Capacitive load drive circuit and liquid dispensing device

Abstract

To provide a capacitive load drive circuit that can reduce the risk of decreased operational stability and reduced waveform accuracy of the drive signal. [Solution] A capacitive load drive circuit comprising: a first drive signal output circuit that receives a first digital signal and outputs a first drive signal; a first amplification circuit that amplifies the first drive signal and outputs a first drive signal for driving a first capacitive load; and a wiring board that includes a first substrate surface and a second substrate surface located facing each other, on which the first drive signal output circuit and the first amplification circuit are provided, wherein the first amplification circuit is provided on the first substrate surface and the first drive signal output circuit is provided on the second substrate surface.

Description

Technical Field

[0001] The present invention relates to a capacitive load driving circuit and a liquid ejection device.

Background Art

[0002] A liquid ejection device including a liquid ejection head that includes a capacitive load and ejects a liquid such as ink by driving the capacitive load with a driving signal, and a capacitive load driving circuit that supplies a driving signal to the liquid ejection head is known. For example, Patent Document 1 discloses a liquid ejection device including a drive signal generation circuit (capacitive load drive circuit) including an analog conversion circuit that specifies the waveform of a drive signal and a transistor pair that outputs a drive signal based on the output from the analog conversion circuit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The drive signal for driving the liquid ejection head is a signal with a large amplitude, and when the drive signal is supplied to the capacitive load, a large current sufficient to stably drive the capacitive load is involved. This current may cause the transistor pair that outputs the drive signal and the analog conversion circuit that specifies the waveform of the drive signal to become hot. When the transistor pair and the analog conversion circuit become hot, the operating stability of the capacitive load drive circuit including the transistor pair and the analog conversion circuit decreases, and there is a risk that the waveform accuracy of the output drive signal decreases.

Means for Solving the Problems

[0005] One aspect of the capacitive load drive circuit according to the present invention is A first drive signal output circuit that receives a first digital signal and outputs a first drive signal, A first amplification circuit that amplifies the first drive signal and outputs a first drive signal to drive the first capacitive load, A wiring board comprising a first substrate surface and a second substrate surface located facing each other, on which the first drive signal output circuit and the first amplification circuit are provided, Equipped with, The first amplification circuit is provided on the first substrate surface, The first drive signal output circuit is provided on the second substrate surface.

[0006] One embodiment of the liquid dispensing device according to the present invention is: A discharge head that discharges liquid by driving a capacitive load, A capacitive load drive circuit that outputs a drive signal to drive the capacitive load, Equipped with, The capacitive load drive circuit is, A first drive signal output circuit that receives a first digital signal and outputs a first drive signal, A first amplification circuit that amplifies the first drive signal and outputs a first drive signal to drive the first capacitive load, A wiring board comprising a first substrate surface and a second substrate surface located facing each other, on which the first drive signal output circuit and the first amplification circuit are provided, Equipped with, The first amplification circuit is provided on the first substrate surface, The first drive signal output circuit is provided on the second substrate surface. [Brief explanation of the drawing]

[0007] [Figure 1] This is a diagram showing the schematic configuration of a liquid dispensing device. [Figure 2] This figure shows an example of the functional configuration of a dispensing unit. [Figure 3] This figure shows the schematic structure of one of the multiple discharge sections of a discharge module. [Figure 4]It is a diagram showing an example of the signal waveforms of the drive signals COMA and COMB. [Figure 5] It is a diagram showing the functional configuration of the drive signal selection circuit. [Figure 6] It is a diagram showing an example of the decoding content in the decoder. [Figure 7] It is a diagram showing an example of the configuration of the selection circuit corresponding to one unit of the discharge unit. [Figure 8] It is a diagram for explaining the operation of the drive signal selection circuit. [Figure 9] It is a diagram showing an example of the configuration of the drive circuit. [Figure 10] It is a diagram showing an example of the operation of the amplification control circuit. [Figure 11] It is a diagram showing an example of the structure of the head drive module. [Figure 12] It is a diagram showing an example of the structure of the drive circuit board. [Figure 13] It is a diagram showing an example of the structure of the transistor. [Figure 14] It is a diagram for explaining an example of the thermal connection between the transistor and the integrated circuit and the heat sink. [Figure 15] It is a diagram showing an example of the cross-section of the head drive module in the modified example.

Embodiments for Carrying Out the Invention

[0008] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The drawings used are for convenience of explanation. Note that the embodiments described below do not unduly limit the content of the present invention described in the claims. Also, not all of the configurations described below are essential constituent elements of the present invention.

[0009] 1. Configuration of the liquid discharge device FIG. 1 is a diagram showing a schematic configuration of the liquid ejection device 1. As shown in FIG. 1, the liquid ejection device 1 is a so-called line type inkjet printer that forms a desired image on the medium P by ejecting ink, which is an example of a liquid, at a desired timing onto the medium P conveyed by the conveyance unit 4. Note that the liquid ejection device 1 is not limited to a line type inkjet printer and may be a serial type inkjet printer. Further, the liquid ejection device 1 is not limited to an inkjet printer, and may be a color material ejection device used for manufacturing color filters such as liquid crystal displays, an electrode material ejection device used for forming electrodes such as organic EL displays and FEDs (surface emission displays), a biological organic matter ejection device used for manufacturing biochips, a three-dimensional shaping device, a printing device, and the like. Here, in the following description, the direction in which the medium P is conveyed may be referred to as the conveyance direction, and the width direction of the conveyed medium P may be referred to as the main scanning direction.

[0010] As shown in FIG. 1, the liquid ejection device 1 includes a control unit 2, a liquid container 3, a conveyance unit 4, and a plurality of ejection units 5.

[0011] The control unit 2 includes a processing circuit such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and a storage circuit such as a semiconductor memory. The control unit 2 outputs a signal for controlling each element of the liquid ejection device 1 based on image data supplied from an external device such as a host computer (not shown) provided outside the liquid ejection device 1.

[0012] The liquid container 3 stores ink as an example of the liquid supplied to the ejection unit 5. Specifically, the liquid container 3 stores inks of a plurality of colors ejected onto the medium P, for example, inks such as black, cyan, magenta, yellow, red, and gray.

[0013] The transport unit 4 includes a transport motor 41 and transport rollers 42. The transport unit 4 receives a transport control signal Ctrl-T output by the control unit 2. The transport motor 41 operates based on the transport control signal Ctrl-T. The transport rollers 42 rotate in conjunction with the operation of the transport motor 41. As a result, the medium P is transported along the transport direction.

[0014] Each of the multiple ejection units 5 has a head drive module 10 and a liquid ejection module 20. The ejection unit 5 receives an image information signal IP output by the control unit 2, and is also supplied with ink stored in the liquid container 3. The head drive module 10 controls the operation of the liquid ejection module 20 based on the input image information signal IP, and the liquid ejection module 20 ejects the ink supplied from the liquid container 3 onto the medium P. At this time, the liquid ejection modules 20 of each of the multiple ejection units 5 are positioned in a line along the main scanning direction so as to be greater than or equal to the width of the medium P, enabling ink to be ejected over the entire width of the transported medium P, thus configuring a line-type inkjet printer.

[0015] Here, the functional configuration of the dispensing unit 5 will be described. Figure 2 is a diagram showing an example of the functional configuration of the dispensing unit 5. As shown in Figure 2, the dispensing unit 5 has a head drive module 10 and a liquid dispensing module 20.

[0016] The head drive module 10 and the liquid discharge module 20 of the discharge unit 5 are electrically connected via a wiring member 30. For example, flexible printed circuits (FPCs) or flexible flat cables (FFCs) can be used as this wiring member 30. Alternatively, the head drive module 10 and the liquid discharge module 20 may be electrically connected via a BtoB (Board to Board) connector instead of, or in addition to, the FPCs or FFCs mentioned above. That is, in addition to the FPCs and FFCs mentioned above, the wiring member 30 may also be a BtoB (Board to Board) connector. The board may include connecting components such as connectors.

[0017] The head drive module 10 includes a control circuit 100, drive signal output circuits 50-1 to 50-m, and a conversion circuit 120.

[0018] The control circuit 100 includes a CPU, FPGA, etc. The control circuit 100 receives the image information signal IP output by the control unit 2. Based on the input image information signal IP, the control circuit 100 outputs signals to control each element of the output unit 5.

[0019] Specifically, the control circuit 100 generates voltage change data dDATA for controlling the operation of the liquid dispensing module 20 based on the image information signal IP, and outputs it to the conversion circuit 120. The conversion circuit 120 converts the voltage change data dDATA into a differential signal such as LVDS (Low Voltage Differential Signaling) and outputs it to the liquid dispensing module 20 as a data signal DATA. Alternatively, the conversion circuit 120 may convert the voltage change data dDATA into a differential signal of a high-speed transfer method other than LVDS, such as LVPECL (Low Voltage Positive Emitter Coupled Logic) or CML (Current Mode Logic), and output it to the liquid dispensing module 20 as a data signal DATA. Furthermore, the conversion circuit 120 may output part or all of the input voltage change data dDATA to the liquid dispensing module 20 as a single-ended data signal DATA.

[0020] Furthermore, the control circuit 100 outputs digital waveform signals dA1 and dB1 to the drive signal output circuit 50-1. The drive signal output circuit 50-1 has drive circuits 52a and 52b. The digital waveform signal dA1 is input to drive circuit 52a. Drive circuit 52a converts the input digital waveform signal dA1 from digital to analog, then amplifies it in class AB to generate the drive signal COMA1, which is output to the liquid discharge module 20. The digital waveform signal dB1 is input to drive circuit 52b. Drive circuit 52b converts the input digital waveform signal dB1 from digital to analog, then amplifies it in class AB to generate the drive signal COMB1, which is output to the liquid discharge module 20. In other words, the digital waveform signals dA1 and dB1 are digital signals that define the signal waveforms of the drive signals COMA1 and COMB1, and the drive circuits 52a and 52b generate and output the drive signals COMA1 and COMB1 by amplifying the signal waveforms defined by the digital waveform signals dA1 and dB1.

[0021] Furthermore, the drive signal output circuit 50-1 has a reference voltage output circuit 53. The reference voltage output circuit 53 generates a constant potential reference voltage signal VBS1 that indicates the reference potential of the piezoelectric element 60, which will be described later, located in the liquid discharge module 20, and outputs it to the liquid discharge module 20. This reference voltage signal VBS1 may be, for example, the ground potential, or it may be a constant potential such as 5.5V or 6V. Note that the constant potential includes cases where the potential can be considered to be approximately constant when errors such as potential fluctuations caused by the operation of peripheral circuits, potential fluctuations caused by variations in circuit elements, and potential fluctuations caused by the temperature characteristics of circuit elements are taken into account.

[0022] The drive signal output circuits 50-2 to 50-m have the same configuration as the drive signal output circuit 50-1, except that the input signals and output signals are different. That is, the drive signal output circuit 50-j (where j is one of 1 to m) includes circuits corresponding to drive circuits 52a and 52b and a circuit corresponding to the reference voltage output circuit 53. The circuits corresponding to drive circuits 52a and 52b generate drive signals COMAj and COMBj based on the digital waveform signals dAj and dBj input from the control circuit 100 and output them to the liquid discharge module 20, while the circuit corresponding to the reference voltage output circuit 53 generates a reference voltage signal VBSj and outputs it to the liquid discharge module 20.

[0023] The liquid discharge module 20 includes a restoration circuit 220 and discharge modules 23-1 to 23-m.

[0024] The data signal DATA output by the conversion circuit 120 is input to the restoration circuit 220. The restoration circuit 220 restores the input data signal DATA into a single-ended signal, separates it into signals corresponding to each of the output modules 23-1 to 23-m, and outputs them to the corresponding output modules 23-1 to 23-m.

[0025] Specifically, the restoration circuit 220 restores and separates the data signal DATA to generate the clock signal SCK1, print data signal SI1, and latch signal LAT1 corresponding to the ejection module 23-1, and outputs them to the ejection module 23-1. In addition, the restoration circuit 220 restores and separates the data signal DATA to generate the clock signal SCKj, print data signal SIj, and latch signal LATj corresponding to the ejection module 23-j, and outputs them to the ejection module 23-j.

[0026] In other words, the restoration circuit 220 restores the differential signal DATA output by the head drive module 10 and separates the restored signal into signals corresponding to the ejection modules 23-1 to 23-m. As a result, the restoration circuit 220 separates the clock signals SCK1 to SCKm and the print data signals SI1 to 23-m, respectively, corresponding to the ejection modules 23-1 to 23-m. The SIm and latch signals LAT1 to LATm are generated and output to the corresponding ejection modules 23-1 to 23-m. Note that one of the clock signals SCK1 to SCKm, print data signals SI1 to SIm, and latch signals LAT1 to LATm, which are output by the restoration circuit 220 and correspond to each of the ejection modules 23-1 to 23-m, may be a common signal for the ejection modules 23-1 to 23-m.

[0027] Considering that the restoration circuit 220 restores and separates the data signal DATA to generate the clock signals SCK1~SCKm, the print data signals SI1~SIm, and the latch signals LAT1~LATm, the data signal DATA output by the control circuit 100 is a differential signal corresponding to the clock signals SCK1~SCKm, the print data signals SI1~SIm, and the latch signals LAT1~LATm. Furthermore, the voltage change amount data dDATA, which is the basis of the data signal DATA, contains signals corresponding to the clock signals SCK1~SCKm, the print data signals SI1~SIm, and the latch signals LAT1~LATm, respectively. In other words, the voltage change amount data dDATA contains signals that control the operation of the discharge modules 23-1~23-m of the liquid discharge module 20. The ejection unit 5 may also be configured without a conversion circuit 120 and a restoration circuit 220, with the control circuit 100 outputting clock signals SCK1 to SCKm, print data signals SI1 to SIm, and latch signals LAT1 to LATm, respectively.

[0028] The discharge module 23-1 includes a drive signal selection circuit 200 and a plurality of discharge units 600. Each of the plurality of discharge units 600 also includes a piezoelectric element 60.

[0029] The ejection module 23-1 receives the drive signals COMA1 and COMB1 and the reference voltage signal VBS1 output by the drive signal output circuit 50-1, as well as the clock signal SCK1, the print data signal SI1, and the latch signal LAT1 output by the restoration circuit 220. The drive signals COMA1 and COMB1, the clock signal SCK1, the print data signal SI1, and the latch signal LAT1 are input to the drive signal selection circuit 200 of the ejection module 23-1. Based on the input clock signal SCK1, the print data signal SI1, and the latch signal LAT1, the drive signal selection circuit 200 generates the drive signal VOUT by selecting or deselecting the signal waveforms contained in each of the drive signals COMA1 and COMB1, and supplies it to one end of the piezoelectric element 60 of the corresponding ejection unit 600. At this time, the reference voltage signal VBS1 is supplied to the other end of the piezoelectric element 60. Then, 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, causing ink to be ejected from the corresponding ejection unit 600.

[0030] Discharge modules 23-2 to 23-m have the same configuration as discharge module 23-1, except that the input and output signals are different. Specifically, discharge module 23-j has a drive signal selection circuit 200 and a plurality of discharge units 600, each of which includes a piezoelectric element 60. Discharge module 23-j receives drive signals COMAj, COMBj, a reference voltage signal VBSj, a clock signal SCKj, a print data signal SIj, and a latch signal LATj as inputs. The drive signal selection circuit 200 generates a drive signal VOUT by selecting or deselecting the signal waveforms included in each of the drive signals COMAj, COMBj, based on the input clock signal SCKj, print data signal SIj, and latch signal LATj, and supplies it to one end of the piezoelectric element 60 of the corresponding discharge unit 600. At this time, the reference voltage signal VBSj is supplied to the other end of the piezoelectric element 60. Then, 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, causing ink to be ejected from the corresponding ejection unit 600.

[0031] As described above, the liquid dispensing device 1 of this embodiment has a control unit 2 which is a host computer (not shown). Based on image data supplied from a computer or the like, the transport unit 4 controls the transport of the medium P and controls the ejection of ink from the liquid ejection module 20 of the ejection unit 5, thereby causing a desired amount of ink to land at a desired position on the medium P and forming a desired image on the medium P. Specifically, the liquid ejection device 1 comprises a liquid ejection module 20 having ejection modules 23-1 to 23-m that eject ink by driving a piezoelectric element 60, and a head drive module 10 having drive signal output circuits 50-1 to 50-m that output drive signals COMA1 to COMAm and COMB1 to COMBm that drive the piezoelectric element 60.

