JP2019059067A - Liquid ejection device and control method of liquid ejection device - Google Patents

Abstract

An object of the present invention is to reduce the possibility of the drive signal generation circuit becoming a high temperature. A driving signal generation circuit that generates a driving signal using a frame, a first transistor and a second transistor, a first transistor, a second transistor, a thermal conductive sheet in contact with the frame, and driving by the driving signal What is claimed is: 1. A liquid discharge apparatus comprising: a head unit capable of discharging a liquid; and a control circuit for stopping generation of a drive signal by a drive signal generation circuit when a predetermined condition is satisfied. [Selected figure] Figure 14

Description

  The present invention relates to a liquid ejection device and a control method of the liquid ejection device.

  A liquid ejection apparatus such as an inkjet printer drives a head unit to eject liquid such as ink from the head unit to form an image on a recording medium. Such a liquid ejection apparatus is provided with a drive signal generation circuit that generates a drive signal for driving the head unit (see, for example, Patent Document 1).

Unexamined-Japanese-Patent No. 2010-221500

The drive signal for driving the head unit is a signal with a large amplitude, and the drive signal generation circuit generates heat when generating the drive signal. For this reason, when the drive signal generation circuit generates a drive signal, the temperature of the drive signal generation circuit may rise.
Then, the temperature of the drive signal generation circuit rises, and the operation of the drive signal generation circuit becomes inaccurate due to the drive signal generation circuit becoming a high temperature (for example, a temperature higher than the endurance temperature of the drive signal generation circuit). The image quality of the image formed by the liquid discharge device may be degraded.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a technique for reducing the possibility of the drive signal generation circuit becoming high temperature.

  In order to solve the above problems, a liquid discharge apparatus according to the present invention includes a frame, a drive signal generation circuit that generates a drive signal using a first transistor and a second transistor, the first transistor, and the second transistor. A transistor, a thermally conductive sheet in contact with the frame, a head unit driven by the drive signal and capable of discharging a liquid, and generation of the drive signal by the drive signal generation circuit when a predetermined condition is satisfied. And a control circuit for stopping the control unit.

According to this aspect, the heat generated in the drive signal generation circuit including the first transistor and the second transistor can be dissipated to the frame through the heat conduction sheet. Therefore, according to this aspect, for example, the possibility of the drive signal generation circuit becoming high temperature can be reduced as compared with the case where the liquid discharge device does not include the heat conduction sheet.
Further, according to this aspect, when the predetermined condition is satisfied, the control circuit stops the generation of the drive signal in the drive signal generation circuit. Therefore, according to this aspect, for example, even after the predetermined condition is satisfied, the drive signal generation circuit may have a high temperature compared to the case where the generation of the drive signal in the drive signal generation circuit is not stopped. Can be reduced.

  The liquid discharge apparatus described above includes a substrate provided with the drive signal generation circuit, and a thermistor provided on the substrate and detecting a temperature, and the control circuit is configured to detect a temperature detected by the thermistor at a predetermined temperature. In the above case, the generation of the drive signal by the drive signal generation circuit may be stopped.

  According to this aspect, when the temperature detected by the thermistor reaches a predetermined temperature or more, the control circuit stops the generation of the drive signal in the drive signal generation circuit. Therefore, according to this aspect, for example, even after the temperature detected by the thermistor reaches a predetermined temperature or more, the drive signal generation circuit is compared with the case where the generation of the drive signal in the drive signal generation circuit is not stopped. Can reduce the possibility of high temperature.

  In the liquid ejection apparatus described above, the head unit ejects the liquid onto a recording medium to form an image on the recording medium, and the control circuit performs the recording on which the image is formed by the head unit. The number of media may be counted, and the generation of the drive signal by the drive signal generation circuit may be stopped when the counted number of recording media is equal to or more than a predetermined number.

  According to this aspect, when an image is formed on a predetermined number of recording media, the control circuit stops the generation of the drive signal in the drive signal generation circuit. Therefore, according to this aspect, for example, even after formation of an image on a predetermined number or more of recording media, drive signal generation is performed as compared with the case where generation of drive signals in the drive signal generation circuit is not stopped. The possibility of the circuit becoming hot can be reduced.

  In the liquid ejection apparatus described above, the control circuit counts the number of times of ejection of the liquid from the head unit, and the drive signal is generated when the counted number of times of ejection becomes equal to or more than a first reference value. The generation of the drive signal by the circuit may be stopped.

  According to this aspect, when the number of times of liquid ejection from the head unit becomes equal to or more than the first reference value, the control circuit stops the generation of the drive signal in the drive signal generation circuit. Therefore, according to this aspect, for example, even after the number of times of discharge of the liquid from the head unit becomes equal to or more than the first reference value, compared to the case where the generation of the drive signal in the drive signal generation circuit is not stopped. The possibility of the drive signal generation circuit becoming high temperature can be reduced.

  In the liquid ejection apparatus described above, the drive signal generation circuit can supply the drive signal to the head unit every unit period, and the control circuit causes the drive signal generation circuit to transmit the drive signal. The number of unit periods to be supplied is counted, and the generation of the drive signal by the drive signal generation circuit is stopped when the counted number of unit periods becomes equal to or more than a second reference value. It is also good.

  According to this aspect, when the number of times the drive signal is supplied to the head unit becomes equal to or greater than the second reference value, the control circuit stops the generation of the drive signal in the drive signal generation circuit. Therefore, according to this aspect, for example, when generation of the drive signal in the drive signal generation circuit is not stopped even after the number of times the drive signal is supplied to the head unit becomes equal to or more than the second reference value. Compared to the above, the possibility of the drive signal generation circuit becoming high temperature can be reduced.

  In the liquid ejection apparatus described above, the head unit may include 720 or more ejection units, and the ejection unit may be driven by the drive signal to eject the liquid.

  According to this aspect, it is possible to print a high resolution image.

  Further, according to a method of driving a liquid discharge device according to the present invention, a frame, a drive signal generation circuit that generates a drive signal using a first transistor and a second transistor, the first transistor, the second transistor, and A control method for a liquid ejection apparatus, comprising: a heat conduction sheet in contact with the frame; and a head unit driven by the drive signal to eject a liquid, wherein the drive signal is satisfied when a predetermined condition is satisfied. The generation of the drive signal by the generation circuit is stopped.

According to this aspect, the heat generated in the drive signal generation circuit including the first transistor and the second transistor can be dissipated to the frame through the heat conduction sheet. Therefore, according to this aspect, for example, the possibility of the drive signal generation circuit becoming high temperature can be reduced as compared with the case where the liquid discharge device does not include the heat conduction sheet.
Further, according to this aspect, when the predetermined condition is satisfied, the control circuit stops the generation of the drive signal in the drive signal generation circuit. Therefore, according to this aspect, for example, even after the predetermined condition is satisfied, the drive signal generation circuit may have a high temperature compared to the case where the generation of the drive signal in the drive signal generation circuit is not stopped. Can be reduced.

