inkjet printer

Abstract

In inkjet printers with adjustable scanning speed, the goal is to miniaturize the ink receiving component. [Solution] The inkjet printer 1 moves the ink head 50 in the main scanning direction Y using the movement control unit 101. At this time, the flushing control unit 102 ejects ink from nozzle rows 55A to 55D onto the ink receiving member 41 to perform flushing. For example, the flushing control unit 102 ejects ink from nozzle row 55D at a predetermined rate, and then ejects ink from nozzle row 55C. The number of ejections in flushing is determined by the ejection number determination unit 103. The ejection number determination unit 103 determines the number of ejections based on the speed or acceleration of the ink head 50.

Description

Technical Field

[0001] The present invention relates to an inkjet printer.

Background Art

[0002] In an inkjet printer, the ink in the nozzles of the ink head is exposed to air, so the ink may thicken in the nozzles due to drying. However, if the ink in the nozzles thickens, there is a risk of poor ink ejection. Therefore, conventionally, in order to prevent poor ink ejection, flushing is performed before the start of printing or during printing (see, for example, Patent Document 1). Here, flushing means forcibly ejecting ink from the nozzles to the ink receiving member. By performing flushing, the thickened ink is discharged to the ink receiving member, so that the viscosity of the ink in the nozzles can be properly maintained. Therefore, poor ejection can be prevented.

[0003] The ink receiving member is disposed on the side of the platen that supports the recording medium. When flushing is performed during printing, the ink head moves from a position directly above the platen to a position directly above the ink receiving member. Then, after performing flushing, the ink head reverses its traveling direction and moves from the flushing position to the printing position.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] For example, as shown in Figure 11, suppose the ink head 200 has nozzle rows A, B, C, and D. If the ink head 200 is stopped in the flushing position and ink is ejected simultaneously from all nozzle rows, a relatively large ink receiving member 250 with a width W250 is required. Also, the ink head 200 must be stopped in the flushing position from the start to the end of the flushing process. Therefore, if flushing is performed in the middle of printing, the time required for printing will be increased.

[0006] On the other hand, as shown in Figures 12(a) to (d), a method is known in which the ink head 200 is moved while sequentially flushing each nozzle row. By delaying the timing of ink ejection in the order of row D → row C → row B → row A by a predetermined time, sequential flushing can be performed for each nozzle row. In this case, the width W250 of the ink receiving member 250 can be made relatively small. Also, since it is not necessary to stop the ink head 200 at the flushing position, the printing time including flushing can be shortened.

[0007] Incidentally, inkjet printers capable of executing multiple printing modes with different ink head movement speeds (hereinafter referred to as scan speeds) are known. For example, in addition to a standard printing mode, there are inkjet printers that can execute a high-speed printing mode with a relatively high scan speed and a high-quality printing mode with a relatively low scan speed. When the above method is attempted with such an inkjet printer, if the scan speed is slow, the ejected ink may spill out of the ink receiving component.

[0008] For example, as shown in Figure 13(a), the ink head 200 moves to the right and ejects ink from column D, and then ejects ink from column C after a predetermined time. As shown in Figure 13(b), when the scan speed is V10, the ink ejected from column C is received by the ink receiving member 250. However, as shown in Figure 13(c), when the scan speed is V20, which is less than V10, ink may be ejected from column C before it reaches directly above the ink receiving member 250. In this case, the ink ejected from column C will spill out to the left of the ink receiving member 250.

[0009] To prevent ink from bleeding even at slow scanning speeds, the ink receiving member 250 must be extended to the left, as shown in Figure 13(d). However, this presents the challenge of increasing the size of the ink receiving member 250.

[0010] This invention has been made in view of the above, and its purpose is to miniaturize the ink receiving member in an inkjet printer with a changeable scanning speed. [Means for solving the problem]

[0011] The inkjet printer disclosed herein includes an ink head having a plurality of nozzles for ejecting ink arranged in a first direction, a moving mechanism for moving the ink head in a second direction intersecting the first direction, an ink receiving member for receiving the ink ejected from the ink head, and a control device for controlling the ink head and the moving mechanism. The ink head has a first nozzle row in which a plurality of the nozzles are arranged in a first direction, and a second nozzle row in which a plurality of the nozzles are arranged in the first direction and positioned offset from the first nozzle row in the second direction. The control device includes a moving control unit for moving the ink head at a predetermined speed using the moving mechanism, a flushing control unit for performing flushing from the first nozzle row or the second nozzle row of the ink head moved by the moving control unit toward the ink receiving member, and a number determination unit for determining the number of ink droplets to be ejected from the nozzles during the flushing by the flushing control unit. When the ink head is being moved by the movement control unit, the flushing control unit performs the flushing from at least some of the nozzles of the first nozzle row toward the ink receiving member with a first number of shots determined by the shot count determination unit, and after starting the flushing from at least some of the nozzles of the first nozzle row toward the ink receiving member, it performs the flushing from at least some of the nozzles of the second nozzle row toward the ink receiving member. When the ink head is being moved by the movement control unit, the flushing control unit performs the flushing from at least some of the nozzles of the first nozzle row toward the ink receiving member with a second number of shots determined by the shot count determination unit, and after starting the flushing from at least some of the nozzles of the first nozzle row toward the ink receiving member, it performs the flushing from at least some of the nozzles of the second nozzle row toward the ink receiving member. The second speed is smaller than the first speed, and the second number of shots is larger than the first number of shots.

[0012] In the above inkjet printer, the flushing control unit flushes the first nozzle row when the ink head moves due to the movement control unit, and then flushes the second nozzle row. The number of ink droplets ejected by the first nozzle row is determined by the droplet count determination unit. The droplet count determination unit determines the droplet count based on the speed of the ink head when it moves due to the movement control unit. When the ink head moves at a first speed, flushing is performed with a first number of droplets. When the ink head moves at a second speed, which is slower than the first speed, flushing is performed with a second number of droplets, which is greater than the first number. In this way, when the speed of the ink head changes, the position of the second nozzle row when ink is ejected from the second nozzle row can be adjusted by increasing or decreasing the droplet count based on the speed. This makes it possible to adjust the position of the ink ejected into the ink receiving member. Therefore, the ink receiving member can be miniaturized. [Effects of the Invention]

[0013] According to the present invention, the ink receiving member can be miniaturized in an inkjet printer with a changeable scanning speed. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a front view of an inkjet printer according to an embodiment. [Figure 2] Figure 2 is a bottom view of the ink head. [Figure 3] Figure 3 is a cross-sectional view taken along line III-III in Figure 2. [Figure 4] Figure 4 is a front view of the cleaning unit. [Figure 5] Figure 5 is a block diagram of the control device. [Figure 6] Figure 6 shows an example of a drive waveform. [Figure 7] Figure 7 schematically shows the amount of displacement in the position where ink is ejected during flushing. [Figure 8A]FIG. 8A is a front view of the periphery of the ink head when the scan speed is maximum. [Figure 8B] FIG. 8B is a schematic view of the periphery of the ink head when ink is ejected a predetermined number of times from the state shown in FIG. 8B. [Figure 8C] FIG. 8C is a front view of the periphery of the ink head when ink is further ejected a predetermined number of times from the state of FIG. 8B. [Figure 8D] FIG. 8D is a front view of the periphery of the ink head when ink is ejected a predetermined number of times from each nozzle row. [Figure 9] FIG. 9 is a diagram corresponding to FIG. 8B in the case of the standard printing mode. [Figure 10] FIG. 10 is a diagram corresponding to FIG. 8D in the case of the standard printing mode. [Figure 11] FIG. 11 is a diagram showing the state of flushing in which ink is simultaneously ejected from all nozzle rows of the stopped ink head. [Figure 12] FIGS. 12(a) to (d) are diagrams showing the state of flushing in which ink is ejected in order for each nozzle row while moving the ink head. [Figure 13] FIG. 13(a) is a diagram showing the state of ejecting ink from the nozzle row of column D while moving the ink head. FIG. 13(b) is a diagram showing the state of ejecting ink from the nozzle row of column C while moving the ink head at speed V10. FIG. 13(c) is a diagram showing the state of ejecting ink from the nozzle row of column C while moving the ink head at speed V20. FIG. 13(d) is a diagram showing the state of ejecting ink from the nozzle row of column C while moving the ink head at speed V20 when the ink receiving member is extended to the left.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Naturally, the embodiments described herein are not intended to limit the present invention. Furthermore, the same reference numerals are used for members and parts that perform the same function, and redundant explanations are omitted or simplified as appropriate.

