Inkjet head

Abstract

To provide a technique that enables piping extending from an external ink supply part to be easily connected to an ejection part unit, when supplying ink to an inner tank that temporarily stores ink inside the ejection part unit.SOLUTION: An inkjet head comprises an ejection part unit 51 that ejects ink in response to a driving signal and a driving substrate unit 52 that outputs the driving signal. The ejection part unit 51 has: a base plate 511; an inner tank that temporarily stores ink ejected from an ejection port; supply-side ink piping 515 through which ink to be supplied to the inner tank is passed; and first openings formed in exposed parts 401 and 402 of the base plate 511 and communicated with the inner tank. The supply-side ink piping 515 is connected to the first opening, at an end part at one side in an axial direction and extended to the other side in the axial direction along a side wall 101 of a housing 521, where an end part at the other side in the axial direction is positioned closer to the other side than a top plate 102 of the housing 521.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an inkjet head that discharges ink onto a printing medium to perform printing.

Background Art

[0002] Conventionally, an inkjet printing apparatus that prints characters and images by discharging ink from a discharge port onto a printing medium conveyed in a predetermined direction is known. In such a printing apparatus, a discharge unit that discharges ink from the discharge port is provided. Inside the discharge unit, an internal tank that temporarily stores ink and an ink flow path that connects from the internal tank to the outside of the discharge unit are formed. For example, in the recording apparatus (1) disclosed in Patent Document 1, in a discharge unit housing (20) that houses a recording head (7) capable of discharging ink, an ink flow path (46) (liquid flow path) that connects from an ink cartridge (liquid storage unit) to the recording head 7 capable of discharging ink (liquid) is formed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The ink flow path (46) formed in the discharge unit housing (20) of the recording apparatus (1) of Patent Document 1 opens to the side wall of the discharge unit housing (20). Therefore, when replenishing ink from an external ink supply unit to the ink cartridge, a pipe or the like extending from the ink supply unit must be connected to the opening of the ink flow path 46 on the side wall of the discharge unit housing (20). For this reason, an operator must perform these connections on the side of the discharge unit housing (20) with limited space, so the work is difficult and there is a risk of reduced efficiency.

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a technique capable of easily connecting a pipe extending from an external ink supply unit to a discharge unit when supplying ink to an internal tank that temporarily stores the ink inside the discharge unit.

Means for Solving the Problems

[0006] To solve the above problems, a first invention of the present application is an inkjet head that discharges ink onto a printing medium, and includes a discharge unit unit that discharges the ink in response to a drive signal, and a drive board unit that supplies the drive signal to the discharge unit unit. The discharge unit unit includes a base plate, a discharge unit that is disposed on the base plate and discharges the ink from a discharge port, and a discharge unit side connector that receives the drive signal. The drive board unit includes a drive board that generates the drive signal, a drive board side connector that outputs the drive signal, and a housing that holds the drive board and the drive board side connector. The drive board unit is detachable from the discharge unit unit along an axial direction orthogonal to the base plate. In a state where the housing is attached to the discharge unit unit, the drive board side connector and the discharge unit side connector are connected, and an exposed portion is formed where a part of the base plate is exposed. The discharge unit has an internal tank that temporarily stores the ink discharged from the discharge port. The discharge unit unit further includes a supply side ink pipe that allows the ink supplied to the internal tank to pass through, and a first opening that is formed in the exposed portion and communicates with the internal tank. The housing has a side wall that expands in a cylindrical shape along the axial direction, and a top plate that covers one end of the side wall on the side away from the base plate in the axial direction. The supply side ink pipe is connected to the first opening at an end on the other side opposite to the one side in the axial direction, extends to the one side along the side wall, and the end on the one side in the axial direction is located on the one side of the top plate.

[0007] The second invention of the present application is the inkjet head of the first invention, wherein the drive substrate unit is fixed to the side wall of the housing, and further has a locking member that detachably locks an intermediate portion in the axial direction of the supply-side ink pipe.

[0008] The third invention of the present application is the inkjet head of the first invention or the second invention, wherein the discharge unit has a discharge-side ink pipe through which the ink discharged from the internal tank passes, and a second opening formed in the exposed portion and communicating with the internal tank. The discharge-side ink pipe is connected to the second opening at the other end in the axial direction and extends along the side wall to the one side.

[0009] The fourth invention of the present application is the inkjet head of the third invention, wherein the internal tank includes a first internal tank on the ink supply side and a second internal tank on the ink discharge side. The first internal tank communicates with the discharge port and the first opening respectively, and the second internal tank communicates with the discharge port and the second opening respectively.

[0010] The fifth invention of the present application is the inkjet head of the third invention or the fourth invention, wherein the drive substrate unit is disposed between the drive substrate and the inner surface of the housing, and has a cooling jacket for cooling the drive substrate by allowing a cooling medium to flow inside, a supply-side cooling pipe for passing the cooling medium supplied to the cooling jacket, and a connection port formed in the side wall to which the cooling jacket is connected. The supply-side cooling pipe is connected to the connection port at the other end and extends along the side wall to the one side. In a state where the discharge unit and the drive substrate unit are attached to each other, the connection port, the first opening, and the second opening are spaced apart in the axial direction.

Advantages of the Invention

[0011] According to the first to fourth inventions of the present application, one end of the supply-side ink pipe communicating with the internal tank for temporarily storing ink is located on one side in the axial direction further than the top plate of the housing. Thereby, an operator can connect the supply-side ink pipe and the pipe extending from an external ink supply unit on one side in the axial direction rather than the housing. As a result, since the operator can perform the connection work without accessing the side of the housing with limited space, the work efficiency is improved.

[0012] Moreover, according to the second invention of the present application, since the supply-side ink pipe can be locked to the side wall of the housing, bending and entanglement of the supply-side ink pipe can be suppressed.

[0013] Furthermore, according to the fifth invention of the present application, it is possible to suppress the temperature of the cooling medium passing through the supply-side cooling pipe and the temperature of the ink passing through the supply-side ink pipe and the discharge-side ink pipe from influencing each other.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the components described in this embodiment are merely examples, and are not intended to limit the scope of the present invention thereto. Also, in the drawings, for ease of understanding, the dimensions and numbers of each part may be exaggerated or simplified as necessary.

[0016] <1. First Embodiment> <1-1. Configuration of Printing Device> FIG. 1 is a diagram conceptually showing the configuration of a printing device 1 according to an embodiment of the present invention. However, in FIG. 1, the illustration of an ink supply unit 28 described later is omitted. This printing device 1 is an inkjet type continuous accounting printer that records characters and images on the surface of a continuous paper 9 by discharging ink droplets from a plurality of inkjet heads 351 toward the continuous paper 9 while conveying the long strip-shaped continuous paper 9. Note that the long strip-shaped continuous paper 9 is an example of a printing medium. The printing medium may be a plastic film or the like. Also, the printing medium may be a cardboard, a metal foil, or a glass substrate.

[0017] This printing device 1 includes a paper feeding unit 21, a front surface printing unit 23, a reversing unit 25, a back surface printing unit 27, a plurality (eight in this embodiment) of ink supply units 28, and a control unit 29.

[0018] The paper feeding unit 21 supplies the continuous paper 9 to the front surface printing unit 23. The paper feeding unit 21 rotatably holds the roll-shaped continuous paper 9 around a horizontal axis. The paper feeding unit 21 rotates the roll-shaped continuous paper 9 to send out the continuous paper 9 to the front surface printing unit 23.

[0019] The surface printing unit 23 is a device that prints on one of the main surfaces (the largest surface) of both sides of the continuous paper 9 while transporting the continuous paper 9 in the transport direction indicated by the dashed arrow in Fig. 1. The surface printing unit 23 includes a drive unit 31, a plurality of transport rollers 33, a printing unit 35, and a drying unit 37. Hereinafter, the downstream side in the transport direction is simply referred to as the "downstream side". Note that the number and arrangement of the transport rollers 33 in Fig. 1 are examples. That is, in Fig. 1, two transport rollers 33 are shown for each of the printing units 23 and 27, but the number of transport rollers 33 may be more or less than this.

