Printer, control method, and control program

Abstract

To provide a printer, a control method and a control program, each contributing to suppression of intrusion of holding liquid into a storage portion.SOLUTION: A printer comprises: a first storage portion that stores first ejection liquid; a first flow passage connecting the first storage portion to a first nozzle; a first valve provided in the first flow passage; a second storage portion storing second ejection liquid; a second flow passage connecting the second storage portion to a second nozzle; a second valve provided in the second flow passage; a cap that surrounds the first nozzle and the second nozzle and comes in contact with a nozzle surface, thereby forming a holding space between the nozzle surface and the cap and holding liquid in the holding space; and a control portion. In a holding state in which the cap holds the holding liquid in the holding space, the control portion performs control in such a manner that either or both of the first valve and the second valve are closed when the liquid is not circulated (S612).SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to a printer, a control method, and a control program. [Background technology]

[0002] The liquid ejection device described in Patent Document 1 includes an ejection head, a storage container, and a cap. The ejection head ejects ejection liquid from each of a plurality of nozzles. The storage container stores the ejection liquid and is connected to each of the plurality of nozzles. The cap surrounds the plurality of nozzles to form a holding space and holds the retained liquid in the holding space. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-88699 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the liquid ejection device, a first storage section connected to one of the nozzles and a second storage section connected to another of the nozzles may be provided as the storage container. In this case, when the retained liquid is retained in the retaining space, the first storage section and the second storage section are connected to each other via the retaining space so that the liquid can move. Therefore, when a pressure difference occurs between the first storage section and the second storage section, there is a possibility that the retained liquid will enter the storage section with the lower pressure from the nozzle.

[0005] An object of the present invention is to provide a printer, a control method, and a control program that contribute to suppressing the intrusion of the retained liquid into the storage section. [Means for solving the problem]

[0006] A printer according to a first aspect of the present invention is a printer having a first nozzle and a second nozzle provided on a nozzle surface, a first liquid being ejected from the first nozzle and a second liquid being ejected from the second nozzle, the printer including a first reservoir for storing the first liquid, a flow path for the first liquid, the first flow path connecting the first reservoir and the first nozzle, a first valve provided in the first flow path, a second reservoir for storing the second liquid, a flow path for the second liquid, the second flow path connecting the second reservoir and the second nozzle, a second valve provided in the second flow path, and a valve connecting the first nozzle and the second nozzle. the nozzle face and surrounding the nozzle, contacting the nozzle face to form a retention space between the nozzle face and the cap, and retaining a retention liquid, which is the first ejection liquid, the second ejection liquid, or a cleaning liquid, in the retention space; and a control unit, wherein the control unit controls one or both of the first valve and the second valve to a closed state when the cap is in a retention state in which it retains the retention liquid in the retention space and is in a non-circulation state which is neither a first circulation state in which the first ejection liquid circulates via the first flow path nor a second circulation state in which the second ejection liquid circulates via the second flow path.

[0007] According to the first aspect, when the printer is in the retention state and the non-circulation state, one or both of the first valve and the second valve are controlled to be in a closed state. Therefore, even if there is a pressure difference between the first storage portion and the second storage portion, the pressure difference between the first storage portion and the second storage portion is unlikely to affect the pressure difference between the first nozzle and the second nozzle. Therefore, the printer contributes to reducing the possibility of the retained liquid entering the first storage portion and the second storage portion.

[0008] In the printer, when in the holding state and the non-circulation state, the control unit may switch between a first valve state in which the first valve is closed and the second valve is open, and a second valve state in which the first valve is open and the second valve is closed.

[0009] In this case, the heat generated by one of the first valve and the second valve is prevented from continuing for a long period of time compared to when the first valve state or the second valve state is not switched, which contributes to reducing the effect of heat generated by the first valve or the second valve on the ejected liquid.

[0010] In the printer, the first storage portion and the second storage portion may each be a cartridge, and the first valve and the second valve may each be either a diaphragm valve or a tube valve, and the control portion may maintain the first valve state when it detects that at least one of the connection between the first storage portion and the first flow path and the connection between the second storage portion and the second flow path has been released in the holding state, the non-circulation state, and the first valve state, and may maintain the second valve state when it detects that at least one of the connection between the first storage portion and the first flow path and the connection between the second storage portion and the second flow path has been released in the holding state, the non-circulation state, and the second valve state.

[0011] If the first valve state and the second valve state are switched in a state where at least one of the connections between the first reservoir and the first flow path and the second reservoir and the second flow path is disconnected, the pressure change in the first flow path or the second flow path caused by the switching may cause the ejection liquid to overflow from the first flow path or the second flow path or air to enter the first flow path or the second flow path. In the printer, when at least one of the connections between the first reservoir and the first flow path and the second reservoir and the second flow path is disconnected, the printer does not switch from one of the first valve state and the second valve state to the other. Thus, the printer contributes to suppressing the ejection liquid from overflowing from the first flow path or the second flow path or the air from entering the first flow path or the second flow path.

[0012] The printer may include a first sensor that detects a first remaining amount of the first ejection liquid stored in the first storage section, and a second sensor that detects a second remaining amount of the second ejection liquid stored in the second storage section, the first valve and the second valve each being open in a non-energized state and closed in a powered state, and the control unit may control one or both of the first valve and the second valve to a closed state when a difference between the first remaining amount detected by the first sensor and the second remaining amount detected by the second sensor exceeds a predetermined threshold value in the holding state and the non-circulation state, and may control both of the first valve and the second valve to an open state when a difference between the first remaining amount detected by the first sensor and the second remaining amount detected by the second sensor is less than the predetermined threshold value in the holding state and the non-circulation state.

[0013] When the difference between the first remaining amount and the second remaining amount is less than a predetermined threshold, the pressure difference between the first storage portion and the second storage portion is smaller than when the difference between the first remaining amount and the second remaining amount exceeds a predetermined threshold. When the pressure difference between the first storage portion and the second storage portion is relatively large, the possibility that the retained liquid will infiltrate into the first storage portion and the second storage portion is relatively high. In this case, the printer energizes one or both of the first valve and the second valve. This contributes to reducing the possibility that the retained liquid will infiltrate into the first storage portion and the second storage portion. On the other hand, when the pressure difference between the first storage portion and the second storage portion is relatively small, the possibility that the retained liquid will infiltrate into the first storage portion and the second storage portion is relatively low. In this case, the printer does not energize the first valve and the second valve. This contributes to power saving in the printer. That is, the printer contributes to reducing the possibility that the retained liquid will infiltrate into the first storage portion and the second storage portion while contributing to power saving.

[0014] In the printer, the first valve has a self-holding mechanism that closes when current is applied and maintains the closed state when current is stopped in the closed state, and the control unit may stop the application of current to the first valve when the first valve is in the closed state when the printer is in the held state and in the non-circulation state.

[0015] In this case, when the first valve is closed and power supply to the first valve is stopped, the self-holding mechanism keeps the first valve closed, thereby contributing to power saving in the printer and reducing the possibility of retained liquid entering the first and second storage sections.

[0016] In the printer, the control unit may control the cap to the held state with both the first valve and the second valve open, and after the cap has entered the held state, when the cap is in the non-circulation state, close one or both of the first valve and the second valve.

[0017] If one or both of the first valve and the second valve are closed before the cap is controlled to the holding state, the meniscus formed in each of the first nozzle and the second nozzle may be destroyed, and air may enter the first flow path from the first nozzle, or air may enter the second flow path from the second nozzle. In the printer, one or both of the first valve and the second valve are closed after the cap is in the holding state. Thus, the printer contributes to suppressing the meniscus formed in each of the first nozzle and the second nozzle from being destroyed and air from entering the first flow path and the second flow path.

[0018] The printer includes a flow path for the first ejection liquid, the flow path for the first ejection liquid including a third flow path connecting the first storage unit and the first nozzle, a third valve provided in the third flow path, a fourth flow path for the second ejection liquid, the flow path for the second ejection liquid connecting the second storage unit and the second nozzle, a fourth valve provided in the fourth flow path, a first pump that circulates the first ejection liquid through each of the first flow path and the third flow path, and a second pump that circulates the second ejection liquid through each of the second flow path and the fourth flow path, and the control unit controls the flow path when both the first valve and the third valve are open. One pump may be driven and controlled to the first circulation state in which the first discharge liquid circulates through each of the first flow path and the third flow path, and when the liquid is in the holding state and in the first circulation state, both the second valve and the fourth valve may be controlled to a closed state, and the second pump may be driven in a state in which both the second valve and the fourth valve are open and controlled to the second circulation state in which the second discharge liquid circulates through each of the second flow path and the fourth flow path, and when the liquid is in the holding state and in the second circulation state, both the first valve and the third valve may be controlled to a closed state.

[0019] When the printer is in the holding state and in the first circulation state or the second circulation state, one or both of the first valve and the second valve are controlled to be closed. Thus, the printer contributes to suppressing the possibility of the retained liquid entering the first storage portion and the second storage portion not only in the non-circulation state but also in the first circulation state and the second circulation state.

[0020] A control method according to a second aspect of the present invention is a control method for a printer having a nozzle surface provided with a first nozzle and a second nozzle, a first liquid being ejected from the first nozzle and a second liquid being ejected from the second nozzle, the printer including a first reservoir for storing the first liquid, a first flow path for the first liquid connecting the first reservoir and the first nozzle, a first valve provided in the first flow path, a second reservoir for storing the second liquid, a second flow path for the second liquid connecting the second reservoir and the second nozzle, a second valve provided in the second flow path, and and a cap that surrounds the first nozzle and the second nozzle, contacts the nozzle face to form a holding space between the nozzle face, and holds a holding liquid, which is the first ejection liquid, the second ejection liquid, or a cleaning liquid, in the holding space, and the control method is characterized in that when the cap is in a holding state in which it holds the holding liquid in the holding space, and is in a non-circulation state which is neither a first circulation state in which the first ejection liquid circulates via the first flow path, nor a second circulation state in which the second ejection liquid circulates via the second flow path, one or both of the first valve and the second valve are controlled to a closed state.

[0021] The second aspect, like the first aspect, contributes to suppressing the possibility of the retentate entering the first reservoir and the second reservoir.

[0022] A control program according to a third aspect of the present invention is a control program for causing a computer to execute processing to control a printer having a first nozzle and a second nozzle provided on a nozzle face, a first liquid being ejected from the first nozzle, and a second liquid being ejected from the second nozzle, the printer including: first reservoirs for storing the first liquid; a first flow path for the first liquid connecting the first reservoir and the first nozzle; a first valve provided in the first flow path; a second reservoir for storing the second liquid; a second flow path for the second liquid connecting the second reservoir and the second nozzle; and a second valve provided in the second flow path. and a cap that surrounds the first nozzle and the second nozzle, contacts the nozzle face to form a holding space between the nozzle face, and holds a holding liquid, which is the first ejection liquid, the second ejection liquid, or a cleaning liquid, in the holding space, and the control program causes the computer to execute a process of controlling one or both of the first valve and the second valve to a closed state when the cap is in a holding state in which it holds the holding liquid in the holding space and is in a non-circulation state which is neither a first circulation state in which the first ejection liquid circulates via the first flow path nor a second circulation state in which the second ejection liquid circulates via the second flow path.

[0023] The third aspect, like the first aspect, contributes to suppressing the possibility of the retentate entering the first reservoir and the second reservoir. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a perspective view of a printer 1. [Diagram 2] FIG. [Diagram 3] 3 is a cross-sectional view taken along the line III-III in FIG. 1. [Figure 4] FIG. 2 is a diagram showing the flow path configuration of the printer 1. [Diagram 5] 2 is a block diagram showing the electrical configuration of the printer 1. FIG. [Figure 6] 13 is a flowchart of a main process. [Figure 7] 13 is a flowchart of an end-of-day process. [Figure 8] 13 is a flowchart of a circulation process. [Figure 9] 13 is a flowchart of a first circulation process. [Figure 10] 10 is a flowchart of the first circulation process, continuing from FIG. 9. [Figure 11] 13 is a flowchart of a second circulation process. [Figure 12] 13 is a flowchart of a liquid contact release process. [Figure 13] 4 is a flowchart of a valve closing process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] A printer 1 according to an embodiment of the present invention will be described with reference to the drawings. The upper, lower, lower left, upper right, lower right, and upper left in Fig. 1 respectively correspond to the upper, lower, front, rear, right, and left of the printer 1. In this embodiment, the mechanical elements in the drawings are shown to actual scale.

