Patent Application
20250162310
The present application is based on, and claims priority from JP Application Serial Number 2023-195243, filed Nov. 16, 2023, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a liquid ejection apparatus and a print head.
As a liquid ejection apparatus that changes internal pressure of a cavity filled with a liquid by driving a drive element based on a drive signal to thereby eject the liquid due to the change in the internal pressure, there is known a liquid ejection apparatus that has a plurality of drive elements corresponding to one nozzle from which the liquid is ejected, and that ejects the liquid from the single nozzle by driving the plurality of drive elements, in response to market demands for ejecting the liquid high in viscosity and for increasing an amount of the liquid ejected by single drive of the drive elements.
For example, JP-A-2022-057816 discloses a liquid ejection apparatus that has two piezoelectric elements corresponding to one nozzle, and ejects a liquid from one nozzle N by driving the two piezoelectric elements.
JP-A-2022-057816 is an example of the related art.
However, in the liquid ejection apparatus described in JP-A-2022-057816, there was room for further improvement from the viewpoint of improving the ejection accuracy of the liquid.
One aspect of the liquid ejection apparatus according to the present disclosure includes
a drive circuit configured to output a drive signal,
a first switching circuit to which the drive signal is input, and which is configured to switch whether to output a first drive voltage according to the drive signal,
a first piezoelectric element which is displaced in accordance with the first drive voltage,
a first pressure chamber a volume of which varies with a displacement of the first piezoelectric element,
a second piezoelectric element which is displaced in accordance with the first drive voltage,
a second pressure chamber a volume of which varies with a displacement of the second piezoelectric element, and
a first nozzle configured to eject a liquid in accordance with a change in volume of the first pressure chamber and a change in volume of the second pressure chamber, wherein
the first switching circuit includes a single first switch element configured to switch whether to set the drive signal to the first drive voltage and supply the drive signal commonly to the first piezoelectric element and the second piezoelectric element in accordance with a first ejection control signal.
One aspect of the print head according to the present disclosure includes
a first switching circuit to which the drive signal is input, and which is configured to switch whether to output a first drive voltage according to the drive signal,
a first piezoelectric element which is displaced in accordance with the first drive voltage,
a first pressure chamber a volume of which varies with a displacement of the first piezoelectric element,
a second piezoelectric element which is displaced in accordance with the first drive voltage,
a second pressure chamber a volume of which varies with a displacement of the second piezoelectric element, and
a first nozzle configured to eject a liquid in accordance with a change in volume of the first pressure chamber and a change in volume of the second pressure chamber, wherein
the first switching circuit includes a single first switch element configured to switch whether to set the drive signal to the first drive voltage and supply the drive signal commonly to the first piezoelectric element and the second piezoelectric element in accordance with a first ejection control signal.
A preferred embodiment of the present disclosure will hereinafter be described using the drawings. The drawings to be used are for the sake of convenience of explanation. Note that the embodiment described below does not unreasonably limit the content of the present disclosure set forth in the appended claims. Further, all the configurations to be described below are not necessarily essential elements of the present disclosure.
As shown in
The control unit 2 includes a processing circuit such as a central processing unit (CPU) or a field programmable gate array (FPGA), and a storage circuit such as a semiconductor memory device. The control unit 2 outputs a signal for controlling each element of the liquid ejection apparatus 1 based on image data supplied from an external device such as a host computer not shown provided outside the liquid ejection apparatus 1.
The liquid container 3 retains ink as an example of a liquid supplied to the ejection units 5. Specifically, the liquid container 3 retains a plurality of colors of ink to be ejected to the medium P such as black ink, cyan ink, magenta ink, yellow ink, red ink, and gray ink. As such a liquid container 3, an ink cartridge, an ink pack that is shaped like a bag, and is formed of a flexible film, an ink tank in which the ink can be replenished, or the like may be used.
The circulation unit 6 supplies the ink retained in the liquid container 3 to the ejection units 5 based on a control signal Ctrl-P output by the control unit 2. Further, the circulation unit 6 also collects the ink discharged from the ejection units 5 based on the control signal Ctrl-P output by the control unit 2. That is, the circulation unit 6 returns the ink in the liquid ejection apparatus 1. Such a circulation unit 6 can include, for example, a pump for generating a flow of the ink in the liquid ejection apparatus 1.
The conveyance unit 4 includes a conveyance motor 41 and conveyance rollers 42. A conveyance control signal Ctrl-T output by the control unit 2 is input to the conveyance unit 4. Then, the conveyance motor 41 operates based on the conveyance control signal Ctrl-T, and the conveyance rollers 42 rotate due to the operation of the conveyance motor 41. Due to the rotation of the conveyance rollers 42, the medium P is conveyed along the conveyance direction.
The plurality of ejection units 5 each have a drive module 10 and an ejection module 20. To each of the plurality of ejection units 5, an image information signal IP that corresponds to the ejection unit 5, and is output by the control unit 2 is input, and the ink retained in the liquid container 3 is supplied. Then, the drive module 10 controls an operation of the ejection module 20 based on the image information signal IP. Thus, the ejection module 20 ejects the ink supplied from the liquid container 3 at a predetermined timing in accordance with the control of the drive module 10.
In the liquid ejection apparatus 1 according to the present embodiment, the ejection modules 20 respectively provided to the plurality of ejection units 5 are located side by side along the main scanning direction so as to be equal to or longer than the width of the medium P. Then, each of the plurality of ejection units 5 ejects the ink at a timing synchronized with the conveyance of the medium P. Thus, the ink ejected from each of the plurality of ejection units 5 lands at desired positions on the medium P, and a desired image is formed on the medium P.
Then, a schematic configuration of the ejection unit 5 will be described.
The drive module 10 has a control circuit board 11, a drive circuit 50, and a control circuit 100. The control circuit board 11 is a printed circuit board having a single wiring layer or a plurality of wiring layers, and a glass epoxy board, a glass polyimide board, or the like may be used as the control circuit board 11. Elements constituting the drive module 10 including the drive circuit 50 and the control circuit 100 are mounted on the control circuit board 11. Note that the control circuit board 11 on which the elements constituting the drive module 10 are mounted may be formed of a single printed circuit board or a plurality of printed circuit boards.
The control circuit 100 includes a processing circuit such as a CPU or an FPGA and a storage circuit such as a semiconductor memory device. The image information signal IP output by the control unit 2 is input to the control circuit 100. The control circuit 100 generates signals for controlling operations of the drive module 10 and the ejection module 20 based on the image information signal IP input to the control circuit 100, and then outputs the signals.
Specifically, the control circuit 100 generates a clock signal SCK, a latch signal LAT, a change signal CH, an inspection timing signal TSIG, and print data signals SI1 to SIn based on the image information signal IP input to the control circuit 100, and then outputs these signals to the ejection module 20.
Further, the control circuit 100 generates a base drive signal dA and outputs the base drive signal dA to the drive circuit 50. The drive circuit 50 generates a drive signal COM including a signal waveform defined by the base drive signal dA input thereto, and then outputs the drive signal COM to the ejection module 20. Specifically, the control circuit 100 generates the base drive signal dA as a digital signal and then outputs the base drive signal dA to the drive circuit 50. The drive circuit 50 converts the base drive signal dA as a digital signal input to the drive circuit 50 into an analog signal, and then performs class-D amplification on the analog signal thus converted to thereby generate the drive signal COM. Then, the drive circuit 50 outputs the drive signal COM thus generated to the ejection module 20. That is, the base drive signal dA output by the control circuit 100 defines the signal waveform of the drive signal COM output by the drive circuit 50.
Note that the base drive signal dA input to the drive circuit 50 is only required to be a signal capable of defining the signal waveform of the drive signal COM, and may be an analog signal. Further, the drive circuit 50 is only required to be able to generate the drive signal COM by amplifying the signal waveform defined by the base drive signal dA, and may generate the drive signal COM by performing class-A amplification, class-B amplification, or class-AB amplification instead of the class-D amplification.
Further, the drive circuit 50 generates a reference voltage signal VBS and then outputs the reference voltage signal VBS to the ejection module 20. The reference voltage signal VBS is a signal that is constant in voltage value, and that defines a reference potential for drive of piezoelectric elements 60a, 60b provided to an ejector 600 described later. The voltage value of such a reference voltage signal VBS may be, for example, a ground potential GND, or may be 5.5 V, 6 V, or the like. Note that in
Further, a residual vibration signal dNVT is input to the control circuit 100 from the ejection module 20 described later. The control circuit 100 determines whether the ejector 600 corresponding to the residual vibration signal dNVT is normal based on the residual vibration signal dNVT that is input to the control circuit 100. Note that the details of the residual vibration signal dNVT input to the control circuit 100 and the details of determination on whether the ejector 600 is normal based on the residual vibration signal dNVT will be described later.
The ejection module 20 has print heads 21-1 to 21-n, a head circuit board 23, and AD conversion circuits 300-1 to 300-n. Further, each of the print heads 21-1 to 21-n has a head chip 22, a flexible board 24, and a drive signal selection circuit 200. Further, each of the head chips 22 provided respectively to the print heads 21-1 to 21-n has a plurality of ejectors 600, and each of the plurality of ejectors 600 includes the piezoelectric elements 60a, 60b.
The clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, the print data signals SI1 to SIn, the drive signal COM, and the reference voltage signal VBS output by the drive module 10 are input to the ejection module 20.
The head circuit board 23 propagates the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, the print data signals SI1 to SIn, the drive signal COM, and the reference voltage signal VBS, that are input to the head circuit board 23, to the corresponding print heads 21-1 to 21-n. Such a head circuit board 23 is a printed circuit board having a single wiring layer or a plurality of wiring layers, and as the head circuit board 23, a glass epoxy board or a glass polyimide board, for example, may be used.
Out of the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, the print data signals SI1 to SIn, the drive signal COM, and the reference voltage signal VBS, the head circuit board 23 propagates the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, the print data signal SI1, the drive signal COM, and the reference voltage signal VBS to the print head 21-1.
Out of the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, the print data signal SI1, the drive signal COM, and the reference voltage signal VBS input to the print head 21-1, the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, the print data signal SI1, and the drive signal COM are input to the drive signal selection circuit 200 of the print head 21-1. The drive signal selection circuit 200 of the print head 21-1 selects or deselects a signal waveform that the drive signal COM includes based on the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, and the print data signal SI1 input to the drive signal selection circuit 200 to thereby generate drive voltage signals Vin corresponding respectively to the plurality of ejectors 600 provided to the head chip 22 of the print head 21-1, and then supplies the drive voltage signal Vin to one ends of the piezoelectric elements 60a, 60b that the ejector 600 corresponding thereto includes.
On this occasion, the reference voltage signal VBS is supplied to the other ends of the piezoelectric elements 60a, 60b provided to each of the plurality of ejectors 600 provided to the head chip 22 of the print head 21-1. Further, the piezoelectric elements 60a, 60b provided to the plurality of ejectors 600 are driven in accordance with the potential difference between the voltage value of the drive voltage signal Vin supplied to one ends and the voltage value of the reference voltage signal VBS supplied to the other ends. The ink is ejected from the ejector 600 corresponding thereto due to the drive of these piezoelectric elements 60a, 60b.
Further, a residual vibration signal Vout corresponding to the residual vibration generated after the piezoelectric elements 60a, 60b provided to the plurality of ejectors 600 provided to the head chip 22 of the print head 21-1 are driven is input to the drive signal selection circuit 200 of the print head 21-1. The drive signal selection circuit 200 generates a residual vibration signal NVT1 corresponding to the residual vibration signal Vout input to the drive signal selection circuit 200, and then outputs the residual vibration signal NVT1 from the print head 21-1.
Such a drive signal selection circuit 200 provided to the print head 21-1 is configured as an integrated circuit device, and is COF (Chip On Film)-mounted on the flexible board 24 provided to the print head 21-1.
Similarly, out of the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, the print data signals SI1 to SIn, the drive signal COM, and the reference voltage signal VBS, the head circuit board 23 propagates the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, a print data signal SIi (i is any one of 1 to n), the drive signal COM, and the reference voltage signal VBS to a print head 21-i.
Out of the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, the print data signal SIi, the drive signal COM, and the reference voltage signal VBS input to the print head 21-i, the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, the print data signal SIi, and the drive signal COM are input to the drive signal selection circuit 200 of the print head 21-i. The drive signal selection circuit 200 of the print head 21-i selects or deselects a signal waveform that the drive signal COM includes based on the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, and the print data signal SIi input to the drive signal selection circuit 200 to thereby generate the drive voltage signals Vin corresponding respectively to the plurality of ejectors 600 provided to the head chip 22 of the print head 21-i, and then supplies the drive voltage signal Vin commonly to one ends of the piezoelectric elements 60a, 60b that the ejector 600 corresponding thereto includes.
On this occasion, the reference voltage signal VBS is supplied to the other ends of the piezoelectric elements 60a, 60b provided to each of the plurality of ejectors 600 provided to the head chip 22 of the print head 21-i. Further, the piezoelectric elements 60a, 60b provided to the plurality of ejectors 600 are driven in accordance with the potential difference between the voltage value of the drive voltage signal Vin supplied to one ends and the voltage value of the reference voltage signal VBS supplied to the other ends. The ink is ejected from the ejector 600 corresponding thereto due to the drive of these piezoelectric elements 60a, 60b.
Further, the residual vibration signal Vout corresponding to the residual vibration generated after the piezoelectric elements 60a, 60b provided to the plurality of ejectors 600 provided to the head chip 22 of the print head 21-i are driven is input to the drive signal selection circuit 200 of the print head 21-i. The drive signal selection circuit 200 generates a residual vibration signal NVTi corresponding to the residual vibration signal Vout input to the drive signal selection circuit 200, and then outputs the residual vibration signal NVTi from the print head 21-i.
Such a drive signal selection circuit 200 provided to the print head 21-i is configured as an integrated circuit device, and is COF-mounted on the flexible board 24 provided to the print head 21-i.
Here, when the drive signal selection circuit 200 provided to each of the print heads 21-1 to 21-i is COF-mounted on the flexible board 24 corresponding to the print head is not a limitation, and the drive signal selection circuit 200 may be provided to the head circuit board 23, but is preferably COF-mounted on the flexible board 24 corresponding to the print head as shown in the present embodiment. Thus, the propagation path of the drive voltage signal Vin output by the drive signal selection circuit 200 and the propagation path of the residual vibration signal Vout input to the drive signal selection circuit 200 can be shortened, and the possibility that noise is superimposed on the drive voltage signal Vin and the residual vibration signal Vout is reduced, and the possibility that distortion occurs in the signal waveform of the drive voltage signal Vin and the residual vibration signal Vout due to the influence of the impedance of the propagation path is reduced. As a result, the accuracy of the signal waveform of the drive voltage signal Vin supplied to the piezoelectric elements 60a, 60b provided to the ejector 600 corresponding to the drive voltage signal Vin is improved, the driving accuracy of the piezoelectric elements 60a, 60b is improved, and the determination accuracy on whether the ejector 600 is normal in accordance with the residual vibration signal Vout in the control circuit 100 is improved.
The AD conversion circuits 300-1 to 300-n are provided to the head circuit board 23 so as to correspond to the print heads 21-1 to 21-n. Specifically, the AD conversion circuit 300-1 is provided so as to correspond to the print head 21-1, and the residual vibration signal NVT1 output by the drive signal selection circuit 200 of the print head 21-1 is input to the AD conversion circuit 300-1. Then, the AD conversion circuit 300-1 generates a residual vibration signal dNVT1 which is obtained by converting the residual vibration signal NVT1 input thereto into a digital signal, and then outputs the residual vibration signal dNVT1 to the control circuit 100. Similarly, an AD conversion circuit 300-i is provided so as to correspond to the print head 21-i, and the residual vibration signal NVTi output by the drive signal selection circuit 200 of the print head 21-i is input to the AD conversion circuit 300-i. Then, the AD conversion circuit 300-i generates a residual vibration signal dNVTi which is obtained by converting the residual vibration signal NVTi input thereto into a digital signal, and then outputs the residual vibration signal dNVTi to the control circuit 100. Such AD conversion circuits 300-1 to 300-n may be configured as a single integrated circuit device, or may be configured as a single integrated circuit device together with the drive signal selection circuit 200 provided to corresponding one of the print heads 21-1 to 21-n.
