Droplet ejection device, droplet ejection method, and droplet ejection program

Abstract

To provide a droplet discharge device, droplet discharge method and droplet discharge program which can fill in a recess in a printing object medium with liquid in an amount more suitable to the volume thereof in a short time.SOLUTION: A droplet discharge device comprises: a discharge head which has a nozzle that discharges droplets onto a printing object medium and an actuator that applies pressure to liquid in a pressure chamber communicating to the nozzle; a waveform generation circuit which generates a drive waveform of a signal for driving the actuator; a surface information acquisition device which acquires information about the surface of the printing object medium; and a control device. The control device executes processing of calculating the volume of a recess in the printing object medium on the basis of a result of acquisition performed by the surface information acquisition device, repair waveform generation processing of generating a drive waveform for filling in the recess according to the volume of the recess in the waveform generation circuit, and recess repair processing of driving the actuator with the drive waveform generated by the waveform generation circuit and discharging the droplets from the nozzle to the recess.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a droplet ejection device, a droplet ejection method, and a droplet ejection program used in an image recording device such as an inkjet printer. [Background technology]

[0002] Conventionally, techniques for repairing scratches on an image printed on a print medium have been proposed. For example, Patent Document 1 discloses an inkjet printer that acquires positional information of a scratch on a print medium, estimates the amount of ink required to fill the scratch, and then ejects ink onto the scratch. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-129823 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when ejecting ink droplets of the same droplet size onto a scratch on a print medium, there is a risk that the estimated amount of ink will be insufficient for the volume of the scratch, or that the estimated amount of ink will be excessive for the volume of the scratch.

[0005] Therefore, an object of the present invention is to provide a droplet ejection device, a droplet ejection method, and a droplet ejection program that can fill recesses in a print medium in a short time using an amount of liquid that is appropriate for the volume of the recesses. [Means for solving the problem]

[0006] The droplet ejection device of the present invention comprises an ejection head having a nozzle that ejects droplets onto a print medium and an actuator that applies pressure to liquid in a pressure chamber connected to the nozzle, a waveform generation circuit that generates a drive waveform for a signal that drives the actuator, a surface information acquisition device that acquires information about the surface of the print medium, and a control device, wherein the control device performs a process of calculating the volume of a recess in the print medium based on the results acquired by the surface information acquisition device, a repair waveform generation process that causes the waveform generation circuit to generate a drive waveform for filling the recess in accordance with the volume of the recess, and a recess repair process that drives the actuator with the drive waveform generated by the waveform generation circuit and ejects the droplet from the nozzle into the recess.

[0007] According to the present invention, the volume of the recessed portion in the printing medium is calculated by the control device based on the results obtained by the surface information acquisition device. This allows the accurate volume of the recessed portion to be obtained. The control device then executes a recess repair process that drives the actuator using a drive waveform generated by a waveform generation circuit. In this way, a drive waveform corresponding to the volume of the recessed portion in the printing medium is used, so the recessed portion can be filled without excess or deficiency. This makes it possible to avoid excessive ejection of droplets into the recessed portion, and therefore the recessed portion can be filled in a shorter time than conventional methods. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a droplet ejection device, a droplet ejection method, and a droplet ejection program that can suppress deterioration in image quality. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a plan view showing a schematic configuration of a droplet ejection device according to an embodiment of the present invention. [Figure 2] 2 is a plan view showing an example of the arrangement of the ejection head and the light source unit mounted on the carriage of FIG. 1. FIG. [Figure 3] FIG. 2 is a cross-sectional view of a discharge head of the droplet discharge device of FIG. [Figure 4] FIG. 2 is a block diagram showing the configuration of an image recording apparatus equipped with the droplet ejection device of FIG. [Figure 5] 4A and 4B are explanatory diagrams showing dedicated waveforms and printing waveforms generated by a waveform generating circuit. [Figure 6] 10A and 10B are diagrams illustrating dynamic ejection times and static ejection times when filling a first recess on a print medium. [Figure 7] 10A and 10B are diagrams illustrating dynamic ejection times and static ejection times when filling a second recess on a print medium. [Figure 8] 10A and 10B are diagrams illustrating dynamic ejection times and static ejection times when filling a third recess on a print medium. [Figure 9] 4 is a flowchart showing a main routine of a recess repair process performed by the control device. [Figure 10] 10 is a flowchart showing an example of a part of a subroutine of repair printing in FIG. 9. [Figure 11] 10 is a flowchart showing an example of the remaining part of the repair printing subroutine of FIG. 9. [Figure 12] 10A and 10B are diagrams showing the positional relationship between the ejection head and recesses when the ejection head is stopped twice during printing of the recesses. [Figure 13] 10 is a flowchart illustrating an example of a portion of a subroutine for repair printing. [Figure 14] 10 is a flowchart showing an example of the remainder of the repair printing subroutine. [Figure 15] 10A and 10B are diagrams for explaining the stopping position of the ejection head when printing is performed with the ejection head stopped on a plurality of recesses present on a print medium. [Figure 16] FIG. 2 is a cross-sectional view showing a printing nozzle and a recess repair nozzle. DETAILED DESCRIPTION OF THE INVENTION

[0010] A droplet ejection device, a droplet ejection method, and a droplet ejection program according to an embodiment of the present invention will be described below with reference to the drawings. The droplet ejection device, the droplet ejection method, and the droplet ejection program described below are merely one embodiment of the present invention. Therefore, the present invention is not limited to the following embodiment, and additions, deletions, and modifications are possible within the scope of the present invention.

[0011] (First embodiment) 1, a droplet ejection device 10 of this embodiment uses ink as an example of a liquid and ejects ink droplets as an example of a droplet, and includes a storage tank 12, a carriage 16, an ejection head 20, a pair of transport rollers 15, a pair of guide rails 17, and a sub-tank 18. In the droplet ejection device 10, a print medium W is placed on a platen (not shown).

[0012] The carriage 16 is equipped with an ejection head 20. The carriage 16 is supported by a pair of guide rails 17 extending in a movement direction Ds perpendicular to the transport direction Df of the print medium W, and moves back and forth in the movement direction Ds along the guide rails 17. This causes the ejection head 20 to move back and forth in the movement direction Ds. A control device 71, which will be described later, can move the carriage 16 at one of a plurality of movement speeds while causing the ejection head 20 to eject ink droplets. In addition, the carriage 16 is equipped with, for example, four sub-tanks 18. Each sub-tank 18 is connected to a corresponding storage tank 12 via a tube.

[0013] The pair of transport rollers 15 are arranged parallel to each other along the movement direction Ds. The transport rollers 15 rotate when a transport motor (not shown) is driven, thereby transporting the print medium W on the platen in the transport direction.

[0014] Ink is stored in the storage tanks 12. The storage tanks 12 are connected to the ejection heads 20 via ink flow paths to supply ink to the ejection heads 20. A storage tank 12 is provided for each type of ink. For example, four storage tanks 12 are provided, each storing black, yellow, cyan, and magenta ink.

[0015] As shown in Fig. 2, two ejection heads 20 (20A, 20B) and two light source units 40 (40A, 40B) are mounted on the carriage 16. The carriage 16 is configured to be able to reciprocate along the movement direction Ds. As a result, the carriage 16 moves the ejection heads 20 and the light source units 40 in the movement direction Ds.

