Liquid dispensing device

Abstract

As the liquid discharge head moves in the scanning direction, the liquid in the liquid flow path is made to flow, suppressing the thickening of the liquid near the nozzle and reducing unnecessary liquid discharge during liquid introduction. [Solution] The printer includes an inkjet head 1 having a flow path 35, an ink cartridge, a connecting flow path 41 connecting one end of the flow path 35 to the ink cartridge, an exhaust flow path 3B having one end connected to the other end of the flow path 35 and an exhaust port 3X at the other end, an opening / closing mechanism, an introduction mechanism, and a control unit. The exhaust flow path 3B has a pressure absorption section 3E. The control unit closes the exhaust port 3X by the opening / closing mechanism when the inkjet head 1 is moved in the scanning direction, and opens the exhaust port 3X by the opening / closing mechanism when the ink is initially introduced.

Description

Technical Field

[0004] , , , , , ,

[0001] The present invention relates to a liquid ejection device including a liquid ejection head movable in a scanning direction.

Background Art

[0002] Patent Document 1 describes a printer including an inkjet head connected to an ink tank via a tube and a sub-tank and movable in a scanning direction. The sub-tank has a first damper portion and a second damper portion. The inkjet head has a first manifold, a second manifold, and nozzles, and a plurality of individual flow paths communicating between the first manifold and the second manifold. When the inkjet head moves in the scanning direction, a pressure difference generated between the first damper portion and the second damper portion causes an ink flow from the first damper portion through the ink flow paths (the first manifold, the individual flow paths, the second manifold) of the inkjet head toward the second damper portion, and the ink in the inkjet head circulates. Thereby, thickening of the ink in the nozzles can be suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, the object of the present invention is to provide a liquid dispensing device that can suppress the viscosity increase of the liquid near the nozzle by causing the liquid in the liquid flow path to flow as the liquid dispensing head moves in the scanning direction, thereby suppressing the wasteful discharge of liquid during liquid introduction. [Means for solving the problem]

[0006] The liquid discharge device of the present invention comprises a liquid discharge head having a liquid flow path including a nozzle, a moving mechanism for moving the liquid discharge head in a scanning direction, a liquid tank in which liquid is stored, a first connecting flow path connecting one end of the liquid flow path to the liquid tank, a second connecting flow path having one end connected to the other end of the liquid flow path, an opening / closing mechanism capable of opening and closing the outlet which is the other end of the second connecting flow path, an introduction mechanism for introducing liquid from the liquid tank into the liquid flow path via the first connecting flow path, and a control unit for controlling the moving mechanism, the opening / closing mechanism and the introduction mechanism, wherein the first connecting flow path is The second connecting channel has an extended portion that extends in the scanning direction, the extended portion being defined by a tube that moves in the scanning direction together with the liquid discharge head, the second connecting channel has a first pressure absorption section that absorbs pressure fluctuations of the liquid in the liquid channel caused by the flow of liquid in the tube as the liquid discharge head moves in the scanning direction, the control unit closes the outlet with the opening / closing mechanism when the moving mechanism moves the liquid discharge head in the scanning direction, and opens the outlet with the opening / closing mechanism when the introduction mechanism introduces the liquid from the liquid tank into the liquid channel. [Effects of the Invention]

[0007] According to the liquid discharge device of the present invention, as the liquid in the tube flows due to the movement of the liquid discharge head in the scanning direction, the liquid in the first connecting channel flows into the liquid channel, and when the positive pressure generated in the liquid in the liquid channel is absorbed by the first pressure absorption unit, the liquid in the liquid channel flows into the second connecting channel. On the other hand, as the liquid in the first connecting channel flows toward the liquid tank and the negative pressure generated in the liquid channel is absorbed by the first pressure absorption unit, the liquid in the second connecting channel flows into the liquid channel, and the liquid in the liquid channel flows into the first connecting channel. In this way, when the pressure fluctuation of the liquid in the liquid channel is absorbed by the first pressure absorption unit, liquid flow occurs within the liquid channel, making it possible to suppress the viscosity increase of the liquid near the nozzle. In addition, since the outlet is closed when the liquid discharge head moves in the scanning direction, it is possible to prevent liquid from flowing out from the outlet. On the other hand, when the liquid in the liquid tank is introduced into the liquid channel, the outlet is open, so the liquid flows sequentially from the liquid tank to the first connecting channel, the liquid channel, and the second connecting channel. In other words, it becomes possible to supply liquid from the liquid tank to the liquid flow path through a single route, preventing uneven liquid flow in the two paths and thus reducing wasted liquid discharge during liquid introduction. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of a printer according to one embodiment of the present invention. [Figure 2] This is a plan view of an inkjet print head. [Figure 3] Figure 2 shows a cross-sectional view of the head along the line III-III. [Figure 4] Figure 2 shows a cross-sectional view of the head along the IV-IV line. [Figure 5] This is a schematic cross-sectional view relating to a vertical plane perpendicular to the scanning direction of the inkjet head, sub-tank, discharge unit, first cap, second cap, and opening / closing member when the inkjet head is in the maintenance position. [Figure 6] This is a block diagram showing the electrical configuration of a printer. [Figure 7]In a vertical plane perpendicular to the scanning direction of the inkjet head, sub-tank, discharge unit, first cap, second cap, and opening / closing member when the inkjet head is in the maintenance position, (a) is a schematic cross-sectional view when a purging operation is performed, and (b) is a schematic cross-sectional view when initial ink introduction is performed. [Figure 8] (a) is a schematic cross-sectional view showing the ink flow in the flow path when the inkjet head moves in one direction of scanning, and (b) is a schematic cross-sectional view showing the ink flow in the flow path when the inkjet head moves in the other direction of scanning, in a vertical plane perpendicular to the scanning direction of the inkjet head, sub-tank, and discharge unit. [Modes for carrying out the invention]

[0009] <Overall printer configuration> As shown in Figure 1, the printer 100 includes an inkjet head 1, a sub-tank 2, an ejection unit 3, a moving mechanism 4, a platen 5, a transport mechanism 6, a maintenance unit 7, a control unit 90, and a housing 100A that houses these components. The printer 100 corresponds to the "liquid ejection device" of the present invention.

