Printing apparatus

Abstract

To provide a printing device that is able to prevent occurrence of a void portion.SOLUTION: A printing device comprises: an ejection head that ejects onto a printing medium at least one of an ultraviolet curable printing ink, a base layer ink for forming a base layer, and a protective layer ink for forming a protective layer; an acquisition unit that acquires information on a shape of the printing medium; and a controller. The controller performs an ink amount increasing process in which, based on the information on the shape of the printing medium acquired by the acquisition unit, an ejection operation of the ejection head is controlled such that an amount of ink per unit area is increased in a ridge existing region including a ridge that is a boundary between one printing surface and the other printing surface adjacent to each other on the printing medium, compared to that in regions other than the ridge existing region.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a printing apparatus such as an inkjet printer.

Background Art

[0002] Patent Document 1 discloses a printing apparatus including an undercoat agent discharge head unit that discharges an undercoat agent to be applied to the surface of a printing medium before image formation, and a topcoat agent discharge head unit that discharges a topcoat agent to be applied to the surface of the printing medium after image formation. The undercoat agent is applied before an ink discharge unit prints a desired image on the printing medium. As the undercoat agent, a primer for improving the fixing property of ink to the printing medium, a base coloring paint such as a white paint and white ink for creating a base for hiding the color of the material, or a mixture of a primer and a base coloring paint is used. Further, the topcoat agent is applied after an ink discharge unit prints a desired image on the printing medium. The topcoat agent is used to form a transparent coating film having water resistance and weather resistance to protect the printed image.

[0003] In the above printing apparatus, a larger amount of the coating agent is discharged by the coating agent discharge unit to the convex portions on the surface of the printing medium than to the concave portions on the surface of the printing medium. It is said that the coating agent discharge unit may change the discharge amount according to the angle of the inclined surface of the printing medium with respect to the horizontal plane.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, printing is sometimes performed on areas of a printing medium that include the ridge line, which is the boundary between two adjacent printing surfaces. However, in the conventional techniques described above, when printing is performed on areas that include ridge lines, there is a problem in which white areas appear in the printed image in those areas due to misalignment of the ink droplet landing positions. As a result, there have been problems with the quality of the print result and ink peeling due to the aforementioned area of ​​the printing medium coming into contact with the outside.

[0006] Therefore, the present invention aims to provide a printing apparatus that can suppress the occurrence of white areas. [Means for solving the problem]

[0007] The printing apparatus according to the present invention comprises a discharge head that discharges at least one of the following inks onto a printing medium: an ultraviolet-curable printing ink, an underlayer ink for forming an underlayer, and a protective layer ink for forming a protective layer; an acquisition unit that acquires information about the shape of the printing medium; and a controller. The controller performs an ink quantity increase process based on the information about the shape of the printing medium acquired by the acquisition unit, controlling the discharge operation of the discharge head to increase the amount of ink per unit area in the region containing an underlayer edge, which includes an underlayer edge that is the boundary between two adjacent printing surfaces on the printing medium, compared to the region outside the underlayer edge region.

[0008] According to the present invention, in the ink amount increase process, the amount of ink per unit area is increased in the area where the ridge line exists compared to the area outside the ridge line. This makes it possible to suppress or prevent the appearance of white areas in the printed image in the ridge line area due to misalignment of the ink droplet landing position. This improves the quality of the print result and further suppresses ink peeling when the ridge line area of ​​the printing medium comes into contact with the outside. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a printing apparatus that can suppress the occurrence of white areas. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing a printing apparatus according to one embodiment of the present invention. [Figure 2] Figure 1 is a plan view showing the droplet ejection device in the printing apparatus. [Figure 3] Figure 1 is a cross-sectional view showing the configuration of the discharge head. [Figure 4] This figure shows the light-emitting diode chip in the light source shown in Figure 1. [Figure 5] Figure 1 is a block diagram showing the components of the printing apparatus. [Figure 6] Figure 1 is a perspective view showing the printing medium of the printing apparatus. [Figure 7] This is a perspective view showing the printing medium from a different direction than Figure 6. [Figure 8] This figure shows the underlying layers and protective layers in the region where the ridge exists, and in the region outside the region where the ridge exists. [Figure 9] This diagram illustrates the number of ink droplets ejected in the region where the ridge exists and the number of ink droplets ejected in the region outside the ridge. [Figure 10] This diagram illustrates the size of ink droplets in the region where ridges exist and the size of ink droplets in the region outside the ridge region. [Figure 11] Figure 11A shows the curing state of ink droplets and color ink droplets that constitute the base layer in a conventional case, and Figure 11B shows the curing state of ink droplets and color ink droplets that constitute the base layer in this embodiment. [Figure 12] This block diagram shows the configuration of a printing apparatus according to a modified example of the printing apparatus shown in Figure 1. [Figure 13] This block diagram shows the configuration of a printing apparatus according to a modified example of the printing apparatus shown in Figure 12.

