Inkjet head

Abstract

To provide a technique that can efficiently suppress high-temperature heat generated in a driving substrate from being transmitted to an ejection part unit, while downsizing the whole of an inkjet head including a driving substrate unit having a driving substrate and the ejection part unit.SOLUTION: An inkjet head comprises an ejection part unit that ejects ink in response to a driving signal and a driving substrate unit that outputs the driving signal. The driving substrate unit has: a driving substrate 522 that generates a driving signal; a housing that retains the driving substrate; a cooling jacket 525, arranged between the driving substrate 522 and an inside surface of the housing, through which a cooling medium flows to cool the driving substrate 522; and a connection port, formed in a side wall or a top plate of the housing, which the cooling jacket 525 is connected to. At least a portion of the connection port is positioned at one side farther away from the ejection part unit, in an axial direction, than the driving substrate 522.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to an inkjet head that performs printing by ejecting ink onto a print medium. [Background technology]

[0002] Inkjet printing devices are known that print characters and images by ejecting ink from ejection ports onto a print medium transported in a predetermined direction. Such printing devices are equipped with an ejection unit that ejects ink and a drive board that generates a drive signal for driving the ejection unit. For example, Patent Document 1 discloses a recording device (1) that has an ejection unit housing (20) that houses a recording head (7) capable of ejecting ink, and a drive board housing (19) that houses a drive board (40) that drives the recording head (7). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-081049 Summary of the Invention [Problem to be solved by the invention]

[0004] When a printing device is in operation, high-temperature heat is generated from the drive board. Therefore, in the recording device (1) of Patent Document 1, the drive board (40) and the recording head (7) are separated by a large distance to prevent the heat generated by the drive board (40) from affecting the recording head (7). The recording device (1) is also configured to release the heat generated by the drive board (40) to the outside via the housing (22) of the drive board housing portion (19), the housing (45) of the ejection portion housing portion (20), and the heat transfer plate (21). However, in this case, it is difficult to reduce the overall size of the recording device (1) including the drive board (40) and the recording head (7), and there is a risk that the installation space cannot be secured. Furthermore, because it is an air-cooled system, there is still a risk that heat will be trapped in the surrounding atmosphere and affect the recording head (7).

[0005] The present invention has been developed in consideration of these circumstances, and aims to provide a technology that efficiently suppresses the transmission of high-temperature heat generated on the drive substrate to the ejection unit, while realizing miniaturization of a head assembly having a unit including an ejection unit and a unit including a drive substrate. [Means for solving the problem]

[0006] In order to solve the above problems, a first invention of the present application is an inkjet head that prints by ejecting ink onto a printing medium, the inkjet head having an ejection section unit that ejects the ink in response to a drive signal, and a drive substrate unit that supplies the drive signal to the ejection section unit, the ejection section unit having a base plate, an ejection section that is disposed on the base plate and ejects the ink from an ejection port, and an ejection section side connector that receives the drive signal, the drive substrate unit having a drive substrate that generates the drive signal, a drive substrate side connector that outputs the drive signal, and a housing that holds the drive substrate and the drive substrate side connector, the drive substrate unit being axially connected to the ejection section unit in an axial direction that is perpendicular to the base plate. the housing is detachably attached to the discharge section unit by connecting the drive board side connector and the discharge section side connector, and at least a portion of the drive board overlaps the discharge section side connector in the horizontal direction; the housing has a side wall that expands cylindrically along the axial direction, and a top plate that covers one end of the side wall in the axial direction that is remote from the base plate; the drive board unit further has a cooling jacket that is disposed between the drive board and the inner surface of the housing and that cools the drive board by allowing a cooling medium to flow therethrough; and a connection port that is formed on the side wall or the top plate and to which the cooling jacket is connected, and at least a portion of the connection port is located in the vicinity of the top plate.

[0007] The second invention of the present application is an inkjet head according to the first invention, wherein the ejection unit has an opening for supplying the ink to the ejection unit, and the opening is located at the same position as the base plate in the axial direction. [Effects of the Invention]

[0008] According to the first and second inventions of the present application, by arranging the drive substrate unit including the drive substrate and the ejection unit close to each other, the overall inkjet head can be made smaller, while by arranging the cooling jacket close to the drive substrate, it is possible to prevent the high temperature heat generated in the drive substrate from being transmitted to the ejection unit or the external atmosphere. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram conceptually illustrating the configuration of a printing device. [Figure 2] FIG. 2 is a diagram conceptually illustrating the configuration of an ink supply unit and an inkjet head. [Figure 3] FIG. 2 is a block diagram showing connections between a control unit and each unit of the printing device. [Figure 4] FIG. 2 is a perspective view of an inkjet head. [Figure 5] FIG. 2 is a perspective view of a head assembly and a connecting member. [Figure 6] FIG. 2 is an exploded perspective view of a head assembly and a connecting member. [Figure 7] FIG. 2 is a vertical cross-sectional view of the discharge unit. [Figure 8] FIG. [Figure 9] FIG. 2 is a partial perspective view of a head assembly with a part of the interior exposed. [Figure 10] FIG. [Figure 11] FIG. 1 is a perspective view of a torque wrench. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the components described in these embodiments are merely examples and are not intended to limit the scope of the present invention. Furthermore, in the drawings, the dimensions and numbers of each part may be exaggerated or simplified as necessary to facilitate understanding.

[0011] 1. First Embodiment <1-1. Printer Configuration> FIG. 1 is a conceptual diagram illustrating the configuration of a printing device 1 according to one embodiment of the present invention. However, FIG. 1 does not illustrate an ink supply unit 28, which will be described later. This printing device 1 is an inkjet continuous feed printing machine that records characters and images on the surface of a long strip of continuous paper 9 by ejecting ink droplets from multiple inkjet heads 351 toward the continuous paper 9 while transporting the continuous paper 9. The long strip of continuous paper 9 is an example of a printing medium. The printing medium may be a plastic film or the like. The printing medium may also be a substrate made of cardboard, metal foil, or glass.

[0012] The printing device 1 has a paper feed section 21, a front side printing unit 23, a reversing unit 25, a rear side printing unit 27, a plurality of (eight in this embodiment) ink supply sections 28, and a control section 29.

[0013] The paper feed unit 21 supplies the continuous paper 9 to the front printing unit 23. The paper feed unit 21 holds the rolled continuous paper 9 so that it can rotate around a horizontal axis. The paper feed unit 21 rotates the rolled continuous paper 9 to send the continuous paper 9 to the front printing unit 23.