[0010] The moving mechanism 4 includes a carriage 4A, two guide rails 4B and 4C, and a carriage motor 4M. The carriage 4A is supported by the two guide rails 4B and 4C. The two guide rails 4B and 4C extend parallel to each other along the scanning direction. The carriage 4A is connected to the carriage motor 4M via a transmission mechanism (not shown), and when the carriage motor 4M is driven, the carriage 4A moves along the guide rails 4B and 4C in the scanning direction. The transmission mechanism transmits power from the carriage motor 4M so that the carriage 4A moves in the scanning direction. In the following explanation, the right and left directions of the scanning direction will be defined as shown in Figure 1.

[0011] The sub-tank 2 and discharge unit 3 are mounted on the carriage 4A. Here, the printer 100 includes a cartridge holder 10, in which an ink cartridge 10A is removably mounted. The cartridge holder 10 is located on the front right side inside the housing 100A. The ink cartridge 10A stores black ink (the "liquid" of this invention). The ink cartridge 10A corresponds to the "liquid tank" of this invention.

[0012] Subtank 2 is connected to ink cartridge 10A mounted in cartridge holder 10 via tube 10B. This supplies ink from ink cartridge 10A to subtank 2. Tube 10B extends from ink cartridge 10A to the left along the scanning direction, then folds back to the right and extends again in the scanning direction before connecting to subtank 2. In other words, tube 10B has a pair of extending portions 10B1 that extend parallel to the scanning direction. As carriage 4A (subtank 2) moves in the scanning direction, the lengths of the pair of extending portions 10B1 change relative to each other in the scanning direction.

[0013] The inkjet head 1 is mounted on the carriage 4A and connected to the lower end of the sub-tank 2. Ink is supplied to the inkjet head 1 from the sub-tank 2. The inkjet head 1 ejects ink from a plurality of nozzles N formed on its lower surface, the nozzle surface 1A. More specifically, the plurality of nozzles N are arranged in a transport direction perpendicular to the scanning direction. The inkjet head 1 corresponds to the "liquid ejection head" of the present invention. The transport direction corresponds to the "orthogonal direction" of the present invention.

[0014] The discharge unit 3 is positioned adjacent to the inkjet head 1 and the sub-tank 2 on the upstream side in the transport direction. The discharge unit 3 includes an outlet 3X on its lower surface 3Y for discharging ink and air bubbles when ink is initially introduced to the inkjet head 1.

[0015] The platen 5 is disposed below the inkjet head 1 and faces a plurality of nozzles N. The platen 5 extends over the entire length of the paper 9 in the scanning direction and supports the paper 9 from below.

[0016] The conveyance mechanism 6 has two conveyance roller pairs 6A, 6B and a conveyance motor 6M. The conveyance roller pair 6A is disposed upstream of the inkjet head 1 and the platen 5 in the conveyance direction. The conveyance roller pair 6B is disposed downstream of the inkjet head 1 and the platen 5 in the conveyance direction.

[0017] Each conveyance roller pair 6A, 6B consists of two rollers arranged to sandwich the paper 9. The two rollers are composed of a driving roller that rotates when the conveyance motor 6M is driven and a driven roller that rotates as the driving roller rotates. The driving rollers of each conveyance roller pair 6A, 6B are connected to the conveyance motor 6M via a transmission mechanism (not shown). When the conveyance motor 6M is driven, the driving rollers of each conveyance roller pair 6A, 6B rotate, and the paper 9 is conveyed in the conveyance direction. The transmission mechanism transmits the power of the conveyance motor 6M so that the driving rollers of each conveyance roller pair 6A, 6B rotate.

[0018] The maintenance unit 7 includes a first cap 71, a second cap 72, a suction pump 73, a waste liquid tank 74, an opening / closing member 75, a lifting mechanism 76 (see FIG. 6), a cap lifting mechanism 77 (see FIG. 6), and a switching mechanism 78. The maintenance unit 7 mainly forces ink to be discharged from the plurality of nozzles N of the inkjet head 1 to recover its ejection performance, and is disposed at a maintenance position on the right side of the platen 5 in the scanning direction. Also, the maintenance unit 7 is used when initially introducing the ink of the ink cartridge 10A into the inkjet head 1. Details of this maintenance unit 7 will be described later.

[0019] Next, referring to FIGS. 2 to 4, the inkjet head 1 will be described. As shown in FIGS. 2 and 4, the inkjet head 1 has a flow path member 11 and an actuator member 12.

[0020] As shown in FIG. 2, the flow path member 11 has a flow path 35. The flow path 35 is composed of a plurality of individual flow paths 20 arranged in the conveyance direction, a common flow path 30 communicating with these individual flow paths 20, and a connecting flow path 33. A supply port 31X is formed at one end of the flow path 35, and a discharge port 32X is formed at the other end. The flow path 35 corresponds to the "liquid flow path" of the present invention. As shown in FIGS. 3 and 4, the flow path member 11 is composed of 11 plates 11A to 11K laminated in the vertical direction and adhered to each other. Through holes forming the flow path 35 are formed in each of the plates 11A to 11K.

