JP2019064112A - Print head - Google Patents

Abstract

To provide a print head which enables reduction of variations in temperature distribution.SOLUTION: A print head includes: a discharge module including six hundreds or more nozzles which are arranged parallel to each other in a manner that three hundreds or more nozzles are placed per inch, a piezoelectric element for causing a liquid to be discharged from the nozzles, and a drive IC which is provided on the piezoelectric element and outputs a drive signal for driving the piezoelectric element; and a housing which is provided so as to cover the discharge module. At least a part of the housing is formed by aluminium.SELECTED DRAWING: Figure 16

Description

  The present invention relates to a print head.

  2. Related Art An ink jet printer that prints an image or a document by discharging a liquid such as ink is known using a piezoelectric element (for example, a piezoelectric element). The piezoelectric element is provided corresponding to each of the plurality of nozzles in the print head, and each of the plurality of nozzles is driven according to the drive signal, whereby a predetermined amount of liquid is ejected from the nozzles at a predetermined timing to dot on the medium. Form.

  In order to perform high quality and high delicate printing of 600 dpi or more in an ink jet printer, it is necessary to increase the nozzle density of a print head that ejects liquid. Specifically, in the line type inkjet printer, in order to print at 600 dpi, the density of the nozzles arranged in a line requires a nozzle density of 600 or more per inch, and in the serial type inkjet printer In the case of printing by reciprocating operation, a nozzle density of 300 or more per inch is required.

  As a technology for increasing the density of such nozzles, Patent Document 1 discloses a technology for directly mounting a drive IC for driving the piezoelectric element on an actuator substrate including a flow path and the piezoelectric element.

JP, 2016-179575, A

  As described above, with the increase in density of the nozzles provided in the print head, the number of nozzles per unit area increases, and accordingly the amount of heat generation per unit area of the drive IC constituting the print head also increases. . For this reason, in this type of ink jet printer, improvement of the cooling efficiency of the drive IC and reduction of heat generation are required.

  However, in the structure in which the drive IC is provided on the piezoelectric element as in Patent Document 1, the drive IC and the piezoelectric element are closed in order to prevent malfunction caused by adhesion of the liquid to the piezoelectric element and the drive IC. It was necessary to arrange in the space near. For this reason, the cooling could not but rely on heat dissipation by heat conduction to the peripheral structure in which the drive IC is disposed.

  In addition, in order to improve the cooling efficiency, it is also considered to adopt a structure in which a liquid flow path is provided in a structure forming the space, but in this case, the heat generated in the drive IC is While it is possible to dissipate heat through the liquid, when the calorific value of the drive IC exceeds the quantity of heat that can be dissipated through the liquid, the temperature of the liquid flowing in the flow path with the heat generation of the drive IC May cause changes in the viscosity of the liquid, etc.

Furthermore, if the temperature distribution inside the print head varies due to the heat generation of the drive IC, the temperature distribution of the liquid also varies, and the viscosity of the liquid also varies. Therefore, even if the piezoelectric element corresponding to each nozzle provided in the print head is driven in the same manner, the variation in viscosity causes variations in the discharge amount among the plurality of nozzles forming the nozzle row, resulting in discharge Accuracy may be reduced.

  The present invention has been made in view of the above, and according to some aspects of the present invention, it is possible to provide a print head capable of reducing variations in temperature distribution.

  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 print head according to this application example is provided side by side at 300 or more per inch, and has 600 or more nozzles, a piezoelectric element for discharging a liquid from the nozzle, and the piezoelectric element provided on the piezoelectric element A discharge module including a drive IC for outputting a drive signal for driving the element, and a case provided to cover the discharge module, at least a part of the case being formed of aluminum .

  “To cover” does not have to cover the entire surface of the ejection module with the housing, as long as the housing covers the ejection module when viewed from at least one side of the ejection module. Good. Moreover, "aluminum" may be pure aluminum or may be an aluminum alloy.

  In the print head according to this application example, by providing the case formed of aluminum so as to cover the discharge module including the drive IC with a large amount of heat, the heat generated by the discharge module forms the case, and the thermal conductivity The heat is diffused through the high aluminum and heat concentration in the print head is reduced. As a result, it is possible to provide a print head capable of reducing variations in temperature distribution.

Application Example 2
In the print head according to the application example, the housing may have a recess formed at least in part of aluminum, and the discharge module may be disposed between the recess and the fixing plate.

  In the discharge module, the nozzle surface of the nozzle may be positioned on the fixed plate side, and the fixed plate may be formed with an opening where the nozzle surface of the nozzle is exposed.

  In the print head according to this application example, since the discharge module is accommodated in the concave portion of the case formed of aluminum, the heat generated by the discharge module including the driving IC with large heat generation is more efficient through the aluminum. It becomes possible to diffuse and dissipate well. This further reduces the heat concentration in the print head. Therefore, it is possible to further reduce the variation in temperature distribution.

Application Example 3
In the print head according to the application example, the discharge module includes a protective substrate disposed between the piezoelectric element and the drive IC, and the protective substrate protects the piezoelectric element on the piezoelectric element side. You may form a space.

In the print head according to this application example, heat generated by the discharge module is obtained even if the protective substrate is included between the piezoelectric element and the drive IC for downsizing the discharge module and increasing the density of the nozzles. It is possible to efficiently diffuse and dissipate the heat through the aluminum forming the housing. This reduces heat concentration in the print head. Therefore, it is possible to reduce variations in temperature distribution.

  Further, in the print head according to this application example, the protective substrate provided with the drive IC can be disposed so as to protect the piezoelectric element, so that the piezoelectric element can be reduced from being deteriorated by the influence of oxygen or moisture. .

Application Example 4
The print head according to the application example may include a plurality of the ejection modules.

  In the print head according to this application example, even when the plurality of ejection modules are provided, the heat is diffused through the casing formed of aluminum having a high thermal conductivity, and therefore, the plurality of ejection modules may be separated. The temperature difference is reduced. Therefore, it is possible to reduce variations in temperature distribution.

  In addition, in the print head according to the application example, when the plurality of discharge modules are provided in a staggered manner, it is possible to form a continuous nozzle row by partially overlapping the nozzles of the plurality of discharge modules. Therefore, even in the case of a wide print head used for a line printer or the like, it is possible to reduce the variation in the nozzle interval at which the liquid is discharged.

Application Example 5
In the print head according to the application example, the nozzle may discharge the liquid at a frequency of 16000 Hz or more.

  In the print head according to this application example, even when the liquid is discharged at a high frequency of 16000 Hz or more, the heat generated in the discharge module including the drive IC is the case by providing the case formed of aluminum. It is diffused through the high thermal conductivity aluminum to form This reduces heat concentration in the print head. Therefore, it is possible to reduce the occurrence of variations in temperature distribution.

Application Example 6
The print head according to this application example is provided side by side at 300 or more per inch, and has 600 or more nozzles, a piezoelectric element for discharging a liquid from the nozzle, and the piezoelectric element provided on the piezoelectric element A discharge module including a drive IC for outputting a drive signal for driving the element; and a case provided to cover the discharge module, the case having a thermal conductivity of 0.10 kW / (m・ Contains materials higher than ° C.

  In the print head according to this application example, a casing formed of a material having a thermal conductivity higher than 0.10 kW / (m · ° C.) is provided so as to cover the ejection module including the driving IC with large heat generation. The heat generated by the ejection module is diffused through the housing and dissipated, reducing the concentration of heat in the print head. As a result, it is possible to provide a print head capable of reducing variations in temperature distribution.

It is a block diagram of a liquid discharge apparatus. It is a block diagram which shows the electric constitution of a liquid discharge apparatus. It is a disassembled perspective view which shows the structure of a head unit. It is a top view which shows the nozzle surface of a head unit. It is sectional drawing which shows the structure of a head unit. It is sectional drawing which shows the structure of a head unit. It is a disassembled perspective view which shows the structure of a discharge module. It is a sectional view showing the composition of a discharge module. It is a figure which shows an example of the drive signals COMA, COMB, and COMC. It is a block diagram which shows the electric constitution of a discharge module. It is a figure which shows an example of the decoding content of a decoder. It is a figure which shows the structure of a selection part. It is a figure for demonstrating operation | movement of drive IC. It is a figure for demonstrating arrangement | positioning of the discharge module provided in the head unit used for confirmation of a temperature rise value. It is a figure which shows the confirmation result of the temperature rise value of the discharge module provided in the head unit by which the holder was formed with resin. It is a figure which shows the confirmation result of the temperature rise value of the discharge module provided in the head unit in which the holder was formed by aluminum.

  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 print head according to the present invention will be described by taking a print head applied to a liquid ejection apparatus which is a printing apparatus as an example.