[0016] The ejection head 20 may be, for example, an inkjet head that ejects ultraviolet-curable ink droplets. The light source unit 40 emits ultraviolet light that is irradiated onto the ejected ink droplets. The ink droplets are cured by being irradiated with ultraviolet light. The ejection head 20A and the ejection head 20B are arranged side by side along the transport direction Df. The ejection head 20B is arranged, for example, in front of the ejection head 20A. The light source unit 40A and the light source unit 40B are also arranged side by side along the transport direction Df. The light source unit 40B is arranged, for example, in front of the light source unit 40A. The ejection head 20A and the light source unit 40A are also arranged side by side along the movement direction Ds. The light source unit 40A is arranged to the left of the ejection head 20A (one direction Ds1 of the movement direction Ds). The ejection head 20B and the light source unit 40B are also arranged side by side along the movement direction Ds. The light source unit 40B is arranged to the left of the ejection head 20B (one direction Ds1 of the movement direction Ds). The above arrangement is an example and is not limiting.

[0017] During the first scan in the printing process, the carriage 16 moves to the right in the movement direction Ds (the other direction Ds2 of the movement direction Ds). As a result, the ejection head 20 and the light source unit 40 move to the right during the printing process. In this case, the ejection head 20 ejects ink droplets onto the print medium W while moving to the right in the movement direction Ds, and the light source unit 40 irradiates ultraviolet light onto the ink droplets that have landed on the print medium W while moving to the right in the movement direction Ds. In this way, since the light source unit 40 is positioned behind the ejection head 20 in the movement direction of the carriage 16 during the printing process, ultraviolet light can be irradiated onto the ink droplets immediately after they have landed on the print medium W.

[0018] The ejection head 20A ejects ink droplets of each color, yellow (Y), magenta (M), cyan (C), and black (K), which are sometimes collectively referred to as color inks. The ejection head 20A is provided with nozzle rows NL that eject each of the above ink droplets, each extending along the transport direction Df. Each nozzle row NL is provided at regular intervals in the movement direction Ds. The nozzle rows NL may be arranged in the movement direction Ds in the following order from one direction Ds1 side of the movement direction Ds: the nozzle row NL that ejects black ink droplets, the nozzle row NL that ejects cyan ink droplets, the nozzle row NL that ejects magenta ink droplets, and the nozzle row NL that ejects yellow ink droplets.

[0019] On the other hand, the ejection head 20B ejects white (W) ink and clear (Cr) ink droplets. The ejection head 20B is provided with nozzle rows NL that eject these ink droplets, each extending along the transport direction Df. More specifically, the ejection head 20B is provided with two nozzle rows NL that eject white ink droplets and two nozzle rows NL that eject clear ink droplets from one side Ds1 of the movement direction Ds. The nozzle rows NL are provided at regular intervals along the movement direction Ds.

[0020] A color image is printed on the print medium W by ejecting the six color ink droplets onto the print medium W. Generally, when printing a color image on a print medium W such as fabric, white ink droplets are ejected first as base ink to reduce the effect on the color and material of the fabric, and color ink droplets are ejected on top of the white ink droplets that have landed on the print medium W. In particular, when repairing depressions on the print medium W by filling them with ink droplets, an ejection head 20B that ejects white ink or clear ink is used. In this regard, when filling depressions, white ink is used to improve the reproducibility of the print color, and clear ink is used to print while preserving the color of the base material.

[0021] As shown in Figure 3, the ejection head 20 has a plurality of nozzles 21 that eject ink droplets. The ejection head 20 has a laminated body of a flow path forming body and a volume changing unit. A liquid flow path is formed inside the flow path forming body, and a plurality of nozzle holes 21a are opened in the nozzle surface 40a, which is the lower surface of the flow path forming body. The volume changing unit is driven to change the volume of the liquid flow path. At this time, the meniscus vibrates in the nozzle holes 21a, and ink is ejected.

[0022] The flow path forming body of the ejection head 20 is a laminate of multiple plates, and the volume changing section includes a vibration plate 55 and an actuator (piezoelectric element) 60. An insulating film 56 is connected to the top of the vibration plate 55, and a common electrode 61 (described later) is connected to the top of the insulating film 56.

[0023] The multiple plates are stacked including, in order from the bottom, a nozzle plate 46, a spacer plate 47, a first flow path plate 48, a second flow path plate 49, a third flow path plate 50, a fourth flow path plate 51, a fifth flow path plate 52, a sixth flow path plate 53, and a seventh flow path plate 54. The first flow path plate 48, the second flow path plate 49, the third flow path plate 50, the fourth flow path plate 51, and the fifth flow path plate 52 configure the manifold plate 44.

[0024] Each plate has holes and grooves of various sizes formed therein. Inside the flow path forming body where the plates are stacked, the holes and grooves are combined to form a plurality of nozzles 21, a plurality of individual flow paths 64, and a manifold 22 as liquid flow paths.

[0025] The nozzles 21 are formed to penetrate the nozzle plate 46 in the stacking direction. In the nozzle surface 40a of the nozzle plate 46, a plurality of nozzle holes 21a, which are the tips of the nozzles 21, are aligned in the transport direction Df, which is the arrangement direction, to form a nozzle row NL.

[0026] The manifold 22 supplies ink to pressure chambers 28 (described later) to which ink droplet ejection pressure is applied. The manifold 22 extends in the arrangement direction and is connected to one end of each of the individual flow paths 64. In other words, the manifold 22 functions as a common flow path for the ink. The manifold 22 is formed by through-holes that penetrate the first flow path plate 48 to the fourth flow path plate 51 in the stacking direction and recesses that are recessed from the lower surface of the fifth flow path plate 52, which are overlapped in the stacking direction.

[0027] The nozzle plate 46 is disposed below a spacer plate 47. The spacer plate 47 is formed of, for example, stainless steel. The spacer plate 47 has a recess 45 formed by, for example, half-etching, recessing the surface on the nozzle plate 46 side in the thickness direction of the spacer plate 47, thereby forming a thin portion constituting the damper portion 47a and a damper space 47b. With this configuration, the damper space 47b is formed as a buffer space between the manifold 22 and the nozzle plate 46.

[0028] A supply port 22a communicates with the manifold 22. The supply port 22a is formed, for example, in a cylindrical shape and is provided at one end in the arrangement direction. The manifold 22 and the supply port 22a are connected by unillustrated flow paths that penetrate the upper portion of the fifth flow path plate 52, the sixth flow path plate 53, and the seventh flow path plate 54, respectively.

[0029] The multiple individual flow paths 64 are each connected to the manifold 22. The upstream ends of the individual flow paths 64 are connected to the manifold 22, and the downstream ends are connected to the base ends of the nozzles 21. The individual flow paths 64 are composed of a first communication hole 25, a supply throttle path 26 which is an individual throttle path, a second communication hole 27, a pressure chamber 28, and a descender 29, and these components are arranged in this order, and the pressure chamber 28 is connected to the nozzles 21.

[0030] The first communication hole 25 has a lower end connected to the upper end of the manifold 22, extends upward in the stacking direction from the manifold 22, and penetrates an upper portion of the fifth flow path plate 52 in the stacking direction.