[0032] Here, if the drive signal output circuits 50-1 to 50-m have similar configurations and there is no need to distinguish between them, they may be simply referred to as drive signal output circuit 50 in the following explanation. Also, if there is no need to distinguish between drive circuits 52a and 52b included in drive signal output circuits 50-1 to 50-m, they may be simply referred to as drive circuit 52 in the following explanation. In this case, drive circuit 52 is input with digital waveform signals dO as digital waveform signals dA1 to dAm and dB1 to dBm, and drive circuit 52 generates and outputs drive signals COM as drive signals COMA1 to COMAm and COMB1 to COMBm based on the input digital waveform signals dO. On the other hand, if drive circuits 52a and 52b included in drive signal output circuits 50-1 to 50-m are to be distinguished and explained, then in the following explanation, drive circuits 52a and 52b included in drive signal output circuit 50-j may be referred to as drive circuits 52aj and 52bj.

[0033] Furthermore, if the reference voltage output circuits 53 included in each of the drive signal output circuits 50-1 to 50-m have similar configurations and there is no need to distinguish between them, they may be simply referred to as reference voltage output circuits 53 in the following explanation. In this case, the reference voltage output circuits 53 will be described as generating and outputting reference voltage signals VBS as reference voltage signals VBS1 to VBSm. On the other hand, if the reference voltage output circuits 53 included in each of the drive signal output circuits 50-1 to 50-m are to be described separately, the reference voltage output circuit 53 included in the drive signal output circuit 50-j may be referred to as reference voltage output circuit 53-j in the following explanation.

[0034] Furthermore, since ejection modules 23-1 to 23-m have similar configurations and do not need to be distinguished, they may be simply referred to as ejection module 23 in the following description. In this case, the ejection module 23 will be described assuming that it receives the following inputs: clock signals SCK1 to SCKm, print data signals SI1 to SIm, latch signals LAT1 to LATm, drive signals COMA1 to COMAm, drive signals COMB1 to COMBm, and reference voltage signals VBS1 to VBSm.

[0035] Here, an example of the structure of a discharge section 600 in the discharge module 23 will be described. Figure 3 shows a schematic structure of one of the multiple discharge sections 600 in the discharge module 23. As shown in Figure 3, the discharge section 600 includes a piezoelectric element 60, a diaphragm 621, a cavity 631, and a nozzle 651.

[0036] Cavity 631 is filled with ink supplied from reservoir 641. In addition, ink is introduced into reservoir 641 from liquid container 3 via an ink tube (not shown) and supply port 661. In other words, cavity 631 is filled with ink stored in the corresponding liquid container 3.

[0037] The diaphragm 621 is displaced by the drive of the piezoelectric element 60 located on its upper surface in Figure 3. As the diaphragm 621 is displaced, the internal volume of the cavity 631, where the ink is filled, expands and contracts. In other words, the diaphragm 621 functions as a diaphragm that changes the internal volume of the cavity 631.

[0038] The nozzle 651 is provided on the nozzle plate 632 and is an opening that communicates with the cavity 631. As the internal volume of the cavity 631 changes, an amount of ink corresponding to the change in internal volume is ejected from the nozzle 651.

[0039] The piezoelectric element 60 has a structure in which a piezoelectric body 601 is sandwiched between a pair of electrodes 611 and 612. In this structure, the piezoelectric body 601, along with the diaphragm 621, flexes vertically in accordance with the potential difference of the signal supplied to the electrodes 611 and 612. An amount of ink is ejected in accordance with the deformation of the piezoelectric element 60 and the diaphragm 621.

[0040] Specifically, a drive signal VOUT is supplied to one end of the piezoelectric element 60, to either electrode 611 or electrode 612, and a reference voltage signal VBS is supplied to the other end of the piezoelectric element 60, to the other electrode 611 or electrode 612. When the voltage value of the drive signal VOUT increases, the piezoelectric element 60 bends upward. As the piezoelectric element 60 bends upward, the diaphragm 621 is displaced, and the internal volume of the cavity 631 expands. As a result, ink is drawn in from the reservoir 641. On the other hand, when the voltage value of the drive signal VOUT decreases, the piezoelectric element 60 bends downward. As the piezoelectric element 60 bends downward, the diaphragm 621 is displaced, and the internal volume of the cavity 631 shrinks. As a result, an amount of ink corresponding to the degree of shrinkage is ejected from the nozzle 651. In other words, the ejection unit 600 includes a piezoelectric element 60 that is driven by a drive signal VOUT based on a drive signal COM, and ink is ejected when the piezoelectric element 60 is driven.

[0041] Furthermore, the structure of the piezoelectric element 60 is not limited to the bending vibration structure shown in Figure 3, as long as it is a structure that can eject ink from the ejection unit 600 when driven. For example, a structure using longitudinal vibration may also be used. In addition, the piezoelectric element 60 may be configured to bend downward when the voltage value of the drive signal VOUT increases and bend upward when the voltage value of the drive signal VOUT decreases.

[0042] 2. Functional configuration of the drive signal selection circuit Next, the configuration and operation of the drive signal selection circuit 200 of the discharge module 23 will be described. In order to describe the configuration and operation of the drive signal selection circuit 200 of the discharge module 23, first, an example of the signal waveforms included in the drive signals COMA and COMB input to the drive signal selection circuit 200 will be described.

[0043] Figure 4 shows an example of the signal waveforms of drive signals COMA and COMB. As shown in Figure 4, drive signal COMA includes a drive waveform Adp that is timed to the period T from when latch signal LAT rises until when latch signal LAT rises again. Drive waveform Adp is a signal waveform that, when supplied to one end of the piezoelectric element 60, causes a predetermined amount of ink to be ejected from the ejection unit 600 corresponding to the piezoelectric element 60. Drive signal COMB includes a drive waveform Bdp that is timed to the period T. Drive waveform Bdp is a signal waveform with a voltage amplitude smaller than that of drive waveform Adp, and when supplied to one end of the piezoelectric element 60, causes a smaller amount of ink than a predetermined amount to be ejected from the ejection unit 600 corresponding to the piezoelectric element 60. Furthermore, the voltage values ​​of drive waveforms Adp and Bdp at their respective start and end timings are both the same voltage Vc. That is, drive waveforms Adp and Bdp are signal waveforms that start and end at voltage Vc, respectively.

[0044] In the following explanation, when the drive waveform Adp is supplied to one end of the piezoelectric element 60, the amount of ink ejected from the ejection unit 600 corresponding to the piezoelectric element 60 may be referred to as a large amount, and when the drive waveform Bdp is supplied to one end of the piezoelectric element 60, the amount of ink ejected from the ejection unit 600 corresponding to the piezoelectric element 60 may be referred to as a small amount.

[0045] The signal waveforms included in the drive signals COMA and COMB are not limited to those exemplified in Figure 4. Various signal waveforms may be used depending on the type of ink ejected from the ejection unit 600, the number of piezoelectric elements 60 driven by the drive signals COMA and COMB, the wiring length through which the drive signals COMA and COMB propagate, etc. For example, drive signals COMA1 to COMAm may each contain different signal waveforms, and drive signals COMB1 to COMBm may each contain different signal waveforms. Also, for example, each of the drive signals COMA and COMB may contain two or more consecutive drive waveforms in period T. In this case, a signal defining the switching timing of two or more drive waveforms is input to the drive signal selection circuit 200, and the ejection unit 600 ejects ink multiple times in period T. The ink ejected in multiple stages in period T lands on the medium P and combines, forming a single dot on the medium P. Furthermore, for example, the drive signals COMA and COMB are signal waveforms that cause the ink near the opening of the nozzle 651 to vibrate in order to reduce the risk of the viscosity of the ink near the opening of the nozzle 651 increasing, and may include so-called micro-vibration waveforms.

[0046] In the following explanation, the period T from when one latch signal LAT rises until the next latch signal LAT rises is sometimes referred to as the dot formation period, which forms dots of a desired size on the medium P.

[0047] Next, the configuration and operation of the drive signal selection circuit 200, which generates and outputs the drive signal VOUT by selecting or deselecting the signal waveforms contained in the respective drive signals COMA and COMB, will be described. Figure 5 is a diagram showing the functional configuration of the drive signal selection circuit 200. As shown in Figure 5, the drive signal selection circuit 200 includes a selection control circuit 210 and a plurality of selection circuits 230. Hereinafter, the description will assume that the discharge module 23 has n discharge units 600 as a plurality of discharge units 600.

[0048] The selection control circuit 210 receives the print data signal SI, the latch signal LAT, and the clock signal SCK as inputs. The selection control circuit 210 also has a set of shift register (S / R) 212, latch circuit 214, and decoder 216 corresponding to each of the n ejection units 600. That is, the drive signal selection circuit 200 includes n shift registers 212, n latch circuits 214, and n decoders 216, the same number as the total number of ejection units 600.

[0049] The print data signal SI is a signal synchronized with the clock signal SCK and includes 2 bits of print data [SIH,SIL] to define the dot size formed by the ink ejected from each of the n ejection units 600 as either "large dot LD", "small dot SD", or "non-ejected ND". This print data signal SI is held in a shift register 212 corresponding to the ejection unit 600 for each 2 bits of print data [SIH,SIL].

[0050] Specifically, the n shift registers 212 corresponding to the ejection unit 600 are connected in cascaded order. The serially input print data signal SI is sequentially transferred to the downstream of the cascaded shift registers 212 according to the clock signal SCK. When the supply of the clock signal SCK stops, the n shift registers 212 hold 2 bits of print data [SIH, SIL] corresponding to the ejection unit 600 that corresponds to that shift register 212. In Figure 5, to distinguish between the n cascaded shift registers 212, they are labeled as 1st stage, 2nd stage, ..., nth stage from the upstream side where the print data signal SI is input to the downstream side.

[0051] Each of the n latch circuits 214 simultaneously latches the 2-bit print data [SIH, SIL] held in the corresponding shift register 212 on the rising edge of the latch signal LAT. ru.

[0052] Each of the n decoders 216 decodes the 2-bit print data [SIH,SIL] latched by the corresponding latch circuit 214 and outputs logic level selection signals S1 and S2 according to the decoded content at each period T. Figure 6 shows an example of the decoded content in decoder 216. Decoder 216 outputs logic level selection signals S1 and S2 defined by the latched 2-bit print data [SIH,SIL] and the decoded content shown in Figure 6. For example, if the 2-bit print data [SIH,SIL] = [1,0] latched by the corresponding latch circuit 214, decoder 216 sets the logic levels of selection signals S1 and S2 to L and H levels, respectively, at period T. Note that in Figure 6, print data [SIH,SIL] = [0,0] and print data [SIH,SIL] = [0,1] are collectively shown as print data [SIH,SIL] = [0,*].

[0053] The selection circuit 230 is provided in correspondence to each of the n output units 600. That is, the drive signal selection circuit 200 has n selection circuits 230. The selection circuit 230 receives the selection signals S1 and S2 output by the decoder 216 corresponding to the same output unit 600, and the drive signals COMA and COMB. The selection circuit 230 then generates a drive signal VOUT by selecting or deselecting the signal waveforms contained in the respective drive signals COMA and COMB according to the selection signals S1 and S2, and outputs it to the corresponding output unit 600.

[0054] Figure 7 shows an example of the configuration of a selection circuit 230 corresponding to one discharge unit 600. As shown in Figure 7, the selection circuit 230 has inverters 232a, 232b and transfer gates 234a, 234b.

[0055] The selection signal S1 is input to the positive control terminal of the transfer gate 234a that is not marked with a circle, while the inverter 232a logically inverts it and inputs it to the negative control terminal of the transfer gate 234a that is marked with a circle. In addition, the drive signal COMA is supplied to the input terminal of the transfer gate 234a. When the input selection signal S1 is at a high level, the transfer gate 234a conducts between its input terminal and output terminal, and when the input selection signal S1 is at a low level, the input terminal and output terminal do not conduct. That is, the transfer gate 234a outputs the drive signal COMA to its output terminal when the selection signal S1 is at a high level, and does not output the drive signal COMA to its output terminal when the selection signal S1 is at a low level.

[0056] The selection signal S2 is input to the positive control terminal of the transfer gate 234b that is not marked with a circle, while the inverter 232b logically inverts it and inputs it to the negative control terminal of the transfer gate 234b that is marked with a circle. In addition, the drive signal COMB is supplied to the input terminal of the transfer gate 234b. When the input selection signal S2 is at a high level, the transfer gate 234b conducts between its input terminal and output terminal, and when the input selection signal S2 is at a low level, it does not conduct between its input terminal and output terminal. That is, the transfer gate 234b outputs the drive signal COMB to its output terminal when the selection signal S2 is at a high level, and does not output the drive signal COMB to its output terminal when the selection signal S2 is at a low level.

[0057] The output terminals of transfer gates 234a and 234b are connected in common. Drive signals COMA and COMB, selected or unselected by selection signals S1 and S2, are supplied to the output terminals of these commonly connected transfer gates 234a and 234b. The selection circuit 230 outputs the signal supplied to these commonly connected output terminals as a drive signal VOUT to the corresponding discharge unit 600.

[0058] The operation of the drive signal selection circuit 200 will now be explained. Figure 8 is a diagram illustrating the operation of the drive signal selection circuit 200. The print data signal SI is input serially in synchronization with the clock signal SCK and is transferred sequentially by the shift register 212 corresponding to the ejection unit 600. When the input of the clock signal SCK stops, the 2-bit print data [SIH, SIL] corresponding to each of the ejection units 600 is held in the corresponding shift register 212.

[0059] Subsequently, when the latch signal LAT rises, the 2-bit print data [SIH,SIL] held in the shift register 212 is simultaneously latched by the latch circuit 214. Figure 8 shows the 2-bit print data [SIH,SIL] corresponding to the 1st, 2nd, ..., nth stages of the shift register 212 latched by the latch circuit 214 as LT1, LT2, ..., LTn.

[0060] The decoder 216 outputs logic level selection signals S1 and S2 according to the dot size defined by the latched 2-bit print data [SIH, SIL].

[0061] Specifically, when the print data [SIH,SIL]=[1,1], the decoder 216 outputs the logic levels of selection signals S1 and S2 as H and L levels to the selection circuit 230 during period T. As a result, the selection circuit 230 selects the drive waveform Adp during period T and outputs the drive signal VOUT corresponding to the "large dot LD". Also, when the print data [SIH,SIL]=[1,0], the decoder 216 outputs the logic levels of selection signals S1 and S2 as L and H levels to the selection circuit 230 during period T. As a result, the selection circuit 230 selects the drive waveform Bdp during period T and outputs the drive signal VOUT corresponding to the "small dot SD". Furthermore, when the print data [SIH,SIL]=[0,1] and when the print data [SIH,SIL]=[0,0], the decoder 216 outputs the logic levels of the selection signals S1 and S2 as L, L levels to the selection circuit 230 during period T. As a result, the selection circuit 230 does not select either the drive waveform Adp or Bdp during period T, and outputs a drive signal VOUT corresponding to a constant voltage Vc "non-output ND".

[0062] Here, if the selection circuit 230 does not select either the drive waveform Adp or Bdp, the voltage Vc that was supplied to the piezoelectric element 60 immediately before is held at one end of the corresponding piezoelectric element 60 by the capacitance component of the piezoelectric element 60. In other words, when the selection circuit 230 outputs a constant drive signal VOUT with voltage Vc, it includes the case where neither the drive waveform Adp nor Bdp is selected as the drive signal VOUT, and the voltage Vc that was held immediately before is supplied to the piezoelectric element 60 by the capacitance component of the piezoelectric element 60 as the drive signal VOUT.

[0063] As described above, the drive signal selection circuit 200 selects or deselects the drive signals COMA and COMB based on the print data signal SI, the latch signal LAT, and the clock signal SCK, thereby generating a drive signal VOUT corresponding to each of the multiple ejection units 600 and outputting it to the corresponding ejection unit 600. This allows for individual control of the amount of ink ejected from each of the multiple ejection units 600.