[0020] The drive unit 31 takes in the continuous paper 9 from the paper feeding unit 21 into the surface printing unit 23. The drive unit 31 is composed of, for example, a plurality of rollers. The plurality of transport rollers 33 are located on the downstream side of the drive unit 31. The continuous paper 9 is transported in the transport direction while being supported by the plurality of transport rollers 33 by the drive unit 31.

[0021] The printing unit 35 is located on the downstream side of the drive unit 31. The printing unit 35 includes a plurality (four in this embodiment) of inkjet heads 351. Each of the four inkjet heads 351 ejects ink droplets onto the main surface of the continuous paper 9. The four inkjet heads 351 are arranged at intervals in the transport direction. In this embodiment, the four inkjet heads 351 eject inks of different colors (for example, cyan, magenta, yellow, black). The detailed structure of the inkjet head 351 will be described later.

[0022] The drying unit 37 is located on the downstream side of the printing unit 35. The drying unit 37 dries the ink applied to the continuous paper 9 by the printing unit 35. The drying unit 37 raises the temperature of the continuous paper 9 or the periphery of the continuous paper 9, for example, by blowing hot air onto the continuous paper 9 or by applying radiant heat from a heat source such as an electric heater to the continuous paper 9. Further, the drying unit 37 may include, for example, a heat roller. The temperature of the continuous paper 9 may be raised by bringing the heat roller into contact with the continuous paper 9.

[0023] The reversing unit 25 reverses the front and back sides of the continuous paper 9 sent out from the surface printing unit 23. Further, the continuous paper 9 reversed by the reversing unit 25 is fed into the back surface printing unit 27.

[0024] The back surface printing unit 27 performs printing on the other main surface of the continuous paper 9 whose front and back sides have been reversed by the reversing unit 25. Since the back surface printing unit 27 has the same configuration as the surface printing unit 23, duplicate description is omitted. The continuous paper 9 that has passed through the back surface printing unit 27 is further conveyed to the downstream side and is wound up and collected, for example, in a roll shape around a horizontal axis in a collecting unit (not shown).

[0025] Next, the ink supply unit 28 will be described. The ink supply unit 28 supplies the temperature-adjusted ink to the inkjet head 351 while circulating the ink with the inkjet head 351. The printing apparatus 1 of the present embodiment has a total of eight ink supply units 28, namely, four ink supply units 28 corresponding to the four inkjet heads 351 of the surface printing unit 23 and four ink supply units 28 corresponding to the four inkjet heads 351 of the back surface printing unit 27. Since the structures of the eight ink supply units 28 are equivalent, only the structure of one ink supply unit 28 will be described below.

[0026] FIG. 2 is a diagram conceptually showing the configuration of one ink supply unit 28 and one inkjet head 351. Each inkjet head 351 has a plurality (five in the present embodiment) of head assemblies 50. The five head assemblies 50 have the same structure as each other. For this reason, in FIG. 2, four of the five head assemblies 50 are shown in a more simplified manner. As shown in FIG. 2, the ink supply unit 28 has a storage tank 281, a supply pump 282, a reflux pump 284, and a pipe 285. The pipe 285 includes a first supply pipe 91, a plurality (five in the present embodiment) of second supply pipes 92, a plurality (five in the present embodiment) of first reflux pipes 93, and a second reflux pipe 94.

[0027] The storage tank 281 is a container for storing ink. The storage tank 281 is equipped with a temperature adjustment mechanism (not shown) for adjusting the temperature of the stored ink. The first supply pipe 91 and the five second supply pipes 92 are pipes connecting the storage tank 281 and each head assembly 50. That is, the storage tank 281 is connected to each head assembly 50 via the first supply pipe 91 and the second supply pipes 92. One end of the first supply pipe 91 is communicatively connected to the inside of the storage tank 281 near the lower end of the storage tank 281. Also, the other end of the first supply pipe 91 is communicatively connected to one end of each of the five second supply pipes 92.

[0028] The first supply pipe 91 has a first on-off valve 286, a supply pump 282, and a filter 290 inserted therein. The first on-off valve 286 is disposed between the storage tank 281 and the supply pump 282. Also, the filter 290 is disposed between the supply pump 282 and the other end of the first supply pipe 91. However, the position where the filter 290 is disposed is not limited thereto.

[0029] The supply pump 282 is a liquid feeding means for sending ink from the storage tank 281 to each head assembly 50. The supply pump 282 generates a flow of ink from the storage tank 281 toward each head assembly 50 inside the first supply pipe 91 according to an operation signal from the control unit 29. Thereby, the ink stored and temperature-adjusted inside the storage tank 281 is supplied to each head assembly 50 via the first supply pipe 91 and the second supply pipes 92.

[0030] When the first on-off valve 286 is in the closed state, the communication of the first supply pipe 91 is blocked. That is, when the first on-off valve 286 is in the closed state, the communication between the storage tank 281 and each head assembly 50 is blocked. On the other hand, when the first on-off valve 286 is in the open state, the communication of the first supply pipe 91 is ensured. During the operation of the printing apparatus 1, the first on-off valve 286 is normally in the open state.

[0031] The filter 290 removes solid components and foreign matters in the ink passing through the first supply pipe 91. This suppresses the mixing of solid components and foreign matters into the ink supplied to each head assembly 50.

[0032] The other end of each of the five second supply pipes 92 is communicatively connected to one end of a supply-side ink pipe 515 (to be described later) of the head assembly 50. The other end of the supply-side ink pipe 515 communicates with an internal tank 82 of the head assembly 50 and is communicatively connected to a first opening 410 for supplying ink to a nozzle 83 via the internal tank 82. Thus, the ink stored inside the storage tank 281 is supplied to the internal tank 82 of the head assembly 50 via the first supply pipe 91, the second supply pipe 92, the supply-side ink pipe 515, and the first opening 410.

[0033] Note that the head assembly 50 is equipped with a liquid level sensor (not shown). The liquid level sensor is a sensor that detects the liquid level height of the ink stored in the internal tank 82. Based on a signal from the liquid level sensor, the control unit 29 detects the liquid level height of the ink in the internal tank 82 and determines whether to supply ink to the internal tank 82. When supplying ink from the storage tank 281 to the internal tank 82, the control unit 29 opens the first on-off valve 286 and operates the supply pump 282. When stopping the supply of ink from the storage tank 281 to the internal tank 82, the control unit 29 stops the supply pump 282 and closes the first on-off valve 286.

[0034] The five first reflux pipes 93 and the second reflux pipe 94 are pipes that connect each head assembly 50 and the storage tank 281. One end of each of the five first reflux pipes 93 is communicatively connected to one end of a discharge-side ink pipe 516 (to be described later) of the head assembly 50. The other end of the discharge-side ink pipe 516 is communicatively connected to a second opening 420 that communicates with the internal tank 82 of the head assembly 50. Also, the other end of each of the five first reflux pipes 93 is communicatively connected to one end of the second reflux pipe 94. The other end of the second reflux pipe 94 is communicatively connected to the inside of the storage tank 281.

[0035] A second on-off valve 287 is inserted into each first reflux pipe 93. When the second on-off valve 287 is in the closed state, the communication of the first reflux pipe 93 into which the second on-off valve 287 is inserted is blocked. That is, when the second on-off valve 287 is in the closed state, the communication between the internal tank 82 of the corresponding head assembly 50 and the second reflux pipe 94 is blocked. On the other hand, when the second on-off valve 287 is in the open state, the communication of the first reflux pipe 93 into which the second on-off valve 287 is inserted is ensured. That is, when the second on-off valve 287 is in the open state, the communication between the internal tank 82 of the corresponding head assembly 50 and the second reflux pipe 94 is ensured.

