Liquid ejection apparatus

Abstract

To provide a liquid ejection apparatus capable of reducing a consumption amount of liquid and stirring the liquid to suppress sedimentation of components in the liquid.SOLUTION: A liquid ejection apparatus comprises: a plurality of nozzles N which eject liquid; a common liquid chamber SR which communicates with the plurality of nozzles N; a liquid storage part which stores liquid; a supply flow path for supplying the liquid from the liquid storage part to the common liquid chamber SR; a differential pressure valve mechanism 130 which is disposed in middle of the supply flow path; and a first liquid chamber 121 which is disposed between the differential pressure valve mechanism 130 and the common liquid chamber SR in the supply flow path and in which a portion of the wall surface is defined by a first flexible member 123. Maintenance that causes liquid to flow in a portion between the differential pressure valve mechanism 130 and the first liquid chamber 121 is executed by deforming the first flexible member 123.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a liquid ejecting apparatus having a liquid ejecting head that ejects liquid from nozzles, and more particularly to an ink jet recording apparatus that ejects ink as the liquid. [Background technology]

[0002] 2. Description of the Related Art A liquid ejecting apparatus, typified by an ink jet recording apparatus such as an ink jet printer, is equipped with a liquid ejecting head capable of ejecting liquid, such as ink, stored in a cartridge, a tank, or the like, in the form of droplets.

[0003] A liquid ejection head ejects droplets from a nozzle by generating a pressure change in the liquid using a pressure generating means such as a piezoelectric actuator or a heating element. Also, a liquid ejection device equipped with a differential pressure valve mechanism for applying negative pressure to the liquid in the nozzle has been proposed (for example, see Patent Document 1).

[0004] The differential pressure valve mechanism opens due to the pressure difference with atmospheric pressure when the pressure of the liquid in the downstream flow path drops, allowing liquid to flow from upstream to downstream, and closes when the pressure of the liquid in the downstream flow path reaches a predetermined level or higher, stopping the supply of liquid, thereby applying negative pressure to the liquid in the nozzle. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-94579 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, there have been cases where coloring materials such as pigments contained in the liquid have settled in the flow path downstream of the differential pressure valve mechanism. Therefore, in order to eliminate the settling of the liquid in the flow path downstream of the differential pressure valve mechanism, it is necessary to discharge the liquid from the nozzle by suction cleaning or the like, which sucks the liquid from the nozzle, in an amount equal to or greater than the volume of the flow path from the differential pressure valve mechanism to the nozzle, which poses the problem of a large amount of liquid being consumed to restore the settled state.

[0007] Such problems exist not only in ink jet recording apparatuses, but also in liquid ejecting apparatuses that eject liquids other than ink. [Means for solving the problem]

[0008] An aspect of the present invention that solves the above problem is a liquid injection device comprising a plurality of nozzles for ejecting liquid, a common liquid chamber connected to the plurality of nozzles, a liquid storage section for storing liquid, a supply flow path for supplying liquid from the liquid storage section to the common liquid chamber, a differential pressure valve mechanism arranged midway through the supply flow path, and a first liquid chamber arranged in the supply flow path between the differential pressure valve mechanism and the common liquid chamber, and having a wall portion defined by a first flexible member, and characterized in that maintenance is performed by deforming the first flexible member to cause liquid to flow in the portion between the differential pressure valve mechanism and the first liquid chamber. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing a schematic configuration of a liquid ejecting apparatus according to a first embodiment. [Diagram 2] 1 is an exploded perspective view of a main part of a liquid jet module according to a first embodiment. [Diagram 3] 1 is a cross-sectional view of a main part of a liquid jet module according to a first embodiment. [Figure 4] FIG. 2 is a schematic diagram illustrating a gas flow path and a liquid flow path according to the first embodiment. [Diagram 5] FIG. 2 is a schematic diagram illustrating the internal configuration of a differential pressure valve mechanism according to the first embodiment. [Figure 6]3 is a schematic diagram illustrating an internal configuration of a pressure adjustment unit according to the first embodiment. FIG. [Figure 7] 1 is a cross-sectional view of a head chip according to a first embodiment. [Figure 8] FIG. 2 is a schematic diagram illustrating pressure cleaning according to the first embodiment. [Figure 9] FIG. 2 is a schematic diagram illustrating pressure cleaning according to the first embodiment. [Figure 10] FIG. 2 is a schematic diagram illustrating the maintenance according to the first embodiment. [Figure 11] FIG. 11 is a schematic diagram illustrating the maintenance according to the second embodiment. [Figure 12] FIG. 11 is a schematic diagram illustrating the maintenance according to the second embodiment. [Figure 13] FIG. 11 is a schematic diagram illustrating the maintenance according to the second embodiment. [Figure 14] FIG. 11 is a schematic diagram illustrating the maintenance according to the third embodiment. [Figure 15] FIG. 11 is a schematic diagram illustrating the maintenance according to the third embodiment. [Figure 16] FIG. 11 is a schematic diagram illustrating the maintenance according to the third embodiment. [Figure 17] FIG. 11 is a schematic diagram illustrating a maintenance method according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in detail below based on an embodiment. However, the following description shows one aspect of the present invention, and can be arbitrarily modified within the scope of the present invention. In each drawing, the same reference numerals indicate the same members, and the description is omitted as appropriate. In each drawing, X, Y, and Z represent three spatial axes that are mutually orthogonal. In this specification, the directions along these axes are defined as the X direction, the Y direction, and the Z direction. The direction in which the arrow in each drawing points is defined as the positive (+) direction, and the opposite direction to the arrow is defined as the negative (-) direction. The Z direction indicates the vertical direction, the +Z direction indicates the vertical downward direction, and the -Z direction indicates the vertical upward direction. Furthermore, the directions of the three spatial axes that are not limited to the positive and negative directions are defined as the X-axis direction, the Y-axis direction, and the Z-axis direction.

[0011] (Embodiment 1) FIG. 1 is a diagram showing a schematic configuration of a liquid ejecting apparatus 1 according to a first embodiment of the present invention.

[0012] 1 is an inkjet printing device that ejects ink, a type of "liquid," as droplets onto a medium S. The liquid ejection device 1 is a so-called line-type printing device in which a plurality of nozzles N that eject ink are distributed across the Y-axis direction, which is the width direction of the medium S, and printing is performed by ejecting ink from the nozzles N while transporting the medium S in the X-axis direction. The medium S can be made of any material, such as recording paper, resin film, or cloth.

[0013] As shown in the figure, the liquid ejection device 1 is equipped with a liquid storage section 8 that stores ink, which is a liquid. Examples of the liquid storage section 8 include a cartridge that can be attached to and detached from the liquid ejection device 1, a bag-shaped ink pack formed of a flexible film, and an ink tank that can be refilled with ink. Note that the liquid storage section 8 stores, for example, a plurality of types of ink with different colors, components, and the like. Although FIG. 1 illustrates one liquid storage section 8, a plurality of liquid storage sections 8 may be provided according to the type of ink. The liquid storage section 8 may be divided into a main tank and a sub-tank. The sub-tank may be connected to the liquid ejection module M, and ink consumed by ejecting ink droplets from the liquid ejection module M may be refilled from the main tank to the sub-tank. Although not particularly shown in the figure, the liquid ejection device 1 has a pressure-feeding means for pressure-feeding the ink in the liquid storage section 8 toward the liquid ejection module M. Examples of the pressure-feeding means include a pressing means for pressing the liquid storage section 8 from the outside, a pressure pump, and the like. The pressure-feeding means may use a head pressure difference generated by adjusting the relative positions of the liquid storage section 8 and the liquid jet module M in the vertical direction.

[0014] The liquid ejection device 1 includes a control unit 2, a transport mechanism 3, a liquid ejection module M, and a housing 4.

[0015] The control unit 2 controls the operation of each element of the liquid ejection device 1. The control unit 2 includes, for example, a control device such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and a storage device such as a semiconductor memory. The control unit 2 also includes a power supply device that supplies power supplied from an external power source such as a commercial power source to each element of the liquid ejection device 1. The control unit 2 is electrically connected to the liquid ejection module M via external wiring (not shown). The control unit 2 comprehensively controls each element of the liquid ejection device 1 by the control device executing a program stored in the storage device.

[0016] The transport mechanism 3 transports the medium S in the X-axis direction under the control of the control unit 2. The transport mechanism 3 includes a transport roller 3a and a motor (not shown) that rotates the transport roller 3a, and transports the medium S in the X-axis direction as the transport roller 3a rotates. Note that the transport mechanism 3 that transports the medium S is not limited to one that includes the transport roller 3a, and may transport the medium S by, for example, a belt or a drum.

[0017] The liquid ejection module M ejects ink supplied from the liquid storage section 8 from each of the nozzles N in the +Z direction under the control of the control unit 2. The liquid ejection module M has a shape with the Y-axis direction as the longitudinal direction and the X-axis direction as the transverse direction when viewed in the Z-axis direction, and is a line head having a plurality of liquid ejection heads H arranged so that the plurality of nozzles N are distributed over the entire range of the medium S in the Y-axis direction. The plurality of liquid ejection heads H are arranged in a straight line along the Y-axis direction. Of course, the arrangement of the plurality of liquid ejection heads H is not limited to this, and may be arranged in a staggered manner along the Y-axis direction, for example. Here, staggered arrangement of the liquid ejection heads H along the Y-axis direction means that the liquid ejection heads H arranged in parallel in the Y-axis direction are arranged alternately with a shift in the X-axis direction. In other words, two rows of liquid ejection heads H arranged in parallel in the Y-axis direction are arranged in parallel in the X-axis direction, and one of the two rows of liquid ejection heads H is arranged with a half pitch shift in the Y-axis direction.

[0018] The liquid jet module M is supported by a support body 5. The support body 5 is a plate-like member made of metal or the like, and has a mounting hole 5a penetrating in the Z-axis direction for mounting the liquid jet module M. The liquid jet module M is fixed to the mounting hole 5a of the support body 5 by screwing or the like with the nozzle N exposed in the +Z direction.

[0019] The liquid ejection device 1 may have a maintenance mechanism used for maintenance operations of the liquid ejection module M. The maintenance operations include, for example, a flushing operation and a nozzle cleaning operation. The flushing operation is an operation in which ink that does not directly contribute to image formation is forcibly ejected from the multiple nozzles N. The nozzle cleaning operation is an operation in which ink inside the liquid ejection module M is forcibly discharged from the multiple nozzles N by applying pressure from the upstream side of the liquid ejection module M or by suction from the downstream side. The maintenance mechanism has, for example, a flushing box that receives ink ejected from each nozzle N by the flushing operation, and a cap that covers the multiple nozzles N when the nozzle cleaning operation is performed.

[0020] Furthermore, the liquid ejection device 1 is provided with a first pump 6 and a second pump 7 that send gas, in this embodiment, air, to the liquid ejection head H. The first pump 6 supplies air to the liquid ejection module M via a first gas supply tube 6a, and the second pump 7 supplies air to the liquid ejection module M via a second gas supply tube 7a. In addition, the first pump 6 and the second pump 7 in this embodiment also function as suction pumps that can suck in gas. Of course, both a supply pump and a suction pump may be provided and used by switching between them.