Here, the print heads 21-1 to 21-n are all substantially the same in configuration. Therefore, in the following description, when there is no need to distinguish the print heads 21-1 to 21-n from each other, the print heads 21-1 to 21-n may simply be referred to as print heads 21. The description will be presented assuming that on this occasion, the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, a print data signal SI as the print data signals SI1 to SIn, the drive signal COM, and the reference voltage signal VBS are input to the print head 21, and a residual vibration signal NVT as the residual vibration signals NVT1 to NVTn is output. Further, the description will be presented assuming that the residual vibration signal NVT output by the print head 21 is converted into a digital signal in an AD conversion circuit 300 as the AD conversion circuits 300-1 to 300-n, to thereby be output as the residual vibration signal dNVT to the control circuit 100.
As described above, the liquid ejection apparatus 1 according to the present embodiment is provided with the ejection units 5 for ejecting the ink to the medium P, and the conveyance unit 4 for conveying the medium P on which the ink ejected from the print head 21 lands, and the ejection unit 5 is provided with the drive circuit 50 for outputting the drive signal COM, the print heads 21 for ejecting the ink based on the drive signal COM, the AD conversion circuits 300 for converting the residual vibration signals NVT corresponding to the residual vibration signals Vout into the residual vibration signals dNVT as the digital signals, and the control circuit 100 for determining whether the print heads 21 including the ejectors 600 as the inspection target are normal based on the residual vibration signals dNVT output by the ejection module 20.
Then, the configuration and the operation of the drive signal selection circuit 200 that outputs the drive voltage signal Vin corresponding to each of the plurality of ejectors 600 by selecting or deselecting the signal waveform that the drive signal COM includes will be described. In describing the details of the drive signal selection circuit 200, an example of a signal waveform of the drive signal COM input to the drive signal selection circuit 200 will be described first.
The drive signal ComA includes drive waveforms Adp1, Adp2 as signal waveforms in a period t after the latch signal LAT rises until the latch signal LAT subsequently rises.
The drive waveform Adp1 is arranged in a period tp1 from the rise of the latch signal LAT to a rise of the change signal CH in the period t. The voltage value of the drive waveform Adp1 starts at a voltage Vc, then the voltage value changes so as to drive the piezoelectric elements 60a, 60b, and then the voltage value ends at the voltage Vc. When the drive waveform Adp1 is supplied to the piezoelectric elements 60a, 60b, a predetermined amount of ink is ejected from the ejector 600 corresponding to the piezoelectric elements 60a, 60b.
The drive waveform Adp2 is arranged in a period tp2 from the rise of the change signal CH to the rise of the latch signal LAT in the period t. The voltage value of the drive waveform Adp2 starts at the voltage Vc, then the voltage value changes so as to drive the piezoelectric elements 60a, 60b, and then the voltage value ends at the voltage Vc. When the drive waveform Adp2 is supplied to the piezoelectric elements 60a, 60b, a smaller amount of ink than the predetermined amount is ejected from the ejector 600 corresponding to the piezoelectric elements 60a, 60b.
Here, in the following description, in some cases, the predetermined amount of ink ejected from the ejector 600 corresponding to the piezoelectric elements 60a, 60b when the drive waveform Adp1 is supplied to the piezoelectric elements 60a, 60b may be referred to as a medium amount, and the smaller amount of ink than the predetermined amount ejected from the ejector 600 corresponding to the piezoelectric elements 60a, 60b when the drive waveform Adp2 is supplied to the piezoelectric elements 60a, 60b may be referred to as a small amount.
The drive signal ComB includes drive waveforms Bdp1, Bdp2, and Bdp3 as the signal waveforms in the period t.
The drive waveform Bdp1 is arranged in a period ts1 from the rise of the latch signal LAT to a rise of the inspection timing signal TSIG in the period t. The voltage value of the drive waveform Bdp1 starts at the voltage Vc, then the voltage value changes so as to drive the piezoelectric elements 60a, 60b, and then the voltage value ends at a voltage Vd. When the drive waveform Bdp1 is supplied to the piezoelectric elements 60a, 60b, the ink is not ejected from the ejector 600 corresponding to the piezoelectric elements 60a, 60b, and the piezoelectric elements 60a, 60b are driven so that a predetermined vibration is generated in the ejector 600 corresponding to the piezoelectric elements 60a, 60b.
The drive waveform Bdp2 is arranged in a period ts2 from the rise of the inspection timing signal TSIG defining the end of the period ts1 to a subsequent rise of the inspection timing signal TSIG in the period t. The voltage value of the drive waveform Bdp2 is constant at the voltage Vd. When the drive waveform Bdp2 is supplied to one ends of the piezoelectric elements 60a, 60b, the piezoelectric elements 60a, 60b are not driven, and accordingly the ink is not ejected from the ejector 600 corresponding to the piezoelectric elements 60a, 60b.
The drive waveform Bdp3 is arranged in a period ts3 from the rise of the inspection timing signal TSIG defining the end of the period ts2 to a subsequent rise of the latch signal LAT in the period t. The drive waveform Bdp3 starts with the voltage value at the voltage Vd, and is then terminated when the voltage value becomes the voltage Vc. When the drive waveform Bdp3 is supplied to the piezoelectric elements 60a, 60b, the piezoelectric elements 60a, 60b are not driven, and accordingly, the ink is not ejected from the ejector 600 corresponding to the piezoelectric elements 60a, 60b.
That is, the drive circuit 50 outputs the drive signal COM including the drive signal ComA including the drive waveforms Adp1, Adp2, and the drive signal ComB including the drive waveforms Bdp1, Bdp2, and Bdp3 to the drive signal selection circuit 200. Then, by selecting or deselecting the drive waveforms Adp1, Adp2, and the drive waveforms Bdp1, Bdp2, and Bdp3, the drive signal selection circuit 200 generates the drive voltage signal Vin including signal waveforms for expressing four gray levels of a large dot LD, a medium dot MD, a small dot SD, and non-recording ND on the medium P, and the drive voltage signal Vin including signal waveforms for executing a state inspection CD of inspecting the state of the ejector 600, and then outputs the drive voltage signals Vin thus generated to the ejector 600 corresponding thereto.
Note that the signal waveforms of the drive signal COM shown in
Then, a specific example of the configuration of the drive signal selection circuit 200 will be described.
The clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, the print data signal SI, and the drive signal COM are input to the switching circuit 210. The switching circuit 210 selects or deselects the drive waveforms Adp1, Adp2 provided to the drive signal ComA and the drive waveforms Bdp1, Bdp2, and Bdp3 provided to the drive signal ComB in the drive signal COM based on the clock signal SCK, the latch signal LAT, the inspection timing signal TSIG, the change signal CH, and the print data signal SI input to the switching circuit 210 to thereby generate the drive voltage signal Vin corresponding to each of the plurality of ejectors 600. Then, the drive voltage signals Vin generated by the switching circuit 210 are output from the drive signal selection circuit 200.
The drive voltage signal Vin output from the drive signal selection circuit 200 is supplied to the piezoelectric element 60a and the piezoelectric element 60b provided to the ejector 600 corresponding to the drive voltage signal Vin. Specifically, the drive voltage signal Vin output by the drive signal selection circuit 200 propagates through a wiring line 311. The wiring line 311 branches into a wiring line 312 and a wiring line 313 at a node 315. Then, by the wiring line 312 being electrically coupled to the piezoelectric element 60a provided to the ejector 600 corresponding thereto, and the wiring line 313 being electrically coupled to the piezoelectric element 60a provided to the ejector 600 corresponding thereto, the drive voltage signal Vin output from the drive signal selection circuit 200 is supplied to the piezoelectric element 60a and the piezoelectric element 60b provided to the ejector 600 corresponding to the drive voltage signal Vin. That is, the drive voltage signal Vin output by the drive signal selection circuit 200 propagates through the wiring line 311 and the wiring line 312 and is supplied to the piezoelectric element 60a provided to the ejector 600 corresponding thereto, and also propagates through the wiring line 311 and the wiring line 313 and is supplied to the piezoelectric element 60b provided to the ejector 600 corresponding thereto. In other words, the piezoelectric element 60a and the piezoelectric element 60b are electrically coupled to each other at the node 315.
Here, in the following description, in some cases, the drive voltage signal Vin that is supplied to the piezoelectric element 60a and propagates through the wiring line 312 is referred to as a drive voltage signal Vin1, and the drive voltage signal Vin that is supplied to the piezoelectric element 60b and propagates through the wiring line 313 is referred to as a drive voltage signal Vin2.
In addition, after the piezoelectric elements 60a, 60b are driven by the drive voltage signal Vin output by the drive signal selection circuit 200, the switching circuit 210 acquires the residual vibration signal Vout corresponding to the residual vibration generated in the ejector 600.
Specifically, after the drive voltage signal Vin1 is supplied to the piezoelectric element 60a and the drive voltage signal Vin2 is supplied to the piezoelectric element 60b, the residual vibration is generated in the ejector 600. Then, the piezoelectric element 60a outputs counter-electromotive force generated in response to the residual vibration as a residual vibration signal Vout1, and the piezoelectric element 60b outputs counter-electromotive force generated in response to the residual vibration as a residual vibration signal Vout2.
The residual vibration signal Vout1 output by the piezoelectric element 60a propagates through the wiring lines 312, 311 and is input to the drive signal selection circuit 200. Further, the residual vibration signal Vout2 output by the piezoelectric element 60b propagates through the wiring lines 313, 311 and is input to the drive signal selection circuit 200. That is, the residual vibration signal Vout in which the residual vibration signal Vout1 and the residual vibration signal Vout2 are synthesized with each other is input to the drive signal selection circuit 200. The switching circuit 210 acquires the residual vibration signal Vout input to the switching circuit 210, at a predetermined timing. Then, the switching circuit 210 outputs the residual vibration signal Vout thus acquired to the waveform shaping circuit 240.
The waveform shaping circuit 240 shapes the signal waveform of the residual vibration signal Vout input to the waveform shaping circuit 240. Then, the waveform shaping circuit 240 outputs the signal obtained by shaping the waveform of the residual vibration signal Vout as the residual vibration signal NVT. The residual vibration signal NVT output by the waveform shaping circuit 240 is output from the drive signal selection circuit 200, and is then input to the AD conversion circuit 300.
A specific example of a configuration and an operation of the switching circuit 210 provided to the drive signal selection circuit 200 will be described.
The clock signal SCK, the print data signal SI, the latch signal LAT, the change signal CH, and the inspection timing signal TSIG are input to the selection control circuit 220. Based on the clock signal SCK, the print data signal SI, the latch signal LAT, the change signal CH, and the inspection timing signal TSIG input thereto, the selection control circuit 220 generates selection signals Sa, Sb, and Sc having predetermined logic levels in each of the periods tp1, tp2 and the periods ts1, ts2, ts3, and then outputs the selection signals Sa, Sb, and Sc to the selection circuits 230 corresponding thereto.
The selection control circuit 220 includes a set of a shift register 222, a latch circuit 224, and a decoder 226 provided so as to correspond respectively to the plurality of ejectors 600 provided to the print head 21. Here, the description will be presented assuming that the print head 21 has the M ejectors 600. That is, the selection control circuit 220 includes M sets of the shift register 222, the latch circuit 224, and the decoder 226. In other words, the selection control circuit 220 includes the M shift registers 222, the M latch circuits 224, and the M decoders 226.
The print data signal SI serially includes 3-bit print data SId [SIH, SIM, SIL] for selecting which one of the large dot LD, the medium dot MD, the small dot SD, the non-recording ND, and the state inspection CD described above, the ejector 600 is to be driven to correspond to, so as to correspond to each of the M ejectors 600. That is, the print data signal SI is a serial signal of 3M bits or more in total.
The print data signal SI is input to the selection control circuit 220 in synchronization with the clock signal SCK. The M shift registers 222 provided to the selection control circuit 220 hold the 3-bit print data SId [SIH, SIM, SIL] provided to the print data signal SI input thereto so as to correspond to the ejectors 600.
Particularly, the M shift registers 222 are serially coupled so as to correspond respectively to the M ejectors 600. The print data signal SI serially input to the selection control circuit 220 is sequentially transferred to the subsequent stages of the M shift registers 222 serially coupled to one another in synchronization with the clock signal SCK. Then, when the supply of the clock signal SCK to the selection control circuit 220 is stopped, the 3-bit print data SId [SIH, SIM, SIL] corresponding to the M ejectors 600 are held in the M shift registers 222. Note that in the following description, in order to distinguish the M shift registers 222 serially coupled from each other, the M shift registers 222 may be referred to as a first stage, a second stage, . . . , and an M-th stage in this order from the upstream side to the downstream side in a direction in which the print data signal SI is supplied.
Each of the M latch circuits 224 latches the 3-bit print data SId [SIH, SIM, SIL] held in the shift register 222 corresponding thereto simultaneously at the rising edge of the latch signal LAT.
Then, the print data SId [SIH, SIM, SIL] latched by the M latch circuits 224 are input to the decoders 226 corresponding thereto. Each of the M decoders 226 decodes the print data SId [SIH, SIM, SIL] input thereto to generate the selection signals Sa, Sb, and Sc having the logic levels corresponding to the large dot LD, the medium dot MD, the small dot SD, the non-recording ND, and the state inspection CD, and then outputs the selection signals Sa, Sb, and Sc to the selection circuit 230 corresponding thereto.
Further, when the print data SId [SIH, SIM, SIL]=[1, 0, 0] corresponding to the medium dot MD is input, the decoder 226 sets the logic level of the selection signal Sa to H, L levels in the periods tp1, tp2, sets the logic level of the selection signal Sb to L, L, and L levels in the periods ts1, ts2, and ts3, and sets the logic level of the selection signal Sc to L, L, and L levels in the periods ts1, ts2, and ts3.
Further, when the print data SId [SIH, SIM, SIL]=[0, 1, 0] corresponding to the small dot SD is input, the decoder 226 sets the logic level of the selection signal Sa to L, H levels in the periods tp1, tp2, sets the logic level of the selection signal Sb to L, L, and L levels in the periods ts1, ts2, and ts3, and sets the logic level of the selection signal Sc to L, L, and L levels in the periods ts1, ts2, and ts3.
When the print data SId [SIH, SIM, SIL]=[0, 0, 0] corresponding to the non-recording ND is input, the decoder 226 sets the logic level of the selection signal Sa to L, L levels in the periods tp1, tp2, sets the logic level of the selection signal Sb to L, L, and L levels in the periods ts1, ts2, and ts3, and sets the logic level of the selection signal Sc to L, L, and L levels in the periods ts1, ts2, and ts3.
Further, when the print data SId [SIH, SIM, SIL]=[1, 1, 1] corresponding to the state inspection SD is input, the decoder 226 sets the logic level of the selection signal Sa to L, L levels in the periods tp1, tp2, sets the logic level of the selection signal Sb to H, L, and H levels in the periods ts1, ts2, and ts3, and sets the logic level of the selection signal Sc to L, H, and L levels in the periods ts1, ts2, and ts3.
As described above, based on the print data SId [SIH, SIM, SIL], the selection control circuit 220 generates the selection signals Sa, Sb, and Sc of the logic levels corresponding to each of the M ejectors 600. Then, the selection control circuit 220 outputs the selection signals Sa, Sb, and Sc thus generated to the corresponding selection circuits 230.
