Head unit and liquid ejection device

Abstract

To provide a head unit which can inhibit a liquid flowing in a passage connection part from being heated and inhibit occurrence of failure in jetting of the liquid, and to provide a liquid jet device.SOLUTION: A heat unit 2 jets a liquid and includes: a circuit board 40 for driving the head unit 2; a housing including a cover 50 defining a housing space for housing the circuit board 40; and a passage member 10 including a passage connection part 12 for connecting with a passage member 3a at the outside of the head unit 2 and partially disposed within the housing. The cover 50 has: a suction port 53 for suctioning air from the outside of the cover 50 into the housing space; and an exhaust port 54 for exhausting air that has passed through the housing space. The passage connection part 12 is disposed outside the housing and is arranged closer to the suction port 53 than the exhaust port 54.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a head unit and a liquid ejecting apparatus that ejects a liquid, and more particularly to a head unit and 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 or plotter, includes a head unit capable of ejecting liquid such as ink stored in an ink tank or ink cartridge.

[0003] The head unit is disclosed to have a cover that forms a housing, and a flow path member and a wiring board housed inside the housing, with the supply protrusion and discharge protrusion that serve as flow path connection parts of the flow path member to which an external flow path member is connected being positioned outside the cover (see, for example, Patent Document 1).

[0004] Also disclosed is a configuration in which the housing has an opening that serves as an air intake port and an opening that serves as an air exhaust port, and air is allowed to flow from the intake port toward the exhaust port inside the cover to cool the wiring components inside the housing (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-53882 [Patent Document 2] Japanese Patent Publication No. 2020-62763 Summary of the Invention [Problem to be solved by the invention]

[0006] However, if the positional relationship between the intake and exhaust ports formed in the housing and the flow path connection part is not sufficiently considered, the flow path connection part may be heated by the heat of the substrate or the air flowing inside the housing that has absorbed the heat of the substrate, which may heat the liquid flowing inside the flow path connection part and reduce the viscosity of the liquid.Furthermore, when the liquid with reduced viscosity is ejected from the nozzle, there is a risk of ejection defects such as reduced ejection characteristics. [Means for solving the problem]

[0007] An aspect of the present invention that solves the above problem is a head unit that ejects liquid, comprising: a circuit board for driving the head unit; a housing including a cover that defines a storage space that houses the circuit board; and a flow path member that includes a flow path connection portion for connecting to a flow path member outside the head unit, a portion of which is arranged within the housing, wherein the cover has an intake port for drawing air from outside the cover into the storage space, and an exhaust port for discharging air that has passed through the storage space, and the flow path connection portion is arranged outside the housing and is closer to the intake port than the exhaust port.

[0008] Another aspect of the present invention is a liquid ejecting apparatus including the head unit according to the above aspect, and a liquid storage section that stores liquid to be supplied to the head unit. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a plan view showing a schematic configuration of a recording apparatus according to a first embodiment. [Figure 2] FIG. 1 is an exploded perspective view showing a schematic configuration of a head unit according to a first embodiment. [Figure 3] FIG. 1 is an exploded perspective view showing a schematic configuration of a head unit according to a first embodiment. [Figure 4] 1 is a cross-sectional view of a main part of a head unit according to a first embodiment. [Figure 5] 1 is a cross-sectional view of a main part of a head unit according to a first embodiment. [Figure 6] FIG. 2 is a bottom view of the head unit according to the first embodiment. [Figure 7] 1 is an exploded perspective view showing a schematic configuration of a liquid jet head according to a first embodiment. [Figure 8] FIG. 10 is a cross-sectional view of a main part of a head unit according to a second embodiment. [Figure 9] FIG. 10 is a cross-sectional view of a main part of a head unit according to a third embodiment. [Figure 10] FIG. 10 is a cross-sectional view of a main part of a head unit according to a fourth embodiment. [Figure 11] FIG. 10 is a cross-sectional view of a main part of a head unit according to a fourth embodiment. [Figure 12] FIG. 10 is a cross-sectional view of a main part of a head unit according to a fifth embodiment. [Figure 13] FIG. 11 is a cross-sectional view of a main part of a modified example of the head unit according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below based on embodiments. However, the following description illustrates one aspect of the present invention and can be modified as desired within the scope of the present invention. In each drawing, the same reference numerals indicate the same components, and their description will be omitted as appropriate. In each drawing, X, Y, and Z represent three spatial axes that are orthogonal to each other. In this specification, the directions along these axes are referred to as the X direction, Y direction, and Z direction. In each drawing, the direction indicated by the arrow is referred to as the positive (+) direction, and the direction opposite the arrow is referred to as the negative (-) direction. Furthermore, three spatial axes that are not limited to the positive and negative directions will be referred to as the X axis, Y axis, and Z axis.

[0011] (Embodiment 1) 1 is a plan view showing a schematic configuration of an ink jet recording apparatus 1, which is an example of a liquid ejecting apparatus according to Embodiment 1 of the present invention. In this embodiment, the +X direction is an example of the "first direction," and the +Y direction is an example of the "second direction."

[0012] The inkjet recording apparatus 1, which is an example of a "liquid ejection apparatus" according to this embodiment, is a printing apparatus that ejects and lands ink, a type of liquid, on a printing medium S, and prints (also known as a recording operation) an image or the like by forming an array of dots on the medium S. The medium S can be made of any material, such as recording paper, resin film, or cloth. The inkjet recording apparatus 1 according to this embodiment is a so-called line-type recording apparatus that prints by ejecting and landing ink from the head unit 2 onto the medium S while transporting the medium S, with the head unit 2 fixed to the apparatus main body 6 during printing.

[0013] As shown in FIG. 1, the ink jet recording apparatus 1 includes a head unit 2, a liquid storage section 3, a control unit 4, a transport mechanism 5, and an apparatus main body 6.

[0014] The head unit 2 has nozzles that eject ink supplied from the liquid storage section 3 in the +Z direction. The head unit 2 is a so-called line head that ejects and lands ink while transporting the medium S, with the head unit 2 fixed to the device main body 6 during printing. Details of the head unit 2 will be described later.

[0015] The liquid storage section 3 individually stores multiple types of ink (for example, multiple colors) to be ejected from the head unit 2. The ink in the liquid storage section 3 is supplied to the head unit 2 via tubes 3a. Examples of the liquid storage section 3 include an ink cartridge that is detachable from the device main body 6, a bag-shaped ink pack made of flexible film, and an ink tank that can be refilled with ink. Note that the liquid storage section 3 stores multiple types of ink with different colors, ingredients, etc.

[0016] The control unit 4 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 4 comprehensively controls each element of the inkjet recording apparatus 1, i.e., the head unit 2, the transport mechanism 5, etc., by the control device executing a program stored in the storage device.

[0017] The transport mechanism 5 is controlled by the control unit 4 to transport the medium S in the direction along the Y axis, and includes a transport roller 5a. That is, the transport mechanism 5 transports the medium S in the direction along the Y axis by rotating the transport roller 5a. Note that the transport mechanism 5 that transports the medium S is not limited to one that includes the transport roller 5a, and may transport the medium S using, for example, a belt or a drum.

[0018] 2 and 3 are exploded perspective views showing a schematic configuration of the head unit 2 of this embodiment. Fig. 4 is a cross-sectional view of the main part of the head unit 2 in a direction perpendicular to the Y axis. Fig. 5 is a cross-sectional view of the main part taken along line AA' in Fig. 4.

[0019] As shown in the figure, the head unit 2 includes a flow path member 10 to which ink is supplied from a liquid storage section 3, a liquid ejection section 30 having a plurality of liquid ejection heads 100 that eject the ink supplied from the flow path member 10, a circuit board 40 for driving the head unit 2, a unit base 20 that supports the liquid ejection section 30 and the flow path member 10, and a cover 50 that houses the flow path member 10 and the circuit board 40 between the unit base 20. In the head unit 2, the circuit board 40, the flow path member 10, the unit base 20, and the liquid ejection section 30 are layered in this order toward the +Z direction, and the cover 50 is arranged to house the flow path member 10 and the circuit board 40 in the -Z direction of the liquid ejection section 30. The flow path member 10, the unit base 20, the liquid ejection section 30, the circuit board 40, and the cover 50 are fixed to one another by adhesives, screws, or the like (not shown).

[0020] The flow path member 10 has a plurality of first inlets S1 corresponding to the number of types of ink supplied to the head unit 2, and a plurality of outlets D corresponding to the number of types of ink and the number of liquid jet heads 100. Figures 2 and 3 show an example in which there are four first inlets S1 and 24 outlets D.

[0021] The flow path member 10 includes a flow path member main body 11 and a flow path connecting portion 12. The flow path member main body 11 has a rectangular shape with the longitudinal direction along the X axis and the lateral direction along the Y axis when viewed in the +Z direction. In other words, the flow path member main body 11 extends along the X axis. The flow path connecting portion 12 is provided to protrude in the -Z direction from the end of the flow path member main body 11 in the -X direction. The flow path member main body 11 and the flow path connecting portion 12 are integrally formed.

