Patent ID: 12257831

DESCRIPTION OF EXEMPLARY EMBODIMENTS

An embodiment of the present disclosure will be described below with reference to the accompanying drawings. However, in each of the drawings below, dimensions and a scale of each part are different from actual ones as appropriate. The embodiment described below is a preferable concreate example of the present disclosure, and therefore, have various kinds of technically preferred limitations. The scope of the present disclosure, however, is not limited to such embodiments unless there is any description specifically limiting the present disclosure in the following description.

A. EMBODIMENT

In this embodiment, a liquid ejecting apparatus will be described using, as an example, an ink jet printer that ejects ink to form an image on recording paper PP.

1. Outline of Ink Jet Printer

An example of a configuration of an ink jet printer1according to this embodiment will be described below with reference toFIG.1toFIG.3.

FIG.1a functional block diagram illustrating an example of a configuration of the ink jet printer1.

As illustrated inFIG.1, print data Img indicating an image that the ink jet printer1is to form is supplied to the ink jet printer1from a host computer, such as a personal computer, a digital camera, or the like. The ink jet printer1executes print processing of forming the image indicated by the print data Img supplied from the host computer on the recording paper PP. Note that the recording paper PP is an example of a “medium”.

The ink jet printer1includes a control unit2that controls each component of the ink jet printer1, a head unit3in which an ejection portion D that ejects ink is provided, a driving signal generation unit4that generates a driving signal Com to drive the ejection portion D, and a transport unit7that changes a relative position of the recording paper PP with respect to the head unit3. Note that the ink jet printer1is an example of a “liquid ejecting apparatus”, and the driving signal generation unit4that generates the driving signal Com to drive the ejection portion D includes, for example, one or more electric circuits and is an example of a “driving circuit”.

In this embodiment, a reactive ink is used as the ink that is ejected from the ejection portion D by the ink jet printer1. Herein, the term “reactive ink” is a generic term for solvent inks, photoreactive inks, textile printing inks, and pretreatment inks. Among the above-described inks, the solvent inks are inks each in which a color material, such as a pigment, a dye, or the like, is dispersed in any one of solvents of various types, such as an oily solvent, an aqueous solvent, or the like. As for the solvent inks, for example, JP-A-2014-80539 discloses a solvent ink. The photoreactive inks are inks whose properties are changed through light irradiation. Examples of the photoreactive inks include, for example, an ultraviolet curing ink that is cured through irradiation of ultraviolet rays. As for the photoreactive inks, for example, JP-A-2015-174077 discloses a photoreactive ink. Textile printing inks are inks suitable for printing of textiles. As for the textile printing inks, for example, JP-A-2017-222943 discloses a textile printing ink. Pretreatment inks are inks that are applied to textiles in advance as pretreatment before printing. As for the pretreatment inks, for example, JP-A-2004-143621 discloses a pretreatment ink. The reactive inks described above tend to be high in aggressiveness to organic materials, as compared to aqueous inks.

In this embodiment, it is assumed that the ink jet printer1includes one or more head units3and one or more driving signal generation units4corresponding to the one or more head units3on a one-to-one basis. Specifically, in this embodiment, it is considered that the ink jet printer1includes four head units3and four driving signal generation units4corresponding to the four head units3on a one-to-one basis. However, in the following, for convenience, as illustrated inFIG.1, description is sometimes made with focus on one head unit3of the four head units3and one driving signal generation unit4of the four driving signal generation units4that is provided to correspond to the one head unit3.

The control unit2includes one or more CPUs. However, the control unit2may include, instead of the one or more CPUs or in addition to the one or more CPUs, a programmable logic device, such as a FPGA or the like. As used herein, the term “CPU” is an abbreviation for central processing unit, and the term “FPGA” is an abbreviation for field-programmable gate array. The control unit2includes memory. The memory includes one or both of volatile memory and nonvolatile memory. Examples of volatile memory include random access memory (RAM) or the like, and examples of nonvolatile memory include read only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable ROM (PROM), or the like.

Although details will be described later, the control unit2generates signals, such as a print signal SI, a waveform designation signal dCom, or the like, to control an operation of components of the ink jet printer1.

Herein, the term “waveform designation signal dCom” refers to a digital signal that defines a waveform of a driving signal Com. The term “driving signal Com” refers to an analog signal that drives the ejection portion D. The driving signal generation unit4includes a digital-to-analogue (DA) conversion circuit and generates the driving signal Com having a waveform defined by the waveform designation signal dCom. The print signal SI is a digital signal that designates a type of an operation of the ejection portion D. Specifically, the print signal SI is a signal that designates a type of an operation of the ejection portion D by designating whether to supply the driving signal Com to the ejection portion D.

As illustrated inFIG.1, the head unit3includes a supply circuit31and a recording head32.

The recording head32includes M ejection portions D. Herein, a value M is a natural number that satisfies “M≥1”. In the following, among the M ejection portions D provided in the recording head32, an mth ejection portion D will be sometimes referred to as an ejection portion D[m]. Herein, a variable m is a natural number that satisfies “1≥m≥M”. In the following, when a component element of the ink jet printer1, a signal, or the like corresponds to the ejection portion D[m] among the M ejection portions D, a suffix [m] is sometimes attached to a sign representing the component element, the signal, or the like.

The supply circuit31switches, based on the print signal SI, whether the driving signal Com is supplied to the ejection portion D[m]. Note that, among the driving signals Com, a driving signal Com supplied to the ejection portion D[m] will be hereinafter sometimes referred to as a supply driving signal Vin[m].

