the temporary irradiation time setting unit 206 temporarily sets a time T from landing of UV ink containing UV resin to UV irradiation based on the gloss data G of the output image (printed image) input from the application unit 201. To do. As described above, the time T from the landing of the UV resin to the irradiation determined here may be applied only to the ink layer that forms the outermost surface of the image contributing to the gloss. For the layer below it, the irradiation time may be determined so as to be cured at the time t _n shown in FIG. 2 (the standard time in the printing control of the first embodiment). When the UV irradiation time T is temporarily set, the process proceeds to step S1007.
In step S1007, when using multi-pass printing, the pass separation processing unit 207 performs separation into each pass in multi-pass printing.

  When all the uneven layers are reproduced with CMYK ink, the number of scans Mn determined by the pass separation processing unit 207 indicates how many times the height H can be reproduced by repeating the lamination of CMYK. That is, Mn is the number of repetitions of CMYK printing after pass separation. For example, if the CMYK ink nozzle group 209a is divided into 1-pass to 4-pass areas and the repetition is 3 times (Mn = 3), 4 × 3. = 12, the decomposed image data for 12 paths is generated by the path decomposition processing unit 207. The lowest layer is formed by the first 1 to 4 passes, the intermediate layer is formed by the next 1 to 4 passes, and the outermost layer is formed by the last 1 to 4 passes. When the path decomposition process ends, the process proceeds to step S1008.

In step S <b> 1008, for example, data for one pass is selected from the data for twelve passes generated by the pass decomposition processing unit 207 in the stacking order. When data for one pass is selected, the process proceeds to step S1009.
In step S1009, the UV irradiation process setting unit 208 sets the UV irradiation process for the data for one pass selected in step S1008. Specifically, in the setting of the UV irradiation process performed here, as described in FIG. 3, the inclination θ of the shape formed by the preceding pass (for example, the inclination θ1 of the printing surface 27a in FIG. 3) is set. Acquired (detected or calculated) by the inclination calculation unit 208a. The shape can be calculated by integrating the height of the ink drop that is ejected for each pass data in the stacking order selected in step S1008. If the calculated shape data (integrated value of height) and the height added by the pass printing currently being processed are stored as, for example, integrated values, the shape data in the next processing can be calculated at higher speed. Is possible.

  Since the inclination calculation unit 208a is a means for obtaining information on the inclination θ, it can be referred to as an inclination information acquisition means. Further, the UV irradiation process setting unit 208 performs UV irradiation of the UV light irradiation unit (UV-LED arrays 209b, 209c, etc.) according to the inclination of the print target part (printed surface 27a, etc.) acquired by the inclination calculation unit 208a. Since the timing is controlled, it can be said that the control means variably controls the UV irradiation based on the inclination of the print portion.

If the inclination θ of the printing surface of the ink drop can be calculated, the UV irradiation timing (time to UV irradiation) t at the inclination θ can be obtained from the relationship of FIG. In step S1009, a time t from ink landing to irradiation on the printing surface is set for all dots in one pass. When the time t is set, the process proceeds to step S1010.
In step S1010, printing is performed by driving the print head 209 according to the ink for one pass set by the UV irradiation process setting unit 208 and the irradiation time t of each drop. For example, the irradiation timing can be changed (adjusted) by changing the scanning speed of the carriage unit 25. The scanning speed of the carriage unit 25 may be adjusted to increase as the inclination of the printing surface increases.

In step S1011, it is determined whether the UV irradiation process setting for all passes (step S1009) and the head drive (step S1010) have been completed. If steps S1009 and S1010 have not been completed for all paths, the process returns to step S1008. If steps S1009 and S1010 have been completed for all paths, the series of operations is terminated.
In step S1005, when the relationship between the drop size and the number of overlaps is known in advance, the drop size for determining the number of overlaps may not be the minimum drop size. For example, the calculation may be performed with the maximum drop size or a combination of various drop sizes. Further, steps S1002 to S1006 may be executed out of the order shown in FIG.

FIG. 10 is a block diagram illustrating an example of a hardware configuration of the UV curable printer 22. The UV curable printer 22 includes a CPU 31, a ROM 32, a RAM 33, an external memory 34, a printing unit 35, an input unit 36, a display unit 37, a communication I / F 38, and a system bus 19.
The CPU 31 controls the operation of the UV curable printer 22 in an integrated manner, and controls each component (32 to 38) via the system bus 19. The CPU 31 implements functions such as the color separation unit 203, the halftoning unit 204, the overlap number determination unit 205, the irradiation time temporary setting unit 206, the pass separation processing unit 207, and the UV irradiation process setting unit 208 shown in FIG.

