Image forming apparatus, image forming method, and image forming program

Abstract

To provide an image formation apparatus which can express a high-gloss image in a hue like a metallic color.SOLUTION: An image formation apparatus according to an aspect of the present invention comprises: a liquid discharge head which discharges liquid onto a recording medium; an irradiation unit which irradiates the liquid on the recording medium with light; a carriage which is provided with the liquid discharge head and the irradiation unit; and a movement unit which alternately performs a main scanning movement that relatively moves the carriage in the main-scanning direction with respect to the recording medium and a sub-scanning movement that relatively moves the carriage in the sub-scanning direction orthogonal to the main-scanning direction with respect to the recording medium. The liquid contains metallic ink and color ink. The liquid discharge head discharges the color ink to a region where the metallic ink is discharged to the recording medium in the first main-scanning movement of the main-scanning movement in the second main-scanning movement subsequent to the first main-scanning movement. The irradiation unit irradiates the region to which the color ink has been discharged with the light.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an image forming apparatus, an image forming method, and an image forming program.

Background Art

[0002] Conventionally, there is known an image forming apparatus that forms an image on a recording medium by discharging a liquid while relatively moving a liquid discharge head provided with a plurality of nozzles for discharging a liquid in a nozzle row in a sub-scanning direction, a recording medium, in a main scanning direction and a sub-scanning direction orthogonal to the main scanning direction.

[0003] In addition, when forming an image by discharging a metallic ink containing ultraviolet curable metal particles, a printing method is disclosed in which a leveling step, a pre-curing step, and a main curing step are performed to improve the luminance of the image (see, for example, Patent Document 1).

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the printing method of Patent Document 1 only discloses image formation using only metallic ink, and cannot express a highly glossy image with colors such as metallic colors. This metallic color is expressed by overlapping metallic ink and color ink in a certain area.

[0005] An object of the present invention is to provide an image forming apparatus capable of expressing a highly glossy image with colors such as metallic colors.

Means for Solving the Problems

[0006] An image forming apparatus according to one aspect of the present invention comprises: a liquid ejection head for ejecting liquid onto a recording medium; an irradiation unit for irradiating light onto the liquid on the recording medium; a carriage on which the liquid ejection head and the irradiation unit are provided; and a moving unit that alternately performs a main scanning movement for moving the carriage relative to the recording medium in the main scanning direction and a sub-scanning movement for moving the carriage relative to the recording medium in the sub-scanning direction perpendicular to the main scanning direction, wherein the liquid includes metallic ink and color ink, and the liquid ejection head ejects the color ink in a second main scanning movement after the first main scanning movement to the region on which the metallic ink was ejected during the first main scanning movement, and the irradiation unit does not irradiate the region with light during the first main scanning movement. In a third main scanning movement, which is a main scanning movement that occurs after the first main scanning movement and before the second main scanning movement, the region is irradiated with the light. In the region after ejecting the color ink during the second main scanning movement ,before Shine the marking light. [Effects of the Invention]

[0007] According to the present invention, it is possible to express images with metallic colors and high gloss. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an example of the overall configuration of an image forming apparatus according to the first embodiment. Figure 1(a) is a perspective view from the front of the apparatus, and Figure 1(b) is a perspective view from the rear of the apparatus. [Figure 2] This is a diagram showing an example of the carriage configuration according to the first embodiment. [Figure 3] This is a diagram showing an example of the hardware configuration of an image forming apparatus according to the first embodiment. [Figure 4] This is a diagram showing an example of the functional configuration of a controller unit according to the first embodiment. [Figure 5] This is a flowchart illustrating an example of the operation of the image forming apparatus according to the first embodiment. [Figure 6]These diagrams illustrate the process of image formation on paper, with Figures 6(a) to 6(d) showing examples of image formation during the first to fourth main scan movements. [Figure 7] This is a diagram showing the configuration of the carriage in the comparative example. [Figure 8] This is a perspective view of another example of the overall configuration of the image forming apparatus according to the embodiment. [Figure 9] This figure shows an example of the configuration of the carriage of an image forming apparatus related to a modified example. [Modes for carrying out the invention]

[0009] The embodiments for carrying out the invention will be described below with reference to the drawings. In each drawing, the same reference numerals are used for identical components, and redundant explanations may be omitted.

[0010] Furthermore, the embodiments described below illustrate image forming apparatuses that embody the technical concept of the present invention, and do not limit the present invention to the embodiments described below. Unless otherwise specified, the dimensions, materials, shapes, relative arrangements, etc., of the components described below are intended to be illustrative and not to limit the scope of the present invention to those components alone. In addition, the size and positional relationships of the members shown in the drawings may be exaggerated to clarify the explanation.

[0011] The image forming apparatus according to the embodiment includes a liquid discharge head for discharging liquid onto a recording medium, an irradiation unit for irradiating light onto the liquid on the recording medium, a carriage on which the liquid discharge head and the irradiation unit are provided, and a moving unit that alternately performs a main scanning movement, which moves the carriage relative to the recording medium in the main scanning direction, and a sub-scanning movement, which moves the carriage relative to the recording medium in a sub-scanning direction perpendicular to the main scanning direction.

[0012] The liquid contains metallic ink and colored ink. The metallic ink and colored ink are, for example, UV-curable, and the irradiating part cures the liquid by irradiating it with ultraviolet light.

[0013] Also in an embodiment, in the liquid ejection head, for a region where metallic ink is ejected onto a recording medium in a first main scanning movement among main scanning movements, color ink is ejected in a second main scanning movement after the first main scanning movement, and the irradiation unit irradiates the region after the color ink is ejected with the light. Thereby, by ensuring a long time from the ejection of the metallic ink to the start of curing, the glossiness of the image formed on the recording medium is improved.