[0026] The printer 1 shown in Fig. 1 is an inkjet printer that prints by ejecting ink onto a print medium. The print medium is fabric, paper, etc., such as a T-shirt. The printer 1 can print color images on the print medium using five colors of ink: white, black, yellow, cyan, and magenta.

[0027] In the following, the white ink of the five color inks will be referred to as "white ink". When referring to the four of the five color inks, black, cyan, yellow, and magenta, collectively or when none of them is specified, they will be referred to as "color ink". When referring to white ink and color inks collectively or when none of them is specified, they will simply be referred to as "ink". White ink is used in printing to represent the white part of an image or as a base for color inks. Color inks are ejected directly onto the printing medium or on top of a base of white ink, and are used to print color images.

[0028] The mechanical configuration of the printer 1 will be described with reference to FIGS. 1 to 3. As shown in FIG. 1, the printer 1 includes a frame 2, a platen 12, and a mounting unit 8. The frame 2 is configured in a lattice shape by a plurality of plates and a plurality of shafts extending in the front-rear, left-right, or up-down direction. An opening 13 is formed in the frame 2. The opening 13 is located in the center of the frame 2 in a front view, and extends rearward from the front end of the frame 2. The platen 12 is disposed within the opening 13 in a front view. The platen 12 is plate-shaped and extends in the front-rear, left-right, and up-down directions. A print medium is placed on the platen 12. The platen 12 is supported from below by a support portion 14. The support portion 14 is fixed to the frame 2 within the opening 13. The support portion 14 includes an axis and extends in the front-rear direction. The platen 12 moves in the front-rear direction along the support portion 14 by driving a sub-scanning motor 97 shown in FIG. 5. Therefore, in this embodiment, the front-rear direction is the sub-scanning direction.

[0029] A pair of guide shafts 21, 22 are fixed to the upper end of the frame body 2. The guide shaft 21 is located at the front end of the frame body 2, and extends in the left-right direction from the left end to the right end of the frame body 2. The guide shaft 22 is located approximately in the center of the frame body 2 in the front-to-rear direction, and is located rearward of the guide shaft 21. The guide shaft 22 extends in the left-right direction from the left end to the right end of the frame body 2. The guide shafts 21, 22 support the carriage 6. The carriage 6 is plate-shaped and extends in the front-to-rear and left-right directions. The carriage 6 extends from the guide shaft 21 to the guide shaft 22.

[0030] A drive belt 98 is connected to the carriage 6. The drive belt 98 is provided on the guide shaft 21 and extends in the left-right direction. The drive belt 98 is connected to a main scanning motor 99. The main scanning motor 99 is provided at the right end of the guide shaft 21. When the main scanning motor 99 is driven, the drive belt 98 moves the carriage 6 in the left-right direction along the guide shafts 21 and 22. Therefore, in this embodiment, the left-right direction is the main scanning direction. Figures 1 and 3 show a state in which the carriage 6 is located at the left end of its movement range. Heads 31 and 32 are provided on the carriage 6. Head 31 is located at the rear of the carriage 6 and ejects white ink. Head 32 is aligned forward of head 31 and ejects color inks.

[0031] The mounting section 8 is box-shaped and opens forward, and is fixed to the right surface of the frame 2. A plurality of ink cartridges 23, 24, 25, 26, 27, 28 are mounted in the mounting section 8. The ink cartridges 23 to 28 are each a container that is replaceable with respect to the mounting section 8. The ink cartridge 23 stores white ink 36 (see FIG. 4) to be supplied to the head 31. The ink cartridge 24 stores white ink 37 (see FIG. 4) to be supplied to the head 31. The ink cartridges 25 to 28 store black, cyan, yellow, and magenta inks (not shown) to be supplied to the head 32, respectively.

[0032] According to the above configuration, the heads 31, 32 move in the left-right direction together with the carriage 6. The area where the movement path of the platen 12 in the left-right direction and the movement path of the heads 31, 32 in the front-rear direction overlap each other in the vertical direction is called the "printing area 18." The area of ​​the movement paths of the heads 31, 32 to the left of the movement path of the platen 12 is called the "non-printing area 19." When the heads 31, 32 and the platen 12 are located in the printing area 18, the platen 12 and the heads 31, 32 face each other in the vertical direction.

[0033] In the printing area 18, the printer 1 moves the platen 12 in the front-to-back direction (sub-scanning direction) by driving the sub-scanning motor 97 shown in Figure 5, and moves the carriage 6 in the left-to-right direction (main scanning direction) by driving the main scanning motor 99, thereby transporting the printing medium in the front-to-back and left-to-right directions relative to the heads 31, 32.

[0034] The operation of moving the carriage 6 in the left-right direction while ejecting white ink from the head 31 or ejecting color inks from the head 32 is called an "ejection scan." The printer 1 prints on the print medium by repeating the ejection scan and the movement of the platen 12 in the front-to-back direction. For example, the printer 1 ejects white ink from the head 31 during the ejection scan to form a base on the print medium. The printer 1 ejects color inks from the head 32 during the ejection scan to print a color image on the base formed on the print medium.

[0035] As shown in FIG. 2, the head 31 has a rectangular parallelepiped shape. A nozzle surface 311 is provided on the bottom surface of the head 31. The nozzle surface 311 is planar and extends in the front-rear and left-right directions. The nozzle surface 311 is located above the platen 12 shown in FIG. 1 and is exposed downward from an opening provided in the carriage 6 shown in FIG. 1. A plurality of nozzles 313 are provided on the nozzle surface 311. The plurality of nozzles 313 are openings and eject ink downward. The plurality of nozzles 313 are arranged in a plurality of rows in the left-right direction, with one row of nozzles arranged in the front-rear direction. The plurality of nozzles 313 are divided into nozzle groups W1, W2, W3, and W4. The nozzle groups W1, W2, W3, and W4 are arranged in the order of the nozzle groups W1, W2, W3, and W4 from left to right.

[0036] The nozzle group W1 is a row of multiple nozzles to which the ink cartridge 23 is connected via a flow path 52 (see FIG. 4) described later. The nozzle group W2 is a row of multiple nozzles to which the ink cartridge 23 is connected via a flow path 53 (see FIG. 4) described later. Therefore, the nozzle group W1 and the nozzle group W2 each eject the white ink 36 supplied from the ink cartridge 23. The nozzle group W3 is a row of multiple nozzles to which the ink cartridge 24 is connected via a flow path 62 (see FIG. 4) described later. The nozzle group W4 is a row of multiple nozzles to which the ink cartridge 24 is connected via a flow path 63 (see FIG. 4) described later. Therefore, the nozzle group W3 and the nozzle group W4 each eject the white ink 37 supplied from the ink cartridge 24.

[0037] 3 and 4 are provided inside the head 31. The communicating paths 314, 315 are each formed by a wall inside the head 31. For example, the communicating paths 314, 315 are each formed by forming a groove in a layer above the nozzle surface 311 among the laminated plates that form the nozzle surface 311.

[0038] One end of the communication path 314 is connected to the nozzle group W1. The other end of the communication path 314 is connected to the nozzle group W2. As a result, the nozzle group W1 and the nozzle group W2 are connected to each other via the communication path 314. One end of the communication path 315 is connected to the nozzle group W3. The other end of the communication path 315 is connected to the nozzle group W4. As a result, the nozzle group W3 and the nozzle group W4 are connected to each other via the communication path 315.

[0039] The communication passage 314 may be a flow path connecting a first common pressure chamber connected to the nozzle group W1 and a first common pressure chamber connected to the nozzle group W2. That is, the communication passage 314 may connect the nozzle group W1 and the nozzle group W2 to each other via the first common pressure chamber. The communication passage 315 may be a flow path connecting a second common pressure chamber connected to the nozzle group W3 and a second common pressure chamber connected to the nozzle group W4. That is, the communication passage 315 may connect the nozzle group W3 and the nozzle group W4 to each other via the second common pressure chamber.

[0040] Although not shown, a nozzle surface is provided on the bottom surface of the head 32, and multiple nozzles are provided on the nozzle surface, similar to the configuration of the head 31. The head 32 ejects color inks downward from the multiple nozzles. Note that the head 32 does not need to be provided with communication paths for connecting the nozzle groups that eject color inks of different colors to each other.

[0041] As shown in FIG. 3, the printer 1 includes a capping mechanism 4. The capping mechanism 4 is provided in the non-printing area 19 (see FIG. 1). The capping mechanism 4 includes a cap support part 47, a cap 41, and another cap (not shown). The cap support part 47 is plate-shaped and extends in the front-rear and left-right directions. The cap support part 47 moves in the up-down direction by being driven by a cap motor 48 shown in FIG. 5. The cap 41 and the other cap are fixed to the upper surface of the cap support part 47. The cap 41 and the other cap are located at the same positions as the heads 31, 32 in the front-rear direction, respectively. The cap 41 and the other cap are made of an elastic body such as rubber, and open upward.

[0042] According to the above configuration, when the carriage 6 is located at the left end of its movement range, the nozzle surface 311 of the head 31 and the nozzle surface of the head 32 are disposed above the cap 41 and the other cap, respectively, in the non-printing region 19, and face the cap 41 and the other cap in the vertical direction. The position of the carriage 6 when the nozzle surface 311 of the head 31 and the nozzle surface of the head 32 face the cap 41 and the other cap in the vertical direction, respectively, is referred to as the "cap position."

[0043] When the cap support part 47 moves upward with the carriage 6 in the cap position, the cap 41 surrounds all of the nozzle groups W1, W2, W3, and W4 in the head 31 and comes into contact with the nozzle surface 311 from below. This forms a holding space 42 between the cap 41 and the nozzle surface 311. The holding space 42 is a space surrounded by the cap 41 and the nozzle surface 311. Hereinafter, the state in which the cap 41 comes into contact with the nozzle surface 311 in the head 31 from below to form the holding space 42 is referred to as the "capping state" (see Figures 3 and 4). The state in which the cap 41 is separated downward from the nozzle surface 311 in the head 31 is referred to as the "uncapping state" (see Figure 2).

[0044] The printer 1 places the cap 41 in a capping state to prevent the ink in the head 31 from drying while printing is not being performed. In the capping state of this embodiment, the cap 41 contacts the nozzle surface 311 to an extent that the pressure difference between the inside (holding space 42) of the cap 41 and the outside (atmosphere) can be maintained. For example, when all of the multiple nozzles 313 are blocked from the atmosphere, the holding space 42 becomes a sealed space surrounded by the cap 41 and the nozzle surface 311. The holding space 42 is a space for holding the holding liquid 35 shown in FIG. 4. The holding liquid 35 is composed of at least one of the white inks 36 and 37 and the cleaning liquid 38 shown in FIG. 4. Hereinafter, the state in which the cap 41 holds the holding liquid 35 in the holding space 42 is referred to as a "holding state." When the holding space 42 is filled with the holding liquid 35, the holding liquid 35 contacts the nozzle surface 311. In the holding state, the state in which the holding space 42 is filled with the holding liquid 35 and the holding liquid 35 is in contact with the nozzle surface 311 is referred to as a "liquid contact state."

[0045] Similar to the cap 41, when the cap support part 47 moves upward with the carriage 6 located at the cap position, the other cap comes into contact from below with the nozzle surface of the head 32. A holding space (not shown) is formed between the other cap and the nozzle surface of the head 32.

[0046] The flow path configuration of the printer 1 will be described with reference to FIG. 4. In this embodiment, each flow path is formed of a tube and has flexibility. The printer 1 has flow paths 50 and 60. The flow path 50 is a flow path for white ink 36, and connects the ink cartridge 23 to each of the nozzle groups W1 and W2. The flow path 60 is a flow path for white ink 37, and connects the ink cartridge 24 to each of the nozzle groups W3 and W4. Although not shown, sub-tanks may be provided in the flow paths 50 and 60 as intermediate buffers for the white inks 36 and 37, respectively.