[0064] 3. Drive Circuit Configuration Next, the configuration and operation of the drive circuit 52, which outputs drive signals COMA and COMB, will be described. Figure 9 shows an example of the configuration of the drive circuit 52. As shown in Figure 9, the drive circuit 52 has an amplification control circuit 510, a drive circuit 520, and an amplification circuit 530.

[0065] The amplification control circuit 510 includes a memory 511, a latch circuit 512, an adder 513, a latch circuit 514, and a D / A converter 515. The amplification control circuit 510 also receives voltage change data dDATA and latch signals as digital waveform signals dO output by the control circuit 100. The signal dLAT and the clock signal dCK are input.

[0066] The voltage change data dDATA is input to memory 511. Memory 511 holds the voltage change information Dv contained in the input voltage change data dDATA. The latch signal dLAT is input to latch circuit 512. At the rising edge of the input latch signal dLAT, latch circuit 512 latches the voltage change information Dv held in memory 511. Then, latch circuit 512 outputs the latched voltage change information Dv to adder 513.

[0067] The adder 513 receives not only the voltage change amount information Dv output by the latch circuit 512, but also the signal output by the latch circuit 514, which will be described later. The adder 513 calculates and stores the summed voltage change amount information by adding the voltage change amount information Dv to the signal output by the latch circuit 514.

[0068] The clock signal dCK is input to the latch circuit 514. The latch circuit 514 latches the summation voltage change amount information held by the adder 513 at the rising edge of the clock signal dCK. The latch circuit 514 then outputs the latched summation voltage change amount information to the adder 513 and the D / A converter 515. In other words, the adder 513 calculates and holds new summation voltage change amount information by adding the voltage change amount information Dv latched by the latch circuit 512 to the summation voltage change amount information latched by the latch circuit 514.

[0069] The D / A converter 515 converts the summation voltage change information output by the latch circuit 514 into an analog signal and outputs it to the drive circuit 520 as a drive waveform signal WS. The drive waveform signal WS output by the D / A converter 515, when amplified from the voltage value of the drive waveform signal WS output by the amplification control circuit 510, corresponds to the signal waveform of the drive signal COM.

[0070] Here, we will explain the operation of the amplification control circuit 510 that outputs the drive waveform signal WS. Figure 10 is a diagram showing an example of the operation of the amplification control circuit 510. As shown in Figure 10, at time t0, the control circuit 100 generates voltage change amount data dDATA, which includes voltage change amount information Dv1 for changing the voltage value by voltage ΔV1, as a digital waveform signal dO, and outputs it to the memory 511. As a result, the voltage change amount information Dv1 is stored in the memory 511.

[0071] Then, at time t1, the control circuit 100 sets the logic level of the latch signal dLAT, which is a digital waveform signal dO, to high. As a result, the voltage change amount information Dv1 held in memory 511 is latched by the latch circuit 512. Subsequently, at time t3, the control circuit 100 outputs voltage change amount data dDATA, which includes voltage change amount information Dv0 for maintaining a constant voltage value, as a digital waveform signal dO to memory 511. In other words, memory 511 now holds voltage change amount information Dv0 instead of voltage change amount information Dv1.

[0072] At time t1, the voltage change amount information Dv1 latched by the latch circuit 512 is input to the adder 513. The adder 513 adds the voltage change amount information Dv1 latched by the latch circuit 512 to the added voltage change amount information output by the latch circuit 514 and stores it as new added voltage change amount information.

[0073] Furthermore, the control circuit 100 generates a clock signal dCK as a digital waveform signal dO, which is at an H level every period ΔT, and outputs it to the latch circuit 514. Then, at times t2, t4, and t5, when an H-level clock signal dCK is input to the latch circuit 514, the latch circuit 514 latches information on the summation voltage change amount, where the voltage value has risen by voltage ΔV1 each time an H-level clock signal dCK is input, and outputs it to the D / A converter 515. Therefore, the D / A converter 515 generates and outputs a drive waveform signal WS at times t2, t4, and t5, in which the voltage value increases by voltage ΔV1.

[0074] At the time t6, the control circuit 100 sets the logic level of the latch signal dLAT, which is a digital waveform signal dO, to high. As a result, the voltage change amount information Dv0, which is necessary to keep the voltage value held in memory 511 constant, is latched by the latch circuit 512. Then, at the time t8, the control circuit 100 generates voltage change amount data dDATA, which is a digital waveform signal dO, and includes voltage change amount information Dv2, which is necessary to change the voltage value by voltage -ΔV2, and outputs it to memory 511. In other words, memory 511 now holds voltage change amount information Dv2 instead of voltage change amount information Dv0.

[0075] The voltage change amount information Dv0 latched by the latch circuit 512 is input to the adder 513. The adder 513 adds the voltage change amount information Dv0 latched by the latch circuit 512 to the added voltage change amount information output by the latch circuit 514 and stores it as new added voltage change amount information.

[0076] Furthermore, at times t7 and t9, a high-level clock signal dCK is input to the latch circuit 514. At this time, the voltage change amount information Dv0 latched by the latch circuit 512 is information for maintaining a constant voltage value. Therefore, even when a high-level clock signal dCK is input, the latch circuit 514 latches the summation voltage change amount information, which does not change the voltage value, and outputs it to the D / A converter 515. As a result, the D / A converter 515 generates and outputs a drive waveform signal WS with a constant voltage value at times t7 and t9.

[0077] Then, at time t10, the control circuit 100 sets the logic level of the latch signal dLAT to high as the digital waveform signal dO. As a result, the voltage change amount information Dv2, which causes the voltage value held in memory 511 to change by voltage -ΔV2, is latched by the latch circuit 512.

[0078] The voltage change amount information Dv2 latched by the latch circuit 512 is input to the adder 513. The adder 513 then adds the voltage change amount information Dv2 latched by the latch circuit 512 to the added voltage change amount information output by the latch circuit 514 and stores it as new added voltage change amount information.

[0079] Furthermore, the control circuit 100 generates a clock signal dCK as a digital waveform signal dO, which is at an H level every period ΔT, and outputs it to the latch circuit 514. Then, at times t11 and t12, when an H-level clock signal dCK is input to the latch circuit 514, the latch circuit 514 latches summation voltage change information, in which the voltage value decreases by voltage ΔV2 each time an H-level clock signal dCK is input, and outputs it to the D / A converter 515. As a result, the D / A converter 515 generates and outputs a drive waveform signal WS at times t11 and t12, in which the voltage value decreases by voltage ΔV2.

[0080] As described above, the amplification control circuit 510 outputs a drive waveform signal WS with an increasing voltage value, a drive waveform signal WS with a decreasing voltage value, and a drive waveform signal WS with a constant voltage value, based on the digital waveform signal dO. In other words, the amplification control circuit 510 can output a drive waveform signal WS with a signal waveform corresponding to the digital waveform signal dO output by the control circuit 100.

[0081] Here, in the liquid dispensing device 1 of this embodiment, the voltage change amount data dDATA included in the digital waveform signal dO input to the amplification control circuit 510 was described as data indicating the change in the voltage value of the drive waveform signal WS for each period of the clock signal dCK. The voltage change data dDATA included in the digital waveform signal dO may also be data that shows the absolute value of the voltage of the drive waveform signal WS for each period of the clock signal dCK.

[0082] By making the voltage change data dDATA included in the digital waveform signal dO data that shows the change in the voltage value of the drive waveform signal WS for each period of the clock signal dCK, it is possible to reduce the amount of data in the voltage change data dDATA included in the digital waveform signal dO, and as a result, the transmission speed of the voltage change data dDATA included in the digital waveform signal dO can be increased. On the other hand, if the voltage change data dDATA included in the digital waveform signal dO is data that shows the absolute value of the voltage value of the drive waveform signal WS for each period of the clock signal dCK, the amplification control circuit 510 does not need to have an adder 513 or a latch circuit 514, and as a result, the amplification control circuit 510 can be made smaller.

[0083] Returning to Figure 9, the drive circuit 520 receives the drive waveform signal WS output by the amplification control circuit 510 and a voltage signal Vamp with a predetermined voltage value input to the amplification circuit 530. Here, the voltage value of the voltage signal Vamp is greater than or equal to the maximum voltage value of the drive waveforms Adp and Bdp included in the drive signals COMA and COMB, for example, a DC voltage of 42V. The drive circuit 520 generates an amplified drive waveform signal by voltage amplified the voltage value of the input drive waveform signal WS based on the voltage signal Vamp. The waveform shape of this amplified drive waveform signal becomes the waveform shape of the drive waveforms Adp and Bdp included in the drive signals COMA and COMB. The drive circuit 520 then generates amplification control signals Hdr and Ldr based on the generated amplified drive waveform signal and outputs them to the amplification circuit 530.

[0084] Specifically, the drive circuit 520 generates an amplification control signal Hdr, which is obtained by adding a predetermined voltage bias voltage to the amplified drive waveform signal, and an amplification control signal Ldr, which is obtained by subtracting a predetermined voltage bias voltage from the amplified drive waveform signal, and outputs these to the amplifier circuit 530. Here, it is preferable that the voltage value of the bias voltage that the drive circuit 520 adds to the amplified drive waveform signal is determined according to the voltage value of the base-emitter saturation voltage of transistor 531 in the amplifier circuit 530 (described later), and the voltage value of the bias voltage that the drive circuit 520 subtracts from the amplified drive waveform signal is determined according to the voltage value of the base-emitter saturation voltage of transistor 532 in the amplifier circuit 530 (described later). This reduces the risk of distortion occurring in the signal waveform of the drive signal COM output by the drive circuit 52. Such a drive circuit 520 is configured to include, for example, an operational amplifier that voltage-amplifies the voltage value of the drive waveform signal WS based on a voltage signal Vamp.

[0085] The amplification circuit 530 includes transistors 531 and 532. Transistor 531 is an NPN bipolar transistor, and transistor 532 is a PNP bipolar transistor. In this case, it is preferable that transistors 531 and 532 form a complementary pair.

[0086] The collector terminal of transistor 531 is input to a voltage signal Vamp. The base terminal of transistor 531 is input to an amplification control signal Hdr. The emitter terminal of transistor 531 is electrically connected to the emitter terminal of transistor 532. The base terminal of transistor 532 is input to an amplification control signal Ldr. The collector terminal of transistor 532 is input to ground potential Gnd. The amplification circuit 530 outputs the signal at the connection point Cout, where the emitter terminals of transistor 531 and transistor 532 are connected, as the drive signal COM.

[0087] In such an amplification circuit 530, when the voltage value of the drive waveform signal WS increases, and the voltage value of the amplified drive waveform signal generated by the drive circuit 520 increases, the transistor The collector terminal and emitter terminal of transistor 531 are controlled to conduct, and the emitter terminal and collector terminal of transistor 532 are controlled to not conduct. As a result, the multiple piezoelectric elements 60 connected to connection point Cout are supplied with current based on the voltage signal Vamp via transistor 531. Consequently, the capacitive component of the piezoelectric elements 60 causes the voltage value at connection point Cout, which is the voltage value of the drive signal COM output by the amplification circuit 530, to rise in accordance with the voltage value of the amplified drive waveform signal generated by the drive circuit 520.

[0088] Furthermore, if the voltage value of the drive waveform signal WS decreases, and the voltage value of the amplified drive waveform signal generated by the drive circuit 520 decreases, the collector terminal and emitter terminal of transistor 531 are controlled to be non-conductive, and the emitter terminal and collector terminal of transistor 532 are controlled to be conductive. As a result, the charge stored in the multiple piezoelectric elements 60 connected to connection point Cout is released to ground potential Gnd via transistor 532. Consequently, the voltage value of connection point Cout, which is the voltage value of the drive signal COM output by the amplifier circuit 530, decreases to follow the voltage value of the amplified drive waveform signal generated by the drive circuit 520.

[0089] Furthermore, when the voltage value of the drive waveform signal WS is constant, and the voltage value of the amplified drive waveform signal generated by the drive circuit 520 is constant, the collector terminal and emitter terminal of transistor 531 are controlled to be non-conductive, and the emitter terminal and collector terminal of transistor 532 are controlled to be non-conductive. As a result, the voltage value at connection point Cout, which is the voltage value of the drive signal COM output by the amplifier circuit 530, is maintained by the capacitive component of the piezoelectric element 60 connected to connection point Cout. That is, the voltage value at connection point Cout, which is the voltage value of the drive signal COM output by the amplifier circuit 530, is maintained at a voltage value equivalent to the voltage value of the amplified drive waveform signal generated by the drive circuit 520.

[0090] As described above, in the liquid dispensing device 1 of this embodiment, the drive circuit 52 includes an amplification control circuit 510, a drive circuit 520, and an amplification circuit 530. The amplification control circuit 510 outputs a drive waveform signal WS that defines the signal waveform of the drive signal COM based on a digital waveform signal dO, which is a digital signal. The drive circuit 520 generates an amplified drive waveform signal by voltage amplified from the drive waveform signal WS. The amplification circuit 530 then outputs the amplified drive waveform signal as a drive signal COM by current amplified from the amplified drive waveform signal. As a result, even when the dispensing module 23 has a large number of piezoelectric elements 60, the drive circuit 52 can output a drive signal COM that can supply a current amount sufficient to stably drive the large number of piezoelectric elements 60.

[0091] Specifically, the drive circuit 52a1 includes an amplification control circuit 510 that receives a digital waveform signal dA1 and outputs a drive waveform signal WS, and an amplification circuit 530 that amplifies the drive waveform signal WS and outputs a drive signal COMA1. The drive circuit 52b1 includes an amplification control circuit 510 that receives a digital waveform signal dB1 and outputs a drive waveform signal WS, and an amplification circuit 530 that amplifies the drive waveform signal WS and outputs a drive signal COMB1. Similarly, each of the drive circuits 52a2 to 52am has an amplification control circuit 510 that receives corresponding digital waveform signals dA2 to dAm as input and outputs a drive waveform signal WS, and an amplification circuit 530 that amplifies the drive waveform signal WS and outputs corresponding drive signals COMA2 to COMAm. Each of the drive circuits 52b2 to 52bm has an amplification control circuit 510 that receives corresponding digital waveform signals dB2 to dBm as input and outputs a drive waveform signal WS, and an amplification circuit 530 that amplifies the drive waveform signal WS and outputs corresponding drive signals COMB2 to COMBm. In other words, the head drive module 10 comprises a plurality of amplification control circuits 510 and a plurality of amplification circuits 530.

[0092] At this time, each of the multiple amplification circuits 530 in the head drive module 10 is The device includes ipolar transistors 531 and 532, and by driving transistors 531 and 532, it amplifies the drive waveform signal WS in class AB, thereby outputting a drive signal COM. In other words, each of the multiple amplification circuits 530 in the liquid discharge device 1 of this embodiment constitutes a class AB amplification circuit.

[0093] In this embodiment, the liquid dispensing device 1 includes a drive circuit 520 and an amplification control circuit 510, both of which are part of the drive circuit 52. This allows for miniaturization of the drive circuit 52. In this case, a portion of the circuits constituting the amplification control circuit 510 and the drive circuit 520 may be configured outside the integrated circuit 500. Furthermore, in this case, the amplification control circuit 510 and drive circuit 520 included in one of the multiple drive circuits 52 of the head drive module 10, and the amplification control circuit 510 and drive circuit 520 included in a different drive circuit 52, may be mounted on a single integrated circuit 500. In other words, the amplification control circuit 510 and drive circuit 520 included in the drive circuit 52a of the drive signal output circuit 50-j, and the amplification control circuit 510 and drive circuit 520 included in the drive circuit 52b of the drive signal output circuit 50-j, may be configured as a single integrated circuit 500, and the amplification control circuit 510 and drive circuit 520 included in the drive circuit 52a of the drive signal output circuit 50-1, and the amplification control circuit 510 and drive circuit 520 included in the drive circuit 52a of the drive signal output circuit 50-j, may be configured as a single integrated circuit 500. In this embodiment of the liquid discharge device 1, the explanation will be given by illustrating the case in which the amplification control circuit 510 and drive circuit 520 included in the drive circuit 52a of the drive signal output circuit 50-j, and the amplification control circuit 510 and drive circuit 520 included in the drive circuit 52b of the drive signal output circuit 50-j, are configured as a single integrated circuit 500.