[0022] The plurality of first inlets S1 are provided in the flow path connection part 12. Specifically, the plurality of first inlets S1 are located on the side surface of the flow path connection part 12 in the +Y direction. A tube 3a connected to the liquid storage part 3 is connected to the flow path connection part 12 where the first inlets S1 open. In other words, the tube 3a is an example of an "external flow path member" connected to the flow path connection part 12.

[0023] The discharge port D is located on the surface of the flow path member main body 11 on the +Z direction side. A flow path is formed inside the flow path member 10, which connects any one of the first inlets S1 to at least any one of the discharge ports D. In other words, one end of the flow path provided inside the flow path member 10 is the first inlet S1, and the other end is the discharge port D.

[0024] In this embodiment, the flow path member 10 is composed only of a flow path member main body 11 and a flow path connecting portion 12. The flow path member 10 may also be configured without a flexible tube such as the tube 3a. That is, the flow path member 10 may be composed only of a rigid body. When a rigid flow path needle or flow path pipe is provided at the end of the tube 3a connected to the flow path member 10, the tube 3a and the flow path connecting portion 12 may be liquid-tightly connected by press-fitting the flow path needle or the flow path pipe into the first inlet S1 of the flow path connecting portion 12. In this case, a flexible seal member may be provided inside the first inlet S1 to liquid-tightly connect the flow path needle or the flow path pipe to the first inlet S1. The flow path connecting portion 12 may also be a flow path needle or a flow path pipe that protrudes from the flow path member main body 11 in the −Z direction and has the first inlet S1 formed at its tip.

[0025] The liquid ejection unit 30 has a plurality of liquid ejection heads 100, six in this embodiment. The plurality of liquid ejection heads 100 are positioned in the +Z direction of the unit base 20 and fixed to the unit base 20 with adhesive, screws, or the like (not shown). In this embodiment, the plurality of liquid ejection heads 100 are fixed in a head accommodating portion 21 having a recessed shape and opening to a surface of the unit base 20 in the +Z direction. That is, the plurality of liquid ejection heads 100 are fixed to a bottom surface of the head accommodating portion 21, i.e., a surface in the -Z direction that defines the head accommodating portion 21. The head accommodating portion 21 in this embodiment is sized to accommodate six liquid ejection heads 100. A plurality of openings corresponding to the plurality of discharge ports D are formed in the unit base 20. Furthermore, a plurality of second inlet ports S2 are provided in the -Z direction of each liquid ejection head 100. Each of the plurality of second inlet ports S2 is connected to a respective one of the plurality of discharge ports D of the flow path member 10 via a plurality of openings formed in the unit base 20. That is, the liquid ejecting part 30 has a plurality of second inlets S2 corresponding to the plurality of outlets D that the flow path member 10 has, respectively.

[0026] Further, a recessed first accommodating portion 22 that opens onto a surface facing the -Z direction is provided in the -Z direction of the unit base 20. The flow path member 10 is accommodated in this first accommodating portion 22.

[0027] In this embodiment, six liquid jet heads 100 are provided in one head unit 2, but the number of liquid jet heads 100 provided in one head unit 2 is not particularly limited to this. One head unit 2 may be provided with only one liquid jet head 100, or may be provided with two or more liquid jet heads 100.

[0028] Furthermore, flange portions 23 are provided at each end of the unit base 20 in the +X direction and the -X direction, and the head unit 2 is fixed by fastening the flange portions 23 to the device main body 6 with fixing members such as screws. In other words, the flange portions 23 are the fixing region that fixes the head unit 2 to the device main body 6.

[0029] Here, the flow of ink from the liquid storage portion 3 until it is supplied to the liquid jet heads 100 of the head unit 2 will be described. The ink stored in the liquid storage portion 3 is supplied to the first inlet S1 of the flow path member 10 via the tube 3a. The ink supplied to the first inlet S1 is distributed by flow paths (not shown) provided inside the flow path member main body 11, and then supplied to the second inlet S2 of each of the six liquid jet heads 100 of the liquid jet unit 30 via the outlet D. In other words, the flow path member 10 functions as a distribution flow path member that distributes and supplies the ink supplied to the head unit 2 from the first inlet S1 to each of the multiple liquid jet heads 100 of the head unit 2.

[0030] In this embodiment, the flow path member 10 is a distribution flow path member, but may be provided with a recovery flow path for discharging ink that was not ejected from the liquid jet heads 100 to the outside of the head unit 2. Specifically, a confluence flow path that merges and recovers ink that was not ejected from the multiple liquid jet heads 100 may be formed in the flow path member main body 11, and a discharge port may be formed in the flow path connection portion 12 for discharging the ink flowing through the confluence flow path to the outside of the head unit 2. The discharge port may be formed as a part of the flow path member main body 11, or may be formed in a flow path connection portion for recovery that is provided separately from the flow path connection portion 12 and is laminated on the flow path member main body 11 by using the flow path connection portion 12 for supply.

[0031] Here, a description will be given of an example of the arrangement of the plurality of liquid jet heads 100 in the head unit 2. Fig. 6 is a bottom view of the head unit 2 as viewed in the -Z direction.

[0032] As shown in FIG. 6, each of the multiple liquid jet heads 100 included in the head unit 2 has six head chips 140 (see FIG. 7) arranged side by side along the +X direction. Each head chip 140 has multiple nozzles N that eject ink onto the medium S. The multiple nozzles N included in each head chip 140 are arranged side by side along a column direction RD in an XY plane that is perpendicular to the Z axis and defined by the X and Y axes. The column direction RD is a direction inclined with respect to both the X and Y axes. In the following description, the multiple nozzles N arranged side by side along the column direction RD may be referred to as a nozzle column. Note that the number of head chips 140 included in each of the multiple liquid jet heads 100 is not limited to six.

[0033] Next, a description will be given of an example of the structure of the liquid jet head 100. FIG.

[0034] Each liquid jet head 100 includes a filter unit 110, a wiring board 120, a holder 130, six head chips 140, and a fixing plate 150. The liquid jet head 100 is configured by stacking the filter unit 110, the wiring board 120, the holder 130, and the fixing plate 150 in this order in the +Z direction, and the head chips 140 are housed between the holder 130 and the fixing plate 150.

[0035] The filter unit 110 has a generally parallelogram shape with two opposing sides extending along the +X direction when viewed in the +Z direction and two opposing sides extending along the column direction RD. The filter unit 110 includes four flow path filters 111 and four second inlets S2. The four second inlets S2 are located in the -Z direction of the filter unit 110 and are provided corresponding to the four flow path filters 111 located inside the filter unit 110. The flow path filters 111 collect foreign matter such as air bubbles and dust contained in the ink supplied from the second inlets S2.

[0036] The wiring board 120 is located in the +Z direction of the filter unit 110, and has a generally parallelogram shape with two opposing sides extending along the X axis when viewed in the +Z direction and two opposing sides extending along the column direction RD. Wiring members 141 extending from each head chip 140 in the -Z direction are electrically connected to the wiring board 120. Connection wiring 121 is connected to both ends of the wiring board 120 in the column direction RD. The connection wiring 121 is made of a flexible wiring board, such as a flexible flat cable (FFC) or a flexible printed circuit (FPC). The two connection wiring 121 pass through both sides of the filter unit 110 in the +Y direction and the -Y direction, electrically connecting the circuit board 40 and the wiring board 120.

[0037] The holder 130 is located on the +Z direction side of the wiring substrate 120 and has a generally parallelogram shape with two opposing sides extending along the X axis when viewed in the +Z direction and two opposing sides extending along the column direction RD. The holder 130 also has a holding portion 131 that forms a groove-like space in the +Z direction. The holding portion 131 is continuously provided on the +Z direction surface of the holder 130 across the +X direction, thereby opening on both side surfaces in the +X and -X directions. Six head chips 140 are arranged side by side in the +X direction within the holding portion 131 of the holder 130 and fixed therein with an adhesive or the like. While the present embodiment is configured to accommodate six head chips 140 in one holding portion 131, this is not particularly limited, and multiple holding portions 131 capable of individually accommodating each head chip 140 may be provided.

[0038] Furthermore, four third inlets S3 are provided at the four corners in the -Z direction of holder 130. Each of third inlets S3 is connected to a flow path of filter unit 110. As a result, ink supplied from second inlet S2 of filter unit 110 is supplied to third inlet S3 of holder 130. Then, the ink supplied to third inlet S3 is distributed to six head chips 140 in the flow path inside holder 130, and then supplied to six head chips 140.