The selection circuit 230 is provided so as to correspond to each of the M ejectors 600. That is, the switching circuit 210 includes the M selection circuits 230.
Then, the drive signal COM is input to each of the M selection circuits 230, and whether the drive voltage signal Vin corresponding to the drive signal COM is output to the ejector 600 corresponding to the drive voltage signal Vin is switched.
The selection signal Sa is supplied to a positive control terminal of the transfer gate 234a, and is inverted in logic level by the NOT circuit 232a, and is then also supplied to a negative control terminal of the transfer gate 234a. The selection signal Sb is supplied to a positive control terminal of the transfer gate 234b, and is inverted in logic level by the NOT circuit 232b, and is then also supplied to a negative control terminal of the transfer gate 234b. The selection signal Sc is supplied to a positive control terminal of the transfer gate 234c, and is inverted in logic level by the NOT circuit 232c, and is then also supplied to a negative control terminal of the transfer gate 234c.
Further, the drive signal ComA is supplied to an input terminal of the transfer gate 234a, and the drive signal ComB is supplied to an input terminal of the transfer gate 234b. Further, output terminals of the transfer gates 234a, 234b are coupled to each other. The output terminals of the transfer gates 234a, 234b coupled to each other are electrically coupled to the ejector 600 corresponding thereto via the wiring line 311 corresponding thereto. Further, an input terminal of the transfer gate 234c is electrically coupled to the output terminals of the transfer gates 234a, 234b coupled to each other and one end of the ejector 600. As shown in
In the selection circuit 230 configured as described hereinabove, when the logic level of the selection signal Sa is at the H level, the transfer gate 234a becomes conductive between the input terminal and the output terminal, and when the logic level of the selection signal Sa is at the L level, the transfer gate 234a becomes non-conductive between the input terminal and the output terminal. Similarly, when the logic level of the selection signal Sb is at the H level, the transfer gate 234b becomes conductive between the input terminal and the output terminal, and when the logic level of the selection signal Sb is at the L level, the transfer gate 234b becomes non-conductive between the input terminal and the output terminal. Similarly, when the logic level of the selection signal Sc is at the H level, the transfer gate 234c becomes conductive between the input terminal and the output terminal, and when the logic level of the selection signal Sc is at the L level, the transfer gate 234c becomes non-conductive between the input terminal and the output terminal. Here, in the following description, the conductive state between the input terminal and the output terminal may be referred to as “ON”, and the non-conductive state between the input terminal and the output terminal may be referred to as “OFF”, in some cases.
Then, when the transfer gate 234a is turned on, the drive signal ComA is output from the switching circuit 210 as the drive voltage signal Vin, and when the transfer gate 234b is turned on, the drive signal ComB is output from the switching circuit 210 as the drive voltage signal Vin. The drive voltage signal Vin output from the switching circuit 210 is supplied to the ejector 600 corresponding thereto. Further, by the transfer gate 234c being turned on, the switching circuit 210 acquires the residual vibration signal Vout corresponding to the residual vibration generated in the ejector 600 corresponding thereto. Then, the switching circuit 210 outputs the residual vibration signal Vout thus acquired to the waveform shaping circuit 240. That is, the waveform shaping circuit 240 is electrically coupled to the coupling point to which the output terminals of the transfer gates 234c of the M selection circuits 230 are coupled in common, and the waveform shaping circuit 240 outputs the residual vibration signal NVT corresponding to the signal at that coupling point.
That is, the switching circuit 210 has the selection control circuit 220 that outputs the selection signal Sa for controlling switching of the conduction state of the transfer gate 234a, the selection signal Sb for controlling switching of the conduction state of the transfer gate 234b, and the selection signal Sc for controlling switching of the conduction state of the transfer gate 234c. Further, the selection circuit 230 has the single transfer gate 234a that switches whether to supply the drive signal ComA as the drive signal COM commonly to the piezoelectric element 60a and the piezoelectric element 60b as the drive voltage signal Vin in accordance with the selection signal Sa, the single transfer gate 234b that switches whether to supply the drive signal ComB as the drive signal COM commonly to the piezoelectric element 60a and the piezoelectric element 60b as the drive voltage signal Vin in accordance with the selection signal Sb, and the single transfer gate 234c that switches whether to output the residual vibration signal Vout, that is a composite wave of the residual vibration signal Vout1 and the residual vibration signal Vout2, to the waveform shaping circuit 240 in accordance with the selection signal Sc. That is, the transfer gate 234a has one end to which the drive signal ComA is input and the other end electrically coupled to the node 315 to switch whether to supply the drive signal ComA commonly to the piezoelectric element 60a and the piezoelectric element 60b in accordance with the selection signal Sa input to the control terminal, the transfer gate 234b has one end to which the drive signal ComB is input and the other end electrically coupled to the node 315 to switch whether to supply the drive signal ComB commonly to the piezoelectric element 60a and the piezoelectric element 60b in accordance with the selection signal Sb input to the control terminal, and the transfer gate 234c has one end electrically coupled to the node 315 and the other end electrically coupled to the waveform shaping circuit 240 to switch the conduction state between the node 315 and the waveform shaping circuit 240 in accordance with the selection signal Sc input to the control terminal to thereby switch whether to output the residual vibration signal Vout to the waveform shaping circuit 240.
The details of the operation of the switching circuit 210 configured as described above will be described.
Thereafter, when the latch signal LAT rises, each of the latch circuits 224 simultaneously latches the print data SId [SIH, SIM, SIL] held in the shift register 222. Here, LT1, LT2, . . . , LTM shown in
The decoder 226 decodes the print data SId [SIH, SIM, SIL] thus latched with the contents shown in
Specifically, in the case of the print data SId [SIH, SIM, SIL]=[1, 1, 0], the decoder 226 sets the logic level of the selection signal Sa to H, H levels in the periods tp1, tp2, sets the logic level of the selection signal Sb to L, L, and L levels in the periods ts1, ts2, and ts3, and sets the logic level of the selection signal Sc to L, L, and L levels in the periods ts1, ts2, and ts3. Accordingly, the selection circuit 230 selects the drive waveform Adp1 of the drive signal ComA in the period tp1, and selects the drive waveform Adp2 of the drive signal ComA in the period tp2. As a result, the switching circuit 210 outputs the drive voltage signal Vin corresponding to the large dot LD shown in
Further, in the case of the print data SId [SIH, SIM, SIL]=[1, 0, 0], the decoder 226 sets the logic level of the selection signal Sa to H, L levels in the periods tp1, tp2, sets the logic level of the selection signal Sb to L, L, and L levels in the periods ts1, ts2, and ts3, and sets the logic level of the selection signal Sc to L, L, and L levels in the periods ts1, ts2, and ts3. Accordingly, the selection circuit 230 selects the drive waveform Adp1 of the drive signal ComA in the period tp1, and does not select any signal waveform of the drive signals ComA, ComB in the period tp2. As a result, the switching circuit 210 outputs the drive voltage signal Vin corresponding to the medium dot MD shown in
Further, in the case of the print data SId [SIH, SIM, SIL]=[0, 1, 0], the decoder 226 sets the logic level of the selection signal Sa to L, H levels in the periods tp1, tp2, sets the logic level of the selection signal Sb to L, L, and L levels in the periods ts1, ts2, and ts3, and sets the logic level of the selection signal Sc to L, L, and L levels in the periods ts1, ts2, and ts3. Accordingly, the selection circuit 230 does not select any signal waveform of the drive signals ComA, ComB in the period tp1, and selects the drive waveform Adp2 of the drive signal ComA in the period tp2. As a result, the switching circuit 210 outputs the drive voltage signal Vin corresponding to the small dot SD shown in
In the case of the print data SId [SIH, SIM, SIL]=[0, 0, 0], the decoder 226 sets the logic level of the selection signal Sa to L, L levels in the periods tp1, tp2, sets the logic level of the selection signal Sb to L, L, and L levels in the periods ts1, ts2, and ts3, and sets the logic level of the selection signal Sc to L, L, and L levels in the periods ts1, ts2, and ts3. Accordingly, the selection circuit 230 does not select any signal waveform of the drive signals ComA, ComB in the period tp1, and does not select any waveform of the drive signals ComA, ComB in the period tp2. As a result, the switching circuit 210 outputs the drive voltage signal Vin corresponding to the non-recording ND illustrated in
Further, in the case of the print data SId [SIH, SIM, SIL]=[1, 1, 1], the decoder 226 sets the logic level of the selection signal Sa to L, L levels in the periods tp1, tp2, sets the logic level of the selection signal Sb to H, L, and H levels in the periods ts1, ts2, and ts3, and sets the logic level of the selection signal Sc to L, H, and L levels in the periods ts1, ts2, and ts3. Accordingly, the selection circuit 230 selects the drive waveform Bdp1 of the drive signal ComB in the period ts1, then acquires the residual vibration signal Vout corresponding to the residual vibration generated in the ejector 600 after the piezoelectric elements 60a, 60b are driven by the drive waveform Bdp1 in the period ts2, outputs the residual vibration signal Vout thus acquired from the switching circuit 210, and selects the drive waveform Bdp3 of the drive signal ComB in the period ts3. As a result, the switching circuit 210 outputs the drive voltage signal Vin corresponding to the state inspection CD shown in
As described above, the switching circuit 210 generates the drive voltage signal Vin by selecting or deselecting the drive waveforms Adp1, Adp2 provided to the drive signal ComA and the drive waveforms Bdp1, Bdp2, and Bdp3 provided to the drive signal ComB in the drive signal COM output by the drive circuit 50 based on the clock signal SCK, the print data signal SI, the latch signal LAT, the change signal CH, and the inspection timing signal TSIG. Then, the switching circuit 210 supplies the drive voltage signal Vin thus generated to the ejector 600 corresponding thereto, acquires the residual vibration signal Vout generated after the drive voltage signal Vin is supplied to the ejector 600, and outputs the residual vibration signal Vout to the waveform shaping circuit 240.
Then, a specific example of a configuration and an operation of the waveform shaping circuit 240 provided to the drive signal selection circuit 200 will be described.
The filter circuit 241 includes a capacitor C10 and a resistor R10. The residual vibration signal Vout is supplied to one end of the capacitor C10. The other end of the capacitor C10 is electrically coupled to one end of the resistor R10. The ground potential is supplied to the other end of the resistor R10. As described above, the filter circuit 241 forms a high-pass filter. Then, the filter circuit 241 extracts a high frequency component superimposed on the residual vibration signal Vout by reducing a low frequency component to be superimposed on the residual vibration signal Vout.
That is, the waveform shaping circuit 240 includes the filter circuit 241 for extracting the AC component contained in the residual vibration signal Vout. Note that the filter circuit 241 may form a so-called band-pass filter having a low-pass filter in addition to a high-pass filter, and may extract a signal of a predetermined frequency component to be superimposed on the residual vibration signal Vout.
The amplifier circuit 242 includes an operational amplifier AM10 and resistors R11, R12. A signal output by the filter circuit 241 is input to a positive input terminal of the operational amplifier AM10. A negative input terminal of the operational amplifier AM10 is electrically coupled to one end of the resistor R11 and one end of the resistor R12. The other end of the resistor R11 is electrically coupled to an output terminal of the operational amplifier AM10. The ground potential is supplied to the other end of the resistor R12. The amplifier circuit 242 configured as described above amplifies a signal that is output by the filter circuit 241 and input to the positive input terminal of the operational amplifier AM10 with a gain defined by the resistance values of the resistors R11, R12. That is, the amplifier circuit 242 configures a non-inverting amplifier circuit that amplifies the amplitude of a signal obtained by extracting the AC component of the residual vibration signal Vout with a gain defined by the resistance values of the resistors R11, R12. In other words, the waveform shaping circuit 240 includes the amplifier circuit 242 that amplifies the signal of the AC component extracted by the filter circuit 241. Note that the amplifier circuit 242 is only required to be able to amplify the amplitude of the signal obtained by extracting the AC component of the residual vibration signal Vout with a predetermined gain, and is not limited to the non-inverting amplifier circuit.
The impedance conversion circuit 243 includes an operational amplifier AM11. A signal output by the amplifier circuit 242 is input to the positive input terminal of the operational amplifier AM11. In addition, the negative input terminal of the operational amplifier AM11 is electrically coupled to an output terminal of the operational amplifier AM11. The impedance conversion circuit 243 configured as described above constitutes a so-called voltage follower circuit that outputs a signal having the same signal waveform as the signal waveform of the signal input to the positive input terminal of the operational amplifier AM11 from the output terminal of the operational amplifier AM11.
Then, the waveform shaping circuit 240 outputs, as the residual vibration signal NVT, a signal that is output from the output terminal of the operational amplifier AM10 provided to the amplifier circuit 242, and is output from the output terminal of the operational amplifier AM11 provided to the impedance conversion circuit 243.
The piezoelectric elements 60a, 60b provided to the ejector 600 as an inspection target are driven by supplying the drive voltage signal Vin corresponding to the state inspection CD, and then, a high-frequency damped vibration is generated in the ejector 600 as the inspection target. Then, the piezoelectric elements 60a, 60b output the residual vibration signals Vout1, Vout2 corresponding to the damped vibration generated in the ejector 600 as the inspection target. That is, the switching circuit 210 acquires a signal of the composite wave of the residual vibration signals Vout1, Vout2, that is obtained by combining signal waveforms of the high-frequency damped vibrations as the residual vibration signal Vout corresponding to the ejector 600 as the inspection target. Such a residual vibration signal Vout is small in voltage amplitude, and is therefore easily affected by noise.
In contrast, in the waveform shaping circuit 240 of the present embodiment, by removing noise in the low-frequency component and the DC component from the residual vibration signal Vout in the filter circuit 241 to extract the high-frequency component that the residual vibration signal Vout includes, the signal corresponding to the high frequency damped vibration generated in the ejector 600 as the inspection target, and then, by amplifying the signal output by the filter circuit 241 in the amplifier circuit 242, the resistance to noise is improved. Further, the impedance conversion circuit 243 converts the impedance of the signal output by the amplifier circuit 242 to thereby enhance the stability of the residual vibration signal NVT output by the waveform shaping circuit 240. That is, the waveform shaping circuit 240 of the present embodiment outputs the signal that corresponds to the residual vibration signal Vout, that is obtained by shaping the signal waveform of the residual vibration signal Vout input thereto, that is reduced in influence of noise and so on, in which the resistance to noise is improved, and that is high in stability, as the residual vibration signal NVT.
As described above, the residual vibration signal Vout, which is the residual vibration signal Vout1 and the residual vibration signal Vout2, and is a composite wave of the residual vibration signal Vout1 and the residual vibration signal Vout2, is input to the waveform shaping circuit 240, and the waveform shaping circuit 240 outputs the residual vibration signal NVT.
Then, a structure of the print head 21 will be described.
As shown in
The nozzle substrate 360 is a plate-like member that is elongated along the Y axis and extends in substantially parallel to and along the X-Y plane formed of the X axis and the Y axis. The nozzle substrate 360 is provided with M nozzles N. The nozzles N are through holes provided to the nozzle substrate 360. Since these M nozzles N are arranged in parallel to each other along the Y axis in the nozzle substrate 360, a nozzle column Ln is provided to the nozzle substrate 360. Here, the expression “substantially parallel” is not limited to when two things are completely parallel to each other, but includes when the two things are assumed to be parallel to each other when taking errors or the like into consideration.
The communication plate 302 is located at the −Z side of the nozzle substrate 360. The communication plate 302 is a plate-like member that is elongated along the Y axis and extends in substantially parallel to the X-Y plane. The communication plate 302 is provided with a supply flow path RA1, a discharge flow path RA2, M coupling flow paths RK1, M coupling flow paths RK2, M communication flow paths RR1, M communication flow paths RR2, and M nozzle flow paths RN as a part of flow paths through which the ink flows.
