Liquid discharge apparatus and liquid discharge method

Abstract

A liquid discharge apparatus includes a head that discharges liquid onto an object and a moving mechanism that causes relative movement between the head and the object. The head discharges the liquid that lands on the object. The moving mechanism moves the head relative to the object in a first direction that is perpendicular to a second direction. The head discharges the liquid onto a discharge region on the object. The discharge region has a downstream end region in the first direction. The downstream end region defines a trailing end region. The liquid, that is landed on the trailing end region, has a length in the second direction that is smaller than a length in the second direction of the liquid landed on a region of the discharge region, that is other than the trailing end region.

Description

[DESCRIPTION][Title of Invention]LIQUID DISCHARGE APPARATUS AND LIQUID DISCHARGE METHOD [Technical Field]

[0001] Embodiments of the present invention relate to a liquid discharge apparatus and a liquid discharge method.[Background Art]

[0002] A liquid discharge apparatus in which a head discharges liquid onto an object is known.

[0003] For example, Patent Literature (PTL) 1 discloses an inkjet printer that prints an upstream end of an image at a decreased resolution changed from a preset resolution so as to reduce effect caused by secondary droplets.[Citation List][Patent Literature]

[0004] [PTL 1]Japanese Unexamined Patent Application Publication No. 2015-024599 [Summary of Invention] [Technical Problem]

[0005] However, the inkjet printer disclosed by PTL 1 is to improve the effect caused by the secondary droplets in a downstream end of the image.

[0006] It is an objective of the present invention to reduce the effect caused by the secondary droplets.[Solution to Problem]

[0007] A liquid discharge apparatus according to an embodiment of the present invention includes a head and a moving mechanism. The head discharges liquid onto an object. The moving mechanism causes relative movement between the head and the object. The head discharges the liquid that lands on the object. The moving mechanism moves the head relative to the object in a first direction that is perpendicular to a second direction. The head discharges the liquid in a discharge region on the object, that includes a downstream end region in the first direction. The downstream end region defines a trailing end region. The liquid landed on the trailing end region has a length in the second direction, that is smaller than a length in the second direction of the liquid landed on a region of the discharge region, that is other than the trailing end region.[Advantageous Effects of Invention]

[0008] The liquid discharge apparatus according to an embodiment of the present invention reduces the effect caused by the secondary droplets.[Brief Description of Drawings]

[0009] A more complete appreciation of embodiments of the present disclosure and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to the accompanying drawings.

[0010] [Fig. 1]FIG. 1 is a view of a liquid discharge apparatus according to a first embodiment of the present invention, illustrating an entire construction thereof.[Fig. 2]FIG. 2 is a perspective view of a head incorporated in the liquid discharge apparatus according to the first embodiment of the present invention, illustrating a construction of the head.[Fig. 3]FIG. 3 is a cross-sectional view of the head, taken on a plane S 1 depicted in FIG. 2.[Fig. 4]FIG. 4 is a view of a supply portion incorporated in the liquid discharge apparatus according to the first embodiment of the present invention, illustrating a construction of the supply portion.[Fig. 5]FIG. 5 is a block diagram of the liquid discharge apparatus according to the first embodiment of the present invention, illustrating a configuration thereof.[Fig. 6]FIG. 6 is a block diagram of a controller incorporated in the liquid discharge apparatus according to the first embodiment of the present invention, illustrating a functional configuration of the controller.[Fig. 7]FIG. 7 is a view of a relative movement path through which the head of the liquid discharge apparatus according to the first embodiment of the present invention moves relative to an object, as one example of the relative movement path.[Fig. 8]FIG. 8 is a diagram of a liquid droplet discharged from the liquid discharge apparatus according to the first embodiment of the present invention, illustrating a first example of a state of the liquid droplet.[Fig. 9]FIG. 9 is a diagram of dots produced by the liquid droplet depicted in FIG. 8.[Fig. 10]FIG. 10 is a diagram of a liquid droplet discharged from the liquid discharge apparatus according to the first embodiment of the present invention, illustrating a second example of a state of the liquid droplet.[Fig. 11]FIG. 11 is a diagram of dots produced by the liquid droplet depicted in FIG. 10.[Fig. 12]FIG. 12 is a diagram of dots landed on the object from the liquid discharge apparatus according to the first embodiment of the present invention, as a first example.[Fig. 13]FIG. 13 is a diagram of dots landed on the object from the liquid discharge apparatus according to the first embodiment of the present invention, as a second example.[Fig. 14]FIG. 14 is a diagram of dots landed on the object from the liquid discharge apparatus according to the first embodiment of the present invention, as a third example.[Fig. 15]FIG. 15 is a diagram of dots landed on the object as a comparative example.[Fig. 16]FIG. 16 is a graph of a moving speed of the head of the liquid discharge apparatus according to the first embodiment of the present invention, as a first example.[Fig. 17]FIG. 17 is a graph of a moving speed of the head of the liquid discharge apparatus according to the first embodiment of the present invention, as a second example.[Fig. 18]FIG. 18 is a diagram of a relation between a discharge cycle of liquid droplets and a thickness of a coating film produced by the liquid discharge apparatus according to the first embodiment of the present invention, as a first example.[Fig. 19]FIG. 19 is a diagram of a relation between a discharge cycle of liquid droplets and a thickness of a coating film produced by the liquid discharge apparatus according to the first embodiment of the present invention, as a second example.[Fig. 20]FIG. 20 is a diagram of a relation between a discharge cycle of liquid droplets and a thickness of a coating film produced by the liquid discharge apparatus according to the first embodiment of the present invention, as a third example.[Fig. 21]FIG. 21 is a graph of a driving voltage of a head of a liquid discharge apparatus as a comparative example.[Fig. 22]FIG. 22 is a graph of a driving voltage of the head of the liquid discharge apparatus according to the first embodiment of the present invention, as a first example.[Fig. 23]FIG. 23 is a graph of a driving voltage of the head of the liquid discharge apparatus according to the first embodiment of the present invention, as a second example.[Fig. 24]FIG. 24 is a graph of a driving voltage of the head of the liquid discharge apparatus according to the first embodiment of the present invention, as a third example.[Fig. 25]FIG. 25 is a graph of a driving voltage of the head of the liquid discharge apparatus according to the first embodiment of the present invention, as a fourth example.[Fig. 26]FIG. 26 is a graph of a driving voltage of the head of the liquid discharge apparatus according to the first embodiment of the present invention, as a fifth example.[Fig. 27]FIG. 27 is a flowchart of processes for setting dot data, that are performed by the liquid discharge apparatus according to the first embodiment of the present invention.[Fig. 28]FIG. 28 is a flowchart of processes for determining parameters for addressing secondary droplets, that are performed by the liquid discharge apparatus according to the first embodiment of the present invention.[Fig. 29]FIG. 29 is a diagram of the head of the liquid discharge apparatus according to the first embodiment of the present invention, that moves relative to the object reciprocatingly.[Fig. 30]FIG. 30 is a diagram of the head of the liquid discharge apparatus according to the first embodiment of the present invention, that moves relative to the object reciprocatingly, illustrating first discharging performed by the head.[Fig. 31 A]FIG. 31 A is a diagram of the head of the liquid discharge apparatus according to the first embodiment of the present invention, that moves relative to the object reciprocatingly, illustrating second discharging performed by the head.[Fig. 3 IB]FIG. 3 IB is a diagram of the head of the liquid discharge apparatus according to the first embodiment of the present invention, that moves relative to the object reciprocatingly, illustrating second discharging performed by the head.[Fig. 32]FIG. 32 is a diagram of the head of the liquid discharge apparatus according to the first embodiment of the present invention, that moves relative to the object reciprocatingly, illustrating third discharging performed by the head.[Fig. 33]FIG. 33 is a diagram of the head of the liquid discharge apparatus according to the first embodiment of the present invention, that moves relative to the object reciprocatingly, illustrating fourth discharging performed by the head.[Fig. 34]FIG. 34 is a view of the head of the liquid discharge apparatus according to the first embodiment of the present invention, illustrating a discharge region as a first example. [Fig. 35]FIG. 35 is a view of heads of a liquid discharge apparatus according to the first embodiment of the present invention, illustrating discharge regions as a second example.[Fig. 36]FIG. 36 is a view of the heads of the liquid discharge apparatus according to the first embodiment of the present invention, illustrating discharge regions as a third example. [Fig. 37]FIG. 37 is a view of a liquid discharge apparatus according to a second embodiment of the present invention, illustrating a construction thereof.[Fig. 38]FIG. 38 is a view of a liquid discharge apparatus according to a third embodiment of the present invention, illustrating a construction thereof.[Fig. 39]FIG. 39 is a cross-sectional view of the liquid discharge apparatus, taken on line XXXIX- XXXIX in FIG. 38.

[0011] The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views. [Description of Embodiments]

[0012] Referring to drawings, a detailed description is provided of liquid discharge apparatuses and liquid discharge methods according to embodiments of the present invention. The embodiments described below indicate the liquid discharge apparatuses and the liquid discharge methods that embody the technology of the embodiments of the present invention and are not limited to the below. The embodiments describe elements that have a dimension, a material, a shape, a relative location, and the like that do not limit the scope of the present invention unless otherwise specified, as examples. The drawings may emphasize a size, a positional relation, and the like of members to clarify the description. In the description below, members having identical names and reference numerals indicate identical or equivalent members and a detailed description of the members is omitted properly.

[0013] A description is provided of an entire construction of a liquid discharge apparatus 100 according to a first embodiment of the present invention as an example. FIG. 1 is a view of the liquid discharge apparatus 100 according to the first embodiment of the present invention, illustrating one example of the entire construction thereof. The liquid discharge apparatus 100 includes liquid dischargers 10, heads 11, and moving mechanisms 13. The moving mechanisms 13 move the heads 11, respectively, relative to an object 200 in a first direction. The liquid discharge apparatus 100 depicted in FIG. 1 as an example further includes a control unit 20 that controls the liquid dischargers 10.