[0014] The front side printing unit 23 is a device that prints on one of the two main sides (largest sides) of the continuous paper 9 while transporting the continuous paper 9 in the transport direction indicated by the dashed arrow in Figure 1. The front side printing unit 23 includes a drive unit 31, multiple transport rollers 33, a printing unit 35, and a drying unit 37. Hereinafter, the downstream side in the transport direction will be simply referred to as the "downstream side." Note that the number and arrangement of the transport rollers 33 in Figure 1 are merely an example. That is, although Figure 1 illustrates two transport rollers 33 for each of the printing units 23 and 27, the number of transport rollers 33 may be more or less than this.

[0015] The drive unit 31 takes the continuous paper 9 from the paper feed unit 21 into the front side printing unit 23. The drive unit 31 is composed of, for example, multiple rollers. The multiple transport rollers 33 are located downstream of the drive unit 31. The continuous paper 9 is transported in the transport direction by the drive unit 31 while being supported by the multiple transport rollers 33.

[0016] The printing unit 35 is located downstream of the driving unit 31. The printing unit 35 has a plurality of inkjet heads 351 (four in this embodiment). 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 ink of different colors (for example, cyan, magenta, yellow, and black). The detailed structure of the inkjet heads 351 will be described later.

[0017] The drying unit 37 is located downstream 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 increases the temperature of the continuous paper 9 or the area around 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. The drying unit 37 may also include, for example, a heat roller. The temperature of the continuous paper 9 may be increased by bringing the heat roller into contact with the continuous paper 9.

[0018] The reversing unit 25 reverses the continuous paper 9 sent out from the front-side printing unit 23. The continuous paper 9 reversed by the reversing unit 25 is then sent to the back-side printing unit 27.

[0019] The reverse printing unit 27 prints on the other main surface of the continuous paper 9 that has been inverted by the inversion unit 25. The reverse printing unit 27 has a similar configuration to the front printing unit 23, so a duplicated description will be omitted. After passing through the reverse printing unit 27, the continuous paper 9 is transported further downstream and wound up, for example, into a roll around a horizontal axis and collected in a collection section (not shown).

[0020] Next, the ink supply unit 28 will be described. The ink supply unit 28 circulates ink between the inkjet head 351 and the inkjet head 351, and supplies temperature-controlled ink to the inkjet head 351. The printing device 1 of this embodiment has a total of eight ink supply units 28: four ink supply units 28 corresponding to the four inkjet heads 351 of the front side printing unit 23, and four ink supply units 28 corresponding to the four inkjet heads 351 of the back side printing unit 27. Since the eight ink supply units 28 have the same structure, the following describes the structure of only one ink supply unit 28.

[0021] FIG. 2 is a conceptual diagram showing the configuration of one ink supply unit 28 and one inkjet head 351. Each inkjet head 351 has multiple (five in this embodiment) head assemblies 50. The five head assemblies 50 have the same structure. For this reason, FIG. 2 shows four of the five head assemblies 50 in a 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, multiple (five in this embodiment) second supply pipes 92, multiple (five in this embodiment) first reflux pipes 93, and a second reflux pipe 94.

[0022] The storage tank 281 is a container that stores 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 five second supply pipes 92 are pipes that connect the storage tank 281 to each head assembly 50. In other words, 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 connected and communicated with the interior of the storage tank 281 near the bottom end of the storage tank 281. The other end of the first supply pipe 91 is connected and communicated with one end of each of the five second supply pipes 92.

[0023] A first on-off valve 286, a supply pump 282, and a filter 290 are inserted in the first supply pipe 91. The first on-off valve 286 is disposed between the storage tank 281 and the supply pump 282. The filter 290 is disposed between the supply pump 282 and the other end of the first supply pipe 91. However, the location where the filter 290 is disposed is not limited to this.

[0024] The supply pump 282 is a liquid delivery unit that delivers ink from the storage tank 281 to each head assembly 50. The supply pump 282 generates a flow of ink inside the first supply pipe 91 that flows from the storage tank 281 to each head assembly 50 in accordance with an operation signal from the control unit 29. As a result, ink that has been stored inside the storage tank 281 and whose temperature has been adjusted is supplied to each head assembly 50 via the first supply pipe 91 and the second supply pipe 92.

[0025] When the first on-off valve 286 is in a closed state, communication with the first supply pipe 91 is blocked. In other words, when the first on-off valve 286 is in a closed state, 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 an open state, communication with the first supply pipe 91 is ensured. When the printing device 1 is operating, the first on-off valve 286 is normally in an open state.

[0026] The filter 290 removes solid components and foreign matter from the ink passing through the first supply pipe 91. This prevents solid components and foreign matter from mixing into the ink supplied to each head assembly 50.

[0027] The other end of each of the five second supply pipes 92 is connected in communication with one end of a later-described supply-side ink pipe 515 of the head assembly 50. The other end of the supply-side ink pipe 515 is connected in communication with the internal tank 82 of the head assembly 50, and is connected in communication with a first opening 410 for supplying ink to the nozzles 83 via the internal tank 82. As a result, 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.

[0028] 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 of ink stored in the internal tank 82. The control unit 29 detects the liquid level of ink in the internal tank 82 based on a signal from the liquid level sensor and determines whether or not 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.

[0029] The five first return pipes 93 and the second return pipes 94 are pipes that connect each head assembly 50 to the storage tank 281. One end of each of the five first return pipes 93 is connected in communication with one end of a discharge-side ink pipe 516 (described later) of the head assembly 50. The other end of the discharge-side ink pipe 516 is connected in communication with a second opening 420 that communicates with the internal tank 82 of the head assembly 50. In addition, the other end of each of the five first return pipes 93 is connected in communication with one end of a second return pipe 94. The other end of the second return pipe 94 is connected in communication with the interior of the storage tank 281.

[0030] A second on-off valve 287 is inserted in each first return pipe 93. When the second on-off valve 287 is closed, communication between the first return pipe 93 in which the second on-off valve 287 is inserted is blocked. That is, when the second on-off valve 287 is closed, communication between the internal tank 82 of the corresponding head assembly 50 and the second return pipe 94 is blocked. On the other hand, when the second on-off valve 287 is open, communication between the first return pipe 93 in which the second on-off valve 287 is inserted is ensured. That is, when the second on-off valve 287 is open, communication between the internal tank 82 of the corresponding head assembly 50 and the second return pipe 94 is ensured.

[0031] A reflux pump 284 and a third on-off valve 288 are inserted in the second reflux pipe 94. The reflux pump 284 is a liquid delivery device that delivers ink from the internal tank 82 of each head assembly 50 to the storage tank 281. In response to an operation signal from the control unit 29, the reflux pump 284 generates an ink flow inside the second reflux pipe 94 from each first reflux pipe 93 toward the storage tank 281. As a result, ink stored in the internal tank 82 of each head assembly 50 (ink that has not been ejected but has accumulated in the internal tank 82 and has decreased in temperature) is returned to the storage tank 281 via the second opening 420, the discharge-side ink pipe 516, the first reflux pipe 93, and the second reflux pipe 94. This makes it possible to maintain the temperature, viscosity, and other properties of the ink stored in the internal tank 82 of the head assembly 50 within an appropriate range. As a result, deterioration of the ink ejected from each head assembly 50 is suppressed, thereby improving printing quality.

