Liquid discharge head and liquid discharge device

Abstract

To efficiently cool drive elements.SOLUTION: A liquid discharge head comprises: a first discharge element substrate and a second discharge element substrate each having a discharge element for discharging liquid from a discharge port; and a first drive circuit substrate and a second drive circuit substrate each having a drive element for driving the discharge elements of the discharge element substrates. The liquid discharge head further comprises a cooling member configured to contact the first drive circuit substrate and the second drive circuit substrate. The cooling member includes: an inlet for introducing a coolant from outside; an outlet for discharging the coolant to outside; and a first coolant channel and a second coolant channel each connecting the inlet and the outlet, the first coolant channel cooling the first drive circuit substrate and the second coolant channel cooling the second drive circuit substrate. The first coolant channel and the second coolant channel are arranged so as to sandwich the inlet therebetween.SELECTED DRAWING: Figure 26

Description

[Technical Field]

[0001] The present disclosure relates to a liquid ejection head and a liquid ejection apparatus. [Background technology]

[0002] High-speed recording is required for liquid ejection devices used for business, commercial, or industrial purposes. To achieve high-speed recording, liquid ejection heads have been proposed that incorporate multiple ejection modules to increase the ejection width per pass. The ejection modules of such liquid ejection heads may incorporate drive elements for driving the ejection elements. However, heat generation by the drive elements poses a problem when attempting to achieve high-speed recording.

[0003] Patent Document 1 describes a technology in which a heat sink for cooling a drive circuit board on which drive elements are provided is brought into contact with each drive element, and cooling water is supplied to each heat sink in parallel to cool the drive elements. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-199021 Summary of the Invention [Problem to be solved by the invention]

[0005] Increasing the number of ejection elements to achieve high-speed printing requires increasing the number of drive elements and drive circuit boards on which the drive elements are mounted. In the method of Patent Document 1, increasing the number of drive circuit boards requires the installation of as many heat sinks to cool each drive element and as many flow paths to supply each heat sink, resulting in an increase in the number of components. Furthermore, arranging multiple ejection modules in a staggered pattern can make the layout of the supply paths to the heat sinks difficult. Furthermore, because each drive circuit board has its own independent heat sink, the patent document does not disclose a configuration for distributing the cooling load of each heat sink when the heat generation of each drive circuit board varies. That is, a configuration is needed that can efficiently cool each drive circuit board evenly even when the number of drive elements is increased, distribute the cooling load even when the heat generation of each drive element varies, and increase the layout flexibility of the coolant supply paths to the heat sinks.

[0006] The present disclosure aims to efficiently cool a driving element. [Means for solving the problem]

[0007] A liquid ejection head according to one aspect of the present disclosure comprises a liquid ejection unit having a first ejection element substrate and a second ejection element substrate, each of which has ejection elements for ejecting liquid from an ejection port, a first drive circuit board provided with first drive elements for driving the ejection elements on the first ejection element substrate, and a second drive circuit board provided with second drive elements for driving the ejection elements on the second ejection element substrate, and further comprises a cooling member configured to be in contact with the first drive circuit board and the second drive circuit board, respectively, the cooling member having an inlet for introducing a coolant from the outside, an outlet for discharging the coolant to the outside, a first coolant flow path connecting the inlet and the outlet and for cooling the first drive circuit board, and a second coolant flow path connecting the inlet and the outlet and for cooling the second drive circuit board, the first coolant flow path and the second coolant flow path being arranged so as to sandwich the inlet from each other. [Effects of the Invention]

