Liquid ejection device and cooling unit

Abstract

This invention provides a liquid ejection device and a cooling unit. The liquid ejection device includes: a head having an ejection portion that receives a drive signal and ejects liquid from a nozzle; a drive circuit connected to the head and generating the drive signal; and a cooling unit that cools the drive circuit. The cooling unit includes: a first heat-conducting component connected to a first portion of the drive circuit; a second heat-conducting component connected to a second portion of the drive circuit; a first flow path connecting the first heat-conducting component and the second heat-conducting component; and a control unit that controls the circulation of liquid circulating in the first flow path. If the heat generated by the first portion is greater than the heat generated by the second portion, a first control is performed to circulate the liquid in the first flow path in the order of the first heat-conducting component and the second heat-conducting component. If the heat generated by the second portion is greater than the heat generated by the first portion, a second control is performed to circulate the liquid in the first flow path in the order of the second heat-conducting component and the first heat-conducting component.

Description

Technical Field

[0001] This invention relates to a liquid ejection device and a cooling unit. Background Technology

[0002] To form high-resolution images, high ejection stability is essential. However, as the distance from the drive circuit transmitting the signal that forms the basis of the image data to the head increases, the influence of wiring on inductance may increase, leading to decreased ejection stability. Therefore, a technique described in Patent Document 1, which places the drive circuit directly above the head, is known.

[0003] In such printing apparatuses, the driving circuits reach extremely high temperatures due to the dense arrangement of electronic components such as integrated circuits, FETs, and coils within a limited space at the top of the printing head. Therefore, cooling mechanisms are typically installed. However, air cooling directly above the printing head can potentially affect the landing position of the ink ejected from the nozzles. Furthermore, ink mist floating directly above the printing head can adhere to electronic components due to the Lenard effect and other factors, potentially causing short circuits.

[0004] In the case of water cooling, a technology described in Patent Document 2 is known in which heated electronic components are arranged sequentially from the upstream of the flow path.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-138356

[0006] Patent Document 2: Japanese Patent Application Publication No. 2003-121039

[0007] The technology described in Patent Document 2 has a problem with cooling efficiency. For example, which electronic component gets hotter sometimes varies depending on the image data to be printed. Therefore, even if the order of the hottest electronic components is predetermined and the electronic components are arranged in this order, the cooling efficiency will decrease depending on the image data to be printed. Summary of the Invention

[0008] To solve the above-mentioned technical problems, a liquid ejection device according to one aspect of this disclosure includes: a head having an ejection portion that receives a drive signal and ejects liquid from a nozzle disposed on a nozzle surface; a drive circuit connected to the head and generating a drive signal; and a cooling unit for cooling the drive circuit, the cooling unit including: a first heat-conducting component connected to a first portion of the drive circuit; a second heat-conducting component connected to a second portion of the drive circuit; a first flow path connecting the first heat-conducting component and the second heat-conducting component; and a control unit for controlling the circulation of liquid circulating in the first flow path. When the heat generated by the first portion is greater than the heat generated by the second portion, the control unit performs a first control to circulate the liquid in the first flow path in the order of the first heat-conducting component and the second heat-conducting component; when the heat generated by the second portion is greater than the heat generated by the first portion, the control unit performs a second control to circulate the liquid in the first flow path in the order of the second heat-conducting component and the first heat-conducting component.

[0009] Furthermore, one aspect of the present disclosure provides a cooling unit for cooling a drive circuit of a liquid ejection device, the liquid ejection device comprising: a head having an ejection portion that receives a drive signal and ejects liquid from a nozzle disposed on a nozzle surface; and a drive circuit connected to the head and generating a drive signal. The cooling unit comprises: a first heat-conducting component connected to a first portion of the drive circuit; a second heat-conducting component connected to a second portion of the drive circuit; a first flow path connecting the first heat-conducting component and the second heat-conducting component; and a control unit that controls the circulation of liquid circulating in the first flow path. If the heat generated by the first portion is greater than the heat generated by the second portion, the control unit performs a first control to circulate the liquid in the first flow path in the order of the first heat-conducting component and the second heat-conducting component. If the heat generated by the second portion is greater than the heat generated by the first portion, the control unit performs a second control to circulate the liquid in the first flow path in the order of the second heat-conducting component and the first heat-conducting component. Attached Figure Description

[0010] Figure 1 This is a diagram showing the simplified structure of a liquid ejection device.

[0011] Figure 2 This is a diagram showing the simplified structure of the ejection unit.

[0012] Figure 3 This is a diagram showing an example of the signal waveforms of the drive signals COMA, COMB, and COMC.

[0013] Figure 4This is a diagram illustrating the functional structure of the drive signal selection circuit.

[0014] Figure 5 This is a diagram representing an example of the decoded content in the decoder.

[0015] Figure 6 This is a diagram illustrating an example of the configuration of a selection circuit.

[0016] Figure 7 This is a diagram used to illustrate the operation of the drive signal selection circuit.

[0017] Figure 8 This is a diagram showing the structure of the liquid ejection module.

[0018] Figure 9 This is a diagram illustrating an example of the structure of an ejection module.

[0019] Figure 10 It is along Figure 9 The cross-sectional view shown is taken when the ejection module is cut along line Aa.

[0020] Figure 11 This is a perspective view showing the appearance of the head drive module according to the first embodiment of this disclosure.

[0021] Figure 12 This is a perspective view showing the appearance of the head drive module 10 in the state of being mounted with a frame, according to the first embodiment of this disclosure.

[0022] Figure 13 This is a diagram illustrating the configuration of the drive signal output circuit according to the first embodiment of this disclosure.

[0023] Figure 14 This is a perspective view showing the configuration of a drive circuit board that stands upright relative to a substrate according to the first embodiment of this disclosure.

[0024] Figure 15 This is a bottom view showing the configuration of the drive circuit board that stands upright relative to the substrate according to the first embodiment of this disclosure.

[0025] Figure 16 This is a perspective view showing the configuration of the plurality of ejection units according to the first embodiment of this disclosure.

[0026] Figure 17 This is a top view showing the configuration of the plurality of ejection units according to the first embodiment of this disclosure.

[0027] Figure 18 This diagram illustrates the configuration of the terminals of the connector according to the first embodiment of this disclosure.

[0028] Figure 19This is a perspective view showing the configuration of the cooling unit according to the second embodiment of this disclosure.

[0029] Figure 20 This is a perspective view of the cooling unit according to the second embodiment of this disclosure, installed in the drive signal output circuit.

[0030] Figure 21 This is a perspective view showing the configuration of a drive circuit board with a heat-conducting sheet according to the second embodiment of this disclosure.

[0031] Figure 22 This is a perspective view showing the state in which the heat sink section according to the second embodiment of this disclosure is connected to the drive circuit board.

[0032] Figure 23 This is a perspective view showing the shape of the heat sink portion as viewed from the surface according to the second embodiment of this disclosure.

[0033] Figure 24 This is a perspective view showing the shape of the heat sink portion as viewed from the rear according to the second embodiment of this disclosure.

[0034] Figure 25 This is a perspective view showing the configuration of the head drive module in the state of having a cooling unit and a frame installed according to the second embodiment of this disclosure.

[0035] Figure 26 This is a perspective view showing the configuration of the head drive module according to the second embodiment of this disclosure, in a state where a cooling unit, a frame, and an air guide are installed.

[0036] Figure 27 This is a diagram illustrating the control of liquid circulation according to the second embodiment of this disclosure.

[0037] Figure 28 This is a schematic diagram illustrating the cooling of the plurality of head units according to the second embodiment of this disclosure.

[0038] Figure 29 This is a diagram illustrating an example of the overall configuration of the cooling unit according to the second embodiment of this disclosure.

[0039] Explanation of reference numerals in the attached figures

[0040] 1…Liquid ejection device, 2…Control unit, 3…Liquid container, 4…Conveying unit, 5…Ejection unit, 10…Head drive module, 20…Liquid ejection module, 23…Ejection module, 30…Wiring components, 31…Housing, 33…Assembly substrate, 34…Flow path structure, 35…Head substrate, 37…Distribution flow path, 39…Fixing plate, 41…Conveyor motor, 42…Conveyor roller, 50…Drive signal output circuit, 52, 52a, 52b, 52c…Drive circuit, 53…Reference voltage output circuit, 60…Piezoelectric element, 100…Control circuit, 120…Conversion circuit, 200…Drive signal selection circuit, 201…Integrated circuit, 210…Selection control circuit, 212…Shift register, 214… Latch circuit, 216…decoder, 220…restore circuit, 230…selection circuit, 232a, 232b, 232c…inverter, 234a, 234b, 234c…transmission gate, 311, 351, 371, 391…opening, 313…substrate insertion part, 315…holding member, 330…connection part, 341, 373…inlet part, 343, 643…through hole, 352, 353, 355…cutout part, 388…wiring component, 521a, 521b, 521c…coil, 522a, 522b, 522c…field-effect transistor, 523a, 523b, 523c…integrated circuit, 600…ejector, 610…vibrating plate, 611…lead wire Electrode, 620… Plastic substrate, 621… Sealing film, 622… Fixing substrate, 623… Nozzle plate, 623a… Liquid jet surface, 630… Connecting plate, 641… Protective substrate, 642… Flow path forming substrate, 644… Protective space, 660… Housing, 661… Inlet channel, 662… Connection port, 665… Recess, Adp… Trapezoidal waveform, B1… Base substrate, B2… Conversion circuit substrate, BSD… Micro-vibration, C1… Control unit, CB, CB1, CB2… Pressure chamber, CN1… First connector on the drive circuit unit side, CN2… Second connector on the drive circuit unit side, CN3… Connecting connector, DRB, DRB1, DRB2, DRB3, DRB4, DRB5, D… RB6…Driver circuit board, DRV, DRV1, DRV2, DRV3, DRV4, DRV5, DRV6…Drive signal output circuit, F1, F2…Flow path, FC…Wiring components, H1…Air guide hole, H2…Air guide hole, HD…Frame, HD1, HD2, HD3…Head unit, HM1, HM2, HM3…Head drive module, HS, HS1, HS2, HS3, HS4, HS5, HS6…Heat sink, HU1, HU2, HU3, HU4…Ejection unit, Ln1, Ln2…Nozzle array, MN, MN1, MN2…Manifold, N, N1, N2…Nozzle, P…Dielectric, P1…COMA terminal, P2…COMB terminal, P3…VBS terminal,P4…COMC terminal, PM1…pump, RD1…cooler, RA, RA1, RA2, RB, RB1, RB2…supply connection channel, RK1, RK2…pressure chamber connection channel, RR, RR1, RR2…nozzle connection channel, RX, RX1, RX2…connection connection channel, Sd…small dot, Su1, Su2…flow path plate, TS1…heat conduction plate, U1…cooling unit, WR…air guide section, WT1…water storage section. Detailed Implementation

[0041] The preferred embodiments of this disclosure will now be described using the accompanying drawings. The drawings are provided for ease of explanation. It should be noted that the embodiments described below do not unduly limit the scope of this disclosure as defined in the claims. Furthermore, not all of the components described below are essential elements of this disclosure.

[0042] 1. First Implementation Method

[0043] 1.1 Composition of the liquid ejection device

[0044] Figure 1 This is a diagram showing a simplified configuration of the liquid ejection device 1. (See diagram below.) Figure 1 As shown, the liquid ejection device 1 is a so-called line inkjet printer, which forms a desired image on the medium P by ejecting ink, such as a liquid, onto the medium P conveyed by the transport unit 4 at a desired timing. Here, in the following description, the direction in which the medium P is transported is sometimes referred to as the transport direction, and the width direction of the transported medium P is referred to as the main scanning direction.

[0045] like Figure 1 As shown, the liquid ejection device 1 includes a control unit 2, a liquid container 3, a conveying unit 4, and multiple ejection units 5.

[0046] The control unit 2 includes processing circuits such as a CPU (Central Processing Unit) and an FPGA (Field Programmable Gate Array), and storage circuits such as semiconductor memory. Based on image data supplied from an external device such as a host computer (not shown) located outside the liquid ejection device 1, the control unit 2 outputs signals to control various elements of the liquid ejection device 1.

[0047] Liquid container 3 stores one or more liquids that are supplied to ejection unit 5. Specifically, liquid container 3 stores inks of various colors that are ejected to medium P, such as black, cyan, magenta, yellow, red, and gray inks. Of course, it may store only black ink, or it may store liquids other than inks.

[0048] The conveying unit 4 includes a conveying motor 41 and a conveying roller 42. A conveying control signal Ctrl-T, output by the control unit 2, is input to the conveying unit 4. The conveying motor 41 then operates based on the input conveying control signal Ctrl-T, driving the conveying roller 42 to rotate, thereby conveying the medium P along the conveying direction.

[0049] Multiple ejection units 5 each have a head drive module 10 and a liquid ejection module 20. The ejection unit 5 is input with an image information signal IP output from the control unit 2 and is supplied with ink stored in the liquid container 3. Thus, the head drive module 10 controls the operation of the liquid ejection module 20 based on the image information signal IP input from the control unit 2. According to the control of the head drive module 10, the liquid ejection module 20 ejects the ink supplied from the liquid container 3 to the medium P.

[0050] Furthermore, the liquid ejection modules 20 of each of the multiple ejection units 5 are arranged and positioned along the main scanning direction to be wider than the width of the medium P, enabling ink to be ejected into the entire area in the width direction of the transported medium P. Thus, the liquid ejection device 1 constitutes a line inkjet printer. It should be noted that the liquid ejection device 1 is not limited to a line inkjet printer.

[0051] Next, a brief description of the structure of the ejection unit 5 will be given. Figure 2 This is a diagram showing a simplified configuration of the ejection unit 5. (See diagram for example.) Figure 2 As shown, the ejection unit 5 has a head drive module 10 and a liquid ejection module 20. Furthermore, in the ejection unit 5, the head drive module 10 and the liquid ejection module 20 are electrically connected by one or more wiring components 30.

[0052] The wiring component 30 is a flexible component, such as a flexible printed circuit (FPC), used to electrically connect the head drive module 10 and the liquid ejection module 20.

[0053] The head drive module 10 includes a control circuit 100, drive signal output circuits 50-1 to 50-m, and a conversion circuit 120.

[0054] The control circuit 100 includes a CPU, FPGA, etc. The control circuit 100 receives the image information signal IP output from the control unit 2. Based on the input image information signal IP, the control circuit 100 outputs signals controlling various elements of the ejection unit 5.

[0055] The control circuit 100 generates a basic data signal dDATA based on the image information signal IP to control the operation of the liquid ejection module 20, and outputs it to the conversion circuit 120. The conversion circuit 120 converts the basic data signal dDATA into a differential signal such as LVDS (Low Voltage Differential Signaling), and outputs it as the data signal DATA to the liquid ejection module 20. It should be noted that the conversion circuit 120 can also convert the basic data signal dDATA into a differential signal using a high-speed transmission method other than LVDS, such as LVPECL (Low Voltage Positive Emitter Coupled Logic) or CML (Current Mode Logic), and output it as the data signal DATA to the liquid ejection module 20. Alternatively, it can output part or all of the basic data signal dDATA as a single-ended data signal DATA to the liquid ejection module 20.

[0056] Additionally, the control circuit 100 outputs basic drive signals dA1, dB1, and dB1 to the drive signal output circuit 50-1. The drive signal output circuit 50-1 includes drive circuits 52a, 52b, and 52c. The basic drive signal dA1 is input to drive circuit 52a. Drive circuit 52a generates drive signal COMA1 by performing a digital-to-analog conversion on the input basic drive signal dA1 and then amplifying it in Class D, and outputs it to the liquid ejection module 20. The basic drive signal dB1 is input to drive circuit 52b. Drive circuit 52b generates drive signal COMB1 by performing a digital-to-analog conversion on the input basic drive signal dB1 and then amplifying it in Class D, and outputs it to the liquid ejection module 20. The basic drive signal dB1 is input to drive circuit 52c. Drive circuit 52c generates drive signal COMC1 by performing a digital-to-analog conversion on the input basic drive signal dB1 and then amplifying it in Class D, and outputs it to the liquid ejection module 20.