[0021] As also shown in FIG. 4, the liquid ejection device 1 includes a first branched passage 6b branched from the first gas supply tube 6a between the first pump 6 and the liquid ejection module M. The end of the first branched passage 6b opposite to the branched portion is open to the atmosphere. A first valve 6c for opening and closing the first branched passage 6b is provided in the middle of the first branched passage 6b. The first valve 6c is configured to be switchable between an open state that allows air to flow in the first branched passage 6b and a closed state that inhibits air to flow in the first branched passage 6b. The liquid ejection device 1 also includes a second branched passage 7b branched from the second gas supply tube 7a between the second pump 7 and the liquid ejection module M. The end of the second branched passage 7b opposite to the branched portion is open to the atmosphere. A second valve 7c for opening and closing the second branched passage 7b is provided in the middle of the second branched passage 7b. The second valve 7c is configured to be switchable between an open state in which the air flow in the second branch passage 7b is permitted and a closed state in which the air flow in the second branch passage 7b is inhibited.

[0022] FIG. 2 is an exploded perspective view of the main parts of the liquid jet module M. FIG. 3 is a cross-sectional view of the main parts of the liquid jet module M. FIG. 4 is a schematic diagram illustrating the gas flow path and the liquid flow path in the liquid jet module M. FIG. 5 is a schematic diagram illustrating the internal configuration of the differential pressure valve mechanism 130. FIG. 6 is a schematic diagram illustrating the internal configuration of the pressure adjustment unit 20. Each direction of the liquid jet module M will be explained based on the directions when it is mounted on the liquid jet device 1, that is, the X-axis direction, the Y-axis direction, and the Z-axis direction.

[0023] As shown in Figures 2 and 3, the liquid ejection module M includes a flow path member 10 in which a flow path is formed, a pressure adjustment unit 20 that adjusts the pressure of the ink flowing therethrough, a circuit board 30, a holding member 40 that houses the pressure adjustment unit 20 and the circuit board 30 therein, and a liquid ejection head H attached to the underside facing the +Z direction of a base 42 that forms the bottom surface of the holding member 40.

[0024] The flow path member 10 is a plate-like member made of resin or the like that supplies ink to each liquid jet head H, and as shown in FIG. 4, an upper liquid flow path 100 that constitutes a part of the liquid flow path through which ink flows, and upper gas flow paths 101 and 102 that constitute a part of the gas flow path through which air flows are formed inside. As shown in FIG. 2, a plurality of liquid supply tube connection parts 11, four in this embodiment, are formed on the surface facing the -Z direction of this flow path member 10 to which one end of an ink supply tube 8a, one end of which is connected to a liquid storage part 8 corresponding to each color, is connected to the other end. The liquid supply tube connection part 11 is communicated with a liquid outlet 12 formed on the lower surface of the flow path member 10 via the upper liquid flow path 100 inside the flow path member 10. The upper liquid flow path 100 in this embodiment is branched midway so that ink flowing in from one liquid supply tube connection part 11 is distributed to four liquid jet heads H, and is communicated with four liquid outlets 12. That is, one liquid supply tube connection portion 11 communicates with four liquid outlet ports 12 via the upper liquid flow passage 100 .

[0025] 2, a gas supply tube connection portion 13 to which the first gas supply tube 6a and the second gas supply tube 7a are connected is formed on the surface of the flow path member 10 facing the -Z direction. The gas supply tube connection portion 13 connected to the first gas supply tube 6a is connected to a gas outlet 14 formed on the surface of the flow path member 10 facing the +Z direction via a first upper gas flow path 101 inside the flow path member 10. The gas supply tube connection portion 13 connected to the second gas supply tube 7a is connected to a gas outlet 14 formed on the surface of the flow path member 10 facing the +Z direction via a second upper gas flow path 102 inside the flow path member 10. The first upper gas flow path 101 and the second upper gas flow path 102 are each branched midway and connected to four gas outlets 14. That is, one gas supply tube connection part 13 communicates with the four gas outlets 14 via the first upper gas flow passage 101. The other gas supply tube connection part 13 communicates with the four gas outlets 14 via the second upper gas flow passage 102. The flow passage member 10 of this embodiment is placed on a surface facing the -Z direction of a cover 43 described later.

[0026] In this embodiment, a plurality of gas outlets 14 (eight in this embodiment) are formed along the Y-axis direction of the flow path member 10 at approximately the center in the X-axis direction of the flow path member 10. Moreover, the liquid outlets 12 in this embodiment are arranged in parallel along the Y-axis direction on both sides in the X-axis direction of the row of gas outlets 14. That is, two rows in which eight liquid outlets 12 are arranged are formed with the row of gas outlets 14 in between. Moreover, the liquid outlets 12 and the gas outlets 14 in this embodiment are formed in a cylindrical shape and are provided to protrude in the -Z direction from a surface of the flow path member 10 facing the -Z direction.

[0027] The pressure adjustment unit 20 is made of resin or the like arranged on the surface side of the flow path member 10 facing the +Z direction with a cover 43 described later sandwiched therebetween. A plurality of liquid inlets 21 corresponding to the liquid outlets 12 of the flow path member 10 and a plurality of gas inlets 22 corresponding to the gas outlets 14 of the flow path member 10 are formed on the surface of the pressure adjustment unit 20 facing the -Z direction. As shown in FIG. 3, the connection portion between the liquid outlets 12 and the liquid inlets 21 and the connection portion between the gas outlets 14 and the gas inlets 22 are connected on the +Z direction side of the cover 43, that is, in the storage space 41 described later. In addition, a lower liquid flow path 103 is formed inside the pressure adjustment unit 20 as shown in FIG. 4. The liquid inlet 21 is connected to a liquid outlet pipe 23 protruding downward from the pressure adjustment unit 20 via the lower liquid flow path 103. Furthermore, a first lower gas flow path 104 and a second lower gas flow path 105 are formed inside the pressure adjustment unit 20. The gas outlet 14 communicating with the first upper gas passage 101 is connected to a choke chamber 110 (described later) via a first lower gas passage 104. The gas outlet 14 communicating with the second upper gas passage 102 is connected to a buffer chamber 120 (described later) via a second lower gas passage 105.

[0028] 4, ink from the liquid storage section 8 passes through the ink supply tube 8a, the upper liquid flow path 100, and the lower liquid flow path 103, and is discharged from the liquid outlet pipe 23 protruding downward from the pressure adjustment unit 20 to the liquid ejection head H side. On the other hand, air from the first pump 6 passes through the first gas supply tube 6a, the first upper gas flow path 101, and the first lower gas flow path 104 to a buffer chamber 120 formed in the middle of the lower liquid flow path 103. In addition, air from the second pump 7 passes through the second gas supply tube 7a, the second upper gas flow path 102, and the second lower gas flow path 105 to a choke chamber 110 formed in the middle of the lower liquid flow path 103.

[0029] 4, a differential pressure valve mechanism 130, a choke chamber 110, and a buffer chamber 120 are formed in the lower liquid flow path 103 in this order from the upstream side. The differential pressure valve mechanism 130 is a type of negative pressure generating means that maintains the interior of the lower liquid flow path 103 in the pressure adjustment unit 20 at a predetermined negative pressure.

[0030] Here, as shown in FIG. 5, the differential pressure valve mechanism 130 includes a valve mechanism body 131, a valve body 132, a film 133, and a coil spring 134.

[0031] The valve mechanism body 131 is made of, for example, a resin material. The valve mechanism body 131 has a downstream chamber 135, an upstream chamber 136, a communication passage 137, and a through hole 138. The valve mechanism body 131 also has a partition wall 131a that separates the downstream chamber 135 and the upstream chamber 136 and in which the through hole 138 is formed.

[0032] The downstream chamber 135 has a concave shape that opens to one side of the valve mechanism body 131. The upstream chamber 136 is provided inside the valve mechanism body 131, and communicates with the liquid storage section 8 side of the lower liquid flow path 103. The upstream chamber 136 and the downstream chamber 135 communicate with each other via a through hole 138. A communication passage 137 communicates between the downstream chamber 135 and the liquid jet head H side of the lower liquid flow path 103. The opening of the downstream chamber 135 is sealed by a flexible film 133 fixed to the surface of the valve mechanism body 131.

[0033] The valve body 132 includes a shaft portion 132a and a valve seat 132b that is integrally provided on one end side of the shaft portion 132a. The valve body 132 has the shaft portion 132a inserted into the through hole 138 so that the valve seat 132b is disposed in the upstream chamber 136 and the end side of the shaft portion 132a opposite to the valve seat 132b is disposed in the downstream chamber 135. That is, the shaft portion 132a has an outer diameter smaller than the inner diameter of the through hole 138. The end of the shaft portion 132a opposite to the valve seat 132b is disposed so as to abut against the film 133 via a pressure receiving plate 133a that is a thin metal plate fixed to the film 133. The tip of the shaft portion 132a may abut directly against the film 133 without the pressure receiving plate 133a. Such a valve seat 132b has an outer diameter larger than the inner diameter of the through hole 138. Furthermore, a coil spring 134 serving as a biasing member is provided between the surface of the valve seat 132b facing away from the film 133 and the wall surface of the upstream chamber 136, and the coil spring 134 biases the valve body 132 toward the film 133. The bias of the coil spring 134 causes the valve seat 132b of the valve body 132 to abut against the partition wall 131a, thereby blocking the opening of the through hole 138 and closing the through hole 138, thereby isolating the downstream chamber 135 and the upstream chamber 136. It is preferable that either the portion of the valve seat 132b abutting against the partition wall 131a or the portion of the partition wall 131a abutting against the valve seat 132b is made of an elastic material such as an elastomer.

[0034] When negative pressure acts within the downstream chamber 135, the film 133 deforms toward the downstream chamber 135 due to the pressure difference between the negative pressure within the downstream chamber 135 and the external air pressure outside the downstream chamber 135 separated by the film 133, and this deformation is transmitted to the valve body 132. That is, when a pressure difference that resists the biasing force of the coil spring 134 occurs between the negative pressure in the downstream chamber 135 and the external air pressure, the film 133 deforms toward the downstream chamber 135. As a result, the valve body 132 moves the valve seat 132b toward the partition wall 131a against the biasing force of the coil spring 134, and a gap is formed between the peripheral portion of the through hole 138 and the valve seat 132b, opening the downward liquid flow path 103, i.e., opening the valve.

[0035] As a result, ink from the liquid storage unit 8 is supplied toward the liquid jet head H through the lower liquid flow path 103. On the other hand, when ink is introduced from the liquid storage unit 8 and the internal pressure of the lower liquid flow path 103 rises, the film 133 bends in a direction away from the valve body 132, and the valve body 132 moves in the valve closing direction by the biasing force of the coil spring 134, closing the lower liquid flow path 103. That is, the differential pressure valve mechanism 130 closes the lower liquid flow path 103 in a normal state, and when the negative pressure in the downstream chamber 135 becomes equal to or lower than a predetermined pressure due to consumption of ink due to ejection by the liquid jet head H, it autonomously opens the lower liquid flow path 103 to introduce ink from the liquid storage unit 8 toward the liquid jet head H. In this embodiment, the film 133 corresponds to the "flexible member."