[0094] 4. Structure of the head drive module In the drive circuit 52 configured as described above, if the number of piezoelectric elements 60 driven by the drive signal COM increases, the amount of current generated as the drive signal COM propagates increases, and the amount of heat generated increases. In particular, in a head drive module 10 having multiple drive circuits 52 as shown in the liquid ejection device 1 of this embodiment, because the multiple drive circuits 52 are arranged at high density, the heat generated in the multiple drive circuits 52 may concentrate, potentially causing a localized temperature rise. Such a temperature rise in the head drive module 10 may reduce the operational stability of the head drive module 10, which includes multiple drive circuits 52. If the operational stability of the head drive module 10 decreases, the operational stability of the liquid ejection module 20, whose operation is controlled by the head drive module 10, will also decrease, resulting in a decrease in the ink ejection accuracy from the liquid ejection module 20.

[0095] In the liquid ejection device 1 of this embodiment, the head drive module 10 has a distinctive configuration with excellent heat dissipation performance that can efficiently release the heat generated in the drive circuit 52, thereby addressing the aforementioned problem. This reduces the risk of the operational stability of the head drive module 10 decreasing due to heat generated in the multiple drive circuits 52. As a result, the risk of the operational stability of the liquid ejection module 20 decreasing is reduced, and the risk of the ink ejection accuracy from the liquid ejection module 20 decreasing is also reduced.

[0096] A specific example of the structure of the head drive module 10, which has excellent heat dissipation performance, will be described. Figure 11 is a diagram showing an example of the structure of the head drive module 10. Here, in the following description, the liquid discharge module 20 will be described as having six discharge modules 23, with discharge modules 23-1 to 23-6. Therefore, the head drive module 10 will be described as having drive signal output circuits 50-1 to 50-6 corresponding to each of the discharge modules 23-1 to 23-6. Furthermore, in the following description, the X, Y, and Z axes, which are orthogonal to each other, will be used. In this case, the starting point of the arrow along the X axis shown in the figure is - In some cases, the X side and the tip side are referred to as the +X side, the starting point of the arrow along the Y axis shown in the diagram is referred to as the -Y side and the tip side as the +Y side, and the starting point of the arrow along the Z axis shown in the diagram is referred to as the -Z side and the tip side as the +Z side.

[0097] As shown in Figure 11, the head drive module 10 includes a drive circuit board 800 and heat sinks 710 and 720.

[0098] The drive circuit board 800 includes a wiring board 810, connection parts CN1 and CN2 mounted on the wiring board 810, an integrated circuit 101, and various circuits including drive signal output circuits 50-1 to 50-6.

[0099] The heatsink 710 has a recess 711 that opens to the -Z side and is located on the +Z side of the drive circuit board 800, and the heatsink 720 has a recess 721 that opens to the -Z side and is located on the -Z side of the drive circuit board 800. The drive circuit board 800 is housed in the space formed by the recess 711 of the heatsink 710 and the recess 721 of the heatsink 720. In other words, the drive circuit board 800, which has a wiring board 810 and various circuits including connection parts CN1, CN2, integrated circuit 101, and drive signal output circuits 50-1 to 50-6 mounted on the wiring board 810, is housed in the space formed by the recess 711 of the heatsink 710 and the recess 721 of the heatsink 720. The drive circuit board 800 and the various circuits on the drive circuit board 800 are cooled by both the heatsink 710 and the heatsink 720. In other words, the heat sinks 710 and 720 together promote the cooling of the drive circuit board 800 and the various circuits contained within it. As a result, the heat generated in the drive circuit board 800 is efficiently dissipated. From the viewpoint of efficiently dissipating the heat generated in the drive circuit board 800, it is preferable that the heat sinks 710 and 720 be made of a metallic material with high thermal conductivity, such as aluminum, iron, or copper.

[0100] Furthermore, the heatsink 710 has an opening 712 that connects the +Z side surface to the recess 711, and a cooling fan 713 attached to the opening 712. The cooling fan 713 blows airflow into the recess 711 of the heatsink 710 through the opening 712. As a result, the cooling fan 713 promotes the cooling of the drive circuit board 800 housed in the space formed by the recess 711 and the recess 721. In other words, the heat dissipation performance of the heatsink 710 is higher than that of the heatsink 720 because it has a cooling fan 713. Here, the statement that the heat dissipation performance of heatsink 710 is higher than that of heatsink 720 is not limited to configurations using cooling fan 713, but also includes, for example, cases where the thermal conductivity of the material used for heatsink 710 is higher than that of the material used for heatsink 720, or where the area contributing to heat dissipation in heatsink 710 is larger than the area contributing to heat dissipation in heatsink 720, or where the heat capacity contributing to heat dissipation in heatsink 710 is larger than the heat capacity contributing to heat dissipation in heatsink 720.

[0101] As described above, the head drive module 10 is provided on the drive circuit board 800 and includes a plurality of amplification control circuits 510 and a plurality of amplification circuits 530 that are included in the drive signal output circuits 50-1 to 50-6 of the drive circuit board 800, and heat sinks 710 and 720 that help dissipate heat.

[0102] Here, a specific example of the structure of a drive circuit board 800, which includes a wiring board 810, connection parts CN1 and CN2 mounted on the wiring board 810, an integrated circuit 101, and drive signal output circuits 50-1 to 50-6, will be described. Figure 12 is a diagram showing an example of the structure of a drive circuit board 800. As shown in Figure 12, the drive circuit board 800 has a wiring board 810, drive signal output circuits 50-1 to 50-6, connection parts CN1 and CN2, and an integrated circuit 101.

[0103] The wiring board 810 is a substantially rectangular plate-like member that extends in the plane formed by the X and Y axes, and includes a side 811 extending along the Y axis, a side 812 located on the +X side of side 811 and extending along the Y axis, a side 813 intersecting sides 811 and 812 and extending along the X axis, and a side 814 located on the -Y side of side 813, intersecting sides 811 and 812 and extending along the X axis. The drive signal output circuits 50-1 to 50-6, connection parts CN1 and CN2, and integrated circuit 101 are mounted on this wiring board 810. In the following description, in the wiring board 810, which is a plate-like member that extends in the plane formed by the X and Y axes, the surface located on the +Z side will be referred to as surface 815, and the surface located on the -Z side will be referred to as surface 816. In other words, the head drive module 10 includes surfaces 815 and 816 that are positioned opposite each other along the Z-axis, and has a wiring board 810 on which amplification control circuits 510 and amplification circuits 530 are provided, which are included in the drive circuits 52a and 52b of each of the drive signal output circuits 50-1 to 50-6.

[0104] The connection part CN1 is provided on the surface 815 of the wiring board 810 and is located along the edge 811. A cable (not shown) that is electrically connected to the control unit 2 is attached to the connection part CN1. As a result, various signals, including the image information signal IP output by the control unit 2, are supplied to the head drive module 10 via the connection part CN1. Note that the connection part CN1 is not limited to a configuration on which a cable carrying various signals, including the image information signal IP, is attached; for example, it may be a BtoB connector that directly electrically connects the head drive module 10 and the control unit 2.

[0105] The connection part CN2 is provided on the surface 815 of the wiring board 810 and is located along the edge 812. One end of the wiring member 30 is attached to the connection part CN2. The other end of the wiring member 30 is connected to the liquid discharge module 20. As a result, various signals, including the drive signals COMA1~COMA6, COMB1~COMB6, and the data signal DATA output by the head drive module 10, are supplied to the liquid discharge module 20 via the connection part CN2.

[0106] The integrated circuit 101 is provided on surface 815 of the wiring board 810, located on the +X side of connection part CN1 and on the -X side of connection part CN2. Part or all of the above-described control circuit 100 is mounted on the integrated circuit 101. That is, the integrated circuit 101 receives the image information signal IP input via connection part CN1, and the integrated circuit 101 generates and outputs various signals based on the input image information signal IP. Here, in addition to the control circuit 100, part or all of the above-described conversion circuit 120 may also be mounted on the integrated circuit 101. In this embodiment of the liquid dispensing device 1, it will be explained assuming that the entirety of the control circuit 100 and the entirety of the conversion circuit 120 are mounted on the integrated circuit 101.

[0107] The drive signal output circuits 50-1 to 50-6 are located on the wiring board 810 between the integrated circuit 101 and the connection part CN2.

[0108] Specifically, drive signal output circuits 50-1 to 50-3 of the drive signal output circuits 50-1 to 50-6 are located between the integrated circuit 101 and the connector CN2, and are arranged along the X-axis from side 811 to side 812 in the order of drive signal output circuit 50-1, drive signal output circuit 50-2, and drive signal output circuit 50-3. Also, drive signal output circuits 50-4 to 50-6 of the drive signal output circuits 50-1 to 50-6 are located between the integrated circuit 101 and the connector CN2, and are arranged along the X-axis from side 811 to side 812 on the side 813 of drive signal output circuits 50-1 to 50-3 in the order of drive signal output circuit 50-4, drive signal output circuit 50-5, and drive signal output circuit 50-6.

[0109] In the drive signal output circuit 50-1, transistors 531 and 532 included in the drive circuit 52a are provided on the surface 815 of the wiring board 810, with transistor 531 on the side 811. Transistor 532 is positioned along the X-axis so that it faces side 812, and transistors 531 and 532 included in drive circuit 52b are provided on the surface 815 of the wiring board 810 on the +Y side of transistors 531 and 532 included in drive circuit 52a, and are positioned along the X-axis so that transistor 531 faces side 811 and transistor 532 faces side 812.

[0110] Furthermore, in the drive signal output circuit 50-1, the integrated circuit 500, on which the drive circuit 520 and amplification control circuit 510 included in drive circuit 52a and the drive circuit 520 and amplification control circuit 510 included in drive circuit 52b are mounted, is located between transistors 531 and 532 included in drive circuit 52a of the drive signal output circuit 50-1, and between transistors 531 and 532 included in drive circuit 52b of the drive signal output circuit 50-1, when the wiring board 810 is viewed from a direction along the Z axis, and is provided on surface 816 of the wiring board 810. In other words, the integrated circuit 500 of the drive signal output circuit 50-1, the transistors 531 and 532 included in the drive circuit 52a of the drive signal output circuit 50-1, and the transistors 531 and 532 included in the drive circuit 52b of the drive signal output circuit 50-1 are mounted on different sides of the wiring board 810, and the integrated circuit 500 of the drive signal output circuit 50-1 is located between the transistors 531 and 532 included in the drive circuit 52a of the drive signal output circuit 50-1, and between the transistors 531 and 532 included in the drive circuit 52b of the drive signal output circuit 50-1.

[0111] In other words, the amplification circuit 530 included in the drive circuit 52a, which includes transistors 531 and 532, is provided on surface 815 of the wiring board 810, while the amplification control circuit 510 included in the drive circuit 52a mounted on the integrated circuit 500 is provided on surface 816 of the wiring board 810. At this time, the integrated circuit 500 including the amplification control circuit 510 is located in the direction normal to the wiring board 810, and when the wiring board 810 is viewed from a direction along the Z-axis, it is located between transistors 531 and 532 included in the amplification circuit 530.

[0112] Similarly, in each of the drive signal output circuits 50-2 to 50-6, the transistors 531 and 532 included in drive circuit 52a are provided on the surface 815 of the wiring board 810, and are positioned side by side along the X-axis such that transistor 531 is on the side 811 and transistor 532 is on the side 812. The transistors 531 and 532 included in drive circuit 52b are provided on the surface 815 of the wiring board 810 on the +Y side of the corresponding transistors 531 and 532 included in drive circuit 52a, and are positioned side by side along the X-axis such that transistor 531 is on the side 811 and transistor 532 is on the side 812.

[0113] Furthermore, in each of the drive signal output circuits 50-2 to 50-6, the integrated circuit 500, on which the drive circuit 520 and amplification control circuit 510 included in drive circuit 52a and the drive circuit 520 and amplification control circuit 510 included in drive circuit 52b are mounted, are located between transistors 531 and 532 included in drive circuit 52a of the corresponding drive signal output circuits 50-2 to 50-6, and between transistors 531 and 532 included in drive circuit 52b of the corresponding drive signal output circuits 50-2 to 50-6, when the wiring board 810 is viewed from a direction along the Z axis, and is provided on the surface 816 of the wiring board 810. In other words, in each of the drive signal output circuits 50-2 to 50-6, the integrated circuit 500 and the transistors 531 and 532 included in the drive circuit 52a and drive circuit 52b of the corresponding drive signal output circuits 50-2 to 50-6 are mounted on different sides of the wiring board 810, and the integrated circuit 500 is located between the transistors 531 and 532 included in the drive circuit 52a and between the transistors 531 and 532 included in the drive circuit 52b of the corresponding drive signal output circuits 50-2 to 50-6.

[0114] In other words, the transistors 531 and 532 in the amplification circuits 530 included in each of the multiple drive circuits 52 of the head drive module 10 are provided on the surface 815 of the wiring board 810 and not on the surface 816 of the wiring board 810, and the integrated circuit 500 including the amplification control circuit 510 included in each of the multiple drive circuits 52 of the head drive module 10 is provided on the surface 816 of the wiring board 810 and not on the surface 815 of the wiring board 810. That is, in the liquid dispensing device 1 of this embodiment, all of the transistors 531 and 532 in the amplification circuits 530 included in each of the multiple drive circuits 52 of the head drive module 10 are provided on the surface 815 of the wiring board 810, and all of the integrated circuit 500 including the amplification control circuit 510 included in each of the multiple drive circuits 52 of the head drive module 10 are provided on the surface 816 of the wiring board 810.

[0115] As described above, the drive circuit board 800 receives an image information signal IP via the connection part CN1, which is then supplied to the integrated circuit 101. The control circuit 100 and conversion circuit 120 included in the integrated circuit 101 generate digital waveform signals dA1~dA6, dB1~dB6 and a data signal DATA based on the image information signal IP, and output them from the integrated circuit 101. The digital waveform signals dA1~dA6, dB1~dB6 output from the integrated circuit 101 propagate through the wiring patterns (not shown) on the wiring board 810 and are input to the corresponding drive circuits 52. Each of the drive circuits 52 generates and outputs the corresponding drive signals COMA1~COMA6, COMB1~COMB6 based on the input digital waveform signals dA1~dA6, dB1~dB6. Then, multiple signals, including drive signals COMA1~COMA6,COMB1~COMB6 output by multiple drive circuits 52 and data signal DATA output by integrated circuit 101, are supplied to the liquid ejection module 20 via connection section CN2. As a result, the operation of the liquid ejection module 20, specifically the ejection of ink from the liquid ejection module 20, is controlled by the head drive module 10.

[0116] In this embodiment, the liquid dispensing device 1 is shown as an example in which the integrated circuit 101, including the control circuit 100, is mounted on the wiring board 810 together with the multiple drive circuits 52. However, the integrated circuit 101 may be mounted on a different board (not shown) from the drive circuits 52. When the integrated circuit 101 is mounted on a common board with the multiple drive circuits 52, as in the liquid dispensing device 1 of this embodiment, the wiring length for signal propagation between the multiple drive circuits 52 and the integrated circuit 101 can be shortened. This reduces the risk of noise and other interference superimposed on the signals propagating between the multiple drive circuits 52 and the integrated circuit 101, and improves the waveform accuracy of various signals, including the drive signal COM output by each of the multiple drive circuits 52. On the other hand, the amount of heat generated by the multiple drive circuits 52 is greater than that generated by the integrated circuit 101. By mounting the multiple drive circuits 52 and the integrated circuit 101 on different boards, the risk of heat generated by the multiple drive circuits 52 contributing to the integrated circuit 101 is reduced. As a result, the risk of a decrease in the operational stability of the integrated circuit 101 is reduced.

[0117] In the head drive module 10 of the liquid ejection device 1 of this embodiment, the drive circuit board 800, as shown in Figure 12, is housed in a space formed by a recess 711 in the heat sink 710 located on the +Z side of the drive circuit board 800 and a recess 721 in the heat sink 720 located on the -Z side of the drive circuit board 800. At this time, the heat generated in the drive circuit board 800, including the heat generated by the transistors 531, 532 and the integrated circuit 500, is released from both the +Z and -Z sides of the drive circuit board 800 via the heat sinks 710 and 720. As a result, in the liquid ejection device 1 of this embodiment, the risk of a decrease in the operational stability of the head drive module 10 due to heat generated by the multiple drive circuits 52 of the head drive module 10 is reduced. Therefore, the risk of a decrease in the operational stability of the liquid ejection module 20 controlled by the head drive module 10 is also reduced, and the risk of a decrease in the ink ejection accuracy from the liquid ejection module 20 is also reduced.

