Inkjet printer

Abstract

To provide a novel inkjet printer which can control touch feeling.SOLUTION: An inkjet printer includes: an ink head having a nozzle for discharging droplets of a photocurable ink toward a recording medium 2; a light irradiation device for irradiating the droplets discharged onto the recording medium 2 with light; and a control part for controlling the ink head and the light irradiation device. The control part includes a touch feeling imparting control part for controlling a discharge amount of the photocurable ink discharged from the nozzle and a timing at which the light is emitted from the light irradiation device, thereby forming a projection 3 having a predetermined size and / or predetermined surface roughness on the recording medium 2, and imparting touch feeling to the recording medium.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an ink-jet printer that uses photocurable ink. [Background technology]

[0002] Inkjet printers that print desired images on a recording medium using an inkjet method have been known for some time. For example, Patent Document 1 discloses an inkjet printer that includes an inkjet head having a nozzle that ejects droplets of UV ink, ejects droplets of 70 pl or more from the nozzle, and prints on a recording medium in one pass. Patent Document 1 describes that by ejecting giant droplets of 70 pl or more from the nozzle, a printed matter having unevenness with an arithmetic roughness of 3 μm or more is formed, thereby imparting a decorative effect to the printing medium. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-109429 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, according to the inventors' investigations, even with the above techniques, it is difficult to control the tactile feel of printed matter. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a novel inkjet printer capable of controlling the tactile feel. [Means for solving the problem]

[0005] The present inventors conceived of forming protrusions on the surface of a printed matter, and further controlling the tactile feel of the printed matter by varying the surface condition of the protrusions, for example, the size or surface roughness of the protrusions. After extensive investigations, they have come up with the present invention.

[0006] The inkjet printer according to the present invention includes an ink head having nozzles for ejecting droplets of a photocurable ink toward a recording medium, a light irradiation device for irradiating the droplets ejected onto the recording medium with light, and a control unit for controlling the ink head and the light irradiation device. The control unit includes a tactile sensation imparting control unit configured to form protrusions having a predetermined size and / or a predetermined surface roughness on the recording medium by controlling the amount of the photocurable ink ejected from the nozzles and the timing of the light irradiation from the light irradiation device, thereby imparting a tactile sensation to the recording medium.

[0007] The inkjet printer can form protrusions of a predetermined size and / or a predetermined surface roughness (unevenness) on the recording medium. This allows the desired tactile sensation, for example, a rough or smooth tactile sensation, to be selectively imparted to the printed matter. Therefore, compared to the technology of Patent Document 1, for example, the tactile sensation of the printed matter can be suitably controlled. Effect of the Invention

[0008] According to the inkjet printer of the present invention, the feel of the printed matter can be controlled. [Brief description of the drawings]

[0009] [Figure 1] 1 is a front view of an inkjet printer according to an embodiment of the present invention; [Diagram 2] FIG. 2 is an enlarged view of the carriage of FIG. [Diagram 3] 2 is a functional block diagram illustrating a configuration of a control unit in FIG. 1. [Figure 4] FIG. 13 is a schematic perspective view illustrating an example of a protruding portion having a plurality of protrusions. [Diagram 5] FIG. 5 is a schematic side view of the protrusion of FIG. 4. [Figure 6] (A) is a laser microscope image, and (B) is a cross-sectional profile along L1-L1 of (A). [Figure 7](A) is a laser microscope image, and (B) is a cross-sectional profile along L2-L2 of (A). [Figure 8] (A) is a laser microscope image, and (B) is a cross-sectional profile along L3-L3 of (A). [Figure 9] (A) is a laser microscope image, and (B) is a cross-sectional profile along L4-L4 in (A). [Figure 10] (A) is a laser microscope image, and (B) is a cross-sectional profile along L5-L5 in (A). [Figure 11] (A) is a laser microscope image, and (B) is a cross-sectional profile along L6-L6 in (A). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An inkjet printer according to an embodiment of the present invention will be described below with reference to the drawings. It should be noted that the embodiment described here is not intended to limit the present invention in any particular way. Also, the same reference numerals are used for members and parts that perform the same function, and duplicated descriptions are omitted or simplified as appropriate. Also, in this specification, the expression "A to B" (A and B are arbitrary numerical values) indicating a range includes the meaning of "A or more and B or less," as well as "preferably greater than A" and "preferably smaller than B."

[0011] In this specification, the term "inkjet printer" refers to printers in general that use printing methods using conventionally known inkjet technology, for example, continuous methods such as binary deflection methods or continuous deflection methods, thermal methods, or on-demand methods such as piezoelectric methods. Also, the term "printer" includes 2D printers that print two-dimensional images, and 3D printers (three-dimensional modeling devices) that create three-dimensional objects.