It is a block diagram showing an example of composition of ink jet printer 1 concerning the present invention. FIG. 2 is a perspective view showing an example of a schematic internal structure of the inkjet printer 1; It is an explanatory view for explaining an example of the structure of discharge part D. FIG. 6 is a plan view showing an example of the arrangement of nozzles N in the recording head HD. FIG. 6 is a block diagram showing an example of a configuration of a drive signal generation circuit 5; FIG. 2 is a block diagram showing an example of the configuration of a power supply circuit 9; FIG. 6 is a plan view showing an example of a circuit arrangement on a substrate 200. FIG. 6 is a plan view showing an example of a circuit arrangement on a substrate 200. It is an explanatory view for explaining an example of the physical relationship of substrate 200 and heat conduction sheet SH. It is an explanatory view for explaining an example of the physical relationship of substrate 200 and heat conduction sheet SH. It is a block diagram showing an example of composition of head unit HU. 5 is a timing chart for describing an example of an operation in print processing. It is an explanatory view for explaining an example of connection state designation signal SL [m]. 5 is a flowchart showing an example of the operation of the inkjet printer 1;

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, in each of the drawings, the dimensions and the scale of each part are appropriately different from the actual ones. Further, the embodiment described below is a preferable specific example of the present invention, and therefore, various technically preferable limitations are added, but the scope of the present invention particularly limits the present invention in the following description. As long as there is no statement of purport, it is not limited to these forms.

<< A. Embodiment >>
In the present embodiment, a liquid ejection apparatus will be described by exemplifying an inkjet printer which ejects ink (an example of “liquid”) to form an image on a recording sheet P (an example of “recording medium”).

<< 1. Outline of inkjet printer >>
Hereinafter, the configuration of the ink jet printer 1 according to the present embodiment will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a functional block diagram showing an example of the configuration of the inkjet printer 1. The inkjet printer 1 includes print data Img indicating an image to be formed by the inkjet printer 1 from a host computer (not shown) such as a personal computer or a digital camera, and a number of copies indicating the number of copies of the image to be formed by the inkjet printer 1 Information CP is supplied. The inkjet printer 1 executes a printing process for forming an image indicated by print data Img supplied from a host computer on a recording sheet P.

  As illustrated in FIG. 1, the inkjet printer 1 includes a control module 2, a head unit HU provided with a discharge unit D that discharges ink, and a transport for changing the relative position of the recording paper P with respect to the head unit HU. And a mechanism 7. Among them, the control module 2 includes a control circuit 6 for controlling the operation of each part of the ink jet printer 1, a drive signal generation circuit 5 for generating a drive signal Com for driving the ejection part D, and storage for storing various information. A circuit 4, a power supply circuit 9 for supplying power to each part of the ink jet printer 1, a temperature detection circuit 81, and a notification circuit 82 are provided. In the present embodiment, each component (control circuit 6, drive signal generation circuit 5, storage circuit 4, power supply circuit 9, temperature detection circuit 81, and notification circuit 82) of control module 2 is a substrate, as an example. The case where it forms on 200 (refer FIG. 2) is assumed.

The temperature detection circuit 81 includes a thermistor TM (see FIG. 7) for detecting a temperature, and outputs a detection signal XS indicating a detection result by the thermistor TM.
The notification circuit 82 outputs a notification signal XH indicating whether the temperature indicated by the detection signal XS is equal to or higher than the reference temperature Tth. For example, the notification circuit 82 compares an electric signal such as a current value or a voltage value output from the thermistor TM with an electric signal serving as another reference, and outputs an output according to the magnitude relationship between the values indicated by the two electric signals. It may be changed. For example, as the notification circuit 82, a comparator can be employed.

The head unit HU includes a recording head HD having M discharge units D, and a supply circuit 10 that switches whether to supply the drive signal Com output from the drive signal generation circuit 5 to the recording head HD (see FIG. In the present embodiment, M is a natural number satisfying 8 ≦ M).
Hereinafter, in order to distinguish each of the M discharge sections D provided in the recording head HD, the M discharge sections D may be referred to as one stage, two stages,. Further, the discharge part D of m stages may be referred to as a discharge part D [m] (the variable m is a natural number satisfying 1 ≦ m ≦ M). In addition, when the constituent elements and signals of the ink jet printer 1 correspond to the number m of stages of the discharge section D [m], the code for representing the constituent elements and the signals corresponds to the number m of stages May be expressed with a suffix [m] indicating that
Also, in the following, among the drive signals Com, the drive signal Com supplied to the ejection unit D may be referred to as a supply drive signal Vin. Further, the supply drive signal Vin supplied to the ejection unit D [m] may be referred to as a supply drive signal Vin [m].

  The memory circuit 4 may be, for example, a volatile memory such as a random access memory (RAM), a non-volatile memory such as a read only memory (ROM), an electrically erasable programmable read only memory (EEPROM), or a programmable ROM (PROM). It is configured to include one or both of a memory, and stores various information such as print data Img supplied from a host computer and a control program of the inkjet printer 1.

The control circuit 6 is configured to include a CPU (Central Processing Unit). However, the control circuit 6 may include a programmable logic device such as a field-programmable gate array (FPGA) instead of or in addition to the CPU.
The control circuit 6 controls the operation of each part of the ink jet printer 1 by the CPU provided in the control circuit 6 executing a control program stored in the storage circuit 4 and operating according to the control program. Specifically, the control circuit 6 includes a print signal SI for controlling the supply circuit 10 provided in the head unit HU, a waveform designation signal dCom for controlling the drive signal generation circuit 5, and the transport mechanism 7. A signal for controlling the operation of each part of the ink jet printer 1 such as a signal for control is generated.

Here, the waveform designation signal dCom is a digital signal that designates the waveform of the drive signal Com.
Further, the drive signal Com is an analog signal for driving the ejection unit D. The drive signal generation circuit 5 generates a drive signal Com having a waveform defined by the digital waveform specification signal dCom.
The print signal SI is a digital signal for specifying the type of operation of the discharge unit D. Specifically, the print signal SI designates the type of operation of the discharge unit D by specifying whether to supply the drive signal Com to the discharge unit D. Here, with the designation of the type of operation of the ejection unit D, for example, it is designated whether or not the ejection unit D is to be driven, or is the ink ejected from the ejection unit D when the ejection unit D is driven? It is to specify whether or not the ink is discharged, or to designate the amount of ink discharged from the discharge part D when the discharge part D is driven.

  When the printing process is executed, the control circuit 6 first causes the storage circuit 4 to store the print data Img supplied from the host computer. Next, based on various data such as print data Img stored in the memory circuit 4, the control circuit 6 performs various processes such as a print signal SI, a waveform designation signal dCom, and a signal for controlling the transport mechanism 7. Generate control signals. The control circuit 6 changes the relative position of the recording sheet P to the head unit HU based on various control signals such as the printing signal SI and various data stored in the memory circuit 4. While controlling, the supply circuit 10 is controlled so that the discharge part D is driven. Thereby, the control circuit 6 adjusts the presence or absence of the ink discharge from the discharge unit D, the discharge amount of the ink, the discharge timing of the ink, and the like, and forms the image corresponding to the print data Img on the recording paper P Each part of the ink jet printer 1 is controlled so that the process is performed.

