Liquid ejecting apparatus and driving device

Abstract

To suppress an increase in temperature of an analog conversion circuit for designating a waveform of a drive signal.SOLUTION: A liquid discharge apparatus includes a liquid discharge head that is driven by a drive signal to discharge a liquid, a first substrate, a transistor pair that is provided on the first substrate and includes two bipolar transistors that generate the drive signal, a second substrate, and an analog conversion circuit that is provided on the second substrate and converts a digital first waveform signal that designates a waveform of the drive signal into an analog second waveform signal that designates the waveform of the drive signal.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection device and a driving device. [Background technology]

[0002] There is known a liquid ejection device that includes a liquid ejection head that ejects liquid such as ink in response to drive by a drive signal, and a drive signal generation circuit that supplies the drive signal to the liquid ejection head. For example, Patent Document 1 discloses a liquid ejection device that is provided with a drive signal generation circuit that includes an analog conversion circuit that specifies the waveform of the drive signal, and a transistor pair that generates the drive signal based on the output from the analog conversion circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-099852 Summary of the Invention [Problem to be solved by the invention]

[0004] The drive signal that drives the liquid ejection head is a large-amplitude signal, and the transistor pair generates heat when generating the drive signal. When the drive signal generation circuit generates the drive signal, the heat generated by the transistor pair can be transmitted to the analog conversion circuit, causing the analog conversion circuit to become very hot. This can cause the analog conversion circuit to become unstable when the drive signal generation circuit generates the drive signal. [Means for solving the problem]

[0005] In order to solve the above problems, the liquid ejection device of the present invention comprises a liquid ejection head that is driven by a drive signal to eject liquid, a first substrate, a transistor pair provided on the first substrate and including two bipolar transistors that generate the drive signal, a second substrate, and an analog conversion circuit provided on the second substrate that converts a digital first waveform signal that specifies the waveform of the drive signal into an analog second waveform signal that specifies the waveform of the drive signal, wherein the transistor pair generates the drive signal based on the second waveform signal, and the second substrate is provided separately from the first substrate.

[0006] Furthermore, a driving device according to the present invention is a driving device that supplies a driving signal to a liquid ejection head that is driven by the driving signal to eject liquid, and is characterized in that it comprises a first substrate, a transistor pair provided on the first substrate and including two bipolar transistors that generate the driving signal, a second substrate, and an analog conversion circuit provided on the second substrate that converts a digital first waveform signal that specifies the waveform of the driving signal into an analog second waveform signal that specifies the waveform of the driving signal, wherein the transistor pair generates the driving signal based on the second waveform signal, and the second substrate is provided separately from the first substrate. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a block diagram showing an example of the configuration of an inkjet printer 1 according to an embodiment of the invention. [Figure 2] FIG. 1 is a perspective view showing an example of a schematic internal structure of an inkjet printer 1. [Figure 3] FIG. 10 is a cross-sectional view showing an example of the structure of a discharge section D[m]. [Figure 4] 2 is a block diagram showing an example of the configuration of a liquid ejection unit 3. FIG. [Figure 5] 10 is a timing chart showing an example of a signal supplied to the liquid ejection unit 3. [Figure 6]It is an explanatory diagram showing an example of the individual designation signal Sd[m]. [Figure 7] It is a block diagram showing an example of the configuration of the drive signal generation circuit 50. [Figure 8] It is an exploded perspective view showing an example of the structure of the drive control unit 8. [Figure 9] It is a plan view showing an example of the component arrangement on the transistor substrate 501. [Figure 10] It is a cross-sectional view showing an example of the structure of the drive control unit 8. [Figure 11] [[ID=I15]]It is an explanatory diagram showing the thermal conductivity and specific gravity of various metals. [Figure 12] It is a block diagram showing an example of the configuration of the drive signal generation circuit 50B according to Modification 3 of the present invention. [Figure 13] It is a block diagram showing an example of the configuration of the inkjet printer 1C according to Modification 4 of the present invention.

Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, in each figure, the dimensions and scales of each part are appropriately different from the actual ones. Further, the embodiments described below are preferred specific examples of the present invention, and thus various technically preferable limitations are imposed. However, the scope of the present invention is not limited to these embodiments unless there is a description to specifically limit the present invention in the following description.

[0009] <<A. Embodiment>> Hereinafter, the liquid ejection device will be described by exemplifying an inkjet printer 1 that ejects ink to form an image on a recording paper PP.

[0010] <<A.1. Outline of Inkjet Printer 1>> Hereinafter, an example of the configuration of the inkjet printer 1 according to the present embodiment will be described while referring to FIGS. 1 to 3.

[0011] FIG. 1 is a functional block diagram showing an example of the configuration of an inkjet printer 1.

[0012] 1, print data Img indicating the image to be formed by the inkjet printer 1 is supplied from a host computer such as a personal computer or digital camera to the inkjet printer 1. The inkjet printer 1 executes a printing process to form the image indicated by the print data Img supplied from the host computer on recording paper PP.

[0013] As shown in Figure 1, the inkjet printer 1 includes a control unit 2 that controls each part of the inkjet printer 1, a liquid ejection unit 3 provided with an ejection section D that ejects ink onto recording paper PP, a drive signal generation unit 5 provided with a drive signal generation circuit 50 that generates a drive signal Com for driving the ejection section D, and a transport unit 9 that transports the liquid ejection unit 3 and recording paper PP. In this embodiment, the inkjet printer 1 is an example of a "liquid ejection device," the liquid ejection unit 3 is an example of a "liquid ejection head," ink is an example of a "liquid," and the recording paper PP is an example of a "medium." In addition, hereinafter, a configuration including the control unit 2 and the drive signal generation unit 5 will be referred to as a "drive control unit 8." In this embodiment, the drive control unit 8 is an example of a "drive device."

[0014] In this embodiment, it is assumed that the inkjet printer 1 includes one or more liquid ejection units 3. Specifically, in this embodiment, as an example, it is assumed that the inkjet printer 1 includes four liquid ejection units 3. For ease of explanation, the following description may focus on one of the four liquid ejection units 3, as shown in FIG. 1.

[0015] In addition, in this embodiment, as an example, it is assumed that the drive signal generation unit 5 includes one or more drive signal generation circuits 50 corresponding to one liquid ejection unit 3. Specifically, in this embodiment, it is assumed that the drive signal generation unit 5 includes two drive signal generation circuits 50 corresponding to one liquid ejection unit 3. That is, in this embodiment, it is assumed that the drive signal generation unit 5 includes eight drive signal generation circuits 50 corresponding to four liquid ejection units 3. However, the present invention is not limited to this aspect. The drive signal generation unit 5 may include one drive signal generation circuit 50 corresponding to one liquid ejection unit 3, or may include three or more drive signal generation circuits 50 corresponding to one liquid ejection unit 3. Note that, for convenience of explanation, the following description may focus on one of the eight drive signal generation circuits 50 as shown in FIG. 1.

[0016] The control unit 2 includes a control circuit 21 and a memory circuit 22.

[0017] Of these, the memory circuit 22 is composed of volatile memory such as RAM (Random Access Memory) and non-volatile memory such as ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), or PROM (Programmable ROM), and stores various information such as the control program of the inkjet printer 1.

[0018] The control circuit 21 is configured to include one or more CPUs (Central Processing Units). However, instead of or in addition to a CPU, the control circuit 21 may include a programmable logic device such as an FPGA (field-programmable gate array). The control circuit 21 executes a control program for the inkjet printer 1 stored in the memory circuit 22 and operates in accordance with this control program to control each part of the inkjet printer 1. Specifically, the control circuit 21 generates signals for controlling the operation of each part of the inkjet printer 1, such as a specification signal SI, a waveform specification signal dCom, a carriage transport control signal SK, and a medium transport control signal SB.

[0019] Here, the waveform specification signal dCom is a digital signal that defines the waveform of the drive signal Com. The drive signal Com is an analog signal for driving the discharge section D. The specification signal SI is a digital signal that specifies the type of operation of the discharge section D. Specifically, the specification signal SI specifies whether or not to supply the drive signal Com to the discharge section D, thereby specifying the type of operation of the discharge section D, such as whether or not to discharge ink from the discharge section D. The carriage transport control signal SK and the medium transport control signal SB are signals for controlling the transport unit 9. In this embodiment, the waveform designation signal dCom is an example of a "first waveform signal."

[0020] When a printing process is performed, the control unit 2 generates signals, such as a designation signal SI, for controlling the liquid ejection unit 3 based on the print data Img. Furthermore, when a printing process is performed, the control unit 2 generates signals, such as a waveform designation signal dCom, for controlling the drive signal generation unit 5. Furthermore, when a printing process is performed, the control unit 2 generates signals, such as a carriage transport control signal SK and a medium transport control signal SB, for controlling the transport unit 9. In this way, during the printing process, the control unit 2 controls the transport unit 9 to move the liquid ejection unit 3 and the recording paper PP, while also adjusting the presence or absence of ink ejection from the ejection section D, the timing of ink ejection, and the like, and controls each part of the inkjet printer 1 so that an image corresponding to the print data Img is formed on the recording paper PP.

[0021] As shown in FIG. 1, the liquid ejection unit 3 includes a supply circuit 31 and a head unit 32.

[0022] The head unit 32 has M discharge units D. Here, the value M is a natural number that satisfies "M≧1." Note that, hereinafter, the mth discharge unit D of the M discharge units D provided in the head unit 32 may be referred to as discharge unit D[m]. Here, the variable m is a natural number that satisfies "1≦m≦M." Furthermore, hereinafter, when a component or signal of the inkjet printer 1 corresponds to a discharge unit D[m] among the M discharge units D, the subscript [m] may be added to the symbol representing the component or signal. The supply circuit 31 switches whether to supply the drive signal Com to the discharge section D[m] based on the designation signal SI. Hereinafter, the drive signal Com supplied to the discharge section D[m] may be referred to as the supply drive signal Vin[m].

[0023] As shown in FIG. 1, the transport unit 9 includes a carriage transport motor 91 and a medium transport motor 92.

[0024] The carriage transport motor 91 transports a carriage 110, which will be described later, based on a carriage transport control signal SK. The medium transport motor 92 transports the recording paper PP based on the medium transport control signal SB.

[0025] FIG. 2 is a perspective view showing an example of the general internal structure of the inkjet printer 1. As shown in FIG.

[0026] 2, this embodiment assumes that the inkjet printer 1 is a serial printer. Specifically, when executing a printing process, the inkjet printer 1 transports the recording paper PP in the X1 direction, while moving the liquid ejection unit 3 in the Y1 direction that intersects the X1 direction, or in the Y2 direction opposite the Y1 direction, and ejects ink from the liquid ejection unit 3 to form an image on the recording paper PP according to the print data Img.

[0027] Hereinafter, the X1 direction and its opposite X2 direction will be collectively referred to as the "X-axis direction," the Y1 direction intersecting the X-axis direction and its opposite Y2 direction will be collectively referred to as the "Y-axis direction," and the Z1 direction intersecting the X-axis and Y-axis directions and its opposite Z2 direction will be collectively referred to as the "Z-axis direction." In this embodiment, as an example, a description will be given assuming that the X-axis direction, Y-axis direction, and Z-axis direction are perpendicular to one another. However, the present invention is not limited to this aspect. The X-axis direction, Y-axis direction, and Z-axis direction may intersect one another. In this embodiment, the Z1 direction is the direction in which ink is ejected from the ejection section D.

[0028] 2, the inkjet printer 1 according to this embodiment includes a housing 100 and a carriage 110 that can move back and forth in the Y-axis direction within the housing 100. The carriage 110 is equipped with four liquid ejection units 3 and a drive control unit 8 that includes a control unit 2 and a drive signal generation unit 5.