[0014] Here, "metallic" is an expression for having a metallic luster.

[0015] Hereinafter, an embodiment will be described by taking an inkjet type image forming apparatus that ejects an ultraviolet curable ink onto a sheet to form an image as an example. Here, the ink is an example of a liquid, and the sheet is an example of a recording medium. The sheet includes various types such as plain paper or glossy paper. However, the recording medium is not limited to paper and may be a plastic film, a prepreg, or a silver foil, etc.

[0016] Also, in the terms of the embodiment, image formation, recording, printing, imprinting, and printing are all synonymous. Further, the liquid may be any one having a viscosity and surface tension that can be ejected from the liquid ejection head, and is not particularly limited, but it is preferably one having a viscosity of 30 mPa·s or less at normal temperature and normal pressure, or by heating or cooling.

[0017] More specifically, it includes solutions, suspensions, emulsions, etc. containing solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functional imparting materials such as surfactants, biocompatible materials such as DNA, amino acids, proteins, and calcium, and edible materials such as natural pigments. These can be used, for example, in applications such as inkjet inks, surface treatment liquids, components of electronic elements and light emitting elements, and liquids for forming electronic circuit resist patterns, and material liquids for three-dimensional modeling.

[0018] A liquid ejection head is a functional component that ejects and sprays liquid from nozzles. As an energy source for ejecting the liquid, there are included those that use a piezoelectric actuator (a laminated piezoelectric element and a thin-film piezoelectric element), a thermal actuator that uses an electrothermal conversion element such as a heating resistor, an electrostatic actuator composed of a diaphragm and a counter electrode, and the like.

[0019] In the following description, the main scanning direction is the X-axis direction, the sub-scanning direction substantially orthogonal to the main scanning direction is the Y-axis direction, and the direction orthogonal to both the X-axis direction and the Y-axis direction is the Z-axis direction. Note that the direction in which the arrow points in the X-axis direction is denoted as the +X direction, the opposite direction of the +X direction is denoted as the -X direction, the direction in which the arrow points in the Y-axis direction is denoted as the +Y direction, the opposite direction of the +Y direction is denoted as the -Y direction, the direction in which the arrow points in the Z-axis direction is denoted as the +Z direction, and the opposite direction of the +Z direction is denoted as the -Z direction. However, these do not limit the orientation of the image forming apparatus, and the orientation of the image forming apparatus is arbitrary.

[0020] [First Embodiment] (Example of the overall configuration of the image forming apparatus 10) First, the overall configuration of the image forming apparatus 10 according to the embodiment will be described. FIG. 1 is a perspective view showing an example of the overall configuration of the image forming apparatus 10. FIG. 1(a) is a perspective view viewed from the front side of the apparatus, and FIG. 1(b) is a perspective view viewed from the back side of the apparatus.

[0021] The image forming apparatus 10 includes a carriage 200 and a mounting table 13 on which a sheet P is placed. The carriage 200 is provided with an ink ejection head and an irradiation unit. The ink ejection head is an example of a liquid ejection head in which a plurality of nozzles for ejecting ink onto the sheet P are provided as a nozzle row in the sub-scanning direction.

[0022] The ink ejection head forms an image by ejecting ink from the nozzles. The nozzles are provided so as to face the mounting table 13. Also, the irradiation unit is provided so as to face the mounting table 13. The ink ejection head and the irradiation unit will be described in detail separately with reference to FIG. 2.

[0023] Guide rods 19 are stretched across the left and right side plates 18a and 18b, and the guide rods 19 hold the carriage 200 so that it can move in the X-axis direction. The carriage 200 performs a main scanning movement along the guide rods 19, moving relative to the paper P in the main scanning direction.

[0024] Furthermore, the carriage 200, guide rod 19, and side plates 18a and 18b are integrated and can move in the Y-axis direction along a guide rail 29 provided at the bottom of the mounting base 13. The carriage 200 performs a sub-scanning movement along the guide rail 29, moving relative to the recording medium in the sub-scanning direction.

[0025] Furthermore, the carriage 200 is held so as to be movable in the Z direction (vertical direction).

[0026] The image forming apparatus 10 performs unidirectional printing, forming an image only in the forward path, which is the main scanning movement along the +X direction.

[0027] (Example configuration of Carriage 200) Next, the configuration of the carriage 200 will be explained with reference to Figure 2. Figure 2 is a diagram showing an example of the carriage configuration. Figure 2 is a view of the carriage 200 in Figure 1 from the -Z direction side.

[0028] The carriage 200 is a box-shaped member with an open side in the -Z direction. As shown in Figure 2, the carriage 200 contains a metallic ink ejection head 300, color ink ejection heads 301a and 301b, and an irradiation unit 400 inside the box-shaped member.

[0029] Since the color ink ejection heads 301a and 301b have the same configuration except for the color of the ink they eject and their position, they will be collectively referred to as the color ink ejection head 301 below unless otherwise specified.

[0030] The metallic ink ejection head 300 and the color ink ejection head 301 have the same configuration except for the type of ink ejected and their positions. However, they do not necessarily have to have the same configuration.

[0031] The carriage 200 holds the metallic ink ejection head 300, the color ink ejection head 301, and the irradiation unit 400 so that they face the paper P located on the -Z side of the carriage 200.

[0032] The metallic ink ejection head 300 has a piezoelectric element as a pressure generating unit, which contracts in response to a drive signal, and the pressure change accompanying the contraction ejects metallic ink through each nozzle included in the nozzle row 300n toward the -Z direction.

[0033] The metallic ink according to this embodiment is an ultraviolet-curable ink and comprises at least a monomer or oligomer, a photopolymerization initiator, and metallic particles. For example, an ink containing a methacrylate monomer can be used as the ultraviolet-curable ink. Methacrylate monomers have the characteristics of being relatively irritating to the skin and exhibiting a large degree of curing shrinkage.