[0036] As shown in FIG. 6, the choke chamber 110 is a space connected to the liquid ejection head H side, which is the downstream side of the differential pressure valve mechanism 130, via a first connection flow path 106, which is a part of the lower liquid flow path 103. The downstream end of the first connection flow path 106 is opened to one surface of the choke chamber 110, which is the bottom surface, which is the lower surface in FIG. 6 in this embodiment. In addition, a second connection flow path 107, which is a part of the lower liquid flow path 103, is connected to the bottom surface of the choke chamber 110. The upstream end of the second connection flow path 107 is opened to the tip of a protruding portion 113 that protrudes cylindrically upward from the bottom surface of the choke chamber 110. Furthermore, the downstream end of the second lower gas flow path 105 is opened to the upper surface, which is the surface opposite to the bottom surface of the choke chamber 110. A second flexible member 114 made of a flexible material such as rubber or film is attached to the choke chamber 110 to separate a second liquid space 111, with which the first connecting flow path 106 and the second connecting flow path 107 communicate, from a second gas space 112, with which the first lower gas flow path 104 communicates. As a result, the second liquid space 111 partitioned by the second flexible member 114 in the choke chamber 110 becomes part of the lower liquid flow path 103 through which liquid flows, and the second gas space 112 partitioned by the second flexible member 114 in the choke chamber 110 becomes part of the gas flow path through which gas flows, which communicates with the second gas supply tube 7a.

[0037] The second flexible member 114 in this embodiment is fixed to the bottom surface of the choke chamber 110. The center of the second flexible member 114 is urged toward the upper surface of the choke chamber 110 by the second urging member 115 fixed to the bottom surface of the choke chamber 110. The second urging member 115 in this embodiment is wound around the protruding portion 113. As a result, when the second gas space 112 is not pressurized, for example, when the pressure is atmospheric pressure or a pressure close to atmospheric pressure, a gap is formed between the second flexible member 114 and the tip of the protruding portion 113 by the urging force of the second urging member 115, as shown by the solid line in FIG. 6, and the opening of the second connection flow path 107 on the choke chamber 110 side is opened. This allows the ink to flow into the buffer chamber 120 side. On the other hand, when the second gas space 112 is pressurized by driving the second pump 7, as shown by the dashed line in FIG. 6, the second flexible member 114 deforms toward the protruding portion 113 against the biasing force of the second biasing member 115 and abuts against the tip of the protruding portion 113. This blocks the opening of the second connection flow path 107 on the choke chamber 110 side, and inhibits the flow of ink into the buffer chamber 120 side. That is, the second flexible member 114 and the second biasing member 115 function as an opening / closing valve that switches the lower liquid flow path 103 upstream of the buffer chamber 120 between an open state that allows the flow of ink in the lower liquid flow path 103 and a closed state that inhibits the flow of liquid in the lower liquid flow path 103. In this embodiment, the second liquid space 111 of the choke chamber 110 corresponds to the "second liquid chamber."

[0038] As shown in FIG. 6, the buffer chamber 120 is a space connected to the downstream side of the choke chamber 110 via the second connection flow path 107. The downstream end of the second connection flow path 107 is opened to one side of the buffer chamber 120, which is the bottom surface, which is the lower surface in FIG. 6 in this embodiment. The third connection flow path 108 constituting the downstream part of the lower liquid flow path 103 is connected to the bottom surface of the buffer chamber 120. Furthermore, the downstream end of the first lower gas flow path 104 is opened to the other side of the buffer chamber 120, which is the top surface, which is the upper surface in FIG. 6 in this embodiment. The first flexible member 123 made of a flexible material such as rubber or film is attached to the buffer chamber 120 to separate a first liquid space 121, to which the second connection flow path 107 and the third connection flow path 108 communicate, from a first gas space 122, to which the first lower gas flow path 104 communicates. As a result, the first liquid space 121 partitioned by the first flexible member 123 in the buffer chamber 120 becomes part of the lower liquid flow path 103 through which liquid flows, and the first gas space 122 partitioned by the first flexible member 123 in the buffer chamber 120 becomes part of the gas flow path through which gas flows, connected to the first gas supply tube 6a.

[0039] In this embodiment, the first flexible member 123 is fixed to the bottom surface of the buffer chamber 120. The center of the first flexible member 123 is urged toward the upper surface of the buffer chamber 120 by a first biasing member 124 fixed to the opening edge of the third connection flow path 108 on the bottom surface of the buffer chamber 120. As a result, when the first gas space 122 is not pressurized, for example, when the pressure is atmospheric pressure or a pressure close to atmospheric pressure, the first flexible member 123 is pressed toward the upper surface side of the buffer chamber 120 by the biasing force of the first biasing member 124 as shown by the solid line in FIG. 6, and the volume of the first liquid space 121 becomes large. On the other hand, when the first gas space 122 is pressurized by the drive of the first pump 6, the first flexible member 123 is pressed toward the bottom surface side of the buffer chamber 120 against the biasing force of the first biasing member 124 as shown by the dashed line in FIG. 6, and the volume of the first liquid space 121 becomes small. That is, when the first flexible member 123 is deformed toward the bottom surface of the buffer chamber 120 due to pressurization of the first gas space 122, the first liquid space 121 is changed to a first volume shown by the dashed line in Fig. 6, whereas when the first flexible member 123 is deformed toward the top surface of the buffer chamber 120 due to depressurization of the first gas space 122, the first liquid space 121 is changed to a second volume larger than the first volume shown by the solid line in Fig. 6. In this embodiment, the first liquid space 121 of the buffer chamber 120 corresponds to the "first liquid chamber."

[0040] As shown in Fig. 3, the holding member 40 is a member in which an accommodation space 41 for accommodating the pressure adjustment unit 20 and the circuit board 30 is formed. The holding member 40 includes a highly rigid base 42 to which the pressure adjustment unit 20 and the circuit board 30 are attached on a surface facing the -Z direction and to which a plurality of liquid ejection heads H are fixed on a surface facing the +Z direction, and a cover 43 for covering the pressure adjustment unit 20 and the circuit board 30. The base 42 is formed of a plate-like member along the XY plane that is elongated in the Y-axis direction as shown in Fig. 2. A plurality of base through-holes 44 through which the liquid outflow pipes 23 of the pressure adjustment unit 20 are inserted are provided in the region of the base 42 to which the pressure adjustment unit 20 is fixed, penetrating the Z-axis direction. The liquid outflow pipes 23 of the pressure adjustment unit 20 are inserted and connected to the liquid ejection heads H by being inserted through the base through-holes 44.

[0041] Further, at one end of the base 42 in the X-axis direction, a step 45 is formed by lowering the surface of the base 42 facing the -Z direction by one step. The circuit board 30 is placed on the surface of the step 45 facing the -Z direction so as to fit along the side of the step 45, and is fixed by a circuit board fixing screw 46.

[0042] The cover 43 is formed of a hollow member that is elongated in the Y-axis direction and opens in the +Z direction so as to cover the pressure adjustment unit 20 and the circuit board 30 with a gap therebetween. The cover 43 is attached to the base 42 as shown in FIG. 3, and forms an accommodation space 41 between the cover 43 and the base 42. The cover 43 is fixed to the base 42 by cover fixing screws 47. The cover 43 is also provided with a first cover opening 48a through which the liquid outlet 12 of the flow path member 10 is inserted, a second cover opening 48b through which the gas outlet 14 of the flow path member 10 is inserted, and a third cover opening 48c through which the wiring member 31 is inserted. The wiring member 31 is inserted through the third cover opening 48c and connected to the circuit board 30.

[0043] The liquid ejection heads H are fixed to the surface facing the +Z direction of the holding member 40 in a line in the Y-axis direction with each being positioned relative to the other. The method of fixing the liquid ejection heads H to the holding member 40 is not particularly limited, and may be adhesion with an adhesive, screwing, or the like.

[0044] The liquid ejecting head H includes a plurality of head chips 200, a holder 400 that holds the plurality of head chips 200, and a cover head 500 that is provided on the surface side of the head chip 200 that faces the +Z direction.

[0045] Head chip 200 has nozzle surface 220a on which nozzles N are provided on a surface facing the +Z direction. In addition, the surfaces facing the -Z direction of a plurality of head chips 200 are bonded to a surface of holder 400 facing the +Z direction.

[0046] The holder 400 has a holding portion 401 that forms a groove-shaped space that opens on a surface facing the +Z direction. The holding portion 401 is provided continuously along the Y-axis direction on the +Z direction surface of the holder 400, and is provided with openings on both side surfaces in the Y-axis direction.

[0047] A plurality of head chips 200 are fixed in such holding portion 401 by an adhesive or the like. Note that a flow path and the like that supplies ink to head chip 200 are provided inside holder 400 (not shown). Such holder 400 may be configured by stacking a plurality of members in the Z-axis direction.

[0048] In addition, a plurality of head chips 200 are bonded in the holding portion 401 of the holder 400 in a line in the Y-axis direction. In this embodiment, six head chips 200 are bonded to one holder 400. Of course, the number of head chips 200 fixed to one holder 400 is not particularly limited to this, and one holder 400 may have one head chip 200 or two or more head chips 200. Incidentally, by providing a plurality of head chips 200 on one liquid ejection head H to achieve multiple nozzle rows, it is possible to improve the yield compared to the case where multiple nozzle rows are provided on only one head chip 200 of one liquid ejection head H to achieve multiple rows.

[0049] In addition, the multiple head chips 200 of this embodiment are fixed so that the nozzle row is inclined with respect to the X-axis direction, which is the transport direction of the medium S, in the XY plane, which is the in-plane direction of the nozzle surface 220a. That is, the Xa direction, which is the juxtaposition direction of the nozzles N constituting the nozzle row, is inclined with respect to the X-axis direction. In this embodiment, the liquid ejection head H has multiple head chips 200 arranged in the Y-axis direction, and at least a portion of the nozzles N of two head chips 200 adjacent to each other in the Y-axis direction are arranged at positions overlapping each other in the X-axis direction. Therefore, the nozzles N arranged in the Y-axis direction of the liquid ejection head H at the same intervals can be formed.

[0050] Cover head 500 corresponds to a fixing plate for relatively positioning multiple head chips 200. Cover head 500 is made of a plate-like member such as metal. Cover head 500 is provided on the nozzle surface 220a side of head chip 200, and covers an opening of holding part 401 facing the +Z direction. Cover head 500 is formed by bending both ends in the Y-axis direction of a flat plate-like member, and the bent ends cover the opening of holding part 401 in the Y-axis direction.

[0051] The cover head 500 is provided with exposure openings 501 which are through holes for exposing the nozzles N of each head chip 200. The exposure openings 501 are provided so as to open independently for each head chip 200.