[0047] The flow path 50 includes flow paths 51, 52, 53, 54, and 55. A connection port 511 is provided at one end of the flow path 51. The connection port 511 is disposed within the mounting portion 8 shown in FIG. 1. When the ink cartridge 23 is mounted in the mounting portion 8, the ink cartridge 23 is connected to the connection port 511. Hereinafter, when the ink cartridge 23 is connected to the flow path 51 via the connection port 511, it is said that "the ink cartridge 23 is in a connected state." The flow path 51 extends from the connection port 511 (ink cartridge 23) to point P11, and connects to each of the flow paths 52 and 53 at point P11. That is, the flow path 51 branches into the flow path 52 and the flow path 53 at point P11.

[0048] The flow path 52 extends from the point P11 to the nozzle group W1 and connects to the nozzle group W1. Thus, the flow path 52 connects the ink cartridge 23 and the nozzle group W1 to each other via the flow path 51. The flow path 53 extends from the point P11 to the nozzle group W2 and connects to the nozzle group W2. Thus, the flow path 53 connects the ink cartridge 23 and the nozzle group W2 to each other via the flow path 51. The point P12 is located between the point P11 and the nozzle group W1. The point P13 is located between the point P11 and the nozzle group W2. The flow path 54 extends from the point P12 to the point P13, connects to the flow path 52 at the point P12, and connects to the flow path 53 at the point P13. The point P14 is located between the point P12 and the nozzle group W1. The point P15 is located between the point P13 and the nozzle group W2. Flow path 55 extends from point P14 to point P15, connects to flow path 52 at point P14, and connects to flow path 53 at point P15.

[0049] A valve 521 and a filter 522 are provided in the flow path 52. The valve 521 and the filter 522 are located between the point P11 and the point P12. In this embodiment, the valve 521 and the filter 522 are arranged in this order from the point P11 to the point P12.

[0050] When the valve 521 is closed, the flow path 52 is blocked between the points P11 and P12. When the valve 521 is open, the flow path 52 is connected between the points P11 and P12. The valve 521 is not limited to a specific type, but may be, for example, a diaphragm valve that opens and closes the flow path using an elastic diaphragm, or a tube valve that opens and closes the flow path by squeezing a tube. Note that the types of valves 531, 551, 621, 631, and valve 651 described below may be different from the valve 521, but are the same as the valve 521 in this embodiment. The filter 522 filters the white ink 36 that passes through the filter 522. The filter 522 is not limited to a specific type, but may be, for example, a nonwoven fabric, a woven fabric, a resin film, or a porous metal piece. Note that the types of filters 532, 542, 622, 632, and 642 described below may be different from the filter 522, but are the same as the filter 522 in this embodiment.

[0051] A valve 531 and a filter 532 are provided in the flow path 53. The valve 531 and the filter 532 are located between the point P11 and the point P13. In this embodiment, the valve 531 and the filter 532 are arranged in this order from the point P11 toward the point P13. When the valve 531 is closed, the flow path 53 is blocked between the point P11 and the point P13. When the valve 531 is open, the flow path 53 is connected between the point P11 and the point P13. The filter 532 filters the white ink 36 passing through the filter 532.

[0052] A pump 541 and a filter 542 are provided in the flow path 54. In this embodiment, the pump 541 and the filter 542 are arranged in this order from point P13 toward point P12. The pump 541 sends the white ink 36 from point P13 toward point P12 when driven. The filter 542 filters the white ink 36 passing through the filter 542. A valve 551 is provided in the flow path 55. When the valve 551 is closed, the flow path 55 is blocked. When the valve 551 is open, the flow path 55 is connected.

[0053] The configuration of the flow path 60 differs from the flow path 50 in that the connection destination is the ink cartridge 24 and the nozzle groups W3 and W4 instead of the ink cartridge 23 and the nozzle groups W1 and W2. The flow path 60 includes flow paths 61, 62, 63, 64, and 65. A connection port 611 is provided at one end of the flow path 61. The connection port 611 is disposed in the mounting portion 8 shown in FIG. 1. When the ink cartridge 24 is mounted in the mounting portion 8, the ink cartridge 24 is connected to the connection port 611. In the following, when the ink cartridge 24 is connected to the flow path 61 via the connection port 611, it is said that the ink cartridge 23 is in a connected state. The flow path 61 extends from the connection port 611 (ink cartridge 24) to point P21 and connects to each of the flow paths 62 and 63 at point P21. That is, the flow path 61 branches into the flow path 62 and the flow path 63 at point P21.

[0054] The flow path 62 extends from the point P21 to the nozzle group W3 and connects to the nozzle group W3. Thus, the flow path 62 connects the ink cartridge 24 and the nozzle group W3 to each other via the flow path 61. The flow path 63 extends from the point P21 to the nozzle group W4 and connects to the nozzle group W4. Thus, the flow path 63 connects the ink cartridge 24 and the nozzle group W4 to each other via the flow path 61. The point P22 is located between the point P21 and the nozzle group W3. The point P23 is located between the point P21 and the nozzle group W4. The flow path 64 extends from the point P22 to the point P23, connects to the flow path 62 at the point P22, and connects to the flow path 63 at the point P23. The point P24 is located between the point P22 and the nozzle group W3. The point P25 is located between the point P23 and the nozzle group W4. Flow path 65 extends from point P24 to point P25, connects to flow path 62 at point P24, and connects to flow path 63 at point P25.

[0055] A valve 621 and a filter 622 are provided in the flow path 62. The valve 621 and the filter 622 are located between points P21 and P22. In this embodiment, the valve 621 and the filter 622 are arranged in this order from point P21 toward point P22. When the valve 621 is closed, it blocks the flow path 62 between points P21 and P22. When the valve 621 is open, it connects the flow path 62 between points P21 and P22. The filter 622 filters the white ink 37 passing through the filter 622.

[0056] A valve 631 and a filter 632 are provided in the flow path 63. The valve 631 and the filter 632 are located between points P21 and P23. In this embodiment, the valve 631 and the filter 632 are arranged in this order from point P21 to point P23. When the valve 631 is closed, it blocks the flow path 63 between points P21 and P23. When the valve 631 is open, it connects the flow path 63 between points P21 and P23. The filter 632 filters the white ink passing through the filter 632.

[0057] A pump 641 and a filter 642 are provided in the flow path 64. In this embodiment, the pump 641 and the filter 642 are arranged in the order of the pump 641 and the filter 642 from point P23 to point P22. The pump 641 is driven to send the white ink 37 from point P23 to point P22. The filter 642 filters the white ink 37 passing through the filter 642. A valve 651 is provided in the flow path 65. When the valve 651 is closed, it blocks the flow path 65. When the valve 651 is open, it opens the flow path 65.

[0058] According to the above configuration, for example, during printing, the pair of valves 521 and 531 in the flow path 50 is in an open state, and the driving of the pump 541 is stopped. In this case, the white ink 36 flows from the ink cartridge 23 to the flow path 51 due to the external pressure acting on the ink cartridge 23. The white ink 36 branches into the flow path 51 and the flow path 52 at point P11, flows toward the nozzle group W1 through the flow path 52, and flows toward the nozzle group W2 through the flow path 53. During printing, the pair of valves 621 and 631 in the flow path 60 is in an open state, and the driving of the pump 641 is stopped. In this case, the white ink 37 flows from the ink cartridge 24 to the flow path 61 due to the external pressure acting on the ink cartridge 24. The white ink 37 branches into the flow path 62 and the flow path 63 at point P21, flows toward the nozzle group W3 through the flow path 62, and flows toward the nozzle group W4 through the flow path 63.

[0059] The printer 1 includes a cleaning liquid tank 70 and flow paths 71 and 72. The cleaning liquid tank 70 is a container that stores the cleaning liquid 38 for cleaning the nozzle surface 311 and the like. One end of the flow path 71 is connected to the cleaning liquid tank 70. The other end of the flow path 71 is connected to the cap 41 (retaining space 42). As a result, the flow path 71 connects the cleaning liquid tank 70 and the cap 41 (retaining space 42) to each other. A valve 711 is provided in the flow path 71. The valve 711 is located between point P31 and the other end (cap 41) of the flow path 71. When the valve 711 is closed, the flow path 71 is blocked between point P31 and the other end (cap 41) of the flow path 71. When the valve 711 is open, the flow path 71 is connected between point P31 and the other end (cap 41) of the flow path 71. One end of the flow path 72 is connected to the flow path 71 at point P31. The other end of the flow path 72 is open to the atmosphere 73. A valve 721 is provided in the flow path 72. When the valve 721 is closed, the flow path 72 is blocked. When the valve 721 is open, the flow path 72 is connected.

[0060] The printer 1 includes a waste liquid tank 90 and a flow path 91. The waste liquid tank 90 is a container for receiving the retained liquid 35 discharged from the holding space 42, i.e., the waste liquid 39. One end of the flow path 91 is connected to the cap 41 (holding space 42). The other end of the flow path 91 is connected to the waste liquid tank 90. ​​As a result, the flow path 91 connects the waste liquid tank 90 and the cap 41 (holding space 42) to each other. A valve 911 and a pump 912 are provided in the flow path 91. The valve 911 and the pump 912 are arranged in this order from the cap 41 toward the waste liquid tank 90. ​​When the valve 911 is closed, the flow path 91 is blocked. When the valve 911 is open, the flow path 91 is communicated. When the pump 912 is driven, it sucks the retained liquid 35 or air from the holding space 42 and sends the sucked retained liquid 35 or air to the waste liquid tank 90 via the flow path 91.

[0061] The electrical configuration of the printer 1 will be described with reference to FIG. 5. The printer 1 includes a control board 80. The control board 80 is provided with a CPU 81, a ROM 82, a RAM 83, and a flash memory 84. The CPU 81 controls the printer 1 and is electrically connected to the ROM 82, the RAM 83, and the flash memory 84. The ROM 82 stores a control program for the CPU 81 to control the operation of the printer 1, and information required by the CPU 81 when executing various programs. The control program includes a main program for executing a main process (see FIG. 6) described below, and a closing process program for executing a valve closing process (see FIG. 13) described below. The RAM 83 temporarily stores various data used in the control program. The flash memory 84 is non-volatile, and stores print data for printing, etc.

[0062] The CPU 81 is electrically connected to the main scanning motor 99, the sub-scanning motor 97, the cap motor 48, the head driving unit 301, the solenoids 152, 153, 155, 162, 163, 165, 171, 172, 191, the pump motors 254, 264, 291, the remaining amount sensors 231, 241, the connection sensors 232, 242, and the operation unit 17. The main scanning motor 99, the sub-scanning motor 97, the cap motor 48, the head driving unit 301, the solenoids 152, 153, 155, 162, 163, 165, 171, 172, 191, and the pump motors 254, 264, 291 are driven under the control of the CPU 81.

[0063] The head driving unit 301 is configured, for example, by a piezoelectric element or a heating element, and is provided for each of the multiple nozzles 313 (see FIG. 2) in the head 31. When driven, the head driving unit 301 causes the head 31 to selectively eject white ink from the multiple nozzles 313. Although not shown, each of the multiple nozzles of the head 32 is also provided with a head driving unit for selectively ejecting color ink.

[0064] Solenoid 152 is provided in valve 521. Solenoid 152 opens valve 521 in a state where it is de-energized by CPU 81 (hereinafter referred to as a "de-energized state"), and closes valve 521 in a state where it is energized by CPU 81 (hereinafter referred to as a "energized state") Similarly, solenoids 153, 155, 162, 163, 165, 171, 172, and 191 are provided in valves 531, 551, 621, 631, 651, 711, 721, and 911, respectively. The solenoids 153, 155, 162, 163, 165, 171, 172, 191 open the valves 531, 551, 621, 631, 651, 711, 721, 911, respectively, in a non-energized state, and close the valves 531, 551, 621, 631, 651, 711, 721, 911, respectively, in a powered state. The pump motor 254 is provided in the pump 541 and drives the pump 541. Similarly, the pump motors 264, 291 are provided in the pumps 641, 912, respectively, and drive the pump 541.