Best Mode for Carrying Out the Invention

[0011] Hereinafter, a printing apparatus according to an embodiment of the present invention will be described with reference to the drawings. The printing apparatus described below is merely one embodiment of the present invention. Therefore, the present invention is not limited to the following embodiments, and additions, deletions, and changes are possible without departing from the spirit of the present invention.

[0012] FIG. 1 is a perspective view showing a printing apparatus 1 according to an embodiment of the present invention. In FIG. 1, directions orthogonal to each other are defined as a first direction Ds, a second direction Df, and a third direction Dz. In the present embodiment, for example, the first direction Ds is the moving direction of a carriage 3 described later, the second direction Df is the conveying direction of a printing medium W (FIG. 6) described later, and the third direction Dz is the vertical direction. In the following description, Ds will be referred to as the moving direction, Df will be referred to as the conveying direction, and Dz will be referred to as the vertical direction.

[0013] As shown in FIG. 1, the printing apparatus 1 of the present embodiment includes a housing 2, an operation key 4, a display unit 5, a platen 6 on which a printing medium W is placed, an upper cover 7, a droplet ejection device 1a (FIG. 2) including a discharge head 10 and a light source 40, and a controller unit 19 (FIG. 5) including a control device 20 (FIG. 5). The discharge head 10 is, for example, an inkjet head that discharges ultraviolet-curable ink droplets. The printing apparatus 1 is, for example, an inkjet printer. In the present embodiment, the control device 20 corresponds to the controller.

[0014] The housing 2 is formed in a box shape. The housing 2 has an opening 2a. The housing 2 is provided with an operation key 4. Further, a display unit 5 is provided near the operation key 4. The operation key 4 receives operation inputs from the user. The display unit 5 is configured, for example, as a touch panel and displays predetermined information. A part of the display unit 5 also functions as an operation key. The controller unit 19 realizes a printing function based on an input from the operation key 4 or an external input via a communication interface (not shown) and controls the display on the display unit 5.

[0015] The platen 6 is configured to be able to place the printing medium W described later. The platen 6 has a predetermined thickness and is formed of, for example, a rectangular plate material with the transport direction Df as the longitudinal direction. The platen 6 is removably supported by a platen support base (not shown). The platen support base is configured to be movable in the transport direction Df between a printing position for performing printing on the printing medium W by driving the transport motor 33 (FIG. 5) and a detachable position for removing the printing medium W from the platen 6. Thereby, the platen 6 relatively moves the printed surface of the printing medium W in the transport direction Df with respect to the ejection head 10. During printing, since the platen 6 moves in the transport direction Df, the printing medium W placed on the platen 6 is transported along the transport direction Df.

[0016] The upper cover 7 is configured to rotate upward when its end is lifted. Thereby, the inside of the housing 2 is exposed.

[0017] As shown in FIG. 2, the droplet ejection device 1a includes a storage tank 62, a carriage 3 on which, for example, two ejection heads 10 (10A, 10B) and two light sources 40 (40A, 40B) are mounted, and a pair of guide rails 67. The ejection head 10 has a plurality of nozzle rows NL arranged in parallel in the moving direction Ds. Although two ejection heads 10 and two light sources 40 are provided, the present invention is not limited thereto, and one ejection head 10 and one light source 40 may be provided.

[0018] The carriage 3 is supported by a pair of guide rails 67 extending in the moving direction Ds and reciprocates in the moving direction Ds along the guide rails 67. Thereby, the two ejection heads 10 (10A, 10B) and the two light sources 40 (40A, 40B) can reciprocate in the moving direction Ds. Further, the ejection head 10 is connected to the storage tank 62 via a tube 62a.

[0019] In this embodiment, for example, the ejection head 10A ejects ink droplets of yellow (Y), magenta (M), cyan (C), and black (K), which are sometimes collectively referred to as color inks. When these four ink droplets are ejected onto the printing medium W, a color image is printed on the printing medium W.

[0020] Meanwhile, the ejection head 10B ejects, for example, droplets of primer ink, white (W) ink, and clear (Cr) ink. When forming the underlayer, primer ink or white ink is used as the underlayer ink. Such underlayer inks are used to improve the adhesion of the color inks or to maintain the shape of the printing medium W. In particular, because primer ink is viscous, it can further improve the adhesion of the color inks. Drops of the underlayer ink are ejected onto the printing medium W first, and then droplets of color ink are ejected on top of these underlayer ink droplets. Clear ink is used as a protective layer ink, and its droplets are ejected when forming a protective layer that protects the printed area.

[0021] The storage tanks 62 store ink. Each storage tank 62 is provided for a different type of ink. For example, there are six storage tanks 62, each storing black, yellow, cyan, magenta, white, and clear ink.

[0022] The droplet dispensing device 1a further includes a purge section 50 and a wipe section 54. The purge section 50 and the wipe section 54 are positioned on one end of a pair of guide rails 67 in the direction of movement Ds, so as to overlap with the movement area of ​​the carriage 3.