[0034] UV-curable inks may also contain additives. These additives may include, for example, sensitizers, dispersants, leveling agents, and polymerization inhibitors, and can be selected as appropriate.

[0035] In this embodiment, the metallic particles are aluminum particles with an outer diameter of approximately 5 μm and a thickness of 0.1 μm or more and 0.2 μm or less, and are flaky or flattened. However, the invention is not limited to these, and metal particles other than aluminum can be used, and their shape does not have to be flaky.

[0036] The color ink ejection head 301 has a piezoelectric element as a pressure generating unit, which contracts in response to a drive signal, and the pressure change accompanying the contraction ejects color ink through each nozzle included in the nozzle row 301n toward the -Z direction.

[0037] The color ink according to this embodiment is an ultraviolet-curable ink and comprises at least a monomer or oligomer, a photopolymerization initiator, and colored particles. The colored particles are particles such as dyes or pigments. The colors of the colored particles are, for example, cyan, magenta, yellow, and black, but are not limited to these and can be appropriately selected depending on the application of the image forming apparatus 10.

[0038] The materials constituting the UV-curable ink are not particularly limited to those described above, and various materials can be used as appropriate depending on the application of the image forming apparatus 10. The same applies to the viscosity and surface tension of the ink.

[0039] It is preferable from the viewpoint of improving curing efficiency or drying efficiency if at least one of the metallic ink and the color ink contains a solvent, as this increases volatility. It is also preferable from the viewpoint of environmental resistance if at least one of the metallic ink and the color ink contains water.

[0040] The irradiation unit 400 is an example of an irradiation unit that irradiates light onto metallic ink and color ink on paper P.

[0041] In this embodiment, the irradiation unit 400 cures the metallic ink and color ink on the paper P by irradiating them with ultraviolet light. The cured metallic ink and color ink adhere to and fix to the paper P. For example, a UV (Ultra Violet) lamp can be used as the irradiation unit 400.

[0042] The length of the irradiation unit 400 in the sub-scanning direction is preferably longer than the lengths of the metallic ink ejection head 300 and the color ink ejection head 301 in the sub-scanning direction. This allows the metallic ink ejection head 300 or the color ink ejection head 301 to irradiate the entire surface of the ink ejected onto the paper P in a single main scan movement with ultraviolet light in the sub-scanning direction.

[0043] As shown in Figure 2, in the carriage 200, the irradiation unit 400, the metallic ink ejection head 300, and the color ink ejection head 301 are arranged in this order from the upstream side to the downstream side of the forward path in the main scanning movement. The color ink ejection heads 301a and 301b are arranged side by side along the main scanning direction.

[0044] The metallic ink ejection head 300 is located downstream (+Y direction) of the color ink ejection head 301 along the sub-scanning direction, at a position offset by twice a predetermined sub-scanning width from the position where the color ink ejection head 301 is located. This sub-scanning width is approximately equal to the length of the nozzle rows 300n and 301n along the sub-scanning direction.

[0045] The color ink ejection head 301 and the irradiation unit 400 are arranged to overlap in the sub-scanning direction, while the metallic ink ejection head 300 and the irradiation unit 400 are arranged not to overlap in the sub-scanning direction.

[0046] Specifically, the metallic ink ejection head 300 is located downstream (towards the +Y direction) of the irradiation unit 400 along the sub-scanning direction, at a position offset by the sub-scanning width from the position where the irradiation unit 400 is located.

[0047] (Example of hardware configuration of image forming apparatus 10) Next, the hardware configuration of the image forming apparatus 10 will be described with reference to Figure 3. Figure 3 is a block diagram showing an example of the hardware configuration of the image forming apparatus 10.

[0048] As shown in Figure 3, the image forming apparatus 10 includes a controller unit 3, a detection group 4, a transport unit 100, a carriage 200, a metallic ink ejection head 300, a color ink ejection head 301, an irradiation unit 400, and a maintenance unit 500.

[0049] Of these, the controller unit 3 includes a unit control circuit 31, a memory 32, a CPU (Central Processing Unit) 33, and an I / F (Interface) 34.

[0050] I / F34 is an interface for connecting the image forming apparatus 10 to an external device, the PC (Personal Computer) 2. The connection method between the image forming apparatus 10 and the PC 26 can be anything, including a connection via a network or a direct connection between the two using a communication cable.

[0051] The CPU 33 uses the memory 32 as a workspace to control each unit of the image forming apparatus 10 via the unit control circuit 31. Specifically, the CPU 33 controls each unit based on the image data received from the PC 26 and the data detected by the detection group 4 to form an image on the paper P.

[0052] Detection group 4 consists of various sensors provided in the image forming apparatus 10, such as an encoder sensor that detects the position of the carriage 200 in the main scanning direction.

[0053] PC26 has a printer driver installed. The printer driver generates image data to be sent to the image forming apparatus 10. The image data includes command data to operate the carriage 200, etc., of the image forming apparatus 10, and pixel data related to the image to be formed.

[0054] The transport unit 100 is a unit equipped with a transport mechanism for transporting paper P. The transport unit 100 is also an example of a moving part that performs a main scanning movement, which moves the carriage 200 relative to the paper P in the main scanning direction, and a sub-scanning movement, which moves the carriage 200 relative to the paper P in the sub-scanning direction. The transport unit 100 includes a guide rod 19 and a guide rail 29, etc.

[0055] The maintenance unit 500 has a mechanism for maintaining and restoring the ejection function of the metallic ink ejection head 300 and the color ink ejection head 301. The maintenance and restoration mechanism includes a cap for covering the nozzle surface to protect the nozzle from drying out during periods when the image forming apparatus 10 is not forming images.

