Print head and liquid ejecting apparatus

Abstract

The invention provides a printing head and a liquid ejecting apparatus, which can improve the detection precision of residual vibration generated after a piezoelectric element is driven. A print head includes: a pressure chamber whose volume varies according to a drive signal; the nozzle is communicated with the pressure chamber and sprays liquid; a piezoelectric element that outputs a residual vibration signal corresponding to residual vibration generated by a change in volume of the pressure chamber; a residual vibration detection circuit to which the residual vibration signal is input and which outputs a residual vibration detection signal corresponding to the residual vibration signal; and a first switching circuit that switches whether to supply the residual vibration signal to the residual vibration detection circuit, the first switching circuit being an N-channel transistor.

Description

Technical Field

[0001] The present invention relates to a printing head and a liquid ejecting device. Background Art

[0002] In a liquid ejection device that ejects ink from an ejection portion by being driven by a piezoelectric element, as described in Patent Document 1, there is known a technology for detecting a signal corresponding to residual vibration generated after the piezoelectric element is driven and determining the state of the ejection portion based on the detection result of the signal.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-039856

[0006] However, from the perspective of improving the detection accuracy of residual vibration generated after the piezoelectric element is driven, the technology described in Patent Document 1 is insufficient and has room for further improvement. Summary of the Invention

[0007] One embodiment of a print head according to the present invention comprises:

[0008] pressure chamber, whose volume changes according to the driving signal;

[0009] a nozzle, connected to the pressure chamber and configured to spray liquid;

[0010] a piezoelectric element that outputs a residual vibration signal corresponding to residual vibration generated by a volume change of the pressure chamber;

[0011] a residual vibration detection circuit that receives the residual vibration signal and outputs a residual vibration detection signal corresponding to the residual vibration signal; and

[0012] a first switch circuit for switching whether to supply the residual vibration signal to the residual vibration detection circuit;

[0013] The first switch circuit is an N-channel transistor.

[0014] One embodiment of the liquid ejection device according to the present invention comprises:

[0015] A driving circuit outputting a driving signal;

[0016] a pressure chamber, the volume of which changes according to the driving signal;

[0017] a nozzle, connected to the pressure chamber and configured to spray liquid;

[0018] a piezoelectric element that outputs a residual vibration signal corresponding to residual vibration generated by a volume change of the pressure chamber;

[0019] a residual vibration detection circuit which receives the residual vibration signal and outputs a residual vibration detection signal corresponding to the residual vibration signal;

[0020] a first switch circuit for switching whether to supply the residual vibration signal to the residual vibration detection circuit; and

[0021] a processor that determines a discharge state of liquid discharged from the nozzle based on the residual vibration detection signal,

[0022] The first switch circuit is an N-channel transistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a diagram showing a schematic configuration of a liquid ejecting device.

[0024] Figure 2 It is a diagram showing a schematic configuration of a discharge unit.

[0025] Figure 3 This is a diagram for explaining the schematic configuration of the ejection unit.

[0026] Figure 4 : is a diagram showing an example of the signal waveform of the driving voltage signal COM.

[0027] Figure 5 This is a diagram showing an example of the functional configuration of a drive signal selection circuit.

[0028] Figure 6 This is a diagram showing an example of the decoded content in the decoder.

[0029] Figure 7 1 is a diagram showing an example of a circuit configuration of a selection circuit, a switching circuit, and a residual vibration detection circuit included in a drive signal selection circuit.

[0030] Figure 8 This is a diagram showing an example of the operation of the drive signal selection circuit.

[0031] Figure 9 This is a diagram showing an example of the structure of an integrated circuit.

[0032] Figure 10 1 is a diagram showing an example of the structure of a mounting area Sel where a selection circuit is mounted.

[0033] Figure 11 1 is a diagram showing an example of the configuration of a mounting region Sw where a switching circuit is mounted.

[0034] Figure 123 is a diagram showing an example of the residual vibration signal Vout.

[0035] Figure 13 This is a diagram showing an example of a calculation model of a single vibration assuming residual vibration occurring in the pressure chamber or the vibration plate.

[0036] Figure 14 This is a diagram for explaining the relationship between the viscosity of ink and the signal waveform of the residual vibration signal Vout.

[0037] Figure 15 This is a diagram for explaining the signal waveform of the residual vibration signal Vout when air bubbles are mixed into the pressure chamber.

[0038] Figure 16 This is a diagram showing an example of the circuit configuration of a selection circuit, a switching circuit, and a residual vibration detection circuit included in the drive signal selection circuit of the second embodiment.

[0039] Figure 17 This is a diagram showing an example of the configuration of a mounting region Sel on which a selection circuit is mounted according to the second embodiment.

[0040] Figure 18 This is a diagram showing an example of the configuration of a mounting region Sw on which a switching circuit is mounted according to the second embodiment.

[0041] Figure 19 This is a diagram showing an example of the structure of an integrated circuit according to the second embodiment.

[0042] Description of Reference Numerals

[0043] 1: Liquid ejection device; 2: Control unit; 3: Liquid container; 4: Transport unit; 5: Ejection unit; 10: Drive module; 11: Control circuit substrate; 15: Cable; 20: Ejection module; 21: Print head; 22: Head chip; 23: Head circuit substrate; 24: Flexible substrate; 41: Transport motor; 42: Transport roller; 50: Drive circuit; 60: Piezoelectric element; 100: Control circuit; 110: Power supply circuit; 200: Drive signal selection circuit; 220: Selection control circuit; 222: Register; 224: Latch circuit; 226: Decoder; 230: Selection Circuit; 232a, 232b, 232c: Logic inversion circuit; 234a, 234b, 234c: Switch circuit; 236a, 236b, 236c: N-type transistors; 238a, 238b, 238c: P-type transistors; 240: Switch circuit; 242: Switch circuit; 242a: N-type transistor; 242b: P-type transistor; 243: Logic inversion circuit; 244: Logical OR circuit; 250: Residual vibration detection circuit; 270: Waveform information output circuit; 300: Integrated circuit; 310: Substrate; 311, 312: Short side; 313 314: long side; 331, 332, 333: N-type diffusion layer; 334, 335: electrode; 341, 342, 343: N-type diffusion layer; 344, 345: electrode; 351, 352, 353: P-type diffusion layer; 354, 355: electrode; 361, 362, 363: N-type diffusion layer; 364, 365: electrode; 371, 372, 373: P-type diffusion layer; 374, 375: electrode; 381, 382, ​​383: P-type diffusion layer; 384, 385: electrode; 600: ejection part; 601: piezoelectric body; 611, 61 2: electrode; 621: vibration plate; 631: pressure chamber; 632: nozzle plate; 641: reservoir; 651: nozzle; 661: supply port; C: compliance; C1, C2: capacitors; OP1: amplifier circuit; P: dielectric; PW1: power supply circuit; R1~R7: resistors; Tca, Tcb, Tch, Tck, Tlt, Tnv, Tsg, Tsi, Tvh, Tvi: terminals; Wbc, Wca, Wcb, Wch, Wck, Wlt, Wnv, Wsa, Wsb, Wsc, Wsg, Wsi, Wss, Wvh, Wvo: wiring. DETAILED DESCRIPTION

[0044] The following drawings illustrate preferred embodiments of the present invention. The drawings are provided for ease of description. It should be noted that the embodiments described below do not unduly limit the scope of the present invention as set forth in the claims. Furthermore, not all of the components described below are essential components of the present invention.

[0045] 1. First Implementation

[0046] 1.1 Composition of liquid ejection device

[0047] Figure 1 1 is a diagram showing a schematic structure of the liquid ejecting device 1. Figure 1 As shown, the liquid ejection device 1 is a so-called line inkjet printer that forms a desired image on the medium P transported by the transport unit 4 by ejecting ink, an example of a liquid, at a desired timing. It should be noted that the liquid ejection device 1 is not limited to a line inkjet printer and may also be a serial inkjet printer. Furthermore, the liquid ejection device 1 is not limited to an inkjet printer and may be a colorant ejection device used to manufacture color filters for liquid crystal displays, electrode material ejection devices used to form electrodes for organic EL displays, FEDs (surface emitting displays), etc., living organic material ejection devices used to manufacture biochips, 3D modeling devices, printing and dyeing devices, etc. In the following description, the direction in which the medium P is transported is sometimes referred to as the transport direction, and the width direction of the transported medium P is sometimes referred to as the scanning direction.

[0048] like Figure 1 As shown, the liquid ejecting device 1 includes a control unit 2 , a liquid container 3 , a transport unit 4 , and a plurality of ejecting units 5 .

[0049] The control unit 2 includes processing circuits such as a CPU (Central Processing Unit) and an FPGA (Field Programmable Gate Array), and storage circuits such as semiconductor memory. The control unit 2 outputs signals for controlling various elements of the liquid ejection device 1 based on image data supplied from an external device such as a host computer (not shown) located outside the liquid ejection device 1.

[0050] The liquid container 3 stores ink, an example of liquid, which is supplied to the ejection unit 5. Specifically, the liquid container 3 stores inks of various colors, such as black, cyan, magenta, yellow, red, and gray, which are ejected onto the medium P. Examples of the liquid container 3 include ink cartridges, bag-shaped ink bags formed of flexible films, and refillable ink tanks.

[0051] The conveying unit 4 includes a conveying motor 41 and conveying rollers 42. The conveying control signal Ctrl-T output by the control unit 2 is input to the conveying unit 4. The conveying motor 41 is driven based on the conveying control signal Ctrl-T, and the conveying rollers 42 rotate in response to the drive of the conveying motor 41. The rotation of the conveying rollers 42 conveys the medium P in the conveying direction.

[0052] Each of the multiple ejection units 5 includes a driver module 10 and an ejection module 20. Ink stored in the liquid container 3 is supplied to each of the multiple ejection units 5 while corresponding image information signals IP output by the control unit 2 are input. The driver module 10 controls the operation of the ejection module 20 based on the image information signals IP. Consequently, the ejection module 20 ejects the ink supplied from the liquid container 3 at a predetermined timing in accordance with the control of the driver module 10.

[0053] In the liquid ejection device 1 of this embodiment, the ejection modules 20 included in each of the plurality of ejection units 5 are positioned so as to extend along the scanning direction, extending beyond the width of the medium P. The drive modules 10 included in each of the plurality of ejection units 5 cause ink to be ejected from the ejection modules 20 at a timing synchronized with the transport of the medium P. The ink ejected from each of the plurality of ejection modules 20 lands at a desired location on the medium P, thereby forming a desired image on the medium P.

[0054] Next, the schematic configuration of the discharge unit 5 will be described. Figure 2 : is a diagram showing a schematic structure of the ejection unit 5. Figure 2 As shown, the discharge unit 5 includes a drive module 10 and a discharge module 20. In the discharge unit 5, the drive module 10 and the discharge module 20 are electrically connected via a cable 15. A flexible flat cable (FFC) or a flexible printed circuit (FPC) can be used as the cable 15 for electrically connecting the drive module 10 and the discharge module 20. Alternatively, the drive module 10 and the discharge module 20 can be electrically connected using a BtoB (Board to Board) connector instead of the cable 15, or they can be electrically connected using both the cable 15 and the BtoB connector.

[0055] The driving module 10 includes a control circuit substrate 11 , a driving circuit 50 , a control circuit 100 , and a power supply circuit 110 .

[0056] The power supply circuit 110 converts the commercial voltage signal input to the liquid ejection device 1 into a DC voltage signal of a certain voltage value, for example, a DC voltage signal of 42V, and outputs the converted DC voltage signal as a voltage signal VHV. The voltage signal VHV output by the power supply circuit 110 is input to the drive circuit 50 and also to the ejection module 20. As such a power supply circuit 110, a switching regulator that can efficiently convert a commercial voltage signal into a DC voltage signal, such as a flyback circuit, can be used. It should be noted that the DC voltage signal including the voltage signal VHV output by the power supply circuit 110 can also be input to various components of the liquid ejection device 1 in addition to the drive circuit 50 and the ejection module 20. In addition, the voltage value of the voltage signal VHV output by the power supply circuit 110 is not limited to 42V. In addition to the voltage signal VHV, the power supply circuit 110 can also output DC voltage signals of multiple voltage values ​​used in the liquid ejection device 1.

[0057] The control circuit board 11 is a printed circuit board having one or more wiring layers, and a glass epoxy board, a glass polyimide board, or the like can be used. The various components that make up the driver module 10, including the driver circuit 50, the control circuit 100, and the power supply circuit 110, are mounted on the control circuit board 11. It should be noted that the control circuit board 11, on which the various components that make up the driver module 10 are mounted, can consist of either a single printed circuit board or multiple printed circuit boards.

[0058] The control circuit 100 includes a CPU (a processor), a processing circuit such as an FPGA, and a storage circuit such as a semiconductor memory. The image information signal IP output by the control unit 2 is input to the control circuit 100. Based on the input image information signal IP, the control circuit 100 generates and outputs signals for controlling the operation of the drive module 10 and the ejection module 20.

[0059] Specifically, the control circuit 100 generates a clock signal SCK, a latch signal LAT, a change signal CH, a check timing signal TSIG, and print data signals SI1 to SIn based on the input image information signal IP, and outputs the signals to the ejection module 20 .

[0060] In addition, the control circuit 100 generates a basic drive signal dA and outputs it to the drive circuit 50. The drive circuit 50 generates a drive voltage signal COM including a signal waveform specified by the input basic drive signal dA, and outputs it to the ejection module 20. Specifically, the control circuit 100 generates a basic drive signal dA of a digital signal and outputs it to the drive circuit 50. After converting the basic drive signal dA of the input digital signal into an analog signal, the drive circuit 50 performs a D-class amplification on the converted analog signal based on the voltage signal VHV, thereby generating a drive voltage signal COM. The drive circuit 50 outputs the generated drive voltage signal COM to the ejection module 20. That is, the control circuit 100 outputs the basic drive signal dA that specifies the signal waveform of the drive voltage signal COM output by the drive circuit 50. It should be noted that the basic drive signal dA can be any signal that can specify the signal waveform of the drive voltage signal COM, and can also be an analog signal. In addition, the driving circuit 50 only needs to be able to generate the driving voltage signal COM by amplifying the signal waveform specified by the basic driving signal dA based on the voltage signal VHV. It can also generate the driving voltage signal COM by replacing the D-class amplification or performing class A amplification, class B amplification or class AB amplification on the basis of the D-class amplification.