As described above, in this embodiment, the ink jet printer1executes print processing. When the print processing is executed, the control unit2generates, based on the print data Img, a signal, such as the print signal SI or the like, that controls the head units3. When the print processing is executed, the control unit2generates a signal, such as the waveform designation signal dCom or the like, that controls the driving signal generation unit4. Moreover, when the print processing is executed, the control unit2generates a signal that controls the transport unit7. Thus, in the print processing, the control unit2controls the components of the ink jet printer1to adjust whether to eject ink from the ejection portion D[m], an ink ejection amount, an ink ejection timing, or the like such that an image corresponding to the print data Img is formed on the recording paper PP, while controlling the transport unit7to change the relative position of the recording paper PP with respect to the head unit3.

FIG.2is a perspective view illustrating an example of a schematic internal structure of the ink jet printer1.

As illustrated inFIG.2, in this embodiment, it is assumed that the ink jet printer1is a serial printer. Specifically, in executing print processing, while transporting the recording paper PP in an X1direction, the ink jet printer1ejects ink from the ejection portion D[m] with the head units3reciprocated in a Y1direction crossing the X1direction and a Y2direction that is an opposite direction of the Y1direction, so that dots Dt corresponding to the print data Img are formed on the recording paper PP.

Hereinafter, the X1direction and an X2direction that is an opposite direction of the X1direction will be collectively referred to as an “X-axis direction”, the Y1direction crossing the X-axis direction and the Y2direction that is the opposite direction of the Y1direction will be collectively referred to as a “Y-axis direction”, and a Z1direction crossing the X-axis direction and the Y-axis direction and a Z2direction that is an opposite direction of the Z1direction will be referred to as a “Z-axis direction”. In this embodiment, as an example, it is assumed that the X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to each other. However, the present disclosure is not limited thereto. It is sufficient that the X-axis direction, the Y-axis direction, and the Z-axis direction cross each other. Note that, in this embodiment, the Z1direction is a direction in which the ink is ejected from the ejection portion D[m].

As illustrated inFIG.2, the ink jet printer1according to this embodiment includes a housing100and a carriage110that is configured to reciprocally move in the Y-axis direction in the housing100and on which the four head units3are mounted.

In this embodiment, as illustrated inFIG.2, it is assumed that the carriage110stores four ink cartridges120corresponding to inks of four colors, that is, cyan, magenta, yellow, and black, on a one-to-one basis. In this embodiment, as described above, it is assumed that the ink jet printer1includes the four head units3corresponding to the four ink cartridges120on a one-to-one basis. Each ejection portion D[m] receives supply of the ink from one of the ink cartridges120corresponding to the head unit3in which the ejection portion D[m] is provided. Thus, inside of each ejection portion D[m] is filled with the supplied ink and the ejection portion D[m] can eject the filling ink from a nozzle N. Note that the ink cartridges120may be provided outside the carriage110.

As described above, the ink jet printer1according to this embodiment includes the transport unit7. As illustrated inFIG.2, the transport unit7includes a carriage transport mechanism71that reciprocally moves the carriage110in the Y-axis direction, a carriage guide shaft76that supports the carriage110reciprocablly in the Y-axis direction, a medium transport mechanism73that transports the recording paper PP, and a platen75provided in the Z1direction of the carriage110. Therefore, when print processing is executed, the transport unit7changes a relative position of the recording paper PP with respect to the head units3to allow the ink to land on entire recording paper PP by reciprocating the head units3with the carriage110in the Y-axis direction along the carriage guide shaft76by the carriage transport mechanism71and transporting the recording paper PP on the platen75in the X1direction by the medium transport mechanism73.

FIG.3is a schematic partial sectional view of the recording head32obtained by cutting the recording head32such that a cross section includes the ejection portion D[m].

As illustrated inFIG.3, the ejection portion D[m] includes a piezoelectric element PZ[m], a cavity CV inside of which is filled with an ink, a nozzle N that communicates with the cavity CV, and a vibration plate321. The ejection portion D[m] ejects the ink in the cavity CV from the nozzle N by driving the piezoelectric element PZ[m] with the supply driving signal Vin[m]. The cavity CV is a space defined by a cavity plate324, a nozzle plate323in which the nozzle N is formed, and the vibration plate321. The cavity CV communicates with a reservoir325via an ink supply port326. The reservoir325communicates with the ink cartridge120corresponding to the ejection portion D[m] via an ink inlet port327. The piezoelectric element PZ[m] includes an upper electrode Zu[m], a lower electrode Zd[m], a piezoelectric body Zm[m] provided between the upper electrode Zu[m] and the lower electrode Zd[m]. The lower electrode Zd[m] is electrically coupled to a feeder line LD set to a potential VBS. Then, when the supply driving signal Vin[m] is supplied to the upper electrode Zu[m] and thus a voltage is applied between the upper electrode Zu[m] and the lower electrode Zd[m], the piezoelectric element PZ[m] is displaced in the Z1direction or the Z2direction in accordance with the applied voltage, so that the piezoelectric element PZ[m] vibrates. The lower electrode Zd[m] is joined to the vibration plate321. Therefore, when the piezoelectric element PZ[m] is driven by the supply driving signal Vin[m] to vibrate, the vibration plate321also vibrates. A volume of the cavity CV and a pressure in the cavity CV change due to vibration of the vibration plate321and thus the ink with which the cavity CV is filled is ejected from the nozzle N.

Note that a portion of the ink ejected from the nozzle N in the print processing becomes mist before hitting the recording paper PP and floats in the housing100.