[0008] According to the present disclosure, the driving element can be cooled efficiently. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a liquid ejection device. [Figure 2] FIG. 2 is a perspective view of a liquid ejection head. [Figure 3] FIG. 2 is a perspective view of a liquid ejection head. [Figure 4] FIG. 2 is an exploded perspective view of the liquid ejection head. [Figure 5] FIG. 2 is a diagram illustrating an electrical connection configuration of the liquid ejection head. [Figure 6] FIG. 2 is a perspective view of a liquid ejection unit. [Figure 7] FIG. 2 is a perspective view of a liquid ejection unit. [Figure 8] FIG. 2 is an exploded perspective view of the liquid ejection unit. [Figure 9] FIG. 2 is an enlarged view of an electrode portion of the liquid ejection unit. [Figure 10] FIG. [Figure 11] FIG. 2 is a plan view of the liquid ejection head assembled to the support unit, as viewed from the ejection surface side. [Figure 12] 12 is a cross-sectional view taken along the line XII-XII in FIG. [Figure 13] 13 is a cross-sectional view taken along the line XIII-XIII in FIG. 11. [Figure 14] 14 is a cross-sectional view taken along the line XIV-XIV in FIG. [Figure 15] 10A and 10B are diagrams showing a connection configuration of a liquid member between a support unit and a liquid supply unit. [Figure 16] 10 is a cross-sectional view of a fluid connection between a liquid supply unit and a liquid supply member. FIG. [Figure 17] 10A and 10B are diagrams illustrating a connection configuration of a liquid member of a support unit. [Figure 18]3A and 3B are diagrams illustrating a connection configuration of a liquid member of a liquid ejection unit. [Figure 19] FIG. 2 is a diagram showing a fluid connection configuration within an ejection element substrate. [Figure 20] FIG. [Figure 21] FIG. [Figure 22] 22-XXII cross-sectional view of FIG. 20. [Figure 23] FIG. 4 is a cross-sectional view of an electrical connection portion between the liquid ejection device main body and the liquid ejection head. [Figure 24] FIG. [Figure 25] FIG. 2 is a cross-sectional view of the cooling unit. [Figure 26] FIG. 2 is a plan view of the cooling unit. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, examples of embodiments of the present disclosure will be described with reference to the drawings. However, the following description does not limit the scope of the present disclosure. As an example, in this embodiment, a method of ejecting liquid by driving a piezoelectric element will be described. However, liquid ejection heads employing a thermal method of ejecting liquid by bubbles generated by a heater element, as well as various other liquid ejection methods, are also within the scope of application of the present disclosure. In other words, the liquid ejection head can be a head having any energy generating element configured to generate energy for ejecting liquid.

[0011] This embodiment can be an inkjet recording apparatus (recording apparatus) in a form in which a liquid such as ink is circulated between a tank and a liquid ejection head, but other forms are also possible. For example, instead of circulating the ink, a form in which tanks are provided upstream and downstream of the liquid ejection head, and the ink flows from one tank to the other, thereby causing the ink to flow within the pressure chamber. Furthermore, the apparatus according to the present disclosure is not limited to a recording apparatus that ejects ink, but can be a liquid ejection apparatus that ejects any liquid.

[0012] <<First Embodiment>> FIG. 1 is a schematic diagram illustrating an example of a liquid ejection device 10 according to the present embodiment. The liquid ejection device 10 includes a so-called one-pass liquid ejection head 100, which, when recording an image in a predetermined area on a recording medium 20, completes the recording of the image in the predetermined area by moving the recording medium 20 in a single movement. The liquid ejection head 100 has ejection openings arranged across a range corresponding to the entire width of the recording medium 20 (the X direction in FIG. 1). The recording medium 20 is transported in the direction of arrow A by a transport unit 11, and recording is performed by the liquid ejection head 100. The liquid ejection head 100 according to the present embodiment is a liquid ejection head 100 corresponding to a total of four colors: cyan, magenta, yellow, and black. More specifically, the liquid ejection head 100 includes two heads for each color. Specifically, the liquid ejection head 100 includes cyan heads 100Ca and 100Cb, magenta heads 100Ma and 100Mb, yellow heads 100Ya and 100Yb, and black heads 100Ka and 100Kb. The following description focuses on one of these eight heads. For the sake of simplicity, any one head will be described as the liquid ejection head 100. The liquid ejection head of the present disclosure may be a head of any form and is not limited to the example shown in FIG.

[0013] In this embodiment, the direction in which the liquid is ejected (gravity direction) is defined as the +Z direction, the upstream side of the transport direction of the recording medium 20 is defined as the +Y direction, and the arrangement direction in which the ejection ports are arranged in the head is defined as the +X direction.

[0014] FIG. 2 is a perspective view of the liquid ejection head 100 of this embodiment. FIG. 3 is a perspective view of the liquid ejection head 100 of this embodiment, seen from a different direction than FIG. 2. FIG. 4 is an exploded perspective view of the liquid ejection head 100 of this embodiment. The configuration of the liquid ejection head 100 will be described using FIGS. 2 to 4. As mentioned above, one of the eight heads shown in FIG. 1 will be described below as the liquid ejection head 100.

