JP2018099869A - Liquid discharge device and circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge device which reduces the possibility such that a control signal deteriorates in a circuit board, and can accurately discharge a liquid.SOLUTION: A liquid discharge device includes a head unit which has a driving element and discharges a liquid based on a driving signal driving the driving element and a control signal controlling application of the driving signal to the driving element, and a first circuit board, where the first circuit board is provided with a control signal input terminal, a control signal transfer wiring, a control signal output terminal and a driving signal output terminal, a shortest distance between the control signal input terminal and a first side of the first circuit board is shorter than a shortest distance between the control signal input terminal and a second side crossing the first side of the first circuit board, a shortest distance between the control signal output terminal and the second side is shorter than a shortest distance between the control signal output terminal and the first side, and a distance between the control signal input terminal and the control signal output terminal is shorter than a distance between the control signal input terminal and the driving signal output terminal.SELECTED DRAWING: Figure 21

Description

  The present invention relates to a liquid ejection device and a circuit board.

  As a liquid ejecting apparatus such as an ink jet printer that ejects ink and prints an image or a document, an apparatus using a piezoelectric element (for example, a piezoelectric element) is known. The piezoelectric element is provided corresponding to each of the plurality of ejection units in the head (inkjet head), and each is driven according to a drive signal, whereby a predetermined amount of ink (liquid) is ejected from the nozzle of the ejection unit at a predetermined timing. ) Are ejected to form dots. Patent Document 1 discloses a relay substrate provided with wiring for transmitting a signal for driving the head to the ejection head.

JP 2014-188914 A

  Signals for driving the head include a drive signal for driving a piezoelectric element provided corresponding to the nozzle and a control signal for controlling application of the drive signal to the piezoelectric element. These signals are transferred. In a circuit board on which wiring is formed, there is a risk that signal degradation may occur during signal transfer depending on the wiring layout. In addition, when the circuit board needs to be replaced, it may be required that it can be easily replaced.

  The present invention has been made in view of at least a part of the above problems, and according to some aspects of the present invention, the possibility of deterioration of the control signal in the circuit board is reduced, and the liquid can be accurately supplied. A liquid discharge apparatus capable of discharging can be provided. In addition, according to some aspects of the present invention, it is possible to provide a liquid discharge apparatus that can be easily replaced when the circuit board needs to be replaced. In addition, according to some aspects of the present invention, it is possible to provide a circuit board that can reduce the possibility of signal degradation due to mutual interference between a drive signal and a control signal.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
The liquid ejection apparatus according to this application example includes a drive element, and ejects liquid based on a drive signal that drives the drive element and a control signal that controls application of the drive signal to the drive element. A head unit; and a first circuit board, wherein the first circuit board is connected to the control signal input terminal to which the control signal is input and the control signal input terminal to transfer the control signal. A control signal transfer wiring for transferring the drive signal, a drive signal transfer wiring for transferring the drive signal, a control signal output terminal connected to the control signal transfer wiring for outputting the control signal to the head unit, and the drive signal transfer wiring; A drive signal output terminal connected to output the drive signal to the head unit, and the shortest distance between the control signal input terminal and the first side of the first circuit board is The shortest distance between the control signal output terminal and the second side is shorter than the shortest distance between the control signal input terminal and the second side intersecting the first side of the first circuit board. The distance between the control signal output terminal and the first side is shorter than the shortest distance, and the distance between the control signal input terminal and the control signal output terminal is the distance between the control signal input terminal and the drive signal output terminal. Shorter than.

  The drive element may be, for example, a piezoelectric element or a heat generating element. The control signal may be a differential signal used for high-speed signal transfer, for example.

  In the liquid ejection apparatus according to this application example, in the circuit board, the control signal input terminal is provided along the first side, and the control signal output terminal is first along the second side that intersects the first side. It is provided at a position close to the side. Therefore, according to the liquid ejection apparatus according to this application example, the control signal transfer wiring is shortened in the circuit board, and the possibility that the control signal is deteriorated can be reduced, so that the liquid can be ejected with high accuracy.

[Application Example 2]
The liquid ejection apparatus according to the application example further includes a second circuit board to which the first circuit board is connected, and the first circuit board is further provided with a drive circuit that outputs the drive signal. The first circuit board includes a second circuit in a direction in which a surface on which the driving circuit is provided intersects a surface of the second circuit board to which the first circuit board is connected. It may be connected to the substrate.

  According to the liquid ejection apparatus according to this application example, since the region to which the first circuit board is connected is small in the second circuit board, the first circuit can be mounted with high density.

[Application Example 3]
In the liquid ejection apparatus according to the application example, the first circuit board further includes a first connector including the control signal input terminal, and the first circuit board includes the first connector. It may be connected to the second circuit board via

  According to the liquid ejection apparatus according to this application example, since the first connector can be attached to and detached from the second circuit board, it can be easily replaced when the first circuit board needs to be replaced. it can.

[Application Example 4]
In the liquid ejection apparatus according to the application example, the first circuit board is further provided with a second connector including the control signal output terminal and a third connector including the drive signal output terminal. May be.

  In the liquid ejection apparatus according to this application example, the control signal is transferred to the head unit through a cable connected to the second connector, separately from the cable that is connected to the third connector and transfers the drive signal to the head unit. The Therefore, according to the liquid ejection apparatus according to this application example, it is possible to reduce the possibility that the control signal is deteriorated, and thus it is possible to eject the liquid with high accuracy.

[Application Example 5]
In the liquid ejection apparatus according to the application example, the first connector is provided along the first side, and the second connector and the third connector are along the second side. It may be provided.

In the liquid ejection apparatus according to this application example, when the first circuit board is connected to the second board so that the second side is close to the head unit, the second connector and the third connector The cable connecting each head unit is shortened. Therefore, according to the liquid ejection apparatus according to this application example, the possibility that the drive signal and the control signal are deteriorated can be reduced, and thus the liquid can be ejected with high accuracy.

[Application Example 6]
The liquid ejection device according to the application example further includes a radiator attached to the first circuit board, and a case for housing the first circuit board, and the radiator contacts the case. You may do it.

  In the liquid ejection device according to this application example, since the radiator is in contact with the case housing the first circuit board, the heat conducted from the first circuit board to the radiator is efficiently conducted to the case. . Therefore, according to the liquid ejecting apparatus according to this application example, it is possible to reduce the possibility that the drive circuit directed to the first circuit board has a problem due to heat generation and the drive signal is deteriorated. It can be discharged.

[Application Example 7]
In the liquid ejection apparatus according to the application example, the head unit, the first circuit board, and the second circuit board may be mounted on a movable carriage.

  In the liquid ejection apparatus according to this application example, since the first circuit board provided with the drive circuit for outputting the drive signal is mounted on the movable carriage, the length of the wiring through which the drive signal propagates to the drive element Becomes shorter. Therefore, according to the liquid ejection apparatus according to this application example, it is possible to reduce overshoot and ringing that occur in the drive waveform, and thus it is possible to eject the liquid with high accuracy.

[Application Example 8]
The liquid ejection apparatus according to the application example may include a plurality of the first circuit boards.

[Application Example 9]
The circuit board according to this application example includes a drive element, and ejects liquid based on a drive signal that drives the drive element and a control signal that controls application of the drive signal to the drive element. A circuit board connected to the unit, the control signal input terminal to which the control signal is input, the control signal transfer wiring that is connected to the control signal input terminal and transfers the control signal, and the drive signal A drive signal transfer wiring that is connected to the control signal transfer wiring, a control signal output terminal that outputs the control signal to the head unit, and a drive signal transfer wiring that is connected to the drive unit and outputs the drive signal to the head unit. A drive signal output terminal, and a shortest distance between the control signal input terminal and the first side of the circuit board is a first distance between the control signal input terminal and the circuit board. Shorter than the shortest distance between the second side and the second side, and the shortest distance between the control signal output terminal and the second side is the shortest distance between the control signal output terminal and the first side. The distance between the control signal input terminal and the control signal output terminal is shorter than the distance between the control signal input terminal and the drive signal output terminal.

  In the circuit board according to this application example, the control signal input terminal is provided along the first side, and the control signal output terminal is located near the first side along the second side that intersects the first side. Is provided. According to the circuit board according to this application example, the control signal transfer wiring is shortened, and the possibility that the control signal is deteriorated can be reduced. Therefore, it is possible to accurately discharge the liquid to the connected head unit.

It is a side surface schematic diagram which shows the structure of a liquid discharge apparatus. It is a front view which shows the internal structure of a liquid discharge apparatus. It is a block diagram which shows the electrical structure of a liquid discharge apparatus. It is a figure which shows the structure of a discharge part. It is a figure which shows the waveform of drive signal COM-Ai and COM-Bi. It is a figure which shows the waveform of the drive signal Vout. It is a figure which shows the structure of a selection control part. It is a figure which shows the decoding content of a decoder. It is a figure which shows the structure of a selection part. It is a figure for demonstrating operation | movement of a selection control part and a selection part. It is a figure which shows the circuit structure of a drive circuit (capacitive load drive circuit). It is a figure for demonstrating operation | movement of a drive circuit. It is a side surface schematic diagram which shows the structure around a liquid discharge unit. It is a model perspective view which shows the internal structure of a liquid discharge unit. It is a side view of a drive circuit board. It is a figure which shows roughly an example of a structure of the 1st wiring layer of a drive circuit board. It is a figure which shows roughly an example of a structure of the 2nd wiring layer of a drive circuit board | substrate. It is a figure which shows roughly an example of a structure of the 3rd wiring layer of a drive circuit board. It is a figure which shows roughly an example of a structure of the 4th wiring layer of a drive circuit board. It is a figure which shows schematically an example of a structure of the 8th wiring layer of a drive circuit board. It is the figure which accumulated the 1st wiring layer of the drive circuit board, the 2nd wiring layer, the 3rd wiring layer, and the 8th wiring layer. It is the figure which accumulated the 1st wiring layer of the drive circuit board, the 3rd wiring layer, the 4th wiring layer, and the 8th wiring layer.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The drawings used are for convenience of explanation. The embodiments described below do not unduly limit the contents of the present invention described in the claims. Also, not all of the configurations described below are essential constituent requirements of the present invention.

1. Overview of Liquid Ejecting Apparatus A printing apparatus as an example of a liquid ejecting apparatus according to the present embodiment ejects ink in accordance with image data supplied from an external host computer, whereby ink dot groups are applied to a printing medium such as paper. This is an inkjet printer that prints an image (including characters, graphics, etc.) according to the image data.

  FIG. 1 is a schematic side view showing the configuration of the liquid ejection apparatus 1. FIG. 2 is a front view showing the internal configuration of the liquid ejection apparatus 1.

  As illustrated in FIG. 1, the liquid ejection apparatus 1 includes a feeding unit 12 that feeds out the medium M, a support unit 13 that supports the medium M, a transport unit 14 that transports the medium M, and a printing unit that performs printing on the medium M. 15, a blower unit 16 that blows gas toward the printing unit 15, and a control unit 10 that controls these configurations.

  In the following description, the width direction of the liquid ejection device 1 (the direction perpendicular to the paper surface in FIG. 1) is referred to as “first direction X”, and the depth direction of the liquid ejection device 1 (the left-right direction in FIG. 1) is defined as “first direction”. 2 ”, the height direction of the liquid ejection device 1 (the vertical direction in FIG. 1) is“ third direction Z ”, and the direction in which the medium M is transported is“ transport direction F ”. The first direction X, the second direction Y, and the third direction Z are directions that intersect (orthogonal) each other, and the transport direction F is a direction that intersects (orthogonal) the first direction X.

  The feeding unit 12 includes a holding member 18 that rotatably holds the roll body R around which the medium M is wound. The holding member 18 holds different types of media M and roll bodies R having different dimensions in the first direction X. In the feeding unit 12, the roll M is rotated in one direction (counterclockwise in FIG. 1) so that the medium M unwound from the roll R is fed out toward the support unit 13.

  The support unit 13 includes a first support unit 25, a second support unit 26, and a third support unit 27 that form a transport path for the medium M from the transport direction upstream to the transport direction downstream. The first support unit 25 guides the medium M fed from the feeding unit 12 toward the second support unit 26, and the second support unit 26 supports the medium M on which printing is performed, and the third support unit 27. Guides the printed medium M downstream in the transport direction.

  On the opposite side of the first support portion 25, the second support portion 26, and the third support portion 27 from the medium M transport path side, the first support portion 25, the second support portion 26, and the third support portion 27 are provided. There is provided a heating unit 22 for heating. The heating unit 22 supports the first support unit 25, the second support unit 26, and the third support unit 27 by heating the first support unit 25, the second support unit 26, and the third support unit 27. The medium M to be heated is indirectly heated. The heating unit 22 is configured by, for example, a heating wire (heater wire).

  The transport unit 14 includes a transport roller 23 that applies a transport force to the medium M, a driven roller 24 that presses the medium M against the transport roller 23, and a transport motor 41 that drives the transport roller 23. The transport roller 23 and the driven roller 24 are rollers having the first direction X as an axial direction.

  The transport roller 23 is disposed vertically below the transport path of the medium M, and the driven roller 24 is disposed vertically above the transport path of the medium M. The transport motor 41 is configured by, for example, a motor and a speed reducer. In the transport unit 14, the medium M is transported in the transport direction F by rotating the transport roller 23 while the medium M is sandwiched between the transport roller 23 and the driven roller 24.