[0016] Figure 1 is a front view of the inkjet printer (hereinafter simply referred to as "printer") 1 according to this embodiment. In the following description, left, right, top, and bottom refer to the left, right, top, and bottom, respectively, as seen from the perspective of a user (not shown) standing in front of the printer 1. The direction from the printer 1 towards the user is referred to as the front, and the direction from the user towards the printer 1 is referred to as the rear. The symbols F, Rr, L, R, U, and D in the drawing represent front, rear, left, right, top, and bottom, respectively.

[0017] In the drawings, the symbol Y represents the main scanning direction. Here, the main scanning direction is the direction in which the ink head 50 (see Figure 2), described later, moves while ejecting ink. The main scanning direction Y is an example of a second direction in the present invention. In the drawings, the symbol X (see Figure 2) represents the sub-scanning direction, which is perpendicular to the main scanning direction Y. The sub-scanning direction X is an example of a first direction in the present invention. In this embodiment, the main scanning direction Y coincides with the left-right direction, and the sub-scanning direction X coincides with the front-back direction. In the drawings, the symbol Z represents the up-down direction. However, these directions are defined merely for the convenience of explanation and do not limit the installation configuration of the printer 1 in any way, nor do they limit the present invention in any way.

[0018] The printer 1 shown in Figure 1 is an inkjet printer, a so-called inkjet printer. In this embodiment, the printer 1 is a roll-to-roll type printer that unfolds the recording medium 5 on the platen 4 and moves it in the sub-scanning direction X.

[0019] As shown in Figure 1, the printer 1 prints onto the recording medium 5. The recording medium 5 is, for example, recording paper. However, the recording medium 5 is not limited to recording paper. The recording medium 5 is not limited to paper, but may also be a sheet or film made of resin such as polyvinyl chloride or polyester, a fabric such as woven or nonwoven fabric, or other media.

[0020] The printer 1 comprises a casing 2, a platen 4 supporting a recording medium 5, a guide rail 6 extending in the main scanning direction Y, a carriage 8 slidably engaged with the guide rail 6, an ink head 50 (see Figure 2) fixed to the carriage 8, and a cleaning unit 40. The printer 1 also includes a head moving mechanism 30 for moving the carriage 8 in the main scanning direction Y, a transport mechanism 20 for moving the recording medium 5 in the sub-scanning direction X, and a control device 100.

[0021] The transport mechanism 20 includes a pinch roller 21, a grid roller 22, and a feed motor 23. The pinch roller 21 is positioned above the platen 4 and below the guide rail 6. The pinch roller 21 presses down on the recording medium 5 from above. The grid roller 22 is provided on the platen 4. The upper part of the grid roller 22 is exposed above the platen 4. The grid roller 22 faces the pinch roller 21. The installation positions and number of the pinch roller 21 and grid roller 22 are not particularly limited. In this embodiment, the pinch roller 21 and grid roller 22 are positioned at the left end and right end of the platen 4, respectively. The feed motor 23 is connected to the grid roller 22. The feed motor 23 rotates the grid roller 22. When the grid roller 22 rotates with the recording medium 5 sandwiched between the pinch roller 21 and the grid roller 22, the recording medium 5 is transported in the sub-scanning direction X. The feed motor 23 is electrically connected to the control device 100. The feed motor 23 is controlled by the control device 100. Note that the above configuration of the transport mechanism 20 is just an example. The transport mechanism 20 only needs to be able to move the recording medium 5 in the sub-scanning direction X, and its specific configuration is not particularly limited.

[0022] The head movement mechanism 30 is a mechanism that moves the ink head 50 (see Figure 2) in the main scanning direction Y. The head movement mechanism 30 is an example of a movement mechanism in the present invention. Here, the head movement mechanism 30 is configured to move the ink head 50 in the main scanning direction Y via a carriage 8. The head movement mechanism 30 comprises a left pulley 31a, a right pulley 31b, a belt 32, and a carriage motor 33. The left pulley 31a is located near the left end of the guide rail 6. The right pulley 31b is located near the right end of the guide rail 6. The belt 32 is, for example, endless and is wrapped around the left pulley 31a and the right pulley 31b. The carriage 8 is fixed to the belt 32. The carriage motor 33 is connected to the right pulley 31b. When the carriage motor 33 is driven, the right pulley 31b rotates, and the belt 32 travels between the left pulley 31a and the right pulley 31b. As a result, the carriage 8 and the ink head 50 move along the guide rail 6 in the main scanning direction Y. The carriage motor 33 is electrically connected to the control device 100 and is controlled by the control device 100. Note that the above configuration of the head moving mechanism 30 is just one example. The head moving mechanism 30 only needs to be able to move the ink head 50 in the main scanning direction Y, and its specific configuration is not particularly limited.

[0023] As shown in Figure 2, in this embodiment, the ink head 50 is mounted on the carriage 8. The ink head 50 includes first to fourth ink heads 51 to 54, which are separate from each other.

[0024] The first ink head 51 has a nozzle plate 58. The nozzle plate 58 forms the bottom surface of the first ink head 51 and faces the recording medium 5 (see Figure 1) on the platen 4 (see Figure 1). Multiple nozzles 55 for ejecting ink are formed on the nozzle plate 58. The nozzles 55 are arranged in the sub-scanning direction X, forming a nozzle row 55A. Note that in Figure 2, the illustration of the nozzle row 55A, specifically the intermediate nozzles 55 arranged in the sub-scanning direction X, is omitted.

[0025] Figure 3 is a cross-sectional view taken along line III-III in Figure 2. The first ink head 51 has an ink chamber 61, a plurality of pressure chambers 62 communicating with the ink chamber 61, a diaphragm 63 partitioning the pressure chambers 62, and a piezoelectric element 64 attached to the diaphragm 63. The pressure chambers 62, diaphragm 63, and piezoelectric element 64 are provided for each nozzle 55, and their number is the same. The piezoelectric element 64 is electrically connected to the control device 100. When the control device 100 drives the piezoelectric element 64, the piezoelectric element 64 is displaced and the diaphragm 63 flexes. As a result, the ink in the pressure chamber 62 is pressurized or depressurized, and ink is ejected from the nozzle 55.

[0026] As shown in Figure 2, in this embodiment, the first ink head 51, the second ink head 52, the third ink head 53, and the fourth ink head 54 have similar configurations. The configurations of the second to fourth ink heads 52 to 54 are the same as those of the first ink head 51, so their descriptions will be omitted. Hereafter, the nozzle rows of the second ink head 52, the third ink head 53, and the fourth ink head 54 will be referred to as nozzle rows 55B, 55C, and 55D, respectively, from left to right in Figure 2. The ink head 50 according to this embodiment has four nozzle rows 55A to 55D. Here, the four nozzle rows 55A to 55D are arranged at equal intervals in the main scanning direction Y. As shown in Figure 2, the distance between each nozzle row is a width Ld. The number of ink heads provided by the printer 1 and the number of nozzle rows formed on each ink head are not particularly limited.