The supply flow path RA1 is located at the +X side in the communication plate 302 and extends along the Y direction. The discharge flow path RA2 is located at the −X side in the communication plate 302 and extends along the Y direction. On this occasion, the supply flow path RA1 and the discharge flow path RA2 are formed so as to substantially be line symmetrical taking the Z axis passing through the nozzle N as the axis of symmetry. The M coupling flow paths RK1 are located at the −X side of the supply flow path RA1 and are arranged in parallel along the Y direction. The M communication flow paths RR1 are located at the −X side of the M coupling flow paths RK1 arranged in parallel along the Y direction, and are arranged in parallel along the Y direction. The M coupling flow paths RK2 are located at the +X side of the discharge flow path RA2, and at the −X side of the M communication flow paths RR1 arranged in parallel along the Y direction, and are arranged in parallel along the Y direction. The M communication flow paths RR2 are located at the +X side of the M coupling flow paths RK2 arranged in parallel along the Y direction, and at the −X side of the M communication flow paths RR1 arranged in parallel along the Y direction, and are arranged in parallel along the Y direction. On this occasion, the coupling flow path RK1 and the coupling flow path RK2 are formed so as to substantially be line symmetrical taking the Z axis passing through the nozzle N as the axis of symmetry, and the communication flow path RR1 and the communication flow path RR2 are formed so as to substantially be line symmetrical taking the Z axis passing through the nozzle N as the axis of symmetry. The nozzle flow path RN communicates the communication flow path RR1 and the communication flow path RR2 corresponding to the common nozzle N with each other. Further, the nozzle substrate 360 is fixed to the communication plate 302 so that the nozzles N are located at substantially the central positions in the X direction of the nozzle flow paths RN when the communication plate 302 is viewed from the Z direction.
The pressure chamber substrate 303 is located at the −Z side of the communication plate 302 and is fixed to the communication plate 302. The pressure chamber substrate 303 is a plate-like member that is elongated in the Y-axis direction and extends in substantially parallel to the X-Y plane. This pressure chamber substrate 303 is provided with M pressure chambers CB1 and M pressure chambers CB2 as a part of the flow paths through which the ink flows. On this occasion, the pressure chamber CB1 and the pressure chamber CB2 are formed so as to substantially be line symmetrical taking the Z axis passing through the nozzle N as the axis of symmetry.
The M pressure chambers CB1 correspond one-to-one to the M nozzles N, and are arranged in parallel along the Y axis. Further, each of the M pressure chambers CB1 is communicated with the coupling flow path RK1 and the communication flow path RR1 corresponding to the nozzle N in common. Specifically, in the pressure chamber CB1, an end portion at the +X side is communicated with the coupling flow path RK1, and an end portion at the −X side is communicated with the communication flow path RR1 when viewed along the Z axis. That is, the pressure chamber CB1 communicates the coupling flow path RK1 and the communication flow path RR1 corresponding to the nozzle N in common with each other.
Similarly, the M pressure chambers CB2 correspond one-to-one to the M nozzles N and are located at the −X side of the M pressure chambers CB1 arranged in parallel along the Y axis, and are arranged in parallel along the Y axis. Further, each of the M pressure chambers CB2 is communicated with the coupling flow path RK2 and the communication flow path RR2 corresponding to the nozzle N in common. Specifically, in the pressure chamber CB2, an end portion at the −X side is communicated with the coupling flow path RK2, and an end portion at the +X side is communicated with the communication flow path RR2 when viewed along the Z axis. That is, the pressure chamber CB2 communicates the coupling flow path RK2 and the communication flow path RR2 corresponding to the nozzle N in common with each other.
The vibration plate 304 is located at the −Z side of the pressure chamber substrate 303 and is fixed to the pressure chamber substrate 303 so as to close up the pressure chambers CB1, CB2. The vibration plate 304 is a plate-like member that is elongated in the Y direction, extends substantially in parallel to the X-Y plane, and can elastically vibrate. Further, the M piezoelectric elements 60a and the M piezoelectric elements 60b are arranged in parallel at the −Z side of the vibration plate 304. The M piezoelectric elements 60a are arranged in parallel along the Y axis at the −Z side of the vibration plate 304. Further, the M piezoelectric elements 60b are arranged in parallel along the Y axis at the −Z side of the vibration plate 304 and at the −X side of the M piezoelectric elements 60a arranged in parallel along the Y axis. That is, a column of the M piezoelectric elements 60a and a column of the M piezoelectric elements 60b are arranged in parallel at the −Z side of the vibration plate 304.
The retention chamber formation substrate 305 is located at the −Z side of the communication plate 302. The retention chamber formation substrate 305 is a member elongated in the Y direction and includes an aperture 350. Further, the retention chamber formation substrate 305 is fixed to the communication plate 302 so that the pressure chamber substrate 303, the vibration plate 304, and a wiring substrate 308 are located inside the aperture 350. Further, the retention chamber formation substrate 305 includes a supply flow path RB1, a discharge flow path RB2, a supply port 351, and a discharge port 352. The supply flow path RB1 is communicated with the supply flow path RA1. The discharge flow path RB2 is communicated with the discharge flow path RA2. The supply port 351 is communicated with the supply flow path RB1. The discharge port 352 is communicated with the discharge flow path RB2. Further, due to the operation of the circulation unit 6, the ink retained in the liquid container 3 is supplied to the supply port 351. As a result, the ink is supplied to the head chip 22. Further, the ink supplied to the head chip 22 flows through the inside of the head chip 22 and is collected through the discharge port 352 by the operation of the circulation unit 6. That is, the ink supplied to the head chip 22 is returned due to the operation of the circulation unit 6.
The flexible board 24 is electrically coupled to the vibration plate 304 at the −X side of the column of the M piezoelectric elements 60a on the −Z side surface of the vibration plate 304, and at the +X side of the column of the M piezoelectric elements 60b. That is, the flexible board 24 is electrically coupled to the vibration plate 304 between the column of the M piezoelectric elements 60a and the column of the M piezoelectric elements 60b provided to the vibration plate 304. On this occasion, it is preferable for the flexible board 24 to electrically be coupled to the vibration plate 304 so that the distance between the flexible board 24 and the column of the M piezoelectric elements 60a and the distance between the flexible board 24 and the column of the M piezoelectric elements 60b are substantially equal to each other.
An integrated circuit 201 is COF-mounted on the flexible board 24. The drive signal selection circuit 200 described above is implemented in the integrated circuit 201. That is, the M selection circuits 230 including the transfer gates 234a, 234b, and 234c provided to the drive signal selection circuit 200 are provided to the integrated circuit 201. Further, the integrated circuit 201 includes a pair of long sides located to be opposed to each other and a pair of short sides that are located to be opposed to each other and are shorter than the long sides, and is COF-mounted on the flexible board 24 so that the long sides extend along the Y axis. As described above, the drive signal selection circuit 200 outputs the drive voltage signals Vin to the M ejectors 600. Accordingly, the integrated circuit 201 has M terminals for outputting the drive voltage signals Vin respectively to the M ejectors 600. Further, by performing the COF mounting on the flexible board 24 so that the long sides of the integrated circuit 201 extend along the Y axis, it becomes possible to arrange the M terminals in a line along the long sides of the integrated circuit 201. As a result, the possibility that the wiring pattern propagated by the drive voltage signals Vin is routed cumbersomely in the flexible board 24 is reduced, the possibility that a difference occurs in the wiring length between the wiring patterns propagated by the drive voltage signals Vin to the respective M ejectors 600 is reduced, and the waveform accuracy of the drive voltage signals Vin supplied to the M ejectors 600 is improved.
Further, in this case, it is preferable that the length of the long sides of the integrated circuit 201 is shorter than a length in a direction along the Y axis of the nozzle column Ln in which the M nozzles N are arranged in parallel in a column in the nozzle substrate 360. The size of the print head 21 is defined by larger one of the size of the head chip 22 and the size of the flexible board 24. The size of the head chip 22 may be defined by the length of the nozzle column Ln in some cases, and the length of the nozzle column Ln is defined by the usage of the liquid ejection apparatus 1, such as the type of the ink ejected from the liquid ejection apparatus 1 or the image formation speed on the medium P. That is, the size of the head chip 22 may be defined by specifications of the liquid ejection apparatus 1 in some cases. Therefore, in order to reduce the size of the print head 21 to the extent that the specifications of the liquid ejection apparatus 1 are satisfied, it is necessary to reduce the size of the flexible board 24 and to reduce the size of the integrated circuit 201 to be COF-mounted on the flexible board 24.
In the liquid ejection apparatus 1 according to the present embodiment, by making the length of the long sides of the integrated circuit 201 shorter than the length in the direction along the Y axis of the nozzle column Ln in which the M nozzles N are arranged in a column on the nozzle substrate 360, it is possible to appropriately achieve the reduction in size of the print head 21 within the range in which the specifications of the liquid ejection apparatus 1 are satisfied.
The flexible board 24 configured as described above propagates the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, the print data signal SI, the drive signal COM, and the reference voltage signal VBS to be input to the print head 21. Out of the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, the print data signal SI, the drive signal COM, and the reference voltage signal VBS propagated by the flexible board 24, the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, the print data signal SI, and the drive signal COM are input to the plurality of terminals arranged in parallel on, for example, the long side at the −Z side of the integrated circuit 201.
The integrated circuit 201 selects or deselects the signal waveform of the drive signal COM based on the clock signal SCK, the latch signal LAT, the change signal CH, the inspection timing signal TSIG, and the print data signal SI input to the integrated circuit 201 to thereby generate the drive voltage signals Vin corresponding respectively to the plurality of ejectors 600. Further, the integrated circuit 201 outputs the drive voltage signals Vin thus generated from the M terminals arranged in parallel on the long side at the +Z side of the integrated circuit 201 so as to correspond respectively to the plurality of ejectors 600. The drive voltage signal Vin output from the integrated circuit 201 propagates through the flexible board 24, and is then commonly supplied to the piezoelectric element 60a and the piezoelectric element 60b provided to the ejector 600 corresponding to the drive voltage signal Vin. That is, the wiring lines 311, 312, and 313 described above are formed on the flexible board 24 and the vibration plate 304.
Then, the drive voltage signal Vin1 as the drive voltage signal Vin propagated through the wiring lines 311, 312 formed on the flexible board 24 and the vibration plate 304 is supplied to the piezoelectric element 60a provided to the ejector 600 corresponding to the drive voltage signal Vin, and the drive voltage signal Vin2 as the drive voltage signal Vin propagated through the wiring lines 311, 313 formed on the flexible board 24 and the vibration plate 304 is supplied to the piezoelectric element 60b provided to the ejector 600 corresponding to the drive voltage signal Vin. As a result, each of the M piezoelectric elements 60a, 60b is driven to be displaced along the Z axis. Then, the vibration plate 304 provided with the piezoelectric elements 60a, 60b is displaced along the Z axis by driving the piezoelectric elements 60a, 60b, and the volumes of the pressure chambers CB1, CB2 are changed by the displacement of the vibration plate 304. Then, the internal pressure of the pressure chambers CB1, CB2 changes in accordance with the volume change of the pressure chambers CB1, CB2.
Here, the wiring line 311 propagating the drive voltage signal Vin is preferably formed on the flexible board 24 provided with the integrated circuit 201 in which the drive signal selection circuit 200 is implemented, and the wiring line 312 propagating the drive voltage signal Vin1 and the wiring line 313 propagating the drive voltage signal Vin2 are preferably formed on the vibration plate 304 provided with the piezoelectric elements 60a, 60b. That is, it is preferable that the coupling point at which the flexible board 24 and the vibration plate 304 are electrically coupled to each other corresponds to the node 315 described above.
As a result, there is no need to individually provide a wiring pattern for propagating the drive voltage signal Vin1 to the piezoelectric element 60a and a wiring pattern for propagating the drive voltage signal Vin2 to the piezoelectric element 60b to the flexible board 24, and it becomes possible to reduce the number of the wiring lines formed on the flexible board 24. That is, the reduction in size of the flexible board 24 can be realized.
Further, by forming the wiring line 312 that is formed on the flexible board 24 provided with the integrated circuit 201 in which the drive signal selection circuit 200 is implemented, and is propagated by the drive voltage signal Vin1, and the wiring line 313 that is formed on the flexible board 24 provided with the integrated circuit 201 in which the drive signal selection circuit 200 is implemented, and is propagated by the drive voltage signal Vin2, on the vibration plate 304 provided with the piezoelectric elements 60a, 60b, the node 315 can be formed in the vicinity of the piezoelectric elements 60a, 60b and on the vibration plate 304. That is, the electrical distance between the piezoelectric element 60a and the node 315 can be made shorter than the electrical distance between the node 315 and the transfer gates 234a, 234b, and 234c corresponding thereto.
As a result, the wiring length of the wiring line 312 and the wiring length of the wiring line 313 become shorter than the wiring length of the wiring line 311. Therefore, the influence of the impedance components of the wiring lines 312, 313 in the propagation paths of the drive voltage signals Vin1, Vin2 is reduced. In other words, the influence of an impedance difference between the impedance of the wiring line 312 propagated by the drive voltage signal Vin1 and the impedance of the wiring line 313 propagated by the drive voltage signal Vin2 is reduced. That is, the impedance of the wiring line 312 and the impedance of the wiring line 313, that are the impedance of the propagation path propagated by the drive voltage signal Vin1 and the residual vibration signal Vout1 and the impedance of the propagation path propagated by the drive voltage signal Vin2 and the residual vibration signal Vout2, can be made substantially equivalent. In other words, a resistance value between the transfer gate 234a provided to the drive signal selection circuit 200 implemented in the integrated circuit 201 and the piezoelectric element 60a can be made substantially equal to a resistance value between the transfer gate 234a provided to the drive signal selection circuit 200 implemented in the integrated circuit 201 and the piezoelectric element 60b, and a resistance value between the transfer gate 234b provided to the drive signal selection circuit 200 implemented in the integrated circuit 201 and the piezoelectric element 60a can be made substantially equal to a resistance value between the transfer gate 234b provided to the drive signal selection circuit 200 implemented in the integrated circuit 201 and the piezoelectric element 60b.
As a result, a possibility that a difference in signal waveform occurs between the drive voltage signal Vin1 corresponding to the drive voltage signal Vin and the drive voltage signal Vin2 corresponding to the drive voltage signal Vin decreases, and the signal waveform of the drive voltage signal Vin1 to be supplied to the piezoelectric element 60a and the signal waveform of the drive voltage signal Vin2 to be supplied to the piezoelectric element 60b can be made substantially equivalent. As a result, the drive amount of the piezoelectric element 60a driven in accordance with the drive voltage signal Vin1 and the drive amount of the piezoelectric element 60b driven in accordance with the drive voltage signal Vin2 can be made substantially equivalent.
Further, the compliance sheets 361, 362 are located at the +Z side of the communication plate 302. The compliance sheet 361 closes the supply flow path RA1 and the coupling flow paths RK1 provided to the communication plate 302. Such a compliance sheet 361 is formed including an elastic material. As a result, the pressure fluctuation generated in the supply flow path RA1 and the coupling flow paths RK1 in accordance with the variation of the internal pressure of the pressure chambers CB1, CB2 is absorbed. Further, the compliance sheet 362 closes the discharge flow path RA2 and the coupling flow paths RK2 provided to the communication plate 302. Such a compliance sheet 362 is formed including an elastic material. As a result, pressure fluctuation generated in the discharge flow path RA2 and the coupling flow paths RK2 in accordance with the variation of the internal pressure of the pressure chambers CB1, CB2 is absorbed.
Here, in the print head 21, the configuration that includes the piezoelectric elements 60a, 60b, the pressure chambers CB1, CB2, the communication flow paths RR1, RR2, and the nozzles N, and is provided to the head chip 22 corresponds to the ejector 600 described above.