[0039] The head chip 140 has nozzles N that eject ink toward the +Z direction. In this embodiment, each head chip 140 has two nozzle rows arranged side by side along the X axis, with the nozzles N arranged side by side in the row direction RD. The head chip 140 also has a fourth inlet S4 on the -Z direction side. Ink from the holder 130 is supplied to the head chip 140 through the fourth inlet S4. Each head chip 140 also has a flow path including a pressure chamber that communicates with the nozzle N and the fourth inlet S4, and a pressure generating unit that generates a pressure change in the ink in the pressure chamber. The pressure generating unit can be, for example, a piezoelectric actuator that has a piezoelectric material that exhibits electromechanical conversion function, which changes the volume of the flow path by deforming the flow path to generate a pressure change in the ink in the flow path and eject ink droplets from the nozzle N. Other pressure generating means that can be used include a device in which a heating element is placed in the flow path and ink droplets are ejected from the nozzle N by bubbles generated by the heat generated by the heating element, or a so-called electrostatic actuator that generates electrostatic force between a vibration plate and an electrode, which deforms the vibration plate and ejects ink droplets from the nozzle N. The nozzle surface of the head chip 140 where the nozzle N opens constitutes part of the ejection surface 2a.

[0040] Furthermore, wiring members 141 connected to internal pressure generating means (not shown) extend from the surface on the -Z direction side of each head chip 140. The wiring members 141 can be a flexible sheet-like wiring substrate, for example, a flexible substrate such as a COF (Chip On Film) substrate, or flexible wiring such as an FFC or FPC. For example, a switching element for driving the pressure generating means may or may not be mounted on the wiring members 141.

[0041] Holder 130 is provided with wiring insertion holes 132 that open to the bottom surface of holding portion 131, i.e., the surface of holding portion 131 in the -Z direction and the surface on the wiring substrate 120 side. Wiring members 141 of head chip 140 held by holding portion 131 pass through wiring insertion holes 132 and are led out in the -Z direction of holder 130. The multiple wiring members 141 led out in the -Z direction of holder 130 are electrically connected to wiring substrate 120.

[0042] The fixed plate 150 is located on the +Z direction side of the holder 130. The fixed plate 150 is formed by bending a plate-like member such as a metal so as to cover the openings of the holding portion 131 on the +Y direction and -Y direction side surfaces of the holder 130. The fixed plate 150 is also provided with exposure openings 151, which are through holes for exposing the nozzles N of each head chip 140. In this embodiment, the exposure openings 151 are provided so as to open independently for each head chip 140. That is, since the head unit 2 of this embodiment has six head chips 140, the fixed plate 150 is provided with six independent exposure openings 151. The fixed plate 150 is bonded to the holder 130 and the multiple head chips 140 via an adhesive. The +Z direction surface of the fixed plate 150 constitutes part of the ejection surface 2a. In other words, the ejection surface 2a of the head unit 2 in this embodiment includes the nozzle surface on which the nozzles N of the head chip 140 exposed by the exposed openings 151 open, and the surface of the fixed plate 150 opposite the nozzles N; in other words, the surface of the fixed plate 150 on the side on which the exposed openings 151 open. In other words, the ejection surface 2a of the head unit 2 includes the nozzle surface facing the medium S on which the nozzles N open, and the surface of the fixed plate 150 located closer to the medium S than the nozzle surface. The ejection surface 2a also includes the nozzle surface facing the medium S on which the nozzles N open, and also includes the surface of the head unit 2 facing the medium S on which ink adheres when the ink is ejected. Furthermore, the ejection surface 2a also includes the surface wiped by a wiping member such as an elastomer or cloth (not shown). The ejection surface 2a may be composed only of the nozzle surface on which the nozzles N open. The nozzles N are flow paths including openings that form meniscuses of ink ejected by pressure changes in a pressure chamber caused by driving a pressure generating means.

[0043] On the other hand, as shown in FIGS. 2 to 5, the circuit board 40 of the head unit 2 is located on the -Z direction side of the flow path member 10. The circuit board 40 is a plate-like member having a substantially rectangular shape, with two opposing sides extending in the +X direction and the other two opposing sides extending along the +Y direction when viewed in the +Z direction, that is, a so-called rigid board. The circuit board 40 is also arranged so that its thickness direction is perpendicular to the ejection surface 2a, that is, the same direction as the +Z direction. By arranging the circuit board 40 so that its thickness direction is the same as the +Z direction in this way, it is possible to prevent the head unit 2 from becoming larger in the +Z direction, and thereby to achieve a more compact head unit 2.

[0044] The circuit board 40 is formed with a drive signal generation circuit (not shown) that outputs a drive signal for driving the pressure generating means of the liquid jet head 100. The drive signal generation circuit is composed of wiring and electronic components (not shown). Examples of electronic components that make up the drive signal generation circuit include capacitors, transistors, and integrated circuits. The circuit board also has two connectors 41, which are an example of electronic components, on its -Z direction surface. The control unit 4 is connected to the connectors 41 via wiring (not shown), and receives the power supply voltage of the head unit 2, a position information signal indicating the transport position of the medium S, image information, and the like from the control unit 4. The circuit board 40 generates control signals, such as drive signals for driving the pressure generating means and timing signals for supplying the drive signals, from the power supply voltage, position information signal, image signal, and the like received via the connector 41, and outputs these signals to each liquid jet head 100.

[0045] A heat sink 42 for dissipating heat generated by electronic components (not shown) is attached to the surface of the circuit board 40 on the −Z direction side. That is, in the housing space formed by the first housing portion 22 and the second housing portion 51 described below, the circuit board 40 is disposed between the heat sink 42 and the flow path member main body 11, which is a part of the flow path member 10. By providing the heat sink 42 on the circuit board 40 in this manner, the cooling efficiency of the electronic components on the circuit board 40 can be improved. Furthermore, because the circuit board 40 is disposed between the heat sink 42 and the flow path member main body 11, heat from the heat sink 42 is less likely to be conducted to the flow path member main body 11, and heating of the ink in the flow path member main body 11 can be suppressed. That is, the circuit board 40 is disposed in a housing described in detail below so as to partition the housing space described in detail below into a space in which the flow path member main body 11 is disposed and a space in which the heat sink 42 is disposed.

[0046] Such a circuit board 40 is provided with a drive signal generation circuit, and therefore is more likely to generate heat than a relay board that relays connections between wires. For this reason, the circuit board 40 generates heat when the head unit 2 ejects ink, and therefore needs to be cooled to prevent the drive signal generation circuit from running out of control or being destroyed by heat. Of course, in this embodiment, the circuit board 40 is provided with a drive signal generation circuit, but this is not particularly limited, and the circuit board 40 may be provided with wires or the like without a drive signal generation circuit formed thereon.

[0047] Furthermore, the connection wiring 121 of the plurality of liquid jet heads 100 is electrically connected to the circuit board 40. Specifically, the connection wiring 121 of the liquid jet heads 100 passes outside the flow path member 10 in the +Y direction and the −Y direction, and is electrically connected to the surface of the circuit board 40 in the +Z direction. Furthermore, the circuit board 40 is a common board to which the connection wiring 121 of the six liquid jet heads 100 are commonly connected. Of course, the circuit board 40 may be divided into two or more pieces. Furthermore, a plurality of circuit boards 40 may be stacked along the Z axis.

[0048] The cover 50 has a second housing portion 51 that opens in the +Z direction. The second housing portion 51 is defined by a first wall portion 51a provided in the -X direction, a second wall portion 51b provided in the +X direction, a third wall portion 51c provided in the -Y direction, a fourth wall portion 51d provided in the +Y direction, and a ceiling portion 51e provided in the -Z direction. The cover 50 further has an extension portion 52 that extends in the -X direction beyond the first wall portion 51a. When the cover 50 is fixed to the -Z direction surface of the unit base 20, a "housing space" is defined between the unit base 20 and the cover 50, consisting of the first housing portion 22 and the second housing portion 51. In this embodiment, the circuit board 40 is housed in this housing space, the second housing portion 51. In other words, the cover 50 and the unit base 20 of this embodiment form a "housing" that defines the housing space. A flow path member main body 11, which is a part of the flow path member 10, is accommodated in a first accommodation portion 22 of the accommodation space. Note that a flow path connection portion 12 of the flow path member 10 is provided outside the accommodation space.

[0049] The flow path connection portion 12 and the first wall portion 51a are disposed facing each other with a gap therebetween. The flow path connection portion 12 is disposed at a position overlapping the accommodation space in a direction perpendicular to the ejection surface 2a, which in this embodiment is the +Z direction. Here, "the flow path connection portion 12 is disposed at a position overlapping the accommodation space in the +Z direction" means that at least a portion of the flow path connection portion 12 overlaps with the second accommodation portion 51 when viewed in an in-plane direction of an XY plane defined by the X-axis and Y-axis perpendicular to the +Z direction, where the flow path connection portion 12 and the second accommodation portion 51 constituting the accommodation space are viewed in the +X direction in this embodiment. In this embodiment, the flow path connection portion 12 is disposed at a position completely overlapping with the second accommodation portion 51 when viewed in the +X direction, but this also includes a case where only a portion of the flow path connection portion 12 overlaps with the second accommodation portion 51 when viewed in the +X direction. In this way, by arranging the flow path connection portion 12 at a position that overlaps with the storage space in the +Z direction, in this embodiment with the second storage portion 51, the head unit 2 can be prevented from becoming larger in the +Z direction compared to when the flow path connection portion 12 is arranged at a position that does not overlap with the storage space in the +Z direction.