[0061] In addition, the driving circuit 50 generates a reference voltage signal VBS and outputs it to the ejection module 20. The reference voltage signal VBS is a signal with a constant voltage value and is used to determine the reference potential for driving the piezoelectric element 60 described later. The voltage value of such a reference voltage signal VBS can be, for example, the ground potential, or 5.5V, 6V, etc. It should be noted that in Figure 2 In the figure, the driving circuit 50 is shown to generate the reference voltage signal VBS and output it to the discharge module 20, but the reference voltage signal VBS may be generated by a constant voltage output circuit (not shown) configured separately from the driving circuit 50.

[0062] Furthermore, waveform information signals WFS1 to WFSn are input to the control circuit 100 from the discharge module 20 (described later). Based on the input waveform information signals WFS1 to WFSn, the control circuit 100 determines whether the ink discharge state from the discharge module 20 is normal. Details of the waveform information signals WFS1 to WFSn input to the control circuit 100 and a method for determining whether the ink discharge state from the discharge module 20 is normal based on the waveform information signals WFS1 to WFSn will be described later.

[0063] The ejection module 20 includes print heads 21-1 to 21-n, a head circuit board 23, and waveform information output circuits 270-1 to 270-n. Each of the print heads 21-1 to 21-n includes a head chip 22, a flexible board 24, and a drive signal selection circuit 200. Furthermore, each of the head chips 22 in the print heads 21-1 to 21-n includes an ejection unit 600-1 to 600-m, and each of the ejection units 600-1 to 600-m includes a piezoelectric element 60.

[0064] The ejection module 20 receives the clock signal SCK, latch signal LAT, change signal CH, inspection timing signal TSIG, print data signals SI1 to SIn, drive voltage signal COM, reference voltage signal VBS, and voltage signal VHV outputted from the drive module 10 .

[0065] The head circuit board 23 transmits the input clock signal SCK, latch signal LAT, change signal CH, inspection timing signal TSIG, print data signals SI1 to SIn, drive voltage signal COM, reference voltage signal VBS, and voltage signal VHV to the corresponding print heads 21-1 to 21-n. The head circuit board 23 is a print substrate having one or more wiring layers, and can be, for example, a glass epoxy substrate or a glass polyimide substrate.

[0066] Specifically, the head circuit substrate 23 transmits the clock signal SCK, latch signal LAT, replacement signal CH, check timing signal TSIG, printing data signal SI1~SIn, drive voltage signal COM, reference voltage signal VBS and voltage signal VHV among the input clock signal SCK, latch signal LAT, replacement signal CH, check timing signal TSIG, printing data signal SI1~SIn, drive voltage signal COM, reference voltage signal VBS and voltage signal VHV to the print head 21-1, and transmits the clock signal SCK, latch signal LAT, replacement signal CH, check timing signal TSIG, printing data signal SIn, drive voltage signal COM, reference voltage signal VBS and voltage signal VHV among them to the print head 21-n.

[0067] The clock signal SCK, latch signal LAT, change signal CH, inspection timing signal TSIG, print data signal SI1, drive voltage signal COM, reference voltage signal VBS, and voltage signal VHV input to the print head 21-1 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 included in the drive voltage signal COM based on the input clock signal SCK, latch signal LAT, change signal CH, inspection timing signal TSIG, and print data signal SI1, thereby generating and outputting drive voltage signals Vin-1 to Vin-m.

[0068] The drive voltage signals Vin-1 to Vin-m output by the drive signal selection circuit 200 of the print head 21-1 are supplied to the corresponding ejection units 600-1 to 600-m included in the head chip 22 of the print head 21-1. Specifically, the drive voltage signal Vin-1 among the drive voltage signals Vin-1 to Vin-m output by the drive signal selection circuit 200 of the print head 21-1 is supplied to one end of the piezoelectric element 60 included in the ejection unit 600-1 included in the head chip 22 of the print head 21-1, while the drive voltage signal Vin-m is supplied to one end of the piezoelectric element 60 included in the ejection unit 600-1 included in the head chip 22 of the print head 21-1. At this time, the other end of the piezoelectric element 60 included in each of the ejection units 600-1 to 600-m included in the head chip 22 of the print head 21-1 is commonly supplied with the reference voltage signal VBS. The piezoelectric elements 60 included in each of the ejection units 600-1 to 600-m of the head chip 22 of the print head 21-1 are driven based on the potential difference between the voltage values ​​of the corresponding drive voltage signals Vin-1 to Vin-m supplied to one end and the voltage value of the reference voltage signal VBS supplied to the other end. Ink is ejected from the ejection units 600-1 to 600-m of the print head 21-1 in an amount corresponding to the driving of the piezoelectric elements 60.

[0069] Furthermore, after the piezoelectric elements 60 included in the ejection sections 600-1 to 600-m of the head chip 22 of the print head 21-1 are driven, residual vibrations are generated. The piezoelectric elements 60 included in each of the ejection sections 600-1 to 600-m of the head chip 22 of the print head 21-1 are displaced according to the residual vibrations generated in the corresponding ejection sections 600-1 to 600-m. The piezoelectric elements 60 included in each of the ejection sections 600-1 to 600-m of the print head 21-1 output residual vibration signals Vout-1 to Vout-m corresponding to the displacements. These residual vibration signals Vout-1 to Vout-m 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 then generates a residual vibration detection signal NVT corresponding to the input residual vibration signals Vout-1 to Vout-m and outputs it from the print head 21-1.

[0070] The drive signal selection circuit 200 included in the print head 21 - 1 may be configured as an integrated circuit device, and a COF (Chip On Film) may be mounted on the flexible substrate 24 included in the print head 21 - 1 .

[0071] Furthermore, among the clock signal SCK, latch signal LAT, change signal CH, inspection timing signal TSIG, print data signal SIn, drive voltage signal COM, reference voltage signal VBS, and voltage signal VHV input to the print head 21-n, the clock signal SCK, latch signal LAT, change signal CH, inspection timing signal TSIG, print data signal SIn, drive voltage signal COM, and voltage signal VHV are input to the drive signal selection circuit 200 of the print head 21-n. The drive signal selection circuit 200 of the print head 21-n selects or deselects a signal waveform included in the drive voltage signal COM based on the input clock signal SCK, latch signal LAT, change signal CH, inspection timing signal TSIG, and print data signal SIn, thereby generating and outputting drive voltage signals Vin-1 to Vin-m.

[0072] The drive voltage signals Vin-1 to Vin-m output by the drive signal selection circuit 200 of the print head 21-n are supplied to the corresponding ejection units 600-1 to 600-m included in the head chip 22 of the print head 21-n. Specifically, the drive voltage signal Vin-1 of the drive signal selection circuit 200 of the print head 21-n is supplied to one end of the piezoelectric element 60 included in the ejection unit 600-1 included in the head chip 22 of the print head 21-n, and the drive voltage signal Vin-m is supplied to one end of the piezoelectric element 60 included in the ejection unit 600-1 included in the head chip 22 of the print head 21-n. At this time, the reference voltage signal VBS is commonly supplied to the other end of the piezoelectric element 60 included in each of the ejection units 600-1 to 600-m included in the head chip 22 of the print head 21-n. Then, the piezoelectric elements 60 included in each of the ejection units 600-1 to 600-m of the head chip 22 of the print head 21-n are driven based on the potential difference between the voltage value of the corresponding driving voltage signals Vin-1 to Vin-m supplied to one end and the voltage value of the reference voltage signal VBS supplied to the other end. Ink is ejected from the ejection units 600-1 to 600-m of the print head 21-n in an amount corresponding to the driving of the piezoelectric elements 60.

[0073] Furthermore, after the piezoelectric elements 60 included in the ejection sections 600-1 to 600-m of the head chip 22 of the print head 21-n are driven, residual vibrations are generated. The piezoelectric elements 60 included in each of the ejection sections 600-1 to 600-m of the head chip 22 of the print head 21-n are displaced according to the residual vibrations generated in the corresponding ejection sections 600-1 to 600-m. The piezoelectric elements 60 included in each of the ejection sections 600-1 to 600-m of the print head 21-n output residual vibration signals Vout-1 to Vout-m corresponding to the displacements. These residual vibration signals Vout-1 to Vout-m are input to the drive signal selection circuit 200 of the print head 21-n. The drive signal selection circuit 200 of the print head 21-n then generates a residual vibration detection signal NVT corresponding to the input residual vibration signals Vout-1 to Vout-m and outputs it from the print head 21-n.

[0074] The drive signal selection circuit 200 included in the print head 21 - n may be configured as an integrated circuit device, and a COF may be mounted on the flexible substrate 24 included in the print head 21 - n.

[0075] The waveform information output circuits 270 - 1 to 270 - n are mounted on the head circuit board 23 .

[0076] The residual vibration detection signal NVT outputted by the print head 21-1 is inputted to the waveform information output circuit 270-1. The waveform information output circuit 270-1 acquires waveform information of the input residual vibration detection signal NVT and generates a waveform information signal WFS1 including the acquired waveform information.

[0077] Specifically, the waveform information output circuit 270-1 compares the voltage value of the input residual vibration detection signal NVT with a predetermined reference voltage value to obtain the period of the input residual vibration detection signal NVT as waveform information of the input residual vibration detection signal NVT. Furthermore, based on the obtained period of the input residual vibration detection signal NVT, the waveform information output circuit 270-1 infers and obtains the amplitude of the input residual vibration detection signal NVT as waveform information of the input residual vibration detection signal NVT. It should be noted that the waveform information output circuit 270-1 may also obtain the period and amplitude of the input residual vibration detection signal NVT as waveform information of the input residual vibration detection signal NVT by performing analog-to-digital conversion on the input residual vibration detection signal NVT. Alternatively, instead of or in addition to the period or amplitude of the residual vibration detection signal NVT, the waveform information output circuit 270-1 may obtain the attenuation rate of the frequency or amplitude as waveform information. Then, the waveform information output circuit 270 - 1 generates a waveform information signal WFS1 including the acquired waveform information, and outputs the waveform information signal to the control circuit 100 included in the driving module 10 .

[0078] Similarly, the residual vibration detection signal NVT output by the print head 21-n is input to the waveform information output circuit 270-n. The waveform information output circuit 270-n acquires waveform information of the input residual vibration detection signal NVT and generates a waveform information signal WFSn including the acquired waveform information.

[0079] Specifically, the waveform information output circuit 270-n compares the voltage value of the input residual vibration detection signal NVT with a predetermined reference voltage value to obtain the period of the input residual vibration detection signal NVT as waveform information of the input residual vibration detection signal NVT. Furthermore, based on the obtained period of the input residual vibration detection signal NVT, the waveform information output circuit 270-n obtains the amplitude of the input residual vibration detection signal NVT as waveform information of the input residual vibration detection signal NVT. It should be noted that the waveform information output circuit 270-n may also obtain the period and amplitude of the input residual vibration detection signal NVT as waveform information of the input residual vibration detection signal NVT by performing analog-to-digital conversion on the input residual vibration detection signal NVT. Alternatively, the waveform information output circuit 270-n may obtain the frequency and amplitude attenuation rate of the residual vibration detection signal NVT as waveform information. The waveform information output circuit 270-n then generates a waveform information signal WFSn including the obtained waveform information and outputs it to the control circuit 100 of the drive module 10.

[0080] The control circuit 100 determines whether the ink ejection state from each of the print heads 21 - 1 to 21 - n is normal based on the input waveform information signals WFS1 to WFSn.

[0081] Here, the waveform information output circuits 270-1 to 270-n may be constructed as a single integrated circuit device or may be constructed from discrete components. Furthermore, the waveform information output circuit 270-1 may be implemented together with the drive signal selection circuit 200 on an integrated circuit device that constitutes the drive signal selection circuit 200 included in the print head 21-1, and the waveform information output circuit 270-n may be implemented together with the drive signal selection circuit 200 on an integrated circuit device that constitutes the drive signal selection circuit 200 included in the print head 21-n.

[0082] As described above, in the liquid ejection device 1 of this embodiment, the ejection unit 5 includes the drive circuit 50 that outputs the drive voltage signal COM and the control circuit 100 that determines the ejection state of ink ejected from the print head 21 based on the residual vibration detection signal NVT.

[0083] Here, print heads 21-1 to 21-n all have the same configuration and, when distinction is not necessary, are sometimes simply referred to as print head 21. Furthermore, the print head 21 is described as receiving inputs of a clock signal SCK, a latch signal LAT, a change signal CH, a check timing signal TSIG, print data signals SI (SI1 to SIn), a drive voltage signal COM, a reference voltage signal VBS, and a voltage signal VHV, and outputting a residual vibration detection signal NVT. Furthermore, the residual vibration detection signal NVT output by the print head 21 is input to waveform information output circuits 270 (270-1 to 270-n). The waveform information output circuits 270 acquire waveform information of the input residual vibration detection signal NVT and, based on the acquired waveform information, generate waveform information signals WFS (WFS1 to WFSn) and output these to the control circuit 100 of the drive module 10.

[0084] The ejection units 600-1 to 600-m included in the print head 21 all have the same configuration and, unless otherwise specified, are simply referred to as ejection units 600. Specifically, the print head 21 is described as including m ejection units 600 as a plurality of ejection units 600. In this case, the ejection units 600 are supplied with a drive voltage signal Vin as drive voltage signals Vin-1 to Vin-m, and the ejection units 600 output a residual vibration signal Vout as residual vibration signals Vout-1 to Vout-m.

[0085] 1.2 Structure of the ejection part

[0086] Next, an example of the configuration of the ejection unit 600 included in the head chip 22 of the print head 21 will be described. Figure 3 600 is a diagram for explaining the schematic structure of the ejection portion 600. Figure 3 , in addition to the ejection portion 600 , a nozzle plate 632 , a reservoir 641 , and a supply port 661 are also shown.