[0023] The purging unit 50 includes a cap 51, a suction pump 52, and a lifting mechanism 53. The suction pump 52 is connected to the cap 51. The lifting mechanism 53 raises and lowers the cap 51 between a suction position and a standby position. In the standby position, the discharge surface NM (Figure 3) is separated from the cap 51. On the other hand, in the suction position, the discharge surface NM is covered by the cap 51, forming a sealed space. When the suction pump 52 is driven while the cap 51 is in the suction position, the sealed space is sucked in, and a purging process is performed in which ink is discharged from the nozzle hole 121a (Figure 3), which will be described later.

[0024] The wipe section 54 also has two wipers 55 and 56 and a moving mechanism 57. The two wipers 55 and 56 are supported by the moving mechanism 57. The moving mechanism 57 moves in the transport direction Df with the discharge surface NM positioned facing these wipers 55 and 56. As a result, the two wipers 55 and 56 perform a wiping operation (i.e., wiping the discharge surface NM) while moving in the transport direction Df.

[0025] Next, the detailed structure of the discharge head 10 will be described. As shown in Figure 3, the discharge head 10 has a plurality of nozzles 121 that discharge ink droplets using ink from the storage tank 62. The discharge head 10 has a laminate of a flow channel forming body and a volume changing body. An ink flow channel is formed inside the flow channel forming body, and a plurality of nozzle holes 121a open on its lower surface, the discharge surface NM. The volume changing body is driven to change the volume of the ink flow channel. At this time, the meniscus vibrates in the nozzle holes 121a and ink is discharged.

[0026] The flow path forming body of the discharge head 10 is a laminate of multiple plates, and the volume changing section includes a diaphragm 155 and an actuator (piezoelectric element) 160. A common electrode 161, described later, is connected to the diaphragm 155.

[0027] Multiple plates are stacked, from bottom to top, including a nozzle plate 146, a spacer plate 147, a first channel plate 148, a second channel plate 149, a third channel plate 150, a fourth channel plate 151, a fifth channel plate 152, a sixth channel plate 153, and a seventh channel plate 154.

[0028] Each plate has holes and grooves of various sizes formed in it. Inside the flow channel forming body formed by stacking the plates, the holes and grooves are combined to form multiple nozzles 121, multiple individual flow channels 164, and a manifold 122 as ink flow channels.

[0029] The nozzle 121 is formed by penetrating the nozzle plate 146 in the stacking direction. On the discharge surface NM of the nozzle plate 146, multiple nozzle holes 121a, which are the tips of the nozzles 121, are arranged in the transport direction Df to form a nozzle row NL.

[0030] The manifold 122 supplies ink to the pressure chamber 128 to which discharge pressure is applied. The manifold 122 extends in the transport direction Df and is connected to one end of each of the multiple individual flow channels 164. In other words, the manifold 122 functions as a common flow channel for the ink. The manifold 122 is formed by through holes that penetrate the first flow channel plates 148 to the fourth flow channel plates 151 in the stacking direction, and recesses that are recessed from the lower surface of the fifth flow channel plate 152, overlapping in the stacking direction.

[0031] The nozzle plate 146 is positioned below the spacer plate 147. The spacer plate 147 is made of, for example, stainless steel. The spacer plate 147 has a recess 145 formed by, for example, half-etching, which causes a recess in the thickness direction of the spacer plate 147 from the surface facing the nozzle plate 146, thereby forming a thin-walled portion that forms a damper portion 147a and a damper space 147b. As a result, a damper space 147b is formed between the manifold 122 and the nozzle plate 146, acting as a buffer space.

[0032] A supply port 122a is connected to the manifold 122. The supply port 122a is formed, for example, in a cylindrical shape and is provided at one end in the conveying direction Df. The manifold 122 and the supply port 122a are connected by a flow path not shown in the figure.

[0033] Each individual flow path 164 is connected to the manifold 122. The upstream end of each individual flow path 164 is connected to the manifold 122, and the downstream end is connected to the base end of the nozzle 121. Each individual flow path 164 consists of a first communication hole 125, an individual throttling passage which is a supply throttling passage 126, a second communication hole 127, a pressure chamber 128, and a descender 129, and these components are arranged in this order.

[0034] The first communication hole 125 has its lower end connected to the upper end of the manifold 122, extends upward from the manifold 122 in the stacking direction, and penetrates the upper portion of the fifth flow path plate 152 in the stacking direction.

[0035] The upstream end of the supply throttling passage 126 is connected to the upper end of the first communication hole 125. The supply throttling passage 126 is formed, for example, by half-etching and consists of a groove recessed from the lower surface of the sixth flow channel plate 153. The second communication hole 127 has its upstream end connected to the downstream end of the supply throttling passage 126, extends upward from the supply throttling passage 126 in the stacking direction, and is formed by penetrating the sixth flow channel plate 153 in the stacking direction.