[0029] As shown in FIG. 2, this embodiment assumes that the carriage 110 is equipped with four ink cartridges 120, each corresponding to one of the four colors of ink: cyan, magenta, yellow, and black. Furthermore, as described above, this embodiment assumes that the carriage 110 is equipped with four liquid ejection units 3, each corresponding to one of the four ink cartridges 120. Each ejection section D[m] receives a supply of ink from the ink cartridge 120 corresponding to the liquid ejection unit 3 in which the ejection section D[m] is provided. This allows each ejection section D[m] to be filled with the supplied ink, and to eject the ink filled inside the ejection section D[m] from the nozzle N provided in the ejection section D[m]. The ink cartridges 120 may be provided outside the carriage 110.

[0030] As described above, the inkjet printer 1 according to this embodiment also includes a transport unit 9. As shown in Fig. 2, the transport unit 9 includes a carriage transport motor 91 for reciprocating the carriage 110 in the Y-axis direction, a carriage guide shaft 96 that supports the carriage 110 so that it can reciprocate in the Y-axis direction, a belt 97 that transports the carriage 110 in the Y-axis direction based on the drive of the carriage transport motor 91, a medium transport motor 92 for transporting the recording paper PP in the X1 direction, a medium transport mechanism 93 that rotates based on the drive of the medium transport motor 92 to transport the recording paper PP in the X1 direction, and a platen 95 that is provided on the Z1 side of the carriage 110 and supports the recording paper PP. Therefore, when a printing process is performed, the transport unit 9 uses the carriage transport motor 91 to move the liquid ejection unit 3 and the carriage 110 back and forth in the Y-axis direction along the carriage guide shaft 96, and the medium transport motor 92 to transport the recording paper PP on the platen 95 in the X1 direction, thereby changing the relative position of the recording paper PP with respect to the liquid ejection unit 3 and enabling ink to land on the entire recording paper PP.

[0031] FIG. 3 is a schematic partial cross-sectional view of the head unit 32, in which the head unit 32 is cut so as to include the discharge unit D[m].

[0032] As shown in FIG. 3, the ejection unit D[m] includes a piezoelectric element PZ[m], a cavity CV[m] filled with ink inside, a nozzle N[m] communicating with the cavity CV[m], and a diaphragm 321. When the piezoelectric element PZ[m] is driven by a supply drive signal Vin[m], the ejection unit D[m] ejects the ink in the cavity CV[m] from the nozzle N[m]. The cavity CV[m] is a space partitioned by a cavity plate 324, a nozzle plate 323 in which the nozzle N[m] is formed, and the diaphragm 321. The cavity CV[m] communicates with a reservoir 325 via an ink supply port 326. The reservoir 325 communicates with an ink cartridge 120 corresponding to the ejection unit D[m] via an ink inlet 327. The piezoelectric element PZ[m] has an upper electrode Zu[m], a lower electrode Zd[m], and a piezoelectric body Zm[m] provided between the upper electrode Zu[m] and the lower electrode Zd[m]. The lower electrode Zd[m] is electrically connected to a power supply line LD set to a predetermined potential VBS. When a supply drive signal Vin[m] is supplied to the upper electrode Zu[m] and a voltage is applied between the upper electrode Zu[m] and the lower electrode Zd[m], the piezoelectric element PZ[m] is displaced in the Z1 direction and the Z2 direction according to the applied voltage. As a result, the piezoelectric element PZ[m] vibrates. The lower electrode Zd[m] is joined to the diaphragm 321. Therefore, when the piezoelectric element PZ[m] is driven by the supply drive signal Vin[m] and vibrates, the diaphragm 321 also vibrates. Then, the vibration of the diaphragm 321 changes the volume of the cavity CV[m] and the pressure inside the cavity CV[m], and the ink filled in the cavity CV[m] is ejected from the nozzle N[m].

[0033] <<A.2. Configuration and Operation of Liquid Ejection Unit 3>> Hereinafter, an example of the configuration and operation of the liquid ejection unit 3 will be described while referring to FIGS. 4 to FIG. 6.

[0034] FIG. 4 is a block diagram showing an example of the configuration of the liquid ejection unit 3.

[0035] 4, the liquid ejection unit 3 includes a supply circuit 31 and a head unit 32. The liquid ejection unit 3 also includes a wiring LC to which a drive signal Com is supplied from the drive signal generation unit 5.

[0036] As shown in FIG. 4, the supply circuit 31 includes M switches WS[1] to WS[M] that correspond one-to-one to M discharge sections D[1] to D[M], and a connection state designation circuit 310 that designates the connection state of each switch. The connection state designation circuit 310 generates a connection state designation signal QS[m] that designates the on / off state of the switch WS[m] based on at least some of the designation signal SI, latch signal LAT, change signal CH, and clock signal CLK supplied from the control unit 2. The switch WS[m] switches between conduction and non-conduction between the wiring LC and the upper electrode Zu[m] of the piezoelectric element PZ[m] provided in the discharge section D[m] based on the connection state designation signal QS[m]. In this embodiment, the switch WS[m] is turned on when the connection state designation signal QS[m] is at a high level and turned off when the connection state designation signal QS[m] is at a low level. When the switch WS[m] is turned on, the drive signal Com supplied to the wiring LC is supplied to the upper electrode Zu[m] of the discharge section D[m] as the supply drive signal Vin[m].

[0037] FIG. 5 is a timing chart showing an example of various signals such as the drive signal Com supplied to the liquid ejection unit 3. In FIG.

[0038] 5, when the inkjet printer 1 executes a printing process, one or more unit periods TP are set as the operating period of the inkjet printer 1. In this embodiment, during each unit period TP, the inkjet printer 1 can drive each discharge section D[m] for the printing process.

[0039] As shown in Figure 5, the control unit 2 outputs a latch signal LAT having a pulse PLL. As a result, the control unit 2 defines a unit period TP as the period from the rising edge of the pulse PLL to the rising edge of the next pulse PLL. The control unit 2 also outputs a change signal CH having a pulse PLC during the unit period TP. The control unit 2 then divides the unit period TP into a drive period TQ1 from the rising edge of the pulse PLL to the rising edge of the pulse PLC, and a drive period TQ2 from the rising edge of the pulse PLC to the rising edge of the pulse PLL.

[0040] As shown in FIG. 5, the designation signal SI includes M individual designation signals Sd[1] to Sd[M] that correspond one-to-one to the M discharge sections D[1] to D[M]. The individual designation signal Sd[m] designates the drive mode of the discharge section D[m] during each unit period TP when the inkjet printer 1 executes a printing process. Prior to each unit period TP, the control unit 2 synchronizes the designation signal SI, including the M individual designation signals Sd[1] to Sd[M], with the clock signal CLK and supplies it to the connection state designation circuit 310. The connection state designation circuit 310 then generates a connection state designation signal QS[m] during that unit period TP based on the individual designation signal Sd[m].

[0041] In this embodiment, it is assumed that during the unit period TP in which the printing process is executed, the ejection section D[m] is capable of forming any of the following dots: a large dot made of ink with an ink amount ξ1, a medium dot made of ink with an ink amount ξ2 which is less than the ink amount ξ1, or a small dot made of ink with an ink amount ξ3 which is less than the ink amount ξ2.

[0042] FIG. 6 is an explanatory diagram illustrating an example of the individual designation signal Sd[m].

[0043] As shown in Figure 6, in this embodiment, the individual designation signal Sd[m] can take any one of four values ​​during the unit period TP in which the printing process is executed: the value "1" that designates the discharge section D[m] as a large dot-forming discharge section DP-1; the value "2" that designates the discharge section D[m] as a medium dot-forming discharge section DP-2; the value "3" that designates the discharge section D[m] as a small dot-forming discharge section DP-3; and the value "4" that designates the discharge section D[m] as a non-dot-forming discharge section DP-4. Here, the large-dot-forming discharge section DP-1 is a discharge section D that forms large dots in the unit period TP. The medium-dot-forming discharge section DP-2 is a discharge section D that forms medium dots in the unit period TP. The small-dot-forming discharge section DP-3 is a discharge section D that forms small dots in the unit period TP. The non-dot-forming discharge section DP-4 is a discharge section D that does not form dots in the unit period TP.

[0044] Returning to the explanation of Figure 5. As shown in FIG. 5, in this embodiment, the drive signal Com has a waveform PA1 provided in the drive period TQ1 and a waveform PA2 provided in the drive period TQ2. Of these, the waveform PA1 is a waveform that goes from a potential V0 to a potential VLA1 that is lower than the potential V0, through a potential VHA1 that is higher than the potential V0, and then returns to the potential V0. The waveform PA1 is determined so that when a supply drive signal Vin[m] having the waveform PA1 is supplied to the discharge section D[m], ink equivalent to an ink amount φ1 is ejected from the discharge section D[m]. The waveform PA2 is a waveform that goes from a potential V0 to a potential VLA2 that is lower than the potential V0, through a potential VHA2 that is higher than the potential V0, and then returns to the potential V0. The waveform PA2 is determined so that when a supply drive signal Vin[m] having the waveform PA2 is supplied to the discharge section D[m], ink equivalent to an ink amount φ2 is ejected from the discharge section D[m]. In this embodiment, it is assumed that the ink amount ξ1 corresponds to the sum of the ink amount φ1 and the ink amount φ2, the ink amount ξ2 corresponds to the ink amount φ1, and the ink amount ξ3 corresponds to the ink amount φ2.

[0045] In addition, in this embodiment, as an example, it is assumed that when the potential of the supply drive signal Vin[m] supplied to the ejection section D[m] is high, the volume of the cavity CV[m] provided in the ejection section D[m] is smaller than when the potential is low. Therefore, when the ejection section D[m] is driven by the supply drive signal Vin[m] having the waveform PA1 or the like, the potential of the supply drive signal Vin[m] changes from low to high, causing the ink in the ejection section D[m] to be ejected from the nozzle N[m].

[0046] 6, when the individual designation signal Sd[m] indicates a value of "1" that designates the discharger D[m] as the large-dot-forming discharger DP-1 during the unit period TP, the connection state designation circuit 310 sets the connection state designation signal QS[m] to a high level during the drive periods TQ1 and TQ2. In this case, the switch WS[m] is turned on during the drive periods TQ1 and TQ2. Therefore, during the unit period TP, the discharger D[m] is driven by the supply drive signal Vin[m] having waveforms PA1 and PA2, and discharges ink of an ink amount ξ1 corresponding to a large dot. Furthermore, if the individual designation signal Sd[m] indicates a value of "2" that designates the discharger D[m] as the medium-dot-forming discharger DP-2 during the unit period TP, the connection state designation circuit 310 sets the connection state designation signal QS[m] to a high level during the drive period TQ1. In this case, the switch WS[m] is turned on during the drive period TQ1. As a result, the discharger D[m] is driven by the supply drive signal Vin[m] having the waveform PA1 during the unit period TP, and discharges ink at an ink volume ξ2 corresponding to a medium dot. Furthermore, if the individual designation signal Sd[m] indicates a value of "3" during the unit period TP, which designates the discharge unit D[m] as the small-dot-forming discharge unit DP-3, the connection state designation circuit 310 sets the connection state designation signal QS[m] to a high level during the drive period TQ2. In this case, the switch WS[m] is turned on during the drive period TQ2. Therefore, during the unit period TP, the discharge unit D[m] is driven by the supply drive signal Vin[m] having the waveform PA2, and discharges ink at an ink volume ξ3 corresponding to a small dot. Further, when the individual designation signal Sd[m] indicates the value "4" that designates the discharge unit D[m] as the dot non-forming discharge unit DP-4 in the unit period TP, the connection state designation circuit 310 sets the connection state designation signal QS[m] to the low level throughout the unit period TP. In this case, the switch WS[m] turns off throughout the unit period TP. Therefore, the discharge unit D[m] is not driven by the supply drive signal Vin[m] and does not discharge ink in the unit period TP.