[0057] Here, each of the drive circuits 52a, 52b, and 52c only needs to amplify the waveforms defined by the input basic drive signals dA1, dB1, and dC1 to generate drive signals COMA1, COMB1, and COMC1. They can replace Class D amplifier circuits, or include Class A, Class B, or Class AB amplifier circuits in addition to Class D. Furthermore, each of the basic drive signals dA1, dB1, and dC1 only needs to define the waveforms of the corresponding drive signals COMA1, COMB1, and COMC1; these can also be analog signals.

[0058] Additionally, the drive signal output circuit 50-1 includes a reference voltage output circuit 53. The reference voltage output circuit 53 generates a reference voltage signal VBS1 representing a reference potential of the piezoelectric element 60 (described later) in the liquid ejection module 20, and outputs it to the liquid ejection module 20. This reference voltage signal VBS1 can be, for example, ground potential, or a fixed potential such as 5.5V or 6V. Here, "fixed potential" includes a case where variations caused by errors, such as potential variations due to the operation of peripheral circuits, potential variations due to deviations in circuit components, and potential variations due to the temperature characteristics of circuit components, are considered approximately constant.

[0059] The drive signal output circuits 50-2 to 50-m differ only in the input and output signals; their configuration is identical to that of drive signal output circuit 50-1. Specifically, drive signal output circuit 50-j (j being any one of 1 to m) includes circuits equivalent to drive circuits 52a, 52b, and 52c, and a circuit equivalent to reference voltage output circuit 53. Based on the basic drive signals dAj, dBj, and dCj input from control circuit 100, it generates drive signals COMAj, COMBj, and COMCj, and a reference voltage signal VBSj, which are then output to the liquid ejection module 20.

[0060] In the following description, the drive circuits 52a, 52b, and 52c included in the drive signal output circuit 50-1 have the same configuration as the drive circuits 52a, 52b, and 52c included in the drive signal output circuit 50-j, and are sometimes simply referred to as drive circuit 52 when no distinction is needed. In this case, the description will focus on drive circuit 52 generating and outputting drive signal COM based on the basic drive signal do. On the other hand, when distinguishing between the drive circuits 52a, 52b, and 52c included in the drive signal output circuit 50-1 and the drive circuits 52a, 52b, and 52c included in the drive signal output circuit 50-j, the drive circuits 52a, 52b, and 52c included in the drive signal output circuit 50-1 are sometimes referred to as drive circuits 52a1, 52b1, and 52c1, and the drive circuits 52a, 52b, and 52c included in the drive signal output circuit 50-j are sometimes referred to as drive circuits 52aj, 52bj, and 52cj.

[0061] The liquid ejection module 20 has a recovery circuit 220 and ejection modules 23-1 to 23-m.

[0062] The restoration circuit 220 restores the data signal DATA into a single-ended signal and separates it into signals corresponding to the ejection modules 23-1 to 23-m, and outputs them to the corresponding ejection modules 23-1 to 23-m.

[0063] Specifically, the restoration circuit 220 restores and separates the data signal DATA to generate a clock signal SCK1, a printing data signal SI1, and a latch signal LAT1 corresponding to the ejection module 23-1, and outputs them to the ejection module 23-1. Additionally, the restoration circuit 220 restores and separates the data signal DATA to generate a clock signal SCKj, a printing data signal SIj, and a latch signal LATj corresponding to the ejection module 23-j, and outputs them to the ejection module 23-j.

[0064] As described above, the restoration circuit 220 restores the data signal DATA of the differential signal output by the head drive module 10, and separates the restored signal into signals corresponding to the ejection modules 23-1 to 23-m. Thus, the restoration circuit 220 generates clock signals SCK1 to SCKm, printing data signals SI1 to SIm, and latch signals LAT1 to LATm corresponding to each of the ejection modules 23-1 to 23-m, and outputs them to the corresponding ejection modules 23-1 to 23-m. It should be noted that any one of the clock signals SCK1 to SCKm, printing data signals SI1 to SIm, and latch signals LAT1 to LATm output by the restoration circuit 220 corresponding to each of the ejection modules 23-1 to 23-m can also be a signal shared by all of the ejection modules 23-1 to 23-m.

[0065] Here, given that the restoration circuit 220 generates clock signals SCK1~SCKm, printing data signals SI1~SIm, and latch signals LAT1~LATm by restoring and separating the data signal DATA, the data signal DATA output by the control circuit 100 is a differential signal corresponding to the clock signals SCK1~SCKm, printing data signals SI1~SIm, and latch signals LAT1~LATm. Furthermore, the basic data signal dDATA, which forms the basis of the data signal DATA, includes signals corresponding to each of the clock signals SCK1~SCKm, printing data signals SI1~SIm, and latch signals LAT1~LATm. That is, the basic data signal dDATA includes signals that control the operation of the ejection modules 23-1~23-m of the liquid ejection module 20.

[0066] The ejection module 23-1 has a drive signal selection circuit 200 and a plurality of ejection sections 600. In addition, each of the plurality of ejection sections 600 includes a piezoelectric element 60.

[0067] The ejection module 23-1 is input with drive signals COMA1, COMB1, COMC1, a reference voltage signal VBS1, a clock signal SCK1, a printing data signal SI1, and a latch signal LAT1. These drive signals COMA1, COMB1, COMC1, SCK1, SI1, and LAT1 are input to the drive signal selection circuit 200 of the ejection module 23-1. Based on the input clock signal SCK1, SI1, and LAT1, the drive signal selection circuit 200 selects or deselects drive signals COMA1, COMB1, and COMC1 to generate a drive signal VOUT, which is then supplied to one end of the piezoelectric element 60 of the corresponding ejection section 600. At the same time, the reference voltage signal VBS1 is supplied to the other end of the piezoelectric element 60. Therefore, the piezoelectric element 60 is driven by the potential difference between the drive signal VOUT supplied to one end and the reference voltage signal VBS1 supplied to the other end, thereby ejecting ink from the corresponding ejection section 600.

[0068] Similarly, the ejection module 23-j has a drive signal selection circuit 200 and a plurality of ejection sections 600. In addition, each of the plurality of ejection sections 600 includes a piezoelectric element 60.

[0069] The ejection module 23-j is input with drive signals COMAj, COMBj, COMCj, a reference voltage signal VBSj, a clock signal SCKj, a printing data signal SIj, and a latch signal LATj. These drive signals COMAj, COMBj, COMCj, SCKj, SIj, and LATj are input to the drive signal selection circuit 200 of the ejection module 23-j. Based on the input clock signal SCKj, SIj, and LATj, the drive signal selection circuit 200 selects or deselects the drive signals COMAj, COMBj, and COMCj to generate a drive signal VOUT, which is then supplied to one end of the piezoelectric element 60 of the corresponding ejection section 600. At the same time, the reference voltage signal VBSj is supplied to the other end of the piezoelectric element 60. Therefore, the piezoelectric element 60 is driven by the potential difference between the drive signal VOUT supplied to one end and the reference voltage signal VBSj supplied to the other end, thereby ejecting ink from the corresponding ejection section 600.

[0070] In the liquid ejection device 1 of the first embodiment configured as described above, the control unit 2 controls the transport unit 4 to transport the medium P based on image data supplied by a host computer or the like (not shown), and controls the ejection of ink from the liquid ejection module 20 of the ejection unit 5. Thus, the liquid ejection device 1 can cause a desired amount of ink to land at a desired position on the medium P, forming a desired image on the medium P.

[0071] Here, the ejection modules 23-1 to 23-m of the liquid ejection module 20 are identical in configuration, differing only in the input signals. Therefore, in the following description, unless it is necessary to distinguish between ejection modules 23-1 to 23-m, they will sometimes be simply referred to as ejection module 23. Furthermore, in this case, the drive signals COMA1 to COMAm input to the ejection module 23 will sometimes be referred to as drive signals COMA, drive signals COMB1 to COMBm as drive signals COMB, drive signals COMC1 to COMCm as drive signals COMC, reference voltage signals VBS1 to VBSm as reference voltage signals VBS, clock signals SCK1 to SCKm as clock signals SCK, printing data signals SI1 to SIm as printing data signals SI, and latch signals LAT1 to LATm as latch signals LAT.

[0072] That is, the ejection module 23 is input with drive signals COMA, COMB, COMC, a reference voltage signal VBS, a clock signal SCK, a printing data signal SI, and a latch signal LAT. The drive signals COMA, COMB, COMC, SCK, SI, and LAT are input to the drive signal selection circuit 200 of the ejection module 23. Based on the input clock signal SCK, SI, and LAT, the drive signal selection circuit 200 selects or deselects the drive signals COMA, COMB, and COMC to generate a drive signal VOUT, which is then supplied to one end of the piezoelectric element 60 of the corresponding ejection section 600. At this time, the other end of the piezoelectric element 60 is supplied with the reference voltage signal VBS. Thus, the piezoelectric element 60 is driven by the potential difference between the drive signal VOUT supplied to one end and the reference voltage signal VBS supplied to the other end, thereby ejecting ink from the corresponding ejection section 600.

[0073] In summary, the liquid ejection device 1 in this embodiment includes: a liquid ejection module 20, including an ejection module 23 that ejects ink in response to the drive of a piezoelectric element 60; a head drive module 10, including drive signal output circuits 50-1 to 50-m that output drive signals COMA, COMB, and COMC; and a wiring component 30, one end of which is electrically connected to the head drive module 10 and the other end of which is electrically connected to the liquid ejection module 20. Here, the piezoelectric element 60 is an example of a drive element, the ejection module 23 that ejects ink in response to the drive of the piezoelectric element 60 or the liquid ejection module 20 including the ejection module 23 is an example of an ejection head, and any one of the drive signal output circuits 50-1 to 50-m that output drive signals COMA, COMB, and COMC or the head drive module 10 including the drive signal output circuits 50-1 to 50-m is an example of a head drive circuit.

[0074] 1.2 Functional Composition of the Drive Signal Selection Circuit

[0075] Next, the configuration and operation of the drive signal selection circuit 200 of the ejection module 23 will be explained. When explaining the configuration and operation of the drive signal selection circuit 200 of the ejection module 23, an example of the signal waveforms included in the drive signals COMA, COMB, and COMC input to the drive signal selection circuit 200 will first be explained.

[0076] Figure 3 This is a diagram illustrating an example of the signal waveforms for the drive signals COMA, COMB, and COMC. (Example...) Figure 3 As shown, the drive signal COMA includes a trapezoidal waveform Adp arranged in period T from the rise of the latch signal LAT to the next rise of the latch signal LAT. The trapezoidal waveform Adp is a signal waveform that causes a predetermined amount of ink to be ejected from the ejection section 600 corresponding to the piezoelectric element 60 when supplied to one end of the piezoelectric element 60. The drive signal COMB includes a trapezoidal waveform Bdp arranged in period T. This trapezoidal waveform Bdp is a signal waveform with a voltage amplitude smaller than that of the trapezoidal waveform Adp, and is a signal waveform that causes a less than predetermined amount of ink to be ejected from the ejection section 600 corresponding to the piezoelectric element 60 when supplied to one end of the piezoelectric element 60. The drive signal COMC includes a trapezoidal waveform Cdp arranged in period T. This trapezoidal waveform Cdp is a signal waveform with a voltage amplitude smaller than that of the trapezoidal waveforms Adp and Bdp, and is a signal waveform that causes ink near the nozzle opening to vibrate to a degree that prevents ink from being ejected from the ejection section 600 corresponding to the piezoelectric element 60 when supplied to one end of the piezoelectric element 60. The trapezoidal waveform Cdp is supplied to the piezoelectric element 60, causing the ink near the nozzle opening of the ejection section 600, which includes the piezoelectric element 60, to vibrate. As a result, the possibility of increased viscosity of the ink near the nozzle opening is reduced.

[0077] That is, the drive signal COMA is the signal that drives the piezoelectric element 60 to eject ink, the drive signal COMB is the signal that drives the piezoelectric element 60 to eject ink, and the drive signal COMC is the signal that drives the piezoelectric element 60 to not eject ink. The amount of ink ejected from the liquid ejection module 20 including the ejection module 23 when the drive signal COMA is supplied to the piezoelectric element 60 is different from the amount of ink ejected from the liquid ejection module 20 including the ejection module 23 when the drive signal COMB is supplied to the piezoelectric element 60.

[0078] Furthermore, at the start and end timings of the trapezoidal waveforms Adp, Bdp, and Cdp, the voltage values ​​of the trapezoidal waveforms Adp, Bdp, and Cdp are all the same voltage Vc. That is, the trapezoidal waveforms Adp, Bdp, and Cdp are signal waveforms that begin and end with voltage Vc, respectively.

[0079] In the following description, the amount of ink ejected from the ejection section 600 corresponding to the piezoelectric element 60 when a trapezoidal waveform Adp is supplied to one end of the piezoelectric element 60 is sometimes referred to as a large amount, and the amount of ink ejected from the ejection section 600 corresponding to the piezoelectric element 60 when a trapezoidal waveform Bdp is supplied to one end of the piezoelectric element 60 is sometimes referred to as a small amount. Furthermore, when a trapezoidal waveform Cdp is supplied to one end of the piezoelectric element 60, the ink near the nozzle opening vibrates to a degree that prevents it from being ejected from the ejection section 600 corresponding to the piezoelectric element 60, this is sometimes referred to as micro-vibration.

[0080] It should be noted that, in Figure 3 The example illustrates a scenario where each of the drive signals COMA, COMB, and COMC contains a trapezoidal waveform within a period T. However, each of these drive signals can also contain two or more consecutive trapezoidal waveforms within a period T. In this case, the drive signal selection circuit 200 is input with a signal specifying the switching timing of two or more trapezoidal waveforms, and the ejection unit 600 ejects ink multiple times within the period T. Thus, by causing the ink ejected multiple times within the period T to land on and bind to the medium P, a dot is formed on the medium P. This increases the grayscale level of the dot formed on the medium P.

[0081] In contrast, in the liquid ejection device 1 shown in the first embodiment, the driving signals COMA, COMB, and COMC are described as signals containing a trapezoidal waveform within a period T. This shortens the period T for forming dots on the medium P, enabling a faster image formation speed for forming images on the medium P. Furthermore, by supplying the driving signals COMA, COMB, and COMC in parallel to the liquid ejection module 20, the grayscale level of the dots formed on the medium P is also increased. Here, the period T from the rise of the latch signal LAT to the next rise of the latch signal LAT is sometimes referred to as the dot formation period for forming dots of the desired size on the medium P.

[0082] It should be noted that the signal waveforms included in the drive signals COMA, COMB, and COMC are not limited to... Figure 3 The signal waveforms illustrated herein can be varied depending on the type of ink ejected from the ejection section 600, the number of piezoelectric elements 60 driven by the drive signals COMA, COMB, and COMC, and the length of the wiring transmitting the drive signals COMA, COMB, and COMC. That is, Figure 2 The drive signals COMA1 to COMAm shown can each include different signal waveforms. Similarly, the drive signals COMB1 to COMBm and the drive signals COMC1 to COMCm can each include different signal waveforms.

[0083] Next, the configuration and operation of the drive signal selection circuit 200, which outputs the drive signal VOUT by selecting or not selecting the drive signals COMA, COMB, and COMC respectively, will be explained. Figure 4 This is a diagram illustrating the functional configuration of the drive signal selection circuit 200. (Example) Figure 4 As shown, the drive signal selection circuit 200 includes a selection control circuit 210 and multiple selection circuits 230.

[0084] The selection control circuit 210 receives the printing data signal SI, the latch signal LAT, and the clock signal SCK as inputs. Furthermore, the selection control circuit 210 has a group of shift registers (S / R) 212, latch circuits 214, and decoders 216 corresponding to each of the n ejector sections 600. That is, the drive signal selection circuit 200 includes the same number of shift registers 212, latch circuits 214, and decoders 216 as the number of ejector sections 600.