[0015] As shown in Fig. 3, the liquid ejection head 100 is a head in which four ejection element substrates 210 capable of ejecting liquid are arranged in a staggered pattern on a support member 310. The liquid ejection head 100 is positioned in the main body of the liquid ejection device by a reference member 340. As shown in Fig. 2, a liquid connection part 501 and a coolant connection part 611 are provided on the top of the liquid ejection head 100. The liquid connection part 501 is connected to a liquid supply part 13 on the liquid ejection device main body side, and the coolant connection part 611 is connected to a coolant supply part 14 on the liquid ejection device main body side. As a result, liquid such as ink and a coolant are supplied from the liquid ejection device main body into the liquid ejection head 100.

[0016] The exterior of the liquid ejection head 100 is provided with a cover member 420 and an electrical connection portion cover member 430 for covering and protecting the electrical board, electrical connection portions, etc. As shown in FIG. 4, the liquid ejection head 100 internally includes a support unit 300 including a support member 310, an electrical wiring board 400, and an electrical wiring board support member 410 for holding the electrical wiring board 400. The liquid ejection head 100 also includes a liquid supply unit 500 that supplies liquid to the liquid ejection units 200 via the support unit 300, and a cooling unit 600 that cools the drive circuit. The liquid ejection head 100 includes a plurality of liquid ejection units 200, specifically four liquid ejection units 200. The configuration of each portion of the liquid ejection head 100 will be described in detail below.

[0017] FIG. 5 is a diagram showing the electrical connection configuration of the liquid ejection head 100 of this embodiment. The liquid ejection device main body and the ejection element substrate 210 are electrically connected via a flexible wiring substrate 250 and an electrical wiring substrate 400. The electrical wiring substrate 400 is electrically connected to a control unit (not shown) on the liquid ejection device main body side by electrical connection terminals 402. An ejection drive signal and power required for ejection are supplied to the electrical wiring substrate 400 via the electrical connection terminals 402. The electrical wiring substrate 400 and the flexible wiring substrate 250 are electrically connected by electrical connection portions 401. By consolidating the wiring using the electrical circuit within the electrical wiring substrate 400, the number of terminals of the electrical connection terminals 402 can be reduced compared to the number of terminals on the ejection element substrate 210. This reduces the number of electrical connections that need to be removed when assembling the liquid ejection head 100 to the liquid ejection device or when replacing the liquid ejection head 100. A drive circuit substrate 251 for driving the ejection elements of the ejection element substrate 210 is provided on the flexible wiring substrate 250. The drive circuit board 251 is provided with drive elements for driving the ejection elements. The ejection drive signal supplied to the electric wiring board 400 is input to the drive circuit board 251. The drive circuit board 251 performs drive control to drive each recording element in accordance with the ejection drive signal.

[0018] 5, in this embodiment, one liquid discharge unit 200 is provided with two flexible wiring boards 250: flexible wiring board a 250a and flexible wiring board b 250b. In the following, when describing an individual flexible wiring board, it will be referred to as flexible wiring board a 250a or flexible wiring board b 250b, and when describing matters common to both, it will be simply referred to as flexible wiring board 250. Furthermore, the drive circuit board 251 provided on the flexible wiring board a 250a will be referred to as drive circuit board a 251a equipped with drive element a. The drive circuit board 251 provided on the flexible wiring board b 250b will be referred to as drive circuit board b 251b equipped with drive element b. In the following, when describing individual drive circuit boards, they will be referred to as drive circuit board a: 251a or drive circuit board b: 251b, and when describing matters common to both, they will be simply referred to as drive circuit board: 251.

[0019] Fig. 6 is a perspective view of the liquid ejection unit 200. Fig. 7 is a perspective view of the liquid ejection unit 200. Fig. 8 is an exploded perspective view of the liquid ejection unit 200. Fig. 9 is an enlarged view of the electrode portion of the liquid ejection unit 200. The configuration of the liquid ejection unit 200 will be described below with reference to Figs. 6 to 9.

[0020] 6 to 8, the liquid ejection unit 200 has an ejection element substrate 210 that ejects liquid, an ejection element substrate flow path member 220 that supplies liquid to the ejection element substrate 210, and a flow path member 240 that supplies liquid to the ejection element substrate flow path member 220. The liquid ejection unit 200 also has a flexible wiring substrate 250 that is electrically connected to the ejection element substrate 210, and an ejection element substrate support member 230 that is joined to the ejection surface side of the ejection element substrate 210.