2. Outline of Head Unit

An outline of the head unit3will be described below with reference toFIG.4toFIG.6.

FIG.4is a block diagram illustrating an example of a configuration of the head unit3.

As illustrated inFIG.4, the head unit3includes the supply circuit31and the recording head32. The head unit3includes wiring LC through which the driving signal Com is supplied from the driving signal generation unit4.

As illustrated inFIG.4, the supply circuit31includes M switches WS[1] to WS[M] corresponding to the M ejection portions D[1] to D[M] on a one-to-one basis and a coupling state designation circuit310that designates a coupling state of each switch.

The coupling state designation circuit310generates a coupling state designation signal QS[m] that designates on and off of a switch WS[m], based on at least some of the print signal SI, a latch signal LAT, and a change signal CH supplied from the control unit2.

The switch WS[m] switches, based on the coupling state designation signal QS[m], between conduction and non-conduction between the wiring LC and the upper electrode Zu[m] of the piezoelectric element PZ[m] provided in the ejection portion D[m]. In this embodiment, the switch WS[m] turns on when the coupling state designation signal QS[m] is at a high level and turns off when the coupling state designation signal QS[m] is at a low level. When the switch WS[m] turns on, the driving signal Com that is supplied to the wiring LC is supplied as the supply driving signal Vin[m] to the upper electrode Zu[m] of the ejection portion D[m].

In this embodiment, when the ink jet printer1executes print processing, one or more unit periods TP are set as an operation period of the ink jet printer1. The ink jet printer1according to this embodiment can drive each ejection portion D[m] for the print processing in each unit period TP.

FIG.5is a timing chart illustrating various signals, such as the driving signal Com or the like, supplied to the head unit3in the unit period TP.

As illustrated inFIG.5, the control unit2outputs the latch signal LAT having a pulse PLL. Thus, the control unit2defines the unit period TP as a period from a rise of a pulse PLL to a rise of a next pulse PLL.

The control unit2also outputs the change signal CH having a pulse PLC in the unit period TP. Then, the control unit2divides the unit period TP into a driving period TQ1from the rise of the pulse PLL to a rise of the pulse PLC and a driving period TQ2from the rise of the pulse PLC to the rise of the next pulse PLL.

As illustrated inFIG.5, the print signal SI includes M individual designation signals Sd[1] to Sd[M] corresponding to the M ejection portion D[1] to D[M] on a one-to-one basis. When the ink jet printer1executes print processing, an individual designation signal Sd[m] designates a mode of driving of the ejection portion D[m] in each unit period TP. Prior to each unit period TP, the control unit2supplies the print signal SI including the M individual designation signals Sd[1] to Sd[M] to the coupling state designation circuit310in synchronization with a clock signal CL. Then, the coupling state designation circuit310generates the coupling state designation signal QS[m], based on the individual designation signal Sd[m], in the unit period TP.

Note that, in this embodiment, it is assumed that, in the unit period TP in which print processing is executed, the ejection portion D[m] is configured to form the dots Dt of any ones of large dots formed of ink of an ink amount ξ1, medium dots formed of ink of an ink amount ξ2 that is smaller than the ink amount ξ1, and small dots formed of ink of an ink amount ξ3 that is smaller than the ink amount ξ2.

FIG.6is a table illustrating the individual designation signal Sd[m].

As illustrated inFIG.6, in this embodiment, the individual designation signal Sd[m] can be any one of four values, that is, a value “1” that designates the ejection portion D[m] as a large dot forming ejection portion DP-1, a value “2” that designates the ejection portion D[m] as a medium dot forming ejection portion DP-2, a value “3” that designates the ejection portion D[m] as a small dot forming ejection portion DP-3, and a value “4” that designates the ejection portion D[m] as a non-dot-forming ejection portion DP-N in the unit period TP in which print processing is executed. Herein, the large dot forming ejection portion DP-1 is an ejection portion D that forms large dots in the unit period TP. The medium dot forming ejection portion DP-2 is an ejection portion D that forms medium dots in the unit period TP. The small dot forming ejection portion DP-3 is an ejection portion D that forms small dots in the unit period TP. The non-dot-forming ejection portion DP-N is an ejection portion D that does not form dots in the unit period TP.

Return to description ofFIG.5. As illustrated inFIG.5, in this embodiment, the driving signal Com has a waveform PA1provided in a driving period TQ1and a waveform PA2provided in a driving period TQ2. Of the waveforms, the waveform PA1is a waveform in which a potential changes from a reference potential V0to a potential VLA1that is lower than the reference potential V0and a potential VHA1that is higher than the reference potential V0, and then, returns to the reference potential V0. The waveform PA1is determined such that, when the supply driving signal Vin[m] having the waveform PA1is supplied to the ejection portion D[m], ink corresponding to an ink amount φ1 is ejected from the ejection portion D[m].

The waveform PA2is a waveform in which a potential changes from the reference potential V0to a potential VLA2that is lower than the reference potential V0and a potential VHA2that is higher than the reference potential V0, and then, returns to the reference potential V0. The waveform PA2is determined such that, when the supply driving signal Vin[m] having the waveform PA2is supplied to the ejection portion D[m], ink corresponding to an ink amount φ2 is ejected from the ejection portion D[m].

Note that, in this embodiment, it is assumed that the ink amount ξ1 corresponds to a sum of the ink amount φ1 and the ink amount φ2, the ink amount ξ2 corresponds to the ink amount φ1, and the ink amount ξ3 corresponds to the ink amount φ2.