[0050] The cover 50 is also provided with an intake port 53 and an exhaust port 54 that connect the second housing portion 51 to the outside.

[0051] The air intake port 53 is an opening for drawing air from the outside into the second housing portion 51. The air intake port 53 is arranged closer to the flow path connecting portion 12 than the air exhaust port 54. Specifically, the air intake port 53 of this embodiment is provided so as to penetrate the first wall portion 51a along the X axis. That is, the air intake port 53 of this embodiment is provided at a position facing the flow path connecting portion 12. Therefore, the air intake port 53 and the flow path connecting portion 12 are arranged with a gap between them in the +X direction. It is preferable that the air intake port 53 be open over a relatively wide area, and in this embodiment, the air intake port 53 is open over substantially the entire surface of the first wall portion 51a.

[0052] The exhaust port 54 is an opening for discharging air inside the second housing portion 51 to the outside. The exhaust port 54 is disposed farther from the flow path connection portion 12 than the intake port 53. Specifically, the exhaust port 54 is provided so as to penetrate along the Y axis at the end side of the fourth wall portion 51d in the -X direction. That is, the circuit board 40 is disposed so that the direction along the +X direction is the longitudinal direction, the intake port 53 is provided at one end side of the second housing portion 51 in the +X direction (the end side in the -X direction in this embodiment), and the exhaust port 54 is provided at the other end side in the +X direction (the end side in the +X direction in this embodiment).

[0053] The flow path connection portion 12 is arranged at a position facing the intake port 53 with a spacing in the -X direction from the intake port 53 of the cover 50. That is, the intake port 53 is provided at the -X direction end of the second housing portion 51. In contrast, the exhaust port 54 is provided at the +X direction end side on the opposite side of the flow path connection portion 12 of the second housing portion 51. For this reason, the flow path connection portion 12 is arranged closer to the intake port 53 than the exhaust port 54. Note that the flow path connection portion 12 being arranged closer to the intake port 53 than the exhaust port 54 means that, when viewed in the +Z direction, the distance L1 between the flow path connection portion 12 and the intake port 53 in the direction along the X-axis is shorter than the distance L2 between the flow path connection portion 12 and the exhaust port 54. That is, the distance L1 and the distance L2 satisfy the relationship L1 < L2.

[0054] Also, in this embodiment, the intake port 53 has a rectangular shape when viewed in the +X direction. Also, the exhaust port 54 has a rectangular shape when viewed in the -Y direction. Of course, the opening shapes of the intake port 53 and the exhaust port 54 are not particularly limited to this, and may be circular, elliptical, polygonal, or the like.

[0055] An exhaust fan 55 for blowing the air inside the second housing portion 51 to the outside is provided at the exhaust port 54 of such a cover 50. The exhaust fan 55 is a "blowing mechanism" that blows the air inside the second housing portion 51 to the outside of the second housing portion 51, thereby creating a negative pressure inside the second housing portion 51 with respect to the outside, and sending air from the outside of the second housing portion 51 into the second housing portion 51 through the intake port 53. Note that the blowing mechanism is not particularly limited to this, and an intake fan that blows air from the outside of the second housing portion 51 into the intake port 53 may be provided, or both an intake fan and an exhaust fan may be provided. Also, the blowing mechanism is not limited to an intake fan and an exhaust fan, and may be a pressure pump that pumps external air into the second housing portion 51 from the intake port 53, or a suction pump that sucks the air inside the second housing portion 51 from the exhaust port 54, or the like.

[0056] By operating the exhaust fan 55 provided at the exhaust port 54, the air inside the second housing section 51 is discharged from the exhaust port 54 to the outside of the second housing section 51. By discharging the air inside the second housing section 51 from the exhaust port 54 in this manner, the inside of the second housing section 51 becomes negative pressure relative to the outside (e.g., atmospheric pressure), and air outside the second housing section 51 is drawn into the inside via the intake port 53. That is, by operating the exhaust fan 55, an air flow along the +X direction from the intake port 53 toward the exhaust port 54 is generated inside the second housing section 51. That is, the air outside the second housing section 51 is drawn into the inside of the second housing section 51 through the intake port 53, and the air drawn into the second housing section 51 moves along the +X direction, thereby cooling the circuit board 40 and the heat sink 42. The air heated by cooling the circuit board 40 and the heat sink 42 inside the second housing portion 51 is exhausted to the outside of the second housing portion 51 through the exhaust port 54.

[0057] In other words, the air sucked in from the intake port 53 flows within the second storage section 51 along the +X direction, and the flow path connection section 12, the intake port 53 and the exhaust port 54 are arranged in this order in the +X direction.

[0058] In the second housing section 51, the air taken in through the air intake port 53 flows in the +X direction toward the exhaust port 54, so that the circuit board 40 and the heat sink 42 are easily cooled on the air intake port 53 side and are more difficult to cool on the exhaust port 54 side than the air intake port 53 side. This is because the air taken in through the air intake port 53 cools the air intake port 53 side of the circuit board 40 and the heat sink 42, thereby heating them, and the heated air heats the exhaust port 54 side of the circuit board 40 and the heat sink 42. In other words, the temperatures of the circuit board 40 and the heat sink 42 cooled by the air flowing through the second housing section 51 are high on the +X direction side along the X axis and gradually decrease toward the −X direction. Therefore, by arranging the flow path connection part 12 at a position closer to the intake port 53 than to the exhaust port 54, the relatively cooler parts of the circuit board 40 and the heat sink 42 are arranged closer to the flow path connection part 12, and the ink passing through the flow path connection part 12 is less likely to be heated by the heat of the circuit board 40 and the heat sink 42. In contrast, for example, if the flow path connection part 12 is arranged closer to the exhaust port 54 than to the intake port 53, the relatively hotter parts of the circuit board 40 and the heat sink 42 are arranged closer to the flow path connection part 12, and there is a risk that the ink passing through the flow path connection part 12 will be heated by the heat of the circuit board 40 and the heat sink 42. When the ink in the flow path connection part 12 is heated, the viscosity of the ink decreases, which can cause problems such as a deterioration in the ejection characteristics of the ink ejected from the liquid ejection head 100 and poor ink ejection. In this embodiment, the circuit board 40 and the heat sink 42 make it difficult for the ink in the flow path connection portion 12 to heat up, thereby preventing a decrease in the viscosity of the ink supplied to the liquid jet head 100, and thereby preventing a decrease in the jetting characteristics of the ink jetted from the liquid jet head 100, thereby preventing poor ink jetting.

[0059] Furthermore, in this embodiment, as described above, the flow path connection part 12 is disposed at a position facing the intake port 53, and the exhaust port 54 does not face the flow path connection part 12. That is, air drawn in through the intake port 53 moves in the +X direction from the intake port 53 to the exhaust port 54, and the flow path connection part 12, the intake port 53, and the exhaust port 54 are aligned in this order in the +X direction. By aligning the flow path connection part 12, the intake port 53, and the exhaust port 54 in this order in the +X direction, the flow path connection part 12 is positioned away from the second housing part 51 in the housing space in which the intake port 53 and the exhaust port 54 are provided, and at a position relatively far from the exhaust port 54. This makes it possible to suppress the heat in the second housing part 51 from being conducted to the flow path connection part 12 via the cover 50. In particular, by locating a relatively high-temperature portion of the second housing part 51 on the exhaust port 54 side relatively far from the flow path connection part 12, heating of the flow path connection part 12 can be suppressed. This further prevents the ink in the flow path connection part 12 from being heated by the heat in the second storage part 51. Furthermore, since the exhaust port 54 is provided at a position that does not face the flow path connection part 12, the heated air exhausted from the exhaust port 54 is prevented from being blown onto the flow path connection part 12, and heating of the flow path connection part 12 can be prevented.

[0060] Here, the distance L1 between the flow path connection portion 12 and the air intake port 53 is preferably equal to or greater than the maximum width W of the air intake port 53. In other words, the distance L1 and the maximum width W preferably satisfy the relationship L1≧W. The distance L1 between the flow path connection portion 12 and the air intake port 53 refers to the minimum dimension between the flow path connection portion 12 and the air intake port 53 in the +X direction. Furthermore, the maximum width W of the air intake port 53 refers to the diagonal dimension of the air intake port 53 shown in FIG. 2 because the air intake port 53 of this embodiment has a rectangular shape. By making the distance L1 between the flow path connection portion 12 and the air intake port 53 equal to or greater than the maximum width W of the air intake port 53, it is possible to prevent a gap between the flow path connection portion 12 and the air intake port 53 from interfering with the suction of air through the air intake port 53, thereby enabling efficient suction of air through the air intake port 53 and efficient cooling of the circuit board 40 and the heat sink 42. Furthermore, by setting the distance L1 between the flow path connection part 12 and the intake port 53 to be equal to or greater than the maximum width W of the intake port 53, it is possible to prevent the flow path connection part 12 from being heated by the radiant heat of the circuit board 40 and the heat sink 42 inside the second storage part 51. Therefore, it is possible to prevent the ink introduced from the first inlet S1 from being heated inside the flow path connection part 12 by the circuit board 40 and the heat sink 42.

