Liquid discharging device, control method for same, and program

Abstract

The present invention achieves both a decrease in the time required for liquid supply to a nozzle and reduction of the amount of waste liquid.　A CPU of a printer firstly drives a pump 51 in a state in which a valve 81 is in an open position and valves 82-84 are in a closed position, thereby generating a suction force in a cap 50 and supplying black ink to a flow channel 120K from an ink tank 71 through a tube 61 (S1: first step). Thereafter, the CPU 91 drives the pump 51 in a state in which the valve 82 is in an open position and the valves 81, 83, 84 are in a closed position, thereby generating a suction force in the cap 50 and supplying yellow ink to a flow channel 120Y from an ink tank 72 through a tube 62 (S3: second step). The suction force generated in the cap 50 in S3 is weaker than the suction force generated in the cap 50 in S1.

Description

Liquid ejection device, control method thereof, and program

[0001] The present disclosure relates to a liquid ejection device that includes a head having a nozzle surface with nozzles opening therein and a cap that contacts the nozzle surface to cover the nozzles, and a control method and program for the same.

[0002] Japanese Patent Application Laid-Open No. 2006-103663 discloses an inkjet recording device including a recording head having a discharge port surface with a plurality of discharge ports, a recovery tub in close contact with the discharge port surface, a pump connected to the recovery tub, a plurality of ink tanks for storing ink of each color and connected to the discharge ports of each color via tubes, and a plurality of valves provided along each tube. When the pump is driven to create a negative pressure inside the recovery tub, ink flows out of the discharge ports of each color of the recording head, is temporarily stored in the recovery tub, and then is drawn into a waste ink tank. The ink in each ink tank is supplied to each recording head by passing through the tubes.

[0003] Japanese Patent Application Laid-Open No. 2006-082517

[0004] To supply liquid from each tank to the nozzles of the head, it is conceivable to operate a pump to generate suction force within the cap. In this case, if the pump is operated with all valves (first valve, second valve) in the open position, the suction force within the cap will be dispersed among multiple flow paths (first flow path, second flow path), lengthening the time required for liquid supply. Therefore, for each flow path, the pump is operated with one valve of the first and second valves corresponding to that flow path in the open position and the other valve in the closed position. This prevents the suction force within the cap from being dispersed among multiple flow paths, thereby shortening the time required for liquid supply.

[0005] However, if the same suction force is generated when the pump is driven for each flow path, a large amount of liquid will be wasted. Specifically, when liquid is supplied to the first flow path, negative pressure is generated between the second valve, which corresponds to the second flow path and is in the closed position, and the second nozzle. When the second valve is then switched from the closed position to the open position while liquid is being supplied to the second flow path, the negative pressure is released and the liquid in the second tank moves toward the second nozzle. When the pump is then driven and the same suction force as when liquid was supplied to the first flow path is generated, the same amount of ink as when liquid was supplied to the first flow path moves toward the second nozzle, and the liquid that moved becomes waste when the negative pressure is released.

[0006] An object of the present disclosure is to provide a liquid ejection apparatus that can achieve both a reduction in the time required to supply liquid to nozzles and a reduction in the amount of waste liquid, as well as a control method and program for the same.

[0007] A liquid ejection device according to the present disclosure includes a head having a nozzle surface in which first and second nozzles are opened, a cap that contacts the nozzle surface and covers the first and second nozzles, a pump connected to the cap, a first tank that stores a first liquid and communicates with the first nozzle via a first flow path, a second tank that stores a second liquid and communicates with the second nozzle via a second flow path, a first valve that can selectively take an open position that opens the first flow path and a closed position that closes the first flow path, a second valve that can selectively take an open position that opens the second flow path and a closed position that closes the second flow path, and a control unit. the control unit executes a first step of generating a first suction force in the cap by driving the pump with the first valve in an open position and the second valve in a closed position, and supplying the first liquid from the first tank to the first nozzle via the first flow path; and a second step of generating a second suction force weaker than the first suction force in the cap by driving the pump with the first valve in a closed position and the second valve in an open position, and supplying the second liquid from the second tank to the second nozzle via the second flow path, after the first step.