[0085] The printing data signal SI is a signal synchronized with the clock signal SCK, comprising 2 bits of printing data [SIH, SIL]. This 2-bit printing data [SIH, SIL] is used to specify the dot size formed by the ink ejected from each of the n ejector sections 600, using any one of "Large Dot LD", "Small Dot SD", "No Ejection ND", and "Micro Vibration BSD". The printing data signal SI is maintained in shift register 212 corresponding to the ejector section 600 in 2-bit increments of printing data [SIH, SIL].

[0086] Specifically, n shift registers 212 corresponding to the ejector section 600 are cascaded together. The serially input printing data signal SI is sequentially transmitted to the subsequent stage of the cascaded shift registers 212 according to the clock signal SCK. Then, by stopping the supply of the clock signal SCK, two bits of printing data [SIH, SIL] corresponding to the ejector section 600 of that shift register 212 are held in the n shift registers 212. It should be noted that... Figure 4 In order to distinguish the cascaded n shift registers 212, they are recorded as level 1, level 2, ..., level n from the upstream side to the downstream side of the input printed data signal SI.

[0087] Each of the n latching circuits 214 latches together the 2 bits of printed data [SIH, SIL] held by the corresponding shift register 212 at the rising edge of the latch signal LAT.

[0088] Each of the n decoders 216 decodes the 2-bit printed data [SIH, SIL] latched by the corresponding latch circuit 214, and outputs selection signals S1, S2, and S3 corresponding to the logic level of the decoded content in each cycle T. Figure 5 This is a diagram illustrating an example of the decoded content in decoder 216. Decoder 216 outputs latched 2-bit printed data [SIH, SIL] and... Figure 5 The selected signals S1, S2, and S3 specify the logic levels of the decoded content. For example, in the first embodiment, when the 2-bit printed data [SIH, SIL] latched by the corresponding latch circuit 214 is [1, 0], the decoder 216 sets the logic levels of the selected signals S1, S2, and S3 to L, H, and L levels respectively during the period T.

[0089] Each of the n ejector sections 600 is provided with a corresponding selection circuit 230. That is, the drive signal selection circuit 200 has n selection circuits 230. The selection signals S1, S2, S3 and the drive signals COMA, COMB, COMC, output by the decoder 216 corresponding to the same ejector section 600 are input to the selection circuit 230. Then, the selection circuit 230 generates a drive signal VOUT and outputs it to the corresponding ejector section 600 by selecting or deselecting the drive signals COMA, COMB, COMC based on the selection signals S1, S2, S3 and the drive signals COMA, COMB, COMC.

[0090] Figure 6 This diagram illustrates an example of the configuration of a selection circuit 230 corresponding to an ejector section 600. For example... Figure 6 As shown, the selection circuit 230 has inverters 232a, 232b, 232c and transmission gates 234a, 234b, 234c.

[0091] The selection signal S1 is input to the positive control terminal of transmission gate 234a (not marked with a circle), while it is logically inverted by inverter 232a and input to the negative control terminal of transmission gate 234a (marked with a circle). Additionally, a drive signal COMA is supplied to the input terminal of transmission gate 234a. When the input selection signal S1 is at a high level (H), transmission gate 234a conducts between its input and output terminals; when the input selection signal S1 is at a low level (L), it de-conducts between the input and output terminals. That is, transmission gate 234a outputs the drive signal COMA to the output terminal when the selection signal S1 is at a high level (H), and does not output the drive signal COMA to the output terminal when the selection signal S1 is at a low level (L).

[0092] The selection signal S2 is input to the positive control terminal of transmission gate 234b (not marked with a circle), while it is logically inverted by inverter 232b and input to the negative control terminal of transmission gate 234b (marked with a circle). Additionally, a drive signal COMB is supplied to the input terminal of transmission gate 234b. When the input selection signal S2 is at a high level (H), transmission gate 234b conducts between its input and output terminals; when the input selection signal S2 is at a low level (L), it de-conducts between the input and output terminals. That is, transmission gate 234b outputs the drive signal COMB to its output terminal when the selection signal S2 is at a high level (H), and does not output the drive signal COMB to its output terminal when the selection signal S2 is at a low level (L).

[0093] The selection signal S3 is input to the positive control terminal of transmission gate 234c (not marked with a circle), and is logically inverted by inverter 232c before being input to the negative control terminal of transmission gate 234c (marked with a circle). Additionally, a drive signal COMC is supplied to the input terminal of transmission gate 234c. When the input selection signal S3 is at a high level (H), transmission gate 234c conducts between its input and output terminals; when the input selection signal S3 is at a low level (L), it de-conducts between the input and output terminals. That is, transmission gate 234c outputs the drive signal COMC to its output terminal when the selection signal S3 is at a high level (H), and does not output the drive signal COMC to its output terminal when the selection signal S3 is at a low level (L).

[0094] The outputs of transmission gates 234a, 234b, and 234c are connected together. That is, drive signals COMA, COMB, and COMC, which are selected or not selected by selection signals S1, S2, and S3, are supplied to the outputs of the commonly connected transmission gates 234a, 234b, and 234c. The selection circuit 230 outputs the signal supplied to this commonly connected output as a drive signal VOUT to the corresponding ejection section 600.

[0095] The operation of the drive signal selection circuit 200 is explained. Figure 7 This diagram illustrates the operation of the drive signal selection circuit 200. The printing data signal SI is input serially in sync with the clock signal SCK, and is sequentially transmitted in the shift register 212 corresponding to the ejector unit 600. Then, by stopping the input of the clock signal SCK, the two bits of printing data [SIH, SIL] corresponding to each ejector unit 600 are held in the corresponding shift register 212.

[0096] Then, when the latch signal LAT rises, the 2 bits of printed data [SIH, SIL] held by shift register 212 are latched together by latch circuit 214. It should be noted that in... Figure 7 In the diagram, the 2-bit printed data [SIH, SIL] corresponding to the shift registers 212 of levels 1, 2, ..., n, which are latched by the latching circuit 214, are illustrated as LT1, LT2, ..., LTn.

[0097] The decoder 216 outputs logic level selection signals S1, S2, and S3 based on the dot size specified by the latched 2-bit printed data [SIH, SIL].

[0098] Specifically, when the printed data [SIH, SIL] is [1, 1], decoder 216 sets the logic levels of selection signals S1, S2, and S3 to H, L, and L levels during period T and outputs them to selection circuit 230. As a result, selection circuit 230 selects the trapezoidal waveform Adp during period T and outputs the drive signal VOUT corresponding to "large dot LD". Alternatively, when the printed data [SIH, SIL] is [1, 0], decoder 216 sets the logic levels of selection signals S1, S2, and S3 to L, H, and L levels during period T and outputs them to selection circuit 230. As a result, selection circuit 230 selects the trapezoidal waveform Bdp during period T and outputs the drive signal VOUT corresponding to "small dot SD". Alternatively, when the printed data [SIH, SIL] is [0, 1], decoder 216 sets the logic levels of selection signals S1, S2, and S3 to L, L, and L levels during period T and outputs them to selection circuit 230. As a result, selection circuit 230 does not select any of the trapezoidal waveforms Adp, Bdp, or Cdp during period T, and outputs a constant voltage Vc driving signal VOUT corresponding to "No ejection ND". Additionally, when the printed data [SIH, SIL] is [0, 0], decoder 216 sets the logic levels of selection signals S1, S2, and S3 to L, L, and H levels during period T and outputs them to selection circuit 230. As a result, selection circuit 230 selects trapezoidal waveform Cdp during period T and outputs the driving signal VOUT corresponding to "Micro-vibration BSD".

[0099] Here, when the selection circuit 230 does not select any of the trapezoidal waveforms Adp, Bdp, and Cdp, the voltage Vc supplied to the piezoelectric element 60 just now is maintained at one end of the corresponding piezoelectric element 60 through the capacitive component of the piezoelectric element 60. That is, the drive signal VOUT output by the selection circuit 230 at a constant voltage Vc includes the case where the voltage Vc just now, maintained by the capacitive component of the piezoelectric element 60, is supplied to the piezoelectric element 60 as the drive signal VOUT when none of the trapezoidal waveforms Adp, Bdp, and Cdp are selected as the drive signal VOUT.

[0100] As described above, the drive signal selection circuit 200 selects or deselects drive signals COMA, COMB, and COMC based on the printing data signal SI, latch signal LAT, and clock signal SCK, thereby generating a drive signal VOUT corresponding to each of the multiple ejector sections 600 and outputting it to the corresponding ejector section 600. This allows for individual control of the amount of ink ejected from each of the multiple ejector sections 600.

[0101] 1.3 Composition of the liquid ejection module

[0102] Next, use Figures 8 to 10The structure of the liquid ejection module 20 is described. Figure 8 This is a diagram showing the structure of the liquid ejection module 20. Here, the structure of the liquid ejection module 20 will be described. Figures 8 to 10 The middle diagram shows arrows indicating the mutually orthogonal X1, Y1, and Z1 directions. Additionally, in... Figures 8 to 10 In the description, the starting side of the arrow indicating the X1 direction is sometimes referred to as the -X1 side, and the front end side as the +X1 side; the starting side of the arrow indicating the Y1 direction is sometimes referred to as the -Y1 side, and the front end side as the +Y1 side; and the starting side of the arrow indicating the Z1 direction is sometimes referred to as the -Z1 side, and the front end side as the +Z1 side. Furthermore, in the following description, the liquid ejection module 20 of the liquid ejection device 1 in the first embodiment is described as having six ejection modules 23. When distinguishing between the individual ejection modules of the six ejection modules 23, each of the six ejection modules 23 is sometimes referred to as ejection modules 23-1 to 23-6.

[0103] The liquid ejection module 20 includes a housing 31, a collection substrate 33, a flow path structure 34, a head substrate 35, a distribution flow path 37, a fixing plate 39, and ejection modules 23-1 to 23-6. Furthermore, in the liquid ejection module 20, the flow path structure 34, the head substrate 35, the distribution flow path 37, and the fixing plate 39 are stacked along the Z1 direction from the -Z1 side to the +Z1 side in the order of fixing plate 39, distribution flow path 37, head substrate 35, and flow path structure 34. The housing 31 is located around the flow path structure 34, head substrate 35, distribution flow path 37, and fixing plate 39 to support them. The collection substrate 33 is erected on the +Z1 side of the housing 31 and held in place by the housing 31. The six ejection modules 23 are located between the distribution flow path 37 and the fixing plate 39, with a portion of them protruding from the outside of the liquid ejection module 20.

[0104] When describing the structure of the liquid ejection module 20, the structure of the ejection module 23 included in the liquid ejection module 20 will be described first. Figure 9 This is a diagram illustrating an example of the structure of the ejection module 23. Additionally, Figure 10 This is a diagram showing an example of a cross-section of the ejection module 23. Here, Figure 10 It is along Figure 9 The section shown is cut along line Aa. Figure 9 The cross-sectional view shown is of the ejection module 23. Additionally, Figure 9 The Aa line shown is a virtual line segment that passes through the inlet channel 661 of the ejection module 23 and through nozzles N1 and N2.

[0105] like Figure 9 and Figure 10As shown, the ejection module 23 has a plurality of nozzles N1 arranged side by side and a plurality of nozzles N2 arranged side by side. The total number of nozzles N1 and nozzles N2 in the ejection module 23 is n, the same number as the ejection section 600 in the ejection module 23. It should be noted that in the first embodiment, the ejection module 23 is described with the same number of nozzles N1 and nozzles N2. That is, the ejection module 23 is described with n / 2 nozzles N1 and n / 2 nozzles N2. Here, in the following description, when it is not necessary to distinguish between nozzles N1 and nozzles N2, they will sometimes be simply referred to as nozzle N.

[0106] The ejection module 23 includes wiring components 388, housing 660, protective substrate 641, flow path forming substrate 642, connecting plate 630, plastic substrate 620, and nozzle plate 623.

[0107] On the flow path forming substrate 642, a pressure chamber CB1, divided by multiple partition walls through anisotropic etching from one side, is arranged side-by-side corresponding to nozzle N1, and a pressure chamber CB2, divided by multiple partition walls through anisotropic etching from one side, is arranged side-by-side corresponding to nozzle N2. In the following description, without needing to distinguish between pressure chamber CB1 and pressure chamber CB2, they will sometimes be simply referred to as pressure chamber CB.

[0108] The nozzle plate 623 is located on the -Z1 side of the flow path forming substrate 642. A nozzle array Ln1 formed by n / 2 nozzles N1 and a nozzle array Ln2 formed by n / 2 nozzles N2 are provided on the nozzle plate 623. Here, in the following description, the surface of the nozzle plate 623 on the -Z1 side where the nozzles N open will sometimes be referred to as the liquid jetting surface 623a.

[0109] The connecting plate 630 is located on the -Z1 side of the flow path forming substrate 642 and the +Z1 side of the nozzle plate 623. A nozzle connecting channel RR1 connecting pressure chamber CB1 to nozzle N1 and a nozzle connecting channel RR2 connecting pressure chamber CB2 to nozzle N2 are provided on the connecting plate 630. Additionally, a pressure chamber connecting channel RK1 connecting the end of pressure chamber CB1 to manifold MN1 and a pressure chamber connecting the end of pressure chamber CB2 to manifold MN2 are independently provided on the connecting plate 630, corresponding to both pressure chambers CB1 and CB2.

[0110] Manifold MN1 includes a supply connection channel RA1 and a connecting connection channel RX1. The supply connection channel RA1 is configured to penetrate the connecting plate 630 along the Z1 direction, while the connecting connection channel RX1 does not penetrate the connecting plate 630 in the Z1 direction, but instead opens on the nozzle plate 623 side of the connecting plate 630 and is positioned midway along the Z1 direction. Similarly, manifold MN2 includes a supply connection channel RA2 and a connecting connection channel RX2. The supply connection channel RA2 is configured to penetrate the connecting plate 630 along the Z1 direction, while the connecting connection channel RX2 does not penetrate the connecting plate 630 in the Z1 direction, but instead opens on the nozzle plate 623 side of the connecting plate 630 and is positioned midway along the Z1 direction. Thus, the connecting connection channel RX1 of manifold MN1 is connected to the corresponding pressure chamber CB1 via the pressure chamber connection channel RK1, and the connecting connection channel RX2 of manifold MN2 is connected to the corresponding pressure chamber CB2 via the pressure chamber connection channel RK2.

[0111] In the following description, when it is not necessary to distinguish between nozzle connection channel RR1 and nozzle connection channel RR2, they will sometimes be referred to simply as nozzle connection channel RR; when it is not necessary to distinguish between manifold MN1 and manifold MN2, they will sometimes be referred to simply as manifold MN; when it is not necessary to distinguish between supply connection channel RA1 and supply connection channel RA2, they will sometimes be referred to simply as supply connection channel RA; and when it is not necessary to distinguish between connection connection channel RX1 and connection connection channel RX2, they will sometimes be referred to simply as connection connection channel RX.

[0112] The vibrating plate 610 is located on the +Z1 side of the flow path forming substrate 642. Furthermore, on the +Z1 side of the vibrating plate 610, two rows of piezoelectric elements 60 are formed corresponding to nozzles N1 and N2. One electrode and piezoelectric layer of each piezoelectric element 60 are formed for each pressure chamber CB, and the other electrode of each piezoelectric element 60 is configured as a common electrode shared by the pressure chambers CB. Therefore, a drive signal VOUT is supplied from the drive signal selection circuit 200 to one electrode of the piezoelectric element 60, and a reference voltage signal VBS is supplied to the other electrode of the piezoelectric element 60, i.e., the common electrode.