1. Configuration of Liquid Discharge Device FIG. 1 is a configuration diagram showing a liquid discharge device 1 of the present embodiment. The liquid ejection apparatus 1 according to the present embodiment performs printing by ejecting ink, which is an example of a liquid, onto a medium P to form dots. The medium P is typically a printing paper, but any printing object such as a resin film or a fabric may be used as the medium P.

  The liquid ejection device 1 includes a control unit 10, a head unit 20 (print head), and a transport unit 30. Further, the liquid discharge device 1 is provided with a liquid container 50 for storing ink. As the liquid container 50, for example, a cartridge that can be detached from the liquid ejection device 1, a bag-like ink pack formed of a flexible film, an ink tank that can be refilled with ink, or the like can be employed. The liquid container 50 stores a plurality of types of ink having different colors.

The control unit 10 is, for example, a CPU (Central Processing Unit) or an FPGA (Field).
Each element of the liquid ejection apparatus 1 is controlled based on information input from an external device such as a host computer including a processing circuit such as a programmable gate array) and a storage circuit such as a semiconductor memory. Specifically, the control unit 10 generates a control signal Ctrl for transporting the medium P in the direction Y, and outputs the control signal Ctrl to the transport unit 30. Further, the control unit 10 generates drive signals COMA, COMB, COMC, a plurality of differential signals dS including print data and the like, and a differential clock signal dClk, and outputs them to the head unit 20.

  The transport unit 30 transports the medium P in the direction Y based on the input control signal Ctrl.

The head unit 20 is a line type print head which is long in a direction X intersecting (typically orthogonal) to the direction Y. The head unit 20 includes a plurality of ejection modules 40 (four in FIG. 1). Ink is supplied from the liquid container 50 to each of the plurality of ejection modules 40. Further, each of the plurality of ejection modules 40 receives, from the control unit 10, drive signals COMA, COMB, and COMC for driving the ejection modules 40, and a plurality of differential signals including print data for controlling the driving. dS and the differential clock signal dClk are input. Then, each of the plurality of ejection modules 40 ejects ink from a part or all of the plurality of nozzles provided in the ejection module 40 based on the plurality of differential signals dSn. Although four ejection modules 40 are shown in FIG. 1, five or more ejection modules 40 may be provided in the liquid ejection device 1, or three or less ejection modules 40 may be provided.

  As described above, in the liquid ejection apparatus 1 according to the present embodiment, the plurality of ejection modules 40 provided in the head unit 20 eject the ink onto the medium P in synchronization with the conveyance of the medium P by the conveyance unit 30. , Forming an image on the surface of the medium P.

  A direction perpendicular to a plane (X-Y plane) parallel to the surface of the medium P is referred to as a direction Z. The direction Z is typically a direction in which ink is ejected from the ejection module 40.

2. Electrical Configuration of Liquid Ejection Device FIG. 2 is a block diagram showing the electrical configuration of the liquid ejection device 1 of the present embodiment. As shown in FIG. 2, the liquid ejection device 1 includes a head unit 20, a control unit 10 that outputs a signal for controlling the ejection of ink from the head unit 20, and a transport unit 30 that transports the medium P. Prepare. A flexible flat cable (FFC: Flexible Flat Cable) (not shown) is connected to each of the control unit 10, the head unit 20, and the transport unit 30, and is electrically connected via the FFC.

  The control unit 10 includes a control circuit 11, a control signal conversion circuit 12, a control signal transmission circuit 13, and a drive circuit 14.

  The control circuit 11 outputs various control signals and the like for controlling each unit when various signals such as image data are supplied from the host computer.

  Specifically, the control circuit 11 uses n (n.gtoreq.1) original control signals as a plurality of types of original control signals for controlling the ejection of ink from the ejection unit 600 described later based on various signals from the host computer. The print data signals sSI1 to sSIn and n original latch signals sLAT1 to sLATn are generated and output to the control signal conversion circuit 12 in parallel format. Note that a plurality of types of original control signals may not include a part of these signals, or may include other signals.

  The control signal conversion circuit 12 converts each of the original print data signal sSIi (i is any one of 1 to n) and the original latch signal sLATi output from the control circuit 11 into an original serial control signal sSi in one serial format ( Serialize) and output to the control signal transmission circuit 13.

The control signal transmission circuit 13 converts the original serial control signals sS1 to sSn output from the control signal conversion circuit 12 into a plurality of differential signals dS (differential signals dS1 to dSn) formed of two signals, respectively. The differential signals dS1 to dSn are transmitted to the head unit 20. The control signal transmission circuit 13 also generates a differential clock signal dClk used for high-speed serial data transfer of the differential signals dS1 to dSn, and transmits the differential clock signal dClk to the head unit 20. For example, the control signal transmission circuit 13 may use LVDS (Low Voltage Differential).
Signaling: The differential signals dS1 to dSn of the transfer method and the differential clock signal dClk are generated and transmitted to the head unit 20. Since the differential signal of the LVDS transfer system has an amplitude of about 350 mV, high-speed data transfer can be realized. The control signal transmission circuit 13 may be a low voltage positive emitter coupled logic (LVPECL) other than LVDS or a CM.
The differential signals dS1 to dSn and differential clock signals dClk of various high-speed transfer methods such as L (Current Mode Logic) may be generated and transmitted to the head unit 20.

  Further, the control circuit 11 is based on various signals from the host computer to drive data dA, dB, of digital data as drive sources of drive signals COMA, COMB, COMC for driving the plurality of ejection modules 40 provided in the head unit 20. dC is generated and output to the drive circuit 14. In the present embodiment, the drive data dA, dB, dC are digital data obtained by analog / digital conversion of the waveform (drive waveform) of the drive signal. However, the drive data dA, dB, dC may be digital data indicating the difference with respect to the latest drive data, or the drive waveform defines the correspondence between the length of each section having a constant slope and the slope. It may be digital data.

  The drive circuit 14 generates a drive signal COMA for driving each of the plurality of ejection modules 40 provided in the head unit 20 based on the drive data dA output from the control circuit 11. Similarly, the drive circuit 14 generates a drive signal COMB for driving each of the plurality of ejection modules 40 based on the drive data dB. Similarly, the drive circuit 14 generates a drive signal COMC for driving each of the plurality of ejection modules 40 based on the drive data dC. For example, the drive circuit 14 may generate drive signals COMA, COMB, COMC by performing class D amplification after performing digital / analog conversion on each of the drive data dA, dB, dC. A plurality of drive circuits 14 may be provided corresponding to each of the drive signals COMA, COMB, COMC. At this time, the drive circuit 14 for generating each of the drive signals COMA, COMB, and COMC may have the same circuit configuration, except that the input drive data and the output drive signal are different.

  The control circuit 11 generates and outputs a control signal Ctrl to the transport unit 30 that transports the medium P, in addition to the above processing. The transport unit 30 includes a motor (not shown) for transporting the medium P, and transports the medium P in a predetermined direction and position by controlling the driving of the motor based on the control signal Ctrl.

  The head unit 20 has a control signal reception circuit 23, a control signal restoration circuit 22, and a plurality of ejection modules 40.

  The control signal reception circuit 23 receives the differential signals dS1 to dSn of the LVDS transfer scheme transmitted from the control signal transmission circuit 13, differentially amplifies the received differential signals dS1 to dSn, and controls the serial control signals S1 to S1. It converts into Sn and outputs the converted serial control signals S1 to Sn to the control signal restoration circuit 22. Further, the control signal reception circuit 23 receives the differential clock signal dClk of the LVDS transfer system transmitted from the control signal transmission circuit 13, differentially amplifies the received differential clock signal dClk, and converts it into a clock signal Clk. The converted clock signal Clk is output to the control signal restoration circuit 22. The control signal receiving circuit 23 may receive differential signals dS1 to dSn and differential clock signals dClk of various high-speed transfer methods such as LVPECL and CML other than LVDS.

The control signal restoration circuit 22 controls the discharge of the ink from the discharge unit 600 based on the serial control signals S1 to Sn converted by the control signal reception circuit 23 as clock signals Sck and n printings as a plurality of types of signals. Data signals SI1 to SIn and n latch signals LAT1 to LATn are generated. Specifically, the control signal restoration circuit 22 outputs the original print data signal sSIi and the original latch signal sLATi included in the serial control signal Si (i is any one of 1 to n) output from the control signal reception circuit 23. By restoring (deserializing), the print data signal SIi and the latch signal LATi are generated and output to the ejection module 40. Further, the control signal restoration circuit 22 performs predetermined processing (for example, processing of dividing at a predetermined division ratio) on the clock signal Clk output from the control signal reception circuit 23, and the print data signals SI1 to SIn. A clock signal Sck synchronized with the latch signals LAT1 to LATn is generated and output to the plurality of ejection modules 40.