[0118] Here, an example of the thermal connection between the drive circuit 52 in the head drive module 10 of the liquid discharge device 1 of this embodiment and the transistors 531, 532 and integrated circuit 500 in the head drive module 10 and the heat sinks 710 and 720 will be described. Here, "thermal connection" refers to a state in which two or more members are connected in a manner that promotes heat transfer, and includes not only a state in which the two members are in physical contact with each other, but also a state in which one or more inclusions with excellent thermal conductivity are provided between the two members and they are connected via these inclusions, or a state in which there is a gap between the two members but the gap is 100 μm or less. Furthermore, as the "inclusions with excellent thermal conductivity" used for thermal connection, any material with high conductivity is acceptable, but preferably, in addition to high thermal conductivity, a material that is flame retardant, electrically insulating, and conforms to uneven surfaces can be used. For example, conductive grease, gel sheets, rubber sheets, etc., containing silicone or acrylic resin and having high thermal conductivity can be used.

[0119] In order to explain a specific example of the thermal connection relationship between transistors 531, 532 and integrated circuit 500 in the head drive module 10 and heat sinks 710 and 720, we will first describe an example of the structure of transistors 531 and 532 included in the drive circuit 52. As mentioned above, in the liquid discharge device 1 of this embodiment, transistor 531 is an NPN bipolar transistor, and transistor 532 is a PNP bipolar transistor, and transistors 531 and 532 constitute a complementary pair. Therefore, transistors 531 and 532 have similar structures, differing only in the type of semiconductor element mounted on them. In the following description, only the structure of transistor 531 will be described in detail using drawings, while the structure of transistor 532 will not be shown, and its description will be simplified or omitted.

[0120] Figure 13 shows an example of the structure of transistor 531. As shown in Figure 13, transistor 531 has a molded portion 531mo, lead frames 531fa, 531fb, 531fc, a semiconductor chip 531cp, and external connection terminals 531ta, 531tb, 531tc.

[0121] The molded portion 531mo has a surface 531mb, which has the largest area, and a surface 531mf, which is located opposite surface 531mb and has an area equal to or second largest to surface 531mb. That is, the transistor 531 includes surfaces 531mb and 531mf, the area of ​​surface 531mb is larger than the area of ​​surface 531mf, and surfaces 531mb and 531mf are located opposite each other. In addition, lead frames 531fa, 531fb, 531fc, and semiconductor chips 531cp are provided inside the molded portion 531mo. That is, the molded portion 531mo is formed to cover the lead frames 531fa, 531fb, 531fc, and semiconductor chips 531cp. Such a molded portion 531mo is composed of a flame-retardant epoxy resin or the like and functions as a protective member that protects the semiconductor chip 531cp located inside from outside air and impact. It should be noted that the molded portion 531mo is not limited to being composed of a single material; for example, from the viewpoint of improving heat dissipation, the surface 531mb may be composed of a tin-based alloy or a copper-based alloy, and in this case, the tin-based alloy or copper-based alloy constituting the surface 531mb may be integrally formed with the lead frame 531fb, which will be described later.

[0122] The lead frame 531fb is made of a material with a copper-based alloy as the base material. The lead frame 531fb includes a flat plate that extends along the plane formed by at least one of the surfaces 531mb and 531mf within the mold portion 531mo, and the flat plate is on surface 531mf It is located closer to the surface 531mb than the lead frame 531fb. That is, the lead frame 531fb is positioned such that the thermal resistance between the lead frame 531fb and the surface 531mb is smaller than the thermal resistance between the lead frame 531fb and the surface 531mf. A semiconductor chip 531cp, which is an NPN bipolar transistor element, is mounted on this lead frame 531fb. At this time, the semiconductor chip 531cp is fixed to the lead frame 531fb by, for example, high-melting-point solder. This electrically connects the semiconductor chip 531cp and the lead frame 531fb. That is, the transistor 531 includes the semiconductor chip 531cp, and within the mold portion 531mo, the semiconductor chip 531cp is fixed to the lead frame 531fb, so that the thermal resistance between the semiconductor chip 531cp and the surface 531mb is smaller than the thermal resistance between the semiconductor chip 531cp and the surface 531mf.

[0123] Furthermore, the lead frames 531fa and 531fc, provided inside the molded portion 531mo, are each made of a copper-based alloy material. Each of the lead frames 531fa and 531fc is electrically connected to the semiconductor chip 531cp by bonding wires (not shown), such as aluminum wire or gold wire. As a result, inside the molded portion 531mo, the base electrode, collector electrode, and emitter electrode of the semiconductor chip 531cp, which is an NPN bipolar transistor element, are electrically connected to the corresponding lead frames 531fa, 531fb, and 531fc, respectively.

[0124] External connection terminals 531ta, 531tb, and 531tc are connection terminals provided outside the molded portion 531mo for mounting the transistor 531 onto the wiring board 810, and are made of a material with a copper-based alloy as the base material.

[0125] External connection terminal 531ta is integrated with lead frame 531fa and extends from surface 531md of molded portion 531mo, which intersects with both surfaces 531mb and 531mf, toward the outside of molded portion 531mo. External connection terminal 531tb is integrated with lead frame 531fb and extends from surface 531md toward the outside of molded portion 531mo. External connection terminal 531tc is integrated with lead frame 531fc and extends from surface 531md toward the outside of molded portion 531mo. In other words, external connection terminals 531ta, 531tb, and 531tc function as the base terminal, collector terminal, and emitter terminal of transistor 531, and extend from surface 531md of molded portion 531mo toward the outside of molded portion 531mo. At this time, the external connection terminals 531ta, 531tb, and 531tc are formed in such a way that they extend in a direction away from the molded portion 531mo along the surface on which the surface 531mf extends, as shown in Figure 13.

[0126] Here, in the liquid dispensing device 1 of this embodiment, it will be explained that the base electrode of the semiconductor chip 531cp is electrically connected to the lead frame 531fa, the collector electrode of the semiconductor chip 531cp is electrically connected to the lead frame 531fb, and the emitter electrode of the semiconductor chip 531cp is electrically connected to the lead frame 531fc. That is, the external connection terminal 531ta corresponds to the base terminal of the transistor 531, the external connection terminal 531tb corresponds to the collector terminal of the transistor 531, and the external connection terminal 531tc corresponds to the emitter terminal of the transistor 531. However, the relationship between the external connection terminals 531ta, 531tb, and 531tc and the base terminal, emitter terminal, and collector terminal of the transistor 531 is not limited to these.

[0127] As described above, in the liquid dispensing device 1 of this embodiment, the transistors included in the drive circuits 52a and 52b, each of the drive signal output circuits 50-1 to 50-6 531 is a so-called SIP (Single In-line Package) type bipolar transistor in which external connection terminals 531ta, 531tb, and 531tc, which are electrically connected to the wiring board 810, are provided in a row on the surface 531md of the molded portion 531mo. The external connection terminals 531ta, 531tb, and 531tc, which extend from the surface 531md of the molded portion 531mo toward the molded portion 531mo, are formed into a predetermined shape and then mounted on the surface 815 of the wiring board 810.

[0128] As described above, transistors 531 and 532 have similar structures. That is, transistor 532 has molded portion 532mo, surfaces 532mb, 532mf, 532md, lead frames 531fa, 531fb, 531fc, semiconductor chip 531cp, and external connection terminals 531ta, 531tb, 531tc, which correspond to the molded portion 531mo, surfaces 531mb, 531mf, 531md, lead frames 531fa, 531fb, 531fc, semiconductor chip 532cp, and external connection terminals 532ta, 532tb, 532tc of transistor 531. In this case, the area of ​​surface 532mb included in transistor 532 is larger than the area of ​​surface 532mf, and surfaces 532mb and 532mf are located facing each other. The transistor 532 includes a semiconductor chip 532cp inside the molded portion 532mo, and the semiconductor chip 532cp is fixed to the lead frame 532fb inside the molded portion 532mo, so that the thermal resistance between the semiconductor chip 532cp and the surface 532mb is smaller than the thermal resistance between the semiconductor chip 532cp and the surface 532mf. In addition, the external connection terminals 532ta, 532tb, and 532tc of the transistor 532, which are electrically connected to the wiring board 810, are provided in a row on the surface 532md of the molded portion 532mo. In other words, the transistor 532 is a SIP-type bipolar transistor. The transistor 532 is then formed into a predetermined shape on the external connection terminals 532ta, 532tb, and 532tc extending from the surface 532md of the molded portion 532mo, and then mounted on the surface 815 of the wiring board 810.

[0129] Figure 14 is a diagram illustrating an example of thermal connection between transistors 531, 532 and integrated circuit 500 and heat sinks 710 and 720. Here, Figure 14 is a cross-sectional view when the head drive module 10 is cut so that it passes through transistors 531, 532 and integrated circuit 500, which are part of one of the multiple drive circuits 52 that the head drive module 10 has.

[0130] As shown in Figure 14, in the head drive module 10, the drive circuit board 800 is housed in a space formed by recesses 711 and 721 such that the surface 815 of the wiring board 810 is on the +Z side and the surface 816 of the wiring board 810 is on the -Z side. Transistors 531, 532 and integrated circuit 500 are mounted on the wiring board 810 of the drive circuit board 800.

[0131] Transistor 531 is mounted on surface 815 of the wiring board 810 such that its molded portion 531mo is on the -X side, its external connection terminals 531ta, 531tb, and 531tc are on the +X side, and at least a portion of its surface 531mf is in contact with surface 815. Transistor 531 is mounted on the wiring board 810 by electrically connecting each of the external connection terminals 531ta, 531tb, and 531tc to the wiring board 810 using solder or the like. Transistor 532 is mounted on surface 815 of the wiring board 810 such that its molded portion 532mo is on the +X side, its external connection terminals 532ta, 532tb, and 532tc are on the -X side, and at least a portion of its surface 532mf is in contact with surface 815. Then, the transistor 532 is mounted on the wiring board 810 by electrically connecting each of the external connection terminals 532ta, 532tb, and 532tc to the wiring board 810 with solder or the like. In other words, transistors 531 and 532 are connected to the external connection terminals 531ta, 531tb, Terminals 531tc and external connection terminals 532ta, 532tb, and 532tc are mounted on surface 815 of the wiring board 810 so that they face each other.

[0132] The integrated circuit 500 is mounted on surface 816 of the wiring board 810 such that, when viewed from the direction along the Z-axis, at least a portion of it is located between transistors 531 and 532. In this case, when viewed from the direction along the Z-axis, at least a portion of the integrated circuit 500 overlaps with at least a portion of transistor 531, and at least a portion of the integrated circuit 500 overlaps with at least a portion of transistor 532.

[0133] Here, transistors 531 and 532 are mounted on surface 815 of the wiring board 810 such that their external connection terminals 531ta, 531tb, 531tc and external connection terminals 532ta, 532tb, 532tc face each other. Therefore, the integrated circuit 500 is mounted on surface 816 of the wiring board 810 such that, when viewed from the direction along the Z axis, it is located between the external connection terminals 531ta, 531tb, 531tc and external connection terminals 532ta, 532tb, 532tc. This makes it possible to shorten the wiring length through which the amplification control signal Hdr output by the integrated circuit 500 to transistor 531 propagates, and the wiring length through which the amplification control signal Ldr output by the integrated circuit 500 to transistor 532 propagates. As a result, the risk of noise and other interference superimposed on the amplification control signals Hdr and Ldr is reduced, and the drive control of transistors 531 and 532 is improved. Therefore, the waveform accuracy of the drive signal COM output by the drive circuit 52 is improved, and the ink ejection accuracy from the liquid ejection module 20 is improved.

[0134] The heatsink 720 is located on the -Z side of the drive circuit board 800 and on the side 816 of the wiring board 810. The heatsink 720 includes protrusions 722, 723, and 724 that project in the +Z direction.

[0135] The protrusion 722 is formed in correspondence with the transistor 531. Specifically, when the head drive module 10 is viewed from a direction along the Z-axis, at least a portion of the protrusion 722 is positioned to overlap at least a portion of the surface 531mf of the transistor 531. In addition, the heat conductive member 543, which is the intervening material described above, is located between the wiring board 810 and the protrusion 722 in the direction along the Z-axis. When the drive circuit board 800 is housed in the space formed by the recesses 711 and 721, the protrusion 722 is in contact with one surface of the heat conductive member 543, the other surface of the heat conductive member 543 is in contact with the surface 816 of the wiring board 810, and the surface 531mf of the transistor 531 is in contact with the region of the surface 815 that is opposite the surface 816 in contact with the heat conductive member 543 along the Z-axis. In other words, the protrusion 722, the surface 531mf, and the heat conductive member 543 are positioned such that at least a portion of them overlap when viewed from a direction along the Z-axis. As a result, the protrusion 722 and the surface 531mf of the transistor 531 are thermally connected via the heat conductive member 543 and the wiring board 810. Therefore, the heat generated in the transistor 531 is efficiently transferred to the heat sink 720 via the wiring board 810 and the heat conductive member 543. Thus, the efficiency of heat dissipation from the transistor 531 is improved.

[0136] Here, as described above, the heat conductive member 543 as an intervening part is preferably a material that has high thermal conductivity, as well as flame retardancy, electrical insulation properties, and the ability to conform to uneven surfaces, such as conductive grease, gel sheets, or rubber sheets. As a result, the heat conductive member 543 functions not only as a heat conductive member that transmits the heat generated in the transistor 531 to the heat sink 720, but also as a member that insulates the wiring board 810 and the heat sink 720, and as a member that enhances the adhesion between the wiring board 810 and the heat sink 720.

[0137] As described above, the surface 531mf of the transistor 531 is thermally connected to the surface 815 of the wiring board 810, and the surface 816 of the wiring board 810 is thermally connected to the heat sink 720. Therefore, the heat sink 720 is thermally connected to the amplification circuit 530 including the transistor 531 via the wiring board 810. As a result, the heat generated by the transistor 531 and the heat generated by the amplification circuit 530 including the transistor 531 is efficiently transferred to the heat sink 720 and released to the outside. In this embodiment, the liquid dispensing device 1 has a heat conductive member 543 located between the heat sink 720 and the wiring board 810, between the protrusion 722 of the heat sink 720 and the surface 816 of the wiring board 810, and in contact with both the heat sink 720 and the wiring board 810. That is, the surface 816 of the wiring board 810 and the heat sink 720 are thermally and physically connected via the insulating heat conductive member 543. This improves the heat dissipation efficiency between the surface 816 of the wiring board 810 and the heat sink 720, and also improves the insulation performance between the surface 816 of the wiring board 810 and the heat sink 720.

[0138] Here, when the drive circuit board 800 is housed in the space formed by the recesses 711 and 721, it is more preferable that, when the head drive module 10 is viewed from a direction along the Z-axis, the entire protrusion 722 is positioned to overlap with at least a portion of the surface 531mf of the transistor 531, or at least a portion of the protrusion 722 is positioned to overlap with the entire surface 531mf of the transistor 531. This allows the heat generated in the transistor 531 to be more efficiently transferred to the heat sink 720 via the wiring board 810 and the heat conductive member 543. As a result, the efficiency of heat dissipation from the transistor 531 is further improved.

[0139] Furthermore, as shown in Figure 12, multiple transistors 531 are arranged in parallel along the Y-axis on the surface 815 of the wiring board 810. The heat sink 720 may include protrusions 722 that correspond individually to each of the multiple transistors 531 arranged in parallel along the Y-axis, or it may include protrusions 722 that are common to some of the multiple transistors 531 arranged in parallel along the Y-axis. In addition, the protrusions 722 may have notches or through holes that are continuous along the X-axis from the -X side to the +X side of the protrusion 722. This allows the gas, including the airflow sent out by the cooling fan 713, to circulate efficiently inside the space formed by the recesses 711 and 721. Therefore, the cooling efficiency of the head drive module 10 is improved.

