JP2019116044A - Liquid ejection device - Google Patents

Abstract

To provide a liquid ejection device in which heat dissipation performance of a substrate provided with a plurality of drive circuits is improved.SOLUTION: The liquid ejection device is provided that comprises: an ejection head which includes a nozzle ejecting liquid and to which a driving signal is input; a substrate which has a first side and a second side opposing to the first side in a first direction in which the liquid is ejected from the nozzle and is provided separately from the ejection head in a second direction intersecting with the first direction; a plurality of amplifier circuits which are provided in the substrate and juxtaposed toward the second direction in a center area between the first side and the second side, and generate the driving signals; and a plurality of elements which are provided in the substrate and juxtaposed toward the second direction in areas between the plurality of amplifier circuits and at least either one of the first side and the second side, and have heights larger than heights of the plurality of amplifier circuits.SELECTED DRAWING: Figure 14

Description

  The present invention relates to a liquid discharge device.

  2. Related Art A liquid discharge apparatus such as an ink jet printer which discharges ink to print an image or a document is known to use a piezoelectric element (e.g., a piezoelectric element). The piezoelectric element is provided corresponding to each of the plurality of nozzles in the head (ejection head), and each is driven according to the drive signal to eject a predetermined amount of ink (liquid) from the nozzles at a predetermined timing. Dots are formed. Since the piezoelectric elements are electrically capacitively loaded like a capacitor, it is necessary to supply a sufficient current to operate the piezoelectric elements of each nozzle. Therefore, in the above-described liquid discharge apparatus, the drive signal amplified by the drive circuit is supplied to the head to drive the piezoelectric element.

  Patent Document 1 and Patent Document 2 disclose a technology in which ink is ejected from a nozzle opening by providing a piezoelectric element in a head main body (ejection head) and causing pressure change in a pressure generation chamber by driving the piezoelectric element. ing.

Patent No. 5181898 gazette JP, 2011-207180, A

  In such an ejection head, in recent years, high-definition printing requirements for liquid ejection devices, specifically, high-precision (more simply, high-precision) printing requirements exceeding 600 dpi have been increasing. To meet such high precision printing requirements, the number of nozzles provided in the ejection head has been increased to increase the density of the nozzles based on the miniaturization of the piezoelectric element using the MEMS technology. Furthermore, in order to cope with such an increase in the number of nozzles and the densification of the nozzles, a technique is known in which a plurality of drive circuits are mounted on one substrate.

  However, the drive signal for driving the nozzle is a signal with a large amplitude, so the drive circuit generates heat when generating the drive signal. Such heat generation of the drive circuit may change the voltage value of the drive signal, and may further deteriorate the discharge characteristics of the ink due to the fluctuation of the voltage value of the drive signal.

  The problem of heat generation of such a drive circuit becomes more pronounced when a plurality of drive circuits are mounted on one substrate, and furthermore, since a plurality of drive circuits are provided on one substrate, the number of parts to be mounted is There is a risk that the components increase the path for radiating the heat generated in the drive circuit and the path for cooling the drive circuit by the cooling means etc., so that the drive circuit and a plurality of drive circuits are mounted. There is a new problem that the heat dissipation efficiency of the substrate and the cooling efficiency may decrease.

  According to some aspects of the present invention, it is possible to provide a liquid discharge device capable of improving the heat dissipation of a substrate provided with a plurality of drive circuits.

  The present invention has been made to solve at least a part of the above-mentioned problems, and it is possible to realize the following aspects or applications.

Application Example 1
The liquid ejection apparatus according to this application example receives a drive signal, and an ejection head including a nozzle that ejects liquid, a first side, and the first side in a first direction in which the liquid is ejected from the nozzle A substrate having a second side facing each other and spaced apart from the discharge head in a second direction intersecting the first direction, a substrate provided on the substrate, and the first side and the second side A plurality of amplification circuits arranged in parallel in the second direction in the middle region between the plurality of amplification circuits for generating the drive signal, the plurality of amplification circuits provided on the substrate, the first side and the second side And a plurality of elements arranged in parallel in the second direction in a region between at least one of the plurality of elements and having a height greater than the heights of the plurality of amplification circuits.

  In the liquid discharge device according to this application example, the heights of the plurality of amplifier circuits arranged in parallel in the second direction in the central region between the first side and the second side of the substrate, and the plurality of amplifier circuits are described. In the substrate provided with a plurality of elements having a large height, the plurality of elements are in a second direction in a region between the plurality of amplifier circuits and at least one of the first side and the second side. It is installed side by side. As described above, by arranging the plurality of amplification circuits and the plurality of elements having a large height in the same direction, the flow of heat emitted from the plurality of amplification circuits can be performed by the plurality of elements having a large height. An unobstructed path can be formed. Therefore, the heat released from the plurality of amplification circuits is efficiently discharged through the path. Therefore, the heat dissipation of the substrate provided with the plurality of amplifier circuits can be improved.

  Further, in the liquid discharge device according to the application example, when the plurality of amplifier circuits and the plurality of elements are provided on the same surface of the substrate, the heat emitted from the surfaces of the plurality of amplifier circuits is The flow is expelled through a path which is not easily blocked by the elements. On the other hand, when a plurality of amplification circuits and a plurality of elements are provided on different sides of the substrate, the heat released from the plurality of amplification circuits through the substrate is blocked by the plurality of elements. Exhausted through difficult routes.

  That is, in the liquid discharge device according to this application example, even when the plurality of amplifier circuits and the plurality of elements are provided on the same surface of the substrate, or are provided on different surfaces of the substrate Even in this case, the heat emitted from the plurality of amplification circuits can be efficiently discharged through the path in which the flow of the heat is not easily blocked by the plurality of elements. Therefore, the heat dissipation of the substrate provided with the plurality of amplifier circuits can be improved.

  Further, in the liquid discharge apparatus according to the application example, when a plurality of substrates are juxtaposed, a surface on which a heat flow of one of the two adjacent substrates is difficult to be blocked is formed, and the other The heat generated at the surface of the other substrate on which the plurality of elements are not provided is blocked by the heat flow of the one substrate by providing the surface of the other substrate on which the plurality of elements are not provided. Exhausted efficiently through difficult routes. Therefore, even when a plurality of substrates provided with a plurality of amplifier circuits is provided, the heat dissipation of each substrate can be improved.

  Furthermore, in the liquid discharge device according to this application example, since a path in which the flow of heat is difficult to be blocked is formed by the plurality of elements having a large height, when the liquid discharge device includes the cooling means, it is generated by the cooling means. The air flow can be efficiently supplied to a substrate provided with a plurality of amplification circuits through a path where heat flow is not easily blocked. Therefore, the heat dissipation (cooling performance) of the substrate provided with the plurality of amplification circuits can be improved.

Application Example 2
In the liquid ejection apparatus according to the application example, the ejection head may be provided with a plurality of ejection modules provided with 300 or more and 600 or more nozzles per inch.

  In the liquid discharge apparatus according to this application example, since heat generated by the plurality of amplifier circuits provided on the substrate can be efficiently discharged, the discharge head to which drive signals generated by the plurality of amplifier circuits are input is 1 inch. Even in the case of including a plurality of discharge modules provided with a plurality of nozzles of 300 or more and 600 or more nozzles, the substrate can be efficiently dissipated.

Application Example 3
In the liquid discharge device according to the application example, the plurality of amplification circuits are provided on a first surface of the substrate, and the plurality of elements are provided on a second surface of the substrate, and the first direction and the In the third direction intersecting the two directions, the substrate and the discharge head are arranged in parallel, and one of the first surface and the other of the other of the two adjacent substrates of the plurality of substrates are adjacent to each other. The faces may face each other.

  In the liquid discharge apparatus according to the application example, the plurality of substrates having the first surface provided with the plurality of amplification circuits and the second surface provided with the plurality of elements, and the plurality of discharge heads are arranged in the third direction. The first surface of one of the adjacent substrates and the second surface of the other of the adjacent substrates face each other. At this time, a path in which the flow of heat is not easily blocked is formed on the second surface of the other substrate. Therefore, the heat released from the plurality of amplifier circuits provided on the first surface of one of the substrates can be efficiently discharged through the path formed on the other of the substrates provided facing each other. .

Application Example 4
In the liquid ejection apparatus according to the application example, at least a part of the plurality of elements may be arranged in parallel along the first side.

  In the liquid discharge apparatus according to the application example, at least a part of the plurality of elements are arranged in parallel along the first side of the substrate, thereby widening a path where heat is not easily blocked by the plurality of elements having a large height. can do. Therefore, the heat dissipation of the substrate can be further improved.

Application Example 5
In the liquid ejection apparatus according to the application example, at least a part of the plurality of elements may be arranged in parallel along the second side.

  In the liquid discharge apparatus according to the application example, at least a part of the plurality of elements are arranged in parallel along the second side of the substrate, thereby widening a path where heat is not easily blocked by the plurality of elements having a large height. can do. Therefore, the heat dissipation of the substrate can be further improved.

Application Example 6
In the liquid discharge device according to the application example, the plurality of amplifier circuits may dissipate heat as the drive signal is generated.

  In the liquid discharge apparatus according to this application example, the plurality of amplifier circuits generate heat to generate the drive signal of the large voltage, and therefore, the plurality of amplifier circuits can be efficiently dissipated even if the large heat dissipation is involved. Thus, the heat dissipation of a substrate provided with a plurality of amplifier circuits can be improved.

Application Example 7
In the liquid discharge device according to the application example, the plurality of elements may include the plurality of amplification circuits.
A plurality of capacitors are provided in parallel in the second direction in a region between the first side and one of the second side, for stabilizing power supply voltage signals supplied to the plurality of amplifier circuits. May be included.

  In the liquid discharge device according to the application example, the capacitors having large capacitances and sizes for stabilizing the amplified voltage signals supplied to the plurality of amplifying circuits by the plurality of elements are the first side and the second side. Even when arranged in parallel in the second direction in the region between them, the heat generated in the plurality of amplifier circuits can be efficiently discharged through the path that is hard to be blocked by the plurality of capacitors.