[0027] As shown in Figure 1, the cleaning unit 40 is located to the right of the platen 4. The cleaning unit 40 is located below the ink head 50. Figure 4 is a front view of the cleaning unit 40. As shown in Figure 4, the cleaning unit 40 comprises a flushing unit 42, a wiping unit 46, and a capping unit 48. The flushing unit 42, the wiping unit 46, and the capping unit 48 are aligned in the main scanning direction Y. Here, the flushing unit 42, the wiping unit 46, and the capping unit 48 are arranged from left to right.

[0028] The flushing unit 42 comprises an ink receiving member 41, an absorbent 43 disposed inside the ink receiving member 41, a tube 44 connected to the ink receiving member 41, and a pump 45 connected to the tube 44. The ink head 50 (see Figure 2) is capable of flushing, which forces ink from the nozzle 55 (see Figure 2) toward the ink receiving member 41. By performing flushing by the ink head 50 before the start of printing or during printing, the viscosity of the ink inside the nozzle 55 is suppressed, and ink ejection problems during printing can be prevented.

[0029] The ink receiving member 41 is a member that receives the ink discharged from the ink head 50 during flushing. Here, the ink receiving member 41 is formed by a container with an open top. However, the ink receiving member 41 only needs to be a member that can receive ink, and its specific shape is not particularly limited. The absorbent 43 is made of a member that can absorb ink, and here it is made of a porous material such as a sponge. However, the material and structure of the absorbent 43 are not limited in any way. Also, the absorbent 43 is not necessarily required and can be omitted. An outlet 41a is formed in the ink receiving member 41. The tube 44 is connected to the outlet 41a. The tube 44 is a passage for discharging the ink from inside the ink receiving member 41. The discharge passage is not limited to the tube 44, and may be a pipe, for example. The pump 45 forcibly discharges the ink from the ink receiving member 41 through the tube 44. Note that the flushing unit 42 described above is just one example. The flushing unit 42 does not necessarily have to include the tube 44 and the pump 45. The ink receiving member 41 may simply be a cap.

[0030] The wiping unit 46 removes ink or foreign matter adhering to the nozzle plate 58 (see Figure 2) of the ink head 50 by wiping the nozzle plate 58. The wiping unit 46 has a wiper 46A made of a material such as rubber. Various conventionally known wiping units for inkjet printers can be suitably used in the wiping unit 46.

[0031] The capping unit 48 prevents the ink from drying out inside the nozzle 55 (see Figure 2) of the ink head 50 by covering the nozzle 55 (see Figure 2). In this embodiment, the capping unit 48 has a first cap 48a attached to the first ink head 51 (see Figure 2), a second cap 48b attached to the second ink head 52 (see Figure 2), a third cap 48c attached to the third ink head 53 (see Figure 2), and a fourth cap 48d attached to the fourth ink head 54 (see Figure 2). An absorbent material 49 for absorbing ink is provided inside the first to fourth caps 48a to 48d. The absorbent material 49 is made of a porous material such as a sponge, similar to the absorbent material 43. The first to fourth caps 48a to 48d are configured to be able to move up and down by a lifting mechanism (not shown). The first to fourth caps 48a to 48d are attached to the first to fourth ink heads 51 to 54 by rising when they are directly below the first to fourth ink heads 51 to 54, respectively. Although not shown in the illustration, the capping unit 48 may be configured to forcibly draw ink from the nozzles 55 to the first to fourth caps 48a to 48d by a suction pump.

[0032] Figure 5 is a block diagram of the control device 100 according to this embodiment. The control device 100 is a device that controls printing to the recording medium 5 (see Figure 1) in the printer 1. The configuration of the control device 100 is not particularly limited. The control device 100 is, for example, a microcomputer. The hardware configuration of the microcomputer is not particularly limited, but for example, it includes an interface (I / F) for receiving print data from an external device such as a host computer, a central processing unit (CPU) for executing instructions of the control program, a ROM (read-only memory) for storing the program executed by the CPU, a RAM (random access memory) used as a working area for expanding the program, and a storage device such as memory for storing the program and various data. As shown in Figure 1, the control device 100 is located inside the casing 2. However, the control device 100 does not have to be located inside the casing 2. For example, the control device 100 may be a computer installed outside the casing 2. In this case, the control device 100 is connected to the printer 1 so as to be able to communicate via wired or wireless connection.

[0033] As shown in Figure 5, the control device 100 is communicatively connected to the feed motor 23, the carriage motor 33, and the piezoelectric element 64. The control device 100 controls the feed motor 23, which transports the recording medium 5 (see Figure 1) in the sub-scanning direction X. The control device 100 controls the carriage motor 33, which moves the ink head 50 (see Figure 1) together with the carriage 8 (see Figure 1) in the main scanning direction Y. The control device 100 controls the piezoelectric element 64, which controls the amount of ink ejected from the ink head 50 and the timing of ink ejection.

[0034] The control device 100 comprises a movement control unit 101, a flashing control unit 102, and a shot count determination unit 103. The functions of each part of the control device 100 are implemented by a program. This program is read from a recording medium such as a CD or DVD. Alternatively, this program may be downloaded via the internet. Furthermore, the functions of each part of the control device 100 may also be implemented by a processor and / or circuits.

[0035] The movement control unit 101 moves the ink head 50 at a predetermined speed or predetermined acceleration using the head movement mechanism 30. In this embodiment, the movement control unit 101 controls the movement speed of the carriage 8 by controlling the rotation speed of the carriage motor 33, thereby moving the ink head 50 at a predetermined speed or predetermined acceleration. The predetermined speed or predetermined acceleration of the ink head 50 is determined, for example, by the print data, which is the image data to be printed on the recording medium 5 (see Figure 1), and the printing conditions.

[0036] The flushing control unit 102 performs flushing from the nozzle rows 55A to 55D (see Figure 2) of the ink head 50 (see Figure 2), which is moved by the movement control unit 101, toward the ink receiving member 41 (see Figure 4). For example, when the ink head 50 is moving to the right while flushing, the flushing control unit 102 performs flushing from at least some of the nozzles 55 (see Figure 2) of the nozzle row 55D toward the ink receiving member 41 for a number of times determined by the number of shots determination unit 103, which will be described later, when the ink head 50 is moved by the movement control unit 101 and the nozzle row 55D reaches a predetermined position in the main scanning direction Y. Subsequently, the flushing control unit 102 performs flushing from at least some of the nozzles 55 of the nozzle row 55C (see Figure 2) toward the ink receiving member 41. The same applies to the other nozzle rows. Here, the number of shots refers to the number of times each nozzle 55 ejects ink during flushing.

[0037] The flushing control unit 102, for example, performs flushing from at least some of the nozzles 55 of nozzle row 55D shown in Figure 2, and then, when nozzle row 55C reaches a predetermined position in the main scanning direction Y, performs flushing from at least some of the nozzles 55 of nozzle row 55C toward the ink receiving member 41 (see Figure 4). Similarly, when flushing is performed from nozzle rows 55B and 55A, the flushing control unit 102 performs flushing of each nozzle 55 of nozzle rows 55B and 55A when they reach a predetermined position in the main scanning direction Y. That is, the position in the main scanning direction Y when flushing is started for at least some of the nozzles 55 of nozzle rows 55A to 55D is the same. However, the position in the main scanning direction Y when flushing is started for at least some of the nozzles 55 of nozzle rows 55A to 55D does not have to be the same.

[0038] Figure 6 shows an example of a drive waveform. The drive waveform DW shown in Figure 6 represents the waveform of the signal supplied to the piezoelectric element 64 (see Figure 3). When the flashing control unit 102 (see Figure 5) performs flashing of the nozzle 55 (see Figure 3), it supplies the drive waveform DW to the piezoelectric element 64. As a result, ink is ejected from the nozzle 55. The drive waveform DW is a waveform with a drive frequency of f [Hz]. Therefore, when flashing is performed by the flashing control unit 102, ink is ejected every 1 / f [sec]. Note that the drive waveform DW that ejects ink from the nozzle 55 during printing and the drive waveform DW that ejects ink from the nozzle 55 during flashing may be the same waveform or different waveforms.