[0047] <<A.3. Configuration of the drive signal generation circuit 50>> Hereinafter, an example of the configuration of the drive signal generation circuit 50 provided in the drive signal generation unit 5 will be described while referring to FIG. 7.

[0048] FIG. 7 is a block diagram showing an example of the circuit configuration of the drive signal generation circuit 50.

[0049] As shown in FIG. 7, the drive signal generation circuit 50 includes an analog conversion circuit 51, a transistor pair 52, and an electrolytic capacitor CC, and generates an analog drive signal Com having the waveform specified by the waveform specification signal dCom based on the digital waveform specification signal dCom. Specifically, the drive signal generation circuit 50 generates the drive signal Com, for example, by amplifying the input signal obtained by analog-converting the waveform specification signal dCom in class AB.

[0050] The analog conversion circuit 51 outputs a waveform specification signal QB including a base supply signal QB1 and a base supply signal QB2 based on the digital waveform specification signal dCom. Specifically, the analog conversion circuit 51 converts the waveform specification signal dCom into an analog input signal, and then generates a base supply signal QB1, which is an analog signal indicating a potential based on the potential of the input signal, and a base supply signal QB2, which is an analog signal indicating a potential based on the potential of the input signal and lower than the base supply signal QB1. Then, the analog conversion circuit 51 outputs the base supply signal QB1 from the output terminal Tn1 and outputs the base supply signal QB2 from the output terminal Tn2. In this embodiment, the waveform designation signal QB is an example of a "second waveform signal."

[0051] The transistor pair 52 is a so-called push-pull circuit that includes an NPN bipolar transistor Tr1 and a PNP bipolar transistor Tr2, and generates a drive signal Com based on base supply signals QB1 and QB2.

[0052] The bipolar transistor Tr1 has a base electrode (B) electrically connected to the output terminal Tn1, and receives a base supply signal QB1 from the output terminal Tn1. The bipolar transistor Tr1 has a collector electrode (C) electrically connected to a power supply line LH set to a power supply potential VHV, and an emitter electrode (E) electrically connected to a line LC for supplying a drive signal Com. The bipolar transistor Tr1 turns on, for example, when the potential of the base supply signal QB1 rises, thereby raising the potential of the drive signal Com. The bipolar transistor Tr1 turns off, for example, when the potential of the base supply signal QB1 is constant and when the potential of the base supply signal QB1 falls.

[0053] The bipolar transistor Tr2 has a base electrode (B) electrically connected to the output terminal Tn2, and receives a base supply signal QB2 from the output terminal Tn2. The bipolar transistor Tr2 has a collector electrode (C) electrically connected to ground, and an emitter electrode (E) electrically connected to a line LC for supplying a drive signal Com. The bipolar transistor Tr2 turns on when the potential of the base supply signal QB2 decreases, thereby decreasing the potential of the drive signal Com. The bipolar transistor Tr2 turns off when the potential of the base supply signal QB2 is constant and when the potential of the base supply signal QB2 increases.

[0054] The electrolytic capacitor CC is a capacitor for supplying current to the transistor pair 52. Specifically, for one of the two electrodes of the electrolytic capacitor CC, one electrode is electrically connected to the power supply line LH and the collector electrode of the bipolar transistor Tr1, and the other electrode is electrically connected to the ground.

[0055] <<A.4. Configuration of the drive control unit 8>> Hereinafter, an example of the configuration of the drive control unit 8 will be described while referring to FIGS. 8 to 11.

[0056] FIG. 8 is an exploded perspective view showing an example of the configuration of the drive control unit 8.

[0057] As shown in FIG. 8, the drive control unit 8 includes a control board 200, a transistor board 501, an analog conversion circuit board 502, a transistor cooling mechanism CL1, and an analog conversion circuit cooling mechanism CL2. In this embodiment, as an example, it is assumed that the control board 200, the transistor board 501, and the analog conversion circuit board 502 are provided so as to extend on a plane having the Z1 direction as the normal direction. In this embodiment, the transistor board 501 is an example of the "first board", the analog conversion circuit board 502 is an example of the "second board", and the control board 200 is an example of the "third board".

[0058] A control circuit 21 and a memory circuit 22 are provided on the control board 200. The above-described control unit 2 includes the control board 200, the control circuit 21, and the memory circuit 22.

[0059] A transistor pair 52 including a bipolar transistor Tr1 and a bipolar transistor Tr2 of the drive signal generation circuit 50 is provided on the transistor substrate 501. Specifically, in this embodiment, it is assumed that the transistor pair 52 is provided on a surface PL11 of the transistor substrate 501, the normal direction of which is the Z2 direction, among multiple surfaces of the transistor substrate 501. As described above, in this embodiment, it is assumed that the drive signal generation circuit 50 includes eight drive signal generation circuits 50. Therefore, in this embodiment, eight bipolar transistors Tr1 and eight bipolar transistors Tr2 of the eight transistor pairs 52 are provided on the surface PL11 of the transistor substrate 501. In the following description, the bipolar transistors Tr1 and Tr2 may be collectively referred to as the bipolar transistor Tr.

[0060] Of the drive signal generation circuit 50, the analog conversion circuit 51 and electrolytic capacitor CC are provided on the analog conversion circuit board 502. Specifically, in this embodiment, it is assumed that the analog conversion circuit 51 and electrolytic capacitor CC are provided on a surface PL21, of the multiple surfaces of the analog conversion circuit board 502, whose normal direction is the Z2 direction. As described above, in this embodiment, it is assumed that the drive signal generation circuit 50 includes eight drive signal generation circuits 50. Therefore, in this embodiment, eight analog conversion circuits 51 and eight electrolytic capacitors CC are provided on the analog conversion circuit board 502.

[0061] The transistor cooling mechanism CL1 includes a heat sink HS1 and a fan FN1. In this embodiment, the transistor cooling mechanism CL1 is an example of a "first cooling mechanism."

[0062] The heat sink HS1 is connected to the transistor substrate 501 and dissipates heat generated in the transistor pairs 52 provided on the transistor substrate 501. In this embodiment, it is assumed that the heat sink HS1 is connected to a surface PL12, of the multiple surfaces of the transistor substrate 501, whose normal direction is the Z1 direction.

[0063] In this embodiment, the transistor substrate 501 has an aluminum base material 75. In this embodiment, the heat sink HS1 is also made of aluminum, as will be described in detail later.

[0064] The fan FN1 is connected to the heat sink HS1 and cools the heat sink HS1. However, the fan FN1 may also be connected to the transistor substrate 501 and cool the transistor substrate 501. Note that this embodiment assumes that the fan FN1 remains in operation while the inkjet printer 1 is executing a printing process and the drive signal generation circuit 50 is generating the drive signal Com. For example, in this embodiment, the fan FN1 may remain in operation when the control unit 2 supplies the waveform specification signal dCom to the drive signal generation circuit 50.

[0065] The analog conversion circuit cooling mechanism CL2 includes a heat sink HS2 and a fan FN2. In this embodiment, the analog conversion circuit cooling mechanism CL2 is an example of a "second cooling mechanism."

[0066] The heat sink HS2 is connected to the analog conversion circuit board 502 and dissipates heat generated in the analog conversion circuit 51 provided on the analog conversion circuit board 502. In this embodiment, it is assumed that the heat sink HS2 is connected to the surface PL21 of the analog conversion circuit board 502. However, the heat sink HS2 may be provided so as to be directly connected to the analog conversion circuit 51 provided on the surface PL21 of the analog conversion circuit board 502.

[0067] In this embodiment, the analog conversion circuit board 502 has an aluminum base material, as will be described in detail later. Also, in this embodiment, the heat sink HS2 is made of aluminum.

[0068] The fan FN2 is connected to the heat sink HS2 and cools the heat sink HS2. However, the fan FN2 may also be connected to the analog conversion circuit board 502 and cool the analog conversion circuit board 502. The fan FN2 may also be connected to the analog conversion circuit 51 and cool the analog conversion circuit 51. Note that this embodiment assumes that the fan FN2 remains in operation while the inkjet printer 1 is executing a printing process and the drive signal generation circuit 50 is generating the drive signal Com. For example, in this embodiment, the fan FN2 may remain in operation when the control unit 2 supplies the waveform specification signal dCom to the drive signal generation circuit 50.

[0069] The transistor substrate 501 and the analog conversion circuit board 502 are connected by a board-to-board connector CN1. Specifically, the board-to-board connector CN1 includes a receptacle CN11 fixed to a surface PL11 of the transistor substrate 501, and a plug CN12 fixed to a surface PL22 of the analog conversion circuit board 502, the surface having a normal direction in the Z1 direction, and matable with the receptacle CN11. By mating the receptacle CN11 with the plug CN12, the board-to-board connector CN1 fixes the transistor substrate 501 and the analog conversion circuit board 502 and transmits signals between the transistor substrate 501 and the analog conversion circuit board 502.

[0070] The analog conversion circuit board 502 and the control board 200 are connected by a board-to-board connector CN2. Specifically, the board-to-board connector CN2 includes a receptacle CN21 fixed to a surface PL21 of the analog conversion circuit board 502, and a plug CN22 fixed to a surface of the control board 200 whose normal direction is the Z1 direction, among multiple surfaces of the control board 200, and matable with the receptacle CN21. The board-to-board connector CN2 fixes the analog conversion circuit board 502 and the control board 200 together by mating the receptacle CN21 with the plug CN22, and transmits signals between the analog conversion circuit board 502 and the control board 200.

[0071] FIG. 9 is a plan view showing an example of the arrangement of various electronic components on the transistor substrate 501 when the transistor substrate 501 is viewed in a plane in the Z1 direction.

[0072] As shown in FIG. 9 , the transistor substrate 501 includes a long side LY1 extending in the Y1 direction and located at an end of the transistor substrate 501 in the X2 direction; a long side LY2 extending in the Y1 direction opposite the long side LY1 and located at an end of the transistor substrate 501 in the X1 direction; a short side LX1 extending in the X1 direction and located at an end of the transistor substrate 501 in the Y2 direction; and a short side LX2 extending in the X1 direction opposite the short side LX1 and located at an end of the transistor substrate 501 in the Y1 direction. In this embodiment, the long side LY1 and the long side LY2 have approximately the same length, and the short side LX1 and the short side LX2 have approximately the same length, with the long side LY1 being longer than the short side LX1. Here, "approximately the same" includes cases where the two are completely the same, as well as cases where they can be considered the same taking into account tolerances. For example, "approximately the same" may also mean that the two are the same in terms of design. Furthermore, "substantially the same" may be a concept that includes cases where they can be considered to be the same with an error of about 5% taken into consideration.

[0073] When the transistor substrate 501 is viewed in a plane in the Z1 direction, the surface PL11 of the transistor substrate 501 is divided into an end region AT1 including the long side LY1, an end region AT2 including the long side LY2, and a central region AM arranged between the end region AT1 and the end region AT2.

[0074] As shown in FIG. 9 , this embodiment assumes that the 16 bipolar transistors Tr included in the drive signal generation circuit 50 are provided in the edge region AT1 or the edge region AT2. Specifically, this embodiment assumes that eight of the 16 bipolar transistors Tr included in the drive signal generation circuit 50 are provided in the edge region AT1, and eight of the 16 bipolar transistors Tr included in the drive signal generation circuit 50 are provided in the edge region AT2. That is, this embodiment assumes that the 16 bipolar transistors Tr included in the drive signal generation circuit 50 are arranged along the long side LY1 or the long side LY2. Therefore, according to this embodiment, heat generated by the bipolar transistors Tr can be dissipated more efficiently from the long side LY1 or the long side LY2 than when the bipolar transistors Tr are provided in the central region AM.