[0052] The liquid jet head H of this embodiment has a shape that is approximately a parallelogram when viewed in a plan view in the +Z direction, as shown in Fig. 2. This is because, as described above, the Xa direction, which is the arrangement direction of the nozzles N that constitute the nozzle row of each head chip 200, is inclined with respect to the X-axis direction, which is the transport direction of the medium S, and the outer shape of the liquid jet head H is formed to be approximately a parallelogram in the same manner as the Xa direction, which is the inclination direction of the nozzle row. Of course, the shape of the liquid jet head H when viewed in a plan view in the +Z direction is not limited to an approximately parallelogram, and may be a rectangle, a trapezoid, a polygon, or the like.

[0053] By arranging a plurality of liquid ejection heads H in this manner to form the liquid ejection module M, it is possible to achieve effects such as improved manufacturing yield, ease of processing, and facilitating the flatness of the cover head 500.

[0054] An example of head chip 200 of this embodiment will be further described with reference to Fig. 7. Fig. 7 is a cross-sectional view of head chip 200.

[0055] As shown in the figure, the head chip 200 of this embodiment comprises multiple components such as a flow path forming substrate 210, a communication plate 215, a nozzle plate 220, a protective substrate 230, a compliance substrate 245, and a case 240, and these multiple components are joined together by an adhesive or the like.

[0056] In the flow path forming substrate 210 constituting the head chip 200, pressure chambers 212 partitioned by a plurality of partition walls are arranged in parallel along the direction in which a plurality of nozzles N are arranged in parallel by anisotropic etching from one side. In this embodiment, the direction in which the pressure chambers 212 are arranged in parallel coincides with the Xa direction. In addition, the flow path forming substrate 210 is provided with a plurality of rows in which the pressure chambers 212 are arranged in parallel in the Xa direction, two rows in this embodiment. The row direction in which the pressure chambers 212 are arranged in multiple rows of the pressure chambers 212 formed along the Xa direction is hereinafter referred to as the Ya direction. In addition, in this embodiment, the Xa direction and the direction perpendicular to the Ya direction coincide with the Z axis direction. In addition, the head chip 200 of this embodiment is mounted on the liquid ejecting head H so that the Xa direction, which is the direction in which the nozzles N are arranged in parallel, is inclined with respect to the X axis direction, which is the transport direction of the medium S.

[0057] The flow path forming substrate 210 may be provided with a supply path or the like at one end side of the pressure chamber 212 in the Ya direction, the supply path having an opening area narrower than that of the pressure chamber 212 and providing flow path resistance for the ink flowing into the pressure chamber 212.

[0058] Further, a communication plate 215 is bonded to a surface facing the +Z direction of the flow passage forming substrate 210. A nozzle plate 220 in which a plurality of nozzles N communicating with each pressure chamber 212 are provided is bonded to the communication plate 215.

[0059] The communicating plate 215 is provided with a nozzle communicating passage 216 that communicates between the pressure chamber 212 and the nozzle N. The communicating plate 215 has an area larger than that of the flow path forming substrate 210, and the nozzle plate 220 has an area smaller than that of the flow path forming substrate 210. By making the area of ​​the nozzle plate 220 relatively small in this manner, it is possible to reduce costs.

[0060] The communicating plate 215 is provided with a first manifold portion 217 and a second manifold portion 218 which constitute a part of a common liquid chamber SR communicating with the multiple nozzles N. The first manifold portion 217 is provided penetrating the communicating plate 215 in the Z-axis direction. The second manifold portion 218 is provided partway in the Z-axis direction, opening on the nozzle plate 220 side of the communicating plate 215, without penetrating the communicating plate 215 in the Z-axis direction.

[0061] Furthermore, in the communication plate 215, a supply communication passage 219 that communicates with one end of the pressure chamber 212 in the Ya axis direction is provided independently for each pressure chamber 212. The supply communication passage 219 communicates between the second manifold portion 218 and the pressure chamber 212.

[0062] Nozzles N are formed in the nozzle plate 220, which communicate with each pressure chamber 212 via nozzle communication passages 216. That is, the nozzles N that eject the same type of liquid, that is, ink, are arranged side by side in the Xa direction, and two rows of nozzles N arranged side by side in the Xa direction are formed in the Ya direction.

[0063] On the other hand, a vibration plate 250 is formed on the surface of the flow path forming substrate 210 facing the -Z direction, and a first electrode 260, a piezoelectric layer 270, and a second electrode 280 are laminated on the vibration plate 250 by film formation and lithography to form a piezoelectric actuator 300. In this embodiment, the piezoelectric actuator 300 is a pressure generating means that generates a pressure change in the ink in the pressure chamber 212. Here, the piezoelectric actuator 300 is also called a piezoelectric element, and refers to a portion including the first electrode 260, the piezoelectric layer 270, and the second electrode 280. In addition, a portion where a piezoelectric strain occurs in the piezoelectric layer 270 when a voltage is applied between the first electrode 260 and the second electrode 280 is called an active portion 310. In contrast, a portion where a piezoelectric strain does not occur in the piezoelectric layer 270 is called an inactive portion. In this embodiment, an active portion 310 is formed for each pressure chamber 212. In general, one of the electrodes of the active parts 310 is an individual electrode independent of the other active part 310, and the other electrode is a common electrode common to the multiple active parts 310. In this embodiment, the first electrode 260 constitutes an individual electrode, and the second electrode 280 constitutes a common electrode. Of course, the first electrode 260 may constitute a common electrode, and the second electrode 280 may constitute an individual electrode. From each electrode of such a piezoelectric actuator 300, a lead electrode 290, which is a lead wiring, is drawn out. The end of the lead electrode 290 opposite to the end connected to the piezoelectric actuator 300 is connected to a flexible wiring board 320. The wiring board 320 is made of a COF (Chip On Film) on which a driving circuit having a switching element for driving the piezoelectric actuator 300 is mounted.

[0064] A protective substrate 230 having approximately the same size as the flow path forming substrate 210 is bonded to the surface of the flow path forming substrate 210 facing the -Z direction. The protective substrate 230 has an actuator holding portion 231 which is a space for protecting the piezoelectric actuator 300. The actuator holding portion 231 is provided independently for each row of the piezoelectric actuators 300 arranged side by side in the +Xa direction, and two actuator holding portions 231 are arranged side by side in the Ya axis direction. The protective substrate 230 is provided with a through hole 232 penetrating in the Z axis direction between the two actuator holding portions 231 arranged side by side in the Ya axis direction. The end of the lead electrode 290 drawn from the electrode of the piezoelectric actuator 300 is extended so as to be exposed in the through hole 232, and the lead electrode 290 and the wiring (not shown) of the wiring substrate 320 are electrically connected in the through hole 232.

[0065] In addition, a case 240 that defines a common liquid chamber SR that communicates with the multiple pressure chambers 212 is fixed to the protective substrate 230 and the communication plate 215. The case 240 has approximately the same shape as the communication plate 215 described above in a plan view. The case 240 has a recess 241 that opens on a surface facing the +Z direction and has a depth that accommodates the flow path forming substrate 210 and the protective substrate 230. Then, in a state in which the flow path forming substrate 210 and the like are accommodated in the recess 241, the surface facing the +Z direction is sealed by the flow path forming substrate 210. The case 240 has a third manifold portion 242 on each side of the recess 241 in the Y-axis direction. The third manifold portion 242 is provided to open on the surface of the case 240 facing the +Z direction. A common liquid chamber SR is formed by the first manifold portion 217 and the second manifold portion 218 provided in the communication plate 215 and the third manifold portion 242 provided in the case 240. A total of two common liquid chambers SR are provided, one for each row of the pressure chambers 212. The common liquid chambers SR are provided continuously along the Xa direction in which the pressure chambers 212 are arranged.

[0066] Additionally, the case 240 is provided with inlets 243 that communicate with the common liquid chambers SR and supply ink to each common liquid chamber SR. In this embodiment, an inlet 243 is provided for each common liquid chamber SR. That is, two inlets 243 are provided in one head chip 200. Of course, the case 240 may also be provided with an outlet for discharging the ink in the common liquid chamber SR to the outside.

[0067] Further, a compliance substrate 245 is provided on the surface of the communication plate 215 facing the +Z direction. This compliance substrate 245 seals the openings in the +Z direction of the first manifold portion 217 and the second manifold portion 218. In this embodiment, the compliance substrate 245 includes a flexible sealing film 246 and a fixed substrate 247 made of a hard material such as metal or resin. Since the region of the fixed substrate 247 facing the common liquid chamber SR is an opening 248 that is completely removed in the thickness direction, one side of the common liquid chamber SR is a compliance portion 249 that is a flexible portion sealed only by the flexible sealing film 246.

[0068] Moreover, the cover head 500 is joined to the surface of this compliance substrate 245 opposite to the communication plate 215, that is, the surface facing the +Z direction.

[0069] In the head chip 200 configured as described above, when ink is ejected, ink is taken in from the liquid storage section 8 via the inlet 243, and the inside of the flow path from the common liquid chamber SR to the nozzle N is filled with ink. Thereafter, in accordance with a signal from the drive circuit, a voltage is applied to each active section 310 corresponding to the pressure chamber 212, thereby deflecting and deforming the vibration plate 250 together with the active section 310. This increases the pressure of the ink in the pressure chamber 212, and the ink is ejected from the nozzle N as droplets.

[0070] In this embodiment, the ink supply tube 8a, the liquid supply tube connection portion 11 of the flow path member 10, the upper liquid flow path 100 and the liquid outlet port 12, the liquid inlet port 21, the lower liquid flow path 103 and the liquid outlet tube 23 of the pressure adjustment unit 20, the flow path (not shown) of the holder 400 of the liquid ejection head H, and the inlet port 243 of the head chip 200 correspond to the "supply flow path".

[0071] Here, the pressure cleaning performed by the liquid ejecting apparatus 1 of the present embodiment will be described with reference to Figures 8 and 9. Figures 8 and 9 are schematic diagrams for explaining the pressure cleaning.

[0072] In this embodiment, the volume of the second liquid space 111 in a state where the second gas space 112 of the choke chamber 110 is not pressurized, for example, where the pressure is atmospheric pressure or close to atmospheric pressure, is referred to as the second reference volume. Also, the volume of the first liquid space 121 in a state where the first gas space 122 of the buffer chamber 120 is at atmospheric pressure or close to atmospheric pressure is referred to as the first reference volume.

[0073] First, as shown in Fig. 8, a first pressurized cleaning step is performed in which the second flexible member 114 is deformed so as to close the second liquid space 111. Specifically, the control unit 2 controls the second pump 7 to supply gas, in this embodiment, air, to the second gas space 112 while the second valve 7c is closed. As a result, the second flexible member 114 deforms toward the protruding portion 113 against the biasing force of the second biasing member 115 and comes into contact with the tip of the protruding portion 113. As a result, the opening of the second connection flow path 107 on the choke chamber 110 side is blocked, and the second liquid space 111 is blocked.

[0074] By carrying out this first pressurized cleaning step, the film 133 is deformed so that the volume of the downstream chamber 135 of the differential pressure valve mechanism 130 increases, and the compliance portion 249 is deformed so that the volume of the common liquid chamber SR of the head chip 200 increases.