  Note that one or more printing processes executed to form a single image indicated by the print data Img are referred to as printing tasks. In addition, one or more print tasks executed to form an image indicated by the print data Img for the number of copies corresponding to the copy number information CP will be referred to as a print job.

FIG. 2 is a perspective view showing an example of a schematic internal structure of the ink jet printer 1.
As shown in FIG. 2, in the present embodiment, it is assumed that the inkjet printer 1 is a serial printer. Specifically, when performing the printing process, the inkjet printer 1 discharges the recording sheet P in the sub-scanning direction and reciprocates the head unit HU in the main scanning direction intersecting the sub-scanning direction. By discharging the ink from D, dots corresponding to the print data Img are formed on the recording paper P.
In the following, the + X direction and the reverse direction -X direction are generically referred to as "X axis direction", the + Y direction and the reverse direction -Y direction generically as "Y axis direction", and the + Z direction The -Z direction which is the opposite direction is generically referred to as "Z-axis direction". In the present embodiment, as shown in FIG. 2, the direction from the −X side (upstream side) to the + X side (downstream side) is taken as a sub scanning direction, and the Y axis direction is taken as a main scanning direction. In this embodiment, as an example, it is assumed that the X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to each other, but the X-axis direction, the Y-axis direction, and the Z-axis direction The directions may be in directions crossing each other.

  As illustrated in FIG. 2, the inkjet printer 1 according to the present embodiment is provided in a housing 100 at least a part of which is formed of a metal member and inside the housing 100, and is fixed to the housing 100. And a carriage 110 which can reciprocate in the Y-axis direction inside the housing 100 and mounts the head unit HU. In addition, below, the part formed with the metal members of the housing | casing 100, and the metal member fixed to the housing | casing 100 may be generically called "frame FR."

As illustrated in FIG. 2, in the inkjet printer 1 according to the present embodiment, a substrate 200 on which each component of the control module 2 is formed, and a thermally conductive sheet SH provided to be in contact with the substrate 200 and the frame FR. And.
In this embodiment, for convenience of explanation, as shown in FIG. 2, the case where the substrate 200 is provided so that the straight line perpendicular to the substrate 200 and the Y-axis direction are parallel and the substrate 200 is parallel to the XZ plane As an example.
In the present embodiment, it is assumed that the heat conductive sheet SH is a flat sheet-like member having thermal conductivity and stretchability. Moreover, in this embodiment, as shown in FIG. 2, the case where one part or all part of heat conductive sheet SH is provided between the board | substrate 200 and flame | frame FR is assumed as an example. The heat transfer sheet SH is a component for radiating the heat generated in the control module 2 to the frame FR.

Further, as described above, the ink jet printer 1 according to the present embodiment includes the transport mechanism 7.
The transport mechanism 7 changes the relative position of the recording sheet P with respect to the head unit HU by reciprocating the carriage 110 in the Y-axis direction and transporting the recording sheet P in the + X direction when printing processing is performed. To allow the ink to land on the entire recording paper P.
As shown in FIG. 1, the transport mechanism 7 transports the recording paper P by using a transport motor 71 as a driving source for reciprocating the carriage 110, a motor driver 72 for driving the transport motor 71, and the like. A paper feed motor 73 as a driving source and a motor driver 74 for driving the paper feed motor 73 are provided. Further, as shown in FIG. 2, the transport mechanism 7 is stretched between a carriage guide shaft 76 extending in the Y-axis direction, a pulley 711 rotationally driven by the transport motor 71, and a rotatable pulley 712. And a timing belt 710 extending in the Y-axis direction. The carriage 110 is supported by the carriage guide shaft 76 so as to reciprocate in the Y-axis direction, and is fixed to a predetermined position of the timing belt 710 via the fixing tool 120. Therefore, the conveyance mechanism 7 can reciprocate the carriage 110 in the Y-axis direction along the carriage guide shaft 76 together with the head unit HU by rotationally driving the pulley 711 by the conveyance motor 71.

  Further, as shown in FIG. 2, the transport mechanism 7 rotates in response to the driving of the platen 75 provided on the lower side (−Z side) of the carriage 110 and the paper feed motor 73 to record the recording paper P one by one. A paper feed roller (not shown) for feeding onto the platen 75, and a paper discharge roller 730 for rotating in response to the driving of the paper feed motor 73 to convey the recording paper P on the platen 75 to the paper discharge port. Prepare. Therefore, as shown in FIG. 2, the transport mechanism 7 can transport the recording sheet P from the −X side (upstream side) to the + X side (downstream side) on the platen 75.

In the present embodiment, as illustrated in FIG. 2, four ink cartridges 31 are mounted on the carriage 110 of the ink jet printer 1. More specifically, in the present embodiment, as an example, four ink cartridges 31 corresponding to four colors (CMYK) inks of cyan, magenta, yellow, and black in one-to-one correspondence with the carriage 110. Assume that it is installed.
Further, in the present embodiment, as an example, it is assumed that the M discharge units D are divided into four groups corresponding to the four ink cartridges 31 one by one. Then, each discharge unit D receives the supply of ink from the ink cartridge 31 corresponding to the group to which the discharge unit D belongs. Thereby, each discharge part D can be filled with the supplied ink inside, and can discharge the filled ink from the nozzle N (refer FIG. 3). That is, a total of M discharge units D included in the head unit HU can discharge four colors of CMYK as a whole.
In the present embodiment, as an example, it is assumed that a plurality of ejection units D belong to each group. Further, FIG. 2 is merely an example, and the ink cartridge 31 may be provided outside the carriage 110.

<< 2. Outline of recording head and discharge part >>
The recording head HD and the ejection unit D provided in the recording head HD will be described with reference to FIGS. 3 and 4.

FIG. 3 is a schematic partial cross-sectional view of the recording head HD, in which the recording head HD is cut to include the discharge part D. As shown in FIG.
As shown in FIG. 3, the discharge unit D includes a piezoelectric element PZ, a cavity 320 filled with ink therein, a nozzle N communicating with the cavity 320, and a diaphragm 310. The ejection unit D ejects the ink in the cavity 320 from the nozzle N by supplying the supply drive signal Vin to the piezoelectric element PZ and driving the piezoelectric element PZ with the supply drive signal Vin. The cavity 320 is a space defined by the cavity plate 340, the nozzle plate 330 in which the nozzles N are formed, and the diaphragm 310. The cavity 320 communicates with the reservoir 350 through the ink supply port 360. The reservoir 350 is in communication with the ink cartridge 31 corresponding to the ejection portion D via the ink intake port 370.