[0014] The liquid discharge apparatus 100 includes the four liquid dischargers 10, that is, liquid dischargers 10-1, 10-2, 10-3, and 10-4. The four liquid dischargers 10 (e.g., the liquid dischargers 10-1, 10-2, 10-3, and 10-4) surround the object 200 situated at a coating position. Each of the four liquid dischargers 10 (e.g., the liquid dischargers 10-1, 10-2, 10-3, and 10-4) includes the head 11 that discharges liquid onto the object 200 and the moving mechanism 13. The liquid dischargers 10 depicted in FIG. 1 as an example include detectors 12, respectively.

[0015] For example, the object 200 is a body of a vehicle. The vehicle includes an automobile, a truck, or the like. The object 200 described in the present specification as an example is a vehicle.

[0016] Each of the heads 11 (e.g., heads 11-1, 11-2, 11-3, and 11-4) includes a plurality of nozzles that discharges liquid and is mounted on a tip of the moving mechanism 13. The moving mechanism 13 moves the head 11 relative to the object 200. The moving mechanism 13 depicted in FIG. 1 as an example moves the head 11 relative to the object 200 along a surface of the object 200. While the moving mechanism 13 moves the head 11 relative to the object 200, the nozzles of the head 11 discharge liquid that is applied to the object 200, coating the object 200.

[0017] Each of the detectors 12 (e.g., detectors 12-1, 12-2, 12-3, and 12-4) is mounted on the tip of the moving mechanism 13. The detector 12 outputs feature point data relating to three- dimensional positions of three or more feature points on the object 200. The detector 12 includes a three-dimensional (3D) camera such as a stereo camera, a three-dimensional (3D) sensor other than the stereo camera, a laser displacement meter, or the like. The detector 12 depicted in FIG. 1 as an example includes the stereo camera that performs measurement of a position of the head 11 in X-direction and Y-direction and a tilt of the head 11, detection of a coating start position of the head 11, detection of a size of the object 200 to be coated, and the like. The detectors 12 include a plurality of stereo cameras. Based on a disparity between images captured by the plurality of stereo cameras, respectively, the detectors 12 obtain range images of the object 200 by a triangulation method. The stereo cameras output the range images as the feature point data to the control unit 20. Alternatively, the detector 12 mayinclude the laser displacement meter that performs measurement of a position of the head 11 in Z-direction, detection of a height of a roof of the object 200 and a curvature of the object 200, and the like.

[0018] Each of the moving mechanisms 13 (e.g., moving mechanisms 13-1, 13-2, 13-3, and 13-4) includes a link and a joint. As the moving mechanism 13 rotates or displaces the link and the joint, the moving mechanism 13 changes a position and a tilt of the head 11 relative to the object 200, causing a face of a nozzle plate of the head 11 to face the object 200.

[0019] Based on predetermined shape data of the object 200 and the feature point data relating to the three-dimensional positions of the three or more feature points output from the four detectors 12, respectively, the control unit 20 drives the moving mechanisms 13 that hold the four heads 11, respectively.

[0020] In addition to the elements illustrated in FIG. 1 as an example, the liquid discharge apparatus 100 may further include a supply portion and a maintenance portion. The supply portion supplies liquid to the four heads 11 that discharge the liquid onto the object 200. The maintenance portion removes a thickening agent and a foreign substance adhered to the face of the nozzle plate of the head 11 or the thickening agent, the foreign substance, and the like inside the head 11. The maintenance portion of the liquid discharge apparatus 100 reduces faulty discharging of the head 11 such as nozzle failure, liquid jetting deviation, and variation in discharging speed, thus maintaining a proper discharging status of the head 11.

[0021] In the liquid discharge apparatus 100, after the object 200 is conveyed to the coating position, the moving mechanisms 13 move the heads 11 relative to the object 200 that halts so that the heads 11 coat the object 200. When the heads 11 finish coating the object 200, the object 200 is conveyed to a position outside the coating position so that a subsequent object 200 is conveyed to the coating position.

[0022] Referring to FIGS. 2 and 3, a description is provided of a construction of the head 11 incorporated in the liquid discharge apparatus 100. FIG. 2 is a view of the head 11 according to the first embodiment, illustrating one example of the construction thereof. FIG. 3 is a cross-sectional view of the head 11 according to the first embodiment, taken on a plane SI depicted in FIG. 2. As illustrated in FIGS. 2 and 3, the head 11 includes a supply port 111, a collecting port 112, and a discharge module 340.

[0023] The supply port 111 supplies pressurized liquid that is applied with pressure from an outside of the head 11 to the discharge module 340. The collecting port 112 discharges liquid, that is not discharged when a nozzle 311 described below opens, to the outside of the head 11. The discharge module 340 includes a body 110, a nozzle plate 321 provided with the nozzle 311, achannel 322 for liquid, a valve 310, and a piezoelectric element 324. The nozzle plate 321 is coupled with the body 110 and discharges liquid supplied from the supply port 111 through the nozzle 311. The channel 322 is shared with a plurality of discharge modules 340 (e.g., eight discharge modules 340 depicted in FIG. 3) mounted on the body 110.

[0024] The valve 310 depicted in FIG. 3 is a needle valve. The piezoelectric element 324 drives the valve 310. As the valve 310 moves inside the body 110 reciprocatingly in a liquid discharging direction, the valve 310 opens and closes the nozzle 311. In a state in which a valve of the collecting port 112 closes, the head 11 depicted in FIG. 3 is supplied with the pressurized liquid from the supply port 111 through the channel 322. While the valve 310 is situated at a position where the valve 310 closes the nozzle 311, the nozzle 311 does not discharge liquid. Conversely, as the piezoelectric element 324 is driven to lift the valve 310, the nozzle 311 opens and discharges liquid.

[0025] A description is provided of a construction of a supply portion 14 incorporated in the liquid discharge apparatus 100. FIG. 4 is a diagram of the supply portion 14 incorporated in the liquid discharge apparatus 100, illustrating the construction thereof as one example. The supply portion 14 includes liquid tanks 330, that is, liquid tanks 330-1, 330-2, 330-3, and 330- 4, that serve as sealed containers that contain liquid 325 to be discharged from the heads 11-1, 11-2, 11-3, and 11-4, respectively. The liquid tanks 330 are coupled with inlets (e.g., the supply ports 111) of the heads 11-1, 11-2, 11-3, and 11-4 through tubes 333, respectively, so that the liquid 325 flows from the liquid tanks 330 to the heads 11-1, 11-2, 11-3, and 11-4 through the tubes 333.

[0026] The liquid tanks 330 are coupled with a compressor 230 through a pipe 331 provided with air regulators 332. The compressor 230 supplies compressed air that supplies the liquid 325 that is applied with pressure to the inlets of the heads 11. Thus, the nozzles 311 of the heads 11 of the liquid discharge apparatus 100 discharge the liquid 325. Instead of the liquid tanks 330 that correspond to the heads 11, respectively, a single liquid tank 330 may supply the liquid 325 to the heads 11.

[0027] A description is provided of a configuration of the control unit 20. FIG. 5 is a block diagram of the liquid discharge apparatus 100, illustrating a configuration thereof as one example. The liquid discharge apparatus 100 includes a controller 901, a head control unit 902, a moving mechanism control unit 904, an input device 905, the moving mechanisms 13-1 and 13-2, and a personal computer (PC) 903.

[0028] The controller 901 includes a central processing unit (CPU) 9001, a read only memory (ROM) 9002, a random access memory (RAM) 9003, and an interface (I / F) 9004. The controller 901, the head control unit 902, and the moving mechanism control unit 904construct the control unit 20. The head 11 and the detector 12 construct a head unit 103. The moving mechanisms 13-1 and 13-2 are two of the four moving mechanisms 13 depicted in FIG. 1.

[0029] The PC 903 includes a coating path generation unit 9031 and a coating data generation unit 9032. The coating path generation unit 9031 and the coating data generation unit 9032 depicted in FIG. 5 define functional units of the PC 903. The coating path generation unit 9031 and the coating data generation unit 9032 have functions that are established as a CPU incorporated in the PC 903 executes processes specified by a program stored in a memory such as a ROM.

[0030] The coating path generation unit 9031 obtains position data from the detector 12 mounted on the moving mechanism 13, generating a coating path serving as a path through which the moving mechanism 13 moves the head 11. The coating data generation unit 9032 generates coating dot data based on the coating path generated by the coating path generation unit 9031. The coating data generation unit 9032 includes a discharge frequency generation unit 9033, a moving speed generation unit 9034, and a raster image processor (RIP) 9035. In the coating data generation unit 9032, the discharge frequency generation unit 9033 generates a discharge frequency at which the head 11 discharges liquid according to the generated dot data. The moving speed generation unit 9034 generates a moving speed at which the moving mechanism 13 moves the head 11 and generates a driving condition of the head 11, creating coating data.

[0031] The RIP 9035 performs image processing according to a color profile or a setting specified by a user. The RIP 9035 includes a rendering unit 9036. The rendering unit 9036 decomposes the coating data used for coating the object 200 into image data. The liquid discharge apparatus 100 moves the head 11 in a main scanning direction and a sub-scanning direction perpendicular to the main scanning direction while the head 11 coats the object 200. The image data defines data that is included in the coating data and used for coating whenever the head 11 moves in the main scanning direction.

[0032] The PC 903 is coupled with the input device 905 that performs setting of the image data and coordinate data for coating the object 200, selection of a coating mode, setting of a coating range (e.g., a coating start position and a coating finish position), instruction for coating, and the like. The input device 905 includes a keyboard, a mouse, and a touch panel and receives an input from the user.

[0033] The controller 901 is coupled with the PC 903. The CPU 9001 is an arithmetic unit that reads a program or data stored in the ROM 9002 or the like onto the RAM 9003 and executes processing, achieving functions of the liquid discharge apparatus 100 serving as a coatingrobot. The controller 901 may further include a hard disk drive (HDD), a solid state drive (SSD), or the like.