  As shown in FIGS. 1 and 2, the printing unit 15 includes a guide member 30 extending along the first direction X and the liquid ejection unit 2. The liquid ejection unit 2 includes a carriage 29 that is supported by a guide member 30 so as to be movable along a first direction X, and a plurality (N) of head units that are supported by the carriage 29 and eject ink onto a medium M. 32 and a plurality (N) of drive circuit units 37 that are supported by the carriage 29 and that respectively drive the N head units 32. Further, the liquid ejection unit 2 controls the communication with the control unit 10 and relays various signals between the control unit 10 and each drive circuit unit 37, and each drive circuit unit 37 and the control board 36. And a heat radiating case 34 for housing the housing.

  The drive circuit unit 37 is electrically connected to the control unit 10 via the flexible flat cable 190 and the control board 36.

  N head units 32 are supported in the lower part of the carriage 29 in a state of being arranged at equal intervals in the first direction X, and the lower end of each head unit 32 protrudes from the lower surface of the carriage 29 to the outside. Yes. On the lower surface of each head unit 32, a plurality of ejection portions 600 from which ink is ejected are opened in a state arranged in the second direction Y.

Further, the printing unit 15 includes a carriage motor 31 that moves the carriage 29 in the first direction X, and a maintenance unit 80 that performs maintenance of each head unit 32.

  The maintenance unit 80 is provided adjacent to the second support portion 26 in the first direction X. The maintenance unit 80 executes maintenance processing for recovering the ink ejection state in the ejection unit 600 normally.

  The blower unit 16 includes a duct 51 that communicates the inside and outside of the housing 44 and a blower fan 52 provided in the duct 51. The duct 51 has an air blowing port 53 that opens toward the moving area W of the carriage 29. The air blowing port 53 of the duct 51 is arranged so as to overlap the heat radiating case 34 arranged in the carriage 29 in the third direction Z.

  A plurality of the air blowing units 16 are provided vertically above the movement area W of the carriage 29 so as to be arranged along the movement area W (first direction X). Therefore, the blower unit 16 can blow gas (air) toward the entire movement area W of the carriage 29. That is, the air blower 16 is disposed along the movement path of the carriage 29 and serves as an air flow generator that indirectly cools each drive circuit unit 37 in the heat radiating case 34 by blowing gas toward the heat radiating case 34. Function.

2. FIG. 3 is a block diagram illustrating an electrical configuration of the liquid ejection apparatus 1 according to the present embodiment. As shown in FIG. 3, the liquid ejection apparatus 1 includes a liquid ejection unit 2 (see FIGS. 1 and 2), a control unit 10 that controls ejection of liquid from the liquid ejection unit 2, a control unit 10, and a liquid A flexible flat cable 190 for connecting the discharge unit 2 is provided.

  The control unit 10 includes N discharge control modules 100 (100-1 to 100-N) and a communication control unit 160. The electrical configuration of the N discharge control modules 100 (100-1 to 100-N) is the same.

  Each of the N ejection control modules 100 (100-1 to 100-N) includes a control signal generation unit 110, a control signal conversion unit 120, a control signal transmission unit 130, and a drive data generation unit 140.

  When various signals such as image data are supplied from the host computer, the control signal generation unit 110 outputs various control signals for controlling each unit.

  Specifically, the control signal generator 110 generates n (n ≧ 1) original signals as a plurality of types of original control signals for controlling the discharge of the liquid from the discharge unit 600 based on various signals from the host computer. Print data signals sSI1 to sSIn, n original latch signals sLAT1 to sLATn, and n original change signals sCH1 to sCHn are generated and output to the control signal converter 120 in parallel format. Note that the plurality of types of original control signals may not include some of these signals, or may include other signals.

  The control signal conversion unit 120 converts the original print data signal sSIi (i is any one of 1 to n), the original latch signal sLATE, and the original change signal sCHi output from the control signal generation unit 110 into one serial format original. The signal is converted (serialized) into a serial control signal sSi and output to the control signal transmission unit 130.

The control signal transmission unit 130 converts the n original serial control signals sS1 to sSn output from the control signal conversion unit 120 into differential signals dS1 to dSn each composed of two signals, and the differential signals dS1 to dS1. dSn is transmitted to the liquid ejection unit 2 via the flexible flat cable 190. Further, the control signal transmission unit 130 generates a differential clock signal dClk used for high-speed serial data transfer of the differential signals dS1 to dSn via the flexible flat cable 190, and the differential clock signal dClk is generated by the flexible flat cable 190. To the liquid ejection unit 2 via For example, the control signal transmission unit 130 generates differential signals dS1 to dSn and a differential clock signal dClk of an LVDS (Low Voltage Differential Signaling) transfer method, and transmits them to the liquid ejection unit 2. Since the differential signal of the LVDS transfer system has an amplitude of about 350 mV, high-speed data transfer can be realized. The control signal transmission unit 130 generates differential signals dS1 to dSn and differential clock signals dClk of various high-speed transfer methods such as LVPECL (Low Voltage Positive Emitter Coupled Logic) and CML (Current Mode Logic) other than LVDS. Then, it may be transmitted to the liquid discharge unit 2.

  The drive data generation unit 140 is digital data that is a source of drive signals for driving the n drive modules 20 (20-1 to 20-n) included in the liquid ejection unit 2 based on various signals from the host computer. Certain 2n drive data dA1 to dAn, dB1 to dBn are generated and transmitted to the liquid ejection unit 2 via the flexible flat cable 190. In the present embodiment, the drive data dA1 to dAn and dB1 to dBn are digital data obtained by analog / digital conversion of a drive signal waveform (drive waveform). However, the drive data dA1 to dAn and dB1 to dBn may be digital data indicating a difference with respect to the latest drive data, and the correspondence between the length of each section having a constant slope in the drive waveform and each slope. It may be defined digital data.

  The communication control unit 160 communicates with the communication control unit 260 included in the liquid ejection unit 2 via the flexible flat cable 190, and reads various data setting processes and various data from the liquid ejection unit 2. Process.

  In addition to the above processing, the control unit 10 grasps the scanning position (current position) of the carriage 29 (liquid ejection unit 2), and performs processing for driving the carriage motor 31 based on the scanning position of the carriage 29. Do. Thereby, the movement of the carriage 29 in the first direction X is controlled. Further, the control unit 10 performs processing for driving the transport motor 41. Thereby, the movement of the medium M in the transport direction F is controlled.

  Further, the control unit 10 causes the maintenance unit 80 to perform a maintenance process for recovering the ink ejection state in the ejection unit 600 normally. The maintenance unit 80 may have a cleaning mechanism for performing a cleaning process (pumping process) for sucking thickened ink, bubbles, or the like in the discharge unit 600 by a tube pump (not shown) as a maintenance process. . Further, the maintenance unit 80 may have a wiping mechanism for performing a wiping process for wiping off foreign matters such as paper dust attached to the vicinity of the nozzles of the discharge unit 600 with a wiper member as a maintenance process.

  The liquid discharge unit 2 includes a plurality (N) of discharge modules 200 (200-1 to 200-N) and a communication control unit 260. The electrical configuration of the N discharge modules 200 (200-1 to 200-N) is the same.

  Each of the N discharge modules 200 (200-1 to 200-N) includes a drive circuit unit 37 (see FIGS. 1 and 2) and a head unit 32 (see FIGS. 1 and 2), and is controlled. The discharge of the liquid is controlled by each of the N discharge control modules 100 (100-1 to 100-N) included in the unit 10.

  The drive circuit unit 37 includes 2n drive circuits 50 (50-a1 to 50-an, 50-b1 to 50-bn). The n drive circuits 50-a1 to 50-an respectively drive the drive modules 20-1 to 20-n based on the drive data dA1 to dAn output from the drive data generation unit 140. COM-A1 to COM-An are generated. Similarly, the n drive circuits 50-b1 to 50-bn drive the drive modules 20-1 to 20-n based on the drive data dB1 to dBn output from the drive data generation unit 140, respectively. The drive signals COM-B1 to COM-Bn to be generated are generated. The 2n drive circuits 50 (50-a1 to 50-an, 50-b1 to 50-bn) differ only in the input drive data and the output drive signals, and have a circuit configuration. May be the same.

  The head unit 32 includes a plurality of piezoelectric elements 60 (an example of “driving elements”), driving signals COM-A1 to COM-An, COM-B1 to COM-Bn that drive the plurality of piezoelectric elements 60, and driving. Differential signals dS1 to dSn for controlling application of the signals COM-A1 to COM-An, COM-B1 to COM-Bn to the plurality of piezoelectric elements 60 and a differential clock signal dClk (an example of “control signal”); Based on the above, liquid (ink) is discharged. In the present embodiment, the head unit 32 includes n drive modules 20 (20-1 to 20-n), a control signal receiving unit 240, and a control signal restoring unit 250.

  The control signal receiving unit 240 receives the LVDS transfer type differential signals dS1 to dSn transmitted from the control signal transmitting unit 130, and differentially amplifies the received differential signals dS1 to dSn, respectively, to serial control signals S1 to S1. The converted serial control signals S <b> 1 to Sn are output to the control signal restoration unit 250. The control signal receiving unit 240 receives the LVDS transfer type differential clock signal dClk transmitted from the control signal transmitting unit 130, and differentially amplifies the received differential clock signal dClk to convert it into the clock signal Clk. The converted clock signal Clk is output to the control signal restoration unit 250. Note that the control signal receiving unit 240 may receive the differential signals dS1 to dSn and the differential clock signal dClk of various high-speed transfer methods such as LVPECL and CML other than LVDS.

  Based on the serial control signals S1 to Sn converted by the control signal receiving unit 240, the control signal restoring unit 250 has a clock signal Sck and n pieces of control signals as a plurality of types of control signals for controlling the discharge of the liquid from the discharge unit 600. Print data signals SI1 to SIn, n latch signals LAT1 to LATn, and n change signals CH1 to CHn are generated. Specifically, the control signal restoration unit 250 includes the original print data signal sSIi, the original latch signal sLATi, and the serial control signal Si (i is any one of 1 to n) output from the control signal receiving unit 240. By restoring (deserializing) the original change signal sCHi, the print data signal SIi, the latch signal LATi, and the change signal CHi are generated and output to the drive module 20-i. Further, the control signal restoration unit 250 performs a predetermined process (for example, a process of dividing the clock signal Clk output from the control signal receiving unit 240 with a predetermined frequency division ratio), and print data signals SI1 to SIn. The clock signals Sck synchronized with the latch signals LAT1 to LATn and the change signals CH1 to CHn are generated and output to the n drive modules 20 (20-1 to 20-n).

  The n drive modules 20 (20-1 to 20-n) have the same configuration, and each includes a selection control unit 220, m selection units 230, and m ejection units 600.

In the drive module 20-i (i is any one of 1 to n), the selection control unit 220 should select which of the drive signals COM-Ai and COM-Bi for each of the selection units 230 (or which one) Is not selected) is a clock signal Sck, a print data signal SIi, a latch signal LATi, and a change signal CHi output from the control signal restoration unit 250.
Direct by.

  Each of the selection units 230 selects the drive signals COM-Ai and COM-Bi in accordance with instructions from the selection control unit 220, outputs them to the corresponding ejection units 600 as the drive signals Vout, and outputs the piezoelectric elements 60 included in the ejection unit 600. Applied to one end. Further, the reference voltage signal VBS is commonly applied to the other ends of all the piezoelectric elements 60. The piezoelectric element 60 is provided corresponding to each of the ejection units 600 and is displaced by applying a drive signal Vout (drive signals COM-Ai, COM-Bi). Then, the piezoelectric element 60 is displaced according to the potential difference between the drive signal Vout (drive signals COM-Ai, COM-Bi) and the reference voltage signal VBS, and ejects liquid (ink). As described above, the drive signals COM-Ai and COM-Bi are signals for driving each of the discharge units 600 to discharge liquid.

  The drive signals COM-A1 to COM-An and COM-B1 to COM-Bn are signals for driving the ejection unit 600, and thus are high-voltage (several tens of volts) signals. The drive signals COM-A1 to COM The n drive circuits 50 (50-a1 to 50-n, 50-b1 to 50-bn) that generate -An, COM-B1 to COM-Bn, respectively, have large power consumption and are likely to become high temperature. Further, when the waveforms of the drive signals COM-A1 to COM-An and COM-B1 to COM-Bn change according to the temperature characteristics of the drive circuit 50 (50-a1 to 50-n, 50-b1 to 50-bn). The liquid discharge accuracy from the discharge unit 600 is affected. Accordingly, a temperature sensor is provided in the vicinity of the drive circuits 50-a1 to 50-n and 50-b1 to 50-bn, and the discharge control module 100 receives an output signal of the temperature sensor via the flexible flat cable 190. Based on the output signal of the temperature sensor, drive data dA1 to dAn and dB1 to dBn are generated so that the waveforms of the drive signals COM-A1 to COM-An and COM-B1 to COM-Bn are temperature-corrected. Also good. Further, even if the waveforms of the drive signals COM-A1 to COM-An and COM-B1 to COM-Bn are temperature-corrected, the ejection characteristics change depending on the temperature characteristics of the piezoelectric element 60, and as a result, the liquid ejection accuracy is affected. Occurs. Accordingly, a temperature sensor is provided in the vicinity of the discharge unit 600 (piezoelectric element 60) (for example, in the vicinity of the nozzle plate 632 (see FIG. 4)), and the discharge control module 100 is connected to the temperature sensor via the flexible flat cable 190. The drive data dA1 to dAn and dB1 to dBn may be generated so as to cancel the change in the temperature characteristics of the piezoelectric element 60 based on the output signal of the temperature sensor. By performing these processes by the discharge control module 100, the discharge accuracy of the liquid from the discharge unit 600 can be improved.