In the present embodiment, a unimorph (monomorph) type as shown in FIG. 3 is adopted as the piezoelectric element PZ. The piezoelectric element PZ is not limited to the unimorph type, and may be a bimorph type or a laminated type.
The piezoelectric element PZ has an upper electrode Zu, a lower electrode Zd, and a piezoelectric body Zm provided between the upper electrode Zu and the lower electrode Zd. Lower electrode Zd is electrically connected to power feed line LHd (see FIG. 11) set to power supply potential VBS on the low potential side. Then, when the drive signal Com (supply drive signal Vin) is supplied to the upper electrode Zu and a voltage is applied between the upper electrode Zu and the lower electrode Zd, the piezoelectric element PZ becomes + Z according to the applied voltage. It is displaced in the direction or −Z direction, and as a result, the piezoelectric element PZ vibrates.

  A diaphragm 310 is installed at the top opening of the cavity plate 340. The lower electrode Zd is joined to the diaphragm 310. Therefore, when the piezoelectric element PZ is driven and displaced by the supply drive signal Vin, the diaphragm 310 is also displaced. Then, the displacement of the diaphragm 310 changes the volume of the cavity 320, and the ink filled in the cavity 320 is discharged from the nozzle N.

  FIG. 4 is an explanatory view for explaining an example of the arrangement of the M nozzles N provided in the recording head HD when the inkjet printer 1 is viewed in plan from the + Z direction or the −Z direction.

As shown in FIG. 4, the print head HD is provided with four nozzle rows Ln. Here, the nozzle row Ln is a plurality of nozzles N provided so as to extend in a row in a predetermined direction. In the present embodiment, it is assumed that each nozzle row Ln is configured by arranging a plurality of nozzles N in a row in the X-axis direction.
Hereinafter, the four nozzle rows Ln provided in the print head HD will be referred to as nozzle rows Ln-BK, Ln-CY, Ln-MG, and Ln-YL, respectively. Here, the nozzle row Ln-BK is a nozzle row Ln in which the nozzles N of the discharge unit D that discharges the black ink are arranged, and the nozzle row Ln-CY is the nozzles N of the discharge unit D that discharges the cyan ink. And the nozzle row Ln-MG is a nozzle row Ln in which the nozzles N of the discharge section D that discharges the magenta ink are arranged, and the nozzle row Ln-YL discharges the yellow ink. It is a nozzle row Ln in which the nozzles N of the discharge part D are arranged.

  However, the nozzle row Ln shown in FIG. 4 is an example, and the plurality of nozzles N belonging to each nozzle row Ln are arranged with a predetermined width in a direction intersecting the extending direction of the nozzle row Ln. It is also good. That is, in each nozzle row Ln, the plurality of nozzles N belonging to each nozzle row Ln are arranged in a staggered manner so that positions of even-numbered nozzles N from the + X side and odd-numbered nozzles N in the Y-axis direction are different. May be Also, each nozzle row Ln may extend in a direction different from the X-axis direction. Further, in the present embodiment, although the case where the number of nozzle rows Ln provided in the print head HD is “4” is exemplified, the print head HD is provided with one or more nozzle rows Ln. Just do it.

<< 3. Outline of drive signal generation circuit >>
Next, the drive signal generation circuit 5 will be described with reference to FIG.

FIG. 5 is a block diagram showing the configuration of the drive signal generation circuit 5.
As shown in FIG. 5, the drive signal generation circuit 5 includes a DA conversion circuit 51, a voltage amplification circuit 52, and a current amplification circuit 53.

The DA conversion circuit 51 outputs a signal Q0 that defines the waveform of the drive signal Com based on the waveform designation signal dCom.
The voltage amplification circuit 52 outputs a signal Q1 and a signal Q2 based on the signal Q0. Specifically, the voltage amplification circuit 52 amplifies the voltage between the reference potential such as the power supply potential VBS on the low potential side and the signal Q0, for example, to obtain a potential corresponding to the potential of the drive signal Com. A signal Q1 and a signal Q2 are output.

The current amplification circuit 53 is a so-called push-pull circuit including a transistor Tr1 (an example of a “first transistor”) and a transistor Tr2 (an example of a “second transistor”).
Specifically, the transistor Tr1 is, for example, an NPN bipolar transistor, the signal Q1 is supplied to the base (B), and the collector (C) supplies electricity to the power supply line LHu supplying the high potential side power supply potential VHV. And the emitter (E) is electrically connected to the line LHa for supplying the drive signal Com.
The transistor Tr2 is, for example, a PNP bipolar transistor, the signal (Q2) is supplied to the base (B), and the collector (C) is electrically connected to the power supply line LHd supplying the low potential side power supply potential VBS. The emitter (E) is electrically connected to the line LHa for supplying the drive signal Com.

The current amplification circuit 53 generates a drive signal Com based on the signal Q1 and the signal Q2.
Specifically, of the current amplification circuit 53, the transistor Tr1 is turned on when the potential of the signal Q1 rises, and as a result, the potential of the drive signal Com is raised. The transistor Tr1 is turned off when the potential of the signal Q1 is constant and when the potential of the signal Q1 drops.
On the other hand, in the current amplification circuit 53, the transistor Tr2 is turned on when the potential of the signal Q2 falls, and as a result, the potential of the drive signal Com falls. The transistor Tr2 is turned off when the potential of the signal Q2 is constant and when the potential of the signal Q2 rises.

<< 4. Outline of power supply circuit >>
Next, the power supply circuit 9 will be described with reference to FIG.

FIG. 6 is a circuit diagram schematically showing an example of the configuration of the power supply circuit 9.
As shown in FIG. 6, the power supply circuit 9 includes a voltage conversion circuit 91 and a smoothing circuit 92.

  The voltage conversion circuit 91 transforms the AC voltage supplied from the commercial AC power supply 900, and outputs the transformed AC voltage to the smoothing circuit 92. Specifically, the voltage conversion circuit 91 includes an input terminal Tx1 and a transformer TRS. Among these, the input terminal Tx1 includes a terminal Tx1A and a terminal Tx1B which can be electrically connected to the power supply cable 910. Then, an AC voltage Vac is input to the input terminal Tx1 from the commercial AC power supply 900 via the power supply cable 910. Further, the transformer TRS transforms the AC voltage Vac input to the input terminal Tx1, and outputs the AC voltage after the transformation to the smoothing circuit 92.