[0056] This cap includes a moisturizing cap that serves solely to cover the nozzle surface and protect it from drying, and a suction cap that, in addition to the function of a moisturizing cap, connects to a suction pump and sucks up the thickened ink from the metallic ink ejection head 300 and the color ink ejection head 301.

[0057] (Example of the functional configuration of controller unit 3) Next, the functional configuration of the controller unit 3 provided in the image forming apparatus 10 will be described. Figure 4 is a block diagram showing an example of the functional configuration of the controller unit 3. As shown in Figure 4, the controller unit 3 has an image processing unit 12 and a control unit 30.

[0058] The image processing unit 12 includes a data receiving unit 121, a data generation unit 122, and a data output unit 123.

[0059] The data receiving unit 121 receives image data from the PC 26. The image data includes information such as the pattern or color of the image to be formed. The data generation unit 122 performs predetermined data processing, such as CMYK conversion, degradation, and image conversion, on the image data received by the data receiving unit 121, and generates recording data for forming an image on the paper P based on the image data. The data output unit 123 outputs the generated recording data to the control unit 30.

[0060] The control unit 30 includes an ejection control unit 14, a print mode receiving unit 21, an irradiation drive unit 22, a first drive unit 23, a second drive unit 24, and a formation control unit 25.

[0061] The ejection control unit 14 ejects ink from the metallic ink ejection head 300 and the color ink ejection head 301 based on the recorded data. The print mode receiving unit 21 receives information regarding the print mode. The print mode is information indicating whether to print in color or monochrome, or to print on one side or both sides of paper P, etc.

[0062] The irradiation drive unit 22 drives the irradiation unit 400 to irradiate ultraviolet light.

[0063] The first drive unit 23 moves the carriage 200 in the sub-scanning direction, causing the carriage 200 and the paper P to move relative to each other in the sub-scanning direction. The second drive unit 24 moves the carriage 200 in the main scanning direction, causing the carriage 200 and the paper P to move relative to each other in the main scanning direction.

[0064] The forming control unit 25 receives recording data from the image processing unit 12 and controls the ejection control unit 14, the irradiation drive unit 22, the first drive unit 23, and the second drive unit 24 so that the metallic ink ejection head 300 and the color ink ejection head 301 eject ink corresponding to each pixel of the recording data according to the received recording data.

[0065] <Example of operation of the image forming apparatus 10> Next, the operation of the image forming apparatus 10 will be explained with reference to Figure 5. Figure 5 is a flowchart showing an example of the operation of the image forming apparatus 10. Figure 5 shows the operation triggered by the timing when the image forming apparatus 10 receives image data from the PC 26, forms the recording data, and starts image formation control. Figure 5 also shows the operation when the image forming apparatus 10 forms an image in five main scan movements.

[0066] First, in step S51, the forming control unit 25 moves the carriage 200 in the sub-scanning direction and stops it at the initial position for recording the image.

[0067] Next, in step S52, the forming control unit 25 drives the lifting mechanism to move the carriage 200 to a height suitable for ink ejection by the metallic ink ejection head 300 and the color ink ejection head 301. The height refers to a position along the Z direction.

[0068] This height is, for example, the height at which the gap between the metallic ink ejection head 300 and the color ink ejection head 301 and the paper P is 1 mm. The forming control unit 25 preferably drives and controls the lifting mechanism based on the detection signal from the height sensor that detects the height of the metallic ink ejection head 300 and the color ink ejection head 301.

[0069] Next, in step S53, the forming control unit 25 moves the carriage 200 to the forward path as the first main scanning movement.

[0070] During the first main scan movement, in step S54, the metallic ink ejection head 300 ejects metallic ink into the first area of ​​the paper P. After the first main scan movement is completed, the forming control unit 25 stops the carriage 200, then performs a main scan movement in the return direction, returning it to its original position in the main scan direction and stopping it. Note that during the main scan movement in the return direction in one-way printing, the metallic ink ejection head 300 and the color ink ejection head 301 do not eject ink. This is also true for the main scan movement in the return direction in one-way printing.

[0071] Next, in step S55, the forming control unit 25 moves the carriage 200 in the sub-scanning direction by the sub-scanning width.

[0072] Next, in step S56, the forming control unit 25 moves the carriage 200 to the forward path as the second main scanning movement.

[0073] During the second main scanning movement, in step S57, the metallic ink ejection head 300 ejects metallic ink into a second area of ​​the paper P. The second area is shifted by the sub-scan width downstream (+Y direction) along the sub-scanning direction relative to the first area.

[0074] Furthermore, during the second main scanning movement, in step S58, the irradiation unit 400 irradiates the metallic ink ejected onto the first area of ​​the paper P with ultraviolet light. As a result, the metallic ink ejected onto the first area of ​​the paper P hardens and fixes to the paper P.

[0075] Furthermore, the irradiation unit 400 keeps its UV lamp constantly lit and irradiates with ultraviolet light after the start of the formation control. The metallic ink and color ink are irradiated with ultraviolet light when the irradiation unit 400 faces the metallic ink and color ink ejected into the first region of the paper P. When the irradiation unit 400 faces the metallic ink and color ink ejected into the first region of the paper P, it means that the first region and the irradiation unit 400 overlap in the direction of viewing the paper P from above.

[0076] However, the irradiation unit 400 may be controlled to turn on the UV lamp only when it is facing the metallic ink and color ink ejected onto the first area of ​​the paper P, and to turn off the UV lamp at all other times. These points also apply to subsequent irradiation of ultraviolet light by the irradiation unit 400.