[0075] 9, this embodiment assumes that the board-to-board connector CN1 is provided in the central region AM. Therefore, according to this embodiment, it is possible to reduce fluctuations in the relative position and posture between the transistor substrate 501 and the analog conversion circuit board 502 compared to an embodiment in which the board-to-board connector CN1 is provided in the end region AT1 or end region AT2, and it is possible to stably connect the transistor substrate 501 and the analog conversion circuit board 502 by the board-to-board connector CN1.

[0076] FIG. 10 is a cross-sectional view showing an example of the cross-sectional configuration of the transistor substrate 501, the bipolar transistor Tr, and the heat sink HS1.

[0077] 10, the bipolar transistor Tr includes a chip body 61, a base electrode 62B, a collector electrode 62C, and an emitter electrode 62E. Although the collector electrode 62C and the emitter electrode 62E are not shown in Fig. 10, the collector electrode 62C is located, for example, in the X1 direction from the base electrode 62B, and the emitter electrode 62E is located, for example, in the X2 direction from the base electrode 62B.

[0078] As shown in FIG. 10, the transistor substrate 501 includes a wiring layer 71, an insulating layer 72, a wiring layer 73, an insulating layer 74, and a base material 75.

[0079] The wiring layer 71 includes an insulating resist 712, a wiring 711B electrically connected to the base electrode 62B via a wiring 63B, a wiring 711C electrically connected to the collector electrode 62C via a wiring 63C (not shown), and a wiring 711E electrically connected to the emitter electrode 62E via a wiring 63E (not shown). While the wiring 711C and the wiring 711E are not shown in FIG. 10, the wiring 711C is, for example, arranged in a state insulated from the wiring 711B in the X1 direction relative to the wiring 711B, and the wiring 711E is, for example, arranged in a state insulated from the wiring 711B in the X2 direction relative to the wiring 711B. Of the surfaces of the wiring layer 71, the surface facing the Z2 direction corresponds to a surface PL11.

[0080] The insulating layer 72 includes an insulating portion 722 made of an insulating material, a connection wiring 721B electrically connected to the wiring 711B, a connection wiring 721C electrically connected to the wiring 711C, and a connection wiring 721E electrically connected to the wiring 711E. Note that although the connection wiring 721C and the connection wiring 721E are not shown in Fig. 10, the connection wiring 721C is arranged, for example, in a state insulated from the connection wiring 721B in the X1 direction relative to the connection wiring 721B, and the connection wiring 721E is arranged, for example, insulated from the connection wiring 721B in the X2 direction relative to the connection wiring 721B.

[0081] The wiring layer 73 includes an insulating portion 732 formed of an insulating material, a wiring 731B electrically connected to the connection wiring 721B, a wiring 731C electrically connected to the connection wiring 721C, and a wiring 731E electrically connected to the connection wiring 721E. Note that although the wiring 731C and the wiring 731E are not shown in Fig. 10, the wiring 731C is arranged, for example, in a state insulated from the wiring 731B in the X1 direction relative to the wiring 731B, and the wiring 731E is arranged, for example, insulated from the wiring 731B in the X2 direction relative to the wiring 731B.

[0082] The insulating layer 74 electrically insulates the wiring 731B, the wiring 731C, and the wiring 731E provided on the wiring layer 73 from the base material 75.

[0083] The base material 75 is made of aluminum. In this embodiment, it is assumed that the heat sink HS1 is connected to the base material 75 by grease 64. However, the heat sink HS1 may also be connected to the base material 75 by a heat dissipation sheet. Of the surfaces of the base material 75, the surface facing the Z1 direction corresponds to surface PL12.

[0084] As shown in FIG. 10, the bipolar transistor Tr is provided so that a surface 600 having the largest area among the surfaces of the bipolar transistor Tr is connected to a surface PL11 of the wiring layer 71 of the transistor substrate 501.

[0085] The bipolar transistor Tr is fixed to the transistor substrate 501 by screws 65. Specifically, in this embodiment, the bipolar transistor Tr is fixed to the transistor substrate 501 and the heat sink HS1 by screws 65 that penetrate the transistor substrate 501. In this embodiment, it is assumed that the screws 65 are made of metal. However, the screws 65 may be non-metallic. However, it is preferable that the screws 65 be made of a material that has higher thermal conductivity than the resist 712, the insulating portion 722, the insulating portion 732, and the insulating layer 74 of the transistor substrate 501.

[0086] As described above, in this embodiment, the base material 75 of the transistor substrate 501 is made of aluminum. Also, in this embodiment, the heat sink HS1 is made of aluminum.

[0087] FIG. 11 is a diagram showing the thermal conductivity and specific gravity of various metals.

[0088] As shown in FIG. 11 , the thermal conductivity of copper is 398 W / mk. Therefore, copper has a higher thermal conductivity than aluminum (236 W / mk), iron (67 W / mk), and stainless steel (16 W / mk). That is, by using a copper substrate with a copper base as the transistor substrate 501 and a copper substrate with a copper base as the analog conversion circuit substrate 502, it is possible to efficiently dissipate heat generated in the drive signal generation unit 5. While materials with higher thermal conductivity than copper exist, such as silver (398 W / mk) and diamond (1000 W / mk), their high cost makes them impractical for use as the substrate for the drive signal generation unit 5. For this reason, copper substrates have traditionally been used as the substrate for the drive signal generation unit 5.

[0089] On the other hand, as shown in Figure 11, the specific gravity of aluminum is 2.7 g / cm 3 Therefore, the specific gravity of copper is 8.9 g / cm 3 , specific gravity of iron 7.8g / cm 3 , and the specific gravity of stainless steel is 7.9 g / cm 3Compared to conventional drive signal generation units that use a copper substrate, the specific gravity of aluminum is small. Therefore, the drive signal generation unit 5 according to this embodiment can be made lighter than conventional drive signal generation units that use a copper substrate. As a result, when the drive signal generation unit 5 according to this embodiment is mounted on the carriage 110 and the drive signal generation unit 5 is moved, the load on the carriage transport motor 91 that drives the carriage 110 can be reduced. In other words, the drive signal generation unit 5 according to this embodiment can extend the life of the carriage transport motor 91 and reduce the amount of power required to drive the carriage transport motor 91, compared to conventional drive signal generation units that use a copper substrate.

[0090] As mentioned above, the thermal conductivity of aluminum is lower than that of copper, but higher than that of iron and stainless steel. Therefore, the drive signal generation unit 5 according to this embodiment can reduce the load on the carriage transport motor 91 that drives the carriage 110, while also efficiently dissipating heat in the drive signal generation unit 5.

[0091] Furthermore, a heat sink is typically attached to a drive signal generating unit 5 that generates a large amount of heat to improve the heat dissipation of the drive signal generating unit 5. The heat sink is typically made of aluminum. Therefore, when an aluminum heat sink is attached to a conventional drive signal generating unit that uses a copper substrate, corrosion is likely to occur at the interface between the copper substrate and the aluminum heat sink. Therefore, when an aluminum heat sink is attached to a conventional drive signal generating unit that uses a copper substrate, a heat dissipation sheet is typically interposed between the copper substrate and the aluminum heat sink to prevent corrosion at the interface between the copper substrate and the aluminum heat sink. Therefore, conventional drive signal generating units that use a copper substrate can have problems such as an increase in size, cost, and number of components.

[0092] In contrast, the drive signal generation unit 5 according to this embodiment employs an aluminum substrate as the transistor substrate 501, in which the base material 75 is made of aluminum. Therefore, in the drive signal generation unit 5 according to this embodiment, corrosion at the interface between the aluminum base material 75 and the aluminum heat sink HS1 is not an issue. Therefore, in the drive signal generation unit 5 according to this embodiment, it is not necessary to interpose a heat dissipation sheet between the transistor substrate 501 and the heat sink HS1; it is sufficient to interpose grease 64 between the transistor substrate 501 and the heat sink HS1. This allows the drive signal generation unit 5 according to this embodiment to be smaller, less expensive, and with fewer components, compared to conventional drive signal generation units employing copper substrates.

[0093] Incidentally, aluminum, as a base metal ingot, has the second highest production volume after iron, and in terms of the ratio of its reserves to the current demand, it is said to exceed even iron. Also, aluminum is said to be a metal with excellent recyclability compared to copper. On the other hand, the amount of copper resources is limited, and it is expected that by 2050, the situation will arise where the amount of copper used exceeds the existing reserves. In contrast, in the present embodiment, in the drive signal generation unit 5, an aluminum substrate having a base material 75 formed of aluminum is adopted. Therefore, according to the present embodiment, it is possible to reduce the environmental load compared to the mode of adopting a copper substrate for the drive signal generation unit 5, and it is possible to reduce the impact on the future "copper shortage".

[0094] <<A.5. Summary of the Embodiment>> As described above, according to the present embodiment, since an aluminum substrate having an aluminum base material is adopted as the transistor substrate 501 and the analog conversion circuit substrate 502, the weight of the drive signal generation unit 5 can be reduced compared to a drive signal generation unit that adopts a copper substrate as in the prior art. As a result, according to the present embodiment, when the drive signal generation unit 5 is mounted on the carriage 110 and the drive signal generation unit 5 is moved, it is possible to reduce the load on the carriage transport motor 91 that drives the carriage 110. That is, the drive signal generation unit 5 according to the present embodiment can extend the service life of the carriage transport motor 91 and reduce the amount of power consumed in driving the carriage transport motor 91 compared to a drive signal generation unit that adopts a copper substrate as in the prior art.

[0095] Furthermore, the drive signal generation unit 5 according to this embodiment employs an aluminum substrate, in which the base material 75 is made of aluminum, as the transistor substrate 501. Therefore, in the drive signal generation unit 5 according to this embodiment, corrosion at the interface between the base material 75 made of aluminum and the heat sink HS1, also made of aluminum, is not an issue. Therefore, in the drive signal generation unit 5 according to this embodiment, there is no need to interpose a heat dissipation sheet between the transistor substrate 501 and the heat sink HS1. Similarly, in the drive signal generation unit 5 according to this embodiment, there is no need to interpose a heat dissipation sheet between the analog conversion circuit board 502 and the heat sink HS2. Therefore, compared to conventional drive signal generation units employing copper substrates, the drive signal generation unit 5 according to this embodiment can be made smaller, less expensive, and with fewer components.

[0096] Furthermore, in the drive signal generation unit 5 according to this embodiment, the analog conversion circuit board 502 on which the analog conversion circuit 51 is provided is a separate board from the transistor board 501 on which the transistor pairs 52 are provided. Therefore, compared to an embodiment in which the transistor pairs 52 and the analog conversion circuit 51 are provided on the same board, the drive signal generation unit 5 according to this embodiment can prevent heat generated in the transistor pairs 52 from being transmitted to the analog conversion circuit 51, and can prevent the analog conversion circuit 51 from overheating.

[0097] Furthermore, in the drive signal generation unit 5 according to this embodiment, the control board 200 on which the control circuit 21 is provided is a separate board from the transistor board 501 on which the transistor pairs 52 are provided. Therefore, compared to an embodiment in which the transistor pairs 52 and the control circuit 21 are provided on the same board, the drive signal generation unit 5 according to this embodiment can prevent heat generated in the transistor pairs 52 from being transmitted to the control circuit 21, and can prevent the control circuit 21 from overheating.