The ROM 32 is a non-volatile memory that stores a control program necessary for the CPU 31 to execute processing. The program may be stored in the external memory 34 or a removable storage medium (not shown).
The RAM 33 functions as a main memory, work area, etc. for the CPU 31. Therefore, the CPU 31 implements various functional operations by loading a program or the like necessary from the ROM 32 to the RAM 33 when executing the processing, and executing the program or the like.

For example, the external memory 34 stores various data and various information necessary for the CPU 31 to perform processing using a program. For example, the curve data of FIGS. 2 and 5 may be stored in the external memory 34. The external memory 34 stores, for example, various data and various information obtained by the CPU 31 performing processing using a program or the like.
The printing unit 35 includes a carriage unit 25 on which the print head 209 is mounted, a medium support unit 26, a CMYK ink cartridge (not shown), a drive unit (not shown) of the carriage unit 25, and the like. The printing unit 35 performs printing under the control of the CPU 31.

The input unit 36 includes a power button, a numerical button, and the like, and a user of the UV curable printer 22 can give an instruction to the UV curable printer 22 via the input unit 36.
The display unit 37 includes, for example, a liquid crystal display and displays an image generated by the UV curable printer 22, an image input from the outside, and numerical values / instructions input from the input unit 36.
The communication I / F 38 is an interface for communicating with an external device. The communication I / F 38 is, for example, a LAN interface.
The system bus 19 connects the CPU 31, the ROM 32, the RAM 33, the external memory 34, the printing unit 35, the input unit 36, the display unit 37, and the communication I / F 38 so that they can communicate with each other.

As can be seen from the above description, according to the first embodiment, the light irradiation (for example, the light irradiation timing and the light irradiation intensity) of the light irradiation unit is variably controlled based on the inclination of the printing surface. Images having a desired texture (for example, desired color development, uneven shape, gloss, etc.) can be formed. An uneven shape having a desired color and gloss can be obtained, and an appropriate texture can be expressed.
In the description of the first embodiment, the input image 20 input to the host device 21 may be input to the host device 21 after processing such as editing.

  In the first embodiment, the UV curable ink has four colors, CMYK, but the ink to be used is not limited to this. For example, white (white) ink, red (red), green (green), blue (blue) ink, etc. may be used as appropriate, clear ink may be used, Low light ink may be used. For example, silver ink may be used when a metallic texture is desired. There is no limit to the number of colors that can be described in the three-dimensional LUT.

  In Embodiment 1, it has been described that the concavo-convex shape is composed of three layers, but the number of layers constituting the concavo-convex shape is not limited to three, and any number can be used. For example, if the number of layers is four and a clear ink (colorless) layer is formed on the outermost layer, the outermost layer effectively functions as a glossy layer, for example. In the case of a four-layer structure, preferably, the lowermost layer is formed with clear ink, the upper layer is formed with white ink (white scattering layer), and the upper layer is formed with CMYK ink. The upper layer may be formed of clear ink. Even with such a configuration, the image formation of Embodiment 1 can be applied. Needless to say, clear ink may be used even in the case of a three-layer structure.

In the first embodiment, the input image information 20 is acquired from the outside. However, a user of the host device (personal computer) 21 may prepare a three-dimensional CG image using the host device 21. In this case, the input image information 20 may be generated in the host device 21.
Furthermore, although the example using the ink which hardens | cures with an ultraviolet-ray (UV) was demonstrated above, the ink of Embodiment 1 should just have the characteristic which hardens | cures by irradiation of light, Therefore, the light irradiated is also As long as it has a wavelength or intensity capable of curing the ink, it is not limited to ultraviolet light.

  In the first embodiment, the print medium 16 (medium support unit 26) is not moved in the scanning direction of the carriage unit 25 in the description of FIG. 6, but the medium support unit 26 may be movable. In this case, the UV irradiation timing may be changed by changing the feeding speed of the medium support unit 26 or by changing both the scanning speed of the carriage unit 25 and the feeding speed of the medium support unit 26. May be. Although the print head 209 includes the LED light emitting elements 209b and 209c, the LED light emitting element may be separated from the print head 209 and speed controlled separately from the print head 209.