In this embodiment, as an example, it is assumed that, when a potential of the supply driving signal Vin[m] supplied to the ejection portion D[m] is high, the volume of the cavity CV of the ejection portion D[m] is smaller than that when the potential is low. Therefore, when the ejection portion D[m] is driven by the supply driving signal Vin[m] having the waveform PA1or the like, the potential of the supply driving signal Vin[m] changes from a low potential to a high potential, so that the ink in the ejection portion D[m] is ejected from the nozzle N.

As illustrated inFIG.6, when the individual designation signal Sd[m] represents the value “1” that designates the ejection portion D[m] as the large dot forming ejection portion DP-1 in the unit period TP, the coupling state designation circuit310sets the coupling state designation signal QS[m] to a high level in the driving period TQ1and the driving period TQ2. In this case, the switch WS[m] turns on in the driving period TQ1and the driving period TQ2. Therefore, the ejection portion D[m] is driven by the supply driving signal Vin[m] having the waveform PA1and the waveform PA2to eject ink of the ink amount ξ1 corresponding to large dots in the unit period TP.

When the individual designation signal Sd[m] represents the value “2” that designates the ejection portion D[m] as the medium dot forming ejection portion DP-2 in the unit period TP, the coupling state designation circuit310sets the coupling state designation signal QS[m] to a high level in the driving period TQ1, and in this case, the switch WS[m] turns on in the driving period TQ1. Therefore, the ejection portion D[m] is driven by the supply driving signal Vin[m] having the waveform PA1to eject ink of the ink amount ξ2 corresponding to medium dots in the unit period TP.

When the individual designation signal Sd[m] represents the value “3” that designates the ejection portion D[m] as the small dot forming ejection portion DP-3 in the unit period TP, the coupling state designation circuit310sets the coupling state designation signal QS[m] to a high level in the driving period TQ2. In this case, the switch WS[m] turns on in the driving period TQ2. Therefore, the ejection portion D[m] is driven by the supply driving signal Vin[m] having the waveform PA2to eject ink of the ink amount ξ3 corresponding to small dots in the unit period TP.

When the individual designation signal Sd[m] represents the value “4” that designates the ejection portion D[m] as the non-dot-forming ejection portion DP-N in the unit period TP, the coupling state designation circuit310sets the coupling state designation signal QS[m] to a low level throughout the unit period TP. In this case, the switch WS[m] is off throughout the unit period TP. Therefore, the ejection portion D[m] is not driven by the supply driving signal Vin[m] in the unit period TP, so that the ejection portion D[m] does not eject ink.

3. Driving Signal Generation Unit

An outline of the driving signal generation unit4will be described below with reference toFIG.7.

FIG.7is a block diagram illustrating an example of a circuit configuration of the driving signal generation unit4.

As illustrated inFIG.7, the driving signal generation unit4includes an integrated circuit40, an amplifier circuit41, a smoothing circuit42, a pull-up circuit43, and a filter circuit44and generates the driving signal Com, based on the waveform designation signal dCom.

The integrated circuit40is, for example, an LSI, that is, a large scale integration, and generates a gate signal SGH and a gate signal SGL, based on the waveform designation signal dCom. The integrated circuit40includes an analog conversion circuit402, a subtractor404, an adder406, an attenuator408, an integral attenuator412, a comparator420, and a gate driver430.

The analog conversion circuit402is a DAC, that is, a digital-to-analog converter, and converts the digital waveform designation signal dCom to an analog signal Aa. Note that a voltage amplitude of the signal Aa is, for example, about 0 to 2 volts, and a signal obtained by amplifying the voltage about 20 times is the driving signal Com. That is, the signal Aa is a signal before amplification into the driving signal Com.

The integral attenuator412attenuates a signal SN1that is input to a terminal Tn1that will be described later and then outputs an integrated signal Ax.

The subtractor404outputs a signal Ab representing a potential obtained by subtracting a potential of the signal Aa from a potential of the signal Ax.

The attenuator408outputs a signal Ay obtained by attenuating a high frequency component of a signal SN2that is input to a terminal Tn2that will be described later.

The adder406outputs a signal As representing a potential obtained by adding a potential of the signal Ab to a potential of the signal Ay.

The comparator420outputs a modulation signal Ms obtained by pulse-modulating the signal As. Specifically, the comparator420outputs the modulation signal Ms that goes to a high level when a voltage of the signal As is a threshold voltage Vth1or more during increase of the voltage of the signal As and goes to a low level when the voltage is lower than a threshold voltage Vth2during dropping of the voltage of the signal As. Note that the threshold voltage Vth1and the threshold voltage Vth2are set to be in a relationship “Vth1>Vth2”.

Note that a power supply voltage of a circuit from the analog conversion circuit402to the comparator420is a low voltage, that is, for example, about 3.3 volts. In contrast, the driving signal Com has a large amplitude, and a voltage of the driving signal Com exceeds, for example, 40 volts in some cases. Therefore, in the integral attenuator412, the signal SN1having an amplitude corresponding to the driving signal Com is attenuated to match an amplitude range of the signal Ax to an amplitude range of a signal in the circuit from the analog conversion circuit402to the comparator420.

In this embodiment, as the waveform designation signal dCom, a digital signal is used as an example. However, it is sufficient that the waveform designation signal dCom is a signal that defines a target value in generating the driving signal Com and, for example, the analog signal Aa may be used as the waveform designation signal dCom. When the signal Aa is the waveform designation signal dCom, the integrated circuit40may be configured without the analog conversion circuit402.