[0032] 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 a closed state, communication with the second reflux pipe 94 is blocked. That is, when the third on-off valve 288 is in a closed state, communication between each of the first reflux pipes 93 and the storage tank 281 is blocked. On the other hand, when the third on-off valve 288 is in an open state, communication with the second reflux pipe 94 is ensured. The third on-off valve 288 is opened when the reflux pump 284 is operated to return ink from each head assembly 50 to the storage tank 281.

[0033] In this embodiment, as described above, the second on-off valves 287 are provided in each first return pipe 93, so that it is possible to return ink to each individual head assembly 50. For example, when returning ink from some of the head assemblies 50 to the storage tank 281, the second on-off valves 287 and the third on-off valves 288 corresponding to the target head assembly 50 are opened, and the other second on-off valves 287 are closed, and the return pump 284 is operated.

[0034] Next, the control unit 29 will be described. The control unit 29 is an information processing device for controlling the printing device 1. FIG. 3 is a block diagram showing the connection between the control unit 29 and each unit of the printing device 1. As conceptually shown in FIG. 3, the control unit 29 has a processor 291 such as a CPU, a memory 292 such as RAM, and a storage unit 293 such as a hard disk drive. The storage unit 293 stores a computer program 29P for executing a printing process while transporting the continuous paper 9 and for supplying ink to the inkjet head 351.

[0035] 3, the control unit 29 is communicatively connected to the paper feed unit 21, the drive unit 31 of the front side printing unit 23, the four inkjet heads 351 of the printing unit 35, the drying unit 37, the reversing unit 25, the drive unit 31 of the back side printing unit 27, the four inkjet heads 351 of the printing unit 35, the drying unit 37, the recovery unit, and the eight ink supply units 28. The control unit 29 controls the operation of each of these units in accordance with a computer program 29P. As a result, the transport and printing process of the continuous paper 9 progresses, and ink circulates between the storage tank 281 and the inkjet heads 351, supplying temperature-adjusted ink to the internal tank 82.

[0036] <1-2. Detailed structure of inkjet head> Next, the detailed structure of the inkjet head 351 will be described. The inkjet head 351 is a processing unit that performs printing by ejecting ink droplets onto the transported continuous paper 9. As described above, the printing device 1 has eight inkjet heads 351. Since the eight inkjet heads 351 have the same structure, the following describes the structure of only one inkjet head 351.

[0037] In the following description, the longitudinal direction of the base plate, which will be described later as extending like a plate, will be referred to as the "X-direction," the lateral direction of the base plate as the "Y-direction," and the direction perpendicular to the base plate as the "axial direction." For ease of explanation, the "axial direction" will be defined as the up-down direction, and the shape and positional relationship of each part will be described with the drive board unit attached to the ejection unit, which will be described later, as the upper side. However, this definition of the up-down direction is not intended to limit the orientation of the inkjet head according to the present invention during manufacture or use. In other words, "upper side" will be interpreted as "one side in the axial direction," and "lower side" will be interpreted as "the other side in the axial direction." In the following description, "parallel direction" also includes a substantially parallel direction. Furthermore, "perpendicular direction" also includes a substantially perpendicular direction.

[0038] Fig. 4 is a perspective view of one inkjet head 351. As shown in Fig. 3, each inkjet head 351 has a plurality of (five in this embodiment) head assemblies 50, one head mounting unit 60, and a plurality of (ten in this embodiment) rod-shaped connecting members 70.

[0039] 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 section unit 51 and a drive substrate unit 52. The head assembly 50 is configured by attaching the discharge section unit 51 and the drive substrate unit 52 to each other.

[0040] The ejection unit 51 ejects ink in response to a drive signal, which will be described later. Fig. 7 is a longitudinal cross-sectional view of the ejection unit 51 of Fig. 6 taken along plane S1 in Fig. 6 and viewed from the direction of arrow A1. As shown in Figs. 6 and 7, the ejection unit 51 has a base plate 511, an ejection section 512, an adapter board 513, an ejection section side connector 514, a supply-side ink pipe 515, and a discharge-side ink pipe 516. However, the supply-side ink pipe 515 is not shown in Fig. 7.

[0041] The base plate 511 is a plate-like 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 passage 41, a second communication passage 42, and two positioning grooves 431, 432.

[0042] Base through-hole 40 is a through-hole that penetrates base plate 511 in a portion located at the center in the X direction and the Y direction, in an axial direction perpendicular to base plate 511. A head main body portion 81 (described later) of ejection unit 512 is disposed on base plate 511. When ejection unit 512 is fixed to base plate 511, a lower portion of ejection unit 512 is positioned in base through-hole 40. Furthermore, when ejection unit 512 is fixed to base plate 511, portions of base plate 511 located at both ends in the X direction are exposed and not covered by ejection unit 512. This forms exposed portions 401 and 402 where portions of base plate 511 are exposed. Furthermore, a positioning metal fitting 403 is attached to exposed portion 401, and a positioning metal fitting 404 is attached to exposed portion 402. These positioning metal fittings 403 and 404 are members that fit onto pins (not shown) erected on the head mounting unit 60, and are used as references when mounting the head assembly 50 to the head mounting unit 60.

[0043] The first communication passage 41 extends cavernously from the base through-hole 40 through the interior of the base plate 511 toward one end in the X direction and opens into the surface of the exposed portion 401. As a result, a first opening 410 is formed in the surface of the exposed portion 401. The first opening 410 is an opening for supplying ink to the ejection portion 512. The second communication passage 42 extends cavernously from the base through-hole 40 through the interior of the base plate 511 toward the other end in the X direction and opens into the surface of the exposed portion 402. As a result, a second opening 420 is formed in the surface of the exposed portion 402. The first opening 410 and the second opening 420 are each formed in the surface of the base plate 511. As a result, 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.

[0044] The positioning groove 431 is a through-hole formed by axially penetrating a portion of the exposed portion 401 of the base plate 511 that is located on one side in the X direction of the first opening 410. The positioning groove 432 is a through-hole formed by axially penetrating a portion of the exposed portion 402 of the base plate 511 that is located on the other side in the X direction of the second opening 420. However, the two positioning grooves 431, 432 may also be formed by cutting out parts of the exposed portions 401, 402.

[0045] The ejection unit 512 is disposed on the base plate 511 and is a processing unit that ejects ink from the ejection ports 830. As shown in Fig. 7, the ejection unit 512 has a head main body 81, an internal tank 82, a plurality of nozzles 83, a bracket 84, a plurality of (two in this embodiment) hook portions 85, a plurality of (two in this embodiment) first protrusion portions 86, and a plurality of (two in this embodiment) second protrusion portions 87.