[0012] FIG. 1 is a front view of an inkjet printer (hereinafter, sometimes simply referred to as a "printer") 10. The printer 10 is a 2D printer. In the following description, left, right, top, and bottom refer to the left, right, top, and bottom as seen from a user (a user of the printer 10) in front of the printer 10, and the side of the printer 10 approaching the user is the front, and the side moving away from the user is the rear. In addition, the symbols F, Rr, L, R, U, and D in the drawings represent the front, rear, left, right, top, and bottom, respectively, and the symbols X, Y, and Z in the drawings represent the front-rear direction (sub-scanning direction), the left-right direction (main scanning direction), and the up-down direction. In addition, the up-down direction is an example of the height direction of the recording medium 2 and the protrusion 3 (see FIG. 4). However, these are merely defined for the convenience of explanation, and do not limit the installation mode of the printer 10 in any way.

[0013] The printer 10 is a photocurable printer that prints an image or the like on a recording medium 2 using photocurable ink. In this specification, the term "photocurable printer" refers to a printing device in general that forms an image by irradiating electromagnetic waves (light in a broad sense) including ultraviolet rays, X-rays, visible light, infrared rays, etc., from a light source to cure the photocurable ink on the recording medium 2. In this specification, the term "image" refers to an image formed on the recording medium 2, and the content thereof is not particularly limited. Images include characters, numbers, symbols, figures, pictures, patterns, etc. In addition, the recording medium 2 is an object on which an image is printed, and the shape and material thereof are not particularly limited. The recording medium 2 may be, for example, paper such as plain paper, inkjet printing paper, transfer paper, or card, or may be a sheet made of resin such as polyvinyl chloride (PVC), polyethylene terephthalate, or polyester, a plate made of various materials such as aluminum, iron, stainless steel, wood, glass, or rubber, a cloth such as a woven cloth or a nonwoven cloth, leather, or other medium.

[0014] The printer 10 is a so-called flatbed type printer. The printer 10 is formed in a box shape extending in the left-right direction Y. The printer 10 includes a casing 12 having an opening 11, and a front cover 13 that covers the opening 11 in an openable and closable manner. When the front cover 13 is opened upward around the rear end of the front cover 13, the internal space of the casing 12 communicates with the external space. Note that FIG. 1 shows the front cover 13 in an open state.

[0015] The printer 10 includes a table 20, a carriage 30, a carriage moving mechanism 31, an ink head 40 (see FIG. 2), ink tanks 41 and 42, a light irradiation device 50 (see FIG. 2), and a control unit 60 (see also FIG. 3).

[0016] The table 20 is disposed in the internal space of the casing 12. The table 20 is a platform on which the recording medium 2 is placed. The table 20 is provided below the carriage 30. Here, the table 20 is a rectangular member. The table 20 is configured to be movable in the front-rear direction X and the up-down direction Z by a table movement mechanism (not shown).

[0017] The carriage 30 is disposed in the internal space of the casing 12. The carriage 30 is provided above the table 20. The carriage 30 is configured to be movable in the left-right direction Y by a carriage movement mechanism 31, which will be described later. FIG. 2 is an enlarged view of the carriage 30. As shown in FIG. 2, an ink head 40 and a light irradiation device 50 are mounted on the carriage 30. In this embodiment, the ink head 40 and the light irradiation device 50 move integrally with the carriage 30 in the left-right direction Y.

[0018] The carriage movement mechanism 31 is a mechanism for moving the carriage 30 in the left-right direction Y. As shown in FIG. 1, the carriage movement mechanism 31 includes a guide rail 32, a belt (not shown), left and right pulleys (not shown), and a left-right movement motor 33 (see FIG. 3). The guide rail 32 is fixed to the casing 12 and extends in the left-right direction Y. The guide rail 32 is provided above the table 20. The carriage 30 is slidably engaged with the guide rail 32. The guide rail 32 guides the movement of the carriage 30 in the left-right direction Y. An endless belt is fixed to the carriage 30. The belt is wound around pulleys arranged on the left and right of the guide rail 32. A left-right movement motor 33 is attached to one of the pulleys. The left-right movement motor 33 is electrically connected to the control unit 60 and is controlled by the control unit 60. When the left-right movement motor 33 is driven, the pulley rotates and the belt runs. As a result, the carriage 30 moves in the left-right direction Y along the guide rails 32. However, the mechanism described here is merely an example, and the configuration of the carriage moving mechanism 31 is not particularly limited.

[0019] The ink head 40 ejects droplets of photocurable ink toward the recording medium 2. As shown in FIG. 2, the ink head 40 is provided on the carriage 30. The number of ink heads 40 is six here. The six ink heads 40 are arranged in a so-called in-line arrangement here. However, the number and arrangement of the ink heads 40 are merely an example and are not particularly limited. The ink head 40 has nozzles 40N that eject photocurable ink on the surface (here, the lower surface) facing the recording medium 2. The ink head 40 is electrically connected to the control unit 60. The control unit 60 stores a plurality of pulse waveforms (driving pulses) for causing the ink head 40 to eject a predetermined amount of ink. The amount of droplets ejected from the nozzles 40N is adjusted by the driving pulses supplied to the ink head 40. The ink head 40 is connected to the ink tanks 41 and 42, respectively, by flexible ink tubes (not shown).