[0034] The CPU 9001 controls overall operations of the liquid discharge apparatus 100 according to the image data or the instruction received from the PC 903. The ROM 9002 is a nonvolatile memory that retains the program or the data even when the liquid discharge apparatus 100 is powered off. The RAM 9003 is a volatile memory used as a work area or the like of the CPU 9001. The I / F 9004 is an interface through which characters, values, instructions, and the like are input and output with respect to external devices and the like. The I / F 9004 is an interface through which the controller 901 communicates with an external device such as the PC 903.

[0035] The moving mechanism 13 includes the head unit 103, an encoder sensor 109, and a driver 72. The head 11 discharges liquid according to a driving signal sent from the head control unit 902. The detector 12 sends a detection result of the object 200 to the PC 903.

[0036] Each of the encoder sensors 109 optically detects a slit of an encoder mounted on each of a first joint, a second joint, a third joint, and the like, for example. The encoder sensors 109 detect positions of the slits based on rotation amounts of the moving mechanisms 13-1 and 13-2, respectively, obtaining three-dimensional position data of the head unit 103.

[0037] The driver 72 moves the head unit 103 supported by the moving mechanism 13 to a target position according to a driving signal sent from the moving mechanism control unit 904. The head control unit 902 and the moving mechanism control unit 904 are shared with the moving mechanisms 13-1 and 13-2. Alternatively, the head control unit 902 and the moving mechanism control unit 904 may be provided for each of the moving mechanisms 13-1 and 13-2. The RIP 9035 including the rendering unit 9036 may be incorporated in the controller 901 instead of the PC 903.

[0038] The head control unit 902 receives the discharge cycle signal from the controller 901 and controls liquid discharging of the head 11 based on the discharge cycle signal. The moving mechanism control unit 904 receives a synchronous control signal from the controller 901 and controls driving of the driver 72 based on the synchronous control signal. The moving mechanism control unit 904 controls driving of the driver 72, moving the moving mechanism 13 including the head unit 103 to the target position.

[0039] A description is provided of a functional configuration of the controller 901. FIG. 6 is a block diagram of the controller 901 incorporated in the liquid discharge apparatus 100 according to the first embodiment of the present invention, illustrating one example of the functional configuration of the controller 901. The controller 901 includes a system control unit 9011, adata storage unit 9012, a memory control unit 9013, a discharge cycle signal generation unit 9014, and a cycle control unit 9015.

[0040] The system control unit 9011 controls the overall operations of the liquid discharge apparatus 100 according to the image data or the instruction received from the PC 903. The data storage unit 9012 stores the coating data and the like received from the PC 903. The memory control unit 9013 controls the data storage unit 9012. The discharge cycle signal generation unit 9014 generates a liquid discharge cycle signal based on an output signal output from the encoder sensor 109 and data indicating a resolution of the image data received from the PC 903. The cycle control unit 9015 aligns movement of the moving mechanisms 13-1 and 13-2 with liquid discharging of the heads 11-1 and 11-2 based on the image data, the instruction for coating, and the like that are received from the PC 903.

[0041] A description is provided of relative movement paths through which the heads 11 move relative to the object 200. FIG. 7 is a view of the object 200 and the relative movement paths through which the heads 11 of the liquid discharge apparatus 100 according to the first embodiment of the present invention move relative to the object 200 as one example.

[0042] FIG. 7 illustrates the object 200 that is an automobile and coating regions 211 (e.g., coating regions 211-1, 211-2, 211-3, and 211-4) on a roof 201 of the automobile. The coating regions 211 define regions where the four moving mechanisms 13 depicted in FIG. 1 move the heads 11 relative to the object 200, respectively, so that the heads 11 coat the object 200. The four heads 11 are provided with the coating regions 211 and relative movement paths T10 (e.g., relative movement paths Tl-1, Tl-2, Tl-3, and Tl-4) that are different from each other.

[0043] The coating region 211-1 defines a region where the moving mechanism 13-1 moves the head 11-1 relative to the object 200 to coat the object 200. The relative movement path Tl-1 defines a path through which the head 11-1 moves relative to the object 200.

[0044] The coating region 211-2 defines a region where the moving mechanism 13-2 moves the head 11-2 relative to the object 200 to coat the object 200. The relative movement path Tl-2 defines a path through which the head 11-2 moves relative to the object 200.

[0045] The coating region 211-3 defines a region where the moving mechanism 13-3 moves the head 11-3 relative to the object 200 to coat the object 200. The relative movement path Tl-3 defines a path through which the head 11-3 moves relative to the object 200.

[0046] The coating region 211-4 defines a region where the moving mechanism 13-4 moves the head 11-4 relative to the object 200 to coat the object 200. The relative movement path Tl-4 defines a path through which the head 11-4 moves relative to the object 200.

[0047] As described above, the liquid discharge apparatus 100 includes the four moving mechanisms 13 that move the four heads 11, respectively, relative to the roof 201 of the automobile as the object 200 so that the heads 11 discharge liquid that coats the roof 201.

[0048] A description is provided of liquid discharged from a head while the head moves in the main scanning direction. A state in which the head discharges liquid intermittently defines a state in which the head repeats discharging of liquid and interruption of discharging of liquid periodically while the head moves in the main scanning direction. For example, the state in which the head discharges liquid intermittently defines a state in which the head discharges liquid droplets. Conversely, a state in which the head discharges liquid continuously defines a state in which the head continues discharging liquid while the head moves in the main scanning direction. In other words, the state in which the head discharges liquid continuously defines a state in which the head discharges liquid seamlessly or in a continuous stream in the main scanning direction while the head moves in the main scanning direction. In the description below, liquid discharged intermittently may be called liquid droplets. Liquid discharged continuously may be called liquid thread.

[0049] In a case that a liquid discharge apparatus discharges a liquid droplet, the liquid droplet landed on an object to be coated wets and spreads in a circular shape on the object to be coated, forming a dot. The formed dot overlaps with surrounding dots and fills gaps between the dots, forming a coated face. Since the formed dot has the circular shape, the coated face has an edge that is waved according to the circular shape of the dot.

[0050] Conversely, in a case that the liquid discharge apparatus discharges liquid thread, the liquid thread landed on the object to be coated does not form a dot and forms a line in the main scanning direction in which the head of the liquid discharge apparatus moves. Hence, the coated face has an edge in the sub- scanning direction, that is smoother in the main scanning direction.

[0051] A description is provided of operations of the liquid discharge apparatus 100. A description is now given of reduction of effect caused by secondary droplets, that is performed by the liquid discharge apparatus 100. The following description is given with reference to liquid droplets as an example. However, a basic concept is shared with liquid thread.

[0052] As the valve 310 opens and closes, the head 11 discharges liquid as liquid droplets, that is, droplets of liquid. As the head 11 discharges liquid, the liquid lands on the object 200. As the liquid discharged from the head 11 lands on the object 200, the liquid forms a dot on the object 200. After the valve 310 opens, the control unit 20 controls a time period taken until the valve 310 closes, controlling a volume of the liquid droplet discharged from the head 11.As the time period taken until the valve 310 closes after the valve 310 opens increases, the volume of the liquid droplet increases. As the volume of the liquid droplet increases, a diameter of the dot that is formed on the object 200 and is substantially circular increases.

[0053] The liquid droplet discharged from the head 11 may generate tailing called a ligament that follows the liquid droplet in a direction in which the liquid droplet travels through the air according to a viscosity, a surface tension, or the like of liquid. If the ligament separates from the liquid droplet while the liquid droplet travels through the air, the separated ligament is atomized by the surface tension of liquid into microdroplets that follow the liquid droplet. In the present specification, a body of the liquid droplet, that is other than the ligament, is called a primary droplet. A microdroplet produced as the ligament separated from the primary droplet is atomized is called a secondary droplet. The secondary droplet has a volume that is smaller than a volume of the primary droplet. Since the secondary droplet is spaced apart from the primary droplet, the secondary droplet is also called a satellite droplet. As the primary droplet lands on the object 200, the primary droplet forms a dot. As the secondary droplet lands on the object 200, the secondary droplet forms a satellite dot.

[0054] Referring to FIGS. 8 to 11, a description is provided of a relation between a state of a liquid droplet discharged from the head 11 and a dot formed by the liquid droplet. FIG. 8 is a diagram of a liquid droplet discharged from the liquid discharge apparatus 100 according to the first embodiment of the present invention, illustrating the state of the liquid droplet as a first example. FIG. 9 is a diagram of a dot and a satellite dot formed by the liquid droplet depicted in FIG. 8. FIG. 10 is a diagram of a liquid droplet discharged from the liquid discharge apparatus 100 according to the first embodiment of the present invention, illustrating the state of the liquid droplet as a second example. FIG. 11 is a diagram of a dot and a satellite dot formed by the liquid droplet depicted in FIG. 10. FIGS. 8 and 10 illustrate the state of the liquid droplets, seen from a direction that is substantially perpendicular to a discharging direction C in which the head 11 discharges liquid. FIGS. 9 and 11 illustrate the dot and the satellite dot formed on the object 200 by the liquid droplet that lands on the object 200, seen in a direction parallel to a normal vector to the object 200.

[0055] FIG. 8 illustrates, as the first example, a liquid droplet 80a that includes a primary droplet 81a and a ligament 82a that follows the primary droplet 81a. FIG. 8 illustrates a liquid droplet 80al that generates when a predetermined time elapses after the liquid droplet 80a generates. The liquid droplet 80al includes a plurality of secondary droplets 83a that generates as the ligament 82a separates from the primary droplet 81a and the separated ligament 82a is atomized according to the surface tension of liquid.

[0056] FIG. 9 illustrates, as the first example, a dot 91a formed by the primary droplet 81a and satellite dots 92a formed by the plurality of secondary droplets 83a. A length LI defines adistance from a position of an end of the dot 91a, that is disposed opposite the satellite dot 92a in a first direction A in which the head 11 moves, to a position of an end of the satellite dot 92a, that is opposite to another end of the satellite dot 92a, that is disposed opposite the dot 91a in the first direction A. According to the embodiments of the present invention, the first direction A defines the direction (e.g., the main scanning direction) in which the moving mechanism 13 moves the head 11 relative to the object 200 when the head 11 discharges liquid onto a discharge region on the object 200 to form a dot.

