Liquid ejection device

Abstract

To provide a liquid discharging device which can agitate a liquid in a tank without use of a pump.SOLUTION: A liquid discharging device comprises: two white tanks 330W1, 330W2 which accommodate a white ink 311W to be supplied to a white head 2W; and a buffer tank 340 which communicates with the two white tanks 330W1, 330W2. The white ink 311W is moved between the white tanks 330W1, 330W2 and the buffer tank 340 by a differential pressure between a first pressure P1 and a third pressure applied to the buffer tank 340 and a second pressure P2 applied to two white tanks 330W1, 330W2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a device for discharging liquid. [Background technology]

[0002] In a liquid ejection device, if the liquid to be ejected is left in a tank serving as a liquid storage means for a long period of time, some components such as pigments will settle and the quality will become unstable.

[0003] Therefore, a conventional liquid ejector is known which includes a first liquid tank to which a first pressure is applied, a second liquid tank to which a second pressure different from the first pressure is applied, a flow path connecting the first liquid tank and the second liquid tank so as to allow liquid to be transferred between them, a head connected to the flow path between the first liquid tank and the second liquid tank so as to allow liquid to be exchanged, and a pressure control means which transfers liquid back and forth between the first and second liquid tanks via the flow path and controls the pressures applied to the first and second liquid tanks so that a constant negative pressure is always applied to the liquid inside the head (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-213281 Summary of the Invention [Problem to be solved by the invention]

[0005] However, a configuration that has multiple tanks and uses a pump to move and agitate liquid between the tanks has the problem that it cannot be used in systems that pressurize the tanks to supply the liquid to the head, or in cases where the liquid contains special components and a pump cannot be used.

[0006] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to make it possible to agitate liquid in a tank without using a pump. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention Claim 1 The liquid ejection device according to the present invention a first pressure source that generates a first pressure; one or more second pressure sources generating a second pressure less than the first pressure; a third pressure source that generates a third pressure that is lower than the second pressure; a first head communicating with the second pressure source; 2nd 1 liquid supply at least two first tanks; a second tank communicating with the first pressure source and the third pressure source and communicating with the two first tanks; a first valve that opens and closes a path connecting the first pressure source and the second tank; second valves for opening and closing each of the liquid paths between the two first tanks and the head; a third valve that opens and closes a path connecting the third pressure source and the second tank; a fourth valve for opening and closing each of the liquid paths between the second tank and the two first tanks, The first liquid is moved between the first tank and the second tank by controlling opening and closing of the first valve, the second valve, the third valve, and the fourth valve, and by a pressure difference between the first pressure and the third pressure and the second pressure. 、 The first pressure generated by the first pressure source, the second pressure generated by the second pressure source, and the third pressure generated by the third pressure source are all positive pressures. A liquid ejection device comprising: The composition was as follows. [Effects of the Invention]

[0008] According to the present invention, the liquid in the tank can be agitated without using a pump. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram illustrating a first embodiment of the present invention. [Figure 2] 2A to 2C are explanatory diagrams illustrating main operation modes in the embodiment. [Figure 3] 4A to 4C are explanatory diagrams illustrating the open / closed states of each valve in each operation mode. [Figure 4] FIG. 10 is an explanatory diagram for explaining mode A. [Figure 5] FIG. 10 is an explanatory diagram for explaining Mode B. [Figure 6] FIG. 10 is an explanatory diagram for explaining Mode C. [Figure 7] FIG. 10 is an explanatory diagram for explaining Mode D. [Figure 8] FIG. 10 is an explanatory diagram for explaining mode E. [Figure 9] FIG. 10 is an explanatory diagram illustrating a second embodiment of the present invention. [Figure 10] 2A to 2C are explanatory diagrams illustrating main operation modes in the embodiment. [Figure 11] 4A to 4C are explanatory diagrams illustrating the open / closed states of each valve in each operation mode. [Figure 12] FIG. 10 is an explanatory diagram for explaining Mode F. [Figure 13] FIG. 10 is an explanatory diagram for explaining mode G. [Figure 14] FIG. 10 is an explanatory diagram for explaining Mode H. [Figure 15] FIG. 10 is an explanatory diagram for explaining Mode J. [Figure 16] FIG. 10 is an explanatory diagram for explaining mode K. [Figure 17] FIG. 10 is an illustrative side view of a liquid ejecting device according to a third embodiment of the present invention. [Figure 18] FIG. [Figure 19] FIG. 2 is a perspective view illustrating an example of a discharge unit. [Figure 20] FIG. [Figure 21] FIG. [Figure 22] FIG. 2 is a cross-sectional view illustrating one nozzle portion for explaining an example of a head. [Figure 23] It is an explanatory diagram of an example of a drive voltage used for explaining the operation of the head. [Figure 24] It is an explanatory diagram used for explaining when printing an object to be drawn as an aircraft using a liquid discharging apparatus according to a fourth embodiment of the present invention. [Figure 25] It is a perspective explanatory diagram of an apparatus for discharging the same liquid. [Figure 26] It is a perspective explanatory diagram of an apparatus for discharging a liquid according to a fifth embodiment of the present invention. [Figure 27] It is a perspective explanatory diagram of a drive unit of the same apparatus.

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The first embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is an explanatory diagram used for explaining the same embodiment.

[0011] A liquid discharging apparatus 1000 includes a white head 2W which is a first head for discharging a liquid, a color head 2C which is a second head, two first tanks which are white tanks 330W (300W1, 330W2), a buffer tank 340 which is a second tank, and a color tank 330C which is a third tank.

[0012] The white head 2W discharges white ink 311W which is a first liquid. The color head 2C discharges color ink 311C which is a second liquid. The white head 2W and the color head 2C are provided with a valve mechanism inside, and discharge the liquid (ink) supplied under pressure by appropriately opening the valve according to an image signal.

[0013] Further, it includes a first pressure source 331, second pressure sources 332 (332a, 332b), and a third pressure source 333. The first pressure source 331 generates (produces) a first pressure P1. The second pressure sources 332a, 332b generate (produce) a second pressure P2 (P2 < P1) which is smaller than the first pressure P1. The third pressure source 333 generates (produces) a third pressure P3 (P3 < P2) which is smaller than the second pressure P2.

[0014] In this embodiment, the first pressure source 331, the second pressure source 332 (332a, 332b), and the third pressure source 333 are configured as regulators that adjust the pressure generated by the compressor 230 to a first pressure P1, a second pressure P2, and a third pressure P3, respectively.

[0015] The two white tanks 330W1 and 330W2 are liquid tanks that contain the first liquid (white ink 311W) that is ejected from the white head 2W.

[0016] The white tank 330W1 is connected to a second pressure source 332a that generates a second pressure P2 via an air path 382a. An on-off valve 350W1 that opens and closes the air path 382a is disposed in the air path 382a that connects the white tank 330W1 and the second pressure source 332a. As a result, when the on-off valve 350W1 is open, the second pressure P2 is applied to the white tank 330W1.