[0031] The upstream end of supply throttle path 26 is connected to the upper end of first communication hole 25. Supply throttle path 26 is formed by half etching, for example, and is configured as a groove recessed from the lower surface of sixth flow path plate 53. Furthermore, second communication hole 27 has its upstream end connected to the downstream end of supply throttle path 26, extends upward in the stacking direction from supply throttle path 26, and is formed to penetrate sixth flow path plate 53 in the stacking direction.

[0032] The upstream end of the pressure chamber 28 is connected to the downstream end of the second communication hole 27. The pressure chamber 28 is formed to penetrate the seventh flow path plate 54 in the stacking direction.

[0033] The descender 29 is formed to penetrate the spacer plate 47, the first flow path plate 48, the second flow path plate 49, the third flow path plate 50, the fourth flow path plate 51, the fifth flow path plate 52, and the sixth flow path plate 53 in the stacking direction, and is disposed on the left side of the manifold 22 in the width direction. The descender 29 has an upstream end connected to the downstream end of the pressure chamber 28, and a downstream end connected to the base end of the nozzle 21. The nozzle 21 overlaps the descender 29 in the stacking direction, for example, and is disposed in the center of the descender 29 in the width direction perpendicular to the stacking direction.

[0034] The vibration plate 55 is laminated on the seventh flow path plate 54 and covers the upper openings of the pressure chambers 28.

[0035] The actuator 60 includes a common electrode 61, a piezoelectric layer 62, and an individual electrode 63, which are arranged in this order. The common electrode 61 covers the entire surface of the vibration plate 55 with an insulating film 56 interposed therebetween. The piezoelectric layer 62 is provided for each pressure chamber 28, and is arranged on the common electrode 61 so as to overlap the pressure chamber 28. The individual electrode 63 is provided for each pressure chamber 28, and is arranged on the piezoelectric layer 62. One individual electrode 63, the common electrode 61, and the portion of the piezoelectric layer 62 sandwiched between the two electrodes constitute one actuator 60.

[0036] The individual electrodes 63 are electrically connected to a driver IC. This driver IC receives a control signal from a control device 71 (described later) to generate a drive signal and apply it to the individual electrodes 63. In contrast, the common electrode 61 is always maintained at ground potential. In this configuration, the active portion of the piezoelectric layer 62 expands and contracts in the planar direction together with the two electrodes 61, 63 in response to the drive signal. In response, the vibration plate 55 deforms in cooperation with the drive signal, and the volume of the pressure chamber 28 changes in a direction that increases or decreases. As a result, an ejection pressure is applied to the pressure chamber 28, causing an ink droplet to be ejected from the nozzle 21.

[0037] In the ejection head 20, the supply port 22a is connected to the sub-tank 18 via a pipe. When a pressure pump provided in the pipe is driven, ink passes from the sub-tank 18 through the pipe and flows into the manifold 22 via the supply port 22a. The ink then flows from the manifold 22 into the supply throttle passage 26 via the first communication hole 25, and from the supply throttle passage 26 into the pressure chamber 28 via the second communication hole 27. The ink then flows through the descender 29 and into the nozzle 21. When an ejection pressure is applied to the pressure chamber 28 by the actuator 60, an ink droplet is ejected from the nozzle hole 21a.

[0038] Next, other components of the droplet ejection device 10 and an image recording device 1 including the droplet ejection device 10 will be described with reference to the drawings. The image recording device 1 of this embodiment is, for example, an inkjet printer.

[0039] 4, the droplet discharge device 10 includes a control device 71 that is configured with a CPU and corresponds to a computer, a RAM 72, a ROM 73, a head driver IC 74, an imaging device 75, a waveform generating circuit 76, a light source driver IC 78, motor driver ICs 30 and 32, a transport motor 31, and a carriage motor 33. The image recording device 1 also includes the droplet discharge device 10, a network interface (I / F) 70, and a recording medium reader 77. In this embodiment, the imaging device 75 corresponds to a surface information acquisition device.

[0040] The imaging device 75 captures an image of the surface of the print medium W. The imaging device 75 is, for example, a 3D scanner, and is provided on the carriage 16. The control device 71 receives the imaging results from the imaging device 75. The control device 71 calculates the area and volume of recesses present in the print medium W based on the imaging results from the imaging device 75. In this embodiment, the recesses are either scratches, dents, or both scratches and dents.

[0041] The waveform generating circuit 76 generates a drive waveform for the drive signal that drives the actuator 60. This drive signal includes an ejection drive signal that applies pressure to the ink in the pressure chamber 28 to eject ink droplets from the nozzle 21, a non-ejection drive signal that applies pressure to the ink in the pressure chamber 28 to vibrate the meniscus of the nozzle 21 without ejecting ink droplets from the nozzle 21, and a non-vibration signal that does not vibrate the meniscus of the nozzle 21. The above drive waveforms also include a printing waveform used when printing on the print medium W and a dedicated waveform that is different from the printing waveform and is used to fill in recesses. The printing waveform and the dedicated waveform will be described in detail later.

[0042] The control device 71 executes a process of calculating the volume of a recess in the print medium W based on the imaging results of the imaging device 75, and a repair waveform generation process of causing the waveform generation circuit 76 to generate the dedicated waveform, which is a drive waveform for filling the recess, according to the volume of the recess. The control device 71 also executes a recess repair process of driving the actuator 60 with the dedicated waveform generated by the waveform generation circuit 76 and ejecting ink droplets from the nozzles 21 into the recess. The control device 71 corresponds to a calculation means, a repair waveform generation instruction means, and a recess repair instruction means.

[0043] The RAM 72 temporarily stores print jobs and the like received from an external computer 200 such as a personal computer via the network interface 70. The RAM 72 also temporarily stores ejection data and the like. The ROM 73 stores the droplet ejection program of this embodiment, control programs for performing various data processing, and the like.

[0044] The head driver IC 74 receives instructions from the control device 71 to cause the ejection head 20 to eject ink droplets. The light source driver IC 78 receives instructions from the control device 71 to cause the light source unit 40 to emit ultraviolet light. Furthermore, the motor driver IC 30 receives instructions from the control device 71 to control the drive of the transport motor 31. The transport motor 31 operates the transport rollers 15 to transport the print medium W in the transport direction Df, which is the transport direction. Furthermore, the motor driver IC 32 receives instructions from the control device 71 to control the drive of the carriage motor 33. The carriage motor 33 operates the carriage 16 to move the ejection head 20 in the movement direction Ds.

[0045] The recording medium reader 77 is a device that reads the droplet ejection program from a computer-readable recording medium KB, such as a flexible disk, CD (CD-ROM, CD-R, CD-RW, etc.), DVD (DVD-ROM, DVD-RAM, DVD-R, DVD+R, DVD-RW, DVD+RW, etc.), Blu-ray disk, magnetic disk, optical disk, or magneto-optical disk. The recording medium reader 77 may also be a device that reads the droplet ejection program from a recording medium such as a USB flash memory. The read droplet ejection program is stored in the ROM 73 and executed by the control device 71. The droplet ejection program of this embodiment may be stored in the ROM 73 from the external computer 200 via the network interface 70, or may be downloaded from the Internet and stored in the ROM 73.