As described above, the print head 21 of the present embodiment has the pressure chambers CB1 that change in volume in accordance with the drive voltage signals Vin according to the drive signals COM, the pressure chambers CB2 that change in volume in accordance with the drive voltage signals Vin according to the drive signals COM, the nozzles N that are communicated with the pressure chambers CB1 and the pressure chambers CB2 to eject the ink, the piezoelectric elements 60a for outputting the residual vibration signal Vout1 corresponding to the residual vibration generated in accordance with the volume change of the pressure chamber CB1, and the piezoelectric elements 60b for outputting the residual vibration signal Vout2 corresponding to the residual vibration generated in accordance with the volume change of the pressure chamber CB2. Further, the piezoelectric element 60a is displaced in accordance with the drive voltage signal Vin according to the drive signal COM, the volume of the pressure chamber CB1 changes in accordance with the displacement of the piezoelectric element 60a, the piezoelectric element 60b is displaced in accordance with the drive voltage signal Vin according to the drive signal COM, the volume of the pressure chamber CB2 changes in accordance with the displacement of the piezoelectric element 60b, and the ink is ejected from the nozzle N in accordance with the change in volume of the pressure chamber CB1 and the change in volume of the pressure chamber CB2.
Here, in the print head 21 of the present embodiment, the description will be presented assuming that the element that generates the residual vibration in the pressure chamber CB1 and the element that detects the residual vibration generated in the pressure chamber CB1 are both the piezoelectric element 60a, and the element that generates residual vibration in the pressure chamber CB2 and the element that detects the residual vibration generated in the pressure chamber CB2 are both the piezoelectric elements 60b. However, the element that generates the residual vibration in the pressure chamber CB1 and the element that detects the residual vibration generated in the pressure chamber CB1 may be different from each other, and the element that generates the residual vibration in the pressure chamber CB2 and the element that detects the residual vibration generated in the pressure chamber CB2 may be different from each other.
However, it is preferable that the piezoelectric element 60a generates the residual vibration in the pressure chamber CB1 and detects the residual vibration generated in the pressure chamber CB1, and the piezoelectric element 60b generates the residual vibration in the pressure chamber CB2 and detects the residual vibration generated in the pressure chamber CB2 as shown in the present embodiment. That is, it is preferable that the piezoelectric element 60a outputs the residual vibration signal Vout1 according to the residual vibration generated in accordance with the volume change of the pressure chamber CB1, and is driven in accordance with the drive voltage signal Vin according to the drive signal COM, and the volume of the pressure chamber CB1 is changed by driving the piezoelectric element 60a, and it is preferable that the piezoelectric element 60b outputs the residual vibration signal Vout2 according to the residual vibration generated in accordance with the volume change of the pressure chamber CB2, and is driven in accordance with the drive voltage signal Vin according to the drive signal COM, and the volume of the pressure chamber CB2 is changed by driving the piezoelectric element 60b. As a result, the number of the piezoelectric elements 60a, 60b provided to the print head 21 can be reduced, and it becomes possible to reduce the size of the print head 21.
A specific example of the flow of the ink in the print head 21 configured as described above will be described.
As shown in
The ink supplied to the print head 21 through the supply port 351 flows into the supply flow path RA1 via the supply flow path RB1. The ink flowing into the supply flow path RA1 branches for each of the M nozzles N and flows into the pressure chambers CB1 via the coupling flow paths RK1 corresponding to the pressure chambers CB1. This supplies the ink to the pressure chambers CB1. Further, the ink flowing into the pressure chamber CB1 flows into the pressure chamber CB2 via the communication flow path RR1, the nozzle flow path RN, and the communication flow path RR2. This supplies the ink to the pressure chamber CB2. Then, the ink flowing into the pressure chamber CB2 flows out from the coupling flow path RK2. On this occasion, the ink flowing out from the M coupling flow paths RK2 corresponding respectively to the M nozzles N merges in the discharge flow path RA2. The ink having merged in the discharge flow path RA2 is discharged from the print head 21 through the discharge flow path RB2 and through the discharge port 352.
The ink discharged from the print head 21 through the discharge port 352 flows through a tube 64 and flows back to the circulation unit 6. Subsequently, the circulation unit 6 supplies the ink returned from the print head 21 and the ink retained in the liquid container 3 to the print head 21. That is, the print head 21 of the present embodiment includes the supply port 351 and the discharge port 352, and the ink supplied from the supply port 351 is discharged from the discharge port 352 through the pressure chamber CB1 and the pressure chamber CB2, and at least a part of the ink discharged from the discharge port 352 is returned to the supply port 351. Thus, the possibility that the ink is retained inside the print head 21 is reduced, and as a result, the possibility that physical properties such as viscosity of the ink retained inside the print head 21 are changed is reduced.
As described above, the pressure chambers CB1, CB2 are filled with the ink retained in the liquid container 3 and the ink returned by the circulation unit 6. Then, the ink filling the pressure chambers CB1, CB2 is ejected from the nozzle N in accordance with the volume change of the pressure chambers CB1, CB2 due to the respective drive of each of the M piezoelectric elements 60a, 60b. A specific example of such an ink ejection operation in the print head 21 will be described.
When drawing the ink into the pressure chambers CB1, CB2 as shown in
Further, when ejecting the ink filling the pressure chambers CB1, CB2 as shown in
In the liquid ejection apparatus 1 according to the present embodiment, by repeatedly executing drawing of the ink into the pressure chambers CB1, CB2 as shown in
Here, details of the operation of ejecting the ink from the print head 21 in the liquid ejection apparatus 1 according to the present embodiment will be described. In the liquid ejection apparatus 1 according to the present embodiment, the description will be presented assuming that when the voltage value of the drive voltage signal Vin input to the print head 21 decreases, the center portions of the piezoelectric elements 60a, 60b corresponding to the drive voltage value Vin are displaced along the Z axis toward the −Z side, and when the voltage value of the drive voltage signal Vin input to the print head 21 increases, the center portions of the piezoelectric elements 60a, 60b corresponding to the drive voltage signal Vin are displaced along the Z axis toward the +Z side. Incidentally, the relationship between the voltage value of the drive voltage signal Vin and the displacement of the piezoelectric elements 60a, 60b is not limited to the above, and there may be adopted a configuration in which when the voltage value of the drive voltage signal Vin input to the print head 21 decreases, the center portions of the piezoelectric elements 60a, 60b corresponding thereto are displaced along the Z axis toward the +Z side, and when the voltage value of the drive voltage signal Vin input to the print head 21 increases, the center portions of the piezoelectric elements 60a, 60b corresponding thereto are displaced along the Z axis toward the −Z side.
Further, the ink ejection operation in the print head 21 is caused by the voltage value of the drive voltage signal Vin input thereto. That is, the print head 21 performs substantially the same operation except only the amount of the ink to be ejected different between when the signal waveform of the drive voltage signal Vin input thereto is the drive waveform Adp1 and when the signal waveform of the drive voltage signal Vin input thereto is the drive waveform Adp2, Bdp1, Bdp2, or Bdp3. Therefore, in the following description, there is illustrated when the drive voltage signal Vin including the drive waveform Adp1 is input to the print head 21, and there is omitted when the drive voltage signal Vin including the drive waveform Adp2, Bdp1, Bdp2, or Bdp3 is input to the print head 21.
The voltage value of the drive voltage signal Vin including the drive waveform Adp1 input to the print head 21 is constant at the voltage Vc at the timing when the latch signal LAT rises. Therefore, at the rise of the latch signal LAT, the voltage Vc is supplied to the piezoelectric element 60a as the drive voltage signal Vin1, and the voltage Vc is supplied to the piezoelectric element 60b as the drive voltage signal Vin2. Subsequently, the voltage value of the drive voltage signal Vin input to the print head 21 decreases. Therefore, both the voltage value of the drive voltage signal Vin1 supplied to the piezoelectric element 60a and the voltage value of the drive voltage signal Vin2 supplied to the piezoelectric element 60b decrease. Then, due to the decrease in the voltage value of the drive voltage signal Vin1 supplied to the piezoelectric element 60a, the center portion of the piezoelectric element 60a is displaced along the Z axis toward the −Z side, and due to the decrease in the voltage value of the drive voltage signal Vin2 supplied to the piezoelectric element 60b, the center portion of the piezoelectric element 60b is displaced along the Z axis toward the −Z side. Therefore, the vibration plate 304 is displaced toward the −Z side, and the volume of the pressure chamber CB1 and the volume of the pressure chamber CB2 increase. As a result, a corresponding amount of the ink to the increment in volume is drawn into the pressure chambers CB1, CB2. Subsequently, the voltage value of the drive voltage signal Vin input to the print head 21 is held at a constant voltage value for a predetermined period.
When the predetermined period elapses, the voltage value of the drive voltage signal Vin input to the print head 21 increases to a voltage value equal to or higher than the voltage Vc. Therefore, both the voltage value of the drive voltage signal Vin1 supplied to the piezoelectric element 60a and the voltage value of the drive voltage signal Vin2 supplied to the piezoelectric element 60b increase. Then, due to the increase in the voltage value of the drive voltage signal Vin1 supplied to the piezoelectric element 60a, the center portion of the piezoelectric element 60a is displaced along the Z axis toward the +Z side, and due to the increase in the voltage value of the drive voltage signal Vin2 supplied to the piezoelectric element 60b, the center portion of the piezoelectric element 60b is displaced along the Z axis toward the +Z side. Therefore, the vibration plate 304 is displaced toward the +Z side, and the volume of the pressure chamber CB1 and the volume of the pressure chamber CB2 decrease. As a result, a corresponding amount of the ink to the decrease in the volume of the pressure chamber CB1 flows along the arrow F1 shown in
On this occasion, the voltage value of the drive voltage signal Vin1 supplied to the piezoelectric element 60a and the voltage value of the drive voltage signal Vin2 supplied to the piezoelectric element 60b are substantially equivalent since the drive voltage signals Vin1, Vin2 are branched from the drive voltage signal Vin output by the drive signal selection circuit 200. Therefore, the displacement amount of the piezoelectric element 60a according to the drive voltage signal Vin is substantially equal to the displacement amount of the piezoelectric element 60b according to the drive voltage signal Vin, and therefore, the change amount of the volume of the pressure chamber CB1 due to the displacement of the piezoelectric element 60a is substantially equal to the change amount of the volume of the pressure chamber CB2 due to the displacement of the piezoelectric element 60b.
Further, as described above, the pressure chamber CB1 and the pressure chamber CB2 have substantially equivalent structures formed so as to substantially be line symmetrical taking the Z axis passing through the nozzle N as the axis of symmetry, the communication flow path RR1 and the communication flow path RR2 have substantially equivalent structures formed so as to substantially be line symmetrical taking the Z axis passing through the nozzle N as the axis of symmetry, and further, the nozzle N is located at substantially the center of the nozzle flow path RN. In view of such a point, the flow path length of the flow path that communicates the pressure chamber CB1 and the nozzle N with each other, and through which the ink filling the pressure chamber CB1 flows to the nozzle N, and the flow path length of the flow path that communicates the pressure chamber CB2 and the nozzle N with each other, and through which the ink filling the pressure chamber CB2 flows to the nozzle N are substantially equal to each other.
Further, since the displacement amount of the piezoelectric element 60a in accordance with the drive voltage signal Vin and the displacement amount of the piezoelectric element 60b in accordance with the drive voltage signal Vin are substantially equal to each other, an amount of the ink flowing from the pressure chamber CB1 toward the nozzle N due to the displacement of the piezoelectric element 60a and an amount of the ink flowing from the pressure chamber CB2 toward the nozzle N due to the displacement of the piezoelectric element 60b are substantially equal to each other, and the speed of the ink that flows in the flow path communicating the pressure chamber CB1 and the nozzle N from the pressure chamber CB1 toward the nozzle N due to the displacement of the piezoelectric element 60a and the speed of the ink that flows in the flow path communicating the pressure chamber CB2 and the nozzle N from the pressure chamber CB2 toward the nozzle N due to the displacement of the piezoelectric element 60b are substantially equal to each other.
Further, in view of the point that the pressure chamber CB1 and the pressure chamber CB2 have substantially equivalent structures formed so as to substantially be line symmetrical taking the Z axis passing through the nozzle N as the axis of symmetry, the communication flow path RR1 and the communication flow path RR2 have substantially equivalent structures formed so as to substantially be line symmetrical taking the Z axis passing through the nozzle N as the axis of symmetry, and further, the nozzle N is located at substantially center of the nozzle flow path RN, the direction in which the ink that flows from the pressure chamber CB1 toward the nozzle N due to the displacement of the piezoelectric element 60a flows through the flow path communicating the pressure chamber CB1 and the nozzle N with each other and the direction in which the ink that flows from the pressure chamber CB2 toward the nozzle N due to the displacement of the piezoelectric element 60b flows through the flow path communicating the pressure chamber CB2 and the nozzle N with each other are reverse from each other.
Here, the phrase that the direction in which the ink flowing from the pressure chamber CB1 toward the nozzle N flows and the direction in which the ink flowing from the pressure chamber CB2 toward the nozzle N flows are reversed from each other is not limited to when these directions are opposite to each other, but includes, for example, when the direction in which the ink flowing from the pressure chamber CB1 toward the nozzle N flows and the direction in which the ink flowing from the pressure chamber CB2 toward the nozzle N flows are substantially symmetrical taking the Z axis passing through the nozzle N as the axis of symmetry. Further, in a broader sense, there may be provided a direction in which the ink that flows from the pressure chamber CB1 toward the nozzle N flows from the −X side of the Z axis passing through the nozzle N toward the Z axis passing through the nozzle N, and a direction in which the ink flows from the +X side of the Z axis passing through the nozzle N toward the Z axis passing through the nozzle N.
In the print head 21, which is configured and operates as described above, the ink that flows out in accordance with the decrement in the volume of the pressure chamber CB1 and the ink that flows in accordance with the decrement in the volume of the pressure chamber CB2 merge at the −Z side of the nozzle N. As a result, the ink merged at the −Z side of the nozzle N is accurately ejected from the nozzle N along the Z axis in the direction indicated by the arrow Dl shown in
After the ink is ejected from the print head 21, the voltage value of the drive voltage signal Vin is held at a constant voltage value for a predetermined period. Then, when the predetermined period elapses, the voltage value of the drive voltage signal Vin input to the print head 21 drops to the voltage Vc the same in voltage value as that at the timing of rise of the latch signal LAT. Therefore, both the voltage value of the drive voltage signal Vin1 supplied to the piezoelectric element 60a and the voltage value of the drive voltage signal Vin2 supplied to the piezoelectric element 60b decrease. Then, due to the decrease in the voltage value of the drive voltage signal Vin1 supplied to the piezoelectric element 60a, the center portion of the piezoelectric element 60a is displaced along the Z axis toward the +Z side, and due to the decrease in the voltage value of the drive voltage signal Vin2 supplied to the piezoelectric element 60b, the center portion of the piezoelectric element 60b is displaced along the Z axis toward the +Z side. Thus, the displacement amount of the piezoelectric element 60a and the displacement amount of the piezoelectric element 60b are displacement amounts before the drive voltage signal Vin of the drive waveform Adp1 is supplied, and are substantially equivalent to the displacement amount immediately before the latch signal LAT rises. Therefore, the volume of the pressure chamber CB1 and the volume of the pressure chamber CB2 are also substantially equivalent to the volume at the timing of the rise of the latch signal LAT. Subsequently, the voltage value of the drive voltage signal Vin is held at the voltage Vc.