[0046] The head main body 81 is a hollow box-shaped housing having a rectangular cylindrical side wall 811, an upper cover 812, and a bottom 813. The bottom 813 has a large opening, exposing a plurality of nozzles 83 to the bottom. Hereinafter, the right-angled portion of the side wall 811 will be referred to as a "corner 811a (see FIG. 6)." The head main body 81 is fixed to a base plate 511 by, for example, screws (not shown). An internal tank 82 capable of temporarily storing ink ejected from the ejection ports 830 is disposed inside the head main body 81. The first opening 410 of the base plate 511 communicates with the internal tank 82 via a first communication passage 41. The second opening 420 communicates with the internal tank 82 via a second communication passage 42.

[0047] The multiple nozzles 83 are arranged at equal intervals in the X and Y directions at the bottom of the head main body 81. Each of the multiple nozzles 83 is connected to an internal tank 82. Each of the multiple nozzles 83 has multiple piezoelectric elements 831 (see FIG. 2) as pressure-generating elements, an ink chamber 832 (see FIG. 2), and an ejection port 830. The ink chamber 832 is connected to the internal tank 82. When ejecting ink, ink flows down from the internal tank 82 to the ink chamber 832, and the ink in the ink chamber 832 is pressurized by the action of the piezoelectric elements 831, causing the ink to be ejected as droplets from the ejection port 830. The piezoelectric elements 831 are controlled by input of a drive signal to apply or not apply pressure to the ink in the ink chamber 832. However, the nozzles 83 may be of a so-called thermal type, in which a heater is used as a pressure-generating element to heat the ink in the ink chamber 832 and generate bubbles to pressurize the ink.

[0048] A bracket 84 is further disposed inside the head main body 81. The bracket 84 is fixed to, for example, the side wall 811. The thickness of the bracket 84 is greater than the thickness of the head main body 81. More specifically, the thickness of the bracket 84 is greater than the thickness of the upper cover 812 of the head main body 81. The bracket 84 also has a mounting portion 841. The mounting portion 841 is parallel to the base plate 511 and extends in a plate shape.

[0049] The two hook portions 85 are fixed to the side walls 811 of the head main body portion 81. The hook portions 85 protrude upward in a V-shape.

[0050] Each of the two first protrusions 86 is a columnar member that protrudes upward from the head main body 81 in the axial direction. In this embodiment, the first protrusions 86 are fixed to the bracket 84 and protrude further upward through a through-hole 814 that penetrates the upper cover 812 of the head main body 81. The first protrusions 86 also have a truncated conical shape that tapers in diameter toward the top. By fixing the first protrusions 86 to the bracket 84, which is thicker than the head main body 81, the position and posture of the first protrusions 86 can be made more stable.

[0051] Each of the two second protrusions 87 is a portion that protrudes in the Y direction from the head main body 81. In this embodiment, the second protrusion 87 is formed by a part of the upper cover 812 of the head main body 81 protruding only on one side in the Y direction.

[0052] The adapter board 513 is placed on the upper surface of the mounting portion 841 of the bracket 84 and is fixed to the mounting portion 841 by, for example, screwing. A processor and memory (not shown) are mounted on the adapter board 513. The memory stores the serial number of the discharge unit 51 on which the adapter board 513 is mounted and information related to the characteristics of the discharge unit 51. This information is transmitted to the control unit 29 via the discharge unit side connector 514 and the drive board side connector 523, drive board 522, and external connection connector 524c (described later). The adapter board 513 is also electrically connected to the piezo elements 831 of the multiple nozzles 83 via wiring (not shown).

[0053] The discharge unit side connector 514 is electrically connected to the adapter substrate 513. As a result, the piezo elements 831 of the multiple nozzles 83 and the discharge unit side connector 514 are electrically connected via the adapter substrate 513. The discharge unit side connector 514 also passes through a through-hole 815 that penetrates the upper cover 812 of the head main body 81, and protrudes further upward.

[0054] The supply-side ink pipe 515 is a pipe that extends in the axial direction on one side in the X direction of the head main body 81. When the drive substrate unit 52 is attached to the ejection section unit 51, the supply-side ink pipe 515 extends upward in the axial direction along the narrow wall 112 side of a side wall 101 of a housing 521 (described later) of the drive substrate unit 52. An ink supply-side connector 517 is connected to the upper end of the supply-side ink pipe 515 in the axial direction. A second supply pipe 92 of the ink supply section 28 is connected to the ink supply-side connector 517. In addition, a lower end of the supply-side ink pipe 515 opposite 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 connecting passage 41, and is supplied to the internal tank 82.

[0055] The discharge-side ink pipes 516 are pipes that extend in the axial direction on the other side in the X direction of the head main body 81. When the drive substrate unit 52 is attached to the ejection section unit 51, the discharge-side ink pipes 516 extend axially upward along the narrow wall 112 of the side wall 101 of a housing 521 (described later) of the drive substrate unit 52. An ink discharge-side connector 518 is connected to the upper end of the discharge-side ink pipes 516 in the axial direction. A first return pipe 93 of the ink supply unit 28 is connected to the ink discharge-side connector 518. A lower end of the discharge-side ink pipes 516, opposite the upper end in the axial direction, is connected to a second opening 420 of the base plate 511. When the return pump 284 of the ink supply unit 28 is driven, the ink stored in the internal tank 82 of each head assembly 50 (ink that has not been ejected but has remained in the internal tank 82 and whose temperature has dropped) passes through the second communication passage 42, the second opening 420, the discharge side ink pipe 516, the first return pipe 93, and the second return pipe 94 and is returned to the storage tank 281.

[0056] The upper axial end of the supply-side ink pipe 515 and the upper axial end of the discharge-side ink pipe 516 are both located above a top plate 102 of the housing 521, which will be described later. This allows an operator to connect the ink supply-side connector 517 fixed to the supply-side ink pipe 515 to the second supply pipe 92, and the ink discharge-side connector 518 fixed to the discharge-side ink pipe 516 to the first return pipe 93, on the upper side of the housing 521. As a result, an operator can perform these connection operations without accessing the side of the housing 521, where space is limited, thereby improving work efficiency.

[0057] The drive board unit 52 is a device that supplies a drive signal to the discharge unit 51. Fig. 9 is a partial perspective view of the head assembly 50, with part of the interior exposed, as viewed from the other side in the Y direction. As shown in Figs. 5, 6, and 9, the drive board unit 52 has a housing 521, a drive board 522, a drive board side connector 523, external connection connectors 524c and 524p, a cooling jacket 525, a supply side cooling pipe 526, a discharge side cooling pipe 527, a plurality of (four in this embodiment) leg portions 528, and a plurality of (two in this embodiment) positioning cylinder portions 529.