[0036] A reflux pump 284 and a third on-off valve 288 are inserted into the second reflux pipe 94. The reflux pump 284 is a liquid feeding means for sending ink from the internal tank 82 of each head assembly 50 to the storage tank 281. The reflux pump 284 generates a flow of ink from each first reflux pipe 93 toward the storage tank 281 inside the second reflux pipe 94 according to an operation signal from the control unit 29. Thereby, the ink stored in the internal tank 82 of each head assembly 50 (the ink that has stayed in the internal tank 82 without being discharged and whose temperature has decreased) is refluxed to the storage tank 281 through the second opening 420, the discharge-side ink pipe 516, the first reflux pipe 93, and the second reflux pipe 94. Thereby, the temperature, viscosity, etc. of the ink stored in the internal tank 82 of the head assembly 50 can be maintained within an appropriate range. As a result, the deterioration of the ink discharged from each head assembly 50 can be suppressed, and the printing quality can be improved.

[0037] The third on-off valve 288 is disposed between the reflux pump 284 and the storage tank 281. When the third on-off valve 288 is in the closed state, the communication of the second reflux pipe 94 is blocked. That is, when the third on-off valve 288 is in the closed state, the communication between each first reflux pipe 93 and the storage tank 281 is blocked. On the other hand, when the third on-off valve 288 is in the open state, the communication of the second reflux pipe 94 is ensured. The third on-off valve 288 is set to the open state when the reflux pump 284 is operated to perform ink reflux from each head assembly 50 to the storage tank 281.

[0038] In the present embodiment, as described above, since the second on-off valve 287 is provided in each first reflux pipe 93, ink reflux can be performed for each individual head assembly 50. For example, when performing ink reflux from some of the head assemblies 50 to the storage tank 281, the second on-off valve 287 corresponding to the target head assembly 50 and the third on-off valve 288 are set to the open state, and the other second on-off valves 287 are set to the closed state, and the reflux pump 284 is operated.

[0039] Subsequently, the control unit 29 will be described. The control unit 29 is an information processing device for controlling the printing apparatus 1. FIG. 3 is a block diagram showing the connection between the control unit 29 and each part of the printing apparatus 1. As conceptually shown in FIG. 3, the control unit 29 includes a processor 291 such as a CPU, a memory 292 such as a RAM, and a storage unit 293 such as a hard disk drive. The storage unit 293 stores a computer program 29P for executing printing processing while transporting the continuous paper 9 and further supplying ink to the inkjet head 351.

[0040] Also, as shown in FIG. 3, the control unit 29 is communicably connected to the paper feeding unit 21, the drive unit 31 of the front surface printing unit 23, the four inkjet heads 351 of the printing unit 35, and the drying unit 37, the reversing unit 25, the drive unit 31 of the back surface printing unit 27, the four inkjet heads 351 of the printing unit 35, and the drying unit 37, the recovery unit, and the eight ink supply units 28, respectively. The control unit 29 controls the operations of these units according to the computer program 29P. As a result, the conveyance and printing processes of the continuous paper 9 proceed, and the ink circulates between the storage tank 281 and the inkjet head 351, and the temperature-adjusted ink is supplied to the internal tank 82.

[0041] <1-2. Detailed Structure of Inkjet Head> Subsequently, the detailed structure of the inkjet head 351 will be described. The inkjet head 351 is a processing unit that discharges ink droplets onto the conveyed continuous paper 9 to perform printing. As described above, the printing apparatus 1 has eight inkjet heads 351. Since the structures of the eight inkjet heads 351 are equivalent, only the structure of one inkjet head 351 will be described below.

[0042] Also, hereinafter, the longitudinal direction of the base plate that spreads in a plate shape and will be described later will be referred to as the "X direction", the short side direction of the base plate will be referred to as the "Y direction", and the direction orthogonal to the base plate will be referred to as the "axial direction", respectively. Also, hereinafter, for convenience of explanation, the "axial direction" will be the vertical direction, and with respect to the discharge unit unit to be described later, with the drive substrate unit attached to the discharge unit unit being above, the shape and positional relationship of each unit will be described. However, this definition of the vertical direction is not intended to limit the posture of the inkjet head according to the present invention during manufacturing and use. That is, the "upper side" can be read as "one side in the axial direction", and the "lower side" can be read as "the other side in the axial direction". Also, hereinafter, the "parallel direction" includes a substantially parallel direction. Also, the "orthogonal direction" includes a substantially orthogonal direction.

[0043] FIG. 4 is a perspective view of one inkjet head 351. As shown in FIG. 3, each inkjet head 351 has a plurality (five in this embodiment) of head assemblies 50, one head mounting unit 60, and a plurality (ten in this embodiment) of rod-shaped connecting members 70.

[0044] FIG. 5 is a perspective view of one head assembly 50 and two connecting members 70. FIG. 6 is an exploded perspective view of one head assembly 50 and two connecting members 70. As shown in FIGS. 5 and 6, the head assembly 50 has a discharge unit 51 and a drive substrate unit 52. The head assembly 50 is configured by mounting the discharge unit 51 and the drive substrate unit 52 to each other.

[0045] The discharge unit 51 discharges ink according to a drive signal described later. FIG. 7 is a longitudinal sectional view of the discharge unit 51 of FIG. 6 as seen from the direction of arrow A1 after being cut along the plane S1 in FIG. 6. As shown in FIGS. 6 and 7, the discharge unit 51 has a base plate 511, a discharge unit 512, an adapter substrate 513, a discharge-side connector 514, a supply-side ink pipe 515, and a discharge-side ink pipe 516. However, in FIG. 7, the illustration of the supply-side ink pipe 515 is omitted.

[0046] The base plate 511 is a plate-shaped member that extends perpendicular to the axial direction. FIG. 8 is a perspective view of the base plate 511. As shown in FIG. 8, the base plate 511 has a base through-hole 40, a first communication path 41, a second communication path 42, and two positioning grooves 431 and 432.

[0047] The base through-hole 40 is a through-hole that penetrates a portion located at the center in the X and Y directions of the base plate 511 in the axial direction orthogonal to the base plate 511. On the base plate 511, a head main body portion 81 (to be described later) of the discharge portion 512 is disposed. With the discharge portion 512 fixed to the base plate 511, the lower portion of the discharge portion 512 is located in the base through-hole 40. Also, with the discharge portion 512 fixed to the base plate 511, portions of the base plate 511 located at both ends in the X direction are exposed without being covered by the discharge portion 512. Thereby, exposed portions 401 and 402 where a part of the base plate 511 is exposed are formed. Further, a positioning fitting 403 is attached on the exposed portion 401, and a positioning fitting 404 is attached on the exposed portion 402. These positioning fittings 403 and 404 are members that fit with pins (not shown) erected on the head mounting unit 60, and are used as a reference when attaching the head assembly 50 to the head mounting unit 60.

[0048] The first communication passage 41 extends in a cavity shape from the base through-hole 40 inside the base plate 511 toward one end in the X direction and opens on the surface of the exposed portion 401. Thereby, a first opening 410 is formed on the surface of the exposed portion 401. The first opening 410 is an opening for supplying ink to the discharge portion 512. The second communication passage 42 extends in a cavity shape from the base through-hole 40 inside the base plate 511 toward the other end in the X direction and opens on the surface of the exposed portion 402. Thereby, a second opening 420 is formed on the surface of the exposed portion 402. Also, the first opening 410 and the second opening 420 are each formed on the surface of the base plate 511. For this reason, the first opening 410 and the second opening 420 are each located at the same position as the base plate 511 in the axial direction.