[0057] FIG. 10 illustrates, as the second example, a liquid droplet 80b that includes a primary droplet 81b and a ligament 82b that follows the primary droplet 81b. FIG. 10 illustrates a liquid droplet 80b 1 that generates when a predetermined time elapses after the liquid droplet 80b generates. The liquid droplet 80b 1 includes a plurality of secondary droplets 83b that generates as the ligament 82b separates from the primary droplet 81b and the separated ligament 82b is atomized according to the surface tension of liquid.

[0058] FIG. 11 illustrates, as the second example, a dot 91b formed by the primary droplet 81b and a satellite dots 92b formed by the plurality of secondary droplets 83b. A length L2 defines a distance from a position of an end of the dot 91b, that is disposed opposite the satellite dot 92b in the first direction A, to a position of an end of the satellite dot 92b, that is opposite to another end of the satellite dot 92b, that is disposed opposite the dot 91b in the first direction A.

[0059] The liquid droplet 80a depicted in FIG. 8 is greater than the liquid droplet 80b depicted in FIG. 10 in a liquid amount and a volume. Since the liquid droplet 80a has the greater liquid amount, a length of the ligament 82a is greater than a length of the ligament 82b in the discharging direction C. Since the ligament 82a has the greater length, a number of the secondary droplets 83 a generated from the ligament 82a is greater than a number of the secondary droplets 83b generated from the ligament 82b. Additionally, an entire length defined by the plurality of secondary droplets 83a arranged in the discharging direction C is greater than an entire length defined by the plurality of secondary droplets 83b arranged in the discharging direction C. Since the plurality of secondary droplets 83a arranged in the discharging direction C defines the greater entire length, on the object 200, an area of the satellite dot 92a depicted in FIG. 9 is greater than an area of the satellite dot 92b depicted in FIG. 11. The length LI defined by the satellite dots 92a arranged in the first direction A is greater than the length L2 defined by the satellite dot 92b.

[0060] For example, if a size of a satellite dot increases or if a length defined by satellite dots arranged in the first direction A increases, redundant liquid may adhere to the object 200, staining the object 200.

[0061] Referring to FIGS. 12 to 15, a description is provided of dots formed on the object 200 by the liquid discharge apparatus 100 according to the first embodiment of the present invention. FIG. 12 is a diagram of dots 91 landed on the object 200 to be coated by the liquid discharge apparatus 100 according to the first embodiment of the present invention as a first example. FIG. 13 is a diagram of dots 91 landed on the object 200 to be coated by the liquid discharge apparatus 100 according to the first embodiment of the present invention as a second example. FIG. 14 is a diagram of dots 91 landed on the object 200 to be coated by the liquid discharge apparatus 100 according to the first embodiment of the present invention as a third example. FIG. 15 is a diagram of dots 91 landed on the object 200 as a comparative example. FIGS. 12 to 14 illustrate the dots 91 also assigned with reference numerals 911 and 912 indicating that the dots 91 include the dots 911 and 912. FIG. 15 illustrates the dots 91 also assigned with reference numerals 911 and 912X indicating that the dots 91 include the dots911 and 912X. The following describes a leading end region and a trailing end region of a discharge region 120. The leading end region defines an upstream end region in the first direction A. The trailing end region defines a downstream end region in the first direction A. A direction perpendicular to the first direction A defines a second direction.

[0062] In the liquid discharge apparatus 100 depicted in FIGS. 12 to 14, the discharge region 120 on the object 200 onto which liquid is discharged has a trailing end region 121 and an outboard region other than the trailing end region 121 in the first direction A. A diameter de of the dot912 in the trailing end region 121 is smaller than a diameter d of the dot 911 in the outboard region. Accordingly, a length of liquid landed on the trailing end region 121 in the second direction is smaller than a length of liquid landed on the outboard region in the second direction.

[0063] For example, the head 11 of the liquid discharge apparatus 100 discharges liquid droplets 80 depicted in FIG. 18 onto the trailing end region 121 of the discharge region 120 in an amount that is smaller than an amount of the liquid droplets 80 discharged onto the outboard region of the discharge region 120, that is other than the trailing end region 121. Accordingly, the diameter de of the dot 912 in the trailing end region 121 is smaller than the diameter d of the dot 911 in the outboard region other than the trailing end region 121. Since the amount of the liquid droplets 80 decreases, a length of a ligament decreases. Hence, the liquid discharge apparatus 100 reduces effect caused by secondary droplets. Since the effect caused by the secondary droplets decreases, the liquid discharge apparatus 100 reduces satellited dots, preventing redundant liquid from adhering to and staining the object 200. Each of the first example to the third example reduces the effect caused by the secondary droplets.

[0064] The trailing end region 121 defines a span that is upstream from a rear end of the discharge region 120 in the first direction A in which the head 11 moves for a length not smaller thanthe diameter d of the dot 911. The diameter de of the dot 912 is preferably not greater than 90% of the diameter d of the dot 911.

[0065] In the comparative example depicted in FIG. 15, a discharge region 120X includes a trailing end region 12 IX where an amount of the liquid droplets 80 discharged from the head 11 is not smaller than an amount of the liquid droplets 80 discharged onto an outboard region of the discharge region 120X, that is other than the trailing end region 12 IX. Hence, compared to satellite dots 92 in the first example depicted in FIG. 12, the second example depicted in FIG. 13, and the third example depicted in FIG. 14, satellite dots 92X in the comparative example are greater in number and size.

[0066] A description is provided of reduction of uneven thickness of a coating film produced by the liquid discharge apparatus 100.

[0067] For example, if an amount of the liquid droplets 80 in the trailing end region 121 is smaller than an amount of the liquid droplets 80 in the outboard region other than the trailing end region 121, a thickness of a coating film in the trailing end region 121 may be smaller than a thickness of the coating film in the outboard region other than the trailing end region 121, generating uneven thickness of the coating film.

[0068] In the first example of the liquid discharge apparatus 100 depicted in FIG. 12, a center-to- center distance pc between the adjacent dots 912 in the first direction A in the trailing end region 121 is smaller than a center-to-center distance p between the adjacent dots 911 in the first direction A in the outboard region of the discharge region 120, that is other than the trailing end region 121. Accordingly, the amount of the liquid droplets 80 in the trailing end region 121 is equivalent to the amount of the liquid droplets 80 in the outboard region other than the trailing end region 121. Consequently, the thickness of the coating film in the trailing end region 121 is equivalent to the thickness of the coating film in the outboard region other than the trailing end region 121, reducing uneven thickness of the coating film.

[0069] In the second example of the liquid discharge apparatus 100 depicted in FIG. 13, compared to the first example of the liquid discharge apparatus 100 depicted in FIG. 12, the center-to- center distance pc between the adjacent dots 912 in the first direction A in the trailing end region 121 of the discharge region 120 is further reduced. In the second example of the liquid discharge apparatus 100 also, the amount of the liquid droplets 80 in the trailing end region 121 is equivalent to the amount of the liquid droplets 80 in the outboard region other than the trailing end region 121.

[0070] In the third example of the liquid discharge apparatus 100 depicted in FIG. 14, as the head 11 moves in the first direction A in the trailing end region 121, the diameter de of the dot 912decreases gradually. Additionally, the center-to-center distance pc between the adjacent dots 912 in the first direction A decreases. In the third example of the liquid discharge apparatus 100 also, the amount of the liquid droplets 80 in the trailing end region 121 is equivalent to the amount of the liquid droplets 80 in the outboard region other than the trailing end region 121.

[0071] In order to reduce uneven thickness of the coating film produced by the liquid discharge apparatus 100, a moving speed at which the head 11 moves relative to the object 200 in the trailing end region 121 may be lower than a moving speed at which the head 11 moves relative to the object 200 in the outboard region of the discharge region 120, that is other than the trailing end region 121. FIG. 16 is a graph illustrating a first example of the moving speed of the head 11 of the liquid discharge apparatus 100 according to the first embodiment of the present invention. FIG. 17 is a graph illustrating a second example of the moving speed of the head 11 of the liquid discharge apparatus 100 according to the first embodiment of the present invention. The liquid discharge apparatus 100 controls a number of rotations of a gear of the moving mechanism 13, for example, thus controlling the moving speed of the head 11.

[0072] In FIG. 16, a first period T1 defines a time period when the head 11 discharges liquid in the outboard region of the discharge region 120, that is other than the trailing end region 121. A second period T2 defines a time period when the head 11 discharges liquid in the trailing end region 121 of the discharge region 120. A moving speed at which the head 11 moves in the first direction A in the second period T2 is slower than a moving speed at which the head 11 moves in the first direction A in the first period T 1. The head 11 that moves at the slower moving speed discharges the liquid droplets 80 onto the trailing end region 121 in an amount greater than an amount of the liquid droplets 80 discharged when the head 11 moves at the higher moving speed. Accordingly, the amount of the liquid droplets 80 in the trailing end region 121 is equivalent to the amount of the liquid droplets 80 in the outboard region other than the trailing end region 121. Consequently, the thickness of the coating film in the trailing end region 121 is equivalent to the thickness of the coating film in the outboard region other than the trailing end region 121, reducing uneven thickness of the coating film.

[0073] As illustrated in FIG. 17, the moving speed at which the head 11 moves in the first direction A in the second period T2 decreases gradually as the head 11 moves. Even in a case that the moving speed of the head 11 decreases gradually, compared to a case that the head 11 moves at an increased moving speed, the amount of the liquid droplets 80 in the trailing end region 121 increases. Accordingly, the amount of the liquid droplets 80 in the trailing end region 121 is equivalent to the amount of the liquid droplets 80 in the outboard region other than the trailing end region 121. Consequently, the thickness of the coating film in the trailing end region 121 is equivalent to the thickness of the coating film in the outboard region other than the trailing end region 121, reducing uneven thickness of the coating film.