[0039] The flushing control unit 102 shown in Figure 5 performs flushing from at least some of the nozzles 55 of nozzle row 55D, and then, for example, performs continuous flushing from at least some of the nozzles 55 of nozzle row 55C toward the ink receiving member 41. As described above, the flushing by the flushing control unit 102 ejects ink every 1 / f [sec]. Therefore, for example, when flushing is performed continuously from nozzle row 55D and nozzle row 55C, and ink is ejected every 1 / f [sec] by the drive waveform DW, ink may be ejected from nozzle row 55C 1 / f [sec] after the completion of the last ejection of flushing from nozzle row 55D. However, the time interval between the last ejection of flushing from nozzle row 55D and the first ejection of flushing from nozzle row 55C does not have to be 1 / f [sec] later. The nozzle rows are controlled so that no other ejection operations are included between the last ejection of flushing from nozzle row 55D and the first ejection from nozzle row 55C.

[0040] The number of shots determination unit 103 determines the number of ink shots to be ejected from the nozzle 55 (see Figure 2) by the flushing control unit 102. The number of shots determination unit 103 increases the number of shots when the predetermined speed or predetermined acceleration of the ink head 50 (see Figure 2) moving by the movement control unit 101 is small, and decreases the number of shots when the predetermined speed or predetermined acceleration of the ink head 50 (see Figure 2) moving by the movement control unit 101 is large. The specific method of determining the number of shots by the number of shots determination unit 103 will be described later.

[0041] The control device 100 performs printing and flushing operations by controlling the head movement mechanism 30, the transport mechanism 20, and the piezoelectric element 64. During printing, the ink head 50 moves above the platen 4 (see Figure 1) in the main scanning direction Y, ejecting ink toward the recording medium 5. The ejected ink lands on the recording medium 5, forming an image or the like on the recording medium 5. In the following description, the left side of the main scanning direction Y is referred to as the Y1 direction (see Figure 1), and the right side is referred to as the Y2 direction (see Figure 1). In this embodiment, the home position of the ink head 50 (see Figure 2) is provided in the Y2 direction relative to the platen 4. The ink head 50 moves in the Y1 direction while ejecting ink, completing one pass of printing. The transport mechanism 20 transports the recording medium 5 forward for a predetermined length. After that, the ink head 50 moves in the Y2 direction while ejecting ink, and the ink head 50 returns to its home position, completing the next pass of printing. Similar to when the previous pass of printing was completed, the transport mechanism 20 transports the recording medium 5 forward for a predetermined length. The same process is then repeated, and printing of the next pass is executed. Once all passes have been printed, printer 10 terminates the printing operation.

[0042] In this embodiment, flushing is performed before printing starts and during printing. The control device 100 performs flushing during printing, for example, after each pass of printing is completed. However, the timing of flushing is not particularly limited. The control device 100 may, for example, perform flushing after a predetermined number of passes, two or more, have been completed. Also, in this embodiment, flushing is performed periodically, but it is also possible to perform flushing irregularly.

[0043] The control device 100 does not stop the ink head 50 directly above the flushing unit 42 (see Figure 4) during flushing. The control device 100 performs flushing while moving the ink head 50. Flushing is performed while the ink head 50 passes directly above the flushing unit 42.

[0044] In this embodiment, the printer 1 offers multiple printing modes with different movement speeds (scan speeds) in the main scanning direction Y of the ink head 50. The printer 1 offers a standard printing mode, a high-speed printing mode, and a high-quality printing mode. The scan speeds differ in the standard printing mode, high-speed printing mode, and high-quality printing mode. Incidentally, if the scan speed during printing is different, the scan speed during the flashing process performed in the middle of printing will also be different.

[0045] In the following explanation, we will assume that flushing is performed when the ink head 50 (see Figure 2) is moving in the Y2 direction directly above the flushing unit 42 (see Figure 4). When flushing is performed while the ink head 50 is moving in the Y2 direction, ink will be ejected sequentially from the rightmost nozzle row to the leftmost nozzle row of the nozzle rows 55A to 55D (see Figure 2) of the ink head 50. Here, we assume that the time from when one nozzle row starts ejecting until the nozzle row to its left starts ejecting is constant, regardless of the scan speed. Then, for example, if the scan speed is low, the nozzle row to the left may eject ink before it reaches directly above the ink receiving member 41, and the ink may spill out to the left of the ink receiving member 41 (see also Figure 13(c)).

[0046] Figure 7 schematically illustrates the amount of displacement in the position where ink is ejected during flushing. Figure 7 schematically illustrates the position where ink is ejected in a plan view. The ejection position F1 in Figure 7 indicates the leftmost position of the impact point when ink is ejected from nozzle row 55D (i.e., the rightmost nozzle row) at a certain scan speed V1 [mm / s]. In the main scanning direction Y, the ejection position F1 is located to the right of the left end of the ink receiving member 41 by a width W0. At a scan speed of V1 [mm / s], the position of ink ejection due to flushing is limited to the range to the right of the ejection position F1.

[0047] The ink ejection start position Dd shown in Figure 7 indicates the position of nozzle row 55D in the main scanning direction Y when ink is ejected from nozzle row 55D (see Figure 2) when flushing is performed at a scan speed V2 [mm / s] (V1 > V2) which is slower than the scan speed V1 [mm / s]. Similarly, ink ejection start positions Dc, Db, and Da indicate the positions of nozzle rows 55C, 55B, and 55A in the main scanning direction Y when ink is ejected from nozzle rows 55C, 55B, and 55A, respectively. Here, in the following explanation, the area where ink lands due to flushing is called the ink impact area. The ink impact area Ad indicates the range in which ink is ejected from nozzle row 55D when flushing is performed at a scan speed V2 [mm / s]. That is, it indicates the range in which ink is ejected when nozzle row 55D moves in the Y2 direction from the position of ink ejection start position Dd and ejects a predetermined number of ink droplets. Similarly, the ink impact areas Ac, Ab, and Aa indicate the range in which ink is ejected when nozzle rows 55C, 55B, and 55A move in the Y2 direction from the ink ejection start positions Dc, Db, and Da, and eject a predetermined number of ink shots. Note that in Figure 7, for illustrative purposes, the ink impact areas Ad, Ac, Ab, and Aa are shown in positions that are offset vertically in the view of the drawing; however, in reality, the ink impact areas Ad, Ac, Ab, and Aa are aligned vertically in the view of the drawing.

[0048] As shown in Figure 7, the left edge of the ink impact area Ad is located to the left of the ejection position F1 by a width W1. Therefore, when the scan speed is V2 [mm / s], the ink impact area is shifted to the left by a width W1 for each nozzle row compared to when the scan speed is V1 [mm / s]. Here, let t [sec] be the time from when the ink is ejected from one nozzle row until the ink hits the ink receiving member 41. Assume that the time t [sec] is the same for both scan speeds V1 [mm / s] and V2 [mm / s]. When the scan speed is V1 [mm / s], the ink ejected from one nozzle row travels in the Y2 direction at a scan speed of V1 [mm / s] for t [sec]. Similarly, when the scan speed is V2 [mm / s], the ink ejected from one nozzle row travels in the Y2 direction at a scan speed of V2 [mm / s] for t [sec]. Therefore, the width W1 is expressed by the following equation (1). W1[mm]=V1[mm / s]×t[sec]-V2[mm / s]×t[sec]...(1) Here, if we let the ratio of scan speed V1 to scan speed V2 be r = V1 / V2, then equation (1) can be transformed using the ratio r to get equation (2). W1[mm]=(r-1) / r×V1[mm / s]×t[sec]...(2)

[0049] The width W1 [mm] is the amount by which the ink impact area shifts for each nozzle row when the scan speed is V2 [mm / s]. If there are multiple nozzle rows (four in this embodiment), the ink impact area shifts further by the number of nozzle rows. When all nozzle rows have been flushed, the left edge of the last ejected ink impact area (ink impact area Aa in Figure 7) and the ejection position F1 are shifted by a width W2. If the number of nozzle rows that are flushed is n [number], the width W2 is expressed by the following equation (3) based on equation (2). W2[mm]=n[pieces]×(r-1) / r×V1[mm / s]×t[sec]...(3) In Figure 7, there are four nozzle rows, so n=4. The ejection position F1 is located W0 to the right of the left end of the ink receiving member 41, so the width W3 [mm] of the area of ​​ink that spills out of the ink receiving member 41 in the main scanning direction Y is expressed by the following equation (4). W3[mm]=W0-n[pieces]×(r-1) / r×V1[mm / s]×t[sec]...(4) Therefore, when the scan speed is changed from V1 [mm / s] to V2 [mm / s], the ink receiving member 41 needs to be extended to the left by a width W3 [mm] or more as shown in equation (4). At this time, since the ink receiving member 41 becomes larger, the printer 1 needs to be made larger.