[0049] The positioning groove 431 is a through-hole formed by penetrating in the axial direction a portion of the exposed portion 401 of the base plate 511 that is located on one side in the X direction relative to the first opening 410. The positioning groove 432 is a through-hole formed by penetrating in the axial direction a portion of the exposed portion 402 of the base plate 511 that is located on the other side in the X direction relative to the second opening 420. However, the two positioning grooves 431 and 432 may be formed by notching a part of the exposed portions 401 and 402.

[0050] The ejection unit 512 is a processing unit that is disposed on the base plate 511 and ejects ink from the ejection port 830. As shown in FIG. 7, the ejection unit 512 includes a head main body 81, an internal tank 82, a plurality of nozzles 83, a bracket 84, a plurality (two in this embodiment) of hook portions 85, a plurality (two in this embodiment) of first protrusions 86, and a plurality (two in this embodiment) of second protrusions 87.

[0051] The head main body 81 is a hollow box-shaped housing having a rectangular cylindrical side wall 811, an upper lid portion 812, and a bottom surface portion 813. However, the bottom surface portion 813 is largely open, and a plurality of nozzles 83 are exposed downward. Hereinafter, among the side walls 811, the portions bent at right angles will be referred to as "corner portions 811a (see FIG. 6)". The head main body 81 is fixed to the base plate 511, for example, by screwing (not shown). Inside the head main body 81, an internal tank 82 capable of temporarily storing the ink ejected from the ejection port 830 is disposed. The first opening 410 of the base plate 511 communicates with the internal tank 82 via the first communication path 41. Also, the second opening 420 communicates with the internal tank 82 via the second communication path 42.

[0052] A plurality of nozzles 83 are arranged at equal intervals in the X direction and the Y direction with respect to each other at the lower part of the head main body 81. Each of the plurality of nozzles 83 communicates with the internal tank 82. Further, each of the plurality of nozzles 83 has a plurality of piezo elements 831 (see FIG. 2) as pressure generating elements, an ink chamber 832 (see FIG. 2), and a discharge port 830. The ink chamber 832 communicates with the internal tank 82. When ink is discharged, the ink flows down from the internal tank 82 into the ink chamber 832, and by the action of the piezo element 831, the ink in the ink chamber 832 is pressurized, and the ink is discharged as droplets from the discharge port 830. The piezo element 831 controls the presence or absence of pressure applied to the ink in the ink chamber 832 by input of a drive signal. However, the nozzle 83 may be a so-called thermal system in which a heater is used as a pressure generating element to heat the ink in the ink chamber 832 to generate bubbles (bubbles) to pressurize the ink.

[0053] A bracket 84 is further disposed inside the head main body 81. The bracket 84 is fixed to the side wall 811, for example. The thickness of the bracket 84 is thicker than the thickness of the head main body 81. More specifically, the thickness of the bracket 84 is thicker than the thickness of the upper lid portion 812 of the head main body 81. Further, the bracket 84 has a placement portion 841. The placement portion 841 extends in a plate shape parallel to the base plate 511.

[0054] Each of the two hook portions 85 is fixed to the side wall 811 of the head main body 81. The hook portion 85 protrudes in a V shape upward.

[0055] Each of the two first protrusion portions 86 is a member that protrudes columnarly upward along the axial direction from the head main body 81. In the present embodiment, the first protrusion portion 86 is fixed to the bracket 84 and further protrudes upward through a through hole 814 that penetrates the upper lid portion 812 of the head main body 81. Further, the first protrusion portion 86 has a frustum shape whose diameter becomes smaller toward the upper side. In this way, by fixing the first protrusion portion 86 to the bracket 84 that is thicker than the head main body 81, the position and posture of the first protrusion portion 86 can be made more stable.

[0056] The two second protrusions 87 are each a part protruding in the Y direction from the head main body 81. The second protrusion 87 of the present embodiment is formed by a part of the upper cover 812 of the head main body 81 protruding only to one side in the Y direction.

[0057] The adapter substrate 513 is disposed on the upper surface of the mounting portion 841 of the bracket 84 and is fixed to the mounting portion 841, for example, by screwing. A processor and a memory (not shown) are mounted on the adapter substrate 513. The memory stores the serial number of the ejection unit 51 on which the adapter substrate 513 is mounted and information regarding the characteristics of the ejection unit 51. These pieces of information are transmitted to the control unit 29 via the ejection unit side connector 514 and the drive substrate side connector 523, the drive substrate 522, and the external connection connector 524c, which will be described later. Further, the adapter substrate 513 is electrically connected to the piezo elements 831 of the plurality of nozzles 83 via wirings (not shown).

[0058] The ejection unit side connector 514 is electrically connected to the adapter substrate 513. Thereby, the piezo elements 831 of the plurality of nozzles 83 and the ejection unit side connector 514 are electrically connected via the adapter substrate 513. Further, the ejection unit side connector 514 projects further upward through a through hole 815 penetrating the upper cover 812 of the head main body 81.

[0059] The supply-side ink pipe 515 is a pipe that extends in the axial direction on one side in the X direction from the head main body 81. With the drive board unit 52 attached to the ejection unit 51, the supply-side ink pipe 515 extends upward in the axial direction along the narrow surface wall 112 of the side wall 101 of the housing 521 (to be described later) of the drive board unit 52 on the side of the narrow surface wall 112. An ink supply-side connector 517 is connected to the upper end of the supply-side ink pipe 515 in the axial direction. The second supply pipe 92 of the ink supply unit 28 is connected to the ink supply-side connector 517. Also, the lower end of the supply-side ink pipe 515, which is opposite to the upper end in the axial direction, is connected to the first opening 410 of the base plate 511. When the supply pump 282 of the ink supply unit 28 is driven, the ink stored inside the storage tank 281 passes through the first supply pipe 91, the second supply pipe 92, the supply-side ink pipe 515, the first opening 410, and the first communication path 41 and is supplied to the internal tank 82.

[0060] The discharge-side ink pipe 516 is a pipe that extends in the axial direction on the other side in the X direction from the head main body 81. With the drive board unit 52 attached to the ejection unit 51, the discharge-side ink pipe 516 extends upward in the axial direction along the narrow surface wall 112 of the side wall 101 of the housing 521 (to be described later) of the drive board unit 52 on the side of the narrow surface wall 112. An ink discharge-side connector 518 is connected to the upper end of the discharge-side ink pipe 516 in the axial direction. The first reflux pipe 93 of the ink supply unit 28 is connected to the ink discharge-side connector 518. Also, the lower end of the discharge-side ink pipe 516, which is opposite to the upper end in the axial direction, is connected to the second opening 420 of the base plate 511. When the reflux pump 284 of the ink supply unit 28 is driven, the ink (ink that has stayed in the internal tank 82 without being ejected and whose temperature has decreased) stored in the internal tank 82 of each head assembly 50 passes through the second communication path 42, the second opening 420, the discharge-side ink pipe 516, the first reflux pipe 93, and the second reflux pipe 94 and is refluxed to the storage tank 281.

[0061] Note that both the upper end in the axial direction of the supply-side ink pipe 515 and the upper end in the axial direction of the discharge-side ink pipe 516 are located further above the top plate 102 of the housing 521 described later. As a result, an operator can connect the ink supply-side connector 517 fixed to the supply-side ink pipe 515 to the second supply pipe 92 and connect the ink discharge-side connector 518 fixed to the discharge-side ink pipe 516 to the first reflux pipe 93 above the housing 521. As a result, the operator can perform these connection operations without accessing the side of the housing 521 with limited space, improving work efficiency.