[0065] The remaining amount sensor 231 is provided in the mounting portion 8 or the ink cartridge 23. The remaining amount sensor 231 detects the remaining amount of white ink 36 stored in the ink cartridge 23 (hereinafter referred to as the "remaining amount in the ink cartridge 23") and outputs a signal indicating the detection result to the CPU 81. The remaining amount sensor 241 is provided in the mounting portion 8 or the ink cartridge 24. The remaining amount sensor 241 detects the remaining amount of white ink 37 stored in the ink cartridge 24 (hereinafter referred to as the "remaining amount in the ink cartridge 24") and outputs a signal indicating the detection result to the CPU 81. The remaining amount sensor 231 is not limited to a specific type, and may be an optical sensor, a limit switch, a weight sensor, a pressure sensor, a level sensor, or the like. For example, the remaining amount sensor 231 may detect the remaining amount of the ink cartridge 23 in stages by detecting the change in shape of the ink cartridge 23 associated with the change in the remaining amount in the ink cartridge 23 in stages using multiple optical sensors. For example, the remaining amount sensor 231 may continuously detect the remaining amount in the ink cartridge 23 using, for example, a weight sensor. The remaining amount sensor 241 may also be configured similarly to the remaining amount sensor 231.

[0066] The connection sensor 232 is provided in the mounting portion 8, the ink cartridge 23, or the flow path 51. The connection sensor 232 detects whether the ink cartridge 23 is in a connected state, and outputs a signal indicating the detection result to the CPU 81. The connection sensor 242 is provided in the mounting portion 8, the ink cartridge 24, or the flow path 61. The connection sensor 242 detects whether the ink cartridge 24 is in a connected state, and outputs a signal indicating the detection result to the CPU 81. The connection sensors 232, 242 are not limited to a specific type, and may be an optical sensor, a limit switch, a weight sensor, a pressure sensor, etc.

[0067] The operation unit 17 is a touch panel or the like, and outputs information according to a user's operation to the CPU 81. By operating the operation unit 17, the user can input to the printer 1 a print instruction for starting printing by the printer 1, or the like.

[0068] The main processing will be described with reference to Figures 4 and 6. When the printer 1 is powered on, the CPU 81 executes the main processing shown in Figure 6 by reading and running a main program from the ROM 82. In the main processing, printing, capping, liquid contact, circulation, etc. are controlled. In this embodiment, the main processing starts in the capping state shown in Figure 4 with the pair of valves 521, 531 and the pair of valves 621, 631 open.

[0069] In the following, the difference in pressure between ink cartridge 23 and ink cartridge 24 shown in Figure 4 will be referred to as the "cartridge pressure difference." Of ink cartridges 23 and 24, the cartridge with the lower pressure will be referred to as the "ink cartridge with lower pressure." The difference between the remaining amount in ink cartridge 23 and the remaining amount in ink cartridge 24 will be referred to as the "cartridge remaining amount difference." For example, if there is a cartridge remaining amount difference, there is a possibility that there is a cartridge pressure difference.

[0070] In this embodiment, the ink cartridges 23 and 24 each have an ink storage section and a winding mechanism. The ink storage section is flexible. The winding mechanism winds up the ink storage section to reduce the amount of ink remaining in the ink storage section. For example, the winding mechanism winds up the ink storage section of the ink cartridge 23 toward the connection port 511 as the remaining amount of ink in the ink cartridge 23 decreases. This is configured so that the amount of ink storage section of the ink cartridge 23 wound up increases as the remaining amount of ink in the ink cartridge 23 decreases, and the external pressure acting on the ink storage section of the ink cartridge 23 becomes stronger. Similarly, the ink cartridge 24 is configured so that the amount of ink storage section of the ink cartridge 24 wound up increases as the remaining amount of ink in the ink cartridge 24 decreases, and the external pressure acting on the ink storage section of the ink cartridge 24 becomes stronger. In this case, the ink cartridge with the larger remaining amount out of the ink cartridges 23 and 24 is likely to be the ink cartridge with the smaller pressure. Note that the printer 1 may be provided with a pair of ink cartridges that are configured to undergo little or no change in shape in response to changes in the remaining amount, instead of the ink cartridges 23 and 24. In this case, the cartridge with the less remaining amount of ink in the pair of ink cartridges is likely to be the ink cartridge with the smaller pressure.

[0071] In the following, for the sake of explanation, the first flow path and the other flow path are defined as not being connected to each other. When one end of the first flow path and the other flow path are separated from each other through a gas medium, the liquid discharged from the first flow path through one end of the first flow path falls through the gas medium and does not enter the other flow path through one end of the other flow path. In this way, a state in which the liquid discharged from the first flow path through one end of the first flow path cannot enter the other flow path through one end of the other flow path is called a "state in which the liquid is not connected and does not move". On the other hand, when a liquid medium exists between each end of the first flow path and the other flow path, the liquid discharged from the first flow path through one end of the first flow path flows through the liquid medium and may enter the other flow path through one end of the other flow path. In this way, a state in which the liquid discharged from the first flow path through one end of the first flow path may enter the other flow path through one end of the other flow path is called a "state in which the liquid is connected so that it can move". Even if one flow path and another flow path are not connected to each other, depending on whether or not there is a liquid medium between them, they can be switched between a state in which they are not connected and no liquid moves, and a state in which they are connected and liquid can move.

[0072] In this embodiment, the nozzle groups W1 and W2 are not connected to the nozzle groups W3 and W4. Therefore, when the nozzle surface 311 shown in FIG. 4 is not in a liquid-contact state, the nozzle groups W1 and W2 are not connected to the nozzle groups W3 and W4, and liquid does not move. Therefore, when the nozzle surface 311 is not in a liquid-contact state, the white ink 36 does not enter the flow path 60 through the nozzle groups W3 and W4, and the white ink 37 does not enter the flow path 50 through the nozzle groups W1 and W2, regardless of the presence or absence of a cartridge pressure difference. On the other hand, as shown in FIG. 4, in a liquid-contact state, the nozzle groups W1 and W2 are connected to the nozzle groups W3 and W4 through the retained liquid 35 so that liquid can move between them. Therefore, in a liquid-contact state, the flow path 50 and the flow path 60 are connected to each other through the retained liquid 35 so that liquid can move between them. Furthermore, even if the nozzle surface 311 is not in a liquid-contacting state, if the cap 41 is in a holding state, the retained liquid 35 may come into contact with the nozzle groups W1, W2, W3, and W4 due to vibration or the like, and the flow paths 50 and 60 may become connected to each other via the retained liquid 35 so that liquid can move between them.

[0073] When the flow path 50 and the flow path 60 are connected to each other through the retention liquid 35 in a state where the cartridge pressure difference exists, the retention liquid 35 may enter the ink cartridge with the lower pressure through the nozzle 313. For example, when the ink cartridge with the lower pressure is the ink cartridge 23, the retention liquid 35 may enter the flow path 50 through the nozzle groups W1 and W2. For example, when the white ink 37 constituting the retention liquid 35 enters the flow path 50, the white ink 37 that entered the flow path 50 is consumed by the subsequent printing, so that the consumption amount of the white ink 36 by the subsequent printing is reduced. In this case, the white ink 36 in the ink cartridge 23 becomes old, and the quality of the white ink 36 in the ink cartridge 23 may deteriorate. Furthermore, when the cleaning liquid 38 constituting the retention liquid 35 reaches the ink cartridge 23, the quality of the white ink 36 in the ink cartridge 23 may deteriorate. In this embodiment, the main process (see FIG. 6) is performed to suppress the retention liquid 35 from entering the ink cartridges 23 and 24.

[0074] As shown in FIG. 6, when the main process starts, the CPU 81 determines whether a print instruction has been received via the operation unit 17 shown in FIG. 5 (S111). If a print instruction has not been received (S111: NO), the CPU 81 proceeds to S121. If a print instruction has been received (S111: YES), the CPU 81 refers to the RAM 83 and determines whether the nozzle surface 311 is in the wetted state shown in FIG. 4 based on the state of the liquid contact flag (S112). The liquid contact flag indicates whether the nozzle surface 311 is in the wetted state, and is stored in the RAM 83. If the nozzle surface 311 is in the wetted state, the liquid contact flag is ON. If the nozzle surface 311 is not in the wetted state, the liquid contact flag is OFF.

[0075] When the liquid contact flag is ON and the nozzle surface 311 is in a liquid contact state (S112: YES), the CPU 81 performs a liquid contact release process (S113). As will be described in detail later, in the liquid contact release process (S113), the liquid contact state is released. The CPU 81 moves the process to S114. When the liquid contact flag is OFF and the nozzle surface 311 is not in a liquid contact state (S112: NO), the CPU 81 moves the process to S114. The CPU 81 performs an uncap process in a state in which the liquid contact state is released (S114). In the uncap process (S114), the CPU 81 controls the cap motor 48 shown in FIG. 5 to lower the cap support part 47 shown in FIG. 3. As a result, the cap 41 is separated downward from the nozzle surface 311 of the head 31, and the capped state shown in FIG. 3 and FIG. 4 are changed to the uncapped state shown in FIG. 2.

[0076] The CPU 81 performs a printing process in the uncapping state shown in FIG. 2 (S115). In the printing process (S115), the CPU 81 controls the main scanning motor 99, the sub-scanning motor 97, and the head driving unit 301 shown in FIG. 5 to perform printing on the printing medium by the heads 31 and 32 shown in FIG. 1. When the printing process ends, the CPU 81 performs a capping process (S116). In the capping process (S116), the CPU 81 controls the capping motor 48 shown in FIG. 5 to raise the cap support unit 47 shown in FIG. 3. The cap 41 contacts the nozzle surface 311 of the head 31 to form the holding space 42. This causes the cap 41 to change from the uncapping state shown in FIG. 2 to the capping state shown in FIG. 3 and FIG. 4. The CPU 81 performs a closing process (S122) and a circulation process (S132) described later in the capping state. The CPU 81 shifts the process to the process of S121.

[0077] The CPU 81 determines whether to perform end-of-day processing (S121). For example, the flash memory 84 stores an end-of-day maintenance time set by the user. If it is not the end-of-day maintenance time, the CPU 81 determines not to perform end-of-day processing (S121: NO). In this case, the CPU 81 moves the process to processing of S131. If it is the end-of-day maintenance time, the CPU 81 determines to perform end-of-day processing (S121: YES). In this case, the CPU 81 moves the process to processing of S122. As will be described in more detail later, in the end-of-day processing (S122), the nozzle surface 311 is controlled to the liquid contact state shown in FIG. 4. The CPU 81 moves the process to processing of S131.

[0078] The CPU 81 determines whether to perform the circulation process (S131). For example, the flash memory 84 stores a circulation interval time set by the user. If the circulation interval time has not elapsed since the last circulation process, the CPU 81 determines not to perform the circulation process (S131: NO). In this case, the CPU 81 returns the process to the process of S111. If the circulation interval time has elapsed since the last circulation process, the CPU 81 determines to perform the circulation process (S131: YES). In this case, the CPU 81 performs the circulation process (S132). As will be described in detail later, the circulation process (S132) controls the circulation of the white ink 36 through the flow path 50 shown in FIG. 4 and the circulation of the white ink 37 through the flow path 60 shown in FIG. 4. The CPU 81 returns the process to the process of S111.

[0079] The closing process will be described with reference to Figs. 4 and 7. The closing process is started in a state where the pair of valves 521 and 531 and the pair of valves 621 and 631 shown in Fig. 4 are open. When the closing process is started, the CPU 81 performs a liquid contact process (S211). In the liquid contact process (S211), the CPU 81 closes the valve 721 shown in Fig. 4 and controls the valves 711 and 911 shown in Fig. 4 to be open. In this state, the CPU 81 drives the pump 912 shown in Fig. 4. As a result, as shown in Fig. 4, the cleaning liquid 38 flows from the cleaning liquid tank 70 through the flow path 71 toward the point P31 and into the holding space 42 (see arrow A31). The cap 41 is in a state where the cleaning liquid 38 is contained in the holding space 42 as the holding liquid 35.

[0080] When the driving of the pump 912 continues for a certain period of time, the retention space 42 is filled with the cleaning liquid 38 as the retention liquid 35. In this case, the retention liquid 35 comes into contact with the nozzle surface 311. The CPU 81 stops the driving of the pump 912. When the driving of the pump 912 stops, the CPU 81 closes the valves 711 and 911. As a result, the cap 41 retains the retention liquid 35 in the retention space 42, and is in a retention state (in this embodiment, a liquid contact state). In this embodiment, the time until the retention space 42 is filled with the retention liquid 35 (cleaning liquid 38) is stored in the ROM 82 as the driving time of the pump 912. The CPU 81 turns on a liquid contact flag in the RAM 83 (S212).