  The communication control unit 260 communicates with the communication control unit 160 included in the control unit 10 via the flexible flat cable 190, and in accordance with a request from the communication control unit 160, the n discharge modules 200-1 to 200-N. On the other hand, processing for setting various types of data and processing for reading out various types of data and transmitting them to the communication control unit 160 are performed. Specifically, the communication control unit 260 performs various setting processes for the drive circuit unit 37 (for example, the first reference voltage DAC_HV and the second reference voltage generated by the reference voltage generation unit 580 (see FIG. 11) included in each drive circuit 50). Voltage DAC_LV adjustment processing) and various data (for example, temperature data) indicating various states of the head unit 32 are read and transmitted to the communication control unit 160.

The communication between the communication control unit 160 and the communication control unit 260 may be, for example, an I ² C (Inter-Integrated Circuit) bus method or an SPI (Serial Peripheral Interface) bus method. Good.

3. Configuration of Discharge Unit FIG. 4 is a diagram illustrating a schematic configuration corresponding to one discharge unit 600 in the drive module 20. As shown in FIG. 4, the drive module 20 includes a discharge unit 600 and a reservoir 641.

  The reservoir 641 is provided for each ink color, and the ink is introduced into the reservoir 641 from the supply port 661. The ink may be supplied from an ink cartridge mounted on the liquid discharge unit 2 to the supply port 661 or from an ink tank attached to the main body side independently of the liquid discharge unit 2 via an ink tube. It may be supplied up to the supply port 661.

  The discharge unit 600 includes a piezoelectric element 60, a vibration plate 621, a cavity (pressure chamber) 631, and a nozzle 651. Among these, the diaphragm 621 functions as a diaphragm that is displaced (bending vibration) by the piezoelectric element 60 provided on the upper surface in the drawing, and expands / reduces the internal volume of the cavity 631 filled with ink. The nozzle 651 is an opening provided in the nozzle plate 632 and communicating with the cavity 631. The cavity 631 is filled with a liquid (for example, ink), and the internal volume changes due to the displacement of the piezoelectric element 60. The nozzle 651 communicates with the cavity 631 and discharges the liquid in the cavity 631 as droplets according to the change in the internal volume of the cavity 631.

  A piezoelectric element 60 shown in FIG. 4 has a structure in which a piezoelectric body 601 is sandwiched between a pair of electrodes 611 and 612. In the piezoelectric body 601 having this structure, the central portion in FIG. 4 is bent vertically with respect to both end portions together with the electrodes 611 and 612 and the diaphragm 621 in accordance with the voltage applied by the electrodes 611 and 612. Specifically, the piezoelectric element 60 is configured to bend upward when the voltage of the drive signal Vout increases, and to bend downward when the voltage of the drive signal Vout decreases. In this configuration, if the ink is bent upward, the internal volume of the cavity 631 is expanded. Therefore, if the ink is drawn from the reservoir 641, if the ink is bent downward, the internal volume of the cavity 631 is reduced. Depending on the degree, the ink is ejected from the nozzle 651.

  The piezoelectric element 60 is not limited to the illustrated structure, and may be any type that can deform the piezoelectric element 60 and discharge a liquid such as ink. Further, the piezoelectric element 60 is not limited to bending vibration, and may be configured to use so-called longitudinal vibration.

  In addition, the piezoelectric element 60 is provided corresponding to the cavity 631 and the nozzle 651 in the drive module 20, and is also provided corresponding to the selection unit 230. For this reason, a set of the piezoelectric element 60, the cavity 631, the nozzle 651, and the selection unit 230 is provided for each nozzle 651.

4). Configuration of Drive Signal As a method of forming dots on the medium M, in addition to a method of ejecting ink droplets once to form one dot, ink droplets can be ejected twice or more per unit period, One or more ink droplets ejected in step 1 are landed, and the landed one or more ink droplets are combined to form a single dot (second method), or these two or more ink droplets are combined. There is a method (third method) for forming two or more dots without any problem.

  In the present embodiment, by the second method, “large dot”, “medium dot”, “small dot”, and “non-recording (no dot)” are performed by ejecting ink twice at most for one dot. 4 gradations are expressed. In order to express these four gradations, in the present embodiment, two types of drive signals COM-Ai and COM-Bi are prepared in the drive module 20-i (i is any one of 1 to n). In FIG. 1, the first half pattern and the second half pattern are provided in one cycle. The drive signals COM-Ai and COM-Bi are selected (or not selected) in accordance with the gradation to be expressed in the first half and the second half of one cycle and supplied to the piezoelectric element 60.

  FIG. 5 is a diagram illustrating waveforms of the drive signals COM-Ai and COM-Bi. As shown in FIG. 5, the drive signal COM-Ai is latched next to the trapezoidal waveform Adp1 arranged in the period T1 from when the latch signal LATi rises to when the change signal CHi rises, and after the change signal CHi rises. This is a waveform in which the trapezoidal waveform Adp2 arranged in the period T2 until the signal LATi rises is continued. A period consisting of the period T1 and the period T2 is defined as a period Ta, and a new dot is formed on the medium M for each period Ta.

  In the present embodiment, the trapezoidal waveforms Adp1 and Adp2 are substantially the same waveforms, and if each is supplied to one end of the piezoelectric element 60, a predetermined amount from the nozzle 651 corresponding to the piezoelectric element 60, Specifically, it is a waveform for ejecting a medium amount of ink.

  The drive signal COM-Bi has a waveform in which the trapezoidal waveform Bdp1 arranged in the period T1 and the trapezoidal waveform Bdp2 arranged in the period T2 are continuous. In the present embodiment, the trapezoidal waveforms Bdp1 and Bdp2 are different from each other. Among these, the trapezoidal waveform Bdp1 is a waveform for causing the ink near the opening of the nozzle 651 to vibrate and preventing the viscosity of the ink from increasing. For this reason, even if the trapezoidal waveform Bdp1 is supplied to one end of the piezoelectric element 60, ink droplets are not ejected from the nozzle 651 corresponding to the piezoelectric element 60. The trapezoidal waveform Bdp2 is different from the trapezoidal waveform Adp1 (Adp2). If the trapezoidal waveform Bdp2 is supplied to one end of the piezoelectric element 60, it is a waveform that causes an amount of ink smaller than the predetermined amount to be ejected from the nozzle 651 corresponding to the piezoelectric element 60.

  The voltage at the start timing and the voltage at the end timing of the trapezoidal waveforms Adp1, Adp2, Bdp1, and Bdp2 are all the same as the voltage Vc. That is, the trapezoidal waveforms Adp1, Adp2, Bdp1, and Bdp2 are waveforms that start at the voltage Vc and end at the voltage Vc, respectively.

  FIG. 6 is a diagram illustrating waveforms of the drive signal Vout corresponding to “large dots”, “medium dots”, “small dots”, and “non-recording”.

  As shown in FIG. 6, the drive signal Vout corresponding to the “large dot” is a continuous trapezoidal waveform Adp1 of the drive signal COM-Ai in the period T1 and a trapezoidal waveform Adp2 of the drive signal COM-Ai in the period T2. It has a waveform. When this drive signal Vout is supplied to one end of the piezoelectric element 60, a medium amount of ink is ejected twice from the nozzle 651 corresponding to the piezoelectric element 60 in the period Ta. For this reason, the respective inks land on the medium M and coalesce to form large dots.

  The drive signal Vout corresponding to “medium dot” has a waveform in which the trapezoidal waveform Adp1 of the drive signal COM-Ai in the period T1 and the trapezoidal waveform Bdp2 of the drive signal COM-Bi in the period T2 are continuous. When this drive signal Vout is supplied to one end of the piezoelectric element 60, medium and small amounts of ink are ejected in two from the nozzle 651 corresponding to the piezoelectric element 60 in the period Ta. For this reason, the respective inks land on the medium M and merge to form medium dots.

The drive signal Vout corresponding to “small dots” is the voltage Vc immediately before being held by the capacitive property of the piezoelectric element 60 in the period T1, and the trapezoidal waveform Bdp2 of the drive signal COM-Bi in the period T2. When the drive signal Vout is supplied to one end of the piezoelectric element 60, a small amount of ink is ejected from the nozzle 651 corresponding to the piezoelectric element 60 only in the period T2 in the period Ta. For this reason, this ink is landed on the medium M to form small dots.

  The drive signal Vout corresponding to “non-recording” is the trapezoidal waveform Bdp1 of the drive signal COM-Bi in the period T1, and is the voltage Vc just before being held by the capacitive property of the piezoelectric element 60 in the period T2. When the drive signal Vout is supplied to one end of the piezoelectric element 60, the nozzle 651 corresponding to the piezoelectric element 60 only slightly vibrates in the period T2, and ink is not ejected in the period Ta. For this reason, ink does not land on the medium M, and dots are not formed.

5. Configuration of Selection Control Unit and Selection Unit FIG. 7 is a diagram illustrating a configuration of the selection control unit 220. As shown in FIG. 7, the selection control unit 220 is supplied with a clock signal Sck, a print data signal SIi, a latch signal LATi, and a change signal CHi. In the selection control unit 220, a set of a shift register (S / R) 222, a latch circuit 224, and a decoder 226 is provided corresponding to each of the piezoelectric elements 60 (nozzles 651).

  The print data signal SIi is 2-bit print data for selecting any one of “large dot”, “medium dot”, “small dot”, and “non-record” for each of the m ejection units 600. This is a signal of 2 m bits in total including (SIH, SIL).

  The print data signal SIi is serially supplied from the control signal restoration unit 250 in synchronization with the clock signal Sck. The shift register 222 is a configuration for temporarily holding each 2-bit print data (SIH, SIL) included in the print data signal SIi corresponding to the nozzle.

  More specifically, the shift registers 222 having the number of stages corresponding to the piezoelectric elements 60 (nozzles) are connected in cascade, and the serially supplied print data signal SIi is sequentially transferred to the subsequent stage according to the clock signal Sck. ing.

  When the number of piezoelectric elements 60 is m (m is a plurality), in order to distinguish the shift register 222, the first, second,..., M in order from the upstream side to which the print data signal SIi is supplied. It is written as a step.

  Each of the m latch circuits 224 latches 2-bit print data (SIH, SIL) held in each of the m shift registers 222 at the rising edge of the latch signal LATi.

  Each of the m decoders 226 decodes 2-bit print data (SIH, SIL) latched by each of the m latch circuits 224, and a period T1 defined by the latch signal LATi and the change signal CHi. , The selection signals Sa and Sb are output every T2, and the selection by the selection unit 230 is defined.

  FIG. 8 is a diagram showing the decoding contents in the decoder 226. For example, if the latched 2-bit print data (SIH, SIL) is (1, 0), the decoder 226 sets the logic levels of the selection signals Sa and Sb to the H and L levels in the period T1, respectively, and the period T2 Means output as the L and H levels, respectively.

  Note that the logic levels of the selection signals Sa and Sb are level-shifted to a higher amplitude logic by a level shifter (not shown) than the logic levels of the clock signal Sck, the print data signal SIi, the latch signal LATi, and the change signal CHi. The

  FIG. 9 is a diagram illustrating a configuration of the selection unit 230 corresponding to one piezoelectric element 60 (nozzle 651).

  As illustrated in FIG. 9, the selection unit 230 includes inverters (NOT circuits) 232a and 232b and transfer gates 234a and 234b.

  The selection signal Sa from the decoder 226 is supplied to a positive control terminal that is not circled in the transfer gate 234a, while being logically inverted by the inverter 232a and negatively controlled in the transfer gate 234a. Supplied to the end. Similarly, the selection signal Sb is supplied to the positive control terminal of the transfer gate 234b, while logically inverted by the inverter 232b and supplied to the negative control terminal of the transfer gate 234b.

  The drive signal COM-Ai is supplied to the input terminal of the transfer gate 234a, and the drive signal COM-Bi is supplied to the input terminal of the transfer gate 234b. The output terminals of the transfer gates 234a and 234b are connected in common, and the drive signal Vout is output to the ejection unit 600 via the common connection terminal.

  When the selection signal Sa is at the H level, the transfer gate 234a conducts (turns on) between the input end and the output end, and when the selection signal Sa is at the L level, the transfer gate 234a does not conduct between the input end and the output end. (Off). Similarly, the transfer gate 234b is turned on / off between the input end and the output end according to the selection signal Sb.

  Next, operations of the selection control unit 220 and the selection unit 230 will be described with reference to FIG.

  The print data signal SIi is serially supplied from the control signal restoration unit 250 for each nozzle in synchronization with the clock signal Sck, and sequentially transferred in the shift register 222 corresponding to the nozzle. When the supply of the clock signal Sck from the control signal receiving unit 240 is stopped, the shift register 222 is in a state in which 2-bit print data (SIH, SIL) corresponding to the nozzle is held. The print data signal SIi is supplied in the order corresponding to the last m stages,..., Two stages, and one stage nozzles in the shift register 222.

  Here, when the latch signal LATi rises, each of the latch circuits 224 latches the 2-bit print data (SIH, SIL) held in the shift register 222 at the same time. In FIG. 10, LT1, LT2,..., LTm indicate 2-bit print data (SIH, SIL) latched by the latch circuit 224 corresponding to the first, second,. Yes.

  The decoder 226 shows the logic levels of the selection signals Sa and Sb in each of the periods T1 and T2 in accordance with the dot size defined by the latched 2-bit print data (SIH, SIL), as shown in FIG. The output is as follows.