  The smoothing circuit 92 smoothes the AC voltage output from the voltage conversion circuit 91 and converts it into a DC voltage. Specifically, the smoothing circuit 92 includes a rectifier circuit BD, a smoothing capacitor HC, and an output terminal Tn1. Among these, the rectifier circuit BD is, for example, a bridge diode configured to include a plurality of diodes, and rectifies an AC voltage input from the voltage conversion circuit 91. The smoothing capacitor HC smoothes the voltage rectified by the voltage conversion circuit 91 to convert it into a DC voltage Vdc, and supplies the DC voltage Vdc to the output terminal Tn1. The output terminal Tn1 includes a terminal Tn1A connected to the internal power supply wiring 920 and a terminal Tn1B. The terminal Tn1B is set to the power supply potential VBS on the low potential side, and is electrically connected to the feed line LHd. The terminal Tn1A is set to the high potential power supply potential VHV which is higher than the power supply potential VBS by the potential Vdc, and is electrically connected to the feed line LHu.

<< 5. Substrate and heat conductive sheet >>
Next, the arrangement of circuits on the substrate 200 and the positional relationship between the substrate 200 and the heat conduction sheet SH will be described with reference to FIGS. 7 to 10.

  FIG. 7 is an example of a plan view of the substrate 200 in which the substrate 200 is viewed in plan from the + Y side. Moreover, FIG. 8 is an example of the top view of the board | substrate 200 which planarly viewed the board | substrate 200 from the -Y side. In the present embodiment, as shown in FIG. 2, it is assumed that a thermally conductive sheet SH is provided between the substrate 200 and the frame FR located in the + Y direction of the substrate 200. That is, FIG. 7 is a view showing an example of a surface (hereinafter referred to as “surface G1”) of the substrate 200 on the heat conductive sheet SH side, and FIG. 8 is a heat conductive sheet of the substrate 200. It is a figure which shows an example of the surface (henceforth "the surface G2") on the opposite side to SH. In the substrate 200, the surface G1 on the heat conductive sheet SH side is an example of the "first surface", and the surface G2 on the side opposite to the heat conductive sheet SH of the substrate 200 is an example of the "second surface". It is.

  In this embodiment, as illustrated in FIG. 7, the drive signal generation circuit 5 including the transistor Tr1, the transistor Tr2, the DA conversion circuit 51, and the voltage amplification circuit 52 and the thermistor TM are provided on the surface G1 of the substrate 200. It is assumed that the temperature detection circuit 81 including, the notification circuit 82, the control circuit 6, and the storage circuit 4 are provided. However, the present invention is not limited to such an aspect, and at least the drive signal generation circuit 5 may be provided on the surface G1 of the substrate 200. Hereinafter, a circuit provided on the surface G1 of the substrate 200 may be referred to as a "first circuit".

  In the present embodiment, as illustrated in FIG. 8, on the surface G2 of the substrate 200, the power supply circuit 9 including the smoothing capacitor HC, the rectifier circuit BD, and the transformer TRS, the input terminal Tx1, and the input terminal Tx2 It is assumed that the output terminal Tn1 and the output terminal Tn2 are provided. Here, the input terminal Tx2 is a terminal to which information such as print data Img is supplied from the host computer, and which is connected to an external wiring 210 such as a Universal Serial Bus (USB) cable or a Local Area Network (LAN) cable. is there. The output terminal Tn2 is an internal terminal for supplying various control signals such as the print signal SI and the drive signal Com generated in the control module 2 to various components such as the head unit HU or the transport mechanism 7 and the like. It is a terminal for connecting to the wiring 220. Hereinafter, a circuit provided on the surface G2 of the substrate 200 may be referred to as a "second circuit".

  The substrate 200 is provided with a screw hole HL for inserting the screw SC. In the present embodiment, as illustrated in FIGS. 7 and 8, the case where the screw hole HL is provided between the transistors Tr1 and Tr2 is assumed as an example.

FIG. 9 is an example of a partial cross-sectional view in which the ink jet printer 1 is broken by a plane passing through the line segment E-e in FIG. 7 and FIG. 8.
As illustrated in FIG. 9, the heat transfer sheet SH is provided so as to be in contact with at least the transistors Tr1 and Tr2 and the frame FR between the surface G1 of the substrate 200 and the frame FR. The heat conduction sheet SH may be in contact with the surface G1 of the substrate 200 as illustrated in FIG. 9 in addition to the transistors Tr1 and Tr2 and the frame FR, and the first other than the transistors Tr1 and Tr2 It may be in contact with components of the circuit.

Hereinafter, as illustrated in FIG. 9, the distance between the portion of the first circuit that is most distant from the surface G1 and the surface G1 will be referred to as “distance W1”. Also, in the following, the distance between a portion of the second circuit that is most distant from the surface G2 and the surface G2 will be referred to as a “distance W2”. And in this embodiment, the 1st circuit and the 2nd circuit are provided so that distance W1 may become shorter than distance W2 as an example. In other words, in the present embodiment, among the various circuits included in the control module 2, a circuit having a component having a large height from the substrate 200, such as the smoothing capacitor HC, is provided on the surface G2. Further, in the present embodiment, among the various circuits included in the control module 2, only the components whose height from the substrate 200 is the distance W1 or less, such as the transistors Tr1 and Tr2, are provided on the surface G1. For this reason, in the present embodiment, the adhesion between the heat transfer sheet SH and the surface G1 can be enhanced as compared to the case where the height of the first circuit provided on the surface G1 is greater than the distance W1.
In the present embodiment, the width Ws of the heat conductive sheet SH is preferably equal to or greater than the distance W1, and more preferably equal to or greater than 1.5 times the distance W1. Further, in the present embodiment, the width Ws of the heat conductive sheet SH may be equal to or greater than the distance W1 and equal to or smaller than the distance W2.

  Further, in the present embodiment, as illustrated in FIG. 9, the heat conduction sheet SH is fixed to the frame FR using a screw SC for fixing the substrate 200 to the frame FR. In other words, in the present embodiment, the substrate 200 and the heat conduction sheet SH are fixed to the frame FR using the same screw SC.

  Although FIG. 9 exemplifies the case where the heat conduction sheet SH has a constant width Ws in the thickness direction, the present invention is not limited to such an aspect, and the heat conduction sheet SH is elastic. It may be formed by a body, and the width in the thickness direction of the heat conductive sheet SH may be made variable. In this case, as illustrated in FIG. 10, the heat conductive sheet SH has a width Ws1 at a portion of the surface G1 where the first circuit is not provided, contacts the surface G1, and the first circuit of the surface G1. The portion provided may have a width Ws2 and may be in contact with the first circuit. Here, the width Ws1 satisfies at least “W1 <Ws1”, and the width Ws2 satisfies at least “0 <Ws2 <Ws1”.

<< 6. Outline of head unit >>
Hereinafter, the configuration and operation of the head unit HU will be described with reference to FIGS. 11 to 13.