[0017] The white tank 330W2 is connected to a second pressure source 332b that generates a second pressure P2 via an air path 382b. An on-off valve 350W2 that opens and closes the air path 382b is disposed in the air path 382b that connects the white tank 330W2 and the second pressure source 332b. As a result, when the on-off valve 350W2 is open, the second pressure P2 is applied to the white tank 330W2.

[0018] A second valve 370W1 that opens and closes the liquid path 391a is disposed in the liquid path 391a between the white tank 330W1 and the white head 2W. Therefore, with the second valve 370W1 open, the white ink 311W is supplied under pressure from the white tank 330W1 to the white head 2W.

[0019] A second valve 370W2 that opens and closes the liquid path 391b is disposed in the liquid path 391b between the white tank 330W2 and the white head 2W. Therefore, with the second valve 370W2 open, the white ink 311W is supplied under pressure from the white tank 330W2 to the white head 2W.

[0020] As a result, when at least one of the second valves 370W1, 370W2 is open, a sufficient amount of white ink 311W is supplied under pressure to the white head 2W, and the pressure-supplied white ink 311W is ejected by opening the valve mechanism inside the white head 2W.

[0021] The buffer tank 340 is in communication with the bottoms (lower portions) of the two white tanks 330W1 and 330W2 via liquid paths 392 (392a and 392b). Fourth valves 360W1 and 360W2 that open and close the liquid paths 392a and 392b, respectively, are disposed in the liquid paths 392a and 392b between the buffer tank 340 and the two white tanks 330W1 and 330W2. The fourth valves may be configured, for example, by combining an on-off valve and a three-way valve.

[0022] The buffer tank 340 is in communication with the first pressure source 331 via an air path 384. A first valve 350H that opens and closes the air path 384 is provided in the air path 384 that connects the buffer tank 340 and the first pressure source 331.

[0023] The buffer tank 340 is in communication with the third pressure source 333 via an air path 383. The air path 383 connecting the buffer tank 340 and the third pressure source 333 is provided with a third valve 350L that opens and closes the air path 383.

[0024] The color tank 330C is a liquid tank that stores the second liquid (color ink 311C) that is ejected from the color head 2C. The color tank 330C is in communication with a first pressure source 331 that generates a first pressure P1 via an air path 381. A fifth valve 350C that serves as an air valve for opening and closing the air path 381 is disposed in the air path 381 that connects the color tank 330C and the first pressure source 331.

[0025] As a result, when the fifth valve 350C is open, the first pressure P1 is applied to the color tank 330C, and the color ink 311C is supplied under pressure to the color head 2C. Therefore, by opening the valve mechanism inside the color head 2C, the pressurized and supplied color ink 311C is ejected.

[0026] It should be noted that solenoid valves are used as the first valve 350H, the second valve 370W1, the second valve 370W2, the third valve 350L, the fourth valve 360W1, the fourth valve 360W2, the on-off valve 350W1, and the on-off valve 350W2.

[0027] Next, the main operation modes in this embodiment will be described with reference to Fig. 2. Fig. 2 is an explanatory diagram for explaining the main operation modes during printing.

[0028] The main operating modes during printing are modes A to E. Mode A is the most basic operating mode when printing using color ink 311C and white ink 311W. Modes B, C, D, and E are modes in which the white ink 311 in the white tanks 330W1 and 330W2 is agitated while printing using color ink 311C and white ink 311W.

[0029] Next, each operation mode will be explained with reference to Figures 3 to 8. Figure 3 is an explanatory diagram illustrating the open / closed state of each valve in each operation mode, and Figures 4 to 8 are explanatory diagrams illustrating modes A to E. Note that solid arrows in Figures 4 to 8 indicate the direction of air flow, and dashed arrows indicate the direction of liquid (ink) flow.

[0030] 3 and 4, in mode A, the first valve 350C of the air path 381 and the second valves 370W1 and 370W2 of the liquid paths 391a and 391b are open. Also, the third valve 350L of the air path 383, the first valve 350H of the air path 384, and the fourth valves 360W1 and 360W2 of the liquid paths 392a and 392b are closed.

[0031] As a result, a first pressure P1 from the first pressure source 331 is applied to the color tank 330C, and a second pressure P2 from the second pressure source 332 is applied to the white tanks 330W1 and 330W2. Therefore, the color ink 311C and the white ink 311W are supplied under pressure to the color head 2C and the white head 2W, respectively, and the color ink 311C and the white ink 311W are ejected from the color head 2C and the white head 2W, respectively, in accordance with the image signals.

[0032] Next, the operation of stirring the white ink 311W in the white tank 330W while ejecting the color inks and white ink will be described.

[0033] First, each valve is set to the mode B state shown in Fig. 3. At this time, as shown in Fig. 5, the second valve 370W2 is closed, blocking the liquid path 391b between the white tank 310W2 and the white head 2W. Therefore, the white head 2W continues to eject white ink 311W supplied only from the white tank 330W1.

[0034] Furthermore, when the fourth valve 360W2 is opened, the white tank 330W2 is placed in communication with the buffer tank 340 via the liquid path 392b. At this time, when the third valve 350L is opened, a third pressure P3 is applied to the buffer tank 340. Because the third pressure P3 is set to be smaller than the second pressure P2 applied to the white tank 330W2, the pressure difference causes the white ink 311W to flow from the white tank 330W2 to the buffer tank 340.

[0035] After the white ink 311W has been transferred from the white tank 330W2 to the buffer tank 340, the valves are then set to the state of mode C in Figure 3. At this time, as shown in Figure 6, the first valve 350H is opened, and a first pressure P1 is applied to the buffer tank 340. As a result, the pressure in the buffer tank 340 becomes higher than that of the white tank 330W2, and the white ink 311W is returned from the buffer tank 340 to the white tank 330W2.

[0036] In this way, the white ink 311W moves back and forth between the white tank 330W2 and the buffer tank 340, thereby stirring the white ink 311W in the white tank 330W2 without using a pump.

[0037] Furthermore, in this embodiment, a fifth valve 350C is provided in the air path 381 between the color tank 330C and the first pressure source 331. Therefore, in mode C, by closing the fifth valve 350C when pressurizing the buffer tank 340 to the first pressure P1, the difference between the first pressure P1 and the second pressure P2 is increased, and the white ink 311W can be returned to the white tank 330W2 at high speed.

[0038] At this time, the color tank 330C is not supplied with air from the air compressor 230, which is adjusted to the first pressure P1 from the first pressure source 331. However, if the movement of the white ink 311W from the buffer tank 340 to the white tank 330W2 is short, there is almost no drop in pressure in the color tank 330C, and therefore there is no effect on ejection from the color head 2C.