[0140] The protrusion 723 is formed in correspondence with the transistor 532. Specifically, when the head drive module 10 is viewed from a direction along the Z-axis, at least a portion of the protrusion 723 is positioned to overlap at least a portion of the surface 532mf of the transistor 532. In addition, the heat conductive member 544, which is the intervening material described above, is located between the wiring board 810 and the protrusion 723 in the direction along the Z-axis. When the drive circuit board 800 is housed in the space formed by the recess 711 and the recess 721, the protrusion 723 is in contact with one surface of the heat conductive member 544, the other surface of the heat conductive member 544 is in contact with the surface 816 of the wiring board 810, and the surface 532mf of the transistor 532 is in contact with the region of the surface 815 that is opposite the surface 816 in contact with the heat conductive member 544 along the Z-axis. In other words, the protrusion 723, the surface 532mf, and the heat conductive member 544 are positioned such that at least a portion of them overlap when viewed from a direction along the Z-axis. As a result, the protrusion 723 and the surface 532mf of the transistor 532 are thermally connected via the heat conductive member 544 and the wiring board 810. Therefore, the heat generated in the transistor 532 is efficiently transferred to the heat sink 720 via the wiring board 810 and the heat conductive member 544. Thus, the efficiency of heat dissipation from the transistor 532 is improved.

[0141] Here, as described above, the heat conductive member 544 as an intervening part is a material that has high thermal conductivity, as well as flame retardancy, electrical insulation, and the ability to conform to uneven surfaces, for example, conductive green It is preferable to use materials such as acrylic sheets, gel sheets, or rubber sheets. As a result, the heat conductive member 544 functions not only as a heat conductive member that transmits the heat generated in the transistor 532 to the heat sink 720, but also as a member that insulates the wiring board 810 from the heat sink 720, and as a member that enhances the adhesion between the wiring board 810 and the heat sink 720.

[0142] As described above, the surface 532mf of transistor 532 is thermally connected to the surface 815 of the wiring board 810, and the surface 816 of the wiring board 810 is thermally connected to the heat sink 720. Therefore, the heat sink 720 is thermally connected to the amplification circuit 530 including transistor 532 via the wiring board 810. As a result, the heat generated by transistor 532 and the heat generated by the amplification circuit 530 including transistor 532 is efficiently transferred to the heat sink 720 and released to the outside. In this embodiment, the liquid dispensing device 1 has a heat conductive member 544 located between the heat sink 720 and the wiring board 810, between the protrusion 723 of the heat sink 720 and the surface 816 of the wiring board 810, and in contact with both the heat sink 720 and the wiring board 810. That is, the surface 816 of the wiring board 810 and the heat sink 720 are thermally and physically connected via the insulating heat conductive member 544. This improves the heat dissipation efficiency between the surface 816 of the wiring board 810 and the heat sink 720, and also improves the insulation performance between the surface 816 of the wiring board 810 and the heat sink 720.

[0143] Here, when the drive circuit board 800 is housed in the space formed by the recesses 711 and 721, it is more preferable that, when the head drive module 10 is viewed from a direction along the Z-axis, the entire protrusion 723 is positioned to overlap with at least a portion of the surface 532mf of the transistor 532, or at least a portion of the protrusion 723 is positioned to overlap with the entire surface 532mf of the transistor 532. This allows the heat generated in the transistor 532 to be more efficiently transferred to the heat sink 720 via the wiring board 810 and the heat conductive member 544. As a result, the efficiency of heat dissipation from the transistor 532 is further improved.

[0144] Furthermore, as shown in Figure 12, multiple transistors 532 are arranged in parallel along the Y-axis on surface 815 of the wiring board 810. The heat sink 720 may include protrusions 723 that correspond individually to each of the multiple transistors 532 arranged in parallel along the Y-axis, or it may include protrusions 723 that are common to some of the multiple transistors 532 arranged in parallel along the Y-axis. In addition, the protrusions 723 may have notches or through holes that are continuous along the X-axis from the -X side to the +X side of the protrusion 723. This allows the gas, including the airflow sent out by the cooling fan 713, to circulate efficiently inside the space formed by the recesses 711 and 721. Therefore, the cooling efficiency of the head drive module 10 is improved.

[0145] The protrusion 724 is formed in correspondence with the integrated circuit 500. Specifically, the protrusion 724 is located between the protrusions 722 and 723 when the head drive module 10 is viewed from the direction along the Y axis, and is positioned such that at least a portion of it overlaps with at least a portion of the integrated circuit 500 when the head drive module 10 is viewed from the direction along the Z axis. Furthermore, the heat conductive member 545, which is the intervening material described above, is located between the integrated circuit 500 and the protrusion 724 in the direction along the Z axis. When the drive circuit board 800 is housed in the space formed by the recesses 711 and 721, the protrusion 724 is in contact with one surface of the heat conductive member 545, and the other surface of the heat conductive member 545 is in contact with the integrated circuit 500. That is, the protrusion 724, the integrated circuit 500, and the heat conductive member 545 are positioned such that at least a portion of them overlap when viewed from the direction along the Z axis. As a result, the protrusion 724 and the integrated circuit 500 are thermally connected via the heat conductive member 545. Therefore, the heat generated in the integrated circuit 500 is efficiently transferred to the heat sink 720 via the heat conductive member 545. Thus, the efficiency of heat dissipation from the integrated circuit 500 is improved.

[0146] Here, as described above, the heat conductive member 545 as an intervening part is preferably a material that has high thermal conductivity, as well as flame retardancy, electrical insulation properties, and the ability to conform to uneven surfaces, such as conductive grease, gel sheets, or rubber sheets. As a result, the heat conductive member 545 functions not only as a heat conductive member that transmits the heat generated in the integrated circuit 500 to the heat sink 720, but also as a member that insulates the integrated circuit 500 and the heat sink 720, and as a member that enhances the adhesion between the integrated circuit 500 and the heat sink 720.

[0147] As described above, the integrated circuit 500 is thermally connected to the heat sink 720. In other words, the head drive module 10 includes a heat sink 720 that is thermally connected to the amplification control circuit 510 included in the integrated circuit 500. As a result, the heat generated in the integrated circuit 500, specifically the heat generated in the amplification control circuit 510 mounted on the integrated circuit 500, is efficiently transferred to the heat sink 720 and released to the outside. In this embodiment, the liquid discharge device 1 has a heat conductive member 545 located between the heat sink 720 and the integrated circuit 500, between the protrusion 724 of the heat sink 720 and the integrated circuit 500, and which contacts both the heat sink 720 and the integrated circuit 500. That is, the integrated circuit 500 and the heat sink 720 are thermally and physically connected via the insulating heat conductive member 545. This improves the heat dissipation efficiency between the integrated circuit 500 and the heat sink 720, and also improves the insulation performance between the integrated circuit 500 and the surface 816 of the wiring board 810 on which the integrated circuit 500 is provided, and the heat sink 720.

[0148] Here, when the drive circuit board 800 is housed in the space formed by the recesses 711 and 721, it is more preferable that, when the head drive module 10 is viewed from a direction along the Z-axis, the entire protrusion 724 is positioned to overlap with at least a part of the integrated circuit 500, or at least a part of the protrusion 724 is positioned to overlap with the entire integrated circuit 500. As a result, the heat generated in the integrated circuit 500 is more efficiently transferred to the heat sink 720 via the heat conductive member 545. Consequently, the efficiency of heat dissipation from the transistor 532 is improved.

[0149] Furthermore, as shown in Figure 12, multiple integrated circuits 500 are arranged side by side along the Y-axis on the surface 816 of the wiring board 810. The heat sink 720 may include protrusions 724 that correspond individually to each of the multiple integrated circuits 500 arranged side by side along the Y-axis, or it may include protrusions 724 that are common to some of the multiple integrated circuits 500 arranged side by side along the Y-axis. In addition, the protrusions 724 may have notches or through holes that are continuous along the X-axis from the -X side to the +X side of the protrusion 724. This allows the gas, including the airflow sent out by the cooling fan 713, to circulate efficiently inside the space formed by the recesses 711 and 721. As a result, the cooling efficiency of the entire drive circuit board 800 is improved.

[0150] As described above, the heat sink 720 includes a protrusion 724 that protrudes to the +Z side and is thermally connected to the amplification control circuit 510 included in the integrated circuit 500, a protrusion 722 that protrudes to the +Z side and is thermally connected to the transistor 531 included in the amplification circuit 530, and a protrusion 723 that protrudes to the +Z side and is thermally connected to the transistor 532 included in the amplification circuit 530. In other words, the heat sink 720 includes recesses between the protrusions 722 and 724, and between the protrusions 723 and 724. This reduces the risk that the heat from the amplification control circuit 510 included in the integrated circuit 500, released via the protrusion 724, will contribute to the transistors 531 and 532 included in the amplification circuit 530, and also reduces the risk that the heat from the transistor 531 included in the amplification circuit 530, released via the protrusion 722, and the heat from the transistor 532 included in the amplification circuit 530, released via the protrusion 723, will contribute to the amplification control circuit 510 included in the integrated circuit 500. Furthermore, the heat sink 720 includes recesses between the protrusions 722 and 724, and between the protrusions 723 and 724, which reduces the risk of heat from the amplification control circuit 510 included in the integrated circuit 500. This allows for the mounting of large electronic components along the Z-axis direction on surface 816 of the substrate 810. As a result, the variety of electronic components that can be mounted on the wiring board 810 increases, and the versatility of the drive circuit board 800, including the wiring board 810, is enhanced.

[0151] The heatsink 710 is located on the +Z side of the drive circuit board 800, on the side of the wiring board 810 facing surface 815. In the direction along the Z axis, the heat conductive member 541, as described above, is located between the heatsink 710 and the surface 531mb of the transistor 531, and the heat conductive member 542, as described above, is located between the heatsink 710 and the surface 532mb of the transistor 532. When the drive circuit board 800 is housed in the space formed by the recesses 711 and 721, the surface 531mb of the transistor 531 is in contact with one surface of the heat conductive member 541, the other surface of the heat conductive member 541 is in contact with the heatsink 710, the surface 532mb of the transistor 532 is in contact with one surface of the heat conductive member 542, and the other surface of the heat conductive member 542 is in contact with the heatsink 710. Specifically, the heat sink 710 and the surface 531mf of transistor 531 are thermally connected via the heat conductive member 541, and the heat sink 710 and the surface 532mf of transistor 532 are thermally connected via the heat conductive member 542. As a result, transistor 531 and heat sink 710 are thermally connected, and transistor 532 and heat sink 710 are thermally connected. Therefore, heat generated in transistor 531 is efficiently transferred to the heat sink 710 via the heat conductive member 541, and heat generated in transistor 532 is efficiently transferred to the heat sink 710 via the heat conductive member 542. Thus, the efficiency of heat dissipation from the heat generated in transistors 531 and 532, and the heat generated in the amplification circuit 530 including transistors 531 and 532, is improved.

[0152] Here, as described above, the heat conductive members 541 and 542 as intervening parts are preferably materials that have high thermal conductivity, as well as flame retardancy, electrical insulation, and the ability to conform to uneven surfaces, such as conductive grease, gel sheets, or rubber sheets. As a result, the heat conductive members 541 and 542 function not only as heat conductive members that transfer the heat generated in the transistors 531 and 532 to the heat sink 710, but also as insulating members between the transistors 531 and 532 and the heat sink 710, and as members that enhance the adhesion between the transistors 531 and 532 and the heat sink 710.

[0153] As described above, the surface 531mb of transistor 531 and the surface 532mb of transistor 532 are thermally connected to the heat sink 710. In other words, the amplification circuit 530, including transistors 531 and 532, is thermally connected to the heat sink 710. As a result, the heat generated by transistors 531 and 532, specifically the heat generated in the amplification circuit 530 including transistors 531 and 532, is efficiently transferred to the heat sink 710 and released to the outside. In this embodiment, the liquid discharge device 1 includes a heat conductive member 541 located between the heat sink 710 and the surface 531mb of transistor 531, and in contact with both the heat sink 710 and the surface 531mb of transistor 531, and a heat conductive member 542 located between the heat sink 710 and the surface 532mb of transistor 532, and in contact with both the heat sink 710 and the surface 532mb of transistor 532. Specifically, the heat sink 710 and the surface 531mb of the transistor 531 are thermally and physically connected via an insulating heat conductive member 541, and the heat sink 710 and the surface 532mb of the transistor 532 are thermally and physically connected via an insulating heat conductive member 542. This improves the heat dissipation efficiency between the transistors 531, 532 and the heat sink 710, and also improves the insulation performance between the transistors 531, 532 and the heat sink 710.

[0154] Furthermore, in the liquid dispensing device 1 of this embodiment, as described above, the heat dissipation performance of the heat sink 710 is higher than that of the heat sink 720. Such a heat sink 71 has excellent heat dissipation performance. By releasing the heat generated by transistors 531 and 532 without going through the wiring board 810, the heat dissipation efficiency for transistors 531 and 532 can be further improved.

[0155] Furthermore, in this embodiment, the liquid dispensing device 1 has a heat sink 710 with excellent heat dissipation properties that, at transistor 531, is thermally connected to the surface 531mb of the semiconductor chip 531cp, which has low thermal resistance, without the use of the wiring board 810, and at transistor 532, is thermally connected to the surface 532mb of the semiconductor chip 532cp, which has low thermal resistance, without the use of the wiring board 810. As a result, the heat generated at the semiconductor chips 531cp and 532cp, which generate particularly large amounts of heat in transistors 531 and 532, can be efficiently dissipated through the heat sink 710. Therefore, the heat dissipation efficiency for transistors 531 and 532 is further improved.

[0156] Although Figure 14 illustrates a case where the heatsink 710 does not have protrusions, the heatsink 710 may, like the heatsink 720, have protrusions corresponding to the surface 531mb of transistor 531 and protrusions corresponding to the surface 532mb of transistor 532. Furthermore, the heatsinks 710 and 720 may have a structure with multiple fins formed facing outwards from the head drive module 10. This increases the area of ​​the heatsinks 710 and 720, further improving the heat dissipation efficiency of the heatsinks 710 and 720.

[0157] Here, in the drive circuit 52a of the drive signal output circuit 50-1, the amplification control circuit 510 is an example of a first drive signal output circuit, the digital waveform signal dA1 input to the amplification control circuit 510 of the drive circuit 52a is an example of a first digital signal, the drive waveform signal WS output by the amplification control circuit 510 of the drive circuit 52a is an example of a first drive signal, the amplification circuit 530 of the drive circuit 52a is an example of a first amplification circuit, the transistor 531 of the amplification circuit 530 is an example of a first transistor, the transistor 532 of the amplification circuit 530 is an example of a second transistor, the drive signal COMA1 output by the amplification circuit 530 of the drive circuit 52a is an example of a drive signal, and the piezoelectric element 60 of the discharge module 23-1 driven by the drive signal COMA1 is an example of a first capacitive load. Furthermore, in the drive circuit 52a of the drive signal output circuit 50-2, the amplification control circuit 510 is an example of a second drive signal output circuit, the digital waveform signal dA2 input to the amplification control circuit 510 of the drive circuit 52a is an example of a second digital signal, the drive waveform signal WS output by the amplification control circuit 510 of the drive circuit 52a is an example of a second drive signal, the amplification circuit 530 of the drive circuit 52a is an example of a second amplification circuit, the drive signal COMA2 output by the amplification circuit 530 of the drive circuit 52a is an example of a second drive signal, and the piezoelectric element 60 of the discharge module 23-2 driven by the drive signal COMA2 is an example of a second capacitive load. In addition, the amplification control circuit 510 of each of the drive signal output circuits 50-1 to 50-6 is an example of multiple drive signal output circuits, and the amplification circuit 530 of each of the drive signal output circuits 50-1 to 50-6 is an example of multiple amplification circuits. Furthermore, the liquid discharge module 20 is an example of a discharge head, and the head drive module 10, which includes the drive circuit 52, is an example of a capacitive load drive circuit. Also, the surface 531mb of transistor 531 included in the amplification circuit 530 of the drive circuit 52a of the drive signal output circuit 50-1 is an example of a first surface, the surface 531mf of transistor 531 is an example of a second surface, the surface 532mb of transistor 532 is an example of a third surface, and the surface 532mf of transistor 532 is an example of a fourth surface.Furthermore, surface 815 of the wiring board 810 is an example of a first substrate surface, surface 815 of the wiring board 810 is an example of a second substrate surface, heat sink 710 is an example of a first heat dissipation member, heat sink 720 is an example of a second heat dissipation member, the space formed by the recess 711 of the heat sink 710 and the recess 721 of the heat sink 720 is an example of a housing portion, the protrusion 724 included in the heat sink 720 is an example of a first protrusion, and at least one of the protrusions 722 and 723 included in the heat sink 720 is the first. This is an example of a double-convex section.