FIG. 11 is a block diagram showing an example of the configuration of the head unit HU. As described above, the head unit HU includes the recording head HD, the supply circuit 10, the line LHa, and the feed line LHd.
The supply circuit 10 includes M switches SW (SW [1] to SW [M]) and a connection state designation circuit 11 for specifying the connection state of each switch SW. In addition, as each switch SW, for example, a transmission gate can be adopted. In FIG. 11, only three switches SW are shown for the sake of simplicity.
The connection state designation circuit 11 selects one of the switches SW [1] to SW [M] based on at least a part of the clock signal CLK, the print signal SI, the latch signal LAT, and the change signal CNG supplied from the control circuit 6. Connection state designation signals SL [1] to SL [M] for specifying on / off of.
The switch SW [m] is electrically connected between the wiring LHa and the upper electrode Zu [m] of the piezoelectric element PZ [m] provided in the discharge part D [m] in response to the connection state designation signal SL [m]. And switch non-conduction. For example, the switch SW [m] is turned on when the connection state designation signal SL [m] is at the high level, and turned off when the connection state specifying signal SL [m] is at the low level. As described above, among the drive signals Com, the signal actually supplied to the piezoelectric element PZ [m] of the discharge unit D [m] through the switch SW [m] is the supply drive signal Vin [m].

  In the present embodiment, the operation period of the ink jet printer 1 includes one or more unit periods Tu. The inkjet printer 1 can drive each discharge unit D for printing processing in each unit period Tu. Then, the inkjet printer 1 executes the printing process in a plurality of unit periods Tu provided continuously or intermittently, thereby causing each ejection unit D to eject the ink, for example, one or more times, and the print data Img Form the image shown by

FIG. 12 is a timing chart showing an example of the operation of the ink jet printer 1 in the unit period Tu.
As shown in FIG. 12, the control circuit 6 outputs a latch signal LAT having a pulse PlsL. Thus, the control circuit 6 defines a unit period Tu as a period from the rising of the pulse PlsL to the rising of the next pulse PlsL. The control circuit 6 also outputs a change signal CNG having a pulse PlsC. Thus, the control circuit 6 divides the unit period Tu into a control period Tu1 from the rise of the pulse PlsL to the rise of the pulse PlsC and a control period Tu2 from the rise of the pulse PlsC to the rise of the pulse PlsL.
The print signal SI also includes individual designation signals Sd [1] to Sd [M] for designating the types of operations of the ejection units D [1] to D [M] in each unit period Tu. Then, when print processing is performed in unit period Tu, control circuit 6 generates print signal SI including individual designation signals Sd [1] to Sd [M] as clock signal CLK prior to unit period Tu. It synchronizes and supplies the connection state designation circuit 11. In this case, the connection state designation circuit 11 generates the connection state designation signal SL [m] based on the individual designation signal Sd [m] in the unit period Tu.

  As shown in FIG. 12, the drive signal Com has a waveform PX provided in the control period Tu1 and a waveform PY provided in the control period Tu2. In the present embodiment, the waveform PX and the waveform PY are determined such that the potential difference between the highest potential VHX and the lowest potential VLX of the waveform PX is larger than the potential difference between the highest potential VHY and the lowest potential VLY of the waveform PY. Specifically, when the discharge unit D [m] is driven by the drive signal Com having the waveform PX, the ink corresponding to the medium dot is discharged from the discharge unit D [m] To determine the waveform of the waveform PX. When driving the discharge part D [m] by the drive signal Com having the waveform PY, the waveform is such that the ink corresponding to a small dot (small amount) is discharged from the discharge part D [m]. Determine the PY waveform. The waveform PX and the waveform PY have the potential at the start and the end set to the reference potential V0.

FIG. 13 is an explanatory diagram for describing the relationship between the individual designation signal Sd [m] and the connection state designation signal SL [m].
As shown in FIG. 13, in this embodiment, it is assumed that the individual designation signal Sd [m] is a 2-bit digital signal. Specifically, in each unit period Tu, the individual designation signal Sd [m] discharges ink of an amount (large amount) corresponding to a large dot with respect to the discharge part D [m] (“large dot” Value (1, 1) specifying the formation of “(1)”, and value (1, 0) specifying discharge of a medium amount of ink (sometimes referred to as “formation of medium dot”) 4; a value (0, 1) specifying discharge of a small amount of ink (sometimes referred to as “small dot formation”), and a value (0, 0) specifying non-discharge of ink It is set to one of the values.

When individual designation signal Sd [m] is set to a value (1, 1) for designating formation of a large dot, connection state designation circuit 11 generates connection state designation signal SL [m] during control period Tu1 and control period Tu1. Set to high level at Tu2. In this case, the discharge unit D [m] is driven by the drive signal Com of the waveform PX in the control period Tu1 to discharge a medium amount of ink, and is driven by the drive signal Com of the waveform PY in the control period Tu2. Discharge a small amount of ink. As a result, the discharge unit D [m] discharges a large amount of ink in total in the unit period Tu, and large dots are formed on the recording paper P.
When individual designating signal Sd [m] is set to a value (1, 0) designating formation of a medium dot, connection state designation circuit 11 generates connection state designation signal SL [m] in control period Tu1. It is set to high level and low level in the control period Tu2. In this case, the discharge unit D [m] discharges a medium amount of ink in the unit period Tu, and a medium dot is formed on the recording paper P.
When individual designating signal Sd [m] is set to a value (0, 1) designating formation of a small dot, connection state designation circuit 11 generates connection state designation signal SL [m] in control period Tu1. The low level is set and the control period Tu2 is set high. In this case, the discharge unit D [m] discharges a small amount of ink in the unit period Tu, and small dots are formed on the recording paper P.
When the individual designation signal Sd [m] is set to a value (0, 0) for designating non-ejection of ink, the connection state designation circuit 11 controls the connection state designation signal SL [m] for the control period Tu1 and Tu2. Set to low level at. In this case, the discharge unit D [m] does not discharge the ink in the unit period Tu, and does not form dots on the recording paper P.

<< 7. Operation of inkjet printer >>
FIG. 14 is a flowchart showing the operation of the inkjet printer 1 when the inkjet printer 1 executes a print job. Hereinafter, the operation of the inkjet printer 1 in the case where the inkjet printer 1 executes a print job will be described with reference to FIG.

  The inkjet printer 1 starts the print job shown in FIG. 14 when the print data Img and the number of copies information CP are supplied from the host computer.

  As shown in FIG. 14, in the print job, the control circuit 6 first causes the storage circuit 4 to store the print data Img and the copy number information CP supplied from the host computer (S10).

Next, the control circuit 6 initializes various count values (S12). Specifically, in step S12, the control circuit 6 sets “0” to the total print number PP and sets “0” to the continuous print number α.
Here, the total number of printed sheets PP is the total value of the number of recording sheets P for which the formation of the image indicated by the print data Img is completed in the print job. Further, the continuous printing number α means that when the printing process is continuously executed in a plurality of continuous unit periods Tu, the formation of the image represented by the print data Img is completed in the printing process continuously executed. This is the number of recording sheets P that have been recorded.

  Thereafter, the control circuit 6 generates a print signal SI based on the print data Img (S14). The control circuit 6 may execute the process of step S14 prior to the process of step S12.