In the first embodiment, the host device 21 and the UV curable printer 22 are described as separate units. However, the function of the host device 21 may be built in the UV curable printer 22. That is, both the application unit 201 and the color matching unit 202 may be mounted on the UV curable printer 22.
Furthermore, in the first embodiment, the ink curing timing is controlled by changing the UV irradiation timing, but the present invention is not limited to such an embodiment. For example, the timing of UV irradiation (UV light irradiation) on the ink may be controlled by changing the intensity and frequency of UV light irradiated from the UV-LED arrays 209b and 209c.

(Embodiment 2)
In the first embodiment, all of the plurality of layers constituting the concavo-convex shape formed on the print medium 16 are printed by the UV curable printer 22, but the present invention is not limited to such an embodiment. For example, layers other than the outermost layer may be formed by an external shape forming device such as a three-dimensional printer, and coloring and gloss may be imparted to the solid surface output by the shape forming device by a UV curable printer. . This case will be described below as Embodiment 2 with reference to FIG.
FIG. 11 is a functional block diagram illustrating a configuration example of the image forming system according to the second embodiment. The same reference numerals are used for the same constituent elements as those in the first embodiment (FIG. 1).

(Configuration of Embodiment 2)
In the second embodiment, a shape forming device (for example, a three-dimensional printer; hereinafter simply referred to as “three-dimensional printer”) can be connected to the host device (personal computer) 21 and / or the UV curable printer 22. To do. This connection may be any connection that can exchange data, and may be a wired connection or a wireless connection.
Data used by the three-dimensional printer (3D data) is input from the outside to the three-dimensional printer. This 3D data may be described in, for example, an STL (StereoLithography) format. The three-dimensional printer converts the 3D data into, for example, STL format data (3D-CAD data). Alternatively, data in this STL format may be input to a three-dimensional printer. The three-dimensional printer forms a base layer on the print medium 16 based on the data in the STL format. It may be considered that the underlayer is a layer in which the lowermost layer and the intermediate layer in the first embodiment are combined. The underlayer may be formed without considering color and gloss.

  The host device 21 generates gloss data G, RGB image data, and concavo-convex data (height data) H in the same manner as in the first embodiment on the outermost layer of the printing surface of the printing medium. The gloss data G, RGB image data, and unevenness data H are input from the host device 21 to the UV curable printer 22. On the other hand, the three-dimensional printer forms a base layer on the print medium 16 based on the data in the STL format. Thereafter, the UV curable printer 22 forms an outermost layer on the underlayer based on the gloss data G, the RGB image data, and the height data H. In the following description, differences from the first embodiment will be described.

The UV curable printer 22 according to the second embodiment can acquire the inclination information 210 of the printing surface (the surface of the base layer) by the inclination information acquisition unit 208b by acquiring the STL format data for the three-dimensional printer. .
For example, FIG. 12 shows an example of STL format data generally used in a three-dimensional printer. This STL format is, for example, a binary format. The STL recognizes a three-dimensional shape as a collection of a large number of small triangles (a set of facets), and defines the three-dimensional shape by coordinates and normal vectors of each triangle (three vertices). As shown in FIG. 12, the STL format in the binary format starts with an arbitrary character string of 80 bytes (header), and the number of triangles is described by a 4-byte integer. Thereafter, information of each triangle is described in 50 bytes (the last 2 bytes are unused data). The information of each triangle is described in the order of normal vector, vertex 1 coordinate, vertex 2 coordinate, vertex 3 coordinate. By using this normal vector, the inclination of the printing surface can be found.
Note that the STL format may be the ASCII format instead of the binary format. The ASCII format is highly readable, but the amount of information is larger than the binary format).

(Image Forming Process of Embodiment 2)
FIG. 13 is a flowchart of image forming processing according to the second embodiment. The three-dimensional printer used in the second embodiment is, for example, an optical modeling printer, and can model an underlayer using UV curable ink.
The operation of the host device 21 and the UV curable printer 22 according to the second embodiment will be described below with reference to FIG. In FIG. 13, the processes described with the same step numbers as in FIG. 9 are the same processes as described in FIG. 9, and thus detailed description thereof is omitted.
First, in step S1201, the host device 21 acquires image data of the outermost layer of the reproduction target object from the outside. Alternatively, the host device 21 uses the application unit 201 to generate image data of the outermost layer of the reproduction object. This image data is data including RGB image data for color reproduction and gloss data G for gloss reproduction. When the data acquisition is completed, the process proceeds to step S1002.