The print head 21 of the present embodiment configured as described above ejects the ink filling the inside of the pressure chamber CB1 and the ink filling the inside of the pressure chamber CB2 from the nozzle N using the piezoelectric elements 60a, 60b which are commonly driven in accordance with the drive voltage signal Vin1. Therefore, the driving capacity can be increased compared to the configuration in which the ink filling the inside of one pressure chamber is ejected with one piezoelectric element. As a result, the print head 21 of the present embodiment can increase the amount of the ink ejected, and also achieve stable ejection characteristics even when ink high in viscosity is used.
Furthermore, the print head 21 of the present embodiment can eject the ink along the Z axis toward the +Z side with high accuracy even when the ink is ejected from one nozzle N based on the volume change of the pressure chamber CB1 and the volume change of the pressure chamber CB2. Thus, the landing accuracy of the ejected ink on the medium P can be improved, and as a result, the quality of an image to be formed on the medium P can be enhanced.
Then, a specific example of the residual vibration signal Vout according to the residual vibration generated in the ejector 600 as the inspection target after the drive voltage signal Vin is supplied to the ejector 600 as the inspection target will be described. After the piezoelectric elements 60a, 60b provided to the ejector 600 as the inspection target are driven in accordance with the drive voltage signal Vin, the liquid ejection apparatus 1 according to the present embodiment acquires the residual vibration signal Vout corresponding to the residual vibration generated in the ejector 600 as the inspection target, and determines the state of the ejector 600 as the inspection target based on the residual vibration signal Vout thus acquired.
Specifically, the control circuit 100 outputs the print data SId [SIH, SIM, SIL]=[1, 1, 1] as the print data SId corresponding to the ejector 600 as the inspection target. Thus, the switching circuit 210 supplies the drive voltage signal Vin including the drive waveform Bdp1 to the ejector 600 as the inspection target in the period ts1.
The piezoelectric element 60a provided to the ejector 600 as the inspection target is driven by being supplied with the drive voltage signal Vin1 including the drive waveform Bdp1. Then, the vibration plate 304 is displaced by driving the piezoelectric element 60a, and the internal pressure of the pressure chamber CB1 changes due to the displacement of the vibration plate 304. Subsequently, by supplying the drive voltage signal Vin1 constant at the voltage Vd to the piezoelectric element 60a, a damped vibration due to a change in the internal pressure of the pressure chamber CB1 occurs in the vibration plate 304. This damped vibration generated in the vibration plate 304 displaces the piezoelectric element 60a, and the piezoelectric element 60a outputs counter-electromotive force corresponding to the displacement as the residual vibration signal Vout1.
Similarly, the piezoelectric element 60b provided to the ejector 600 as the inspection target is driven by being supplied with the drive voltage signal Vin2 including the drive waveform Bdp1. Then, the vibration plate 304 is displaced by driving the piezoelectric element 60b, and the internal pressure of the pressure chamber CB2 changes due to the displacement of the vibration plate 304. Subsequently, by supplying the drive voltage signal Vin2 constant at the voltage Vd to the piezoelectric element 60b, a damped vibration due to a change in the internal pressure of the pressure chamber CB2 occurs in the vibration plate 304. This damped vibration generated in the vibration plate 304 displaces the piezoelectric element 60b, and the piezoelectric element 60b outputs counter-electromotive force corresponding to the displacement as the residual vibration signal Vout2.
Here, the relationship between the waveform information of the residual vibration signals Vout1, Vout2 and the state of the ink retained in the pressure chambers CB1, CB2, the state of the ink flowing through the communication flow paths RR1, RR2, and the nozzle flow paths RN will be described using a calculation model.
In such a series of operations of ejecting the ink from the nozzle N, the vibration plate 304 freely vibrates with a natural vibration frequency determined by a flow path resistance r based on the shape of the flow path through which the ink flows, the viscosity of the ink, or the like, an inertance m due to the liquid weight in the flow path, and a compliance C of the vibration plate 304, and the piezoelectric elements 60a, 60b are displaced in accordance with the free vibration generated in the vibration plate 304. Then, the piezoelectric element 60a outputs the counter-electromotive force in accordance with the displacement as the residual vibration signal Vout1, and the piezoelectric element 60b outputs the counter-electromotive force in accordance with the displacement as the residual vibration signal Vout2.
Such a calculation model of the residual vibration generated in the vibration plate 304 can be expressed by a pressure p, the inertance m, the compliance C, and the flow path resistance r. Then, by calculating the step response when applying the pressure p to the circuit shown in
As shown in
Further,
As shown in
As described above, when the thickening abnormality in which the viscosity of the ink increases, or a bubble infiltration abnormality in which bubbles infiltrate occurs in the pressure chamber CB1, the communication flow path RR1, the nozzle flow path RN, and so on, waveform information such as the amplitude and frequency of the residual vibration signal Vout1 changes, and similarly, when the thickening abnormality or the bubble infiltration abnormality occurs in the pressure chamber CB2, the communication flow path RR2, the nozzle flow path RN, and so on, the waveform information such as the amplitude and frequency of the residual vibration signal Vout2 changes. Therefore, the state of the ejector 600 including the piezoelectric elements 60a, 60b which output the residual vibration signals Vout1, Vout2 can be determined based on the waveform information such as the amplitude and frequency of the residual vibration signals Vout1, Vout2.
Here, when the drive signal selection circuit 200 supposedly acquires both the residual vibration signal Vout1 and the residual vibration signal Vout2 individually, and the control circuit 100 supposedly calculates the waveform information such as the amplitude and frequency of the residual vibration signal Vout1 and the waveform information such as the amplitude and frequency of the residual vibration signal Vout2 separately, it may be possible to determine the state of the ejector 600 even in the configuration in which the ejector 600 as the inspection target has the pressure chamber CB1 and the pressure chamber CB2.
However, in the configuration in which the ejector 600 as the inspection target has the pressure chamber CB1 and the pressure chamber CB2, when both the residual vibration signal Vout1 and the residual vibration signal Vout2 are individually acquired, and the state of the ejector 600 is determined, the drive signal selection circuit 200 needs to have a configuration for switching whether to acquire the residual vibration signal Vout1 or to acquire the residual vibration signal Vout2, and as a result, there is a concern that the integrated circuit 201 in which the drive signal selection circuit 200 is implemented grows in size. The growth in size of the integrated circuit 201 makes it difficult to COF-mount the integrated circuit 201 on the flexible board 24, and the growth in size of the print head 21 is concerned, and when the integrated circuit 201 is provided to the head circuit board 23 or the like different from the flexible board 24, there is a possibility that the waveform accuracy of the drive voltage signal Vin output by the drive signal selection circuit 200 is deteriorated.
Further, in the configuration in which the ejector 600 as the inspection target has the pressure chamber CB1 and the pressure chamber CB2, when both the residual vibration signal Vout1 and the residual vibration signal Vout2 are individually acquired and the state of the ejector 600 is determined, it is necessary to sequentially acquire both the residual vibration signal Vout1 and the residual vibration signal Vout2 and to individually determine the waveform information of the residual vibration signal Vout1 and the waveform information of the residual vibration signal Vout2, and as a result, a significant increase in state determination time of the ejector 600 is also concerned.
With respect to such a problem, in the liquid ejection apparatus 1 according to the present embodiment, the drive signal selection circuit 200 acquires the residual vibration signal Vout obtained by combining the residual vibration signal Vout1 and the residual vibration signal Vout2 with each other, to output the residual vibration signal NVT according to the residual vibration signal Vout. Then, the AD conversion circuit 300 converts the residual vibration signal NVT into the residual vibration signal dNVT as a digital signal, and the control circuit 100 determines the state of the ejector 600 as the inspection target based on the residual vibration signal dNVT. Thus, the configuration for switching whether to acquire the residual vibration signal Vout1 corresponding to the pressure chamber CB1 or to acquire the residual vibration signal Vout2 corresponding to the pressure chamber CB2 is not required, and the reduction in size of the integrated circuit 201 in which the drive signal selection circuit 200 is implemented is realized, and since the integrated circuit 201 is small in size, it is easy to COF-mount the integrated circuit 201 on the flexible board 24, and as a result, the reduction in size of the print head 21 can be realized, and the possibility that the accuracy of the drive voltage signal Vin is deteriorated is reduced.
Here, the method of determining the state of the ejector 600 based on the residual vibration signal Vout obtained by combining the residual vibration signal Vout1 and the residual vibration signal Vout2 with each other will be described. In describing the method of determining the state of the ejector 600 based on the residual vibration signal Vout, first, an example of the signal waveform of the residual vibration signal Vout obtained by combining the residual vibration signal Vout1 and the residual vibration signal Vout2 with each other will be described.
As shown in
As shown in
As shown in
As described above, when the pressure chamber CB1 corresponding to the residual vibration signal Vout1 and the pressure chamber CB2 corresponding to the residual vibration signal Vout2 are both normal, both the frequency and the amplitude of the residual vibration signal Vout as the composite wave of the residual vibration signal Vout1 and the residual vibration signal Vout2 are in predetermined ranges. On the other hand, when the viscosity of the ink retained in at least one of the pressure chamber CB1 corresponding to the residual vibration signal Vout1 and the pressure chamber CB2 corresponding to the residual vibration signal Vout2 increases, the amplitude of the residual vibration signal Vout becomes smaller compared to when the pressure chamber CB1 corresponding to the residual vibration signal Vout1 and the pressure chamber CB2 corresponding to the residual vibration signal Vout2 are both normal, and further, when bubbles infiltrate at least one of the pressure chamber CB1 corresponding to the residual vibration signal Vout1 and the pressure chamber CB2 corresponding to the residual vibration signal Vout2, at least one of the phase and the frequency of the residual vibration signal Vout becomes out of the predetermined range when both the pressure chamber CB1 corresponding to the residual vibration signal Vout1 and the pressure chamber CB2 corresponding to the residual vibration signal Vout2 are normal. That is, when an abnormality occurs in at least one of the pressure chamber CB1 corresponding to the residual vibration signal Vout1 and the pressure chamber CB2 corresponding to the residual vibration signal Vout2, the amplitude and the period of the residual vibration signal Vout change.
In the liquid ejection apparatus 1 according to the present embodiment, it is possible to determine whether the ejector 600 as the inspection target is normal based on at least one of the amplitude and the frequency of the residual vibration signal Vout. Note that the liquid ejection apparatus 1 may determine whether the ejector 600 as the inspection target is normal based on various waveform information in addition to amplitude and frequency. Further, of course, the amplitude of the residual vibration signal Vout includes the waveform information that can be calculated from the amplitude such as an attenuation rate, and the frequency of the residual vibration signal Vout includes the waveform information that can be calculated based on the frequency such as the period or the phase.
Here, a specific example of a method of determining the state of the print head 21 based on the residual vibration signal Vout, that is a method of determining the state of the ejector 600 as the inspection target provided to the print head 21 will be described.
First, a specific example of the residual vibration generation step (step S1) will be described.
The print data signal SI including the print data SId [SIH, SIM, SIL]=[1, 1, 1] output by the control circuit 100 is input to the drive signal selection circuit 200 provided to the print head 21. The drive signal selection circuit 200 supplies (step S120) the piezoelectric elements 60a, 60b corresponding to the ejector 600 as the inspection target with the drive voltage signal Vin corresponding to the state inspection CD by controlling the conduction state of the selection circuit 230 corresponding to the ejector 600 as the inspection target in accordance with the print data SId [SIH, SIM, SIL]=[1, 1, 1] input thereto. Thus, the piezoelectric elements 60a, 60b provided to the ejector 600 as the inspection target are driven, and the volumes of the pressure chamber CB1 corresponding to the piezoelectric element 60a and the pressure chamber CB2 corresponding to the piezoelectric element 60b are changed. As a result, the residual vibration is generated in the pressure chamber CB1 and the residual vibration is generated in the pressure chamber CB2. Then, the piezoelectric element 60a provided to the ejector 600 as the inspection target provided to the print head 21 outputs the residual vibration signal Vout1 of the counter-electromotive force corresponding to the residual vibration generated in the pressure chamber CB1, and the piezoelectric element 60b provided to the ejector 600 as the inspection target outputs the residual vibration signal Vout2 of the counter-electromotive force corresponding to the residual vibration generated in the pressure chamber CB2 (step S130). This ends the residual vibration generation step (step S1).
That is, in the residual vibration generation step (step S1) of the present embodiment, the volume of the pressure chamber CB1 is changed by driving the piezoelectric element 60a in accordance with the drive voltage signal Vin based on the drive signal COM, and the volume of the pressure chamber CB2 is changed by driving the piezoelectric element 60b in accordance with the drive voltage signal Vin based on the drive signal COM. Then, the piezoelectric element 60a outputs the residual vibration signal Vout1 according to the residual vibration generated in the pressure chamber CB1, and the piezoelectric element 60b outputs the residual vibration signal Vout2 according to the residual vibration generated in the pressure chamber CB2.
Then, a specific example of the signal conversion step (step S2) will be described.
That is, the signal conversion step (step S2) includes the step of extracting the signal of the AC component contained in the residual vibration signal Vout and the step of amplifying the signal of the AC component extracted from the residual vibration signal Vout.
The residual vibration signal NVT output by the drive signal selection circuit 200 is input to the AD conversion circuit 300. The AD conversion circuit 300 converts the voltage value of the residual vibration signal NVT input thereto into a digital signal, and acquires the digital signal as a detection voltage dnvt (step S250). Then, the AD conversion circuit 300 outputs (step S260) the residual vibration signal dNVT including the detection voltage dnvt input thereto.
The residual vibration signal dNVT including the detection voltage dnvt output by the AD conversion circuit 300 is input to the control circuit 100. The control circuit 100 stores the value obtained by subtracting a predetermined reference value from the detection voltage dnvt contained in the residual vibration signal dNVT as a holding voltage value snvt[j](step S270). Subsequently, the drive signal selection circuit 200 determines (step S280) whether the inspection timing signal TSIG has risen. When the drive signal selection circuit 200 determines that the inspection timing signal TSIG has not risen (N in step S280), the control circuit 100 adds 1 to the variable j (step S290) and repeats the processing in steps S250 to S280 described above. Here, the predetermined reference value is a value of the DC component to be superimposed on the residual vibration signal NVT, and is ideally “0” in the present embodiment.
That is, the AD conversion circuit 300 sequentially converts the voltage value of the residual vibration signal NVT input during the period ts2 that is a period from when the inspection timing signal TSIG rises to when the inspection timing signal TSIG subsequently rises into a digital signal at timings based on a sampling period to convert the result into the detection voltage dnvt as the digital signal thus converted. Then, the control circuit 100 sequentially stores the detection voltage dnvt input from the AD conversion circuit 300 as the holding voltage value snvt[j] at a timing based on the sampling period.
Subsequently, by the drive signal selection circuit 200 determining that the inspection timing signal TSIG has risen (Y in step S280), the drive signal selection circuit 200 determines that the acquisition of the detection voltage dvnt, that is the voltage value of the residual vibration signal NVT in the period ts2, is completed. This ends the signal conversion step (step S2).
Then, a specific example of the determination step (step S3) will be described.
When the determination step (step S3) starts, the control circuit 100 reads out (step S310) the holding voltage values snvt[1] to snvt[p] stored therein. Then, the control circuit 100 extracts a holding voltage value snvt at the timing when the voltage value switches from a positive value to a negative value or from a negative value to a positive value from the holding voltage values snvt[1] to snvt[p] thus read out. Here, in the following description, the holding voltage value snvt at the timing at which the voltage value is changed from a positive value to a negative value or from a negative value to a positive value for the first time after the inspection timing signal TSIG rises is referred to as a reversal voltage value vn[p1], and the holding voltage value snvt at the timing at which the voltage value is changed from a positive value to a negative value or from a negative value to a positive value for the last time after the inspection timing signal TSIG rises, that is the holding voltage value snvt at the timing at which the voltage value is changed from a positive value to a negative value or from a negative value to a positive value for the s-th time, is referred to as a reversal voltage value vn[ps]. That is, the control circuit 100 extracts (step S320) the reversal voltage values vn[p1] to vn[ps] at the timings when the voltage value switches from a positive value to a negative value or from a negative value to a positive value from the holding voltage values svnt[1] to svnt[p] thus read out.