[0008] A control method according to the present disclosure provides a liquid ejection device including: a head having a nozzle surface in which first nozzles and second nozzles are opened; a cap that contacts the nozzle surface and covers the first nozzles and the second nozzles; a pump connected to the cap; a first tank that stores a first liquid and communicates with the first nozzles via a first flow path; a second tank that stores a second liquid and communicates with the second nozzles via a second flow path; a first valve that can selectively take an open position that opens the first flow path and a closed position that closes the first flow path; and a second valve that can selectively take an open position that opens the second flow path and a closed position that closes the second flow path. a control method for controlling a liquid supplying device, the control method comprising: a first step of generating a first suction force in the cap by driving the pump with the first valve in an open position and the second valve in a closed position, and supplying the first liquid from the first tank to the first nozzle via the first flow path; and a second step of generating a second suction force weaker than the first suction force in the cap by driving the pump with the first valve in a closed position and the second valve in an open position, and supplying the second liquid from the second tank to the second nozzle via the second flow path, after the first step.

[0009] The program according to the present disclosure is used in a liquid ejection device including: a head having a nozzle surface in which first nozzles and second nozzles are opened; a cap that contacts the nozzle surface and covers the first nozzles and the second nozzles; a pump connected to the cap; a first tank that stores a first liquid and communicates with the first nozzles via a first flow path; a second tank that stores a second liquid and communicates with the second nozzles via a second flow path; a first valve that can selectively take an open position that opens the first flow path and a closed position that closes the first flow path; and a second valve that can selectively take an open position that opens the second flow path and a closed position that closes the second flow path. a control unit configured to operate the pump with the first valve in an open position and the second valve in a closed position, thereby generating a first suction force within the cap and supplying the first liquid from the first tank to the first nozzle via the first flow path; and a second step of, after the first step, generating a second suction force weaker than the first suction force within the cap and supplying the second liquid from the second tank to the second nozzle via the second flow path by operating the pump with the first valve in a closed position and the second valve in an open position.

[0010] By supplying liquid to each flow path in the first and second steps, the suction force in the cap is not dispersed among multiple flow paths, thereby shortening the time required for liquid supply. Furthermore, rather than generating the same suction force in the first and second steps, a smaller suction force is generated in the second step than in the first step. This reduces the amount of waste liquid even if the liquid corresponding to the negative pressure generated in the first step moves toward the second nozzle. In other words, according to the present disclosure, it is possible to shorten the time required for liquid supply to the nozzle and reduce the amount of waste liquid.

[0011] 4 is a plan view showing the overall configuration of a printer according to a first embodiment of the present disclosure; FIG. 5 is a partial cross-sectional view of the head shown in FIG. 1; FIG. 6 is a block diagram showing the electrical configuration of the printer of FIG. 1; FIG. 7 is a flow diagram showing a program executed by the CPU of the printer of FIG. 1; (a) is a schematic diagram showing step S1 of FIG. 4; (b) is a schematic diagram showing step S2 of FIG. 4; (c) is a schematic diagram showing step S3 of FIG. 4; (a) is a schematic diagram showing step S4 of FIG. 4; (b) is a schematic diagram showing step S5 of FIG. 4; (c) is a schematic diagram showing step S6 of FIG. 4; and (d) is a schematic diagram showing step S7 of FIG. 4; FIG. 7 is a flow diagram showing another program executed by the CPU of the printer according to the present disclosure; (a) is a schematic diagram showing step S1 of FIG. 7; (b) is a schematic diagram showing step S31 of FIG. 7; and (c) is a schematic diagram showing step S2 of FIG. 7.

[0012] 1 is an embodiment of a liquid ejection device according to the present disclosure. The printer 100 includes a housing 40, a head 10, a carriage 19 that holds the head 10, a scanning mechanism 20 that moves the carriage 19 and the head 10 in a scanning direction (a direction perpendicular to the vertical direction), a platen 30, a cap 50, a pump 51, a waste liquid tank 52, ink tanks 71 to 74, and a control device 90.

[0013] The head 10 , carriage 19 , scanning mechanism 20 , ink tanks 71 to 74 and control device 90 are housed inside a housing 40 .

[0014] The platen 30 is transported in a transport direction (a direction perpendicular to the scanning direction and the vertical direction) by driving a transport motor 30M shown in FIG. 3 , from the outside upstream in the transport direction relative to the housing 40, through the inside of the housing 40, and to the outside downstream in the transport direction relative to the housing 40. Inside the housing 40, the platen 30 passes below the head 10. The platen 30 is a rectangular plate member arranged in a direction perpendicular to the vertical direction, and a print medium is supported on its upper surface. The print medium is fabric (for example, a T-shirt containing polyester fiber).