[0036] The pressure chamber 128 has its upstream end connected to the downstream end of the second communication hole 127. The pressure chamber 128 is formed by penetrating the seventh flow channel plate 154 in the stacking direction.

[0037] The descender 129 is formed by penetrating the spacer plate 147, the first flow path plate 148, the second flow path plate 149, the third flow path plate 150, the fourth flow path plate 151, the fifth flow path plate 152, and the sixth flow path plate 153 in the stacking direction. The upstream end of the descender 129 is connected to the downstream end of the pressure chamber 128, and the downstream end is connected to the base end of the nozzle 121. The nozzle 121 overlaps the descender 129 in the stacking direction, for example, and is positioned in the center of the descender 129 in the width direction.

[0038] The diaphragm 155 is laminated on the seventh flow path plate 154 and covers the upper end opening of the pressure chamber 128.

[0039] The actuator 160 includes a common electrode 161, a piezoelectric layer 162, and individual electrodes 163, arranged in this order. The common electrode 161 covers the entire surface of the diaphragm 155. The piezoelectric layer 162 covers the entire surface of the common electrode 161. Individual electrodes 163 are provided for each pressure chamber 128 and are arranged on the piezoelectric layer 162. One actuator 160 is composed of one individual electrode 163, the common electrode 161, and the portion of the piezoelectric layer 162 sandwiched between the two electrodes.

[0040] The individual electrodes 163 are electrically connected to a driver IC. This driver IC receives a control signal from the control device 20, generates a drive signal (voltage signal), and applies it to the individual electrodes 163. In contrast, the common electrode 161 is always kept at ground potential. In this configuration, the active portion of the piezoelectric layer 162 expands and contracts in the planar direction together with the common electrode 161 and the individual electrodes 163 in response to the drive signal. Accordingly, the diaphragm 155 deforms in cooperation, changing the volume of the pressure chamber 128 in a direction that increases or decreases it. As a result, the discharge pressure that causes ink droplets to be ejected from the nozzle 121 is applied to the pressure chamber 128.

[0041] In the ejection head 10, ink flows into the manifold 122 via the supply port 122a, then flows from the manifold 122 into the supply throttling passage 126 via the first communication hole 125, and from the supply throttling passage 126 into the pressure chamber 128 via the second communication hole 127. The ink then flows through the descender 129 and into the nozzle 121. At this point, when ejection pressure is applied to the pressure chamber 128 by the actuator 160, ink droplets are ejected from the nozzle hole 121a.

[0042] Figure 4 shows a light-emitting diode chip DT in the light source 40. As shown in Figure 4, the light source 40 has a support substrate 41 and a plurality of light-emitting diode chips DT arranged on the support substrate 41 that emit ultraviolet light. Each light-emitting diode chip DT irradiates ultraviolet light to cure the ink ejected by the ejection head 10. The light-emitting diode chip DT is a semiconductor element that generates ultraviolet light. Each light-emitting diode chip DT is regularly arranged at predetermined intervals in, for example, the moving direction Ds and the transport direction Df. Each light-emitting diode chip DT is arranged, for example, in a matrix.

[0043] Next, each component of the printing apparatus 1 of this embodiment will be described with reference to the block diagram. Figure 5 is a block diagram of the components of the printing apparatus 1 in Figure 1.

[0044] As shown in Figure 5, in addition to the components described above, the printing apparatus 1 includes a controller unit 19, a reader 26, motor driver ICs 30 and 31, head driver ICs 32 and 35, transport motor 33, carriage motor 34, irradiation device driver ICs 36 and 37, purge driver IC 38, wipe driver IC 39, and a 3D camera 29.

[0045] The controller unit 19 includes a control device 20 composed of a CPU, a storage unit (ROM 21, RAM 22, EEPROM 23, HDD 24), and an ASIC 25. The control device 20 is connected to each of the above-mentioned storage units and controls the driver ICs 29, 30-32, 35-39 and the display unit 5.

[0046] The control device 20 performs various functions by executing a predetermined processing program stored in the ROM 21. The control device 20 may be implemented as a single processor in the controller unit 19, or as multiple processors working together. The processing program is read by the reader 26 from a recording medium KB such as a computer-readable magneto-optical disk or USB flash memory and stored in the ROM 21. The RAM 22 stores image data received from an external source and the calculation results of the control device 20. The EEPROM 23 stores various initial setting information entered by the user. The HDD 24 stores specific information, etc.

[0047] The ASIC25 is connected to motor driver ICs 30 and 31, head driver ICs 32 and 35, irradiation device driver ICs 36 and 37, purge driver IC 38, wipe driver IC 39, and a 3D camera 29. When the control device 20 receives a print job from the user, it outputs a processing command to the ASIC25 based on the processing program. The ASIC25 drives each driver IC 29, 30-32, 35-39 based on the processing command. The control device 20 moves the platen 6 in the transport direction Df by driving the transport motor 33 with the motor driver IC 30. The control device 20 moves the carriage 3 in the movement direction Ds by driving the carriage motor 34 with the motor driver IC 31.