[0058] The housing 521 is a hollow member that holds the drive substrate 522, the drive substrate side connector 523, the external connection connectors 524c and 524p, the cooling jacket 525, and the positioning cylinder portion 529. The housing 521 has four side walls 101, a top plate 102, a plurality of (two in this embodiment) engaging portions 103, a plurality of (two in this embodiment) locking members 104, and a plurality of (four in this embodiment) supporting members 105.

[0059] The four side walls 101 extend in a rectangular cylindrical shape along the axial direction. The rectangular cylinder formed by the four side walls 101 is slightly larger than the rectangular cylinder formed by the side walls 811 of the head main body 81. The top plate 102 covers the opening at the upper end of the rectangular cylindrical shape formed by the four side walls 101. The top plate 102 is also provided with a plurality of through holes 200 (two in this embodiment). Each of the two through holes 200 penetrates the top plate 102 in the axial direction. 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 side walls extending in a cylindrical shape along the axial direction and a top plate covering one end of the side walls remote from the base plate 511 in the axial direction.

[0060] The four side walls 101 include a pair of broad walls 111 facing each other and a pair of narrow walls 112 facing each other. The pair of broad walls 111 and the pair of narrow walls 112 are adjacent to each other. Each narrow wall 112 has a smaller surface area than each broad wall 111.

[0061] An engagement portion 103 is fixed to each of the pair of broad 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. The housing 521 can be attached to the discharge unit 51 by engaging the engagement bar 113 with the hook portion 85 of the discharge unit 51. This makes it possible to attach the drive board unit 52 including the housing 521 to and detach it from the discharge unit 51 along the axial direction.

[0062] Further, a notch 110 is provided in only one of the four side walls 101. In this embodiment, of the pair of wide walls 111, the notch 110 is provided in only the wide wall 111 on one side in the Y direction. The notch 110 is a portion cut out from the lower end of the wide wall 111 toward the upper side. When attaching the housing 521 to the discharge unit 51, the worker fits the second protrusion 87 of the discharge unit 51 into the notch 110. Here, if the orientation of the housing 521 relative to the discharge unit 51 is incorrect and the second protrusion 87 hits a side wall 101 that does not have the notch 110, the housing 521 cannot be advanced any further toward the discharge unit 51, and the installation will not be successful. With this configuration, when the drive substrate unit 52 is attached to the ejection unit 51, it is possible to prevent the orientation of the housing 521 relative to the ejection unit 51 from being incorrect.

[0063] The two locking members 104 are fixed to each of the pair of narrow walls 112. Each of the two locking members 104 has a U-shape that is concave toward the narrow walls 112 when viewed in the axial direction. The size of the U-shape is approximately equal to the diameter of the supply-side ink pipe 515 and the diameter of the discharge-side ink pipe 516. As described above, the supply-side ink pipe 515 and the discharge-side ink pipe 516 each extend in the axial direction on the narrow wall 112 side. 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, it is possible to detachably lock the axial intermediate portions of the supply-side ink pipe 515 and the discharge-side ink pipe 516. This makes it possible to prevent the supply-side ink pipe 515 and the discharge-side ink pipe 516 from bending or becoming tangled with surrounding components.

[0064] Two more support members 105 are fixed to each of the pair of narrow face walls 112. In this embodiment, the two support members 105 are fixed to each narrow face wall 112 with a gap between them in the axial direction. Each support member 105 protrudes outward in the X direction from the narrow face wall 112 in a plate-like shape. 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. The two support holes 106 provided in the two support members 105 fixed to one narrow face wall 112 are located at the same position as each other when viewed in the axial direction.

[0065] 6, of the pair of narrow side walls 112, only the narrow side wall 112 on one side in the X direction is further provided with a plurality of through holes 120 (four in this embodiment). In this embodiment, of the pair of narrow side walls 112, only the narrow side wall 112 to which the supply-side ink pipe 515 is engaged is provided with four through holes 120 spaced apart from one another in the axial direction. 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 pipe of the cooling jacket 525, which will be described later. However, the through holes 120 may be provided in the top plate 102 of the housing 521.

[0066] The drive substrate 522 is housed inside the housing 521 and fixed to the side wall 101 of the housing 521 by, for example, screws. A drive substrate connector 523 is electrically connected to a 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 an upper end of the drive substrate 522 via, for example, an FFC (flexible flat cable). Furthermore, the two external connection connectors 524c and 524p are exposed to the outside through through holes 200 in the top plate 102 of the housing 521.

[0067] A power line extending from an external power source is connected to the external connection connector 524p. This allows power to be supplied from the external power source to drive the drive substrate 522, the adapter substrate 513 of the discharge unit 51, and the plurality of piezo elements 831. A communication cable extending from the control unit 29 is connected to the external connection connector 524c. This allows the control unit 29 to supply small dot signals for forming small dots, medium dot signals for forming medium dots, and large dot signals for forming large dots to the drive substrate 522 via the external connection connector 524c. The drive substrate 522 generates drive signals including drive waveforms for driving the plurality of piezo elements 831 from the supplied small dot signals, medium dot signals, and large dot signals.

[0068] When the housing 521 is attached to the ejection unit 51, the drive board connector 523 held in the housing 521 and the ejection section connector 514 of the ejection unit 51 are electrically connected. This allows power to be supplied from an external power source, driving the drive board 522, the adapter board 513 of the ejection unit 51, and the multiple piezo elements 831. The drive board connector 523 also outputs a drive signal generated in the drive board 522, and the ejection section connector 514 receives the drive signal. The multiple piezo elements 831 are further controlled based on the drive signal. As a result, ink droplets are ejected from the ejection ports 830 toward the continuous paper 9, recording characters and images on the surface of the continuous paper 9.

[0069] 9, in this embodiment, when the ejector unit 51 and the drive board unit 52 are attached to each other, at least a portion of the drive board 522 overlaps horizontally with the ejector-side connector 514. This configuration reduces the size of the head assembly 50, which includes the ejector unit 51 and the drive board unit 52, in the axial direction. Therefore, the drive board 522, which generates high-temperature heat, is close to precision elements such as the multiple piezo elements 831 of the ejector unit 51 and the ink stored in the internal tank 82 of the ejector unit 51.

[0070] Therefore, in this embodiment, a cooling jacket 525 is attached between the drive substrate 522 and the inner surface of the housing 521 (on the back surface of the drive substrate 522). A known water-cooled device is used for the cooling jacket 525, which cools the drive substrate 522 by flowing a cooling medium such as cooling water through the inside of piping. In this embodiment, two pipings for circulating the cooling water are arranged in a loop on the back surface of the drive substrate 522. This makes it possible to prevent the high temperature heat generated in the drive substrate 522 from being transmitted to the discharge unit 51 or the external atmosphere. As a result, it is possible to prevent deterioration and damage due to heat of precision elements such as the plurality of piezoelectric elements 831.