That is, when the print data (SIH, SIL) is (1, 1) and the size of the large dot is defined, the decoder 226 sets the selection signals Sa and Sb to the H and L levels in the period T1, and the period At T2, the H and L levels are set. Further, when the print data (SIH, SIL) is (1, 0) and the size of the medium dot is defined, the decoder 226 sets the selection signals Sa and Sb to the H and L levels in the period T1, and the period At T2, L and H levels are set. Further, the decoder 226 indicates that the print data (SIH, SIL) is (0
1), and when the size of a small dot is defined, the selection signals Sa and Sb are set to L and L levels in the period T1 and to L and H levels in the period T2. When the print data (SIH, SIL) is (0, 0) and non-recording is specified, the decoder 226 sets the selection signals Sa and Sb to the L and H levels in the period T1, and in the period T2. L and L level.

  When the print data (SIH, SIL) is (1, 1), the selection unit 230 selects the drive signal COM-Ai (trapezoidal waveform Adp1) because the selection signals Sa and Sb are at the H and L levels in the period T1. Since the Sa and Sb are at the H and L levels even during the period T2, the drive signal COM-Ai (trapezoidal waveform Adp2) is selected. As a result, the drive signal Vout corresponding to the “large dot” shown in FIG. 6 is generated.

  In addition, when the print data (SIH, SIL) is (1, 0), the selection unit 230 outputs the drive signal COM-Ai (trapezoidal waveform Adp1) because the selection signals Sa and Sb are at the H and L levels in the period T1. In the period T2, since Sa and Sb are at the L and H levels, the drive signal COM-Bi (trapezoidal waveform Bdp2) is selected. As a result, the drive signal Vout corresponding to the “medium dot” shown in FIG. 6 is generated.

  In addition, when the print data (SIH, SIL) is (0, 1), the selection unit 230 selects any of the drive signals COM-Ai and COM-Bi because the selection signals Sa and Sb are at the L and L levels in the period T1. In the period T2, Sa and Sb are at the L and H levels, so the drive signal COM-Bi (trapezoidal waveform Bdp2) is selected. As a result, the drive signal Vout corresponding to the “small dot” shown in FIG. 6 is generated. Note that since neither the drive signal COM-Ai nor COM-Bi is selected in the period T1, one end of the piezoelectric element 60 is opened. However, the drive signal Vout has the voltage Vc immediately before due to the capacitance of the piezoelectric element 60. Retained.

  In addition, when the print data (SIH, SIL) is (0, 0), the selection unit 230 outputs the drive signal COM-Bi (trapezoidal waveform Bdp1) because the selection signals Sa and Sb are at the L and H levels in the period T1. In the period T2, since the selection signals Sa and Sb are at the L and L levels, neither of the drive signals COM-Ai and COM-Bi is selected. As a result, the drive signal Vout corresponding to “non-recording” shown in FIG. 6 is generated. Note that, during the period T2, since neither the drive signal COM-Ai nor COM-Bi is selected, one end of the piezoelectric element 60 is opened. However, due to the capacitance of the piezoelectric element 60, the drive signal Vout has the immediately preceding voltage Vc. Retained.

  Note that the drive signals COM-Ai and COM-Bi shown in FIGS. 5 and 10 are merely examples. Actually, various combinations of waveforms prepared in advance are used according to the moving speed of the liquid discharge unit 2 and the properties of the medium M.

  Further, here, the example in which the piezoelectric element 60 bends upward as the voltage increases has been described. However, when the voltage supplied to the electrodes 611 and 612 is reversed, the piezoelectric element 60 increases as the voltage increases. Will bend downward. Therefore, in the configuration in which the piezoelectric element 60 bends downward as the voltage increases, the drive signals COM-Ai and COM-Bi illustrated in FIGS. 5 and 10 have waveforms that are inverted with respect to the voltage Vc. Become.

6). Configuration of Drive Circuit Next, the drive circuits 50-ai and 50-bi (i is any one of 1 to n) will be described. Of these, one drive circuit 50-ai is summarized as follows. The drive signal COM-Ai is generated as follows. That is, the drive circuit 50-ai first converts the drive data dAi supplied from the drive data generation unit 140 into an analog signal, and secondly outputs the drive signal COM.
-Ai is fed back, the deviation between the signal (attenuation signal) based on the drive signal COM-Ai and the target signal is corrected with the high-frequency component of the drive signal COM-Ai, and the modulation signal is generated according to the corrected signal. Third, an amplified modulated signal is generated by switching a transistor according to the modulated signal, and fourth, the amplified modulated signal is smoothed (demodulated) with a low-pass filter, and the smoothed signal is It outputs as drive signal COM-Ai.

  The other drive circuit 50-bi has the same configuration, and differs only in that the drive signal COM-Bi is output from the drive data dBi. Therefore, in FIG. 11 below, the drive circuits 50-ai and 50-bi will be described as the drive circuit 50 without distinction.

  However, input drive data and output drive signals are expressed as dAi (dBi), COM-Ai (COM-Bi), etc., and in the case of the drive circuit 50-ai, the drive data dAi is input. Then, the drive signal COM-Ai is output, and in the case of the drive circuit 50-bi, the drive data dBi is input and the drive signal COM-Bi is output.

  FIG. 11 is a diagram showing a circuit configuration of the drive circuit (capacitive load drive circuit) 50. FIG. 11 shows a configuration for outputting the drive signal COM-Ai.

  As illustrated in FIG. 11, the drive circuit 50 includes an integrated circuit device (capacitive load driving integrated circuit device) 500, an output circuit 550, a first feedback circuit 570, and a second feedback circuit 572. ing.

  The integrated circuit device 500 applies a gate signal (amplification control signal) to each of the first transistor M1 and the second transistor M2 based on k-bit drive data dAi (source signal) input via the terminals IN1 to INk. Output. Therefore, the integrated circuit device 500 includes a DAC (Digital to Analog Converter) 511, an adder 512, an adder 513, a comparator 514, an integral attenuator 516, an attenuator 517, an inverter 515, and a first gate. A driver 521, a second gate driver 522, a first power supply unit 530, a booster circuit 540, and a reference voltage generation unit 580 are included. Further, the integrated circuit device 500 may include a first power supply unit 530.

  The reference voltage generation unit 580 generates a first reference voltage DAC_HV (high voltage side reference voltage) and a second reference voltage DAC_LV (low voltage side reference voltage), and supplies the generated voltage to the DAC 511.

  The DAC 511 converts the drive data dAi defining the waveform of the drive signal COM-Ai into an original drive signal Aa having a voltage between the first reference voltage DAC_HV and the second reference voltage DAC_LV, and the input terminal ( +). The maximum amplitude and the minimum value of the original drive signal Aa are determined by the first reference voltage DAC_HV and the second reference voltage DAC_LV (for example, about 1 to 2 V), and the amplified voltage is used to drive the original drive signal Aa. It becomes the signal COM-Ai. That is, the original drive signal Aa is a target signal before amplification of the drive signal COM-Ai.

  The integral attenuator 516 attenuates the voltage of the terminal Out input through the terminal Vfb, that is, the drive signal COM-Ai, integrates it, and supplies it to the input terminal (−) of the adder 512.

  The adder 512 supplies a voltage signal Ab obtained by subtracting the voltage at the input terminal (−) from the voltage at the input terminal (+) to the input terminal (+) of the adder 513.

  Note that the power supply voltage of the circuit from the DAC 511 to the inverter 515 is 3.3 V having a low amplitude (power supply voltage VDD supplied from the power supply terminal Vdd). For this reason, while the voltage of the original drive signal Aa is about 2V at the maximum, the voltage of the drive signal COM-Ai may exceed 40V at the maximum, so that the amplitude range of both voltages is matched when obtaining the deviation. The voltage of the drive signal COM-Ai is attenuated by the integral attenuator 516.

  The attenuator 517 attenuates the high frequency component of the drive signal COM-Ai input through the terminal Ifb and supplies the attenuated high frequency component to the input terminal (−) of the adder 513. The adder 513 supplies a voltage signal As obtained by subtracting the voltage at the input terminal (−) from the voltage at the input terminal (+) to the comparator 514. The function of the attenuator 517 is adjustment of modulation gain (sensitivity). That is, the frequency and duty ratio of the modulation signal Ms change in accordance with the drive data dAi (source signal), but the attenuator 517 adjusts these changes.

  The voltage of the signal As output from the adder 513 is a voltage obtained by subtracting the attenuation voltage of the signal supplied to the terminal Ifb from the voltage of the original drive signal Aa by subtracting the attenuation voltage of the signal supplied to the terminal Vfb. is there. For this reason, the voltage of the signal As from the adder 513 is obtained by subtracting the deviation obtained by subtracting the attenuation voltage of the drive signal COM-Ai output from the terminal Out from the target voltage of the original drive signal Aa. It can be said that the signal is corrected with the high frequency component of Ai.

  The comparator 514 outputs a modulation signal Ms that is pulse-modulated as follows based on the subtraction voltage from the adder 513. Specifically, the comparator 514 is at the H level when the signal As output from the adder 513 is at a voltage rise, when the signal As becomes equal to or higher than the voltage threshold Vth1, and when the signal As is at the voltage fall, A modulation signal Ms that becomes L level when it falls below the threshold value Vth2 is output. As will be described later, the voltage threshold is set to have a relationship of Vth1> Vth2.

  The modulation signal Ms from the comparator 514 is supplied to the second gate driver 522 through logic inversion by the inverter 515. On the other hand, the modulation signal Ms is supplied to the first gate driver 521 without undergoing logic inversion. For this reason, the logic levels supplied to the first gate driver 521 and the second gate driver 522 are mutually exclusive.

  The logic levels supplied to the first gate driver 521 and the second gate driver 522 are actually timings so that they are not simultaneously at the H level (so that the first transistor M1 and the second transistor M2 are not turned on simultaneously). You may control. Therefore, strictly speaking, exclusive here means that they are not simultaneously at the H level (the first transistor M1 and the second transistor M2 are not simultaneously turned on).

  By the way, the modulation signal here is the modulation signal Ms in a narrow sense, but if it is considered that the signal is pulse-modulated according to the original drive signal Aa, a negative signal of the modulation signal Ms is also included in the modulation signal. That is, the modulation signal pulse-modulated according to the original drive signal Aa includes not only the modulation signal Ms but also a signal obtained by inverting the logic level of the modulation signal Ms and a signal whose timing is controlled.

  Note that the adder 512, the adder 513, the comparator 514, the inverter 515, the integral attenuator 516, and the attenuator 517 modulate the original drive signal Aa to generate the modulation signal Ms. It functions as a (modulation circuit).

  The first gate driver 521 level-shifts the low logic amplitude, which is the output signal of the comparator 514, to a high logic amplitude and outputs the result from the terminal Hdr. Of the power supply voltage of the first gate driver 521, the higher side is a voltage applied via the terminal Bst, and the lower side is a voltage applied via the terminal Sw. The terminal Bst is connected to one end of the capacitive element C5 and the cathode electrode of the backflow preventing diode D1. The terminal Sw is connected to the source electrode in the first transistor M1, the drain electrode in the second transistor M2, the other end of the capacitive element C5, and one end of the inductor L1. The anode electrode of the diode D1 is connected to one end of the terminal Gvd, and a voltage Vm (for example, 7.5 V) output from the booster circuit 540 is applied. Therefore, the potential difference between the terminal Bst and the terminal Sw is approximately equal to the potential difference between both ends of the capacitive element C5, that is, the voltage Vm (for example, 7.5 V).

  The second gate driver 522 operates on the lower potential side than the first gate driver 521. The second gate driver 522 levels the low logic amplitude (L level: 0 V, H level: 3.3 V), which is the output signal of the inverter 515, to a high logic amplitude (for example, L level: 0 V, H level: 7.5 V). Shift and output from terminal Ldr. Among the power supply voltages of the second gate driver 522, the voltage Vm (for example, 7.5V) is applied as the high-order side, and the voltage zero is applied through the ground terminal Gnd as the low-order side, that is, the ground terminal Gnd is grounded. Grounded. The terminal Gvd is connected to the anode electrode of the diode D1.

  The first transistor M1 and the second transistor M2 are, for example, N-channel FETs (Field Effect Transistors). Among these, in the first transistor M1 on the high side, the voltage Vh (for example, 42V) is applied to the drain electrode, and the gate electrode is connected to the terminal Hdr via the resistor R1. For the low-side second transistor M2, the gate electrode is connected to the terminal Ldr via the resistor R2, and the source electrode is grounded.

  Therefore, when the first transistor M1 is off and the second transistor M2 is on, the voltage at the terminal Sw is 0V, and the voltage Vm (for example, 7.5V) is applied to the terminal Bst. On the other hand, when the first transistor M1 is on and the second transistor M2 is off, Vh (for example, 42V) is applied to the terminal Sw, and Vh + Vm (for example, 49.5V) is applied to the terminal Bst.

  That is, the first gate driver 521 changes the reference potential (the potential of the terminal Sw) to 0 V or Vh (for example, 42 V) according to the operation of the first transistor M1 and the second transistor M2 using the capacitive element C5 as a floating power source. Therefore, an amplification control signal having an L level near 0 V and an H level near Vm (eg, 7.5 V), or an L level near Vh (eg, 42 V) and an H level near Vh + Vm (eg, 49.5 V) is output. To do. On the other hand, in the second gate driver 522, the reference potential (the potential of the ground terminal Gnd) is fixed to 0V regardless of the operations of the first transistor M1 and the second transistor M2, and therefore the L level is near 0V and An amplification control signal whose H level is near Vm (for example, 7.5 V) is output.