[0077] Here, the metallic ink ejection head 300 is positioned offset by the sub-scan width in the +Y direction of the irradiation unit 400. Therefore, during the first main scan movement, the irradiation unit 400 does not face the metallic ink ejected onto the paper P during the first main scan movement, and thus the metallic ink is not irradiated with ultraviolet light.

[0078] On the other hand, during the second main scanning movement, ultraviolet light is irradiated onto the metallic ink ejected onto the paper P during the first main scanning movement, as the machine faces the metallic ink ejected onto the paper P during the first main scanning movement. This ensures a longer time between the ejection of the metallic ink onto the paper P during the first main scanning movement and the start of curing.

[0079] After the second main scan movement is completed, the forming control unit 25 stops the carriage 200, then performs a main scan movement on the return path, returning it to its original position in the main scan direction and stopping it.

[0080] Next, in step S59, the forming control unit 25 moves the carriage 200 in the sub-scanning direction by the sub-scanning width.

[0081] Next, in step S60, the forming control unit 25 moves the carriage 200 to the forward path as the third main scanning movement.

[0082] During the third main scanning movement, in step S61, the color ink ejection head 301 ejects color ink into the first area of ​​the paper P.

[0083] Furthermore, during the third main scanning movement, in step S62, the metallic ink ejection head 300 ejects metallic ink into the third area of ​​the paper P. The third area is an area shifted by the sub-scan width downstream (+Y direction) along the sub-scanning direction relative to the second area.

[0084] Furthermore, during the third main scanning movement, in step S63, the irradiation unit 400 irradiates ultraviolet light onto the metallic ink ejected into the second area of ​​the paper P. In parallel with this, the irradiation unit 400 irradiates ultraviolet light onto the color ink ejected into the first area of ​​the paper P. As a result, the metallic ink ejected into the second area of ​​the paper P and the color ink ejected into the first area of ​​the paper P harden and fix to the paper P.

[0085] Here, the ink ejection head, which includes a metallic ink ejection head 300 and a color ink ejection head 301, ejects color ink to the first region on the paper P during the first main scanning movement of the main scanning movement, and the irradiation unit 400 irradiates with ultraviolet light after ejecting the color ink.

[0086] Furthermore, the color ink is ejected by the color ink ejection head 301 during the third main scan movement, and the irradiation unit 400 irradiates ultraviolet light during the third main scan movement, which is the main scan movement after the color ink has been ejected.

[0087] The first main scan movement is an example of the first main scan movement, and the third main scan movement is an example of the second main scan movement. The second main scan movement is an example of the third main scan movement, which occurs after the first main scan movement and before the second main scan movement. The irradiation unit 400 irradiates the area of ​​the paper P with ultraviolet light during the third main scan movement.

[0088] During the second main scanning movement, the metallic ink ejected onto the paper P is irradiated with ultraviolet light during the third main scanning movement, thus ensuring a longer time between the ejection of the metallic ink and the start of curing.

[0089] The metallic ink ejection head 300 is positioned downstream of the color ink ejection head 301 in the sub-scanning direction, offset by twice the sub-scanning width. Therefore, during the third main scan movement, the metallic ink ejection head 300 can eject metallic ink into the third area of ​​the paper P, and the color ink ejection head 301 can eject color ink into the first area of ​​the paper P.

[0090] Furthermore, since the color ink ejection head 301 and the irradiation unit 400 are positioned to overlap in the sub-scanning direction, the color ink ejected onto the paper P during the third main scanning movement is irradiated with ultraviolet light during the third main scanning movement.

[0091] After the third main scan movement is completed, the forming control unit 25 stops the carriage 200, then performs a main scan movement on the return path, returning it to its original position in the main scan direction and stopping it.

[0092] Next, in step S64, the forming control unit 25 moves the carriage 200 in the sub-scanning direction by the sub-scanning width.

[0093] Next, in step S65, the forming control unit 25 moves the carriage 200 to the forward path as the fourth main scanning movement.

[0094] During the fourth main scanning movement, in step S66, the color ink ejection head 301 ejects color ink into the second area of ​​the paper P.

[0095] Furthermore, during the fourth main scanning movement, in step S67, the irradiation unit 400 irradiates ultraviolet light onto the metallic ink ejected into the third area of ​​the paper P. In parallel with this, the irradiation unit 400 also irradiates ultraviolet light onto the color ink ejected into the second area of ​​the paper P. As a result, the metallic ink ejected into the third area of ​​the paper P and the color ink ejected into the second area of ​​the paper P harden and fix to the paper P.

[0096] Here, the color ink is ejected by the color ink ejection head 301 during the third main scan movement, and the irradiation unit 400 irradiates ultraviolet light during the fourth main scan movement, which is the next main scan movement after the ejection of the color ink.

[0097] After the fourth main scan movement is completed, the forming control unit 25 stops the carriage 200, then performs a main scan movement on the return path, returning it to its original position in the main scan direction and stopping it.

[0098] Next, in step S68, the forming control unit 25 moves the carriage 200 in the sub-scanning direction by the sub-scanning width.

[0099] Next, in step S69, the forming control unit 25 moves the carriage 200 to the forward path as the fifth main scanning movement.

[0100] During the fifth main scanning movement, in step S70, the color ink ejection head 301 ejects color ink into the third area of ​​the paper P.

[0101] Furthermore, during the fifth main scanning movement, in step S71, the irradiation unit 400 irradiates the color ink ejected into the third area of ​​the paper P with ultraviolet light. As a result, the color ink ejected into the third area of ​​the paper P hardens and fixes to the paper P.

[0102] In this way, the image forming apparatus 10 can form an image in the first to third regions of the paper P by five main scanning movements.

[0103] In Figures 5 and 6, an example of image formation is shown using five main scanning movements. However, the image forming apparatus 10 can also increase the number of main scanning movements by repeatedly performing steps S55 to S59 in Figure 5. By increasing the number of main scanning movements, an image can be formed over a larger area of ​​the paper P.