  In each of the plurality of ejection modules 40, a plurality of types of control signals including the print data signal SIi output from the control signal restoration circuit 22, the latch signal LATi, and the clock signal Sck, and three types of drive signals COMA, COMB, and COMC. It is input. Since the plurality of ejection modules 40 have the same configuration, only one ejection module 40 will be described as a representative, and the print data signal SIi and the latch signal input to the ejection modules 40 do not need to be particularly distinguished. LATi will be described as a print data signal SI and a latch signal LAT, respectively.

  The ejection module 40 includes a piezoelectric element 60, and a plurality of ejection units 600 that eject ink by driving the piezoelectric element 60, and a drive signal Vout for driving the piezoelectric element 60 included in each of the plurality of ejection units 600. And a driving IC 41 that generates the

  A plurality of control signals including the print data signal SI, the latch signal LAT, and the clock signal Sck, and three types of drive signals COMA, COMB, COMC are input to the drive IC 41. Although the details will be described later, the drive IC 41 generates three types of piezoelectric elements 60 corresponding to the plurality of ejection units 600 based on the print data signal SI at timing based on the latch signal LAT synchronized with the clock signal Sck. The drive signal Vout is generated by controlling which of the drive signals COMA, COMB, and COMC is output or not.

  The drive signal Vout generated by the drive IC 41 is applied to one end of each piezoelectric element 60 of the plurality of ejection units 600, and the constant voltage signal VBS is commonly applied to the other end of the piezoelectric element 60. Then, the piezoelectric element 60 is displaced in accordance with the potential difference between the drive signal Vout and the constant voltage signal VBS to eject ink.

3. Configuration of Head Unit Here, the configuration of the head unit 20 will be described using FIGS. 3 to 6.

  FIG. 3 is an exploded perspective view showing the configuration of the head unit 20 of the present embodiment. FIG. 4 is a plan view showing a nozzle surface Na on which a nozzle row from which ink is ejected in the head unit 20 is formed. 5 is a cross-sectional view taken along a line II in FIG. 4, and FIG. 6 is a cross-sectional view taken along a line II-II in FIG.

  As shown in FIG. 3, the head unit 20 of the present embodiment includes a head unit main body 200 that ejects ink, and a filter member 250 fixed to the head unit main body 200.

  The head unit body 200 is fixed to a plurality of ejection modules 40 having nozzles N for ejecting ink, a holder 220 (an example of a “housing”) provided so as to cover the plurality of ejection modules 40, and the holder 220 The circuit board 230, the supply member 240, and the fixing plate 210 for fixing the plurality of ejection modules 40 are provided.

As shown in FIG. 4, in the ejection module 40, a plurality of nozzles N for ejecting ink are arranged in two rows in the direction X. Inside the ejection module 40, a flow path communicating with the nozzle N and a piezoelectric element 60 driven to cause pressure change in the ink in the flow path are provided. Then, the drive signal Vout is applied to the piezoelectric element 60, so that the piezoelectric element 60 is deformed, and the volume of the flow path is changed, so that the ink is discharged from the nozzle N. The surface provided with the nozzle N of the ejection module 40 is referred to as a nozzle surface Na.

  Further, as shown in FIG. 3, on the side surface of each ejection module 40, a drive wiring 401 is provided which extends in the direction opposite to the direction Z with respect to the surface provided with the nozzles N. The ejection module 40 and the circuit board 230 are electrically connected by the drive wiring 401. The details of the operation and structure of the ejection module 40 will be described later.

  As shown in FIGS. 3 and 4, the fixing plate 210 has a plurality of openings 211.

  The plurality of ejection modules 40 are fixed to the fixing plate 210 so that the nozzle surface Na is exposed from each of the plurality of openings 211. Specifically, the peripheral edge portion of the opening 211 and the nozzle surface Na side of the discharge module 40 are fixed. At this time, the ejection modules 40 are arranged in a zigzag along the direction X. Displacing the ejection modules 40 in the direction X in a staggered manner means that the ejection modules 40 juxtaposed in the direction X are alternately displaced in the direction Y. That is, the rows of ejection modules 40 juxtaposed in the direction X are juxtaposed in two rows in the direction Y, and the rows of juxtaposed discharge modules 40 are arranged by being shifted by a half pitch in the direction X. By arranging the ejection modules 40 in a staggered manner along the direction X in this manner, the nozzles N of the two ejection modules 40 are partially overlapped in the direction X, and a row of nozzles N continuous in the direction X is provided. Can be formed. In FIG. 4, for example, two rows of ejection modules 40 juxtaposed in the direction X are juxtaposed in two rows in the direction Y, but three or more ejection modules 40 are juxtaposed in the direction X It may be arranged in parallel in three or more rows in the direction Y.

  As shown in FIG. 3, FIG. 5 and FIG. 6, on one surface side of the direction Z of the holder 220, a housing portion 221 (an example of a “recess”) for housing a plurality of discharge modules 40 is provided. The accommodation portion 221 has a concave shape that opens on one surface side in the direction Z, and the plurality of ejection modules 40 fixed to the fixing plate 210 are accommodated. Specifically, the ejection module 40 is disposed in an accommodation space formed between the accommodation portion 221 of the holder 220 provided so as to cover the ejection module 40 and the fixing plate 210. Note that the storage portion 221 may be provided for each of the plurality of ejection modules 40, or may be provided continuously over the plurality of ejection modules 40.

  The holder 220 provided so as to cover the ejection module 40 may be provided so as to cover at least one surface other than the nozzle surface Na of the ejection module 40. Specifically, when the ejection module 40 is viewed from at least one of the direction X, the direction Y, and the direction Z, the ejection module 40 may be covered by the holder 220. At this time, the ejection module 40 is preferably disposed in the vicinity of the holder 220, and more preferably, the ejection module 40 and the holder 220 are disposed in contact with each other.

  Further, the circuit board 230 is held on the other surface side of the holder 220 in the direction Z. The circuit board 230 is provided with electronic components, wirings and the like that constitute the control signal receiving circuit 23 (FIG. 2) and the control signal restoration circuit 22 (FIG. 2). Further, the circuit board 230 is provided with connectors 233 on both sides in the direction Y, respectively.

  As shown in FIGS. 3 and 6, the holder 220 is provided with an insertion hole 223 for inserting the drive wiring 401 provided in the ejection module 40. Insertion holes 231 are provided in the circuit board 230 at positions corresponding to the insertion holes 223. The drive wiring 401 is inserted through the insertion hole 223 of the holder 220 and the insertion hole 231 of the circuit board 230, and the discharge module 40 disposed on one side of the holder 220 and the circuit board 230 held on the other side of the holder 220. And electrically connected.

  Furthermore, as shown in FIGS. 3 and 5, the holder 220 is provided with a flow path 222 for supplying the ink supplied from the supply member 240 to the ejection module 40. In the present embodiment, two flow paths 222 are provided for one ejection module 40. Insertion holes 232 are provided at positions corresponding to the flow paths 222 of the circuit board 230.

  The supply member 240 is fixed to the other side of the holder 220 as shown in FIGS. 3 and 5.

  The supply member 240 is provided with an insertion hole 243 penetrating in the direction Z at a position corresponding to the connector 233. The external wiring 260 connected to the connector 233 provided on the circuit board 230 is inserted into the insertion hole 243. At this time, the drive signals COMA, COMB, COMC of the large voltage signal are supplied to one of the connectors 233 provided on the circuit board 230 through the external wiring 260, and the other external wiring 260 is supplied to the other of the connector 233. The differential signal dS of the small voltage signal (differential signals dS1 to dSn) and the differential clock signal dClk are supplied via the signal line. This makes it possible to reduce the superposition of the large voltage signal on the small voltage signal.

  Further, the supply member 240 is provided with a flow path 242 which is connected to the flow path 222 of the holder 220 to form a flow path for supplying the ink. As shown in FIG. 5, the flow path 242 is also provided in the inside of a projecting portion 241 provided to protrude on one surface side of the supply member 240 in the Z direction. The protrusion 241 is inserted into the insertion hole 232 of the circuit board 230. Thereby, the flow path 242 and the flow path 222 are connected, and a flow path for supplying the ink from the supply member 240 to the holder 220 is formed. Further, the flow path 242 is provided to open on one surface side of the direction Z of the supply member 240, and is connected to the filter member 250.

  The filter member 250 includes a plurality of filter units 251, and removes foreign matter, air bubbles, and the like contained in the ink supplied from the liquid container 50.