[0021] As shown in FIGS. 3 and 4, the common flow path 30 has an upper common flow path 31 and a lower common flow path 32 arranged overlapping each other in the vertical direction. The upper common flow path 31 and the lower common flow path 32 each extend in the conveyance direction. The upper common flow path 31 and the lower common flow path 32 have substantially the same length (length in the conveyance direction), width (length in the scanning direction), and height (length in the vertical direction).

[0022] As shown in FIG. 4, the connecting flow path 33 extends in the vertical direction and connects one end in the conveyance direction of the upper common flow path 31 and one end in the conveyance direction of the lower common flow path 32. The other end in the conveyance direction of the upper common flow path 31 (the upper end in FIG. 2) communicates with the sub-tank 2 via the supply port 31X. The other end in the conveyance direction of the lower common flow path 32 (the upper end in FIG. 2) communicates with the discharge unit 3 via the discharge port 32X. The supply port 31X and the discharge port 32X open on the upper surface 11X of the flow path member 11.

[0023] As shown in FIG. 2, the supply port 31X and the discharge port 32X are on the same side with respect to the plurality of individual flow paths 20 in the conveyance direction and are arranged side by side in the conveyance direction. The supply port 31X is between the plurality of individual flow paths 20 and the discharge port 32X in the conveyance direction.

[0024] As shown in Figures 3 and 4, the upper common channel 31 is composed of a through-hole formed in plate 11E. The lower common channel 32 is composed of a through-hole formed in plate 11H. A damper chamber 34 is provided between the upper common channel 31 and the lower common channel 32 in the vertical direction. The damper chamber 34 is composed of a recess formed in plate 11F and a recess formed in plate 11G. The bottom of the recess in plate 11F functions as a damper membrane 31D for the upper common channel 31. The bottom of the recess in plate 11G functions as a damper membrane 32D for the lower common channel 32. By having such a damper chamber 34 and damper membranes 31D and 32D, crosstalk of discharge pressure through the upper common channel 31 and the lower common channel 32 that occurs when ink is discharged from multiple nozzles N can be effectively suppressed.

[0025] Each individual flow path 20 includes a nozzle N, a pressure chamber flow path 21, an inflow flow path 24, and an outflow flow path 25, as shown in Figure 3. The nozzle N is composed of a through hole formed in the plate 11K and opens to the lower surface (nozzle surface 1A) of the flow path member 11.

[0026] The pressure chamber flow path 21 consists of a pressure chamber 22 and a connecting flow path 23. The pressure chamber 22 is formed by a through hole in the plate 11A and opens to the upper surface 11X of the flow path member 11. The pressure chamber 22 is a roughly rectangular shape that is elongated in the scanning direction on the upper surface 11X. An inflow flow path 24 is connected to one end of the pressure chamber 22 in the scanning direction, and a connecting flow path 23 is connected to the other end in the scanning direction.

[0027] The connecting channel 23 is composed of through holes formed in plates 11B to 11J and extends in the vertical direction. The connecting channel 23 is positioned between the nozzle N and the pressure chamber 22 in the vertical direction and connects the nozzle N and the pressure chamber 22 to each other.

[0028] The inflow channel 24 is composed of through holes formed in plates 11B to 11D. The inflow channel 24 has an upper end connected to the pressure chamber 22 and a lower end connected to the upper common channel 31. The inflow channel 24 corresponds to the "first communication channel" of the present invention.

[0029] The outflow channel 25 is composed of through holes formed in plates 11I to 11K. The outflow channel 25 has one end that connects to the lower end of the connecting channel 23 and the other end that connects to the lower common channel 32. The outflow channel 25 corresponds to the "second communication channel" of the present invention.

[0030] The inlet channel 24 and outlet channel 25 each have a width smaller than the width (length in the conveying direction) of the pressure chamber 22 and function as a throttling channel. In addition, one inlet channel 24 and one outlet channel 25 are provided for each pressure chamber channel 21.

[0031] When ink is ejected from nozzle N, the ink supplied from the upper common channel 31 to each individual channel 20 flows into the pressure chamber 22 through the inflow channel 24, moves approximately horizontally within the pressure chamber 22, and flows into the connecting channel 23. The ink that flows into the connecting channel 23 moves downward and is ejected from nozzle N.

[0032] As shown in Figure 3, the actuator member 12 includes, from bottom to top, a diaphragm 12A, a common electrode 12B, a plurality of piezoelectric elements 12C, and a plurality of individual electrodes 12D.

[0033] The diaphragm 12A and the common electrode 12B are positioned on the upper surface 11X of the flow channel member 11 and cover all of the pressure chambers 22 formed in the plate 11A. On the other hand, the piezoelectric element 12C and the individual electrodes 12D are provided for each pressure chamber 22 and overlap each of the pressure chambers 22 in the vertical direction.

[0034] The common electrode 12B and the multiple individual electrodes 12D are electrically connected to the driver IC 13. The driver IC 13 maintains the potential of the common electrode 12B at ground potential while changing the potential of the individual electrodes 12D. Specifically, the driver IC 13 generates a drive signal based on a control signal from the control unit 90 and applies this drive signal to the individual electrodes 12D. As a result, the potential of the individual electrodes 12D changes between a predetermined drive potential and ground potential. At this time, the portion of the diaphragm 12A and piezoelectric element 12C sandwiched between the individual electrodes 12D and the pressure chamber 22 (actuator 12X) deforms so as to become convex toward the pressure chamber 22, thereby changing the volume of the pressure chamber 22, applying pressure to the ink in the pressure chamber 22, and ejecting the ink from the nozzle N. The actuator member 12 has multiple actuators 12X corresponding to each of the pressure chambers 22.