[0039] If it takes time for the white ink 311W to move from the buffer tank 340 to the white tank 330W2, the first valve 350H and the fifth valve 350C are operated by alternately opening and closing them intermittently, thereby preventing a drop in pressure in the color tank 330C while discharging the white ink 311W into the white tank 330W2.

[0040] 3. To agitate the white ink 311W in the white tank 330W1 while supplying and ejecting the white ink 311W in the white tank 330W2 to the white head 2W, the valves are set to the state of mode D in FIG.

[0041] 7, the second valve 370W1 is closed, blocking the liquid path 391a between the white tank 310W1 and the white head 2W. Therefore, the white head 2W continues to eject the white ink 311W supplied only from the white tank 330W2.

[0042] Furthermore, when the fourth valve 360W1 is opened, the white tank 330W1 is placed in communication with the buffer tank 340 via the liquid path 392a. At this time, when the third valve 350L is opened, a third pressure P3 is applied to the buffer tank 340. Because the third pressure P3 is set to be smaller than the second pressure P2 applied to the white tank 330W1, the pressure difference causes the white ink 311W to flow from the white tank 330W1 to the buffer tank 340.

[0043] After the white ink 311W has been transferred from the white tank 330W1 to the buffer tank 340, the valves are then set to the state of mode E in Figure 3. At this time, as shown in Figure 8, the first valve 350H is opened, and a first pressure P1 is applied to the buffer tank 340. As a result, the pressure in the buffer tank 340 becomes higher than that of the white tank 330W1, and the white ink 311W is returned from the buffer tank 340 to the white tank 330W1.

[0044] In this way, the white ink 311W moves back and forth between the white tank 330W1 and the buffer tank 340, thereby stirring the white ink 311W in the white tank 330W1 without using a pump.

[0045] Furthermore, in this embodiment, a fifth valve 350C is provided in the air path 381 between the color tank 330C and the first pressure source 331. Therefore, in mode E, by closing the fifth valve 350C when pressurizing the buffer tank 340 to the first pressure P1, the difference between the first pressure P1 and the second pressure P2 is increased, and the white ink 311W can be returned to the white tank 330W1 at high speed.

[0046] At this time, the color tank 330C is not supplied with air from the compressor 230, which is adjusted to the first pressure P1 from the first pressure source 331. However, if the movement of the white ink 311W from the buffer tank 340 to the white tank 330W1 is short, there is almost no pressure drop in the color tank 330C, and therefore there is no effect on ejection from the color head 2C.

[0047] If it takes time for the white ink 311W to move from the buffer tank 340 to the white tank 330W1, the first valve 350H and the fifth valve 350C are operated by alternately opening and closing them intermittently, thereby preventing a drop in pressure in the color tank 330C while discharging the white ink 311W into the white tank 330W1.

[0048] As described above, in this embodiment, an apparatus that discharges a plurality of liquids by pressurizing them at different pressures includes a plurality of liquid tanks that contain the liquids that require agitation, and a buffer tank that communicates with the plurality of liquid tanks. The pressure that pressurizes the liquid tanks is used to move the liquid back and forth between the liquid tanks and the buffer tank, thereby agitating the liquid, so that the quality inside the liquid tanks, which is maintained at high pressure, can be maintained constant without using a pump.

[0049] Next, a second embodiment of the present invention will be described with reference to Fig. 9. Fig. 9 is an explanatory diagram for explaining the second embodiment.

[0050] The liquid ejecting apparatus 1000 according to this embodiment includes, in addition to the components of the apparatus 1000 according to the first embodiment, a treatment liquid head 2X that is a third head that ejects a third liquid, and a treatment liquid tank 330X that is a fourth tank that contains a treatment liquid 311X that is the third liquid to be supplied to the treatment liquid head 2X. The treatment liquid 311X is, for example, an overcoat liquid such as a pre-treatment liquid or a post-treatment liquid.

[0051] The treatment liquid tank 330X is connected to the third pressure source 333 via an air path 386 and an air path 383. The air path 386 is connected to the air path 383 upstream of the third valve 350L. A sixth valve 350X that opens and closes the air path 386 is provided in the air path 386. Therefore, the treatment liquid 311X is selected to be one that can be discharged at a third pressure P3 that is lower than the first pressure P1 and the second pressure P2.

[0052] In this embodiment, liquid level sensors 334W1, 334W2, and 334V are provided between the white tanks 330W1, 330W2 and the buffer tank 340 near the bottom of the white tanks 330W1, 330W2 to sense the liquid level of the liquid (white ink 311W).

[0053] Next, the main operation modes in this embodiment will be described with reference to Fig. 10. Fig. 10 is an explanatory diagram for explaining the main operation modes during printing.

[0054] The main operating modes during printing are modes F to K. Mode F is the most basic operating mode when printing using the color inks 311C, white ink 311W, and treatment liquid 311X. Modes G, H, I, and J are modes in which the white ink 311W in the white tanks 330W1 and 330W2 is agitated while printing using the color inks 311C, white ink 311W, and treatment liquid 311X.

[0055] Next, each operation mode will be explained with reference to Figures 11 to 16. Figure 11 is an explanatory diagram illustrating the open / closed state of each valve in each operation mode, and Figures 12 to 16 are explanatory diagrams illustrating modes F to K. Note that solid arrows in Figures 12 to 16 indicate the direction of air flow, and dashed arrows indicate the direction of liquid (ink) flow.

[0056] 11 and 12, in mode F, the first valve 350C in air path 381, the sixth valve 350X in air path 386, and the second valves 370W1 and 370W2 in liquid paths 391a and 391b are open. Also, the third valve 350L in air path 383, the first valve 350H in air path 384, and the fourth valves 360W1 and 360W2 in liquid paths 392a and 392b are closed.

[0057] As a result, a first pressure P1 is applied from the first pressure source 331 to the color tank 330C. A second pressure P2 is applied from the second pressure source 332 to the white tanks 330W1 and 330W2. Furthermore, a third pressure P3 is applied from the third pressure source 333 to the treatment liquid tank 330X.

[0058] Therefore, the color ink 311C, the white ink 311W, and the treatment liquid 311X are supplied under pressure to the color head 2C, the white head 2W, and the treatment liquid head 2X, respectively, and the color ink 311C, the white ink 311W, and the treatment liquid 311X are ejected from the color head 2C, the white head 2W, and the treatment liquid head 2X, respectively, in accordance with image signals, etc.

[0059] Next, the operation of stirring the white ink in the white tank while ejecting all the liquid will be described.

[0060] First, each valve is set to mode G1. At this time, as shown in Figure 13, the second valve 370W2 is closed, blocking the liquid path 391b between the white tank 330W2 and the white head 2W. Therefore, the white head 2W continues to eject white ink 311W supplied only from the white tank 330W1.