  The first gate driver 521 and the second gate driver 522 function as a gate driver 520 that generates an amplification control signal based on the modulation signal Ms. The first transistor M1 and the second transistor M2 function as an amplifier circuit that generates an amplified modulation signal obtained by amplifying the modulation signal Ms.

The other end of the inductor L1 is a terminal Out that is output from the drive circuit 50, and a drive signal COM-Ai is supplied to each of the selection units 230 from the terminal Out.

  The terminal Out is connected to one end of the capacitive element C1, one end of the capacitive element C2, and one end of the resistor R3. Among these, the other end of the capacitive element C1 is grounded. For this reason, the inductor L1 and the capacitive element C1 are a low-pass filter (Low Pass Filter) that smoothes (demodulates) the amplified modulation signal appearing at the connection point between the first transistor M1 and the second transistor M2 to generate a drive signal. It functions as 560 (demodulation circuit).

  The other end of the resistor R3 is connected to the terminal Vfb and one end of the resistor R4, and the voltage Vh is applied to the other end of the resistor R4. As a result, the drive signal COM-Ai that has passed through the first feedback circuit 570 (the circuit configured by the resistors R3 and R4) is pulled up and fed back to the terminal Vfb.

  On the other hand, the other end of the capacitive element C2 is connected to one end of the resistor R5 and one end of the resistor R6. Among these, the other end of the resistor R5 is grounded. For this reason, the capacitive element C2 and the resistor R5 function as a high-pass filter that passes a high-frequency component that is equal to or higher than the cutoff frequency in the drive signal COM-Ai from the terminal Out. Note that the cutoff frequency of the high-pass filter is set to about 9 MHz, for example.

  The other end of the resistor R6 is connected to one end of the capacitive element C4 and one end of the capacitive element C3. Among these, the other end of the capacitive element C3 is grounded. For this reason, the resistor R6 and the capacitive element C3 function as a low-pass filter that passes a low-frequency component that is equal to or lower than the cutoff frequency among the signal components that have passed through the high-pass filter. Note that the cutoff frequency of the LPF is set to about 160 MHz, for example.

  Since the cut-off frequency of the high-pass filter is set lower than the cut-off frequency of the low-pass filter, the high-pass filter and the low-pass filter pass high-frequency components in a predetermined frequency range in the drive signal COM-Ai. Functions as a band pass filter.

  The other end of the capacitive element C4 is connected to the terminal Ifb of the integrated circuit device 500. Accordingly, the drive signal COM that has passed through the second feedback circuit 572 (a circuit constituted by the capacitive element C2, the resistor R5, the resistor R6, the capacitive element C3, and the capacitive element C4) that functions as the bandpass filter is provided to the terminal Ifb. Of the high-frequency components of -Ai, the DC component is cut and returned.

  By the way, the drive signal COM-Ai output from the terminal Out smoothes the amplified modulation signal at the connection point (terminal Sw) between the first transistor M1 and the second transistor M2 by a low-pass filter including the inductor L1 and the capacitive element C1. Signal. This drive signal COM-Ai is integrated / subtracted via the terminal Vfb and then fed back to the adder 512. Therefore, the feedback delay (the delay due to the smoothing of the inductor L1 and the capacitive element C1, the integral attenuator) Self-oscillation at a frequency determined by the transfer function of feedback).

  However, since the delay amount of the feedback path through the terminal Vfb is large, the frequency of self-excited oscillation is high enough to ensure the accuracy of the drive signal COM-Ai only by the feedback through the terminal Vfb. You may not be able to.

Therefore, in this embodiment, by providing a path for feeding back the high-frequency component of the drive signal COM-Ai via the terminal Ifb, in addition to the path via the terminal Vfb, the delay when viewed as a whole circuit is reduced. ing. For this reason, the frequency of the signal As obtained by adding the high-frequency component of the drive signal COM-Ai to the signal Ab sufficiently ensures the accuracy of the drive signal COM-Ai as compared to the case where there is no path through the terminal Ifb. As high as you can.

  FIG. 12 is a diagram illustrating the waveforms of the signal As and the modulation signal Ms in association with the waveform of the original drive signal Aa.

  As shown in FIG. 12, the signal As is a triangular wave, and the oscillation frequency varies according to the voltage (input voltage) of the original drive signal Aa. Specifically, it is highest when the input voltage is an intermediate value, and decreases as the input voltage increases from the intermediate value or decreases.

  In addition, the slope of the triangular wave in the signal As is approximately equal between the rise (voltage rise) and the fall (voltage drop) when the input voltage is near the intermediate value. For this reason, the duty ratio of the modulation signal Ms, which is the result of comparing the signal As with the voltage thresholds Vth1 and Vth2 by the comparator 514, is approximately 50%. When the input voltage increases from the intermediate value, the downward slope of the signal As becomes gentle. For this reason, the period during which the modulation signal Ms is at the H level is relatively long, and the duty ratio is increased. On the other hand, as the input voltage becomes lower from the intermediate value, the upward slope of the signal As becomes gentler. For this reason, the period during which the modulation signal Ms is at the H level becomes relatively short, and the duty ratio becomes small.

  Therefore, the modulation signal Ms is a pulse density modulation signal as follows. That is, the duty ratio of the modulation signal Ms is approximately 50% at the intermediate value of the input voltage, and increases as the input voltage becomes higher than the intermediate value, and decreases as the input voltage becomes lower than the intermediate value.

  The first gate driver 521 turns on / off the first transistor M1 based on the modulation signal Ms. That is, the first gate driver 521 turns on the first transistor M1 if the modulation signal Ms is at the H level, and turns off the first transistor M1 if the modulation signal Ms is the L level. The second gate driver 522 turns on / off the second transistor M2 based on the logic inversion signal of the modulation signal Ms. In other words, the second gate driver 522 turns off the second transistor M2 when the modulation signal Ms is at the H level, and turns on when the modulation signal Ms is at the L level.

  Therefore, the voltage of the drive signal COM-Ai obtained by smoothing the amplified modulated signal at the connection point of the first transistor M1 and the second transistor M2 with the inductor L1 and the capacitive element C1 increases as the duty ratio of the modulated signal Ms increases. As the duty ratio decreases, the driving signal COM-Ai is controlled to be a signal obtained by expanding the voltage of the original driving signal Aa and is output.

  Since this drive circuit 50 uses pulse density modulation, there is an advantage that a change width of the duty ratio can be increased as compared with pulse width modulation in which the modulation frequency is fixed.

That is, since the minimum positive pulse width and negative pulse width that can be handled by the entire circuit are limited by the circuit characteristics, in the pulse width modulation with a fixed frequency, the duty ratio change width is within a predetermined range (for example, from 10%). Only 90%). On the other hand, in pulse density modulation, the oscillation frequency decreases as the input voltage moves away from the intermediate value. Therefore, the duty ratio can be increased in a region where the input voltage is high, and the region where the input voltage is low. In, the duty ratio can be further reduced. For this reason, in the self-excited oscillation type pulse density modulation, the change range of the duty ratio is wider (for example, 5%).
To 95%) can be secured.

  The drive circuit 50 is a self-excited oscillation circuit that includes a signal path through which the drive signal COM-Ai, the modulation signal Ms, and the amplified modulation signal propagate, and oscillates a high frequency carrier wave as in the case of separately excited oscillation. A circuit to be generated is unnecessary. For this reason, there is an advantage that integration other than a circuit that handles high voltage, that is, a portion of the integrated circuit device 500 is easy.

  In addition, in the drive circuit 50, the feedback path of the drive signal COM-Ai includes not only a path via the terminal Vfb but also a path that feeds back a high-frequency component via the terminal Ifb. Becomes smaller. For this reason, since the frequency of self-excited oscillation becomes high, the drive circuit 50 can generate the drive signal COM-Ai with high accuracy.

  Returning to FIG. 11, in the example shown in FIG. 11, the resistor R <b> 1, the resistor R <b> 2, the first transistor M <b> 1, the second transistor M <b> 2, the capacitor C <b> 5, the diode D <b> 1, and the low-pass filter 560 generate the amplification control signal based on the modulation signal. The output circuit 550 is configured to generate the drive signal COM-Ai based on the amplification control signal and output the drive signal COM-Ai to the capacitive load (piezoelectric element 60).

  The first power supply unit 530 applies a signal to a terminal different from the terminal to which the drive signal of the piezoelectric element 60 is applied. The first power supply unit 530 is configured by a constant voltage circuit such as a band gap reference circuit, for example. The first power supply unit 530 outputs a reference voltage signal VBS having a constant voltage (for example, 6V) from the terminal Vbs. In the example illustrated in FIG. 11, the first power supply unit 530 generates the reference voltage signal VBS with reference to the ground potential of the ground terminal Gnd.

  The booster circuit 540 supplies power to the gate driver 520. In the example shown in FIG. 11, the booster circuit 540 boosts the power supply voltage VDD supplied from the power supply terminal Vdd with reference to the ground potential of the ground terminal Gnd, and becomes the power supply voltage on the high potential side of the second gate driver 522. A voltage Vm is generated. The booster circuit 540 can be configured with a charge pump circuit, a switching regulator, or the like. However, the configuration of the charge pump circuit can suppress the generation of noise compared to the configuration of the switching regulator. Therefore, the drive circuit 50 can generate the drive signal COM-Ai with higher accuracy and can control the voltage applied to the piezoelectric element 60 with high accuracy, thereby improving the liquid ejection accuracy. . In addition, since the power generation unit of the gate driver 520 is reduced in size by being configured by a charge pump circuit, the gate driver 520 can be mounted on the integrated circuit device 500, and compared with the case where the power generation unit of the gate driver 520 is configured outside the integrated circuit device 500. Thus, the overall circuit area of the drive circuit 50 can be significantly reduced.

  The drive circuit unit 37 includes a power supply voltage generation circuit that generates voltages (voltage Vh, power supply voltage VDD, etc.) necessary for the operation of each drive circuit 50 separately from the integrated circuit device 500, and the first power supply unit 530. Alternatively, the booster circuit 540 may be included in the power supply generation circuit.

7). Structure of Liquid Discharge Unit FIG. 13 is a schematic side view showing the configuration around the liquid discharge unit 2 in the present embodiment. FIG. 14 is a schematic perspective view showing the internal configuration of the liquid discharge unit 2.

  As shown in FIG. 13, the carriage 29 includes a carriage main body 38 whose section when viewed in the first direction X is L-shaped, and a carriage main body 38 that is detachably attached to the carriage main body 38. And a cover member 39 that forms a closed space.

As shown in FIGS. 13 and 14, a front end portion of a rectangular heat radiation case 34 that accommodates each drive circuit unit 37 and the control board 36 is fixed to the upper end portion of the rear portion of the carriage 29. Accordingly, each drive circuit unit 37 and the control board 36 are supported by the carriage 29 via the heat dissipation case 34. The drive circuit units 37 are supported in the heat radiating case 34 in a state of being arranged at equal intervals in the first direction X.

  Each drive circuit unit 37 constitutes a drive circuit board 300 (an example of “first circuit board” or an example of “circuit board”), a heat sink 42 (an example of “heat radiator”), and a drive circuit 50. It has various circuit components (not shown).

  A flexible flat cable 190 is connected to the control board 36 (an example of “second circuit board”). In addition, a communication control unit 260 (for example, a microcontroller IC) is mounted on the control board 36. Furthermore, a plurality (N) of drive circuit boards 300 are connected to the control board 36. In particular, in the present embodiment, each drive circuit board 300 has a surface (drive circuit mounting surface) on which N drive circuits 50 (50-a1 to 50-an, 50-b1 to 50-bn) are provided. The drive circuit board 300 is connected to the control board 36 in a direction crossing the surface of the control board 36 to which the drive circuit board 300 is connected. With such a connection structure, a region where the drive circuit board 300 is connected to the control board 36 is reduced, and a plurality (N) of drive circuit units 37 can be mounted on the carriage 29 with high density. .

  Further, each drive circuit board 300 is provided with a connector 70 (an example of a “first connector”) on the surface opposite to the drive circuit mounting surface, and each drive circuit board 300 is connected via the connector 70. The control board 36 is detachably connected (detachable). With such a connection structure, when each drive circuit board 300 needs to be replaced, the drive circuit board 300 to be replaced can be easily replaced.

  Each heat sink 42 is attached to the surface of each drive circuit board 300 opposite to the drive circuit mounting surface, and releases heat generated in each part of each drive circuit unit 37. In addition to the connectors 70, 71, 72, for example, a capacitor for stabilizing the power supply is mounted on the surface opposite to the drive circuit mounting surface of each drive circuit board 300, compared with the drive circuit mounting surface. Since there is a large empty area (flat area), for example, a heat transfer sheet (not shown) is stuck in close contact with the empty area, and the heat radiating plate 42 is in contact with the heat transfer sheet. It is fixed to 300. Thereby, since the contact area of the heat sink 42 and a heat transfer sheet can be enlarged, the heat of the drive circuit board 300 is efficiently conducted to the heat transfer sheet and the heat sink 42. Furthermore, in the present embodiment, each heat radiating plate 42 is in contact with a heat radiating case 34 (an example of “case”) that accommodates each drive circuit board 300, and the heat conducted to the heat radiating plate 42 is further increased. It is designed to be conducted efficiently. Accordingly, the drive circuits 50-a1 to 50-an and 50-b1 to 50-bn of each drive circuit unit 37 are defective due to heat generation, and the drive signals COM-A1 to COM-An and COM-B1 to COM-Bn are generated. The risk of deterioration can be reduced. In addition, since each heat sink 42 is attached to the surface opposite to the drive circuit mounting surface of each drive circuit board 300, the drive circuits 50-a1 to 50-an and 50-b1 to 50-bn are heat sinks. Stable operation is possible without applying stress from 42.