[0035] Next, with reference to Figure 5, the sub-tank 2 and the discharge unit 3 will be described. As shown in Figure 5, the sub-tank 2 has a tank body 2A fixed to the flow path member 11, a joint portion 2B, and a damper membrane 2C. The tank body 2A has a storage chamber 2A1 in which ink can be stored. The damper membrane 2C seals the open upper part of the tank body 2A. The damper membrane 2C is made of a flexible thin plate member. The storage chamber 2A1 is formed by the region enclosed by the damper membrane 2C and the tank body 2A. In other words, the damper membrane 2C constitutes the upper wall of the storage chamber 2A1.

[0036] Furthermore, the sub-tank 2 has a pressure absorption section 2E consisting of a storage chamber 2A1 and a damper membrane 2C. The pressure absorption section 2E absorbs pressure fluctuations acting on the ink in the storage chamber 2A1. The pressure absorption section 2E corresponds to the "second pressure absorption section" of the present invention. The storage chamber 2A1 corresponds to the "second damper chamber," and the damper membrane 2C corresponds to the "second damper membrane."

[0037] A recess 2A2 is formed in the lower part of the tank body 2A, where an actuator member 12 can be positioned between it and the flow path member 11. The tank body 2A also has a discharge channel 2A3 that discharges the ink from the storage chamber 2A1 into the flow path 35. The discharge channel 2A3 is in communication with the flow path 35 via a supply port 31X.

[0038] The joint section 2B is made of a cylindrical member and has a supply channel 2B1 inside. The supply channel 2B1 is in communication with the tube 10B, and ink from the ink cartridge 10A flows through it. The supply channel 2B1 is also in communication with the storage chamber 2A1, and supplies ink from the ink cartridge 10A to the storage chamber 2A1. The channel inside the tube 10B, the supply channel 2B1, the storage chamber 2A1, and the discharge channel 2A3 constitute a single connecting channel 41 that connects the ink cartridge 10A to one end (supply port 31X) of the channel 35 of the inkjet head 1. The connecting channel 41 corresponds to the "first connecting channel" of the present invention.

[0039] The discharge unit 3 comprises a case 3A, a discharge channel 3B, a damper membrane 3C, and an on / off valve 3D. The case 3A is integrally formed on the side of the tank body 2A (the side on the upstream side in the transport direction) and opens upward. The damper membrane 3C seals the open upper part of the case 3A. The discharge channel 3B is located within the case 3A and is formed in the region enclosed by the case 3A and the damper membrane 3C. The damper membrane 3C consists of the upstream portion in the transport direction of the thin plate member that constitutes the damper membrane 2C. In other words, these damper membranes 2C and 3C are made from a single thin plate member. Furthermore, the damper membranes 2C and 3C are positioned above the storage chamber 2A1 and the damper chamber 3B1 (described later).

[0040] Furthermore, the discharge passage 3B includes a damper chamber 3B1, a first communication passage 3B2, and a second communication passage 3B3. The damper chamber 3B1 is defined by a damper membrane 3C, and its volume changes as the damper membrane 3C is displaced. In other words, the discharge unit 3 has a pressure absorption section 3E consisting of the damper chamber 3B1 and the damper membrane 3C. The pressure absorption section 3E absorbs pressure fluctuations acting on the ink in the damper chamber 3B1. The pressure absorption section 3E corresponds to the "first pressure absorption section" of the present invention. The damper chamber 3B1 corresponds to the "first damper chamber," and the damper membrane 3C corresponds to the "first damper membrane."

[0041] The pressure absorption section 3E has a compliance that is smaller than that of the pressure absorption section 2E. In other words, the pressure absorption section 2E has a compliance that is larger than that of the pressure absorption section 3E. When the carriage 4A moves in the scanning direction, such as when printing on paper 9 with the inkjet head 1, the inkjet head 1, sub-tank 2, and discharge unit 3 also move in the scanning direction, as does the tube 10B. As the tube 10B moves, the ink in the extended portion 10B1 connected to the joint portion 2B of the pair of extended portions 10B1 flows in the scanning direction, and the resulting inertial pressure acts on the ink in the flow path 35 of the inkjet head 1. The pressure absorption section 2E is set to a compliance that is sufficient to prevent the application of inertial pressure to the ink in the flow path 35 of the inkjet head 1 that would damage the meniscus of the nozzle N.

[0042] On the other hand, the pressure absorption section 3E is set to a compliance level that allows the flow of ink in the flow path 35 of the inkjet head 1 to occur due to the flow of ink in the tube 10B as it moves in the scanning direction.

[0043] The first connecting passage 3B2 extends vertically, with its upper end communicating with the damper chamber 3B1 and its lower end communicating with the discharge port 32X. The second connecting passage 3B3 extends vertically, with its upper end communicating with the damper chamber 3B1 and a discharge port 3X formed at its lower end. The first connecting passage 3B2 and the second connecting passage 3B3 are arranged side by side in the conveying direction. The discharge passage 3B corresponds to the "second connecting passage" of the present invention.

[0044] Furthermore, case 3A extends vertically on the side upstream of the tank body 2A in the transport direction and on the side upstream of the inkjet head 1 in the transport direction, with its lower surface 3Y positioned at approximately the same height level as the nozzle surface 1A. The discharge port 3X opens into the lower surface 3Y of case 3A.

[0045] The on / off valve 3D is disposed to be movable vertically within the second communication passage 3B3 and includes a valve member 3D1 capable of closing the discharge passage 3B, and a coil spring 3D2 that biases the valve member 3D1 downward.