  Specifically, each of the plurality of filter units 251 has an opening 252, a flow path 253, and a filter 254. Ink is supplied to the opening 252 from the liquid container 50 through an ink tube (not shown) or the like. The ink supplied from the opening 252 is supplied to the flow path 242 of the supply member 240 via the flow path 253. The filter 254 is provided so as to intervene in the flow path 253, and removes air bubbles, foreign matters, and the like contained in the ink supplied to the flow path 253 from the opening 252. As a result, the ink supplied to the head unit main body 200 is less likely to contain air bubbles, foreign matters, and the like.

  In the present embodiment, the filter member 250 for supplying the ink to the head unit main body 200 is fixed to the other surface side of the supply member 240, and a plurality of filter units 251 are stacked in the direction Y.

4. Configuration of Discharge Module Here, the configuration of the discharge module 40 will be described using FIGS. 7 and 8. FIG. 7 is an exploded perspective view of the ejection module 40. FIG. 8 is a cross-sectional view taken along line III-III of FIG.

As shown in FIG. 7, the ejection module 40 includes 2M nozzles N arranged in the direction X. In the present embodiment, 2M nozzles N form two nozzle rows divided into two rows of the row L1 and the row L2. Hereinafter, each of the M nozzles N belonging to the row L1 may be referred to as a nozzle N1, and each of the M nozzles N belonging to the row L2 may be referred to as a nozzle N2. Also, as an example, the position in the direction X between the m-th nozzle N1 of the M nozzles N1 belonging to the row L1 and the m-th nozzle N2 of the M nozzles N2 belonging to the row L2 is It is assumed that they substantially match (m is a natural number that satisfies 1 ≦ m ≦ M). Here, "substantially match" is a concept including a case where it can be regarded as identical if an error is taken into consideration, in addition to a case where they are completely matched. The 2M nozzles N are the direction X of the m-th nozzle N1 of the M nozzles N1 belonging to the row L1, and the m-th nozzle N2 of the M nozzles N2 belonging to the row L2. It may be arranged in a staggered manner so that the position of.

  As shown in FIGS. 7 and 8, the ejection module 40 includes a flow path substrate 44. The flow path substrate 44 is a plate-like member including the surface F1 and the surface FA. The face F1 is a surface on the medium P side, and the face FA is a surface on the opposite side to the face F1. The pressure chamber substrate 45, the vibrating portion 46, the plurality of piezoelectric elements 60, the protective substrate 47, and the flow path member 48 are provided on the surface of the surface FA, and the nozzle plate 49 and the vibration absorber are provided on the surface of the surface F1. 43 are installed. Each element of the ejection module 40 is a plate-like member that is generally elongated in the direction X, and the components are stacked in the direction Z, and are bonded to each other using, for example, an adhesive.

  The nozzle plate 49 is a plate-like member, and 2M nozzles N which are through holes are formed. In the nozzle plate 49, M nozzles N corresponding to each of the rows L1 and L2 are juxtaposed at a density of 300 or more per inch, and 600 or more in one ejection module 40 are provided. Assume that

  The flow path substrate 44 is a plate-like member for forming a flow path of ink, and as shown in FIGS. 7 and 8, the flow path RA is formed in the flow path substrate 44. Further, in the flow path substrate 44, 2M flow paths 441 and 2M flow paths 442 are formed so as to correspond to 2M nozzles N and one to one. The flow path 441 and the flow path 442 are openings formed to penetrate the flow path substrate 44 as shown in FIG. The flow path 442 communicates with the nozzle N corresponding to the flow path 442. Further, on the surface F1 of the flow path substrate 44, two flow paths 443 are formed. One of the two flow paths 443 is a flow path connecting the flow path RA and the M flow paths 441 corresponding to the M nozzles N1 belonging to the row L1 one to one, and the other is a flow path It is a flow path which connects M flow paths 441 corresponding to 1 to 1 to M nozzles N2 belonging to RA and row L2.

  As shown in FIGS. 7 and 8, the pressure chamber substrate 45 is a plate-like member in which 2M openings 451 are formed to correspond to 2M nozzles N and one to one. A vibrating portion 46 is provided on the surface of the pressure chamber substrate 45 opposite to the flow path substrate 44. The vibrating portion 46 is a plate-like member capable of vibrating.

  As shown in FIG. 8, the vibrating portion 46 and the surface FA of the flow path substrate 44 oppose each other at an inner side of each opening 451 with a space therebetween. A space located between the surface FA of the flow path substrate 44 and the vibrating portion 46 inside the opening 451 functions as a pressure chamber C for applying pressure to the ink filled in the space. The pressure chamber C is, for example, a space in which the direction Y is a longitudinal direction and the direction X is a lateral direction. The discharge module 40 is provided with 2M pressure chambers C so as to correspond to 2M nozzles N one by one. The pressure chamber C provided corresponding to the nozzle N1 communicates with the flow path RA via the flow path 441 and the flow path 443 and also communicates with the nozzle N1 via the flow path 442. The pressure chamber C provided corresponding to the nozzle N2 communicates with the flow path RA via the flow path 441 and the flow path 443 and also communicates with the nozzle N2 via the flow path 442.

As shown in FIGS. 7 and 8, on the surface of the vibrating portion 46 opposite to the pressure chamber C, 2M piezoelectric elements are provided so as to correspond to 2M pressure chambers C one to one. 60 are provided. The drive signal Vout is applied to one end of the piezoelectric element 60, and the constant voltage signal VBS is applied to the other end. The piezoelectric element 60 is deformed (driven) in accordance with the potential difference between the drive signal Vout and the constant voltage signal VBS. The vibrating portion 46 vibrates in conjunction with the deformation of the piezoelectric element 60, and when the vibrating portion 46 vibrates, the pressure in the pressure chamber C fluctuates. Then, when the pressure in the pressure chamber C fluctuates, the ink filled in the pressure chamber C is discharged via the flow path 442 and the nozzle N. In the present embodiment, it is assumed that the piezoelectric element 60 can be driven so that the ink is ejected from the nozzle N at least 16000 times (that is, a frequency of 16000 Hz or more) for the drive signal Vout.

  The pressure chamber C, the flow paths 441 and 442, the nozzle N, the vibration unit 46, and the piezoelectric element 60 function as a discharge unit 600 for discharging the ink filled in the pressure chamber C by driving the piezoelectric element 60. That is, in the ejection module 40, a plurality of ejection units 600 are arranged in parallel in two rows along the direction X.

  The protective substrate 47 shown in FIGS. 7 and 8 is a plate-like member for protecting the 2M piezoelectric elements 60 formed in the vibrating portion 46, and is a surface of the vibrating portion 46 or the pressure chamber substrate 45. It is provided on the surface.

  Two accommodation spaces 473 are formed on the surface G1 of the protective substrate 47 which is the surface on the medium P side as viewed from the ejection module 40. One of the two accommodation spaces 473 is a space for accommodating M piezoelectric elements 60 corresponding to the M nozzles N1, and the other is M piezoelectric elements 60 corresponding to the M nozzles N2. Space for housing The housing space 473 functions as a “protection space” sealed in order to prevent the piezoelectric element 60 from being deteriorated due to the influence of oxygen or moisture when the protection substrate 47 is disposed on the discharge portion 600. The width (height) of the housing space 473 in the direction Z is sufficiently large so that the piezoelectric element 60 and the protective substrate 47 do not contact even if the piezoelectric element 60 is displaced. For this reason, even when the piezoelectric element 60 is displaced, the noise caused by the displacement of the piezoelectric element 60 is prevented from propagating to the outside of the accommodation space 473. The protective space for preventing deterioration due to the influence of oxygen or moisture of the piezoelectric element 60 may be, for example, a housing space 473 sealed by a protective substrate 47 as shown in FIG. There may be a case where there is a partial opening between the protective substrate 47 and the surface G1. At this time, for example, the space may be sealed by the flow path member 48 or the like.

  A drive IC 41 is provided on a surface G2 of the protection substrate 47 which is the surface opposite to the surface G1. The drive IC 41 receives a plurality of control signals such as the print data signal SI, the latch signal LAT, and the clock signal Sck input to the ejection module 40, and the drive signals COMA, COMB, and COMC. Then, based on the print data signal SI, the drive IC 41 generates a drive signal Vout by switching which of the drive signals COMA, COMB, and COMC is to be supplied to each piezoelectric element 60, and outputs an output. Do. The driving IC 41 has a rectangular shape including a long side and a short side, and the driving IC 41 in the present embodiment has a long rectangular shape whose long side is ten times or more as long as the short side. Good.