[0062] The drive board unit 52 is a device that supplies a drive signal to the ejection unit 51. FIG. 9 is a partial perspective view of the head assembly 50 with a part of its interior exposed, viewed from the other side in the Y direction. As shown in FIGS. 5, 6, and 9, the drive board unit 52 includes a housing 521, a drive board 522, a drive board side connector 523, external connection connectors 524c, 524p, a cooling jacket 525, a supply-side cooling pipe 526, a discharge-side cooling pipe 527, a plurality (four in this embodiment) of legs 528, and a plurality (two in this embodiment) of positioning cylinder portions 529.

[0063] The housing 521 is a hollow member that holds the drive board 522, the drive board side connector 523, the external connection connectors 524c, 524p, the cooling jacket 525, and the positioning cylinder portion 529. The housing 521 includes four side walls 101, a top plate 102, a plurality (two in this embodiment) of engaging portions 103, a plurality (two in this embodiment) of locking members 104, and a plurality (four in this embodiment) of support members 105.

[0064] The four side walls 101 extend in a square tube shape along the axial direction. The square tube formed by the four side walls 101 is slightly larger than the square tube formed by the side wall 811 of the head main body 81. The top plate 102 covers the opening at the upper end of the square tube shape formed by the four side walls 101. Further, a plurality (two in this embodiment) of through holes 200 are provided in the top plate 102. The two through holes 200 each penetrate the top plate 102 in the axial direction. Furthermore, a handle 130 is fixed to the top plate 102. However, the shape of the housing 521 is not limited to this. The housing 521 may have a side wall that extends in a tubular shape along the axial direction and a top plate that covers one end of the side wall on the side away from the base plate 511 in the axial direction.

[0065] In addition, the four side walls 101 include a pair of wide surface walls 111 facing each other and a pair of narrow surface walls 112 facing each other. The pair of wide surface walls 111 and the pair of narrow surface walls 112 are adjacent to each other. Also, the surface area of each narrow surface wall 112 is smaller than that of each wide surface wall 111.

[0066] Engagement portions 103 are respectively fixed to the pair of wide surface walls 111. Each engagement portion 103 has a horizontal engagement bar 113. The position of the engagement bar 113 in the axial direction is variable. By engaging the engagement bar 113 with the hook portion 85 of the discharge unit 51, the housing 521 can be attached to the discharge unit 51. Thereby, the drive substrate unit 52 including the housing 521 is detachable along the axial direction with respect to the discharge unit 51.

[0067] Further, the notch portion 110 is provided only on one of the four side walls 101. In the present embodiment, the notch portion 110 is provided only on the wide surface wall 111 on one side in the Y direction among the pair of wide surface walls 111. The notch portion 110 is a portion notched upward from the lower end of the wide surface wall 111. When the operator attaches the housing 521 to the discharge unit 51, the second protrusion 87 of the discharge unit 51 is fitted into the notch portion 110. Here, if the orientation of the housing 521 with respect to the discharge unit 51 is mistaken and the second protrusion 87 is applied to the side wall 101 without the notch portion 110, the housing 521 cannot be advanced further toward the discharge unit 51, and thus cannot be properly attached. By adopting such a configuration, it is possible to prevent the operator from misorienting the housing 521 with respect to the discharge unit 51 when attaching the drive substrate unit 52 to the discharge unit 51.

[0068] The two locking members 104 are fixed to each of the pair of narrow surface walls 112, one for each. Each of the two locking members 104 has a U-shaped recessed toward the narrow surface wall 112 when viewed in the axial direction. Also, the size of the U shape is substantially equal to the diameter of the supply-side ink pipe 515 and the diameter of the discharge-side ink pipe 516, respectively. As described above, the supply-side ink pipe 515 and the discharge-side ink pipe 516 each extend in the axial direction along the side of the narrow surface wall 112. Therefore, by fitting the supply-side ink pipe 515 and the discharge-side ink pipe 516 into the U shape of the locking member 104, respectively, the intermediate portions of the supply-side ink pipe 515 and the discharge-side ink pipe 516 in their respective axial directions can be detachably locked. This can suppress the bending of the supply-side ink pipe 515 and the discharge-side ink pipe 516 and their entanglement with peripheral members.

[0069] In addition, two support members 105 are further fixed to each of the pair of narrow side walls 112. In the present embodiment, two support members 105 are fixed to each narrow side wall 112 with a gap therebetween in the axial direction. Each support member 105 protrudes plate-like outward in the X direction from the narrow side wall 112. Further, each support member 105 is provided with a support hole 106. The support hole 106 is formed by penetrating the support member 105 in the axial direction. Note that the two support holes 106 provided in the two support members 105 fixed to one narrow side wall 112 are located at the same position as each other when viewed in the axial direction.

[0070] Also, as shown in FIG. 6, a plurality (four in the present embodiment) of through holes 120 are further provided only in the narrow side wall 112 on one side in the X direction among the pair of narrow side walls 112. In the present embodiment, four through holes 120 are provided at intervals in the axial direction from each other only in the narrow side wall 112 to which the supply-side ink pipe 515 is locked among the pair of narrow side walls 112. Each through hole 120 penetrates the narrow side wall 112 in the thickness direction (X direction). A joint 531 (see FIG. 9) is fixed to each through hole 120. The joint 531 forms a connection port for connecting the pipes of a cooling jacket 525 described later. However, the through hole 120 may be provided in the top plate 102 of the housing 521.

[0071] The drive substrate 522 is housed inside the housing 521 and is fixed to the side wall 101 of the housing 521 by, for example, screwing. A drive substrate-side connector 523 is electrically connected to the lower end of the drive substrate 522 via, for example, an FFC (Flexible Flat Cable). Similarly, two external connection connectors 524c and 524p are electrically connected to the upper end of the drive substrate 522 via, for example, an FFC (Flexible Flat Cable). Further, the two external connection connectors 524c and 524p are each exposed to the outside through the through hole 200 in the top plate 102 of the housing 521.

[0072] A power line extending from an external power supply is connected to the external connection connector 524p. Thereby, power for driving the drive substrate 522, the adapter substrate 513 of the ejection unit 51, and the plurality of piezo elements 831 is supplied from the external power supply. A communication cable extending from the control unit 29 is connected to the external connection connector 524c. Thereby, a small dot signal for forming small dots, a medium dot signal for forming medium dots, and a large dot signal for forming large dots are supplied from the control unit 29 to the drive substrate 522 via the external connection connector 524c. The drive substrate 522 generates a drive signal including a drive waveform for driving the plurality of piezo elements 831 from the supplied small dot signal, medium dot signal, and large dot signal.

[0073] When the housing 521 is attached to the ejection unit 51, the drive substrate side connector 523 held by the housing 521 and the ejection unit side connector 514 of the ejection unit 51 are electrically connected. Thereby, power is supplied from the external power supply, and the drive substrate 522, the adapter substrate 513 of the ejection unit 51, and the plurality of piezo elements 831 are driven. Further, the drive substrate side connector 523 outputs the drive signal generated in the drive substrate 522, and the ejection unit side connector 514 receives the drive signal. Furthermore, based on the drive signal, the plurality of piezo elements 831 are controlled. As a result, ink droplets are ejected from the ejection port 830 toward the continuous paper 9, and characters and images are recorded on the surface of the continuous paper 9.

[0074] As shown in FIG. 9, in the present embodiment, at least a part of the drive substrate 522 overlaps the ejection unit side connector 514 in the horizontal direction in a state where the ejection unit 51 and the drive substrate unit 52 are attached to each other. By adopting such a configuration, the head assembly 50 including the ejection unit 51 and the drive substrate unit 52 is miniaturized in the axial direction. For this reason, the drive substrate 522 that generates high-temperature heat is close to the precision elements such as the plurality of piezo elements 831 of the ejection unit 51 and the ink stored in the internal tank 82 of the ejection unit 51.