[0050] In the following explanation, the drive frequency during flashing will be denoted as fmax[Hz]. The drive frequency fmax[Hz] is the maximum drive frequency fmax[Hz] for printer 1.

[0051] First, let's explain the flashing in high-speed printing mode. Let the scan speed in high-speed printing mode be Vmax [mm / s]. Vmax [mm / s] is the maximum scan speed in printer 1. Vmax [mm / s] is an example of the first speed in this invention. Let N [times] be the number of flashes in high-speed printing mode. N [times] is an example of the first number of flashes in this invention. Figure 8A is a front view of the area around the ink head 50 when the scan speed is Vmax [mm / s]. The ink head 50 is moved in the Y2 direction at the scan speed Vmax [mm / s] by the movement control unit 101 (see Figure 5).

[0052] The ink head 50 ejects ink while moving in the Y2 direction at a scan speed Vmax [mm / s]. Ink ejection is controlled by the flushing control unit 102 (see Figure 5). In this embodiment, for each nozzle row, ink is first ejected N times from the odd-numbered nozzles 55, and then N times from the even-numbered nozzles 55. Note that the odd-numbered nozzles 55 and even-numbered nozzles 55 refer to the odd-numbered nozzles (1st, 3rd, 5th, etc.) and even-numbered nozzles (2nd, 4th, 6th, etc.) of the multiple nozzles 55 (see also Figure 2) arranged in the sub-scanning direction X, starting from the rear and moving towards the front.

[0053] Figure 8A shows the state in which the nozzle row 55D of the ink head 50 has reached a predetermined position P1 in the main scanning direction Y. The predetermined position P1 is the position where the flushing of the nozzle row 55D begins. Although not limited to this, the predetermined position P1 is located slightly to the left of the left end of the ink receiving member 41. The movement control unit 101 (see Figure 5) moves the carriage 8 (see Figure 2) in the Y2 direction, causing the ink head 50 to reach the predetermined position P1 in the main scanning direction Y. As mentioned above, the scan speed at this time is Vmax [mm / s]. At this time, the flushing control unit 102 (see Figure 5) supplies a drive waveform with a drive frequency fmax [Hz] to the piezoelectric element 64 (see Figure 3). As a result, N [times] of ink is ejected from the odd-numbered nozzles 55 of the nozzle row 55D (i.e., the number of ejections is N [times]). The flushing control unit 102 ejects ink N times from the odd-numbered nozzles 55 of the nozzle row 55D over a period of N times / fmax Hz. The ejected ink lands in a predetermined area of ​​the ink receiving member 41.

[0054] Figure 8B is a schematic diagram of the area around the ink head 50 after N [times] of ink has been ejected from the state shown in Figure 8A. An ink impact area D1 is formed on the ink receiving member 41 by the ink ejected from the odd-numbered nozzles 55 of the nozzle row 55D. If the width of the ink impact area D1 in the main scanning direction Y is denoted as width Wa [mm], then width Wa [mm] is the distance the ink head 50 moves in the Y2 direction by the movement control unit 101 from the time the flashing control unit 102 starts flashing from the nozzles 55 of the nozzle row 55D at a drive frequency fmax [Hz] until the number of inks determined by the number of ejections determination unit 103 (see Figure 5) has finished ejecting. Therefore, width Wa [mm] is calculated using the scan speed Vmax [mm / s], the number of ejections N [times], and the drive frequency fmax [Hz] by the following equation (5). Wa[mm]=Vmax[mm / s]×N[times] / fmax[Hz] ···(5)

[0055] Here, the width Wa is equal to the width Ld between each of the four nozzle rows 55A to 55D. Therefore, as the ink head 50 moves in the Y2 direction and N [times] of ink is ejected from the nozzle 55 of nozzle row 55D, nozzle row 55C reaches position P1, as shown in Figure 8B.

[0056] From the state shown in Figure 8B, the movement control unit 101 moves the ink head 50 in the Y2 direction while maintaining the scan speed at Vmax [mm / s]. At this time, the flushing control unit 102 ejects ink N times from the even-numbered nozzles 55 of nozzle row 55D, and ejects ink N times from the odd-numbered nozzles 55 of nozzle row 55C. At this time, the flushing control unit 102 ejects ink N times from the odd-numbered nozzles 55 of nozzle row 55D over a period of N times / fmax [Hz]. The ejected ink lands in a predetermined area of ​​the ink receiving member 41.

[0057] Figure 8C is a front view of the area around the ink head 50 after an additional N [times] of ink has been ejected from the state shown in Figure 8B. Ink ejected from the even-numbered nozzles 55 of nozzle row 55D forms an ink impact area D2 on the ink receiving member 41. Ink impact area D2 is formed to the right of ink impact area D1. Ink ejected from the odd-numbered nozzles 55 of nozzle row 55C forms an ink impact area C1 above ink impact area D1. At this time, nozzle row 55C has moved by a width Wa (i.e., width Ld) in the Y2 direction from position P1. At this time, nozzle row 55B has reached position P1. For the sake of explanation, ink impact area C1 is formed above ink impact area D1, but the ink forming ink impact area D1 and the ink forming ink impact area C1 may be mixed together.

[0058] Subsequently, the flushing control unit 102 (see Figure 5) performs flushing in the following order: even-numbered nozzles 55 of nozzle row 55C and odd-numbered nozzles 55 of nozzle row 55B, even-numbered nozzles 55 of nozzle row 55B and odd-numbered nozzles 55 of nozzle row 55A, and even-numbered nozzles 55 of nozzle row 55A. Figure 8D is a front view of the area around the ink head 50 when N [times] of ink has been ejected from all nozzle rows. The even-numbered nozzles 55 of nozzle row 55C form the ink impact area C2. The odd-numbered nozzles 55 and even-numbered nozzles 55 of nozzle row 55B form the ink impact areas B1 and B2, respectively. The odd-numbered nozzles 55 and even-numbered nozzles 55 of nozzle row 55A form the ink impact areas A1 and A2, respectively. At this time, the ink impact areas D1, C1, B1, and A1 are formed on the ink receiving member 41 in the following order from bottom to top. Furthermore, ink impact areas D2, C2, B2, and A2 are formed on the ink receiving member 41 in order from bottom to top. Ink impact areas D2, C2, B2, and A2 are formed to the right of ink impact areas D1, C1, B1, and A1. Therefore, the width of the area where ink is ejected on the ink receiving member 41 in the main scanning direction Y is 2 × Wa [mm]. Ink impact areas D1, D2, C1, C2, B1, B2, A1, and A2 are each examples of the first ink impact areas in the present invention. For the sake of explanation, the ink impact areas are shown separately, but the ink forming each ink impact area may be mixed together and arranged above the ink receiving member 41.