[0081] The greater the cartridge pressure difference, the higher the possibility that the retention liquid 35 will infiltrate into the ink cartridge with the lower pressure. For this reason, as shown in FIG. 7, the CPU 81 determines whether the cartridge remaining amount difference exceeds a predetermined threshold value (S213). The threshold value is a cartridge pressure difference value at which the retention liquid 35 shown in FIG. 4 does not substantially infiltrate into the ink cartridge with the lower pressure. The threshold value is stored in advance in the ROM 82. In the process of S213, the CPU 81 specifies the remaining amount of the ink cartridge 23 based on a signal from the remaining amount sensor 231 shown in FIG. 5, and specifies the remaining amount of the ink cartridge 24 based on a signal from the remaining amount sensor 241 shown in FIG. 5. The CPU 81 specifies the cartridge remaining amount difference based on the specified remaining amounts of the ink cartridge 23 and the ink cartridge 24. The CPU 81 compares the specified cartridge remaining amount difference with the threshold value.

[0082] If the cartridge remaining amount difference exceeds the threshold value (S213: YES), the CPU 81 turns on a close flag in the RAM 83 (S214). The close flag is a flag for advancing the process from S611 to S612 in the valve closing process (see FIG. 13) described below, and is stored in the RAM 83. When the process advances from S611 to S612, the close flag is turned on. When the process repeats S611, the close flag is turned off.

[0083] By performing the process of S214, the process advances from the process of S611 to the process of S612 in the valve closing process (see FIG. 13). As will be described in detail later, by performing the process from the process of S611 to the process of S612 in the valve closing process, the valves 521, 531, 621, and 631 shown in FIG. 4 are controlled, and one or both pairs (one in this embodiment) of the pair of valves 521 and 531 and the pair of valves 621 and 631 are closed. Therefore, after the process of S214, until the close flag is turned OFF, the CPU 81 performs each process of the main process in a state in which one or both pairs of the pair of valves 521 and 531 and the pair of valves 621 and 631 are closed. This prevents the retention liquid 35 from entering the ink cartridge with a low pressure when the cartridge remaining amount difference exceeds the threshold value. The CPU 81 returns the process to the main process shown in FIG. 6.

[0084] If the cartridge remaining amount difference is equal to or less than the threshold value (S213: NO), the CPU 81 returns the process to the main process shown in Fig. 6 without turning on the close flag. In this case, since the valves 521, 531, 621, and 631 are not opened or closed in the valve closing process (see Fig. 13), the meniscuses formed in the multiple nozzles 313 are prevented from being destroyed by the impact caused by the opening and closing of the valves 521, 531, 621, and 631.

[0085] The circulation process will be described with reference to FIG. 8. In this embodiment, in the circulation process, the CPU 81 controls a first circulation process (S316) and a second circulation process (S318) described below in a liquid contact state. For this reason, when the circulation process is started, the CPU 81 refers to the RAM 83 and determines whether the nozzle surface 311 is in a liquid contact state based on the state of the liquid contact flag (S311). If the liquid contact flag is ON, the nozzle surface 311 is in the liquid contact state shown in FIG. 4 (S311: YES). In this case, the CPU 81 turns OFF the close flag in the RAM 83 (S314). The CPU 81 proceeds to the process of S315.

[0086] If the liquid contact flag is OFF, the nozzle surface 311 is not in a liquid contact state (S311: NO). In this case, the CPU 81 performs liquid contact processing (S312). The liquid contact processing of S312 is the same as the liquid contact processing of S211 shown in Fig. 7. The liquid contact processing of S312 puts the nozzle surface 311 into the liquid contact state shown in Fig. 4. The CPU 81 sets the liquid contact flag ON in the RAM 83 (S313). The CPU 81 proceeds to processing of S315.

[0087] The CPU 81 determines whether the cartridge remaining amount difference exceeds the threshold value (S315) in the same manner as the process of S213 shown in Fig. 7. If the cartridge remaining amount difference exceeds the threshold value (S315: YES), the CPU 81 performs a first circulation process (S316). After the first circulation process (S316) is completed, the CPU 81 turns on the close flag in the RAM 83 (S317). The CPU 81 returns the process to the main process shown in Fig. 6. If the cartridge remaining amount difference is equal to or less than the threshold value (S315: NO), the CPU 81 performs a second circulation process (S318). After the second circulation process (S318) is completed, the CPU 81 returns the process to the main process shown in Fig. 6.

[0088] The first circulation process will be described with reference to Fig. 4, Fig. 9, and Fig. 10. As shown in Fig. 9, when the first circulation process is started, the CPU 81 performs a first hybrid circulation process (S511). In the first hybrid circulation process (S511), the CPU 81 controls the head circulation operation of the flow path 50 and the bypass circulation operation of the flow path 60.

[0089] As shown in FIG. 4 and FIG. 9, in the head circulation operation of the flow path 50, the CPU 81 closes the pair of valves 521 and 531, and closes the valve 551. In this state, the CPU 81 drives the pump 541. In this case, the white ink 36 circulates in the flow path 50 as shown by the arrow A11. That is, the white ink 36 flows from the pump 541 to the point P12 in the flow path 54. The white ink 36 flows in the flow path 52 from the point P12 to the point P14, and flows to the nozzle group W1. The white ink 36 flows from the nozzle group W1 to the nozzle group W2 through the communication path 314. The white ink 36 flows in the flow path 53 from the nozzle group W2 to the point P15, and flows to the point P13. The white ink 36 flows in the flow path 54 from the point P13 to the point P12, and circulates. This suppresses the increase in viscosity of the white ink 36 in the flow path 50 near the nozzle groups W1 and W2. When a predetermined pump drive time has elapsed in the head circulation operation of the flow path 50, the CPU 81 stops the pump 541. This ends the head circulation operation of the flow path 50.

[0090] In the bypass circulation operation of the flow path 60, the CPU 81 closes the pair of valves 621 and 631 and maintains the valve 651 in an open state. In this state, the CPU 81 drives the pump 641. In this case, the white ink 37 circulates in the flow path 60 as indicated by the arrow A22. That is, the white ink 37 flows from the pump 641 to the point P22 in the flow path 64. The white ink 37 flows from the point P22 to the point P24 in the flow path 62. The white ink 37 flows from the point P24 to the point P25 in the flow path 65. The white ink 37 flows from the point P25 to the point P23 in the flow path 63. The white ink 37 flows and circulates in the flow path 64 from the point P23 to the point P22. This suppresses the negative pressure in the nozzle groups W3 and W4. When a predetermined pump drive time has elapsed in the bypass circulation operation of the flow path 60, the CPU 81 stops the pump 541. This ends the bypass circulation operation of the flow path 60.

[0091] 9, in the present embodiment, in the first hybrid circulation process (S511), the CPU 81 performs the head circulation operation of the flow path 50 and the bypass circulation operation of the flow path 60 in parallel. The CPU 81 may perform the head circulation operation of the flow path 50 and the bypass circulation operation of the flow path 60 with a shift from each other. After the first hybrid circulation process (S511) is completed, the CPU 81 performs the second hybrid circulation process (S512). In the second hybrid circulation process (S512), the CPU 81 controls the bypass circulation operation of the flow path 50 and the head circulation operation of the flow path 60.

[0092] As shown in FIG. 4 and FIG. 9, in the bypass circulation operation of the flow path 50, the CPU 81 opens the valve 551 and maintains the pair of valves 521 and 531 in a closed state. In this state, the CPU 81 drives the pump 541. In this case, the white ink 36 circulates in the flow path 50 as indicated by the arrow A12. That is, the white ink 36 flows from the pump 541 to the point P12 in the flow path 54. The white ink 36 flows from the point P12 to the point P14 in the flow path 52. The white ink 36 flows from the point P14 to the point P15 in the flow path 55. The white ink 36 flows from the point P15 to the point P13 in the flow path 53. The white ink 36 flows and circulates in the flow path 54 from the point P13 to the point P12. This suppresses the negative pressure in the nozzle groups W1 and W2. When a predetermined pump drive time has elapsed in the bypass circulation operation of the flow path 50, the CPU 81 stops the pump 541. This ends the bypass circulation operation of the flow path 50.

[0093] In the head circulation operation of the flow path 60, the CPU 81 maintains the pair of valves 621 and 631 in a closed state and closes the valve 651. In this state, the CPU 81 drives the pump 641. In this case, the white ink 37 circulates in the flow path 60 as indicated by the arrow A21. That is, the white ink 37 flows from the pump 641 to the point P22 in the flow path 64. The white ink 37 flows in the flow path 62 from the point P22 to the point P24, and flows to the nozzle group W3. The white ink 37 flows from the nozzle group W3 to the nozzle group W4 via the communication path 315. The white ink 37 flows in the flow path 63 from the nozzle group W4 to the point P25, and flows to the point P23. The white ink 37 flows in the flow path 64 from the point P23 to the point P22, and circulates. This prevents the white ink 37 from becoming highly viscous in the vicinity of the nozzle groups W3 and W4 in the flow path 60. When a predetermined pump drive time has elapsed during the head circulation operation of the flow path 60, the CPU 81 stops the pump 641. This ends the head circulation operation of the flow path 60.

[0094] As shown in FIG. 9, in this embodiment, in the second hybrid circulation process (S512), the CPU 81 performs the bypass circulation operation of the flow path 50 and the head circulation operation of the flow path 60 in parallel with each other. The CPU 81 may perform the bypass circulation operation of the flow path 50 and the head circulation operation of the flow path 60 in a shifted manner. After the second hybrid circulation process (S512) is completed, the CPU 81 sets the first hybrid circulation process and the second hybrid circulation process following the first hybrid circulation process as one set of hybrid circulation operations, and determines whether the number of sets of the hybrid circulation operations that have been executed has reached a predetermined number of sets (for example, three sets) (S513). If the number of sets of the hybrid circulation operations that have been executed is less than the predetermined number of sets (S513: NO), the CPU 81 returns the process to the process of S511. As a result, the hybrid circulation operation is repeated. If the number of sets of the hybrid circulation operations that have been executed reaches the predetermined number of sets (S513: YES), the CPU 81 shifts the process to the process of S514 shown in FIG. 10.

[0095] As shown in FIG. 10, the CPU 81 performs a first filter circulation process (S514). In the first filter circulation process (S514), a filter circulation operation of the flow path 50 is executed. As shown in FIG. 4 and FIG. 10, in the filter circulation operation of the flow path 50, the CPU 81 opens the pair of valves 521 and 531 and closes the valve 551. In this state, the CPU 81 drives the pump 541. In this case, in the flow path 50, the white ink 36 circulates as indicated by the arrow A13. That is, the white ink 36 flows from the pump 541 to the point P12 in the flow path 54. The white ink 36 flows from the point P12 to the point P11 in the flow path 52. The white ink 36 flows from the point P11 to the point P13 in the flow path 53. The white ink 36 flows and circulates in the flow path 54 from the point P13 to the point P12. As a result, deposits on the filters 522, 532, and 542 are removed. When a predetermined pump drive time has elapsed during the filter circulation operation of the flow path 50, the CPU 81 stops the pump 541. This ends the filter circulation operation of the flow path 50.

[0096] In the first filter circulation process (S514), while the filter circulation operation of the flow path 50 is being performed, the CPU 81 maintains a state in which the filter circulation operation of the flow path 60 is stopped. In this case, the CPU 81 controls the pair of valves 621, 631 and the valve 651 to be closed. The CPU 81 maintains a state in which the driving of the pump 641 is stopped.