[0113] The protective substrate 641 is bonded to the +Z1 side surface of the flow path forming substrate 642. The protective substrate 641 forms a protective space 644 for protecting the piezoelectric element 60. Furthermore, a through hole 643 extending along the Z1 direction is provided on the protective substrate 641. The end of the lead electrode 611 leading from the electrode of the piezoelectric element 60 extends outwards, exposed inside the through hole 643. Thus, the wiring member 388 is electrically connected to the end of the lead electrode 611 exposed inside the through hole 643.

[0114] Additionally, a housing 660 is fixed to the protective substrate 641 and the connecting plate 630, which divides a portion of the manifold MN that communicates with multiple pressure chambers CB. The housing 660 is engaged with the protective substrate 641 and also with the connecting plate 630. Specifically, the housing 660 has a recess 665 on the -Z1 side surface that accommodates the flow path forming substrate 642 and the protective substrate 641. The recess 665 has an opening area larger than the surface of the protective substrate 641 that is engaged with the flow path forming substrate 642. Thus, when the flow path forming substrate 642, etc., are accommodated in the recess 665, the opening surface on the -Z1 side of the recess 665 is sealed by the connecting plate 630. As a result, the housing 660, the flow path forming substrate 642, and the protective substrate 641 divide the outer periphery of the flow path forming substrate 642 into a supply communication channel RB1 and a supply communication channel RB2. Here, when it is not necessary to distinguish between the supply communication channel RB1 and the supply communication channel RB2, they are sometimes simply referred to as the supply communication channel RB.

[0115] Furthermore, a malleable substrate 620 is provided on the surface of the connecting plate 630 where the connecting channel RA and the opening of the connecting channel RX are supplied. This malleable substrate 620 seals the openings of the connecting channel RA and the connecting channel RX. This malleable substrate 620 has a sealing film 621 and a fixing substrate 622. The sealing film 621 is formed of a flexible thin film or the like, and the fixing substrate 622 is formed of a hard material such as stainless steel.

[0116] An inlet channel 661 for supplying ink to the manifold MN is provided on the housing 660. In addition, a connection port 662 is provided on the housing 660. The connection port 662 is an opening that communicates with the through hole 643 of the protective substrate 641 and extends through it in the Z1 direction. The wiring component 388 is inserted through the connection port 662.

[0117] The wiring component 388 is a flexible component for electrically connecting the ejection module 23 to the head substrate 35, and an FPC can be used for example. Additionally, an integrated circuit 201 is mounted on the wiring component 388 using a COF (Chip On Film) mount. At least a portion of the aforementioned drive signal selection circuit 200 is mounted in this integrated circuit 201.

[0118] In the ejection module 23 configured as described above, the drive signal VOUT and the reference voltage signal VBS output by the drive signal selection circuit 200 are supplied to the piezoelectric element 60 via the wiring component 388. Then, the piezoelectric element 60 is driven by the change in the potential difference between the drive signal VOUT and the reference voltage signal VBS. As the piezoelectric element 60 is driven, the vibrating plate 610 is displaced in the vertical direction, causing a change in the internal pressure of the pressure chamber CB. Then, the change in the internal pressure of the pressure chamber CB causes the ink stored inside the pressure chamber CB to be ejected from the corresponding nozzle N. Here, the ejection module 23, including the nozzle N, the nozzle communication channel RR, the pressure chamber CB, the piezoelectric element 60, and the vibrating plate 610, corresponds to the ejection section 600 described above.

[0119] Return to Figure 8 The fixing plate 39 is located on the -Z1 side of the ejection module 23. The fixing plate 39 fixes six ejection modules 23. Specifically, the fixing plate 39 has six openings 391 extending through the fixing plate 39 along the Z2 direction. The liquid injection surface 623a of the ejection module 23 protrudes from each of these six openings 391. That is, the six ejection modules 23 are fixed to the fixing plate 39 in such a way that the liquid injection surface 623a protrudes from the corresponding opening 391.

[0120] The distribution flow path 37 is located on the +Z1 side of the ejection module 23. Four inlet portions 373 are provided on the +Z1 side surface of the distribution flow path 37. These four inlet portions 373 are flow path tubes protruding from the +Z1 side surface of the distribution flow path 37 along the Z1 direction towards the +Z1 side, communicating with flow path holes (not shown) formed on the -Z1 side surface of the flow path structure 34. Additionally, the (not shown) flow path tubes communicating with the four inlet portions 373 are located on the -Z1 side surface of the distribution flow path 37. These (not shown) flow path tubes on the -Z1 side surface of the distribution flow path 37 communicate with the inlet channels 661 of each of the six ejection modules 23. Furthermore, the distribution flow path 37 has six openings 371 extending along the Z1 direction. Wiring components 388 of each of the six ejection modules 23 are inserted through these six openings 371.

[0121] The head substrate 35 is located on the +Z1 side of the distribution flow path 37. A wiring component FC, electrically connected to the assembly substrate 33 (described later), is mounted on the head substrate 35. Four openings 351 and cutouts 352 and 353 are formed on the head substrate 35. Wiring components 388 of the ejection modules 23-2 to 23-5 are inserted through the four openings 351. The wiring components 388 of each of the ejection modules 23-2 to 23-5, inserted through the four openings 351, are then electrically connected to the head substrate 35 via solder or the like. The wiring component 388 of the ejection module 23-1 passes through the cutout 352, and the wiring component 388 of the ejection module 23-6 passes through the cutout 353. The wiring components 388 of each of the ejection modules 23-1 and 23-6, passing through the cutouts 352 and 353 respectively, are then electrically connected to the head substrate 35 via solder or the like.

[0122] In addition, four cutouts 355 are formed at the four corners of the head substrate 35. The inlet portion 373 passes through the four cutouts 355. Then, the four inlet portions 373 of the cutouts 355 are connected to the flow path structure 34 located on the +Z1 side of the head substrate 35.

[0123] The flow path structure 34 has a flow path plate Su1 and a flow path plate Su2. The flow path plate Su1 and the flow path plate Su2 are stacked along the Z1 direction with the flow path plate Su1 located on the +Z1 side and the flow path plate Su2 located on the -Z1 side, and are joined together by an adhesive or the like.

[0124] The flow path structure 34 has four inlet portions 341 protruding towards the +Z1 side along the Z1 direction on its +Z1 side surface. The four inlet portions 341 communicate with flow path holes (not shown) formed on the -Z1 side surface of the flow path structure 34 via ink flow paths formed inside the flow path structure 34. Furthermore, the flow path holes (not shown) formed on the -Z1 side surface of the flow path structure 34 communicate with the four inlet portions 373. Additionally, a through hole 343 extending along the Z1 direction is formed on the flow path structure 34. A wiring component FC, electrically connected to the head substrate 35, is inserted through the through hole 343. Furthermore, inside the flow path structure 34, in addition to the ink flow paths connecting the inlet portions 341 to the flow path holes (not shown) formed on the -Z1 side surface, a filter or similar device may also be provided to capture foreign matter contained in the ink flowing in the ink flow paths.

[0125] The housing 31 is positioned to cover the flow path structure 34, the head substrate 35, the distribution flow path 37, and the fixing plate 39, and supports the flow path structure 34, the head substrate 35, the distribution flow path 37, and the fixing plate 39. The housing 31 has four openings 311, a substrate insertion portion 313, and a retaining member 315.

[0126] The flow path structure 34 has four inlet portions 341 that are inserted through four openings 311. Ink is then supplied from the liquid container 3 to the four inlet portions 341 inserted through the four openings 311 via a tube (not shown).

[0127] The retaining member 315 holds the assembly substrate 33 in a state where a portion of the assembly substrate 33 is inserted through the assembly substrate insertion portion 313. A connection portion 330 is provided on the assembly substrate 33. Various signals, such as data signals DATA, drive signals COMA, COMB, COMC, reference voltage signal VBS, and other power supply voltages, output from the head drive module 10 are input to the connection portion 330 via the wiring member 30. In addition, the wiring member FC of the head substrate 35 is electrically connected to the assembly substrate 33. Thus, the assembly substrate 33 and the head substrate 35 are electrically connected. A semiconductor device including the above-mentioned recovery circuit 220 may also be provided on the assembly substrate 33. It should be noted that in Figure 8 The figure shows the case where the assembly substrate 33 has a connection portion 330. However, when the liquid ejection device 1 has multiple wiring components 30 and various signals such as data signal DATA, drive signal COMA, COMB, COMC, reference voltage signal VBS and other power supply voltage output by the head drive module 10 are input to the assembly substrate 33 through the multiple wiring components 30, the assembly substrate 33 may also have multiple connection portions 330 corresponding to each of the multiple wiring components 30.

[0128] In the liquid ejection module 20 configured as described above, ink stored in the liquid container 3 is supplied via a pipe (not shown) that connects the liquid container 3 and the inlet 341. The ink supplied to the liquid ejection module 20 is then guided through an ink flow path formed inside the flow path structure 34 to a flow path hole (not shown) formed on the -Z1 side of the flow path structure 34, and then supplied to four inlet 373s in the distribution flow path 37. The ink supplied to the distribution flow path 37 via the four inlet 373 is distributed to each of the six ejection modules 23 in the ink flow path (not shown) formed inside the distribution flow path 37, and then supplied to the inlet channel 661 of the corresponding ejection module 23. The ink supplied to the ejection module 23 via the inlet channel 661 is then stored in the pressure chamber CB included in the ejection section 600.

[0129] Furthermore, the head drive module 10 and the liquid ejection module 20 are electrically connected via one or more wiring components 30. Thus, various signals, including the drive signals COMA, COMB, COMC, reference voltage signal VBS, and data signal DATA output from the head drive module 10, are supplied to the liquid ejection module 20. These various signals, including the drive signals COMA, COMB, COMC, reference voltage signal VBS, and data signal DATA, are transmitted in the assembly substrate 33 and the head substrate 35. At this time, the recovery circuit 220 generates clock signals SCK1 to SCK6, printing data signals SI1 to SI6, and latch signals LAT1 to LAT6 corresponding to the ejection modules 23-1 to 23-6, based on the data signal DATA. Additionally, the integrated circuit 201, which includes a drive signal selection circuit 200, provided in the wiring component 388 generates a drive signal VOUT corresponding to each of the n ejection sections 600 and supplies it to the piezoelectric element 60 included in the corresponding ejection section 600. As a result, the piezoelectric element 60 is driven to eject the ink stored in the pressure chamber CB.

[0130] 1.4 Structure of the Head Driver Module

[0131] Next, refer to Figures 11 to 18 The structure of the head driving module 10 according to this embodiment will be described here. Figures 11 to 17 The diagram shows arrows indicating mutually orthogonal X2, Y2, and Z2 directions, which are independent of the aforementioned X1, Y1, and Z1 directions. Additionally, in... Figures 11 to 12 In the description, sometimes the starting side of the arrow indicating the X2 direction is called the -X2 side and the front side is called the +X2 side; the starting side of the arrow indicating the Y2 direction is called the -Y2 side and the front side is called the +Y2 side; the starting side of the arrow indicating the Z2 direction is called the -Z2 side and the front side is called the +Z2 side.

[0132] Figure 11 This is a perspective view showing the appearance of the head drive module 10 according to this embodiment. The head drive module 10 includes a base substrate B1, a conversion circuit substrate B2, and six drive signal output circuits DRV. The six drive signal output circuits DRV are composed of drive signal output circuit DRV1, drive signal output circuit DRV2, drive signal output circuit DRV3, drive signal output circuit DRV4, drive signal output circuit DRV5, and drive signal output circuit DRV6. The six drive signal output circuits DRV are equivalent to... Figure 2 The case where m is 6 in the drive signal output circuits 50-1 to 50-m shown.

[0133] The drive signal output circuits DRV1, DRV2, DRV3, DRV4, DRV5, and DRV6 are all identical in configuration. Therefore, in the following description, sometimes any one of the drive signal output circuits DRV1, DRV2, DRV3, DRV4, DRV5, and DRV6 will be described using drive signal output circuit DRV1 as an example.

[0134] The substrate B1 is configured such that it extends in the Z2 direction. That is, the substrate B1 is configured such that it extends in a direction intersecting the nozzle surface.

[0135] A conversion circuit board B2 and six drive signal output circuits (DRVs) are disposed on a base substrate B1. The conversion circuit board B2 is fixed to the base substrate B1 by multiple screws. The conversion circuit board B2 is the substrate on which the control circuit 100 is disposed. The control circuit 100 includes... Figure 2 The conversion circuit 120 shown is shown.

[0136] The drive signal output circuit DRV1 includes a drive circuit board DRB1. A drive circuit for generating drive signals is mounted on the drive circuit board DRB1. The drive signal output circuit DRV1 is connected to the substrate B1 via a BtoB connection to the drive circuit board DRB1. A BtoB connection refers to a connection via a BtoB connector. The drive circuit board DRB1 is connected to the substrate B1 via a BtoB connection and stands upright relative to the substrate B1.

[0137] Similarly, drive signal output circuits DRV2 to DRV6 each include drive circuit substrates DRB1 to DRB6. Drive circuit substrates DRB1 to DRB6 are respectively connected to the substrate B1B-to-B and are erected relative to the substrate B1. It should be noted that drive circuit substrates DRB1 to DRB6 are connected to other substrates only through B-to-B connections with the substrate B1.

[0138] The drive signal output circuits DRV1 and DRV2 are separated in the Y2 direction. That is, the drive signal output circuits DRV1 and DRV2 are separated in a direction orthogonal to a first direction, which is the direction opposite to the nozzle of the liquid ejector unit.

[0139] The drive signal output circuits DRV2 and DRV3 are separated in the Y2 direction. That is, the drive signal output circuits DRV2 and DRV3 are separated in a direction orthogonal to a first direction, which is the direction opposite to the nozzle of the liquid ejector unit.

[0140] The drive signal output circuits DRV4 and DRV5 are separated in the Y2 direction. That is, the drive signal output circuits DRV4 and DRV5 are separated in a direction orthogonal to a first direction, which is the direction opposite to the nozzle of the liquid ejector unit.

[0141] The drive signal output circuits DRV5 and DRV6 are separated in the Y2 direction. That is, the drive signal output circuits DRV5 and DRV6 are separated in a direction orthogonal to a first direction, which is the direction opposite to the nozzle of the liquid ejector unit.

[0142] The substrate B1 has a first connector CN1 on the drive circuit unit side.

[0143] The first connector CN1 on the drive circuit unit side is positioned along the -Z2 side edge of the substrate B1. One end of a wiring component 30 is mounted on this first connector CN1. The other end of the wiring component 30 is connected to the head-side connector of the liquid ejection module 20. That is, signals including drive signals COMA1~COMA6, COMB1~COMB6, COMC1~COMC6, and data signals DATA output from the head drive module 10 are supplied to the liquid ejection module 20 via the first connector CN1 and the wiring component 30. Therefore, the first connector CN1 on the drive circuit unit side is connected to the head-side connector via the wiring component 30.

[0144] The drive signal generated by the drive signal output circuit DRV1 is supplied from the drive circuit substrate DRB1 to the first connector CN1 on the drive circuit unit side via the substrate B1. In other words, the drive signal generated by the drive signal output circuit DRV1 is supplied to the liquid ejection module 20 via the substrate B1.

[0145] The second connector CN2 on the drive circuit unit side is positioned along the +Z2 side edge of the conversion circuit board B2. A cable (not shown) electrically connected to the control unit 2 is mounted on this second connector CN2. Thus, the signal output by the control unit 2, including the image information signal IP, is supplied to the head drive module 10. Here, the head drive module 10 and the control unit 2 can be connected, for example, via a Flexible Flat Cable (FFC), a USB (Universal Serial Bus) cable, or an HDMI (High-Definition Multimedia Interface) cable. In this case, a USB connector or an HDMI connector corresponding to the type of cable used is used as the second connector CN2 on the drive circuit unit side. Alternatively, the head drive module 10 and the control unit 2 can be directly electrically connected without a cable. In this case, a BtoB (Board to Board) connector can be used as the second connector CN2 on the drive circuit unit side.