[0020] The ink tanks 41 and 42 are containers that store photocurable ink. The ink tanks 41 and 42 are not mounted on the carriage 30, but are placed stationary in the internal space of the casing 12. The ink tanks 41 and 42 are, for example, ink cartridges. The ink tanks 41 and 42 each store ultraviolet curable ink (UV ink) that has the property of being cured when irradiated with ultraviolet light (wavelength: 10 to 400 nm).

[0021] Here, there are five ink tanks 41. Each ink tank 41 stores a colored light-curable ink (colored ink). The five ink tanks 41 store, for example, process color inks (CMYK) of cyan ink, magenta ink, yellow ink, and black ink, and white ink. Here, there is one ink tank 42. The ink tank 42 stores a transparent light-curable ink (clear ink). However, the number of ink tanks 41 and 42 and the type of ink are merely examples and are not particularly limited. In this specification, "clear ink" refers to ink that does not contain a colorant (a component that absorbs light with wavelengths in the visible light region) or contains a colorant to a degree that is not intended for coloring (for example, the colorant is about 0.1 mass % or less of the entire ink), and "colored ink" refers to all inks other than clear ink, typically all inks that contain a colorant.

[0022] The light irradiation device 50 is a device that irradiates light to droplets of the photocurable ink discharged onto the recording medium 2 to cure the photocurable ink. As shown in FIG. 2, the light irradiation device 50 is provided on the carriage 30. Here, the number of the light irradiation devices 50 is two. Here, the two light irradiation devices 50 are arranged so as to sandwich the ink head 40 from both the left and right ends. However, the number and arrangement of the light irradiation devices 50 are merely an example and are not particularly limited. Here, the light irradiation device 50 is an ultraviolet lamp (UV lamp) that irradiates ultraviolet light. The light irradiation device 50 is, for example, an LED (Light Emitting Diode) lamp. The light irradiation device 50 is electrically connected to the control unit 60. The light irradiation device 50 is turned on and off by the control unit 60.

[0023] The control unit 60 controls the overall operation of the printer 10. In this embodiment, the control unit 60 is a computer dedicated to the printer 10 and disposed inside the casing 12. The control unit 60 is, for example, a microcomputer. However, some or all of the functions of the control unit 60 may be executed by a general-purpose personal computer or the like that is disposed outside the casing 12 and communicably connected to the printer 10 via wire or wirelessly.

[0024] The hardware configuration of the control unit 60 is not particularly limited, but may include, for example, an interface (I / F) for receiving print data and the like from an external device such as a host computer, a central processing unit (CPU) for executing instructions of a control program, a read only memory (ROM) that stores the program executed by the CPU, a random access memory (RAM) used as a working area for expanding the program, and a storage device such as a memory for storing the above-mentioned program and various data.

[0025] FIG. 3 is a functional block diagram of the control unit 60. As shown in FIG. 3, the control unit 60 is connected to the left-right movement motor 33 of the carriage movement mechanism 31, the ink head 40, and the light irradiation device 50 in a communicable manner, and is configured to control them. In this embodiment, the control unit 60 includes a print signal receiving unit 61, an image formation control unit 62, and a tactile sensation imparting control unit 63. However, the image formation control unit 62 is not essential and can be omitted in other embodiments. Each unit of the control unit 60 is configured to be able to communicate with each other. Each unit of the control unit 60 may be configured by software or hardware. Each unit of the control unit 60 may be realized by one or more processors, or may be incorporated into a circuit.

[0026] The print signal receiving unit 61 is a control unit that receives print data from an external device (not shown), such as a host computer. The print data is, for example, data in a raster format. The print data includes at least data (protrusion formation data) representing protrusions 3 (see FIG. 4) to be printed on the recording medium 2. The print data further includes data (image formation data) representing an image to be printed on the recording medium 2.

[0027] The image formation control unit 62 is a control unit for forming a desired image on the recording medium 2. The image formation control unit 62 is a control unit that executes an image forming operation for forming an image on the recording medium 2 on the table 20 based on the image formation data received by the print signal receiving unit 61. The image formation control unit 62 controls the left-right movement motor 33 of the carriage moving mechanism 31 to move the carriage 30 in the left-right direction Y. The image formation control unit 62 controls the ink head 40 to eject droplets of photocurable ink toward the recording medium 2. The image formation control unit 62 ejects droplets of, for example, colored ink. The image formation control unit 62 controls the light irradiation device 50 after ejecting the photocurable ink from the ink head 40 to irradiate light toward the photocurable ink on the recording medium 2.