[0075] Therefore, in the present embodiment, a cooling jacket 525 is attached between the drive substrate 522 and the inner surface of the housing 521 (the back surface of the drive substrate 522). A known water-cooling device in which a cooling medium such as cooling water flows inside a pipe to cool the drive substrate 522 is used for the cooling jacket 525. In the present embodiment, two pipes for circulating the cooling water are arranged in a loop on the back surface of the drive substrate 522. Thereby, it is possible to suppress the high-temperature heat generated in the drive substrate 522 from being transmitted to the discharge unit 51 and the external atmosphere. As a result, deterioration and damage due to heat of precision elements such as a plurality of piezoelectric elements 831 can be suppressed.

[0076] On the other hand, the cooling jacket 525 itself is arranged at an axial distance from the discharge unit 51. Thereby, even if the cooling medium circulates inside the pipe of the cooling jacket 525, it is possible to suppress a decrease in the temperature of the ink stored in the internal tank 82. The drive of the cooling jacket 525 is controlled by an external device (not shown). However, the drive of the cooling jacket 525 may be controlled by the control unit 29.

[0077] Both ends of each of the two pipes of the cooling jacket 525 are connected to connection ports of four joints 531 fixed to the narrow surface wall 112 of the housing 521. In addition, the lower ends of two supply-side cooling pipes 526 extending from an external device are respectively connected to the connection ports of two of the four joints 531. The supply-side cooling pipe 526 is a pipe that allows the cooling medium supplied to the cooling jacket 525 to pass through. The lower ends of two discharge-side cooling pipes 527 extending from an external device are connected to the connection ports of the remaining two of the four joints 531. The discharge-side cooling pipe 527 is a pipe that allows the cooling medium discharged from the cooling jacket 525 to pass through. The two supply-side cooling pipes 526 and the two discharge-side cooling pipes 527 each extend upward along the narrow surface wall 112. When the cooling jacket 525 is driven, the cooling medium supplied from an external device passes through the supply-side cooling pipe 526, circulates through the pipe of the cooling jacket 525, and is discharged through the discharge-side cooling pipe 527.

[0078] In addition, the four joints 531 and their connection ports are located near the top plate 102 of the housing 521. In the present embodiment, among the four joints 531 and their connection ports, three joints 531 and their connection ports are located above the axial center of the housing 521. That is, the four joints 531 and the connection ports are arranged axially spaced apart from the discharge unit 51. Thereby, the decrease in the temperature of the ink stored in the internal tank 82 can be further suppressed. In addition, the workability when connecting the supply-side cooling pipe 526 and the discharge-side cooling pipe 527 to the connection ports of the four joints 531 is further improved. However, at least a part of the joint 531 and the connection port may be located above the axial center of the housing 521.

[0079] Also, with the drive substrate unit 52 mounted on the discharge unit 51, the four joints 531 and connection ports to which the ends of the supply-side cooling pipe 526 and the discharge-side cooling pipe 527 are connected are separated from the first opening 410 to which the supply-side ink pipe 515 is connected and the second opening 420 to which the discharge-side ink pipe 516 is connected in the axial direction. Thereby, it is possible to suppress the temperatures of the supply-side cooling pipe 526 and the discharge-side cooling pipe 527 and the temperatures of the supply-side ink pipe 515 and the discharge-side ink pipe 516 from affecting each other. As a result, precise temperature control of the drive substrate 522 and the ink stored in the internal tank 82 becomes possible. Also, as described above, the first opening 410 and the second opening 420 are each located at the same position as the base plate 511 in the axial direction. Thereby, ink can be supplied to the discharge unit 51 from a position away from the drive substrate 522. As a result, it is possible to suppress the heat generated by the drive substrate 522 from being transmitted to the ink supplied to the discharge unit 51.

[0080] As shown in FIGS. 5 and 6, legs 528 are fixed, for example, by screwing, to the outer surfaces of the respective four side walls 101 that expand in a square tube shape. The four legs 528 each extend in the axial direction. Also, the lower ends of the four legs 528 are at positions equal in the axial direction to each other.

[0081] When attaching the housing 521 to the discharge unit 51, the operator first moves the drive substrate unit 52 toward the base plate 511 while gripping the handle 130 of the housing 521 so that the head main body 81 is covered by the four side walls 101. When the drive substrate unit 52 is moved a predetermined distance toward the base plate 511, the lower ends of the four legs 528 come into contact with the base plate 511. Thereby, the drive substrate unit 52 can be positioned in the axial direction with respect to the discharge unit 51. That is, in the present embodiment, the contact between the base plate 511 and the legs 528 constitutes a "first positioning portion" for positioning the drive substrate unit 52 in the axial direction with respect to the discharge unit 51.

[0082] At the same time, by covering the head main body 81 with the four side walls 101 (more specifically, covering the four corners of the head main body 81 with the inner surfaces of the four legs 528), the inner surfaces of the four side walls 101 come into contact with the corner portions 811a of the head main body 81. Thereby, the drive substrate unit 52 can be positioned in the horizontal direction parallel to the base plate 511 with respect to the discharge unit 51. That is, in the present embodiment, the contact between the inner surfaces of the four side walls 101 and the corner portions 811a of the head main body 81 simultaneously constitutes a "first positioning portion" for positioning the drive substrate unit 52 in the horizontal direction parallel to the base plate 511 with respect to the discharge unit 51.

[0083] As shown in FIG. 9, between the drive substrate 522 and the inner surface of the housing 521 (the back surface of the drive substrate 522), two bottomed cylindrical positioning cylinder portions 529 are further arranged. The two positioning cylinder portions 529 are respectively fixed to the back surface of the drive substrate 522, for example, by screwing. Each of the two positioning cylinder portions 529 has a recess 540. The recess 540 is recessed in the axial direction from the lower end surface of the positioning cylinder portion 529 upward. The recess 540 has substantially the same shape as the first protrusion 86 of the discharge unit 51. That is, the recess 540 has a frustum shape that becomes narrower toward the upper side. Note that the recess 540 is slightly larger than the first protrusion 86.

[0084] When attaching the housing 521 to the discharge unit 51, after an operator covers the head main body 81 with the four side walls 101 as described above, when the four side walls 101 are slid along the corner portions 811a of the head main body 81, the upper tips of the first protrusions 86 fit into the recesses 540 of the positioning cylinder portion 529. At this time, since the tips of the first protrusions 86 have a small diameter, they easily fit into the recesses 540. Then, when the operator further brings the drive substrate unit 52 closer to the base plate 511, the first protrusions 86 fit to the depths of the recesses 540. Here, as described above, the recesses 540 have substantially the same shape as the first protrusions 86 and are slightly larger than the first protrusions 86. For this reason, the first protrusions 86 fit into the depths of the recesses 540 without a gap, and substantially the entire first protrusions 86 come into contact with the recesses 540. As a result, the drive substrate unit 52 can be precisely positioned in a horizontal direction parallel to the base plate 511 with respect to the discharge unit 51. That is, in the present embodiment, by fitting the first protrusions 86 into the recesses 540, a "second positioning portion" is configured to position the drive substrate unit 52 with respect to the discharge unit 51 in a horizontal direction parallel to the base plate 511 and more precisely than the "first positioning portion".

[0085] However, the configuration of the "second positioning portion" is not limited to this. The "second positioning portion" may be configured, for example, by a protrusion protruding downward provided on the drive substrate unit 52 fitting into a recess recessed downward provided on the discharge unit 51.