[0015] The head 10 has a plurality of nozzles 15. The plurality of nozzles 15 constitute four nozzle rows 15K, 15Y, 15C, and 15M. Each of the four nozzle rows 15K, 15Y, 15C, and 15M is made up of a plurality of nozzles 15 lined up in the transport direction. The nozzles 15 constituting nozzle row 15K eject black ink, the nozzles 15 constituting nozzle row 15Y eject yellow ink, the nozzles 15 constituting nozzle row 15C eject cyan ink, and the nozzles 15 constituting nozzle row 15M eject magenta ink.

[0016] Although not shown, the printer 100 further includes a head that has a similar structure to the head 10 and ejects white ink from its nozzles. The white ink is used in printing to represent the white color of an image or as a base for color inks. The color inks are ejected onto the white ink base and are used to print color images.

[0017] As shown in FIG. 2, the head 10 includes a flow path member 12 and an actuator member 13 .

[0018] The flow path member 12 has flow paths 120 (120K, 120Y, 120C, 120M) for each of the colors black, yellow, cyan, and magenta formed therein. Each flow path 120 includes a common flow path 121 that communicates with the corresponding ink tanks 71 to 74 (see FIG. 1 ), and an individual flow path 122 that is separate for each nozzle 15. The individual flow path 122 is a flow path that runs from the outlet of the common flow path 121 through a pressure chamber 123 to the nozzle 15. A plurality of pressure chambers 123 open into the upper surface of the flow path member 12. A plurality of nozzles 15 (see FIG. 1 ) open into a lower surface 12X of the flow path member 12. The lower surface 12X corresponds to the "nozzle surface" in this disclosure.

[0019] The actuator member 13 includes a metal vibration plate 131 arranged on the upper surface of the flow path member 12 so as to cover the multiple pressure chambers 123, a piezoelectric layer 132 arranged on the upper surface of the vibration plate 131, and multiple individual electrodes 133 arranged on the upper surface of the piezoelectric layer 132 in positions that vertically overlap each of the multiple pressure chambers 123.

[0020] The vibration plate 131 and the plurality of individual electrodes 133 are electrically connected to a driver IC 14. The driver IC 14 maintains the potential of the vibration plate 131 at ground potential, while varying the potential of the individual electrodes 133 between ground potential and a drive potential. This causes deformation of the portion of the vibration plate 131 and the piezoelectric layer 132 sandwiched between the individual electrode 133 and the pressure chamber 123 (actuator 13X), thereby changing the volume of the pressure chamber 123. When the volume of the pressure chamber 123 increases, ink is sucked from the common flow path 121 into the individual flow path 122, and ink is supplied to the common flow path 121 from the corresponding ink tanks 71 to 74 (see FIG. 1 ). When the volume of the pressure chamber 123 decreases, pressure is applied to the ink in the pressure chamber 123, causing ink to be ejected from the nozzle 15.

[0021] As shown in FIG. 1 , the ink tank 71 stores black ink and is connected via a tube 61 to a black flow path 120K including the nozzles 15 of the nozzle row 15K. The ink tank 72 stores yellow ink and is connected via a tube 62 to a yellow flow path 120Y including the nozzles 15 of the nozzle row 15Y. The ink tank 73 stores cyan ink and is connected via a tube 63 to a cyan flow path 120C including the nozzles 15 of the nozzle row 15C. The ink tank 74 stores magenta ink and is connected via a tube 64 to a magenta flow path 120M including the nozzles 15 of the nozzle row 15M. Each of the ink tanks 71 to 74 may have an opening (not shown) through which ink is supplied. Alternatively, the ink tanks 71 to 74 may be removable cartridges.

[0022] Each of the tubes 61 to 64 may be provided with a sub-tank (not shown). The four sub-tanks store black ink, yellow ink, cyan ink, and magenta ink, respectively. The capacity of each sub-tank is smaller than the capacity of each of the ink tanks 71 to 74.