The gate driver430outputs, to a terminal TnH, the gate signal SGH obtained by converting the modulation signal Ms into a specific amplitude. The gate driver430also outputs, to a terminal TnL, the gate signal SGL obtained by converting a signal obtained by inverting a logic level of the modulation signal Ms to a signal with a specific amplitude.

The amplifier circuit41includes, for example, a transistor TrH and a transistor TrL and generates an amplification signal Az that is a signal obtained by amplifying the modulation signal Ms, based on the gate signal SGH and the gate signal SGL output from the integrated circuit40. Note that, in this embodiment, as an example, it is assumed that the transistor TrH and the transistor TrL are N-channel field effect transistors, that is, N-channel FETs.

The gate signal SGH output from the gate driver430is input to a gate electrode of the transistor TrH via the terminal TnH and a resistor RGH.

The gate signal SGL output from the gate driver430is input to a gate electrode of the transistor TrL via the terminal TnL and a resistor RGL. Respective logic levels of the gate signal SGH and the gate signal SGL are in a mutually exclusive relationship.

As used herein, the term “mutually exclusive relationship” refers to a relationship in which a signal level of the gate signal SGH supplied to the gate electrode of the transistor TrH and a signal level of the gate signal SGL supplied to the gate electrode of the transistor TrL do not go to a high level at the same time, that is, the transistor TrH and the transistor TrL do not turn on at the same time. Note that the transistor TrH turns on when the gate electrode of the transistor TrH is at a high level and turns off when the gate electrode of the transistor TrH is at a low level. The transistor TrL turns on when the gate electrode of the transistor TrL is at a high level and turns off when the gate electrode of the transistor TrL is at a low level.

A drain electrode of the transistor TrH is electrically coupled to a feeder line set to a power supply potential VH on a high potential side and a source electrode thereof is electrically coupled to a node Nd.

A source electrode of the transistor TrL is grounded and a drain electrode thereof is electrically coupled to the node Nd. Note that the source electrode of the transistor TrL may be electrically coupled to the feeder line LD set to the potential VBS that is a power supply potential on a low potential side.

As described above, the transistor TrH turns on when the gate signal SGH supplied to the gate electrode thereof is at a high level and turns off when the gate signal SGH is at a low level. The transistor TrL turns on when the gate signal SGL supplied to the gate electrode thereof is at a high level and turns off when the gate signal SGL is at a low level. Therefore, the amplification signal Az obtained by amplifying the modulation signal Ms is output to the node Nd that electrically couples the source electrode of the transistor TrH and the drain electrode of the transistor TrL together. Note that, in this embodiment, one of the transistor TrH and the transistor TrL is an example of a “signal generation transistor”.

The smoothing circuit42is an LPF, that is, a low pass filter, and smooths the amplification signal Az to generate the driving signal Com. The smoothing circuit42includes an inductor L0and a capacitor C0. The inductor L0is configured such that one end thereof is electrically coupled to the node Nd and the other end thereof is electrically coupled to an output terminal Tn-out. The capacitor C0is configured such that one end thereof is electrically coupled to the output terminal Tn-out and the other end thereof is grounded. The driving signal Com obtained by smoothing the amplification signal Az is output from the output terminal Tn-out. Note that, in this embodiment, the amplification signal Az input to the inductor L0is an example of an “input signal” and the inductor L0is an example of a “signal generation coil”.

The pull-up circuit43feeds back, to the terminal Tn1, the signal SN1obtained by pulling up the driving signal Com output to the output terminal Tn-out. The pull-up circuit43includes a resistor R1configured such that one end thereof is electrically coupled to the output terminal Tn-out and the other end thereof is electrically coupled to the terminal Tn1and a resistor R2configured such that one end thereof is electrically coupled to the terminal Tn1and the other end thereof is electrically coupled to a feeder line set to the power supply potential VH.

The filter circuit44is a BPF, that is, a band pass filter, and feeds back, to the terminal Tn2, the signal SN2obtained by cutting off a DC component of the driving signal Com from a frequency component in a specific band. The filter circuit44includes a resistor R3, a capacitor C1configured such that one end thereof is electrically coupled to the output terminal Tn-out and the other end thereof is electrically coupled to one end of the resistor R3, a resistor R4configured such that one end thereof is electrically coupled to the one end of the resistor R3and the other end thereof is grounded, a capacitor C2configured such that one end thereof is electrically coupled to the other end of the resistor R3and the other end thereof is grounded, and a capacitor C3configured such that one end thereof is electrically coupled to the other end of the resistor R3and the other end thereof is electrically coupled to the terminal Tn2.

Among the above-described components of the filter circuit44, the capacitor C1and the resistor R4function as HPFs, that is, high pass filters, that pass high frequency components of a cutoff frequency or higher in the driving signal Com. The resistor R3and the capacitor C2function as LPFs, that is, low pass filters, that pass low frequency components of a cutoff frequency or lower in the driving signal Com. In this embodiment, in the filter circuit44, the cutoff frequency of the HPFs is set lower than the cutoff frequency of the LPFs. Therefore, the filter circuit44passes frequency components of the driving signal Com in a specific band that is equal to or higher than the cutoff frequency of the HPFs and equal to or lower than the cutoff frequency of the LPFs. The filter circuit44includes the capacitor C3, and therefore, feeds back, to the terminal Tn2, signals of the driving signal Com in which DC components are cut off from signals of frequency components in a specific band that have passed through the HPFs and the LPFs.