[0087] like Figure 3As shown, the ejection portion 600 includes a piezoelectric element 60, a vibration plate 621, a pressure chamber 631, and a nozzle 651. Furthermore, the piezoelectric element 60 includes a piezoelectric body 601 and electrodes 611 and 612. The piezoelectric element 60 is configured such that the electrodes 611 and 612 are located between the piezoelectric body 601. Such a piezoelectric element 60 is driven in such a manner that its central portion is displaced in the vertical direction according to the potential difference between the voltage supplied to the electrode 611 and the voltage supplied to the electrode 612. For example, a driving voltage signal Vin based on the driving voltage signal COM is supplied to the electrode 611, and a reference voltage signal VBS is supplied to the electrode 612. Then, when the voltage value of the driving voltage signal Vin supplied to the electrode 611 changes, the potential difference between the driving voltage signal Vin supplied to the electrode 611 and the reference voltage signal VBS supplied to the electrode 612 changes. As a result, the piezoelectric element 60 is driven in such a manner that its central portion is displaced in the vertical direction. It should be noted that the driving voltage signal Vin based on the driving voltage signal COM may be supplied to the electrode 612 , and the reference voltage signal VBS may be supplied to the electrode 611 .

[0088] The vibration plate 621 is located at Figure 3 In other words, the piezoelectric element 60 is formed below the vibration plate 621. Figure 3 Such a vibration plate 621 is displaced in the vertical direction as the piezoelectric element 60 is driven in the vertical direction.

[0089] The pressure chamber 631 is located at the vibrating plate 621. Figure 3 . Ink is supplied to the pressure chamber 631 from the reservoir 641. Furthermore, the ink stored in the liquid container 3 is introduced into the reservoir 641 via the supply port 661. That is, the interior of the pressure chamber 631 is filled with the ink stored in the liquid container 3. The internal volume of the pressure chamber 631 expands or contracts as the vibrating plate 621 moves in the vertical direction. In other words, the pressure in the pressure chamber 631 changes as the vibrating plate 621 moves in the vertical direction. At this time, the vibrating plate 621 functions as a diaphragm that changes the internal volume of the pressure chamber 631.

[0090] The nozzle 651 is provided in the nozzle plate 632 and is an opening that communicates with the pressure chamber 631. When the internal volume of the pressure chamber 631 changes, the ink filled in the pressure chamber 631 is ejected from the nozzle 651 in accordance with the change in the internal volume.

[0091] In the ejection unit 600 constructed as described above, when the piezoelectric element 60 is driven to flex upward, the vibration plate 621 displaces upward. This expands the internal volume of the pressure chamber 631, causing ink stored in the reservoir 641 to be drawn into the pressure chamber 631. On the other hand, when the piezoelectric element 60 is driven to flex downward, the vibration plate 621 displaces downward. This reduces the internal volume of the pressure chamber 631, resulting in an amount of ink ejected from the nozzle 651 corresponding to the reduction in the internal volume of the pressure chamber 631.

[0092] Furthermore, when the piezoelectric element 60 is driven to bend downward, damped vibrations are generated in the pressure chamber 631. The damped vibrations generated in the pressure chamber 631 vibrate the vibration plate 621, and the piezoelectric element 60 also vibrates. The piezoelectric element 60 then vibrates in response to the vibrations of the vibration plate 621, thereby outputting a residual vibration signal Vout based on the charge generated in response to this vibration.

[0093] Specifically, the ejection unit 600 of the print head 21 of the liquid ejection device 1 of this embodiment includes a pressure chamber 631 whose volume changes in response to a drive voltage signal COM; a nozzle 651 that communicates with the pressure chamber 631 and ejects ink; and a piezoelectric element 60 that outputs a residual vibration signal Vout corresponding to the residual vibration generated by the volume change of the pressure chamber 631. At this time, the piezoelectric element 60 displaces in response to the drive voltage signal COM, and the volume of the pressure chamber 631 changes in response to the displacement of the piezoelectric element 60.

[0094] It should be noted that the piezoelectric element 60 is not limited to a structure that can be driven by supplying a driving voltage signal Vin corresponding to the driving voltage signal COM and can eject ink from the nozzle 651 by being driven. Figure 3 The structure shown.

[0095] 1.3 Configuration and Operation of the Drive Signal Selection Circuit

[0096] 1.3.1 Signal waveform of driving voltage signal COM

[0097] Next, the configuration and operation of the drive signal selection circuit 200, which generates and outputs corresponding drive voltage signals Vin to each of the plurality of ejection units 600 included in the print head 21 by selecting or not selecting the signal waveform included in the drive voltage signal COM, will be described. When describing the details of the drive signal selection circuit 200, an example of the signal waveform of the drive voltage signal COM input to the drive signal selection circuit 200 will be described. Figure 4 : is a diagram showing an example of a signal waveform of the driving voltage signal COM. Figure 4 As shown, the driving voltage signal COM includes a driving voltage signal ComA and a driving voltage signal ComB.

[0098] The driving voltage signal ComA includes a signal waveform for representing four grayscales: large dot LD, medium dot MD, small dot SD, and non-recorded ND on the medium P. Specifically, the driving voltage signal ComA includes driving waveforms Adp1 and Adp2 as signal waveforms in a period t between the rise of the latch signal LAT and the rise of the next latch signal LAT.

[0099] The driving waveform Adp1 is configured within the period tp1 between the rise of the latch signal LAT and the rise of the change signal CH within the period t. In the driving waveform Adp1, the voltage value starts at voltage Vc, changes to drive the piezoelectric element 60, and then ends at voltage Vc. When this driving waveform Adp1 is supplied to one end of the piezoelectric element 60, a predetermined amount of ink is ejected from the corresponding nozzle 651.

[0100] The driving waveform Adp2 is configured within the period tp2 between the rising edge of the switching signal CH and the rising edge of the latch signal LAT within the period t. In the driving waveform Adp2, the voltage value starts at voltage Vc, changes to drive the piezoelectric element 60, and then ends at voltage Vc. When this driving waveform Adp2 is supplied to one end of the piezoelectric element 60, a smaller amount of ink than the predetermined amount is ejected from the corresponding nozzle 651.

[0101] Here, in the following description, the amount of ink ejected from the corresponding nozzle 651 when the driving waveform Adp1 is supplied to one end of the piezoelectric element 60 is sometimes referred to as a medium amount, and the amount of ink ejected from the corresponding nozzle 651 when the driving waveform Adp2 is supplied to one end of the piezoelectric element 60 is less than the predetermined amount and is sometimes referred to as a small amount.

[0102] The driving voltage signal ComB includes a signal waveform for performing the state inspection CD of the nozzle 651 to be inspected among the plurality of nozzles 651. Specifically, the driving voltage signal ComB includes driving waveforms Bdp1, Bdp2, and Bdp3 as signal waveforms within a period t.

[0103] The driving waveform Bdp1 is configured within the period ts1 between the rise of the latch signal LAT and the rise of the test timing signal TSIG within the period t. In the driving waveform Bdp1, the voltage value starts at voltage Vc, changes to drive the piezoelectric element 60, and then ends at voltage Vd. When this driving waveform Bdp1 is supplied to one end of the piezoelectric element 60, the piezoelectric element 60 is driven so that ink is not ejected from the corresponding nozzle 651 and a predetermined residual vibration is generated in the corresponding ejection unit 600.

[0104] The driving waveform Bdp2 is configured within the period ts2 between the rising edge of the inspection timing signal TSIG at the end of the predetermined period ts1 and the rising edge of the next inspection timing signal TSIG within the cycle t. The voltage value of the driving waveform Bdp2 is constant at the voltage Vd. When the driving waveform Bdp2 is supplied to one end of the piezoelectric element 60, the piezoelectric element 60 is not driven, and therefore, ink is not ejected from the corresponding nozzle 651.

[0105] The driving waveform Bdp3 is configured within the period ts3, which begins when the check timing signal TSIG rises at the end of the predetermined period ts2 and ends when the latch signal LAT rises. In the driving waveform Bdp3, the voltage value starts at voltage Vd and then ends when the voltage value reaches voltage Vc. When the driving waveform Bdp3 is supplied to one end of the piezoelectric element 60, the piezoelectric element 60 is not driven, and therefore, ink is not ejected from the corresponding nozzle 651.

[0106] That is, the driving circuit 50 outputs a driving voltage signal COM including a driving voltage signal ComA and a driving voltage signal ComB to the driving signal selection circuit 200, wherein the driving voltage signal ComA includes driving waveforms Adp1 and Adp2 for representing four gray levels of large dot LD, medium dot MD, small dot SD and non-recording ND on the medium P, and the driving voltage signal ComB includes driving waveforms Bdp1, Bdp2, and Bdp3 for performing a status check CD on the ejection part 600 including the nozzle 651 of the inspection object.

[0107] It should be noted that Figure 4 The signal waveform of the driving voltage signal COM shown is an example, and the driving voltage signal COM may include signal waveforms of various shapes according to the type of the medium P on which the ink lands, the characteristics of the ejected ink, and the like.

[0108] 1.3.2 Configuration of the drive signal selection circuit

[0109] A specific example of the configuration of the drive signal selection circuit 200 will be described. Figure 5 2 is a diagram showing an example of the functional configuration of the drive signal selection circuit 200. Figure 5 In FIG. 1 , m ejection units 600 driven by the driving voltage signal Vin output by the driving signal selection circuit 200, namely, ejection units 600-1 to 600-m are shown. Figure 5 As shown, the drive signal selection circuit 200 includes a selection control circuit 220 , m selection circuits 230 , a switching circuit 240 , and a residual vibration detection circuit 250 .

[0110] The clock signal SCK, print data signal S1, latch signal LAT, change signal CH, inspection timing signal TSIG, and voltage signal VHV are input to the selection control circuit 220. Based on the input clock signal SCK, print data signal S1, latch signal LAT, change signal CH, inspection timing signal TSIG, and voltage signal VHV, the selection control circuit 220 outputs selection signals Sa, Sb, and Sc at predetermined logic levels during periods tp1, tp2, ts1, ts2, and ts3, respectively.

[0111] The selection control circuit 220 includes a register 222, a latch circuit 224, and a decoder 226, each provided corresponding to each of the ejection units 600-1 to 600-m of the print head 21. Specifically, the selection control circuit 220 includes at least m register 222, latch circuit 224, and decoder 226 sets.

[0112] The print data signal SI includes three bits of print data SId [SIH, SIM, SIL] serially corresponding to each of the m ejection units 600. The three bits of print data SId [SIH, SIM, SIL] are used to select whether to form large dots LD, medium dots MD, small dots SD, or non-recording dots ND on the medium P, and to perform a status check CD to check the ejection status of the ink ejected from the ejection unit 600. That is, the print data signal SI is a serial signal of at least 3m bits.

[0113] The print data signal SI is input to the selection control circuit 220 in synchronization with the clock signal SCK. The m registers 222 included in the selection control circuit 220 hold the 3-bit print data SId [SIH, SIM, SIL] included in the input print data signal SI, corresponding to the ejection units 600-1 to 600-m.

[0114] Specifically, m registers 222 are cascade-connected corresponding to the ejection units 600-1 to 600-m, respectively. The print data signal SI input to the selection control circuit 220 is sequentially transmitted to the subsequent stages of the m cascade-connected registers 222 in synchronization with the clock signal SCK. In other words, the m registers 222 constitute a shift register. Then, by stopping the supply of the clock signal SCK to the selection control circuit 220, the 3-bit print data SId [SIH, SIM, SIL] corresponding to the ejection units 600-1 to 600-m is retained in the m registers 222. It should be noted that in the following description, in order to distinguish the m cascade-connected registers 222, they may be referred to as level 1, level 2, ..., level m, in the order from the upstream side to the downstream side of the print data signal SI.

[0115] When the latch signal LAT rises, each of the m latch circuits 224 simultaneously latches the 3-bit print data SId [SIH, SIM, SIL] held by the corresponding register 222 .

[0116] The print data SId [SIH, SIM, SIL] latched by the m latch circuits 224 is input to the corresponding decoders 226. The m decoders 226 decode the input print data SId [SIH, SIM, SIL] to generate selection signals Sa, Sb, and Sc of logic levels corresponding to large dots LD, medium dots MD, small dots SD, non-recording ND, and status check CD, respectively.

[0117] Figure 6 2 is a diagram showing an example of the decoding content in the decoder 226. Figure 6 It is shown that when the decoder 226 is input with the printing data SId[SIH,SIM,SIL]=[1,1,0] corresponding to the large dot LD, the logic level of the selection signal Sa is set to H, H level during the periods tp1 and tp2, the logic level of the selection signal Sb is set to L, L, L level during the periods ts1, ts2, ts3, and the logic level of the selection signal Sc is set to L, L, L level during the periods ts1, ts2, ts3.

[0118] In addition, when the decoder 226 is input with the printing data SId[SIH,SIM,SIL]=[1,0,0] corresponding to the midpoint MD, the logic level of the selection signal Sa is set to H and L levels during the periods tp1 and tp2, the logic level of the selection signal Sb is set to L, L, L levels during the periods ts1, ts2, and ts3, and the logic level of the selection signal Sc is set to L, L, L levels during the periods ts1, ts2, and ts3.

[0119] In addition, when the decoder 226 is input with the printing data SId[SIH,SIM,SIL]=[0,1,0] corresponding to the small dot SD, the logic level of the selection signal Sa is set to L, H level during the periods tp1 and tp2, the logic level of the selection signal Sb is set to L, L, L level during the periods ts1, ts2, ts3, and the logic level of the selection signal Sc is set to L, L, L level during the periods ts1, ts2, ts3.

[0120] In addition, when the decoder 226 is input with the printing data SId[SIH,SIM,SIL]=[0,0,0] corresponding to non-recording ND, the logic level of the selection signal Sa is set to L, L level during the periods tp1 and tp2, the logic level of the selection signal Sb is set to L, L, L level during the periods ts1, ts2, ts3, and the logic level of the selection signal Sc is set to L, L, L level during the periods ts1, ts2, ts3.

[0121] In addition, when the decoder 226 inputs the printing data SId[SIH,SIM,SIL]=[1,1,1] corresponding to the status check CD, the logic level of the selection signal Sa is set to L, L level during the periods tp1 and tp2, the logic level of the selection signal Sb is set to H, L, H level during the periods ts1, ts2, ts3, and the logic level of the selection signal Sc is set to L, H, L level during the periods ts1, ts2, ts3.

[0122] As described above, the decoder 226 generates selection signals Sa, Sb, and Sc of logic levels corresponding to the amount of ink ejected from the corresponding ejection unit 600 based on the print data SId [SIH, SIM, SIL]. The selection signals Sa, Sb, and Sc output by the decoder 226 are high-amplitude logic signals that have been level-shifted by a level shifter (not shown). Specifically, the low level of the signals is level-shifted to ground potential, and the high level of the signals is level-shifted to the voltage value of the voltage signal VHV.