[0086] As described above, when attaching the housing 521 to the discharge unit 51, the operator first moves the legs 528 of the drive board unit 52 toward the base plate 511 of the discharge unit 51 while bringing the inner surfaces of the four side walls 101 of the drive board unit 52 into contact with the head main body 81 of the discharge unit 51 at the "first positioning part". In the process of the operator moving the drive board unit 52 toward the base plate 511, at the "second positioning part", the first protrusion 86 of the discharge unit 51 fits into the recess 540 of the drive board unit 52 until the entire first protrusion 86 contacts the recess 540. When the inner surfaces of the four side walls 101 of the drive board unit 52 are brought into contact with the head main body 81 of the discharge unit 51, the head main body 81 and the base plate 511 of the discharge unit 51 that constitute the "first positioning part", and the four side walls 101 and the legs 528 of the drive board unit 52 are visible from the outside. As a result, the operator can position the drive board unit 52 with respect to the discharge unit 51 while visually observing the "first positioning part" from the outside, and then more precisely position the drive board unit 52 with respect to the discharge unit 51 by the "second positioning part". As a result, the drive board unit 52 can be easily and more accurately positioned with respect to the discharge unit 51.

[0087] Note that when the first protrusion 86 fits into the recess 540 at the "second positioning part", the drive board side connector 523 held by the housing 521 and the discharge part side connector 514 of the discharge unit 51 are automatically and electrically connected. By having such a configuration, the discharge part side connector 514 and the drive board side connector 523 can be accurately connected without displacement or the like. As a result, the drive signal generated in the drive board 522 can be output to the discharge unit 51, and by controlling a plurality of piezo elements 831 according to the drive signal, ink can be discharged from the discharge port 830.

[0088] The head mounting unit 60 is a unit that is constantly fixed to the frame of the printing apparatus 1. Five head assemblies 50 are installed in the head mounting unit 60. The head mounting unit 60 has a head mounting plate 601 and five through holes 602. The head mounting plate 601 is a plate-shaped member that is long and strip-shaped and extends in the XY plane. Each of the five through holes 602 penetrates the head mounting plate 601 in the axial direction. As will be described later, the ejection unit unit 51 and the drive substrate unit 52 are installed in the axial direction on the surface 601f of the head mounting plate 601 in a state where they are attached to each other. When the ejection unit unit 51 and the drive substrate unit 52 are installed on the surface 601f of the head mounting plate 601 and the inkjet head 351 is viewed in the axial direction, each through hole 602 surrounds a plurality of nozzles 83 and is smaller than the base plate 511. For this reason, the ejection ports 830 of the plurality of nozzles 83 are exposed to the back surface 601b side of the head mounting plate 601 through the through holes 602. As a result, ink can be ejected from the ejection unit unit 51 to the continuous paper 9 conveyed downward through the through holes 602 of the head mounting plate 601.

[0089] The head mounting plate 601 is further provided with ten mounting holes 603. In the present embodiment, they are formed on the outside of both ends in the X direction of each of the five through holes 602, that is, two on each side of each through hole 602. In the present embodiment, the mounting holes 603 are screw holes formed from the surface 601f of the head mounting plate 601 toward the back surface 601b side. Female threads are formed in the mounting holes 603.

[0090] The connecting member 70 is a rod-shaped member used to connect the discharge unit 51, the drive substrate unit 52, and the head attachment unit 60 to each other. Fig. 10 is a perspective view of one connecting member 70. With the discharge unit 51 and the drive substrate unit 52 installed on the surface 601f of the head attachment plate 601, the connecting member 70 extends in the axial direction on the side of the narrow surface wall 112 of the housing 521. Hereinafter, the lower end of the connecting member 70 will be referred to as the first end 701, and the upper end of the connecting member 70 will be referred to as the second end 702. As shown in Fig. 10, the connecting member 70 has a small-diameter portion 703, a large-diameter portion 704, and a polygonal columnar portion 705.

[0091] The small-diameter portion 703 is located at the first end 701 of the connecting member 70 and is a small-diameter portion extending in a columnar shape in the axial direction. A male thread is formed on the small-diameter portion 703. Also, the diameter of the small-diameter portion 703 is smaller than the diameters of the two positioning grooves 431, 432 of the base plate 511. The large-diameter portion 704 is located on the second end 702 side of the small-diameter portion 703, extends in a columnar shape in the axial direction, and is a portion having a larger diameter than the small-diameter portion 703. The diameter of the large-diameter portion 704 is larger than the diameters of the two positioning grooves 431, 432 of the base plate 511. The polygonal columnar portion 705 is a portion located at the second end 702 of the connecting member 70. The polygonal columnar portion 705 of the present embodiment extends in a quadrangular columnar shape in the axial direction. However, the shape of the polygonal columnar portion 705 is not limited to this. The polygonal columnar portion 705 only needs to extend in a polygonal columnar shape in the axial direction.

[0092] A commercially available torque wrench 800 illustrated in Fig. 11 can be fitted to the second end 702 of the connecting member 70. The shape of the square drive 801 of the torque wrench 800 is the same as the shape of the polygonal columnar portion 705 (in this embodiment, a quadrangular columnar shape) and is used.

[0093] When attaching the ejection unit 51 and the drive board unit 52 to the head mounting plate 601, the operator first attaches the ejection unit 51 and the drive board unit 52 to each other to form the head assembly 50, and then installs the head assembly 50 on the surface 601f of the head mounting plate 601 in the axial direction so as to cover the through hole 602. Next, using two connecting members 70, pass their small diameter portions 703 through two positioning grooves 431, 432 of the base plate 511 and thread them into two mounting holes 603 respectively. At this time, the large diameter portion 704 of the connecting member 70 does not penetrate the positioning grooves 431, 432 of the base plate 511. Therefore, the end face 707 adjacent to the small diameter portion 703 in the large diameter portion 704 contacts the exposed portions 401, 402 of the base plate 511 and presses the exposed portions 401, 402 downward.

[0094] As a result, the two connecting members 70 are fixed to the two mounting holes 603 while positioning the base plate 511 in the positioning grooves 431, 432. As a result, the end faces 707 (lower surfaces of the large diameter portions 704) of the two connecting members 70 can fix the ejection unit 51 including the base plate 511 and the drive board unit 52 mounted on the ejection unit 51 to the head mounting plate 601. Note that, among the head assembly 50, the parts where the connecting members 70 contact and press are limited to the parts near the positioning grooves 431, 432 of the base plate 511. Therefore, it is possible to suppress the occurrence of distortion in members such as other housings 521 in the head assembly 50.

[0095] Also, in the present embodiment, with the ejection unit 51 and the drive board unit 52 fixed to the head mounting plate 601, the supply side ink pipe 515 and the discharge side ink pipe 516 extend in the axial direction at a position closer to the narrow surface wall 112 than the connecting member 70. That is, the connecting member 70 is located farther from the housing 521 than the supply side ink pipe 515 and the discharge side ink pipe 516. Therefore, it is possible to further suppress the occurrence of distortion in the housing 521 and the like due to the pressing by the connecting member 70.

[0096] Note that two groove portions 706 are provided in the connecting member 70. The two groove portions 706 are recessed inward over the entire circumference in a part of the connecting member 70 in the axial direction. Also, in the present embodiment, the two groove portions 706 are provided in the large-diameter portion 704 of the connecting member 70 with a gap therebetween in the axial direction. For example, a resin ring is fitted into each groove portion 706. As a result, two flange portions 750 that protrude in a ring shape over the entire circumference are formed in the large-diameter portion 704 of the connecting member 70.

[0097] Here, the diameter of the portion of the large-diameter portion 704 excluding the flange portion 750 is smaller than the diameter of each support hole 106 provided in the two support members 105 arranged in the axial direction in the housing 521. Therefore, the portion of the connecting member 70 excluding the flange portion 750 can freely move in the axial direction through the two support holes 106. However, the diameter of the flange portion 750 is larger than the diameter of the support hole 106. Therefore, the flange portion 750 cannot pass through the support hole 106 and contacts the support member 105. In the present embodiment, while passing the portion of the connecting member 70 excluding the flange portion 750 through the two support holes 106 arranged in the axial direction, the flange portion 750 is positioned between the two support members 105 in the axial direction. As a result, the support member 105 can hold the connecting member 70 while suppressing the connecting member 70 from falling. As a result, the workability when attaching the head assembly 50 to the head mounting plate 601 is further improved.