  On the surface G2 of the protective substrate 47, 2M wires 471 are electrically connected to the drive IC 41 so as to correspond to 2M piezoelectric elements 60 and one-on-one. Specifically, one end of the wiring 471 is electrically connected to the output of the selection unit 420 (see FIG. 10) of the drive IC 41 described later, and the other end is connected to the piezoelectric element 60 through the conduction hole penetrating the protection substrate 47. Electrically connected. As described above, the drive signal Vout output from the drive IC 41 is transmitted through the wiring 471 provided on the protective substrate 47, the conduction hole, and the connection terminal, and is applied to the piezoelectric element 60. Thus, in the present embodiment, the piezoelectric element 60 and the drive IC 41 are provided in a layer structure via the protective substrate 47. In other words, the protective substrate 47 is disposed between the piezoelectric element 60 provided in the layer structure and the drive IC 41.

  Further, on the surface G2 of the protective substrate 47, a plurality of wirings 472 electrically connected to the drive IC 41 are formed. The drive wiring 401 is joined to the plurality of wirings 472. The drive wiring 401 is a member in which a plurality of wirings for transferring a plurality of signals input to the ejection module 40 to the drive IC 41 are formed, and is, for example, a flexible printed circuit (FPC), an FFC, etc. It is also good. The wiring 472 transfers control signals such as the print data signal SI, the latch signal LAT, the clock signal Sck, and the drive signals COMA, COMB, COMC, and the like input from the drive wiring 401 to the drive IC 41. As described above, the protective substrate 47 also functions as a relay substrate for mounting the drive IC 41 and transferring a signal for controlling the drive of the piezoelectric element 60.

  The flow path member 48 is a case for storing the ink supplied to the 2M pressure chambers C. The surface FB which is a surface on the medium P side of the flow path member 48 as viewed from the discharge module 40 is fixed to the surface FA of the flow path substrate 44 by, for example, an adhesive. A groove-shaped recess 481 extending in the direction X is formed on the surface FB of the flow path member 48. The protective substrate 47 and the drive IC 41 are accommodated inside the recess 481. At this time, the drive wiring 401 extends in the direction X so as to pass inside the recess 481.

  The flow path member 48 is formed, for example, by injection molding of a resin material. As shown in FIG. 7, in the flow path member 48, a flow path RB communicating with the flow path RA is formed. The flow path RA and the flow path RB function as a reservoir Q that stores the ink supplied to the 2M pressure chambers C.

  The ink supplied from the liquid container 50 is introduced to the reservoir Q via the filter member 250, the channel 242 and the channel 222 shown in FIG. 5 on the surface F2 which is the opposite surface of the surface FB of the channel member 48. Two openings 482 are provided for this purpose. The ink supplied from the liquid container 50 to the two openings 482 flows into the flow passage RA via the flow passage RB. Then, a part of the ink that has flowed into the flow passage RA is supplied to the pressure chamber C corresponding to the nozzle N via the flow passage 443 and the flow passage 441. The ink filled in the pressure chamber C corresponding to the nozzle N is discharged from the nozzle N via the flow path 442 by the drive of the piezoelectric element 60 corresponding to the nozzle N.

5. Generation of Drive Signal Vout Here, the electrical configuration of the ejection module 40 will be described with reference to FIGS. 9 to 13.

  As described above, the drive IC 41 included in the ejection module 40 receives various types of control signals including the print data signal SI, the latch signal LAT, and the clock signal Sck, and three types of drive signals COMA, COMB, and COMC. . Then, the drive IC 41 applies a drive signal Vout to one end of the piezoelectric element 60 included in the discharge unit 600 based on the input signal. As a result, the piezoelectric element 60 is driven and ink is ejected from the ejection unit 600. Therefore, first, one example of the three types of drive signals COMA, COMB, and COMC in the present embodiment will be described using FIG. 9, and thereafter, the electrical configuration and the drive signal of the ejection module 40 will be described using FIGS. The generation of Vout will be described.

  In the present embodiment, as described below, the print data signal SI includes a signal for causing the ejection unit 600 to eject the ink and a signal for preventing the ejection unit 600 from ejecting the ink. Further, as signals for preventing the discharge of the ink from the discharge unit 600, two types of signals are included: a signal for outputting the drive signal Vout for slightly vibrating the piezoelectric element 60 and a signal for not applying the drive signal Vout to the piezoelectric element 60.

As a method of ejecting ink by the drive signal Vout and forming dots on the medium P, a method of ejecting ink once in a unit period (ejection cycle) from the ejection unit 600 to form one dot (first method And ink can be ejected twice or more in a unit period, one or more inks ejected in a unit period are made to land, and one landed ink is combined to form one dot ((1) Second method), a method (third method) of forming two or more dots without combining these two or more inks, and the like can be mentioned.

  In the present embodiment, three gradations of “large dot”, “small dot” and “non-recording (no dot)” are expressed by the first method. In order to express these three gradations, three types of drive signals COMA, COMB and COMC are prepared. Then, in the printing cycle, the drive signals COMA, COMB, and COMC are selected or not selected according to the gradation to be expressed, and are applied to one end of the piezoelectric element 60 as the drive signal Vout.

  FIG. 9 is a diagram showing an example of voltage waveforms included in the drive signals COMA, COMB, COMC. As shown in FIG. 9, the drive signal COMA has a voltage waveform Adp arranged in a cycle Ta from the rise of the latch signal LAT to the rise of the latch signal LAT next. The cycle Ta is a printing cycle, and the drive signal COMA forms new dots on the medium P every cycle Ta. Specifically, assuming that the voltage waveform Adp is supplied to one end of the piezoelectric element 60, a predetermined amount, specifically, a large amount of ink is discharged from the discharge portion 600 (nozzle N) including the piezoelectric element 60. Let it discharge.

  The drive signal COMB is a voltage waveform Bdp arranged in a cycle Ta. The drive signal COMB forms new dots on the medium P every cycle Ta. Specifically, assuming that the voltage waveform Bdp is supplied to one end of the piezoelectric element 60, the discharge portion 600 (nozzle N) including the piezoelectric element 60 has a smaller amount than a predetermined amount, specifically, a small amount. Eject a volume of ink.

  The drive signal COMC is a voltage waveform Cdp arranged in a cycle Ta. The voltage waveform Cdp is a waveform for finely vibrating the piezoelectric element 60 to prevent an increase in the viscosity of the ink in the vicinity of the nozzle N of the corresponding ejection unit 600. Therefore, even if the voltage waveform Cdp is supplied to one end of the piezoelectric element 60, the ink is not ejected from the nozzle N corresponding to the piezoelectric element 60. That is, the voltage waveform Cdp included in the drive signal COMC is a waveform for driving the piezoelectric element 60 so that the ink is not discharged from the discharge unit 600.

  FIG. 10 is a view showing an electrical configuration of the ejection module 40. As shown in FIG. The ejection module 40 includes the drive IC 41 and the plurality of ejection units 600 as described above, and the drive IC 41 further includes the selection control unit 410 and the plurality of selection units 420.

  The selection control unit 410 includes a shift register (S / R) 412, a latch circuit 414, and a decoder 416. In the selection control unit 410, a set of a shift register 412, a latch circuit 414, and a decoder 416 is provided corresponding to each of the discharge units 600 (piezoelectric elements 60). That is, the number of sets of the shift register 412, the latch circuit 414, and the decoder 416 included in the drive IC 41 is the same as the total number 2M of the discharge units 600 (nozzles N) included in the discharge module 40.

  The selection control unit 410 is supplied with the clock signal Sck, the print data signal SI and the latch signal LAT. The print data signal SI is a signal including 2-bit print data (SIH, SIL) associated with each of the 2M discharge units 600.

The shift register 412 is configured to temporarily hold 2-bit print data (SIH, SIL) included in the print data signal SI for every 2M discharge units 600. More specifically, the shift registers 412 in stages corresponding to the ejection unit 600 are cascade-connected to one another, and the print data signal SI is sequentially transferred to the subsequent stage according to the clock signal Sck.

  In FIG. 10, in order to distinguish the plurality of shift registers 412, they are described as one stage, two stages,..., 2M stages in order from the upstream side to which the print data signal SI is supplied.

  Each of the 2M latch circuits 414 latches the 2-bit print data (SIH, SIL) held by each of the corresponding 2M shift registers 412 at the rise of a latch signal LAT.

  Each of 2M decoders 416 decodes 2-bit print data (SIH, SIL) latched by each of corresponding 2M latch circuits 414, and selects selection signals Sa, Sb, Sc for each cycle Ta. Are output to the selection unit 420.

  FIG. 11 is a diagram showing an example of the decoding content of the decoder 416 in the present embodiment.

  In FIG. 11, when the 2-bit print data (SIH, SIL) is, for example, (1, 0), the decoder 416 sets the logic level of the selection signal Sa in the period Ta to L level and the logic level of the selection signal Sb. Is set to H level, and the logic level of the selection signal Sc is output as L level.

  The logic levels of the selection signals Sa, Sb, and Sc are shifted to higher amplitude logic by a level shifter (not shown) than the logic levels of the clock signal Sck, the print data signal SI, and the latch signal LAT.