Application Example 8
In the liquid discharge device according to the application example, the discharge head includes a piezoelectric element that is displaced by the supply of the drive signal and the reference voltage signal, and the nozzle is configured to move the liquid based on the displacement of the piezoelectric element. The plurality of elements are disposed in parallel in the second direction in a region between the plurality of amplifier circuits and the other of the first side and the second side, and are supplied to the piezoelectric element. And a plurality of capacitors for stabilizing the reference voltage signal.

  In the liquid discharge apparatus according to the application example, the plurality of capacitors have large capacitances and sizes for stabilizing the reference voltage signal supplied to the piezoelectric element, and one of the first side and the second side The heat generated in the plurality of amplifier circuits can be efficiently discharged through the path that is hard to be blocked by the plurality of capacitors even if the regions between the two are arranged in parallel in the second direction.

It is a side view which shows the structure of a liquid discharge apparatus. FIG. 6 is a side view showing a peripheral configuration of a printing unit of the liquid discharge device. FIG. 6 is a front view showing a peripheral configuration of a printing unit of the liquid discharge device. FIG. 6 is a perspective view showing a peripheral configuration of a printing unit of the liquid discharge device. It is an exploded perspective view of a discharge head. FIG. 6 is an exploded perspective view of the discharge head as viewed from the nozzle formation surface. It is a top view which shows the nozzle formation surface of a discharge head. It is sectional drawing which shows schematic structure of a discharge part. It is a block diagram which shows the electric constitution of a liquid discharge apparatus. It is a figure which shows the circuit structure of a drive circuit. It is a figure for demonstrating the operation | movement of a drive circuit. It is a top view for demonstrating arrangement of the parts and circuit of a drive circuit board. It is a side view for explaining arrangement of parts and circuits of a drive circuit board. FIG. 6 is a side view showing a drive circuit board and a discharge head in a state of being mounted on a liquid discharge device. FIG. 6 is a front view showing a drive circuit board and a discharge head in a state of being mounted on a liquid discharge device.

  Hereinafter, preferred embodiments of the present invention will be described using the drawings. The drawings used are for convenience of illustration. Note that the embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, not all of the configurations described below are necessarily essential configuration requirements of the present invention.

  Hereinafter, the liquid ejection apparatus according to the present invention will be described by taking an inkjet printer, which is a printing apparatus, as an example.

1. Outline of Liquid Ejection Device The configuration of the liquid ejection device 1 in the present embodiment will be described using FIGS. 1 to 4.

  FIG. 1 is a side view showing the configuration of the liquid ejection device 1. FIG. 2 is a side view showing the peripheral configuration of the printing unit 6 of the liquid discharge device 1. FIG. 3 is a front view showing the peripheral configuration of the printing unit 6 of the liquid ejection device 1. FIG. 4 is a perspective view showing the peripheral configuration of the printing unit 6 of the liquid discharge device 1.

  As shown in FIG. 1, the liquid discharge apparatus 1 includes a delivery unit 3 for delivering the medium M, a support unit 4 for supporting the medium M, a transport unit 5 for transporting the medium M, and a printing unit for printing on the medium M 6 and a control unit 2 that controls these configurations.

  In the following description, the width direction of the liquid ejection device 1 is referred to as “scanning direction X” (an example of “third direction”), and the depth direction of the liquid ejection device 1 is referred to as “front and back direction Y” (“second direction”). The height direction of the liquid ejection device 1 is referred to as “vertical direction Z” (an example of “first direction”), and the direction in which the medium M is transported is referred to as “transport direction F”. The scanning direction X, the longitudinal direction Y, and the vertical direction Z are directions intersecting each other (perpendicularly), and the transport direction F is a direction intersecting the scanning direction X (perpendicularly).

  The feeding unit 3 has a holding member 31 which rotatably holds a roll R on which the medium M is wound and stacked. The holding member 31 holds different types of media M and roll bodies R having different dimensions in the scanning direction X. Then, in the feeding unit 3, the medium M unwound from the roll R is fed toward the support 4 by rotating the roll R in one direction (clockwise direction in FIG. 1).

  The support portion 4 includes a first support portion 41, a second support portion 42, and a third support portion 43, which constitute a transport path of the medium M, from the upstream to the downstream in the transport direction F. The first support portion 41 guides the medium M delivered from the delivery portion 3 toward the second support portion 42, and the second support portion 42 supports the medium M on which printing is performed, and a third support portion 43 Guides the printed medium M downstream in the transport direction F.

  The transport unit 5 includes a transport roller 52 that applies a transport force to the medium M, a driven roller 53 that presses the medium M against the transport roller 52, and a rotation mechanism 51 that drives the transport roller 52. The transport roller 52 and the driven roller 53 are rollers having the scanning direction X as an axial direction.

  The conveyance roller 52 is disposed below the conveyance path of the medium M in the vertical direction Z, and the driven roller 53 is disposed above the conveyance path of the medium M in the vertical direction Z. The rotation mechanism 51 is configured by, for example, a motor and a reduction gear. Then, in the conveyance unit 5, the medium M is conveyed in the conveyance direction F by rotating the conveyance roller 52 in a state where the medium M is nipped by the conveyance roller 52 and the driven roller 53.

  As shown in FIGS. 2 and 3, the printing unit 6 includes a guide member 62 extending along the scanning direction X, a carriage 71 supported by the guide member 62 movably along the scanning direction X, and a carriage 71. A plurality of (five in the present embodiment) discharge heads 40 that are supported and discharge ink (liquid) onto the medium M and a moving mechanism 61 that moves the carriage 71 in the scanning direction X are provided.

  Further, the printing unit 6 is supported by the carriage 71, the drive circuit board 30, the control circuit board 20, the heat dissipation case 81 accommodating the drive circuit board 30 and the control circuit board 20, and the maintenance of the ejection heads 40. And a maintenance unit 91 that performs the

  The carriage 71 is a carriage cover 73 which forms a closed space by a carriage body 72 having an L-shaped cross section when viewed in the scanning direction X, and the carriage body 72 detachably attached to the carriage body 72. And A plurality of discharge heads 40 are supported at the lower part of the carriage 71 in a state of being arranged at equal intervals in the scanning direction X, and the lower end of each discharge head 40 protrudes from the lower surface of the carriage 71 to the outside. On the lower surface of each discharge head 40, a plurality of nozzles 651 from which the ink is discharged is opened in an arrayed state.

  Each ejection head 40 is a so-called inkjet head having pressure generating means (piezoelectric element) for ejecting ink for each nozzle 651, and the opening of each nozzle 651 is supported by the second support portion 42 in a state supported by the carriage 71. It is aimed at. The moving mechanism 61 includes a motor and a reduction gear, and converts the rotational force of the motor into a moving force in the scanning direction X of the carriage 71. Therefore, the carriage 71 reciprocates in the scanning direction X while supporting the plurality of ejection heads 40, the plurality of drive circuit boards 30, and the control circuit board 20 by driving the moving mechanism 61.

  As shown in FIG. 2 and FIG. 4, the front end portion of a rectangular parallelepiped heat dissipation case 81 accommodating each drive circuit board 30 and control circuit board 20 is fixed to the upper end portion of the rear portion of the carriage 71.

  The control circuit board 20 is supported by the carriage 71 via the heat dissipation case 81. A connector 29 is provided on the control circuit board 20.

  The control unit 2 and the connector 29 are connected via a cable 65. That is, the cable 65 electrically connects the control circuit board 20 supported by the carriage 71 reciprocatingly moving in the scanning direction X, and the control unit 2 fixed to the liquid discharge device 1. Therefore, the cable 65 is preferably configured by an FFC (Flexible Flat Cable) that deforms following the reciprocating movement of the carriage 71.

  Further, a plurality of drive circuit boards 30 are provided upright and arranged above the control circuit board 20 in the vertical direction Z. The control circuit board 20 and each drive circuit board 30 are connected by a B to B (Board to Board) connector 83.

  The plurality of drive circuit boards 30 are supported by the carriage 71 via the heat dissipation case 81. In detail, the plurality of drive circuit boards 30 are supported by the heat dissipation case 81 in a state of being arranged at equal intervals in the scanning direction X. At this time, the arrangement direction of the plurality of drive circuit boards 30 and the arrangement direction of the plurality of ejection heads 40 are the same.

  Each drive circuit board 30 is provided with FFC connectors 84 and 85 at its front end. Each of the FFC connectors 84 and 85 is exposed to the carriage 71 from the front surface of the heat dissipation case 81.

  One end of a cable 86 composed of an FFC or the like is detachably connected (retractable) to the FFC connector 84, and one end of a cable 87 composed of an FFC or the like is detachably connected to the FFC connector 85 Be done.

The discharge head 40 includes a discharge head main body 45 including a nozzle 651, and a connection substrate 74 provided on the upper surface of the discharge head main body 45. The discharge head main body 45 and the connection substrate 74 are connected via the BtoB connector 75. Further, the connection substrate 74 is provided with FFC connectors 76 and 77. The other end of the cable 86 is detachably connected to the FFC connector 76, and the other end of the cable 87 is detachably connected to the FFC connector 77. As a result, each drive circuit board 30 and each discharge head 40 are electrically connected via the cables 86 and 87.

  As shown in FIGS. 2 and 4, the guide member 62 has a guide rail portion 63 extending in the scanning direction X at its lower front surface. The carriage 71 is supported movably in the scanning direction X by a guide rail portion 63 at a carriage support portion 64 provided at the lower part of the rear surface. That is, the carriage support portion 64 is slidably coupled to the guide rail portion 63 in the scanning direction X. That is, the carriage 71 reciprocates along the scanning direction X while being guided by the guide rail portion 63 of the guide member 62 in the carriage support portion 64 by the drive of the moving mechanism 61.

  As shown in FIG. 3, the maintenance unit 91 is provided adjacent to the second support unit 42 in the scanning direction X. The maintenance unit 91 includes a cap 92 for capping the space where each nozzle 651 is opened as a closed space by contacting the discharge head 40. Capping is performed to suppress drying of the ink in each nozzle 651 of the ejection head 40. Capping is an example of maintenance and is not limited to this.

2. Configuration of Discharge Head The configuration of the discharge head 40 in the present embodiment will be described using FIGS. 5 to 7.