  Here, the heat radiating case 34 and each heat radiating plate 42 are preferably configured as follows in order to efficiently radiate the heat generated in each drive circuit unit 37 to the outside. That is, it is preferable to increase the contact area between the heat dissipation case 34 and each heat dissipation plate 42 in order to increase the amount of heat transfer from each heat dissipation plate 42 to the heat dissipation case 34. Further, the heat radiating case 34 and each heat radiating plate 42 are preferably formed of a metal material having a high thermal conductivity such as aluminum in order to easily conduct heat. In order to increase the amount of heat released from the heat radiating case 34 to the outside air, heat radiating fins may be provided outside the heat radiating case 34. In that case, it is preferable to increase the area of the heat radiating fins in contact with the outside air.

  Each drive circuit board 300 is connected to the control unit 10 via the flexible flat cable 190 and the connector 70. From the control unit 10, the differential signals dS1 to dSn, the differential clock signal dClk, and the drive data dA1 to dAn, dB1. ~ DBn is input. Each drive circuit board 300 is connected to the communication control unit 260 via the connector 70, and various communication signals are input from the communication control unit 260, and various communication signals are output to the communication control unit 260. To do. That is, the connector 70 has a plurality of control signal input terminals to which the differential signals dS1 to dSn and the differential clock signal dClk are respectively input, and a plurality of drive signal inputs to which the drive data dA1 to dAn and dB1 to dBn are respectively input. A terminal and a plurality of communication terminals are provided.

  Further, a connector 71 (an example of “third connector”) and a connector 72 (an example of “second connector”) are provided on the surface opposite to the drive circuit mounting surface of each drive circuit board 300. The connectors 71 and 72 are exposed in the carriage 29 from the front surface of the heat dissipation case 34. Each head unit 32 has a connector 73 and a connector 74 on its upper surface. For example, one end of a connection cable 75 made of, for example, FFC (Flexible Flat Cable) is detachably connected to the connector 71, and the other end of the connection cable 75 is detachably connected to the connector 73. The Similarly, one end of a connection cable 76 formed of, for example, FFC is detachably connected to the connector 72, and the other end of the connection cable 76 is detachably connected to the connector 74. That is, each drive circuit board 300 and each head unit 32 are electrically connected via the two connection cables 75 and 76.

  The drive circuit board 300 sends drive signals COM-A1 to COM-An, COM-B1 to COM-Bn, a reference voltage signal VBS, and various signals for communication to the head unit 32 via the connector 71 and the connection cable 75. And various signals for communication are input from the head unit 32. That is, the connector 71 is provided with a plurality of drive signal output terminals and a plurality of communication terminals that respectively output the drive signals COM-A1 to COM-An and COM-B1 to COM-Bn.

  The drive circuit board 300 outputs the differential signals dS1 to dSn and the differential clock signal dClk to the head unit 32 via the connector 72 and the connection cable 76. That is, the connector 72 is provided with control signal output terminals for outputting the differential signals dS1 to dSn and the differential clock signal dClk, respectively. As described above, in this embodiment, the differential signals dS1 to dSn and the differential clock signal dClk that are susceptible to interference from other signals because they have a small amplitude (for example, several hundred mV) are connected to the connector 71, In addition to the connection cable 75 for transferring the drive signals COM-A1 to COM-An, COM-B1 to COM-Bn, various signals for communication, and the like to the head unit 32, the connection cable 76 connected to the connector 72 is used for the head. Since the data is transferred to the unit 32, the possibility that the differential signals dS1 to dSn and the differential clock signal dClk are deteriorated is reduced.

Further, the drive circuit board 300 includes a plurality of drive data transfer wirings and drive circuit 50- for transferring drive data dA1 to dAn from the connector 70 to the drive circuits 50-a1 to 50-an and 50-b1 to 50-bn, respectively. A plurality of drive signal transfer lines for transferring drive signals COM-A1 to COM-An, COM-B1 to COM-Bn from a1 to 50-an, 50-b1 to 50-bn to the connector 71 are provided. The drive circuit board 300 is provided with a reference voltage signal transfer wiring for transferring the reference voltage signal VBS in common from the drive circuits 50-a1 to 50-an, 50-b1 to 50-bn to the connector 71. The drive circuit board 300 also has a plurality of communication signals for transferring various communication signals between the connector 70 and the drive circuits 50-a1 to 50-an, 50-b1 to 50-bn, or the connector 71. Transfer wiring is provided. The drive circuit board 300 is provided with a plurality of control signal transfer wirings for transferring the differential signals dS1 to dSn and the differential clock signal dClk from the connector 70 to the connector 72, respectively.

  The head unit 32 ejects ink from the ejection unit 600 based on the differential signals dS1 to dSn, the differential clock signal dClk, and the drive signals COM-A1 to COM-An and COM-B1 to COM-Bn.

  The guide member 30 has a guide rail portion 48 extending in the first direction X at the lower front portion thereof. The carriage 29 is supported by a guide rail portion 48 so as to be movable in the first direction X at a carriage support portion 49 provided at the lower portion of the rear surface thereof. That is, the carriage support portion 49 is connected to the guide rail portion 48 so as to be slidable in the first direction X. That is, the carriage 29 supports the head unit 32 including the discharge unit 600 and the heat dissipation case 34 including the drive circuit unit 37, and is driven by the carriage motor 31 to the guide rail unit 48 of the guide member 30 by the carriage support unit 49. It reciprocates along the first direction X while being guided.

  Thus, in the present embodiment, the control board 36, each drive circuit unit 37 (drive circuit board 300), and each head unit 32 are mounted on the movable carriage 29. If each drive circuit unit 37 is not mounted on the carriage 29, the drive signals COM-A1 to COM-An and COM-B1 to COM-Bn propagate through the very long flexible flat cable 190. A large overshoot or ringing occurs in the drive waveform, and the liquid ejection accuracy from each head unit 32 deteriorates. On the other hand, in the present embodiment, since each drive circuit unit 37 is mounted on the carriage 29, the wiring through which the drive signals COM-A1 to COM-An and COM-B1 to COM-Bn propagate to the piezoelectric element 60 is provided. Since the overshoot and ringing generated in the drive waveform can be reduced, the liquid can be discharged from each head unit 32 with high accuracy.

  The carriage 29 is located on the front side of the guide member 30, and the heat dissipation case 34 that houses each drive circuit unit 37 is located on the upper side of the guide member 30. As a result, the rotational moment of the carriage 29 with the carriage support 49 as a fulcrum can be kept small, and the lengths of the connection cables 75 and 76 can be shortened. Accordingly, the weight balance of the carriage 29 is stabilized, and the signals output from the drive circuit units 37 to the head units 32 are stabilized.

8). Configuration of Drive Circuit Board FIG. 15 is a side view of the drive circuit board 300 in the present embodiment. As shown in FIG. 15, the drive circuit board 300 is a multilayer board in which four boards 300a, 300b, 300c, and 300d are stacked, and the upper surface of each of the boards 300a, 300b, 300c, and 300d (the upper face in FIG. 15). ) And the rear surface (the lower surface in FIG. 15) are formed with various wirings, through holes, and the like (not shown). The front surface and the back surface of the substrate 300a correspond to the first wiring layer LYR1 and the second wiring layer LYR2, respectively. Further, the front surface and the back surface of the substrate 300b correspond to the third wiring layer LYR3 and the fourth wiring layer LYR4, respectively. Further, the front surface and the back surface of the substrate 300c correspond to the fifth wiring layer LYR5 and the sixth wiring layer LYR6, respectively. The front surface and the back surface of the substrate 300d correspond to the seventh wiring layer LYR7 and the eighth wiring layer LYR8, respectively. The first wiring layer LYR1 and the eighth wiring layer LYR8 correspond to the drive circuit mounting surface of the drive circuit board 300 and the surface on the opposite side, respectively.

Hereinafter, eight drive circuits 50-a1 to 50-a4 and 50-b1 to the drive circuit board 300 are provided.
A case where 50-b4 is provided (in the case of n = 4) will be described as an example, and the configuration of some of the wiring layers will be described with reference to FIGS. 16 to 20 show only a part of circuit components, wiring, through holes, and the like. FIGS. 17 to 20 show the second wiring layer LYR2, the third wiring layer LYR3, the fourth wiring layer LYR4, and the eighth wiring layer LYR8 from the surface side (first wiring layer LYR1 side) of the drive circuit board 300, respectively. FIG. Although not illustrated, the fifth wiring layer LYR5, the sixth wiring layer LYR6, and the seventh wiring layer LYR7 of the drive circuit board 300 are also provided with various wirings, through holes, and the like.

  FIG. 16 is a diagram schematically showing an example of the configuration of the first wiring layer LYR1 of the drive circuit board 300. As shown in FIG. As shown in FIG. 16, the first wiring layer LYR1 includes a drive circuit 50-a1 that outputs a drive signal COM-A1, a drive circuit 50-b1 that outputs a drive signal COM-B1, and a drive signal COM-A2. A drive circuit 50-a2 that outputs, a drive circuit 50-b2 that outputs a drive signal COM-B2, a drive circuit 50-a3 that outputs a drive signal COM-A3, a drive circuit 50-b3 that outputs a drive signal COM-B3, The drive circuit 50-a4 that outputs the drive signal COM-A4 and the drive circuit 50-b4 that outputs the drive signal COM-B4 are directed from the short side P1 to the short side P2 of the substantially rectangular drive circuit board 300 ( They are arranged in a row in the second direction Y).

  FIG. 17 is a diagram schematically showing an example of the configuration of the second wiring layer LYR2 of the driving circuit board 300, and the second wiring layer LYR2 is seen through from the front surface side (first wiring layer LYR1 side) of the driving circuit board 300. FIG. As shown in FIG. 17, in the second wiring layer LYR2, the drive signal transfer wiring 301 for transferring the drive signal COM-A1, the drive signal transfer wiring 311 for transferring the drive signal COM-B1, and the drive signal COM- A drive signal transfer wiring 304 for transferring A4 and a drive signal transfer wiring 314 for transferring the drive signal COM-B4 are provided. In the second wiring layer LYR2, the ground wiring 350 is provided in almost all areas except the arrangement area of the drive signal transfer wirings 301, 304, 311 and 314.

  FIG. 18 is a diagram schematically showing an example of the configuration of the third wiring layer LYR3 of the drive circuit board 300. The third wiring layer LYR3 is seen through from the front surface side (first wiring layer LYR1 side) of the drive circuit board 300. FIG. As shown in FIG. 18, in the third wiring layer LYR3, the reference voltage signal transfer wiring 320 for transferring the reference voltage signal VBS, the control signal transfer wiring 331 for transferring the differential signal dS1, and the differential signal dS2 are sent. Control signal transfer wiring 332 for transferring, control signal transfer wiring 333 for transferring differential signal dS3, control signal transfer wiring 334 for transferring differential signal dS4, and control signal transfer wiring 335 for transferring differential clock signal dClk. And are provided.

  FIG. 19 is a diagram schematically showing an example of the configuration of the fourth wiring layer LYR4 of the drive circuit board 300. The fourth wiring layer LYR4 is seen through from the front surface side (first wiring layer LYR1 side) of the drive circuit board 300. FIG. As shown in FIG. 19, in the fourth wiring layer LYR4, a driving signal transfer wiring 302 that transfers the driving signal COM-A2, a driving signal transfer wiring 312 that transfers the driving signal COM-B2, and a driving signal COM- A drive signal transfer wiring 303 for transferring A3 and a drive signal transfer wiring 313 for transferring the drive signal COM-B3 are provided. In the fourth wiring layer LYR4, the ground wiring 360 is provided in almost all areas except the arrangement area of the drive signal transfer wirings 302, 303, 312, and 313.

FIG. 20 is a diagram schematically showing an example of the configuration of the eighth wiring layer LYR8 of the drive circuit board 300, and the eighth wiring layer LYR8 is seen through from the front surface side (first wiring layer LYR1 side) of the drive circuit board 300. FIG. As shown in FIG. 20, in the eighth wiring layer LYR8, the driving signal transfer wiring 301 for transferring the driving signal COM-A1, the driving signal transfer wiring 311 for transferring the driving signal COM-B1, and the driving signal COM- A drive signal transfer wiring 302 for transferring A2, a drive signal transfer wiring 312 for transferring drive signal COM-B2, a drive signal transfer wiring 303 for transferring drive signal COM-A3, and a drive for transferring drive signal COM-B3. A signal transfer line 313, a drive signal transfer line 304 for transferring the drive signal COM-A4, and a drive signal transfer line 314 for transferring the drive signal COM-B4 are provided. The drive signal transfer wirings 301 to 304, 311 to 314 provided in the eighth wiring layer LYR8 are the same as the drive signal transfer wirings 301 to 304 and 311 to 314 provided in the first wiring layer LYR1, respectively. Connected through vias.

  Further, in the eighth wiring layer LYR8, a control signal transfer wiring 331 that transfers the differential signal dS1, a control signal transfer wiring 332 that transfers the differential signal dS2, and a control signal transfer wiring 333 that transfers the differential signal dS3. And a control signal transfer wiring 334 for transferring the differential signal dS4 and a control signal transfer wiring 335 for transferring the differential clock signal dClk. The control signal transfer wirings 331 to 335 provided in the eighth wiring layer LYR8 are connected to the control signal transfer wirings 331 to 335 provided in the third wiring layer LYR3 through through holes and vias, respectively. .