[0021] As shown in FIG. 9, electrode portions 212 are provided on thin plate portions 211 at both ends of the ejection element substrate 210. FIG. 9 is an enlarged view of one end of the ejection element substrate 210. Note that this end refers to an end in a direction intersecting the arrangement direction of the ejection elements (or ejection ports) on the ejection element substrate 210. As shown in FIG. 9, the ejection element substrate 210 and the flexible wiring substrate 250 are electrically connected by contacting the electrodes of the electrode portion 212 and the first electrical connection portion 252 of the flexible wiring substrate 250. In order to prevent liquid from penetrating into this electrical connection portion and to reinforce the thin plate portion 211 of the ejection element substrate 210, an ejection element substrate support member 230 is joined to the ejection surface side of the thin plate portion 211, as shown in FIGS. 6 to 8. The flexible wiring substrate 250 is provided with a drive circuit board 251 for driving the ejection elements of the ejection element substrate 210 (see FIG. 5). As shown in Figures 7 and 8, flexible wiring board a: 250a and flexible wiring board b: 250b are arranged opposite each other so as to sandwich the ejection element substrate 210 from opposing directions that are approximately perpendicular to the arrangement direction in which the ejection elements are arranged.

[0022] FIG. 10 is a perspective view of a support unit 300 that supports a liquid ejection unit 200. The support unit 300 includes a support member 310 to which the liquid ejection unit 200 is joined and a frame member 320 that surrounds the liquid ejection unit 200. The support unit 300 also includes a liquid supply member 330 formed with a flow path that supplies liquid to each liquid ejection unit 200 (four liquid ejection units 200 in this embodiment) via the support member 310. The support unit 300 also includes a reference member 340 that functions to position the liquid ejection device body, and a reference fixing member 350 that fixes the reference member 340 to the support member 310. The support member 310, frame member 320, and liquid supply member 330 are preferably made of the same material, taking into consideration the effects of thermal expansion, for example, during ink heating temperature control or environmental fluctuations. Alternatively, if different materials are used for the support member 310, frame member 320, and liquid supply member 330, it is preferable to select materials with linear expansion coefficients that are as similar as possible. This makes it possible to suppress deformation of the entire support unit during thermal expansion and the resulting deterioration in the positional accuracy of the ejection element substrate 210.

[0023] FIG. 11 is a plan view of a liquid ejection head in which the liquid ejection unit 200 is assembled to the support unit 300, as seen from the ejection surface side. FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. 11. FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG. 11. FIG. 14 is a cross-sectional view taken along line XIV-XIV in FIG. 11. FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG. 11, showing the liquid ejection unit 200 assembled to the support unit 300 and the various components assembled. As shown in FIGS. 12 to 14, the flow path member 240 and the liquid supply member 330 are joined to the support member 310, and the liquid flow paths are fluidly connected. The periphery of the ejection element substrate support member 230 is sealed with a peripheral sealing member 360 between the support member 230 and the frame member 320 to prevent liquid infiltration. The back surface of the ejection element substrate support member 230 (the surface opposite the ejection port surface) may be sealed with a back surface sealing member 370 for reinforcement. 11, the support member 310 has three holes for inserting the reference fixing member 350. The reference fixing member 350 is fixed to these holes, and the reference member 340 is fixed to the reference fixing member 350. The reference fixing member 350 may be an integral part of the support member 310.

[0024] FIG. 15 is a diagram showing the connection configuration of the liquid members between the support unit 300 and the liquid supply unit 500 of the liquid ejection head 100 according to this embodiment. FIG. 15(a) is a perspective view from above. FIG. 15(b) is a perspective view from below. The liquid supply unit 500 has a liquid connection portion 501 and is connected to the liquid supply portion 13 (FIG. 2) of the liquid ejection device main body. This allows liquid to be supplied from the supply system of the liquid ejection device main body to the liquid ejection head 100, and liquid that has passed through the liquid ejection head 100 is recovered to the supply system of the liquid ejection device main body. In this way, liquid can circulate through the paths of the liquid ejection device main body and the liquid ejection head 100. Inside the liquid supply unit 500, filters (not shown) are provided that communicate with each opening of the liquid connection portion 501 to remove foreign matter from the ink being supplied.

[0025] Figure 16 is a cross-sectional view of the fluid connection between liquid supply unit 500 and liquid supply member 330. Figure 16 is a cross-sectional view taken along XVI-XVI in Figure 15. Liquid that flows in from the liquid ejection device main body side through liquid connection part 501 passes through communication port 502 and is supplied to liquid supply member 330. The gap between liquid supply unit 500 and liquid supply member 330 is sealed by elastic member 503.