[0123] Then, the selection control circuit 220 outputs the selection signals Sa, Sb, and Sc outputted from the decoder 226 to the corresponding selection circuits 230 , and outputs the selection signal Sc outputted from the decoder 226 to the switching circuit 240 .

[0124] Figure 7 2 is a diagram showing an example of the circuit configuration of the selection circuit 230, the switching circuit 240, and the residual vibration detection circuit 250 included in the drive signal selection circuit 200. The drive signal selection circuit 200 includes m selection circuits 230 corresponding to the m piezoelectric elements 60. Here, the m selection circuits 230 all have the same configuration. Figure 7, only the circuit configuration of the selection circuit 230 corresponding to the ejection unit 600 - 1 is shown, and the circuit configurations of the selection circuits 230 corresponding to the other ejection units 600 are omitted.

[0125] The selection circuit 230 includes logic inversion circuits 232 a and 232 b and switch circuits 234 a , 234 b , and 234 c .

[0126] The switch circuit 234a includes an n-type transistor 236a and a p-type transistor 238a. One end of the n-type transistor 236a is electrically connected to one end of the p-type transistor 238a, and the other end of the n-type transistor 236a is electrically connected to the other end of the p-type transistor 238a. Furthermore, a drive voltage signal ComA is supplied to a connection point where one end of the n-type transistor 236a and one end of the p-type transistor 238a are electrically connected. The connection point where the other end of the n-type transistor 236a and the other end of the p-type transistor 238a are electrically connected is electrically connected to one end of the piezoelectric element 60 included in the ejection unit 600-1. Furthermore, a selection signal Sa is supplied to the gate terminal serving as the control terminal of the n-type transistor 236a, and a signal obtained by inverting the logic level of the selection signal Sa using the logic inversion circuit 232a is supplied to the gate terminal serving as the control terminal of the p-type transistor 238a. In other words, the switch circuit 234a constitutes a transmission gate.

[0127] Here, in the following description, the connection point where one end of the n-type transistor 236a and one end of the p-type transistor 238a are electrically connected is sometimes referred to as one end of the switching circuit 234a, and the connection point where the other end of the n-type transistor 236a and the other end of the p-type transistor 238a are electrically connected is sometimes referred to as the other end of the switching circuit 234a.

[0128] The switch circuit 234a configured as described above is controlled to be conductive at one end and the other end by receiving an H-level selection signal Sa. As a result, the switch circuit 234a supplies the drive voltage signal ComA to one end of the piezoelectric element 60. On the other hand, the switch circuit 234a is controlled to be non-conductive at one end and the other end by receiving an L-level selection signal Sa. As a result, the switch circuit 234a does not supply the drive voltage signal ComA to one end of the piezoelectric element 60. In other words, the switch circuit 234a switches whether to supply the drive voltage signal ComA to the piezoelectric element 60 based on the logic level of the selection signal Sa.

[0129] Switching circuit 234b includes an n-type transistor 236b and a p-type transistor 238b. One end of n-type transistor 236b is electrically connected to one end of p-type transistor 238b, and the other end of n-type transistor 236b is electrically connected to the other end of p-type transistor 238b. Furthermore, a driving voltage signal ComB is supplied to a connection point where one end of n-type transistor 236b and one end of p-type transistor 238b are electrically connected. The connection point where the other end of n-type transistor 236b and the other end of p-type transistor 238b are electrically connected is electrically connected to one end of piezoelectric element 60 included in ejection section 600-1. Furthermore, a selection signal Sb is supplied to the gate terminal, which serves as the control terminal of n-type transistor 236b, and a signal obtained by inverting the logic level of selection signal Sb using logic inversion circuit 232b is supplied to the gate terminal, which serves as the control terminal of p-type transistor 238b. In other words, switching circuit 234b constitutes a transmission gate.

[0130] Here, in the following description, the connection point where one end of the n-type transistor 236b and one end of the p-type transistor 238b are electrically connected is sometimes referred to as one end of the switching circuit 234b, and the connection point where the other end of the n-type transistor 236b and the other end of the p-type transistor 238b are electrically connected is sometimes referred to as the other end of the switching circuit 234b.

[0131] The switch circuit 234b configured as described above is controlled to be conductive at one end and the other end by receiving an H-level selection signal Sb. As a result, the switch circuit 234b supplies the drive voltage signal ComB to one end of the piezoelectric element 60. On the other hand, the switch circuit 234b is controlled to be non-conductive at one end and the other end by receiving an L-level selection signal Sb. As a result, the switch circuit 234b does not supply the drive voltage signal ComB to one end of the piezoelectric element 60. In other words, the switch circuit 234b switches whether to supply the drive voltage signal ComB to the piezoelectric element 60 based on the logic level of the selection signal Sb.

[0132] The switch circuit 234c includes an n-type transistor 236c. One end of the n-type transistor 236c is electrically connected to one end of the residual vibration detection circuit 250, and the other end of the n-type transistor 236c is electrically connected to one end of the piezoelectric element 60 included in the ejection unit 600-1. Furthermore, a selection signal Sc is supplied to the gate terminal, which serves as the control terminal of the n-type transistor 236b. In the following description, one end of the n-type transistor 236c may be referred to as one end of the switch circuit 234b, and the other end of the n-type transistor 236c may be referred to as the other end of the switch circuit 234b.

[0133] The switch circuit 234c configured as described above is controlled to be conductive at one end and the other end by receiving an H-level selection signal Sc. As a result, the switch circuit 234c outputs the residual vibration signal Vout-1 output by the piezoelectric element 60 included in the ejection unit 600-1 to the residual vibration detection circuit 250. On the other hand, the switch circuit 234c is controlled to be non-conductive at one end and the other end by receiving an L-level selection signal Sc. As a result, the switch circuit 234c does not output the residual vibration signal Vout-1 output by the piezoelectric element 60 included in the ejection unit 600-1 to the residual vibration detection circuit 250. In other words, the switch circuit 234c switches whether to output the residual vibration signal Vout to the residual vibration detection circuit 250.

[0134] Here, the other ends of the switch circuits 234c included in the m selection circuits 230 corresponding to the ejection units 600-1 to 600-m are connected in common and then electrically connected to the residual vibration detection circuit 250. In other words, the residual vibration signals Vout-1 to Vout-m outputted by the m selection circuits 230 corresponding to the ejection units 600-1 to 600-m propagate through a common wiring pattern and are input to the residual vibration detection circuit 250. In the following description, the residual vibration signals Vout-1 to Vout-m inputted to the residual vibration detection circuit 250 may sometimes be referred to as residual vibration signals dVout.

[0135] The selection circuit 230 configured as described above generates a drive voltage signal Vin by selecting or not selecting the signal waveforms of the drive voltage signals ComA and ComB based on the selection signals Sa and Sb, and supplies the drive voltage signal Vin to one end of the piezoelectric element 60. Furthermore, based on the selection signal Sc, the selection circuit 230 switches whether to obtain the residual vibration signal Vout generated in the corresponding ejection portion 600. In the following description, the states in which one end and the other end of the switch circuit 234a are controlled to be conductive, the states in which one end and the other end of the switch circuit 234b are controlled to be conductive, and the states in which one end and the other end of the switch circuit 234c are controlled to be conductive are sometimes referred to as "on," and the states in which one end and the other end of the switch circuit 234a are controlled to be non-conductive, the states in which one end and the other end of the switch circuit 234b are controlled to be non-conductive, and the states in which one end and the other end of the switch circuit 234c are controlled to be non-conductive are sometimes referred to as "off," respectively.

[0136] Specifically, the selection circuit 230 includes a switch circuit 234a for switching whether the driving voltage signal ComA is supplied to one end of the piezoelectric element 60 included in the ejection unit 600; a switch circuit 234b for switching whether the driving voltage signal ComB is supplied to one end of the piezoelectric element 60 included in the ejection unit 600; and a switch circuit 234c for switching whether the residual vibration signal Vout output by the piezoelectric element 60 of the ejection unit 600 is supplied to the residual vibration detection circuit 250. In this case, in the liquid ejection device 1 of this embodiment, the switch circuit 234a is a transmission gate including an n-type transistor 236a, which is an N-channel transistor, and a p-type transistor 238a, which is a P-channel transistor; the switch circuit 234b is a transmission gate including an n-type transistor 236b, which is an N-channel transistor, and a p-type transistor 238b, which is a P-channel transistor; and the switch circuit 234c is an n-type transistor 236c, which is an N-channel transistor.

[0137] In other words, the selection circuit 230 has: an n-type transistor 236a and a p-type transistor 238a, which switch whether the driving voltage signal ComA is supplied to one end of the piezoelectric element 60 included in the ejection part 600; an n-type transistor 236b and a p-type transistor 238b, which switch whether the driving voltage signal ComB is supplied to one end of the piezoelectric element 60 included in the ejection part 600; and an n-type transistor 236c, which switches whether the residual vibration signal Vout output by the piezoelectric element 60 of the ejection part 600 is supplied to the residual vibration detection circuit 250.

[0138] The switching circuit 240 includes a switch circuit 242 and a logical OR circuit 244. The switch circuit 242 includes an n-type transistor 242a.

[0139] The selection signal Sc output by the decoder 226 corresponding to each of the ejection units 600-1 to 600-m is input to the logical OR circuit 244. Furthermore, the logical OR circuit 244 outputs a switch control signal SS to the control terminal, or gate terminal, of the n-type transistor 242a. One end of the n-type transistor 242a is electrically connected to a wiring pattern for propagating the drive voltage signal ComB, while the other end is electrically connected to the residual vibration detection circuit 250.

[0140] In the switching circuit 240 configured as described above, when any one of the selection signals Sc outputted by the decoders 226 corresponding to the ejection units 600-1 to 600-m is at an H level, the logical OR circuit 244 outputs an H-level switch control signal SS. The H-level switch control signal SS inputted from the switching circuit 240 controls the n-type transistor 242a so that one terminal and the other terminal thereof are turned on. As a result, the switching circuit 240 outputs the drive voltage signal ComB as the drive voltage signal bCom to the residual vibration detection circuit 250.

[0141] That is, switching circuit 240 switches whether to output drive voltage signal ComB as drive voltage signal bCom to residual vibration detection circuit 250 based on the logic level of selection signal Sc. In other words, switching circuit 240 includes n-type transistor 242a, which is an N-channel transistor, for switching whether drive voltage signal ComB is supplied to residual vibration detection circuit 250.

[0142] The residual vibration detection circuit 250 includes resistors R1 , R2 , R3 , R4 , R5 , R6 , and R7 , capacitors C1 and C2 , a power supply circuit PW1 , and an amplifier circuit OP1 .

[0143] The driving voltage signal bCom outputted from the switching circuit 240 is supplied to one end of the resistor R1 , and the residual vibration signal dVout outputted from the m selection circuits 230 is supplied to the other end of the resistor R2 .

[0144] One end of resistor R1 is electrically connected to one end of capacitor C1. The other end of capacitor C1 is electrically connected to one end of resistor R2. The other end of resistor R2 is supplied with ground potential. In other words, capacitor C1 and resistor R2 form a high-pass filter circuit. Furthermore, the output of the high-pass filter circuit formed by capacitor C1 and resistor R2, namely the other end of capacitor C1 and one end of resistor R2, is electrically connected to one end of resistor R3. The other end of resistor R3 is electrically connected to one end of resistor R4 and to the negative input terminal of amplifier circuit OP1. Furthermore, the other end of resistor R4 is electrically connected to the output terminal of amplifier circuit OP1.

[0145] The other end of resistor R1 is electrically connected to one end of capacitor C2. The other end of capacitor C2 is electrically connected to one end of resistor R5. The other end of resistor R5 is supplied with ground potential. In other words, capacitor C2 and resistor R5 form a high-pass filter circuit. Furthermore, the output of the high-pass filter circuit formed by capacitor C2 and resistor R5, namely the other end of capacitor C2 and one end of resistor R5, is electrically connected to one end of resistor R6. The other end of resistor R6 is electrically connected to one end of resistor R7 and to the positive input terminal of amplifier circuit OP1. Furthermore, the other end of resistor R7 is electrically connected to the positive terminal of power supply circuit PW1, and the negative (negative) terminal of power supply circuit PW1 is supplied with ground potential.

[0146] In the residual vibration detection circuit 250 configured as described above, a signal obtained by reducing the DC component of the drive voltage signal bCom using the high-pass filter circuit formed by capacitor C1 and resistor R2 is input to the negative (negative) input terminal of amplifier circuit OP1. A signal obtained by superimposing the bias signal VB output by power supply circuit PW1 on the signal whose DC component, included in the residual vibration signal dVout, has been reduced by the high-pass filter circuit formed by capacitor C2 and resistor R4 is input to the positive input terminal of amplifier circuit OP1. Amplifier circuit OP1 then adds the voltage value of bias signal VB, i.e., voltage vb, to the signal obtained by amplifying the difference between the signal input to the negative (negative) input terminal and the signal input to the positive input terminal at an amplification factor determined by the resistance values ​​of resistors R4 and R3, and outputs the resulting signal as residual vibration detection signal NVT. In other words, residual vibration detection circuit 250 outputs a signal corresponding to the difference between the drive voltage signal bCom and the residual vibration signal dVout, i.e., the potential difference across resistor R1, as residual vibration detection signal NVT.

[0147] That is, the residual vibration detection circuit 250 has a resistor R1 having one end electrically connected to one end of the n-type transistor 236c and the other end electrically connected to one end of the n-type transistor 242a, and an amplifier circuit OP1 that amplifies the potential difference between one end and the other end of the resistor R1, and the residual vibration detection circuit 250 outputs a residual vibration detection signal NVT corresponding to the input residual vibration signal Vout, that is, a residual vibration detection signal NVT corresponding to the difference between the residual vibration signal Vout input via the n-type transistor 236c and the driving voltage signal ComB input via the n-type transistor 242a.

[0148] The operation of the driving signal selection circuit 200 configured as described above will be described in detail. Figure 8 This diagram illustrates an example of the operation of the drive signal selection circuit 200. The print data signal SI is serially supplied to the drive signal selection circuit 200 in synchronization with the clock signal SCK. The print data signal SI input to the drive signal selection circuit 200 is sequentially transmitted to the subsequent registers 222 in synchronization with the clock signal SCK. Then, by stopping the supply of the clock signal SCK to the drive signal selection circuit 200, the m registers 222 each hold 3-bit print data SId [SIH, SIM, SIL] corresponding to the m ejection units 600.