[0104] (Effects of the image forming apparatus 10) Next, the effects of the image forming apparatus 10 will be explained.

[0105] When forming images using metallic inks containing metal particles, it is important to improve the glossiness of the metallic ink. In particular, UV-curing inks tend to become thick, and their glossiness changes with thickness, so there is room for improvement in glossiness.

[0106] As a result of the inventor's diligent research into the glossiness of such metallic inks, it was found that increasing the time between the ejection of the metallic ink and the irradiation of light by the irradiation unit 400 improves the glossiness of the image. The reason for this is presumed to be as follows.

[0107] If metallic ink is exposed to light immediately after it lands on the medium, the metallic ink hardens in the same state it was in immediately after landing on the paper P. On the other hand, if the time between the metallic ink landing on the paper P and the exposure to light is extended, the metallic ink spreads and wets the paper P before it hardens. As a result, the ink film thickness becomes thinner, and the numerous metal foil fragments contained in the metallic ink become more likely to orient parallel to the medium. Furthermore, because the numerous metal foil fragments oriented parallel to the medium are more likely to reflect light in the same direction without scattering it, the glossiness of the image is improved.

[0108] Therefore, the image forming apparatus 10 according to this embodiment includes an ink ejection head (liquid ejection head) for ejecting ink (liquid) onto a sheet of paper P (recording medium), an irradiation unit 400 (irradiation unit) for irradiating ultraviolet light (light) onto the ink on the sheet of paper P, and a carriage 200 on which the ink ejection head and the irradiation unit 400 are provided. The image forming apparatus 10 also includes a transport unit 100 (movement unit) that alternately performs a main scanning movement, which moves the carriage 200 relative to the sheet of paper P in a main scanning direction perpendicular to the main scanning direction, and a sub-scanning movement, which moves the carriage 200 relative to the sheet of paper P in a sub-scanning direction.

[0109] The ink includes metallic ink and color ink. The ink ejection head ejects metallic ink to the area on the paper P during the first main scan movement (first main scan movement), and then ejects color ink during the second main scan movement (second main scan movement) which follows the first main scan movement. The irradiation unit 400 irradiates the area after the color ink has been ejected with ultraviolet light.

[0110] The ink ejection head cures the metallic ink by irradiating it with ultraviolet light during a main scan movement that follows the main scan movement in which the metallic ink was ejected. This allows for a longer curing time between ejection and the start of curing of metallic ink compared to the curing time between ejection and the start of curing of color ink. As a result, the glossiness of images formed using metallic ink is improved, enabling the expression of highly glossy images with metallic-like colors.

[0111] Furthermore, in this embodiment, the carriage 200 is not slowed down or stopped in order to ensure a longer time from the ejection of the metallic ink to the start of curing. Therefore, it is possible to increase the glossiness of the image while ensuring high productivity in image formation.

[0112] In this embodiment, the color ink is ejected by the color ink ejection head 301 during the second main scan movement (second main scan movement), and the irradiation unit 400 irradiates ultraviolet light during the second main scan movement, which is the main scan movement after the color ink has been ejected. This allows for a longer curing time from ejection to the start of curing of the metallic ink compared to the curing time from ejection to the start of curing of the color ink, thereby improving the glossiness of the image formed using the metallic ink.

[0113] In this embodiment, each area on the paper P from which the metallic ink was ejected is irradiated with ultraviolet light a total of two times by the irradiation unit 400. This allows the metallic ink to be cured more reliably.

[0114] Furthermore, the irradiation unit 400 may also irradiate the area on the paper P where the color ink was ejected with ultraviolet light during the main scanning movement, which is the next main scanning movement after the ejection of the color ink. This allows for an even longer time between the ejection of the metallic ink and the second ultraviolet irradiation in each area of ​​the paper P, further improving the glossiness of the image formed using the metallic ink and enabling the expression of a highly glossy image with metallic colors.

[0115] In other words, the first main scan move may be any main scan move in any order, and the second main scan move may be any main scan move in any order as long as it occurs after the first main scan move. For example, the first main scan move may be the second main scan move, and the second main scan move may be the fourth main scan move, which occurs after the first main scan move.

[0116] (Comparative example) Here, Figure 7 shows the configuration of carriage 200X according to a comparative example. In Figure 7, components having the same function as carriage 200 according to this embodiment are conveniently given the same part numbers.

[0117] As shown in Figure 7, in the carriage 200X, the color ink ejection head 301 and the irradiation unit 400 are positioned to overlap in the sub-scanning direction. Similarly, the metallic ink ejection head 300 and the irradiation unit 400 are also positioned to overlap in the sub-scanning direction.

[0118] In this configuration, during the same main scanning motion in which the metallic ink ejection head 300 ejects metallic ink, the irradiation unit 400 irradiates the metallic ink ejected onto the paper P with ultraviolet light.

[0119] In this embodiment, since ultraviolet light is irradiated after the main scanning movement following the ejection of metallic ink by the metallic ink ejection head 300, a longer time can be secured from the ejection of metallic ink to the start of curing compared to the comparative example. Therefore, in this embodiment, the glossiness of the image formed using metallic ink can be further improved compared to the comparative example.

[0120] Furthermore, while this embodiment illustrates a configuration using UV-curable ink, it is not limited to this. For example, ink that hardens with light energy such as infrared rays or thermal energy may be used, but from the viewpoint of hardening efficiency, UV-curable ink is preferred.

[0121] Furthermore, in this embodiment, the metallic ink ejection head 300 and the color ink ejection head 301 are shown as being offset by twice the sub-scanning width along the sub-scanning direction, but the embodiment is not limited to this, and they may be offset by an integer multiple of the sub-scanning width.