[0097] As shown in FIG. 10, after the first filter circulation process is completed, the CPU 81 performs a second filter circulation process (S515). In the second filter circulation process (S515), a filter circulation operation of the flow path 60 is executed. As shown in FIG. 4 and FIG. 10, in the filter circulation operation of the flow path 60, the CPU 81 opens the pair of valves 621 and 631 and closes the valve 651. In this state, the CPU 81 drives the pump 641. In this case, in the flow path 60, the white ink 37 circulates as indicated by the arrow A23. That is, the white ink 37 flows from the pump 641 to the point P22 in the flow path 64. The white ink 37 flows from the point P22 to the point P21 in the flow path 62. The white ink 37 flows from the point P21 to the point P23 in the flow path 63. The white ink 37 flows and circulates in the flow path 64 from the point P23 to the point P22. As a result, deposits on the filters 622, 632, and 642 are removed. When a predetermined pump drive time has elapsed during the filter circulation operation of the flow path 60, the CPU 81 stops the pump 641.

[0098] In the second filter circulation process (S515), the CPU 81 maintains the stopped state of the filter circulation operation of the flow path 50 while the filter circulation operation of the flow path 60 is being performed. In this case, the CPU 81 controls the pair of valves 521, 531 and the valve 551 to be closed. The CPU 81 maintains the stopped state of the drive of the pump 541.

[0099] As shown in Fig. 10, after the second filter circulation process (S515) is completed, the CPU 81 sets the first filter circulation process and the second filter circulation process subsequent to the first filter circulation process as one set of filter circulation operations, and determines whether the number of sets of the executed filter circulation operations has reached a predetermined number of sets (e.g., 3 sets) (S516). If the number of sets of the executed filter circulation operations is less than the predetermined number of sets (S516: NO), the CPU 81 returns the process to the process of S514. This causes the filter circulation to be repeated. If the number of sets of the executed filter circulation operations has reached the predetermined number of sets (S516: YES), the CPU 81 returns the process to the main process shown in Fig. 6.

[0100] Hereinafter, the state in which the white ink 36 circulates through each of the flow paths 51 and 52 shown in Fig. 4 will be referred to as the "circulation state of the flow path 50," and the state in which the white ink 37 circulates through each of the flow paths 61 and 62 shown in Fig. 4 will be referred to as the "circulation state of the flow path 60." In this embodiment, the circulation state of the flow path 50 is a state in which at least one of a head circulation operation of the flow path 50, a bypass circulation operation of the flow path 50, and a filter circulation operation of the flow path 50 is being performed. In this embodiment, the circulation state of the flow path 60 is a state in which at least one of a head circulation operation of the flow path 60, a bypass circulation operation of the flow path 60, and a filter circulation operation of the flow path 60 is being performed.

[0101] As described above, in the first filter circulation process (S514), the CPU 81 controls the pair of valves 621, 631 to be closed in the circulation state of the flow path 50. In the second filter circulation process (S515), the CPU 81 controls the pair of valves 521, 531 to be closed in the circulation state of the flow path 60.

[0102] The second circulation process will be described with reference to Fig. 11. The CPU 81 performs a first hybrid circulation process (S521). The first hybrid circulation process of S521 is the same as the first hybrid circulation process of S511 shown in Fig. 9. Therefore, in the flow path 50, the white ink 36 circulates as indicated by the arrow A11, and in the flow path 60, the white ink 37 circulates as indicated by the arrow A22 (see Fig. 4).

[0103] After the first hybrid circulation process (S521) is completed, the CPU 81 performs a second hybrid circulation process (S522). The second hybrid circulation process of S522 is the same as the second hybrid circulation process of S512 shown in Fig. 9. Therefore, in the flow path 50, the white ink 36 circulates as indicated by the arrow A12, and in the flow path 60, the white ink 37 circulates as indicated by the arrow A21 (see Fig. 4).

[0104] After the second hybrid circulation process (S522) is completed, the CPU 81 determines whether the number of sets of the executed hybrid circulation action reaches a predetermined number of sets (S523), similar to the process of S523 shown in Fig. 9. If the number of sets of the executed hybrid circulation action is less than the predetermined number of sets (S523: NO), the CPU 81 returns the process to the process of S521. This causes the hybrid circulation action to be repeated. If the number of sets of the executed hybrid circulation action reaches the predetermined number of sets (S523: YES), the CPU 81 shifts the process to the process of S524.

[0105] The CPU 81 performs a filter circulation process (S524). In the filter circulation process (S524), the CPU 81 performs the filter circulation operation of the flow path 50 and the filter circulation operation of the flow path 60 in parallel with each other. The filter circulation operation of the flow path 50 in the filter circulation process of S524 is the same as the filter circulation operation of the flow path 50 in the first filter circulation process of S514 shown in FIG. 10. Therefore, the white ink 36 circulates in the flow path 50 as indicated by the arrow A13 (see FIG. 4). The filter circulation operation of the flow path 60 in the filter circulation process of S524 is the same as the filter circulation operation of the flow path 60 in the second filter circulation process of S515 shown in FIG. 10. Therefore, the white ink 37 circulates in the flow path 60 as indicated by the arrow A23 (see FIG. 4).

[0106] After the filter circulation process (S524) is completed, the CPU 81 determines whether the number of times the filter circulation process has been executed has reached a predetermined number (e.g., three times) (S525). If the number of times the filter circulation process has been executed is less than the predetermined number (S525: NO), the CPU 81 returns the process to the process of S524. This causes the filter circulation process to be repeated. If the number of times the filter circulation process has been executed has reached the predetermined number (S525: YES), the CPU 81 returns the process to the main process shown in FIG.

[0107] The liquid contact release process will be described with reference to FIG. 4 and FIG. 12. The CPU 81 refers to the RAM 83 and determines whether the close flag is ON (S411). If the close flag is OFF (S411: NO), the CPU 81 moves the process to S414. If the close flag is ON (S411: YES), the CPU 81 turns the close flag OFF in the RAM 83 (S412). This ends the control of the valves 521, 531, 621, and 631 by the valve close process (see FIG. 13). The CPU 81 performs the valve open process (S413). In the valve open process (S413), the CPU 81 opens the pair of valves that is in a closed state out of the pair of valves 521, 531 and the pair of valves 621, 631 shown in FIG. 4. This brings both pairs of valves 521, 531 and the pair of valves 621, 631 into an open state.

[0108] The CPU 81 performs a discharge process (S414). In the discharge process (S414), as shown in FIG. 4, the CPU 81 opens the valves 711, 721, and 911. In this state, the CPU 81 drives the pump 912. As a result, the retained liquid 35 flows from the retaining space 42 through the flow path 91 to the waste liquid tank 90 (see arrow A32). Furthermore, the cleaning liquid 38 is not supplied from the cleaning liquid tank 70 to the retaining space 42, and air flows from the atmosphere 73 through the flow path 72 toward the point P31 and flows through the flow path 71 to the retaining space 42 (see arrow A33). Therefore, when the drive of the pump 912 continues for a certain period of time, substantially the entire retained liquid 35 is discharged to the waste liquid tank 90 as the waste liquid 39, and the retaining space 42 is filled with air. As a result, the liquid contact state is released.

[0109] In this embodiment, the time until substantially all of the retained liquid 35 is discharged as waste liquid 39 into the waste liquid tank 90 and the holding space 42 is filled with air is stored in the ROM 82 as the drive time of the pump 912. As shown in Fig. 12, when the drive of the pump 912 is stopped, the CPU 81 turns off the liquid contact flag in the RAM 83 (S415). The CPU 81 returns the process to the main process shown in Fig. 6.

[0110] The valve closing process will be described with reference to Figures 4 and 13. When the printer 1 is powered on, the CPU 81 executes the valve closing process by reading and running a closing process program from the ROM 82. In this case, the CPU 81 advances the valve closing process in parallel with the main process. In the valve closing process, opening and closing control is performed for the pair of valves 521, 531 and the pair of valves 621, 631.

[0111] When the valve closing process is started, the CPU 81 refers to the RAM 83 and determines whether the close flag is ON (S611). If the close flag is maintained OFF (S611: NO), the CPU 81 repeats the process of S611 until the close flag is ON. The close flag is turned ON by the process of S214 shown in FIG. 7 or S317 shown in FIG. 8 (S611: YES). That is, when the cap 41 is in the holding state (liquid contact state) shown in FIG. 4, the close flag is turned ON. In this case, the CPU 81 closes the pair of valves 521 and 531 shown in FIG. 4 (S612). In this embodiment, in the process of S612, the CPU 81 closes each of the pair of valves 521 and 531 with a time difference. For example, when a predetermined waiting time has elapsed since the valve 521 was closed, the CPU 81 closes the valve 531. As a result, the power consumed to close both the valves 521 and 531 is reduced compared to the case where the valves 521 and 531 are closed simultaneously. The waiting time is shorter than the time from when the first switching timing is reached to when the second switching timing is reached, which will be described later. The waiting time is not limited to a specific length, but is, for example, about several seconds.

[0112] As described above, the close flag is turned ON after the liquid contact process (S211) shown in Fig. 7 is performed. Therefore, after the cap 41 is in the holding state (in this embodiment, the liquid contact state), the CPU 81 closes the pair of valves 521 and 531 shown in Fig. 4 by the process of S612.

[0113] A state that is neither the circulation state of flow path 50 nor the circulation state of flow path 60 is referred to as a "non-circulation state", and one or both of the circulation states of flow path 50 and flow path 60 is referred to as a "circulation state". The close flag is turned OFF by the process of S314 before the first circulation process (S316) and the second circulation process (S318) shown in Fig. 8 are performed, and is not turned ON in the circulation state. Therefore, in the non-circulation state, the CPU 81 closes the pair of valves 521, 531 by the process of S612.

[0114] The CPU 81 refers to the RAM 83 and determines whether the close flag is OFF (S613). The close flag is turned OFF by the process of S314 shown in FIG. 8 or the process of S412 shown in FIG. 12 in the main processing (S613: YES). In this case, the CPU 81 returns the process to the process of S611. In this case, the CPU 81 repeats the process of S611 until the close flag is turned ON again. If the close flag is maintained ON (S613: NO), the CPU 81 determines whether either of the ink cartridges 23, 24 is in a connected state based on signals from the connection sensors 232, 242 shown in FIG. 5 (S614).

[0115] If both ink cartridges 23, 24 are in a connected state (S614: YES), the CPU 81 determines whether the switching timing has arrived (S615). The switching timing may be, for example, the timing when a predetermined switching time has elapsed since the processing of S612 or the previous switching processing (S616) was performed. The switching timing may be, for example, a predetermined switching time. The switching time or switching time may be stored in the ROM 82, or may be set by the user and stored in the flash memory 84.

[0116] If the switching timing has not yet arrived (S615: NO), the CPU 81 returns the process to the process of S613. If the switching timing has arrived (S615: YES), the CPU 81 performs switching processing (S616). Hereinafter, a state in which the pair of valves 521, 531 is closed and the pair of valves 621, 631 is open is referred to as a "first valve state", and a state in which the pair of valves 521, 531 is open and the pair of valves 621, 631 is closed is referred to as a "second valve state". In the switching processing (S616), the CPU 81 alternates between the first valve state and the second valve state. For example, the CPU 81 sets the pair of valves 521, 531 and the pair of valves 621, 631 that are open to a closed state, and sets the pair of valves that are closed to an open state.

[0117] In this embodiment, in the switching process (S616), the CPU 81 closes each of the open valve pairs with a time lag, similar to the process of S612. That is, when a predetermined waiting time has elapsed since the CPU 81 closed one of the open valve pairs, the CPU 81 closes the other of the open valve pairs. The CPU 81 returns the process to the process of S613.

[0118] For example, when the ink cartridge 23 is removed from the flow path 51 and the valve 521 or the valve 531 is switched between open and closed, the pressure change caused by the opening and closing of the valves 521 and 531 may cause air to enter the flow path 50 from the connection port 511, or the white ink 36 to overflow from the flow path 50 via the connection port 511. Similarly, when the ink cartridge 24 is removed from the flow path 61 and the valve 621 or the valve 631 is switched between open and closed, air may enter the flow path 60 from the connection port 611, or the white ink 37 may overflow from the flow path 60 via the connection port 611.

[0119] If the connection state of one or both of the ink cartridges 23, 24 is released (S614: NO), the CPU 81 returns the process to the process of S613. As a result, the CPU 81 prohibits the switching process (S616) from being performed when the ink cartridge 23 is removed from the flow path 51, and prohibits the switching process (S616) from being performed when the ink cartridge 24 is removed from the flow path 61. In this way, after the process of S214 shown in Fig. 7 or S317 shown in Fig. 8 is performed, the CPU 81 repeats the switching process (S616) each time the switching timing is reached (S615: YES) until the process of S412 shown in Fig. 12 is performed or the connection state of one or both of the ink cartridges 23, 24 is released.