[0028] The tactile sensation imparting control unit 63 is a control unit for imparting a desired tactile sensation onto the recording medium 2. The tactile sensation imparting control unit 63 is a control unit for executing a protrusion forming operation for forming one or more protrusions 3 (see FIG. 4) on the recording medium 2 on the table 20 based on the protrusion forming data received by the print signal receiving unit 61. The tactile sensation imparting control unit 63 controls the left-right movement motor 33 of the carriage moving mechanism 31 to move the carriage 30 in the left-right direction Y. The tactile sensation imparting control unit 63 controls the ink head 40 to eject a predetermined amount of droplets of photocurable ink toward the recording medium 2. The tactile sensation imparting control unit 63 ejects, for example, droplets of clear ink. The tactile sensation imparting control unit 63 controls the light irradiation device 50 after ejecting the photocurable ink from the ink head 40 to irradiate light toward the photocurable ink on the recording medium 2 at a predetermined timing. The tactile sensation imparting control unit 63 may be configured to form a plurality of protrusions 3. The tactile sensation imparting control unit 63 may be configured to form the protrusions 3 on the image after the image formation control unit 62 executes the image forming operation and an image is formed on the recording medium 2.

[0029] The tactile sensation imparting control unit 63 is configured to form protrusions 3 (see FIG. 4) having a predetermined size and / or predetermined surface roughness on the recording medium 2 by controlling the amount of photocurable ink ejected from the nozzles 40N of the ink head 40 and the timing of light irradiation from the light irradiation device 50. By adjusting the size and / or surface roughness of the protrusions 3 to be formed, the tactile sensation of the surface of the printed matter can be suitably controlled.

[0030] The size of the protrusion 3 is adjusted so as to realize a desired tactile sensation. For this reason, although not particularly limited, the tactile sensation imparting control unit 63 may be configured to form the protrusion 3 so that the diameter D of the protrusion 3 is approximately 10 μm or more, for example 50 μm or more, preferably 100 μm or more, and approximately 2000 μm or less, preferably 1000 μm or less, more preferably 500 μm or less. The tactile sensation imparting control unit 63 may also be configured to form the protrusion 3 so that the height H of the protrusion 3 (maximum height, average height in the case of multiple protrusions 3) is typically the diameter D or less, for example 1 μm or more, for example 10 μm or more, preferably 20 μm or more, and approximately 500 μm or less, for example 200 μm or less, preferably 100 μm or less. The ratio (D / H) of the diameter D to the height H of the protrusion 3 may be approximately 1 or more, for example 2 or more, 5 or more, and approximately 50 or less, for example 25 or less. By satisfying at least one of the above conditions, the protrusions 3 can be raised three-dimensionally, effectively improving the tactile sensation when touching the printed matter. The size of the protrusions 3 can be determined, for example, from an observation image of the side or cross section of the printed matter.

[0031] FIG. 4 is a perspective view of a protrusion portion 4 having a plurality of protrusions 3. FIG. 5 is a side view of the protrusions 3 as viewed from the direction of the arrow. As shown in FIG. 4, in the protrusion portion 4, a plurality of protrusions 3 having the same shape are regularly arranged on the recording medium 2 at a predetermined pitch P. The protrusions 3 are substantially circular in plan view. As shown in FIG. 5, the protrusions 3 are dome-shaped in side view. FIG. 5 shows the protrusions 3 consisting of droplets of 20 pl. The diameter d0 of one droplet (20 pl) is 50 μm here, and the height h0 of one droplet (20 pl) is 10 μm here. The diameter D of the protrusions 3 is 100 μm here, and the height H of the protrusions 3 is 50 μm here. The distance (pitch P) between two adjacent protrusions 3 is 100 μm here. The pitch P is preferably equal to or greater than the diameter D, and may be, for example, 100 to 1000 μm.

[0032] The surface roughness of the protrusions 3 is adjusted so as to realize a desired tactile sensation. According to the study by the present inventors, from the viewpoint of favorably controlling the tactile sensation, it is preferable to adjust at least one (preferably both) of the "arithmetic mean height Wa of the waviness curve" and / or the "arithmetic mean height Ra of the roughness profile" as the surface roughness. The "arithmetic mean height Wa of the waviness curve" represents the unevenness of the surface of the protrusions 3 (large unevenness, in other words, large surface roughness), and the "arithmetic mean height Ra of the roughness curve" represents the roughness of the surface of the printed matter (fine unevenness of the surface, in other words, small surface roughness). These surface roughnesses can be obtained from the cross-sectional profile (primary profile) at the reference length L based on JIS-B0601:2001. The cross-sectional profile can be measured, for example, by a laser microscope.