[0059] Next, we will explain the flushing in the standard printing mode. The scan speed in the standard printing mode is denoted as scan speed Va [mm / s]. Scan speed Va [mm / s] is an example of the second speed in this invention. The scan speed Va [mm / s] in the standard printing mode is slower than the scan speed Vmax [mm / s] in the high-speed printing mode. Therefore, if ink is ejected from nozzle rows 55A to 55D at the same timing as the flushing in the high-speed printing mode, the nozzles 55 on the left side of the nozzle row (nozzle rows 55A to 55C, excluding the rightmost nozzle row 55D) will eject ink at a position further to the left (in the Y1 direction). As a result, there is a risk that the ink receiving member 41 will not be able to receive the ink (see also Figure 7).

[0060] Therefore, in this embodiment, when performing flushing in standard printing mode, the number of flushes is increased compared to flushing in high-speed printing mode. By increasing the number of flushes, the start of ink ejection from the left nozzle row can be delayed by the number of increased flushes. Incidentally, the faster the scan speed, the larger the ink impact area. In this embodiment, the number of flushes at the scan speed Vmax [mm / s] of high-speed printing mode, which is the fastest scan speed, is used as a reference, and the number of flushes at the scan speed Va [mm / s] of standard printing mode is set accordingly. If the size of the ink receiving member 41 is designed to accommodate the ink impact area at scan speed Vmax [mm / s], then the ink impact area at scan speed Va [mm / s] will also inevitably be accommodated by the ink receiving member 41. The number of flushes is determined by the number determination unit 103 (see Figure 5). Let the number of flushes in standard printing mode be Na [times] (Na>N). The number of flushes Na [times] is an example of the second number in this invention.

[0061] In standard printing mode flushing, first, similar to high-speed printing mode flushing, the flushing control unit 102 (see Figure 5) supplies a drive waveform with a drive frequency fmax [Hz] to the piezoelectric element 64 (see Figure 3). Figure 9 is a diagram equivalent to Figure 8B in the case of standard printing mode. In Figure 9, an ink impact area D11 is formed in the ink receiving member 41. Similar to the ink impact area D1 (see Figure 8B), the ink impact area D11 is formed by ink ejected from the odd-numbered nozzles 55 of the nozzle row 55D. As shown in Figure 9, the length of the ink impact area D11 in the main scanning direction Y is the width Wb [mm]. The width Wb [mm] is calculated using the scan speed Va [mm], the number of shots Na [times], and the drive frequency fmax [Hz], similar to the width Wa [mm], by the following equation (6). Wb[mm]=Va[mm / s]×Na[times] / fmax[Hz] ···(6)

[0062] Here, by making the width Wa [mm] of the ink impact area D1 (see Figure 8B) the same as the width Wb [mm] of the ink impact area D11, it is possible to suppress the ejection of ink from the nozzles in the leftmost nozzle row at a position further to the left (in the Y1 direction). Therefore, equations (5) and (6) must be equal. When equations (5) and (6) are equal, the number of shots Na [times] is expressed by the following equation (7). Na[times] = Vmax[mm / s] / Va[mm / s] × N[times] ... (7)

[0063] Therefore, the number of shots determination unit 103 (see Figure 5) determines the number of shots to Na [times] in the standard printing mode where the scan speed is Va [mm / s]. The number of shots determination unit 103 determines the number of shots Na [times], for example, before the pass is executed. The scan speed Vmax [mm / s], Va [mm / s], and number of shots N [times] are assumed to be stored in the control device 100. In the standard printing mode, the flushing control unit 102 (see Figure 5) performs flushing by ejecting ink only the number of shots Na [times] determined by the number of shots determination unit 103. Similarly, by increasing the number of shots from the nozzles 55 of nozzle rows 55C, 55B, and 55A, the width of the ink impact area is made to match in the standard printing mode and the high-speed printing mode. Figure 10 is a diagram equivalent to Figure 8D in the case of the standard printing mode. In Figure 10, the ink receiving member 41 has ink impact areas D11, D22, C11, C22, B11, B22, A11, and A22 formed therein. The even-numbered nozzles 55 of nozzle row 55D form the ink impact area D22. The odd-numbered nozzles 55 and even-numbered nozzles 55 of nozzle row 55C form the ink impact areas C11 and C22, respectively. The odd-numbered nozzles 55 and even-numbered nozzles 55 of nozzle row 55B form the ink impact areas B11 and B22, respectively. The odd-numbered nozzles 55 and even-numbered nozzles 55 of nozzle row 55A form the ink impact areas A11 and A22, respectively. The ink impact areas D11, D22, C11, C22, B11, B22, A11, and A22 are each examples of the second ink impact areas in the present invention. In this case, even if the scan speed Va [mm / s] in standard printing mode is slower than the scan speed Vmax [mm / s] in high-speed printing mode, the ink ejected from all nozzles 55A to 55D during flushing can be received by the ink receiving member 41.

[0064] The scan speed in high-quality print mode is even slower than the scan speed Va [mm / s] in standard print mode. In high-quality print mode, the number of flashes is increased for the nozzles 55 in the left nozzle row compared to the standard print mode. As a result, even in high-quality print mode, the ink ejected from the nozzles 55 in all nozzle rows 55A to 55D can be received by the ink receiving member 41.

[0065] The above describes the flushing operation. Next, we will explain the various effects that can be obtained by this embodiment.

[0066] According to the printer 1 of this embodiment, the ink head 50 has nozzle rows 55A to 55D (see Figure 2). For example, nozzle row 55D is located to the right of nozzle row 55C, and nozzle rows 55D and 55C are examples of the "first nozzle row" and "second nozzle row," respectively. The control device 100 is configured to perform flushing in high-speed printing mode and flushing in standard printing mode. In high-speed printing mode, while moving the ink head 50 in the Y2 direction at a scan speed Vmax [mm / s], flushing is performed from the odd-numbered nozzles 55 of nozzle row 55D for a number of shots N [times]. After that, flushing is performed from the even-numbered nozzles 55 of nozzle row 55D and the odd-numbered nozzles 55 of nozzle row 55C for a number of shots N [times]. On the other hand, in standard printing mode, while moving the ink head 50 in the Y2 direction at a scan speed Va [mm / s], flushing is performed with Na [times] from the odd-numbered nozzles 55 of nozzle row 55D. Subsequently, flushing is performed with Na [times] from the even-numbered nozzles 55 of nozzle row 55D and the odd-numbered nozzles 55 of nozzle row 55C. Na [times] is a number greater than N [times]. The number determination unit 103 determines the number Na [times] in standard printing mode based on the scan speed Vmax in high-speed printing mode.

[0067] In the printer 1 of this embodiment, the print count determination unit 103 determines the number of flashes Na [times] in the standard printing mode from the scan speed Vmax [mm / s] in the high-speed printing mode, the number of flashes N [times] in the high-speed printing mode, and the scan speed Va [mm / s] in the standard printing mode. That is, the number of flashes Na [times] in the standard printing mode is changed based on the scan speed (movement speed of the ink head 50) in the high-speed printing mode. The flashing control unit 102 performs flashing on the ink receiving member 41 with the number of flashes Na [times] determined by the print count determination unit 103. In this embodiment, since the number of flashes Na [times] in the standard printing mode is greater than the number of flashes N [times] in the high-speed printing mode, the timing of ink ejection from the nozzles 55 of nozzle rows 55A to 55C in the standard printing mode is later than in the high-speed printing mode. This makes it possible to suppress the position of the left edge of the ink landing area from shifting to the left in the standard printing mode. If the number of prints is the same in high-speed printing mode and standard printing mode, the width of the ink receiving member 41 (dimension in the main scanning direction Y) needs to be extended by a width W3 (see Figure 7 and Equation (7)) or more. However, according to this embodiment, it is possible to suppress ink ejected from the nozzle 55 from spilling out of the ink receiving member 41 without extending the width of the ink receiving member 41. Therefore, the ink receiving member 41 can be made smaller.