[0074] Referring to FIGS. 18 to 20, a description is provided of a relation between a discharge cycle of the head 11 of the liquid discharge apparatus 100 according to the first embodiment of the present invention and the thickness of the coating film. FIG. 18 is a diagram illustrating the relation between the discharge cycle of the head 11 of the liquid discharge apparatus 100 according to the first embodiment of the present invention and the thickness of the coating film, as a first example. FIG. 19 is a diagram illustrating the relation between the discharge cycle of the head 11 of the liquid discharge apparatus 100 according to the first embodiment of the present invention and the thickness of the coating film, as a second example. FIG. 20 is a diagram illustrating the relation between the discharge cycle of the head 11 of the liquid discharge apparatus 100 according to the first embodiment of the present invention and the thickness of the coating film, as a third example.

[0075] FIGS. 18 to 20 illustrate a discharge cycle ql of the liquid droplets 80 and a thickness tl of a coating film 180 in the first period Tl and a discharge cycle q2 of the liquid droplets 80 and a thickness t2 of the coating film 180 in the second period T2. The coating film 180 defines a film that coats the object 200.

[0076] In the first example depicted in FIG. 18, an amount of the liquid droplets 80 discharged in the second period T2 is smaller than an amount of the liquid droplets 80 discharged in the first period T 1. The discharge cycle q2 in the second period T2 is equivalent to the discharge cycle ql in the first period Tl. Accordingly, in the first example, the thickness t2 of the coating film 180 produced in the second period T2 is smaller than the thickness tl of the coating film 180 produced in the first period T 1.

[0077] In the second example depicted in FIG. 19, an amount of the liquid droplets 80 discharged in the second period T2 is smaller than an amount of the liquid droplets 80 discharged in the first period T 1. The discharge cycle q2 in the second period T2 is shorter than the discharge cycle ql in the first period Tl. As the discharge cycle q2 shortens, the amount of the liquid droplets 80 discharged onto the object 200 increases. Accordingly, in the second example, the thickness t2 of the coating film 180 produced in the second period T2 is substantially equivalent to the thickness tl of the coating film 180 produced in the first period Tl. If the discharge cycle q2 in the second period T2 is identical to the discharge cycle ql in the first period Tl, the thickness t2 of the coating film 180 produced in the second period T2 may be smaller than the thickness tl of the coating film 180 produced in the first period Tl. In this case, unevenness in the thickness of the coating film 180 may increase. Conversely, in the second example, the thickness t2 of the coating film 180 produced in the second period T2 is substantially equivalent to the thickness tl of the coating film 180 produced in the first period Tl, reducing unevenness in the thickness of the coating film 180.

[0078] In the third example depicted in FIG. 20, an amount of the liquid droplets 80 discharged in the second period T2 is smaller than an amount of the liquid droplets 80 discharged in the first period T 1. Additionally, as the head 11 moves in the first direction A, the amount of the liquid droplets 80 discharged in the second period T2 decreases gradually. The discharge cycle q2 in the second period T2 is shorter than the discharge cycle ql in the first period Tl. Additionally, as the head 11 moves in the first direction A, the discharge cycle q2 shortens gradually. As the discharge cycle q2 shortens, the amount of the liquid droplets 80 discharged onto the object 200 increases. Accordingly, in the third example, the thickness t2 of the coating film 180 produced in the second period T2 is substantially equivalent to the thickness tl of the coating film 180 produced in the first period Tl. Consequently, in the third example, unevenness in the thickness of the coating film 180 decreases.

[0079] Referring to FIGS. 21 to 26, a description is provided of a driving voltage applied to the head 11 of the liquid discharge apparatus 100 according to the first embodiment of the present invention. FIG. 21 is a graph illustrating the driving voltage applied to the head 11 of the liquid discharge apparatus 100 according to a comparative example, as an example. FIG. 22 is a graph illustrating the driving voltage applied to the head 11 of the liquid discharge apparatus 100 according to the first embodiment of the present invention, as a first example. FIG. 23 is a graph illustrating the driving voltage applied to the head 11 of the liquid discharge apparatus 100 according to the first embodiment of the present invention, as a second example. FIG. 24 is a graph illustrating the driving voltage applied to the head 11 of the liquid discharge apparatus 100 according to the first embodiment of the present invention, as a third example. FIG. 25 is a graph illustrating the driving voltage applied to the head 11 of the liquid discharge apparatus 100 according to the first embodiment of the present invention, as a fourth example. FIG. 26 is a graph illustrating the driving voltage applied to the head 11 of the liquid discharge apparatus 100 according to the first embodiment of the present invention, as a fifth example.

[0080] In the comparative example depicted in FIG. 21, the liquid discharge apparatus 100 applies a driving voltage VI to the head 11 with the discharge cycle ql in an open period Al. As the valve 310 moves in a movement amount according to the driving voltage V 1 , the nozzle 311 opens and discharges liquid in an amount according to the movement amount of the valve 310 and the open period Al. In this case, the amount of the liquid is not smaller than an amount of liquid discharged in the outboard region of the discharge region 120, that is other than the trailing end region 121. Hence, satellite dots generated in the comparative example may increase in number and size compared to satellite dots generated in the first example to the fifth example described below. To address the circumstance, the liquid discharge apparatus 100 according to the embodiments of the present invention employs configurations described below with reference to FIGS. 22 to 26.

[0081] In the first example depicted in FIG. 22, the liquid discharge apparatus 100 applies the driving voltage VI to the head 11 with the discharge cycle ql in the open period Al in the first period Tl. The liquid discharge apparatus 100 applies a driving voltage V2 to the head 11 with the discharge cycle q2 in an open period A2 in the second period T2. Thus, the liquid discharge apparatus 100 as the first example is different from the liquid discharge apparatus 100 as the comparative example depicted in FIG. 21. Since the open period A2 is shorter than the open period Al, an amount of liquid discharged in the second period T2 is smaller than an amount of liquid discharged in the first period Tl. As the liquid discharge apparatus 100 as the first example performs a discharge control illustrated in FIG. 22, the head 11 discharges the liquid droplets 80 depicted in FIG. 18.

[0082] The liquid discharge apparatus 100 as the second example depicted in FIG. 23 is different from the liquid discharge apparatus 100 as the first example depicted in FIG. 22 in that the discharge cycle q2 is shorter than the discharge cycle ql. As the liquid discharge apparatus 100 as the second example performs a discharge control illustrated in FIG. 23, the head 11 discharges the liquid droplets 80 depicted in FIG. 19.

[0083] The liquid discharge apparatus 100 as the third example depicted in FIG. 24 is different from the liquid discharge apparatus 100 as the second example depicted in FIG. 23 in that the discharge cycle q2 shortens gradually as the head 11 moves. As the liquid discharge apparatus 100 as the third example performs a discharge control illustrated in FIG. 24, the head 11 discharges the liquid droplets 80 depicted in FIG. 20.

[0084] The liquid discharge apparatus 100 as the fourth example depicted in FIG. 25 is different from the liquid discharge apparatus 100 as the comparative example depicted in FIG. 21 in that the driving voltage V2 is lower than the driving voltage VI. As the liquid discharge apparatus 100 as the fourth example performs a discharge control illustrated in FIG. 25, the head 11 discharges the liquid droplets 80 depicted in FIG. 18.

[0085] The liquid discharge apparatus 100 as the fifth example depicted in FIG. 26 is different from the liquid discharge apparatus 100 as the comparative example depicted in FIG. 21 in that the open period Al is equivalent to the first period Tl and the open period A2 is equivalent to the second period T2. As the liquid discharge apparatus 100 as the fifth example performs a discharge control illustrated in FIG. 26, the head 11 discharges continuous liquid instead of liquid droplets, thus generating liquid thread.

[0086] The liquid discharge apparatus 100 drives the head 11 at the driving voltage used in any of the first example depicted in FIG. 22 to the fifth example depicted in FIG. 26. The discharge control performed by the liquid discharge apparatus 100 is not limited to a control in which the head 11 is applied with a voltage to control an amount of movement of the valve 310 andan open time period for which the valve 310 opens. For example, the discharge control performed by the liquid discharge apparatus 100 may be a control in which air drives the valve 310 to control the amount of movement of the valve 310 and the open time period for which the valve 310 opens.

[0087] Since the discharge control of the head 11 changes the amount of movement of the valve 310 according to the length of the open period of the nozzle 311, sound that generates as the valve 310 moves changes. Hence, if the head 11 discharges the liquid droplets 80 in the trailing end region 121 in an amount smaller than an amount of the liquid droplets 80 discharged in the outboard region other than the trailing end region 121, sound that generates as the valve 310 moves in the trailing end region 121 is different from sound that generates as the valve 310 moves in the outboard region other than the trailing end region 121. Accordingly, from one perspective, the sound that generates as the valve 310 moves specifies that the head 11 discharges the liquid droplets 80 in the trailing end region 121 in the amount smaller than the amount of the liquid droplets 80 discharged in the outboard region other than the trailing end region 121.

[0088] A description is provided of operations of the liquid discharge apparatus 100. Referring to FIG. 27, a description is now given of processes for setting dot data, that are performed by the liquid discharge apparatus 100 according to the first embodiment of the present invention. FIG. 27 is a flowchart of the processes for setting the dot data, that are performed by the liquid discharge apparatus 100 according to the first embodiment of the present invention, as one example. Whenever the liquid discharge apparatus 100 coats the object 200, the liquid discharge apparatus 100 performs the processes depicted in FIG. 27 before the liquid discharge apparatus 100 starts coating.

[0089] In step S 11, in order to monitor movement of the head 11 according to a shape of the object 200, the coating path generation unit 9031 of the PC 903 of the liquid discharge apparatus 100 reads a coating path stored in a memory such as the ROM of the PC 903.

[0090] Subsequently, in step S12, the liquid discharge apparatus 100 specifies the trailing end region 121 per the discharge region 120 in the coating path read in step Sil.

[0091] Subsequently, in step S13, the liquid discharge apparatus 100 determines whether or not the trailing end region 121 per the discharge region 120 specified in step S12 overlaps other discharge region 120.