[0046] The valve member 3D1 has a bottomed cylindrical valve body 3D3 that is movable vertically within the second communication passage 3B3, and a valve stem 3D4 extending downward from the bottom of the valve body 3D3. The outer diameter of the valve body 3D3 is smaller than the inner diameter of the second communication passage 3B3, allowing ink to flow between the valve body 3D3 and the inner wall surface of the second communication passage 3B3. An annular sealing material 3D5 is attached to the lower surface of the valve body 3D3, and the valve body 3D3 is configured to close the second communication passage 3B3 (discharge passage 3B) by contacting a valve seat surface 3D6 provided in a stepped portion of the second communication passage 3B3 via the sealing material 3D5.

[0047] The coil spring 3D2 is positioned in a compressed state between the inner wall 3A1 of the case 3A and the valve body 3D3, and this coil spring 3D2 biases the valve member 3D1 downward. When the valve body 3D3 is driven upward against the biasing force of the coil spring 3D2 by the lifting mechanism 76, which will be described later, the valve body 3D3 separates from the valve seat surface 3D6, and the discharge passage 3B is opened.

[0048] Next, the maintenance unit 7 will be described. As shown in Figure 5, the first cap 71 has a recess 71A that opens upward and is configured to be in close contact with the nozzle surface 1A of the inkjet head 1. When the inkjet head 1 (carriage 4A) moves to the maintenance position, the first cap 71 faces the nozzle surface 1A. In this state, the first cap 71 is moved upward by the drive of the cap drive motor 77M (see Figure 6) of the cap lifting mechanism 77, so that the first cap 71 is in close contact with the nozzle surface 1A and covers the multiple nozzles N, as shown in Figure 7(a). At this time, a sealed space K1 is formed in which the nozzle surface 1A is covered by the recess 71A.

[0049] As shown in Figure 5, the second cap 72 has a recess 72A that opens upward and is configured to be in close contact with the lower surface 3Y of the discharge unit 3. When the inkjet head 1 (carriage 4A) moves to the maintenance position, the second cap 72 faces the lower surface 3Y of the discharge unit 3. In this state, the second cap 72 is moved upward by the cap drive motor 77M (see Figure 6) of the cap lifting mechanism 77, so that the second cap 72 is in close contact with the lower surface 3Y and covers the discharge port 3X, as shown in Figure 7(a). At this time, a sealed space K2 is formed where the lower surface 3Y is covered by the recess 72A. The cap lifting mechanism 77 is configured to allow the first cap 71 and the second cap 72 to move up and down in the vertical direction.

[0050] The opening / closing member 75 is a rod-shaped member that extends in the vertical direction. The opening / closing member 75 penetrates the bottom wall of the second cap 72 while maintaining airtightness and is configured to be movable relative to the second cap 72 in the vertical direction. Furthermore, when the inkjet head 1 moves to the maintenance position, as shown in Figure 7, the opening / closing member 75 is positioned directly below the output port 3X.

[0051] The opening / closing member 75 is moved up and down by the drive of the valve drive motor 76M (see Figure 6) of the lifting mechanism 76. In other words, the opening / closing member 75 moves between the open position and the closed position when the valve drive motor 76M is driven. That is, the lifting mechanism 76 is configured to allow the opening / closing member 75 to move up and down in the vertical direction. The closed position is the position in which the opening / closing member 75 moves away from the opening / closing valve 3D and closes the opening / closing valve 3D, as shown in Figure 7(a). The open position is the position in which the opening / closing member 75 contacts the opening / closing valve 3D and opens the opening / closing valve 3D, as shown in Figure 7(b).

[0052] Then, with the discharge port 3X on the lower surface 3Y of the discharge unit 3 covered by the second cap 72, when the opening / closing member 75 moves upward relative to the discharge unit 3, the upper end of the opening / closing member 75 is inserted into the second communication passage 3B3 from the discharge port 3X, and pushes the valve stem 3D4 inside the second communication passage 3B3 upward. As a result, the valve body 3D3 moves upward integrally with the valve stem 3D4, the sealing material 3D5 separates from the valve seat surface 3D6, and the discharge passage 3B is opened (valve opens).

[0053] In this embodiment, the on / off valve 3D, the on / off member 75, and the lifting mechanism 76 constitute an on / off mechanism capable of opening and closing the discharge port 3X of the discharge passage 3B.

[0054] The suction pump 73 is connected to the first cap 71 and the second cap 72 by a tube via a switching mechanism 78. The switching mechanism 78 is configured to selectively switch between a first communication state, in which the suction pump 73 is connected to the recess 71A of the first cap 71, and a second communication state, in which the suction pump 73 is connected to the recess 72A of the second cap 72.

[0055] When the first cap 71 is in close contact with the nozzle surface 1A and covers the nozzle N, and the switching mechanism 78 is in the first communication state, the suction operation of the suction pump 73 is performed, the air in the sealed space K1 is sucked in and the pressure decreases, and as shown in Figure 7(a), ink is discharged from the nozzle N into the recess 71A (purged). This makes it possible to discharge the thickened ink in the nozzle N and the air bubbles in the inkjet head 1 from the nozzle N along with the ink.

[0056] When the second cap 72 is in close contact with the lower surface 3Y of the discharge unit 3, covering the discharge port 3X, and the opening / closing valve 3D is opened by the opening / closing member 75, and the switching mechanism 78 is in the second communication state, when the suction operation of the suction pump 73 is performed, the air in the sealed space K2 is sucked in, the pressure decreases, and ink is discharged from the discharge port 3X into the recess 72A as shown in Figure 7(b) (initial ink introduction). This allows the ink from the ink cartridge 10A to be introduced into the connecting channel 41, the channel 35 of the inkjet head 1, and the discharge channel 3B of the discharge unit 3, and also makes it possible to discharge air bubbles and foreign matter in these channels along with the ink.

[0057] In this embodiment, the second cap 72, the switching mechanism 78, and the suction pump 73 constitute an introduction mechanism that introduces the ink from the ink cartridge 10A into the flow path 35 of the inkjet head 1 via the connecting flow path 41.