  Referring back to FIG. 10, the selection unit 420 selects or not selects the drive signals COMA, COMB, and COMC based on the selection signals Sa, Sb, and Sc input from the selection control unit 410, and selects a plurality of ejections as the drive signal Vout. It outputs to each of the part 600 (piezoelectric element 60). The selection unit 420 is provided corresponding to each of the piezoelectric elements 60. Therefore, the number of selection units 420 included in the drive IC 41 is the same as the total number 2M of the nozzles N included in the ejection module 40.

  FIG. 12 is a diagram showing the configuration of the selection unit 420 corresponding to one discharge unit 600. As shown in FIG. 12, the selection unit 420 includes inverters 422 a, 422 b and 422 c and transfer gates 424 a, 424 b and 424 c.

  Selection signals Sa, Sb, and Sc are input from the decoder 416 to the selection unit 420.

  The selection signal Sa is supplied to the non-rounded positive control end in the transfer gate 424a while being logically inverted by the inverter 422a and supplied to the circled negative control end in the transfer gate 424a. Ru. The transfer gate 424a conducts between the input end and the output end when the selection signal Sa is at the H level, and does not conduct between the input end and the output end when the selection signal Sa is at the L level. Thus, when the selection signal Sa is at the H level, the transfer gate 424a outputs the drive signal COMA supplied to the input terminal, and when the selection signal Sa is at the L level, the transfer gate 424a does not output a signal.

Similarly, while the selection signal Sb is supplied to the non-rounded positive control terminal in the transfer gate 424b, the negative control terminal is logically inverted by the inverter 422b and is circled in the transfer gate 424b. Supplied to The transfer gate 424b conducts between the input end and the output end when the selection signal Sb is at the H level, and does not conduct between the input end and the output end when the selection signal Sb is at the L level. Thus, when the selection signal Sb is at the H level, the transfer gate 424b outputs the drive signal COMB supplied to the input terminal, and when the selection signal Sb is at the L level, the transfer gate 424b does not output a signal.

  Similarly, while the selection signal Sc is supplied to the non-rounded positive control end in the transfer gate 424c, the negative control end is logically inverted by the inverter 422c and circled in the transfer gate 424c. Supplied to The transfer gate 424c conducts between the input end and the output end when the selection signal Sc is at the H level, and does not conduct between the input end and the output end when the selection signal Sc is at the L level. Thus, when the selection signal Sc is at the H level, the transfer gate 424c outputs the drive signal COMC supplied to the input terminal, and when the selection signal Sc is at the L level, the transfer gate 424c does not output a signal.

  The output ends of the transfer gates 424 a, 424 b, and 424 c are commonly connected, and the drive signal Vout is output to the discharge unit 600 through the common connection terminal.

  As described above, the selection unit 420 selects the drive signals COMA, COMB, and COMC based on the selection signals Sa, Sb, and Sc from the decoder 416, and switches whether to apply the drive signals Vout to the piezoelectric element 60 or not. At this time, the drive signals COMA, COMB, COMC are voltage signals having a voltage amplitude high enough to drive the piezoelectric element 60 (for example, 42 Vpeak), and conduction or non-conduction of such drive signals COMA, COMB, COMC. It is preferable that the selection signals Sa, Sb, and Sc that control the signal more reliably be high voltage signals.

  Here, details of the operation of the drive IC 41 will be described with reference to FIG.

  When the print data signal SI synchronized with the clock signal Sck is supplied as a serial signal to the selection control unit 410, the print data signal SI is sequentially transferred in the shift register 412 corresponding to each of the plurality of ejection units 600. Then, when the supply of the clock signal Sck is stopped, 2-bit print data (SIH, SIL) to be supplied to the corresponding discharge unit 600 (piezoelectric element 60) is held in each of the shift registers 412. The print data signal SI is supplied in the order corresponding to the final 2M stages,..., Two stages, and one stage of nozzles in the shift register 412.

  Here, when the latch signal LAT rises, each of the latch circuits 414 latches the 2-bit print data (SIH, SIL) held in the shift register 412 all at once. 13, LT1, LT2,..., LT2M indicate 2-bit print data (SIH, SIL) latched by the latch circuit 414 corresponding to the shift register 412 of one stage, two stages,. There is.

  The decoder 416 outputs the latched 2-bit print data (SIH, SIL) as the selection signals Sa, Sb, Sc in the cycle Ta according to the definition of FIG.

Specifically, when the print data (SIH, SIL) is (1, 1), the decoder 416 selects the H level in the cycle Ta as the selection signal Sa and the L level in the cycle Ta as the selection signal Sb. Further, the L level is output to the selection unit 420 in the cycle Ta as the selection signal Sc. As a result, only the transfer gate 424a to which the selection signal Sa is input in the period Ta is conducted. Therefore, the drive signal COMA (voltage waveform Adp) is selected and output as the drive signal Vout. At this time, a large amount of ink is ejected from the ejection unit 600 corresponding to the selection unit 420 to which the signal is input among the plurality of selection units 420, and large dots are formed on the medium P.

  Further, when the print data (SIH, SIL) is (1, 0), the decoder 416 selects the L level in the cycle Ta as the selection signal Sa and the H level in the cycle Ta as the selection signal Sb. The L level is output to the selection unit 420 in the cycle Ta as the selection signal Sc. Thus, only the transfer gate 424b to which the selection signal Sb is input in the period Ta is conducted. Therefore, the drive signal COMB (voltage waveform Bdp) is selected and output as the drive signal Vout. At this time, a small amount of ink is ejected from the ejection unit 600 corresponding to the selection unit 420 to which the signal is input among the plurality of selection units 420, and small dots are formed on the medium P.

  When the print data (SIH, SIL) is (0, 1), the decoder 416 selects L level in the cycle Ta as the selection signal Sa and L level in the cycle Ta as the selection signal Sb. The H level is output to the selection unit 420 in the cycle Ta as the selection signal Sc. As a result, only the transfer gate 424c to which the selection signal Sc is input in the period Ta is conducted. Therefore, the drive signal COMC (voltage waveform Cdp) is selected and output as the drive signal Vout. At this time, among the plurality of selection units 420, the piezoelectric element 60 included in the discharge unit 600 corresponding to the selection unit 420 to which the signal is input vibrates slightly. Therefore, since the ink is not discharged from the discharge unit 600, no dot is formed on the medium P.

  In addition, when the print data (SIH, SIL) is (0, 0), the decoder 416 selects L level in the cycle Ta as the selection signal Sa and L level in the cycle Ta as the selection signal Sb. The L level is output to the selection unit 420 in the cycle Ta as the selection signal Sc. As a result, all of the transfer gates 424a, 424b, and 424c become nonconductive. Therefore, among the plurality of selection units 420, the selection unit 420 to which the signal is input does not output the drive signal Vout. At this time, the piezoelectric element 60 included in the discharge unit 600 corresponding to the selection unit 420 is not driven. Therefore, since the ink is not discharged from the discharge unit 600, no dot is formed on the medium P.

  As described above, the print data signal SI includes a plurality of signals for causing the ejection unit 600 to eject the ink, and a signal for causing the ejection unit 600 not to eject the ink. Furthermore, in the present embodiment, as a signal that does not eject the ink from the ejection unit 600, a signal that outputs the drive signal Vout that slightly vibrates the piezoelectric element 60 and a signal that does not apply the drive signal Vout to the piezoelectric element 60 Includes various types of signals.

  The drive signals COMA, COMB and COMC shown in FIG. 9 are merely examples. In practice, a combination of various waveforms prepared in advance is used according to the transport speed and properties of the medium P. The print data (SIH, SIL) shown in FIG. 11 is merely an example, and may be composed of, for example, three or more bits of data.

6. In the liquid discharge apparatus 1 as described above, each of the drive signals COMA, COMB, COMC for driving the piezoelectric element 60 generated by the drive circuit 14 has a voltage waveform with a large amplitude. Is a signal including Therefore, the selection unit 420 of the drive IC 41 which selects one of the drive signals COMA, COMB, and COMC as the drive signal Vout and supplies it as the drive signal Vout to the piezoelectric element 60 has a current and a voltage based on the drive signal Vout. It is supplied and generates heat.

  Such heat generation becomes large when driving the piezoelectric element 60 so that the ink is ejected from the nozzle N at the frequency of 16000 times or more (16000 Hz or more) of the drive signal Vout in the selection unit 420. .

  Further, when the ejection module 40 is arranged in parallel at a high density of 300 or more per inch and 600 or more nozzles N (piezoelectric elements 60) are provided, the selection portion 420 is also provided in the drive IC 41 at a high density. Therefore, the heat generation amount per unit area of the drive IC 41 also increases with the heat generation of the selection unit 420.