[0075] 9, a second pressurized cleaning process is performed in which the first flexible member 123 is deformed so that the volume of the first liquid space 121 of the buffer chamber 120 becomes smaller than the first reference volume. Specifically, the control unit 2 controls the first pump 6 to supply gas, in this embodiment, air, to the first gas space 122 with the first valve 6c closed. This causes the first flexible member 123 to deform toward the bottom side of the buffer chamber 120 against the biasing force of the first biasing member 124. In this embodiment, the volume of the first liquid space 121 by the second pressurized cleaning process is referred to as a first pressurized cleaning volume.

[0076] In the second pressurized cleaning step, since the second liquid space 111 of the choke chamber 110 is blocked in the first pressurized cleaning step, the ink discharged due to the volume of the first liquid space 121 of the buffer chamber 120 becoming smaller than the first reference volume is supplied toward the liquid ejection head H. At this time, the ink discharged from the first liquid space 121 deforms the compliance section 249 to its allowable limit, and then the ink is discharged to the outside from the nozzle N. In other words, the ink in the nozzle N has a positive pressure relative to the outside air pressure. Thereafter, the nozzle surface 220a is wiped with a wiper or the like (not shown). At this time, since the ink in the nozzle N is at a positive pressure, it is possible to prevent foreign matter such as air bubbles and dust attached to the nozzle surface 220a from entering the nozzle N by wiping. Then, the control unit 2 controls the second pump 7 to release the pressurization of the second gas space 112 and the second valve 7c to open the second gas space 112 to the atmosphere, so that the second flexible member 114 moves to the ceiling side of the choke chamber 110 by the biasing force of the second biasing member 115, and the blockage of the second liquid space 111 of the choke chamber 110 is released. After that, the control unit 2 controls the first pump 6 to release the pressurization of the first gas space 122 and the first valve 6c to open the first gas space 122 to the atmosphere, so that the first flexible member 123 moves to the ceiling side of the buffer chamber 120 by the force of the first biasing member 124, and the volume of the first liquid space 121 returns to the first reference volume. As a result, ink is supplied from the upstream side to the first liquid space 121, and a meniscus is formed in the nozzle N. In this manner, pressurized cleaning is performed by pressurizing the first gas space 122 and the second gas space 112 using the first pump 6 and the second pump 7, and opening the first gas space 122 and the second gas space 112 to the atmosphere.

[0077] In such pressurized cleaning, since ink flows from the first liquid space 121 of the buffer chamber 120 to the nozzle N, the ink is stirred and the settling of the pigment and other components contained in the ink can be suppressed to some extent. However, since the volume of the first liquid space 121 of the buffer chamber 120 is not repeatedly changed, the ink is not sufficiently stirred. In addition, since ink does not flow from the first liquid space 121 to the upstream side, i.e., the second liquid space 111 and the downstream chamber 135, in the pressurized cleaning, there is a risk of ink settling in these areas. Therefore, although the unevenness in shading of the printed matter can be suppressed at the beginning of printing by only performing pressurized cleaning, there is a risk of the unevenness in shading occurring halfway through printing. In order to suppress such unevenness in shading, if a conventional suction cleaning is performed by sucking ink from the nozzle N, the ink from the nozzle N to the differential pressure valve mechanism 130 must be sucked and discarded, which increases the amount of ink consumed. For this reason, in this embodiment, the maintenance described below is performed to reduce the amount of ink consumed and to agitate the ink, thereby suppressing the occurrence of uneven shading during printing due to settling of ink components.

[0078] The maintenance of this embodiment will be described with reference to Fig. 6 and Fig. 10. Fig. 10 is a schematic diagram for explaining the maintenance of this embodiment.

[0079] The maintenance of this embodiment is carried out when the period during which the ink flow in the "supply flow path" has stopped since the end of the previously executed printing operation or various cleaning operations has exceeded a predetermined period. This predetermined period is preferably set to the time it takes for the ink components to settle, for example, one to two days. Note that the time it takes for the ink components to settle varies depending on the type of ink and the structure of the supply flow path, so the predetermined period is not limited to this.

[0080] First, from the initial state shown in FIG. 6, as shown in FIG. 10, in a state where the second liquid space 111 of the choke chamber 110 is not blocked by the second flexible member 114, a first step is performed in which the first flexible member 123 is deformed so that the volume of the first liquid space 121 of the buffer chamber 120 becomes smaller than the first reference volume. Specifically, the control unit 2 controls the first pump 6 to supply gas, in this embodiment, air, to the first gas space 122 in a state where the first valve 6c is closed. As a result, the first flexible member 123 moves toward the bottom side of the buffer chamber 120 against the biasing force of the first biasing member 124. In this embodiment, the volume of the first liquid space 121 in the first step is referred to as the first volume. In this way, the ink removed by reducing the first liquid space 121 from the first reference volume to the first volume in the first step is sent to the differential pressure valve mechanism 130 on the upstream side and the liquid ejection head H on the downstream side. As a result, the film 133 deforms so that the volume of the downstream chamber 135 of the differential pressure valve mechanism 130 increases, and the compliance portion 249 deforms so that the volume of the common liquid chamber SR of the head chip 200 increases.

[0081] Next, in a state where the second liquid space 111 of the choke chamber 110 is not blocked by the second flexible member 114, the first flexible member 123 is deformed so that the first liquid space 121 changes from the first volume to the first reference volume. Specifically, the control unit 2 stops the supply of air to the first gas space 122 by the first pump 6 and opens the first valve 6c to open to the atmosphere. As a result, the first flexible member 123 moves to the ceiling side of the buffer chamber 120 against the biasing force of the first biasing member 124. As a result, in the differential pressure valve mechanism 130, the film 133 is deformed so that the volume of the downstream chamber 135 returns to the original volume shown in FIG. 6, and the compliance portion 249 is deformed so that the volume of the common liquid chamber SR of the head chip 200 returns to the original volume shown in FIG. 6. Note that the second step may be controlled so that the first pump 6 sucks the gas in the first gas space 122 with the first valve 6c closed.

[0082] By repeating the first and second steps a number of times, the ink is moved back and forth from the differential pressure valve mechanism 130 to the nozzle N of the liquid ejection head H, and is stirred, thereby suppressing the settling of the ink components. When the first and second steps are performed, no external force is applied to the second flexible member 114; that is, the control unit 2 does not perform control such that gas is supplied to the second gas space 112 by the second pump 7 from the initial state shown in FIG. 6. In other words, if the negative pressure generated in the second connection flow path 107 by the second step does not exceed the biasing force by the second biasing member 115, the first flexible member can be deformed in the first and second steps without the second liquid space 111 of the choke chamber 110 being blocked by the second flexible member 114. In this embodiment, the ink can be agitated to suppress settling of ink components without discharging the ink from the differential pressure valve mechanism 130 to the liquid injection head H to the outside, thereby reducing wasteful consumption of ink compared to removing ink whose components have settled from the differential pressure valve mechanism 130 to the nozzle N by suction cleaning or the like.

[0083] In addition, the configuration for carrying out the maintenance of this embodiment can carry out pressure cleaning. In other words, it is not necessary to provide separate configurations for carrying out pressure cleaning and maintenance, and they can be shared. Therefore, costs can be reduced.

[0084] In this embodiment, since the head chip 200 includes the compliance portion 249, the meniscus of the ink in the nozzle N is not easily destroyed by the deformation of the compliance portion 249 during maintenance. Therefore, the amount of deformation of the first flexible member 123 is increased to increase the agitation of the ink, and the settling of the ink can be further suppressed. Of course, the maintenance is preferably performed by deforming the first flexible member 123 so that the meniscus of the ink in the nozzle N is not destroyed. In other words, the first step is preferably performed by changing the volume of the first liquid space 121 so that the ink is not discharged from the nozzle N. For example, if the meniscus of the ink in the nozzle N is destroyed, a flushing operation or a nozzle cleaning operation is required, which increases the wasteful consumption of ink. The first step is capable of suppressing the wasteful consumption of ink by preventing the meniscus of the nozzle N from being destroyed. Of course, the ink may be discharged from the nozzle N by the maintenance. When ink is discharged from nozzle N, flushing operations and nozzle cleaning operations are required to form a meniscus for nozzle N. However, even when such operations are performed, wasteful consumption of ink can be reduced compared to the case where ink whose components have settled from the differential pressure valve mechanism 130 to nozzle N is removed by suction cleaning or the like.

[0085] In addition, in the first step, at least one of the amount of change and the rate of change by which the first flexible member 123 changes to reduce the volume of the first liquid space 121 is preferably smaller than the amount of change and the rate of change by which the first flexible member 123 changes to reduce the volume of the first liquid space 121 in the pressurized cleaning. Here, the amount of change refers to the difference in the volume change, and the rate of change refers to the amount of change in volume per unit time. In other words, at least one of the amount of change and the rate of change when the volume changes from the first reference volume in the first step in the maintenance to the first volume is preferably smaller than the amount of change and the rate of change when the volume changes from the first reference volume to the first pressurized cleaning volume in the second pressurized cleaning step in the pressurized cleaning. By specifying the amount of change and the rate of change when the volume changes from the first reference volume in the first step to the first volume in this way, ink is less likely to be discharged from the nozzle N to the outside, and the meniscus of the nozzle N is less likely to be destroyed. Incidentally, in the maintenance, since the second liquid space 111 of the choke chamber 110 is not blocked, the ink sent out by reducing the volume of the first liquid space 121 moves to both the liquid ejection head H side and the differential pressure valve mechanism 130 side. Therefore, since the film 133 of the differential pressure valve mechanism 130 is deformed by the ink sent out from the first liquid space 121 to absorb the pressure, the meniscus of the nozzle N of the liquid ejection head H is unlikely to be destroyed even with the same amount of change and rate of change as in the pressurized cleaning. Therefore, in the first step, at least one of the amount of change and rate of change at which the first flexible member 123 changes to reduce the volume of the first liquid space 121 may be equal to or greater than the amount of change and rate of change at which the first flexible member 123 changes to reduce the volume of the first liquid space 121 in the pressurized cleaning.

[0086] In the above maintenance, the first step is performed first from the initial state shown in FIG. 6, and then the second step is performed, but the order of performing the first and second steps is not limited to this. That is, from the initial state shown in FIG. 6, the second step of deforming the first flexible member 123 so that the volume of the first liquid space 121 becomes larger than the first reference volume may be performed first, and then the first step of deforming the first flexible member 123 so that the volume of the first liquid space 121 becomes smaller may be performed. Specifically, in the second step, the first pump 6 is controlled to suck gas from the first gas space 122 with the first valve 6c closed, and in the first step, the first pump 6 stops sucking air into the first gas space 122 and the first valve 6c is opened to open to the atmosphere. In the first step, the first pump 6 may be controlled to supply gas to the first gas space 122 with the first valve 6c closed.

[0087] In this case, it is preferable that in the second step, at least one of the amount and rate of change by which the first flexible member 123 changes to increase the volume of the first liquid space 121 is smaller than the amount and rate of change by which the first flexible member 123 changes in the pressurized cleaning to decrease the volume of the first liquid space 121. By specifying the amount and rate of change of the volume of the first liquid space 121 in the second step in this manner, it is possible to make it difficult for the differential pressure valve mechanism 130 to open.