[0046] FIG. 5 shows the dedicated waveform Ws and printing waveform Wp generated by the waveform generating circuit 76. As shown in FIG. 5, the printing waveform Wp is a drive waveform that has more ejection pulses Pp in one drive cycle as the volume of the ink droplet to be ejected increases. The printing waveform Wp shown as an example in FIG. 5 is a drive waveform for ejecting large ink droplets. The drive waveforms for ejecting medium-sized ink droplets and the drive waveforms for ejecting small ink droplets have fewer ejection pulses Pp in one drive cycle than the printing waveform Wp. In contrast, the dedicated waveform Ws is a drive waveform that has more ejection pulses Pp in one drive cycle than the printing waveform Wp. In FIG. 5, the printing waveform Wp has three ejection pulses Pp, while the dedicated waveform Ws has four or five ejection pulses Pp.

[0047] The printing waveform Wp is a drive waveform that includes a pre-pulse Pr positioned at the beginning of one drive cycle, a cancel pulse Pc positioned at the end of one drive cycle, or both a pre-pulse Pr and a cancel pulse Pc within one drive cycle. The pre-pulse Pr is a pulse that vibrates the meniscus to improve ejection performance, and the cancel pulse Pc is a pulse that suppresses residual vibrations that affect the drive waveform in the next drive cycle. In Figure 5, the printing waveform Wp includes a pre-pulse Pr and a cancel pulse Pc within one drive cycle. In contrast, the dedicated waveform Wp is a waveform that includes at least one drive cycle that does not include either a pre-pulse Pr or a cancel pulse Pc. Figure 5 illustrates one drive cycle that does not include either a pre-pulse Pr or a cancel pulse Pc.

[0048] In this embodiment, when performing recess repair to fill recesses present on the print medium W, the control device 71 determines, in terms of shortening the processing time, whether to eject ink while moving the ejection head 20B using the carriage 16, or while stopping the ejection head 20B, depending on the recess. The time required to complete the recess repair process by having the ejection head 20B eject ink droplets while moving the carriage 16 in the movement direction Ds is referred to as the moving ejection time Th1. In contrast, the time required to complete the recess repair process by having the ejection head 20B eject ink droplets while the carriage 16 is stopped is referred to as the stop ejection time Th2. Below, the method of calculating the moving ejection time Th1 and the stop ejection time Th2 calculated by the control device 71 will be described in detail.

[0049] In this embodiment, if the resolution is K (dpi), then per dot, (25.4 / K) 2 [mm 2 / dot]. The area of ​​the part to be filled in one pass is S [mm 2 ], then for the part to be filled, S × (K / 25.4) 2 You can print the dots in one pass.

[0050] Next, if the time required for the nozzle row NL of the ejection head 20B to pass through the recess in the movement direction Ds is T, the ejection amount per unit time is S×(K / 25.4) 2 If the number of ink droplets (dots) required to fill the recesses is X, the time required to repair the recesses, i.e., the moving ejection time Th1, is X / (S×(K / 25.4) 2 / T) [sec]. In this case, the control device 71 uses the smallest value of the plurality of movement speeds of the carriage 16 in calculating the movement ejection time Th1.

[0051] Next, the calculation method for the stop discharge time Th2 is as follows. If the discharge frequency of the discharge head 20B is F [kHz] and the number of nozzles used to repair the recessed portion is W [number], the discharge amount per unit time is 1000 × W × F [dot / s]. If the number of times the discharge head 20B is stopped is N, the discharge amount per unit time per stop is 1000 × W × F / N [dot / s].

[0052] Then, as in the case of calculating the moving ejection time Th1, if the number of ink droplets required to fill the recess is X, the time required to repair the recess, i.e., the stopped ejection time Th2, can be calculated as X / (1000×W×F / N) [sec].

[0053] The dynamic discharge time Th1 and the stop discharge time Th2 will be described below with reference to specific examples. Fig. 6 is a diagram illustrating the dynamic discharge time Th1 and the stop discharge time Th2 when filling recess d1 on the print medium W. Fig. 7 is a diagram illustrating the dynamic discharge time Th1 and the stop discharge time Th2 when filling recess d2 on the print medium W. Fig. 8 is a diagram illustrating the dynamic discharge time Th1 and the stop discharge time Th2 when filling recess d3 on the print medium W. Note that in Figs. 6 to 8, Fig. 12 (described later), and Fig. 15 (described later), the dimension in the transport direction Df of the print medium W corresponds to one pass.

[0054] In the ejection head 20B of FIGS. 6 to 8, the two nozzle rows NL that eject white ink droplets are designated as nozzle rows NLW1 and NLW2, and the two nozzle rows NL that eject clear ink droplets are designated as nozzle rows NLC1 and NLC2.

[0055] In the following explanation, recesses d1, d2, and d3 are filled using only one nozzle row NL, that is, nozzle row NLW2. In Fig. 6, the time T1 required for nozzle row NLW2 of ejection head 20B to pass recess d1 in the movement direction Ds is set to 0.05 seconds. The required time T1 is calculated by control device 71 from the movement speed of ejection head 20B (movement speed of carriage 16) and the dimension of recess d1 in the movement direction Ds based on the image capture results by imaging device 75. The same applies to required times T2 and T3 described below.

[0056] Here, when the ejection frequency F is 10 [kHz], the time required to print one dot is 0.0001 [sec]. Also, as shown in FIG. 6, the number of nozzles 21 in the nozzle row NLW2 that can fill the recess d1 is nine. The above numerical values ​​and the area per dot (25.4 / K) 2 If we assume that there is almost no overlap between the dots printed, the area S of the recess d1 is (0.05 / 0.0001) × 9 × (25.4 / K) 2 Therefore, the ejection amount per unit time from the nozzle row NLW2 is calculated as follows: (0.05 / 0.0001)×9×(25.4 / K) 2 ×(K / 25.4) 2 With / T1, the result is 4500 / 0.05=90000 [dot / s].

[0057] If the number of dots X required to fill the recess d1 is 6000 dots, for example, the moving discharge time Th1 is 6000 / 90000.

[0058] On the other hand, the discharge stop time Th2 can be calculated by X / (1000×W×F / N) [sec] as described above. In this case, the discharge stop time Th2 is 6000 / (1000×9×10 / 1)=6000 / 90000.

[0059] 6, the moving ejection time Th1 and the stop ejection time Th2 are the same value. In this case, taking into account the small time loss due to acceleration and deceleration when the carriage 16 is stopped, the control device 71 creates a profile for ejecting while moving the ejection head 20B during the recess repair process. As described above, when filling the recess d1, ejection is performed while moving the ejection head 20B.

[0060] Next, the filling of the recess d2 will be described with reference to Fig. 7. The shape of the recess d2 is different from the shape of the recess d1. The calculation method of the dynamic ejection time Th1 and the pause ejection time Th2 in the process of filling the recess d2 is basically the same as in the case of filling the recess d1.

[0061] In Figure 7, the time T2 required for the nozzle row NLW2 of the ejection head 20B to pass through the recessed portion d2 is set to 0.13 seconds. Also, as shown in Figure 7, the number of nozzles 21 in the nozzle row NLW2 that can fill the recessed portion d2 is five. Using these values ​​and the above-mentioned area per dot (25.4 / K), 2 If we assume that there is almost no overlap between the dots, the area S of the recess d2 is (0.13 / 0.0001) × 5 × (25.4 / K) 2 Therefore, the ejection amount per unit time from the nozzle row NLW2 is calculated as follows: (0.13 / 0.0001)×5×(25.4 / K) 2 ×(K / 25.4) 2 With / T2, the result is 6500 / 0.13=50000 [dot / s].