[0071] On the other hand, the cooling jacket 525 itself is disposed at a distance from the discharge unit 51 in the axial direction. This makes it possible to suppress a decrease in the temperature of the ink stored in the internal tank 82 even when a cooling medium circulates inside the piping of the cooling jacket 525. The driving of the cooling jacket 525 is controlled by an external device (not shown). However, the driving of the cooling jacket 525 may also be controlled by the control unit 29.

[0072] Both ends of the two pipes of the cooling jacket 525 are connected to connection ports of four joints 531 fixed to the narrow wall 112 of the housing 521. Furthermore, lower ends of two supply-side cooling pipes 526 extending from an external device are connected to the connection ports of two of the four joints 531. The supply-side cooling pipes 526 are pipes through which the cooling medium supplied to the cooling jacket 525 passes. 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 pipes 527 are pipes through which the cooling medium discharged from the cooling jacket 525 passes. The two supply-side cooling pipes 526 and the two discharge-side cooling pipes 527 each extend upward along the narrow 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 pipes of the cooling jacket 525, and is discharged through the discharge-side cooling pipe 527.

[0073] The four joints 531 and their connection ports are located near the top plate 102 of the housing 521. In this embodiment, of the four joints 531 and their connection ports, three of them are located above the center of the housing 521 in the axial direction. That is, the four joints 531 and their connection ports are arranged at an axial distance from the ejection unit 51. This further suppresses a decrease in the temperature of the ink stored in the internal tank 82. This also further improves the ease of connecting the supply-side cooling pipe 526 and the discharge-side cooling pipe 527 to the connection ports of the four joints 531. However, it is sufficient that at least some of the joints 531 and their connection ports are located above the center of the housing 521 in the axial direction.

[0074] Furthermore, when the drive substrate unit 52 is attached to the ejector unit 51, the four joints 531 and connection ports to which the ends of the supply-side cooling pipes 526 and the discharge-side cooling pipes 527 are connected are spaced apart in the axial direction 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. This prevents the temperatures of the supply-side cooling pipes 526 and the discharge-side cooling pipes 527 from affecting each other, and the temperatures of the supply-side ink pipes 515 and the discharge-side ink pipes 516 from affecting each other. As a result, precise temperature control of the ink stored in the drive substrate 522 and the internal tank 82 is possible. Furthermore, 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. This allows ink to be supplied to the ejector 512 from a position away from the drive substrate 522. As a result, the heat generated in the drive substrate 522 can be prevented from being transmitted to the ink supplied to the ejection section 512 .

[0075] 5 and 6, legs 528 are fixed, for example, by screws, to the outer surface of each of the four side walls 101 that extend in the shape of a rectangular tube. Each of the four legs 528 extends in the axial direction. The lower ends of the four legs 528 are located at equal positions relative to each other in the axial direction.

[0076] When attaching the housing 521 to the discharge section unit 51, the worker first grips the handle 130 of the housing 521 and moves the drive board unit 52 toward the base plate 511 so that the four side walls 101 cover the head main body 81. When the drive board 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. This allows the drive board unit 52 to be positioned in the axial direction relative to the discharge section unit 51. That is, in this embodiment, the contact between the base plate 511 and the legs 528 forms a "first positioning portion" that positions the drive board unit 52 in the axial direction relative to the discharge section unit 51.

[0077] At the same time, the four side walls 101 cover the head main body 81 (more specifically, the inner surfaces of the four legs 528 cover the four corners of the head main body 81), so that the inner surfaces of the four side walls 101 come into contact with the corners 811a of the head main body 81. This makes it possible to position the drive substrate unit 52 relative to the discharge section unit 51 in the horizontal direction parallel to the base plate 511. That is, in this embodiment, the inner surfaces of the four side walls 101 come into contact with the corners 811a of the head main body 81, thereby simultaneously configuring a "first positioning section" that positions the drive substrate unit 52 relative to the discharge section unit 51 in the horizontal direction parallel to the base plate 511.

[0078] As shown in FIG. 9, two further bottomed cylindrical positioning tubes 529 are arranged between the drive substrate 522 and the inner surface of the housing 521 (on the back surface of the drive substrate 522). Each of the two positioning tubes 529 is fixed to the back surface of the drive substrate 522, for example, by screwing. Each of the two positioning tubes 529 has a recess 540. The recess 540 is recessed in the axial direction from the lower end surface of the positioning tube 529 toward the upper side. 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 truncated cone shape that tapers toward the upper side. The recess 540 is slightly larger than the first protrusion 86.

[0079] When attaching the housing 521 to the discharge unit 51, the worker covers the head main body 81 with the four side walls 101 as described above, and then slides the four side walls 101 along the corners 811a of the head main body 81. This causes the upper tips of the first protrusions 86 to fit into the recesses 540 of the positioning tube 529. At this time, the tips of the first protrusions 86 have a small diameter, so they fit easily into the recesses 540. Then, when the worker moves the drive board unit 52 closer to the base plate 511, the first protrusions 86 fit all the way into 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. Therefore, the first protrusions 86 fit all the way into the recesses 540 without any gaps, 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 relative to the discharge section unit 51 in the horizontal direction parallel to the base plate 511. That is, in this embodiment, by fitting the first protrusion 86 into the recess 540, a "second positioning section" is formed that positions the drive substrate unit 52 relative to the discharge section unit 51 in the horizontal direction parallel to the base plate 511 and more precisely than the "first positioning section."

[0080] However, the configuration of the "second positioning portion" is not limited to this. For example, the "second positioning portion" may be configured by fitting a protrusion that protrudes downward and is provided on the drive substrate unit 52 into a recess that is recessed downward and is provided on the discharge portion unit 51.

[0081] As described above, when attaching the housing 521 to the discharge section unit 51, the worker first moves the legs 528 of the drive board unit 52 toward the base plate 511 of the discharge section 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 section unit 51 at the "first positioning portion." In the process of the worker moving the drive board unit 52 toward the base plate 511, the first protrusion 86 of the discharge section unit 51 fits deep into the recess 540 of the drive board unit 52 at the "second positioning portion," and the entire first protrusion 86 comes into contact with the recess 540. When the inner surfaces of the four side walls 101 of the drive substrate unit 52 are brought into contact with the head main body 81 of the discharge unit 51, the head main body 81 and base plate 511 of the discharge unit 51, which constitute the "first positioning portion," and the four side walls 101 and legs 528 of the drive substrate unit 52 are visible from the outside. This allows the worker to position the drive substrate unit 52 relative to the discharge unit 51 while visually checking the "first positioning portion" from the outside, and then more precisely position the drive substrate unit 52 relative to the discharge unit 51 using the "second positioning portion." As a result, the drive substrate unit 52 can be positioned relative to the discharge unit 51 easily and with greater precision.