  FIG. 5 is an exploded perspective view of the discharge head 40. As shown in FIG. 5, the discharge head 40 includes a discharge head main body 45 and a connection substrate 74 provided above the discharge head main body 45 in the vertical direction Z (upper side in FIG. 5).

  The connection substrate 74 is provided with the FFC connectors 76 and 77 and the BtoB connector 75 as described above.

  The BtoB connector 75 is provided on the lower surface (lower in FIG. 5) of the connection substrate 74 in the vertical direction Z, and is connected to the discharge head main body 45.

  The FFC connectors 76 and 77 are provided on the upper surface in the vertical direction Z along the front-rear direction Y, which is a surface different from the surface on which the BtoB connector 75 of the connection substrate 74 is provided. The other end of the cable 86 is detachably connected to the FFC connector 76, and the other end of the cable 87 is detachably connected to the FFC connector 77, whereby the drive circuit board 30 and the ejection head 40 are connected. Are electrically connected.

  The discharge head main body 45 includes a holder 21 and a cover member 27.

  On both sides of the holder 21 in the front-rear direction Y, flange portions 22 are provided integrally with the holder 21. The flange portion 22 is fixed to the carriage body 72 (see FIG. 2) by a screw or the like.

  The cover member 27 is provided above the holder 21 in the vertical direction Z. The cover member 27 protects an ink flow path (not shown) provided inside the discharge head 40 for introducing the ink into the nozzle 651. Further, an opening 28 through which the BtoB connector 75 connected to the connection substrate 74 is inserted is provided above the cover member 27 in the vertical direction Z.

  FIG. 6 is an exploded perspective view of the discharge head 40 as viewed from the lower side in the vertical direction Z (the surface on which the nozzles 651 are formed).

  As shown in FIG. 6, the holder 21 of the discharge head 40 is provided with a fixing plate 23, a reinforcing plate 24, and a plurality of (four in the present embodiment) discharge modules 400.

  The holder 21 is made of a conductive material, such as metal, having a strength greater than that of the fixing plate 23. A storage portion 25 for storing a plurality of discharge modules 400 is provided on the surface of the holder 21 at the lower side (upper side in FIG. 6) in the vertical direction Z.

  The accommodation portion 25 has a concave shape that opens downward in the vertical direction Z, and accommodates the plurality of ejection modules 400 fixed by the fixing plate 23. At this time, the opening of the housing portion 25 is sealed by the fixing plate 23. That is, the discharge module 400 is accommodated in the space formed by the accommodation portion 25 and the fixing plate 23. Note that the storage unit 25 may be provided for each discharge module 400, or may be provided continuously across the plurality of discharge modules 400.

  A recess 26 having a concave shape to which the reinforcing plate 24 and the fixing plate 23 are fixed is provided on the surface of the holder 21 on which the housing portion 25 is provided. The reinforcing plate 24 and the fixing plate 23 are sequentially stacked on the bottom of the recess 26.

  The fixing plate 23 is formed of a plate-like member formed of a conductive material such as metal. Further, the fixing plate 23 is provided with an opening 23a penetrating in the vertical direction Z, which exposes a nozzle surface 651a on which the nozzle 651 of each ejection module 400 is provided. The openings 23 a are provided independently for each discharge module 400. The fixing plate 23 is fixed to the side of the nozzle surface 651 a of the ejection module 400 at the periphery of the opening 23 a.

  The reinforcing plate 24 is preferably made of a material having a strength higher than that of the fixing plate 23. In the reinforcing plate 24, an opening 24 a having an inner diameter larger than the outer periphery of the discharge module 400 corresponding to the discharge module 400 joined to the fixed plate 23 is provided to penetrate in the vertical direction Z. The discharge module 400 inserted into the opening 24 a of the reinforcing plate 24 is joined to the fixing plate 23.

  The fixed plate 23 and the holder 21 are mutually pressed by a predetermined pressure and joined while being supported by a support (not shown).

  FIG. 7 is a view showing a nozzle formation surface on which the nozzles 651 of the ejection head 40 are formed.

  As shown in FIG. 7, the ejection modules 400 are arranged in a staggered manner on the lower surface of the holder 21 in the vertical direction Z. In the ejection module 400, nozzles 651 for ejecting ink are arranged in parallel along the front-rear direction Y. Further, in the ejection module 400, two rows in the scanning direction X in which the nozzles 651 are arranged in parallel in the front-rear direction Y are provided. In the ejection module 400, 300 or more nozzles 651 per inch are arranged in parallel along the scanning direction X, and further, 600 or more nozzles 651 are provided in one ejection module 400. That is, the discharge head 40 in the present embodiment is provided with 2400 or more nozzles 651.

  Further, in the inside of the ejection module 400, a flow path communicating with the nozzle 651 and a pressure generation unit for causing a pressure change in the ink in the flow path are provided.

3. Configuration of Ejection Unit Here, the configuration of the flow path communicating with the nozzle 651 provided in the ejection module 400 and the configuration of the pressure generation unit for causing pressure change in the ink in the flow path will be described using FIG. FIG. 8 is a view showing a schematic configuration corresponding to one of the plurality of ejection units 600 including the plurality of nozzles 651 provided in the ejection module 400. As shown in FIG. As shown in FIG. 8, the discharge module 400 includes a discharge part 600 and a reservoir 641.

  Ink is introduced into the reservoir 641 from an ink cartridge (not shown) via the ink tube and the supply port 661. The reservoir 641 is provided for each ink color.

  The discharge unit 600 includes a piezoelectric element 60, a diaphragm 621, a cavity 631, and a nozzle 651. Among these, the diaphragm 621 is displaced by the piezoelectric element 60 provided on the upper surface in FIG. 8, and functions as a diaphragm that enlarges / reduces the internal volume of the cavity 631 filled with the ink. The nozzle 651 is an opening provided in the nozzle plate 632 and in communication with the cavity 631. The inside of the cavity 631 is filled with ink, and the displacement of the piezoelectric element 60 changes the internal volume. The nozzle 651 communicates with the cavity 631 and discharges the ink in the cavity 631 according to the change of the internal volume of the cavity 631.

  The piezoelectric element 60 shown in FIG. 8 functions as a pressure generating means, and has a structure in which the piezoelectric body 601 is sandwiched between a pair of electrodes 611 and 612. In the piezoelectric body 601 having this structure, the central portion bends in the vertical direction with respect to both end portions in FIG. 8 together with the electrodes 611 and 612 and the diaphragm 621 according to the voltage applied by the electrodes 611 and 612. The piezoelectric body 601 of the piezoelectric element 60 in the present embodiment has a film thickness of 1 μm or less.

  Specifically, a drive voltage Vout which is a voltage signal to be described later is supplied to the electrode 611 of the piezoelectric element 60, and a voltage VBS which is a voltage signal of a constant voltage to be described later is supplied to the electrode 612. The piezoelectric element 60 is configured to bend upward as the potential difference between the drive voltage Vout and the voltage VBS increases, and to deflect downward as the potential difference between the drive voltage Vout and the voltage VBS decreases. That is, the piezoelectric element 60 is displaced by the potential difference between the drive voltage Vout and the voltage VBS (an example of the “reference voltage signal”).

  Then, when the piezoelectric element 60 bends upward, the internal volume of the cavity 631 is expanded, and the ink is drawn from the reservoir 641. On the other hand, when it is bent downward, the internal volume of the cavity 631 is reduced. Thus, the internal volume of the cavity 631 changes as the piezoelectric element 60 is displaced. Ink is ejected from the nozzle 651 according to the change in the internal volume.

  The piezoelectric element 60 is not limited to the illustrated structure, and may be any type that can deform the piezoelectric element 60 and eject ink 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 in the discharge module 400 corresponding to the cavity 631 and the nozzle 651.

4. Electrical Configuration of Liquid Ejection Device The electrical configuration of the liquid ejection device 1 in the present embodiment will be described with reference to FIG. FIG. 9 is a block diagram showing the electrical configuration of the liquid ejection device 1. As shown in FIG. 9, the liquid discharge apparatus 1 includes a power supply circuit board 10, a control circuit board 20, a plurality of drive circuit boards 30-1 to 30-n, and a plurality of discharge heads 40-1 to 40-n. . Here, in the liquid discharge apparatus 1 according to the present embodiment, as described above, the control circuit board 20, the plurality of drive circuit boards 30-1 to 30-n, and the plurality of discharge heads 40-1 to 40-n It is supported by

  The plurality of drive circuit boards 30-1 to 30-n are all referred to as the drive circuit board 30 when the same configuration is provided and it is not necessary to distinguish them. The plurality of ejection heads 40-1 to 40-n are all referred to as the ejection head 40 if they have the same configuration and need not be distinguished. Further, in the present embodiment, the drive circuit boards 30-i (i = 1 to n) and the ejection heads 40-i are provided correspondingly.

  The power supply circuit board 10 is provided with a high voltage generation circuit 110. Also, the power supply circuit board 10 is electrically connected to the control circuit board 20 via the cable 65.

  The high voltage generation circuit 110 generates a voltage HVH which is a voltage signal of, for example, DC 42 V used in the liquid ejection device 1 based on a power supply voltage (for example, AC 100 V which is a commercial power supply) input from the outside of the liquid ejection device 1 Output to the control circuit board 20.

  Further, the power supply circuit board 10 transmits a signal input from a host computer outside the liquid discharge device 1 to the control circuit board 20. The power supply circuit board 10 is fixed to the liquid discharge device 1 together with the control unit 2 (see FIG. 1).

  The control circuit board 20 is provided with a control circuit 210, and is electrically connected to the drive circuit board 30 via a B to B connector 83.

  The control circuit 210 includes an ejection data generation circuit 211 and a drive data generation circuit 212, and when the host computer supplies various signals such as image data via the power supply circuit board 10, the drive circuit board 30 and the ejection head 40 to output various control signals and the like for controlling 40.

  Specifically, part of the signal input to the control circuit 210 is input to the ejection data generation circuit 211. Then, the ejection data generation circuit 211 generates plural types of control signals for controlling the ejection of the ink from the ejection unit 600 based on the input signal.