  Furthermore, as shown in FIGS. 7 and 8, in order to miniaturize and increase the density of the ejection module 40, the protective substrate 47 provided with the drive IC 41 is disposed in the vicinity of the ejection portion 600, and the periphery is a flow path member When it is covered by 48, the drive IC 41 does not come in contact with the outside air of the discharge module 40. Alternatively, the area in which the drive IC 41 and the protection substrate 47 come in contact with the air outside the discharge module 40 is reduced. As a result, the heat dissipation efficiency of the drive IC 41 may be reduced to a high temperature.

  On the other hand, by arranging the drive IC 41 and the protective substrate 47 in the space surrounded by the reservoir Q and the pressure chamber C of the ejection module 40 as shown in FIGS. 7 and 8, the heat generated by the drive IC 41 is Heat is dissipated through the ink supplied to the inside of the reservoir Q and the pressure chamber C. Thereby, when the ink is discharged from the nozzle N, a large heat radiation effect can be obtained. Specifically, fresh ink is supplied from the liquid container 50 to the reservoir Q through the opening 482 as the ink is discharged, and the rise in the ink temperature in the reservoir Q and the pressure chamber C is reduced. Thus, the drive IC 41 dissipates heat efficiently through the ink in the reservoir Q and the pressure chamber C.

  However, generally, the piezoelectric element 60 is driven to such an extent that the ink is not ejected from the nozzle N to the piezoelectric element 60 corresponding to the nozzle N from which the ink is not ejected (hereinafter, referred to as "fine vibration") Drive signal Vout is supplied. Such minute vibration causes the ink in the vicinity of the opening of the nozzle N to be agitated to prevent an increase in the viscosity of the ink. At this time, since the drive IC 41 (select unit 420) supplies the drive signal Vout to the piezoelectric element 60 as in the case of discharging the ink, the drive IC 41 generates heat as in the case of discharging the ink. On the other hand, new ink is not supplied to the reservoir Q from the liquid container 50 unlike in the case of discharging the ink. Therefore, when fine vibration is continuously performed on a specific nozzle N, the heat generated by the selection unit 420 corresponding to the nozzle N is accumulated, and the accumulated heat is stored in the reservoir Q and the pressure chamber C. The temperature of the drive IC 41 (selection unit 420) rises when the amount of heat released through the ink in the above is exceeded. Then, as the temperature of the drive IC 41 rises, the ink temperature inside the reservoir Q and the pressure chamber C rises, the viscosity of the ink changes as the ink temperature rises, and the ejection accuracy of the liquid ejection device 1 deteriorates. there is a possibility.

  The temperature (temperature rise) of the head unit 20 and the ejection module 40 is detected with respect to the deterioration of the ejection accuracy of the liquid ejection device 1 caused by the temperature rise of the ink as described above, and the drive circuit 14 A method of correcting the voltage amplitude, voltage waveform and the like of the generated drive signals COMA, COMB and COMC may be used.

As described above, one of the causes of heat generation in the drive IC 41 is heat generation of the selection unit 420, and the selection unit 420 is provided corresponding to each of the plurality of discharge units 600 provided in the discharge module 40. . Therefore, the temperature of the ink may be different for each of the plurality of ejection units 600. In other words, the temperature distribution inside the ejection module 40 is not uniform, and furthermore, when a plurality of ejection modules 40 are provided in the head unit 20, the temperature distribution among the plurality of ejection modules 40 is also not uniform.

  In the present embodiment, the drive signals COMA, COMB, COMC generated by the drive circuit 14 are configured to be commonly supplied to one or a plurality of ejection modules 40 as shown in FIG. As illustrated, the configuration is also commonly supplied to the plurality of selection units 420 and the plurality of discharge units 600. Therefore, the temperature (temperature rise) of the head unit 20 and the ejection module 40 is detected, and the voltage amplitude, voltage waveform, etc. of the drive signals COMA, COMB, COMC generated by the drive circuit 14 based on the detected temperature. In order to perform the correction, it is required that the temperature distribution of the head unit 20 and the ejection module 40 be substantially uniform.

  Here, ideally, the temperature distribution of the plurality of discharge units 600 provided in each of the plurality of discharge modules 40 of the head unit 20 is preferably the same, that the temperature distribution is substantially uniform, specifically, It is preferable that the temperature difference (or the difference between the temperature rise values) of each of the plurality of ejection modules 40 of the head unit 20 and the plurality of ejection units 600 be 5 ° C. or less.

  Further, in the present embodiment, as described above, the drive signal Vout for slightly vibrating the piezoelectric element 60 is output as the signal for preventing the discharge of the ink from the discharge unit 600, and the drive signal Vout is not applied to the piezoelectric element 60; including. As a result, the application of the drive signal Vout that causes the micro vibration to continue to the piezoelectric element 60 corresponding to the specific nozzle N is reduced. Therefore, the heat quantity stored in the drive IC 41 and the temperature rise of the drive IC 41 can be reduced based on the slight vibration.

7. The effect of forming the holder from aluminum With respect to such problems, the head unit 20 in the present embodiment discharges the nozzle N, the piezoelectric element 60, and the drive IC 41 provided on the piezoelectric element 60. A module 40 and a holder 220 (an example of a “housing”) provided to cover the discharge module 40 are provided, and at least a part of the holder 220 is formed of aluminum.

  Here, "aluminum" may be pure aluminum, or may be an aluminum alloy in which magnesium, silicon, manganese, copper, zinc or the like is added to pure aluminum. Such aluminum is 0.23 kW / (m · ° C) for pure aluminum, 0.15 to 0.22 kW / (m · ° C) and iron (0.08 kW / (m · ° C)) for aluminum alloys, etc. It has high thermal conductivity in comparison with.

  Specifically, in the head unit 20 shown in FIG. 3, FIG. 5 and FIG. 6, the ejection module 40 including the drive IC 41 generating heat is fixed with the housing portion 221 of the holder 220 provided to cover the ejection module 40. It is arrange | positioned in the accommodation space formed of the board 210 and. At this time, the holder 220 is formed of aluminum.

  As described above, by forming the holder 220 of aluminum having a high thermal conductivity, it is possible to efficiently dissipate the heat generated by the discharge module 40 provided in the housing portion 221. Thus, the temperature increase of the ink supplied to the plurality of flow paths provided in the ejection module 40 and the ejection unit 600 is reduced.

  Further, when the head unit 20 is provided with a plurality of ejection modules 40 as shown in FIG. 3 to FIG. 6, the heat generated in each of the plurality of ejection modules 40 is accommodated by the heat conduction of the aluminum forming the holder 220. The light is diffused to the inside and the outside of the space formed by the portion 221. Thereby, the temperature difference which arises between the some discharge modules 40 provided in the head unit 20 can be made small. In other words, the temperature distribution of the head unit 20 and the ejection module 40 can be made substantially uniform.

  In addition, the holder 220 and the discharge module 40 should just be provided so that the heat which arose with the discharge module 40 can be efficiently conducted via aluminum. Therefore, it is preferable that the holder 220 and the ejection module 40 be provided in contact with each other. The holder 220 may be provided so as to be able to efficiently conduct the heat generated by the discharge module 40. For example, the holder 220 may not be in contact with the discharge module 40. It may be in contact via the configuration. Furthermore, in order to enhance the efficiency of heat conduction, it is preferable that the holder 220 be entirely made of aluminum, but it is sufficient if the temperature difference generated between the plurality of ejection modules 40 can be reduced. For example, the ejection modules 40 are arranged A part including the concave portion forming the housing portion 221 may be formed of aluminum.

  Furthermore, in addition to high thermal conductivity, the holder 220 is preferably made of aluminum from the viewpoints of strength, corrosion resistance, material cost, and the like. On the other hand, the head unit 20 may be formed of different materials depending on the use environment and application of the liquid discharge device 1 provided. Specifically, the holder 220 may be formed including a material having a thermal conductivity higher than 0.10 kW / (m · ° C.), and may be formed of, for example, gold, silver, copper or the like.

  Here, an effect obtained by forming the holder 220 of aluminum will be described with reference to FIGS. 14 to 16. Specifically, the head unit 20 in which the holder 220 is made of resin and the head unit 20 in which the holder 220 is made of aluminum are operated under the same conditions. A description will be given based on the temperature rise values of the plurality of ejection modules 40 provided in the head unit 20 at this time.

  FIG. 14 is a diagram for explaining the arrangement of the ejection modules 40 provided in the head unit 20 used for the confirmation of the temperature rise value. Moreover, FIG. 15 is a figure which shows the confirmation result of each temperature rise value of several discharge module 40 with which the holder 220 is equipped with the head unit 20 formed with resin. FIG. 16 is a diagram showing the confirmation results of the temperature rise values of the plurality of ejection modules 40 provided in the head unit 20 in which the holder 220 is formed of aluminum.