  Further, the eighth wiring layer LYR8 is provided with a connector 70 including a plurality of terminals 340 along the long side Q2 of the drive circuit board 300, and a plurality of terminals 341 along the short side P2 of the drive circuit board 300. And a connector 72 having a plurality of terminals 342 are provided.

  The plurality of terminals 340 of the connector 70 include a plurality of control signal input terminals to which the differential signals dS1 to dS4 and the differential clock signal dClk are respectively input. Each of the control signal input terminals is a control signal. The transfer lines 331 to 335 are respectively connected. The plurality of terminals 340 include a plurality of drive data input terminals to which drive data dA1 to dA4 and dB1 to dB4 are input, respectively, and each of the plurality of drive data input terminals includes a first wiring layer. LYR1 is connected to each of a plurality of drive data transfer wirings (not shown) provided in at least one of the eighth wiring layers LYR8. Further, the plurality of terminals 340 include a plurality of communication terminals, and each of the plurality of communication terminals is provided in at least one of the first wiring layer LYR1 to the eighth wiring layer LYR8. Are connected to respective communication signal transfer wirings (not shown).

  The plurality of terminals 341 of the connector 71 include a plurality of drive signal output terminals that output the drive signals COM-A1 to COM-A4 and COM-B1 to COM-B4, respectively. Are connected to drive signal transfer wirings 301 to 304, 311 to 314, respectively. The plurality of terminals 341 include at least one reference voltage signal output terminal that outputs the reference voltage signal VBS, and the reference voltage signal output terminal is connected to the reference voltage signal transfer wiring 320. Furthermore, the plurality of terminals 341 include a plurality of communication terminals, and each of the plurality of communication terminals is connected to a plurality of communication signal transfer wirings (not shown).

  The plurality of terminals 342 of the connector 72 include a plurality of control signal output terminals that respectively output the differential signals dS1 to dS4 and the differential clock signal dClk, and each of the plurality of control signal output terminals is controlled. The signal transfer wirings 331 to 335 are respectively connected.

Each control signal input terminal included in the plurality of terminals 340 of the connector 70 and connected to the differential signals dS1 to dS4 and the differential clock signal dClk is connected to the long side Q2 (“first side”) of the drive circuit board 300. Is shorter than the shortest distance between each control signal input terminal and the short side P2 that intersects the long side Q2 of the drive circuit board 300 (an example of the “second side”). . The shortest distance between each control signal output terminal, which is included in the plurality of terminals 342 of the connector 72 and to which the differential signals dS1 to dS4 and the differential clock signal dClk are connected, and the short side P2 is the control signal. It is shorter than the shortest distance between the output terminal and the long side Q2. Further, the distance between each control signal input terminal included in the plurality of terminals 340 and each control signal output terminal included in the plurality of terminals 342 is included in each control signal input terminal and the plurality of terminals 341 of the connector 71. The drive signal transfer wirings 301 to 304 and 311 to 314 are shorter than the distances to the respective drive signal output terminals to which the drive signal transfer wirings 301 to 304 and 311 to 314 are connected. That is, in this embodiment, each control signal input terminal is provided along the long side Q2, and each control signal output terminal is provided at a position close to the long side Q2 along the short side P2 intersecting the long side Q2. Yes. Thereby, the control signal transfer wirings 331 to 335 are shortened, and the possibility that the differential signals dS1 to dS4 and the differential clock signal dClk are deteriorated is reduced.

  Further, since the connectors 71 and 72 are provided along the short side P2 close to the connectors 73 and 74 of the head units 32 in the drive circuit board 300, the connection cables 75 and 76 are shortened and the drive signal COM is shortened. -A1 to COM-A4, COM-B1 to COM-B4, differential signals dS1 to dS4, and the differential clock signal dClk are less likely to be deteriorated.

  FIG. 21 is a diagram in which the first wiring layer LYR1 (FIG. 16), the second wiring layer LYR2 (FIG. 17), the third wiring layer LYR3 (FIG. 18), and the eighth wiring layer LYR8 (FIG. 20) are stacked. FIG. 22 is a diagram in which the first wiring layer LYR1 (FIG. 16), the third wiring layer LYR3 (FIG. 18), the fourth wiring layer LYR4 (FIG. 19), and the eighth wiring layer LYR8 (FIG. 20) are overlapped. is there. 21 and 22, the reference voltage signal transfer wiring 320 and the ground wirings 350 and 360 are not shown.

  Referring to FIGS. 21 and 22, in this embodiment, the shortest distance between the long side Q1 of the drive circuit board 300 and each of the drive signal transfer wirings 301 to 304, 311 to 314 is the drive signal transfer wirings 301 to 304. , 311 to 314 and each of the control signal transfer wirings 331 to 335 is shorter than the shortest distance. The shortest distance between the long side Q2 facing the long side Q1 of the drive circuit board 300 and each of the control signal transfer wirings 331 to 335 is the control signal transfer with each of the drive signal transfer wirings 301 to 304 and 311 to 314. It is shorter than the shortest distance from each of the wirings 331 to 335. That is, since the drive signal transfer wirings 301 to 304, 311 to 314 are provided along the long side Q1, and the control signal transfer wirings 331 to 335 are provided along the long side Q2, the drive signal transfer wiring 301 is provided. ˜304, 311 to 314 and the control signal transfer wirings 331 to 335 are sufficiently separated. Accordingly, the drive signals COM-A1 to COM-A4, COM-B1 to COM-B4 having large amplitude (for example, several tens of volts) propagating through the drive signal transfer wirings 301 to 304 and 311 to 314, respectively, and the control signal transfer wiring The possibility that each signal deteriorates due to the mutual interference with the differential signals dS1 to dS4 and the differential clock signal dClk having a minute amplitude (for example, several hundred mV) and high frequency propagating through 331 to 335 is reduced.

  21 and 22, in the present embodiment, in the plan view of the drive circuit board 300, the drive circuits 50-a1 to 50-a4 and 50-b1 to 50-b4 are connected to the drive signal transfer wirings 301 to 301, respectively. 304, 311 to 314 and the control signal transfer wirings 331 to 335 are provided. As described above, since the drive signal transfer wirings 301 to 304 and 311 to 314 and the control signal transfer wirings 331 to 335 are arranged sufficiently apart from each other, a large empty area is generated between these wirings. Therefore, in the present embodiment, since the drive circuits 50-a1 to 50-a4 and 50-b1 to 50-b4 are arranged in this empty area, the short sides P1 and P2 of the drive circuit board 300 are shortened. Miniaturization of the drive circuit board 300 is realized.

21 and 22, in this embodiment, the integrated circuit device 500 (modulation) included in the control signal transfer wirings 331 to 335 and the drive circuits 50-a1 to 50-a4 and 50-b1 to 50-b4. The shortest distance from the unit 510) is shorter than the shortest distances between the control signal transfer wirings 331 to 335 and the first transistor M1 and the second transistor M2 (amplifier circuit). That is, the first transistor M1 and the second transistor M2 through which a large current flows are sufficiently separated from the control signal transfer wirings 331 to 335 that transfer the differential signals dS1 to dS4 and the differential clock signal dClk having minute amplitudes, respectively. The drive circuits 50-a1 to 50-a4 and 50-b1 to 50-b4 are arranged. This further reduces the possibility that the differential signals dS1 to dS4 and the differential clock signal dClk deteriorate.

  17, 18 and 19, in the present embodiment, the second wiring layer LYR2 and the fourth wiring layer LYR4, which are two layers sandwiching the third wiring layer LYR3 of the driving circuit board 300, Ground wirings 350 and 360 are provided in regions facing the regions where the differential signals dS1 to dS4 and the differential clock signal dClk are provided, respectively. That is, the control signal transfer wirings 331 to 335 are sandwiched and guarded by the ground wirings 350 and 360, and the possibility that the differential signals dS1 to dS4 and the differential clock signal dClk are deteriorated is further reduced.

  17 and 18, in the present embodiment, the drive signal transfer wirings 301, 304, 311 and 314 are provided in the second wiring layer LYR2 of the drive circuit board 300, and the reference voltage signal transfer wiring is provided. 320 is provided in the third wiring layer LYR3 of the driving circuit board 300 in a region facing the region in which the driving signal transfer wirings 301, 304, 311 and 314 are provided. Similarly, referring to FIGS. 18 and 19, in the present embodiment, the drive signal transfer wirings 302, 303, 312, and 313 are provided in the fourth wiring layer LYR4 of the drive circuit board 300, and the reference voltage signal transfer is performed. The wiring 320 is provided in a region facing the region where the driving signal transfer wirings 302, 303, 312, and 313 are provided in the third wiring layer LYR 3 of the driving circuit substrate 300. That is, the reference voltage signal transfer wiring 320 is the driving signal transfer wiring 301 provided in the second wiring layer LYR2 in the third wiring layer LYR3 located between the second wiring layer LYR2 and the fourth wiring layer LYR4. 304, 311, 314 and the drive signal transfer wirings 302, 303, 312, and 313 provided in the fourth wiring layer LYR4 are provided so as to face each other. For example, each piezoelectric element 60 included in the drive module 20-1 is applied with the drive signal COM-A1 or the drive signal COM-B1 at one end and the reference voltage signal VBS at the other end. Since the voltages of −A1 and COM-B1 are higher than the voltage of the reference voltage signal VBS, a large current flows in the order of the drive signal transfer wiring 301 or the drive signal transfer wiring 311, each piezoelectric element 60, and the reference voltage signal transfer wiring 320. There is a current path. In the present embodiment, the drive signal transfer wirings 301 to 304, 311 to 314 and the reference voltage signal transfer wiring 320 are provided to face each other in different wiring layers, whereby each current path is shortened and each current path is shortened. The wiring impedance is reduced.

  In addition, current flows in the drive signal transfer wirings 301 to 304 and 311 to 314 in the direction from the short side P1 to the short side P2 of the drive circuit board 300, whereas the reference voltage signal transfer wiring 320 has the drive circuit board. A current flows in a direction from 300 short side P2 to short side P1. That is, the current flowing through the drive signal transfer wirings 301 to 304, 311 to 314 and the current flowing through the reference voltage signal transfer wiring 320 are opposite to each other and have almost the same total amount, and the drive signal transfer wirings 301 to 304, Since the magnetic field generated by the current flowing through 311 to 314 and the magnetic field generated by the current flowing through the reference voltage signal transfer wiring 320 cancel each other, this further reduces the wiring impedance of each current path. Further, since the relative positions and distances of the drive signal transfer wirings 301 to 304, 311 to 314 and the reference voltage signal transfer wiring 320 are equal, the drive signals COM-A1 to COM-A4 and COM- Variations in the transfer accuracy of B1 to COM-B4 are reduced.

21 and 22, in the present embodiment, the driving circuit board 300 is included in the driving circuit 50-a1 and the plurality of terminals 341 of the connector 71 in the plan view, and the driving signal transfer wirings 301 and 311 are included. The shortest distances from the drive signal output terminals to which the drive signals are connected are included in the drive circuit 50-a2 and the plurality of terminals 341 of the connector 71, and the drive signals to which the drive signal transfer wirings 302 and 312 are connected, respectively. It is longer than the shortest distance to the output terminal, and the maximum width of the drive signal transfer wirings 301 and 311 is larger than the maximum width of the drive signal transfer wirings 302 and 312. In the plan view of the drive circuit board 300, the shortest distance between the drive circuit 50-a3 and each drive signal output terminal included in the plurality of terminals 341 of the connector 71 and connected to the drive signal transfer wirings 303 and 313, respectively. The distance is longer than the shortest distance between the drive circuit 50-a4 and each of the drive signal output terminals to which the drive signal transfer wirings 304 and 314 are connected, which are included in the plurality of terminals 341 of the connector 71, and the drive signal transfer. The maximum width of the wirings 303 and 313 is larger than the maximum width of the drive signal transfer wirings 304 and 314. Note that the maximum width of the drive signal transfer wirings 303 and 313 and the maximum width of the drive signal transfer wirings 303 and 313 are substantially the same. In other words, in the present embodiment, the drive signal transfer wiring having a longer wiring length is generally thicker, so that the drive signal transfer wirings 301 to 304 and 311 to 314 have the same wiring impedance, and the drive signal COM. -A1 to COM-A4, COM-B1 to COM-B4, variation in transfer accuracy is further reduced. Further, referring to FIGS. 17 and 19, in the present embodiment, the sum of the maximum widths of the drive signal transfer wirings 301, 311, 304, and 314 provided in the second wiring layer LYR2 and the fourth wiring layer LYR4 The sum of the maximum widths of the drive signal transfer wirings 302, 312, 303, and 314 provided is substantially equal. As a result, the vacant areas in the second wiring layer LYR2 and the fourth wiring layer LYR4 are reduced, and thereby the short sides P1 and P2 of the driving circuit board 300 are shortened, so that the driving circuit board 300 can be reduced in size.