[0092] In a case that the liquid discharge apparatus 100 determines that the trailing end region 121 in each discharge region 120 does not overlap other discharge region 120 (NO in step S13), the liquid discharge apparatus 100 proceeds to step SI 5. In this case, the dot data retains adefault thereof. Conversely, in a case that the liquid discharge apparatus 100 determines that the trailing end region 121 in a particular discharge region 120 overlaps other discharge region 120 (YES in step S13), the liquid discharge apparatus 100 determines parameters of a secondary droplet mitigation measure to address secondary droplets described below with reference to FIG. 28 in step S14. The liquid discharge apparatus 100 changes the dot data according to the parameters of the secondary droplet mitigation measure.

[0093] Subsequently, in step S15, the liquid discharge apparatus 100 applies the dot data to the coating path read in step S 11.

[0094] As described above, the liquid discharge apparatus 100 performs the processes for setting the dot data.

[0095] Referring to FIG. 28, a description is provided of processes for determining the parameters of the secondary droplet mitigation measure, that are performed by the liquid discharge apparatus 100 according to the first embodiment of the present invention. The parameters of the secondary droplet mitigation measure define parameters of various mitigation measures for reducing effect caused by secondary droplets. FIG. 28 is a flowchart of the processes for determining the parameters of the secondary droplet mitigation measure, that are performed by the liquid discharge apparatus 100 according to the first embodiment of the present invention, as one example. The liquid discharge apparatus 100 starts the processes depicted in FIG. 28 in step S14 depicted in FIG. 27. The liquid discharge apparatus 100 performs the process in each step depicted in FIG. 28 in the trailing end region 121 in each of the plurality of discharge regions 120.

[0096] In step S21, the control unit 20 of the liquid discharge apparatus 100 determines a span of the trailing end region 121 applied with the secondary droplet mitigation measure. For example, the liquid discharge apparatus 100 determines a multiple of the diameter d of the dot 911, that specifies a span of the trailing end region 121 to be applied with the secondary droplet mitigation measure. The span is upstream from the rear end of the discharge region 120 in the first direction A in which the head 11 moves. The multiple of the diameter d of the dot 911, that is determined, defines n in the processes described below.

[0097] Subsequently, in step S22, the control unit 20 of the liquid discharge apparatus 100 determines a number of dots increased to perform the secondary droplet mitigation measure. The determined number of dots increased defines m that defines a relation of n < m.

[0098] Subsequently, in step S23, the control unit 20 of the liquid discharge apparatus 100 determines an amount of the liquid droplets 80 discharged onto the trailing end region 121, that is regulated based on the driving voltage V2 and the open period A2.

[0099] Subsequently, in step S24, the control unit 20 of the liquid discharge apparatus 100 determines the moving speed of the head 11 in the trailing end region 121.

[0100] Subsequently, in step S25, the control unit 20 of the liquid discharge apparatus 100 determines the discharge cycle q2 in the trailing end region 121 based on the moving speed determined in step S24. The discharge cycle q2 is constant or inconstant. However, the discharge cycle q2 defines a relation of ql > q2.

[0101] Subsequently, in step S26, based on the amount of the liquid droplets 80 discharged onto the trailing end region 121, that is determined in step S23, the control unit 20 of the liquid discharge apparatus 100 determines the driving voltage to control discharging by the head 11, for example, determines which of the driving voltages V 1 and V2 of the first example to the fifth example depicted in FIGS. 22 to 26 to use.

[0102] As described above, the liquid discharge apparatus 100 performs the processes for determining the parameters of the secondary droplet mitigation measure.

[0103] Referring to FIGS. 29, 30, 31 A, 3 IB, 32, and 33, a description is provided of discharging by the head 11 of the liquid discharge apparatus 100 according to the first embodiment of the present invention while the head 11 moves relative to the object 200 reciprocatingly. FIG. 29 is a diagram illustrating reciprocating motion of the head 11 relative to the object 200 in the liquid discharge apparatus 100 according to the first embodiment of the present invention, as one example. FIG. 30 is a first diagram illustrating discharging by the head 11 that moves relative to the object 200 reciprocatingly in the liquid discharge apparatus 100 according to the first embodiment of the present invention. Each of FIGS. 31A and 3 IB is a second diagram illustrating discharging by the head 11 that moves relative to the object 200 reciprocatingly in the liquid discharge apparatus 100 according to the first embodiment of the present invention. FIG. 32 is a third diagram illustrating discharging by the head 11 that moves relative to the object 200 reciprocatingly in the liquid discharge apparatus 100 according to the first embodiment of the present invention. FIG. 33 is a fourth diagram illustrating discharging by the head 11 that moves relative to the object 200 reciprocatingly in the liquid discharge apparatus 100 according to the first embodiment of the present invention.

[0104] Each of FIGS. 29, 30, 31 A, 3 IB, 32, and 33 illustrates the head 11 that moves relative to and travels across the object 200, seen from above the head 11. A forward direction Al defines one direction of the first direction A. A backward direction A2 defines a direction of the first direction A, that is opposite to the forward direction Al. FIGS. 29 and 30 illustrate the forward direction Al together with a reference numeral A of the first direction A to indicate that the first direction A includes the forward direction Al. FIGS. 29, 32, and 33 illustrate thebackward direction A2 together with the reference numeral A of the first direction A to indicate that the first direction A includes the backward direction A2.

[0105] As illustrated in FIG. 29, the head 11 moves relative to the object 200 in the forward direction Al to coat a first line area on the object 200. After the head 11 finishes coating the first line area, the head 11 moves relative to the object 200 in a second direction B perpendicular to the first direction A to perform line feeding. After the head 11 finishes line feeding, the head 11 moves relative to the object 200 in the backward direction A2 to coat a second line area on the object 200. After the head 11 finishes coating the second line area, the head 11 moves relative to the object 200 in the second direction B to perform line feeding. After the head 11 finishes line feeding, the head 11 moves relative to the object 200 in the forward direction Al to coat a third line area on the object 200. The head 11 of the liquid discharge apparatus 100 moves relative to the object 200 as described above to discharge liquid.

[0106] FIG. 30 is an enlarged diagram of motion 1 in FIG. 29. Each of FIGS. 31A and 3 IB is an enlarged diagram of motion 2 in FIG. 29. As illustrated in FIG. 31 A, the head 11 moves in the second direction B while the head 11 retains an orientation thereof. As illustrated in FIG.3 IB, in motion 2, the orientation of the head 11 may be mirrored about a shaft extending in the second direction B as a rotation shaft, for example. FIG. 32 is an enlarged diagram of motion 3 in FIG. 29. FIG. 33 is an enlarged diagram of motion 4 in FIG. 29. In examples depicted in FIGS. 30, 31 A, 3 IB, 32, and 33, the head 11 includes five nozzles 311 that discharge liquid droplets, respectively.

[0107] For example, if the diameter de of the dot 912 in the trailing end region 121 is smaller than the diameter d of the dot 911 in the outboard region other than the trailing end region 121, a length in the second direction B defined by the dots 912 in the trailing end region 121 is smaller than a length in the second direction B defined by the dots 911 in the outboard region. Accordingly, an area not applied with liquid droplets, that is, a print dropout, may generate between the first line area and the second line area, for example. The print dropout may degrade quality of coating by the liquid discharge apparatus 100.

[0108] The moving mechanism 13 of the liquid discharge apparatus 100 depicted in FIG. 1 moves the head 11 relative to the object 200 reciproc atingly in the forward direction Al and the backward direction A2. As illustrated in FIG. 30, the diameter de of the dot 912 in the forward direction Al in the trailing end region 121 is smaller than the diameter d of the dot 911 in the outboard region of the discharge region 120, that is other than the trailing end region 121. For example, a length of liquid in the second direction B, that lands on the trailing end region 121 in the forward direction Al, is smaller than a length of liquid in the second direction B, that lands on the outboard region of the discharge region 120, that is other than the trailing end region 121 in the forward direction Al. As illustrated in FIG. 32, adiameter de of a dot 913 in a leading end region 122 of the discharge region 120, that is, an upstream end region in the backward direction A2, is greater than the diameter d of the dot 911 in the outboard region of the discharge region 120, that is other than the leading end region 122. For example, a length of liquid in the second direction B, that lands on the upstream end region in the backward direction A2 of the discharge region 120 where the head 11 discharges the liquid onto the object 200, is greater than a length of liquid in the second direction B, that lands on the outboard region of the discharge region 120, that is other than the upstream end region in the backward direction A2. The upstream end region in the backward direction A2 is described as the leading end region 122 for convenience. As illustrated in FIGS. 32 and 33, the trailing end region 121 is aligned with the leading end region 122 in the first direction A.

[0109] The trailing end region 121 serves as a downstream region of the discharge region 120 in the forward direction Al or an upstream region of the discharge region 120 in the backward direction A2. The leading end region 122 serves as a downstream region of the discharge region 120 in the forward direction Al or an upstream region of the discharge region 120 in the backward direction A2. A configuration in which the trailing end region 121 is aligned with the leading end region 122 in the first direction A defines a configuration in which the leading end region 122 encompasses the trailing end region 121 in the first direction A from a different perspective. A position at which the trailing end region 121 is aligned with the leading end region 122 in the first direction A is not limited to a turnaround position where the head 11 turns a moving direction from the forward direction Al to the backward direction A2 and a turnaround position where the head 11 turns the moving direction from the backward direction A2 to the forward direction Al in a reciprocating moving path. The position at which the trailing end region 121 is aligned with the leading end region 122 in the first direction A may be a position other than the turnaround position in the reciprocating moving path.

[0110] The diameter de of the dot 913 in the leading end region 122 of the discharge region 120 in the backward direction A2 is greater than the diameter d of the dot 911 in an outboard region of the discharge region 120, that is other than the leading end region 122. Hence, a length of the leading end region 122 in the second direction B increases. Since the leading end region 122 is aligned with the trailing end region 121 in the first direction A, the head 11 coats an uncoated region on the object 200, that is not coated while the head 11 moves over the trailing end region 121 on the object 200, supplementally while the head 11 moves over the leading end region 122 on the object 200. As a result, the liquid discharge apparatus 100 reduces print dropouts. Reduction of the print dropouts suppresses degradation in quality of coating by the liquid discharge apparatus 100.