In step S1002, color matching processing is performed by the color matching unit 202 of the host device 21, and then the process proceeds to step S1003.
In step S1003, color separation processing is performed by the color separation unit 203 of the UV curable printer 22, and then the process proceeds to step S1004.
In step S1004, halftone processing is performed by the halftoning unit 204 of the UV curable printer 22, and then the process proceeds to step S1202. In the second embodiment, since the layer formed by the UV curable printer 22 is only the outermost layer, the processing by the overlap number determination unit 205 in FIG. 1 is unnecessary.

  In step S1202, the UV curable printer 22 acquires three-dimensional data (three-dimensional printer data) (three-dimensional data in the STL format shown in FIG. 12) used at the time of printing output by the three-dimensional printer. This three-dimensional data is acquired directly from a three-dimensional printer or from the host device 21 (via the host device 21). The three-dimensional data is data relating to the underlying layer. If three-dimensional data has been acquired, the process proceeds to step S1203.

  In step S1203, the UV curable printer 22 analyzes the three-dimensional data. The XYZ coordinates and normal vectors shown in FIG. 12 are used in the processing of step S1203. The analysis result includes information on the inclination (θ) of the printing surface calculated from the normal vector at each XYZ coordinate of the surface of the underlying layer (printing surface). Further, the height of the underlayer is also known from the value of the XYZ coordinates. Accordingly, the analysis result of the three-dimensional data includes the height information of the underlayer. When the analysis of the three-dimensional data ends, the process proceeds to step S1204. The inclination θ used in FIG. 5 is obtained by analyzing three-dimensional data. In the second embodiment, the inclination calculation unit 208a described in the first embodiment functions as a unit that analyzes the inclination information of the printing surface as described above.

  Step S1204 is a step of setting a process for forming the outermost layer on the base layer. The UV irradiation process of the UV curable printer 22 is set according to the inclination θ of the printing surface obtained in step S1203. The UV irradiation timing to the ink ejected from the UV curable printer 22 onto the surface of the underlayer is based on the analysis result (inclination information) in step S1203 using the equal dot curve in FIG. 5 for each ink dot. Can be determined.

  Following step S1204, step S1010 is executed. In step S1010, based on the UV irradiation process set in step S1204, the print head 209 of the UV curable printer 22 is driven to form the outermost layer. Since the appearance (shape, color, and gloss) of the uneven shape is finally determined by the outermost layer, the desired shape and color (coloring) are also formed on the print medium in the second embodiment as in the first embodiment. And a concavo-convex shape having a desired texture including gloss can be obtained.

(Modification)
Although image formation (printing) using the image forming apparatus of the present invention has been described based on Embodiment 1 and Embodiment 2, the present invention is not limited to the above-described embodiment. For example, in Embodiments 1 and 2, assuming that the texture information (color, height, gloss, etc. of each layer) of the object to be reproduced is known in advance, all layers are printed by a printer (UV curable printer 22, three-dimensional printer). However, the present invention is not limited to such a configuration. That is, the present invention can be applied even if the unevenness information of any of the layers constituting the uneven shape is unknown (for example, the unevenness information of the underlying layer is unknown). The acquisition of the unevenness information in that case will be described below.

  As a method for acquiring the unevenness information, a light cutting method, a focus movement method, a stereo matching method, and the like are known. As an example, FIG. 14 shows the principle of the light cutting method. As shown in FIG. 14, light (slit light) 43 from a light source 41 through a slit plate 42 is applied to an object 40 having a three-dimensional shape. The position of light on the object 40 can be obtained by triangulation if the positions of the light source 41 and the image sensor (camera) 44 are known. Therefore, the three-dimensional shape of the object 40 can be measured by moving the slit light 43 in the direction of the arrow X in FIG. 14 and detecting the reflected light (image of the object 40) from the object 40 by the image sensor 44. For example, by mounting the light source 41, the slit plate 42, and the image sensor 44 on the UV curable printer 22 of FIG. 1, the UV curable printer 22 can acquire the data of the outer shape of the object 40. Data acquisition of the outer shape of the object 40 can be easily performed by a pre-scan operation of the UV curable printer 22 or the like. When the stereo matching method is used, for example, a stereo camera is mounted on the UV curable printer 22.