[0149] Then, when the latch signal LAT rises, each latch circuit 224 latches the print data SId[SIH, SIM, SIL] held in the register 222 at the same time. Figure 8LT1 , LT2 , . . . , LTm shown represent print data SId [SIH, SIM, SIL] held by the registers 222 of the 1st, 2nd, . . . , mth stages and latched by the corresponding latch circuits 224 .

[0150] The print data SId[SIH, SIM, SIL] latched by the latch circuit 224 is input to the decoder 226. The decoder 226 performs the Figure 6 The content shown decodes the input print data SId [SIH, SIM, SIL] and outputs selection signals Sa, Sb, Sc of predetermined logic levels within a period t.

[0151] Specifically, when decoder 226 receives print data SId[SIH, SIM, SIL] = [1, 1, 0], it sets the logic level of select signal Sa to H, H during periods tp1 and tp2, sets the logic level of select signal Sb to L, L, L during periods ts1, ts2, and ts3, and sets the logic level of select signal Sc to L, L, L during periods ts1, ts2, and ts3. Consequently, during period tp1, switch circuit 234a is controlled to be on, switch circuit 234b is controlled to be off, and switch circuit 234c is controlled to be off. Consequently, selector circuit 230 selects drive waveform Adp1 during period tp1 and outputs it as drive voltage signal Vin. Furthermore, during period tp2, switch circuit 234a is controlled to be on, switch circuit 234b is controlled to be off, and switch circuit 234c is controlled to be off. Therefore, the selection circuit 230 selects the driving waveform Adp2 during the period tp2 and outputs it as the driving voltage signal Vin.

[0152] That is, when the decoder 226 is input with the print data SId[SIH,SIM,SIL]=[1,1,0], the corresponding selection circuit 230 supplies the piezoelectric element 60 included in the corresponding ejection unit 60 with the continuous drive voltage signal Vin of the drive waveform Adp1 and the drive waveform Adp2 within the period t. Figure 8 The driving voltage signal Vin corresponding to the large dot LD is shown. Consequently, a medium amount of ink is ejected from the corresponding nozzle 651 of the ejection unit 600 during period tp1, and a small amount of ink is ejected from the corresponding nozzle 651 of the ejection unit 600 during period tp2. As a result, during period t, the medium amount of ink and the small amount of ink droplets land on the medium P and combine to form a large dot LD on the medium P.

[0153] Furthermore, when decoder 226 receives print data SId[SIH, SIM, SIL] = [1, 0, 0], it sets the logic levels of select signal Sa to H and L during periods tp1 and tp2, select signal Sb to L, L, L during periods ts1, ts2, and ts3, and select signal Sc to L, L, L during periods ts1, ts2, and ts3. Consequently, during period tp1, switch circuit 234a is turned on, switch circuit 234b is turned off, and switch circuit 234c is turned off. Consequently, selector circuit 230 selects drive waveform Adp1 during period tp1 and outputs it as drive voltage signal Vin. Furthermore, during period tp2, switch circuit 234a is turned off, switch circuit 234b is turned off, and switch circuit 234c is turned off. Therefore, the selection circuit 230 does not select any of the drive waveforms Adp1, Adp2, Bdp1, Bdp2, and Bdp3 during the period tp2. At this time, the voltage Vc held by the capacitance component of the corresponding piezoelectric element 60 is supplied to the corresponding piezoelectric element 60.

[0154] That is, when the decoder 226 is input with the print data SId[SIH,SIM,SIL]=[1,0,0], the corresponding selection circuit 230 supplies the piezoelectric element 60 included in the corresponding ejection unit 60 with the driving waveform Adp1 and the driving voltage signal Vin having a constant signal waveform and a voltage value of Vc to the piezoelectric element 60 included in the corresponding ejection unit 600 within the period t. Figure 8 The driving voltage signal Vin corresponding to the midpoint MD is shown. Consequently, a moderate amount of ink is ejected from the nozzles 651 included in the corresponding ejection unit 600 during period tp1, and no ink is ejected from the nozzles 651 included in the corresponding ejection unit 600 during period tp2. As a result, a moderate amount of ink lands on the medium P during period t, forming the midpoint MD on the medium P.

[0155] Furthermore, when decoder 226 receives print data SId[SIH, SIM, SIL] = [0, 1, 0], it sets the logic levels of select signal Sa to L, H during periods tp1 and tp2, select signal Sb to L, L, L during periods ts1, ts2, and ts3, and select signal Sc to L, L, L during periods ts1, ts2, and ts3. Consequently, during period tp1, switch circuit 234a is controlled to be off, switch circuit 234b is controlled to be off, and switch circuit 234c is controlled to be off. Consequently, selector circuit 230 does not select any of drive waveforms Adp1, Adp2, Bdp1, Bdp2, or Bdp3 during period tp1. At this time, the corresponding piezoelectric element 60 is supplied with voltage Vc, which is maintained by the capacitance component of that piezoelectric element 60. Furthermore, during period tp2, switch circuit 234a is controlled to be on, switch circuit 234b is controlled to be off, and switch circuit 234c is controlled to be off. Therefore, the selection circuit 230 selects the drive waveform Adp2 during period tp2 and outputs it as the drive voltage signal Vin.

[0156] That is, when the decoder 226 is input with the print data SId[SIH,SIM,SIL]=[0,1,0], the corresponding selection circuit 230 supplies the piezoelectric element 60 included in the corresponding ejection unit 60 with a voltage value of voltage Vc and a constant signal waveform continuous with the drive waveform Adp2, that is, the drive voltage signal Vin, which is a constant signal waveform continuous with the drive waveform Adp2, to the piezoelectric element 60 included in the corresponding ejection unit 60 within the period t. Figure 8 The driving voltage signal Vin corresponding to the small dot SD is shown. Consequently, during period tp1, ink is not ejected from the corresponding nozzle 651 included in the ejection unit 600. During period tp2, a small amount of ink is ejected from the corresponding nozzle 651 included in the ejection unit 600. As a result, during period t, a small amount of ink lands on the medium P, forming a small dot SD on the medium P.

[0157] Furthermore, when decoder 226 receives print data SId[SIH, SIM, SIL] = [0, 0, 0], it sets the logic level of select signal Sa to L, L during periods tp1 and tp2, sets the logic level of select signal Sb to L, L, L during periods ts1, ts2, and ts3, and sets the logic level of select signal Sc to L, L, L during periods ts1, ts2, and ts3. Consequently, during period tp1, switch circuit 234a is controlled to be off, switch circuit 234b is controlled to be off, and switch circuit 234c is controlled to be off. Consequently, selector circuit 230 does not select any of drive waveforms Adp1, Adp2, Bdp1, Bdp2, or Bdp3 during period tp1. At this time, the corresponding piezoelectric element 60 is supplied with voltage Vc, which is maintained by the capacitance component of that piezoelectric element 60. Furthermore, during period tp2, switch circuit 234a is controlled to be off, switch circuit 234b is controlled to be off, and switch circuit 234c is controlled to be off. Therefore, selection circuit 230 does not select any of drive waveforms Adp1, Adp2, Bdp1, Bdp2, or Bdp3 during period tp2. At this time, the corresponding piezoelectric element 60 is supplied with voltage Vc maintained by the capacitance component of that piezoelectric element 60.

[0158] That is, when the decoder 226 is input with the print data SId[SIH,SIM,SIL]=[0,0,0], the corresponding selection circuit 230 supplies the driving voltage signal Vin having a voltage value of voltage Vc and a constant signal waveform to the piezoelectric element 60 included in the corresponding ejection unit 600 at period t, i.e. Figure 8 The driving voltage signal Vin corresponding to the non-recording ND is shown. Consequently, ink is not ejected from the corresponding nozzles 651 included in the ejection unit 600 during period tp1, and ink is also not ejected from the corresponding nozzles 651 included in the ejection unit 600 during period tp2. As a result, ink does not land on the medium P during period t, and no dots are formed on the medium P.

[0159] Furthermore, when decoder 226 receives print data SId[SIH, SIM, SIL] = [1, 1, 1], it sets the logic level of select signal Sa to L, L levels during periods tp1 and tp2, sets the logic level of select signal Sb to H, L, H levels during periods ts1, ts2, and ts3, and sets the logic level of select signal Sc to L, H, L levels during periods ts1, ts2, and ts3. Consequently, during period ts1, switch circuit 234a is controlled to be OFF, switch circuit 234b is controlled to be ON, and switch circuit 234c is controlled to be OFF. Consequently, selector circuit 230 selects drive waveform Bdp1 during period ts1 and outputs it as drive voltage signal Vin. Furthermore, during period ts2, switch circuit 234a is controlled to be OFF, switch circuit 234b is controlled to be OFF, and switch circuit 234c is controlled to be ON. Therefore, during period tp2, the selection circuit 230 obtains a residual vibration signal Vout corresponding to the residual vibration generated in the corresponding ejection unit 600 after the piezoelectric element 60 is driven according to the drive waveform Bdp1. Furthermore, during period ts3, the switch circuit 234a is controlled to be off, the switch circuit 234b is controlled to be on, and the switch circuit 234c is controlled to be off. Therefore, during period ts3, the selection circuit 230 selects the drive waveform Bdp3 and outputs it as the drive voltage signal Vin.

[0160] That is, when the decoder 226 is input with the printing data SId[SIH,SIM,SIL]=[1,1,1], the corresponding selection circuit 230 supplies the driving voltage signal Vin for driving the piezoelectric element 60 to the piezoelectric element 60 during the period ts1, so that the ink is not ejected from the nozzle 651 included in the corresponding ejection part 600, and a predetermined residual vibration is generated in the corresponding ejection part 600; the residual vibration signal Vout output by the corresponding piezoelectric element 60 is obtained during the period ts2; and the driving voltage signal Vin is supplied to the piezoelectric element 60 during the period ts3 so that the displacement of the piezoelectric element 60 is in a stable state.

[0161] The residual vibration signal Vout corresponding to the residual vibration generated in the corresponding ejection unit 600, obtained by the selection circuit 230 during the period ts2, is output as the residual vibration signal dVout to the residual vibration detection circuit 250. Furthermore, during the period tp2, the H-level selection signal Sc output by the decoder 226 is also input to the switching circuit 240. Consequently, the switching circuit 240 outputs the drive voltage signal ComB during the period tp2, i.e., the drive waveform Bdp2, as the drive voltage signal bCom to the residual vibration detection circuit 250. The residual vibration detection circuit 250 then adds the voltage value of the bias signal VB, i.e., the voltage vb, to the signal obtained by amplifying the difference between the residual vibration signal dVout and the drive voltage signal bCom, and outputs the signal as the residual vibration detection signal NVT.

[0162] The residual vibration detection signal NVT output by the residual vibration detection circuit 250 is input to the aforementioned waveform information output circuit 270. The waveform information output circuit 270 obtains the period and amplitude of the residual vibration detection signal NVT as input waveform information of the residual vibration detection signal NVT, generates a waveform information signal WFS including the obtained waveform information, and outputs the waveform information signal to the control circuit 100. Based on the input waveform information signal WFS including the waveform information, the control circuit 100 then determines the ejection status of ink from the ejection module 20, specifically, the ejection status of ink from the ejection unit 600 including the piezoelectric element 60 that outputs the residual vibration signal Vout. Specifically, by inputting print data SId[SIH, SIM, SIL] = [1, 1, 1] to the decoder 226, a status check CD is executed to check the ejection status of ink from the corresponding ejection unit 600.

[0163] Here, the residual vibration signal Vout obtained by the selection circuit 230 during period ts2, i.e., the residual vibration signal dVout input to the residual vibration detection circuit 250 during period ts2, is a signal obtained by superimposing the charge output by the piezoelectric element 60 in response to the residual vibration generated in the corresponding ejection unit 600 on the voltage value of the drive waveform Bdp1, i.e., the voltage Vd, supplied to the piezoelectric element 60 prior to period ts2. During period ts2, the drive voltage signal ComB outputted by the switching circuit 240 as the drive voltage signal bCom is a signal having a constant voltage value of the drive waveform Bdp2, i.e., the voltage Vd. In other words, during period ts2, the residual vibration detection circuit 250 extracts and amplifies the signal generated by the charge output by the piezoelectric element 60 in response to the residual vibration generated in the ejection unit 600, and adds the voltage value of the bias signal VB, i.e., the voltage vb, to generate the residual vibration detection signal NVT. In other words, the residual vibration detection circuit 250 shapes the signal waveform of the residual vibration signal Vout output according to the residual vibration generated in the corresponding ejection part 600 , and outputs a residual vibration detection signal NVT corresponding to the residual vibration generated in the ejection part 600 .

[0164] As a result, the residual vibration detection circuit 250 of this embodiment reduces the influence of noise that could be superimposed on the drive voltage signal ComB. Consequently, the accuracy of the residual vibration detection signal NVT output by the residual vibration detection circuit 250 is improved. Consequently, the control circuit 100 improves the accuracy of determining the ejection status of ink from the ejection module 20, that is, the accuracy of determining the ejection status of ink from the ejection unit 600 including the piezoelectric element 60 that outputs the residual vibration signal Vout.

[0165] To summarize, the drive signal selection circuit 200 controls the amount of ink ejected from the corresponding ejection section 600 in each cycle t based on the logic level of the printing data SId[SIH, SIM, SIL] serially included in the printing data signal SI input synchronously with the clock signal SCK, thereby forming multi-grayscale dots on the medium P, and at the same time obtains the residual vibration signal Vout corresponding to the residual vibration generated in the corresponding ejection section 600, and outputs the residual vibration detection signal NVT corresponding to the obtained residual vibration signal Vout.

[0166] Here, it is preferable that the voltage value of the residual vibration signal Vout during the period ts2 when the selection circuit 230 acquires the residual vibration signal Vout, that is, during the period when the n-type transistor 236c is controlled to be on and the n-type transistor 236c outputs the residual vibration signal Vout to the residual vibration detection circuit 250, is less than the value obtained by subtracting the threshold voltage for controlling the n-type transistor 236c to be on, that is, the threshold voltage for switching whether the n-type transistor 236c supplies the residual vibration signal Vout to the residual vibration detection circuit 250, from the voltage value of the selection signal Sc input to the gate terminal, which serves as the control terminal of the n-type transistor 236c. In other words, it is preferable that the voltage value of the drive voltage signal ComB during the period ts2, that is, the voltage value of the drive waveform Bdp2, is less than the voltage value obtained by subtracting the threshold voltage of the n-type transistor 236c from the voltage value of the selection signal Sc, that is, the voltage value of the voltage signal VHV.