[0098] Further, in the drive signal generation unit 5 according to the present embodiment, an analog conversion circuit cooling mechanism CL2 for cooling the analog conversion circuit board 502 provided with the analog conversion circuit 51 is provided separately from the transistor cooling mechanism CL1 for cooling the transistor board 501 provided with the transistor pair 52. Therefore, the drive signal generation unit 5 according to the present embodiment can more efficiently cool the analog conversion circuit board 502 as compared with an aspect in which the cooling of the analog conversion circuit board 502 is also performed by the transistor cooling mechanism CL1 that cools the transistor board 501. Thus, the drive signal generation unit 5 according to the present embodiment can effectively suppress heat generation in the analog conversion circuit 51 even when the drive signal Com is a large-amplitude signal and the base current supplied from the analog conversion circuit 51 to the transistor pair 52 is a large current.

[0099] Further, in the drive signal generation unit 5 according to the present embodiment, the transistor board 501 and the analog conversion circuit board 502 are fixed by the board-to-board connector CN1. Therefore, according to the present embodiment, even when the drive signal generation unit 5 is mounted on the carriage 110 and moves inside the inkjet printer 1, the relative positional displacement and the relative positional displacement between the transistor board 501 and the analog conversion circuit board 502 can be suppressed as compared with an aspect in which the transistor board 501 and the analog conversion circuit board 502 are connected by, for example, a flexible printed board or the like. Thus, according to the present embodiment, the transistor board 501 and the analog conversion circuit board 502 can be stably connected. Similarly, according to the present embodiment, the analog conversion circuit board 502 and the control board 200 can be stably connected.

[0100] <<B. Modified Example>> Each of the above embodiments can be variously modified. Specific modification modes are exemplified below. Two or more modes arbitrarily selected from the following examples can be appropriately combined within a range that does not conflict with each other. In the modification examples exemplified below, for elements whose actions and functions are equivalent to those of the embodiments, the reference numerals referred to in the above description are used, and the detailed description of each is appropriately omitted.

[0101] <<B.1. Modification Example 1>> In the above-described embodiment, the case where the analog conversion circuit board 502 is an aluminum board formed of aluminum as the base material has been exemplified and described, but the present invention is not limited to such a mode. The analog conversion circuit board 502 may be a copper board formed of copper as the base material. The analog conversion circuit board 502 may be a metal board formed of metal as the base material.

[0102] Also, in the above-described embodiment, the case where the heat sink HS2 is formed of aluminum has been exemplified and described, but the present invention is not limited to such a mode. The heat sink HS2 may be formed of copper. By adopting a copper board as the analog conversion circuit board 502 and forming the heat sink HS2 of copper, the occurrence of corrosion between the heat sink HS2 and the analog conversion circuit board 502 may be suppressed.

[0103] <<B.2. Modification Example 2>> In the above-described embodiment and Modification Example 1, the case where the transistor board 501 is an aluminum board formed of aluminum as the base material 75 has been exemplified and described, but the present invention is not limited to such a mode. The transistor board 501 may be a copper board formed of copper as the base material 75. The transistor board 501 may be a metal board formed of metal as the base material.

[0104] Also, in the above-described embodiment, the case where the heat sink HS1 is formed of aluminum has been exemplified and described. However, the present invention is not limited to such a mode. The heat sink HS1 may be formed of copper. Note that, by adopting a copper substrate as the transistor substrate 501 and forming the heat sink HS1 of copper, the occurrence of corrosion between the heat sink HS1 and the base material 75 may be suppressed.

[0105] <<B.3. Modified Example 3>> In the above-described embodiment and modified examples 1 and 2, in the drive signal generation circuit 50, the mode in which one transistor pair 52 is provided corresponding to one analog conversion circuit 51 has been exemplified and described. However, the present invention is not limited to such a mode. A plurality of transistor pairs 52 may be provided corresponding to one analog conversion circuit 51.

[0106] FIG. 12 is a block diagram showing an example of the circuit configuration of the drive signal generation circuit 50B according to this modified example. The inkjet printer according to this modified example is configured in the same manner as the inkjet printer 1 according to the embodiment, except that it includes a drive signal generation circuit 50B instead of the drive signal generation circuit 50.

[0107] As shown in FIG. 12 , the drive signal generation circuit 50B differs from the drive signal generation circuit 50 according to the embodiment in that it includes an analog conversion circuit 51B instead of the analog conversion circuit 51, multiple transistor pairs 52[1] to 52[K] instead of the transistor pair 52, and multiple electrolytic capacitors CC[1] to CC[K] instead of the electrolytic capacitor CC. Here, the value K is a natural number satisfying "K≧1." Note that, hereinafter, the kth transistor pair 52 among the K transistor pairs 52 provided in the drive signal generation circuit 50B may be referred to as transistor pair 52[k]. Also, hereinafter, the kth electrolytic capacitor CC among the K electrolytic capacitors CC provided in the drive signal generation circuit 50B may be referred to as electrolytic capacitor CC[k]. Here, the variable k is a natural number satisfying "1≦k≦K." Note that, hereinafter, a case where the value K is "2" will be described as an example, as shown in FIG. 12 .

[0108] The analog conversion circuit 51B outputs a waveform specification signal QB[k] including a base supply signal QB1[k] and a base supply signal QB2[k] based on the digital waveform specification signal dCom[k]. The analog conversion circuit 51B then outputs the base supply signal QB1[k] from the output terminal Tn1[k] and outputs the base supply signal QB2[k] from the output terminal Tn2[k]. In this modified example, it is assumed that the waveform designation signals dCom[1] and dCom[2] are signals that designate different waveforms, but the present invention is not limited to this. The waveform designation signals dCom[1] and dCom[2] may be signals that designate the same waveform. In this modification, it is assumed that the analog conversion circuit 51B generates waveform designation signals QB[1] to QB[K] based on waveform designation signals dCom[1] to dCom[K], but the present invention is not limited to this. The analog conversion circuit 51B may also generate waveform designation signals QB[1] to QB[K] having substantially the same waveforms based on a single waveform designation signal dCom.

[0109] The transistor pair 52[k] includes an NPN bipolar transistor Tr1[k] and a PNP bipolar transistor Tr2[k], and generates a drive signal Com[k] based on a base supply signal QB1[k] and a base supply signal QB2[k].

[0110] The bipolar transistor Tr1[k] has a base electrode (B) electrically connected to the output terminal Tn1[k], and a base supply signal QB1[k] is supplied from the output terminal Tn1[k]. The bipolar transistor Tr1[k] also has a collector electrode (C) electrically connected to a power supply line LH set to a power supply potential VHV, and an emitter electrode (E) electrically connected to a wiring LC[k] for supplying a drive signal Com[k].

[0111] The bipolar transistor Tr2[k] has a base electrode (B) electrically connected to the output terminal Tn2[k], and a base supply signal QB2[k] is supplied from the output terminal Tn2[k]. The bipolar transistor Tr2[k] also has a collector electrode (C) electrically connected to ground, and an emitter electrode (E) electrically connected to a wiring LC[k] for supplying a drive signal Com[k].

[0112] The electrolytic capacitor CC[k] is a capacitor for supplying current to the transistor pair 52[k]. Specifically, the electrolytic capacitor CC[k] has two electrodes, one of which is electrically connected to the power supply line LH and the collector electrode of the bipolar transistor Tr1[k], and the other electrode of which is electrically connected to ground.

[0113] As described above, according to this modification example, a single analog conversion circuit 51B can drive a plurality of transistor pairs 52[k]. Also, in this modification example, the analog conversion circuit 51B is cooled by the analog conversion circuit cooling mechanism CL2. Therefore, in this modification example, even when the amount of base current supplied from the analog conversion circuit 51B to the plurality of transistor pairs 52[k] increases, the temperature rise of the analog conversion circuit 51B can be suppressed.

[0114] <<B.4. Modification Example 4>> In the above-described embodiments and modification examples 1 to 3, an example was illustrated and described in which the fan FN1 maintains its operating state regardless of the temperature of the transistor pair 52 provided on the transistor substrate 501, and the fan FN2 maintains its operating state regardless of the temperature of the analog conversion circuit 51 provided on the analog conversion circuit substrate 502. However, the present invention is not limited to such a mode. The fan FN1 may be driven based on the temperature of the transistor pair 52 provided on the transistor substrate 501. Also, the fan FN2 may be driven based on the temperature of the analog conversion circuit 51 provided on the analog conversion circuit substrate 502.

[0115] FIG. 13 is a functional block diagram showing an example of the configuration of the inkjet printer 1C according to this modification example.

[0116] As shown in FIG. 13, the inkjet printer 1C is configured in the same manner as the inkjet printer 1 according to the embodiment, except that it includes a control unit 2C instead of the control unit 2 and a drive signal generation unit 5C instead of the drive signal generation unit 5. In this modification example, the configuration including the control unit 2C and the drive signal generation unit 5C is referred to as a drive control unit 8C. In this modification example, the drive control unit 8C is an example of a "drive device".

[0117] The drive signal generation unit 5C differs from the drive signal generation unit 5 according to the embodiment in that it includes a temperature sensor TS1 and a temperature sensor TS2. The temperature sensor TS1 includes, for example, a thermistor provided on the transistor substrate 501, and outputs temperature information DT1 indicating a temperature TT1 based on the temperature of the transistor pair 52. The temperature sensor TS2 includes, for example, a thermistor provided on the analog conversion circuit substrate 502, and outputs temperature information DT2 indicating a temperature TT2 based on the temperature of the analog conversion circuit 51.

[0118] The control unit 2C differs from the control unit 2 according to the embodiment in that it includes a control circuit 21C instead of the control circuit 21.

[0119] The control circuit 21C generates a fan control signal SF1 that instructs the fan FN1 to operate or stop based on the temperature TT1 indicated by the temperature information DT1. This causes the control circuit 21C to operate the fan FN1 based on the temperature TT1. More specifically, in this modification, the control circuit 21C generates a fan control signal SF1 that instructs the fan FN1 to operate when the temperature TT1 is equal to or greater than a predetermined temperature, and generates a fan control signal SF1 that instructs the fan FN1 to stop when the temperature TT1 is less than the predetermined temperature. However, the present invention is not limited to this configuration. For example, the control circuit 21C may generate a fan control signal SF1 that instructs the fan FN1 to operate when the value obtained by subtracting the ambient temperature of the inkjet printer 1C from the temperature TT1 is equal to or greater than a predetermined threshold, and generate a fan control signal SF1 that instructs the fan FN1 to stop when the value obtained by subtracting the ambient temperature of the inkjet printer 1C from the temperature TT1 is less than the predetermined threshold. In this case, the inkjet printer 1C may be equipped with a temperature sensor (not shown) that measures the ambient temperature of the inkjet printer 1C.

[0120] The control circuit 21C generates a fan control signal SF2 that specifies driving or stopping of the fan FN2 based on the temperature TT2 indicated by the temperature information DT2. Thereby, the control circuit 21C operates the fan FN2 based on the temperature TT2. More specifically, in this modification, the control circuit 21C generates a fan control signal SF2 that specifies operating the fan FN2 when the temperature TT2 is equal to or higher than a predetermined temperature, and generates a fan control signal SF2 that specifies stopping the fan FN2 when the temperature TT2 is lower than the predetermined temperature. However, the present invention is not limited to such a mode. For example, the control circuit 21C may generate a fan control signal SF2 that specifies operating the fan FN2 when a subtraction value obtained by subtracting the ambient temperature of the inkjet printer 1C from the temperature TT2 is equal to or higher than a predetermined threshold value, and generate a fan control signal SF2 that specifies stopping the fan FN2 when the subtraction value obtained by subtracting the ambient temperature of the inkjet printer 1C from the temperature TT2 is lower than the predetermined threshold value. In this case, the inkjet printer 1C may include a temperature sensor (not shown) that measures the ambient temperature of the inkjet printer 1C.