[0026] FIG. 17 is a diagram showing the connection structure of the liquid flow paths of the support unit 300. FIG. 18 is a diagram showing the connection structure of the liquid flow paths of the liquid ejection unit 200. The liquid supply unit 500 and the liquid supply member 330 in the support unit 300 are fluidly connected by a first communication port 331. A flow path for distributing liquid to each liquid ejection unit 200 is formed in the liquid supply member 330. In this example, a flow path for distributing liquid to four liquid ejection units 200 is formed in one liquid supply member 330. The liquid supply member 330 and the support member 310 are fluidly connected by a second communication port 311. The support member 310 and each liquid ejection unit 200 are fluidly connected by a third communication port 241 of the flow path member 240, as shown in FIG. 18. A liquid flow path 242 is formed in the flow path member 240. The flow path member 240 is fluidly connected to the ejection element substrate flow path member 220 via a fourth communication port 221. 19 is a diagram showing the fluid connection configuration within the ejection element substrate 210. The liquid that flows in from each fourth communication port 221 passes through a common flow path 222 and is supplied to the ejection element substrate 210, and is ejected from the ejection port 213 by the piezoelectric element 214, which is an ejection element.

[0027] FIG. 20 is a perspective view of a cooling unit 600 for cooling the drive circuit board 251. FIG. 21 is an exploded view of the cooling unit 600. FIG. 22 is a cross-sectional view taken along line XXII-XXII in FIG. 20. As described above, the drive circuit board 251 is disposed on the flexible wiring board 250 (see FIG. 5). FIG. 20 is a view showing the drive circuit board 251 covered by the cooling unit 600. As shown in FIG. 20, the cooling unit 600 has a refrigerant connector 611. The refrigerant connector 611 is connected to the refrigerant supply unit 14 (FIG. 2) of the liquid ejection device main body. This allows the refrigerant to be supplied from the refrigerant supply system of the liquid ejection device main body to the cooling unit 600, and the refrigerant that has passed through the cooling unit 600 is recovered to the refrigerant supply system of the liquid ejection device main body. In this way, the refrigerant can circulate through the paths of the liquid ejection device main body and the cooling unit 600. As shown in FIG. 21 , the refrigerant flowing in through the refrigerant connection portion 611 branches into refrigerant channels formed between the first refrigerant supply member 610 and the second refrigerant supply member 620. The second refrigerant supply member 620 and the cooling member 630 are fluidly connected via a seal member 670. The refrigerant that branches in the second refrigerant supply member 620 circulates in a refrigerant channel 631 formed between the cooling member 630 and the cover member 640 and flows back into the second refrigerant supply member 620. The refrigerant that flows back into the second refrigerant supply member 620 joins together in the refrigerant channel formed between the first refrigerant supply member 610 and the second refrigerant supply member 620 and flows out from the refrigerant connection portion 611. The second refrigerant supply member 620 and the cooling member 630 are fixed by a first fixing member 680. The cooling member 630 and the cover member 640 are fixed by a second fixing member 690.

[0028] The cooling unit 600 of this embodiment has four sets of cooling members 630 and lid members 640. The second refrigerant supply member 620 is separated into two cooling systems in the Y direction. Each cooling system is provided with two sets of cooling members 630 and lid members 640. These two sets are arranged opposite each other in the Y direction. In addition, a heat conduction member 650 is provided between these two sets in the Y direction, contacting the cooling members 630.

[0029] The cooling unit 600 of this embodiment is provided with four cooling members 630. In FIGS. 20 and 21 , the cooling members 630 to which a refrigerant is supplied from the second refrigerant supply member 620 branching off at the front left of the drawing are referred to as a first cooling member 630a and a second cooling member 630b, starting from the front left of the drawing. Hereinafter, when describing individual cooling members, they will be referred to as the first cooling member 630a and the second cooling member 630b, and when describing matters common to both, they will be simply referred to as the cooling member 630. Furthermore, the heat conduction member 650 in contact with the first cooling member 630a will be referred to as the first heat conduction member 650a. The heat conduction member 650 in contact with the second cooling member 630b opposite the first cooling member 630a will be referred to as the second heat conduction member 650b. In this manner, the first cooling member 630a and the second cooling member 630b are disposed opposite each other. 21, in cooling unit 600, elastic member 660 is disposed between first heat conduction member 650a and second heat conduction member 650b. As shown in Fig. 20, flexible wiring board 250 on which drive circuit board 251 is disposed is provided between heat conduction member 650 and elastic member 660, and heat conduction member 650 abuts drive circuit board 251 (see Figs. 20 and 22). Furthermore, first cooling member 630a and second cooling member 630b are each fixed by first fixing member 680 while being pressed against second refrigerant supply member 620.