[0062] Next, assuming that the number of dots X required to fill the recessed portion d2 is 10,000 dots, for example, the moving ejection time Th1 is 10,000 / 50,000. On the other hand, the stopping ejection time Th2 is 10,000 / (1,000 x 5 x 10 / 2) = 20,000 / 50,000. Note that, taking into consideration the fluidity of the ink droplets into the recessed portion d2, it is desirable to stop the carriage 16 once every 0.07 seconds of the required time T, so the number of stops N is set to 2.

[0063] 7, since the stop discharge time Th2 is longer than the moving discharge time Th1, the control device 71 creates a profile for discharging while moving the discharge head 20B during the recess repair process. As described above, discharge is performed while moving the discharge head 20B when filling the recess d2.

[0064] Next, the filling of the recess d3 will be described with reference to Fig. 8. The shape of the recess d3 is different from the shapes of the recesses d1 and d2. The calculation method of the dynamic ejection time Th1 and the pause ejection time Th2 in the process of filling the recess d3 is basically the same as when filling the recesses d1 and d2.

[0065] In Figure 8, the time T3 required for the nozzle row NLW2 of the ejection head 20B to pass through the recessed portion d3 is set to 0.05 seconds. Also, as shown in Figure 8, the number of nozzles 21 in the nozzle row NLW2 that can fill the recessed portion d3 is seven. The above numerical values ​​and the area per dot (25.4 / K) 2 Therefore, if we assume that there is almost no overlap between the dots, the area S of the recess d3 is (0.05 / 0.0001) × 7 × (25.4 / K) 2 Therefore, the ejection amount per unit time from the nozzle row NLW2 is calculated as follows: (0.05 / 0.0001)×7×(25.4 / K) 2 ×(K / 25.4) 2 With / T3, the result is 3500 / 0.05=70000 [dot / s].

[0066] For example, if the number of dots X required to fill the recess d3 is 7000 dots, the moving discharge time Th1 is 7000 / 70000. On the other hand, the stopping discharge time Th2 is 7000 / (1000×7×10 / 1)=7000 / 70000.

[0067] 8, the moving ejection time Th1 and the stop ejection time Th2 have the same value. In this case, taking into account the small time loss due to acceleration and deceleration when stopping the carriage 16, the control device 71 creates a profile for ejecting while moving the ejection head 20B during the recess repair process. As described above, when filling recess d3, ejection is performed while moving the ejection head 20B, in the same way as when filling recess d1.

[0068] After the recesses d1, d2, and d3 are repaired using the profile corresponding to the recesses d1, d2, and d3, printing is performed by ejecting white ink droplets, the same as the ink droplets used for repair, onto the print medium W. Then, as needed, normal printing of patterns, pictures, etc. can be performed using the ejection head 20A onto the print medium W onto which the white ink droplets have been ejected. Note that it is desirable to perform a purge process for the ejection head 20A all at once immediately before the normal printing, in order to reduce the number of purging operations.

[0069] Hereinafter, a series of processes performed by the control device 71 will be described with reference to flowcharts. Fig. 9 is a flowchart showing a main routine of the recess repair process performed by the control device 71, and Figs. 10 and 11 are flowcharts showing a repair printing subroutine in the flowchart of Fig. 9.

[0070] 9, the control device 71 causes the imaging device 75 to capture an image of the surface of the print medium W (step S1). As a result, the imaging device 75 obtains information about the surface of the print medium W as the imaging result.

[0071] Next, the control device 71 calculates the depth and volume of the recesses in the print medium W based on the image capture results from the imaging device 75, and determines whether or not a recess exists on the print medium W based on the calculation results (step S2). In this case, the control device 71 can determine that a recess exists on the print medium W if the value of the recess depth or volume is equal to or greater than a threshold value. If it is determined that recesses d1, d2, and d3 exist on the print medium W (YES in step S2), the control device 71 stores the positions of the recesses d1, d2, and d3 on the print medium W in the RAM 72 (step S3). On the other hand, if no recesses exist on the print medium W (NO in step S2), the control device 71 ends the process.

[0072] After the processing of step S3, the control device 71 estimates the current amount of ink in the recesses d1, d2, and d3 (step S4) based on the image capture results of the image capture device 75. Then, the control device 71 estimates the amount of ink required for the portions corresponding to the recesses d1, d2, and d3 (i.e., the portions that should be printed without the recesses d1, d2, and d3 being present) based on the ejection data (step S5).

[0073] Next, the control device 71 subtracts the ink amount estimated in step S4 from the ink amount estimated in step S5 to obtain the ink amount required to repair the recesses (step S6).The control device 71 then creates repair data for repairing the recesses d1, d2, and d3 (step S7).After these processes, the control device 71 executes repair printing (step S8).Repair printing will be described below with reference to a flowchart.

[0074] 10, the control device 71 acquires the number L of recesses in one pass based on the recess position information in step S3 described above (step S11). Next, the control device 71 sets the Mth recess out of the L recesses as a target for repair (step S12), and calculates the moving discharge time Th1 and the stopping discharge time Th2 for that recess as described above (step S13). As a result, the moving discharge time Th1 and the stopping discharge time Th2 corresponding to the recess on the print medium W are calculated.

[0075] If the calculated moving discharge time Th1 is equal to or shorter than the stop discharge time Th2 (YES in step S14), the control device 71 creates a profile (moving repair profile) for discharging while moving the discharge head 20B (step S15). On the other hand, if the moving discharge time Th1 exceeds the stop discharge time Th2 (NO in step S14), the control device 71 creates a profile (stop repair profile) for discharging while the discharge head 20B is stopped (step S16).

[0076] After the processing of step S15 and step S16, the control device 71 determines whether or not profiles have been created for all L recesses (step S17), and if all profiles have been created (YES in step S17), causes the ejection head 20B to print for one pass (step S18). On the other hand, if not all profiles have been created (NO in step S17), the control device 71 sets M=M+1 (step S19), returns to the processing of step S12 described above, and repeats the subsequent processing.

[0077] After the process of step S18, the control device 71 causes the imaging device 75 to capture an image of the repaired portion and calculates the depth of the repaired portion based on the captured image (step S20). Next, the control device 71 determines whether the calculated depth is less than a predetermined value (step S21 in FIG. 11). If the calculated depth is equal to or greater than the predetermined value (NO in step S21), the control device 71 causes the ejection head 20B to perform additional printing to reduce the depth to less than the predetermined value (step S22). In this case, if the recess cannot be completely filled in one pass, i.e., if it is not possible to eject ink droplets in a volume equivalent to the volume of the recess in one pass, the recess is repaired in an additional pass. This allows the recess to be repaired in a state where it is almost completely filled. Note that the predetermined value is, for example, 20 nm, but is not limited to this. In addition, the ROM 73 stores a profile (moving repair profile) for ejecting ink while moving the ejection head 20B for the additional pass. In the additional pass, the control device 71 uses the moving repair profile for the additional pass to eject from the ejection head 20B an amount of ink sufficient to fill the depth equivalent to the predetermined value.