[0122] Furthermore, while this embodiment illustrates the operation of an image forming apparatus in which the carriage moves in both the main scanning direction and the sub-scanning direction, it is not limited to this. For example, the carriage can be moved in the main scanning direction and the paper P can be moved in the sub-scanning direction.

[0123] Here, Figure 8 is a perspective view showing another example of the configuration of such an image forming apparatus. In Figure 8, the image forming apparatus is shown partially from an oblique upward direction.

[0124] As shown in Figure 8, the image forming apparatus 10a comprises an apparatus body 101, a feeding device 102, and a winding device 103. The feeding device 102 is a medium supply device that supplies rolled-up sheet-like paper P located below the apparatus body 101. The rolled-up paper P is an example of a recording medium.

[0125] The feeding device 102 holds a roll body 112 in which paper P is wound around a hollow shaft portion 115. The winding device 103 is equipped with a hollow shaft portion 114 for winding paper P, and the roll body 112 is wound onto this hollow shaft portion 114. Note that the feeding device 102 and the winding device 103 may be integrally configured with the main body 101 rather than being separate components.

[0126] The feeding device 102 supplies paper P into the main body 101 of the device. Inside the main body 101 of the device is an image forming unit 104 which forms an image on the paper P supplied in the transport direction indicated by arrow B. Guide rods 1 and guide stays 2, which are guide members, are stretched across both side plates of the image forming unit 104, and these guide rods 1 and guide stays 2 support the carriage 200 so that it can move in the main scanning direction indicated by arrow A. The winding device 103 winds up the image formed paper P.

[0127] A main scanning motor 8, which is the drive source for reciprocating the carriage 200, is located on one side of the main scanning direction. A timing belt 11 is wrapped between a drive pulley 9, which is rotationally driven by the main scanning motor 8, and a driven pulley 20 located on the other side of the main scanning direction. The belt holding portion of the carriage 200 is fixed to this timing belt 11, and the carriage 200 is moved back and forth in the main scanning direction by driving the main scanning motor 8.

[0128] Even with this configuration of the image forming apparatus 10a, the same effect as the image forming apparatus 10 described above can be obtained by applying the carriage 200 shown in Figure 2.

[0129] (modified version) Figure 9 shows an example of the configuration of the carriage 200a in the modified image forming apparatus 10a. The image forming apparatus 10a differs from the above-described embodiment in that, in order to speed up color printing, two sets of color ink ejection heads 301a and 301b are provided along the sub-scanning direction.

[0130] The print mode receiving unit 21 of the image forming apparatus 10a accepts a print mode specified by the user, or receives information regarding the print mode along with image data received from the PC 26.

[0131] If the print mode received by the print mode receiving unit 21 is the first image print mode which includes metallic colors, the image forming apparatus 10a does not use one of the two sets of color ink ejection heads 310a and 301b, specifically the one on the +Y direction side (metallic ink ejection head 300 side) in Figure 9, and ejects metallic ink and color ink to perform printing in essentially the same way as in the embodiment described above. In other words, the image forming apparatus 10a performs printing using only the color ink ejection heads 301a and 301b, which are enclosed by the thick dashed frame A in Figure 9.

[0132] On the other hand, if the accepted printing mode is a second image printing mode that does not include metallic colors, the image forming apparatus 10a performs printing using two sets of color ink ejection heads 301a and 301b without using the metallic ink ejection head 300.

[0133] In this modified version, the image forming apparatus 10a can print images at high speed by using two sets of color ink ejection heads 301a and 301b when printing in a color image printing mode that does not include metallic colors. In addition, when printing in a color image printing mode that includes metallic colors, the image forming apparatus 10a can produce high-gloss images with metallic-like colors. Other effects are the same as those of the image forming apparatus 10.

[0134] Although preferred embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the embodiments of the present invention as described in the claims.

[0135] In the embodiments described above, examples were given of a configuration in which the carriage 200 moves in both the main scanning direction and the sub-scanning direction, and a configuration in which the carriage moves in the main scanning direction and the paper P moves in the sub-scanning direction, but the invention is not limited to these. As long as the paper P and the carriage can move relative to each other, a configuration in which the paper P moves in both the main scanning direction and the sub-scanning direction, or a configuration in which the paper P moves in the main scanning direction and the carriage moves in the sub-scanning direction, is also acceptable.

[0136] The embodiments also include an image forming method. For example, the image forming method includes the steps of: discharging a liquid onto a recording medium using a liquid discharging head; irradiating the liquid on the recording medium with light using an irradiation unit; and alternately performing a main scanning movement in which a carriage equipped with the liquid discharging head and the irradiation unit is moved relative to the recording medium in the main scanning direction, and a sub-scanning movement in which the carriage is moved relative to the recording medium in a sub-scanning direction perpendicular to the main scanning direction, wherein the liquid includes metallic ink and color ink, and the liquid discharging head, in the first main scanning movement of the main scanning movement, dispenses the color ink onto the region on the recording medium where the metallic ink was dispensed, and in the second main scanning movement following the first main scanning movement, dispenses the color ink onto the region after the color ink has been dispensed, and the irradiation unit irradiates the region with light after the color ink has been dispensed. Such an image forming method can obtain the same effects as the image forming apparatus described above. Such an image forming method may be implemented by a CPU, LSI or other circuit, IC card or standalone module, etc.