[0061] Furthermore, air sucked in through the air intake port 53 flows through the second housing portion 51 along the +X direction, and is discharged from the exhaust port 54 in the +Y direction, which is different from the +X direction in which the air flows through the second housing portion 51. By providing the exhaust port 54 in the cover 50 so as to discharge air in the +Y direction in this manner, the exhaust fan 55 connected to the exhaust port 54 and the exhaust duct 56 connected to the exhaust fan 55, which will be described in detail later, can be arranged in the +Y direction of the head unit 2, thereby making it possible to make the head unit 2 more compact in the +X direction than when the exhaust fan 55 and the exhaust duct 56 are arranged on the +X direction side of the cover 50. Furthermore, because the exhaust fan 55 and the exhaust duct 56 do not need to be arranged in the +X direction of the cover 50, the flange portion 23 of the unit base 20 used to fix the head unit 2 to the device main body 6 is not covered by the exhaust fan 55 and the exhaust duct 56, and this makes it possible to prevent a decrease in workability when fixing the head unit 2 to the device main body 6.

[0062] Furthermore, in this embodiment, the circuit board 40 is disposed so that its longitudinal direction is along the +X direction, the intake port 53 is provided at an end on the -X direction side, which is one end side in the +X direction, and the exhaust port 54 is provided at an end side in the +X direction, which is the other end side in the +X direction. This allows an air flow to be formed along the longitudinal direction of the circuit board 40 inside the second housing portion 51, and the distance over which the air flowing inside the second housing portion 51 comes into contact with the circuit board 40 and the heat sink 42 is increased, allowing the circuit board 40 and the heat sink 42 to be efficiently cooled by the air.

[0063] In this embodiment, the air intake 53 is disposed at a position facing the flow path connecting portion 12. That is, the air intake 53 is provided in the first wall portion 51a. By providing the air intake 53 in the first wall portion 51a in this manner, the head unit 2 and the inkjet recording apparatus 1 can be made smaller in size along the Y axis than when the air intake 53 is provided in the third wall portion 51c or the fourth wall portion 51d. That is, if the air intake 53 is provided in a position not facing the flow path connecting portion 12, for example, in the third wall portion 51c or the fourth wall portion 51d, another member cannot be provided in a position that blocks the air intake 53. Therefore, another member must be provided with a gap between the third wall portion 51c and the fourth wall portion 51d where the air intake 53 is provided, which results in an increase in size of the inkjet recording apparatus 1 in the Y axis direction. Similarly, if the flow path connection part 12 is provided at a position that protrudes in the +Y direction or the −Y direction from the cover 50 of the head unit 2 so that the intake port 53 does not face the flow path connection part 12, the head unit 2 will become larger in the direction along the Y axis. In this embodiment, by arranging the flow path connection part 12 and the intake port 53 at positions that face each other, it is not necessary to arrange the flow path connection part 12 at a position that protrudes in the +Y direction or the −Y direction from the cover 50, and the head unit 2 and the inkjet recording apparatus 1 can be made smaller in the direction along the Y axis.

[0064] Furthermore, in this embodiment, the first inlet S1 of the flow path connecting portion 12 is provided so as to open to the side surface in the +Y direction. In other words, the first inlet S1 of the flow path connecting portion 12 is provided at a position that does not face the air intake port 53. Therefore, when connecting the tube 3a to the first inlet S1, it is not necessary to connect it in the narrow space between the flow path connecting portion 12 and the air intake port 53, which makes the connection work easy, and also makes it difficult for the tube 3a to block the air intake port 53, which makes it possible to prevent the tube 3a from interfering with the suction of air from the air intake port 53.

[0065] In this embodiment, as shown in FIG. 1 , one end of an exhaust duct 56 is connected to the exhaust fan 55. The other end of the exhaust duct 56 is open to the outside of the inkjet recording apparatus 1, i.e., to the outer surface of the apparatus main body 6. Therefore, air exhausted from the inside of the second storage unit 51 to the outside by the exhaust fan 55 is exhausted to the outside of the inkjet recording apparatus 1 via the exhaust duct 56. Note that the position of the exhaust fan 55 when the exhaust duct 56 is provided is not particularly limited. One end of the exhaust duct 56 may be connected to the exhaust port 54, and the exhaust fan 55 may be provided inside the exhaust duct 56. Alternatively, the exhaust fan 55 may be provided on the other end side of the exhaust duct 56, i.e., on the outer surface side of the apparatus main body 6. By providing the exhaust duct 56, the exhaust fan 55 can exhaust air from the second storage unit 51 to the outside of the inkjet recording apparatus 1. Therefore, it is possible to prevent heated air exhausted from the exhaust port 54 from being sucked through the intake port 53. In other words, by providing exhaust duct 56, the air heated by cooling circuit board 40 and heat sink 42 inside second housing section 51 is exhausted to the outside of inkjet recording apparatus 1, and the heated air exhausted from exhaust port 54 is less likely to be sucked into second housing section 51 through intake port 53. Therefore, it is possible to prevent air heated inside second housing section 51 from being sucked again through intake port 53, and to efficiently cool circuit board 40 and heat sink 42 inside second housing section 51 with unheated air.

[0066] The cover 50 is made of a resin material or a metal material. In this embodiment, the cover 50 is made of a resin material, which allows for reduction in weight and cost.

[0067] Further, an opening 52a is provided in the extension portion 52 of the cover 50 to expose the connector 41 of the circuit board 40 to the outside in the -Z direction. External wiring (not shown) from the control unit 4 is connected to the connector 41 through the opening 52a.

[0068] As described above, the head unit 2 of this embodiment is a head unit 2 that ejects ink, which is a liquid, and includes a circuit board 40 for driving the head unit 2, and a housing including a cover 50 that defines a first housing portion 22 and a second housing portion 51, which are housing spaces that house the circuit board 40. The head unit 2 also includes a flow path member 10, a portion of which is disposed within the housing, and includes a flow path connection portion 12 for connecting to a tube 3a that is a flow path member external to the head unit 2. The cover 50 also has an intake port 53 for drawing air from outside the cover 50 into the second housing portion 51, and an exhaust port 54 for discharging air that has passed through the second housing portion 51. The flow path connection portion 12 is disposed outside the housing, and is disposed closer to the intake port 53 than the exhaust port 54.

[0069] Because the air taken in from the air intake port 53 flows toward the exhaust port 54, the air intake port 53 side of the circuit board 40 is more easily cooled, and the exhaust port 54 side is less easily cooled than the air intake port 53 side. Therefore, by arranging the flow path connection unit 12 near the air intake port 53, heat from the circuit board 40 is less likely to be transferred to the flow path connection unit 12, and the ink in the flow path connection unit 12 is less likely to be heated, compared to a configuration in which the flow path connection unit 12 is arranged near the exhaust port 54. In this way, because the ink in the flow path connection unit 12 is less likely to be heated by the circuit board 40, a decrease in the viscosity of the ink supplied from the flow path connection unit 12 to the liquid jet head 100 is suppressed, and a decrease in the ejection characteristics of the ink ejected from the liquid jet head 100 is suppressed, making it possible to suppress the occurrence of ink ejection defects.

[0070] Furthermore, in the head unit 2 of this embodiment, it is preferable that the air intake 53 faces the flow path connection portion 12. By having the air intake 53 and the flow path connection portion 12 face each other in this manner, the head unit 2 can be made smaller in size in the direction along the Y axis. That is, if the air intake 53 is provided at a position not facing the flow path connection portion 12, for example, on the third wall portion 51c or the fourth wall portion 51d, another member cannot be provided in a position that blocks the air intake 53. Therefore, another member must be provided with a gap between the third wall portion 51c and the fourth wall portion 51d where the air intake 53 is provided, which increases the size of the inkjet recording apparatus 1 in the direction along the Y axis. Similarly, if the flow path connection portion 12 is provided at a position that protrudes in the +Y direction or the −Y direction from the cover 50 of the head unit 2 so that the air intake 53 does not face the flow path connection portion 12, the head unit 2 will increase in size in the direction along the Y axis. In this embodiment, by positioning the flow path connection part 12 and the air intake port 53 in positions facing each other, there is no need to position the flow path connection part 12 in a position that protrudes in the +Y direction or the -Y direction from the cover 50, and the head unit 2 and the inkjet recording device 1 can be made smaller in the direction along the Y axis.

[0071] Furthermore, in the head unit 2 of this embodiment, it is preferable that the distance L1 between the air intake 53 and the flow path connection part 12 is equal to or greater than the maximum width W of the air intake 53. By sufficiently separating the air intake 53 from the flow path connection part 12, it is possible to prevent the air intake from being obstructed by the flow path connection part 12 through the air intake 53, and it is also possible to prevent the air intake 53 from being heated by the radiant heat of the circuit board 40 in the second housing part 51.