[0033] In this specification, the "arithmetic mean height Wa of the waviness curve" refers to the average of absolute values ​​at a reference length L (0.8 mm) in a "waviness curve" obtained by applying a profile curve filter with a cutoff value λc (25 μm) to the cross-sectional profile to remove surface roughness components with wavelengths shorter than λc from the cross-sectional profile. In addition, in the calculation of the arithmetic mean height Wa, a filter with a cutoff value λf is not applied in order to take into account all large irregularities other than fine irregularities. In addition, in this specification, the "arithmetic mean height Ra of the roughness curve" refers to the average of absolute values ​​at a reference length L (0.8 mm) in a "roughness curve" obtained by applying a high-pass filter with a cutoff value λc (25 μm) to the cross-sectional profile to remove surface roughness components with wavelengths longer than λc from the cross-sectional profile.

[0034] In this embodiment, the tactile sensation imparting control unit 63 includes two control units that impart different tactile sensations onto the recording medium 2, namely, a first tactile sensation imparting control unit 81 and a second tactile sensation imparting control unit 82. However, in other embodiments, either one of them may be omitted.

[0035] The first tactile sensation imparting control unit 81 is a control unit for imparting a rough tactile sensation onto the recording medium 2. The first tactile sensation imparting control unit 81 may be a control unit for forming, on the recording medium 2, protrusions 3 or protrusions 4 having a surface roughness (unevenness) greater than that of the recording medium 2. In this specification, "having a surface roughness greater than that of the recording medium 2" means that at least one (preferably both) of the arithmetic mean height Wa in the reference length of the waviness curve and the arithmetic mean height Ra in the reference length of the roughness curve is greater than that of the recording medium 2.

[0036] Although not particularly limited, the first tactile sensation imparting control unit 81 may be configured to form the protrusions 3 having an arithmetic mean height Wa of the undulation curve of 3.0 μm or more, preferably 5.0 μm or more, more preferably 10.0 μm or more, and approximately 100 μm or less, for example, 50 μm or less, 30 μm or less, or 20 μm or less. The first tactile sensation imparting control unit 81 may also be configured to form the protrusions 3 having an arithmetic mean height Ra of the roughness curve of 0.2 μm or more, and for example, 10 μm or less, or 1 μm or less. The ratio of Wa to Ra (Wa / Ra) may be approximately 10 or more, for example, 20 or more, 30 or more, and approximately 100 or less, for example, 80 or less, 70 or less. By setting Wa and / or Ra to a predetermined value or more, the protrusions 3 can be raised three-dimensionally, and a significantly rough tactile sensation can be realized. By setting Wa and / or Ra to a predetermined value or less, the protrusions 3 can be formed stably and quickly, and printing throughput can be improved.

[0037] In order to achieve a rough tactile sensation, the first tactile sensation imparting control unit 81 may be configured to irradiate light immediately after the droplets discharged from the nozzles 40N land on the recording medium 2. For example, the first tactile sensation imparting control unit 81 may be configured to irradiate light simultaneously with the droplets landing on the recording medium 2, or within approximately 500 ms, preferably within 100 ms, for example within 50 ms, after the droplets land on the recording medium 2. This makes it possible to suitably form protrusions 3 having the above-mentioned size and / or surface roughness.

[0038] The second tactile sensation imparting control unit 82 is a control unit for imparting a smooth tactile sensation onto the recording medium 2. The second tactile sensation imparting control unit 82 may be a control unit for forming, on the recording medium 2, protrusions 3 or protrusions 4 having a smaller surface roughness (unevenness) than the recording medium 2. In this specification, "having a smaller surface roughness than the recording medium 2" means that at least one (preferably both) of the arithmetic mean height Wa of the waviness curve and the arithmetic mean height Ra of the roughness curve is smaller than that of the recording medium 2.

[0039] Although not particularly limited, the second tactile sensation imparting control unit 82 may be configured to form protrusions 3 having an arithmetic mean height Wa of the undulation curve less than 3.0 μm, preferably 1.0 μm or less, more preferably 0.5 μm or less, for example, a measurement lower limit or less. The second tactile sensation imparting control unit 82 may also be configured to form protrusions 3 having an arithmetic mean height Ra of the roughness curve greater than approximately 0.02 μm, preferably 0.05 μm or more, and approximately 0.5 μm or less, preferably less than 0.2 μm, for example, 0.1 μm or less. By setting Wa and / or Ra to a predetermined value or more, a solid tactile sensation can be realized. By setting Wa and / or Ra to a predetermined value or less, a significantly smooth tactile sensation can be realized.

[0040] In order to realize a smooth tactile sensation, the first tactile sensation imparting control unit 81 may be configured to irradiate light a while after the droplets discharged from the nozzle 40N land on the recording medium 2. For example, the first tactile sensation imparting control unit 81 may be configured to irradiate light at a timing when a time has elapsed that is approximately 700 ms or more, preferably 1000 ms or more, for example 2000 ms or more or 5000 ms or more, and approximately 20000 ms or less, preferably 10000 ms or less, for example 7000 ms or less, after the droplets land on the recording medium 2. This makes it possible to suitably form the protrusions 3 having the above-mentioned size and / or surface roughness.