  More specifically, the ejection data generation circuit 211 selects a plurality (n) of print data signals SI1 to SIn for controlling which of the drive voltages COM-A and COM-B described later is selected, and the ejection unit 600. A plurality of (n) latch signals LAT1 to LATn for controlling the cycle of ink ejection are generated and output to the plurality (n) of drive circuit boards 30-1 to 30-n. At this time, the print data signal SIi and the latch signal LATi are input to the drive circuit substrate 30-i. The signals for controlling the discharge input to the drive circuit substrate 30 are referred to as a print data signal SI and a latch signal LAT.

  Furthermore, the ejection data generation circuit 211 outputs the clock signal Sck in common to the plurality of drive circuit boards 30-1 to 30-n.

  In addition, part of the signal input to the control circuit 210 is input to the drive data generation circuit 212. The drive data generation circuit 212 generates 2n pieces of drive data dA1 to dAn and dB1 to dBn, which are digital data that is the source of the drive voltage for driving the ejection unit 600, based on the input signal. It outputs to each of the drive circuit boards 30-1 to 30-n. At this time, m drive data dAi1 to dAim, dBi1 to dBim are input to the drive circuit board 30-i. The digital data that is the source of the drive voltage input to the drive circuit board 30 is referred to as drive data dA and dB.

  Here, the drive data dA1 to dAn, dB1 to dBn may be digital data obtained by analog / digital converting the waveform (drive waveform) of the drive voltage, and even if it is digital data indicating a difference with respect to the latest drive data. Good. Alternatively, it may be digital data defining the correspondence between the length of each section having a constant slope in the drive waveform and the slope.

  The control circuit board 20 is provided with a wiring pattern for branching the voltage HVH generated by the high voltage generation circuit 110, and outputs the voltage HVH to each of the plurality of drive circuit boards 30-1 to 30-n. That is, the control circuit board 20 also functions as a relay board for branching and transferring the voltage HVH.

  Here, the control circuit 210 provided on the control circuit board 20 may be provided on the power supply circuit board 10. Specifically, the print data signals SI1 to SIn, latch signals LAT1 to LATn, and drive data dA1 to dAn, dB1 to dBn generated by the control circuit 210 are input to the control circuit board 20 through the cable 65. It may be

  Furthermore, the signals transferred from the power supply circuit board 10 to the control circuit board 20 through the cable 65 are serial control signals in an LVDS (Low Voltage Differential Signaling) transfer mode, a LVPECL (Low Voltage Positive Emitter Coupled Logic) transfer mode, CML (Current Mode Logic) A differential signal used in a transfer method or the like may be used. At this time, the power supply circuit board 10 is provided with various signals to be transferred to the control circuit board 20 and a conversion circuit for converting into the differential signal, and the control circuit board 20 receives the differential input thereto. A recovery circuit is provided to recover the signal.

  The driving circuit substrate 30 (an example of a “substrate”) includes m driving circuits 311 (four in the present embodiment: four shown in FIG. 6) corresponding to each of the ejection modules 400 provided in the ejection head 40 (the fourth embodiment). A drive circuit 311-1 to 311-m), m drive circuits 312 (drive circuits 312-1 to 312-m), a voltage generation circuit 320, and capacitors 350 and 360 are provided. It is electrically connected to the discharge head 40 via 87.

  The drive data dA and the voltage HVH are input to each of the m drive circuits 311 (an example of the “amplifying circuit”). Then, each of the m drive circuits 311 is driven by a drive voltage COM-A (drive voltage COM-A1 to COM), which is a voltage signal based on the input drive data dA and the voltage HVH (an example of the "power supply voltage signal"). −Am) (an example of “drive signal”) is generated and output to the discharge head 40.

  Drive data dB and a voltage HVH are input to each of the m drive circuits 312 (another example of “amplifying circuit”). Then, each of the m drive circuits 312 is a drive voltage COM-B (drive voltages COM-B1 to COM-Bm) (“drive signal”) which is a voltage signal based on the input drive data dB and the voltage HVH. Another example is generated and output to the discharge head 40. The details of the drive circuits 311 and 312 will be described later.

  Here, the drive circuits 311-1 to 311-m and 312-1 to 312-m provided on the drive circuit substrate 30 are different only in the input data and the output voltage signal, and the circuit configuration is It may be identical. Further, the drive data generation circuit 212 generates drive data dA and dB corresponding to each of the m drive circuits 311 and m drive circuits 312, and the drive data generation circuit 212 generates m drive circuits 311 and m drive circuits 312. It may be configured to output each of them. Therefore, in the case where it is not necessary to distinguish in particular, the drive circuits 311-1 to 311-m will be referred to as the drive circuit 311 and the drive circuits 312-1 to 312-m will be referred to as the drive circuit 312.

The voltage generation circuit 320 generates a plurality of voltage signals having a plurality of voltage values based on the voltage HVH.

  Specifically, the voltage generation circuit 320 generates a voltage VBS (for example, DC 6 V) supplied to the piezoelectric element 60 provided in the ejection head 40 as a voltage signal, and outputs the voltage VBS to the ejection head 40. Further, the plurality of voltage generation circuits 320 generate, as voltage signals, voltages VDD (for example, DC 3.3 V) for supplying power supply voltages of various configurations provided in the ejection head 40 and output the voltages to the ejection head 40. Further, the plurality of voltage generation circuits 320 generate, as voltage signals, voltages GVDD (for example, DC 7.5 V) for driving the amplifiers included in the class D amplification circuits included in the drive circuits 311 and 312. Output to 312. The plurality of voltage generation circuits 320 may generate a plurality of voltage signals other than those described above.

  The capacitor 350 receives the voltage VBS output from the voltage generation circuit 320 and reduces the fluctuation of the potential of the voltage VBS supplied to the ejection head 40. In other words, the capacitor 350 stabilizes the potential of the voltage VBS. The ground potential (0 V) is input to the terminal to which the voltage VBS of the capacitor 350 is not supplied.

  Although only one capacitor 350 is shown in FIG. 9, it is preferable that the capacitor 350 for stabilizing the potential of the voltage VBS have a large capacity, and therefore, as shown in FIG. Capacitors 350 may be connected in parallel.

  The capacitor 360 receives the voltage HVH generated by the high voltage generation circuit 110 of the power supply circuit board 10, and reduces variation in the potential of the voltage HVH supplied to the drive circuits 311 and 312. In other words, the capacitor 360 stabilizes the potential of the voltage HVH. The ground potential (0 V) is input to the terminal to which the voltage HVH of the capacitor 350 is not supplied.

  Although only one capacitor 360 is shown in FIG. 9, it is preferable that the capacitor 360 for stabilizing the potential of the voltage HVH have a large capacity, and therefore, as shown in FIG. Capacitors 360 may be connected in parallel.

  Further, the drive circuit substrate 30 transfers the print data signal SI, the latch signal LAT, and the clock signal Sck input from the discharge data generation circuit 211 to the discharge head 40.

  Here, the drive circuit substrate 30 and the ejection head 40 are electrically connected via the cable 86 and the cable 87 as described above. Among them, the cable 86 transfers the drive voltages COM-A and COM-B and the voltages VDD, VBS and HVH from the drive circuit substrate 30 to the ejection head 40, and the cable 86 transmits the print data signal SI, the latch signal LAT and the clock. Transfer the signal Sck.

  As described above, the cable 87 for transferring the print data signal SI, the latch signal LAT and the clock signal Sck, which controls the discharge based on the voltage of several mV, and the drive voltages COM-A and COM-B which are voltage signals of several V or more. By transferring the voltages VDD, VBS, and HVH via the different FFC cables to the cables 86 for transferring the voltages VDD, VBS and HVH, respectively, interference between the signals can be reduced.

  The ejection head 40 includes a plurality of ejection modules 400.

  Each of the plurality of ejection modules 400 includes a drive signal selection circuit 410 and a plurality of ejection units 600.

  The drive signal selection circuit 410 includes a selection control circuit 420 and a plurality of selection circuits 430. The drive signal selection circuit 410 is formed of, for example, an IC (Integrated Circuit), and operates with the voltage VDD.

  The selection control circuit 420 receives the print data signal SI, the latch signal LAT, and the clock signal Sck.

  Selection control circuit 420 is a selection signal for controlling which of drive voltages COM-A and COM-B should be selected (or not selected at all) for each of a plurality of selection circuits 430. Is generated based on the print data signal SI, and is output based on the printing cycle determined by the latch signal LAT.

  The drive voltages COM-A and COM-B generated by the drive circuits 311 and 312 are input to the selection circuits 430, respectively. Then, according to the selection signal output from the selection control circuit 420, one of the drive voltages COM-A and COM-B to be input is selected and output to the corresponding ejection unit 600 as the drive voltage Vout. Then, the drive voltage Vout is applied to one end of the piezoelectric element 60.

  At this time, the voltage HVH is also input to the selection circuit 430. The selection circuit 430 selects the high-voltage drive voltages COM-A and COM-B amplified based on the voltage HVH in the drive circuits 311 and 312, and outputs the selected drive voltages as the drive voltage Vout. Therefore, selection circuit 430 more reliably selects drive voltages COM-A and COM-B by controlling which of drive voltages COM-A and COM-B is selected using voltage HVH. be able to.

  As described above, the drive signal selection circuit 410 selects the drive voltages COM-A and COM-B to be input, and supplies them to the piezoelectric element 60 as the drive voltage Vout. In other words, the drive signal selection circuit 410 controls the supply of the drive voltages COM-A and COM-B to the piezoelectric element 60.

  Each of the plurality of ejection units 600 includes a piezoelectric element 60, and is provided corresponding to each of the selection circuits 430. The drive voltage Vout output from the selection circuit 430 is applied to one end of the piezoelectric element 60, and the voltage VBS is applied to the other end. Then, the piezoelectric element 60 is displaced due to the potential difference between the drive voltage Vout and the voltage VBS, and the ink is ejected from the ejection unit 600 (nozzle 651) based on the displacement.