[0048] The control device 20 converts image data acquired from an external device into ejection data for ejecting ink droplets onto the printing surface. Based on the converted ejection data, the control device 20 uses head driver ICs 32 and 35 to eject ink droplets from the ejection head 10. The control device 20 also uses irradiation device driver ICs 36 and 37 to irradiate ultraviolet light from the light-emitting diode chips of light sources 40A and 40B. The control device 20 uses a purge driver IC 38 to drive the suction pump 52 and lifting mechanism 53 of the purge unit 50. The control device 20 uses a wipe driver IC 39 to drive the movement mechanism 57 of the wipe unit 54.

[0049] The control device 20 has an acquisition unit 70 as a functional configuration. The 3D camera is, for example, mounted on the carriage 3 and images the printing medium W. The acquisition unit 70 of the control device 20 receives information about the shape of the printing medium W imaged by the 3D camera 29. In order to acquire the shape of the printing medium W, other devices such as a distance measuring sensor may be used instead of the 3D camera 29 that images the printing medium W.

[0050] Figure 6 is a perspective view showing the printing medium W, which is the target of printing by the printing apparatus 1 in Figure 1, and Figure 7 is a perspective view showing the printing medium W from a different direction than in Figure 6. The ejection head 10 prints on the printing medium W, which is a three-dimensional object with edges. In Figures 6 and 7, the printing medium W is shown as an example of a shape formed in the shape of a triangular pyramid.

[0051] As shown in Figures 6 and 7, the printing medium W has two adjacent printing surfaces Wh1 and Wh2. The boundary between printing surface Wh1 and printing surface Wh2 is the edge line RL.

[0052] The control device 20 performs a process (hereinafter sometimes referred to as the ink amount increase process) to control the ejection operation of the ejection head 10 so that the amount of ink per unit area is increased in the ridge-existing region Rr, which is the region including the ridge line RL, compared to the region outside the ridge-existing region Rr. In this embodiment, the control device 20 can perform the ink amount increase process for the ejection head 10A. As a result, the ejection head 10A ejects ink droplets of color ink with an increased amount per unit area compared to the region outside the ridge-existing region Rr into the ridge-existing region Rr. This makes the thickness of the printed portion in the ridge-existing region Rr greater than the thickness of the printed portion in the region outside the ridge-existing region Rr. Note that the illustration of the color ink printed portion is omitted in Figure 8.

[0053] Furthermore, the control device 20 can also perform an ink quantity increase process for the ejection head 10B. As a result, the ejection head 10B ejects primer ink or white ink droplets to the ridge region Rr in a quantity increased per unit area compared to areas other than the ridge region Rr. This makes the thickness of the base layer Lu1 in the ridge region Rr greater than the thickness of the base layer Lu2 in areas other than the ridge region Rr, as shown in Figure 8. In addition, the ejection head 10B ejects clear ink droplets to the ridge region Rr in a quantity increased per unit area compared to areas other than the ridge region Rr. As a result, as shown in Figure 8, the thickness of the protective layer Lp1 in the ridge region Rr greater than the thickness of the protective layer Lp2 in areas other than the ridge region Rr.

[0054] At least one of the following processes must be performed: increasing the amount of ink in the printed area with color ink in the ridge region Rr, increasing the amount of ink in the underlayer Lu1 in the ridge region Rr, and increasing the amount of ink in the protective layer Lp1 in the ridge region Rr.

[0055] The printing medium W in Figures 6 and 7 has multiple ridges, but the only ridge included in the ridge existence region Rr where printing is performed by the ejection head 10 is the ridge RL formed by the printing surface Wh1 and printing surface Wh2 that face the ejection surface NM of the ejection head 10 when the ejection head 10 moves back and forth in the movement direction Ds. Therefore, in a triangular pyramidal printing medium W, for example, the ridge between the printing surface Wh1 and other printing surfaces (printing surfaces other than printing surfaces Wh1 and Wh2), or for example, the ridge between the printing surface Wh2 and one end surface in the axial direction of the printing medium W, do not fall under the ridge RL included in the ridge existence region Rr.

[0056] The processing procedure of the control device 20 is as follows: After receiving print data from an external source, the control device 20 acquires information related to the shape of the printing medium W on the platen 6 from the 3D camera 29 using the acquisition unit 70. Based on the print data and the shape of the printing medium W, the control device 20 determines whether correction is necessary (i.e., whether an ink volume increase process is necessary). In this case, correction is determined to be necessary if the ridge line RL defined above exists on the printing medium W. The control device 20 then determines the method and amount of the ink volume increase process (size of the ridge line presence area Rr and layer thickness) to be performed and creates print image data. Based on the created print image data, the control device 20 causes the ejection head 10 to perform printing.