[0088] (Embodiment 2) 11 to 13 are schematic diagrams illustrating the maintenance according to the second embodiment of the present invention. Note that the same members as those in the above-mentioned embodiment are given the same reference numerals and the duplicated description will be omitted.

[0089] In the maintenance of this embodiment, first, from the initial state shown in Fig. 6, as shown in Fig. 11, a 1A process is performed in which the second flexible member 114 is deformed so that the volume of the second liquid space 111 of the choke chamber 110 is made smaller than the second reference volume so that the second liquid space 111 is not blocked. Specifically, the control unit 2 controls the second pump 7 to supply gas, in this embodiment, air, to the second gas space 112 while the second valve 7c is closed. As a result, the second flexible member 114 moves toward the bottom side of the choke chamber 110 against the biasing force of the second biasing member 115. In this embodiment, the volume of the second liquid space 111 by the 1A process is referred to as a 2A volume. By performing this 1A process, ink from the second liquid space 111 is sent to the differential pressure valve mechanism 130 and the liquid ejection head H, and the film 133 of the differential pressure valve mechanism 130 deforms so as to increase the volume of the downstream chamber 135, and the compliance portion 249 of the head chip 200 deforms so as to increase the volume of the common liquid chamber SR.

[0090] Next, as shown in FIG. 12, a 2A step is performed to deform the first flexible member 123 so that the volume of the first liquid space 121 of the buffer chamber 120 becomes larger than the first reference volume. Specifically, the control unit 2 controls the first pump 6 to suck the gas in the first gas space 122, which is air in this embodiment, while the first valve 6c is closed. As a result, the first flexible member 123 moves to the ceiling side of the buffer chamber 120. In this embodiment, the volume of the first liquid space 121 by the 2A step is referred to as a 1A volume. As a result, the ink in the differential pressure valve mechanism 130 and the liquid ejection head H is sent to the first liquid space 121, the film 133 is deformed so that the volume of the downstream chamber 135 of the differential pressure valve mechanism 130 becomes smaller, and the compliance portion 249 is deformed so that the volume of the common liquid chamber SR of the head chip 200 becomes smaller.

[0091] It is preferable that the amount of change in volume of the first liquid space 121 from the first reference volume to the 1A volume in the 2A step is larger than the amount of change in volume of the second liquid space 111 from the second reference volume to the 2A volume in the 1A step. This allows the ink in the flow path from the differential pressure valve mechanism 130 to the liquid ejection head H to flow significantly, thereby allowing the ink to be significantly agitated.

[0092] Next, as shown in FIG. 13, a 3A step is performed in which the first flexible member 123 is deformed so that the volume of the first liquid space 121 of the buffer chamber 120 is reduced. Specifically, the control unit 2 controls the first pump 6 to supply air to the first gas space 122 while the first valve 6c is closed. As a result, the first flexible member 123 moves to the bottom side of the buffer chamber 120. In this embodiment, the volume of the first liquid space 121 by the 3A step is referred to as a 3A volume. As a result, the ink in the first liquid space 121 is sent to the differential pressure valve mechanism 130 and the liquid ejection head H, the film 133 is deformed so that the volume of the downstream chamber 135 of the differential pressure valve mechanism 130 is increased, and the compliance portion 249 is deformed so that the volume of the common liquid chamber SR of the head chip 200 is increased. In step 3A, the control unit 2 may stop the suction of gas from the first gas space 122 by the first pump 6 and open the first valve 6c to the atmosphere.

[0093] By repeating these steps 2A and 3A multiple times, the ink from the differential pressure valve mechanism 130 to the nozzle N of the liquid ejection head H is moved back and forth and agitated, thereby making it possible to suppress the settling of the ink components. In this embodiment, since the ink from the differential pressure valve mechanism 130 to the liquid ejection head H can be agitated and the settling of the ink components can be suppressed without discharging the ink from the differential pressure valve mechanism 130 to the liquid ejection head H to the outside, it is possible to suppress the wasteful consumption of ink compared to the case where ink from which the components have settled is removed from the differential pressure valve mechanism 130 to the nozzle N by suction cleaning or the like.

[0094] In addition, the configuration for carrying out the maintenance of this embodiment can carry out pressure cleaning. In other words, there is no need to provide separate configurations for carrying out pressure cleaning and maintenance, and they can be shared. This allows for cost reduction.

[0095] In this embodiment, similarly to the above-described first embodiment, the maintenance is preferably performed by deforming the first flexible member 123 so as not to destroy the meniscus of the ink in the nozzle N. That is, in step 1A, it is preferable to change the volume of the second liquid space 111 so as not to discharge ink from the nozzle N. Furthermore, in step 2A, it is preferable to change the volume of the first liquid space 121 so as not to allow air to enter through the nozzle N. Furthermore, in step 3A, it is preferable to change the volume of the first liquid space 121 so as not to discharge ink from the nozzle N.

[0096] In addition, in the maintenance step 2A, it is preferable to deform the first flexible member 123 so as to increase the volume of the first liquid space 121 within a range in which the differential pressure valve mechanism 130 does not open. For example, if the differential pressure valve mechanism 130 opens in the step 2A, ink flows from the upstream side to the downstream side, i.e., the downstream chamber 135 side, and the ink in the downstream flow path increases. If the first flexible member 123 is subsequently deformed in the step 3A so as to decrease the volume of the first liquid space 121, the film 133 of the differential pressure valve mechanism 130 and the compliance portion 249 of the head chip 200 cannot deform, and there is a risk that the meniscus of the nozzle N will be destroyed. By performing the step 2A within a range in which the differential pressure valve mechanism 130 does not open, it is possible to prevent the meniscus of the nozzle N from being destroyed. The range in which the differential pressure valve mechanism 130 does not open refers to a range in which the downstream chamber 135 does not fall below a predetermined pressure, and refers to a range in which the valve body 132 does not communicate between the downstream chamber 135 and the upstream chamber 136.

[0097] In addition, in the step 2A, the first flexible member 123 may be deformed so that the pressure inside the downstream chamber 135 becomes equal to or lower than a predetermined pressure, in other words, the volume of the first liquid space 121 is increased so that the differential pressure valve mechanism 130 opens. In this way, by opening the differential pressure valve mechanism 130 in the step 2A, the flow rate of ink flowing from the differential pressure valve mechanism 130 to the liquid ejection head H increases and the flow speed increases, so that the time required to mix the ink components can be shortened. In addition, when the first flexible member 123 is deformed so that the differential pressure valve mechanism 130 opens, there is a possibility that air will be drawn from the nozzle N. However, even if air is drawn from the nozzle N, the meniscus of the nozzle N can be restored simply by discarding the ink near the nozzle N by a flushing operation, pressurized cleaning, suction cleaning, or the like. Therefore, the amount of ink consumed can be reduced compared to the case where ink is discarded from the differential pressure valve mechanism 130 to the nozzle N.

[0098] In this embodiment, by performing step 2A prior to step 3A, the differential pressure valve mechanism 130 is less likely to open when performing maintenance, and the meniscus formed in the nozzle N is less likely to be destroyed. In other words, by deforming the film 133 in step 2A so as to increase the volume of the downstream chamber 135 of the differential pressure valve mechanism 130, and by deforming the compliance section 249 so as to increase the volume of the common liquid chamber SR of the head chip 200, it is possible to ensure a large amount of deformation of the film 133 until the differential pressure valve mechanism 130 opens in the next step 3A, and a large amount of deformation of the compliance section 249 until the meniscus of the nozzle N is not destroyed.

[0099] Also, similarly to the above-described embodiment 1, in the 3A step, at least one of the amount of change and the rate of change by which the first flexible member 123 changes to reduce the volume of the first liquid space 121 is preferably smaller than the amount of change and the rate of change by which the first flexible member 123 changes to reduce the volume of the first liquid space 121 in the pressurized cleaning. In other words, at least one of the amount of change and the rate of change when the volume changes from the 1A volume to the 3A volume in the 3A step in the maintenance is preferably smaller than the amount of change and the rate of change when the volume changes from the first reference volume to the first pressurized cleaning volume in the second pressurized cleaning step in the pressurized cleaning. By specifying the amount of change and the rate of change when the volume changes from the 1A volume to the 3A volume in the 3A step in this way, ink is less likely to be discharged to the outside from the nozzle N, and the meniscus of the nozzle N is less likely to be destroyed.

[0100] Furthermore, similarly to the above-described first embodiment, in step 2A, at least one of the amount and rate of change at which the first flexible member 123 changes to increase the volume of the first liquid space 121 is preferably smaller than the amount and rate of change at which the first flexible member 123 changes to decrease the volume of the first liquid space 121 in the pressurized cleaning. This can make it difficult to open the differential pressure valve mechanism 130.

[0101] (Embodiment 3) 14 to 16 are schematic diagrams illustrating the maintenance according to the third embodiment of the present invention. Note that the same members as those in the above-mentioned embodiments are given the same reference numerals and the duplicated description will be omitted.

[0102] In the maintenance of this embodiment, first, from the initial state shown in Fig. 6, as shown in Fig. 14, a 1B process is performed in which the second flexible member 114 is deformed so that the volume of the second liquid space 111 of the choke chamber 110 is made larger than the second reference volume so that the second liquid space 111 is not blocked. Specifically, the control unit 2 controls the second pump 7 to suck gas from the second gas space 112, which is air in this embodiment, while keeping the second valve 7c closed. This causes the second flexible member 114 to move toward the ceiling side of the choke chamber 110. In this embodiment, the volume of the second liquid space 111 in the 1B process is referred to as a 2B volume. By performing this 1B process, the ink in the differential pressure valve mechanism 130 and the liquid ejection head H is sent to the second liquid space 111, and the film 133 of the differential pressure valve mechanism 130 deforms so as to reduce the volume of the downstream chamber 135, and the compliance portion 249 of the head chip 200 deforms so as to reduce the volume of the common liquid chamber SR.

[0103] Next, as shown in FIG. 15, a 2B process is performed in which the first flexible member 123 is deformed so that the volume of the first liquid space 121 of the buffer chamber 120 becomes smaller than the first reference volume. Specifically, the control unit 2 controls the first pump 6 to supply air to the first gas space 122 while the first valve 6c is closed. As a result, the first flexible member 123 moves to the bottom side of the buffer chamber 120 against the biasing force of the first biasing member 124. In this embodiment, the volume of the first liquid space 121 by the 2B process is referred to as a 1B volume. As a result, the ink in the first liquid space 121 is sent to the differential pressure valve mechanism 130 and the liquid ejection head H, the film 133 is deformed so that the volume of the downstream chamber 135 of the differential pressure valve mechanism 130 becomes larger, and the compliance portion 249 is deformed so that the volume of the common liquid chamber SR of the head chip 200 becomes larger.