[0023] A valve 81 is attached to the tube 61. A valve 82 is attached to the tube 62. A valve 83 is attached to the tube 63. A valve 84 is attached to the tube 64. Each of the valves 81 to 84 can be selectively placed in an open position that opens the flow path of the corresponding tube 61 to 64, or in a closed position that closes the flow path, under the control of the control device 90. Note that when each of the tubes 61 to 64 is provided with a sub-tank as described above, the valves 81 to 84 are disposed between the sub-tank in the tubes 61 to 64 and the head 10.

[0024] For example, black ink corresponds to the "first liquid" of the present disclosure, yellow ink corresponds to the "second liquid" of the present disclosure, and cyan ink corresponds to the "third liquid" of the present disclosure. In this case, ink tank 71 corresponds to the "first tank" of the present disclosure, ink tank 72 corresponds to the "second tank" of the present disclosure, and ink tank 73 corresponds to the "third tank" of the present disclosure. The flow path in tube 61 corresponds to the "first flow path" of the present disclosure, the flow path in tube 62 corresponds to the "second flow path" of the present disclosure, and the flow path in tube 63 corresponds to the "third flow path" of the present disclosure. Nozzles 15 of nozzle row 15K correspond to the "first nozzle" of the present disclosure, nozzles 15 of nozzle row 15Y correspond to the "second nozzle" of the present disclosure, and nozzles 15 of nozzle row 15C correspond to the "third nozzle" of the present disclosure. Valve 81 corresponds to the "first valve" in the present disclosure, valve 82 corresponds to the "second valve" in the present disclosure, and valve 83 corresponds to the "third valve" in the present disclosure.

[0025] 1, the scanning mechanism 20 includes a pair of guides 21 and 22 that support the carriage 19, and a belt 23 connected to the carriage 19. The guides 21 and 22 and the belt 23 extend in the scanning direction. When the scanning motor 20M (see FIG. 3) is driven under the control of the control device 90, the belt 23 runs, and the carriage 19 and head 10 move in the scanning direction along the guides 21 and 22.

[0026] The cap 50 is disposed on one side of the conveying region of the platen 30 in the scanning direction. The cap 50 is a box-shaped member with an open top and can be moved vertically by driving a cap lift motor 50M (see FIG. 3 ). When the head 10 is positioned above the cap 50, the cap lift motor 50M is driven under the control of the control device 90, and the cap 50 is moved upward, whereby the cap 50 contacts the lower surface 12X of the head 10, forming a sealed space between the cap 50 and the head 10. At this time, all of the nozzles 15 formed in the head 10 are covered by the cap 50. This state of the cap 50 is referred to as a capped state. On the other hand, a state in which the cap 50 is separated from the head 10 and does not cover the nozzles 15 (a state in which no sealed space is formed between the cap 50 and the head 10) is referred to as an uncapped state. The cap lift motor 50M may be omitted. For example, the cap 50 may be connected to the scanning motor 20M via a driving member such as a pinion, gear, or belt, and may be raised and lowered by the driving of the scanning motor 20M. Also, the cap 50 may be raised and lowered by contact with the carriage 19 or head 10 that is moved by the driving of the scanning motor 20M.

[0027] The pump 51 is connected to the cap 50 via a tube. The waste liquid tank 52 is connected to the pump 51 via a tube. The pump 51 is interposed between the cap 50 and the waste liquid tank 52. When the pump 51 is driven under the control of the control device 90 while the cap 50 is in the capping state, the sealed space between the cap 50 and the head 10 is depressurized, and ink is forcibly discharged from the nozzles 15. The discharged ink is received in the cap 50, passes through the tube and the pump 51, and is stored in the waste liquid tank 52.

[0028] The driving of the pump 51 as described above is executed during a purge operation, an initial introduction operation, etc. A purge operation is an operation for forcibly ejecting ink from the nozzles 15 to restore the ink ejection performance of the nozzles 15. An initial introduction operation is an operation for introducing ink from the ink tanks 71 to 74 into each flow path 120 of the head 10.

[0029] As shown in FIG. 3 , the control device 90 is electrically connected to the driver IC 14, the scanning motor 20M, the conveying motor 30M, the cap lifting motor 50M, and the pump 51, and is also communicatively connected to an external device (such as a personal computer) 150. The control device 90 includes a CPU 91, a ROM 92, and a RAM 93. The ROM 92 stores programs and data for the CPU 91 to perform various controls. The RAM 93 temporarily stores data (such as image data) used by the CPU 91 when executing the programs. The CPU 91 performs various controls based on data input from an input unit of the external device 150 or the printer 100 and data stored in the ROM 92 and RAM 93. The CPU 91 corresponds to the "control unit" in this disclosure.