[0057] The specific method for increasing the ink volume will be explained. Figure 9 is a diagram illustrating the number of ink droplets Id ejected in the ridge region Rr and the number of ink droplets Id ejected in regions other than the ridge region Rr. Figure 10 is a diagram illustrating the size of ink droplets Idb in the ridge region Rr and the size of ink droplets Id in regions other than the ridge region Rr. For ease of understanding, the line indicating the ridge region Rr is shown in thicker lines in Figures 9 and 10.

[0058] In this embodiment, the ridge line RL includes a straight line that has no width in direction D1 and extends in direction D2 perpendicular to direction D1, as well as a line that has a predetermined width in direction D1 and extends in direction D2, as shown in Figures 9 and 10. In Figures 9 and 10, the angle between one printed surface Wh1 and the other printed surface Wh2 is denoted as θ.

[0059] As shown in Figure 9, the control device 20 controls the ejection operation of the ejection head 10 so that the number of ejections to the ridge area Rr is greater than the number of ejections to the area other than the ridge area Rr during the ink volume increase process. This makes it possible to increase the amount of ink per unit area in the ridge area Rr compared to the area other than the ridge area Rr. Note that the ink droplet Id in Figure 9 and Figure 10 below is one of the following: an ink droplet of color ink, an ink droplet of primer ink or white ink that forms the base layer, or an ink droplet of clear ink that forms the protective layer.

[0060] Alternatively, the following may be done: As shown in Figure 10, the control device 20 may control the ejection operation of the ejection head 10 so that the size of the ink droplet Idb ejected to the ridge region Rr is larger than the size of the ink droplet Id ejected to the region other than the ridge region Rr during the ink amount increase process. This also makes it possible to increase the amount of ink per unit area in the ridge region Rr compared to the region other than the ridge region Rr.

[0061] Alternatively, the control device 20 may control the ejection head 10 in the ink volume increase process so that the ejection operation is performed in more passes for the area where the ridge line exists Rr than for the area where the ridge line exists Rr. In this case, for example, the ejection head 10 performs the ejection operation in one pass for the area where the ridge line exists Rr, and in two passes for the area where the ridge line exists Rr. This also makes it possible to increase the amount of ink per unit area in the area where the ridge line exists Rr compared to the area where the ridge line exists Rr.

[0062] Here, the size (area) of the ridge-existing region Rr described above can be changed. The control device 20 changes the area of ​​the ridge-existing region Rr based on the material of the printing medium W. Specifically, when the material of the printing medium W is relatively hard (when the amount of deformation is relatively small), the area of ​​the ridge-existing region Rr is made relatively small, and when the material of the printing medium W is relatively soft (when the amount of deformation is relatively large), the area of ​​the ridge-existing region Rr is made relatively large. In addition, when the ink droplet adhesion on the printing medium W is poor, the area of ​​the ridge-existing region Rr is made relatively large.

[0063] As a specific example of how to change the area of ​​the ridge presence region Rr, for example, a table showing the correspondence between each material of the printing medium W and each coefficient corresponding to that material (each coefficient when the coefficient for when the printing medium W is made of a predetermined standard material is set to 1.0) can be pre-stored in a storage unit such as a ROM 21 or HDD 24. The control device 20 reads the coefficient from the storage unit based on the material of the printing medium W, and can obtain the area of ​​the ridge presence region Rr corresponding to that material by multiplying the area of ​​the ridge presence region Rr when the material of the printing medium W is a standard material (standard area) by the coefficient. The control device 20 ejects ink droplets from the ejection head 10 to the ridge presence region Rr of the acquired area. This makes it possible to perform an ink amount increase process for the ridge presence region Rr having an area corresponding to the material of the printing medium W.

[0064] Furthermore, the control device 20 may change the thickness of the base layer Lu1 and the protective layer Lp1 in the ridge area Rr based on the material of the printing medium W. In this regard, if the material of the printing medium W is relatively hard, the thickness of the ridge area Rr may be made relatively thick to prevent chipping, and if the material of the printing medium W is relatively soft, the thickness of the ridge area Rr may be made relatively thin. Also, if the ink droplet adhesion on the printing medium W is poor, the thickness of the ridge area Rr may be made relatively thick.

[0065] The control device 20 may change the area of ​​the edge region Rr based on the angle θ formed by one printable surface Wh1 and the other printable surface Wh2. In this case, for example, a table showing the correspondence between each angle θ and each coefficient corresponding to the angle θ (each coefficient when the coefficient for angle θ is a predetermined reference angle is set to 1.0) can be pre-stored in a storage unit such as a ROM 21 or HDD 24. The control device 20 reads the coefficient from the storage unit based on the angle θ and obtains the area of ​​the edge region Rr corresponding to that angle θ by multiplying the area of ​​the edge region Rr when the angle θ is a reference angle (reference area) by the coefficient. The control device 20 ejects ink droplets from the ejection head 10 to the edge region Rr of the obtained area. This allows for an ink amount increase process to be performed on the edge region Rr having an area corresponding to the angle θ. In this case, the smaller the angle θ, the larger the area of ​​the edge region Rr.