[0121] As described above, according to this modification, the fan FN1 can be operated based on the temperature of the transistor pair 52, and the fan FN2 can be operated based on the temperature of the analog conversion circuit 51. Therefore, it is possible to reduce the power consumption related to the operation of the fans FN1 and FN2 as compared with a mode in which the fans FN1 and FN2 are constantly operating.

[0122] <<B.5. Modification 5>> In the above-described embodiments and Modifications 1 to 4, the case where the transistor substrate 501 and the analog conversion circuit substrate 502 are fixed by the board-to-board connector CN1 has been exemplified and described. However, the present invention is not limited to such an aspect. The transistor substrate 501 and the analog conversion circuit substrate 502 may be fixed by a pin header. Here, a pin header is a connector including an insertion pin member having a plurality of insertion pins formed of metal and a holding portion that holds the plurality of insertion pins in an insulated state from each other, and a pin socket having a plurality of insertion holes provided corresponding to the plurality of insertion pins.

[0123] In this modification, it is assumed that the insertion pin member of the pin header is fixed to the surface PL11 of the transistor substrate 501 and the pin socket of the pin header is fixed to the surface PL22 of the analog conversion circuit substrate 502. The pin header fixes the transistor substrate 501 and the analog conversion circuit substrate 502 by fitting the insertion pin member and the pin socket, and transmits a signal between the transistor substrate 501 and the analog conversion circuit substrate 502.

[0124] <<B.6. Modification 6>> In the above-described embodiments and Modifications 1 to 5, the case where the transistor cooling mechanism CL1 includes the heat sink HS1 and the fan FN1 has been exemplified and described. However, the present invention is not limited to such an aspect. The transistor cooling mechanism CL1 may include a water-cooled cooling device.

[0125] Also, in the above-described embodiments and Modifications 1 to 5, the case where the analog conversion circuit cooling mechanism CL2 includes the heat sink HS2 and the fan FN2 has been exemplified and described. However, the present invention is not limited to such an aspect. The analog conversion circuit cooling mechanism CL2 may include a water-cooled cooling device.

[0126] <<B.7. Modification 7>> In the above-described embodiments and Modifications 1 to 6, the mode in which the control unit 2 is mounted on the carriage 110 as the drive control unit 8 has been described as an example. However, the present invention is not limited to such a mode. The control unit 2 may be provided separately from the drive control unit 8. In this case, the control unit 2 may be provided outside the carriage 110.

[0127] <<B.8. Modification 8>> In the above-described embodiments and Modifications 1 to 7, the case where the drive control unit 8 is mounted on the carriage 110 has been described as an example. However, the present invention is not limited to such a mode. The drive control unit 8 may be provided outside the carriage 110.

[0128] <<B.9. Modification 9>> In the above-described embodiments and Modifications 1 to 8, the case where the inkjet printer 1 is a serial printer has been assumed. However, the present invention is not limited to such a mode. The inkjet printer 1 may be a so-called line printer in which a plurality of nozzles N are provided in the liquid ejection unit 3 so as to extend wider than the width of the recording paper PP.

[0129] <<C. Supplementary Note>> Aspects related to the above description are appended below. For the sake of easy understanding of each aspect, in the following, the reference numerals in the drawings are appended in parentheses for convenience, but it is not intended to limit the present invention to the illustrated aspects.

[0130] <<C.1. Supplementary Note 1>> Hereinafter, the inkjet printer 1 according to Supplementary Note 1 will be described.

[0131] <<Supplementary Note 1-1>> The inkjet printer 1 according to Appendix 1-1 is characterized by comprising: a liquid ejection unit 3 that is driven by a drive signal Com to eject ink; an analog conversion circuit 51 that converts a digital waveform designation signal dCom that designates the waveform of the drive signal Com into an analog waveform designation signal QB that designates the waveform of the drive signal Com; a transistor pair 52 that includes two bipolar transistors Tr that generate the drive signal Com based on the waveform designation signal QB; a transistor cooling mechanism CL1 that cools the transistor pair 52; and an analog conversion circuit cooling mechanism CL2 that cools the analog conversion circuit 51. In addition, in Supplementary Note 1-1, the drive signal Com is an example of a "first drive signal," and the transistor pair 52 is an example of a "first transistor pair."

[0132] According to Supplementary Note 1-1, since the analog conversion circuit cooling mechanism CL2 is provided separately from the transistor cooling mechanism CL1, it is possible to prevent the analog conversion circuit 51 from becoming too hot, compared to an embodiment in which a single cooling mechanism cools both the analog conversion circuit 51 and the transistor pairs 52. Therefore, according to Supplementary Note 1-1, it is possible to prevent the analog conversion circuit 51 from becoming unstable due to an increase in the temperature of the analog conversion circuit 51.

[0133] <<Appendix 1-2>> The inkjet printer 1 according to Supplementary Note 1-2 is the inkjet printer 1 according to Supplementary Note 1-1, characterized in that the output terminal Tn1 of the analog conversion circuit 51 is electrically connected to the base electrode 62B of the bipolar transistor Tr.

[0134] According to Supplementary Note 1-2, even when the drive signal Com is a large-amplitude signal and the base current supplied from the analog conversion circuit 51 to the transistor pair 52 is large, the analog conversion circuit 51 can be prevented from becoming too hot, thereby preventing the analog conversion circuit 51 from becoming unstable in operation due to the analog conversion circuit 51 becoming too hot.

[0135] <<Appendix 1-3>> The inkjet printer 1 according to Appendix 1-3 is the inkjet printer 1 according to Appendix 1-1 or Appendix 1-2, characterized in that the analog conversion circuit cooling mechanism CL2 comprises a heat sink HS2 connected to the analog conversion circuit 51 or an analog conversion circuit board 502 on which the analog conversion circuit 51 is mounted, and a fan FN2 that operates based on the temperature of the analog conversion circuit 51.

[0136] According to Supplementary Note 1-3, the temperature rise of the analog conversion circuit 51 can be suppressed.

[0137] <<Appendix 1-4>> The inkjet printer 1 according to Appendix 1-4 is the inkjet printer 1 according to Appendix 1-1 to Appendix 1-3, characterized in that it comprises a transistor board 501 on which a transistor pair 52 is provided, an analog conversion circuit board 502 on which an analog conversion circuit 51 is provided, a control circuit 21 that generates a waveform specification signal dCom, and a control board 200 on which the control circuit 21 is provided, and the control board 200 is provided separately from the analog conversion circuit board 502.

[0138] According to Supplementary Note 1-4, it is possible to prevent the control board 200 from becoming too hot, compared to an embodiment in which the control board 200 and the analog conversion circuit board 502 are on the same board.

[0139] <<Appendix 1-5>> The inkjet printer 1 according to Supplementary Note 1-5 is the inkjet printer 1 according to Supplementary Note 1-4, characterized in that the analog conversion circuit board 502 and the control board 200 are connected by a board-to-board connector CN2.

[0140] According to Appendix 1-5, even if the analog conversion circuit board 502 and the control board 200 vibrate, such as when the analog conversion circuit board 502 and the control board 200 are mounted on a carriage 110 that moves within the inkjet printer 1, it is possible to maintain a stable connection between the analog conversion circuit board 502 and the control board 200.

[0141] <<Appendix 1-6>> The inkjet printer 1 according to Supplementary Note 1-6 is the inkjet printer 1 according to Supplementary Note 1-4 or Supplementary Note 1-5, characterized in that the analog conversion circuit board 502 is provided separately from the transistor board 501.

[0142] According to Supplementary Note 1-6, compared to an embodiment in which the analog conversion circuit 51 is provided on the same substrate as the transistor pair 52, it is possible to suppress the propagation of heat generated in the transistor pair 52 to the analog conversion circuit 51. Therefore, according to Supplementary Note 1-6, it is possible to suppress the analog conversion circuit 51 from becoming too hot and to suppress instability in the operation of the analog conversion circuit 51.

[0143] <<Appendix 1-7>> The inkjet printer 1 according to Supplementary Note 1-7 is the inkjet printer 1 according to Supplementary Note 1-4 to Supplementary Note 1-6, characterized in that the transistor board 501 and the analog conversion circuit board 502 are connected by a board-to-board connector CN1.

[0144] According to Appendix 1-7, even if the transistor substrate 501 and the analog conversion circuit board 502 vibrate, such as when the transistor substrate 501 and the analog conversion circuit board 502 are mounted on a carriage 110 that moves within the inkjet printer 1, it is possible to maintain a stable connection between the transistor substrate 501 and the analog conversion circuit board 502.

[0145] <<Appendix 1-8>> The inkjet printer 1 according to Supplementary Note 1-8 is the inkjet printer 1 according to Supplementary Note 1-4 to Supplementary Note 1-6, characterized in that the transistor board 501 and the analog conversion circuit board 502 are connected by a pin header.

[0146] According to Appendix 1-8, even if the transistor substrate 501 and the analog conversion circuit board 502 vibrate, such as when the transistor substrate 501 and the analog conversion circuit board 502 are mounted on a carriage 110 that moves within the inkjet printer 1, it is possible to maintain a stable connection between the transistor substrate 501 and the analog conversion circuit board 502.

[0147] <<Appendix 1-9>> The inkjet printer 1 according to Supplementary Note 1-9 is the inkjet printer 1 according to Supplementary Note 1-1 to Supplementary Note 1-8, characterized in that it comprises a transistor substrate 501 on which a transistor pair 52 is provided, and the bipolar transistor Tr is provided on the transistor substrate 501 so that the surface 600 having the largest area among the multiple surfaces of the bipolar transistor Tr is connected to the transistor substrate 501.

[0148] According to Supplementary Note 1-9, the surface 600 having the largest area among the multiple surfaces of the bipolar transistor Tr is connected to the transistor substrate 501, and therefore, compared to, for example, an embodiment in which the surface having the smallest area among the multiple surfaces of the bipolar transistor Tr is connected to the transistor substrate 501, or an embodiment in which the multiple surfaces of the bipolar transistor Tr are not connected to the transistor substrate 501, it is possible to efficiently dissipate heat generated in the bipolar transistor Tr.

[0149] <<Appendix 1-10>> The inkjet printer 1 according to Supplementary Note 1-10 includes a liquid ejection unit 3 that is driven by a drive signal Com[1] and a drive signal Com[2] to eject ink, and an analog conversion circuit that converts a digital waveform designation signal dCom[1] that designates the waveform of the drive signal Com[1] into an analog waveform designation signal QB[1] that designates the waveform of the drive signal Com[1], and converts a digital waveform designation signal dCom[2] that designates the waveform of the drive signal Com[2] into an analog waveform designation signal QB[2] that designates the waveform of the drive signal Com[2]. The analog conversion circuit 51B is characterized by comprising: a transistor pair 52[1] including two bipolar transistors Tr that generate a drive signal Com[1] based on a waveform specification signal QB[1]; a transistor pair 52[2] including two bipolar transistors Tr that generate a drive signal Com[2] based on a waveform specification signal QB[2]; a transistor cooling mechanism CL1 that cools the transistor pair 52[1] and the transistor pair 52[2]; and an analog conversion circuit cooling mechanism CL2 that cools the analog conversion circuit 51B. In addition, in Supplementary Note 1-10, drive signal Com[1] is an example of a "first drive signal," drive signal Com[2] is an example of a "second drive signal," transistor pair 52[1] is an example of a "first transistor pair," transistor pair 52[2] is an example of a "second transistor pair," waveform designation signal dCom[1] is an example of a "first waveform signal," waveform designation signal QB[1] is an example of a "second waveform signal," waveform designation signal dCom[2] is an example of a "third waveform signal," and waveform designation signal QB[2] is an example of a "fourth waveform signal."