Next, the control circuit 6 determines whether or not the continuous printing number α is smaller than the reference number αth (an example of the “predetermined number”) (S16). Here, the reference number αth is a natural number that satisfies αth> 0.
If the result of the determination in step S16 is affirmative, the control circuit 6 determines whether the temperature indicated by the detection signal XS is lower than the reference temperature Tth (an example of the “predetermined temperature”) based on the notification signal XH. It judges (S18).
If the result of the determination in step S18 is affirmative, control circuit 6 supplies print signal SI including individual designation signals Sd [1] to Sd [M] to head unit HU, and drive signal generation circuit 5 On the other hand, by supplying the waveform designation signal dCom, the inkjet printer 1 is controlled so that the printing process is performed (S20).

Thereafter, the control circuit 6 updates the total printing number PP and the continuous printing number α (S22), and advances the process to step S32.
Specifically, in step S22, the control circuit 6 determines whether or not one print task (that is, formation of an image on one recording sheet P) is completed by the printing process executed in step S20. If the result of the determination is affirmative, “1” is added to the total print number PP, and “1” is added to the continuous print number α, and if the result of the determination is negative, The values of the total printing number PP and the continuous printing number α are not changed.

If the result of the determination in step S16 is negative, control circuit 6 stops the supply of print signal SI to head unit HU and the supply of waveform designation signal dCom to drive signal generation circuit 5 for a predetermined standby time. To do (S24). In other words, in step S24, the control circuit 6 stops the generation of the drive signal Com in the drive signal generation circuit 5, and stops the drive of the head unit HU.
Here, the stop of the supply of the print signal SI means that the control circuit 6 does not supply the print signal SI to the head unit HU in a certain unit period Tu. The stop of the supply of the waveform designation signal dCom means that the control circuit 6 does not supply the waveform designation signal dCom to the drive signal generation circuit 5 in a unit period Tu. Further, the waiting time is a time consisting of one or more unit periods Tu. Specifically, the standby time may be a predetermined time (for example, 10 seconds), or may be a time determined according to the reference number αth. For example, when the reference number αth is a large value, the standby time may be set to be longer than when the reference number αth is a small value.
In the present embodiment, the control circuit 6 stops the generation of the drive signal Com in the drive signal generation circuit 5 by stopping the supply of the waveform designation signal dCom, but the present invention is limited to such an aspect. Instead, the control circuit 6 causes the drive signal generation circuit 5 to stop the generation of the drive signal Com in the drive signal generation circuit 5 by supplying a signal designating the termination of the generation of the drive signal Com. May be

  Thereafter, the control circuit 6 initializes the continuous printing number α to “0” (S26), and advances the process to step S32.

When the result of the determination in step S18 is negative, control circuit 6 stops the supply of print signal SI to head unit HU and the supply of waveform designation signal dCom to drive signal generation circuit 5 for only unit period Tu. (S28).
Thereafter, the control circuit 6 initializes the continuous printing number α to “0” (S30), and advances the process to step S32.

Thereafter, the control circuit 6 determines whether the print job has ended (S32). Specifically, in step S32, the control circuit 6 determines whether the total print number PP is equal to or more than the number of print copies indicated by the copy number information CP.
Then, if the result of the determination in step S32 is affirmative, the control circuit 6 ends the series of processes shown in FIG. When the result of the determination in step S32 is negative, the control circuit 6 advances the process to step S16.

As described above, in the present embodiment, the control circuit 6 executes the printing process only at the timing at which both of the following condition 1 and condition 2 are satisfied, and at least at least the following condition 1 and condition 2 If one is not satisfied, the print job is interrupted without executing the print process.
<Condition 1>
The temperature indicated by the detection signal XS is less than the reference temperature Tth <Condition 2>
The continuous printing number α is less than the reference number αth

Then, in the present embodiment, when the condition 1 is not satisfied, the control circuit 6 waits for the condition 1 to be satisfied, and restarts the print job. Therefore, according to the present embodiment, the possibility that the state in which the temperature of the drive signal generation circuit 5 is high (for example, the temperature equal to or higher than the reference temperature Tth) continues can be reduced.
Further, in the present embodiment, when the condition 2 is not satisfied, the control circuit 6 resumes the print job after waiting for the waiting time. In other words, in the present embodiment, even if the temperature of the drive signal generation circuit 5 is not high, the control circuit 6 is highly likely that the temperature of the drive signal generation circuit 5 is high. Suspend the print job in advance. Therefore, according to the present embodiment, the possibility that the temperature of the drive signal generation circuit 5 becomes high can be reduced, thereby reducing the possibility that the print job is interrupted for a long period of time.

In the present embodiment, the control circuit 6 determines whether or not the condition 2 is satisfied in step S16, but the present invention is not limited to such an aspect, and the control circuit 6 In step S16, instead of condition 2 or in addition to condition 2, it may be determined whether one or both of condition 3 and condition 4 below are satisfied. That is, part or all of the conditions 1 to 4 is an example of the “predetermined condition”.
<Condition 3>
The number of continuous discharges β is less than the reference number of times βth (an example of “first reference value”) <Condition 4>
The continuous supply frequency γ is less than the reference frequency γth (an example of the “second reference value”)

Here, the continuous ejection number β refers to the number of ejections of ink from the head unit HU in the printing process that is continuously performed when the printing process is continuously performed in a plurality of continuous unit periods Tu. Is the total value of Further, the reference number of times βth is a natural number that satisfies βth> 0. The continuous ejection number β is initialized to “0” in step S12, a value corresponding to the print signal SI is added in step S22, and is initialized to “0” in steps S26 and S30.
The continuous supply number γ is the number of continuous unit periods Tu when the printing process is continuously performed in a plurality of continuous unit periods Tu. In other words, when the unit period Tu in which the drive signal Com is supplied from the drive signal generation circuit 5 to the head unit HU is continuous, the continuous supply number γ is the number of the continuous unit periods Tu. Further, the reference number of times γth is a natural number that satisfies γth> 0. The continuous supply number γ is initialized to “0” in step S12, “1” is added in step S22, and “0” is initialized in steps S26 and S30.

<< 8. Conclusion of embodiment >>
As described above, in the present embodiment, the heat conduction sheet SH is provided to be in contact with the transistors Tr1 and Tr2 and the frame FR. Therefore, according to the present embodiment, the heat generated in the drive signal generation circuit 5, in particular, the heat generated in the transistors Tr1 and Tr2 is transferred to the outside of the ink jet printer 1 through the heat conductive sheet SH and the frame FR. It becomes possible to dissipate heat.

  Further, in the present embodiment, the printing process is executed only when the condition 1 is satisfied. Therefore, according to the present embodiment, it is possible to prevent the drive signal generation circuit 5 from continuing the high temperature state.

  Further, in the present embodiment, the printing process is executed only when a part or all of the conditions 2 to 4 is satisfied. Therefore, according to the present embodiment, it is possible to reduce the possibility that the drive signal generation circuit 5 becomes high temperature.