[0146] Figure 12 This is a perspective view showing the appearance of the head drive module 10 in the state of having the frame installed according to this embodiment. Figure 12 The text shows that in Figure 11 The head drive module 10 shown is equipped with a frame HD and an air guide WR. The frame HD and air guide WR are provided for dust protection of the head drive module 10. Additionally, the frame HD has air guide holes H1 and H2. Air guide holes H1 and H2 improve the heat dissipation of the head drive module 10. Furthermore, air guide holes H1 and H2 utilize external airflow to cool the head drive module 10. It should be noted that air guide holes H1 and H2 can be omitted from the configuration of the air guide WR.

[0147] Here, refer to Figure 13 The configuration of the drive signal output circuit DRV is explained. Figure 13 This is a diagram illustrating the configuration of the drive signal output circuit DRV according to this embodiment. Figure 13 In this paper, we will take the drive signal output circuit DRV1 among the six drive signal output circuits DRV as an example to explain the structure of the drive signal output circuit DRV, but the same applies to the drive signal output circuits DRV2 to DRV6.

[0148] It should be noted that the length of the drive circuit board DRB1 in the Z2 direction can also be longer than the length in the Y2 direction. That is, the length of the drive circuit board DRB1 in the first direction can also be longer than the length in any direction orthogonal to the first direction, which is the direction opposite to the nozzle of the liquid ejector unit.

[0149] The drive circuit mounted on the drive circuit board DRB1 includes generating Figure 2 The diagram shows a driving circuit 52a for generating the driving signal COMA1, a driving circuit 52b for generating the driving signal COMB1, and a driving circuit 52c for generating the driving signal COMC1. Driving circuit 52a includes a coil 521a, a field-effect transistor (FET) 522a, and an integrated circuit (IC) 523a. Driving circuit 52b includes a coil 521b, a field-effect transistor 522b, and an integrated circuit 523b. Driving circuit 52c includes a coil 521c, a field-effect transistor 522c, and an integrated circuit 523c.

[0150] Drive circuits 52a, 52b, and 52c are Class D amplifiers, each comprising an integrated circuit, a transistor, and a coil. Compared to Class AB amplifiers, Class D amplifiers generate less heat. Therefore, in drive circuits 52a, 52b, and 52c, components used for heat dissipation, such as heat sinks, can be miniaturized compared to Class AB amplifiers. As a result, the mounting area of ​​the drive signal output circuit DRV1 is reduced, allowing for a more compact head drive module 10.

[0151] The drive circuit board DRB1 includes a connector CN3. The connector CN3 is connected to the base substrate B1. The drive circuit board DRB1 is connected to the base substrate B1 via the connector CN3 (BtoB connection). The configuration of the terminals of the connector CN3 will be described later.

[0152] The distance between connector CN3 and coil 521a is shorter than the distance between connector CN3 and integrated circuit 523a. The distance between connector CN3 and coil 521b is shorter than the distance between connector CN3 and integrated circuit 523b. The distance between connector CN3 and coil 521c is shorter than the distance between connector CN3 and integrated circuit 523c. With this configuration, the coil can be positioned near the connector in the head drive module 10. Therefore, in the head drive module 10, the wiring for the COM flow as the ejection waveform is shortened, which increases the ejection stability.

[0153] Here, the drive signal COMC1 is a micro-vibration signal that causes the liquid to vibrate to a degree that prevents it from being ejected from the nozzle of the head. The drive circuit 52c is a micro-vibration generation circuit that generates this micro-vibration signal. Therefore, the drive circuit board DRB1 is equipped with a micro-vibration generation circuit that generates this micro-vibration signal. With this configuration, ink thickening can be suppressed in the head drive module 10. It should be noted that the drive circuit 52c can also be omitted from the drive circuit board DRB1.

[0154] Here, refer to Figure 14 and Figure 15 The configuration in which the drive circuit board DRB stands upright relative to the base board B1 will be described. Figure 14 This is a perspective view showing the configuration of the drive circuit board DRB that stands upright relative to the substrate B1 according to this embodiment. Figure 15 This is a bottom view showing the configuration of the drive circuit boards DRBs that stand upright relative to the substrate B1 according to this embodiment. Six drive circuit boards DRBs stand upright relative to the substrate B1. The six drive circuit boards DRBs stand upright relative to the substrate B1 in a substantially parallel manner.

[0155] The substrate B1 is arranged such that its surface overlaps on a first virtual plane intersecting the nozzle surface. The nozzle surface refers to the surface on which the nozzles included in the plurality of ejection portions 600 are arranged. The first virtual plane is a plane with the X2 direction as its normal. In other words, the first virtual plane is a plane that includes the direction in which the substrate B1 extends. It should be noted that the direction in which the substrate B1 extends specifically refers to the direction of the long side of the substrate B1.

[0156] Therefore, the six drive circuit boards (DRBs) are connected to the base substrate B1 in a direction intersecting the direction of extension of the base substrate B1. With this configuration, the head drive module 10 does not become larger in the direction of extension of the base substrate B1, and the space utilization efficiency when each of the six drive circuit boards (DRBs) is connected to the base substrate B1 via the connector CN3 is improved. For example, if the surfaces of the six drive circuit boards (DRBs) on the base substrate B1 are arranged approximately parallel to the surface of the base substrate B1 and each of the six drive circuit boards (DRBs) is connected to the base substrate B1 via the connector CN3, the space utilization efficiency when each of the six drive circuit boards (DRBs) is connected to the base substrate B1 via the connector CN3 is reduced.

[0157] Furthermore, the six drive circuit boards (DRBs) are connected to the base substrate B1 in such a way that the six drive circuit boards (DRBs) extend in a direction substantially perpendicular to the nozzle surface. With this configuration, the head drive module 10 does not become large in the direction in which the base substrate B1 extends, and the space utilization efficiency on the base substrate B1 can be improved.

[0158] In this way, in the head drive module 10, the six drive circuit substrates DRB are erected relative to the base substrate B1. Therefore, the head drive module 10 does not become larger in the direction in which the base substrate B1 extends.

[0159] It should be noted that the extension directions of the six drive circuit substrates (DRBs) when they are connected to the base substrate B1 are not limited to the directions described above. The extension directions of the six drive circuit substrates (DRBs) can also be inclined from a direction approximately perpendicular to the nozzle surface. Furthermore, the extension directions of the six drive circuit substrates (DRBs) can be different from each other.

[0160] It should be noted that as long as the six drive circuit boards DRB are disposed on the base substrate B1, they do not need to stand upright relative to the base substrate B1.

[0161] It should be noted that the number of DRBs on multiple drive circuit boards can also be more than six.

[0162] Next, refer to Figure 16 and Figure 17 The configuration comprising the ejection units including the head drive module 10 will be described. Figure 16 This is a perspective view showing the configuration of the multiple ejection units involved in this embodiment. Figure 16 As an example, nine ejection units are shown. The nine ejection units are identical in configuration. Ejection unit 5 is one of the nine ejection units.

[0163] In the ejection unit 5, the head drive module 10 and the liquid ejection module 20 are electrically connected via one or more wiring components 30. When assembled into the ejection unit 5, the head drive module 10 is located on the side opposite to the nozzle of the liquid ejection module 20. In the ejection unit 5, to achieve high-speed and high-resolution image formation, the head drive module 10 is positioned directly above the liquid ejection module 20.

[0164] In the ejection unit 5, a structure is adopted in which liquid ejection modules 20 are densely arranged to achieve high-speed and high-resolution image formation. Each liquid ejection module 20 is equivalent to a head. Each liquid ejection module 20 includes an ejection section 600 and an assembly substrate. The ejection section 600 receives a drive signal and ejects liquid from a nozzle disposed on a nozzle surface. The assembly substrate includes a head-side connector.

[0165] The structure of densely arranged liquid ejection modules 20 is also called a row head structure. The three ejection units are arranged adjacent to each other in the main scanning direction. Figure 16The middle direction is Y2. Therefore, multiple liquid ejection modules 20 are arranged along a first direction parallel to the nozzle surface. Three ejection units arranged adjacent to each other in the main scanning direction are further arranged with three more in the delivery direction. Figure 16 The middle direction is X2. It should be noted that the main scanning direction is also called the paper width direction, and the transport direction is also called the paper feed direction.

[0166] Figure 17 This is a top view showing the configuration of the multiple ejection units involved in this embodiment. Figure 17 The thickness direction of the head drive module 10 is described below. Figure 17 The middle direction is X2. In Figure 17 In the figure, the thickness of the head drive module 10 in the thickness direction is shown as thickness T1.

[0167] As described above, in the head drive module 10, by erecting and connecting six drive circuit substrates DRB relative to the base substrate B1, the large size in the direction of extension of the base substrate B1 is suppressed. On the other hand, in the head drive module 10, since the six drive circuit substrates DRB are erected and connected relative to the base substrate B1, the thickness T1 is increased. Here, the increase in thickness T1 refers to an increase compared to the case where the drive circuits, each mounted on one of the six drive circuit substrates DRB, are mounted on the base substrate B1. In the head drive module 10, the thickness T1 is set to a range that does not exceed the thickness T2 of the liquid ejection module 20. That is, the thickness T1 is set to a range that does not exceed the external dimensions of the head.

[0168] Here, refer to Figure 18 The configuration of the terminals provided by connector CN3 for connection is described. Figure 18 This diagram illustrates the configuration of the terminals of the connector CN3 according to this embodiment. The connector CN3 includes a COMA terminal P1, a COMB terminal P2, a VBS terminal P3, and a COMC terminal P4. It should be noted that... Figure 18 The image shows a portion of the terminals of the connector CN3.

[0169] COMA terminal P1 transmits the drive signal COMA1 to the upper electrode included in the piezoelectric element 60 of the head.

[0170] The COMB terminal P2 transmits the drive signal COMB1 to the upper electrode included in the piezoelectric element 60.

[0171] The VBS terminal P3 transmits a constant voltage signal to the lower electrode included in the piezoelectric element 60. This constant voltage signal is the reference voltage signal VBS1.

[0172] The COMC terminal P4 transmits the drive signal COMC1. As described above, the drive signal COMC1 is a micro-vibration signal that causes the liquid to vibrate to a degree that prevents it from being ejected from the nozzle.

[0173] like Figure 18 As shown, among the terminals located between COMA terminal P1 and COMB terminal P2, a portion are either VBS terminal P3 or COMC terminal P4. It should be noted that... Figure 18 The terminal configuration of the connector CN3 shown is an example and is not limited thereto. However, in order to reduce inductance, the terminal configuration of the connector CN3 is preferably one that satisfies the following conditions.

[0174] The VBS terminal P3 is connected adjacent to both the COMA terminal P1 and the COMB terminal P2. In other words, the VBS terminal P3 is positioned between the COMA terminal P1 and the COMB terminal P2. This configuration, by placing the VBS terminal P3, which transmits the reference voltage signal VBS1 that flows in the opposite direction to the current flowing relative to the drive signals COMA1 and COMB1, between the COMA terminal P1 and the COMB terminal P2, reduces inductance.

[0175] like Figure 18 As shown, the COMC terminal P4 is positioned between the COMA terminal P1 and the COMB terminal P2. Here, the drive signals COMA1 and COMB1 are relatively large currents compared to the drive signal COMC1. By positioning the COMC terminal P4, which flows through the drive signal COMC1, between the COMA terminal P1, which flows through the drive signal COMA1, and the COMB terminal P2, which flows through the drive signal COMB1, the inductance can be reduced.

[0176] As explained above, the drive circuit unit involved in this embodiment is a drive circuit unit disposed together with the head in the head unit and generating drive signals for driving the head, and includes a base substrate B1 and multiple drive circuit substrates.

[0177] The substrate B1 includes a drive circuit unit side connector that connects to the head-side connector. Drive circuits that generate drive signals are mounted on multiple drive circuit substrates.

[0178] The base substrate B1 is arranged such that it extends in a direction intersecting the nozzle surface of the head. Multiple drive circuit boards are disposed on the base substrate B1.

[0179] With this configuration, in the driving circuit unit according to this embodiment, since multiple driving circuit substrates are disposed on the substrate B1, the driving circuit unit does not become large in the direction intersecting the nozzle surface. In the driving circuit unit according to this embodiment, the size of the substrate B1 corresponding to chip driving in the long side direction is suppressed. In the driving circuit unit according to this embodiment, since the head is densely arranged in the main scanning direction, it is beneficial to form a high-resolution image.

[0180] It should be noted that the liquid ejection device 1 is not limited to ejecting liquid by driving a piezoelectric element; the present invention can also be applied to liquid ejection devices of other types, such as the so-called thermosensitive method. Furthermore, the liquid ejection device 1 can also be a device that ejects liquid by moving the ejection unit 5 relative to the medium P, or it can move the ejection unit 5 without moving the medium P.

[0181] Alternatively, the first connector CN1, the second connector CN2, and the connecting connector CN3 on the drive circuit unit side can use flat-angle connectors instead of right-angle connectors. When the first connector CN1 on the drive circuit unit side is a flat-angle connector, it can also connect from the side to the portion of the liquid ejection module 20 protruding towards the Z2 side. It should be noted that the first connector CN1 on the drive circuit unit side can also be referred to as the first connector. The head-side connector can also be referred to as the head connector.

[0182] 2. Second Implementation Method

[0183] 2.1 Cooling the drive circuit using a cooling unit

[0184] Next, refer to Figures 19 to 28 As a second embodiment, the configuration of the cooling drive circuit by the cooling unit will be described. Figure 19 This is a perspective view showing the configuration of the cooling unit U1 according to this embodiment. The cooling unit U1 cools the drive circuit by circulating liquid in a flow path. As an example, the liquid is water. The liquid is also called coolant. It should be noted that circulating liquid in a flow path is also called allowing liquid to flow through a flow path.

[0185] The cooling unit U1 includes six radiator sections HS, flow paths F1 and F2, and a control unit C1 (not shown). The six radiator sections HS consist of radiator section HS1, radiator section HS2, radiator section HS3, radiator section HS4, radiator section HS5, and radiator section HS6. It should be noted that the radiator section can also be referred to as a housing.

[0186] Since the functions of radiator section HS1, radiator section HS2, radiator section HS3, radiator section HS4, radiator section HS5 and radiator section HS6 are the same, in the following description, radiator section HS1 will sometimes be used as the representative to describe the functions of the six radiator sections HS.

[0187] Flow path F1 connects radiator sections HS1, HS2, HS3, HS4, HS5, and HS6 in this sequence. Flow path F1 has a straight section as a direct portion and a curved section as a curved portion. Flow path F1 connects radiator section HS1 and HS2 through the straight section. Flow path F1 connects radiator section HS2 and HS3 through the curved section. Flow path F1 connects radiator section HS3 and HS4 through the straight section. Flow path F1 connects radiator section HS4 and HS5 through the curved section. Flow path F1 connects radiator section HS5 and HS6 through the straight section.

[0188] Flow path F2 has the same shape as flow path F1. Flow path F2 is positioned at a different height than flow path F1. The height is... Figure 19 The position in the X2 direction is shown in the middle. Flow path F2 connects heat sink sections HS1, HS2, HS3, HS4, HS5, and HS6 in the same order as flow path F1.

[0189] Control unit C1 controls the circulation of the liquid circulating in flow path F1. Control unit C1 also controls the circulation of the liquid circulating in flow path F2. Control unit C1 can independently control the circulation of the liquid in flow path F1 and the circulation of the liquid in flow path F2. For example, control unit C1 can control the circulation direction of the liquid in flow path F1 to be the same as that of the liquid in flow path F2. On the other hand, control unit C1 can control the circulation direction of the liquid in flow path F1 to be different from that of the liquid in flow path F2. Details regarding the control of liquid circulation by control unit C1 will be described later.

[0190] Figure 20 This is a perspective view showing the cooling unit U1 according to this embodiment installed in the drive signal output circuit DRV. The heat sink HS1 is connected to the drive circuit board DRB1. Similarly, the heat sink HS2 is connected to the drive circuit board DRB2. The heat sink HS3 is connected to the drive circuit board DRB3. The heat sink HS4 is connected to the drive circuit board DRB4. The heat sink HS5 is connected to the drive circuit board DRB5. The heat sink HS6 is connected to the drive circuit board DRB6.