[0120] When one or both of the ink cartridges 23, 24 are released from the connected state after the ink cartridges 23, 24 are released from the connected state (S614: YES), the CPU 81 repeats the switching process (S616) each time the switching timing is reached (S615: YES). In this case, the CPU 81 may continue or interrupt the timing of the switching time during the period when the ink cartridges 23, 24 are released from the connected state. For example, when the timing of the switching time is continued during the period when the ink cartridges 23, 24 are released from the connected state, if a predetermined switching time or more has passed since the processing of S612 or the previous switching process (S616) was performed at the time of processing S615, the CPU 81 may determine that the switching timing has been reached. Alternatively, if the predetermined switching time has passed at the time of processing S615, the CPU 81 may determine that the switching timing has been reached, or may determine that the switching timing has not been reached until the next switching time after the predetermined switching time has passed.

[0121] An example of the effect of the embodiment described above will be described. In the above embodiment, in the case of the holding state and the non-circulation state, the CPU 81 controls one of the pair of valves 521, 531 and the pair of valves 621, 631 to a closed state (first valve state or second valve state). For example, when the processes of S214 and S317 are performed and the close flag is turned ON, the cap 41 is in the holding state (liquid contact state) and the flow paths 50, 60 are in the non-circulation state. When the close flag is turned ON (S611: YES), the CPU 81 controls the pair of valves 521, 531 to a closed state by the process of S612. According to this, the pair of valves 521, 531 is closed, and the flow paths 50 are blocked between the ink cartridge 23 and each of the nozzle groups W1, W2. Therefore, even if the nozzle groups W1, W2 and the nozzle groups W3, W4 are connected to each other so that liquid can move between them, the ink cartridges 23 and 24 are unlikely to be connected to each other so that liquid can move between them via the retention liquid 35. Therefore, even if there is a cartridge pressure difference, the cartridge pressure difference is unlikely to affect the pressure difference between the nozzle groups W1, W2 and the nozzle groups W3, W4. Therefore, the printer 1 contributes to reducing the possibility of the retention liquid 35 entering the ink cartridges 23, 24.

[0122] For example, if the first valve state is not switched to the second valve state, the pair of valves 521 and 531 will continue to heat for a long time. In this case, the heat state of the valves 521 and 531 will continue for a long time. Therefore, the valves 521 and 531 may deteriorate, and the heat generated by the valves 521 and 531 may adversely affect the white ink 36. In the above embodiment, in the holding state and non-circulation state, the CPU 81 alternates between the first valve state and the second valve state (S616). This prevents one of the pair of valves 521 and 531 and the pair of valves 621 and 631 from continuing to heat for a long time, compared to when the first valve state or the second valve state is not switched. Therefore, the printer 1 contributes to suppressing the influence on the white inks 36 and 37 caused by the heat generated by the pair of valves 521 and 531 or the pair of valves 621 and 631. The printer 1 contributes to suppressing deterioration in durability of the pair of valves 521 and 531 or the pair of valves 621 and 631.

[0123] In the case of the holding state, the non-circulation state, and the first valve state, if it is detected that at least one of the connections between the ink cartridge 23 and the flow path 50 and between the ink cartridge 24 and the flow path 60 has been disconnected (S614: NO), the CPU 81 skips the switching process (S616) and maintains the first valve state. In the case of the holding state, the non-circulation state, and the second valve state, if it is detected that at least one of the connections between the ink cartridge 23 and the flow path 50 and between the ink cartridge 24 and the flow path 60 has been disconnected (S614: NO), the CPU 81 skips the switching process (S616) and maintains the second valve state. According to this, in the printer 1, when the connection state of one or both of the ink cartridges 23, 24 is disconnected, the printer 1 does not switch from one of the first valve state and the second valve state to the other. Therefore, the printer 1 contributes to suppressing the overflow of the white inks 36, 37 from the flow paths 50, 60, or the intrusion of air into the flow paths 50, 60.

[0124] The pair of valves 521, 531 and the pair of valves 621, 631 are open in a non-energized state and closed in an energized state. When the difference in the remaining amount of cartridges exceeds a threshold value in the case of the holding state and non-circulating state (S213: YES or S315: YES), the CPU 81 turns on the close flag and controls one of the pair of valves 521, 531 and the pair of valves 621, 631 to a closed state (first valve state or second valve state) (S612). When the difference in the remaining amount of cartridges is less than the threshold value in the case of the holding state and non-circulating state (S213: NO or S315: NO), the close flag is maintained OFF, so that both the pair of valves 521, 531 and the pair of valves 621, 631 are controlled to an open state. According to this, when the possibility of the retention liquid 35 entering the ink cartridges 23, 24 is relatively high, electricity is applied to one of the pair of valves 521, 531 and the pair of valves 621, 631. This allows the printer 1 to contribute to reducing the possibility of the retention liquid 35 entering the ink cartridges 23, 24. On the other hand, when the possibility of the retention liquid 35 entering the ink cartridges 23, 24 is relatively low, electricity is not applied to the pair of valves 521, 531 and the pair of valves 621, 631. This allows the printer 1 to contribute to power saving. In other words, the printer 1 contributes to reducing the possibility of the retention liquid 35 entering the ink cartridges 23, 24 while contributing to power saving.

[0125] If one or both of the pair of valves 521, 531 and the pair of valves 621, 631 are closed before being controlled to the holding state, the meniscus formed in each of the nozzle groups W1, W2 and the nozzle groups W3, W4 may be destroyed, and air may enter the flow path 50 from the nozzle groups W1, W2, or air may enter the flow path 60 from the nozzle groups W3, W4. In this case, purging is required to exhaust air from the flow paths 50, 60. In the above embodiment, when the processes of S214 and S317 are performed and the close flag is turned ON, the cap 41 is in the holding state and the flow paths 50, 60 are in the non-circulating state. After the cap 41 is in the holding state, if it is in the non-circulating state, the CPU 81 turns the close flag ON and closes one of the pair of valves 521, 531 and the pair of valves 621, 631 (S612). Therefore, the printer 1 contributes to suppressing the meniscus formed in each of the nozzle groups W1 and W2 and the nozzle groups W3 and W4 from being destroyed, and the intrusion of air into the flow paths 50 and 60.

[0126] In the case of the retention state and the circulation state of the flow path 50, the CPU 81 controls both of the pair of valves 621, 631 to be closed (S514). In the case of the retention state and the circulation state of the flow path 60, the CPU 81 controls both of the valves 521, 531 to be closed (S515). This contributes to reducing the possibility of the retention liquid 35 entering the ink cartridges 23, 24 not only in the non-circulation state but also in the circulation state of the flow path 50 and the circulation state of the flow path 60.

[0127] In the above embodiment, the nozzle surface 311 corresponds to the "nozzle surface" of the present invention. The nozzle groups W1 and W2 correspond to the "first nozzle" of the present invention. The nozzle groups W3 and W4 correspond to the "second nozzle" of the present invention. The white ink 36 corresponds to the "first ejection liquid" of the present invention. The white ink 37 corresponds to the "second ejection liquid" of the present invention. The ink cartridge 23 corresponds to the "first storage section" of the present invention. The ink cartridge 24 corresponds to the "second storage section" of the present invention. One of the flow paths 51 and 52 corresponds to the "first flow path" of the present invention. One of the valves 521 and 531 corresponds to the "first valve" of the present invention. One of the flow paths 61 and 62 corresponds to the "second flow path" of the present invention. One of the valves 621 and 631 corresponds to the "second valve" of the present invention. The retention space 42 corresponds to the "retention space" of the present invention. The cleaning liquid 38 corresponds to the "cleaning liquid" of the present invention. The retention liquid 35 corresponds to the "retention liquid" of the present invention. The cap 41 corresponds to the "cap" of the present invention. The CPU 81 corresponds to the "controller" and the "computer" of the present invention.

[0128] The remaining amount sensor 231 corresponds to the "first sensor" of the present invention. The remaining amount sensor 241 corresponds to the "second sensor" of the present invention. The other of the flow paths 51, 52 corresponds to the "third flow path" of the present invention. The other of the valves 521, 531 corresponds to the "third valve" of the present invention. The other of the flow paths 61, 62 corresponds to the "fourth flow path" of the present invention. The other of the valves 621, 631 corresponds to the "fourth valve" of the present invention. Pump 541 corresponds to the "first pump" of the present invention. Pump 641 corresponds to the "second pump" of the present invention. The circulation state of flow path 50 corresponds to the "first circulation state" of the present invention. The circulation state of flow path 60 corresponds to the "second circulation state" of the present invention.

[0129] The present invention may be modified from the above embodiment. Various modified examples described below can be combined with each other as long as no contradiction occurs. At least one of the pair of valves 521, 531 and the pair of valves 621, 631 may have a self-holding mechanism that closes when energized and maintains the closed state when energization is stopped in the closed state. A permanent magnet, for example, is used as the self-holding mechanism. For example, when the pair of valves 521, 531 has a self-holding mechanism, the CPU 81 may change the valve closing process as follows. In the process of S612, the CPU 81 closes the pair of valves 521, 531, and then stops energizing the pair of valves 521, 531 while the pair of valves 521, 531 is closed. That is, the CPU 81 may not maintain energization of the valves 521, 531 after energizing the valves 521, 531 and closing the pair of valves 521, 531. In this case, the CPU 81 may omit the processes of S615 and S616.

[0130] In the case of the above modification, when the power supply to the pair of valves 521, 531 is stopped while the pair of valves 521, 531 is closed, the self-holding mechanism keeps the pair of valves 521, 531 closed. Thus, the printer 1 contributes to power saving while reducing the possibility of the retention liquid 35 entering the ink cartridges 23, 24.

[0131] In the above embodiment, the printer 1 may be configured to be unable to execute some or all of the head circulation operation, bypass circulation operation, and filter circulation operation. In the capping state, the CPU 81 may eject the white inks 36, 37 instead of the cleaning liquid 38, and fill the retention space 42 with the white inks 36, 37 as the retention liquid 35. The liquid contact flag may indicate whether the cap 41 is in a retention state. In other words, when the liquid contact flag is ON, the nozzle surface 311 does not necessarily have to be in a liquid contact state, as long as the cap 41 is in a retention state.

[0132] In the above embodiment, in the process of S612, the CPU 81 closes one of the pair of valves 521, 531 and the pair of valves 621, 631. In contrast, in the process of S612, the CPU 81 may close both of the pair of valves 521, 531 and the pair of valves 621, 631. In this case, the CPU 81 may omit the processes of S615 and S616.

[0133] In the above embodiment, the nozzle group W1 is composed of a plurality of nozzle rows. In contrast, the nozzle group W1 may be composed of a single nozzle row, or may be composed of one nozzle 313. The nozzle groups W2, W3, and W4 may also be modified in the same manner as the nozzle group W1. The printer 1 may omit one of the nozzle groups W1 and W2. The printer 1 may omit one of the nozzle groups W3 and W4. For example, when the printer 1 omits the nozzle groups W2 and W4, the flow paths 53, 54, and 55 may be omitted in the flow path 50, and the flow paths 63, 64, and 65 may be omitted in the flow path 60. Furthermore, the flow paths 50 and 60 may be modified in various ways. For example, in the flow path 50, only the flow path 54 may be omitted, or only the flow path 55 may be omitted. The flow path 50 may connect one or more nozzle groups to the ink cartridge 23 in addition to the nozzle groups W1 and W2. The flow paths 52 and 53 may be directly connected to the ink cartridge 23 without the flow path 51. The flow path 60 may be modified in the same manner as the flow path 50.

[0134] In the above embodiment, in the switching process (S616), the CPU 81 may switch between the first valve state and the second valve state via a state in which both the pair of valves 521, 531 and the pair of valves 621, 631 are closed. The CPU 81 may omit the switching process (S616). That is, after closing the pair of valves 521, 531 in the process of S612, the CPU 81 may maintain the pair of valves 521, 531 in the closed state until the close flag becomes OFF.