[0104] It is preferable that the amount of change in volume of the first liquid space 121 from the first reference volume to the 1B volume in the 2B step is larger than the amount of change in volume of the second liquid space 111 from the second reference volume to the 2B volume in the 1B step. This allows the ink in the flow path from the differential pressure valve mechanism 130 to the liquid ejection head H to flow significantly, thereby allowing the ink to be significantly agitated.

[0105] Next, as shown in FIG. 16, a 3B process is performed to deform the first flexible member 123 so that the volume of the first liquid space 121 of the buffer chamber 120 increases. Specifically, the control unit 2 controls the first pump 6 to suck air into the first gas space 122 while the first valve 6c is closed. As a result, the first flexible member 123 moves to the ceiling side of the buffer chamber 120. In this embodiment, the volume of the first liquid space 121 by the 3B process is referred to as a 3B volume. As a result, the ink in the differential pressure valve mechanism 130 and the liquid ejection head H is sent to the first liquid space 121, the film 133 is deformed so that the volume of the downstream chamber 135 of the differential pressure valve mechanism 130 decreases, and the compliance portion 249 is deformed so that the volume of the common liquid chamber SR of the head chip 200 decreases. In addition, in step 3B, the control unit 2 may stop the supply of gas to the first gas space 122 by the first pump 6 and open the first valve 6c to the atmosphere.

[0106] By repeating these steps 2B and 3B multiple times, the ink from the differential pressure valve mechanism 130 to the nozzle N of the liquid ejection head H is moved back and forth and agitated, thereby making it possible to suppress the settling of the ink components. In this embodiment, since the ink from the differential pressure valve mechanism 130 to the liquid ejection head H can be agitated and the settling of the ink components can be suppressed without discharging the ink from the differential pressure valve mechanism 130 to the liquid ejection head H to the outside, it is possible to suppress the wasteful consumption of ink compared to the case where ink from which the components have settled is removed from the differential pressure valve mechanism 130 to the nozzle N by suction cleaning or the like.

[0107] In addition, the configuration for carrying out the maintenance of this embodiment can carry out pressure cleaning. In other words, there is no need to provide separate configurations for carrying out pressure cleaning and maintenance, and they can be shared. This allows for cost reduction.

[0108] In this embodiment, similarly to the above-described first embodiment, the maintenance is preferably performed by deforming the first flexible member 123 so as not to destroy the meniscus of the ink in the nozzle N. That is, in step 1B, it is preferable to change the volume of the second liquid space 111 so as to prevent air from entering through the nozzle N. Furthermore, in step 2B, it is preferable to change the volume of the first liquid space 121 so as to prevent ink from being discharged from the nozzle N. Furthermore, in step 3B, it is preferable to change the volume of the first liquid space 121 so as to prevent air from entering through the nozzle N.

[0109] In addition, in the maintenance step 3B, it is preferable to deform the first flexible member 123 so as to increase the volume of the first liquid space 121 within a range in which the differential pressure valve mechanism 130 does not open. For example, if the differential pressure valve mechanism 130 opens in step 3B, ink flows from the upstream side to the downstream side, i.e., the downstream chamber 135 side, and the ink in the downstream flow path increases. If the first flexible member 123 is subsequently deformed in step 2B so as to decrease the volume of the first liquid space 121, the film 133 of the differential pressure valve mechanism 130 and the compliance portion 249 of the head chip 200 cannot deform, and there is a risk that the meniscus of the nozzle N will be destroyed. By performing step 3B within a range in which the differential pressure valve mechanism 130 does not open, it is possible to prevent the meniscus of the nozzle N from being destroyed. The range in which the differential pressure valve mechanism 130 does not open refers to a range in which the downstream chamber 135 does not drop below a predetermined pressure, and refers to a range in which the valve body 132 does not communicate between the downstream chamber 135 and the upstream chamber 136. Similarly, in step 1B, it is preferable to deform the second flexible member 114 so as to increase the volume of the second liquid space 111 within a range in which the differential pressure valve mechanism 130 does not open.

[0110] In addition, in step 3B, the first flexible member 123 may be deformed so that the pressure inside the downstream chamber 135 becomes equal to or lower than a predetermined pressure, in other words, the volume of the first liquid space 121 is increased so that the differential pressure valve mechanism 130 opens. In this way, in step 3B, the differential pressure valve mechanism 130 opens, so that the flow rate of ink flowing from the differential pressure valve mechanism 130 to the liquid ejection head H increases and the flow speed increases, thereby shortening the time required to mix the ink components. In addition, when the first flexible member 123 is deformed so that the differential pressure valve mechanism 130 opens, there is a possibility that air will be drawn from the nozzle N. However, even if air is drawn from the nozzle N, the meniscus of the nozzle N can be restored simply by discarding the ink near the nozzle N by a flushing operation, pressurized cleaning, suction cleaning, or the like. Therefore, the amount of ink consumed can be reduced compared to the case where ink is discarded from the differential pressure valve mechanism 130 to the nozzle N.

[0111] In this embodiment, by performing step 2B prior to step 3B, the differential pressure valve mechanism 130 is less likely to open when performing maintenance, and the meniscus formed in the nozzle N is less likely to be destroyed. In other words, by deforming the film 133 in step 2B so as to increase the volume of the downstream chamber 135 of the differential pressure valve mechanism 130, and by deforming the compliance section 249 so as to increase the volume of the common liquid chamber SR of the head chip 200, it is possible to ensure a large amount of deformation of the film 133 until the differential pressure valve mechanism 130 opens in the next step 3B, and a large amount of deformation of the compliance section 249 until the meniscus of the nozzle N is not destroyed.

[0112] Also, similarly to the above-described embodiment 1, in the 2B step, at least one of the amount of change and the rate of change by which the first flexible member 123 changes to reduce the volume of the first liquid space 121 is preferably smaller than the amount of change and the rate of change by which the first flexible member 123 changes to reduce the volume of the first liquid space 121 in the pressurized cleaning. In other words, at least one of the amount of change and the rate of change when the volume changes from the first reference volume to the 1B volume in the 2B step in maintenance is preferably smaller than the amount of change and the rate of change when the volume changes from the first reference volume to the first pressurized cleaning volume in the second pressurized cleaning step in the pressurized cleaning. By specifying the amount of change and the rate of change when the volume changes from the first reference volume to the 1B volume in the 2B step in this manner, ink is less likely to be discharged to the outside from the nozzle N, and the meniscus of the nozzle N is less likely to be destroyed.

[0113] Furthermore, similarly to the above-described first embodiment, in step 3B, at least one of the amount and rate of change at which the first flexible member 123 changes to increase the volume of the first liquid space 121 is preferably smaller than the amount and rate of change at which the first flexible member 123 changes to decrease the volume of the first liquid space 121 in the pressurized cleaning. This can make it difficult to open the differential pressure valve mechanism 130. (Other embodiments) Although each embodiment of the present invention has been described above, the basic configuration of the present invention is not limited to the above.

[0114] Other maintenance can also be performed using the liquid ejecting device 1 of each of the above-described embodiments. Here, the other maintenance will be described with reference to Figures 8 and 17. Figure 17 is a schematic cross-sectional view illustrating the other maintenance.

[0115] First, similarly to the first pressure cleaning step of the pressure cleaning shown in FIG. 8, a 1C step is performed in which the second flexible member 114 is deformed so as to close the second liquid space 111.

[0116] Next, with the second liquid space 111 closed, a second process C is performed in which the first flexible member 123 is deformed so that the volume of the first liquid space 121 in the buffer chamber 120 becomes smaller than the first reference volume, as shown by the solid line in Figure 17.

[0117] Next, with the second liquid space 111 in a closed state, step 3C is performed in which the first flexible member 123 is deformed so that the volume of the first liquid space 121 returns to the first reference volume, as indicated by the dotted line in FIG.

[0118] By repeating the 2C step and the 3C step a number of times, the ink in the liquid jet head H can be moved reciprocally from the first liquid space 121 upstream and downstream, thereby agitating the ink.

[0119] Thereafter, the blockage of the first liquid space 121 is released, and if air has entered from the nozzle N in step 3C, a flushing operation, pressurized cleaning, suction cleaning for sucking ink from the nozzle N, or the like is performed to restore the meniscus to the nozzle N. This type of other maintenance can also agitate the ink in the liquid ejecting head H from the first liquid space 121, thereby suppressing settling of components contained in the ink, such as pigment. In addition, since only ink required to restore the meniscus is consumed, the amount of ink consumed can be reduced compared to the case where ink from the first liquid space 121 to the nozzle N is discarded.

[0120] In addition, in the above-mentioned other maintenance, the second liquid space 111 of the choke chamber 110 is closed, but the present invention is not limited to this. For example, the first liquid space 121 may be closed by the first flexible member 123, and the second flexible member 114 may be repeatedly deformed to reduce or increase the volume of the second liquid space 111 so as not to close the second liquid space 111. By closing the first liquid space 121 and deforming the second flexible member 114 in this manner, the ink upstream of the second liquid space 111, that is, from the second liquid space 111 to the differential pressure valve mechanism 130, can be agitated. For this reason, the ink in the second liquid space 111 that is not agitated and the ink up to the nozzle N of the liquid ejection head H can be discarded by, for example, suction cleaning, and therefore the amount of ink consumed can be reduced compared to the case where the ink from the differential pressure valve mechanism 130 to the nozzle N is discarded. When closing the first liquid space 121 of the buffer chamber 120 as described above, a protrusion similar to the protrusion 113 of the choke chamber 110 may be provided in the buffer chamber 120. In other words, the buffer chamber 120 in the above-described first to third embodiments does not have the function of closing the flow path.

[0121] In addition, in each of the above-described embodiments 1 to 3 and other maintenance, the choke chamber 110 is provided, but this is not particularly limited, and only the buffer chamber 120 may be provided without providing the choke chamber 110.

[0122] In addition, in each of the above-described embodiments, the first flexible member 123 and the second flexible member 114 are deformed by the pressure of gas such as air, but the present invention is not limited to this. For example, the first flexible member 123 and the second flexible member 114 may be deformed by a solenoid using an electromagnet or by transmitting the driving force of an electric motor via a gear mechanism such as a rack, an eccentric cam, or the like.

[0123] In the above-described embodiments, the thin-film type piezoelectric actuator 300 has been used as the pressure generating means for generating a pressure change in the pressure chamber 212, but the present invention is not limited thereto, and for example, a thick-film type piezoelectric actuator formed by attaching a green sheet or a vertical vibration type piezoelectric actuator in which piezoelectric material and electrode forming material are alternately laminated and expanded and contracted in the axial direction can be used. In addition, as the pressure generating means, a device in which a heating element is disposed in the pressure chamber 212 and droplets are ejected from the nozzle N by bubbles generated by the heat generated by the heating element, or a so-called electrostatic actuator in which static electricity is generated between a vibration plate and an electrode and the vibration plate is deformed by electrostatic force to eject droplets from the nozzle N can be used.

[0124] Furthermore, the present invention is broadly intended for liquid ejection devices in general that are equipped with a liquid ejection head. Examples of the liquid ejection head include recording heads such as various ink jet recording heads used in image recording devices such as printers, and color material ejection heads used in manufacturing color filters for liquid crystal displays, etc. Examples of the liquid ejection head include electrode material ejection heads used in forming electrodes in organic EL displays, FEDs (field emission displays), etc., and bioorganic material ejection heads used in biochip manufacturing, and the present invention can be applied to liquid ejection devices equipped with these liquid ejection heads.