Then, the control circuit 100 calculates (step S330) a frequency Fnvt of the residual vibration signal Vout based on a reversal voltage value vn[pu](u is any one of 1 to s−2) and a reversal voltage value vn[p(u+2)] out of the reversal voltage values vn[p1] to vn[ps] thus extracted.
Specifically, the control circuit 100 calculates the number of the holding voltage values snvt obtained between the reversal voltage value vn[pu] and the reversal voltage value vn[p(u+2)]. Then, the control circuit 100 calculates the time from the reversal voltage value vn[pu] to the reversal voltage value vn[p(u+2)] from the number of the holding voltage values snvt thus calculated and the sampling period of the AD conversion circuit 300. The control circuit 100 calculates the frequency Fnvt of the residual vibration signal Vout based on the time thus calculated from the reversal voltage value vn[pu] to the reversal voltage value vn[p(u+2)].
Further, the control circuit 100 holds (step S340) the holding voltage value snvt the largest in absolute value among the holding voltage values snvt stored between a reversal voltage value vn[pv](v is one of 1 to s−1) and a reversal voltage value vn[p(v+1)] as a maximum voltage value Vpec[v]. Specifically, the control circuit 100 stores the holding voltage value snvt the largest in absolute value out of the holding voltage values snvt stored between the reversal voltage value vn[p1] and a reversal voltage value vn[p2] as a maximum voltage value Vpek[1], and similarly holds the holding voltage value snvt the largest in absolute value out of the holding voltage values snvt held between the reversal voltage value vn[pv] and the reversal voltage value vn[p(v+1)] as the maximum voltage value Vpek[v], and holds the holding voltage value snvt the largest in absolute value out of the holding voltage values snvt stored between a reversal voltage value vn[p(s−1)] and the reversal voltage value vn[ps] as a maximum voltage value Vpek[s−1]. The maximum voltage value Vpek[v] held by the control circuit 100 corresponds to the amplitude generated in the residual vibration signal Vout. Then, the control circuit 100 calculates (step S350) an attenuation rate ARnvt of the amplitude of the residual vibration signal Vout based on the maximum voltage values Vpek[1] to Vpek[s−1] corresponding to the amplitude generated in the residual vibration signal Vout.
Subsequently, the control circuit 100 reads out (step S360) frequency upper limit threshold information FHth, frequency lower limit threshold information FLth, and amplitude determination threshold information ARth stored in advance. Here, the frequency upper limit threshold information FHth, the frequency lower limit threshold information FLth, and the amplitude determination threshold information ARth can be set based on the frequency, the amplitude, and the attenuation rate of the residual vibration signal Vout, which is the composite wave of the residual vibration signals Vout1, Vout2 output by the piezoelectric elements 60a, 60b when the pressure chambers CB1, CB2 are normal.
Then, the control circuit 100 determines whether the frequency Fnvt of the residual vibration signal Vout thus calculated is in between the frequency upper limit threshold information FHth and the frequency lower limit threshold information FLth. That is, the control circuit 100 determines (step S370) whether the frequency Fnvt is lower than the frequency upper limit threshold information FHth and whether the frequency Fnvt is higher than the frequency lower limit threshold information FLth. Then, when the frequency Fnvt is higher than or equal to the frequency upper limit threshold information FHth, or when the frequency Fnvt is lower than or equal to the frequency lower limit threshold information FLth (N in step S370), in other words, when the frequency Fnvt of the residual vibration signal Vout thus calculated is not in between the frequency upper limit threshold information FHth and the frequency lower limit threshold information FLth, the control circuit 100 determines (step S375) that the bubble infiltration abnormality has occurred in the ejector 600 as the inspection target, and ends the determination step.
Further, when the frequency Fnvt is lower than the frequency upper limit threshold information FHth and the frequency Fnvt is higher than the frequency lower limit threshold information FLth (Y in step S370), the control circuit 100 determines (step S380) whether the attenuation rate ARnvt of the amplitude of the residual vibration signal Vout is higher than the amplitude determination threshold information ARth. Then, when the attenuation rate ARnvt of the amplitude of the residual vibration signal Vnvt is higher than the amplitude determination threshold information ARth (Y in step S380), the control circuit 100 determines (step S385) that the thickening abnormality has occurred in the ejector 600 as the inspection target, and ends the determination step.
Further, when the attenuation rate ARnvt of the amplitude of the residual vibration signal Vnvt is lower than or equal to the amplitude determination threshold information ARth (N in step S380), the control circuit 100 determines (step S395) that the ejector 600 as the inspection target is normal and ends the determination step.
As described above, in the liquid ejection apparatus 1 according to the present embodiment, it is possible to determine whether the ejector 600 as the inspection target is normal based on the amplitude and the frequency of the residual vibration signal Vout. That is, in the determination step (step S3), at least one of the amplitude and the frequency of the residual vibration signal Vout and the residual vibration signal NVT is calculated based on the residual vibration signal dNVT to determine the state of the print head 21, that is the state of the ejector 600 as the inspection target provided to the print head 21, based on the calculation result. In other words, the control circuit 100 calculates at least one of the amplitude and the frequency of the residual vibration signal Vout and the residual vibration signal NVT based on the residual vibration signal dNVT to determine the state of the print head 21, that is the state of the ejector 600 as the inspection target provided to the print head 21, based on the calculation result.
Here, the drive signal ComA as the drive signal COM is an example of the drive signal, the piezoelectric element 60a, the piezoelectric element 60b, the pressure chamber CB1, the pressure chamber CB2, and the nozzle N provided to any one of the plurality of ejectors 600 provided to the print head 21 are examples of a first piezoelectric element, a second piezoelectric element, a first pressure chamber, a second pressure chamber, and a first nozzle, respectively, the drive voltage signal Vin input to the ejector 600 is an example of a first drive voltage, the selection circuit 230 corresponding to the ejector 600 is an example of a first switching circuit, the transfer gate 234a provided to the selection circuit 230 as an example of the first switching circuit is an example of a first switch element, and the selection signal Sa for controlling the transfer gate 234a as an example of the first switch element is an example of a first ejection control signal.
Further, the piezoelectric element 60a, the piezoelectric element 60b, the pressure chamber CB1, the pressure chamber CB2, and the nozzle N provided to a different one of the plurality of ejectors 600 provided to the print head 21 are examples of a third piezoelectric element, a fourth piezoelectric element, a third pressure chamber, a fourth pressure chamber, and a second nozzle, respectively, the drive voltage signal Vin input to the ejector 600 is an example of a second drive voltage, the selection circuit 230 corresponding to the ejector 600 is an example of a second switching circuit, the transfer gate 234a provided to the selection circuit 230 as an example of the second switching circuit is an example of a second switch element, and the selection signal Sa for controlling the transfer gate 234a as an example of the second switch element is an example of a second ejection control signal.
Further, the communication flow path RR1 that communicates the pressure chamber CB1 as an example of the first pressure chamber and the nozzle N as an example of the first nozzle with each other and a part of the nozzle flow path RN are an example of a first flow path, and the communication flow path RR2 that communicates the pressure chamber CB2 as an example of the second pressure chamber and the nozzle N as an example of the first nozzle with each other and another part of the nozzle flow path RN are an example of a second flow path. Further, the plurality of transfer gates 234a provided to the drive signal selection circuit 200 including the transfer gate 234a as an example of the first switch element and the transfer gate 234a as an example of the second switch element is an example of a plurality of switch elements.
The liquid ejection apparatus 1 and the print head 21 according to the present embodiment configured as described above include the selection circuit 230 to which the drive signal ComA as the drive signal COM is input, and which switches whether to output the drive voltage signal Vin according to the drive signal ComA, the piezoelectric element 60a that is displaced in accordance with the drive voltage signal Vin, the pressure chamber CB1 the volume of which changes due to the displacement of the piezoelectric element 60a, the piezoelectric element 60b that is displaced in accordance with the drive voltage signal Vin, the pressure chamber CB2 the volume of which changes due to the displacement of the piezoelectric element 60b, and the nozzle N that ejects the ink in accordance with the change in volume of the pressure chamber CB1 and the change in volume of the pressure chamber CB2, wherein the selection circuit 230 includes the single transfer gate 234a that switches whether to supply the drive signal ComA commonly to the piezoelectric element 60a and the piezoelectric element 60b as the drive voltage signal Vin in accordance with the selection signal Sa.
That is, the single nozzle N that ejects the ink in accordance with the volume change of the pressure chamber CB1 and the volume change of the pressure chamber CB2 is provided, wherein the volume of the pressure chamber CB1 changes due to the displacement of the piezoelectric element 60a, and the volume of the pressure chamber CB2 changes due to the displacement of the piezoelectric element 60b. On this occasion, the drive voltage signal Vin for driving the piezoelectric element 60a and the drive voltage signal Vin for driving the piezoelectric element 60b are output by the single transfer gate 234a. In other words, the same drive voltage signal Vin is branched and input as the drive voltage signal Vin for driving the piezoelectric element 60a and the drive voltage signal Vin for driving the piezoelectric element 60b. As a result, the possibility that a difference occurs between the signal waveform of the drive voltage signal Vin supplied to the piezoelectric element 60a and the signal waveform of the drive voltage signal Vin supplied to the piezoelectric element 60b is reduced. Therefore, the possibility that a difference occurs between the displacement amount of the piezoelectric element 60a and the displacement amount of the piezoelectric element 60b is reduced, and the possibility that a variation occurs between the amount of the ink supplied from the pressure chamber CB1 to the nozzle N and the amount of the ink supplied from the pressure chamber CB2 to the nozzle N is reduced. As a result, the ejection accuracy of the ink ejected from the nozzle N is improved.
Furthermore, in the liquid ejection apparatus 1 and the print head 21 according to the present embodiment, the displacement amount of the piezoelectric element 60a according to the drive voltage signal Vin and the displacement amount of the piezoelectric element 60b according to the drive voltage signal Vin are substantially equal to each other, the change amount of the volume of the pressure chamber CB1 due to the displacement of the piezoelectric element 60a and the change amount of the volume of the pressure chamber CB2 due to the displacement of the piezoelectric element 60b are substantially equal to each other, and the flow path length of the flow path communicating the pressure chamber CB1 and the nozzle N with each other and the flow path length of the flow path communicating the pressure chamber CB2 and the nozzle N with each other are substantially equal to each other. That is, the amount of the ink flowing from the pressure chamber CB1 toward the nozzle N due to the displacement of the piezoelectric element 60a and the amount of the ink flowing from the pressure chamber CB2 toward the nozzle N due to the displacement of the piezoelectric element 60b are substantially equal to each other, the speed in the flow path communicating the pressure chamber CB1 and the nozzle N with each other of the ink flowing from the pressure chamber CB1 toward the nozzle N due to the displacement of the piezoelectric element 60a and the speed in the flow path communicating the pressure chamber CB2 and the nozzle N with each other of the ink flowing from the pressure chamber CB2 toward the nozzle N due to the displacement of the piezoelectric element 60b are substantially equal to each other, and the direction of the ink that flows in the flow path communicating the pressure chamber CB1 and the nozzle N from the pressure chamber CB1 toward the nozzle N due to the displacement of the piezoelectric element 60a and the direction of the ink that flows in the flow path communicating the pressure chamber CB2 and the nozzle N from the pressure chamber CB2 toward the nozzle N due to the displacement of the piezoelectric element 60b are opposite to each other.
Thus, the ink flowing from the pressure chamber CB1 toward the nozzle N due to the displacement of the piezoelectric element 60a and the ink flowing from the pressure chamber CB2 toward the nozzle N due to the displacement of the piezoelectric element 60b merge at the −Z side of the nozzle N and flow toward the +Z side. As a result, in the print head 21, the possibility that the flow of the ink to be ejected from the nozzle N is hindered by the member constituting the flow path through which the ink flows is reduced, and the possibility that unintended convection is generated in the ink to be ejected from the nozzle N is reduced. Therefore, the ejection accuracy of the ink to be ejected from the nozzle N is further improved.
Further, the liquid ejection apparatus 1 and the ejection unit 5 according to the present embodiment include the drive circuit 50 for outputting the drive signal ComB as the drive signal COM, the pressure chamber CB1 the volume of which varies in accordance with the drive signal ComB, the pressure chamber CB2 the volume of which varies in accordance with the drive signal ComB, the nozzle N that communicates with the pressure chamber CB1 and the pressure chamber CB2 to eject the ink, the piezoelectric element 60a for outputting the residual vibration signal Vout1 according to the residual vibration generated in accordance with the volume change of the pressure chamber CB1, the piezoelectric element 60b for outputting the residual vibration signal Vout2 according to the residual vibration generated in accordance with the volume change of the pressure chamber CB2, the waveform shaping circuit 240 to which the residual vibration signal Vout1 and the residual vibration signal Vout2 are input, and which outputs the residual vibration signal NVT, the AD conversion circuit 300 to which the residual vibration signal NVT is input, and which outputs the residual vibration signal dNVT, the control circuit 100 for determining the ejection state of the liquid from the nozzle N based on the residual vibration signal dNVT, and the transfer gate 234c for switching whether to output the residual vibration signal Vout1 and the residual vibration signal Vout2 to the waveform shaping circuit 240, wherein the piezoelectric element 60a and the piezoelectric element 60b are electrically coupled at the node 315, and the transfer gate 234c switches the conduction state between the node 315 and the waveform shaping circuit 240.
That is, the residual vibration signal Vout, which is a composite wave of the residual vibration signal Vout1 and the residual vibration signal Vout2, is input to the waveform shaping circuit 240, and the control circuit 100 determines the state of the print head 21, that is the ejection state of the ink from the nozzle N, based on the residual vibration signal dNVT corresponding to the residual vibration signal Vout, which is the composite wave of the residual vibration signal Vout1 and the residual vibration signal Vout2. As a result, it is possible to accurately determine the ejection state of the ink from the nozzle N even in the configuration in which the ink is ejected from a single nozzle N in accordance with the volume change of the pressure chamber CB1 due to the drive of the piezoelectric element 60a and the volume change of the pressure chamber CB2 due to the drive of the piezoelectric element 60b. Further, on this occasion, by the control circuit 100 determining the ejection state of ink from the nozzle N based on the residual vibration signal Vout, which is the composite wave of the residual vibration signal Vout1 and the residual vibration signal Vout2, it is unnecessary to increase the number of the transfer gates 234c provided to the ejection unit 5 and the print head 21 when determining the ejection state of the ink from the nozzle N, and the possibility that the print head 21 and the ejection unit 5 grow in size is also reduced.
Further, in the liquid ejection apparatus 1, the ejection unit 5, and the print head 21 according to the present embodiment, the state determination of the print head 21 having the pressure chamber CB1 the volume of which changes in accordance with the drive signal ComB as the drive signal COM, the pressure chamber CB2 the volume of which changes in accordance with the drive signal ComB as the drive signal COM, the nozzle N that communicates with the pressure chamber CB1 and the pressure chamber CB2, and that ejects the liquid, the piezoelectric element 60a that outputs the residual vibration signal Vout1 according to the residual vibration generated in accordance with the volume change of the pressure chamber CB1, and the piezoelectric element 60b that outputs the residual vibration signal Vout2 according to the residual vibration generated in accordance with the volume change of the pressure chamber CB2 is achieved by the method including the residual vibration generation step (step S1) of changing the volumes of the pressure chamber CB1 and the pressure chamber CB2 to thereby generate the residual vibration in the pressure chamber CB1 and generate the residual vibration in the pressure chamber CB2, the signal conversion step (step S2) of converting the residual vibration signal NVT corresponding to the residual vibration signal Vout obtained by combining the signal waveform of the residual vibration signal Vout1 and the signal waveform of the residual vibration signal Vout2 with each other into the residual vibration signal dNVT as a digital signal, and the determination step (step S3) of determining the state of the print head 21, that is the ejection state of the ink from the nozzle N based on the residual vibration signal dNVT.