[0078] After the process of step S22 and if the depth is less than the predetermined value (YES in step S21), the control device 71 determines whether printing has been completed for all passes (step S23). If printing for all passes has been completed (YES in step S23), the control device 71 ends the process. On the other hand, if printing for all passes has not been completed (NO in step S23), the control device 71 drives the transport roller 15 to transport the print medium W in the transport direction Df (step S24), and then returns to the process of step S11 described above and repeats the subsequent processes.

[0079] (Second embodiment) Next, the processing of the control device 71 in the second embodiment will be described. The second embodiment differs from the first embodiment in that the processing for calculating the moving ejection time Th1 and the stop ejection time Th2, which are the repair times in FIG. 10 of the first embodiment, is not performed. That is, the control device 71 determines whether to create a moving repair profile or a stop repair profile based on a comparison between the amount of ink required for repair and the amount of ink that can be ejected while moving the ejection head 20B. A specific example will be described below.

[0080] In this embodiment, an example will be described in which recesses d1 (see FIG. 6 above), d2 (see FIG. 7 above), and d3 (see FIG. 8 above) are filled using two nozzle rows NL, NLW1 and NLW2. In the following description, reference will be made to FIGS. 6 to 8, which were used in the description of the first embodiment, as appropriate.

[0081] In this embodiment, the amount of ink required to repair the recess d1, calculated in step S6 in FIG. 9, is 6,000 dots. As described in the first embodiment, the amount of ink ejected per unit time by the nozzle array NLW2 is 4,500 / 0.05 = 90,000 dots / s. Also, as in the first embodiment, the required time T1 is 0.05 seconds. Based on these assumptions, when two nozzle arrays NLW1 and NLW2 are used in this embodiment, ink droplets of 90,000 × 0.05 s × 2 arrays = 9,000 dots can be ejected. Therefore, the amount of ink that can be ejected by the nozzle arrays NLW1 and NLW2 of the moving ejection head 20B is greater than the amount of ink required for repair. Therefore, the control device 71 determines that printing while moving the ejection head 20B is possible and creates a moving repair profile.

[0082] The following example will be described. Assume that the amount of ink required to repair the recess d2, calculated in step S6 in FIG. 9, is 15,000 dots. As described in the first embodiment, the ejection amount per unit time by the nozzle array NLW2 is 6,500 / 0.13 = 50,000 dots / s. Also, as in the first embodiment, the required time T2 is 0.13 seconds. Based on these assumptions, if two nozzle arrays NLW1 and NLW2 are used in this embodiment, ink droplets of 50,000 × 0.13 s × 2 arrays = 13,000 dots can be ejected. Therefore, the amount of ink that can be ejected by the nozzle arrays NLW1 and NLW2 of the moving ejection head 20B is less than the amount of ink required for repair. Therefore, printing while moving the ejection head 20B cannot completely repair the recess d2. Therefore, the control device 71 determines that printing while moving the ejection head 20B is impossible and creates a stationary repair profile.

[0083] In this case, printing can be performed by stopping the ejection head 20B, for example, twice, as shown in FIG. 12. As shown in the upper part of FIG. 12, ink droplets are ejected while the nozzle arrays NLW1 and NLW2 of the ejection head 20B are stopped above the upstream portion of the recess d2, and then ink droplets are ejected while the nozzle arrays NLW1 and NLW2 are stopped above the downstream portion of the recess d2. Note that, of the 15,000 dots of ink required to repair the recess d2, for example, 10,000 dots can be ejected during the first stop, and the remaining 5,000 dots can be ejected during the second stop. Alternatively, of the 15,000 dots, for example, 7,500 dots can be ejected during the first stop, and the remaining 7,500 dots can be ejected during the second stop.

[0084] The following example will be described. Assume that the amount of ink required to repair the recess d3, calculated in step S6 in FIG. 9, is 7,000 dots. As described in the first embodiment, the ejection amount per unit time by the nozzle array NLW2 is 3,500 / 0.05 = 70,000 dots / s. Also, as in the first embodiment, the required time T3 is 0.05 seconds. Based on these assumptions, if two nozzle arrays NLW1 and NLW2 are used in this embodiment, ink droplets of 70,000 × 0.05 s × 2 arrays = 7,000 dots can be ejected. Therefore, the amount of ink that can be ejected by the nozzle arrays NLW1 and NLW2 of the moving ejection head 20B is equal to the amount of ink required for repair. In this case, the control device 71 determines that printing while moving the ejection head 20B is possible and creates a moving repair profile.

[0085] 13 and 14 are flowcharts showing a subroutine for repair printing in the second embodiment.

[0086] 13, the control device 71 acquires the number L of recesses in one pass based on the position information of the recesses in the above-mentioned step S3 (step S31). Next, the control device 71 sets the Mth recess among the L recesses as a repair target (step S32).

[0087] Next, the control device 71 determines whether printing can be performed while moving the ejection head 20B (step S33). In this case, the control device 71 makes this determination based on a comparison between the amount of ink required for repair and the amount of ink that can be ejected while moving the ejection head 20B, as described above.

[0088] If printing can be performed while moving the ejection head 20B (YES in step S33), the control device 71 creates a moving restoration profile (step S34). On the other hand, if printing cannot be performed while moving the ejection head 20B (NO in step S33), the control device 71 creates a stationary restoration profile (step S35).

[0089] After the processing of step S34 and step S35, the control device 71 determines whether or not profiles have been created for all L recesses (step S36), and if all profiles have been created (YES in step S36), causes the ejection head 20B to print for one pass (step S37). On the other hand, if not all profiles have been created (NO in step S36), the control device 71 sets M=M+1 (step S38), returns to the processing of step S32 described above, and repeats the subsequent processing.

[0090] After the process of step S37, the control device 71 causes the imaging device 75 to capture an image of the repaired portion and calculates the depth of the repaired portion based on the image capture result (step S39).The control device 71 then determines whether the calculated depth is less than a predetermined value (step S40 in FIG. 14), and if the depth is equal to or greater than the predetermined value (NO in step S40), causes the ejection head 20B to perform additional printing to make the depth less than the predetermined value (step S41).

[0091] After the process of step S41 and if the depth is less than the predetermined value (YES in step S40), the control device 71 determines whether printing has been completed for all passes (step S42). If printing for all passes has been completed (YES in step S42), the control device 71 ends the process. On the other hand, if printing for all passes has not been completed (NO in step S42), the control device 71 drives the transport roller 15 to transport the print medium W in the transport direction Df (step S43), and then returns to the process of step S31 described above and repeats the subsequent processes.

[0092] (Third embodiment) Next, the stopping position of the ejection head 20B when printing on multiple recesses present on the print medium W while the ejection head 20B is stopped will be described with reference to the drawings. FIG. 15 is a diagram for explaining the stopping position of the ejection head 20B when printing on multiple recesses present on the print medium W while the ejection head 20B is stopped. The upper diagram in FIG. 15 shows the positions of recesses d10, d11, d12, d13, d14, d15, d16, and d17. The lower diagram in FIG. 15 shows the stopping positions of the ejection head 20B with wavy lines. Note that in the description of FIG. 15, all four nozzle rows NL of the ejection head 20B are assumed to eject white ink droplets. In the following description of FIG. 15, the four nozzle rows NL will be referred to as the first nozzle row NL, second nozzle row NL, third nozzle row NL, and fourth nozzle row NL from the side of one direction Ds1 in the movement direction Ds. Also, for ease of understanding, the position of the first nozzle row NL is aligned with the left end (end on the one direction Ds1 side) of the ejection head 20B, and the position of the fourth nozzle row NL is aligned with the right end (end on the other direction Ds2 side) of the ejection head 20B.