[0066] The control device 20 may change the thickness of the underlying layer Lu1 and the protective layer Lp1 in the ridge region Rr according to the angle θ. In this case, the smaller the angle θ, the thicker the layer Lu1 and the protective layer Lp1 become.

[0067] Figure 11A shows the curing state of ink droplets and color ink droplets that make up the base layer in a conventional case. Figure 11B shows the curing state of ink droplets and color ink droplets that make up the base layer in this embodiment.

[0068] As shown in Figure 11A, if the ink droplets Ids forming the base layer are irradiated with ultraviolet light relatively soon after ejection, the ink droplets Ids harden before they have formed a flat shape. As a result, the contact area between the ink droplets Ids of the subsequently ejected color ink becomes smaller. Consequently, the adhesion of the color ink droplets Ids to the ink droplets Ids is reduced. In addition, the coverage rate of the base layer on the printed surface Wh1, Wh2 also decreases, making the base layer more visible.

[0069] In contrast, in this embodiment, ultraviolet light is irradiated relatively late after the ink droplets Ids that form the base layer are ejected. This allows the ink droplets Ids to harden (or partially harden) in a flattened state. As a result, the contact area between the ink droplets Ids of the subsequently ejected color ink and the ink droplets Ids increases. This improves the adhesion of the color ink to the ink droplets Ids. Furthermore, the coverage rate of the printed surface Wh1,Wh2 by the base layer also increases, making the base layer less visible.

[0070] As explained above, in the printing apparatus 1, during the ink amount increase process, the amount of ink per unit area is increased in the ridge area Rr compared to areas other than the ridge area Rr. This suppresses or prevents the appearance of white areas in the printed image in the ridge area Rr due to misalignment of the ink droplet landing position. This improves the quality of the printing result and further suppresses ink peeling when the ridge area Rr of the printing medium W comes into contact with the outside.

[0071] Furthermore, in this embodiment, during the ink volume increase process, the number of inks ejected to the ridge-containing region Rr is increased compared to the number of inks ejected to regions other than the ridge-containing region Rr. This makes it easy to increase the amount of ink per unit area in the ridge-containing region Rr.

[0072] Furthermore, in this embodiment, during the ink volume increase process, the size of the ink droplet Idb ejected to the ridge region Rr is larger than the size of the ink droplet Id ejected to regions other than the ridge region Rr. This makes it easy to increase the amount of ink per unit area in the ridge region Rr.

[0073] Furthermore, in this embodiment, during the ink volume increase process, the ejection operation is performed with more passes for the ridge-containing region Rr than for the regions other than the ridge-containing region Rr. This makes it easy to increase the amount of ink per unit area for the ridge-containing region Rr.

[0074] Furthermore, in this embodiment, the size of the edge region Rr is changed based on the material of the printing medium W, and the thickness of the base layer Lu1 and the protective layer Lp1 are changed. This allows for appropriate adjustment of the thickness of the base layer Lu1 and the protective layer Lp1 according to the hardness (softness) of the printing medium W, thereby suppressing or preventing the appearance of white areas in the printed image.

[0075] Furthermore, in this embodiment, the size of the ridge-existing region Rr is changed based on the angle θ between one printable surface Wh1 and the other printable surface Wh2, and the thickness of the base layer Lu1 and the protective layer Lp1 are changed. This allows for appropriate adjustment of the thickness of the base layer Lu1 and the protective layer Lp1 according to the angle θ (i.e., the shape of the printable medium W), thereby suppressing or preventing the appearance of white areas in the printed image.

[0076] (Other embodiments) The present invention is not limited to the embodiments described above, and other embodiments can be adopted without departing from the spirit of the invention. For example, the following:

[0077] In the above embodiment, the control device 20 in the printing device 1 is configured to determine whether correction is necessary (whether an ink amount increase process is necessary) based on the print data and the shape of the printing medium W. In other words, the printer is configured to determine whether correction is necessary. However, the invention is not limited to this, and the printing device may be configured as follows. Figure 12 is a block diagram showing the configuration of a printing device 1A, which is a modified example of the printing device 1 in Figure 1.

[0078] As shown in Figure 12, the printing apparatus 1A is a technical concept that includes a computer 200, such as a personal computer, and a printer 300. The printer 300 has the same printing function as the printing apparatus 1 in Figure 1. The computer 200 includes an input unit 201 such as a keyboard, an acquisition unit 202, a correction necessity determination unit 203, and a correction unit 204. The acquisition unit 202, the correction necessity determination unit 203, and the correction unit 204 are functional components of the CPU provided in the computer 200. The printer 300 also includes a control device 301 and an ejection head 302.