[0061] Furthermore, when the fourth valve 360W2 is opened, the white tank 330W2 is placed in communication with the buffer tank 340 via the liquid path 392b. Here, when the third valve 350L is opened, the third pressure P3 of the buffer tank 340 is set to be smaller than the second pressure P2 of the white tank 330W2, and therefore the white ink 311W flows from the white tank 330W2 to the buffer tank 340 due to the pressure difference.

[0062] In this mode G1, the sixth valve 350X is closed, so air is not supplied to the treatment liquid tank 330X from the compressor 230 via the third pressure source 333. However, if the movement of the white ink 311W from the white tank 330W2 to the buffer tank 340 is short, the pressure drop in the treatment liquid tank 330X is small, so there is no effect on the ejection of the treatment liquid 311X from the treatment liquid head 2X.

[0063] If the movement of the white ink 311W from the white tank 330W2 to the buffer tank 340 does not finish within a short time (predetermined time), the mode shifts to mode G2, the third valve 350L is closed, and the sixth valve 350X is opened.

[0064] As a result, the movement of the white ink 311W to the buffer tank 340 temporarily stops, but the pressure in the treatment liquid tank 330X can be restored because the third pressure P3 is applied to the treatment liquid tank 330X from the third pressure source 333. After the pressure is restored, the movement of the white ink 311W from the white tank 330W2 to the buffer tank 340 resumes by returning to mode G1.

[0065] In this way, the white ink 311W is moved from the white tank 330W2 to the buffer tank 340 while alternately repeating the mode G1 and the mode G2.

[0066] Then, when the liquid level sensor 334W2 detects that the remaining amount of white ink 311W in the white tank 330W2 is low, the fourth valve 360W2 and the third valve 350L are closed, thereby stopping the movement of the white ink 311W from the white tank 330W2 to the buffer tank 340.

[0067] Next, each valve is set to the state of Mode H. At this time, as shown in Figure 14, the first valve 350H is opened, and a first pressure P1 is applied to the buffer tank 340. As a result, the pressure in the buffer tank 340 becomes higher than that in the white tank 330W2, and the white ink 311W is returned from the buffer tank 340 to the white tank 330W2.

[0068] Then, the fourth valve 360W2 and the first valve 350H are closed at the timing when the liquid level sensor 334V detects the liquid level in the buffer tank 340. This stops the movement of the white ink 311W from the buffer tank 340 to the white tank 330W2.

[0069] In this way, the white ink 311W moves back and forth between the white tank 330W2 and the buffer tank 340, thereby stirring the white ink 311W in the white tank 330W2 without using a pump.

[0070] Furthermore, in this embodiment, a fifth valve 350C is provided in the air path 381 between the color tank 330C and the first pressure source 331. Therefore, in mode H, by closing the fifth valve 350C when pressurizing the buffer tank 340 to the first pressure P1, the difference between the first pressure P1 and the second pressure P2 is increased, and the white ink 311W can be returned to the white tank 330W2 at high speed.

[0071] At this time, the color tank 330C is not supplied with air from the compressor 230, which is adjusted to the first pressure P1 from the first pressure source 331. However, if the movement of the white ink 311W from the buffer tank 340 to the white tank 330W2 is short, there is almost no pressure drop in the color tank 330C, and therefore there is no effect on ejection from the color head 2C.

[0072] If it takes time for the white ink 311W to move from the buffer tank 340 to the white tank 330W2, the first valve 350H and the fifth valve 350C are operated by alternately opening and closing them intermittently, thereby preventing a drop in pressure in the color tank 330C while discharging the white ink 311W into the white tank 330W2.

[0073] Next, to agitate the white ink 311W in the white tank 330W1 while ejecting the white ink 311W in the white tank 330W2 from the white head 2W, it is first necessary to return the pressure in the buffer tank 340 to the third pressure P3.

[0074] Therefore, each valve is set to a state of mode I1. In mode I1, the first valve 350H and the sixth valve 350X are closed, and the third valve 350L is opened. This causes the high-pressure air in the buffer tank 340 to be discharged from the regulator of the third pressure source 333.

[0075] At this time, the supply of pressure to the processing liquid tank 330X is stopped by closing the sixth valve 350. If the air discharge from the buffer tank 340 does not finish within a short time, the valves are switched to the mode I2, the third valve 350L is closed, and the sixth valve 350X is opened, and the pressure in the processing liquid tank 330X is restored to the third pressure P3.

[0076] By repeating these modes I1 and I2 several times, the pressure in the buffer tank 340 is set to the second pressure P2 again.

[0077] In modes I1 and I2, the fourth valves 360W1 and 360W2 are closed and the second valves 370W1 and 370W2 are open, so that the white ink 311W from the two white tanks 330W1 and 330W2 is supplied to the white head 2W and ejected.

[0078] Next, each valve is set to the mode J1 state. At this time, as shown in Figure 15, the second valve 370W1 is closed, blocking the liquid path 391a between the white tank 330W1 and the white head 2W. Therefore, the white head 2W continues to eject white ink 311W supplied only from the white tank 330W2.

[0079] Furthermore, when the fourth valve 360W1 is opened, the white tank 330W1 is placed in communication with the buffer tank 340 via the liquid path 392a. Here, when the third valve 350L is opened, the third pressure P3 of the buffer tank 340 is set to be smaller than the second pressure P2 of the white tank 330W1, and therefore the white ink 311W flows from the white tank 330W1 to the buffer tank 340 due to the pressure difference.

[0080] In this mode J1, the sixth valve 350X is closed, so air is not supplied to the treatment liquid tank 330X from the compressor 230 via the third pressure source 333. However, if the movement of the white ink 311W from the white tank 330W1 to the buffer tank 340 is short, the pressure drop in the treatment liquid tank 330X is small, so there is no effect on the ejection of the treatment liquid 311X from the treatment liquid head 2X.

[0081] If the movement of the white ink 311W from the white tank 330W1 to the buffer tank 340 does not finish within a short time (predetermined time), the mode shifts to mode J2, the third valve 350L is closed, and the sixth valve 350X is opened.

[0082] As a result, the movement of the white ink 311W to the buffer tank 340 temporarily stops, but the pressure in the treatment liquid tank 330X can be restored because the third pressure P3 is applied to the treatment liquid tank 330X from the third pressure source 333. After the pressure is restored, by returning to mode J1 again, the movement of the white ink 311W from the white tank 330W1 to the buffer tank 340 resumes.

[0083] In this way, the white ink 311W is moved from the white tank 330W1 to the buffer tank 340 while alternately repeating the mode J1 and the mode J2.

[0084] Then, when the liquid level sensor 334W1 detects that the remaining amount of white ink 311W in the white tank 330W1 is low, the fourth valve 360W1 and the third valve 350L are closed, thereby stopping the movement of the white ink 311W from the white tank 330W1 to the buffer tank 340.