[0082] When the first protrusion 86 of the "second positioning portion" fits all the way into the recess 540, the drive board side connector 523 held in the housing 521 and the ejection section side connector 514 of the ejection section unit 51 are automatically and electrically connected. With this configuration, the ejection section side connector 514 and the drive board side connector 523 can be accurately connected without misalignment. As a result, a drive signal generated in the drive board 522 is output to the ejection section unit 51, and ink can be ejected from the ejection port 830 by controlling the multiple piezo elements 831 in accordance with the drive signal.

[0083] The head mounting unit 60 is a unit permanently 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 long, strip-shaped, plate-like member extending in the XY plane. Each of the five through holes 602 axially penetrates the head mounting plate 601. As will be described later, the ejection unit 51 and the drive board unit 52 are attached to each other and installed axially on the surface 601f of the head mounting plate 601. When the inkjet head 351 is viewed axially with the ejection unit 51 and the drive board unit 52 installed on the surface 601f of the head mounting plate 601, each through hole 602 surrounds a plurality of nozzles 83 and is smaller than the base plate 511. Therefore, the ejection ports 830 of the multiple nozzles 83 are exposed on the rear 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 51 through the through holes 602 of the head mounting plate 601 onto the continuous paper 9 being transported below.

[0084] The head mounting plate 601 is further provided with ten mounting holes 603. In this embodiment, the mounting holes 603 are formed on the outer sides of both ends in the X direction of each of the five through holes 602, i.e., two on each side of each through hole 602. In this embodiment, the mounting holes 603 are threaded holes formed from the front surface 601f toward the back surface 601b of the head mounting plate 601. The mounting holes 603 are formed with female threads.

[0085] The connecting member 70 is a rod-shaped member used to connect the discharge unit 51, the drive substrate unit 52, and the head mounting unit 60 to one another. FIG. 10 is a perspective view of one connecting member 70. When the discharge unit 51 and the drive substrate unit 52 are installed on the surface 601f of the head mounting 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 a first end 701, and the upper end of the connecting member 70 will be referred to as a 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.

[0086] The thin-diameter portion 703 is located at the first end 701 of the connecting member 70 and is a thin-diameter portion extending in a cylindrical shape in the axial direction. A male thread is formed in the thin-diameter portion 703. The diameter of the thin-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 closer to the second end 702 than the thin-diameter portion 703 and is a portion extending in a cylindrical shape in the axial direction and having a larger diameter than the thin-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 prism-shaped portion 705 is located at the second end 702 of the connecting member 70. The polygonal prism-shaped portion 705 of this embodiment extends in the axial direction in the shape of a quadrangular prism. However, the shape of the polygonal prism-shaped portion 705 is not limited thereto. The polygonal columnar portion 705 only needs to extend in the axial direction in the shape of a polygonal column.

[0087] A commercially available torque wrench 800, as shown 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 matches the shape of the polygonal columnar portion 705 (in this embodiment, a square columnar shape).

[0088] When attaching the discharge unit 51 and the drive board unit 52 to the head mounting plate 601, the worker first attaches the discharge unit 51 and the drive board unit 52 to each other to form the head assembly 50, and then installs the head assembly 50 axially on the surface 601f of the head mounting plate 601 so as to cover the through-hole 602. Next, the worker uses two connecting members 70 to pass their small diameter portions 703 through the two positioning grooves 431 and 432 of the base plate 511 and screw them into the two mounting holes 603, respectively. At this time, the large diameter portion 704 of the connecting member 70 does not pass through the positioning grooves 431 and 432 of the base plate 511. Therefore, an end surface 707 of the large diameter portion 704 adjacent to the small diameter portion 703 comes into contact with the exposed portions 401 and 402 of the base plate 511 and presses the exposed portions 401 and 402 downward.

[0089] 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 faces of the large diameter portions 704) of the two connecting members 70 can fix the discharge unit 51 including the base plate 511 and the drive board unit 52 attached to the discharge unit 51 to the head mounting plate 601. Note that the portions of the head assembly 50 that the connecting members 70 come into contact with and press are limited to the areas near the positioning grooves 431, 432 of the base plate 511. This makes it possible to prevent distortion of other components of the head assembly 50, such as the housing 521.

[0090] Furthermore, in this embodiment, when the ejection portion unit 51 and the drive board unit 52 are fixed to the head mounting plate 601, the supply-side ink pipes 515 and the discharge-side ink pipes 516 extend in the axial direction at positions closer to the narrow surface wall 112 than the connecting member 70. In other words, the connecting member 70 is positioned farther from the housing 521 than the supply-side ink pipes 515 and the discharge-side ink pipes 516. This makes it possible to further prevent distortion of the housing 521 and the like due to pressure from the connecting member 70.

[0091] The connecting member 70 is provided with two grooves 706. The two grooves 706 are recessed inward over the entire circumference of a portion of the connecting member 70 in the axial direction. In this embodiment, the two grooves 706 are provided in the large diameter portion 704 of the connecting member 70, spaced apart from each other in the axial direction by a gap. A resin ring, for example, is fitted into each groove 706. As a result, two flanges 750 are formed in the large diameter portion 704 of the connecting member 70, protruding in a ring shape over the entire circumference.

[0092] Here, the diameter 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 aligned axially in the housing 521. Therefore, the portion of the connecting member 70, excluding the flange portion 750, can pass through each of the two support holes 106 and move freely in the axial direction. 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 comes into contact with the support member 105. In this embodiment, the portion of the connecting member 70, excluding the flange portion 750, is passed through the two support holes 106 aligned axially, while the flange portion 750 is positioned between the two support members 105 in the axial direction. This allows the support members 105 to hold the connecting member 70 while preventing the connecting member 70 from falling. As a result, the workability of attaching the head assembly 50 to the head mounting plate 601 is further improved.

[0093] As shown in FIG. 4 , in this embodiment, five head assemblies 50 are arranged in a zigzag (staggered) pattern on the head mounting plate 601 for one inkjet head 351. The five head assemblies 50 are fixed to the surface 601f of the head mounting plate 601 via connecting members 70, with their side walls 101 adjacent to each other. Furthermore, when the five head assemblies 50 are fixed to the head mounting plate 601, the gap between the narrow walls 112 of adjacent head assemblies 50 is larger than the gap between the wide walls 111 of adjacent head assemblies 50. As described above, when attaching the head assemblies 50 to the head mounting plate 601, the small-diameter portions 703 of the two connecting members 70 held on the narrow wall 112 side of the housing 521 are inserted 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, work can be performed on the side of the narrow wall 112 where there is a relatively large space, further improving workability.