As described above, the driving signal generation unit4generates the driving signal Com by smoothing the amplification signal Az in the node Nd by the smoothing circuit42. The driving signal Com is integrated and subtracted by the integral attenuator412, and then, is fed back to the subtractor404. Therefore, the driving signal generation unit4performs self-oscillation at a frequency determined by a delay in the smoothing circuit42, a delay in the integral attenuator412, and a transfer function of feedback. However, since a delay amount of a feedback path via the terminal Tn1is large, the frequency of self-oscillation cannot be made high enough to sufficiently ensure accuracy of a waveform of the driving signal Com only by feedback via the terminal Tn1. In contrast, in this embodiment, a path on which the high frequency components of the driving signal Com are fed back via the terminal Tn2is provided separately from a path on which the high frequency components of the driving signal Com are fed back via the terminal Tn1, and therefore, a delay of feedback in the entire driving signal generation unit4can be made small. That is, in this embodiment, a frequency of the signal As obtained by adding the signal Ay that is a high frequency component of the driving signal Com to the signal Ab can be made high, as compared to when there is no feedback path via the terminal Tn2, so that the accuracy of the driving signal Com can be sufficiently ensured.

4. Driving Signal Generation Unit and Storage Unit

The driving signal generation unit4and a storage unit600that stores the driving signal generation unit4will be described below with reference toFIG.8andFIG.9.

FIG.8is a plan view illustrating the driving signal generation unit4and the storage unit600as viewed in plan view from a YE1direction toward a YE2direction opposite to the YE1direction.FIG.9is a sectional view illustrating the driving signal generation unit4and the storage unit600taken along a line IX-IX inFIG.8.

Note that, hereinafter, the YE1direction and the YE2direction that is an opposite direction of the YE1direction will be collectively referred to as a “YE axis direction”, an XE1direction crossing the YE axis direction and an XE2direction that is an opposite direction of the XE1direction will be collectively referred to as an “XE axis direction”, and a ZE1direction crossing the XE axis direction and the YE axis direction and a ZE2direction that is an opposite direction of the ZE1direction will be collectively referred to as a “ZE axis direction”. In this embodiment, as an example, it is assumed that the XE axis direction, the YE axis direction, and the ZE axis direction are orthogonal to each other. However, the present disclosure is not limited thereto. It is sufficient that the XE axis direction, the YE axis direction, and the ZE axis direction cross each other. In this embodiment, the ZE1direction is a direction approximately in parallel to a gravitational acceleration direction. Moreover, the ZE1direction may be a direction approximately in parallel to the Z1direction. As used herein, the term “approximately in parallel” refers a concept including a case where the mentioned directions can be regarded as being in parallel in consideration of an error, in addition to a case where the mentioned directions are completely in parallel. In this embodiment, the term “approximately in parallel” refers to a concept including a case where the mentioned directions can be regarded as being in parallel in consideration of an error of about plus or minus 10%.

As illustrated inFIG.8andFIG.9, the storage unit600includes a circuit board60and a cover61.

The driving signal generation unit4is provided on a circuit forming surface PC of the circuit board60. Herein, the circuit forming surface PC is one surface of two surfaces of the circuit board60to which the YE axis direction is normal, the one surface facing in the YE1direction.

The cover61is, for example, formed of metal. The cover61preferably has a thermal conductivity of 10 [W/m·K] or more and more preferably has a thermal conductivity of 50 [W/m·K] or more. As the cover61, for example, iron, copper, or the like can be employed.

The cover61is fixed to the circuit board60by a screw69so as to be in contact with the circuit forming surface PC of the circuit board60. Note that the cover61has a shape with a portion around a center thereof in the ZE axis direction protruding in the YE1direction. Therefore, a space SP is formed between the circuit forming surface PC of the circuit board60and the cover61by fixing the cover61to the circuit forming surface PC of the circuit board60. The portion of the cover61protruding in the YE1direction will be hereinafter referred to as a “protruding portion of the cover61” sometimes.

Note that, in this embodiment, it is assumed that the space SP is a sealed space enclosed by the circuit board60and the cover61, but the present disclosure is not limited thereto. For example, the space SP may be an open space that communicates with a space outside the storage unit600via a gap existing between the circuit board60and the cover61.

A heat sink62is provided to the cover61. Specifically, the heat sink62is provided at a portion of the cover61located in the YE1direction as viewed from the space SP. That is, the heat sink62is provided at the protruding portion of the cover61. However, the present disclosure is not limited thereto. For example, the heat sink62may be provided at a portion of the cover61located in the ZE2direction as viewed from the space SP.

A heat conduction member80that conducts heat generated in the driving signal generation unit4to the heat sink62is provided in the space SP. In this embodiment, the heat conduction member80includes a heat conductive material81provided so as to be in contact with the driving signal generation unit4, a heat conductive material82provided so as to be in contact with a surface of the protruding portion of the cover61in the YE2direction, and a reinforcing member83that supports the heat conductive material81and the heat conductive material82.

The heat conductive material81is a flame-retardant material having thermal conductivity, heat resistance, and insulating property.

More specifically, the heat conductive material81has a thermal conductivity that is at least higher than that of air, is required, for example, to have a thermal conductivity of 0.1 [W/m·K] or more, preferably has a thermal conductivity of 0.2 [W/m·K] or more, and more preferably has a thermal conductivity of 0.8 [W/m·K] or more.

The heat conductive material81is a flexible material that follows an uneven surface of the driving signal generation unit4in the YE1direction. For example, the heat conductive material81is an elastic material, such as rubber, a jelly-like (gelled) material, such as gel, or a semi-solid or paste-like material, such as grease.

The heat conductive material81is chemically stable, is excellent in chemical resistance, and does not react with a reactive ink.