[0072] Furthermore, in the head unit 2 of this embodiment, it is preferable that the first inlet S1, which is an opening of the flow path formed in the flow path connection part 12, does not face the air intake port 53. By providing the first inlet S1 at a position that does not face the air intake port 53, it is not necessary to connect the tube 3a to the first inlet S1 in the narrow space between the flow path connection part 12 and the air intake port 53, and the connection work can be easily performed. Furthermore, the tube 3a is less likely to block the air intake port 53, and it is possible to prevent the tube 3a from obstructing the suction of air from the air intake port 53.

[0073] Furthermore, in the head unit 2 of this embodiment, it is preferable that the exhaust port 54 does not face the flow path connection portion 12. In this way, by not facing the flow path connection portion 12, the exhaust port 54 prevents the heated air exhausted from the exhaust port 54 from being blown toward the flow path connection portion 12, and thus prevents the flow path connection portion 12 from being heated.

[0074] Furthermore, in the head unit 2 of this embodiment, it is preferable that the air sucked in through the air intake port 53 moves in the +X direction, which is the first direction, from the air intake port 53 toward the exhaust port 54, and that the flow path connection portion 12, the air intake port 53, and the exhaust port 54 are aligned in this order in the +X direction. By aligning the air flow path connection portion 12, the air intake port 53, and the exhaust port 54 in this order in the +X direction in this way, the flow path connection portion 12 is disposed at a position away from the second housing portion 51 and at a position relatively far from the exhaust port 54. This makes it possible to suppress the heat in the second housing portion 51 from being conducted to the flow path connection portion 12 via the cover 50. In particular, by locating a relatively high-temperature portion of the second housing portion 51 on the exhaust port 54 side relatively far from the flow path connection portion 12, it is possible to suppress heating of the flow path connection portion 12.

[0075] Furthermore, in the head unit 2 of this embodiment, the circuit board 40 has its longitudinal direction in the +X direction, which is the first direction, and the air intake 53 is preferably provided at one end in the +X direction of the second housing section 51, which is the space within the housing space from the air intake 53 to the air exhaust 54, and the air exhaust 54 is preferably provided at the other end in the +X direction of the second housing section 51. Because air moves along the +X direction from the air intake 53 toward the air exhaust 54 within the second housing section 51, aligning the longitudinal direction of the circuit board 40 with the +X direction can increase the area of ​​the circuit board 40 that comes into contact with the air flowing within the second housing section 51. Therefore, the circuit board 40 can be cooled efficiently.

[0076] Furthermore, in the head unit 2 of this embodiment, it is preferable that the exhaust port 54 exhaust air in the +Y direction, which is a second direction different from the +X direction, which is the first direction. Accordingly, since the exhaust port 54 is configured to exhaust air in the +Y direction, a blower mechanism such as an exhaust fan 55 or a suction pump can be arranged in the +Y direction at the exhaust port 54, compared to when the exhaust port 54 is configured to exhaust air in the +X direction. This allows the head unit 2 to be made smaller in size in the +X direction. Furthermore, the head unit 2 has flange portions 23, which are fixing regions for fixing the head unit 2 to the device main body 6 with screws or the like, provided on both sides in the +X and −X directions. Therefore, when a blower mechanism is provided at the exhaust port 54, the flange portions 23 are not covered by the blower mechanism, which prevents a decrease in workability when fixing the head unit 2 to the device main body 6.

[0077] Furthermore, in the head unit 2 of this embodiment, the head unit 2 is a line head configured with multiple liquid jet heads 100 lined up in the +X direction, which is the first direction, and it is preferable that the circuit board 40 is a circuit board 40 common to the multiple liquid jet heads 100.

[0078] Furthermore, in the head unit 2 of this embodiment, the head unit 2 has an ejection surface 2a on which a plurality of nozzles N that eject ink, which is a liquid, are formed, and it is preferable that the flow path connection part 12 overlaps with the storage space in the +Z direction, which is the direction perpendicular to the ejection surface 2a. Accordingly, by arranging the flow path connection part 12 and the storage space at positions where they overlap with each other in the +Z direction, it is possible to prevent the head unit 2 from becoming larger in the +Z direction, and to achieve a more compact head unit 2.

[0079] Furthermore, in the head unit 2 of this embodiment, it is preferable that the thickness direction of the circuit board 40 is the same direction as the +Z direction, which is the direction perpendicular to the ejection surface 2a. By arranging the circuit board 40 so that its thickness direction is the same as the +Z direction in this way, it is possible to prevent the cover 50 from being enlarged in the +Z direction in order to form the second housing portion 51 that houses the circuit board 40 large in the +Z direction, and it is possible to reduce the size of the head unit 2 in the +Z direction.

[0080] Furthermore, the head unit 2 of this embodiment further includes a heat sink 42 that is disposed in the second housing portion 51, which is a housing space, and that dissipates heat from the circuit board 40. Preferably, the flow path member main body 11, which is a part of the flow path member 10, is disposed in the first housing portion 22, which is a housing space, and the circuit board 40 is disposed between the flow path member main body 11, which is disposed in the flow path member main body 11, which is a housing space, and the heat sink 42. By providing the heat sink 42 on the circuit board 40, the cooling efficiency of the electronic components on the circuit board 40 can be improved. Furthermore, because the circuit board 40 is disposed between the heat sink 42 and the flow path member main body 11, heat from the heat sink 42 is unlikely to be conducted to the flow path member main body 11, and heating of the ink in the flow path member main body 11 can be suppressed.

[0081] Furthermore, in the head unit 2 of this embodiment, it is preferable that air be introduced from outside the cover 50 via the intake port 53 by an exhaust fan 55, which is a blower mechanism. By providing a blower mechanism such as the exhaust fan 55 in this manner, air for cooling the circuit board 40 can be taken into the housing space through the intake port 53 and exhausted to the outside through the exhaust port 54.

[0082] Further, an inkjet recording apparatus 1 which is an example of the liquid ejection device of the present embodiment includes the head unit 2 described above and a liquid storage unit 3 that stores ink which is the liquid supplied to the head unit 2. By suppressing the heating of the flow path connection portion 12 by the circuit board 40, it is possible to realize a liquid ejection device that suppresses a decrease in the ejection characteristics of the ink and suppresses ejection failure of the ink.

[0083] (Embodiment 2) FIG. 8 is a cross-sectional view of a main part of the head unit 2 according to Embodiment 2 of the present invention. Note that the same members as those in the above-described embodiment are denoted by the same reference numerals, and redundant descriptions are omitted.

[0084] As shown in FIG. 8, in the head unit 2 of the present embodiment, the intake port 53 is provided at the -X direction side end of the fourth wall portion 51d of the cover 50. Further, the exhaust port 54 is provided at the +X direction side end of the fourth wall portion 51d. That is, both the intake port 53 and the exhaust port 54 are arranged at positions not facing the flow path connection portion 12. Further, the flow path connection portion 12 is arranged at a position farther in the -X direction than the first wall portion 51a. For this reason, the flow path connection portion 12 is arranged closer to the intake port 53 than the exhaust port 54. That is, in the direction along the X axis, the distance L3 between the flow path connection portion 12 and the intake port 53 is smaller than the distance L2 between the flow path connection portion 12 and the exhaust port 54. That is, the distance L3 and the distance L2 satisfy the relationship L3 < L2.

[0085] Note that, regarding other configurations of the head unit 2, since they are the same as those in the above-described embodiment, redundant descriptions are omitted.

[0086] In the head unit 2 of this embodiment, by arranging the flow path connection portion 12 near the intake port 53, compared with the configuration in which the flow path connection portion 12 is arranged near the exhaust port, the heat of the circuit board 40 is less likely to be transmitted to the flow path connection portion 12, and the ink in the flow path connection portion 12 is less likely to be heated. Thus, since the ink in the flow path connection portion 12 is less likely to be heated by the circuit board 40, it is possible to suppress a decrease in the viscosity of the ink supplied from the flow path connection portion 12 to the liquid ejection head 100, suppress a decrease in the ejection characteristics of the ink ejected from the liquid ejection head 100, and suppress the occurrence of ink ejection failure.

[0087] (Embodiment 3) FIG. 9 is a cross-sectional view of a main part of the head unit 2 according to Embodiment 3 of the present invention. Note that the same members as those in the above-described embodiment are denoted by the same reference numerals, and redundant descriptions are omitted.

[0088] As shown in FIG. 9, in the head unit 2 of this embodiment, the intake port 53 is provided at the -X direction side end of the ceiling portion 51e of the cover 50. Further, the exhaust port 54 is provided in the second wall portion 51b. That is, both the intake port 53 and the exhaust port 54 are arranged at positions not facing the flow path connection portion 12. Also, the flow path connection portion 12 is arranged at a position farther in the -X direction than the first wall portion 51a. For this reason, the flow path connection portion 12 is arranged closer to the intake port 53 than the exhaust port 54. That is, in the direction along the X axis, the distance L4 between the flow path connection portion 12 and the intake port 53 is smaller than the distance L5 between the flow path connection portion 12 and the exhaust port 54. That is, the distance L4 and the distance L5 satisfy the relationship L4 < L5.

[0089] Also, in this embodiment, the circuit board 40 is arranged such that the thickness direction is the same as the +Y direction. That is, the circuit board 40 and the heat sink 42 are provided side by side along the +Y direction.