5. Configuration of Drive Circuit Next, drive circuits 311 and 312 for generating the drive voltages COM-A and COM-B will be described. The drive circuit 311 firstly converts the drive data dA into an analog signal, and secondly feeds back the output drive voltage COM-A, and a signal (attenuation signal) based on the drive voltage COM-A and a target signal. Is corrected with the high frequency component of the drive voltage COM-A, and the modulation signal is generated according to the corrected signal. Then, the drive circuit 311 thirdly generates an amplified modulated signal by switching a transistor in accordance with the modulated signal, and fourth, smoothes (demodulates) the amplified modulated signal with a low pass filter, The smoothed signal is output as the drive voltage COM-A. The drive circuit 312 has a similar configuration, and differs only in that the drive voltage COM-B is output from the drive data dB. Therefore, in the following description, only the drive circuit 311 will be described, and the description of the drive circuit 312 will be omitted.

  FIG. 10 is a diagram showing a circuit configuration of the drive circuit 311. As shown in FIG. As shown in FIG. 10, the drive circuit 311 includes an amplification control signal generation circuit 500, an output circuit 550, a first feedback circuit 570, a second feedback circuit 572 and a plurality of other circuit elements.

  The amplification control signal generation circuit 500 includes a DAC (Digital to Analog Converter) 511, a modulation unit 510, a gate driver 520, and a reference voltage generation unit 580.

  The amplification control signal generation circuit 500 is formed of an integrated circuit electrically connected to the outside through a terminal including a terminal In, a terminal Bst, a terminal Hdr, a terminal Sw, a terminal Gvd, a terminal Ldr, and a terminal Gnd. The input drive data dA is modulated by the modulation unit 510, and an amplification control signal for driving the respective gates of the first transistor M1 and the second transistor M2 described later is output.

  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 DAC 511 with the first reference voltage DAC_HV. The first reference voltage DAC_HV and the second reference voltage DAC_LV may be generated as the voltage signal in the amplification control signal generation circuit 500 after being generated by the voltage generation circuit 320 (FIG. 9).

  The DAC 511 converts the drive data dA defining the waveform of the drive voltage COM-A into an analog drive control signal Aa of the voltage between the first reference voltage DAC_HV and the second reference voltage DAC_LV, and is included in the modulation unit 510. It supplies to the input end (+) of the adder 512.

  The maximum and minimum values of the voltage amplitude of drive control signal Aa are determined by first reference voltage DAC_HV and second reference voltage DAC_LV (for example, about 1 to 2 V), and those obtained by amplifying this voltage are driven. It becomes voltage COM-A. That is, the drive control signal Aa is a target signal before amplification of the drive voltage COM-A.

  The modulation unit 510 outputs a modulation signal Ms obtained by modulating the drive control signal Aa (drive data dA) to the output circuit 550 via the gate driver 520. The modulation unit 510 includes adders 512 and 513, a comparator 514, an inverter 515, an integral attenuator 516 and an attenuator 517.

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

  The voltage of the drive control signal Aa is input to the input terminal (+) of the adder 512, and the voltage output from the integrating attenuator 516 is input to the input terminal (-). Then, the adder 512 subtracts the voltage input to the input end (−) from the voltage input to the input end (+) and supplies the signal Ab of the integrated voltage to the input end (+) of the adder 513 .

  Here, while the maximum of the voltage amplitude of the drive control signal Aa is about 2 V, the voltage of the drive voltage COM-A may exceed 40 V at the maximum. For this reason, the integral attenuator 516 attenuates the drive voltage COM-A in order to match the amplitude ranges of both voltages in order to obtain the deviation.

  The attenuator 517 supplies to the input end (−) of the adder 513 a voltage obtained by attenuating the high frequency component of the drive voltage COM-A input through the terminal Ifb.

The signal Ab output from the adder 512 is input to the input terminal (+) of the adder 513, and the voltage output from the attenuator 517 is input to the input terminal (-). Then, the adder 513 outputs, to the comparator 514, a voltage signal As obtained by subtracting the voltage input to the input terminal (-) from the voltage input to the input terminal (+).

  Thus, the voltage signal As output from the adder 513 subtracts the voltage of the signal supplied to the terminal Vfb from the voltage of the drive control signal Aa, and further subtracts the voltage of the signal supplied to the terminal Ifb Voltage. For this reason, the voltage of the voltage signal As output from the adder 513 is the drive obtained by subtracting the attenuation voltage of the drive voltage COM-A output from the terminal Out from the voltage of the target drive control signal Aa It can be said that the signal is corrected by the high frequency component of the voltage COM-A.

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

  The modulation signal Ms changes in frequency and duty ratio in accordance with the drive data dA (drive control signal Aa). Therefore, the amount of change in the frequency or the duty ratio is adjusted by adjusting the modulation gain (sensitivity) by the attenuator 517.

  The modulation signal Ms output from the comparator 514 is supplied to the first gate driver 521 included in the gate driver 520. The modulation signal Ms is also supplied to the second gate driver 522 included in the gate driver 520 via logic inversion by the inverter 515. Therefore, the signals supplied to the first gate driver 521 and the second gate driver 522 have an exclusive relationship with each other.

  The logic levels of the signals supplied to the first gate driver 521 and the second gate driver 522 do not actually become H level at the same time (so that the first transistor M1 and the second transistor M2 are not simultaneously turned on) , Timing may be controlled. For this reason, the term "exclusively" as used herein means, strictly speaking, that H level does not simultaneously occur (the first transistor M1 and the second transistor M2 are not simultaneously turned on).

  By the way, although the modulation signal mentioned here is the modulation signal Ms in a narrow sense, if it is considered to be pulse modulation according to the analog drive control signal Aa based on the digital drive data dA, the modulation signal Ms is not A signal is also included in the modulation signal. That is, the modulation signal output from the modulation unit 510 includes not only the modulation signal Ms but also the one obtained by inverting the logic level of the modulation signal Ms and the one whose timing is controlled.

  The gate driver 520 includes a first gate driver 521 and a second gate driver 522.

The first gate driver 521 shifts the level of the modulation signal Ms output from the comparator 514 and outputs the result as a first amplification control signal from the terminal Hdr. Among the power supply voltages of the first gate driver 521, the high side is a voltage applied through the terminal Bst, and the low side is a voltage applied through the terminal Sw. The terminal Bst is connected to one end of the capacitor C5 and the cathode electrode of the diode D1 for backflow prevention. The terminal Sw is connected to the other end of the capacitor C5. The anode electrode of the diode D1 is connected to the terminal Gvd, and the voltage GVDD (for example, 7.5 V) supplied from the voltage generation circuit 320 (see FIG. 9) is applied. Therefore, the potential difference between the terminals Bst and Sw is approximately equal to the potential difference between the both ends of the capacitor C5, that is, the voltage GVDD (for example, 7.5 V). Then, the first gate driver 521 outputs a voltage larger than the terminal Sw by the voltage GVDD as a first amplification control signal from the terminal Hdr in accordance with the input modulation signal Ms.

  The second gate driver 522 operates at a lower potential than the first gate driver 521. The second gate driver 522 shifts the level of the signal obtained by inverting the modulation signal Ms output from the comparator 514 by the inverter 515, and outputs the signal as a second amplification control signal from the terminal Ldr. The voltage GVDD is applied to the high side of the power supply voltage of the second gate driver 522, and the ground potential (0 V) is applied to the low side via the terminal Gnd. Then, according to the signal input to the second gate driver 522, a voltage larger than the terminal Gnd by the voltage GVDD is output from the terminal Ldr as a second amplification control signal.

  The output circuit 550 includes a first transistor M1, a second transistor M2, and a low pass filter 560.

  A voltage HVH (for example, 42 V) is applied to the drain of the first transistor M1. The gate of the first transistor M1 is connected to one end of the resistor R1, and the other end of the resistor R1 is connected to the terminal Hdr of the amplification control signal generation circuit 500. The source of the first transistor M1 is connected to the terminal Sw of the amplification control signal generation circuit 500.

  The drain of the second transistor M2 is connected to the source of the first transistor M1. The gate of the second transistor M2 is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the terminal Ldr of the amplification control signal generation circuit 500. The source of the second transistor M2 is connected to the ground potential.

  In the first transistor M1 and the second transistor M2 connected as described above, when the first transistor M1 is off and the second transistor M2 is on, the voltage of the terminal Sw is the ground potential, and the voltage GVDD is applied to the terminal Bst. Applied. On the other hand, when the first transistor M1 is on and the second transistor M2 is off, the voltage of the terminal Sw is the voltage HVH, and the voltage HVH + GVDD (for example, 49.5 V) is applied to the terminal Bst.

  That is, the first gate driver 521 for driving the first transistor M1 uses the capacitor C5 as a floating power supply, and the potential of the terminal Sw (low potential side) is 0 V or a voltage according to the operation of the first transistor M1 and the second transistor M2. Change to HVH. Then, the first gate driver 521 sets the gate of the first transistor M1 to the first amplification control signal whose L level is near the voltage HVH (for example 42 V) and H level is near the voltage HVH + voltage GVDD (for example 49.5 V). Output.

  On the other hand, the second gate driver 522 for driving the second transistor M2 is fixed at the potential of the terminal Gnd regardless of the operation of the first transistor M1 and the second transistor M2, so that the L level is near 0 V and the H level is The second amplification control signal near the voltage GVDD is output.

  As described above, the modulation signal Ms in which the drive data dA is modulated by the first transistor M1 and the second transistor M2 is amplified to generate an amplified modulation signal.

  At this time, the amplification modulation signal is applied to one end of the inductor L1 included in the low pass filter 560 through a node to which the source of the first transistor M1 and the drain of the second transistor M2 are connected.

  The first transistor M1 and the second transistor M2 function as an amplification circuit that generates an amplified modulation signal obtained by amplifying the modulation signal Ms.

  The low pass filter 560 smoothes the amplified modulation signal output from the amplifier circuit (the first gate driver 521 and the second gate driver 522) to generate the drive voltage COM-A, and outputs the drive voltage COM-A. The low pass filter 560 includes an inductor L1 and a capacitor C1.