  As shown in FIG. 14, twelve discharge modules 40 are provided in the head unit 20 used for the confirmation of the temperature rise value. Specifically, three ejection modules 40 are juxtaposed in the longitudinal direction of the head unit 20, and a row of three ejection modules 40 juxtaposed is provided in four rows in the lateral direction of the head unit 20. ing. At this time, the ejection modules 40 provided in rows adjacent to each other in the short direction of the head unit 20 are arranged in a so-called staggered manner so that the positions in the long side direction are different. The twelve ejection modules 40 provided in the head unit 20 may be referred to as ejection modules H01 to H12 for the sake of convenience.

  In the confirmation of the temperature rise value, among the twelve ejection modules 40, the ejection modules H05 and H06 operate such that ink is ejected from all the provided nozzles N, while the ejection modules H05 and H06 The ten ejection modules H01 to H04 and H07 to H12 except the above operate so as not to eject ink from all the provided nozzles N. That is, the ejection modules H05 and H06 can eject heat efficiently through the supplied ink, and are the ejection modules 40 in which the temperature rise of the ink and the drive IC 41 is reduced. On the other hand, the ejection modules H01 to H04 and H07 to H12 are ejection modules 40 in which the heat radiation effect of the ink stored inside is reduced and the temperature rise of the ink and the drive IC 41 is concerned.

FIG. 15 shows the results of confirmation of the temperature rise value of the ejection module 40 provided in the head unit 20 in which the holder 220 is formed of resin under the above-described conditions.

  As shown in FIG. 15, while the temperature increase values of the discharge modules H05 and H06 are both 4 ° C. or less, the temperature increase values of the discharge modules H01 to H04 and H07 to H12 which may cause a temperature increase are all Also, the temperature rise value of the discharge module H09 exceeds 9 ° C.

  As described above, in the head unit 20 in which the holder 220 is formed of resin, the difference in the temperature rise value among the plurality of ejection modules 40 (H01 to H12) provided in the head unit 20 becomes large. Therefore, for example, the temperature (temperature rise) of at least one of the head unit 20 and the ejection module 40 is detected, and the voltage amplitude, voltage waveform, and the like of the drive signals COMA, COMB, and COMC are corrected based on the detected temperature. In this case, it becomes difficult to determine the temperature that is the basis of correction. In addition, when the reference temperature is uniquely determined, the difference between the temperature rise values among the plurality of ejection modules 40 (H01 to H12) is large, and the voltage amplitudes and voltage waveforms of the drive signals COMA, COMB and COMC are corrected. Accuracy of

  FIG. 16 shows the results of confirmation of the temperature rise value of the ejection module 40 provided in the head unit 20 in which the holder 220 is formed of aluminum under the same conditions as in FIG.

  As shown in FIG. 15, by forming the holder 220 from aluminum, the temperature increase values of all of the ejection modules H01 to H12 provided in the head unit 20 become 4 ° C. to 5 ° C., and a plurality of ejection modules 40 are obtained. The difference in the temperature rise value between (H01 to H12) is 1 ° C. or less. That is, by forming the holder 220 of aluminum, the variation in the temperature distribution of the head unit 20 is reduced.

  Thereby, for example, the temperature (temperature rise) of at least one of the head unit 20 and the ejection module 40 is detected, and the voltage amplitude, voltage waveform, etc. of the drive signals COMA, COMB, COMC are corrected based on the detected temperature. When this is done, it becomes possible to uniquely determine the reference temperature of the head unit 20 or the ejection module 40. Therefore, the accuracy of the correction can be improved.

  Furthermore, the heat radiation effect is promoted by forming the holder 220 of aluminum, and the temperature rise of the ejection modules H01 to H04 and H07 to H12 from which the ink is not ejected is also reduced.

7. As described above, in the head unit 20 according to the present embodiment, the thermal conductivity such as aluminum is 0.10 kW / (m · ° C.) so as to cover the ejection module 40 including the driving IC 41 with large heat generation. By providing the holder 220 formed of a high material, the heat generated by the drive IC 41 is diffused through the high thermal conductivity aluminum forming the holder 220. Furthermore, even when the head unit 20 includes the plurality of ejection modules 40, the temperature difference between the plurality of ejection modules 40 can be reduced. Thereby, the concentration of heat in the head unit 20 is reduced, and the occurrence of variations in temperature distribution can be reduced.

Further, in the head unit 20 according to the present embodiment, the ejection module 40 is accommodated in the accommodation portion 221 of the holder 220 formed of aluminum, and the heat generated by the ejection module 40 is efficiently dissipated through the aluminum. Therefore, the temperature rise of the discharge module 40 including the drive IC 41 can be reduced. Thereby, the heat concentration in the head unit 20 is further reduced, and the occurrence of variations in temperature distribution is further reduced.

  As described above, in the head unit 20 according to the present embodiment, heat concentration can be suppressed, and the heat radiation effect can be further improved. Therefore, even if the ejection module 40 is arranged in parallel at a high density of 300 or more per inch and 600 or more nozzles N (piezoelectric elements 60) are provided, the temperature concentration of the head unit 20 and the ejection module 40 The temperature rise can be reduced. Similarly, when driving the piezoelectric element 60 so that the ink is ejected from the nozzle N at a frequency of 16000 times or more (16000 Hz or more) of the drive signal Vout, the head unit 20 and the ejection module 40 are similarly Temperature concentration and temperature rise can be reduced. As a result, even if the temperature rise of the head unit 20 and the ejection module 40 occurs, the drive signals COMA, COMB, COMC can be properly corrected.

8. Modifications Although the liquid ejection device 1 has been described as a line printer in the present embodiment, the head unit 20 may be a serial printer that performs printing by moving in a direction orthogonal to the conveyance direction of the medium P. Good.

  As mentioned above, although this embodiment or modification was described, the present invention is not limited to these this embodiment or modification, and it is possible in a range which does not deviate from the gist to carry out in various modes. For example, it is also possible to combine the above-mentioned embodiment and each modification suitably.

  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, 10 ... Control unit, 11 ... Control circuit, 12 ... Control signal conversion circuit, 13 ... Control signal transmission circuit, 14 ... Drive circuit, 20 ... Head unit, 22 ... Control signal restoration circuit, 23 ... Control Signal reception circuit, 30: transport unit, 40: discharge module, 41: drive IC, 43: absorber, 44: flow path substrate, 45: pressure chamber substrate, 46: vibration portion, 47: protection substrate, 48: flow path Members 49 nozzle plate 50 liquid container 60 piezoelectric element 200 head unit main body 210 fixing plate 211, 451, 482 opening portion 220 holder 221 storage portion 222, 242 253, 441, 442, 443, RA, RB: flow path, 223, 231, 243: insertion hole, 230: circuit board, 232: insertion hole, 233: connector, 240: supply member 241: projection part 250: filter member 251: filter unit 254: filter 260: external wiring 401: drive wiring 410: selection control section 412: shift register 414: latch circuit 416: decoder 420 ... Selection part, 471, 472 ... Wiring, 473 ... Accommodation space, 481 ... Concave part, 600 ... Discharge part, 422a, 422b, 422c ... Inverter, 424a, 424b, 424c ... Transfer gate, C ... Pressure chamber, N ... Nozzle, P: Medium, Q: Reservoir

Claims (6)

300 or more nozzles per inch and 600 or more nozzles, a piezoelectric element for discharging liquid from the nozzles, and a drive signal provided on the piezoelectric element for driving the piezoelectric element A discharge module including a drive IC;
A housing provided to cover the discharge module;
Equipped with
At least a portion of the housing is formed of aluminum,
Print head characterized by The housing has a recess formed at least in part of aluminum,
The discharge module is disposed between the recess and the fixing plate.
The print head according to claim 1, characterized in that: The discharge module includes a protective substrate disposed between the piezoelectric element and the drive IC.
The protective substrate forms a protective space on the piezoelectric element side to protect the piezoelectric element.
The print head according to claim 1 or 2, characterized in that: Comprising a plurality of said discharge modules,
The print head according to any one of claims 1 to 3, characterized in that: The nozzle discharges the liquid at a frequency of 16000 Hz or higher.
The print head according to any one of claims 1 to 4, characterized in that: 300 or more nozzles per inch and 600 or more nozzles, a piezoelectric element for discharging liquid from the nozzles, and a drive signal provided on the piezoelectric element for driving the piezoelectric element A discharge module including a drive IC;
A housing provided to cover the discharge module;
Equipped with
The housing contains a material having a thermal conductivity higher than 0.10 kW / (m · ° C.),
Print head characterized by

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