In this embodiment, as the heat conductive material81, silicone is employed. Specifically, in this embodiment, as the heat conductive material81, rubber type silicone is employed. However, as the heat conductive material81, grease type or gel type silicone may be employed. Note that, as the heat conductive material81, in addition to silicone, some other polymer gel excellent in thermal conductivity, heat resistance, insulating property, and chemical resistance may be employed.

The heat conductive material82may be a similar material to the heat conductive material81. In this embodiment, as the heat conductive material82, silicone is employed. Specifically, in this embodiment, as the heat conductive material82, rubber type silicone is employed. However, unlike the heat conductive material81, the heat conductive material82is not required to have a following property to follow an uneven shape, and therefore, a material less flexible than the heat conductive material81may be employed.

The reinforcing member83supports the heat conductive material81and the heat conductive material82to suppress change in positions of the heat conductive material81and the heat conductive material82in the ZE axis direction. Specifically, the reinforcing member83is a flame-retardant material having an insulating property. The reinforcing member83is excellent in chemical resistance and does not react with a reactive ink.

In this embodiment, as the reinforcing member83, glass fiber made of glass in fibrous form is employed.

Note that, in this embodiment, the reinforcing member83does not completely separate the heat conductive material81and the heat conductive material82from each other and may have a gap through which a portion of the heat conductive material81and a portion of the heat conductive material82can contact each other.

As illustrated inFIG.8, in this embodiment, when the storage unit600is viewed in plan view with respect to the YE2direction, the heat conduction member80is provided such that the entire driving signal generation unit4is covered with the heat conductive material81provided in the heat conduction member80. Moreover, as illustrated in FIG.9, in this embodiment, the heat conduction member80is provided such that the driving signal generation unit4is sealed between the circuit forming surface PC of the circuit board60and the heat conductive material81.

However, the present disclosure is not limited thereto and, for example, when the storage unit600is viewed in plan view with respect to the YE2direction, the heat conduction member80may be provided such that only a portion of the driving signal generation unit4is covered with the heat conductive material81.

In this embodiment, the heat conduction member80is provided such that the heat conductive material81is in contact with the integrated circuit40, the transistor TrH, the transistor TrL, and the inductor L0.

However, the present disclosure is not limited thereto and the heat conduction member80may be provided such that the heat conductive material81is in contact with at least some of the transistor TrH, the transistor TrL, and the inductor L0. For example, the heat conduction member80may be provided such that the heat conductive material81is in contact with the transistor TrH and the transistor TrL, or the heat conduction member80may be provided such that the heat conductive material81is in contact with the inductor L0.

The driving signal generation unit4generates heat when generating the driving signal Com. Specifically, in the transistor TrH, the transistor TrL, and the inductor L0of the driving signal generation unit4, a large amount of heat is generated when the driving signal generation unit4generates the driving signal Com.

In contrast, in this embodiment, the heat conductive material81is in contact with the transistor TrH, the transistor TrL, and the inductor L0of the driving signal generation unit4. The heat conductive material81conducts heat generated in the transistor TrH, the transistor TrL, and the inductor L0to the heat sink62via the heat conductive material82. That is, in this embodiment, the heat generated in the transistor TrH, the transistor TrL, and the inductor L0is dissipated to outside of the storage unit600via the heat conduction member80and the heat sink62. Thus, according to this embodiment, as compared to a mode where the heat conduction member80is not provided, a probability that a failure occurs in the driving signal generation unit4due to the heat generated in the driving signal generation unit4can be reduced.

According to this embodiment, the driving signal generation unit4is stored in the storage unit600, and furthermore, in the space SP in the storage unit600, the heat conduction member80is provided so as to cover the driving signal generation unit4. Therefore, according to this embodiment, as compared to a mode in which the heat conduction member80is not provided, a probability of dust and dirt adhering to the driving signal generation unit4can be reduced, and also, a probability that mist of reactive ink generated due to ejection of the reactive ink from the ejection portions D attaches to the driving signal generation unit4can be reduced. Therefore, according to this embodiment, as compared to a mode where the heat conduction member80is not provided, a probability that a failure, such as short circuit, an electric leakage, or the like, occurs in the driving signal generation unit4due to adherence of mist of the reactive ink to the driving signal generation unit4can be reduced.

According to this embodiment, the heat conduction member80is formed of a material that does not react with the reactive ink. Therefore, according to this embodiment, as compared to a mode where the heat conduction member80is formed of a material that has a low chemical resistance and reacts with the reactive ink, reduction over time in a “protective function against mist” of the heat conduction member80to protect the driving signal generation unit4from mist of the reactive ink and a “heat dissipating function” of the heat conduction member80to dissipate the heat generated in the driving signal generation unit4can be suppressed.

In this embodiment, the heat conduction member80includes the reinforcing member83that supports the heat conductive material81and the heat conductive material82. Therefore, according to this embodiment, as compared to a mode where the heat conduction member80does not include the reinforcing member83, a state where the heat conductive material81and the heat conductive material82are disposed at positions that allow the “protective function against mist” and the “heat dissipating function” of the heat conduction member80to be properly performed can be maintained. That is, according to this embodiment, as compared to a mode where the heat conduction member80does not include the reinforcing member83, reduction over time in the “protective function against mist” to protect the driving signal generation unit4from mist of the reactive ink and the “heat dissipating function” to dissipate the heat generated in the driving signal generation unit4can be suppressed.