[0030] 4, a program executed by the CPU 91 will be described. This program is started, for example, when the CPU 91 receives an initial installation instruction from an operation unit (not shown) provided in the printer 100 or from the external device 150 in a state where the CPU 91 receives a signal from a sensor (not shown) indicating that ink is present in the ink tanks 71 to 74, or a signal from a sensor (not shown) indicating that the ink tanks 71 to 74 have been installed in the printer 100.

[0031] At the start of the program, the flow paths 120K, 120Y, 120C, and 120M of the head 10 and the tubes 61 to 64 are not filled with ink. The head 10 is positioned above the cap 50 (see FIG. 1), and the cap 50 is in a capping state, with all of the nozzles 15 formed in the head 10 covered by the cap 50. The valves 81 to 84 are all in the open position.

[0032] The CPU 91 first switches the valves 82 to 84 from the open position to the closed position. Then, as shown in FIG. 5A, the pump 51 is driven with the valve 81 in the open position and the valves 82 to 84 in the closed position, thereby generating a suction force within the cap 50 and supplying black ink from the ink tank 71 to the flow path 120K (and thus to the nozzles 15 constituting the nozzle row 15K) via the tube 61 (S1: first step). At this time, negative pressure is generated in the flow paths 120Y, 120C, and 120M and in portions of the tubes 62 to 64 that are closer to the flow paths 120Y, 120C, and 120M than the valves 82 to 84.

[0033] 5B, the CPU 91 switches the valves 82 to 84 from the closed position to the open position while stopping the pump 51, thereby bringing all of the valves 81 to 84 into the open position (S2: third step). At this time, the release of the negative pressure causes a small amount of ink to move from the ink tanks 72 to 74 toward the head 10.

[0034] 5C, the CPU 91 switches the valves 81, 83, and 84 from the open position to the closed position, and operates the pump 51 with the valve 82 in the open position and the valves 81, 83, and 84 in the closed position, thereby generating a suction force within the cap 50 and supplying yellow ink from the ink tank 72 to the flow path 120Y (and thus to the nozzles 15 constituting the nozzle row 15Y) via the tube 62 (S3: second step). At this time, negative pressure is generated in the flow paths 120C and 120M and in portions of the tubes 63 and 64 that are closer to the flow paths 120C and 120M than the valves 83 and 84.

[0035] The suction force generated in the cap 50 in S3 is weaker than the suction force generated in the cap 50 in S1. For example, the CPU 91 may set the rotation speed of the pump 51 in S3 to be slower than the rotation speed of the pump 51 in S1. Alternatively, the CPU 91 may set the rotation amount of the pump 51 in S3 to be slower than the rotation amount of the pump 51 in S1. Alternatively, in a case where the pump 51 includes a first pump and a second pump having a weaker suction force than the first pump, the CPU 91 may drive the first pump in S1 and drive the second pump in S3.

[0036] 6A, the CPU 91 switches the valves 81, 83, and 84 from the closed position to the open position with the pump 51 stopped, thereby bringing all of the valves 81 to 84 into the open position (S4). At this time, the release of the negative pressure causes a small amount of ink in the ink tanks 73 and 74 to move toward the head 10.

[0037] 6B, the CPU 91 switches the valves 81, 82, and 84 from the open position to the closed position, and drives the pump 51 with the valve 83 in the open position and the valves 81, 82, and 84 in the closed position, thereby generating a suction force within the cap 50 and supplying cyan ink from the ink tank 73 to the flow path 120C (and thus to the nozzles 15 constituting the nozzle row 15C) via the tube 63 (S5). At this time, negative pressure is generated in the flow path 120M and in a portion of the tube 64 closer to the flow path 120M than the valve 84.

[0038] The suction force generated in the cap 50 in S5 is weaker than the suction force generated in the cap 50 in S3. For example, the CPU 91 may set the rotation speed of the pump 51 in S5 to be slower than the rotation speed of the pump 51 in S3. Alternatively, the CPU 91 may set the rotation amount of the pump 51 in S5 to be slower than the rotation amount of the pump 51 in S3. Alternatively, in a case where the pump 51 includes a first pump, a second pump having a suction force weaker than the first pump, and a third pump having a suction force weaker than the second pump, the CPU 91 may drive the first pump in S1, the second pump in S3, and the third pump in S5.