[0068] In this embodiment, the case where ink spills out of the ink receiving member 41 is assumed to be based on the high-speed printing mode, which has the fastest scan speed. However, when flushing is performed at a scan speed faster than a certain scan speed, the ink is ejected at a position further to the right (in the Y2 direction) by the nozzle 55 of the left nozzle row. Therefore, the ink impact area formed by the left nozzle row is shifted to the right compared to the case of the reference scan speed. In such a case, the number of flashes determination unit 103 may determine the number of flashes to be reduced compared to the number of flashes at the reference scan speed.

[0069] In the printer 1 of this embodiment, the print count determination unit 103, controlled by the movement control unit 101, increases the print count when the scan speed (the movement speed of the ink head 50) is slow, and decreases the print count when the scan speed is fast. Therefore, the print count can be determined relatively easily.

[0070] In the printer 1 of this embodiment, the print count determination unit 103 determines the print count Na based on equation (7). Equation (7) determines the print count Na based on the maximum scan speed Vmax [mm / s]. In equation (7), when Va [mm / s] is less than Vmax [mm / s], the print count Na is greater than the print count N. In equation (7), when Va [mm / s] is the same as Vmax [mm / s], the print count Na is the same as the print count N. Therefore, according to equation (7), the print count Na can be greater than or equal to the print count N. Here, if the scan speed is slower than the scan speed Vmax [mm / s], and flushing is performed with a print count smaller than the print count N, the time between flushing the nozzle rows 55A to 55D and ejecting the next ink becomes relatively long. Therefore, the ink near the nozzles 55 may dry out, potentially causing the ink to become thicker. However, as in this embodiment, by setting the number of shots Na [times] to N [times] or more, based on the maximum scan speed Vmax [mm / s], ink drying can be suppressed. Furthermore, if the size of the ink receiving member 41 is designed to accommodate the ink impact area at the scan speed Vmax [mm / s], the ink impact area at the scan speed Va [mm / s] can also be accommodated within the ink receiving member 41.

[0071] In the printer 1 of this embodiment, ink impact areas D1, D2, C1, C2, B1, B2, A1, A2 (first impact areas) are formed on the ink receiving member 41 by flashing during high-speed printing mode (scan speed Vmax [mm / s]) (see Figure 8D). In addition, ink impact areas D11, D22, C11, C22, B11, B22, A11, A22 (second ink impact areas) are formed by flashing during standard printing mode (scan speed Va [mm / s]) (see Figure 10). The width Wa [mm] of the first impact area is equal to the width Wb [mm] of the second ink impact area. Therefore, even if the number of flashes is increased in standard printing mode compared to high-speed printing mode, the ink can be suitably received without increasing the size of the ink receiving member 41.

[0072] In the printer 1 of this embodiment, the flushing control unit 102 performs flushing when each of the nozzle rows 55A to 55D reaches a predetermined position P1, as controlled by the movement control unit 101. That is, each nozzle row starts flushing at the same position. As a result, the left end positions of the ink impact areas A1, B1, C1, and D1 formed on the ink receiving member 41 are aligned. Therefore, the ink receiving member 41 can receive ink effectively without increasing its size. However, the positions at which each nozzle row starts flushing do not have to be the same. It is sufficient that the flushing start position is the same for each nozzle row across modes with different scan speeds. For example, if in high-speed printing mode, nozzle row 55D starts flushing at a first predetermined position and nozzle row 55C starts flushing at a second predetermined position, then in standard printing mode, nozzle row 55D also starts flushing at the first predetermined position and nozzle row 55C starts flushing at the second predetermined position. The same applies to the other nozzle rows. The first predetermined position and the second predetermined position may be the same or different.

[0073] According to this embodiment, as shown in Figure 1, the cleaning unit 40 is positioned to the right of the platen 4, which is an example of a mounting platform on which the recording medium 5 is placed. As shown in Figure 4, the caps 48a to 48d of the capping unit 48 of the cleaning unit 40 are positioned to the right of the ink receiving member 41 of the flushing unit 42. Therefore, the ink receiving member 41 is positioned between the platen 4 and the caps 48a to 48d. The ink receiving member 41 is positioned relatively close to the platen 4. Thus, when flushing is performed during printing, the distance the ink head 50 moves can be made relatively short.

[0074] Although one embodiment of the present invention has been described above, this embodiment is merely an example, and various other embodiments are possible. Next, we will briefly describe some examples of other embodiments.

[0075] In the embodiment described above, a wiping unit 46 is positioned to the right of the flushing unit 42, and the ink head 50 discharges ink to the ink receiving member 41 while moving to the right. However, the direction of movement of the ink head 50 when flushing is performed is not limited to the right. For example, the ink head 50 may discharge ink to the ink receiving member 41 while moving to the left.

[0076] In the embodiment described above, the ink head 50 performs flushing while moving to the right at a constant speed. However, during printing, the ink head 50 repeatedly moves back and forth in the main scanning direction Y. The ink head 50 changes direction of travel to the right of the platen 4. To the right of the platen 4, the ink head 50 moves to the right while decelerating, stops briefly, and then moves to the left while accelerating. Therefore, when the ink head 50 ejects ink to the ink receiving member 41 while moving to the right, the ink head 50 may decelerate directly above the ink receiving member 41. Also, when the ink head 50 ejects ink to the ink receiving member 41 while moving to the left, the ink head 50 may accelerate directly above the ink receiving member 41. This allows the space directly above the ink receiving member 41 to be used as space for the ink head 50 to decelerate or accelerate. Thus, a large space can be secured for deceleration or acceleration, preventing sudden deceleration or acceleration of the ink head 50.

[0077] Incidentally, the movement speed of the ink head 50 is not constant during deceleration or acceleration. The ink head 50 may decelerate or accelerate at the flashing position. The flashing position is the position where, when viewed from above, at least a part of the ink head 50 overlaps with the ink receiving member 41. When the ink head 50 decelerates or accelerates at the flashing position, the print count determination unit 103 may determine the print count based on the acceleration of the ink head, instead of the scan speed (i.e., a constant speed) as in the above embodiment. For example, if the scan speed at the start of acceleration / deceleration of the ink head 50 is V0 [mm / s] and the acceleration is a [mm / s] 2 If the elapsed time from the start of acceleration / deceleration is T [sec], the scan speed V [mm / s] after T [sec] has elapsed from the start of acceleration / deceleration is expressed by the following equation (8). V[mm / s] = V0[mm / s] + a[mm / s] 2 ]×T[sec] ···(8) Scan speed V0 [mm / s], acceleration a [mm / s] 2] may be predetermined by the control device 100, for example. Also, the elapsed time T at the flushing position may be estimated in advance by the control device 100. By substituting V [mm / s] calculated by equation (8) into Va [mm / s] in equation (7), the number of shots when the ink head 50 decelerates or accelerates can be determined.

[0078] Furthermore, when the ink head 50 decelerates or accelerates, the moving speed of the ink head 50 may be the average speed at which the ink head 50 passes the flashing position. Thus, the "predetermined speed" of the present invention is not necessarily limited to a constant speed, but may be a speed that decelerates or accelerates.

[0079] In the embodiment described above, the flushing unit 42 is located to the right of the platen 4, but the flushing unit 42 may also be located to the left of the platen 4. In this case, the ink head 50 may perform flushing while moving to the left, or while moving to the right. Furthermore, the flushing unit 42 may be located on both the right and left sides of the platen 4. In this case, the ink head 50 may perform flushing on both the right and left sides of the platen 4.

[0080] In the embodiment described above, during flushing, ink is first ejected from the odd-numbered nozzles 55 in each nozzle row 55A to 55D, and then from the even-numbered nozzles 55. However, the manner in which ink is ejected in each nozzle row 55A to 55D is not particularly limited. For example, ink may be ejected first from the even-numbered nozzles 55, and then from the odd-numbered nozzles 55. Also, when each nozzle row ejects ink in two stages, it is not necessarily limited to the division into odd-numbered and even-numbered nozzles. Furthermore, a nozzle row may eject ink in three or more stages during flushing, or it may eject ink in a single stage.