[0079] The user inputs print data and information relating to the shape of the print medium W using the input unit 201 of the computer 200. The acquisition unit 202 acquires the input information relating to the shape of the print medium W. The correction necessity determination unit 203 determines whether correction is necessary based on the print data and the shape of the print medium W. The correction unit 204 determines the method and amount of ink increase processing (area of ​​the edge presence region Rr and layer thickness), creates print image data, and sends it to the printer 300. In this case, the correction unit 204 applies layer addition processing such as a color layer and a protective layer to the print image data. Meanwhile, the control device 301 of the printer 300 causes the ejection head 302 to execute printing based on the print image data sent from the computer 200. As described above, the corrected print image data may be created on the computer 200 side.

[0080] Furthermore, the configuration of the printing apparatus 1A in Figure 12 may be modified as follows. Figure 13 is a block diagram showing the configuration of the printing apparatus 1B, which is a modified version of the printing apparatus 1A in Figure 12.

[0081] As shown in Figure 13, the printing apparatus 1B is a technical concept that includes a computer 200A, such as a personal computer, and a printer 300A. The printer 300A has the same printing function as the printing apparatus 1 in Figure 1. The computer 200A includes an input unit 201, an acquisition unit 202, a correction necessity determination unit 203, and a correction instruction unit 205. The acquisition unit 202, the correction necessity determination unit 203, and the correction instruction unit 205 are functional components of the CPU provided in the computer 200A. The printer 300A also includes a control device 301 having a correction unit 303 and an ejection head 302.

[0082] The user inputs print data and information relating to the shape of the printing medium W using the input unit 201 of the computer 200A. The acquisition unit 202 acquires the input information relating to the shape of the printing medium W. The correction necessity determination unit 203 determines whether correction is necessary based on the print data and the shape of the printing medium W. The correction instruction unit 205 determines the method and amount of ink increase processing (area of ​​the ridge-existing region Rr and layer thickness) and sends data with correction instruction information added to the uncorrected print image data to the printer 300A. In this case, the correction instruction unit 205 adds the method of ink increase processing, the amount of increase processing (area of ​​the ridge-existing region Rr and layer thickness), and ejection waveform setting information to the print image data as correction instruction information. Meanwhile, the correction unit 303 of the control device 301 of the printer 300A creates corrected print image data based on the print image data to which the correction instruction information has been added, and causes the ejection head 302 to execute printing based on this print image data. As described above, the computer 200 may create only the correction instruction information, and the printer 300A may create the corrected print image data based on that correction instruction information. [Explanation of Symbols]

[0083] 1,1A,1B Printing device 10, 10A, 10B Discharge Head 20 Control device 70 Acquisition Department Lp1 Protective layer in the ridge region Lp2 Protective layer in regions other than the ridge region Lu1 Underlying layers in the ridge region Lu2 Substrates in areas other than the ridge region RL ridge Rr Edge existence area W Printing medium Wh1,Wh2 Printing surface θ is the angle formed between one surface to be printed and the other surface to be printed.

Claims

1. A printing medium is provided with a printing head that ejects at least one of the following inks: an ultraviolet-curing printing ink, an underlayer ink that forms a base layer, and a protective layer ink that forms a protective layer. An acquisition unit that acquires information about the shape of the printing medium, Equipped with a controller, The aforementioned controller, Based on the shape information of the printing medium acquired by the acquisition unit, an ink amount increase process is performed to control the ejection operation of the ejection head so as to increase the amount of ink per unit area in the region containing the ridge line, which is the boundary between one printing surface and the other adjacent printing surface of the printing medium, compared to the region outside the ridge line region, and A printing apparatus that controls the ejection operation of the ejection head to change the size of the region where the ridge line should be ejected by the ejection head, based on the angle formed between one surface to be printed and the other surface to be printed, and to change the thickness of the base layer and the thickness of the protective layer.

2. The printing apparatus according to claim 1, wherein the controller controls the ejection operation of the ejection head in the ink volume increase process so that the number of ejections to the area where the ridge exists is greater than the number of ejections to the area other than the area where the ridge exists.

3. The printing apparatus according to claim 1, wherein the controller controls the ejection operation of the ejection head in the ink volume increase process such that the size of the ink droplet ejected to the region where the ridge exists is larger than the size of the ink droplet ejected to the region other than the region where the ridge exists.

4. The printing apparatus according to claim 1, wherein the controller controls the ejection head in the ink volume increase process so that the ejection operation is performed in the region where the ridge exists with more passes than the passes to the region other than the region where the ridge exists.

5. The printing apparatus according to claim 1, wherein the protective layer ink is clear ink.

6. The printing apparatus according to claim 1, wherein the ink for the underlayer is a primer ink or a white ink.

7. The printing apparatus according to claim 1, wherein the controller controls the ejection operation of the ejection head to change the size of the region where the ridge line should be ejected by the ejection head, and to change the thickness of the underlayer and the thickness of the protective layer, based on the material of the medium to be printed.

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