[0041] The tactile sensation imparting control unit 63 may be configured to form the protrusion 3 by discharging a droplet from the nozzle 40N once, or may be configured to form the protrusion 3 by discharging droplets multiple times and merging the droplets in flight or landing them at approximately the same position on the recording medium 2. The tactile sensation imparting control unit 63 may be configured to scan the carriage 30 multiple times in the left-right direction Y over the same printing area of ​​the recording medium 2, forming the protrusion 3 by a so-called multi-pass method. The tactile sensation imparting control unit 63 may be configured to set the discharge amount per droplet (unit droplet) to approximately 1 pl or more, for example 5 pl or more, preferably 10 pl or more, and approximately 100 pl or less, for example 50 pl or less, preferably 40 pl or less. This allows the protrusion 3 to be formed stably and accurately.

[0042] The tactile sensation imparting control unit 63 is preferably configured to set the discharge amount per one protrusion 3 (unit protrusion) to approximately 100pl or more, for example 200pl or more, preferably 500pl or more, and approximately 50,000pl or less, for example 20,000pl or less, preferably 10,000pl or less. By setting the discharge amount of droplets per unit protrusion to a predetermined value or more, a definite tactile sensation can be imparted to the printed matter. In addition, it is possible to prevent adjacent protrusions 3 from being too close to each other. In addition, it is possible to suitably form protrusions 3 having the above-mentioned size and / or surface roughness.

[0043] As described above, the printer 10 can selectively impart a desired texture, such as a rough texture or a smooth texture, to the printed matter by forming the protrusions 3 in desired portions on the recording medium 2. This allows the texture of the printed matter to be suitably controlled.

[0044] In this embodiment, the tactile sensation imparting control unit 63 determines whether the surface roughness satisfies the following conditions: the arithmetic mean height Wa of the waviness curve based on JIS-B0601:2001 is 3.0 μm≦Wa; the arithmetic mean height Ra of the roughness curve based on JIS-B0601:2001 is 0.2 μm ≦It includes a first tactile sensation imparting control unit 81 configured to form protrusions 3 each having Ra; etc., whereby a rough tactile sensation can be imparted prominently on the recording medium 2.

[0045] In this embodiment, the first tactile sensation imparting control unit 81 is configured to irradiate light within 100 ms after the droplets ejected from the nozzle 40N land on the recording medium 2. Thereby, the protrusions 3 having the surface roughness as described above can be preferably formed.

[0046] In this embodiment, the tactile sensation imparting control unit 63 includes a second tactile sensation imparting control unit 82 configured to form protrusions 3 each having the following conditions: the arithmetic mean height Wa of the waviness curve based on JIS - B0601:2001 is Wa < 3.0 μm; the arithmetic mean height Ra of the roughness curve based on JIS - B0601:2001 is 0.02 μm < Ra < 0.2 μm. Thereby, a smooth tactile sensation can be imparted prominently on the recording medium 2.

[0047] In this embodiment, the second tactile sensation imparting control unit 82 is configured to irradiate light after a time of 1000 ms or more and 10000 ms or less has elapsed after the droplets ejected from the nozzle 40N land on the recording medium 2. Thereby, the protrusions 3 having the surface roughness as described above can be preferably formed.

[0048] In this embodiment, the tactile sensation imparting control unit 63 is configured such that the ejection amount of droplets per unit protrusion is 500 pl or more and 10000 pl or less. Thereby, a definite tactile sensation can be imparted to the printed matter.

[0049] In this embodiment, the tactile sensation imparting control unit 63 is configured such that the ejection amount of droplets per unit droplet is 10 pl or more and 40 pl or less. Thereby, the protrusions 3 can be formed stably and speedily, and the printing throughput can be improved.

[0050] In this embodiment, the tactile sensation imparting control unit 63 is configured to form the protrusions 3 whose sizes satisfy all of the following conditions: diameter D: 100 μm≦D≦1000 μm; height H: 20 μm≦H≦100 μm. This effectively enhances the tactile sensation felt when touching the printed matter.

[0051] Test examples relating to the present invention will be described below, but it is not intended that the present invention be limited to those shown in the following test examples.

[0052] <Test I - Examination of rough texture> Using the printer 1 equipped with the tactile sensation imparting control unit 63 as described above, multiple protrusions as shown in FIG. 4 were formed on the surface of the recording medium. In Example 1, the amount of droplets discharged from the nozzle at one time (discharge amount per unit droplet) was 20 pl, and the discharge amount of droplets per protrusion was 1000 pl. In addition, UV light was irradiated from the light irradiation device within 100 ms (about 50 ms) after the droplets landed on the recording medium. In Comparative Example 1, the discharge amount per unit droplet was made smaller than that of Example 1 to form multiple protrusions. In Reference Example 1, normal printing (color printing) was performed by the image formation control unit 62 of the printer 1. Then, the multiple protrusions were observed with a non-contact 3D measuring laser microscope, and a cross-sectional profile was obtained based on the obtained observation image. In addition, the surface roughness was obtained based on the cross-sectional profile by the above-mentioned method. The results are shown in FIGS. 6 to 8 and Table 1.