[0125] (Additional Note) From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0126] A preferred embodiment of the liquid ejection device according to the first aspect includes a plurality of nozzles for ejecting liquid, a common liquid chamber communicating with the plurality of nozzles, a liquid storage section for storing liquid, a supply flow path for supplying liquid from the liquid storage section to the common liquid chamber, a differential pressure valve mechanism disposed midway through the supply flow path, and a first liquid chamber disposed in the supply flow path between the differential pressure valve mechanism and the common liquid chamber, with a wall surface partially defined by a first flexible member, and performs maintenance to cause liquid to flow in a portion between the differential pressure valve mechanism and the first liquid chamber by deforming the first flexible member. According to this, when the first flexible member is deformed, the flexible member of the differential pressure valve mechanism is displaced, and the liquid between the differential pressure valve mechanism and the first liquid chamber, which is pressurized or depressurized by the first flexible member, flows between the differential pressure valve mechanism and the first liquid chamber, and the liquid is stirred, so that sedimentation of components contained in the liquid can be suppressed. In addition, the liquid can be stirred without discharging the liquid to the outside or with a small amount of discharge, so that the consumption of the liquid can be reduced.

[0127] In aspect 2, which is a specific example of aspect 1, the maintenance involves deforming the first flexible member so as to increase the volume of the first liquid chamber within a range in which the differential pressure valve mechanism does not open. In this way, by setting the range in which the differential pressure valve mechanism does not open, an increase in liquid downstream of the downstream chamber of the differential pressure valve mechanism is suppressed, and when the first flexible member is subsequently deformed to reduce the volume of the first liquid chamber, destruction of the meniscus of the nozzle can be suppressed. As a result, a cleaning operation to restore the meniscus of the nozzle is not required, and unnecessary consumption of liquid can be suppressed.

[0128] In aspect 3, which is a specific example of aspect 1, a second liquid chamber is disposed in the supply flow path between the differential pressure valve mechanism and the first liquid chamber, and a part of a wall surface of the second liquid chamber is defined by a second flexible member, and the maintenance is performed by deforming the first flexible member in a state in which the second liquid chamber is not blocked by the second flexible member, thereby causing liquid to flow through the second liquid chamber in the portion between the differential pressure valve mechanism and the first liquid chamber. This makes it possible to agitate liquid over a wide range including the second liquid chamber.

[0129] In aspect 4, which is a specific example of aspect 3, the maintenance includes deforming the second flexible member to reduce the volume of the second fluid chamber so that the second fluid chamber is not blocked, and then deforming the first flexible member to increase the volume of the first fluid chamber. This makes it possible to suppress the differential pressure valve mechanism from opening.

[0130] In aspect 5, which is a specific example of aspect 3, the maintenance includes deforming the second flexible member to increase the volume of the second liquid chamber so as not to block the second liquid chamber, and then deforming the first flexible member to decrease the volume of the first liquid chamber. This makes it difficult for a meniscus of a nozzle to be destroyed.

[0131] In Aspect 6, which is a specific example of Aspect 1, the maintenance involves deforming the first flexible member to increase the volume of the first liquid chamber so as to open the differential pressure valve mechanism. In this way, the opening of the differential pressure valve mechanism increases the flow rate and flow velocity of the liquid, improving the mixing ability and shortening the time required for settling recovery, while only consuming enough liquid to restore the meniscus of the nozzle, thereby reducing the amount of liquid consumed.

[0132] In Aspect 7, which is a specific example of Aspect 1, the maintenance includes deforming the first flexible member to reduce the volume of the first liquid chamber, and deforming the first flexible member to increase the volume of the first liquid chamber, thereby moving liquid back and forth between the differential pressure valve mechanism and the first liquid chamber. This can enhance the liquid agitation effect.

[0133] In aspect 8, which is a specific example of aspect 1, a second liquid chamber is disposed in the supply flow path between the differential pressure valve mechanism and the first liquid chamber, and a part of a wall surface of the second liquid chamber is defined by a second flexible member, and in a state in which the second liquid chamber is blocked by the second flexible member, the first flexible member is deformed to reduce the volume of the first liquid chamber, thereby enabling pressurized cleaning to be performed in which liquid is discharged from the multiple nozzles. This allows both maintenance for agitating the liquid and pressurized cleaning to be performed with the same configuration.

[0134] In Aspect 9, which is a specific example of Aspect 8, at least one of the amount and rate of change by which the first flexible member changes in the direction reducing the size of the first liquid chamber during the maintenance is smaller than the amount and rate of change by which the first flexible member changes in the direction reducing the size of the first liquid chamber during the pressure cleaning. This makes it difficult for the meniscus of the nozzle to break.

[0135] In Aspect 10, which is a specific example of Aspect 8, at least one of the amount and rate of change at which the first flexible member changes in the direction to enlarge the first liquid chamber during the maintenance is smaller than the amount and rate of change at which the first flexible member changes in the direction to reduce the first liquid chamber during the pressure cleaning. This makes it difficult for the differential pressure valve mechanism to open.

[0136] In aspect 11, which is a specific example of aspect 1, the differential pressure valve mechanism includes an upstream chamber, a downstream chamber, a flexible member that defines a portion of the downstream chamber, and a valve body that provides or does not provide communication between the upstream chamber and the downstream chamber, and when the pressure inside the downstream chamber falls below a predetermined pressure, the flexible member deforms to move the valve body to provide communication between the upstream chamber and the downstream chamber. This makes it possible to supply liquid to the liquid ejection head H at a predetermined pressure by the differential pressure valve mechanism to form a meniscus in the nozzle. [Explanation of symbols]

[0137] H...liquid ejection head, M...liquid ejection module, N...nozzle, S...medium, SR...common liquid chamber, 1...liquid ejection device, 2...control unit, 3...transport mechanism, 4...casing, 5...support, 6...first pump, 6c...first valve, 7...second pump, 7c...second valve, 8...liquid storage section, 10...flow path member, 20...pressure adjustment unit, 30...circuit board, 40...holding member, 100...upper liquid flow path, 101, 102...upper Gas flow path, 103...lower liquid flow path, 104...first lower gas flow path, 105...second lower gas flow path, 106...first connecting flow path, 107...second connecting flow path, 108...third connecting flow path, 110...choke chamber, 111...second liquid space, 112...second gas space, 113...projection, 114...second flexible member, 115...second biasing member, 120...buffer chamber, 121...first liquid space, 122...first gas space, 123...first flexible member Flexible member, 124...first biasing member, 130...differential pressure valve mechanism, 131...valve mechanism main body, 132...valve body, 133...film, 134...coil spring, 135...downstream chamber, 136...upstream chamber, 137...communication passage, 138...through hole, 200...head chip, 210...flow path forming substrate, 212...pressure chamber, 215...communication plate, 216...nozzle communication passage, 219...supply communication passage, 220...nozzle plate, 220a...nozzle surface, 230 ...protective substrate, 231...actuator holding portion, 240...case, 242...third manifold portion, 243...inlet, 245...compliance substrate, 249...compliance portion, 250...diaphragm, 260...first electrode, 270...piezoelectric layer, 280...second electrode, 290...lead electrode, 300...piezoelectric actuator, 310...active portion, 320...wiring substrate, 400...holder, 500...cover head

Claims

1. A plurality of nozzles for ejecting liquid; a common liquid chamber communicating with the plurality of nozzles; a liquid storage section for storing liquid; a supply flow path for supplying liquid from the liquid storage portion to the common liquid chamber; a differential pressure valve mechanism disposed in the supply flow path; a first liquid chamber disposed in the supply flow path between the differential pressure valve mechanism and the common liquid chamber, the first liquid chamber having a wall surface partially defined by a first flexible member; Equipped with performing maintenance by deforming the first flexible member to allow liquid to flow between the differential pressure valve mechanism and the first liquid chamber; A liquid ejection apparatus comprising:

2. During the maintenance, the first flexible member is deformed so as to increase the volume of the first fluid chamber within a range in which the differential pressure valve mechanism does not open. The liquid ejecting apparatus according to claim 1 .

3. a second fluid chamber is disposed in the supply flow passage between the differential pressure valve mechanism and the first fluid chamber, the second fluid chamber having a wall surface partially defined by a second flexible member; the maintenance includes deforming the first flexible member in a state in which the second fluid chamber is not blocked by the second flexible member, thereby causing liquid to flow through the second fluid chamber in a portion between the differential pressure valve mechanism and the first fluid chamber. The liquid ejecting apparatus according to claim 1 .

4. the maintenance includes deforming the second flexible member to reduce a volume of the second liquid chamber so that the second liquid chamber is not blocked, and then deforming the first flexible member to increase a volume of the first liquid chamber. The liquid ejecting apparatus according to claim 3 .

5. the maintenance includes deforming the second flexible member so as to increase a volume of the second liquid chamber so as not to block the second liquid chamber, and then deforming the first flexible member so as to decrease a volume of the first liquid chamber. The liquid ejecting apparatus according to claim 3 .

6. In the maintenance, the first flexible member is deformed to increase the volume of the first fluid chamber so that the differential pressure valve mechanism opens. The liquid ejecting apparatus according to claim 1 .

7. the maintenance includes deforming the first flexible member so as to reduce a volume of the first liquid chamber, and deforming the first flexible member so as to increase a volume of the first liquid chamber, thereby causing liquid to move back and forth between the differential pressure valve mechanism and the first liquid chamber. The liquid ejecting apparatus according to claim 1 .

8. a second fluid chamber is disposed in the supply flow passage between the differential pressure valve mechanism and the first fluid chamber, the second fluid chamber having a wall surface partially defined by a second flexible member; a pressure cleaning unit that performs pressure cleaning by discharging liquid from the plurality of nozzles by deforming the first flexible member so as to reduce a volume of the first liquid chamber while the second flexible member is blocking the second liquid chamber; The liquid ejecting apparatus according to claim 1 .

9. At least one of an amount and a rate of change of the first flexible member in the direction of reducing the size of the first liquid chamber during the maintenance is smaller than an amount and a rate of change of the first flexible member in the direction of reducing the size of the first liquid chamber during the pressure cleaning. The liquid ejecting apparatus according to claim 8 .

10. At least one of an amount and a rate of change in which the first flexible member changes in a direction to enlarge the first liquid chamber during the maintenance is smaller than an amount and a rate of change in which the first flexible member changes in a direction to reduce the first liquid chamber during the pressure cleaning. The liquid ejecting apparatus according to claim 8 .

11. The differential pressure valve mechanism includes an upstream chamber, a downstream chamber, a flexible member that defines a portion of the downstream chamber, and a valve body that allows or prevents communication between the upstream chamber and the downstream chamber, and when the pressure inside the downstream chamber falls below a predetermined pressure, the flexible member deforms to move the valve body, thereby allowing communication between the upstream chamber and the downstream chamber. The liquid ejecting apparatus according to claim 1 .

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