5. Conclusion of Embodiment

As described above, the ink jet printer1according to this embodiment includes the ejection portion D that ejects the reactive ink, the driving signal generation unit4that generates the driving signal Com to drive the ejection portion D, the heat sink62that dissipates the heat generated in the driving signal generation unit4due to generation of the driving signal Com, and the heat conduction member80that conducts the heat generated in the driving signal generation unit4to the heat sink62, and the heat conduction member80includes the heat conductive material81with an insulating property whose state is not changed by a chemical reaction with the reactive ink and the reinforcing member83with an insulating property whose state is not changed by a chemical reaction with the reactive ink.

Therefore, according to this embodiment, as compared to a mode where the heat conduction member80is not provided, a probability that a failure occurs in the driving signal generation unit4due to the heat generated in the driving signal generation unit4can be reduced. According to this embodiment, as compared to a mode where the heat conduction member80is not provided, a probability that a failure, such as a short circuit, an electric leakage, or the like, occurs in the driving signal generation unit4due to adherence of mist of the reactive ink to the driving signal generation unit4can be reduced. According to this embodiment, as compared to a mode where the heat conduction member80is formed of a material that chemically reacts with the reactive ink, a state where the heat conduction member80protects the driving signal generation unit4from the reactive ink can be stably maintained.

According to this embodiment, the heat conductive material81may be silicone.

Therefore, according to this embodiment, the heat generated in the driving signal generation unit4can be dissipated and adherence of mist to the driving signal generation unit4can be suppressed.

According to this embodiment, the heat conductive material81may be a flame-retardant gel material.

Therefore, according to this embodiment, the heat generated in the driving signal generation unit4can be efficiently dissipated.

According to this embodiment, the reinforcing member83may be formed of glass fiber.

Therefore, according to this embodiment, a state where the heat conduction member80protects the driving signal generation unit4from the reactive ink can be stably maintained.

In this embodiment, the driving signal generation unit4may include the inductor L0that smooths the amplification signal Az to generate the driving signal Com and include the transistor TrH that generates the amplification signal Az, and the heat conductive material81may be in contact with the inductor L0and the transistor TrH. Moreover, in this embodiment, the driving signal generation unit4may include the inductor L0that smooths the amplification signal Az to generate the driving signal Com and include the transistor TrL that generates the amplification signal Az, and the heat conductive material81may be in contact with the inductor L0and the transistor TrL.

Therefore, according to this embodiment, as compared to a mode where the heat conductive material81is not in contact with the inductor L0and the transistor TrH and a mode where the heat conductive material81is not in contact with the inductor L0and the transistor TrL, the heat generated in the driving signal generation unit4can be efficiently dissipated.

In this embodiment, the heat conductive material81may be provided so as to entirely cover the inductor L0and the transistor TrH on the circuit board60on which the driving signal generation unit4is disposed. Moreover, in this embodiment, the heat conductive material81may be provided so as to entirely cover the inductor L0and the transistor TrL on the circuit board60on which the driving signal generation unit4is disposed.

Therefore, according to this embodiment, as compared to a mode where the heat conductive material81does not cover a portion of the inductor L0and the transistor TrH, a probability that mist of the reactive ink adheres to the driving signal generation unit4can be reduced. According to this embodiment, as compared to a mode where the heat conductive material81does not cover a portion of the inductor L0and the transistor TrL, a probability that mist of the reactive ink adheres to the driving signal generation unit4can be reduced.

In this embodiment, the heat conductive material81may be provided to entirely cover the driving signal generation unit4on the circuit board60on which the driving signal generation unit4is disposed.

Therefore, according to this embodiment, as compared to a mode where the heat conductive material81does not cover a portion of the driving signal generation unit4, a probability that mist of the reactive ink adheres to the driving signal generation unit4can be reduced.

In this embodiment, the reactive ink may be any one of a solvent ink obtained by dispersing a coloring material in a solvent, a photoreactive ink whose property is changed through irradiation of light, a textile printing ink used for printing of a textile, or a pretreatment ink that is applied to a textile as pretreatment before printing.

Therefore, in this embodiment, even when the ink jet printer1is used for any of various applications, a state where the heat conduction member80protects the driving signal generation unit4from a reactive ink can be maintained.

B. MODIFIED EXAMPLES

Each embodiment described above may be variously modified. Specific modified examples will be described below. Two or more optionally selected examples from the modified examples described below can be combined as appropriate in a range in which they do not mutually contradict each other. Note that, in the modified examples described below, for elements having equivalent effects and functions to those of the embodiment, the reference sings that are referred to in the description given above are also used and the detailed description of each of the elements will be omitted, as appropriate.

First Modified Example

In the above-described embodiment, an example where the storage unit600includes the circuit board60has been described, but the present disclosure is not limited thereto. For example, the circuit board60may be provided separately from the storage unit600and be stored in the storage unit600. In this case, the space SP may be a space in the storage unit600and be a space that stores the driving signal generation unit4and the circuit board60.

Second Modified Example

In the above-described embodiment and the first modified example, an example where the control unit2is not stored in the storage unit600and is provided outside the storage unit600has been described, but the present disclosure is not limited thereto. For example, the control unit2may be stored in the storage unit600.

Third Modified Example

In the above-described embodiment and the first and second modified examples, it is assumed that the ink jet printer1includes four head units3, but the present disclosure is not limited thereto. The ink jet printer1may include one or more and three or less head units3, or the ink jet printer1may include five or more head units3.

Fourth Modified Example

In the above-described embodiment and the first to third modified examples, an example where the ink jet printer1is a serial printer has been described, but the present disclosure is not limited thereto. The ink jet printer1may be a so-called line printer in which, in the head unit3, a plurality of nozzles N are provided so as to extend wider than the width of the recording paper PP.