  One end of the inductor L1 is connected to a node to which the source of the first transistor M1 and the drain of the second transistor M2 are connected, and the other end is connected to a terminal Out which is an output of the drive circuit 311. Then, the drive voltage COM-A is output. The terminal Out is also connected to one end of the capacitor C1, and the other end of the capacitor C1 is connected to the ground potential.

  As described above, the driving voltage COM-A is generated by the inductor L1 and the capacitor C1 smoothing (demodulating) the amplification modulation signal applied to the node to which the first transistor M1 and the second transistor M2 are connected. Be done.

  The first feedback circuit 570 includes a resistor R3 and a resistor R4. One end of the resistor R3 is connected to the terminal Out, and the other end is connected to the terminal Vfb and one end of the resistor R4. The voltage HVH is applied to the other end of the resistor R4. As a result, the drive voltage COM-A that has passed through the first feedback circuit 570 from the terminal Out is pulled up to the terminal Vfb and is fed back as a signal.

  The second feedback circuit 572 includes capacitors C2, C3 and C4 and resistors R5 and R6.

  One end of the capacitor C2 is connected to the terminal Out, and the other end is connected to one end of the resistor R5 and one end of the resistor R6. The other end of the resistor R5 is connected to the ground potential. Thus, the capacitor C2 and the resistor R5 function as a high pass filter. The cutoff frequency of the high pass filter is set to, for example, about 9 MHz.

  The other end of the resistor R6 is connected to one end of the capacitor C4 and one end of the capacitor C3. The other end of the capacitor C3 is grounded. Thus, the resistor R6 and the capacitor C3 function as a low pass filter. The cutoff frequency of the LPF is set to, for example, about 160 MHz.

  By configuring the high pass filter and the low pass filter in this manner, the high pass filter functions as a band pass filter that passes a predetermined frequency range of the drive voltage COM-A.

  The other end of the capacitor C4 is connected to the terminal Ifb of the amplification control signal generation circuit 500. As a result, of the high frequency components of the drive voltage COM-A that has passed through the second feedback circuit 572 functioning as a band pass filter, the signal returns to the terminal Ifb as a signal in which the direct current component is cut.

  The drive voltage COM-A output from the terminal Out is a signal obtained by smoothing the amplification modulation signal by the low pass filter 560. The drive voltage COM-A is integrated / subtracted via the terminal Vfb and fed back to the adder 512. Therefore, self-oscillation occurs at a frequency determined by the feedback delay and the transfer function of the feedback.

  However, when the delay amount of the feedback path via the terminal Vfb is large, the frequency of the self-oscillation can not be made high enough to ensure the accuracy of the drive voltage COM-A only by feedback via the terminal Vfb. There is. Therefore, by providing a path for feeding back the high frequency component of the drive voltage COM-A via the terminal Ifb separately from the path via the terminal Vfb, the delay in the entire circuit is reduced. Therefore, the frequency of the voltage signal As is high enough to ensure the accuracy of the drive voltage COM-A as compared with the case where there is no path through the terminal Ifb.

  FIG. 11 is a diagram showing the waveforms of the voltage signal As and the modulation signal Ms in association with the waveform of the analog drive control signal Aa.

  As shown in FIG. 11, the voltage signal As is a triangular wave, and its oscillation frequency fluctuates according to the voltage of the drive control signal Aa. Specifically, it is highest when the voltage is at an intermediate value and becomes lower as the voltage becomes higher or lower from the intermediate value.

  The slope of the triangular wave of the voltage signal As is substantially equal between the rise and fall of the voltage if the voltage is near the middle value. Therefore, the duty ratio of the modulation signal Ms obtained by comparing the voltage signal As with the threshold values Vth1 and Vth2 by the comparator 514 is approximately 50%. In addition, when the voltage of the voltage signal As increases from an intermediate value, the downward slope of the voltage signal As becomes loose. Therefore, the period in which the modulation signal Ms is at the H level is relatively long, and the duty ratio of the modulation signal Ms is large. In addition, when the voltage of the voltage signal As decreases from an intermediate value, the upward slope of the voltage signal As becomes loose. As a result, the period in which the modulation signal Ms becomes H level becomes relatively short, and the duty ratio of the modulation signal Ms becomes small.

  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 H level, and turns it off if the modulation signal Ms is at L level. On the other hand, the second gate driver 522 turns on / off the second transistor M2 based on the logic inversion signal of the modulation signal Ms. That is, the second gate driver 522 turns off the second transistor M2 if the modulation signal Ms is at H level, and turns on if the modulation signal Ms is at L level.

  Therefore, the voltage of the drive voltage COM-A obtained by smoothing the amplification modulation signal at the terminal SW2 by the inductor L1 and the capacitor C1 increases as the duty ratio of the modulation signal Ms increases, and decreases as the duty ratio decreases. Therefore, the drive voltage COM-A is controlled to be a signal obtained by expanding the voltage of the drive control signal Aa obtained by converting the digital drive data dA into an analog signal.

  Since this drive circuit 311 uses pulse density modulation, there is an advantage that a large change width of the duty ratio can be obtained for pulse width modulation with a fixed modulation frequency.

  The minimum positive pulse width and negative pulse width that can be used in the drive circuit 311 are limited by the circuit characteristics. Therefore, in pulse width modulation with fixed frequency, only a predetermined range can be secured as the change width of the duty ratio. On the other hand, in pulse density modulation, the oscillation frequency decreases as the voltage of the voltage signal As deviates from the intermediate value, and the duty ratio can be further increased in the region where the voltage is high. In the low region, the duty ratio can be made smaller. Therefore, in the self-oscillation type pulse density modulation, a wider range can be secured as the change width of the duty ratio.

6. Configuration of Drive Circuit Board Here, the arrangement of components and circuits to be mounted on the drive circuit board 30 on which the drive circuits 311 and 312 are mounted will be described with reference to FIGS. 12 and 13.

  FIG. 12 is a plan view for explaining the arrangement of components and circuits mounted on the drive circuit board 30. As shown in FIG. FIG. 13 is a side view for explaining the arrangement of components and circuits mounted on the drive circuit substrate 30. As shown in FIG. In FIG. 12, the arrangement of components and circuits arranged on the surface 321 (front surface) of the drive circuit board 30 as viewed from the front surface side of the drawing is indicated by solid lines, and is disposed on the surface 322 (back surface) The parts and circuits that have been

  12 and 13 show the scanning direction X, the longitudinal direction Y, and the vertical direction Z as the directions (see FIGS. 13 and 14) when the drive circuit board 30 is mounted on the liquid ejection device 1. It shows.

  As shown in FIG. 12, the drive circuit board 30 has a pair of sides 331 (an example of “first side”) and sides 332 (an example of “second side”) facing in the vertical direction Z, and in the front-rear direction Y The plane shape has a substantially rectangular shape including a pair of opposite sides 333 and sides 334.

  A plurality of drive circuits 311 and 312 are juxtaposed from the side 333 to the side 334 (the front-rear direction Y) in the central region between the opposing side 331 and the side 332 of the drive circuit substrate 30. The plurality of drive circuits 311 and 312 may be provided on any one of the surface 321 and the surface 322 of the drive circuit substrate 30. In the present embodiment, as described later, it is provided on the surface 322 on the back side.

  In the region between the drive circuits 311 and 312 and at least one of the sides 331 and 332 of the drive circuit substrate 30, at least one of the capacitor 350 and the capacitor 360 is the side 333 to the side 334. They are juxtaposed in the (front-rear direction Y).

  In the present embodiment, a plurality of capacitors 350 are juxtaposed in the front-rear direction Y in the region between the drive circuits 311 and 312 and the side 331, and in the region between the drive circuits 311 and 312 and the side 332, A plurality of capacitors 360 are juxtaposed in the front-rear direction Y.

  As the capacitor 350 and the capacitor 360, capacitor elements having a height greater than that of the drive circuits 311 and 312 are often used. That is, the lengths of the capacitors 350 and 360 in the scanning direction X are larger than the lengths of the drive circuits 311 and 312 in the scanning direction X.

  As described above, by arranging the components and the circuit mounted on the drive circuit substrate 30, it is possible to improve the heat dissipation of the drive circuit substrate 30.

  Specifically, as shown in FIG. 12, a plurality of capacitors 350, a plurality of capacitors 360, and a BtoB connector 83 are provided on one surface 321 (an example of the “second surface”) of the drive circuit substrate 30; FFC connectors 84, 85 are provided. In addition, a plurality of drive circuits 311 and 312 are provided on the other surface 322 (an example of the “first surface”) of the drive circuit substrate 30.

A plurality of capacitors 350 are juxtaposed from the side 333 to the side 334 along the region between the drive circuits 311 and 312 arranged side by side and the side 331 in the drive circuit substrate 30, preferably along the side 331. A plurality of (6) are provided. The capacitor 350 functions as a capacitor for stabilizing the voltage VBS generated by the voltage generation circuit 320 provided on the drive circuit substrate 30 as described above (see FIG. 9). The number of capacitors 350 arranged in parallel along the side 331 is not limited to six.

  The voltage VBS is supplied to the piezoelectric element 60. Therefore, the current generated when the voltage VBS is supplied to the piezoelectric element 60 fluctuates depending on the number of piezoelectric elements 60 to which the voltage VBS is supplied and the drive voltage Vout. Then, the potential of the voltage VBS may be changed due to the change of the current. Capacitor 350 functions as a smoothing element for reducing such fluctuation of voltage VBS.

  A plurality of capacitors 360 are juxtaposed from the side 333 to the side 334 along the region between the drive circuits 311 and 312 and the side 332, preferably along the side 332, in the drive circuit substrate 30. A plurality of (four) are provided. In summary, the capacitor 350, the driver circuits 311 and 312, and the capacitor 360 are arranged in parallel from the side 333 to the side 334. The capacitor 360 is a capacitor for stabilizing the voltage HVH used in the drive circuits 311 and 312 as described above (see FIG. 9). Further, the number of capacitors 360 provided side by side along the side 332 is not limited to four.