[0191] Therefore, in the cooling unit U1, the heat sink section HS1, which allows liquid flow, is located between the drive circuit board DRB1 and the drive circuit board DRB4. The heat sink section HS2, which allows liquid flow, is located between the drive circuit board DRB2 and the drive circuit board DRB3. The heat sink section HS3, which allows liquid flow, is located between the drive circuit board DRB3 and the drive circuit board DRB6. The heat sink section HS4, which allows liquid flow, is located between the drive circuit board DRB4 and the drive circuit board DRB5.

[0192] The cooling unit U1 allows liquid to flow in the order of radiator section HS1, radiator section HS2, radiator section HS3, radiator section HS4, radiator section HS5, and radiator section HS6.

[0193] Here, in the cooling unit U1, for example, the heat sink HS5 is also located on the side of the drive circuit board DRB5 opposite to the drive circuit board DRB4 to allow liquid to flow. The heat sink HS4 is in contact with the drive circuit board DRB4, and the drive circuit board DRB5 is in contact with the side of the heat sink HS4 opposite to the drive circuit board DRB4. In this way, the heat sink is not limited to contacting the drive circuit on one side for cooling, but can also contact the drive circuit on both sides for cooling. It should be noted that this contact also includes indirect contact with the drive circuit through the thermally conductive material and the substrate. The cooling unit U1 reverses the flow of liquid that has passed between the drive circuit boards DRB4 and DRB5, allowing it to flow to the side of the drive circuit board DRB5 opposite to the drive circuit board DRB4.

[0194] With this configuration, even with the cooling unit U1 installed, the length of the head drive module 10 in the Z2 direction, i.e., the first direction, will not increase. This first direction is the direction opposite to the nozzle of the liquid ejection head unit. Furthermore, with this configuration, even with the cooling unit U1 installed, the width of the head drive module 10 in the Y2 direction, i.e., the direction orthogonal to the first direction, will not increase. Even with the cooling unit U1 installed, the space utilization efficiency of the head drive module 10 will not decrease. In other words, both cooling and miniaturization can be achieved.

[0195] Furthermore, in the cooling unit U1, a common flow path is used to cool the multiple drive circuit boards included in the head drive module 10. Therefore, compared to the case where multiple flow paths and multiple pumps are provided separately to cool the multiple drive circuit boards, the number of pumps can be reduced in the cooling unit U1, and the size of the pumps can be miniaturized. In addition, since a common flow path is used in the cooling unit U1 to cool the multiple drive circuit boards, the number of components can be reduced, resulting in high space utilization efficiency.

[0196] In this embodiment, such as Figure 21 As shown, the drive circuit board DRB1 includes a heat-conducting sheet TS1. The heat-conducting sheet TS1 is disposed in contact with the field-effect transistors and integrated circuits mounted in the drive circuit of the drive circuit board DRB1. The heat sink HS1 is connected to the drive circuit board DRB1 by contacting the heat-conducting sheet TS1 disposed on the drive circuit board DRB1. Figure 22 The state of the heat sink section HS1 connected to the drive circuit board DRB1 is shown. Figure 23 This is a perspective view showing the shape of the radiator section HS1 as viewed from the surface. Figure 24 This is a perspective view showing the shape of the radiator section HS1 when viewed from the rear.

[0197] Here, one of the two sides of the heat-conducting sheet TS1 is in contact with the drive circuit mounted on the drive circuit board DRB1. The other side is in contact with the heat sink HS1. That is, the heat sink HS1 is in contact with the heat-conducting sheet TS1 on the side opposite to the drive circuit mounted on the drive circuit board DRB1.

[0198] Similarly, for example, the drive circuit board DRB4 includes a heat-conducting sheet TS4. One of the two sides of the heat-conducting sheet TS4 is in contact with the drive circuit mounted on the drive circuit board DRB4. The other side is in contact with the heat sink HS4. That is, the heat sink HS4 is in contact with the heat-conducting sheet TS4 on the side opposite to the drive circuit mounted on the drive circuit board DRB4.

[0199] Similarly, for example, the drive circuit board DRB5 includes a heat-conducting sheet TS5. The heat-conducting sheet TS5 is disposed in contact with the drive circuit mounted on the drive circuit board DRB5. The heat sink HS5 is in contact with the side of the heat-conducting sheet TS5 opposite to the drive circuit board DRB5.

[0200] It should be noted that thermal conductive sheets can also be called thermally conductive materials.

[0201] It should be noted that a temperature sensor TH1 is located around the drive circuit on the drive circuit board DRB1. The temperature sensor TH1 detects the temperature of the drive circuit. The temperature sensor TH1 is, for example, a thermistor.

[0202] Figure 25 This is a perspective view showing the configuration of the head drive module 10 in the state of having the cooling unit U1 and the frame HD installed according to this embodiment. Figure 26This is a perspective view showing the configuration of the head drive module 10 according to this embodiment, with the cooling unit U1, the frame HD, and the air guide WR installed. As described above, the cooling unit U1 is installed inside the head drive module 10 by sandwiching the heat sink between the drive circuit board and the drive circuit board. Therefore, even with the cooling unit U1 installed, the outer diameter of the head drive module 10 does not change. Even with the cooling unit U1 installed, the frame HD and the air guide WR can still be installed on the head drive module 10.

[0203] Next, refer to Figure 27 The circulation of liquid controlled by the control unit C1 will be explained. Figure 27 This is a diagram illustrating the control of liquid circulation according to this embodiment. Figure 27 The diagram schematically shows a top view of six drive signal output circuits (DRVs). "A", "C", and "B" represent the drive circuits that generate drive signals COMA, COMC, and COMB, respectively, mounted on the six drive circuit boards (DRBs).

[0204] When using drive signal COMA or drive signal COMB, the load and heat generation are greater compared to when using drive signal COMC. Therefore, control unit C1 directs the liquid to flow sequentially from the drive signal output circuit with the highest usage rate of drive signal COMA or drive signal COMB among the six drive signal output circuits DRV.

[0205] For example, consider the case where the drive signal output circuits DRV1 and DRV2 in region R1 have high utilization rates of drive signal COMA or COMB, while the drive signal output circuits DRV5 and DRV6 in region R3 have low utilization rates of drive signal COMA or COMB. That is, when the heat generation in region R1 is greater than that in region R2, the control unit C1 directs the liquid to flow in flow paths F1 and F2 in the order of region R1, region R2, and region R3. In other words, in this case, the control unit C1 controls the flow so that the circulation direction of the liquid in flow path F1 is the same as the circulation direction of the liquid in flow path F2. This direction is... Figure 27 The direction indicated by the circulation direction FD1 is the first direction, namely the -Z2 direction, which is the direction opposite to the nozzle of the liquid ejector unit. Therefore, the cooling unit U1 causes the liquid to flow between the drive circuit board DRB1 and the drive circuit board DRB2 along the first direction.

[0206] On the other hand, consider the case where the utilization rate of drive signals COMA or COMB in drive signal output circuits DRV1 and DRV2 in region R1 is low, while the utilization rate of drive signals COMA or COMB in drive signal output circuits DRV5 and DRV6 in region R3 is high. That is, when the heat generation in region R3 is greater than that in region R1, control unit C1 causes the liquid to flow in flow paths F1 and F2 in the order of region R3, region R2, and region R1. In other words, in this case, control unit C1 controls the flow so that the circulation direction of the liquid in flow path F1 is the same as the circulation direction of the liquid in flow path F2. This direction is... Figure 27 The direction indicated by the circulation direction FD2 is the opposite direction to the nozzle of the liquid ejector unit, i.e., the opposite direction of the first direction, which is the Z2 direction. Therefore, the cooling unit U1 causes the liquid to flow between the drive circuit board DRB1 and the drive circuit board DRB4 in the opposite direction of the first direction.

[0207] Furthermore, consider the scenario where the utilization rates of drive signals COMA or COMB from drive signal output circuits DRV1 and DRV2 in region R1 are the same as those from drive signal output circuits DRV5 and DRV6 in region R3. In other words, when the heat generation in region R1 is the same as that in region R2, control unit C1 causes the liquid to flow in flow path F1 in the order of region R1, region R2, and region R3, and in flow path F2 in the order of region R3, region R2, and region R1. That is, in this case, control unit C1 controls the flow so that the circulation direction of the liquid in flow path F1 is different from the circulation direction of the liquid in flow path F2.

[0208] In the above example, the comparison of heat generation was described using regions of the two drive signal output circuits (DRVs) as units, but this is not a limitation. The object of heat generation comparison could also be a portion of the drive circuit mounted on the drive circuit board (DRB).

[0209] When the heat generated by the first part of the drive circuit is greater than the heat generated by the second part of the drive circuit, the control unit C1 performs a first control to circulate the liquid in the flow path F1 in the order of the heat-conducting component connected to the first part and then the heat-conducting component connected to the second part. Heat sinks HS1 to HS6 are examples of heat-conducting components. Furthermore, when the heat generated by the second part of the drive circuit is greater than the heat generated by the first part of the drive circuit, the control unit C1 performs a second control to circulate the liquid in the flow path F1 in the order of the heat-conducting component connected to the second part and then the heat-conducting component connected to the first part.

[0210] Furthermore, the control unit C1's control of circulating the liquid in flow path F2 is the same as the control unit C1's control of circulating the liquid in flow path F1. That is, when the heat generated by the first part of the drive circuit is greater than the heat generated by the second part of the drive circuit, the control unit C1 performs a first control to circulate the liquid in flow path F2 in the order of the heat-conducting component connected to the first part, and then the heat-conducting component connected to the second part. Conversely, when the heat generated by the second part of the drive circuit is greater than the heat generated by the first part of the drive circuit, the control unit C1 performs a second control to circulate the liquid in flow path F2 in the order of the heat-conducting component connected to the second part, and then the heat-conducting component connected to the first part.

[0211] With this configuration, the liquid ejection device according to this embodiment can be controlled to circulate the liquid in two flow paths in the order of the portions of the drive circuit that generate relatively more heat. Therefore, the liquid ejection device according to this embodiment can achieve more efficient cooling compared to the case with only one flow path.

[0212] When the heat generated by the second part of the drive circuit is the same as that generated by the first part of the drive circuit, the control unit C1 performs a third control to make the liquid circulate in flow path F1 and flow path F2 in different directions.

[0213] With this configuration, in the liquid ejection device according to this embodiment, when the heat generated by the second part of the drive circuit is the same as that generated by the first part of the drive circuit, both the first part and the second part can be cooled equally. Therefore, in the liquid ejection device according to this embodiment, cooling can be performed more efficiently compared to the case where the liquid circulation direction is the same in flow path F1 and flow path F2.

[0214] The control unit C1 acquires temperature information, for example, based on the detection result of the temperature sensor TH1. This temperature information indicates the amount of heat generated by a portion of the drive circuit. For example, multiple drive circuit boards (DRBs) each have a temperature sensor TH1. The control unit C1 switches control based on the temperature information acquired from the temperature sensor TH1. That is, the control unit C1 switches between first control and second control based on the temperature information of a first portion and a second portion of the drive circuit. If, based on the temperature information, the heat generated by the first portion of the drive circuit is greater than the heat generated by the second portion, the control unit C1 performs the first control. On the other hand, if, based on the temperature information, the heat generated by the second portion of the drive circuit is greater than the heat generated by the first portion, the control unit C1 performs the second control.

[0215] With this configuration, in the liquid ejection device according to this embodiment, cooling can be performed sequentially from the parts with higher heat generation in the first and second parts of the drive circuit based on temperature information. Therefore, compared with the case where cooling is not based on temperature information, cooling can be performed more efficiently.

[0216] Furthermore, the duty cycle of a portion of the drive circuit varies depending on the printed pattern. The control unit C1 can also switch between first control and second control based on printing content information. This printing content information indicates the load on the printed pattern. That is, if the heat generated by the first portion of the drive circuit is greater than the heat generated by the second portion of the drive circuit based on the printing content information, the control unit C1 performs first control. Conversely, if the heat generated by the second portion of the drive circuit is greater than the heat generated by the first portion of the drive circuit based on the printing content information, the control unit C1 performs second control.

[0217] With this configuration, in the liquid ejection device according to this embodiment, cooling can be performed sequentially from the parts with high heat generation in the first and second parts of the drive circuit based on the printed pattern. Therefore, compared with the case where cooling is performed without based on the printed pattern, cooling can be performed more efficiently.

[0218] As described above, when using drive signal COMA or drive signal COMB, the load and heat generation are greater compared to when using drive signal COMC. The output waveform of the drive circuit varies depending on the type of drive signal. Therefore, the heat generation of the drive circuit can be obtained based on the output waveform of the drive circuit. The control unit C1 can also switch between first control and second control based on the output waveforms of the first drive circuit and the second drive circuit.

[0219] With this configuration, in the liquid ejection device according to this embodiment, cooling can be performed sequentially from the one with greater heat generation in the first drive circuit and the second drive circuit based on the output waveform. Therefore, compared with the case where cooling is not based on the output waveform, cooling can be performed more efficiently.

[0220] Alternatively, the control unit C1 can also perform control based on information about the duty cycle of the power or current of the driving circuit.

[0221] As described above, the control unit C1 collects the operating status of the drive circuit and estimates the temperature of the drive circuit based on the operating status of the drive circuit.

[0222] Furthermore, the control unit C1 can also change both the number of flow paths that circulate the liquid and the direction of liquid circulation within those flow paths. The control unit C1 can also control at least one of the direction of liquid circulation within the flow paths and the number of flow paths that circulate the liquid.

[0223] Next, refer to Figure 28 The situation of cooling multiple head units is explained. Figure 28 This is a schematic diagram illustrating the cooling of the multiple head units involved in this embodiment. Figure 28 The diagram schematically shows a top view of multiple head units. (For example...) Figure 28 As shown, multiple ejection units HU1, HU2, and HU3 are arranged in the main scanning direction. Ejection unit HU1 is adjacent to ejection unit HU2. Ejection unit HU2 is adjacent to ejection unit HU3.

[0224] Here, the ejection unit HU1 includes a head unit HD1 and a head drive module HM1. The ejection unit HU2 includes a head unit HD2 and a head drive module HM2. The ejection unit HU3 includes a head unit HD3 and a head drive module HM3. Therefore, head units HD1, HD2, and HD3 are arranged in multiples in the main scanning direction. Head units HD1, HD2, and HD3 eject ink into adjacent areas in this order.

[0225] Head drive modules HM1, HM2, and HM3 each have six drive circuits. Heat sinks (not shown) are connected to each of these six drive circuits. Flow path F1 connects the heat sinks (not shown) connected to the six drive circuits of head drive modules HM1, HM2, and HM3, respectively. For example, the drive circuit of head drive module HM1 is referred to as the third drive circuit, and the heat sink connected to this third drive circuit is referred to as the third heat-conducting component. The drive circuit of head drive module HM3 is referred to as the fourth drive circuit, and the heat sink connected to this fourth drive circuit is referred to as the fourth heat-conducting component. Therefore, flow path F1 connects the third heat-conducting component and the fourth heat-conducting component.

[0226] When the heat generated by the third drive circuit in head drive module HM1 is greater than the heat generated by the fourth drive circuit in head drive module HM3, control unit C1 causes the liquid to circulate in flow path F1 in the order of the third heat-conducting component connected to the third drive circuit and the fourth heat-conducting component connected to the fourth drive circuit. This direction is... Figure 28 The direction indicated by the cyclic direction FD3.

[0227] On the other hand, when the heat generated by the fourth drive circuit of the head drive module HM3 is greater than the heat generated by the third drive circuit of the head drive module HM1, the control unit C1 causes the liquid to circulate in the flow path F1 in the order of the fourth heat-conducting component connected to the fourth drive circuit and the third heat-conducting component connected to the third drive circuit. This direction is... Figure 28 The direction indicated by the cyclic direction FD4.