[0039] After S5, the CPU 91 switches the valves 81, 82, and 84 from the closed position to the open position while stopping the pump 51, as shown in Fig. 6C, so that all of the valves 81 to 84 are in the open position (S6). At this time, the release of the negative pressure causes a small amount of ink in the ink tank 74 to move toward the head 10.

[0040] After S6, the CPU 91 switches the valves 81 to 83 from the open position to the closed position, as shown in Figure 6 (d), and drives the pump 51 with the valve 84 in the open position and the valves 81 to 83 in the closed position, thereby generating a suction force within the cap 50 and supplying magenta ink from the ink tank 74 through the tube 64 to the flow path 120M (and thus the nozzles 15 that make up the nozzle row 15M) (S7).

[0041] The suction force generated in the cap 50 in S7 is weaker than the suction force generated in the cap 50 in S5. For example, the CPU 91 may set the rotation speed of the pump 51 in S7 to be lower than the rotation speed of the pump 51 in S5. Alternatively, the CPU 91 may set the rotation amount of the pump 51 in S7 to be lower than the rotation amount of the pump 51 in S5. Alternatively, in a case where the pump 51 includes a first pump, a second pump having a lower suction force than the first pump, a third pump having a lower suction force than the second pump, and a fourth pump having a lower suction force than the third pump, the CPU 91 may drive the first pump in S1, the second pump in S3, the third pump in S5, and the fourth pump in S7.

[0042] After S7, the CPU 91 ends the program.

[0043] As described above, according to this embodiment, as shown in FIG. 4 , ink is supplied to each flow path 120 in steps S1 (first step) and S3 (second step). This prevents the suction force in the cap 50 from being dispersed across multiple flow paths 120, thereby reducing the time required for ink supply. Furthermore, instead of generating the same suction force in steps S1 (first step) and S3 (second step), a suction force weaker than that of step S1 is generated in step S3. This reduces the amount of waste ink even if ink corresponding to the negative pressure generated in step S1 moves toward the head 10, as shown in FIGS. 5A and 5B . In other words, according to this embodiment, both the time required for ink supply to the nozzles 15 and the amount of waste ink can be reduced. This effect is similar whether S3 is considered the first step and S5 the second step, or whether S5 is considered the first step and S7 the second step.

[0044] After S1 (first step: see FIG. 5A) and before S3 (second step: see FIG. 5C), the CPU 91 further executes S2 (third step: see FIG. 5B), which places all valves 81 to 84 in the open position. In this case, residual pressure in the head 10 is released by S2 (third step). By subsequently executing S3 (second step), backflow does not occur in the head 10 and an appropriate amount of ink can be supplied. Furthermore, when ink colors differ for each flow path 120 as in this embodiment, backflow within the head 10 can cause color mixing. However, with this configuration, backflow does not occur and color mixing can also be suppressed. This effect is similar whether S3 is interpreted as the first step, S5 as the second step, and S4 as the third step, or whether S5 is interpreted as the first step, S7 as the second step, and S6 as the third step.

[0045] The CPU 91 stops the pump 51 in S2, S4, and S6 (third step) (see FIGS. 5B, 6A, and 6C). If the pump 51 were driven in S2, S4, and S6, a backflow could occur in the head 10 due to the suction force generated in the cap 50. In this regard, in this embodiment, stopping the pump 51 in S2, S4, and S6 can suppress backflow in the head 10.

[0046] Next, a printer according to another embodiment of the present disclosure will be described.

[0047] The CPU 91 stops the pump 51 in S2, S4, and S6 (third step), but may also drive the pump 51 in S2, S4, and S6 (third step). In S2, S4, and S6, the suction force generated in the cap 50 moves ink from the ink tanks 72 to 74 toward the head 10. This reduces the time required for the subsequent steps S3, S5, and S7 (second step).

[0048] Next, a printer according to another embodiment of the present disclosure will be described.