[0030] In this way, by bringing cooling member 630 into contact with drive circuit board 251 with heat conduction member 650 sandwiched therebetween, heat generated during operation of drive circuit board 251 is transferred to the refrigerant in cooling member 630. To facilitate transfer of heat generated in drive circuit board 251, it is preferable to select a material with as high a thermal conductivity as possible for cooling member 630, such as aluminum. An elastic member 660 is provided between the two flexible wiring boards 250, which makes it possible to reliably bring heat conduction member 650 into close contact with drive circuit board 251.

[0031] As shown in FIG. 20 , two flexible wiring substrates 250, each having a drive circuit board 251, are arranged to extend in the −Z direction from one ejection element substrate 210. The two flexible wiring substrates 250 are arranged to face each other in a direction intersecting the ejection port array direction in which the ejection ports 213 are formed. More specifically, the two flexible wiring substrates 250 are arranged so that the drive circuit boards 251 face each other outward. A heat conduction member 650 abuts on the side of the flexible wiring substrate 250 on which the drive circuit board 251 is arranged (outside), and an elastic member 660 abuts on the side opposite to the side on which the drive circuit board 251 is arranged (inside). A cooling member 630 abuts on the outside of the heat conduction member 650 so as to sandwich the heat conduction member 650 therebetween. 22, in the opposing direction of the two flexible wiring substrates 250, a first cooling member 630a, a drive circuit board a: 251a, an elastic member 660, a drive circuit board b: 251b, and a second cooling member 630b are arranged in this order. This allows the drive circuit board 251 to be efficiently cooled. As shown in FIG. 20, in this embodiment, one cooling member 630 is configured to cool the drive circuit boards 251 of multiple ejection element substrates 210.

[0032] The flow of refrigerant in cooling member 630 will now be described with reference to Figure 26. Figure 26 is a see-through view of cooling member 630 in the Y direction from cover member 640. Here, drive circuit boards adjacent in the X direction are referred to as drive circuit board a (first drive circuit board) and drive circuit board c (second drive circuit board), respectively. The X direction is also referred to as the arrangement direction of the drive circuit boards. The refrigerant supplied from second refrigerant supply member 620 enters inlet 701 of cooling member 630. The refrigerant that has entered inlet 701 branches through the first refrigerant flow path and the second refrigerant flow path in the directions of arrows 710 and 711, respectively, and passes through the projection planes of drive circuit board a (first drive circuit board) 251a and drive circuit board c (second drive circuit board) 251c, thereby cooling each drive element by cooling member 630.

[0033] The coolant that passes through the projection portion of each drive element flows through the first coolant flow path and the second coolant flow path along arrows 712 and 713, respectively, into outlet 702, and is then discharged to the second coolant supply member 620. Because the coolant is supplied to the projection surface of each drive circuit board immediately after branching from inlet 701, the coolant temperature is approximately the same, allowing each drive element to be cooled equally. However, the amount of heat generated by each drive circuit board varies depending on the print duty of the ejection element board being driven, and is not necessarily always uniform. For example, suppose that the print duty of the first ejection element board is high and the print duty of the third ejection element board is controlled to be low depending on the image to be output. In this case, the heat generation amount of drive circuit board a (first drive circuit board) is large and the heat generation amount of drive circuit board c (second drive circuit board) is small, and because the cooling member 630 is shared, heat is conducted inside the cooling member from drive circuit board a (first drive circuit board) which generates a large amount of heat to drive circuit board c (second drive circuit board) which generates a small amount of heat, thereby distributing the cooling load for drive circuit boards with different heat generation amounts. Compared to when an independent heat sink is provided for each drive element, using a common cooling member makes it possible to reduce the peak temperature of drive elements which generate a large amount of heat.

[0034] It is preferable that the inlet 701 and the outlet 702 are arranged at the same height in the direction of gravity. This allows the drive circuit boards to face each other, and allows the cooling members 630 facing the common coolant supply member 620 to be arranged in the same shape. In the present invention, "the same height" means that they are essentially the same height, and some deviation is permissible as long as the effect is achieved.

[0035] From the viewpoint of cooling efficiency, it is preferable that the coolant introduced from the inlet flows through the coolant flow path in an upward direction relative to the direction of gravity and then flows toward the outlet.