[0053] First, a sensory test of the feel was performed by touching a number of protrusions. The results are shown in Table 1. In Table 1, when a hand is moved over the recording medium, the presence of the protrusions is felt and the surface roughness is strongly felt in comparison with Reference Example 1 (normal printing) as a reference, and "Present (rough)" is indicated. When the presence of the protrusions is felt in comparison with Reference Example 1 but the surface roughness is not felt, "Present (smooth)" is indicated. When the presence of the protrusions is not felt in comparison with Reference Example 1, "Absent" is indicated. As shown in Table 1, by satisfying 3.0 μm≦Wa (for example, 5.0 μm or more, 10.0 μm or more), and preferably further satisfying 0.2 μm≦Ra, a rough feel can be suitably imparted to the recording medium.

[0054] Next, the surface of the recording medium was visually inspected, and the visual change (desire to touch) of the image formed by the colored ink formed by forming a plurality of protrusions was confirmed. The results are shown in Table 1. In Table 1, when the visual change is large with respect to Reference Example 1 (normal printing) as a reference, it is indicated as "present", and when the visual change is small, it is indicated as "absent". As shown in Table 1, by setting Wa and / or Ra within the above ranges, a rough tactile sensation could be suitably imparted to the recording medium, and the appearance could be kept equivalent to normal printing.

[0055]

Table 1

[0056] <Examination of Smooth Tactile Sensation - Test II> In Example 2, a plurality of protrusions were formed in the same manner as in Example 1, except that UV light was irradiated from a light irradiation device 1000 to 10000 ms after the droplets landed on the recording medium 2. In Comparative Example 2, the discharge amount per unit droplet was made smaller than that in Example 2, and a plurality of protrusions were formed. In Comparative Example 3, the timing of irradiation with UV light was made earlier than that in Example 2, and a plurality of protrusions were formed. Then, a sensory test of the tactile sensation and confirmation of the visual change (desire to touch) were performed in the same manner as in Test I. The results are shown in FIGS. 9 to 11 and Table 1.

[0057] As shown in Table 1, by satisfying 0.02 μm < Ra < 0.2 μm, and preferably further satisfying Wa < 3.0 μm (for example, 1.0 μm or less, 0.5 μm or less), a smooth tactile sensation could be suitably imparted to the recording medium.

[0058] The preferred embodiments of the present invention have been described above. However, the above-described embodiments are merely examples, and the present invention can be implemented in various other forms.

[0059] For example, the protrusions 3 and the rough or smooth texture of their surface can be formed directly on (the surface of) the recording medium 2 by the tactile sensation imparting control unit 63 executing the protrusion forming operation, or can be formed indirectly on the recording medium 2. As an example, the tactile sensation imparting control unit 63 may directly form the protrusions 3 and the rough or smooth texture of their surface on the recording medium 2 using clear ink (or colored ink). That is, only the texture may be imparted on the recording medium 2. As another example, the protrusions 3 and the rough or smooth texture of their surface can be formed superimposed on an image formed on the recording medium 2. For example, the image forming control unit 62 may execute an image forming operation (i.e., normal printing without protrusions) using colored ink to form a color image on the recording medium 2, and the tactile sensation imparting control unit 63 may execute a protrusion forming operation using clear ink (or colored ink) to form the protrusions 3 and the rough or smooth texture of their surface on the color image.

[0060] In the above embodiment, the carriage 30 is configured to move in the left-right direction Y, and the recording medium 2 is configured to move in the front-rear direction X, but this is not limited to the above. The movements of the carriage 30 and the recording medium 2 are relative, and either one may move in the left-right direction Y or the front-rear direction X. For example, the recording medium 2 may be arranged so as to be immovable, and the carriage 30 may be configured to be movable in both the left-right direction Y and the front-rear direction X. Also, both the carriage 30 and the recording medium 2 may be configured to be movable in both directions.

[0061] In the above embodiment, a so-called shuttle type (serial type) printer 10 has been described in which the ink head 40 is mounted on the carriage 30 and printing is performed while moving back and forth (shuttle movement) in the left-right direction Y, but the present invention is not limited to this. The technology disclosed herein can also be similarly applied to a so-called line type printer, which is provided with a line head having the same width as the recording medium 2 and performs printing with the line head fixed.