[0090] Note that since other configurations of the head unit 2 are the same as those in the above-described embodiment, redundant descriptions are omitted.

[0091] In the head unit 2 of this embodiment, by arranging the flow path connection part 12 near the intake port 53, heat from the circuit board 40 is less likely to be transferred to the flow path connection part 12 and the ink in the flow path connection part 12 is less likely to be heated than in a configuration in which the flow path connection part 12 is arranged near the exhaust port. In this way, since the ink in the flow path connection part 12 is less likely to be heated by the circuit board 40, a decrease in the viscosity of the ink supplied from the flow path connection part 12 to the liquid jet head 100 is suppressed, and a decrease in the jetting characteristics of the ink jetted from the liquid jet head 100 is suppressed, thereby suppressing the occurrence of ink jetting defects.

[0092] (Embodiment 4) Fig. 10 is a cross-sectional view of a main part of a head unit 2 according to a fourth embodiment of the present invention. Fig. 11 is a cross-sectional view of a main part taken along line BB' in Fig. 10. Note that the same members as those in the above-described embodiments are given the same reference numerals, and redundant explanations will be omitted.

[0093] As shown in the figure, the flow path member 10 constituting the head unit 2 of this embodiment has a flow path member main body 11 and two flow path connection portions 12. The two flow path connection portions 12 are provided at the +X direction end and the -X direction end of the flow path member main body 11, respectively. In this embodiment, one flow path connection portion 12 provided in the -X direction is referred to as the first flow path connection portion 12A, and the other flow path connection portion 12 provided in the +X direction is referred to as the second flow path connection portion 12B. Hereinafter, when there is no need to distinguish between the first flow path connection portion 12A and the second flow path connection portion 12B, they will be collectively referred to as the flow path connection portion 12. A plurality of first inlets S1 are provided on the side surface of each flow path connection portion 12 in the +Y direction. In this embodiment, four first inlets S1 are provided for each flow path connection portion 12, for a total of eight first inlets S1. Of course, the number of first inlets S1 is not limited to this. When four first inlets S1 are provided as in the first embodiment described above, two first inlets S1 may be provided in each of the two flow path connecting units 12, or different numbers of first inlets S1 may be provided in each of the two flow path connecting units 12. One of the flow path connecting units 12 may be provided with a first inlet S1, and the other flow path connecting unit 12 may be provided with an outlet of a recovery flow path for discharging ink not ejected from the liquid jet head 100 to the outside of the head unit 2. Furthermore, the first flow path connecting unit 12A is disposed at a distance from the first wall unit 51a in the -X direction. Furthermore, the second flow path connecting unit 12B is disposed at a distance from the second wall unit 51b in the +X direction.

[0094] The cover 50 is provided with two air inlets 53 and one air outlet 54. The air inlets 53 are provided at the +X-direction end and the -X-direction end of the fourth wall portion 51d, respectively. In the present embodiment, one air inlet 53 provided in the -X direction is referred to as the first air inlet 53A, and the air inlet 53 provided in the +X direction is referred to as the second air inlet 53B. Hereinafter, when the first air inlet 53A and the second air inlet 53B are not distinguished, they are collectively referred to as the air inlet 53. The flow path connection portion 12 is disposed closer to the air inlet 53 than to the air outlet 54. That is, the first flow path connection portion 12A is disposed closer to the first air inlet 53A than to the air outlet 54. That is, in the direction along the X axis, the distance L6 between the first flow path connection portion 12A and the first air inlet 53A is smaller than the distance L7 between the first flow path connection portion 12A and the air outlet 54. That is, the distance L6 and the distance L7 satisfy the relationship L6 < L7. Also, the second flow path connection portion 12B is disposed closer to the second air inlet 53B than to the air outlet 54. That is, in the direction along the X axis, the distance L8 between the second flow path connection portion 12B and the second air inlet 53B is smaller than the distance L9 between the second flow path connection portion 12B and the air outlet 54. That is, the distance L8 and the distance L9 satisfy the relationship L8 < L9. That is, each of the two flow path connection portions 12 is disposed closer to either one of the two air inlets 53 than to the air outlet 54.

[0095] Note that, regarding other configurations of the head unit 2, since they are the same as those in the above-described embodiment, redundant descriptions are omitted.

[0096] In such a head unit 2 of the present embodiment, by disposing the flow path connection portion 12 near the air inlet 53, the heat of the circuit board 40 is less likely to be transmitted to the flow path connection portion 12 compared to a configuration where the flow path connection portion 12 is disposed near the air outlet, and the ink in the flow path connection portion 12 is less likely to be heated. Thus, since the ink in the flow path connection portion 12 is less likely to be heated by the circuit board 40, it is possible to suppress a decrease in the viscosity of the ink supplied from the flow path connection portion 12 to the liquid ejection head 100, suppress a decrease in the ejection characteristics of the ink ejected from the liquid ejection head 100, and suppress the occurrence of ink ejection failures.

[0097] (Embodiment 5) 12 is a cross-sectional view of a main part of a head unit 2 according to embodiment 5 of the present invention. Note that the same members as those in the above-described embodiments are given the same reference numerals, and redundant explanations will be omitted.

[0098] As shown in FIG. 12, the cover 50 of the head unit 2 of this embodiment is provided with an intake port 53 and an exhaust port 54 similar to those of the first embodiment described above.

[0099] A filter 60 is provided on the first wall portion 51a where the air intake 53 of the cover 50 opens. The filter 60 captures foreign matter, such as mist generated by ink ejection and paper dust and dirt generated during transport of the medium S, when air is drawn through the air intake 53, to prevent the foreign matter from being drawn into the second storage portion 51. Examples of such a filter 60 include a sheet-like member having multiple micropores formed by finely weaving metal, a plate-like member such as a single metal plate or resin plate having multiple through-holes, and nonwoven fabric. In this embodiment, the filter 60 is provided to cover the entire opening of the air intake 53. Instead of the filter 60, a gas-liquid separation membrane that allows gas to pass but not liquid may be provided on the first wall portion 51a where the air intake 53 of the cover 50 opens. This configuration also prevents mist and other foreign matter from being drawn into the second storage portion 51.

[0100] The other configurations of the head unit 2 are the same as those in the above-described embodiment, and therefore, redundant explanations will be omitted.

[0101] As described above, in the head unit 2 of this embodiment, the cover 50 includes a filter 60 provided in the air intake 53. Providing the filter 60 in the air intake 53 in this manner can prevent foreign matter such as ink mist and paper dust from entering the second housing portion 51 through the air intake 53. This prevents short circuits in electronic components and wiring caused by foreign matter adhering to the circuit board 40, and also prevents a reduction in the cooling effect of the heat sink 42 due to the foreign matter. Furthermore, the flow path connecting portion 12 is provided in a position facing the air intake 53. Therefore, providing the filter 60 can capture ink that leaks when the tube 3a is attached to or detached from the flow path connecting portion 12, thereby preventing ink from entering the second housing portion 51 through the air intake 53.

[0102] Fig. 13 is a diagram showing a modified example of head unit 2 according to embodiment 5 of the present invention. As shown in Fig. 13, filter 60 includes a first portion 61 that covers the -Z direction side of intake port 53, and a second portion 62 that is bent at 90 degrees relative to the first portion and protrudes like a canopy in the -X direction.

[0103] Inside the inkjet recording device 1, when the medium S is transported toward the -Z direction side of the head unit 2, foreign matter such as paper powder and dust falls on the head unit 2 from the -Z direction during transport of the medium S. For this reason, by providing the second portion 62 in the filter 60, the foreign matter can be caught by the second portion 62. Furthermore, by providing the first portion 61, the foreign matter caught by the second portion 62 can be captured by the first portion 61 so that it is not sucked into the second housing portion 51 through the intake port 53. Therefore, it is possible to effectively prevent foreign matter from entering the second housing portion 51 through the intake port 53.

[0104] Furthermore, filter 60 does not cover the +Z direction side of air intake port 53. Therefore, filter 60 is prevented from reducing the suction force of air drawn in from air intake port 53, and the inside of second housing section 51 can be efficiently cooled by air.

[0105] The filter 60 may be provided detachably on the cover 50. This allows the filter 60 to be easily replaced, improving maintainability.

[0106] A mechanism for removing foreign matter adhering to the filter 60 may also be provided. For example, a wiping mechanism for wiping the filter 60 may be provided. Alternatively, a mechanism for periodically feeding out the rolled filter 60 may be provided so that the area of ​​the filter 60 free of foreign matter covers the air intake 53. Providing such a mechanism allows the filter 60 to be used for a long period of time, eliminating the need for frequent replacement of the filter 60 and improving maintainability. Costs can be reduced by using a drive source, such as one provided in the inkjet recording apparatus 1 for moving the head unit 2 along the Z axis, as the drive source for the mechanism for wiping or feeding out the filter 60. Of course, if the air intake 53 is connected to the outside of the inkjet recording apparatus 1 via a suction duct, the filter 60 can capture dust and other particles from outside the inkjet recording apparatus 1. If the air intake 53 is connected to the outside of the inkjet recording apparatus 1 via a suction duct, the filter 60 may be provided midway through the air intake duct or on the outer surface of the inkjet recording apparatus 1.