That is, in the liquid ejection apparatus 1, the ejection unit 5, and the print head 21 according to the present embodiment, the state of the print head 21, that is the ejection state of the ink from the nozzle N, is determined based on the residual vibration signal dNVT as the digital value of the residual vibration signal Vout, which is the composite wave of the residual vibration signal Vout1 and the residual vibration signal Vout2. Thus, even in the configuration in which the ink is ejected from a single nozzle N in accordance with the volume change of the pressure chamber CB1 due to the drive of the piezoelectric element 60a and the volume change of the pressure chamber CB2 due to the drive of the piezoelectric element 60b, it is possible to accurately obtain the details of the signal waveform of the residual vibration signal Vout which is the composite wave of the residual vibration signal Vout1 and the residual vibration signal Vout2, and as a result, it is possible to accurately determine the ejection state of the ink from the nozzle N.
Although the embodiment and the modified examples are described hereinabove, the present disclosure is not limited to the embodiment and can be implemented in various aspects without departing from the gist thereof. For example, the embodiments described above can appropriately be combined.
The present disclosure includes substantially the same configurations (e.g., configurations having the same functions, methods, and results, and configurations having the same purposes and advantages) as the configurations described in the embodiment. Further, the present disclosure includes configurations obtained by replacing non-essential portions of the configurations described in the embodiment. Furthermore, the present disclosure includes configurations that may exert the same functions and advantages or configurations that may achieve the same objects as those of the configurations described in the embodiment. Further, the present disclosure includes configurations obtained by adding a known technique to the configurations described in the embodiment.
The following configurations are derived from the embodiment described above.
One aspect of the liquid ejection apparatus includes
a drive circuit configured to output a drive signal,
a first switching circuit to which the drive signal is input, and which is configured to switch whether to output a first drive voltage according to the drive signal,
a first piezoelectric element which is displaced in accordance with the first drive voltage,
a first pressure chamber a volume of which varies with a displacement of the first piezoelectric element,
a second piezoelectric element which is displaced in accordance with the first drive voltage,
a second pressure chamber a volume of which varies with a displacement of the second piezoelectric element, and
a first nozzle configured to eject a liquid in accordance with a change in volume of the first pressure chamber and a change in volume of the second pressure chamber, wherein
the first switching circuit includes a single first switch element configured to switch whether to set the drive signal to the first drive voltage and supply the drive signal commonly to the first piezoelectric element and the second piezoelectric element in accordance with a first ejection control signal.
According to this liquid ejection apparatus, by driving the first piezoelectric element and the second piezoelectric element with the first drive voltage output by the first switch element that is common to the first piezoelectric element and the second piezoelectric element, a possibility that a difference occurs between the vibration waveform of the first drive voltage supplied to the first piezoelectric element and the signal waveform of the first drive voltage supplied to the second piezoelectric element is reduced. As a result, the possibility that a difference occurs between the change in the volume of the first pressure chamber and the change in the volume of the second pressure chamber is reduced, and the ejection accuracy of the liquid from the first nozzle for ejecting the liquid in accordance with the change in the volume of the first pressure chamber and the change in the volume of the second pressure chamber is improved.
In one aspect of the liquid ejection apparatus described above,
a displacement amount of the first piezoelectric element according to the first drive voltage and a displacement amount of the second piezoelectric element according to the first drive voltage may substantially be equal to each other,
a change amount of the volume of the first pressure chamber with the displacement of the first piezoelectric element and a change amount of the volume of the second pressure chamber with the displacement of the second piezoelectric element may substantially be equal to each other, and
a flow path length of a first flow path configured to communicate the first pressure chamber and the first nozzle with each other and a flow path length of a second flow path configured to communicate the second pressure chamber and the first nozzle with each other may substantially be equal to each other.
According to this liquid ejection apparatus, since the displacement amount of the first piezoelectric element according to the first drive voltage and the displacement amount of the second piezoelectric element according to the first drive voltage are substantially equal to each other, the change amount of the volume of the first pressure chamber with the displacement of the first piezoelectric element and the change amount of the volume of the second pressure chamber with the displacement of the second piezoelectric element are substantially equal to each other, and the flow path length of the first flow path communicating the first pressure chamber and the first nozzle with each other and the flow path length of the second flow path communicating the second pressure chamber and the first nozzle with each other are substantially equal to each other, the liquid flowing from the first pressure chamber toward the nozzle N and the liquid flowing from the second pressure chamber toward the nozzle N merge in the vicinity of the nozzle N. As a result, a possibility that unintentional convection occurs in the liquid to be ejected from the nozzle N is reduced, and the ejection accuracy of the ink to be ejected from the nozzle N is improved.
In one aspect of the liquid ejection apparatus described above,
an amount of the liquid flowing from the first pressure chamber toward the first nozzle due to the displacement of the first piezoelectric element and an amount of the liquid flowing from the second pressure chamber toward the first nozzle due to the displacement of the second piezoelectric element may substantially be equal to each other,
a velocity of the liquid flowing through the first flow path configured to communicate the first pressure chamber and the first nozzle with each other from the first pressure chamber toward the first nozzle due to the displacement of the first piezoelectric element and a velocity of the liquid flowing through the second flow path configured to communicate the second pressure chamber and the first nozzle with each other from the second pressure chamber toward the first nozzle due to the displacement of the second piezoelectric element may substantially be equal to each other, and
a direction in which the liquid flowing from the first pressure chamber toward the first nozzle flows through the first flow path due to the displacement of the first piezoelectric element and a direction in which the liquid flowing from the second pressure chamber toward the first nozzle flows through the second flow path due to the displacement of the second piezoelectric element may be opposite to each other.
According to this liquid ejection apparatus, the liquid flowing from the first pressure chamber toward the nozzle N and the liquid flowing from the second pressure chamber toward the nozzle N flow in respective directions opposite to each other at substantially the same speed, and then merge with each other in the vicinity of the nozzle N. As a result, the possibility that unintentional convection occurs in the liquid to be ejected from the nozzle N is reduced, and the ejection accuracy of the ink to be ejected from the nozzle N is improved.
In one aspect of the liquid ejection apparatus described above,
the first piezoelectric element and the second piezoelectric element may electrically be coupled at a node,
the drive signal may be input to one end of the first switch element, another end of the first switch element may electrically be coupled to the node, and the first switch element may be configured to switch whether to supply the drive signal commonly to the first piezoelectric element and the second piezoelectric element in accordance with a switch control signal input to a control terminal, and
a resistance value between the other end of the first switch element and the first piezoelectric element may substantially be equal to a resistance value between the other end of the first switch element and the second piezoelectric element.
According to this liquid ejection apparatus, the possibility that a difference occurs between the signal waveform of the first drive voltage supplied to the first piezoelectric element and the signal waveform of the first drive voltage supplied to the second piezoelectric element is further reduced. Therefore, the difference between the displacement amount of the first piezoelectric element and the displacement amount of the second piezoelectric element is further reduced, and the ink ejection accuracy from the nozzle N is further improved.
In one aspect of the liquid ejection apparatus described above, there may further be provided
a supply port and a discharge port, wherein
the liquid supplied from the supply port may be discharged from the discharge port via the first pressure chamber and the second pressure chamber, and
at least a part of the liquid discharged from the discharge port may be returned to the supply port.
According to this liquid ejection apparatus, a possibility that a characteristic of the liquid changes due to the retention of the liquid in the first pressure chamber and the second pressure chamber is reduced.
In one aspect of the liquid ejection apparatus described above, there may further be provided
a second switching circuit to which the drive signal is input, and which is configured to switch whether to output a second drive voltage according to the drive signal,
a third piezoelectric element which is displaced in accordance with the second drive voltage,
a third pressure chamber a volume of which varies with a displacement of the third piezoelectric element,
a fourth piezoelectric element which is displaced in accordance with the second drive voltage,
a fourth pressure chamber a volume of which varies with a displacement of the fourth piezoelectric element, and
a second nozzle configured to eject a liquid in accordance with a change in volume of the third pressure chamber and a change in volume of the fourth pressure chamber, wherein
the second switching circuit may include a single second switch element configured to switch whether to set the drive signal to the second drive voltage and supply the drive signal commonly to the third piezoelectric element and the fourth piezoelectric element in accordance with a second ejection control signal,
a plurality of the switch elements including the first switch element and the second switch element may be provided to a single integrated circuit,
the integrated circuit may include a pair of long sides located to be opposed to each other, and a pair of short sides which are shorter than the long sides, and are located to be opposed to each other, and
a length of the long sides of the integrated circuit may be shorter than a length of a nozzle column in which a plurality of nozzles including the first nozzle and the second nozzle is arranged side by side to form a column.
One aspect of the print head may include
a first switching circuit to which the drive signal is input, and which is configured to switch whether to output a first drive voltage according to the drive signal,
a first piezoelectric element which is displaced in accordance with the first drive voltage,
a first pressure chamber a volume of which varies with a displacement of the first piezoelectric element,
a second piezoelectric element which is displaced in accordance with the first drive voltage,
a second pressure chamber a volume of which varies with a displacement of the second piezoelectric element, and
a first nozzle configured to eject a liquid in accordance with a change in volume of the first pressure chamber and a change in volume of the second pressure chamber, wherein
the first switching circuit may include a single first switch element configured to switch whether to set the drive signal to the first drive voltage and supply the drive signal commonly to the first piezoelectric element and the second piezoelectric element in accordance with a first ejection control signal.
According to this print head, by driving the first piezoelectric element and the second piezoelectric element with the first drive voltage output by the first switch element that is common to the first piezoelectric element and the second piezoelectric element, a possibility that a difference occurs between the vibration waveform of the first drive voltage supplied to the first piezoelectric element and the signal waveform of the first drive voltage supplied to the second piezoelectric element is reduced. As a result, the possibility that a difference occurs between the change in the volume of the first pressure chamber and the change in the volume of the second pressure chamber is reduced, and the ejection accuracy of the liquid from the first nozzle for ejecting the liquid in accordance with the change in the volume of the first pressure chamber and the change in the volume of the second pressure chamber is improved.
In one aspect of the print head described above,
a displacement amount of the first piezoelectric element according to the first drive voltage and a displacement amount of the second piezoelectric element according to the first drive voltage may substantially be equal to each other,
a change amount of the volume of the first pressure chamber with the displacement of the first piezoelectric element and a change amount of the volume of the second pressure chamber with the displacement of the second piezoelectric element may substantially be equal to each other, and
a flow path length of a first flow path configured to communicate the first pressure chamber and the first nozzle with each other and a flow path length of a second flow path configured to communicate the second pressure chamber and the first nozzle with each other may substantially be equal to each other.
According to this print head, since the displacement amount of the first piezoelectric element according to the first drive voltage and the displacement amount of the second piezoelectric element according to the first drive voltage are substantially equal to each other, the change amount of the volume of the first pressure chamber with the displacement of the first piezoelectric element and the change amount of the volume of the second pressure chamber with the displacement of the second piezoelectric element are substantially equal to each other, and the flow path length of the first flow path communicating the first pressure chamber and the first nozzle with each other and the flow path length of the second flow path communicating the second pressure chamber and the first nozzle with each other are substantially equal to each other, the liquid flowing from the first pressure chamber toward the nozzle N and the liquid flowing from the second pressure chamber toward the nozzle N merge in the vicinity of the nozzle N. As a result, the possibility that unintentional convection occurs in the liquid to be ejected from the nozzle N is reduced, and the ejection accuracy of the ink to be ejected from the nozzle N is improved.
In one aspect of the print head described above,
an amount of the liquid flowing from the first pressure chamber toward the first nozzle due to the displacement of the first piezoelectric element and an amount of the liquid flowing from the second pressure chamber toward the first nozzle due to the displacement of the second piezoelectric element may substantially be equal to each other,
a velocity of the liquid flowing through the first flow path configured to communicate the first pressure chamber and the first nozzle with each other from the first pressure chamber toward the first nozzle due to the displacement of the first piezoelectric element and a velocity of the liquid flowing through the second flow path configured to communicate the second pressure chamber and the first nozzle with each other from the second pressure chamber toward the first nozzle due to the displacement of the second piezoelectric element may substantially be equal to each other, and
a direction in which the liquid flowing from the first pressure chamber toward the first nozzle flows through the first flow path due to the displacement of the first piezoelectric element and a direction in which the liquid flowing from the second pressure chamber toward the first nozzle flows through the second flow path due to the displacement of the second piezoelectric element may be opposite to each other.
According to this print head, the liquid flowing from the first pressure chamber toward the nozzle N and the liquid flowing from the second pressure chamber toward the nozzle N flow in the respective directions opposite to each other at substantially the same speed and then merge with each other in the vicinity of the nozzle N. As a result, the possibility that unintentional convection occurs in the liquid to be ejected from the nozzle N is reduced, and the ejection accuracy of the ink to be ejected from the nozzle N is improved.
In one aspect of the print head described above,
the first piezoelectric element and the second piezoelectric element may electrically be coupled at a node,
the drive signal may be input to one end of the first switch element, another end of the first switch element may electrically be coupled to the node, and the first switch element may be configured to switch whether to supply the drive signal commonly to the first piezoelectric element and the second piezoelectric element in accordance with a switch control signal input to a control terminal, and
a resistance value between the other end of the first switch element and the first piezoelectric element may substantially be equal to a resistance value between the other end of the first switch element and the second piezoelectric element.
According to this print head, the possibility that a difference occurs between the signal waveform of the first drive voltage supplied to the first piezoelectric element and the signal waveform of the first drive voltage supplied to the second piezoelectric element is further reduced. Therefore, the difference between the displacement amount of the first piezoelectric element and the displacement amount of the second piezoelectric element is further reduced, and the ink ejection accuracy from the nozzle N is further improved.
In one aspect of the print head described above, there may further be provided
a supply port and a discharge port, wherein
the liquid supplied from the supply port may be discharged from the discharge port via the first pressure chamber and the second pressure chamber, and
at least a part of the liquid discharged from the discharge port may be returned to the supply port.
According to this print head, a possibility that a characteristic of the liquid changes due to the retention of the liquid in the first pressure chamber and the second pressure chamber is reduced.
In one aspect of the print head described above, there may further be provided
a second switching circuit to which the drive signal is input, and which is configured to switch whether to output a second drive voltage according to the drive signal,
a third piezoelectric element which is displaced in accordance with the second drive voltage,
a third pressure chamber a volume of which varies with a displacement of the third piezoelectric element,
a fourth piezoelectric element which is displaced in accordance with the second drive voltage,
a fourth pressure chamber a volume of which varies with a displacement of the fourth piezoelectric element, and
a second nozzle configured to eject a liquid in accordance with a change in volume of the third pressure chamber and a change in volume of the fourth pressure chamber, wherein
the second switching circuit may include a single second switch element configured to switch whether to set the drive signal to the second drive voltage and supply the drive signal commonly to the third piezoelectric element and the fourth piezoelectric element in accordance with a second ejection control signal,
a plurality of the switch elements including the first switch element and the second switch element may be provided to a single integrated circuit,
the integrated circuit may include a pair of long sides located to be opposed to each other, and a pair of short sides which are shorter than the long sides, and are located to be opposed to each other, and
a length of the long sides of the integrated circuit may be shorter than a length of a nozzle column in which a plurality of nozzles including the first nozzle and the second nozzle is arranged side by side to form a column.
According to this print head, since the influence of the integrated circuit on the size of the print head is reduced, it is possible to realize the reduction in size of the print head to the extent that the specification is satisfied.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-195243 | Nov 2023 | JP | national |