[0111] In a region XXXII depicted in FIG. 32, end dots 914 overlap the dots 912 in the trailing end region 121 partially. In examples illustrated in FIGS. 32 and 33, the plurality of dots 913 arranged in the second direction B in the leading end region 122 includes the end dots 914 and dots 915 other than the end dots 914. The end dots 914 are situated at an end of the leading end region 122, that abuts on the trailing end region 121 in the second direction B. The diameter de of each of the end dots 914 is greater than a diameter df of each of the dots 915. Accordingly, the liquid discharge apparatus 100 decreases an amount of liquid droplets that form the dots 915 other than the end dots 914, saving liquid droplets compared to a configuration in which each of the plurality of dots 913 has an increased diameter. Alternatively, the liquid discharge apparatus 100 may have a configuration in which the diameter de of each of the plurality of dots 913 arranged in the second direction B in the leading end region 122 may be greater than the diameter d of the dot 911.

[0112] In an example illustrated in FIG. 33, a center-to-center distance pe between the adjacent dots 913 in the first direction A in the leading end region 122 is greater than the center-to-center distance p between the adjacent dots 911 in the first direction A in an outboard region of the discharge region 120, that is other than the leading end region 122. Accordingly, the liquid discharge apparatus 100 decreases difference in thickness of the coating film between the leading end region 122 and the outboard region other than the leading end region 122. The difference may be caused by an amount of liquid droplets that form the dots 913, that is greater than an amount of liquid droplets that form the dots 911. Consequently, the liquid discharge apparatus 100 reduces uneven thickness of the coating film.

[0113] Referring to FIGS. 34 to 36, a description is provided of discharge regions of the liquid discharge apparatus 100 and a liquid discharge apparatus 100A. FIG. 34 is a view of the object 200, illustrating the discharge region 120 of the liquid discharge apparatus 100 according to the first embodiment of the present invention, as a first example. FIG. 35 is a view of the object 200, illustrating the discharge regions of the liquid discharge apparatus 100A according to the first embodiment of the present invention, as a second example. FIG. 36 is a view of the object 200, illustrating the discharge regions of the liquid discharge apparatus 100A according to the first embodiment of the present invention, as a third example.

[0114] In the liquid discharge apparatus 100 as the first example depicted in FIG. 34, the single head 11 moves relative to the object 200 reciprocatingly and discharges liquid onto the discharge region 120, coating the object 200. The trailing end region 121 defines a trailing end of the discharge region 120 in a direction in which the head 11 moves relative to the object 200 reciprocatingly.

[0115] The liquid discharge apparatus 100A as the second example depicted in FIG. 35 and the third example depicted in FIG. 36 includes a first head 1 la that moves relative to the object 200 reciprocatingly and discharges liquid onto a first region 120a, coating the object 200. The first region 120a includes a trailing end region 121a that defines a trailing end of the first region 120a in a direction in which the first head I la moves relative to the object 200 reciprocatingly. The liquid discharge apparatus 100A further includes a second head 1 lb that moves relative to the object 200 reciprocatingly and discharges liquid onto a second region 120b, coating the object 200. The second region 120b includes a trailing end region 121b that defines a trailing end of the second region 120b in a direction in which the second head 1 lb moves relative to the object 200 reciprocatingly.

[0116] In the second example illustrated in FIG. 35, the first head 1 la moves relative to the object 200 reciprocatingly, coating the first region 120a on the object 200. The second head 1 lb moves relative to the object 200 reciprocatingly, coating the second region 120b on the object 200.

[0117] In the third example illustrated in FIG. 36, the first head 1 la moves relative to the object 200 in a predetermined direction A3, coating the first region 120a on the object 200. The second head 1 lb moves relative to the object 200 in an opposite direction A4 opposite to the predetermined direction A3, coating the second region 120b on the object 200. At least a part of the trailing end region 121a of the first region 120a in the predetermined direction A3 overlaps the second region 120b. Since at least a part of the trailing end region 121a of the first region 120a in the predetermined direction A3 overlaps the second region 120b, while the first head 1 la moves at a substantially constant speed and discharges liquid droplets in a substantially constant amount, the liquid discharge apparatus 100A reduces staining of the object 200 with secondary droplets.

[0118] A description is provided of a construction of a liquid discharge apparatus 100B according to a second embodiment of the present invention. The elements having the names and the reference numerals that are shared with the elements according to the embodiments described above indicate members or constructions that are identical or equivalent. Therefore, detailed descriptions of the elements are omitted properly. The detailed descriptions of the elements are omitted similarly in subsequent embodiments.

[0119] Referring to FIG. 37, a description is provided of the construction of the liquid discharge apparatus 100B according to the second embodiment. FIG. 37 is a view of the liquid discharge apparatus 100B according to the second embodiment of the present invention, illustrating the construction thereof, as one example. The liquid discharge apparatus 100B includes a head 11 A that differs from the head 11 according to the first embodiment in that the head 11A is secured stationarily and coats the object 200 that moves.

[0120] The liquid discharge apparatus 100B depicted in FIG. 37 includes the moving mechanism 13 that holds the object 200 and moves the object 200 to a position in proximity to the head 11 A that is secured stationarily. Thereafter, the moving mechanism 13 moves the object 200 to a liquid discharge position of the head 11 A where the head 11A coats the object 200. The liquid discharge apparatus 100B is preferably used for the object 200 that is light or compact enough to be moved by the moving mechanism 13 or the like. The liquid discharge apparatus 100B according to the second embodiment of the present invention employs a liquid discharge method that is similar to a liquid discharge method employed by the liquid discharge apparatus 100 or 100A according to the first embodiment of the present invention.

[0121] Referring to FIGS. 38 and 39, a description is provided of a construction of a liquid discharge apparatus 100C according to a third embodiment of the present invention. FIG. 38 is a view of the liquid discharge apparatus 100C according to the third embodiment of the present invention, illustrating the construction thereof, as one example. FIG. 39 is a cross-sectional view of the liquid discharge apparatus 100C, taken on line XXXIX-XXXIX in FIG. 38.

[0122] The liquid discharge apparatus 100C includes the head 11, first guides 800, securing guides 810, and second guides 820. The first guides 800 guide and move the head 11 in the first direction A. The securing guides 810 combine the head 11 and the first guides 800 into a unit. The second guides 820 guide and move the head 11 in the second direction B perpendicular to the first direction A. The liquid discharge apparatus 100C according to the third embodiment differs from the liquid discharge apparatus 100 according to the first embodiment in that the head 11 is mounted on a member other than the moving mechanism 13.

[0123] As illustrated in FIGS. 38 and 39, the head 11 of the liquid discharge apparatus 100C is mounted on the first guides 800 such that the head 11 is movable in the first direction A. The securing guides 810 combine the head 11 and the first guides 800 into a unit such that the head 11 and the first guides 800 are movable in the second direction B along the second guides 820. Thus, the head 11 scans the object 200 in a two-dimensional direction along the first guides 800 and the second guides 820, applying liquid onto the object 200. The liquid discharge apparatus 100C according to the third embodiment of the present invention employs a liquid discharge method that is similar to the liquid discharge method employed by the liquid discharge apparatus 100 or 100A according to the first embodiment of the present invention.

[0124] The above describes the embodiments of the present invention. However, the technology of the present invention is not limited to the embodiments described above. For example, theembodiments of the present invention are modified and improved variously within the scope of the present invention.

[0125] According to the embodiments, liquid discharged from a head (e.g., the heads 11 and 11A, the first head Ila, and the second head 11b) includes solution, suspension, emulsion, or the like that contains a solvent such as water and an organic solvent, a colorant such as dye and pigment, a functional material such as a polymerizable compound, resin, and a surfactant, a biocompatible material such as deoxyribonucleic acid (DNA), amino acid, protein, and calcium, an edible ingredient such as natural pigment, or the like. For example, the liquid is used as ink for inkjet printing, a coating material, surface treatment liquid, liquid for forming components of an electronic element and a light-emitting element, liquid for forming an electronic circuit resist pattern, liquid for fabricating a three-dimensional object, and the like.

[0126] Functional units according to the embodiments described above are established by one or more processing circuitry. The processing circuitry in the present specification encompasses a processor programmed to execute the functional units with software like a processor implemented by an electronic circuit. The processing circuitry further encompasses a device designed to execute the functional units described above, such as an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field programmable gate array (FPGA), and a general circuit module.

[0127] The technology of the invention is also applied to coating for an objective other than coloring and applying designs to a vehicle body of an automobile or the like. For example, coating processes for coating the vehicle body of the automobile include a primer coat process for ensuring adhesion, corrosion resistance, and the like of a coating film that coats a vehicle body substrate (e.g., a base layer of the vehicle body), a base coat process for ensuring impact resistance, durability, and the like, and a topcoat process for coloring and applying designs. A coating device applied with the technology of the present invention may be used for the primer coat process or the base coat process in addition to the topcoat process. In a case that the topcoat process is followed by a coating process for applying a protective layer such as a clear layer for adding a glossy finish and protecting the coating film, the coating device applied with the technology of the present invention may be used for the coating process for applying the protective layer. In a case that a protective layer that is peelable coats a coating face to protect the coating face after the automobile is shipped or while the automobile is manufactured in a factory, the coating device applied with the technology of the present invention may be used for the coating process for applying the protective layer. The peelable, protective layer adheres to the coating face of the vehicle body and protects a coat portion chemically or physically from dust, metal powder, oil content, salt content, acid, ultraviolet radiation, and the like. For example, the protective layer is preferably made of a material containing an acrylic copolymer agent as a main ingredient.

[0128] The technology of the present invention is also applied to a liquid droplet discharge apparatus that discharges liquid droplets with an objective other than coating. For example, the technology of the present invention is applied to a marking device that discharges liquid droplets onto an object to mark a particular position on the object.