[0098] As shown in FIG. 4, in this embodiment, in one inkjet head 351, five head assemblies 50 are arranged in a zigzag (alternate) pattern on the head mounting plate 601. The five head assemblies 50 are fixed to the surface 601f of the head mounting plate 601 via connecting members 70, respectively, with their side walls 101 being close to each other. Also, in the state where the five head assemblies 50 are fixed to the head mounting plate 601, the gap between the narrow side walls 112 of the head assemblies 50 that are close to each other is larger than the gap between the wide side walls 111 of the head assemblies 50 that are close to each other. As described above, when attaching the head assembly 50 to the head mounting plate 601, the thin-diameter portions 703 of the two connecting members 70 held on the side of the narrow side wall 112 of the housing 521 are passed through the two positioning grooves 431, 432 of the base plate 511 and screwed into the two mounting holes 603, respectively. That is, in this embodiment, since the work can be performed on the side of the relatively spacious narrow side wall 112, the workability is further improved.

[0099] Also, among the connecting members 70, the second end 702 on the side opposite to the first end 701 fixed to the mounting hole 603 of the head mounting plate 601 protrudes above the discharge unit unit 51 and the drive substrate unit 52 in the axial direction (see FIG. 5). For this reason, a torque wrench 800 can be more easily fitted to the second end 702 of the connecting member 70. As a result, the workability when attaching the head assembly 50 to the head mounting plate 601 is further improved.

[0100] Note that in this embodiment, the supply-side ink pipe 515, the discharge-side ink pipe 516, the supply-side cooling pipe 526, and the discharge-side cooling pipe 527 also extend in the axial direction along the side of the narrow side wall 112 of the housing 521, respectively. For this reason, the replacement of each of these pipes can also be performed on the side of the relatively spacious narrow side wall 112, so the workability is further improved.

[0101] In this embodiment, since the inkjet head 351 has the above configuration, it is possible to easily replace each part including the ejection unit 51 that is relatively quickly consumed. Further, when the ejection unit 51 and the drive substrate unit 52 are mounted on each other again, the ejection unit side connector 514 and the drive substrate side connector 523 can be accurately connected without misalignment or the like. As a result, the drive signal generated on the drive substrate 522 can be output to the ejection unit 51, and by controlling a plurality of piezo elements 831 according to the drive signal, ink can be ejected again from the ejection port 830.

[0102] <2. Modification Example> As described above, one embodiment of the present invention has been described, but the present invention is not limited to the above embodiment.

[0103] In the above embodiment, the ink supply unit 28 was configured to supply the temperature-adjusted ink to the inkjet head 351 while circulating the ink with the inkjet head 351. However, the ink supply unit 28 may supply the ink to the inkjet head 351 in one direction.

[0104] Also, in the above embodiment, the ejection unit 512 had one internal tank 82. However, the ejection unit 512 may have a plurality of internal tanks 82. For example, although not shown, the ejection unit 512 may have a first internal tank 82a (internal tank 82a on the ink supply side) communicating with the first communication passage 41 (see FIG. 8) and a second internal tank 82b (internal tank 82b on the ink discharge side) communicating with the second communication passage 42 (see FIG. 8). And the first internal tank 82a and the second internal tank 82b only need to communicate with the ink chamber 832 and the ejection port 830 (see FIG. 2), respectively, and the ink is supplied from the first communication passage 41 to the ink chamber 832 via the first internal tank 82a, and the ink is discharged from the ink chamber 832 to the second communication passage 42 via the second internal tank 82b.

[0105] Also, the respective elements that appeared in the above embodiments and modifications may be appropriately combined within a range where no contradiction occurs.

Explanation of Reference Numerals

[0106] 1 Printing device 9 Continuous paper 28 Ink supply unit 29 Control unit 40 Base through-hole 41 First communication path 42 Second communication path 50 Head assembly 51 Discharge unit 52 Drive substrate unit 60 Head mounting unit 70 Connecting member 81 Head main body 82 Internal tank 83 Nozzle 84 Bracket 86 First protrusion 87 Second protrusion 101 Side wall 102 Top plate 104 Locking member 105 Support member 106 Support hole 110 Notch 111 Wide surface wall 112 Narrow surface wall 351 Inkjet head 401 Exposed part 402 Exposed part 410 First opening 420 Second opening 431 Positioning groove 432 Positioning groove 511 Base plate 512 Discharge part 514 Discharge-side connector 515 Supply-side ink pipe 516 Discharge-side ink pipe 521 Housing 522 Drive substrate 523 Drive-substrate-side connector 525 Cooling jacket 528 Leg 540 Recess 601 Head mounting plate 603 Mounting hole 701 First end 702 Second end 703 Small diameter part 704 Large diameter part 705 Polygonal columnar part 707 End face 750 Flange part 800 Torque wrench 830 Outlet 831 Piezoelectric element

Claims

1. An inkjet head that ejects ink onto a printing medium for printing, comprising: a discharge unit that discharges the ink in response to a drive signal; a drive substrate unit that supplies the drive signal to the discharge unit; and having the discharge unit a base plate; a discharge part disposed on the base plate and discharging the ink from a discharge port; a discharge part side connector that receives the drive signal; and having the drive substrate unit a drive substrate that generates the drive signal; a drive substrate side connector that outputs the drive signal; a housing that holds the drive substrate and the drive substrate side connector; and having the drive substrate unit is detachable along an axial direction orthogonal to the base plate with respect to the discharge unit, and in a state where the housing is attached to the discharge unit, the drive substrate side connector and the discharge part side connector are connected, and an exposed part is formed where a part of the base plate is exposed; the discharge part an internal tank that temporarily stores the ink discharged from the discharge port and having the discharge unit a supply side ink pipe that allows the ink supplied to the internal tank to pass through; a first opening formed in the exposed part and communicating with the internal tank; and further having the housing a side wall that expands in a cylindrical shape along the axial direction; a top plate that covers one end of the side wall on the side away from the base plate in the axial direction; and having The supply side ink pipe is connected to the first opening at an end on the other side opposite to the one side in the axial direction, extends to the one side along the side wall, and the end on the one side in the axial direction is located on the one side of the top plate, an inkjet head.

2. The inkjet head according to claim 1, wherein the drive substrate unit further has a locking member that is fixed to the side wall of the housing and detachably locks an intermediate portion of the supply side ink pipe in the axial direction an inkjet head.

3. The inkjet head according to claim 1 or claim 2, wherein the discharge unit a discharge side ink pipe that allows the ink discharged from the internal tank to pass through; a second opening formed in the exposed part and communicating with the internal tank; and further having The discharge-side ink pipe is connected to the second opening at the other end in the axial direction and extends along the side wall to the one side, for an inkjet head.

4. An inkjet head according to claim 3, wherein the internal tank includes a first internal tank on the ink supply side and a second internal tank on the ink discharge side, the first internal tank communicates with the discharge port and the first opening, respectively, and the second internal tank communicates with the discharge port and the second opening, respectively, for an inkjet head.

5. An inkjet head according to claim 3 or claim 4, wherein the drive substrate unit includes a cooling jacket disposed between the drive substrate and the inner surface of the housing and configured to cool the drive substrate by allowing a cooling medium to flow through the inside thereof, a supply-side cooling pipe configured to allow the cooling medium supplied to the cooling jacket to pass therethrough, and a connection port formed in the side wall and connected to the cooling jacket, and further includes the supply-side cooling pipe is connected to the connection port at the other end and extends along the side wall to the one side, and in a state where the discharge unit unit and the drive substrate unit are attached to each other, the connection port, the first opening, and the second opening are spaced apart from each other in the axial direction, for an inkjet head.

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