[0094] Furthermore, the second end 702 of the connecting member 70, which is opposite to the first end 701 fixed to the mounting hole 603 of the head mounting plate 601, protrudes upward in the axial direction beyond the discharge unit 51 and the drive board unit 52 (see FIG. 5). This makes it even easier to fit the torque wrench 800 into the second end 702 of the connecting member 70. As a result, the workability when mounting the head assembly 50 to the head mounting plate 601 is further improved.

[0095] 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 on the narrow wall 112 side of the housing 521. Therefore, replacement of each of these pipes can be performed on the narrow wall 112 side where there is relatively more space, further improving workability.

[0096] In this embodiment, the inkjet head 351 has the above-described configuration, which makes it easy to replace each part, including the ejection unit 51, which wears out relatively quickly. Furthermore, when the ejection unit 51 and the drive substrate unit 52 are reattached to each other, the ejection unit side connector 514 and the drive substrate side connector 523 can be accurately connected without misalignment. As a result, by outputting a drive signal generated in the drive substrate 522 to the ejection unit 51 and controlling the multiple piezo elements 831 in accordance with the drive signal, ink can be ejected again from the ejection ports 830.

[0097] <2. Modifications> Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

[0098] In the above embodiment, the ink supply unit 28 is configured to circulate ink between the inkjet head 351 and the ink supply unit 28, and to supply temperature-adjusted ink to the inkjet head 351. However, the ink supply unit 28 may also supply ink to the inkjet head 351 in one direction.

[0099] In the above embodiment, the ejection section 512 has one internal tank 82. However, the ejection section 512 may have multiple internal tanks 82. For example, although not shown, the ejection section 512 may have a first internal tank 82a (ink supply internal tank 82a) that communicates with the first communication passage 41 (see FIG. 8) and a second internal tank 82b (ink discharge internal tank 82b) that communicates with the second communication passage 42 (see FIG. 8). 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 be configured to supply ink from the first communication passage 41 to the ink chamber 832 via the first internal tank 82a, and to discharge ink from the ink chamber 832 to the second communication passage 42 via the second internal tank 82b.

[0100] Furthermore, the elements appearing in the above-described embodiments and modifications may be combined as appropriate within the scope of not causing any contradiction. [Explanation of symbols]

[0101] 1 Printing device 9 Continuous Paper 28 Ink supply unit 29 Control Unit 40 Base through hole 41 1st communication passage 42 2nd communication passage 50 Head Assembly 51 Discharge unit 52 Drive board unit 60 Head mounting unit 70 Connecting member 81 Head body 82 Inner Tank 83 nozzle 84 Bracket 86 1st protrusion 87 Second protrusion 101 Side wall 102 Top plate 104 Locking member 105 Support member 106 Support hole 110 Notch 111 Wide Wall 112 Narrow 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 Ink supply piping 516 Ink discharge pipe 521 Case 522 Drive board 523 Drive board side connector 525 Cooling Jacket 528 Legs 540 recess 601 Head mounting plate 603 Mounting hole 701 First end 702 Second end 703 Thin section 704 Large diameter part 705 Polygonal columnar part 707 End face 750 flange 800 torque wrench 830 Discharge port 831 Piezo element

Claims

1. An inkjet head that prints by ejecting ink onto a print medium, a discharge unit that discharges the ink in response to a drive signal; a drive substrate unit that supplies the drive signal to the ejection unit; and The discharge unit includes: A base plate and a discharge unit disposed on the base plate and configured to discharge the ink from a discharge port; a discharge portion side connector for receiving the drive signal; and The drive substrate unit includes: a driving substrate that generates the driving signal; a drive board side connector for outputting the drive signal; a housing for holding the drive board and the drive board side connector; and the drive board unit is detachable from the discharge unit along an axial direction perpendicular to the base plate, and when the housing is attached to the discharge unit, the drive board side connector and the discharge unit side connector are connected, and at least a portion of the drive board overlaps the discharge unit side connector in a horizontal direction; The housing includes: four side walls extending in a rectangular cylindrical shape along the axial direction; a top plate covering one end of the side wall in the axial direction away from the base plate; and The four side walls are: A pair of wide walls facing each other, A pair of narrow walls facing each other and having a surface area smaller than that of the wide wall; and The drive substrate unit includes: a cooling jacket disposed between the drive substrate and the inner surface of the housing, the cooling jacket including a loop-shaped pipe for circulating cooling water, the cooling water flowing through the inside of the pipe to cool the drive substrate; a plurality of connection ports formed in the side wall, to which both ends of the piping of the cooling jacket are connected; and At least some of the plurality of connection ports are located near the top plate, and the plurality of connection ports are provided at intervals from each other in the axial direction on only one of the pair of narrow surface walls, The inkjet head, wherein the cooling jacket is disposed spaced apart from the ejection unit in the vertical direction.

2. 2. The inkjet head according to claim 1, The inkjet head, wherein the ejection unit has an opening for supplying the ink to the ejection unit, and the opening is located at the same position as the base plate in the axial direction.

3. 3. The inkjet head according to claim 1, The inkjet head has an internal tank disposed in the ejection section, which is capable of temporarily storing ink ejected from the ejection ports.

4. An inkjet head that prints by ejecting ink onto a print medium, a discharge unit that discharges the ink in response to a drive signal; a drive substrate unit that supplies the drive signal to the ejection unit; and The discharge unit includes: A base plate and a discharge unit disposed on the base plate and configured to discharge the ink from a discharge port; a discharge portion side connector for receiving the drive signal; and The drive substrate unit includes: a driving substrate that generates the driving signal; a drive board side connector for outputting the drive signal; a housing for holding the drive board and the drive board side connector; and the drive board unit is detachable from the discharge unit along an axial direction perpendicular to the base plate, and when the housing is attached to the discharge unit, the drive board side connector and the discharge unit side connector are connected, and at least a portion of the drive board overlaps the discharge unit side connector in a horizontal direction; The housing includes: four side walls extending in a rectangular cylindrical shape along the axial direction; a top plate covering one end of the side wall in the axial direction away from the base plate; and The four side walls are: A pair of wide walls facing each other, A pair of narrow walls facing each other and having a surface area smaller than that of the wide wall; and The drive substrate unit includes: a cooling jacket disposed between the drive substrate and the inner surface of the housing, the cooling jacket including a loop-shaped pipe for circulating cooling water, the cooling water flowing through the inside of the pipe to cool the drive substrate; a plurality of connection ports formed in the side wall, to which both ends of the piping of the cooling jacket are connected; and At least some of the plurality of connection ports are located near the top plate, and the plurality of connection ports are provided at intervals from each other in the axial direction on only one of the pair of narrow surface walls, The inkjet head, wherein the cooling jacket is directly attached to the rear surface of the drive substrate.

Images