[0036] The thermal conductive member 650 has the role of transferring heat from the drive circuit board 251 to the cooling member 630. For this reason, it is preferable that the thermal resistance of the thermal conductive member 650 is small, and therefore it is also preferable that the thickness of the thermal conductive member 650 is thin. Furthermore, in order to closely contact the cooling member 630 and the drive circuit board 251, it is preferable that the thermal conductive member 650 has elasticity. It is preferable that the thickness of the thermal conductive member 650 is 8 mm or less. In this embodiment, a heat dissipation sheet with an acrylic resin base and filler dispersed therein is arranged as the thermal conductive member 650, and has a thermal conductivity of 2 [W / mK] and a thickness of 1 mm.

[0037] In order to reliably press the drive circuit board 251 against the cooling member 630 even if the drive circuit board 251 is tilted, the thickness of the elastic member 660 is preferably at least greater than that of the heat conduction member 650. In particular, the elastic modulus (compression strength) of the elastic member 660 is preferably 0.01 [N / cm2] or more and approximately 1.0 [N / cm2] or less.

[0038] In this embodiment, the elastic member 660 is made of a foamed material based on ethylene-propylene rubber (EPDM), and has a thickness of 5 mm and a compressive strength of about 0.18 [N / cm 2 ].

[0039] The material of the elastic member 660 is not limited to the above-mentioned EPDM, but may be, for example, a rubber such as chlorinated butyl rubber or urethane rubber, or a member based on silicone or elastomer.

[0040] Furthermore, the heat conduction member 650 is not limited to the heat conduction sheet as described above. It may be a paste-like heat conduction grease instead of a sheet-like member. Furthermore, while it is preferable that the heat conduction member 650 is provided as described above, the heat conduction member 650 may not be provided.

[0041] The heat generated by the drive circuit board 251 in this embodiment is approximately 17 W. Four ejection element substrates 210 are mounted on one liquid ejection head 100 (as shown in FIG. 1, eight liquid ejection heads 100 are mounted on the liquid ejection device 10). Two flexible wiring boards 250 are connected to one ejection element substrate 210 and an electric wiring board 400, and a drive circuit board 251 is mounted on each flexible wiring board 250. Therefore, a total of eight drive circuit boards 251 are mounted on the liquid ejection head 100 in this embodiment. The temperature of the coolant from the cooling unit 600 when it is introduced into the head is 30°C, and the flow rate can be set to approximately 8 cc / min or more and 30 cc / min or less per drive circuit board 251. In other words, the flow rate of the coolant flowing through the coolant connection parts 611 throughout the entire liquid ejection head 100 is controlled to approximately 64 cc / min or more and 240 cc / min or less. This allows the temperature of the drive circuit board 251 to be maintained at 80°C or less, and more preferably at 60°C or less.

[0042] 23 is a cross-sectional view of the electrical connection portion between the liquid ejection device main body and the liquid ejection head 100. An electrical wiring board 400 inside the liquid ejection head 100 is provided with electrical connection terminals 402. The electrical connection terminals 402 are connected to the liquid ejection device electrical wiring section 12, thereby electrically connecting the liquid ejection device 10 and the liquid ejection head 100. The electrical connection terminals 402 are covered with an electrical connection section cover member 430 that can be opened and closed.

[0043] As described above, according to this embodiment, multiple drive elements are cooled evenly, and a common cooling member can be used for multiple drive elements, reducing the number of components and facilitating layout. Furthermore, since the number of inlets and outlets required is fewer than the number of drive elements, layout is facilitated without requiring the first refrigerant supply member 610 and the second refrigerant supply member 620 to have complex shapes. Therefore, complex layouts, such as staggered layouts of drive elements, can be easily accommodated. Furthermore, when the heat generation values ​​of multiple drive elements differ, the cooling load can be distributed, allowing for a reduction in peak temperature.

[0044] <<Other embodiments>> In the above-described embodiment, an example has been described in which one cooling member 630 cools the drive circuit boards 251 of different liquid discharge units 200. That is, an example has been described in which two opposing cooling members cool the drive circuit boards 251 of two liquid discharge units 200. However, this is not limiting. One cooling member 630 may be configured to cool the drive circuit board 251 of one liquid discharge unit 200. Furthermore, one cooling member 630 may be configured to cool the drive circuit boards 251 of three or more liquid discharge units 200.

[0045] In the above example, a flexible wiring board is used, which allows for a high degree of layout freedom, but a configuration without a flexible wiring board is also possible. Even in this case, it is sufficient if the driving elements can be cooled using the cooling member 630 on the driving circuit board 251.