  The voltage HVH is supplied to the drive circuits 311 and 312. The drive circuits 311 and 312 generate drive voltages COM-A and COM-B based on the supplied voltage HVH. The drive voltages COM-A and COM-B generated by the drive circuits 311 and 312 are supplied to the piezoelectric element 60 as the drive voltage Vout by the selection operation of the selection circuit 430. At this time, the current generated when the drive voltages COM-A and COM-B are supplied to the piezoelectric element 60 as the drive voltage Vout is the number of piezoelectric elements 60 to which the drive voltages COM-A and COM-B are supplied. It fluctuates by Then, the potential of the voltage HVH that contributes to the generation of the drive voltages COM-A and COM-B may fluctuate with the fluctuation of the current. Capacitor 360 functions as a smoothing element for reducing such fluctuation of voltage HVH.

  As described above, the plurality of capacitors 350 function as smoothing elements for stabilizing the voltage VBS, and the capacitors 360 function as smoothing elements for stabilizing the voltage HVH. Therefore, it is preferable that the capacitors 350 and 360 have large capacitances in order to secure stable potentials of the voltage VBS and the voltage HVH in a wide range of output current. Therefore, in the present embodiment, by providing a plurality of each of the capacitors 350 and the capacitors 360 in the drive circuit substrate 30, a large capacity is secured.

  At this time, as shown in FIG. 13, the heights H 1 of the plurality of capacitors 350 are smaller than the heights H 2 of the plurality of capacitors 360. The voltage VBS whose potential fluctuation is reduced by the capacitor 350 is, as described above, a low voltage voltage signal of DC 6 V, for example. On the other hand, the voltage HVH whose potential fluctuation is reduced by the capacitor 360 is, as described above, a high voltage voltage signal of, for example, 42 V DC. Therefore, with respect to capacitor 350 for stabilizing voltage VBS, capacitor 360 for stabilizing voltage HVH is required to have a large withstand voltage. Thus, the large withstand voltage capacitor 360 is larger than the small withstand voltage capacitor 350.

  Each of the capacitor 350 and the capacitor 360 is preferably an electrolytic capacitor having a large capacity, and is formed of, for example, an aluminum electrolytic capacitor, a tantalum electrolytic capacitor, or the like.

Here, in the present embodiment, any of the plurality of capacitors 350 (a plurality of first elements) and the plurality of capacitors 360 (a plurality of second elements) described above is an example of the “plural elements” in the present invention. It is.

  Referring back to FIG. 12, the BtoB connector 83 is provided on the side 332 of the drive circuit board 30 to electrically connect the control circuit board 20 and the drive circuit board 30. At this time, the BtoB connector 83 may be provided between the capacitors 360 arranged in parallel.

  The FFC connectors 84 and 85 are provided on the side 334 of the drive circuit board 30, and are electrically connected to the ejection head 40 via the cable 86 and the cable 87.

  Further, as described above, the drive circuits 311 and 312 are provided in parallel on the surface 322 of the drive circuit substrate 30.

  Specifically, the drive circuits 311 and 312 are juxtaposed so that the drive circuits 311 and the drive circuits 312 are alternately positioned from the side 333 to the side 334 in the central region of the drive circuit substrate 30.

  At this time, the number of combinations of the drive circuit 311 and the drive circuit 312 is equal to the number of ejection modules 400 provided in the ejection head 40 electrically connected to the drive circuit substrate 30. For example, when four ejection modules 400 are provided in the ejection head 40 as shown in FIG. 7, four driving circuits 311 and 4 are provided on the drive circuit board 30 electrically connected to the ejection head 40. A total of eight drive circuits, one drive circuit 312, are alternately arranged in parallel.

  At this time, in the central region, drive circuits 311 and 312 juxtaposed to drive circuit board 30 are juxtaposed along capacitors 331 and sides 332 juxtaposed along side 331 when viewed from surface 321. Preferably, they are provided so as not to overlap with the respective capacitors 360.

  The central region is a region including the centers of the sides 331 and 332 facing each other in the vertical direction Z, and for example, the capacitors 350 arranged along the sides 331 and the sides 332 are parallel to each other. It may be an area between the capacitor 360 and the capacitor.

  As described above (see FIG. 10), each of drive circuits 311 and 312 performs analog conversion of drive data dA and dB and corrects the converted signal from amplification control signal generation circuit 500, and amplification control signal generation circuit 500. And an output circuit 550 that generates the drive voltages COM-A and COM-B by amplifying the output signal based on the voltage HVH and smoothing the amplified signal. Also, the output circuit 550 includes an inductor L1 and a first transistor M1 and a second transistor M2.

  In such drive circuits 311 and 312, as described above (see FIG. 10), the first transistor M1, the second transistor M2, and the inductor L1 included in the output circuit 550 are large based on the high voltage voltage HVH. A current flows. Therefore, large heat may be generated in the first transistor M1, the second transistor M2, and the inductor L1. Therefore, in order to improve heat dissipation, the first transistor M1, the second transistor M2, and the inductor L1 are often configured as relatively large parts in the drive circuits 311 and 312.

  Here, the height H3 of the drive circuits 311 and 312 shown in FIG. 13 is the height of the largest component among the components constituting the drive circuits 311 and 312, and in the present embodiment, The height of one of the transistor M1, the second transistor M2, and the inductor L1 corresponds to one another.

  The heat generated by the drive circuits 311 and 312 is discharged by radiation from the surfaces of the components constituting the drive circuits 311 and 312 and radiation via the mounted drive circuit board 30.

  As shown in FIG. 13, the drive circuit substrate 30 is provided with capacitors 350 and 360 that are larger than the drive circuits 311 and 312 in height. Therefore, the flow of heat generated in the drive circuits 311 and 312 is blocked by large components including the large capacitor 350 and the capacitor 360 and retained in the drive circuit board 30, thereby performing sufficient heat dissipation. There is no possibility.

  Further, even in the case where cooling is performed using the air flow generated by the cooling means or the like in the drive circuits 311 and 312 and the drive circuit board 30, the air flow is blocked by the capacitors 350 and 360 or the like having a large height. Thus, there is a possibility that sufficient cooling of the drive circuits 311 and 312 and the drive circuit board 30 can not be performed.

  In the present embodiment, as described above, the drive circuits 311 and 312 and the capacitors 350 and 360 having large heights are arranged in parallel in the same direction from the side 333 to the side 334. Therefore, in the drive circuit substrate 30, a path is formed in which the flow of heat generated in the drive circuits 311 and 312 is not easily blocked by the capacitors 350 and 360 having a large height in the direction from the side 333 toward the side 334. Therefore, the heat generated by the drive circuits 311 and 312 is efficiently discharged through the path. That is, in the drive circuit board 30, the risk of heat retention is reduced, and the heat dissipation efficiency of the drive circuit board 30 is improved.

  Furthermore, in the present embodiment, the capacitors 350 are juxtaposed along the side 331, and the capacitors 360 are juxtaposed along the side 332. That is, in the central region of the drive circuit board 30, the paths where heat is difficult to be shielded by the capacitors 350 and 360 are widely provided. Therefore, the heat dissipation efficiency of the drive circuit board 30 is further improved.

  The first transistor M1 and the second transistor M2 included in the drive circuits 311 and 312 may be formed of a metal package in order to efficiently release the generated heat from the component surface, and the drive circuit board 30 In order to efficiently dissipate (transfer) heat, it may be composed of surface mounted components and the like.

  Here, an embodiment in the case where the drive circuit substrate 30 described above is mounted on the liquid discharge device 1 will be described with reference to FIGS. 14 and 15. FIG. 14 is a side view showing a state in which the drive circuit board 30 and the ejection head 40 are mounted on the liquid ejection device 1. FIG. 15 is a front view showing the liquid discharge apparatus 1 with the drive circuit board 30 and the discharge head 40 mounted.

  As shown in FIG. 14, in the heat dissipation case 81 supported by the carriage 71, the drive circuit board 30 is provided such that the side 331 is above the vertical direction Z, and the side 332 is below the vertical direction Z Provided as. At this time, the BtoB connector 83 provided on the side 332 and the control circuit board 20 are electrically connected. That is, the drive circuit board 30 is erected above the control circuit board 20 in the vertical direction Z such that the side 331 and the side 332 face each other in the vertical direction Z.

The drive circuit substrate 30 is provided such that the side 334 is on the discharge head 40 side in the front-rear direction Y, and the side 333 faces the side 334 in the front-rear direction Y. Then, the FFC connectors 84 and 85 provided along the side 334 and the FFC connectors 76 and 76 provided on the ejection head 40 supported by the carriage main body 72 are cables 86 and 8 respectively.
Connected via 7 Thus, the drive circuit board 30 and the ejection head 40 provided to be separated in the front-rear direction Y of the drive circuit board 30 are electrically connected via the cables 86 and 87.

  In the drive circuit board 30 provided as described above, the capacitors 350 are juxtaposed along the side 331 above the vertical direction Z of the drive circuit board 30, and the capacitors 360 are in the vertical direction Z of the drive circuit board 30. It is juxtaposed along the lower side 332. That is, a path in which the heat is not easily blocked by the capacitors 350 and 360 is formed along the longitudinal direction Y. In FIG. 14 and FIG. 15, the route is illustrated as a route Fp.

  Furthermore, in the liquid discharge device 1, a plurality of sets of such drive circuit substrate 30 and discharge head 40 are arranged in parallel along the scanning direction X, as shown in FIG. At this time, the surfaces 321 and the surfaces 322 of the plurality of drive circuit substrates 30 are provided in the same direction in the scanning direction X. Specifically, one surface 321 and the other surface 322 of two adjacent drive circuit substrates 30 of the plurality of drive circuit substrates 30 arranged in parallel face each other.

  A path Fp is formed on each surface 321 of the plurality of drive circuit boards 30 arranged in parallel. A plurality of drive circuit boards 30 are provided such that the surfaces 321 of the individual drive circuit boards 30 face the surfaces 322 of the adjacent drive circuit boards 30 along the scanning direction X. At this time, paths Fp formed along the front-rear direction Y are provided in parallel in the scanning direction X on the surface 321 side of each drive circuit substrate 30. That is, each drive circuit board 30 forms a path Fp on the side of the surface 321, and a path Fp formed in the adjacent drive circuit board 30 is located on the side of the side 322.