9. As described above, in the liquid ejection apparatus 1 according to the present embodiment, in each drive circuit board 300, the control signal input terminals to which the control signal transfer wirings 331 to 335 are connected are on the long side Q2. Control signal output terminals 331 to 335 to which the control signal transfer wirings 331 to 335 are respectively connected are provided at positions close to the long side Q2 along the short side P2 intersecting the long side Q2. The transfer wirings 331 to 335 are shortened. In each drive circuit board 300, the differential signals dS1 to dSn and the differential clock signal dClk are connected to the connector 71, and the drive signals COM-A1 to COM-An and COM-B1 to COM-Bn are used for communication. Apart from the connection cable 75 for transferring various signals and the like to the head unit 32, the signals are transferred to the head unit 32 by a connection cable 76 connected to the connector 72. Therefore, according to the liquid ejection apparatus 1 according to the present embodiment, the possibility that the differential signals dS1 to dS4 and the differential clock signal dClk are deteriorated is reduced, so that the liquid can be ejected from each head unit 32 with high accuracy. it can. Furthermore, according to the liquid ejection apparatus 1 according to the present embodiment, the connectors 71 and 72 are provided along the short side P2 close to the connectors 73 and 74 of the head units 32 in the drive circuit board 300. Since the connection cables 75 and 76 are shortened, the possibility that the drive signals COM-A1 to COM-A4, COM-B1 to COM-B4, the differential signals dS1 to dS4, and the differential clock signal dClk are deteriorated is reduced. The liquid can be discharged from each head unit 32 with high accuracy.

  Further, in the liquid ejection apparatus 1 according to the present embodiment, since each heat radiating plate 42 is attached to the surface opposite to the drive circuit mounting surface of each drive circuit board 300, the drive circuits 50-a1 to 50-an. , 50-b1 to 50-bn can operate stably without applying stress from the heat radiating plate 42 and are in contact with the heat radiating case 34. It is efficiently conducted to the heat radiating case 34 through the plate 42. Therefore, according to the liquid ejection apparatus 1 according to the present embodiment, problems occur in the operation of the drive circuits 50-a1 to 50-an and 50-b1 to 50-bn, and the drive signals COM-A1 to COM-An, COM. Since the possibility that -B1 to COM-Bn deteriorates can be reduced, the liquid can be discharged from each head unit 32 with high accuracy.

  In the liquid ejection apparatus 1 according to the present embodiment, since the control board 36, the plurality of drive circuit boards 300, and the plurality of head units 32 are mounted on the movable carriage 29, the drive signal COM-A1. The length of the wiring through which COM-An and COM-B1 to COM-Bn propagate to the piezoelectric element 60 is shortened. Therefore, according to the liquid ejecting apparatus 1 according to the present embodiment, it is possible to reduce overshoot and ringing that occur in the drive waveform of the piezoelectric element 60, so that the liquid can be ejected from each head unit 32 with high accuracy.

  In the liquid ejection apparatus 1 according to the present embodiment, each drive circuit board 300 is connected to the control board 36 in a direction in which the drive circuit mounting surface intersects the surface of the control board 36. It is possible to mount the drive circuit unit 37 at a high density. Therefore, according to the liquid ejection apparatus 1 according to the present embodiment, the liquid ejection unit 2 can be reduced in size.

  Further, according to the liquid ejection apparatus 1 according to the present embodiment, each drive circuit board 300 is detachably connected to the control board 36 via the connector 70, so that each drive circuit board 300 needs to be replaced. In such a case, the drive circuit board 300 to be replaced can be easily replaced.

  Further, in the liquid ejection apparatus 1 according to the present embodiment, the drive signal transfer wiring and the control signal transfer wiring are sufficiently separated from each other in each drive circuit board 300, so that the large amplitude drive signals COM-A1 to COM-An. , COM-B1 to COM-Bn, and the mutual interference between the minute amplitude and high frequency differential signals dS1 to dSn and the differential clock signal dClk are reduced. In each drive circuit board 300, the first transistor M1 and the second transistor M2 through which a large current flows are sufficiently separated from the control signal transfer wiring, and the control signal transfer wiring is formed by the ground wiring of the upper and lower wiring layers. Since it is sandwiched and guarded, the possibility that the differential signals dS1 to dSn and the differential clock signal dClk are deteriorated is reduced. In addition, since each drive signal transfer wiring and the reference voltage signal transfer wiring are provided facing each other, each current path is shortened, and the magnetic field generated by the current flowing through each drive signal transfer wiring and the reference voltage signal transfer wiring Since the magnetic fields generated by the currents flowing through each other cancel each other, the wiring impedance of each current path is reduced. Also, the relative position and distance relationship between each drive signal transfer wiring and the reference voltage signal transfer wiring is equal, and the longer the drive signal transfer wiring, the wider the width, and the wiring impedance of each drive signal transfer wiring is equal. Therefore, variations in the transfer accuracy of the drive signals COM-A1 to COM-An and COM-B1 to COM-Bn are reduced. Therefore, according to the liquid ejection apparatus 1 according to the present embodiment, the drive signals COM-A1 to COM-An, COM-B1 to COM-Bn, the differential signals dS1 to dSn, and the differential clock signal in each drive circuit board 300. The dClk transfer accuracy is improved, and the liquid can be discharged from each head unit 32 with high accuracy.

  Further, in the liquid ejection apparatus 1 according to the present embodiment, in each drive circuit substrate 300, the drive circuits 50-a1 to 50-a4 are provided in the empty regions between the plurality of drive signal transfer lines and the plurality of control signal transfer lines. 50-b1 to 50-b4 are arranged. In each drive circuit board 300, a plurality of drive signal transfer wirings having different widths are provided in a plurality of wiring layers, and the area of the drive signal transfer wiring in each wiring layer is equal. . Therefore, according to the liquid ejection apparatus 1 according to the present embodiment, the empty area in each drive circuit board 300 can be reduced, so that each drive circuit board 300 can be reduced in size.

10. In the above-described embodiment, the control unit 10 and the liquid discharge unit 2 are connected by one flexible flat cable 190, but may be connected by a plurality of flexible flat cables. For example, each of the N flexible flat cables includes drive data dA1 to dAn, dB1 to dBn, and differential signals dS1 to dS to each discharge module 200.
n and the differential clock signal dClk may be transferred. In the above embodiment, various signals are transferred from the control unit 10 to the liquid ejection unit 2 by the flexible flat cable 190 (wired), but may be transferred wirelessly.

  In the above-described embodiment, a piezo-type liquid ejection device in which a drive circuit drives a piezoelectric element (capacitive load) as a drive element has been described as an example. However, the present invention is not limited to a capacitive load. The present invention can also be applied to a liquid ejection device that drives a drive element. As such a liquid ejecting apparatus, for example, a thermal method in which a driving circuit drives a heating element (for example, a resistor) as a driving element and ejects liquid using bubbles generated by heating the heating element. (Bubble type) liquid discharge device and the like.

  In the above embodiment, a printing apparatus such as a printer is exemplified as the liquid ejection apparatus. However, the present invention is a color material ejection apparatus, an organic EL display, and an FED (FED) used for manufacturing a color filter such as a liquid crystal display. The present invention can also be applied to liquid discharge devices such as electrode material discharge devices used for electrode formation such as surface emitting displays), bioorganic discharge devices used in biochip manufacturing, three-dimensional modeling devices (so-called 3D printers), textile printing devices, and the like.

  As mentioned above, although this embodiment or the modification was demonstrated, this invention is not limited to these this embodiment or a modification, It is possible to implement in a various aspect in the range which does not deviate from the summary. For example, it is possible to appropriately combine the above-described embodiment and each modification.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 ... Liquid discharge apparatus, 2 ... Liquid discharge unit, 10 ... Control unit, 12 ... Feeding part, 13 ... Supporting part, 14 ... Conveying part, 15 ... Printing part, 16 ... Blower part, 18 ... Holding member, 20, 20 -1 to 20-n: drive module, 22: heating unit, 23: transport roller, 24 ... driven roller, 25 ... first support unit, 26 ... second support unit, 27 ... third support unit, 29 ... carriage, DESCRIPTION OF SYMBOLS 30 ... Guide member, 31 ... Carriage motor, 32 ... Head unit, 34 ... Radiation case, 36 ... Control board, 37 ... Drive circuit unit, 38 ... Carriage body, 39 ... Cover member, 41 ... Conveyance motor, 42 ... Radiation plate , 44 ... housing, 48 ... guide rail part, 49 ... carriage support part, 50, 50-a1 to 50-an, 50-b1 to 50-bn ... drive circuit, 51 ... duct, 52 ... blower fan, 3 ... Blower, 60 ... Piezoelectric element, 70 ... Connector, 71 ... Connector, 72 ... Connector, 73 ... Connector, 74 ... Connector, 75 ... Connection cable, 76 ... Connection cable, 80 ... Maintenance unit, 100, 100-1 100-N: Discharge control module, 110: Control signal generation unit, 120 ... Control signal conversion unit, 130 ... Control signal transmission unit, 140 ... Drive data generation unit, 160 ... Communication control unit, 190 ... Flexible flat cable, 200 , 200-1 to 200-N: Discharge module, 220: Selection control unit, 222: Shift register, 224 ... Latch circuit, 226 ... Decoder, 230 ... Selection unit, 232a, 232b ... Inverter, 234a, 234b ... Transfer gate, 240 ... control signal receiving unit, 250 ... control signal restoration , 260 ... communication control unit, 300 ... drive circuit board, 300a, 300b ... board, 301 ... drive signal transfer wiring, 302 ... drive signal transfer wiring, 303 ... drive signal transfer wiring, 304 ... drive signal transfer wiring, 311 ... drive Signal transfer wiring, 312 ... Drive signal transfer wiring, 313 ... Drive signal transfer wiring, 314 ... Drive signal transfer wiring, 320 ... Reference voltage signal transfer wiring, 331 ... Control signal transfer wiring, 332 ... Control signal transfer wiring, 333 ... Control Signal transfer wiring, 334 ... Control signal transfer wiring, 335 ... Control signal transfer wiring, 340 ... Terminal, 341 ... Terminal, 342 ... Terminal, 350 ... Ground wiring, 360 ... Ground wiring, 500 ... Integrated circuit device, 510 ... Modulator 511 ... DAC, 512 ... adder, 513 ... adder, 514 ... comparator, 515 ... inverter, 516 Integral attenuator 517 Attenuator 520 Gate driver 521 First gate driver 522 Second gate driver 530 First power supply unit 540 Booster circuit 550 Output circuit 560 Low pass filter 570 ... first feedback circuit, 572 ... second feedback circuit, 580 ... reference voltage generator, 600 ... ejection unit, 601 ... piezoelectric body, 611,612 ... electrode, 621 ... vibrating plate, 631 ... cavity, 632 ... Nozzle plate, 641 ... reservoir, 651 ... nozzle, 661 ... supply port

Claims (9)

A head unit that has a driving element and that discharges liquid based on a driving signal that drives the driving element and a control signal that controls application of the driving signal to the driving element;
A first circuit board;
With
In the first circuit board,
A control signal input terminal to which the control signal is input;
A control signal transfer wiring connected to the control signal input terminal and transferring the control signal;
A drive signal transfer wiring for transferring the drive signal;
A control signal output terminal connected to the control signal transfer wiring and outputting the control signal to the head unit;
A drive signal output terminal connected to the drive signal transfer wiring and outputting the drive signal to the head unit;
Is provided,
The shortest distance between the control signal input terminal and the first side of the first circuit board is the distance between the control signal input terminal and the second side that intersects the first side of the first circuit board. Shorter than the shortest distance,
The shortest distance between the control signal output terminal and the second side is shorter than the shortest distance between the control signal output terminal and the first side,
The distance between the control signal input terminal and the control signal output terminal is shorter than the distance between the control signal input terminal and the drive signal output terminal,
A liquid discharge apparatus characterized by that. A second circuit board to which the first circuit board is connected;
In the first circuit board,
A drive circuit for outputting the drive signal is further provided;
The first circuit board is connected to the second circuit board in a direction in which the surface on which the drive circuit is provided intersects the surface of the second circuit board to which the first circuit board is connected. Being
The liquid ejection apparatus according to claim 1, wherein The first circuit board is further provided with a first connector including the control signal input terminal,
The first circuit board is connected to the second circuit board via the first connector.
The liquid discharge apparatus according to claim 2, wherein In the first circuit board,
A second connector including the control signal output terminal;
A third connector including the drive signal output terminal is further provided.
The liquid discharge apparatus according to claim 3. The first connector is provided along the first side;
The second connector and the third connector are provided along the second side,
The liquid ejecting apparatus according to claim 4, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. A radiator attached to the first circuit board;
A case for housing the first circuit board;
Further comprising
The radiator is in contact with the case;
The liquid ejecting apparatus according to claim 2, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. The head unit, the first circuit board, and the second circuit board are mounted on a movable carriage.
The liquid ejecting apparatus according to claim 2, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. A plurality of the first circuit boards;
The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. A circuit board having a driving element and connected to a head unit that ejects liquid based on a driving signal for driving the driving element and a control signal for controlling application of the driving signal to the driving element; And
A control signal input terminal to which the control signal is input;
A control signal transfer wiring connected to the control signal input terminal and transferring the control signal;
A drive signal transfer wiring for transferring the drive signal;
A control signal output terminal connected to the control signal transfer wiring and outputting the control signal to the head unit;
A drive signal output terminal connected to the drive signal transfer wiring and outputting the drive signal to the head unit;
Is provided,
The shortest distance between the control signal input terminal and the first side of the circuit board is shorter than the shortest distance between the control signal input terminal and the second side that intersects the first side of the circuit board. ,
The shortest distance between the control signal output terminal and the second side is shorter than the shortest distance between the control signal output terminal and the first side,
The distance between the control signal input terminal and the control signal output terminal is shorter than the distance between the control signal input terminal and the drive signal output terminal,
A circuit board characterized by that.

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