[0062] Furthermore, the technology disclosed herein can be applied to various types of inkjet printers. For example, in addition to the flatbed type shown in the above embodiment, the technology can also be applied to so-called roll-to-roll type printers that transport a roll-shaped recording medium. Furthermore, the printer 10 is not limited to being used alone as an independent printer, but may be combined with other devices. For example, the printer 10 may be equipped with a cutting device or the like, or may be built into other devices. [Explanation of symbols]

[0063] 1. Printer (inkjet printer) 20 Tables 40 Ink Head 40N Nozzle 50 Light irradiation device 60 Control section 63 Tactile sensation control unit 81 First tactile sensation providing control unit 82 Second tactile sensation providing control unit

Claims

1. an ink head having nozzles for ejecting droplets of a photocurable ink toward a recording medium; a light irradiation device that irradiates light onto the droplets discharged onto the recording medium; A control unit that controls the ink head and the light irradiation device; Equipped with the control unit includes a tactile sensation imparting control unit configured to form protrusions having a predetermined surface roughness on the recording medium by controlling an amount of the photocurable ink ejected from the nozzles and a timing of irradiating the light from the light irradiation device, thereby imparting a tactile sensation to the recording medium; The tactile sensation imparting control unit is configured to have the surface roughness satisfy the following conditions: The arithmetic mean height Wa of the waviness curve based on JIS-B0601:2001 is 3.0 μm≦Wa; The arithmetic mean height Ra of the roughness curve based on JIS-B0601:2001 is 0.2 μm≦Ra; an inkjet printer comprising a first tactile sensation imparting control unit configured to form the protrusion having any one of the above features.

2. The tactile sensation imparting control unit is configured to: The arithmetic mean height Wa of the waviness curve based on JIS-B0601:2001 is Wa<3.0 μm; The arithmetic mean height Ra of the roughness curve based on JIS-B0601:2001 is 0.02 μm<Ra<0.2 μm; and a second tactile sensation providing control unit configured to form the protrusion, 2. The inkjet printer according to claim 1.

3. An ink head having a nozzle for ejecting droplets of a photocurable ink toward a recording medium; a light irradiation device that irradiates light onto the droplets discharged onto the recording medium; A control unit that controls the ink head and the light irradiation device; Equipped with the control unit includes a tactile sensation imparting control unit configured to form protrusions having a predetermined surface roughness on the recording medium by controlling an amount of the photocurable ink ejected from the nozzles and a timing of irradiating the light from the light irradiation device, thereby imparting a tactile sensation to the recording medium; The tactile sensation imparting control unit is configured to have the surface roughness satisfy the following conditions: The arithmetic mean height Wa of the waviness curve based on JIS-B0601:2001 is Wa<3.0 μm; The arithmetic mean height Ra of the roughness curve based on JIS-B0601:2001 is 0.02 μm<Ra<0.2 μm; and a second tactile sensation imparting control portion configured to form the protrusion having any of the above features.

4. the second tactile sensation imparting control unit is configured to irradiate the light after a time period of 1000 ms to 10000 ms has elapsed since the droplets discharged from the nozzles land on the recording medium.

4. The inkjet printer according to claim 3.

5. An ink head having a nozzle for ejecting droplets of a photocurable ink toward a recording medium; a light irradiation device that irradiates light onto the droplets discharged onto the recording medium; A control unit that controls the ink head and the light irradiation device; Equipped with the control unit includes a tactile sensation imparting control unit configured to form protrusions having a predetermined size and / or a predetermined surface roughness on the recording medium by controlling an ejection amount of the photocurable ink ejected from the nozzle and a timing of the irradiation of the light from the light irradiation device, thereby imparting a tactile sensation to the recording medium; The inkjet printer, wherein the tactile sensation imparting control section is configured to set the amount of the photocurable ink ejected per unit protrusion to be 500 pl or more and 10,000 pl or less.

6. An ink head having a nozzle for ejecting droplets of a photocurable ink toward a recording medium; a light irradiation device that irradiates light onto the droplets discharged onto the recording medium; A control unit that controls the ink head and the light irradiation device; Equipped with the control unit includes a tactile sensation imparting control unit configured to form protrusions having a predetermined size on the recording medium by controlling an amount of the photocurable ink ejected from the nozzle and a timing of irradiating the light from the light irradiation device, thereby imparting a tactile sensation to the recording medium; The tactile sensation providing control unit is configured to have a size that satisfies the following conditions: Diameter D is 100 μm≦D≦1000 μm; The height H is 20 μm≦H≦100 μm; and forming the protrusions comprising:

7. the first tactile sensation imparting control unit is configured to irradiate the droplets with the light within 100 ms after the droplets discharged from the nozzles land on the recording medium; 3. The inkjet printer according to claim 1 or 2.

8. the tactile sensation imparting control unit is configured to set the ejection amount of the light curable ink per unit droplet to 10 pl or more and 40 pl or less; 8. The inkjet printer according to claim 1.

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