[0107] (Other embodiments) Although the embodiments of the present invention have been described above, the basic configuration of the present invention is not limited to those described above.

[0108] For example, in each of the above-described embodiments, the first inlet S1 is configured to open on the side surface of the flow path connecting portion 12 in the +Y direction, but this is not particularly limited, and the first inlet S1 may be opened on the surface in the -Z direction. Of course, the first inlet S1 may also be provided on the surface in the -Y direction or the -X direction of the flow path connecting portion 12.

[0109] Furthermore, the inkjet recording device 1 in each of the above-described embodiments is a line-type recording device that performs printing with the head unit 2 fixed to the device body 6, but is not limited to this, and may be a so-called serial-type recording device that performs printing while moving the head unit 2 in a direction that intersects the +Y direction, which is the transport direction of the medium S, for example, in the +X direction and -X direction.

[0110] Furthermore, in each of the above-described embodiments, the circuit board 40 is provided with a heat sink 42, but this is not particularly limited, and the heat sink 42 may not be provided. That is, the circuit board 40 may be accommodated in the second accommodation portion 51, and the circuit board 40 may be directly cooled by air. Furthermore, the circuit board 40 may be composed of multiple boards. The circuit board 40 may have, for example, a board on which a drive signal generation circuit is provided, and an intermediate board that relays the connection between this board and connection wiring and external wiring. Of course, the circuit board 40 may be composed of multiple boards stacked along the Z axis, or may be divided into two or more boards along the +X direction.

[0111] Furthermore, in each of the above-described embodiments, the intake port 53 is configured to suck in air from inside the inkjet recording device 1, but this is not particularly limited to this. One end of an intake duct connected to the intake port 53 may be opened to the outside of the inkjet recording device 1, i.e., to the outer surface of the device main body 6, and air from outside the inkjet recording device 1 may be sucked into the second storage section 51 via the intake duct.

[0112] Furthermore, the present invention is broadly intended for head units in general, and can be applied to, for example, head units using recording heads such as various inkjet recording heads used in image recording devices such as printers, colorant jetting heads used in manufacturing color filters for liquid crystal displays and the like, electrode material jetting heads used in forming electrodes for organic EL displays, FEDs (field emission displays), etc., bioorganic material jetting heads used in manufacturing biochips, etc. Also, although the inkjet recording device 1 has been described as an example of a liquid jetting device, the present invention can also be used in liquid jetting devices having head units using the other liquid jetting heads described above. [Explanation of symbols]

[0113] 1...liquid ejection device (ink jet recording device), 2...head unit, 2a...ejection surface, 3...liquid storage section, 3a...tube (external flow path member), 4...control unit, 5...transport mechanism, 5a...transport roller, 6...device main body, 10...flow path member, 11...flow path member main body, 12...flow path connection section, 12A...first flow path connection section, 12B...second flow path connection section, 20...unit base, 21...head housing section, 22...first housing section, 23...flange section, 30...liquid ejection section, 40...circuit board, 41...connector, 42...heat sink, 50...cover, 51...second housing section, 51a...first wall section, 51b...second wall section, 51c...third wall section, 51d...fourth Wall portion, 51e...ceiling portion, 52...extension portion, 52a...opening portion, 53...intake port, 53A...first intake port, 53B...second intake port, 54...exhaust port, 55...exhaust fan, 56...exhaust duct, 60...filter, 61...first portion, 62...second portion, 100...liquid ejection head, 110...filter portion, 111...flow path filter, 120...wiring board, 121...connecting wiring, 130...holder, 131...holding portion, 132...wiring insertion hole, 140...head chip, 141...wiring member, 150...fixing plate, 151...exposure opening, N...nozzle, S...medium, S1...first inlet, S2...second inlet, S3...third inlet, S4...fourth inlet, D...exhaust port

Claims

1. A head unit that ejects liquid, a circuit board for driving the head unit; a housing including a cover defining an accommodation space for accommodating the circuit board; A flow path connecting portion for connecting to a flow path member outside the head unit is included, and a part of the a flow path member disposed within the housing; Equipped with the external flow path member includes a flexible tube, the flow path member does not include a flexible tube, The cover has an air intake port for drawing air from the outside of the cover into the accommodation space. an exhaust port for discharging air that has passed through the storage space, The flow path connection portion is disposed outside the housing, and the entirety of the flow path connection portion is closer to the intake port than the exhaust port. Located near the air vent, A head unit characterized by:

2. The external flow path member is provided with a flow path needle or a flow path pipe that is a rigid body, The flow path connecting portion has flexibility for liquid-tight connection with the flow path needle or the flow path pipe. a sealing member for 2. The head unit according to claim 1.

3. When viewed in the direction in which the head unit ejects liquid, the flow path connection portion is entirely covered by the cover. - does not overlap, 3. The head unit according to claim 1 or 2.

4. The intake port faces the flow path connection portion.

4. The head unit according to claim 1, wherein the head unit is a light source.

5. A head unit that ejects liquid, a circuit board for driving the head unit; a housing including a cover defining an accommodation space for accommodating the circuit board; A flow path connecting portion for connecting to a flow path member outside the head unit is included, and a part of the a flow path member disposed within the housing; Equipped with The cover has an air intake port for drawing air from the outside of the cover into the accommodation space. an exhaust port for discharging air that has passed through the storage space, The flow path connection portion is disposed outside the housing and is closer to the intake port than the exhaust port. Located nearby, The intake port faces the flow path connection portion. A head unit characterized by:

6. The distance between the intake port and the flow path connection portion is equal to or greater than the maximum width of the intake port.

6. The head unit according to claim 4 or 5.

7. an opening of the flow path formed in the flow path connecting portion does not face the intake port; 7. The head unit according to claim 4, wherein the head unit is a light source.

8. The exhaust port does not face the flow path connection portion.

8. The head unit according to claim 1, wherein the head unit is a light source.

9. The air drawn in through the intake port moves in a first direction from the intake port to the exhaust port. Move, The flow path connection portion, the intake port, and the exhaust port are arranged in this order in the first direction. 、 9. The head unit according to claim 1, wherein the head unit is a light source.

10. A head unit for ejecting liquid, comprising: a circuit board for driving the head unit; a housing including a cover defining an accommodation space for accommodating the circuit board; A flow path connecting portion for connecting to a flow path member outside the head unit is included, and a part of the a flow path member disposed within the housing; Equipped with The cover has an air intake port for drawing air from the outside of the cover into the accommodation space. an exhaust port for discharging air that has passed through the storage space, The flow path connection portion is disposed outside the housing and is closer to the intake port than the exhaust port. Located nearby, The air drawn in through the intake port moves in a first direction from the intake port to the exhaust port. Move, The flow path connection portion, the intake port, and the exhaust port are arranged in this order in the first direction. 、 the circuit board has the first direction as a longitudinal direction, The intake port is a portion of the space in the accommodation space extending from the intake port to the exhaust port. provided on one end side in the first direction, the exhaust port is provided on the other end side of the space in the first direction, The exhaust port exhausts air in a second direction different from the first direction. A head unit characterized by:

11. A head unit for ejecting liquid, comprising: a circuit board for driving the head unit; a housing including a cover defining an accommodation space for accommodating the circuit board; A flow path connecting portion for connecting to a flow path member outside the head unit is included, and a part of the a flow path member disposed within the housing; Equipped with The cover has an air intake port for drawing air from the outside of the cover into the accommodation space. an exhaust port for discharging air that has passed through the storage space, The flow path connection portion is disposed outside the housing and is closer to the intake port than the exhaust port. Located nearby, The air drawn in through the intake port moves in a first direction from the intake port to the exhaust port. Move, The flow path connection portion, the intake port, and the exhaust port are arranged in this order in the first direction. 、 The head unit is a line-type liquid ejection head having a plurality of liquid ejection heads arranged in the first direction. head, the circuit board is a circuit board common to the plurality of liquid jet heads; A head unit characterized by:

12. the head unit has an ejection surface on which a plurality of nozzles for ejecting liquid are formed, the flow path connection portion overlaps with the accommodation space in a direction perpendicular to the ejection surface; 12. The head unit according to claim 1, wherein the head unit is a light source.

13. The thickness direction of the circuit board is the same as the direction perpendicular to the ejection surface.

13. The head unit according to claim 12.

14. a heat sink disposed in the accommodation space for dissipating heat from the circuit board; picture, a portion of the flow path member is disposed within the accommodation space, The circuit board is connected to the part of the flow path member disposed in the accommodation space and the heat sink. The casing is placed between the 14. The head unit according to claim 13.

15. Air is introduced from outside the cover through the air intake by a blower mechanism. The head unit according to any one of claims 1 to 14.

16. A head unit according to any one of claims 1 to 15; a liquid storage section that stores liquid to be supplied to the head unit; A liquid ejection device comprising:

Images