[0058] Next, the control unit 90 will be described. The control unit 90 includes a CPU 91, a ROM 92, and a RAM 93, and controls the operation of the driver IC 13, the transport motor 6M, the carriage motor 4M, the suction pump 73, the valve drive motor 76M, the cap drive motor 77M, and the switching mechanism 78, etc.

[0059] The CPU 91 performs various controls based on data input from external devices, etc., according to programs and data stored in the ROM 92 and RAM 93. For example, the control unit 90 controls the carriage motor 4M, suction pump 73, valve drive motor 76M, cap drive motor 77M, and switching mechanism 78, etc., to perform maintenance operations such as initial introduction to introduce ink to the inkjet head 1 and purging to discharge ink from the nozzles N. The control unit 90 also controls the transport motor 6M, carriage motor 4M, and driver IC 13, etc., to transport the paper 9 in the transport direction and perform printing operations to form an image by ejecting ink onto the paper 9 while moving the inkjet head 1 in the scanning direction.

[0060] ROM92 stores programs and data for the CPU91 to perform various control operations. RAM93 temporarily stores data used by the CPU91 when executing programs.

[0061] Next, the operation during the initial introduction of ink to the inkjet head 1 will be described below with reference to Figure 7(b). When introducing ink for the first time, the control unit 90 controls the carriage motor 4M to move the inkjet head 1 to the maintenance position. Next, the control unit 90 controls the cap drive motor 77M to bring the second cap 72 into close contact with the lower surface 3Y of the discharge unit 3. Then, the control unit 90 controls the valve drive motor 76M to open the on / off valve 3D with the on / off member 75.

[0062] Next, the control unit 90 controls the switching mechanism 78 and the suction pump 73, causing the switching mechanism 78 to enter a second communication state and driving the suction pump 73 to suck air from the sealed space K2. In this way, the sealed space K2 becomes negative pressure, causing the liquid (ink or clear liquid) initially filled into the flow path 35 of the inkjet head 1 to be discharged from the discharge port 3X. By discharging the liquid from the inkjet head 1, the ink from the ink cartridge 10A is introduced into the flow path 35 of the inkjet head 1 through the connecting flow path 41. Then, a predetermined amount of ink from the ink cartridge 10A is discharged from the discharge port 3X through the connecting flow path 41, the flow path 35, and the discharge flow path 3B, completing the initial introduction of ink to the inkjet head 1.

[0063] Next, the operation of moving the inkjet head 1 in the scanning direction during printing, thereby causing the ink in the flow path 35 of the inkjet head 1 to flow, will be explained below with reference to Figure 8.

[0064] Aside from the initial ink introduction and purging operations (for example, during printing), when moving the inkjet head 1 in the scanning direction, the control unit 90 controls the carriage motor 4M to move the inkjet head 1 in the scanning direction. When the inkjet head 1 moves in the scanning direction, the opening / closing member 75 is separated from the opening / closing valve 3D, and the opening / closing valve 3D is closed. In other words, the discharge port 3X is closed by the opening / closing valve 3D (opening / closing mechanism).

[0065] When the inkjet head 1 moves in one direction of scanning, the tube 10B also moves in the same direction, causing the ink inside the tube 10B to flow. This flow of ink inside the tube 10B creates a large positive pressure in the ink inside the storage chamber 2A1, for example, when the ink inside the tube 10B tries to flow into the storage chamber 2A1. Since the sub-tank 2 is provided with a pressure absorption section 2E, the large positive pressure generated in the storage chamber 2A1 is absorbed to some extent by displacing the damper membrane 2C so that it becomes convex upward, as shown in Figure 8(a). As a result, the positive pressure generated in the ink inside the channel 35 when the ink in the connecting channel 41 tries to flow into the channel 35 remains within a predetermined range that does not damage the meniscus of the nozzle N.

[0066] Furthermore, since the flow path 35 and the discharge flow path 3B are in communication, positive pressure is also generated in the damper chamber 3B1. Since the discharge unit 3 is provided with a pressure absorption section 3E, the positive pressure generated in the damper chamber 3B1 is absorbed by displacing the damper membrane 3C so that it becomes convex upward. This displacement of the damper membrane 3C increases the volume of the damper chamber 3B1, causing the ink in the flow path 35 to flow into the discharge flow path 3B. In other words, when the ink in the flow path 35 flows into the discharge flow path 3B, the ink near the nozzle N also flows. As a result, the viscosity of the ink near the nozzle N can be suppressed. In addition, if the ink contains a settling component (a component that may settle, such as a pigment), this component is stirred to prevent settling.

[0067] When the inkjet head 1 moves to the other side in the scanning direction, the tube 10B also moves to the other side in the scanning direction, and the ink in the tube 10B flows. Due to this flow of ink in the tube 10B, for example, if the ink in the tube 10B tries to flow towards the ink cartridge 10A, the ink in the storage chamber 2A1 flows into the tube 10B, creating a large negative pressure in the ink in the storage chamber 2A1. As shown in Figure 8(b), the large negative pressure in the storage chamber 2A1 is absorbed to some extent by the displacement of the damper film 2C so that it becomes convex downwards. As a result, the amount of ink flowing from the flow path 35 into the storage chamber 2A1 is reduced, and the negative pressure in the ink in the flow path 35 is kept within a predetermined range that does not damage the meniscus of the nozzle N.