[0093] The control device 71 acquires the positions of the recesses on the print medium W in the same manner as described above. In Fig. 15, the control device 71 acquires the positions of the recesses d10, d11, d12, d13, d14, d15, d16, and d17. That is, the control device 71 stores the positions of the recesses d10, d11, d12, d13, d14, d15, d16, and d17 on the print medium W in the RAM 72.

[0094] Then, the control device 71 starts printing by positioning the first nozzle row NL, which is the one-end nozzle row located at the end in one direction Ds1 of the movement direction Ds among the multiple nozzle rows NL of the ejection head 20B, at the end on the one direction Ds1 side of the recess d10 located at the end in one direction Ds1.

[0095] When the first nozzle row NL is positioned at the end of the first direction Ds1 as described above, a recess may be present that extends beyond the fourth nozzle row NL, which is the other-end nozzle row positioned at the farthest end of the four nozzle rows NL in the other direction Ds2 of the movement direction Ds, and is divided by the fourth nozzle row NL in a plan view. In FIG. 15, recesses d12 and d16 correspond to the divided recesses. In such a case, the control device 71 performs the next printing with the first nozzle row NL, which is the one-end nozzle row, positioned at the dividing point of recess d12 (recess d16). That is, printing is performed on recess d12 by dividing it into three recesses d121, d122, and d123, and printing is performed on recess d16 by dividing it into two recesses d161 and d162.

[0096] FIG. 16 is a cross-sectional view showing the printing nozzle 21 and the recess repair nozzle 121. As shown in FIG. 16, the recess repair nozzle 121 may be used during the recess repair process. In other words, the discharge head 20B has the recess repair nozzle 121. The recess repair nozzle 121 has a nozzle hole 121a with a larger diameter than the printing nozzle 21. By using the recess repair nozzle 121 with a nozzle hole 121a with a larger diameter in this way, the discharge amount per unit time can be increased, and therefore the time required for the process can be shortened.

[0097] As described above, according to the droplet ejection device 10 of the above embodiment, the volume of the recessed portion in the print medium W is calculated by the control device 71 based on the imaging results of the imaging device 75. This makes it possible to obtain the accurate volume of the recessed portion. The control device 71 then executes a recessed portion repair process in which the actuator 60 is driven by a drive waveform generated by the waveform generation circuit 76. In this way, a drive waveform according to the volume of the recessed portion in the print medium W is used, so the recessed portion can be filled in just the right amount. This makes it possible to avoid ejecting excessive ink droplets into the recessed portion, and therefore the recessed portion can be filled in a shorter time than before.

[0098] In addition, in the above embodiment, a dedicated waveform Ws, which has a larger number of ejection pulses Pp per drive cycle than the printing waveform Wp, is used when repairing recesses. This shortens the time required to fill the recesses with ink droplets. This allows recess repair to be completed in a short time.

[0099] Furthermore, in the above embodiment, the dedicated waveform Ws includes at least one drive period that does not include either a pre-pulse Pr or a cancel pulse Pc, which allows many ejection pulses Pp to be arranged within that drive period.

[0100] Furthermore, in the above embodiment, when the moving discharge time Th1 is equal to or shorter than the stop discharge time Th2, the control device 71 creates a moving repair profile for discharging while moving the discharge head 20B. On the other hand, when the moving discharge time Th1 exceeds the stop discharge time Th2, the control device 71 creates a stop repair profile for discharging while the discharge head 20B is stopped. This makes it possible to select the shorter printing time between printing while moving the discharge head 20B and printing while the discharge head 20B is stopped.

[0101] In the above embodiment, the control device 71 calculates the moving discharge time Th1 by using the minimum value among the multiple moving speeds of the carriage 16. In this case, the above-mentioned S×(K / 25.4) which is the calculation formula for the discharge amount per unit time is used. 2 The maximum value can be used as the required time T in / T [dot / s]. This makes it possible to compare the moving ejection time Th1 and the stopping ejection time Th2, which are calculated taking into account the minimum value of the ejection amount per unit time.

[0102] Furthermore, in the above embodiment, when the first nozzle row NL is positioned at the end on the one side of the direction Ds1, there may be a recess that extends beyond the fourth nozzle row NL, which is the other-end nozzle row located at the farthest end in the other direction Ds2 of the movement direction Ds among the four nozzle rows NL, in the other direction Ds2, and is divided by the fourth nozzle row NL in a plan view. In such a case, the control device 71 performs the next printing with the first nozzle row NL, which is the one-end nozzle row, positioned at the dividing point of the recess d12 (recess d16). This minimizes the number of times the ejection head 20B is stopped.

[0103] Furthermore, in the above embodiment, the control device 71 calculates the depth of the repaired portion, and if the depth is equal to or greater than a predetermined value of 20 nm, the control device 71 causes the ejection head 20B to perform additional printing to reduce the depth to less than 20 nm. This allows the recess to be reliably filled and repaired.

[0104] Furthermore, in the above embodiment, by using a recess repair nozzle 121 with a nozzle hole 121a having a large diameter during printing, it is possible to increase the amount of ink discharged per unit time, thereby shortening the processing time.

[0105] (Variation) The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, the following modifications are possible.

[0106] In the above embodiment, an imaging device 75 was used as an example of a surface information acquisition device, but this is not limited to this, and a measuring device that measures specularly reflected light or diffused light from the printing medium W can also be used as a surface information acquisition device.

[0107] Furthermore, in the above embodiment, the recess repair nozzle 121 is used, but it is not essential to use the recess repair nozzle 121, and printing may be performed using the printing nozzle 21.

[0108] Furthermore, in the above embodiment, the voltage value of the ejection pulse Pp of the dedicated waveform Ws is set to a constant value, but this is not limited to this, and the voltage value may be adjusted depending on the depth or volume of the recess.

[0109] In the above embodiment, when the control device 71 causes the ejection head 20B to perform additional printing in step S21 to make the depth less than the predetermined value, the control device 71 causes the ejection head 20B to eject an amount of ink sufficient to fill the recessed portion by a depth corresponding to the predetermined value, but this is not limited to this. The control device 71 may estimate the current amount of ink equivalent to step S4 based on the image capture result of the image capture device 75, and may re-estimate the amount of ink required for the recessed portion based on the ejection data.