[0135] In the above embodiment, the printer 1 may include a first ink tank instead of the ink cartridge 23. The printer 1 may include a second ink tank instead of the ink cartridge 24. The printer 1 may include a first sub-pouch instead of the ink cartridge 23. The printer 1 may include a second sub-pouch instead of the ink cartridge 24. The first sub-pouch and the second sub-pouch are each a bag-shaped container and have flexibility. In this case, the first sub-pouch and the second sub-pouch may each be connected to an ink cartridge for supplying ink to the first sub-pouch and the second sub-pouch. The first sub-pouch and the second sub-pouch may each be connected to the same ink cartridge or to different ink cartridges. The valves 521, 531, 621, and 631 may each be a ball valve or the like.

[0136] In the valve closing process, if the connection state of one or both of the ink cartridges 23, 24 is released (S614: NO), the CPU 81 may turn off the close flag and return the process to the process of S611. The CPU 81 may omit the process of S614. That is, the CPU 81 may perform the switching process (S616) regardless of whether one or both of the ink cartridges 23, 24 are in a connected state. The printer 1 may omit the connection sensors 232, 242. In this case, the user may input an instruction indicating that one or both of the ink cartridges 23, 24 have become in a connected state via the operation unit 17. The CPU 81 may detect that one or both of the ink cartridges 23, 24 are in a connected state by acquiring the input instruction.

[0137] The printer 1 may omit the remaining amount sensors 231, 241. In this case, the CPU 81 may omit one or both of the processes of S213 and S315. That is, the CPU 81 may turn on the closed graph in the process of S214 regardless of whether the cartridge remaining amount difference exceeds the threshold value. The CPU 81 may execute the first circulation process (S316) regardless of whether the cartridge remaining amount difference exceeds the threshold value, and may execute the second circulation process (S318) regardless of whether the cartridge remaining amount difference exceeds the threshold value.

[0138] In the above embodiment, after the liquid contact process (S211, S312) is performed, the liquid contact flag is turned ON in the process of S214 or S313, and the pair of valves 521, 531 is closed. In contrast, the CPU 81 may close one or both of the pair of valves 521, 531 and the pair of valves 621, 631 before performing the liquid contact process (S211, S312). The CPU 81 may perform the liquid contact process (S211, S312) in a state where one or both of the pair of valves 521, 531 and the pair of valves 621, 631 are closed.

[0139] The ink cartridge 23 may store a liquid different from the white ink 36. The liquid different from the white ink 36 is a color ink, a special color ink, a pre-treatment agent, a discharge agent, a post-treatment agent, etc. Similarly, the ink cartridge 24 may store a liquid different from the white ink 37. The liquid stored in the ink cartridge 23 and the liquid stored in the ink cartridge 24 may be different from each other. In the processing of S612, the CPU 81 may simultaneously close each of the pair of valves 521, 531. In the processing of S616, the CPU 81 may simultaneously close each of the pair of valves that are open.

[0140] In the above embodiment, the valves 521, 531, 551, 621, 631, 651, 711, 721, and 911 are each open in a non-energized state and closed in an energized state. In contrast, the valves 531, 551, 621, 631, 651, 711, 721, and 911 may be closed in a non-energized state and open in an energized state. For example, the valves 531, 621, 631, and 721 may be open in a non-energized state and closed in an energized state, and the valves 551, 651, 711, and 911 may be closed in a non-energized state and open in an energized state.

[0141] The printer 1 may include a line head instead of the heads 31 and 32. In this case, for example, the cap 41 may move in the left-right or front-rear direction with respect to the head 31 to a position facing the nozzle surface 311 in the up-down direction. The positional relationship between the pump 541 and the filter 542 may be changed from that of the above embodiment. For example, the pump 541 and the filter 542 may be arranged in the order of the filter 542 and the pump 541 from the point P13 toward the point P12. Similarly, the positional relationship between the valve 521 and the filter 522, the positional relationship between the valve 531 and the filter 532, the positional relationship between the pump 641 and the filter 642, the positional relationship between the valve 621 and the filter 622, and the positional relationship between the valve 631 and the filter 632 may also be changed. Instead of the pair of the valves 521 and 531, one valve may be provided in the flow path 51. Instead of the pair of the valves 621 and 631, one valve may be provided in the flow path 61.

[0142] The nozzle surface 311 may be configured with separate surfaces for the nozzle groups W1 and W2 and the nozzle groups W3 and W4. In the nozzle surface 311, the surface on which the nozzle groups W1 and W2 are provided and the surface on which the nozzle groups W3 and W4 are provided may be separated from each other on the same plane. For example, the first convex portion and the second convex portion may each protrude downward from the lower surface of the head 31. The nozzle groups W1 and W2 may be provided on the lower surface of the first convex portion, and the nozzle groups W3 and W4 may be provided on the lower surface of the second convex portion. In this case, the lower surface of the first convex portion and the lower surface of the second convex portion constitute the nozzle surface 311.

[0143] Instead of the CPU 81, a microcomputer, an ASIC (Application Specific Integrated Circuits), an FPGA (Field Programmable Gate Array), or the like may be used as a processor. The main processing may be distributed processing by a plurality of processors. The valve closing processing may be distributed processing by a plurality of processors. The non-transitory storage medium such as the ROM 82 and the flash memory 84 may be a storage medium capable of retaining information regardless of the period for which the information is stored. The non-transitory storage medium may not include a temporary storage medium (e.g., a transmitted signal). For example, the control program may be downloaded (i.e., transmitted as a transmission signal) from a server connected to a network not shown, and stored in the ROM 82 or the flash memory 84. In this case, the control program may be stored in a non-transitory storage medium such as an HDD provided in the server. [Explanation of symbols]

[0144] 1: Printer 35:Retentate 38: Cleaning fluid 41: Cap 42: Holding space 50~55, 60~65: Flow path 81 :CPU 311: Nozzle surface 521, 531, 621, 631: Valves 541, 641: Pump W1, W2, W3, W4: Nozzle groups

Claims

1. A printer in which a first nozzle and a second nozzle are provided on a nozzle surface, a first liquid is discharged from the first nozzle, and a second liquid is discharged from the second nozzle, A first reservoir that stores the first ejection liquid; a first flow path for the first discharge liquid, the first flow path connecting the first reservoir and the first nozzle; A first valve provided in the first flow path; A second reservoir that stores the second discharge liquid; a second flow path for the second discharge liquid, the second flow path connecting the second reservoir and the second nozzle; A second valve provided in the second flow path; a cap that surrounds the first nozzle and the second nozzle, comes into contact with the nozzle face, and forms a holding space between the nozzle face and a cap that holds a holding liquid, which is the first ejection liquid, the second ejection liquid, or a cleaning liquid, in the holding space; Control unit and Equipped with The control unit is When the cap is in a holding state in which the retained liquid is retained in the retaining space, and the state is neither a first circulation state in which the first discharge liquid is circulated through the first flow path nor a second circulation state in which the second discharge liquid is circulated through the second flow path, one or both of the first valve and the second valve are controlled to a closed state. A printer characterized by:

2. The control unit is When the holding state is in the non-circulation state, switching is performed between a first valve state in which the first valve is closed and the second valve is open, and a second valve state in which the first valve is open and the second valve is closed.

2. The printer according to claim 1.

3. the first storage portion and the second storage portion are each a cartridge; the first valve and the second valve are each either a diaphragm valve or a tube valve; The control unit is In the case of the holding state, the non-circulation state, and the first valve state, when it is detected that at least one of the connection between the first storage portion and the first flow path and the connection between the second storage portion and the second flow path has been released, the first valve state is maintained, When it is detected that at least one of the connection between the first storage portion and the first flow path and the connection between the second storage portion and the second flow path has been released in the holding state, the non-circulation state, and the second valve state, the second valve state is maintained.

3. The printer according to claim 2.

4. a first sensor for detecting a first remaining amount of the first liquid stored in the first storage portion; a second sensor for detecting a second remaining amount of the second ejection liquid stored in the second storage portion; Equipped with the first valve and the second valve are each open in a non-energized state and closed in an energized state; The control unit is In the case of the holding state and the non-circulation state, when a difference between the first remaining amount detected by the first sensor and the second remaining amount detected by the second sensor exceeds a predetermined threshold, one or both of the first valve and the second valve are controlled to a closed state; When the liquid is in the holding state and the non-circulating state, if a difference between the first remaining amount detected by the first sensor and the second remaining amount detected by the second sensor is less than the predetermined threshold value, both the first valve and the second valve are controlled to be open.

3. The printer according to claim 1 or 2.

5. the first valve has a self-holding mechanism that closes when energized and maintains the closed state when energization is stopped in the closed state; The control unit is When the liquid is in the holding state and in the non-circulating state, the first valve is closed and the current supply to the first valve is stopped.

2. The printer according to claim 1.

6. The control unit is controlling the cap to the holding state with both the first valve and the second valve open; After the cap is in the retained state, in the non-circulating state, one or both of the first valve and the second valve are closed.

3. The printer according to claim 1 or 2.

7. a third flow path which is a flow path of the first discharge liquid and connects the first reservoir and the first nozzle; A third valve provided in the third flow path; a fourth flow path for the second discharge liquid, the fourth flow path connecting the second reservoir and the second nozzle; a fourth valve provided in the fourth flow path; a first pump that circulates the first discharge liquid through each of the first flow path and the third flow path; a second pump that circulates the second discharge liquid through each of the second flow path and the fourth flow path; Equipped with The control unit is driving the first pump in a state where both the first valve and the third valve are open, and controlling the first pump to the first circulation state in which the first discharge liquid circulates through each of the first flow path and the third flow path; When the liquid is in the holding state and the first circulation state, the second valve and the fourth valve are both controlled to be in a closed state; driving the second pump in a state where both the second valve and the fourth valve are open, and controlling the second pump to the second circulation state in which the second discharge liquid circulates through each of the second flow path and the fourth flow path; When the liquid is in the holding state and the second circulation state, the first valve and the third valve are both controlled to be in a closed state.

3. The printer according to claim 1 or 2.

8. A method for controlling a printer in which a first nozzle and a second nozzle are provided on a nozzle surface, a first liquid is discharged from the first nozzle, and a second liquid is discharged from the second nozzle, comprising the steps of: The printer includes: A first reservoir that stores the first ejection liquid; a first flow path for the first discharge liquid, the first flow path connecting the first reservoir and the first nozzle; A first valve provided in the first flow path; A second reservoir that stores the second discharge liquid; a second flow path for the second discharge liquid, the second flow path connecting the second reservoir and the second nozzle; A second valve provided in the second flow path; a cap that surrounds the first nozzle and the second nozzle, comes into contact with the nozzle face, and forms a holding space between the nozzle face and a cap that holds a holding liquid, which is the first ejection liquid, the second ejection liquid, or a cleaning liquid, in the holding space; Equipped with The control method includes: When the cap is in a holding state in which the retained liquid is retained in the retaining space, and the state is neither a first circulation state in which the first discharge liquid is circulated through the first flow path nor a second circulation state in which the second discharge liquid is circulated through the second flow path, one or both of the first valve and the second valve are controlled to a closed state. A control method comprising:

9. A control program for causing a computer to execute a process for controlling a printer in which a first nozzle and a second nozzle are provided on a nozzle surface, a first liquid is ejected from the first nozzle, and a second liquid is ejected from the second nozzle, the control program comprising: The printer includes: A first reservoir for storing the first ejection liquid; a first flow path for the first discharge liquid, the first flow path connecting the first reservoir and the first nozzle; A first valve provided in the first flow path; A second reservoir that stores the second discharge liquid; a second flow path for the second discharge liquid, the second flow path connecting the second reservoir and the second nozzle; A second valve provided in the second flow path; a cap that surrounds the first nozzle and the second nozzle, comes into contact with the nozzle face, and forms a holding space between the nozzle face and a cap that holds a holding liquid, which is the first ejection liquid, the second ejection liquid, or a cleaning liquid, in the holding space; Equipped with The control program causes the computer to When the cap is in a holding state in which the retained liquid is retained in the retaining space, and the state is neither a first circulation state in which the first discharge liquid is circulated through the first flow path nor a second circulation state in which the second discharge liquid is circulated through the second flow path, one or both of the first valve and the second valve are controlled to be in a closed state. A control program characterized by causing the program to be executed.

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