[0068] Furthermore, since the flow path 35 and the discharge flow path 3B are in communication, negative pressure is also generated in the damper chamber 3B1. The negative pressure generated in the damper chamber 3B1 is absorbed by the displacement of the damper membrane 3C so that it becomes convex downwards. This displacement of the damper membrane 3C reduces the volume of the damper chamber 3B1, causing the ink in the discharge flow path 3B to flow into the flow path 35. In other words, ink flow occurs in the flow path 35 as the ink in the discharge flow path 3B flows into the flow path 35, and the ink in the flow path 35 flows into the storage chamber 2A1, causing the ink near the nozzle N to flow as well. As a result, as described above, the viscosity of the ink near the nozzle N can be suppressed, and if the ink contains sedimentation components, these components are stirred and sedimentation is prevented.

[0069] Because the discharge unit 3 is equipped with a pressure absorption section 3E, it is possible to move the inkjet head 1 in the scanning direction to cause the ink in the flow path 35 to flow.

[0070] As described above, in the printer 100 of this embodiment, as the ink in tube 10B flows due to the movement of the inkjet head 1 in the scanning direction, the ink in the connecting channel 41 flows into the channel 35, and when the positive pressure generated in the ink in channel 35 is absorbed by the pressure absorption unit 3E, the ink in channel 35 flows to the discharge channel 3B. On the other hand, when the ink in the connecting channel 41 flows toward the ink cartridge 10A and the negative pressure generated in the ink in channel 35 is absorbed by the pressure absorption unit 3E, the ink in the discharge channel 3B flows into channel 35, and the ink in channel 35 flows to the connecting channel 41. In this way, when the pressure absorption unit 3E absorbs the pressure fluctuation of the ink in channel 35, ink flow occurs in channel 35, making it possible to suppress the viscosity increase of the ink near the nozzle N. In addition, since the discharge port 3X is closed when the inkjet head 1 moves in the scanning direction, it is possible to prevent ink from flowing out from the discharge port 3X. On the other hand, when introducing ink from the ink cartridge 10A into the flow path 35, the discharge port 3X is open, so the ink flows sequentially from the ink cartridge 10A to the connecting flow path 41, flow path 35, and discharge flow path 3B. In other words, it is possible to supply ink from the ink cartridge 10A to the flow path 35 through a single path, and since uneven ink flow does not occur in the two paths, it is possible to suppress wasted ink discharge when introducing ink.

[0071] A pressure absorption section 2E is provided in the sub-tank 2. This makes it possible to suppress the application of large pressure to the ink in the flow path 35 due to the flow of ink in the tube 10B accompanying the movement of the inkjet head 1 in the scanning direction. As a result, it is possible to suppress ink leakage from the nozzle N.

[0072] Furthermore, even if the maximum inertial pressure generated by the flow of ink in tube 10B as the inkjet head 1 moves in the scanning direction is greater than the meniscus pressure resistance of nozzle N, the compliance of pressure absorption section 2E is greater than that of pressure absorption section 3E, so the pressure effect of the maximum inertial pressure on the ink in the flow path 35 can be effectively attenuated. Consequently, it becomes possible to keep the pressure fluctuations of the ink in the flow path 35 within a predetermined range that does not damage the meniscus. Therefore, it is possible to prevent ink from leaking out of nozzle N.

[0073] The damper membranes 2C and 3C are positioned above the storage chamber 2A1 and the damper chamber 3B1. This allows the damper membranes 2C and 3C to be attached from the same direction, thus simplifying the manufacturing process.

[0074] The damper films 2C and 3C are made from the same material. This makes it possible to form the damper films 2C and 3C simultaneously, simplifying the manufacturing process.

[0075] The flow path 35 of the inkjet head 1 includes multiple pressure chamber flow paths 21, each communicating with a plurality of nozzles N, an upper common flow path 31, a lower common flow path 32, and for each pressure chamber flow path 21, an inflow flow path 24 connecting the upper common flow path 31 to the pressure chamber flow path 21 and an outflow flow path 25 connecting the lower common flow path 32 to the pressure chamber flow path 21. As a result, ink flow occurs in each pressure chamber flow path 21 in accordance with the ink flow in the flow path 35 when the pressure absorption section 3E absorbs pressure fluctuations of the ink in the flow path 35. Therefore, it is possible to suppress the viscosity increase of the ink near the nozzles N that communicate with each pressure chamber flow path 21.

[0076] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are possible as long as they are within the scope of the claims.

[0077] The pressure absorption section 2E is not required. Furthermore, the compliance of the pressure absorption section 3E may be greater than or equal to that of the pressure absorption section 2E. The pressure absorption section 2E may function as an air damper using air stored in the storage chamber 2A1. The pressure absorption section 3E may function as an air damper using air stored in the damper chamber 3B1. In these cases, the damper membranes 2C and 3C are not required.

[0078] The sub-tank 2 and the discharge unit 3 do not have to be integrally formed. The sub-tank 2 does not have to be provided. Also, the discharge unit 3 does not have to be arranged to be movable in the scanning direction together with the inkjet head 1. In other words, the pressure absorption unit 3E can be located anywhere within the housing 100A as long as it is in communication with the discharge port 32X of the flow path 35 of the inkjet head 1.

[0079] The damper membrane 2C and the damper membrane 3C may be composed of separate components. Furthermore, the damper membrane 2C and the damper membrane 3C may be arranged in different directions relative to the storage chamber 2A1 and the damper chamber 3B1.

[0080] The common channel 30 may consist of two common channels arranged side by side in the scanning direction. Furthermore, the upper common channel 31 and the lower common channel 32 do not necessarily have to be connected to each other by a connecting channel 33.

[0081] Furthermore, the pressure chamber passage 21 may be composed of a pressure chamber 22. In other words, the pressure chamber 22 and the nozzle N may be directly connected. In this case, it is desirable that the outlet passage 25 communicates with the connection point between the pressure chamber 22 and the nozzle N. Alternatively, the pressure chamber 22 and the nozzle N may communicate via the outlet passage 25.