[0110] In the above embodiment, when the control device 71 causes the discharge head 20B to perform additional printing in step S21 to make the depth less than a predetermined value, a profile (moving repair profile) for discharging while moving the discharge head 20B for the additional pass is stored in the ROM 73, and the control device 71 uses the moving repair profile for the additional pass in the additional pass. However, this is not limited to this, and the ROM 73 may store a profile (stationary repair profile) for discharging while the discharge head 20B for the additional pass is stationary, and the control device 71 may use the stationary repair profile for the additional pass in the additional pass. [Explanation of symbols]

[0111] 1 Image recording device 10 Droplet discharge device 16 Carriage 20, 20A, 20B Discharge Head 21 Printing nozzle 21a Nozzle hole 28 Pressure Chamber 40, 40A, 40B Light Source Unit 60 Actuator 71 Control device 75 Imaging device 76 Waveform generation circuit 121 Depression repair nozzle 121a Nozzle hole Ds moving direction Ds1 One direction of movement Ds2 Other direction of movement d1,d2,d3,d10,d11,d12,d13,d14,d15,d16,d17,d121,d122,d123,d161,d162 recess NL nozzle row Pp Discharge pulse Pr prepulse Pc Cancel Pulse Th1 moving discharge time Th2 stop discharge time W Printing medium Wp printing waveform Ws dedicated waveform

Claims

1. an ejection head having a nozzle that ejects droplets onto a print medium and an actuator that applies pressure to liquid in a pressure chamber that communicates with the nozzle; a waveform generating circuit that generates a drive waveform of a signal that drives the actuator; a surface information acquisition device for acquiring information about the surface of the printing medium; a control device; The control device A process of calculating the volume of a recessed portion in the printing medium based on the results of acquisition by the surface information acquisition device; a process of creating repair data for repairing the recess after the calculation process; a restoration waveform generation process for causing the waveform generation circuit to generate a drive waveform for filling the recess in accordance with the volume of the recess; a recess repair process for driving the actuator by the drive waveform generated by the waveform generation circuit and discharging the droplet from the nozzle into the recess.

2. the drive waveform includes a printing waveform used when printing on the print medium and a waveform that is different from the printing waveform and is dedicated to filling the recesses, The droplet ejection device according to claim 1 , wherein the control device causes the waveform generation circuit to generate the dedicated waveform in the restoration waveform generation process.

3. 3. The droplet ejection device according to claim 2, wherein the printing waveform has more ejection pulses in one drive cycle as the volume of the ejected droplet increases, and the dedicated waveform has more ejection pulses in one drive cycle than any of the printing waveforms.

4. the printing waveform is a waveform that includes, within one drive cycle, either a pre-pulse positioned at the beginning of the one drive cycle, a cancel pulse positioned at the end of the one drive cycle, or the pre-pulse and the cancel pulse; The droplet ejection device according to claim 3 , wherein the dedicated waveform is a waveform that includes at least one of the driving cycles that does not include either the pre-pulse or the cancel pulse.

5. An ejection head having a nozzle that ejects droplets onto a print medium and an actuator that applies pressure to liquid in a pressure chamber that communicates with the nozzle; a waveform generating circuit that generates a drive waveform of a signal that drives the actuator; a surface information acquisition device for acquiring information about the surface of the printing medium; a control device; a carriage that moves the ejection head in a movement direction; The control device A process of calculating the volume of a recessed portion in the printing medium based on the results of acquisition by the surface information acquisition device; a restoration waveform generation process for causing the waveform generation circuit to generate a drive waveform for filling the recess in accordance with the volume of the recess; a recess repair process in which the actuator is driven by the drive waveform generated by the waveform generation circuit, and the droplet is ejected from the nozzle into the recess; a movement ejection time, which is the time required to complete the recess repair process by ejecting droplets from the ejection head while moving the carriage in the movement direction, and a stop ejection time, which is the time required to complete the recess repair process by ejecting droplets from the ejection head while the carriage is stopped; and If the moving ejection time is equal to or less than the stop ejection time, the carriage is moved in the moving direction to perform the recess repair process, and if the moving ejection time is greater than the stop ejection time, the carriage is stopped to perform the recess repair process; and The control device is capable of moving the carriage at one of a plurality of movement speeds while causing the ejection head to eject droplets, and the minimum value of the plurality of movement speeds is used to calculate the movement ejection time.

6. the ejection head has a plurality of nozzle rows arranged in parallel in the movement direction, The control device When the carriage is stopped and the recess repair process is performed, obtaining the position of the recessed portion on the printing medium; performing the recess repair process in a state in which a one-end-side nozzle row, which is located at the end of one end in the one direction of the movement direction among the plurality of nozzle rows of the ejection head, is positioned at an end on the one-direction side of the recess which is located at the end of the one direction in the movement direction; 6. A droplet ejection device as described in claim 5, wherein, when the one-end nozzle row is positioned at the end on the one side, if there is a recess facing the other-end nozzle row that is located at the end of the other direction of the movement direction among the multiple nozzle rows, the next recess repair process is performed with the one-end nozzle row positioned at the division point of the recess divided by the one-end nozzle row and the other-end nozzle row.

7. the droplets are ultraviolet-curable ink droplets, a light source unit mounted on the carriage for irradiating ultraviolet light to harden the ink droplets ejected from the nozzles; the control device, after the ink droplets ejected into the recesses by the recess repair process are hardened by ultraviolet light irradiated from the light source unit, acquires again information about the surface of the printing medium by the surface information acquisition device; A droplet ejection device as described in claim 5 or 6, which calculates the depth of the recess after the recess repair process is performed based on the results of the surface information acquisition device's re-acquisition, and performs the recess repair process again if the calculated depth is 20 nm or more.

8. An ejection head having a nozzle that ejects droplets onto a print medium; a waveform generating circuit that generates a drive waveform for ejecting the droplets from the ejection head; a surface information acquisition device for acquiring information about the surface of the printing medium; a control device; The control device A process of calculating the volume of a recessed portion in the printing medium based on the results of acquisition by the surface information acquisition device; a process of creating repair data for repairing the recess after the calculation process; a restoration waveform generation process for causing the waveform generation circuit to generate a drive waveform for filling the recess in accordance with the volume of the recess; a recess repair process for ejecting the droplets from the nozzles onto the recesses using the drive waveform generated by the waveform generation circuit; The droplet ejection device, wherein the nozzles include a printing nozzle and a recess repair nozzle having a nozzle hole with a larger diameter than the printing nozzle, and the recess repair nozzle is used in the recess repair process.

9. Obtaining information about the surface of the print medium; calculating a volume of the recessed portion in the printing medium based on the acquired information; creating repair data for repairing the recess; generating a drive waveform for filling the recess in accordance with the volume of the recess; The droplet ejection method includes driving an actuator with the generated drive waveform to apply pressure to liquid in a pressure chamber communicating with a nozzle, thereby ejecting droplets from the nozzle into the recess.

10. A droplet ejection program to be executed by a computer in a droplet ejection device including a nozzle that ejects droplets onto a print medium and an actuator that applies pressure to liquid in a pressure chamber that communicates with the nozzle, a waveform generation circuit that generates a drive waveform for a signal that drives the actuator, a surface information acquisition device that acquires information about the surface of the print medium, and a control device, The computer a calculation means for calculating the volume of a recessed portion in the printing medium based on the results of the surface information acquisition device; a means for creating repair data for repairing the recess after the calculation of the volume of the recess by the calculation means; a restoration waveform generation instruction means for causing the waveform generation circuit to generate a drive waveform for filling the recess in accordance with the volume of the recess; and a droplet ejection program that functions as a recess repair instruction means that drives the actuator with the drive waveform generated by the waveform generation circuit and ejects the droplet from the nozzle onto the recess;

Images