<< B. Modified example >>
Each of the above embodiments can be variously modified. The aspect of a specific deformation | transformation is illustrated below. Two or more aspects arbitrarily selected from the following exemplifications may be combined as appropriate within the range not mutually contradictory. In addition, about the element in which an effect | action or a function is equivalent to embodiment in the modification illustrated below, the code | symbol referred by the above description is diverted and detailed description of each is abbreviate | omitted suitably.

<< Modification 1 >>
In the embodiment described above, M is a natural number of 8 or more, but this is an example, and M may be a natural number of 1 or more. For example, M may be a natural number of 720 or more. That is, the printing head HD may be provided with 720 or more ejection units D. In this case, the 720 or more ejection units D provided in the recording head HD may be driven by the drive signal Com generated by the drive signal generation circuit 5.

<< Modification 2 >>
In the embodiment and the modification described above, the transistors Tr1 and Tr2 are bipolar transistors, but the present invention is not limited to such an aspect, and the transistors Tr1 and Tr2 are field effect transistors (FET: Field Effect) It may be a transistor).

<< Modification 3 >>
In the embodiment and the modification described above, the control circuit 6 executes the printing process only when the condition 1 and a part or all of the conditions 2 to 4 are satisfied. Is not limited to such an aspect, and the control circuit 6 may execute the printing process when at least one of the conditions 1 to 4 is satisfied.
For example, when the condition 1 is satisfied, the control circuit 6 may execute the printing process regardless of whether the conditions 2 to 4 are satisfied.
Also, for example, when at least one of the conditions 2 to 4 is satisfied, the control circuit 6 may execute the printing process regardless of whether the condition 1 is satisfied. In this case, the inkjet printer 1 may be configured without the temperature detection circuit 81 and the notification circuit 82.

<< Modification 4 >>
In the embodiment and the modification described above, the heat transfer sheet SH is provided as a heat dissipation mechanism for dissipating heat in the substrate 200 in the ink jet printer 1, but the present invention is limited to such an embodiment. However, two or more heat transfer sheets SH may be provided as a heat release mechanism. For example, in the ink jet printer 1, the heat conduction sheet SH in contact with the surface G1 of the substrate 200, the first circuit, and the frame FR, and the other heat in contact with the surface G2 of the substrate 200, the second circuit, and the frame FR. And a conductive sheet SH.

<< Modification 5 >>
In the above-described embodiment and modification, one screw hole HL is provided between the transistors Tr1 and Tr2, but the present invention is not limited to such an aspect, and between the transistors Tr1 and Tr2 , A plurality of screw holes HL may be provided.

<< Modification 6 >>
In the embodiment and the modification described above, the inkjet printer 1 includes one drive signal generation circuit 5 and one head unit HU, but the present invention is not limited to such an aspect, The inkjet printer 1 may include a plurality of drive signal generation circuits 5 or may include a plurality of head units HU.
For example, the inkjet printer 1 may drive the discharge unit D by selectively supplying a plurality of drive signals Com having different waveforms to the discharge units D included in the head unit HU. In this case, the plurality of drive signal generation circuits 5 may be provided on the substrate 200 so as to correspond to the plurality of drive signals Com and one to one.
Also, for example, the inkjet printer 1 may include a plurality of head units HU. In this case, the plurality of drive signal generation circuits 5 may be provided on the substrate 200 so as to correspond to the plurality of head units HU on a one-to-one basis.
And in this modification, when a plurality of drive signal generation circuits 5 are provided on substrate 200, heat conduction sheet SH is provided so that transistors Tr1 and Tr2 which each drive signal generation circuit 5 comprises may be contacted.

<< Modification 7 >>
In the embodiment and the modification described above, it is assumed that the ink jet printer 1 is a serial printer, but the present invention is not limited to such a mode, and the ink jet printer 1 has a plurality of recording heads HD. It may be a so-called line printer in which the nozzles N are provided so as to extend wider than the width of the recording paper P.

DESCRIPTION OF SYMBOLS 1 ... ink jet printer, 2 ... control module, 4 ... memory circuit, 5 ... drive signal generation circuit, 6 ... control circuit, 7 ... conveyance mechanism, 9 ... power supply circuit, 10 ... supply circuit, 51 ... DA conversion circuit, 52 ... Voltage amplification circuit, 53: current amplification circuit, 100: housing, 200: substrate, D: discharge part, FR: frame, HC: smoothing capacitor, HD: recording head, HU: head unit, SC: screw, SH: Heat conduction sheet, Tr1 ... transistor, Tr2 ... transistor.

Claims (7)

With the frame
A drive signal generation circuit that generates a drive signal using the first transistor and the second transistor;
The first transistor, the second transistor, and a thermally conductive sheet in contact with the frame;
A head unit driven by the drive signal and capable of discharging a liquid;
When a predetermined condition is satisfied,
A control circuit for stopping the generation of the drive signal by the drive signal generation circuit;
Equipped with
Liquid discharge device characterized by. A substrate provided with the drive signal generation circuit;
A thermistor provided on the substrate for detecting a temperature;
Equipped with
The control circuit
When the temperature detected by the thermistor becomes equal to or higher than a predetermined temperature,
Stopping the generation of the drive signal by the drive signal generation circuit;
The liquid ejection apparatus according to claim 1, wherein The head unit is
Forming an image on the recording medium by discharging the liquid to the recording medium;
The control circuit
Counting the number of recording media on which an image is formed by the head unit;
When the counted number of recording media reaches or exceeds a predetermined number,
Stopping the generation of the drive signal by the drive signal generation circuit;
The liquid discharge device according to claim 1, wherein the liquid discharge device is a liquid discharge device. The control circuit
Counting the number of times the liquid is discharged from the head unit;
When the counted number of discharges becomes equal to or greater than a first reference value,
Stopping the generation of the drive signal by the drive signal generation circuit;
The liquid discharge device according to claim 1, wherein the liquid discharge device is a liquid discharge device. The drive signal generation circuit
The drive signal can be supplied to the head unit every unit period,
The control circuit
The drive signal generation circuit counts the number of unit periods in which the drive signal is supplied,
When the number of unit periods counted is equal to or greater than a second reference value,
Stopping the generation of the drive signal by the drive signal generation circuit;
The liquid discharge device according to claim 1, wherein the liquid discharge device is a liquid discharge device. The head unit is
It has more than 720 discharge parts,
The discharge unit is
It is driven by the drive signal to discharge the liquid.
The liquid discharge device according to any one of claims 1 to 5, characterized in that: With the frame
A drive signal generation circuit that generates a drive signal using the first transistor and the second transistor;
The first transistor, the second transistor, and a thermally conductive sheet in contact with the frame;
A head unit driven by the drive signal and capable of discharging a liquid;
A control method of a liquid discharge apparatus including:
When a predetermined condition is satisfied,
Stopping the generation of the drive signal by the drive signal generation circuit;
And controlling the liquid ejection device.

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