[0167] The voltage value associated with the charge output by the piezoelectric element 60 in response to the residual vibration generated in the ejection unit 600, i.e., the charge output by the piezoelectric element 60, is weak. This charge, which is superimposed on the drive waveform Bdp2 in response to the residual vibration generated in the ejection unit 600, is therefore susceptible to the influence of the on-resistance of the n-type transistor 236c when acquiring the residual vibration signal Vout. By setting the voltage value of the residual vibration signal Vout during the period when the n-type transistor 236c outputs the residual vibration signal Vout to the residual vibration detection circuit 250 to be lower than the value obtained by subtracting the threshold voltage for switching whether the n-type transistor 236c supplies the residual vibration signal Vout to the residual vibration detection circuit 250 from the voltage value of the selection signal Sc input to the gate terminal, which serves as the control terminal of the n-type transistor 236c, the on-resistance of the n-type transistor 236c can be reduced. As a result, the accuracy of acquiring the residual vibration signal Vout in the selection circuit 230 is improved, and the accuracy of determining the state of the ejection unit 600 is improved.

[0168] 1.3.3 Structure of the drive signal selection circuit

[0169] Next, an example of the structure of an integrated circuit 300 , which is an integrated circuit device in which the drive signal selection circuit 200 is implemented, will be described. Figure 9 3 is a diagram showing an example of the structure of an integrated circuit 300. Figure 9 In the description, the X-axis and Y-axis are orthogonal to each other. Figure 9 In the description, the front end side of the arrow indicating the X axis in the figure is called the +X side, and the starting point side is called the -(negative) X side. The front end side of the arrow indicating the Y axis in the figure is called the +Y side, and the starting point side is called the -(negative) Y side.

[0170] like Figure 9 As shown, integrated circuit 300 includes substrate 310. Substrate 310 includes short sides 311 and 312, and long sides 313 and 314 that are longer than short sides 311 and 312. When short sides 311 and 312 are oriented along the X-axis, short side 311 is located on the -(negative) X side, and short side 312 is located on the +X side. When long sides 313 and 314 are oriented along the Y-axis, long side 313 is located on the -(negative) Y side, and long side 314 is located on the +Y side. Furthermore, short side 311 is approximately perpendicular to long sides 313 and 314, and short side 312 is approximately perpendicular to long sides 313 and 314. In other words, substrate 310 is generally rectangular. It should be noted that the shape of substrate 310 is not limited to a generally rectangular shape; it can also be circular or other polygonal shapes, and can also have cutouts, arcs, or openings.

[0171] Substrate 310 is provided with terminals Tck, Tsi, Tlt, Tch, Tsg, Tnv, Tca, Tcb, and Tvh, as well as m terminals Tvi. Terminals Tck, Tsi, Tlt, Tch, Tsg, Tnv, Tca, Tcb, and Tvh are located near long side 313 and aligned along the Y-axis. Specifically, terminals Tck, Tsi, Tlt, Tch, Tsg, Tnv, Tca, Tcb, and Tvh are located along the Y-axis in the order of terminal Tvh, terminal Tcb, terminal Tca, terminal Tck, terminal Tsi, terminal Tlt, terminal Tch, terminal Tsg, and terminal Tnv, from the -(negative) X-side toward the +X-side. The m terminals Tvi are located near long side 314 and aligned along the Y-axis. It should be noted that, in addition to the terminals Tck, Tsi, Tlt, Tch, Tsg, Tnv, Tca, Tcb, Tvh, and the m terminals Tvi, a plurality of terminals such as a terminal to which a ground potential is supplied may be provided in the substrate 310 .

[0172] The integrated circuit 300 operates based on signals input via terminals Tck, Tsi, Tlt, Tch, Tsg, Tca, Tcb, and Tvh, and outputs signals corresponding to the operations from terminal Tnv and the m terminals Tvi. Specifically, a clock signal SCK is supplied to terminal Tck, a print data signal SI is supplied to terminal Tsi, a latch signal LAT is supplied to terminal Tlt, a change signal CH is supplied to terminal Tch, a check timing signal TSIG is supplied to terminal Tsg, a drive voltage signal ComA is supplied to terminal Tca, a drive voltage signal ComB is supplied to terminal Tcb, and a voltage signal VHV is supplied to terminal Tvh. Furthermore, a residual vibration detection signal NVT is output from terminal Tnv. Furthermore, a drive voltage signal Vin is output from the m terminals Tvi to the corresponding ejection unit 600, and a residual vibration signal Vout is supplied from the corresponding ejection unit 600 to the m terminals Tvi.

[0173] Furthermore, m registers 222, m latch circuits 224, m decoders 226, m selection circuits 230, a switching circuit 240, and a residual vibration detection circuit 250 constituting the drive signal selection circuit 200 are mounted on the substrate 310. Figure 9 In the figure, the area where the register 222 is installed is illustrated as the installation area Reg, the area where the latch circuit 224 is installed is illustrated as the installation area Lt, the area where the decoder 226 is installed is illustrated as the installation area Dec, the area where the selection circuit 230 is installed is illustrated as the installation area Sel, the area where the logic OR circuit 244 of the switching circuit 240 is installed is illustrated as the installation area Or, the area where the switch circuit 242 of the switching circuit 240 is installed is illustrated as the installation area Sw, and the area where the residual vibration detection circuit 250 is installed is illustrated as the installation area Amp.

[0174] The m mounting areas Reg are located along the X-axis. The m mounting areas Lt are located on the +Y side of the m mounting areas Reg along the X-axis and are also located along the X-axis. The m mounting areas Dec are located on the +Y side of the m mounting areas Lt along the X-axis and are also located along the X-axis. The m mounting areas Sel are located on the +Y side of the m mounting areas Dec along the X-axis and are also located along the X-axis. That is, the m mounting areas Reg, m mounting areas Lt, m mounting areas Dec, and m mounting areas Sel are located along the Y-axis in the order of m mounting areas Reg, m mounting areas Lt, m mounting areas Dec, and m mounting areas Sel, from the - (negative) Y side toward the +Y side.

[0175] In addition, the i-th (i is any one from 1 to m) installation area Reg from the short side 311 side among the m installation areas Reg, the i-th installation area Lt from the short side 311 side among the m installation areas Lt, the i-th installation area Dec from the short side 311 side among the m installation areas Dec, and the i-th installation area Sel from the short side 311 side among the m installation areas Sel are located at positions arranged along the Y axis from the - (negative) Y side toward the +Y side in the order of installation area Reg, installation area Lt, installation area Dec, and installation area Sel.

[0176] The mounting area Or, in which the logical OR circuit 244 of the switching circuit 240 is mounted, is located on the +X side of the m mounting areas Reg, m mounting areas Lt, m mounting areas Dec, and m mounting areas Sel, and at least a portion of the mounting area Or is located between the mounting areas Dec and Sel when viewed along the X-axis. The mounting area Sw, in which the switch circuit 242 of the switching circuit 240 is mounted, is located on the +X side of the mounting area Or, and at least a portion of the mounting area Sw overlaps with the mounting area Or when viewed along the X-axis. The mounting area Amp, in which the residual vibration detection circuit 250 is mounted, is located on the +X side of the mounting area Sw.

[0177] The terminals Tck, Tsi, Tlt, Tch, Tsg, Tnv, Tca, Tcb, Tvh and m terminals Tvi configured as above are electrically connected to m mounting areas Reg, m mounting areas Lt, m mounting areas Dec, m mounting areas Sel, mounting area Or, mounting area Sw and mounting area Amp through a wiring pattern formed on the substrate 310.

[0178] Wiring Wck electrically connects each of the m registers 222 mounted in the m mounting regions Reg. Wiring Wck is also electrically connected to terminal Tck. Furthermore, each of the m registers 222 mounted in the m mounting regions Reg is electrically connected to a register 222 mounted in an adjacent mounting region Reg via a wiring pattern. In other words, the m registers 222 mounted in the m mounting regions Reg are cascade-connected. Furthermore, one end of wiring Wsi electrically connects to the register 222 in the mounting region Reg located closest to the +X side among the m mounting regions Reg arranged along the X-axis, and the other end of wiring Wsi electrically connects to terminal Tsi.

[0179] The print data signal SI supplied to terminal Tsi propagates through wiring Wsi and is input into the register 222 of the mounting area Reg located closest to the +X side among the m mounting areas Reg arranged along the X-axis. The clock signal SCK supplied to terminal Tck propagates through wiring Wck and is input into the m registers 222 mounted in the m mounting areas Reg. Thus, the print data SId [SIH, SIM, SIL] included in the print data signal SI is sequentially transmitted to the subsequent register 222 in synchronization with the clock signal SCK. Subsequently, by stopping the supply of the clock signal SCK to terminal Tck, the print data SId [SIH, SIM, SIL] is retained in the m registers 222 mounted in the m mounting areas Reg.

[0180] The wiring Wlt is electrically connected to the m latch circuits 224 mounted on the m mounting areas Lt, respectively. The wiring Wlt is also electrically connected to the terminal Tlt. In addition, the m latch circuits 224 mounted on the m mounting areas Lt are also electrically connected to the corresponding registers 222 via the wiring pattern. Specifically, the register 222 mounted on the i-th mounting area Reg from the short side 311 side among the m mounting areas Reg is electrically connected to the latch circuit 224 mounted on the i-th mounting area Lt from the short side 311 side among the m mounting areas Lt via the wiring pattern. The register 222 mounted on the i+1-th mounting area Reg from the short side 311 side among the m mounting areas Reg is electrically connected to the latch circuit 224 mounted on the i+1-th mounting area Lt from the short side 311 side among the m mounting areas Lt via the wiring pattern.

[0181] The latch signal LAT supplied to the terminal Tlt propagates through the wiring Wsi and is input to the m latch circuits 224 mounted in the m mounting areas Lt. Then, as the latch signal LAT input to the m latch circuits 224 mounted in the m mounting areas Lt rises, the m latch circuits 224 mounted in the m mounting areas Lt simultaneously latch the print data SId [SIH, SIM, SIL] held by the corresponding register 222.

[0182] The m decoders 226 mounted in the m mounting areas Dec are electrically connected to wiring Wlt, wiring Wch, wiring Wsg, and wiring Wvh. Wiring Wch is also electrically connected to terminal Tch. Wiring Wsg is also electrically connected to terminal Tsg. Wiring Wvh is also electrically connected to terminal Tvh. Furthermore, as previously described, wiring Wlt is also electrically connected to terminal Tlt. Furthermore, the m decoders 226 mounted in the m mounting areas Dec are each electrically connected to the corresponding latch circuit 224 via a wiring pattern. Specifically, the latch circuit 224 installed in the i-th mounting area Lt from the short side 311 side among the m mounting areas Lt is electrically connected to the decoder 226 installed in the i-th mounting area Dec from the short side 311 side among the m mounting areas Dec via the wiring pattern, and the latch circuit 224 installed in the i+1-th mounting area Lt from the short side 311 side among the m mounting areas Lt is electrically connected to the decoder 226 installed in the i+1-th mounting area Dec from the short side 311 side among the m mounting areas Dec via the wiring pattern.

[0183] The latch signal LAT supplied to terminal Tlt, the replacement signal CH supplied to terminal Tch, and the test timing signal TSIG supplied to terminal Tsg propagate through corresponding wirings Wlt, Wch, and Wsg, respectively, and are input to corresponding decoders 226 of the m decoders 226 mounted in the m mounting areas Dec. Furthermore, the voltage signal VHV supplied to terminal Tvh propagates through wiring Wvh and is input to corresponding decoders 226 of the m decoders 226 mounted in the m mounting areas Dec. Then, during corresponding periods of time (tp1 and tp2) defined by the latch signal LAT and the replacement signal CH, and periods (ts1, ts2, and ts3) defined by the latch signal LAT and the test timing signal TSIG, the m decoders 226 mounted in the m mounting areas Dec output selection signals Sa, Sb, and Sc, respectively, obtained by level-shifting the signal corresponding to the logic level latched by the corresponding latch circuit 224 to high-amplitude logic according to the voltage signal VHV.

[0184] The m selection circuits 230 mounted in the m mounting areas Sel are electrically connected to wiring Wca, wiring Wcb, and wiring Wvh. Wiring Wca is also electrically connected to terminal Tca. Wiring Wcb is also electrically connected to terminal Tcb. Furthermore, as previously described, wiring Wvh is also electrically connected to terminal Tvh. Furthermore, the m selection circuits 230 mounted in the m mounting areas Sel are also electrically connected to the corresponding decoders 226 via wiring Wsa for propagating selection signal Sa, wiring Wsb for propagating selection signal Sb, and wiring Wsc for propagating selection signal Sc. Specifically, the decoder 226 installed in the i-th mounting area Dec from the short side 311 among the m mounting areas Dec is electrically connected to the selection circuit 230 installed in the i-th mounting area Sel from the short side 311 among the m mounting areas Sel via wiring Wsa, Wsb, and Wsc, and the decoder 226 installed in the i+1-th mounting area Dec from the short side 311 among the m mounting areas Dec is electrically connected to the selection circuit 230 installed in the i+1-th mounting area Sel from the short side 311 among the m mounting areas Sel via wiring Wsa, Wsb, and Wsc.

[0185] The drive voltage signal ComA supplied to terminal Tca and the drive voltage signal ComB supplied to terminal Tcb propagate through corresponding wirings Wca and Wcb, respectively, and are input to corresponding selection circuits 230 of the m selection circuits 230 mounted in the m mounting areas Sel. The m selection circuits 230 mounted in the m mounting areas Sel select or deselect the drive voltage signals ComA and ComB during corresponding periods tp1 and tp2 and periods ts1, ts2, and ts3, respectively, based on the logic levels of the selection signals Sa, Sb, and Sc propagated and input through wirings Wsa, Wsb, and Wsc, thereby generating drive voltage signals Vin. The drive voltage signals Vin generated by the m selection circuits 230 mounted in the m mounting areas Sel are then output from the integrated circuit 300 via corresponding terminals Tvi. This drives the piezoelectric element 60 included in the corresponding ejection unit 600.