[0085] Next, each valve is set to the mode K state. At this time, as shown in Figure 16, the first valve 350H is opened, and a first pressure P1 is applied to the buffer tank 340. As a result, the pressure in the buffer tank 340 becomes higher than that in the white tank 330W1, and the white ink 311W is returned from the buffer tank 340 to the white tank 330W1.

[0086] Then, the fourth valve 360W1 and the first valve 350H are closed at the timing when the liquid level sensor 334V detects the liquid level in the buffer tank 340. This stops the movement of the white ink 311W from the buffer tank 340 to the white tank 330W1.

[0087] In this way, the white ink 311W moves back and forth between the white tank 330W1 and the buffer tank 340, thereby stirring the white ink 311W in the white tank 330W1 without using a pump.

[0088] Furthermore, in this embodiment, a fifth valve 350C is provided in the air path 381 between the color tank 330C and the first pressure source 331. Therefore, in mode K, by closing the fifth valve 350C when pressurizing the buffer tank 340 to the first pressure P1, the difference between the first pressure P1 and the second pressure P2 is increased, and the white ink 311W can be returned to the white tank 330W1 at high speed.

[0089] At this time, the color tank 330C is not supplied with air from the compressor 230, which is adjusted to the first pressure P1 from the first pressure source 331. However, if the movement of the white ink 311W from the buffer tank 340 to the white tank 330W1 is short, there is almost no pressure drop in the color tank 330C, and therefore there is no effect on ejection from the color head 2C.

[0090] If it takes time for the white ink 311W to move from the buffer tank 340 to the white tank 330W1, the first valve 350H and the fifth valve 350C are operated by alternately opening and closing them intermittently, thereby preventing a drop in pressure in the color tank 330C while discharging the white ink 311W into the white tank 330W1.

[0091] In this way, the liquid can be agitated by exchanging the liquid with the buffer tank using the pressure of a liquid that is higher or lower than the liquid that needs to be agitated. By providing a liquid level sensor in each tank, it is possible to detect the completion of the liquid transfer between the tanks, and by controlling the transfer of the liquid at the appropriate time, it is possible to perform the agitation efficiently.

[0092] In each of the above embodiments, the tank containing white ink is used as the first tank, and the liquid is stirred by moving the liquid between the tank and the buffer tank (second tank), but the liquid contained in the first tank is not limited to white ink. For example, it is also possible to provide a plurality of tanks containing color inks or tanks containing treatment liquid as the first tank, and to move the liquid between the tank and the buffer tank (second tank) to stir the liquid.

[0093] Next, a third embodiment of the present invention will be described with reference to Figures 17 and 18. Figure 17 is a side view of the device for discharging liquid according to this embodiment, and Figure 18 is a plan view of the same.

[0094] The liquid ejecting device 1000 is provided facing a drawing target 100, which is an example of an object, and includes an ejection unit 1 that ejects ink, which is an example of a liquid, toward the drawing target 100.

[0095] The liquid discharging device 1000 includes a Z-axis rail 103 that holds the discharging unit 1 movably in the Z-axis direction, an X-axis rail 101 that holds the Z-axis rail 103 movably in the X-axis direction, and a Y-axis rail 102 that holds the X-axis rail 101 movably in the Y-axis direction. The X-axis rail 101, the Y-axis rail 102, and the Z-axis rail 103 are examples of a guide portion and a holder that movably hold the discharging unit 1.

[0096] The liquid ejection device 1000 also includes a Z-direction drive unit 111 that moves the ejection unit 1 in the Z-axis direction along the Z-axis rail 103, an X-direction drive unit 112 that moves the Z-axis rail 103 in the X-axis direction along the X-axis rail 101, and a Y-direction drive unit 113 that moves the X-axis rail 101 in the Y-axis direction along the Y-axis rail 102.

[0097] As a result, the liquid ejecting device 1000 can eject ink onto the drawing object 100 to draw a picture while moving the carriage 1 in the X-axis, Y-axis, and Z-axis directions. Note that although the drawing object 100 is illustrated as being in the form of a flat plate, it may also be a curved surface as long as it is a nearly vertical surface or a surface with a large radius of curvature, such as the body of a vehicle such as a car, truck, or airplane.

[0098] Next, an example of a discharge unit will be described with reference to Figures 19 to 21. Figure 19 is a perspective explanatory view of the discharge unit, Figure 20 is a side explanatory view of the same, and Figure 21 is a front explanatory view of the head portion of the same.

[0099] The ejection unit 1 has a head section (liquid ejection section) 20 that ejects liquid, and the head section 20 is integrally provided with a cleaning mechanism section 500 that includes a wiping member 501 that wipes a nozzle surface 202a that is an ejection surface.

[0100] In the head unit 20, a plurality of (here, five) heads 2 (color heads 2C1 to 2C4, white head 2W) that eject liquids (inks) of different colors are held by a holder member 21. The color heads 2C1 to 2C4 eject inks of each color, for example, yellow (Y), cyan (C), magenta (M), and black (K), respectively.

[0101] The head 2 has an array of nozzles 202 that eject liquid, and is held by a holder member 21 that serves as a housing, with the array direction of the nozzles 202 inclined with respect to the Y direction.

[0102] The cleaning mechanism 500 includes a wiping member 501 that wipes the nozzle surface 202a of the head 2, and a cleaning liquid ejection unit 502 that is a cleaning liquid application unit that ejects or drops cleaning liquid onto the nozzle surface 202a of the head 2.

[0103] The wiping member 501 and the cleaning liquid discharge part 502 are attached to and held by a moving member 505 .

[0104] Meanwhile, guide members 506, 506 having guide grooves 506a are attached to both sides of holder member 21 of head unit 20. A support shaft 505a of moving member 505 is movably fitted into guide groove 506a of guide member 506. In other words, holder member 21 serves as a housing that holds head 2 and movably supports moving member 505.

[0105] As a result, the moving member 505 is able to move along the guide groove 506a between a position where the wiping member 501 faces the nozzle surface 202a of the head 2 and a position where the wiping member 501 is retracted from the nozzle surface 202a.

[0106] A rotary air cylinder 510 is provided as a driving means for moving the moving member 505. One end of an arm 511 is attached to the rotary air cylinder 510, and the other end of the arm 511 has an elongated hole 511a which is movably fitted into a pin member 505b provided on the side of the moving member 505.

[0107] As a result, by driving the rotary air cylinder 510 to rotate the arm 511 in the direction of arrow A, the moving member 505 is guided by the guide groove 506a of the guide member 506 and moves as shown by arrow B from the retracted position shown by the imaginary line in Fig. 20 to the wiping end position, which is also the opposing position shown by the solid line. This movement of the moving member 505 allows the wiping member 501 to wipe the nozzle surface 202a of the head 2.