[0129] The following describes aspects of the embodiments of the present invention, for example.

[0130] A description is provided of a first aspect of the embodiments of the present invention. A liquid discharge apparatus includes a head that discharges liquid onto an object and a moving mechanism that causes relative movement between the head and the object. The head discharges the liquid that lands on the object. The moving mechanism moves the head relative to the object in a first direction that is perpendicular to a second direction. The head discharges the liquid onto a discharge region on the object. The discharge region has a downstream end region in the first direction. The downstream end region defines a trailing end region. The liquid landed on the trailing end region has a length in the second direction, that is smaller than a length in the second direction of the liquid landed on a region of the discharge region, that is other than the trailing end region.

[0131] A description is provided of a second aspect of the embodiments of the present invention. In the liquid discharge apparatus according to the first aspect, a relative moving speed of the head in the trailing end region is lower than a relative moving speed of the head in the region of the discharge region, that is other than the trailing end region.

[0132] A description is provided of a third aspect of the embodiments of the present invention. In the liquid discharge apparatus according to the first aspect or the second aspect, the first direction defines a forward direction. A direction opposite to the forward direction defines a backward direction. The moving mechanism causes the relative movement between the head and the object to be reciprocal in the forward direction and the backward direction. A length in the second direction of the liquid landed on the trailing end region in the forward direction is smaller than a length in the second direction of the liquid landed on the region of the discharge region, that is other than the trailing end region in the forward direction. A length in the second direction of the liquid landed on an upstream end region in the backward direction of the discharge region where the head discharges the liquid onto the object is greater than a length in the second direction of the liquid landed on a region of the discharge region, that is other than the upstream end region in the backward direction. A position of the trailing end region in the forward direction is aligned in the first direction with a position of the upstream end region in the backward direction.

[0133] A description is provided of a fourth aspect of the embodiments of the present invention. In the liquid discharge apparatus according to any one of the first aspect to the third aspect, the head discharges the liquid that lands on the object to form a plurality of dots.

[0134] A description is provided of a fifth aspect of the embodiments of the present invention. In the liquid discharge apparatus according to the fourth aspect, a center-to-center distance between the adjacent dots in the first direction in the trailing end region is smaller than a center-to- center distance between the adjacent dots in the first direction in the region of the discharge region, that is other than the trailing end region.

[0135] A description is provided of a sixth aspect of the embodiments of the present invention. In the liquid discharge apparatus according to the fourth aspect or the fifth aspect, the plurality of dots is arranged in the second direction in the upstream end region and includes an end dot that is situated at an end of the upstream end region in the second direction. The end abuts on the trailing end region. A diameter of the end dot is greater than a diameter of a dot of the plurality of dots, that is other than the end dot.

[0136] A description is provided of a seventh aspect of the embodiments of the present invention. In the liquid discharge apparatus according to any one of the fourth aspect to the sixth aspect, a center-to-center distance between the adjacent dots in the first direction in the upstream end region is greater than a center-to-center distance between the adjacent dots in the first direction in the region of the discharge region, that is other than the upstream end region.

[0137] A description is provided of an eighth aspect of the embodiments of the present invention. The liquid discharge apparatus according to any one of the first aspect to the seventh aspect includes a plurality of heads that includes a first head and a second head. The first head moves in a predetermined direction of the first direction to define a first region on the object. The second head moves in a direction opposite to the predetermined direction of the first direction to define a second region on the object. At least a part of a trailing end region of the first region in the predetermined direction overlaps the second region.

[0138] A description is provided of a ninth aspect of the embodiments of the present invention. A liquid discharge apparatus performs a liquid discharge method in which a head of the liquid discharge apparatus discharges liquid onto an object. A moving mechanism causes relative movement between the head and the object in a first direction. The head discharges the liquid that lands on the object. The moving mechanism moves the head relative to the object in the first direction that is perpendicular to a second direction. The head discharges the liquid onto a discharge region on the object. The discharge region has a downstream end region in the first direction. The downstream end region defines a trailing end region. The liquid landed on the trailing end region has a length in the second direction, that is smaller than a length inthe second direction of the liquid landed on a region of the discharge region, that is other than the trailing end region.

[0139] The above-described embodiments are illustrative and do not limit the present invention. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements and / or features of different illustrative embodiments may be combined with each other and / or substituted for each other within the scope of the present invention. Any one of the above-described operations may be performed in various other ways, for example, in an order different from the one described above.

[0140] This patent application is based on and claims priority to Japanese Patent Application No. 2024-041275, filed on March 15, 2024, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.[Reference Signs List]

[0141] 11 : Head11-1, 11-2, 11-3, 11-4: HeadIla: First head lib: Second head12, 12-1, 12-2, 12-3, 12-4: Detector13, 13-1, 13-2, 13-3, 13-4: Moving mechanism14: Supply portion20: Control unit72: Driver80: Liquid droplet81a, 81b: Primary droplet82a, 82b: Ligament83a, 83b: Secondary droplet91, 91a, 91b: Dot92, 92a, 92b: Satellite dot911, 912, 913, 915: Dot914: End dot120: Discharge region120a: First region120b: Second region121: Trailing end region122: Leading end region180: Coating film800: First guide810: Securing guide820: Second guide901: Controller9001: CPU9002: ROM9003: RAM9004: 1 / F9011: System control unit9012: Data storage unit9013: Memory control unit9014: Discharge cycle signal generation unit9015: Cycle control unit902: Head control unit903: PC9031 : Coating path generation unit9032: Coating data generation unit9033: Discharge frequency generation unit9034: Moving speed generation unit9035: RIP9036: Rendering unit904: Moving mechanism control unit905 : Input device100: Liquid discharge apparatus103: Head unit109: Encoder sensor110: Body111: Supply port112: Collecting port200: Object201: Roof211, 211-1, 211-2, 211-3, 211-4: Coating region230: Compressor310: Valve311: Nozzle321: Nozzle plate322: Channel324: Piezoelectric element325: Liquid330: Liquid tank331: Pipe332: Air regulator333: Tube340: Discharge moduleA: First directionA 1 : Forward directionA2: Backward directionA3: Predetermined directionA4: Opposite directionB : Second directionC: Discharging direction d, de, de, df: Diameter p, pc, pe: Center-to-center distanceLI, L2: Length ql, q2: Cycle tl, t2: ThicknessT 1 : First periodT2: Second periodT10, Tl-1, Tl-2, Tl-3, Tl-4: Relative movement pathAl, A2: Open periodVI, V2: Driving voltage

Claims

[CLAIMS]

1. A liquid discharge apparatus comprising: a head to discharge liquid onto an object; and a moving mechanism to cause relative movement between the head and the object, the head to discharge the liquid that lands on the object, the moving mechanism to move the head relative to the object in a first direction that is perpendicular to a second direction, the head to discharge the liquid onto a discharge region on the object, the discharge region having a downstream end region in the first direction, the downstream end region defining a trailing end region, the liquid, that is landed on the trailing end region, having a length in the second direction, the length being smaller than a length in the second direction of the liquid landed on a region of the discharge region, that is other than the trailing end region.

2. The liquid discharge apparatus according to claim 1, wherein a relative moving speed of the head in the trailing end region is lower than a relative moving speed of the head in the region of the discharge region, that is other than the trailing end region.

3. The liquid discharge apparatus according to claim 1 or 2, wherein the first direction defines a forward direction, wherein a direction opposite to the forward direction defines a backward direction, wherein the moving mechanism causes the relative movement between the head and the object to be reciprocal in the forward direction and the backward direction, wherein a length in the second direction of the liquid landed on the trailing end region in the forward direction is smaller than a length in the second direction of the liquid landed on the region of the discharge region, that is other than the trailing end region in the forward direction, wherein a length in the second direction of the liquid landed on an upstream end region in the backward direction of the discharge region where the head discharges the liquid onto the object is greater than a length in the second direction of the liquid landed on a region of the discharge region, that is other than the upstream end region in the backward direction, and wherein a position of the trailing end region in the forward direction is aligned in the first direction with a position of the upstream end region in the backward direction.

4. The liquid discharge apparatus according to any one of claims 1 to 3, wherein the head discharges the liquid that lands on the object to form a plurality of dots.

5. The liquid discharge apparatus according to claim 4,wherein the plurality of dots includes adjacent dots in the first direction, and wherein a center-to-center distance between the adjacent dots in the trailing end region is smaller than a center-to-center distance between the adjacent dots in the region of the discharge region, that is other than the trailing end region.

6. The liquid discharge apparatus according to claim 4 or 5, wherein the plurality of dots is arranged in an upstream end region in the backward direction of the discharge region and includes an end dot that is situated at an end of the upstream end region in the second direction, that abuts on the trailing end region, and wherein a diameter of the end dot is greater than a diameter of a dot of the plurality of dots, that is other than the end dot.

7. The liquid discharge apparatus according to any one of claims 4 to 6, wherein the plurality of dots includes adjacent dots in the first direction, and wherein a center-to-center distance between the adjacent dots in an upstream end region in the backward direction of the discharge region is greater than a center-to-center distance between the adjacent dots in a region of the discharge region, that is other than the upstream end region.

8. The liquid discharge apparatus according to any one of claims 1 to 7, further comprising another head to discharge liquid onto the object, wherein the head moves in a predetermined direction of the first direction to define a first region on the object, wherein said another head moves in a direction opposite to the predetermined direction of the first direction to define a second region on the object, and wherein at least a part of a trailing end region of the first region in the predetermined direction overlaps the second region.

9. A liquid discharge method performed by a liquid discharge apparatus, the liquid discharge method comprising: causing a moving mechanism to move a head relative to an object in a first direction that is perpendicular to a second direction; causing the head to discharge liquid that lands on the object; causing the head to discharge the liquid in a discharge region on the object, the discharge region having a downstream end region in the first direction, the downstream end region defining a trailing end region; and causing a length in the second direction of the liquid landed on the trailing end region to be smaller than a length in the second direction of the liquid landed on a region of the discharge region, that is other than the trailing end region.

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