[0186] Furthermore, the m selection circuits 230 mounted in the m mounting areas Sel each receive an input of a residual vibration signal Vout output by the piezoelectric element 60 based on residual vibrations generated after ink is ejected from the corresponding ejection unit 600. The m selection circuits 230 mounted in the m mounting areas Sel each receive the input residual vibration signal Vout based on the logic levels of the input selection signals Sa, Sb, and Sc propagated through the wirings Wsa, Wsb, and Wsc, and output the received residual vibration signal Vout as a residual vibration detection signal NVT.

[0187] The voltage signal VHV supplied to the terminal Tvh propagates through the wiring Wvh and is input to a corresponding mounting area Sel among the m mounting areas Sel. The voltage signal VHV input to a corresponding mounting area Sel among the m mounting areas Sel is supplied to an N-well area Nwell, described later, included in each of the m mounting areas Sel.

[0188] A specific example of the mounting area Sel in which the selection circuit 230 is mounted will be described. Figure 10 FIG. 2 is a diagram showing an example of the structure of the mounting area Sel for mounting the selection circuit 230. Figure 10 In FIG. 1 , the logic inversion circuits 232a and 232b of the selection circuit 230 are simplified. Figure 10 In, use independent of Figure 9 The X-axis and Y-axis shown in the figure are described with the x1-axis and y1-axis being orthogonal to each other. Figure 10 In the description, the front end side of the arrow representing the x1 axis in the figure is sometimes referred to as the +x1 side, the starting point side is sometimes referred to as the -(negative)x1 side, the front end side of the arrow representing the y1 axis in the figure is sometimes referred to as the +y1 side, the starting point side is sometimes referred to as the -(negative)y1 side, and observing the installation area Sel from the normal direction of the plane formed by the x1 axis and the y1 axis is sometimes referred to as a top view of the installation area Sel.

[0189] like Figure 10 As shown, the mounting region Sel includes a P-type substrate region Psub and an N-well region Nwell. The P-type substrate region Psub is a region of a silicon wafer substrate to which impurities such as boron are added, while the N-well region Nwell is a region of the P-type substrate region Psub to which impurities such as phosphorus are added. Furthermore, a ground signal GND is supplied to the P-type substrate region Psub, while a voltage signal VHV is supplied to the N-well region Nwell.

[0190] N-type diffusion layers 331 , 332 , 333 , 341 , 342 , and 343 and electrodes 334 , 335 , 344 , and 345 are formed in the P-type substrate region Psub.

[0191] The N-type diffusion layers 331, 332, and 333 are positioned along the x1 axis, in the order N-type diffusion layer 331, N-type diffusion layer 332, and N-type diffusion layer 333, from the -(negative) x1 side toward the +x1 side. The electrodes 334 and 335 are positioned along the x1 axis, in the order electrode 334 and electrode 335, from the -(negative) x1 side toward the +x1 side. In this case, electrode 334 is positioned such that its end on the -(negative) x1 side overlaps with a portion of the N-type diffusion layer 331 and its end on the +x1 side overlaps with a portion of the N-type diffusion layer 332, as viewed from above the mounting region Sel. Electrode 335 is positioned such that its end on the -(negative) x1 side overlaps with a portion of the N-type diffusion layer 332 and its end on the +x1 side overlaps with a portion of the N-type diffusion layer 333, as viewed from above the mounting region Sel. Specifically, the electrode 334 is located between the N-type diffusion layer 331 and the N-type diffusion layer 332, as viewed from above the mounting region Sel, so as to bridge the N-type diffusion layer 331 and the N-type diffusion layer 332. The electrode 335 is located between the N-type diffusion layer 332 and the N-type diffusion layer 333, as viewed from above the mounting region Sel, so as to bridge the N-type diffusion layer 332 and the N-type diffusion layer 333. Furthermore, an oxide film (not shown) or the like is formed as an insulating layer between the electrode 334 and the P-type substrate region Psub, and between the electrode 335 and the P-type substrate region Psub.

[0192] N-type diffusion layers 341, 342, and 343 are located on the +y1 side of N-type diffusion layers 331, 332, and 333, in the order N-type diffusion layer 341, N-type diffusion layer 342, and N-type diffusion layer 343 along the x1 axis, from the -(negative) x1 side toward the +x1 side. Electrodes 344 and 345 are located in the order electrode 344 and electrode 345 along the x1 axis, from the -(negative) x1 side toward the +x1 side. Electrode 344 is located such that its end on the -(negative) x1 side overlaps with a portion of the N-type diffusion layer 341 and its end on the +x1 side overlaps with a portion of the N-type diffusion layer 342, respectively, as viewed from above the mounting region Sel. Electrode 345 is located such that its end on the -(negative) x1 side overlaps with a portion of the N-type diffusion layer 342 and its end on the +x1 side overlaps with a portion of the N-type diffusion layer 343, as viewed from above the mounting region Sel. Specifically, the electrode 344 is located between the N-type diffusion layer 341 and the N-type diffusion layer 342, so as to bridge the N-type diffusion layer 341 and the N-type diffusion layer 342, when viewed from above the mounting region Sel. The electrode 345 is located between the N-type diffusion layer 342 and the N-type diffusion layer 343, so as to bridge the N-type diffusion layer 342 and the N-type diffusion layer 343, when viewed from above the mounting region Sel. Furthermore, an oxide film (not shown) or the like is formed as an insulating layer between the electrode 344 and the P-type substrate region Psub, and between the electrode 345 and the P-type substrate region Psub.

[0193] P-type diffusion layers 351 , 352 , and 353 and electrodes 354 and 355 are formed in the N-well region Nwell.

[0194] The P-type diffusion layers 351, 352, and 353 are located on the +y1 side of the N-type diffusion layers 341, 342, and 343, in the order of P-type diffusion layer 351, P-type diffusion layer 352, and P-type diffusion layer 353 along the x1 axis, from the -(negative) x1 side toward the +x1 side. Electrodes 354 and 355 are located in the order of electrode 354 and electrode 355 along the x1 axis, from the -(negative) x1 side toward the +x1 side. In this case, electrode 354 is located such that its end on the -(negative) x1 side overlaps with a portion of the P-type diffusion layer 351 and its end on the +x1 side overlaps with a portion of the P-type diffusion layer 352, respectively, when viewed from above the mounting region Sel. Electrode 355 is located such that its end on the -(negative) x1 side overlaps with a portion of the P-type diffusion layer 352 and its end on the +x1 side overlaps with a portion of the P-type diffusion layer 353, when viewed from above the mounting region Sel. Specifically, the electrode 354 is located between the P-type diffusion layer 351 and the P-type diffusion layer 352, as viewed from above the mounting region Sel, so as to bridge the P-type diffusion layer 351 and the P-type diffusion layer 352. The electrode 355 is located between the P-type diffusion layer 352 and the P-type diffusion layer 353, as viewed from above the mounting region Sel, so as to bridge the P-type diffusion layer 352 and the P-type diffusion layer 353. Furthermore, an oxide film (not shown) or the like is formed as an insulating layer between the electrode 354 and the N-well region Nwell, and between the electrode 345 and the N-well region Nwell.

[0195] In the selection circuit 230 mounted in the mounting region Sel as described above, the drive voltage signal ComA is input to the N-type diffusion layer 341 and the P-type diffusion layer 351 via electrodes (not shown), and the drive voltage signal ComB is input to the N-type diffusion layer 343 and the P-type diffusion layer 353 via electrodes (not shown). Furthermore, the selection signal Sa is input to the electrode 344, and after its logic level is inverted by the logic inversion circuit 232a, it is also input to the electrode 354. The selection signal Sb is input to the electrode 345, and after its logic level is inverted by the logic inversion circuit 232b, it is also input to the electrode 355. The selection signal Sc is input to both electrodes 334 and 335. Then, the selection circuit 230 installed in the installation area Sel outputs the signals of the N-type diffusion layer 342 and the P-type diffusion layer 352 as a driving voltage signal Vin via an electrode not shown, and outputs the residual vibration signal Vout generated in the corresponding ejection part 600 along with the driving voltage signal Vin from the N-type diffusion layers 331 and 333 via an electrode not shown and the N-type diffusion layer 332.

[0196] Specifically, when an H-level selection signal Sa is input to the selection circuit 230 mounted in the mounting region Sel, a channel having a channel width Wcn2 is formed in the P-type substrate region Psub, which overlaps with the electrode 344, between the N-type diffusion layer 341 and the N-type diffusion layer 342, as viewed from above the mounting region Sel. A channel having a channel width Wcn3 is formed in the N-well region Nwell, which overlaps with the electrode 354, between the P-type diffusion layer 351 and the P-type diffusion layer 352, as viewed from above the mounting region Sel. Consequently, the drive voltage signal ComA supplied to the N-type diffusion layer 341 and the P-type diffusion layer 351 is supplied to the N-type diffusion layer 342 and the P-type diffusion layer 352, and is output as the drive voltage signal Vin.

[0197] Similarly, when an H-level selection signal Sb is input to the selection circuit 230 mounted in the mounting region Sel, a channel having a channel width Wcn2 is formed in the P-type substrate region Psub, which overlaps with the electrode 345, between the N-type diffusion layer 342 and the N-type diffusion layer 343, as viewed from above the mounting region Sel. A channel having a channel width Wcn3 is formed in the N-well region Nwell, which overlaps with the electrode 355, between the P-type diffusion layer 352 and the P-type diffusion layer 353, as viewed from above the mounting region Sel. Consequently, the drive voltage signal ComB supplied to the N-type diffusion layer 343 and the P-type diffusion layer 353 is supplied to the N-type diffusion layer 342 and the P-type diffusion layer 352, and is output as the drive voltage signal Vin.

[0198] Furthermore, when an H-level selection signal Sc is input to the selection circuit 230 mounted in the mounting region Sel, a channel having a channel width Wcn1 is formed in the P-type substrate region Psub between the N-type diffusion layer 331 and the N-type diffusion layer 332, overlapping with the electrode 334, when viewed from above the mounting region Sel. A channel having a channel width Wcn1 is formed in the P-type substrate region Psub between the N-type diffusion layer 332 and the N-type diffusion layer 333, overlapping with the electrode 335, when viewed from above the mounting region Sel. Consequently, a residual vibration signal Vout corresponding to the residual vibration generated in the corresponding ejection unit 600 in response to the drive voltage signal Vin, supplied to the N-type diffusion layer 332, is supplied to the N-type diffusion layers 331 and 333 and output as the residual vibration signal Vout.

[0199] That is, the N-type diffusion layers 341, 342 and the electrode 344 constitute the n-type transistor 236a included in the switching circuit 234a, the P-type diffusion layers 351, 352 and the electrode 354 constitute the p-type transistor 238a included in the switching circuit 234a, the N-type diffusion layers 343, 342 and the electrode 345 constitute the n-type transistor 236b included in the switching circuit 234b, the P-type diffusion layers 353, 352 and the electrode 355 constitute the p-type transistor 238b included in the switching circuit 234b, and the N-type diffusion layers 331, 332 and the electrode 334 as well as the N-type diffusion layers 332, 333 and the electrode 335 constitute the n-type transistor 236c included in the switching circuit 234c.

[0200] At this time, the ground signal GND of the ground potential supplied to the P-type substrate area Psub is supplied to the back gate terminal of the n-type transistor 236a included in the switching circuit 234a, the back gate terminal of the n-type transistor 236b included in the switching circuit 234b, and the back gate terminal of the n-type transistor 236c included in the switching circuit 234c, and the voltage signal VHV supplied to the N-well area Nwell is supplied to the back gate terminal of the p-type transistor 238a included in the switching circuit 234a and the back gate terminal of the p-type transistor 238b included in the switching circuit 234b.

[0201] return Figure 9 The logical OR circuit 244 mounted in the mounting area Or is electrically connected to m wirings Wsc, each electrically connected to the m decoders 226 mounted in the m mounting areas Dec. As described above, the select signals Sc output by the corresponding decoders 226 are propagated to the wirings Wsc. Thus, the logical OR circuit 244 mounted in the mounting area Or receives the m select signals Sc output by the m decoders 226 mounted in the m mounting areas Dec. The logical OR circuit 244 mounted in the mounting area Or then outputs an H-level switch control signal SS if at least one of the m input select signals Sc is at an H level. If all of the m input select signals Sc are at an L level, the logical OR circuit 244 outputs an L-level switch control signal SS.

[0202] Wiring Wss and wiring Wcb are electrically connected to the switch circuit 242 mounted in the mounting area Sw. Wiring Wss is also electrically connected to the logical OR circuit 244 mounted in the mounting area Or, and the switch control signal SS output by the logical OR circuit 244 mounted in the mounting area Or propagates through wiring Wss. Furthermore, as previously described, wiring Wcb is also electrically connected to the terminal Tcb, and the drive voltage signal ComB supplied to the terminal Tcb propagates through wiring Wcb. Thus, the switch circuit 242 mounted in the mounting area Sw receives the switch control signal SS and the drive voltage signal ComB output by the logical OR circuit 244 mounted in the mounting area Or. Then, the switching circuit 242 installed in the mounting area Sw outputs the driving voltage signal ComB propagated and supplied in the wiring Wcb as the driving voltage signal bCom when the switching control signal SS output by the logic OR circuit 244 installed in the mounting area Or is at the H level; and stops outputting the driving voltage signal ComB as the driving voltage signal bCom when the switching control signal SS output by the logic OR circuit 244 installed in the mounting area Or is at the L level.

[0203] Here, a specific example of the mounting region Sw in which the switch circuit 242 including the n-type transistor 242 a is mounted will be described. Figure 11 2 is a diagram showing an example of the structure of the mounting area Sw for mounting the switch circuit 242. Figure 11 In, use independent of Figure 9 The X-axis, Y-axis and Figure 10 The x1 axis and y1 axis shown in the figure and the x2 axis and y2 axis that are orthogonal to each other are described. Figure 11 In the description, the front end side of the arrow representing the x2 axis in the figure is sometimes referred to as the +x2 side, the starting point side is sometimes referred to as the -(negative)x2 side, the front end side of the arrow representing the y2 axis in the figure is sometimes referred to as the +y2 side, the starting point side is sometimes referred to as the -(negative)y2 side, and observing the installation area Sw from the normal direction of the plane formed by the x2 axis and the y2 axis is sometimes referred to as a top view of the installation area Sw.