[0150] According to Supplementary Note 1-10, even if the base current supplied from the analog conversion circuit 51B to the transistor pair 52[1] and the transistor pair 52[2] becomes large, the analog conversion circuit 51B can be prevented from becoming too hot, thereby preventing the analog conversion circuit 51B from becoming unstable in operation due to the analog conversion circuit 51B becoming too hot.

[0151] In addition, in Supplementary Notes 1-10, the waveform designation signal dCom[1] and the waveform designation signal dCom[2] may be the same signal (waveform designation signal dCom).

[0152] <<Supplementary Note 1-11>> The inkjet printer 1 according to Supplementary Note 1-11 is the inkjet printer 1 according to Supplementary Notes 1-1 to 1-10. The transistor cooling mechanism CL1 is connected to the transistor substrate 501 on which the transistor pair 52 is mounted, and includes a heat sink HS1 formed of aluminum. The analog conversion circuit cooling mechanism CL2 is connected to the analog conversion circuit 51 or the analog conversion circuit substrate 502 on which the analog conversion circuit 51 is mounted, and includes a heat sink HS2 formed of copper.

[0153] According to Supplementary Note 1-11, it is possible to suppress the temperature rise of the analog conversion circuit 51 and suppress the instability of the operation of the analog conversion circuit 51.

[0154] <<Supplementary Note 1-12>> The inkjet printer 1 according to Supplementary Note 1-12 is the inkjet printer 1 according to Supplementary Notes 1-1 to 1-11. The transistor cooling mechanism CL1 is characterized by including a water-cooled cooling device.

[0155] According to Supplementary Note 1-12, it is possible to suppress the temperature rise of the transistor pair 52.

[0156] <<C.2. Supplementary Note 2>> Hereinafter, the inkjet printer 1 according to Supplementary Note 2 will be described.

[0157] <<Supplementary Note 2-1>> The inkjet printer 1 according to Appendix 2-1 comprises a liquid ejection unit 3 that is driven by a drive signal Com to eject ink, a transistor substrate 501, a transistor pair 52 provided on the transistor substrate 501 and including two bipolar transistors Tr that generate the drive signal Com, an analog conversion circuit board 502, and an analog conversion circuit 51 provided on the analog conversion circuit board 502 that converts a digital waveform designation signal dCom that designates the waveform of the drive signal Com into an analog waveform designation signal QB that designates the waveform of the drive signal Com, the transistor pair 52 generating the drive signal Com based on the waveform designation signal QB, and the analog conversion circuit board 502 being provided separately from the transistor substrate 501.

[0158] According to Supplementary Note 2-1, the transistor substrate 501 on which the transistor pairs 52 are provided and the analog conversion circuit substrate 502 on which the analog conversion circuit 51 is provided are provided separately, which makes it possible to prevent heat generated in the transistor pairs 52 from being propagated to the analog conversion circuit 51, compared to an embodiment in which the analog conversion circuit 51 is provided on the same substrate as the transistor pairs 52. Therefore, according to Supplementary Note 2-1, it is possible to prevent the analog conversion circuit 51 from becoming too hot when the drive signal Com is generated, and to prevent the operation of the analog conversion circuit 51 from becoming unstable due to the analog conversion circuit 51 becoming too hot.

[0159] <<Appendix 2-2>> The inkjet printer 1 according to Supplementary Note 2-2 is the inkjet printer 1 according to Supplementary Note 2-1, characterized in that it includes a transistor cooling mechanism CL1 that cools the transistor pairs 52.

[0160] According to Supplementary Note 2-2, the temperature rise of the transistor pair 52 can be suppressed, and therefore the temperature rise of the analog conversion circuit 51 caused by the heat generated in the transistor pair 52 being propagated to the analog conversion circuit 51 can also be suppressed.

[0161] <<Appendix 2-3>> The inkjet printer 1 according to Appendix 2-3 is the inkjet printer 1 according to Appendix 2-1 or Appendix 2-2, characterized in that the transistor substrate 501 has a surface PL11 and a surface PL12 opposite to surface PL11, electronic components including transistor pairs 52 are arranged on surface PL11, and a transistor cooling mechanism CL1 is arranged on surface PL12. In addition, in Supplementary Note 2-3, the surface PL11 is an example of the "first surface," and the surface PL12 is an example of the "second surface."

[0162] According to Supplementary Note 2-3, the temperature rise of the transistor pair 52 can be suppressed, and therefore the temperature rise of the analog conversion circuit 51 caused by the heat generated in the transistor pair 52 being propagated to the analog conversion circuit 51 can also be suppressed.

[0163] <<Appendix 2-4>> The inkjet printer 1 according to Appendix 2-4 is the inkjet printer 1 according to Appendix 2-2 or Appendix 2-3, characterized in that the transistor cooling mechanism CL1 includes a heat sink HS1 connected to the base material 75 of the transistor substrate 501, and a fan FN1 that operates based on the temperature of the transistor pair 52.

[0164] According to Supplementary Note 2-4, the temperature rise of the transistor pair 52 can be suppressed, and therefore the temperature rise of the analog conversion circuit 51 caused by the heat generated in the transistor pair 52 being propagated to the analog conversion circuit 51 can also be suppressed.

[0165] <<Appendix 2-5>> The inkjet printer 1 according to Supplementary Note 2-5 is the inkjet printer 1 according to Supplementary Note 2-1 to Supplementary Note 2-3, characterized in that the analog conversion circuit board 502 is provided with an electrolytic capacitor CC that supplies current to the transistor pair 52.

[0166] According to Supplementary Note 2-5, it is possible to suppress the heat generated in the transistor pair 52 from propagating to the electrolytic capacitor CC, compared to an embodiment in which the electrolytic capacitor CC is provided on the same substrate as the transistor pair 52. Therefore, according to Supplementary Note 2-5, it is possible to suppress the deterioration of the electrolytic capacitor CC due to heat, and to achieve a longer life for the electrolytic capacitor CC, compared to an embodiment in which the electrolytic capacitor CC is provided on the same substrate as the transistor pair 52.

[0167] <<Appendix 2-6>> The inkjet printer 1 according to Supplementary Note 2-6 is the inkjet printer 1 according to Supplementary Note 2-1 to Supplementary Note 2-5, characterized in that the transistor board 501 and the analog conversion circuit board 502 are connected by a board-to-board connector CN1.

[0168] According to Appendix 2-6, even if the transistor substrate 501 and the analog conversion circuit board 502 vibrate, such as when the transistor substrate 501 and the analog conversion circuit board 502 are mounted on a carriage 110 that moves within the inkjet printer 1, it is possible to maintain a stable connection between the transistor substrate 501 and the analog conversion circuit board 502.

[0169] <<Appendix 2-7>> The inkjet printer 1 according to Supplementary Note 2-7 is the inkjet printer 1 according to Supplementary Note 2-1 to Supplementary Note 2-5, characterized in that the transistor board 501 and the analog conversion circuit board 502 are connected by a pin header.

[0170] According to Appendix 2-7, even if the transistor substrate 501 and the analog conversion circuit board 502 vibrate, such as when the transistor substrate 501 and the analog conversion circuit board 502 are mounted on a carriage 110 that moves within the inkjet printer 1, it is possible to maintain a stable connection between the transistor substrate 501 and the analog conversion circuit board 502.

[0171] <<Appendix 2-8>> The inkjet printer 1 according to Appendix 2-8 is the inkjet printer 1 according to Appendix 2-1 to Appendix 2-7, characterized in that it has a connector (board-to-board connector CN1 or pin header) that connects the transistor substrate 501 and the analog conversion circuit board 502, and the connector is arranged in the central region AM of the transistor substrate 501. In addition, in Supplementary Note 2-8, the central area AM is an example of the "central part."

[0172] According to Appendix 2-8, even if the transistor substrate 501 and the analog conversion circuit board 502 vibrate, such as when the transistor substrate 501 and the analog conversion circuit board 502 are mounted on a carriage 110 that moves within the inkjet printer 1, it is possible to maintain a stable connection between the transistor substrate 501 and the analog conversion circuit board 502.

[0173] <<Appendix 2-9>> The inkjet printer 1 according to Appendix 2-9 is the inkjet printer 1 according to Appendix 2-1 to Appendix 2-8, characterized in that the transistor substrate 501 has long sides LY1 and LY2 facing each other and short sides LX1 and LX2 facing each other, a plurality of transistor pairs 52 are provided on the transistor substrate 501, and a plurality of bipolar transistors Tr of the plurality of transistor pairs 52 are arranged so as to be aligned along the long sides LY1 and LY2.

[0174] According to Supplementary Note 2-9, heat generated in the plurality of bipolar transistors Tr can be efficiently dissipated from the long sides LY1 and LY2.

[0175] <<Appendix 2-10>> The inkjet printer 1 according to Supplementary Note 2-10 is the inkjet printer 1 according to Supplementary Notes 2-1 to 2-9, and is characterized in that the bipolar transistor Tr is provided on the transistor substrate 501 such that the surface 600 having the largest area among the plurality of surfaces of the bipolar transistor Tr is connected to the transistor substrate 501.

[0176] According to Supplementary Note 2-10, since the surface 600 having the largest area among the plurality of surfaces of the bipolar transistor Tr is connected to the transistor substrate 501, for example, compared with a mode in which the surface having the smallest area among the plurality of surfaces of the bipolar transistor Tr is connected to the transistor substrate 501, or a mode in which the plurality of surfaces of the bipolar transistor Tr are not connected to the transistor substrate 501, heat generated in the bipolar transistor Tr can be efficiently dissipated.

[0177] <<Supplementary Note 2-11>> The inkjet printer 1 according to Supplementary Note 2-11 is the inkjet printer 1 according to Supplementary Notes 2-1 to 2-10, and the transistor substrate 501 has a surface PL11 and a surface PL12 opposite to the surface PL11. The bipolar transistor Tr is disposed on the surface PL11, and a transistor cooling mechanism CL1 for cooling the bipolar transistor Tr is disposed on the surface PL12. The bipolar transistor Tr is fixed to the transistor cooling mechanism CL1 by a screw 65 penetrating the transistor substrate 501.

[0178] According to Supplementary Note 2-11, heat generated from the bipolar transistor Tr can be dissipated to the transistor cooling mechanism CL1 via the screw 65, so that the temperature rise of the bipolar transistor Tr can be suppressed.

[0179] <<C.3. Supplementary Note 3>> Hereinafter, the inkjet printer 1 according to Supplementary Note 3 will be described.

[0180] <<Appendix 3-1>> The inkjet printer 1 according to Appendix 3-1 is characterized by comprising a liquid ejection unit 3 that is driven by a drive signal Com to eject ink, a metal transistor substrate 501, and a transistor pair 52 that is provided on the transistor substrate 501 and includes two bipolar transistors Tr that generate the drive signal Com.

[0181] According to Supplementary Note 3-1, since the transistor pair 52 is provided on the metal transistor substrate 501, it is possible to more efficiently dissipate heat generated in the transistor pair 52 than in an embodiment in which the transistor pair 52 is provided on a resin substrate, for example. Therefore, according to Supplementary Note 3-1, it is possible to prevent the temperature of the transistor pair 52 from rising too high.

[0182] <<Appendix 3-2>> The inkjet printer 1 according to Appendix 3-2 is the inkjet printer 1 according to Appendix 3-1, characterized in that it includes a carriage 110 that moves the liquid ejection unit 3, and the transistor substrate 501 has a base material 75 made of aluminum and is mounted on the carriage 110.