[0082] The opening and closing mechanism of the present invention may consist of a solenoid valve instead of the opening and closing valve 3D. In other words, the opening and closing mechanism can have any configuration as long as it can open and close the outlet 3X.

[0083] The introduction mechanism of the present invention may be a liquid pump provided in the middle of the tube 10B. In other words, the introduction mechanism can have any configuration as long as it can introduce the ink from the ink cartridge 10A into the flow path 35 of the inkjet head 1. Alternatively, a liquid tank capable of storing liquid may be provided instead of the ink cartridge 10A.

[0084] In the above-described embodiment, the electrodes constituting the actuator 12X have a two-layer configuration including individual electrodes and a common electrode, but they may also have a three-layer configuration. For example, a three-layer configuration includes a drive electrode to which high potential and low potential are selectively applied, a high-potential electrode that is held at a high potential, and a low-potential electrode that is held at a low potential.

[0085] Although the liquid dispensing device of the present invention is used in monochrome printers, it may also be used in color printers. In this case as well, the same effects as described above can be obtained.

[0086] The object from which the liquid is dispensed is not limited to paper. For example, the object from which the liquid is dispensed may be cloth, a substrate, or plastic.

[0087] The liquid dispensed from the nozzle is not limited to ink. For example, the liquid may be a processing solution that causes components in the ink to coagulate or precipitate.

[0088] The present invention is not limited to printers, but is also applicable to facsimile machines, copiers, and multifunction devices. Furthermore, the present invention is also applicable to liquid dispensing devices used for purposes other than image recording. For example, the present invention is applicable to liquid dispensing devices that dispense conductive liquid onto a substrate to form conductive patterns. [Explanation of Symbols]

[0089] 1. Inkjet head 2A1 Storage Room 2C damper membrane 2E Pressure Absorption Section 3B Discharge channel 3B1 Damper Room 3C damper membrane 3D valve (part of the opening / closing mechanism) 3E Pressure Absorption Section 3X outlet 4 Moving mechanism 10A Ink Cartridge 10B Tube 10B1 Extension part 21 Pressure chamber flow path 24 Inflow channel 25 Outlet channel 30 Common channel 31 Upper common channel 32 Lower common channel 35 channels 41 Connection channel 72. Second cap (part of the introduction mechanism) 73. Suction pump (part of the introduction mechanism) 75 Opening / closing member (part of the opening / closing mechanism) 76. Lifting mechanism (part of the opening / closing mechanism) 78. Switching mechanism (part of the introduction mechanism) 90 Control Unit N Nozzle

Claims

1. A liquid discharge head having a liquid flow path including a nozzle, A moving mechanism for moving the liquid discharge head in the scanning direction, A liquid tank in which liquid is stored, A first connecting channel that connects one end of the liquid channel to the liquid tank, A second connecting channel having one end connected to the other end of the liquid channel, An opening / closing mechanism that can open and close the discharge port, which is the other end of the second connecting channel, An introduction mechanism for introducing the liquid in the liquid tank into the liquid channel via the first connecting channel, The system comprises a control unit that controls the moving mechanism, the opening and closing mechanism, and the introduction mechanism, The first connecting channel has an extended portion that extends in the scanning direction, and this extended portion is defined by a tube that moves in the scanning direction together with the liquid discharge head. The second connecting channel has a first pressure absorption section that absorbs pressure fluctuations of the liquid in the liquid channel caused by the flow of the liquid in the tube as the liquid discharge head moves in the scanning direction, The liquid dispensing device is characterized in that the control unit closes the discharge port with the opening / closing mechanism when the moving mechanism moves the liquid dispensing head in the scanning direction, and opens the discharge port with the opening / closing mechanism when the introduction mechanism introduces the liquid from the liquid tank into the liquid flow path.

2. The liquid discharge device according to claim 1, wherein the first connecting channel is a second pressure absorbing section disposed between the extended portion and the liquid channel, and the second pressure absorbing section absorbs pressure fluctuations of the liquid in the liquid channel caused by the flow of the liquid in the tube accompanying the movement of the liquid discharge head in the scanning direction.

3. The liquid discharge device according to claim 2, characterized in that the second pressure absorption section has a compliance greater than that of the first pressure absorption section.

4. The first pressure absorption section includes a first damper chamber that constitutes the first connecting channel and a first damper membrane that constitutes the wall of the first damper chamber. The second pressure absorption section comprises a second damper chamber that constitutes the second connecting channel and a second damper membrane that constitutes the wall of the second damper chamber. The liquid dispensing device according to claim 3, characterized in that the first damper membrane and the second damper membrane are arranged in one of the first damper chambers and the second damper chamber.

5. The liquid dispensing device according to claim 4, characterized in that the first damper membrane and the second damper membrane are made of the same material.

6. The aforementioned liquid channel is A plurality of pressure chamber passages are arranged in an orthogonal direction perpendicular to both the vertical direction perpendicular to the scanning direction and the scanning direction, and each of the plurality of nozzles communicates with a plurality of pressure chamber passages, The system further includes a common channel that communicates with the aforementioned plurality of pressure chamber channels, The common flow path comprises an upper common flow path and a lower common flow path that extend in the orthogonal direction and overlap in the vertical direction, the upper common flow path communicating with one end of the liquid flow path and the lower common flow path communicating with the other end of the liquid flow path. The liquid discharge device according to any one of claims 1 to 5, characterized in that, between the common flow path and the plurality of pressure chamber flow paths, a first communicating flow path is provided for each pressure chamber flow path, which connects the upper common flow path and the pressure chamber flow path, and a second communicating flow path is provided, which connects the pressure chamber flow path and the lower common flow path.

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