  A method of converting data acquired by the light cutting method into, for example, an STL format is a well-known technique. Therefore, if, for example, the outline information of the underlayer described in the second embodiment can be obtained by the light cutting method illustrated in FIG. 14, the light cutting method can be used in the configuration of the second embodiment. That is, data obtained by the light cutting method may be converted into STL format data and used in a three-dimensional printer. The three-dimensional printer forms a base layer based on the STL format data.

  Moreover, the following cases can be considered as another usage of the light cutting method of FIG. For example, when the UV curable printer 22 prints on the surface of an object that is not flat, it can be said that the object is “the surface to be printed has an inclination” from the beginning. Therefore, when printing on such an object with the UV curable printer 22, first, information on the inclination θ of the print portion of the object is obtained by a light cutting method, and based on the amount of the inclination shown in FIG. The UV irradiation time t is determined from the equal dot diameter curve, and the UV curable printer 22 may perform printing.

As mentioned above, although various embodiment was explained in full detail, this invention can take the embodiment as a system, an apparatus, a method, a program, or a storage medium etc., for example. Specifically, the present invention may be applied to a system including a plurality of devices (for example, a host computer, an interface device, an imaging device, a web application, etc.), or may be applied to an apparatus including a single device.
Also, a process of supplying a program that realizes one or more functions of the above-described embodiment to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus reading and executing the program But it is feasible. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.
The present invention has several effects from one or more of the above.

  DESCRIPTION OF SYMBOLS 16 ... Medium to be printed, 22 ... UV curable printer (image forming apparatus), 27a, 28a ... Print surface (printed part), 208 ... UV irradiation process setting part (control means), 208a ... Inclination calculation part (Inclination) Information acquisition means), 209... Print head, 209 b, 209 c... UV-LED array (light irradiation means), θ.

Claims (14)

A print head for ejecting ink onto a print surface of a print medium;
Light irradiating means for irradiating light on the ink-printed surface from the print head and curing the ink on the surface to be printed;
Obtaining means for obtaining information on the inclination of the printing surface with respect to the ink ejection direction;
Control means for variably controlling light irradiation of the light irradiation means based on the acquired information of the inclination;
An image forming apparatus comprising:   The control unit changes a time from when the print head ejects the ink to when the light irradiation unit ejects the light according to the amount of inclination. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein the control unit changes an intensity of the light that the light irradiation unit irradiates the ink according to an amount of the inclination. The light irradiation means comprises a plurality of light emitting elements arranged,
4. The control unit according to claim 1, wherein the control unit selects a light emitting element to irradiate the ink with the light from the plurality of light emitting elements according to an amount of inclination of the printing surface. The image forming apparatus according to claim 1. Carriage means for mounting the light irradiation means and the ink nozzles of the print head;
The image forming apparatus according to claim 4, wherein the control unit selects the light emitting elements arranged closer to the ink nozzles as the amount of inclination is larger.   6. The image forming apparatus according to claim 5, wherein the control unit changes a scanning speed at which the carriage unit moves relative to the print medium in accordance with the amount of the inclination.   The image forming apparatus according to claim 6, wherein the control unit increases the scanning speed of the carriage unit as the amount of inclination increases.   The print head includes a plurality of ink nozzle rows arranged in a scanning direction at predetermined intervals, and at least a part of the light irradiation unit is disposed between the plurality of ink nozzle rows. The image forming apparatus according to claim 1.   A plurality of photocured ink layers are formed on a printing medium, and the control unit variably controls at least light irradiation to the ink ejected to the outermost layer of the ink layer. Item 9. The image forming apparatus according to any one of Items 1 to 8.   The image forming apparatus according to claim 1, wherein the acquisition unit acquires the inclination information of the printed surface from the outside.   2. The apparatus according to claim 1, further comprising a medium support unit on which the printing medium is placed, wherein the control unit controls light irradiation of the light irradiation unit by changing a speed of the medium support unit. The image forming apparatus according to claim 4.   12. The inclination of the printing surface is calculated based on a combination of a dot diameter of the ink constituting the printing surface or the number of overlapping times thereof. 2. The image forming apparatus according to item 1. Irradiating the ink that has landed on the printing surface of the printing medium from the printing head with light, and curing the ink on the printing surface;
Obtaining inclination information of the printing surface with respect to the ink ejection direction;
And a step of variably controlling the irradiation of the light based on the acquired tilt information. A computer program for causing a computer to function as each part of the image forming apparatus according to any one of claims 1 to 12, when the computer reads and executes the computer program.

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