[0158] 5. Effects As described above, the liquid discharge device 1 of this embodiment has a head drive module 10 which includes heat sinks 710 and 720 and a drive circuit board 800. The drive circuit board 800 includes an amplification control circuit 510 which receives a digital waveform signal dO and outputs a drive waveform signal WS, an amplification circuit 530 which includes transistors 531 and 532 and, by driving the transistors 531 and 532, amplifies the drive waveform signal WS and outputs a drive signal COM that drives the piezoelectric element 60, and a wiring board 810 on which the amplification control circuit 510 and the amplification circuit 530 are provided.

[0159] In the head drive module 10, the surface 531mb of transistor 531 and the surface 532mb of transistor 532 are thermally connected to the heat sink 710, and the surface 531mf of transistor 531 that is located opposite the surface 531mb, and the surface 532mf of transistor 532 that is located opposite the surface 532mb, are thermally connected to the surface 815 of the wiring board 810. Furthermore, the surface 816 of the wiring board 810 that is located opposite the surface 815 is thermally connected to the heat sink 720. As a result, the heat generated by transistors 531 and 532 is released from the surfaces 531mb and 532mb by the heat sink 710, and also from the surfaces 531mf and 532mf via the wiring board 810 by the heat sink 720. In other words, the heat generated by transistors 531 and 532 is dissipated from both sides of transistors 531 and 532 by heat sinks 710 and 720. This improves the efficiency of heat dissipation from transistors 531 and 532, reducing the risk of transistors 531 and 532 becoming overheated. Consequently, the risk of a decrease in the operational stability of the drive circuit 52, including the amplification circuit 530, is reduced. Consequently, the risk of a decrease in the waveform accuracy of the drive signal COM output by the drive circuit 52 and the head drive module 10, including the drive circuit 52, is reduced.

[0160] At this time, by making the heat dissipation performance of the heat sink 710, which is thermally connected to the transistors 531 and 532 without going through the wiring board 810, higher than that of the heat sink 720, which is thermally connected to the transistors 531 and 532 via the wiring board 810, the efficiency of heat dissipation from the transistors 531 and 532 is further improved. Therefore, the risk of the transistors 531 and 532 becoming overheated is further reduced. As a result, the risk of a decrease in the operational stability of the drive circuit 52, including the amplification circuit 530, is further reduced, and the risk of a decrease in the waveform accuracy of the drive signal COM output by the drive circuit 52 and the head drive module 10, including the drive circuit 52, is further reduced.

[0161] Furthermore, by making the area of ​​surface 531mb of transistor 531 larger than the area of ​​surface 531mf, and the area of ​​surface 532mb of transistor 532 larger than the area of ​​surface 532mf, the heat dissipation efficiency of transistors 531 and 532 by the heat sink 710 is further improved. Therefore, the risk of transistors 531 and 532 becoming overheated is further reduced. As a result, the risk of a decrease in the operational stability of the drive circuit 52 including the amplification circuit 530 is further reduced, and the risk of a decrease in the waveform accuracy of the drive signal COM output by the drive circuit 52 and the head drive module 10 including the drive circuit 52 is further reduced.

[0162] Furthermore, in transistor 531, the thermal resistance between the semiconductor chip 531cp and the surface 531mb is smaller than the thermal resistance between the semiconductor chip 531cp and the surface 531mf, and in transistor 532, the thermal resistance between the semiconductor chip 532cp and the surface 532mb is smaller than the thermal resistance between the semiconductor chip 532cp and the surface 532mf, further improving the heat dissipation efficiency of transistors 531 and 532 by the heat sink 710. Therefore, the risk of transistors 531 and 532 becoming overheated is further reduced. As a result, the amplification circuit 530 The risk of reduced operational stability of the drive circuit 52, which includes the drive circuit 52, is further reduced, and the risk of reduced waveform accuracy of the drive signal COM output by the drive circuit 52 and the head drive module 10, which includes the drive circuit 52, is further reduced.

[0163] Furthermore, a heat conductive member 541 having high thermal conductivity, as well as flame retardancy, electrical insulation, and the ability to conform to uneven surfaces, is positioned between the surface 531mb of transistor 531 and the heat sink 710; a heat conductive member 542 having high thermal conductivity, as well as flame retardancy, electrical insulation, and the ability to conform to uneven surfaces, is positioned between the surface 532mb of transistor 532 and the heat sink 710; and heat conductive members 543 and 544 having high thermal conductivity, as well as flame retardancy, electrical insulation, and the ability to conform to uneven surfaces, are positioned between the surface 816 of the wiring board 810 and the heat sink 720. As a result, the insulation performance between the heat sinks 710 and 720 and the wiring board 810 is enhanced, and the adhesion between the heat sinks 710 and 720 and the transistors 531 and 532 and the wiring board 810 is improved, further enhancing the heat dissipation efficiency of the heat sinks 710 and 720 from transistors 531 and 532. Therefore, the risk of transistors 531 and 532 overheating is further reduced. As a result, the risk of a decrease in the operational stability of the drive circuit 52, including the amplification circuit 530, is further reduced, and the risk of a decrease in the waveform accuracy of the drive signal COM output by the drive circuit 52 and the head drive module 10, including the drive circuit 52, is further reduced.

[0164] Furthermore, since the amplification circuit 530, which includes transistors 531 and 532, is provided on the surface 815 of the wiring board 810, and the amplification control circuit 510, which outputs the drive waveform signal WS, is provided on the surface 816 of the wiring board 810, the heat generated in the amplification circuit 530 and the heat generated in the amplification control circuit 510 mutually influence each other, reducing the risk of the temperature of the drive circuit 52 rising. Consequently, the risk of a decrease in the operational stability of the drive circuit 52 is reduced, and the risk of a decrease in the waveform accuracy of the drive signal COM output by the drive circuit 52 and the head drive module 10 including the drive circuit 52 is reduced.

[0165] In this case, all of the multiple amplification circuits 530 included in the multiple drive circuits 52 provided on the wiring board 810 are provided on the surface 815 of the wiring board 810, and all of the multiple amplification control circuits 510 included in the multiple drive circuits 52 are provided on the surface 816 of the wiring board 810. This further reduces the risk of mutual influence between the heat generated in the amplification circuits 530 and the heat generated in the amplification control circuits 510, and further reduces the risk of the temperature of the drive circuits 52 rising. Consequently, the risk of a decrease in the operational stability of each of the multiple drive circuits 52 is reduced, and the risk of a decrease in the waveform accuracy of the drive signal COM output by the multiple drive circuits 52 and the head drive module 10 including the multiple drive circuits 52 is reduced.

[0166] Furthermore, among the heat sinks 710 and 720 that facilitate heat dissipation of the amplification circuit 530, the heat sink 720 that facilitates heat dissipation of the amplification circuit 530 is thermally connected to the amplification control circuit 510 from the side 816 of the wiring board 810, thereby improving the heat dissipation efficiency of the amplification control circuit 510. Therefore, the risk of the amplification control circuit 510 becoming overheated, in addition to the transistors 531 and 532, is reduced. As a result, the risk of a decrease in the operational stability of the drive circuit 52, which includes the amplification circuit 530 and the amplification control circuit 510, is further reduced, and the risk of a decrease in the waveform accuracy of the drive signal COM output by the drive circuit 52 and the head drive module 10, which includes the drive circuit 52, is further reduced.

[0167] 6. Variations In the liquid dispensing device 1 of this embodiment described above, the heat sink 710 has a cooling fan 713, and the airflow delivered by the cooling fan 713 helps to cool the drive circuit board 800. However, the invention is not limited to this.

[0168] Figure 15 shows an example of a cross-section of the head drive module 10 in a modified example. As shown in Figure 15, the heat sink 710 may have a water cooling mechanism 715 that facilitates the cooling of the drive circuit board 800. Cooling water is circulated in the water cooling mechanism 715 by power such as a pump (not shown). This further improves the heat dissipation performance of the heat sink 710 and improves the heat dissipation efficiency of the transistors 531 and 532, whose heat dissipation is facilitated by the heat sink 710.

[0169] Furthermore, the heat sinks 710 and 720 may be coated with an insulating coating, such as epoxy resin. This increases the range of materials that can be used for the heat sinks 710 and 720 as a heat conductive member 541 provided between the transistor 531 and the heat sink 710, a heat conductive member 542 provided between the transistor 532 and the heat sink 710, heat conductive members 543 and 544 provided between the wiring board 810 and the heat sink 720, and a heat conductive member 545 provided between the integrated circuit 500 and the heat sink 720. In addition, the heat sinks 710 and 720 can directly promote the dissipation of heat generated in the drive circuit 52 without using the heat conductive members 541 to 545. Therefore, the efficiency of heat dissipation by the heat sinks 710 and 720 in the drive circuit 52 is further improved. Note that the heat sinks 710 and 720 only need to have insulating properties, and may be made of insulating ceramics or the like instead of an insulating coating of epoxy resin or the like.

[0170] Although embodiments and modifications have been described above, the present invention is not limited to these embodiments and can be implemented in various forms without departing from its spirit. For example, the above embodiments can be combined as appropriate.

[0171] The present invention includes configurations that are substantially identical to those described in the embodiments (for example, configurations with the same function, method, and result, or configurations with the same purpose and effect). The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as those described in the embodiments. Finally, the present invention includes configurations that add known technology to the configurations described in the embodiments.

[0172] The following conclusions can be drawn from the embodiments described above.

[0173] One embodiment of a capacitive load drive circuit is: A first drive signal output circuit that receives a first digital signal and outputs a first drive signal, A first amplification circuit that amplifies the first drive signal and outputs a first drive signal to drive the first capacitive load, A wiring board comprising a first substrate surface and a second substrate surface located facing each other, on which the first drive signal output circuit and the first amplification circuit are provided, Equipped with, The first amplification circuit is provided on the first substrate surface, The first drive signal output circuit is provided on the second substrate surface.

[0174] In this capacitive load drive circuit, the first amplifier circuit, which generates a large amount of heat, and the first drive signal output circuit, which also generates a large amount of heat, are located on different sides of the wiring board. As a result, the heat generated by the first amplifier circuit and the heat generated by the first drive signal output circuit on the wiring board mutually affect each other, reducing the risk of the temperature of the capacitive load drive circuit rising. Therefore, the risk of a decrease in the stability of the capacitive load drive circuit is reduced, and the risk of a decrease in the waveform accuracy of the drive signal output by the capacitive load drive circuit is reduced.

[0175] In one embodiment of the capacitive load drive circuit, A second drive signal output circuit that receives a second digital signal and outputs a second drive signal, and a plurality of drive signal output circuits including the first drive signal output circuit, A second amplification circuit that amplifies the second drive signal and outputs a second drive signal for driving a second capacitive load, and a plurality of amplification circuits including the first amplification circuit, Equipped with, The plurality of amplification circuits are provided on the first substrate surface and not on the second substrate surface. The plurality of base drive signal output circuits are provided on the second substrate surface, but may not be provided on the first substrate surface.

[0176] In this capacitive load drive circuit, multiple amplification circuits that generate a large amount of heat are provided on the first substrate surface, which is one side of the wiring board, and multiple base drive signal output circuits that generate a large amount of heat are provided on the second substrate surface, which is the other side of the wiring board. As a result, the heat generated by the multiple amplification circuits and the heat generated by the multiple base drive signal output circuits on the wiring board mutually affect each other, reducing the risk of the temperature of the capacitive load drive circuit rising. Therefore, the risk of a decrease in the stability of the capacitive load drive circuit is reduced, and the risk of a decrease in the waveform accuracy of the drive signal output by the capacitive load drive circuit is reduced.

[0177] In one embodiment of the capacitive load drive circuit, A first heat dissipation member thermally connected to the first amplification circuit, A second heat dissipation member is thermally connected to the first drive signal output circuit, It may be provided.

[0178] In this capacitive load drive circuit, the heat generated in the first amplifier circuit, which generates a large amount of heat, is facilitated by the first heat dissipation member, and the heat generated in the first drive signal output circuit, which also generates a large amount of heat, is facilitated by the second heat dissipation member. Therefore, the risk of the first amplifier circuit, which generates a large amount of heat, becoming overheated is reduced, and the risk of the first drive signal output circuit, which generates a large amount of heat, becoming overheated is also reduced. Consequently, the risk of the temperature of the capacitive load drive circuit rising is further reduced. Consequently, the risk of the stability of the capacitive load drive circuit decreasing is further reduced, and the risk of the waveform accuracy of the drive signal output by the capacitive load drive circuit decreasing is further reduced.

[0179] In one embodiment of the capacitive load drive circuit, The second heat dissipation member may be thermally connected to the first amplification circuit via the wiring board.

[0180] With this capacitive load drive circuit, the heat generated in the first amplifier circuit, which generates a large amount of heat, is dissipated not only by the first heat dissipation member but also by the second heat dissipation member. Therefore, the risk of the first amplifier circuit, which generates a large amount of heat, becoming overheated is further reduced. Consequently, the risk of the temperature of the capacitive load drive circuit rising is further reduced. Consequently, the risk of the stability of the capacitive load drive circuit decreasing is further reduced, and the risk of the waveform accuracy of the drive signal output by the capacitive load drive circuit decreasing is further reduced.

[0181] In one embodiment of the capacitive load drive circuit, The aforementioned second heat dissipation member is A first protrusion is thermally connected to the first drive signal output circuit, A second protrusion is thermally connected to the first amplification circuit via the aforementioned wiring board, It may have.

[0182] According to this capacitive load drive circuit, the second heat dissipation member has a first protrusion that is thermally connected to the first drive signal output circuit and a second protrusion that is thermally connected to the first amplifier circuit via a wiring board, thereby dissipating the heat generated in the first drive signal output circuit and the heat generated in the first amplifier circuit. The mutual influence between the two heat dissipation members reduces the risk of decreased heat dissipation efficiency in the second heat dissipation member. Consequently, the risk of the temperature of the capacitive load drive circuit rising is reduced. Therefore, the risk of decreased stability in the capacitive load drive circuit is reduced, and the risk of decreased waveform accuracy of the drive signal output by the capacitive load drive circuit is reduced.

[0183] In one embodiment of the capacitive load drive circuit, The first amplification circuit includes a first transistor and a second transistor, and outputs the first drive signal by driving the first transistor and the second transistor. The first transistor drive signal output circuit may be located between the first transistor and the second transistor.

[0184] This capacitive load drive circuit allows for a shorter wiring length for the first drive signal output from the first drive signal output circuit. As a result, the operational stability of the first amplifier circuit, including the first and second transistors, is improved.

[0185] In one embodiment of the capacitive load drive circuit, The first amplifier circuit comprises a first heat dissipation member and a second heat dissipation member that promote heat dissipation, The first transistor includes a first surface and a second surface that are located opposite each other, The second transistor includes a third and a fourth surface that are located opposite each other, The heat dissipation performance of the first heat dissipation member is higher than that of the second heat dissipation member. The first surface and the third surface are thermally connected to the first heat dissipation member, The second and fourth surfaces are thermally connected to the first substrate surface. The second substrate surface may be thermally connected to the second heat dissipation member.

[0186] In this capacitive load drive circuit, the first transistor in the first amplifier circuit has enhanced heat dissipation from both its first and second surfaces, and the second transistor in the first amplifier circuit has enhanced heat dissipation from both its third and fourth surfaces. Therefore, the heat generated in the first amplifier circuit, including the first and second transistors, is dissipated more efficiently. Consequently, the risk of the first amplifier circuit, including the first and second transistors, becoming overheated is reduced, and the risk of a decrease in the stability of the capacitive load drive circuit is reduced. Consequently, the risk of a decrease in the waveform accuracy of the drive signal output by the capacitive load drive circuit is reduced.