[0081] In the embodiments described above, the widths Wa and Wb of the ink impact areas D1 and D11 were equal to the width Ld between each of the four nozzle rows 55A to 55D, but this is not limited to this. The widths Wa and Wb of the ink impact areas D1 and D11 may be greater than or less than the width Ld between the nozzle rows. The same applies to ink impact areas other than D1 and D11 (for example, ink impact areas C1, C11, etc.).

[0082] In the embodiment described above, nozzle rows 55D, 55C, 55B, and 55A sequentially performed flushing toward the ink receiving member 41, but the embodiment is not limited to this. For example, flushing may be performed simultaneously from nozzle rows 55D and 55B, and then simultaneously from nozzle rows 55C and 55A.

[0083] In the embodiment described above, flushing was performed from nozzle row 55D followed immediately by flushing from nozzle row 55C, but this is not limited to this. Flushing from nozzle row 55C may be started while flushing from nozzle row 55D is in progress. For example, flushing from nozzle row 55C may be started when a predetermined percentage of the number of flushes from nozzle row 55D has been completed. For example, in high-speed printing mode, flushing from nozzle row 55C may be started when N / 2 [times] of the number of flushes N [times] from nozzle row 55D has been completed, and in standard printing mode, flushing from nozzle row 55C may be started when Na / 2 [times] of the number of flushes Na [times] from nozzle row 55D has been completed. The predetermined percentage only needs to be the same between modes with different scan speeds, and the predetermined percentage may be 1 / 3, 1 / 4, 2 / 3, etc. Furthermore, in the embodiments described above, the ink impact areas D2, C2, B2, and A2 are formed to the right of the ink impact areas D1, C1, B1, and A1 so as not to overlap with them, but the invention is not limited to this. Parts of the ink impact areas D2, C2, B2, and A2 may be formed to partially or entirely overlap with the ink impact areas D1, C1, B1, and A1.

[0084] In the embodiment described above, the first to fourth ink heads 51 to 54 of the ink head 50 are each positioned in alignment with the sub-scanning direction X. However, the arrangement of the ink heads 50 is not limited to this. For example, at least one of the first to fourth ink heads 51 to 54 may be positioned offset from the other ink heads in the sub-scanning direction X.

[0085] The number of nozzle rows in the first to fourth ink heads 51 to 54 is not limited to one row. There may be two or more nozzle rows for each ink head. In the above-described embodiment, four separate ink heads 51 to 54 constitute the ink head 50, but the number of separate ink heads in the ink head 50 is not limited to four, but may be one, two, three, or five or more.

[0086] In the embodiment described above, since the spacing between each nozzle row is a common width Ld, when ink is ejected from a certain nozzle row with a number of shots Na [times], the left nozzle row reaches position P1. However, the spacing between each nozzle row does not have to be common. For example, suppose the spacing between nozzle row 55D and nozzle row 55C in the main scanning direction Y is a width Ld + α [mm] (α > 0). In this case, when ink is ejected from an odd-numbered nozzle 55 of nozzle row 55D with a number of shots Na [times], nozzle row 55C does not reach position P1. Therefore, it is necessary to increase the number of shots by an additional amount equal to a width α [mm]. When the scan speed is Va [mm / s], the time it takes for the ink head 50 to move a width α in the Y2 direction is α [mm] / Va [mm / s]. Therefore, when the drive waveform is supplied at a drive frequency fmax [Hz] as in the embodiment described above, the number of shots when the ink head 50 moves a width α in the Y2 direction is fmax [Hz] × α [mm] / Va [mm / s]. Therefore, if the distance between nozzle row 55D and nozzle row 55C in the main scanning direction Y is width Ld + α [mm], the number of shots in nozzle row 55D can be determined by adding fmax [Hz] × α [mm] / Va [mm / s] to the number of shots Na [times] in equation (7). The same applies to the distances between nozzle rows other than nozzle row 55D and nozzle row 55C. Although the case α > 0 has been explained here, the same applies to the case α < 0. Thus, the shot count determination unit 103 may determine the shot count for each nozzle row separately.

[0087] The technology disclosed herein can be applied to various types of printers. In addition to the roll-to-roll type printers shown in the embodiments described above, it can also be applied to so-called flatbed type printers, for example, in which the media is fixed on a table and the table is transported for printing. Furthermore, it can also be applied to so-called gantry type printers, in which the media is placed on a table and the carriage is moved relative to the table in the main scanning direction Y and the sub-scanning direction X for printing. [Explanation of symbols]

[0088] 1. Printer (inkjet printer) 20. Head movement mechanism (movement mechanism) 41 Ink receiving member 50 Inkheads 51-54 1st-4th ink heads 55 nozzles 55A~55D Nozzle Row 100 Control device 101 Movement Control Unit 102 Flushing Control Unit 103 Number of shots determination unit

Claims

1. An ink head has multiple nozzles that eject ink, arranged in a first direction, A moving mechanism for moving the ink head in a second direction intersecting the first direction, An ink receiving member that receives the ink ejected from the ink head, The system includes a control device for controlling the ink head and the moving mechanism, The ink head is formed with a first nozzle row in which a plurality of nozzles are arranged in the first direction, and a second nozzle row in which a plurality of nozzles are arranged in the first direction and positioned offset from the first nozzle row in the second direction. The control device is A movement control unit that moves the ink head at a predetermined speed using the aforementioned movement mechanism, A flushing control unit that performs flushing from the first nozzle row or the second nozzle row of the ink head, which is moved by the movement control unit, toward the ink receiving member, The flushing control unit comprises a number determination unit that determines the number of ink droplets to be ejected from the nozzle during the flushing process, When the ink head is being moved at a first speed by the movement control unit, the flushing control unit performs the flushing from at least some of the nozzles of the first nozzle row toward the ink receiving member with a first number of shots determined by the shot count determination unit, and after starting the flushing from at least some of the nozzles of the first nozzle row toward the ink receiving member, it performs the flushing from at least some of the nozzles of the second nozzle row toward the ink receiving member. When the ink head is being moved at a second speed by the movement control unit, the flushing is performed from at least some of the nozzles of the first nozzle row toward the ink receiving member at a second number of shots determined by the shot count determination unit, and after the flushing has started from at least some of the nozzles of the first nozzle row toward the ink receiving member, the flushing is performed from at least some of the nozzles of the second nozzle row toward the ink receiving member. The second speed is smaller than the first speed. An inkjet printer in which the second number of prints is greater than the first number of prints.

2. The inkjet printer according to claim 1, wherein the number of prints determination unit determines the number of prints based on the speed or acceleration of the ink head moved by the movement control unit.

3. The inkjet printer according to claim 2, wherein the first speed is the maximum speed Vmax when the ink head moves, the first number of prints is the number of prints N when the ink head moves at the speed Vmax, and the second speed is a speed Va smaller than the speed Vmax, the print count determination unit determines the second number of prints as Vmax / Va × N.

4. The ink receiving member is formed with a first ink impact area where the ink from the flushing occurs when the ink head is moving at a first speed, and a second ink impact area where the ink from the flushing occurs when the ink head is moving at a second speed. The inkjet printer according to claim 1, wherein the flushing control unit performs the flushing such that the length of the first ink impact area in the second direction is equal to the length of the second ink impact area in the second direction.

5. The inkjet printer according to claim 1, wherein the flushing control unit starts flushing from at least some of the nozzles of the first nozzle row when the first nozzle row reaches a predetermined position, and starts flushing from at least some of the nozzles of the second nozzle row toward the ink receiving member when the second nozzle row reaches the predetermined position in the second direction.

6. A mounting platform on which the recording medium is placed, The system comprises a cap positioned in one or the other direction relative to the mounting base, which covers the nozzle of the ink head, The ink receiving member is disposed between the stand described above and the cap, as described above, in the inkjet printer according to claim 1.

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