[0228] As described above, in the head drive module 10, the flow path F1 connects the third heat-conducting component and the fourth heat-conducting component. With this configuration, in the liquid ejection device according to this embodiment, since the multiple drive circuits of each of the multiple head drive modules can be cooled by having a shared flow path F1, a simpler configuration can be formed compared to the case with multiple flow paths. Furthermore, the liquid ejection device according to this embodiment can be miniaturized compared to the case with multiple flow paths.

[0229] Therefore, the cooling unit of the head drive module HM2 allows liquid supplied from the cooling unit of the head drive module HM1, which generates and drives the drive signal of the ejection unit HU1 adjacent to the ejection unit HU2, to circulate. Additionally, the cooling unit U1 discharges liquid into the cooling unit of the head drive module HM3, which generates and drives the drive signal of the ejection unit HU3, which is adjacent to the ejection unit HU2 on the opposite side from the ejection unit HU1.

[0230] Here, the cooling unit of the head drive module HM2 will be described as the aforementioned cooling unit U1. The cooling unit U1 allows the liquid supplied from the cooling unit of the head drive module HM1 to flow in the order of radiator section HS1, radiator section HS4, radiator section HS5, radiator section HS2, radiator section HS3, and radiator section HS6, and then discharges the liquid to the cooling unit of the head drive module HM3.

[0231] As described above, in the ejection units HU1, HU2, and HU3, head units HD1, HD2, and HD3 are arranged in multiples along the main scanning direction. With this configuration, in the liquid ejection apparatus according to this embodiment, since the nozzle density in the main scanning direction can be increased, it is advantageous to form high-resolution images in line printhead printing.

[0232] Next, refer to Figure 29 The overall structure of the cooling unit U1 is described. Figure 29 This diagram illustrates an example of the overall configuration of the cooling unit U1 according to this embodiment. The cooling unit U1 includes a flow path F1, a water storage section WT1, a cooler RD1, a pump PM1, and a control section C1. It should be noted that the cooling unit U1 may also include flow paths F1 and F2 as in the embodiment described above. Figure 29 In the example, the head unit of the head drive module, which is cooled by the cooling unit U1, is shown as the ejection unit HU4, which is configured with a row head.

[0233] The water storage section WT1 is connected to the flow path F1.

[0234] Cooler RD1 cools the liquid in water storage section WT1.

[0235] Pump PM1 circulates the liquid in the water storage section WT1 in the flow path F1.

[0236] Control unit C1 controls the circulation of liquid circulating in flow path F1 by controlling pump PM1. Control unit C1 switches the direction in which pump PM1 circulates liquid between a forward direction and a reverse direction. The forward direction is, for example, the first direction. As described above, control unit C1 can also switch the direction in which pump PM1 circulates liquid between the forward and reverse directions based on the temperature of the drive circuit. In this case, for example, control unit C1 switches the direction in which pump PM1 circulates liquid between the forward and reverse directions based on the temperature of the drive circuit detected by temperature sensor TH1. Additionally, as described above, control unit C1 can also switch the direction in which pump PM1 circulates liquid between the forward and reverse directions based on the temperature of the drive circuit estimated based on the operating state of the drive circuit. It should be noted that control unit C1 includes a CPU and RAM (Random Access Memory) as main storage, and performs control based on a program deployed in the main storage.

[0237] It should be noted that the configuration of the head drive module 10 cooled by the cooling unit U1 is not limited to the configuration described above. For example, the configuration of the head drive module 10 is not limited to having six drive signal output circuits (DRVs). Furthermore, the drive signal output circuits (DRVs) may not be erected relative to the substrate B1. In this embodiment, the drive circuit may also be disposed on the substrate B1. The cooling unit U1 changes the direction of liquid circulation in the flow path based on the heat generated by the portion of the drive circuit. As described above, heat-conducting components such as heat sinks are connected to the portion of the drive circuit. The cooling unit U1 determines from which heat-conducting component the liquid should circulate sequentially based on the heat generated by the portion of the drive circuit.

[0238] As described above, the liquid ejection device according to this embodiment includes a head, a drive circuit, and a cooling unit U1.

[0239] The head has a spray section that receives a drive signal and sprays liquid from a nozzle disposed on the nozzle surface. A drive circuit is connected to the head and generates a drive signal. A cooling unit U1 cools the drive circuit.

[0240] The cooling unit U1 includes: a first heat-conducting component connected to a first part of the drive circuit; a second heat-conducting component connected to a second part of the drive circuit; a first flow path connecting the first heat-conducting component and the second heat-conducting component; and a control unit C1 for controlling the circulation of liquid circulating in the first flow path.

[0241] When the heat generated in the first part is greater than the heat generated in the second part, the control unit C1 performs a first control to circulate the liquid in the first flow path in the order of the first heat-conducting component and the second heat-conducting component. When the heat generated in the second part is greater than the heat generated in the first part, the control unit C1 performs a second control to circulate the liquid in the first flow path in the order of the second heat-conducting component and the first heat-conducting component.

[0242] With this configuration, the liquid ejection device of this embodiment, by incorporating a liquid cooling mechanism, can achieve highly efficient cooling by changing the liquid circulation direction according to the heat generated by the heat source. Highly efficient cooling, for example, refers to cooling sequentially from the portion generating the most heat, based on the heating state of the drive device, such as the duty cycle. When cooling is performed directly above the head using a fan or similar device, the landing position of the ink ejected from the nozzle may sometimes be affected. However, in the liquid ejection device of this embodiment, the landing position of the ink is not affected by cooling. Furthermore, the liquid ejection device of this embodiment is not affected by ink mist floating directly above the head due to cooling.

[0243] In this embodiment, the ejection unit 5 is an example of a liquid ejection device. The liquid ejection module 20 is an example of a head. The drive circuit mounted on each of the six drive circuit boards DRB is an example of a first or second part of the drive circuit. The heat sink sections HS1 to HS6 are examples of a first or a second heat-conducting component, respectively. It should be noted that one or more heat sink sections, that is, one or more heat-conducting components, can also be referred to as a water cooling mechanism. The flow path F1 is an example of a first flow path.

[0244] It should be noted that the first part or the second part is not limited to the drive circuits mounted on each of the six drive circuit substrates (DRBs). The first part or the second part can also be any part of the six drive circuit substrates (DRBs). However, in the liquid ejection device according to this embodiment, the first part and the second part are respectively the first drive circuit and the second drive circuit. The first drive circuit and the second drive circuit are respectively the drive circuits mounted on each of the six drive circuit substrates (DRBs). For example, the first drive circuit is the drive circuit mounted on drive circuit substrate DRB1, and the second drive circuit is the drive circuit mounted on drive circuit substrate DRB2.

[0245] Here, it is considered that the difference in heat generation between the first and second drive circuits, acting as a single drive circuit, tends to be greater than the difference in heat generation between the first and second portions of the same drive circuit, acting as any part of the drive circuit. For example, it is considered that the difference in heat generation between the first and second drive circuits tends to be greater than the difference in heat generation between the first and second portions of the same drive circuit. In the liquid ejection device according to this embodiment, since the cooling sequence can be changed on a per-drive-circuit basis, more efficient cooling can be achieved compared to the case where cooling is performed on a per-portion basis.

[0246] The above description of one embodiment of the present disclosure is based on the accompanying drawings. However, the specific configuration is not limited to the above configuration, and various design changes can be made without departing from the spirit of the present disclosure.

[0247] Appendix 1

[0248] [1]. A driving circuit unit, disposed together with a head in a head unit, and generating a driving signal to drive the head, the driving circuit unit comprising:

[0249] The substrate includes a drive circuit unit side connector that connects to the head-side connector; and

[0250] Multiple driving circuit boards are provided, and driving circuits that generate driving signals are respectively mounted on the multiple driving circuit boards.

[0251] The base plate is configured such that it extends in a direction intersecting the nozzle surface of the head.

[0252] The plurality of driving circuit boards are disposed on the base substrate.

[0253] [2]. According to the driving circuit unit described in [1], wherein,

[0254] The plurality of driving circuit boards are connected to the base substrate in a direction that intersects with the direction extending from the base substrate.

[0255] [3]. According to the driving circuit unit described in [2], wherein,

[0256] The plurality of drive circuit boards are connected to the base substrate in such a manner that the plurality of drive circuit boards extend in a direction substantially perpendicular to the nozzle surface.

[0257] [4]. The driving circuit unit according to any one of [1] to [3], wherein,

[0258] The driving circuit is a Class D amplifier that includes integrated circuits, transistors, and coils.

[0259] [5]. The driving circuit unit according to any one of [1] to [4], wherein,

[0260] The driving circuit board includes a connector for connection to the base substrate.

[0261] The distance between the connector and the coil is shorter than the distance between the connector and the integrated circuit.

[0262] [6]. According to the driving circuit unit described in [5], wherein,

[0263] The connector for connection includes:

[0264] The first terminal transmits a drive signal to the upper electrode included in the piezoelectric element of the head;

[0265] The second terminal transmits a drive signal with an amplitude different from the drive signal transmitted from the first terminal to the upper electrode; and

[0266] The third terminal transmits a constant voltage signal to the lower electrode included in the piezoelectric element.

[0267] The third terminal is disposed between the first terminal and the second terminal.

[0268] [7]. The driving circuit unit according to [5] or [6], wherein,

[0269] The drive circuit board also includes a micro-vibration generation circuit, which generates a micro-vibration signal that causes the liquid to vibrate to a degree that prevents it from being ejected from the nozzle of the head.

[0270] The connector for connection includes:

[0271] The fourth terminal transmits a drive signal to the upper electrode included in the piezoelectric element of the head;

[0272] The fifth terminal transmits a drive signal with an amplitude different from the drive signal transmitted from the fourth terminal to the upper electrode; and

[0273] The sixth terminal transmits the micro-vibration signal.

[0274] The sixth terminal is disposed between the fourth terminal and the fifth terminal.

[0275] [8]. The driving circuit unit according to any one of [1] to [6], wherein,

[0276] The drive circuit board also includes a micro-vibration generation circuit that generates a micro-vibration signal that causes the liquid to vibrate to a degree that prevents it from being ejected from the nozzle of the head.

[0277] [9]. A header unit, comprising:

[0278] Drive circuit unit; and

[0279] head,

[0280] The head has:

[0281] The ejection section receives a drive signal supplied from the drive circuit unit and ejects liquid from a nozzle disposed on the nozzle surface; and

[0282] The assembly substrate includes a head-side connector.

[0283] The driving circuit unit includes:

[0284] The substrate includes a drive circuit unit side connector connected to the head-side connector; and

[0285] Multiple driving circuit boards are provided, and the driving circuits that generate the driving signals are respectively mounted on the multiple driving circuit boards.

[0286] The substrate is configured such that it extends in a direction intersecting the nozzle surface.

[0287] The plurality of driving circuit boards are disposed on the base substrate.

[0288]

[10] . A liquid ejection device, comprising:

[0289] Multiple head units; and

[0290] Conveying unit,

[0291] The head unit includes:

[0292] Drive circuit unit; and

[0293] head,

[0294] The head has:

[0295] The ejection section receives a drive signal supplied from the drive circuit unit and ejects liquid from a nozzle disposed on the nozzle surface; and

[0296] The assembly substrate includes a head-side connector.

[0297] The driving circuit unit includes:

[0298] The substrate includes a drive circuit unit side connector connected to the head-side connector; and

[0299] Multiple driving circuit boards are provided, and the driving circuits that generate the driving signals are respectively mounted on the multiple driving circuit boards.

[0300] The substrate is configured such that it extends in a direction intersecting the nozzle surface.

[0301] The plurality of driving circuit substrates are disposed on the base substrate.

[0302] The plurality of head units are arranged along a first direction parallel to the nozzle surface.

[0303] Appendix 2

[0304] [1]. A liquid ejection device, comprising:

[0305] The head has a spraying part that receives a drive signal and sprays liquid from a nozzle disposed on a nozzle face;

[0306] A driving circuit, connected to the head, generates a driving signal; and

[0307] The cooling unit cools the drive circuit.

[0308] The cooling unit includes:

[0309] The first heat-conducting component is connected to the first part of the driving circuit;

[0310] The second heat-conducting component is connected to the second part of the drive circuit;

[0311] A first flow path connects the first heat-conducting component to the second heat-conducting component; and

[0312] The control unit controls the circulation of the liquid circulating in the first flow path.

[0313] If the heat generated by the first part is greater than the heat generated by the second part, the control unit performs a first control to circulate the liquid in the first flow path in the order of the first heat-conducting component and the second heat-conducting component.

[0314] When the heat generated by the second part is greater than the heat generated by the first part, the control unit performs a second control to circulate the liquid in the first flow path in the order of the second heat-conducting component and the first heat-conducting component.

[0315] [2]. According to the liquid ejection device described in [1], wherein,

[0316] The cooling unit also includes a second flow path that connects the first heat-conducting component and the second heat-conducting component.

[0317] If the heat generated by the first part is greater than the heat generated by the second part, the control unit performs a first control to circulate the liquid in the second flow path in the order of the first heat-conducting component and the second heat-conducting component.

[0318] When the heat generation of the second part is greater than that of the first part, the control unit performs a second control to circulate the liquid in the second flow path in the order of the second heat-conducting component and the first heat-conducting component.

[0319] [3]. According to the liquid ejection device described in [2], wherein,

[0320] When the heat generation of the second part is the same as that of the first part, the control unit performs a third control to make the liquid circulate in the first flow path and the liquid circulate in the second flow path in a manner in which the directions of liquid circulation in the first flow path and the second flow path are different.

[0321] [4]. According to the liquid ejection device described in [3], wherein,

[0322] The control unit switches between the first control and the second control based on the printed content information.

[0323] [5]. The liquid ejection device according to any one of [1] to [4], wherein,

[0324] The control unit switches between the first control and the second control based on the temperature information of the first part and the temperature information of the second part.

[0325] [6]. The liquid ejection device according to any one of [1] to [5], wherein,

[0326] The driving circuit includes a first driving circuit and a second driving circuit.

[0327] The first part is the first driving circuit.

[0328] The second part is the second driving circuit.

[0329] [7]. The liquid ejection device according to [6], wherein,

[0330] The control unit switches between the first control and the second control based on the output waveform of the first drive circuit and the output waveform of the second drive circuit.

[0331] [8]. The liquid ejection device according to any one of [1] to [7], wherein,

[0332] The head unit includes the head and the driving circuit.

[0333] The head unit has multiple units arranged in the paper width direction.

[0334] [9]. The liquid ejection device according to [8], wherein,

[0335] The driving circuits of the plurality of head units respectively include a third driving circuit and a fourth driving circuit.

[0336] The cooling unit includes:

[0337] The third heat-conducting component is connected to the third part of the third driving circuit; and

[0338] The fourth heat-conducting component is connected to the fourth part of the fourth driving circuit.

[0339] The first flow path connects the third heat-conducting component to the fourth heat-conducting component.

[0340]

[10] . A cooling unit for cooling the drive circuit of a liquid ejection device.

[0341] The liquid ejection device includes:

[0342] A head having an ejection section that receives a drive signal and ejects liquid from a nozzle disposed on a nozzle face; and

[0343] The driving circuit is connected to the head and generates driving signals.

[0344] The cooling unit includes:

[0345] The first heat-conducting component is connected to the first part of the driving circuit;

[0346] The second heat-conducting component is connected to the second part of the drive circuit;

[0347] A first flow path connects the first heat-conducting component to the second heat-conducting component; and

[0348] The control unit controls the circulation of the liquid circulating in the first flow path.

[0349] If the heat generated by the first part is greater than the heat generated by the second part, the control unit performs a first control to circulate the liquid in the first flow path in the order of the first heat-conducting component and the second heat-conducting component.