[0183] According to Supplementary Note 3-2, because an aluminum substrate having an aluminum base material is used as the transistor substrate 501, it is possible to reduce the weight of the transistor substrate 501 compared to, for example, an embodiment in which a substrate having a copper base material is used as the transistor substrate 501. Therefore, according to Supplementary Note 3-2, it is possible to reduce the load on the carriage transport motor 91 that moves the carriage 110 on which the transistor substrate 501 is mounted, thereby extending the life of the carriage transport motor 91 and reducing the amount of power required to drive the carriage transport motor 91.

[0184] <<Appendix 3-3>> The inkjet printer 1 according to Supplementary Note 3-3 is the inkjet printer 1 according to Supplementary Note 3-2, characterized in that it includes a heat sink HS1 that is connected to the base material 75 of the transistor substrate 501 and is made of aluminum.

[0185] According to Supplementary Note 3-3, heat generated by the transistor pair 52 can be dissipated from the heat sink HS1, so that the temperature of the transistor pair 52 can be prevented from rising.

[0186] Furthermore, according to Supplementary Note 3-3, because the heat sink HS1 is made of aluminum, the weight of the heat sink HS1 can be reduced compared to when the heat sink HS1 is made of copper, for example. Therefore, according to Supplementary Note 3-3, it is possible to extend the life of the carriage transport motor 91 and reduce the amount of power required to drive the carriage transport motor 91.

[0187] Furthermore, according to Supplementary Note 3-3, because an aluminum heat sink HS1 is connected to the transistor substrate 501 having an aluminum base material 75, the possibility of corrosion occurring at the interface between the transistor substrate 501 and the heat sink HS1 can be reduced compared to, for example, an embodiment in which a substrate having a copper base material is used as the transistor substrate 501 and an aluminum heat sink HS1 is connected to the transistor substrate 501. Therefore, according to Supplementary Note 3-3, it is not necessary to interpose a heat dissipation sheet between the transistor substrate 501 and the heat sink HS1; it is sufficient to simply interpose grease 64 between the transistor substrate 501 and the heat sink HS1. As a result, according to Supplementary Note 3-3, it is possible to reduce the size of the drive signal generation unit 5 including the transistor substrate 501 and the heat sink HS1, reduce the cost of the drive signal generation unit 5, and reduce the number of parts of the drive signal generation unit 5, compared to an embodiment in which a substrate having a copper base material is used as the transistor substrate 501.

[0188] <<Appendix 3-4>> The inkjet printer 1 according to Supplementary Note 3-4 is the inkjet printer 1 according to Supplementary Note 3-1 to Supplementary Note 3-3, characterized in that it includes a fan FN1 that operates based on the temperature of the transistor pair 52.

[0189] According to Supplementary Note 3-4, heat generated by the transistor pair 52 can be dissipated by the fan FN1, so that the temperature of the transistor pair 52 can be prevented from rising.

[0190] <<Appendix 3-5>> The inkjet printer 1 according to Appendix 3-5 is the inkjet printer 1 according to Appendix 3-1 to Appendix 3-4, and is characterized in that it comprises an analog conversion circuit board 502, and an analog conversion circuit 51 provided on the analog conversion circuit board 502 and converting a digital waveform designation signal dCom that designates the waveform of the drive signal Com into an analog waveform designation signal QB that designates the waveform of the drive signal Com, the transistor pair 52 generating the drive signal Com based on the waveform designation signal QB, and the analog conversion circuit board 502 being provided separately from the transistor board 501.

[0191] According to Supplementary Note 3-5, since the analog conversion circuit substrate 502 is provided separately from the transistor substrate 501, it is possible to suppress propagation of heat generated in the transistor pairs 52 to the analog conversion circuit 51, compared to an embodiment in which the analog conversion circuit 51 is provided on the same substrate as the transistor pairs 52. Therefore, according to Supplementary Note 3-5, it is possible to suppress an increase in temperature of the analog conversion circuit 51 and to suppress instability in the operation of the analog conversion circuit 51.

[0192] <<Appendix 3-6>> The inkjet printer 1 according to Appendix 3-6 is the inkjet printer 1 according to Appendix 3-5, characterized in that it is equipped with a transistor cooling mechanism CL1 that cools the transistor pair 52 and an analog conversion circuit cooling mechanism CL2 that cools the analog conversion circuit 51.

[0193] According to Supplementary Note 3-6, since the analog conversion circuit cooling mechanism CL2 is provided separately from the transistor cooling mechanism CL1, it is possible to prevent the analog conversion circuit 51 from becoming too hot, compared to a configuration in which a single cooling mechanism cools both the analog conversion circuit 51 and the transistor pairs 52. Therefore, according to Supplementary Note 3-6, it is possible to prevent the analog conversion circuit 51 from becoming unstable due to an increase in the temperature of the analog conversion circuit 51.

[0194] <<Appendix 3-7>> The inkjet printer 1 according to Supplementary Note 3-7 is the inkjet printer 1 according to Supplementary Note 3-1, characterized in that the transistor substrate 501 includes a base material 75 formed from copper.

[0195] According to Supplementary Note 3-7, since the transistor pair 52 is provided on the transistor substrate 501 having a copper base material, it is possible to more effectively dissipate heat generated in the transistor pair 52 than, for example, in an embodiment in which the transistor pair 52 is provided on a resin substrate.

[0196] <<Appendix 3-8>> The inkjet printer 1 according to Appendix 3-8 is the inkjet printer 1 according to Appendix 3-1 to Appendix 3-7, characterized in that the bipolar transistor Tr is provided on the transistor substrate 501 so that the surface 600 having the largest area among the multiple surfaces of the bipolar transistor Tr is connected to the transistor substrate 501.

[0197] According to Supplementary Note 3-8, the surface 600 having the largest area among the multiple surfaces of the bipolar transistor Tr is connected to the transistor substrate 501, and therefore, compared to, for example, an embodiment in which the surface having the smallest area among the multiple surfaces of the bipolar transistor Tr is connected to the transistor substrate 501, or an embodiment in which the multiple surfaces of the bipolar transistor Tr are not connected to the transistor substrate 501, it is possible to efficiently dissipate heat generated in the bipolar transistor Tr. [Explanation of symbols]

[0198] 1...inkjet printer, 2...control unit, 3...liquid ejection unit, 5...drive signal generation unit, 9...transport unit, 21...control circuit, 22...memory circuit, 31...supply circuit, 32...head portion, 50...drive signal generation circuit, 51...analog conversion circuit, 52...transistor pair, 61...chip main body portion, 64...grease, 65...screw, 71...wiring layer, 72...insulating layer, 73...wiring layer, 74...insulating layer, 75...substrate, 91...carriage transport motor, 92...media transport motor, 200...control board, 501...transistor board, 502...analog conversion circuit board, CC...electrolytic capacitor, CL1...transistor cooling mechanism, CL2...analog conversion circuit cooling mechanism, CN1...board-to-board connector, CN2...board-to-board connector, D...ejection portion, FN1...fan, FN2...fan, HS1...heat sink, HS2...heat sink, Tr1...bipolar transistor, Tr2...bipolar transistor.

Claims

1. a liquid ejection head that is driven by a drive signal to eject liquid; a first substrate; provided on the first substrate, a transistor pair including two bipolar transistors for generating the drive signal; a second substrate; provided on the second substrate, an analog conversion circuit that converts a digital first waveform signal that specifies the waveform of the drive signal into an analog second waveform signal that specifies the waveform of the drive signal; Equipped with the transistor pair generates the drive signal based on the second waveform signal; The second substrate is provided separately from the first substrate. A liquid ejection device characterized by:

2. a first cooling mechanism for cooling the transistor pair; The liquid ejection device according to claim 1 .

3. the first substrate has a first surface and a second surface opposite the first surface; an electronic component including the transistor pair is disposed on the first surface; The first cooling mechanism is disposed on the second surface.

3. The liquid ejection device according to claim 2, wherein the liquid ejection device comprises: a nozzle;

4. The first cooling mechanism a first heat sink connected to a base of the first substrate; a first fan that operates based on the temperature of the transistor pair; 3. The liquid ejection device according to claim 2, wherein the liquid ejection device comprises: a nozzle;

5. an electrolytic capacitor that supplies current to the transistor pair is provided on the second substrate; The liquid ejection device according to claim 1 .

6. The first substrate and the second substrate are connected by a board-to-board connector. The liquid ejection device according to claim 1 .

7. The first board and the second board are connected by a pin header. The liquid ejection device according to claim 1 .

8. a connector that connects the first substrate and the second substrate; The connector is disposed in a central portion of the first substrate. The liquid ejection device according to claim 1 .

9. the first substrate has two long sides facing each other and two short sides facing each other, a plurality of the transistor pairs are provided on the first substrate; the plurality of bipolar transistors included in the plurality of transistor pairs are arranged side by side along a long side of the first substrate; The liquid ejection device according to claim 1 .

10. the bipolar transistor is provided on the first substrate such that the largest surface of a plurality of surfaces of the bipolar transistor is connected to the first substrate; The liquid ejection device according to claim 1 .

11. the first substrate has a first surface and a second surface opposite the first surface; the bipolar transistor is disposed on the first surface; a first cooling mechanism for cooling the bipolar transistor is disposed on the second surface; the bipolar transistor is fixed to the first cooling mechanism by a screw that penetrates the first substrate; The liquid ejection device according to claim 1 .

12. A driving device that supplies a driving signal to a liquid ejection head that is driven by the driving signal to eject liquid, a first substrate; provided on the first substrate, a transistor pair including two bipolar transistors for generating the drive signal; a second substrate; provided on the second substrate, an analog conversion circuit that converts a digital first waveform signal that specifies the waveform of the drive signal into an analog second waveform signal that specifies the waveform of the drive signal; Equipped with the transistor pair generates the drive signal based on the second waveform signal; The second substrate is provided separately from the first substrate. A drive device characterized by:

13. a first cooling mechanism for cooling the transistor pair; 13. The drive device according to claim 12, characterized in that

14. the first substrate has a first surface and a second surface opposite the first surface; an electronic component including the transistor pair is disposed on the first surface; The first cooling mechanism is disposed on the second surface.

14. The drive device according to claim 13, characterized in that

15. The first cooling mechanism a first heat sink connected to a base of the first substrate; a first fan that operates based on the temperature of the transistor pair; 14. The drive device according to claim 13, characterized in that

16. an electrolytic capacitor that supplies current to the transistor pair is provided on the second substrate; 13. The drive device according to claim 12, characterized in that

17. The first substrate and the second substrate are connected by a board-to-board connector.

13. The drive device according to claim 12, characterized in that

18. The first board and the second board are connected by a pin header.

13. The drive device according to claim 12, characterized in that

19. a connector that connects the first substrate and the second substrate; The connector is disposed in a central portion of the first substrate.

13. The drive device according to claim 12, characterized in that

20. the first substrate has two long sides facing each other and two short sides facing each other, a plurality of the transistor pairs are provided on the first substrate; the plurality of bipolar transistors included in the plurality of transistor pairs are arranged side by side along a long side of the first substrate; 13. The drive device according to claim 12, characterized in that

21. the bipolar transistor is provided on the first substrate such that the largest surface of a plurality of surfaces of the bipolar transistor is connected to the first substrate; 13. The drive device according to claim 12, characterized in that

22. the first substrate has a first surface and a second surface opposite the first surface; the bipolar transistor is disposed on the first surface; a first cooling mechanism for cooling the bipolar transistor is disposed on the second surface; the bipolar transistor is fixed to the first cooling mechanism by a screw that penetrates the first substrate; 13. The drive device according to claim 12, characterized in that

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