[0187] Furthermore, this capacitive load drive circuit allows the heat dissipation performance of the first heat dissipation member, which promotes heat dissipation from the first surface of the first transistor and the third surface of the second transistor without using a wiring board, to be higher than that of the second heat dissipation member, which promotes heat dissipation from the third surface of the first transistor and the fourth surface of the second transistor via a wiring board. As a result, the heat generated in the first amplifier circuit, including the first and second transistors, can be dissipated more efficiently. Therefore, the risk of the first amplifier circuit, including the first and second transistors, becoming overheated is further reduced. Consequently, the risk of a decrease in the stability of the capacitive load drive circuit is further reduced, and the risk of a decrease in the waveform accuracy of the drive signal output by the capacitive load drive circuit is further reduced.

[0188] In one embodiment of the capacitive load drive circuit, The wiring board may be housed in a housing that includes the first heat dissipation member and the second heat dissipation member.

[0189] This capacitive load drive circuit reduces the risk of ink mist or other contaminants adhering to the first amplifier circuit and the first drive signal output circuit.

[0190] In one embodiment of the capacitive load drive circuit, The first and second transistors may be SIP-type bipolar transistors.

[0191] In one embodiment of the capacitive load drive circuit, The first amplifier circuit may be a Class AB amplifier circuit.

[0192] One embodiment of a liquid dispensing device is: A discharge head that discharges liquid by driving a capacitive load, A capacitive load drive circuit that outputs a drive signal to drive the capacitive load, Equipped with, The capacitive load drive circuit is, A first drive signal output circuit that receives a first digital signal and outputs a first drive signal, A first amplification circuit that amplifies the first drive signal and outputs a first drive signal to drive the first capacitive load, A wiring board comprising a first substrate surface and a second substrate surface located facing each other, on which the first drive signal output circuit and the first amplification circuit are provided, Equipped with, The first amplification circuit is provided on the first substrate surface, The first drive signal output circuit is provided on the second substrate surface.

[0193] In this liquid dispensing device, the first amplification circuit, which generates a large amount of heat, and the first drive signal output circuit, which also generates a large amount of heat, are provided on different sides of the wiring board. As a result, the heat generated by the first amplification circuit and the heat generated by the first drive signal output circuit on the wiring board mutually affect each other, reducing the risk of the temperature of the capacitive load drive circuit rising. Therefore, the risk of a decrease in the stability of the capacitive load drive circuit is reduced, and the risk of a decrease in the waveform accuracy of the drive signal output by the capacitive load drive circuit is reduced.

[0194] In one embodiment of the liquid dispensing device, The capacitive load drive circuit is, A second drive signal output circuit that receives a second digital signal and outputs a second drive signal, and a plurality of drive signal output circuits including the first drive signal output circuit, A second amplification circuit that amplifies the second drive signal and outputs a second drive signal for driving a second capacitive load, and a plurality of amplification circuits including the first amplification circuit, Equipped with, The plurality of amplification circuits are provided on the first substrate surface and not on the second substrate surface. The plurality of base drive signal output circuits are provided on the second substrate surface, but may not be provided on the first substrate surface.

[0195] In this liquid dispensing device, multiple amplification circuits that generate a large amount of heat are provided on the first substrate surface, which is one side of the wiring board, and multiple base drive signal output circuits that generate a large amount of heat are provided on the second substrate surface, which is the other side of the wiring board. As a result, the heat generated by the multiple amplification circuits and the heat generated by the multiple base drive signal output circuits on the wiring board mutually affect each other, reducing the risk of the temperature of the capacitive load drive circuit rising. Therefore, the risk of a decrease in the stability of the capacitive load drive circuit is reduced, and the risk of a decrease in the waveform accuracy of the drive signal output by the capacitive load drive circuit is reduced.

[0196] In one embodiment of the liquid dispensing device, A first heat dissipation member thermally connected to the first amplification circuit, A second heat dissipation member is thermally connected to the first drive signal output circuit, It may be provided.

[0197] With this liquid dispensing device, the heat generated in the first amplification circuit, which generates a large amount of heat, is facilitated by the first heat dissipation member, and the heat generated in the first drive signal output circuit, which also generates a large amount of heat, is facilitated by the second heat dissipation member. Therefore, the risk of the first amplification circuit, which generates a large amount of heat, becoming overheated is reduced, and the risk of the first drive signal output circuit, which generates a large amount of heat, becoming overheated is also reduced. Consequently, the risk of the temperature of the capacitive load drive circuit rising is further reduced. Consequently, the risk of the stability of the capacitive load drive circuit decreasing is further reduced, and the risk of the waveform accuracy of the drive signal output by the capacitive load drive circuit decreasing is further reduced.

[0198] In one embodiment of the liquid dispensing device, The second heat dissipation member may be thermally connected to the first amplification circuit via the wiring board.

[0199] With this liquid dispensing device, the heat generated in the first amplification circuit, which generates a large amount of heat, is dissipated not only by the first heat dissipation member but also by the second heat dissipation member. Therefore, the risk of the first amplification circuit, which generates a large amount of heat, becoming overheated is further reduced. Consequently, the risk of the temperature of the capacitive load drive circuit rising is further reduced. Consequently, the risk of the stability of the capacitive load drive circuit decreasing is further reduced, and the risk of the waveform accuracy of the drive signal output by the capacitive load drive circuit decreasing is further reduced.

[0200] In one embodiment of the liquid dispensing device, The aforementioned second heat dissipation member is A first protrusion is thermally connected to the first drive signal output circuit, A second protrusion is thermally connected to the first amplification circuit via the aforementioned wiring board, It may have.

[0201] According to this liquid dispensing device, the second heat dissipation member has a first protrusion that is thermally connected to the first drive signal output circuit and a second protrusion that is thermally connected to the first amplifier circuit via a wiring board. As a result, the heat generated in the first drive signal output circuit and the heat generated in the first amplifier circuit mutually influence each other in the second heat dissipation member, reducing the risk of a decrease in the heat dissipation efficiency of the second heat dissipation member. Therefore, the risk of the temperature of the capacitive load drive circuit rising is reduced. Consequently, the risk of a decrease in the stability of the capacitive load drive circuit is reduced, and the risk of a decrease in the waveform accuracy of the drive signal output by the capacitive load drive circuit is reduced.

[0202] In one embodiment of the liquid dispensing device, The first amplification circuit includes a first transistor and a second transistor, and outputs the first drive signal by driving the first transistor and the second transistor. The first transistor drive signal output circuit may be located between the first transistor and the second transistor.

[0203] This liquid dispensing device allows for a reduction in the wiring length over which the first drive signal output from the first drive signal output circuit propagates. As a result, the operational stability of the first amplifier circuit, including the first and second transistors, is improved.

[0204] In one embodiment of the liquid dispensing device, The first amplifier circuit comprises a first heat dissipation member and a second heat dissipation member that promote heat dissipation, The first transistor includes a first surface and a second surface that are located opposite each other, The second transistor includes a third and a fourth surface that are located opposite each other, The heat dissipation performance of the first heat dissipation member is higher than that of the second heat dissipation member. The first surface and the third surface are thermally connected to the first heat dissipation member, The second and fourth surfaces are thermally connected to the first substrate surface. The second substrate surface may be thermally connected to the second heat dissipation member.

[0205] With this liquid discharge device, the first transistor in the first amplifier circuit has enhanced heat dissipation from both its first and second surfaces, and the second transistor in the first amplifier circuit has enhanced heat dissipation from both its third and fourth surfaces. Therefore, the heat generated in the first amplifier circuit, including the first and second transistors, is dissipated more efficiently. Consequently, the risk of the first amplifier circuit, including the first and second transistors, becoming overheated is reduced, and the risk of a decrease in the stability of the capacitive load drive circuit is reduced. Consequently, the risk of a decrease in the waveform accuracy of the drive signal output by the capacitive load drive circuit is reduced.

[0206] Furthermore, this liquid dispensing device allows the heat dissipation performance of the first heat dissipation member, which promotes heat dissipation from the first surface of the first transistor and the third surface of the second transistor without using a wiring board, to be higher than that of the second heat dissipation member, which promotes heat dissipation from the third surface of the first transistor and the fourth surface of the second transistor via a wiring board. As a result, the heat generated in the first amplifier circuit, including the first and second transistors, can be dissipated more efficiently. Therefore, the risk of the first amplifier circuit, including the first and second transistors, becoming overheated is further reduced. Consequently, the risk of a decrease in the stability of the capacitive load drive circuit is further reduced, and the risk of a decrease in the waveform accuracy of the drive signal output by the capacitive load drive circuit is further reduced.

[0207] In one embodiment of the liquid dispensing device, The wiring board may be housed in a housing that includes the first heat dissipation member and the second heat dissipation member.

[0208] This liquid dispensing device reduces the risk of ink mist or other contaminants adhering to the first amplification circuit and the first drive signal output circuit.

[0209] In one embodiment of the liquid dispensing device, The first and second transistors may be SIP-type bipolar transistors.

[0210] In one embodiment of the liquid dispensing device, The first amplifier circuit may be a Class AB amplifier circuit. [Explanation of Symbols]

[0211] 1…Liquid dispensing device, 2…Control unit, 3…Liquid container, 4…Transport unit, 5…Dispensing unit, 10…Head drive module, 20…Liquid dispensing module, 23…Dispensing module, 30…Wiring component, 41…Transport motor, 42…Transport roller, 50…Drive signal output circuit, 52, 52a, 52b…Drive circuit, 53…Reference voltage output circuit, 60…Piezoelectric element, 100…Control circuit, 101…Integrated circuit, 120…Conversion circuit, 200…Drive signal selection circuit, 210…Selection control circuit, 212…Shift register, 214…Latch circuit, 216…Decoder, 220…Restore circuit, 230…Selection circuit, 232a, 232b…Inverter, 234 a, 234b…Transfer gate, 500…Integrated circuit, 510…Amplifier control circuit, 511…Memory, 512…Latch circuit, 513…Adder, 514…Latch circuit, 515…D / A converter, 520…Drive circuit, 530…Amplifier circuit, 531…Transistor, 531cp…Semiconductor chip, 531fa, 531fb, 531fc…Lead frame, 531mb, 531md, 531mf…Surface, 531mo…Molded part, 531ta, 531tb, 531tc…External connection terminal, 532…Transistor, 532cp…Semiconductor chip, 532fa, 532fb, 532fc…Lead frame, 532mb, 532md, 532 mf...face, 532mo...molded part, 532ta, 532tb, 532tc...external connection terminals, 541~545...heat conductive material, 600...discharge part, 601...piezoelectric element, 611, 612...electrode, 621...diaphragm, 631...cavity, 632...nozzle plate, 641...reservoir, 651...nozzle, 661...supply port, 710...heat sink, 711...recess, 712...opening, 713...cooling fan, 715...water cooling mechanism, 720...heat sink, 721...recess, 722~724...protrusion, 800...drive circuit board, 810...wiring board, 811~814...edge, 815, 816...face, CN1, CN2...connection part, P...medium

Claims

1. A first drive signal output circuit receives a first digital signal and outputs a first drive signal, A first amplification circuit that amplifies the first drive signal and outputs a first drive signal to drive the first capacitive load, A wiring board including a first substrate surface and a second substrate surface facing each other, on which the first drive signal output circuit and the first amplification circuit are provided, Equipped with, The first amplification circuit is provided on the first substrate surface, The first drive signal output circuit is provided on the second substrate surface, A capacitive load drive circuit characterized by the following features.

2. A second drive signal output circuit that receives a second digital signal and outputs a second drive signal, and a plurality of drive signal output circuits including the first drive signal output circuit, A second amplification circuit that amplifies the second drive signal and outputs a second drive signal for driving a second capacitive load, and a plurality of amplification circuits including the first amplification circuit, Equipped with, The plurality of amplification circuits are provided on the first substrate surface and not on the second substrate surface. The plurality of base drive signal output circuits are provided on the second substrate surface and not on the first substrate surface. Capacitive load drive circuit according to feature 1.

3. A first heat dissipation member thermally connected to the first amplification circuit, A second heat dissipation member is thermally connected to the first drive signal output circuit, Equipped with, Capacitive load drive circuit according to feature 1.

4. The second heat dissipation member is thermally connected to the first amplification circuit via the wiring board. Capacitive load drive circuit according to feature 3.

5. The second heat dissipation member is A first protrusion is thermally connected to the first drive signal output circuit, A second protrusion is thermally connected to the first amplification circuit via the aforementioned wiring board, Having, Capacitive load drive circuit according to feature 4.

6. The first amplification circuit includes a first transistor and a second transistor, and outputs the first drive signal by driving the first transistor and the second transistor. The first transistor drive signal output circuit is located between the first transistor and the second transistor. Capacitive load drive circuit according to feature 1.

7. The first amplifier circuit comprises a first heat dissipation member and a second heat dissipation member that promote heat dissipation, The first transistor includes a first surface and a second surface that are located opposite each other, The second transistor includes a third and a fourth surface that are located opposite each other, The heat dissipation performance of the first heat dissipation member is higher than that of the second heat dissipation member. The first surface and the third surface are thermally connected to the first heat dissipation member, The second and fourth surfaces are thermally connected to the first substrate surface. The second substrate surface is thermally connected to the second heat dissipation member. Capacitive load drive circuit according to feature 6.

8. The wiring board is housed in a housing that includes the first heat dissipation member and the second heat dissipation member. Capacitive load drive circuit according to feature 7.

9. The first and second transistors are SIP-type bipolar transistors. Capacitive load drive circuit according to feature 8.

10. The first amplifier circuit is a Class AB amplifier circuit. A capacitive load drive circuit according to any one of claims 1 to 9.

11. A discharge head that discharges liquid by driving a capacitive load, A capacitive load drive circuit that outputs a drive signal to drive the capacitive load, Equipped with, The capacitive load drive circuit is, A first drive signal output circuit receives a first digital signal and outputs a first drive signal, A first amplification circuit that amplifies the first drive signal and outputs a first drive signal to drive the first capacitive load, A wiring board including a first substrate surface and a second substrate surface facing each other, on which the first drive signal output circuit and the first amplification circuit are provided, Equipped with, The first amplification circuit is provided on the first substrate surface, The first drive signal output circuit is provided on the second substrate surface, A liquid dispensing device characterized by the following features.

12. The capacitive load drive circuit is, A second drive signal output circuit that receives a second digital signal and outputs a second drive signal, and a plurality of drive signal output circuits including the first drive signal output circuit, A second amplification circuit that amplifies the second drive signal and outputs a second drive signal for driving a second capacitive load, and a plurality of amplification circuits including the first amplification circuit, Equipped with, The plurality of amplification circuits are provided on the first substrate surface and not on the second substrate surface. The plurality of base drive signal output circuits are provided on the second substrate surface and not on the first substrate surface. The liquid dispensing device according to feature 11.

13. A first heat dissipation member thermally connected to the first amplification circuit, A second heat dissipation member is thermally connected to the first drive signal output circuit, Equipped with, The liquid dispensing device according to feature 11.

14. The second heat dissipation member is thermally connected to the first amplification circuit via the wiring board. The liquid dispensing device according to feature 13.

15. The second heat dissipation member is A first protrusion is thermally connected to the first drive signal output circuit, A second protrusion is thermally connected to the first amplification circuit via the aforementioned wiring board, Having, The liquid dispensing device according to feature 14.

16. The first amplification circuit includes a first transistor and a second transistor, and outputs the first drive signal by driving the first transistor and the second transistor. The first transistor drive signal output circuit is located between the first transistor and the second transistor. The liquid dispensing device according to feature 11.

17. The first amplifier circuit comprises a first heat dissipation member and a second heat dissipation member that promote heat dissipation, The first transistor includes a first surface and a second surface that are located opposite each other, The second transistor includes a third and a fourth surface that are located opposite each other, The heat dissipation performance of the first heat dissipation member is higher than that of the second heat dissipation member. The first surface and the third surface are thermally connected to the first heat dissipation member, The second and fourth surfaces are thermally connected to the first substrate surface. The second substrate surface is thermally connected to the second heat dissipation member. The liquid dispensing device according to feature 16.

18. The wiring board is housed in a housing that includes the first heat dissipation member and the second heat dissipation member. The liquid dispensing device according to feature 17.

19. The first and second transistors are SIP-type bipolar transistors. The liquid dispensing device according to feature 18.

20. The first amplifier circuit is a Class AB amplifier circuit. A liquid dispensing device according to any one of claims 11 to 19.

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