  The plurality of drive circuit boards 30 provided in this manner is a plane 321 of the drive circuit board 30 by the paths Fp formed on the drive circuit board 30 and the paths Fp formed on the adjacent drive circuit board 30. It is possible to improve the heat radiation efficiency and the cooling efficiency of the drive circuit board 30 and the drive circuits 311 and 312 on both the side and the surface 322 side.

  Therefore, even when capacitors 350 and 360 are provided on surface 321 of drive circuit substrate 30 and drive circuits 311 and 312 are provided on surface 322, the heat emitted by drive circuits 311 and 312 by adjacent drive circuit substrate 30 is generated. It is possible to reduce the obstruction of the flow of the air, and thus to improve the heat radiation efficiency of the drive circuit board 30 and the drive circuits 311 and 312.

  Further, in the present embodiment, the capacitors 350 are juxtaposed along the upper side (side 331) of the drive circuit substrate 30 in the vertical direction Z, and the capacitor 360 is a lower side of the drive circuit substrate 30 in the vertical direction Z. They are juxtaposed along (side 332).

  As mentioned above, the capacitor 360 requires a large withstand voltage for the capacitor 350, so the size of the capacitor 360 is larger than the size of the capacitor 350. By arranging the capacitor 360 having such a large size in parallel on the side 332 side of the drive circuit board 30 which is the control circuit board 20 side, the heat flow generated in the drive circuit board 30 (drive circuits 311 and 312) can be obtained. It is possible to block in the lower direction of the vertical direction Z. That is, the heat generated in the drive circuit board 30 can be reduced to be conducted to the control circuit board 20. This makes it possible to reduce the temperature rise of the control circuit board 20 due to the heat generated by the drive circuits 311 and 312.

  Furthermore, in the front-rear direction Y of the heat dissipation case 81 provided with the drive circuit board 30, as a cooling means for cooling the drive circuit board 30, a heat dissipation fan, a heat dissipation plate or the like that generates an air flow may be provided.

  In the drive circuit substrate 30 in the liquid discharge device 1 of the present embodiment, a path Fp in which heat is not easily blocked by the capacitors 350 and 360 is formed along the front-rear direction Y. Therefore, when the heat dissipating fan is provided in the front-rear direction Y of the heat dissipating case 81, the air flow generated by the heat dissipating fan is efficiently supplied to the drive circuit board 30 via the path Fp. It is possible to improve the cooling efficiency.

  Note that the heat dissipating fan as the cooling means may be provided, for example, in the longitudinal direction Y of the drive circuit board 30 inside the heat dissipating case 81 or in the longitudinal direction Y of the drive circuit board 30 outside the heat dissipating case 81. It may be done. At this time, the heat dissipation case 81 may be provided with an opening or the like for guiding the air flow generated by the heat dissipation fan into the inside of the heat dissipation case 81.

  Furthermore, by providing the heat sink on the path Fp, the drive circuit board 30 can be efficiently cooled by the air flow for cooling the drive circuit board 30 via the path Fp. Here, the heat sink may be made of, for example, a metal having a high thermal conductivity such as aluminum, and is attached to the drive circuit board 30 via a thermally conductive insulating sheet or the like.

7. Operation and Effect As described above, in the liquid discharge device 1 according to the present embodiment, the drive circuits 311 and 312 provided in the center region in the front-rear direction Y (from the side 333 to the side 334) Are mounted, and a plurality of capacitors 350, 360 having a larger height than the first transistor M1 and the second transistor M2 included in the drive circuits 311, 312 are juxtaposed in the front-rear direction Y along the sides 331 and 332. . Thus, the heat generated in the drive circuits 311 and 312 can be increased by arranging the drive circuits 311 and 312 and the capacitors 350 and 360 in the back-and-forth direction Y (from side 333 to side 334). The path Fp which is hard to be blocked is formed by the large capacitors 350 and 360 of the

  Thus, the heat generated by the drive circuits 311 and 312 can be efficiently discharged via the path Fp. Therefore, the heat dissipation in the drive circuit substrate 30 provided with the plurality of drive circuits 311 and 312 can be improved.

  Further, when the liquid ejection device 1 includes cooling means such as a radiation fan for cooling the drive circuits 311 and 312 and the drive circuit board 30, the drive circuits 311 and 312 and the drive circuit board 30 by the cooling means in the front-rear direction Y Cooling efficiency can be improved. Therefore, the heat dissipation (cooling) in the drive circuit substrate 30 provided with the plurality of drive circuits 311 and 312 can be improved.

  Further, in the liquid discharge apparatus 1 according to the present embodiment, the drive circuits 311 and 312 are provided even when the plurality of drive circuit boards 30 and the plurality of discharge heads 40 are juxtaposed in the scanning direction X. A surface 322 of one drive circuit substrate 30 and a surface 321 of the other drive circuit substrate 30 on which the path Fp is formed are provided to face each other. Therefore, it becomes possible to reduce that heat is prevented from being disturbed by the capacitors 350 and 360 having a large height on both the surface 321 side and the surface 322 side of the drive circuit substrate 30, and the heat radiation efficiency of the drive circuit substrate 30 And cooling efficiency can be improved.

  As mentioned above, although an embodiment and a modification were described, the present invention is not limited to these embodiments, and can be carried out in various modes in the range which does not deviate from the gist. For example, the above embodiments can be combined as appropriate.

The invention includes configurations substantially the same as the configurations described in the embodiments (for example, configurations having the same function, method and result, or configurations having the same purpose and effect). The present invention also includes configurations in which nonessential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that can achieve the same effects or the same objects as the configurations described in the embodiments. Further, the present 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 ... control part, 3 ... delivery part, 4 ... support part, 5 ... conveyance part, 6 ... printing part, 10 ... power supply circuit board, 20 ... control circuit board, 21 ... holder, 22 ... flange Parts 23 Fixing plates 23a Openings 24a Openings 24 Reinforcement plates 25 Housings 26 26 Recesses 27 Covering members 28 Openings 29 connectors 30 Drive circuit board 31 Holding member, 40: discharge head, 41: first support portion, 42: second support portion, 43: third support portion, 45: discharge head main body, 51: rotation mechanism, 52: conveyance roller, 53: driven roller, DESCRIPTION OF SYMBOLS 60 ... Piezoelectric element, 61 ... Movement mechanism, 62 ... Guide member, 63 ... Guide rail part, 64 ... Carriage support part, 65, 86, 87 ... Cable, 71 ... Carriage, 72 ... Carriage main body, 73 ... Carriage cover, 74 ... connection Plate, 75, 83 Bto B connector, 76, 77, 84, 85 FFC connector 81 Heat dissipation case 91 Maintenance portion 92 Cap 110 High voltage generation circuit 210 Control circuit 211 Discharge data Generation circuit 212 drive data generation circuit 311, 312 drive circuit 320 voltage generation circuit 320, 322 surface, 331 332 332 334, 334 side 350, 360 capacitor 400 discharge module 410: drive signal selection circuit 420: selection control circuit 430: selection circuit 500: amplification control signal generation circuit 510: modulation unit 512, 513: adder, 514: comparator, 515: inverter, 516: integration Attenuator, 517: Attenuator, 520: Gate driver, 521: First gate driver, 22 second gate driver 550 output circuit 560 low pass filter 570 first feedback circuit 572 second feedback circuit 580 reference voltage generation unit 600 discharge unit 601 piezoelectric body 611 612: electrode, 621: diaphragm, 631: cavity, 632: nozzle plate, 641: reservoir, 651: nozzle, 651a: nozzle surface, 661: supply port, D: distance, Bst, Gnd, Gvd, Hdr, Ifb , In, Ldr, Out, SW2, Sw, Vfb ... terminals, R1, R2, R3, R4, R5, R6 ... resistances, C1, C2, C3, C4, C5 ... capacitors, D1 ... diodes, L1 ... inductors, M1 ... First transistor, M2 ... Second transistor, Fp ... Path, M ... Medium, R ... Roll body

Claims (8)

A discharge head including a nozzle which receives a drive signal and discharges a liquid;
A first side, and a second side facing the first side in a first direction in which the liquid is discharged from the nozzle, and provided separately from the discharge head in a second direction intersecting the first direction The printed circuit board,
A plurality of amplifier circuits provided on the substrate, arranged in parallel in the second direction in a central region between the first side and the second side, and generating the drive signal;
Provided on the substrate and juxtaposed in the second direction in a region between the plurality of amplifier circuits and at least one of the first side and the second side, from the heights of the plurality of amplifier circuits And multiple elements with large heights,
A liquid discharge apparatus comprising: The discharge head is provided with a plurality of discharge modules provided with 300 or more and 600 or more nozzles per inch.
The liquid discharge device according to claim 1, The plurality of amplifier circuits are provided on a first surface of the substrate,
The plurality of elements are provided on a second surface of the substrate,
In the third direction intersecting the first direction and the second direction, a plurality of the substrates and the ejection heads are arranged in parallel,
The first surface of one of the two adjacent ones of the plurality of substrates and the second surface of the other face each other,
The liquid discharge device according to claim 1 or 2, wherein At least a portion of the plurality of elements are juxtaposed along the first side,
The liquid discharge device according to any one of claims 1 to 3, wherein At least a portion of the plurality of elements are juxtaposed along the second side,
The liquid discharge device according to any one of claims 1 to 4, characterized in that: The plurality of amplifier circuits dissipate heat as the drive signal is generated.
The liquid discharge device according to any one of claims 1 to 5, characterized in that: The plurality of elements are juxtaposed in the second direction in a region between the plurality of amplifier circuits and one of the first side and the second side, and are supplied to the plurality of amplifier circuits. Including multiple capacitors to stabilize the supply voltage signal,
The liquid discharge apparatus according to any one of claims 1 to 6, wherein The discharge head includes a piezoelectric element which is displaced by being supplied with the drive signal and a reference voltage signal.
The nozzle discharges the liquid based on displacement of the piezoelectric element,
The plurality of elements are juxtaposed in the second direction in a region between the plurality of amplifier circuits and the other of the first side and the second side, and the reference supplied to the piezoelectric element Including multiple capacitors to stabilize the voltage signal,
The liquid discharge apparatus according to any one of claims 1 to 7, wherein

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