[0137] The embodiment also includes an image forming program. For example, the image forming program is a program that causes a computer to perform the following processes alternately: discharging a liquid onto a recording medium using a liquid discharging head; irradiating the liquid on the recording medium with light using an irradiation unit; and alternately performing a main scanning movement in which a carriage equipped with the liquid discharging head and the irradiation unit is moved relative to the recording medium in the main scanning direction, and a sub-scanning movement in which the carriage is moved relative to the recording medium in the sub-scanning direction perpendicular to the main scanning direction. The liquid includes metallic ink and color ink, and in the first main scanning movement of the main scanning movement, the liquid discharging head discharges the color ink onto the region on the recording medium where the metallic ink was discharged, and in the second main scanning movement following the first main scanning movement, the irradiation unit irradiates the region after the color ink has been discharged with light. Such an image forming program can obtain the same effects as the image forming apparatus described above.

[0138] Furthermore, the ordinal numbers, quantities, and other figures used in the description of the embodiments are all illustrative to specifically illustrate the technology of the present invention, and the present invention is not limited to these illustrative figures. Also, the connection relationships between the components are illustrative to specifically illustrate the technology of the present invention, and the connection relationships that realize the functions of the present invention are not limited thereto.

[0139] Furthermore, the division of blocks in the functional block diagram is just one example; multiple blocks may be implemented as a single block, one block may be divided into multiple parts, or some functions may be moved to other blocks. Also, the functions of multiple blocks with similar functions may be processed in parallel or time-sharing by a single piece of hardware or software.

[0140] Furthermore, each function of the embodiments described above can be realized by one or more processing circuits. Hereinafter, "processing circuit" as used herein includes processors programmed to execute each function by software, such as processors implemented by electronic circuits, as well as devices such as ASICs (Application Specific Integrated Circuits), DSPs (digital signal processors), FPGAs (field programmable gate arrays), and conventional circuit modules designed to execute each of the functions described above. [Explanation of symbols]

[0141] 3. Controller Unit 10, 10a, 10b Image forming device 12 Image Processing Unit 13. Mounting platform 14 Discharge control unit 18a, 18b side plate 19 Guide Rods 21 Print Mode Acceptance Unit 22 Irradiation drive unit 23 First drive unit 24 Second drive unit 25 Forming control unit 29 Guide rails 61 1st area 62 Second area 63 Third area 100 Transport Unit (Example of a mobile unit) 200 Carriage 300, 300a, 300b Metallic Ink Ejection Heads 301, 301a, 301b Color ink ejection heads 400 Irradiation Unit (Example of Irradiation Section) 300n, 301n nozzle row P paper [Prior art documents] [Patent Documents]

[0142] [Patent Document 1] Japanese Patent Publication No. 2013-230626

Claims

1. A liquid dispensing head that dispenses liquid onto a recording medium, An irradiation unit that irradiates light onto the liquid on the recording medium, A carriage provided with the liquid discharge head and the irradiation unit, The device comprises a moving unit that alternately performs a main scanning movement, which moves the carriage relative to the recording medium in the main scanning direction, and a sub-scanning movement, which moves the carriage relative to the recording medium in a sub-scanning direction perpendicular to the main scanning direction, The liquid comprises metallic ink and colored ink. The liquid ejection head ejects the color ink in the region where the metallic ink was ejected onto the recording medium during the first main scan movement of the main scan movement, during the second main scan movement which follows the first main scan movement. The irradiation unit is In the first main scanning movement, the region is not irradiated with the light. In a third main scanning movement, which is a main scanning movement that occurs after the first main scanning movement and before the second main scanning movement, the region is irradiated with the light. An image forming apparatus characterized by irradiating the region after the color ink has been ejected in the second main scanning movement with the light.

2. The image forming apparatus according to claim 1, characterized in that the irradiation unit irradiates the region with light during the second main scanning movement, which is the same main scanning movement as when ejecting the color ink.

3. The image forming apparatus according to claim 1 or 2, characterized in that each of the metallic ink and the color ink is ultraviolet curable.

4. The image forming apparatus according to any one of claims 1 to 3, characterized in that at least one of the metallic ink and the color ink contains a solvent.

5. The image forming apparatus according to any one of claims 1 to 3, characterized in that at least one of the metallic ink and the color ink contains water.

6. A step of discharging the liquid onto a recording medium using a liquid discharging head, The process involves irradiating the liquid on the recording medium with light using an irradiation unit, The process includes alternating between a main scanning movement, in which a carriage equipped with the liquid discharge head and the irradiation unit is moved relative to the recording medium in the main scanning direction, and a sub-scanning movement, in which the carriage is moved relative to the recording medium in a sub-scanning direction perpendicular to the main scanning direction. The liquid comprises metallic ink and colored ink. The liquid ejection head ejects the color ink in the region where the metallic ink was ejected onto the recording medium during the first main scan movement of the main scan movement, during the second main scan movement which follows the first main scan movement. The irradiation unit is In the first main scanning movement, the region is not irradiated with the light. In a third main scanning movement, which is a main scanning movement that occurs after the first main scanning movement and before the second main scanning movement, the region is irradiated with the light. An image forming method characterized by irradiating the region after the color ink has been ejected in the second main scanning movement with the light.

7. The liquid is discharged onto the recording medium by a liquid discharge head, The irradiation unit irradiates light onto the liquid on the recording medium, A program that causes a computer to perform a process of alternately moving a carriage equipped with the liquid discharge head and the irradiation unit relative to the recording medium in the main scanning direction, and moving the carriage relative to the recording medium in the sub-scanning direction perpendicular to the main scanning direction, The liquid comprises metallic ink and colored ink. The liquid ejection head ejects the color ink in the region where the metallic ink was ejected onto the recording medium during the first main scan movement of the main scan movement, during the second main scan movement which follows the first main scan movement. The irradiation unit is In the first main scanning movement, the region is not irradiated with the light. In a third main scanning movement, which is a main scanning movement that occurs after the first main scanning movement and before the second main scanning movement, the region is irradiated with the light. An image forming program characterized by irradiating the region after the color ink has been ejected during the second main scanning movement with the light.

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