[0108] In this way, the discharge unit 1 integrally includes the head section 20, which is a liquid discharge section that discharges liquid, and the cleaning mechanism section 500 that wipes and cleans the nozzle surface 202a of the head 2 of the head section 20.

[0109] This allows the nozzle surface 202a of the head 2 to be wiped and cleaned when the discharge unit 1 is not discharging liquid, regardless of the position of the discharge unit 1, and the discharge surface (nozzle surface) can be cleaned at any time when necessary.

[0110] Next, an example of a head will be described with reference to Figure 22. Figure 22 is a cross-sectional explanatory diagram of one nozzle portion of the head. Figure 22(a) shows the state in which the nozzle is closed, and (b) shows the state in which the nozzle is open.

[0111] The head 2 is provided with a nozzle 202 at the tip for discharging liquid, and is provided with a hollow housing 204 provided near the nozzle 202 with an inlet 203 through which pressurized liquid (ink) is injected.

[0112] Within the housing 204 are a piezoelectric element 205 that expands and contracts in response to the application of an external voltage, a valve body 207 that opens and closes the nozzle 202, and a valve body moving means 208 that is positioned between the valve body 207 and the piezoelectric element 205 and moves the valve body 207 forward and backward relative to the nozzle 202.

[0113] The piezoelectric element 205 is housed in a case 215, and a pair of wiring members 210a and 210b for applying voltage are connected to it and drawn out to the outside.

[0114] A sealing member 206 is disposed between the valve body 207 and the housing 204 to prevent the pressurized liquid injected from the injection port 203 from entering the piezoelectric element 205. This forms a liquid chamber 209 into which the pressurized liquid is injected from the injection port 203.

[0115] The housing 204 is a cylindrical body having a cylindrical or rectangular shape, and is closed except for the nozzle 202 and the inlet 203. The nozzle 202 is an opening formed at the tip of the housing 204, and ejects the liquid 311 (color ink 311C, white ink 311W). The inlet 203 is provided on the side of the housing 204 near the nozzle 202, and pressurized liquid is continuously supplied through the inlet 203.

[0116] The piezoelectric element 205 is made of zirconia ceramics, etc. A driving waveform (driving voltage) is applied to the piezoelectric element 205 via wiring members 210a and 210b.

[0117] The sealing member 206 is, for example, a packing, an O-ring, or the like, and by fitting the sealing member 206 onto the outside of the valve body 207, the liquid is prevented from flowing from the injection port 203 side to the piezoelectric element 205 side.

[0118] The valve element moving means 208 has a deformation portion 208a with a generally trapezoidal cross section, which is formed from a restorable elastic member made of rubber, soft resin, thin metal plate, or the like. A connecting portion 208e, which corresponds to the upper side of the generally trapezoidal cross section of the deformation portion 208a, is fixed to the surface of the base end side of the valve element 207. The long side of the deformation portion 208a, which corresponds to the bottom side of the generally trapezoidal cross section, is connected to a bent side portion 208d. The radial center portion of the bent side portion 208d is connected to the guide portion 208c, and the portion between the radial center portion and the end portion is connected to a fixed portion 212, one end of which is connected to the case 215.

[0119] When a predetermined voltage is applied to the piezoelectric element 205 of this valve body moving means 208, the piezoelectric element 205 expands, and as shown in Figure 22(b), the guide portion 208c moves toward the nozzle 202 by, for example, a distance e, and the area near the center of the bent side portion 208d is pushed in.

[0120] At this time, because the outer circumferential side of guide portion 208c is connected to fixed portion 212, bent side portion 208d is displaced in the direction of the arrow starting from the connection portion with fixed portion 212. When bent side portion 208d is displaced in the direction of the arrow, deforming portion 208a expands, and connection portion 208e with valve body 207 is pulled in the direction of the arrow.

[0121] By this deformation of the deformation portion 208a of the valve element moving means 208, the valve element 207 fixed to the connecting portion 208e of the deformation portion 208a is pulled in by a distance d, and the nozzle 202 is opened.

[0122] That is, as the piezoelectric element 205 expands, the guide portion 208c moves by a distance e toward the nozzle 202, and the valve body 207 moves by the distance in the direction opposite to the movement direction of the guide portion 208 (the expansion direction of the piezoelectric element 205).

[0123] Here, by adjusting the distance between the connecting portion 208e with the valve body 207 at the deformation portion 208a of the valve body moving means 208 and the bending side portion 208d, and the length of the bending side portion 208d, the movement amount of the valve body 207 can be made longer than the displacement amount of the piezoelectric element 205.

[0124] In other words, the valve element moving means 208 can amplify the displacement of the piezoelectric element 205 and can reduce the displacement of the piezoelectric element 205, thereby allowing the piezoelectric element 205 to be made smaller.

[0125] Next, the operation of the head 2 will be described with reference to Fig. 23. Fig. 23 is an explanatory diagram of an example of a driving voltage used to explain the operation.

[0126] In the head 2, when no voltage is applied to the piezoelectric element 205, the piezoelectric element 205 is in a contracted state, and therefore no force is applied to the valve element moving means 208 by the piezoelectric element 205. At this time, the deformation portion 208a of the valve element moving means 208 is in a swollen state (normal state) as shown in Figure 23(a), and the valve element 207 is urged toward the nozzle 202 by the elastic force of the deformation portion 208a. Therefore, the nozzle 202 is closed by the end face of the valve element 207, and liquid 311 is not discharged from the nozzle 202.

[0127] 23(a), when a voltage (+EV) of waveform P1 is applied to piezoelectric element 205, piezoelectric element 205 expands, and as described above, deformation portion 208a of valve element moving means 208 deforms, pulling valve element 207 in the direction of the arrow shown in Fig. 22(b). As a result, valve element 207 opens nozzle 202, and pressurized liquid 311 injected from injection port 203 is discharged from nozzle 202.

[0128] On the other hand, as shown in Figure 23(b), a waveform P2 may be applied to the piezoelectric element 205 in which the voltage (+EV) of the waveform P2 disappears midway, or as shown in Figure 23(c), the voltage of the waveform that should be applied may not be applied to the piezoelectric element 205 due to a power outage or the like.

[0129] At this time, the piezoelectric element 205 maintains its contracted state, and the deforming portion 208a of the valve element moving means 208 returns to the normal state shown in Figure 22(a). Therefore, the valve element 207 maintains the state in which the nozzle 202 is closed, and the liquid 311 is not discharged from the nozzle 202.

[0130] This reduces the risk of the liquid 311 accidentally leaking out of the nozzle 202 or clogging the nozzle, even in the event of a power outage or the like.

[0131] Next, a fourth embodiment of the present invention will be described with reference to Fig. 24 and Fig. 25. Fig. 24 is an explanatory diagram illustrating printing an aircraft as a drawing object using a device for discharging liquid according to this embodiment, and Fig. 25 is a perspective explanatory diagram of the device for discharging liquid.