[0049] As shown in Fig. 4, the CPU 91 sets all the valves 81 to 84 in the open position after S1 and before S3, after S3 and before S5, and after S5 and before S7 (S2, S4, S6). Alternatively, as shown in Fig. 7, the CPU 91 may first switch the target valves 82 to 84 to the open position after S1 and before S3, after S3 and before S5, and after S5 and before S7 (S31, S32, S33: fourth step), and then set all the valves 81 to 84 in the open position (S2, S4, S6: fifth step).

[0050] For example, after S1 shown in Fig. 8A, the CPU 91 switches the valve 82 from the closed position to the open position (S31: fourth step) as shown in Fig. 8B, while keeping the valves 83 and 84 in the closed position. That is, the valves 81 and 82 are in the open position and the valves 83 and 84 are in the closed position. At this time, the release of the negative pressure generated in S1 causes a small amount of ink in the ink tank 72 to move toward the head 10. The amount of ink that moves at this time is greater than when all of the valves 81 to 84 are in the open position at once, as in the first embodiment (see Fig. 5B).

[0051] After S31, the CPU 91 switches the valves 83 and 84 from the closed position to the open position, as shown in FIG. 8C, so that all the valves 81 to 84 are in the open position (S2: fifth step).

[0052] As described above, S31 and S2 (fourth and fifth steps) release the residual pressure in the head 10. By subsequently performing S3 (second step), backflow does not occur in the head 10 in S3, and an appropriate amount of ink can be supplied. Furthermore, if the ink colors differ for each flow path 120, backflow within the head 10 can cause color mixing, but with this configuration, backflow does not occur and color mixing can also be suppressed.

[0053] Furthermore, after S1 and before S3, all of the valves 81 to 84 are not opened at once, but are opened in stages. Specifically, in S31 (fourth step), the valve 82 is opened, and in S2 (fifth step), the valves 83 and 84 are opened. This allows ink to be supplied to the flow path 120Y before ink is supplied to the flow paths 120C and 120M.

[0054] The above effect is the same even if S3 is interpreted as the first step, S5 as the second step, S32 as the fourth step, and S4 as the fifth step, or even if S5 is interpreted as the first step, S7 as the second step, S33 as the fourth step, and S6 as the fifth step.

[0055] <Modifications> The present disclosure is not limited to the above-described embodiments.

[0056] For example, in the program shown in FIG. 4 , the suction force inside the cap is gradually weakened in each of steps S1, S3, S5, and S7, but this is not limiting. For example, the suction force inside the cap in S3 and the suction force inside the cap in S5 may be the same. Furthermore, the suction force inside the cap in S3 may be equal to or greater than the suction force inside the cap in S1. The suction force inside the cap in S5 or S7 may be weaker than the suction force inside the cap in S3. That is, it is sufficient if there is a combination of two steps in S1, S3, S5, and S7, in which the suction force inside the cap in the ink supply executed later is weaker than the suction force inside the cap in the ink supply executed earlier. The step in which the suction force inside the cap is relatively strong is an example of the "first step" of the present disclosure, and the step in which the suction force inside the cap is relatively weak is an example of the "second step" of the present disclosure.

[0057] Although ink is supplied from four ink tanks to four flow paths, this is not a limitation. The number of tanks and the number of flow paths to which liquid is supplied from each tank may be two or more.

[0058] S1 to S7 are performed for the four nozzle rows 15K, 15Y, 15C, and 15M of the head 10 that ejects color inks, but similar processes to S1 to S7 may also be performed for multiple nozzle rows of a head that ejects white ink.

[0059] The first liquid, the second liquid, and the third liquid may be the same in color or composition, or may be different in color or composition.

[0060] The first liquid, second liquid, and third liquid are not limited to ink, and may be liquids other than ink (for example, a treatment liquid that aggregates or precipitates components in ink).

[0061] The object onto which the liquid is ejected (the print medium in the above-described embodiment) is not limited to fabric, but may be paper, a resin member, or the like.

[0062] The nozzle surface may be divided into an area where the first nozzles are open and an area where the second nozzles are open.

[0063] The present disclosure is not limited to printers, but can also be applied to facsimiles, copiers, multifunction peripherals, etc. The present disclosure can also be applied to liquid ejection devices used for purposes other than image recording (for example, liquid ejection devices that eject a conductive liquid onto a substrate to form a conductive pattern).