[0046] In the above example, first refrigerant supply member 610, second refrigerant supply member 620, cooling member 630, and cover member 640 are formed as separate members and then combined together, but some or all of these members may be integrally molded using a 3D printer. This eliminates the need for sealing or fixing members when combining the members, thereby improving the effectiveness of preventing refrigerant leakage and providing a highly reliable cooling member.

[0047] The disclosure of the present embodiment includes configurations typified by the following liquid ejection head examples and liquid ejection device examples.

[0048] <Configuration 1> a cooling member configured to be in contact with the first drive circuit board and the second drive circuit board, respectively; an inlet for introducing a coolant from the outside, an outlet for discharging the coolant to the outside, a first coolant flow path connecting the inlet and the outlet and for cooling the first drive circuit board; and a second coolant flow path connecting the inlet and the outlet and for cooling the second drive circuit board, wherein the first coolant flow path and the second coolant flow path are arranged so as to sandwich the inlet between them.

[0049] <Configuration 2> 2. The liquid ejection head according to configuration 1, wherein the inlet and the outlet of the cooling member are disposed at the same height in the direction of gravity.

[0050] <Configuration 3> 3. The liquid ejection head according to configuration 1 or 2, further comprising a coolant supply member configured to supply a coolant to the cooling member.

[0051] <Configuration 4> 4. The liquid ejection head according to any one of configurations 1 to 3, wherein a heat conduction member is disposed so as to be sandwiched between the cooling member and the first drive circuit board.

[0052] <Configuration 5> 5. The liquid ejection head according to any one of configurations 1 to 4, wherein the plurality of liquid ejection units are arranged in a staggered pattern.

[0053] <Configuration 6> 6. The liquid ejection head according to configuration 5, wherein the cooling member cools a plurality of the liquid ejection units in one row among the plurality of the liquid ejection units arranged in the staggered pattern.

[0054] <Configuration 7> 7. A liquid ejection device comprising: the liquid ejection head according to any one of configurations 1 to 6; a liquid supply unit that supplies liquid to the liquid ejection head; and a coolant supply unit that supplies coolant to the liquid ejection head. [Explanation of symbols]

[0055] 100 Liquid ejection head 200 Liquid Dispensing Unit 210 ejection element substrate 213 Discharge port 214 Piezoelectric element 250a Flexible wiring board a 250b Flexible wiring boardb 251a Drive circuit board a 251b Drive circuit board b 251c Drive circuit board c 630a First cooling member 630b Second cooling member 701 Entrance 702 Exit 710 Flow from the inlet toward the projection surface of the driving element 251a 711 Flow from the inlet toward the projection surface of the driving element 251b 712 Flow from the projection surface of the driving element 251a toward the outlet 713 Flow from the projection surface of the driving element 251b toward the outlet

Claims

1. a first ejection element substrate and a second ejection element substrate each having an ejection element for ejecting liquid from an ejection port; a first drive circuit substrate provided with first drive elements for driving the ejection elements on the first ejection element substrate; a second drive circuit substrate provided with second drive elements for driving the ejection elements on the second ejection element substrate; A liquid ejection head including a liquid ejection unit having a cooling member configured to contact the first drive circuit board and the second drive circuit board, The cooling member is an inlet for introducing a refrigerant from the outside; an outlet for discharging the refrigerant to the outside; a first coolant flow path connecting the inlet and the outlet to cool the first drive circuit board; a second coolant flow path connecting the inlet and the outlet to cool the second drive circuit board; and The liquid ejection head is characterized in that the first coolant flow path and the second coolant flow path are arranged so as to sandwich the inlet.

2. 2. The liquid ejection head according to claim 1, wherein the inlet and the outlet of the cooling member are disposed at the same height in the direction of gravity.

3. The liquid ejection head according to claim 1 , further comprising a coolant supply member configured to supply a coolant to the cooling member.

4. 2. The liquid ejection head according to claim 1, wherein a heat conducting member is disposed so as to be sandwiched between the cooling member and the first drive circuit board.

5. The liquid ejection head according to claim 1 , wherein the plurality of liquid ejection units are arranged in a staggered pattern.

6. The liquid ejection head according to claim 5 , wherein the cooling member cools a plurality of the liquid ejection units in one row among the plurality of the liquid ejection units arranged in the staggered pattern.

7. The liquid ejection head according to claim 1; a liquid supply unit that supplies liquid to the liquid ejection head; a coolant supply unit that supplies a coolant to the liquid ejection head; A liquid ejection device comprising:

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