[0132] The liquid ejection device 1000 is equipped with a linear rail 404 that moves a carriage, which is a moving body carrying the ejection unit 1, back and forth in a straight line, and an articulated robot 405 that moves the linear rail 404 to a predetermined position as appropriate and holds it in that position.

[0133] The articulated robot 405 is equipped with a robot arm 405a that has multiple joints that allow it to move freely like a human arm, and the tip of the robot arm 405a can be moved freely and positioned accurately.

[0134] The articulated robot 405 may be, for example, a six-axis controlled industrial robot equipped with six axes, i.e., six joints. With a six-axis articulated robot, by teaching information regarding its operation in advance, it is possible to very accurately and quickly position the linear rail 404 at a predetermined position on the drawing target 100 (aircraft). The robot 405 is not limited to a six-axis robot, and an articulated robot equipped with an appropriate number of axes, such as five axes or seven axes, may be used.

[0135] A fork-shaped support member 424 that branches into two branches is provided on the robot arm 405a of this robot 405, and a vertical linear rail 423a is attached to the tip of the left branch 424a of this support member 424, and a vertical linear rail 423b is attached to the tip of the right branch 424b so that they are parallel to each other.

[0136] The discharge unit 1 is movably supported by a linear rail 404, and both ends of the linear rail 404 are supported by two vertical linear rails 423a and 423b so as to be bridged over the two rails.

[0137] The discharge unit 1 includes a plurality of heads 2 that discharge liquid of each color, for example, black, cyan, magenta, yellow, and white, or a head 2 that has a plurality of nozzle rows. Liquid of each color is supplied under pressure from a tank 330 to each head 2 or each nozzle row of the head 2 of the discharge unit 1.

[0138] In this liquid ejection device 1, a robot 405 moves a linear rail 404 to a position opposite the required drawing area of ​​the object 100, and the ejection unit 1 is moved along the linear rail 404 according to the print data while driving the head 2 to perform printing.

[0139] Then, when printing of one line is completed, the vertical linear rails 423a and 423b are driven to move the head 2 of the discharge unit 1 from one line to the next line.

[0140] By repeating this operation, printing can be performed on the desired printing area of ​​the object 100 to be drawn.

[0141] At this time, the moving distance of the discharge unit 1 (head 2) becomes longer, but the discharge unit 1 is provided with a wiping member 501, and can clean the nozzle surface 202a of the head 2 at any time.

[0142] This allows for continuous high-quality printing with minimal downtime.

[0143] Next, a fifth embodiment of the present invention will be described with reference to Figures 26 and 27. Figure 26 is a perspective view of a device for discharging liquid according to this embodiment, and Figure 27 is a perspective view of a drive unit of the device.

[0144] Liquid ejection device 1000 includes a movable frame unit 802 that is installed facing drawing target 100 having a curved surface, such as a vehicle hood. A movable unit 813 is attached to left and right frame members 810 and 811 that make up frame unit 802 so as to span between frame members 810 and 811 and be capable of moving up and down in the vertical direction (Y direction).

[0145] The movable unit 813 is equipped with a drive unit 803 incorporating a motor that is arranged so as to be able to move back and forth horizontally (in the X direction) on the movable unit 813, and an ejection unit 1 that is attached to the drive unit 803 and ejects liquid toward the object 100 to be drawn.

[0146] The device also includes a controller 805 that controls the ejection of liquid from the ejection unit 1, the reciprocating movement of the drive unit 803, and the elevation of the movable unit 813, and an information processing device 806 such as a PC (personal computer) that issues instructions to the controller 805. A database section (DB section) 807 that records and saves information about the object 100 to be drawn, such as its shape and size, is connected to the information processing device 806.

[0147] The frame unit 802 comprises upper, lower, left and right frame members 808, 809, 810, 811 formed from metal pillars or the like, and left and right leg members 812a, 812b attached horizontally and at right angles to both sides of the lower frame member 809 to enable the frame unit 802 to stand on its own.

[0148] A movable unit 813 spanning the left and right frame members 810 and 811 is configured to be able to move up and down while supporting the drive unit 803 .

[0149] The drawing target 100 is placed perpendicular to the liquid discharge direction (Z direction), that is, facing the plane formed by the upper, lower, left and right frame members 808, 809, 810, and 811 of the frame unit 802.

[0150] In this case, the object 100 can be positioned at a predetermined position where printing is to be performed by, for example, using a chuck attached to the tip of the arm of an articulated arm robot to suction and hold the back side of the drawing area of ​​the object 100. Using an articulated arm robot makes it possible to accurately position the object 100 at the printing position, and also makes it possible to change the posture of the object 100 as needed.

[0151] 27, the drive unit 803 is arranged so as to be able to move back and forth in the horizontal direction (X direction) on the movable unit 813. The movable unit 813 is composed of a rail 830 arranged horizontally so as to span between the left and right frame members 810, 811 of the frame unit 802, a rack gear 831 arranged parallel to the rail 830, a linear guide 832 fitted onto a part of the rail 830 and moving while sliding, a pinion gear unit 833 connected to the linear guide 832 and meshing with the rack gear 831, a motor 834 with a reducer 836 that rotates and drives the pinion gear unit 833, and a rotary encoder 835 for detecting the printing point position.

[0152] By driving the motor 834 (forward or reverse), the discharge unit 1 is moved rightward or leftward along the movable unit 813. The drive section 803 functions as a drive mechanism for the X direction of the discharge unit 1. Limit switches 837a and 837b are attached to both sides of the housing of the reducer 836.

[0153] The discharge unit 1 includes a plurality of heads 2 that discharge liquid of each color, for example, black, cyan, magenta, yellow, and white, or a head 2 that has a plurality of nozzle rows. The liquid of each color is supplied under pressure from a tank 330 to each head 2 or each nozzle row of the head 2 of the discharge unit 1, in the same manner as the liquid supply system described above.

[0154] In this liquid discharging device 1, the movable unit 813 is moved in the Y direction, and the discharging unit 1 is moved in the X direction, thereby drawing (printing) a desired image on the drawing target 100.

[0155] At this time, the moving distance of the discharge unit 1 (head 2) becomes longer, but the discharge unit 1 is provided with a wiping member 501, and can clean the nozzle surface 202a of the head 2 at any time.

[0156] This allows for continuous high-quality printing with minimal downtime.

[0157] Furthermore, the "liquid ejecting device" in the present invention includes a device that is equipped with a head, a head module, or a liquid ejection unit and ejects liquid by driving a liquid ejection head. The liquid ejecting device includes not only a device that can eject liquid onto an object onto which the liquid can adhere, but also a device that ejects liquid into air or liquid.