[0064] The program according to the present disclosure can be distributed by recording it on a removable recording medium such as a flexible disk or a fixed recording medium such as a hard disk, or can be distributed via a communication line.

[0065] 10 Head 12X Lower surface (nozzle surface) 15 Nozzles (first nozzle, second nozzle, third nozzle) 50 Cap 51 Pump 61 to 64 Tubes (first flow path, second flow path, third flow path) 71 to 74 Ink tanks (first tank, second tank, third tank) 81 to 84 Valves (first valve, second valve, third valve) 91 CPU (control unit) 100 Printer (liquid ejection device)

Claims

1. A head having a nozzle surface with a first nozzle and a second nozzle opening therein; a cap in contact with the nozzle surface to cover the first nozzle and the second nozzle; a pump connected to the cap; a first tank for storing a first liquid and communicating with the first nozzle via a first flow path; a second tank for storing a second liquid and communicating with the second nozzle via a second flow path; a first valve that can selectively take an open position that opens the first flow path and a closed position that closes the first flow path; a second valve that can selectively take an open position that opens the second flow path and a closed position that closes the second flow path; and a control unit, wherein the control unit performs a first step of generating a first suction force within the cap and supplying the first liquid from the first tank to the first nozzle via the first flow path by driving the pump with the first valve in the open position and the second valve in the closed position; a second step of, after the first step, driving the pump with the first valve in a closed position and the second valve in an open position to generate a second suction force weaker than the first suction force within the cap, thereby supplying the second liquid from the second tank to the second nozzle via the second flow path.

2. The liquid ejection device according to claim 1, characterized in that the control unit further executes a third step after the first step and before the second step, in which the first valve is in an open position and the second valve is in an open position.

3. The liquid ejection device according to claim 2, wherein the control unit stops the pump in the third step.

4. The liquid ejection device according to claim 2, wherein the control unit drives the pump in the third step.

5. The liquid ejection device of claim 1, further comprising: a third nozzle further opening in the nozzle surface; the cap covering the first nozzle, the second nozzle, and the third nozzle; a third tank for storing a third liquid and communicating with the third nozzle via a third flow path; and a third valve that can selectively take an open position that opens the third flow path and a closed position that closes the third flow path; and the control unit further executes, after the first step and before the second step, a fourth step of setting the first valve in the open position, the second valve in the open position, and the third valve in the closed position; and a fifth step of setting the first valve in the open position, the second valve in the open position, and the third valve in the open position after the fourth step.

6. A control method for controlling a liquid ejection device comprising: a head having a nozzle surface with first and second nozzles opening therein; a cap that contacts the nozzle surface and covers the first and second nozzles; a pump connected to the cap; a first tank that stores a first liquid and is in communication with the first nozzle via a first flow path; a second tank that stores a second liquid and is in communication with the second nozzle via a second flow path; a first valve that can selectively take an open position that opens the first flow path and a closed position that closes the first flow path; and a second valve that can selectively take an open position that opens the second flow path and a closed position that closes the second flow path, the method comprising: a first step of generating a first suction force in the cap and supplying the first liquid from the first tank to the first nozzle via the first flow path by driving the pump with the first valve in the open position and the second valve in the closed position; a second step of, after the first step, driving the pump with the first valve in a closed position and the second valve in an open position to generate a second suction force weaker than the first suction force in the cap, thereby supplying the second liquid from the second tank to the second nozzle via the second flow path.

7. A control unit used in a liquid ejection device including a head having a nozzle surface with first and second nozzles opening therein, a cap in contact with the nozzle surface to cover the first and second nozzles, a pump connected to the cap, a first tank that stores a first liquid and is in communication with the first nozzle via a first flow path, a second tank that stores a second liquid and is in communication with the second nozzle via a second flow path, a first valve that can selectively take an open position that opens the first flow path and a closed position that closes the first flow path, and a second valve that can selectively take an open position that opens the second flow path and a closed position that closes the second flow path, comprising: a first step of generating a first suction force in the cap and supplying the first liquid from the first tank to the first nozzle via the first flow path by driving the pump with the first valve in the open position and the second valve in the closed position; a second step of generating a second suction force weaker than the first suction force in the cap by driving the pump with the first valve in a closed position and the second valve in an open position after the first step, thereby supplying the second liquid from the second tank to the second nozzle via the second flow path.

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