[0350] When the heat generated by the second part is greater than the heat generated by the first part, the control unit performs a second control to circulate the liquid in the first flow path in the order of the second heat-conducting component and the first heat-conducting component.

[0351] Appendix 3

[0352] [1]. A drive unit located on the side opposite to the nozzle of a liquid ejector head unit, the drive unit comprising:

[0353] A first substrate having a first connector for connection to the head connector of the liquid ejection head unit; and

[0354] The second substrate is equipped with a drive circuit that generates drive signals.

[0355] The second substrate is BtoB connected to the first substrate and stands upright relative to the first substrate.

[0356] The drive signal is supplied from the second substrate to the first connector via the first substrate.

[0357] [2]. According to the driving unit described in [1], wherein,

[0358] The second substrate is connected to other substrates only through a BtoB connection with the first substrate.

[0359] [3]. The driving unit according to [1] or [2], wherein,

[0360] The length of the second substrate in a first direction is longer than the length in any direction orthogonal to the first direction, which is the direction opposite to the nozzle of the liquid ejector unit.

[0361] [4]. The driving unit according to any one of [1] to [3], wherein,

[0362] The driving unit also includes a third substrate, which is BtoB connected to the first substrate and stands upright relative to the first substrate.

[0363] The driving signal generated by the driving circuit mounted on the third substrate is supplied to the liquid ejector unit via the first substrate.

[0364] [5]. According to the driving unit described in [4], wherein,

[0365] The second substrate and the third substrate are separated in a direction orthogonal to a first direction, which is the direction opposite to the outlet of the liquid ejector unit.

[0366] [6]. According to the driving unit described in [5], wherein,

[0367] The drive unit also includes a water-cooling mechanism located between the second substrate and the third substrate, allowing liquid to flow between the second substrate and the third substrate.

[0368] The second substrate is in contact with the second thermally conductive material, and the water-cooling mechanism is in contact with the side of the second thermally conductive material opposite to the second substrate.

[0369] [7]. According to the driving unit described in [6], wherein,

[0370] The water cooling mechanism allows liquid to flow between the second substrate and the third substrate in the first direction or in the opposite direction.

[0371] [8]. The driving unit according to [6] or [7], wherein,

[0372] The water-cooling mechanism is located on the side of the third substrate opposite to the second substrate, allowing liquid to flow on the side of the third substrate opposite to the second substrate.

[0373] The third substrate is in contact with the third thermally conductive material, and the water-cooling mechanism is in contact with the side of the third thermally conductive material opposite to the third substrate.

[0374] [9]. The driving unit according to [7] or [8], wherein,

[0375] The water cooling mechanism causes the liquid that has flowed between the second substrate and the third substrate to flow to the side of the third substrate opposite to the second substrate.

[0376]

[10] . A liquid ejection head unit, comprising a drive unit and a head.

[0377] The head has:

[0378] The nozzle outlet receives a drive signal supplied from the drive unit and ejects liquid from a nozzle disposed on the nozzle surface; and

[0379] The assembly substrate includes the head connector.

[0380] The drive unit is located on the side opposite to the nozzle and includes:

[0381] A first substrate having a first connector for connection to the head connector; and

[0382] The second substrate is equipped with a drive circuit that generates drive signals.

[0383] The second substrate is BtoB connected to the first substrate and stands upright relative to the first substrate.

[0384] The drive signal is supplied from the second substrate to the first connector via the first substrate.

[0385]

[11] . A liquid ejection device, comprising:

[0386] Multiple liquid ejector head units; and

[0387] Conveying unit,

[0388] The liquid ejection head unit includes:

[0389] Drive unit; and

[0390] head,

[0391] The head has:

[0392] The nozzle outlet receives a drive signal supplied from the drive unit and ejects liquid from a nozzle disposed on the nozzle surface; and

[0393] The assembly substrate includes the head connector.

[0394] The drive unit is located on the side opposite to the nozzle and includes:

[0395] A first substrate having a first connector for connection to the head connector; and

[0396] The second substrate is equipped with a drive circuit that generates drive signals.

[0397] The second substrate is BtoB connected to the first substrate and stands upright relative to the first substrate.

[0398] The drive signal is supplied from the second substrate to the first connector via the first substrate.

[0399] Appendix 4

[0400] [1]. A driving unit that generates a driving signal for driving a liquid ejector head unit, and includes:

[0401] A driving substrate, equipped with a driving circuit that generates the driving signal;

[0402] A thermally conductive material is in contact with the drive circuit on the side opposite to the drive substrate;

[0403] The water-cooling mechanism is in contact with the thermally conductive material on the side opposite to the drive circuit.

[0404] The pump circulates the liquid within the water-cooling mechanism; and

[0405] The control circuit controls the operation of the pump.

[0406] The control circuit switches the direction in which the pump directs the liquid flow between a positive direction and a reverse direction opposite to the positive direction.

[0407] [2]. According to the driving unit described in [1], wherein,

[0408] The control circuit switches the direction in which the pump allows liquid to flow between the positive and negative directions based on the temperature of the drive circuit.

[0409] [3]. According to the driving unit described in [2], wherein,

[0410] The driving substrate has a temperature sensor that detects the temperature of the driving circuit around the driving circuit.

[0411] The control circuit switches the direction in which the pump allows liquid to flow between the positive and negative directions based on the temperature of the drive circuit detected by the temperature sensor.

[0412] [4]. According to the driving unit described in [2], wherein,

[0413] The control circuit collects the operating status of the drive circuit, and estimates the temperature of the drive circuit based on the operating status of the drive circuit.

[0414] The control circuit switches the direction in which the pump allows liquid to flow between the positive and negative directions based on the estimated temperature of the drive circuit.

[0415] [5]. A liquid ejector unit, comprising:

[0416] The drive unit generates drive signals to drive the liquid ejector head unit; and

[0417] head,

[0418] The head has:

[0419] The nozzle outlet receives a drive signal supplied from the drive unit and ejects liquid from a nozzle disposed on the nozzle surface; and

[0420] The assembly substrate includes the head connector.

[0421] The drive unit includes:

[0422] A driving substrate, equipped with a driving circuit that generates the driving signal;

[0423] A thermally conductive material is in contact with the drive circuit on the side opposite to the drive substrate;

[0424] The water-cooling mechanism is in contact with the thermally conductive material on the side opposite to the drive circuit.

[0425] The pump circulates the liquid within the water-cooling mechanism; and

[0426] The control circuit controls the operation of the pump.

[0427] The control circuit switches the direction in which the pump directs the liquid flow between a positive direction and a reverse direction opposite to the positive direction.

[0428] [6]. A liquid ejection device, comprising:

[0429] Multiple liquid ejector head units; and

[0430] Conveying unit,

[0431] The liquid ejection head unit includes:

[0432] The driving unit generates a driving signal to drive the liquid ejector head unit; and

[0433] head,

[0434] The head has:

[0435] The nozzle outlet receives a drive signal supplied from the drive unit and ejects liquid from a nozzle disposed on the nozzle surface; and

[0436] The assembly substrate includes the head connector.

[0437] The drive unit includes:

[0438] A driving substrate, equipped with a driving circuit that generates the driving signal;

[0439] A thermally conductive material is in contact with the drive circuit on the side opposite to the drive substrate;

[0440] The water-cooling mechanism is in contact with the thermally conductive material on the side opposite to the drive circuit.

[0441] The pump circulates the liquid within the water-cooling mechanism; and

[0442] The control circuit controls the operation of the pump.

[0443] The control circuit switches the direction in which the pump directs the liquid flow between a positive direction and a reverse direction opposite to the positive direction.

[0444] Appendix 5

[0445] [1]. A first driving unit generates a first driving signal to drive a first liquid ejection head unit, the first driving unit comprising:

[0446] The first driving circuit generates the first driving signal;

[0447] A first thermally conductive material is in contact with the first driving circuit; and

[0448] The first water-cooling mechanism is in contact with the first heat-conducting material on the side opposite to the first driving circuit, and allows liquid to circulate.

[0449] The first water-cooling mechanism allows the liquid supplied from the second water-cooling mechanism of the second drive unit to circulate, and discharges the liquid to the third water-cooling mechanism of the third drive unit.

[0450] The second driving unit generates a second driving signal to drive the second liquid ejector unit adjacent to the first liquid ejector unit.

[0451] The third driving unit generates a third driving signal to drive the third liquid ejector unit, which is adjacent to the first liquid ejector unit on the side opposite to the second liquid ejector unit.

[0452] [2]. According to the first driving unit described in [1], wherein,

[0453] The first driving unit also includes a second driving circuit, which is different from the first driving circuit. The second driving circuit generates a fourth driving signal to drive the first liquid ejector head unit.

[0454] The first water-cooling mechanism has a first chamber and a second chamber. The first chamber is in contact with the first thermally conductive material, the second chamber is in contact with the second thermally conductive material, and the second thermally conductive material is in contact with the second driving circuit.

[0455] After the first water-cooling mechanism causes the liquid from the second water-cooling mechanism to flow through the first tank and the second tank in sequence, the liquid is discharged to the third water-cooling mechanism.

[0456] [3]. The first driving unit according to [1] or [2], wherein,

[0457] The second liquid nozzle unit, the first liquid nozzle unit, and the third liquid nozzle unit spray liquid into adjacent areas in this order.

[0458] [4]. A first liquid ejector head unit, comprising:

[0459] The first driving unit generates a first driving signal to drive the first liquid ejection head unit; and

[0460] head,

[0461] The head has:

[0462] The nozzle outlet receives a drive signal supplied from the first drive unit and ejects liquid from a nozzle disposed on the nozzle surface; and

[0463] The assembly substrate includes the head connector.

[0464] The first driving unit includes:

[0465] The first driving circuit generates the first driving signal;

[0466] A first thermally conductive material is in contact with the first driving circuit; and

[0467] The first water-cooling mechanism is in contact with the first heat-conducting material on the side opposite to the first driving circuit, and allows liquid to circulate.

[0468] The first water-cooling mechanism allows the liquid supplied from the second water-cooling mechanism of the second drive unit to circulate, and discharges the liquid to the third water-cooling mechanism of the third drive unit.

[0469] The second driving unit generates a second driving signal to drive the second liquid ejector unit adjacent to the first liquid ejector unit.

[0470] The third driving unit generates a third driving signal to drive the third liquid ejector unit, which is adjacent to the first liquid ejector unit on the side opposite to the second liquid ejector unit.

[0471] [5]. A liquid ejection device, comprising:

[0472] Multiple liquid ejector head units; and

[0473] Conveying unit,

[0474] The plurality of liquid ejection head units include:

[0475] First liquid ejection head unit;

[0476] The second liquid ejector unit is adjacent to the first liquid ejector unit; and

[0477] The third liquid ejector unit is adjacent to the first liquid ejector unit on the side opposite to the second liquid ejector unit.

[0478] The first liquid ejection head unit includes:

[0479] A first driving unit generates a first driving signal to drive the first liquid ejector head unit; and

[0480] head,

[0481] The head has:

[0482] The nozzle outlet receives a drive signal supplied from the first drive unit and ejects liquid from a nozzle disposed on the nozzle surface; and

[0483] The assembly substrate includes the head connector.

[0484] The first driving unit includes:

[0485] The first driving circuit generates the first driving signal;

[0486] A first thermally conductive material is in contact with the first driving circuit; and

[0487] The first water-cooling mechanism is in contact with the first heat-conducting material on the side opposite to the first driving circuit, and allows liquid to circulate.

[0488] The first water-cooling mechanism allows the liquid supplied from the second water-cooling mechanism of the second drive unit to circulate, and discharges the liquid to the third water-cooling mechanism of the third drive unit.

[0489] The second drive unit generates a second drive signal to drive the second liquid ejection head unit.

[0490] The third driving unit generates a third driving signal to drive the third liquid ejector unit.

Claims

1. A liquid discharge apparatus characterized by comprising: have: The head has a spraying part that receives a drive signal and sprays liquid from a nozzle disposed on a nozzle face; A driving circuit, connected to the head, generates a driving signal; and The cooling unit cools the drive circuit. The cooling unit includes: The first heat-conducting component is connected to the first part of the driving circuit; The second heat-conducting component is connected to the second part of the drive circuit; The first flow path connects the first heat-conducting component and the second heat-conducting component; as well as The control unit controls the circulation of the liquid circulating in the first flow path. If the heat generated by the first part is greater than the heat generated by the second part, the control unit performs a first control to circulate the liquid in the first flow path in the order of the first heat-conducting component and the second heat-conducting component. If the heat generated in the second part is greater than the heat generated in the first part, the control unit performs a second control to circulate the liquid in the first flow path in the order of the second heat-conducting component and the first heat-conducting component. The cooling unit also includes a second flow path that connects the first heat-conducting component and the second heat-conducting component. If the heat generated by the first part is greater than the heat generated by the second part, the control unit performs a first control to circulate the liquid in the second flow path in the order of the first heat-conducting component and the second heat-conducting component. If the heat generated in the second part is greater than the heat generated in the first part, the control unit performs a second control to circulate the liquid in the second flow path in the order of the second heat-conducting component and the first heat-conducting component. When the heat generation of the second part is the same as that of the first part, the control unit performs a third control to make the liquid circulate in the first flow path and the liquid circulate in the second flow path in a manner in which the directions of liquid circulation in the first flow path and the second flow path are different.

2. The liquid ejection device according to claim 1, characterized in that, The control unit switches between the first control and the second control based on the printed content information.

3. The liquid ejection device according to claim 1, characterized in that, The control unit switches between the first control and the second control based on the temperature information of the first part and the temperature information of the second part.

4. The liquid ejection device according to claim 1, characterized in that, The driving circuit includes a first driving circuit and a second driving circuit. The first part is the first driving circuit. The second part is the second driving circuit.

5. The liquid ejection device according to claim 4, characterized in that, The control unit switches between the first control and the second control based on the output waveform of the first drive circuit and the output waveform of the second drive circuit.

6. The liquid ejection device according to claim 4 or 5, characterized in that, The head unit includes the head and the driving circuit. The head unit has multiple units arranged in the paper width direction.

7. The liquid ejection device according to claim 6, characterized in that, The driving circuits of the plurality of head units respectively include a third driving circuit and a fourth driving circuit. The cooling unit includes: The third heat-conducting component is connected to the third part of the third driving circuit; as well as The fourth heat-conducting component is connected to the fourth part of the fourth driving circuit. The first flow path connects the third heat-conducting component to the fourth heat-conducting component.

8. A cooling unit, characterized in that, Cool the drive circuit of the liquid ejection device. The liquid ejection device includes: A head having an ejection section that receives a drive signal and ejects liquid from a nozzle disposed on a nozzle face; and The driving circuit is connected to the head and generates driving signals. The cooling unit includes: The first heat-conducting component is connected to the first part of the driving circuit; The second heat-conducting component is connected to the second part of the drive circuit; The first flow path connects the first heat-conducting component and the second heat-conducting component; as well as The control unit controls the circulation of the liquid circulating in the first flow path. If the heat generated by the first part is greater than the heat generated by the second part, the control unit performs a first control to circulate the liquid in the first flow path in the order of the first heat-conducting component and the second heat-conducting component. If the heat generated in the second part is greater than the heat generated in the first part, the control unit performs a second control to circulate the liquid in the first flow path in the order of the second heat-conducting component and the first heat-conducting component. The cooling unit also includes a second flow path that connects the first heat-conducting component and the second heat-conducting component. If the heat generated by the first part is greater than the heat generated by the second part, the control unit performs a first control to circulate the liquid in the second flow path in the order of the first heat-conducting component and the second heat-conducting component. If the heat generated in the second part is greater than the heat generated in the first part, the control unit performs a second control to circulate the liquid in the second flow path in the order of the second heat-conducting component and the first heat-conducting component. When the heat generation of the second part is the same as that of the first part, the control unit performs a third control to make the liquid circulate in the first flow path and the liquid circulate in the second flow path in a manner in which the directions of liquid circulation in the first flow path and the second flow path are different.

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