[0158] This "liquid ejecting device" can also include means for feeding, transporting, and discharging items onto which liquid can be attached, as well as pre-processing devices and post-processing devices.

[0159] For example, examples of "liquid ejecting devices" include image forming devices that eject ink to form images on paper, and three-dimensional modeling devices (three-dimensional modeling devices) that eject modeling liquid onto a powder layer formed from layers of powder in order to create a three-dimensional object (a three-dimensional model).

[0160] Furthermore, the term "liquid ejection device" is not limited to devices that use ejected liquid to visualize meaningful images such as letters and figures. For example, it also includes devices that form patterns that have no meaning in themselves, and devices that create three-dimensional images.

[0161] The above-mentioned "object onto which a liquid can adhere" means an object onto which a liquid can adhere at least temporarily, an object onto which the liquid can adhere and stick, an object onto which the liquid can penetrate, etc. Specific examples include media such as paper, recording paper, film, and cloth, electronic circuit boards, electronic components such as piezoelectric elements, powder layers, organ models, and test cells, and unless otherwise specified, includes all objects onto which a liquid can adhere.

[0162] The material of the "substance to which a liquid can adhere" may be any material to which a liquid can adhere, even temporarily, such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, or ceramics.

[0163] Furthermore, the "liquid ejection device" may be a device in which a liquid ejection head and an object onto which liquid can be attached move relatively, but is not limited to this. Specific examples include a serial type device in which a liquid ejection head moves, and a line type device in which a liquid ejection head does not move.

[0164] Other examples of "liquid ejecting devices" include a treatment liquid application device that ejects a treatment liquid onto paper to apply the treatment liquid to the surface of the paper for purposes such as modifying the surface of the paper, and an injection granulation device that ejects a composition liquid in which raw materials are dispersed through a nozzle to granulate fine particles of the raw materials.

[0165] The liquid to be ejected may have any viscosity and surface tension that allows it to be ejected from the head, but is not particularly limited thereto. Preferably, the viscosity of the ejected liquid is 30 mPa·s or less at room temperature and pressure, or upon heating or cooling. More specifically, the liquid may be a solution, suspension, emulsion, or the like containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a polymerizable compound, a resin, a surfactant, or the like, a biocompatible material such as DNA, amino acids, proteins, or calcium, or an edible material such as a natural colorant. These liquids can be used, for example, as inkjet inks, surface treatment liquids, liquids for forming components of electronic devices or light-emitting elements, or resist patterns for electronic circuits, and liquid materials for 3D modeling.

[0166] Energy sources for ejecting liquid include piezoelectric actuators (laminated piezoelectric elements and thin-film piezoelectric elements), thermal actuators that use electrothermal conversion elements such as heating resistors, and electrostatic actuators consisting of a vibration plate and an opposing electrode. [Explanation of symbols]

[0167] 1 Discharge unit 2 heads 2W white head (first head) 2C color head (second head) 2X processing liquid head (3rd head) 311W White ink (first liquid) 311C Color Ink (Second Liquid) 311X Processing Liquid (Third Liquid) 330 Tank 330W1, 330W2 White Tank (1st Tank) 330C Color Tank (3rd Tank) 330X Processing liquid tank (4th tank) 331 First Pressure Source 332a, 332b Second pressure source 333 Third Pressure Source 340 Buffer Tank (Second Tank) 350C 5th valve 350H First valve 350L Third Valve 350X 6th Valve 360W1, 360W2 4th valve 370W1, 370W2 Second valve 1000 Liquid discharging device

Claims

1. a first pressure source that generates a first pressure; one or more second pressure sources generating a second pressure less than the first pressure; a third pressure source that generates a third pressure that is lower than the second pressure; at least two first tanks communicating with the second pressure source and supplying a first liquid to the first head; a second tank communicating with the first pressure source and the third pressure source and communicating with the two first tanks; a first valve that opens and closes a path connecting the first pressure source and the second tank; second valves for opening and closing each of the liquid paths between the two first tanks and the head; a third valve that opens and closes a path connecting the third pressure source and the second tank; a fourth valve for opening and closing each of the liquid paths between the second tank and the two first tanks, controlling opening and closing of the first valve, the second valve, the third valve, and the fourth valve to move the first liquid between the first tank and the second tank by a pressure difference between the first pressure and the third pressure and the second pressure; The first pressure generated by the first pressure source, the second pressure generated by the second pressure source, and the third pressure generated by the third pressure source are all positive pressures. A liquid ejection device comprising:

2. The first pressure source, the second pressure source, and the third pressure source generate the first pressure, the second pressure, and the third pressure, respectively, from compressed air supplied from a common compressor.

2. The liquid ejection device according to claim 1.

3. A first pressure source that generates a first pressure; one or more second pressure sources generating a second pressure less than the first pressure; a third pressure source that generates a third pressure that is lower than the second pressure; at least two first tanks communicating with the second pressure source and containing a first liquid to be supplied to the first head; a second tank communicating with the first pressure source and the third pressure source and communicating with the two first tanks; a first valve that opens and closes a path connecting the first pressure source and the second tank; second valves for opening and closing each of the liquid paths between the two first tanks and the head; a third valve that opens and closes a path connecting the third pressure source and the second tank; a fourth valve for opening and closing each of the liquid paths between the second tank and the two first tanks, controlling opening and closing of the first valve, the second valve, the third valve, and the fourth valve to move the first liquid between the first tank and the second tank by a pressure difference between the first pressure and the third pressure and the second pressure; a third tank communicating with the first pressure source and containing a second liquid to be supplied to the second head; a fifth valve that opens and closes a path connecting the first pressure source and the third tank; When the first liquid is transferred from the second tank to the first tank, the first valve and the fifth valve are alternately opened and closed. A liquid ejection device comprising:

4. A first pressure source that generates a first pressure; one or more second pressure sources generating a second pressure less than the first pressure; a third pressure source that generates a third pressure that is lower than the second pressure; at least two first tanks communicating with the second pressure source and containing a first liquid to be supplied to the first head; a second tank communicating with the first pressure source and the third pressure source and communicating with the two first tanks; a first valve that opens and closes a path connecting the first pressure source and the second tank; second valves for opening and closing each of the liquid paths between the two first tanks and the head; a third valve that opens and closes a path connecting the third pressure source and the second tank; a fourth valve for opening and closing each of the liquid paths between the second tank and the two first tanks, controlling opening and closing of the first valve, the second valve, the third valve, and the fourth valve to move the first liquid between the first tank and the second tank by a pressure difference between the first pressure and the third pressure and the second pressure; a fourth tank that contains a third liquid to be supplied to the third head; The fourth tank communicates with the third pressure source. A liquid ejection device comprising:

5. A means for detecting the liquid levels of the first tank and the second tank is provided.

5. The liquid ejection device according to claim 1, wherein the liquid ejection device is a liquid ejection device.

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