[0204] like Figure 11 As shown, the mounting region Sw includes a P-type substrate region Psub. The P-type substrate region Psub is a region where impurities such as boron are added to a silicon wafer substrate. A ground signal GND of a ground potential is supplied to the P-type substrate region Psub.

[0205] In addition, N-type diffusion layers 361 , 362 , and 363 and electrodes 364 and 365 are formed in the P-type substrate region Psub of the mounting region Sw.

[0206] N-type diffusion layers 361, 362, and 363 are positioned along the x2 axis, in the order N-type diffusion layer 361, N-type diffusion layer 362, and N-type diffusion layer 363, from the -(negative) x2 side toward the +x2 side. Electrodes 364 and 365 are positioned along the x2 axis, in the order electrode 364 and electrode 365, from the -(negative) x2 side toward the +x2 side. Electrode 364 is positioned such that its end on the -(negative) x2 side overlaps with a portion of the N-type diffusion layer 361 and its end on the +x2 side, when viewed from above the mounting region Sw. Electrode 365 is positioned such that its end on the -(negative) x2 side overlaps with a portion of the N-type diffusion layer 362 and its end on the +x2 side, when viewed from above the mounting region Sw. Specifically, electrode 364 is located between N-type diffusion layer 361 and N-type diffusion layer 362, so as to bridge N-type diffusion layer 361 and N-type diffusion layer 362, when viewed from above mounting region Sw. Electrode 365 is located between N-type diffusion layer 362 and N-type diffusion layer 363, so as to bridge N-type diffusion layer 362 and N-type diffusion layer 363, when viewed from above mounting region Sw. Furthermore, an oxide film (not shown) or the like is formed as an insulating layer between electrode 364 and P-type substrate region Psub, and between electrode 365 and P-type substrate region Psub.

[0207] In the switch circuit 242 mounted in the mounting region Sw as described above, the drive voltage signal ComB is input to the N-type diffusion layers 361 and 363 via electrodes (not shown). Furthermore, the switch control signal SS is input to electrodes 364 and 365. Then, the n-type transistor 242a mounted in the mounting region Sw outputs the signal from the N-type diffusion layer 362 as the drive voltage signal bCom via an electrode (not shown).

[0208] Specifically, when an H-level switch control signal SS is input to the switch circuit 242 mounted in the mounting region Sw, a channel with a channel width of Wcn4 is formed in the P-type substrate region Psub between the N-type diffusion layers 361 and 362, overlapping with the electrode 364, when viewed from above the mounting region Sw. A channel with a channel width of Wcn4 is formed in the P-type substrate region Psub between the N-type diffusion layers 362 and 363, overlapping with the electrode 365, when viewed from above the mounting region Sw. Consequently, the drive voltage signal ComB supplied to the N-type diffusion layers 361 and 363 is supplied to the N-type diffusion layer 362 and output as the drive voltage signal bCom. In other words, the N-type diffusion layers 361 and 362 and the electrode 364, as well as the N-type diffusion layers 362 and 363 and the electrode 365, constitute the n-type transistor 242a. At this time, the ground signal GND of the ground potential supplied to the P-type substrate region Psub is supplied to the back gate terminal of the n-type transistor 242 a .

[0209] return Figure 9 , wiring Wbc, wiring Wvo, and wiring Wvh are electrically connected to the residual vibration detection circuit 250 mounted in the mounting area Amp. In addition, wiring Wbc is also electrically connected to the n-type transistor 242a mounted in the mounting area Sw, wiring Wvo is also electrically connected to the m selection circuits 230 mounted in the m mounting areas Sel, and wiring Wvh is also electrically connected to the terminal Tvh. The driving voltage signal bCom output by the n-type transistor 242a mounted in the mounting area Sw is transmitted to the wiring Wbc, and the residual vibration signal Vout, i.e., the residual vibration signal dVout, output by each of the m selection circuits 230 mounted in the m mounting areas Sel is transmitted to the wiring Wvo, and the voltage signal VHV is transmitted to the wiring Wvh. Thus, the driving voltage signal bCom and the residual vibration signal dVout are input to the residual vibration detection circuit 250 mounted in the mounting area Amp. Note that, in the mounting region Amp, the voltage signal VHV is used as a reference potential of a well region where some of the circuit elements constituting the residual vibration detection circuit 250 are mounted.

[0210] Then, residual vibration detection circuit 250, mounted in mounting area Amp, generates and outputs residual vibration detection signal NVT by amplifying a signal corresponding to the difference between input drive voltage signal bCom and residual vibration signal dVout. Specifically, residual vibration detection circuit 250 outputs residual vibration detection signal NVT, which is obtained by differentially amplifying residual vibration signal Vout input via n-type transistor 236c and drive voltage signal ComB input via n-type transistor 242a.

[0211] The residual vibration detection signal NVT outputted by the residual vibration detection circuit 250 mounted in the mounting area Amp propagates through the wiring Wnv electrically connected to the residual vibration detection circuit 250 mounted in the mounting area Amp, and is outputted from the terminal Tnv.

[0212] 1.4 Residual vibration signal and ejection part status determination

[0213] Here, a specific example of residual vibration generated in the ejection unit 600 after the drive voltage signal Vin is supplied to the ejection unit 600, and a specific example of a residual vibration signal Vout corresponding to the residual vibration, are described. The liquid ejection device 1 of this embodiment obtains a residual vibration signal Vout corresponding to the residual vibration generated in the ejection unit 600 after the piezoelectric element 60 included in the ejection unit 600 is driven by the drive voltage signal Vin including the drive waveform Bdp1, and determines the state of the corresponding ejection unit 600 based on a residual vibration detection signal NVT corresponding to the obtained residual vibration signal Vout.

[0214] Specifically, in the liquid ejection device 1 of the present embodiment, the piezoelectric element 60 included in the corresponding ejection portion 600 is driven by being supplied with a driving voltage signal Vin including a driving waveform Bdp1. Then, the piezoelectric element 60 is driven, the vibration plate 621 is displaced, and the internal pressure of the pressure chamber 631 changes due to the displacement of the vibration plate 621. Thereafter, the voltage value of the driving voltage signal Vin supplied to the piezoelectric element 60 is constant, thereby generating a damped vibration in the vibration plate 621 that is accompanied by a change in the internal pressure of the pressure chamber 631. At this time, the piezoelectric element 60 is displaced by the damped vibration generated in the vibration plate 621. Then, an electric charge corresponding to the displacement is released from the piezoelectric element 60. The signal corresponding to the electric charge released from the piezoelectric element 60 according to the damped vibration generated in the vibration plate 621 is equivalent to the residual vibration signal Vout.

[0215] Figure 12 : is a diagram showing an example of the residual vibration signal Vout. Figure 12 As shown, the signal waveform of the residual vibration signal Vout is a decaying vibration waveform whose voltage amplitude decreases over time due to the decaying vibration generated in the vibration plate 621 as the internal pressure of the pressure chamber 631 changes. The waveform information such as the amplitude and period included in the decaying vibration waveform of the residual vibration signal Vout changes depending on the state of the ink stored in the pressure chamber 631.

[0216] Here, the relationship between the waveform information of the residual vibration signal Vout and the state of the ink stored in the pressure chamber 631 will be described using a calculation model. Figure 13 This diagram illustrates an example of a calculation model for a single vibration, assuming residual vibrations are generated in the pressure chamber 631 or the vibration plate 621. As previously described, the piezoelectric element 60 is displaced by the supply of the driving voltage signal Vin. As the piezoelectric element 60 moves, the vibration plate 621 also moves. Consequently, the volume of the corresponding pressure chamber 631 changes as the vibration plate 621 moves. At this point, a portion of the ink filling the pressure chamber 631 is ejected from the nozzle 651 based on the pressure generated within the pressure chamber 631.

[0217] During this series of ink ejection operations from the nozzle 651, the vibration plate 621 freely vibrates at a natural frequency determined by the flow path resistance r based on the shape of the ink flow path, the ink viscosity, and other factors, the inertia m generated by the weight of the liquid in the flow path, and the compliance C of the vibration plate 621. The piezoelectric element 60 is displaced in response to the free vibration generated by the vibration plate 621. The charge signal generated by the displacement of the piezoelectric element 60 is output as a residual vibration signal Vout.

[0218] The calculation model of the residual vibration generated in the vibration plate 621 can be represented by pressure p, inertia m, compliance C and flow resistance r. Figure 13 The step response of the circuit shown above when pressure p is applied can be obtained by the following equations (1) to (3).

[0219]

Mathematical formula 1

[0220]

[0221]

Mathematical formula 2

[0222]

[0223]

Mathematical formula 3

[0224]

[0225] Figure 14 : is a diagram for explaining the relationship between the viscosity of ink and the signal waveform of the residual vibration signal Vout. Figure 14 In FIG, time is plotted on the horizontal axis and the magnitude of the residual vibration is plotted on the vertical axis. Figure 14 In the figure, the viscosity of the ink, that is, the signal waveform when the viscosity ratio is 1.0 is shown as waveform a1, the signal waveform when the viscosity ratio is 1.4 is shown as waveform a2, the signal waveform when the viscosity ratio is 1.8 is shown as waveform a3, and the signal waveform when the viscosity ratio is 2.2 is shown as waveform a4.

[0226] like Figure 14 As shown, as the viscosity of the stored ink increases and the thickening ratio increases, the amplitude and attenuation rate of the residual vibration signal Vout change. Specifically, as the viscosity of the ink stored in pressure chamber 631 increases, the flow resistance r increases. Consequently, the amplitude of the damped vibration generated by the vibration plate 621 decreases, and the attenuation rate increases. Consequently, when abnormal thickening occurs in the stored ink, the corresponding amplitude of the residual vibration signal Vout decreases, and the attenuation rate increases.

[0227] in addition, Figure 15 6 is a diagram for explaining the signal waveform of the residual vibration signal Vout when bubbles are mixed into the pressure chamber 631. Figure 15 In FIG, time is plotted on the horizontal axis and the magnitude of the residual vibration is plotted on the vertical axis. Figure 15 , a signal waveform in a normal state where bubbles are not mixed into the pressure chamber 631 is shown as a waveform b1 , and an example of a signal waveform when bubbles are mixed into the pressure chamber 631 is shown as a waveform b2 .

[0228] like Figure 15As shown in Figure 1, when bubbles enter pressure chamber 631, the vibration frequency of residual vibration signal Vout increases. Specifically, when bubbles enter pressure chamber 631, the inertia m, which corresponds to the weight of the stored ink, decreases by an amount corresponding to the amount of bubbles that have entered. Furthermore, as shown in equation (2), the decrease in inertia m increases the angular velocity ω. Consequently, the vibration period of the residual vibration generated by vibration plate 621 decreases, resulting in a higher frequency and shorter period of residual vibration signal Vout.

[0229] In summary, when an abnormality such as increased ink viscosity or an abnormality such as bubble mixing occurs in the pressure chamber 631, the waveform information such as the amplitude and period of the residual vibration signal Vout changes. Therefore, based on the waveform information such as the amplitude and period of the residual vibration signal Vout, the state of the discharge unit 600 including the piezoelectric element 60 that outputs the residual vibration signal Vout can be determined.

[0230] In the liquid ejection device 1 of this embodiment, the drive signal selection circuit 200 acquires the residual vibration signal Vout and shapes it to output as the residual vibration detection signal NVT. The waveform information output circuit 270 then extracts waveform information, such as the amplitude and period, contained in the residual vibration detection signal NVT corresponding to the residual vibration signal Vout. The control circuit 100 determines the state of the corresponding ejection unit 600 based on the waveform information extracted by the waveform information output circuit 270.

[0231] Here, the driving voltage signal ComB is an example of a driving signal, the switch circuit 234c and the n-type transistor 236c which is an N-channel transistor are an example of a first switch circuit, the switch circuit 242 and the n-type transistor 242a which is an N-channel transistor are an example of a second switch circuit, and the control circuit 100 is an example of a processor.

[0232] 1.5 Effects

[0233] In the liquid ejection device 1 and the print head 21 of the present embodiment constructed as described above, there are provided: a pressure chamber 631, the volume of which changes according to the driving voltage signal ComB; a nozzle 651, which is connected to the pressure chamber 631 and ejects liquid; a piezoelectric element 60, which outputs a residual vibration signal Vout corresponding to the residual vibration generated by the volume change of the pressure chamber 631; a residual vibration detection circuit 250, which is input with the residual vibration signal Vout and outputs a residual vibration detection signal NVT corresponding to the residual vibration signal Vout; and a switching circuit 234c, which switches whether the residual vibration signal Vout is supplied to the residual vibration detection circuit 250, the switching circuit 234c being composed only of an n-type transistor 236c, which is an N-channel transistor, and does not include a P-channel transistor.

[0234] Assuming that switching circuit 234c includes a P-channel transistor, a signal with a potential higher than the maximum voltage value of drive voltage signal ComB, such as voltage signal VHV, is supplied to the backgate terminal of the P-channel transistor. To improve the conversion efficiency associated with generating this signal, such high-potential signals, such as voltage signal VHV, are generated by a high-efficiency switching power supply circuit, such as a switching regulator. However, due to the characteristics of the circuit, ripple voltage is superimposed on the signal generated by the switching power supply circuit.

[0235] When a P-channel transistor is included in switch circuit 234c, which switches whether to supply residual vibration signal Vout to residual vibration detection circuit 250, the ripple voltage superimposed on voltage signal VHV via the backgate terminal may contribute to residual vibration signal Vout. In particular, the signal associated with the charge output from piezoelectric element 60 in response to residual vibration generated in ejection unit 600 is very weak, and therefore the influence of the ripple voltage superimposed on voltage signal VHV becomes greater. In other words, when the ripple voltage superimposed on voltage signal VHV contributes to residual vibration signal Vout, the detection accuracy of residual vibration signal Vout, that is, the detection accuracy of the signal associated with the charge output from piezoelectric element 60 in response to residual vibration generated in ejection unit 600, may be reduced.

[0236] In contrast, in the liquid ejection device 1 and print head 21 of this embodiment, the switch circuit 234c that switches whether the residual vibration signal Vout is supplied to the residual vibration detection circuit 250 is composed solely of an n-type transistor 236c, which is an N-channel transistor. This reduces the likelihood that the ripple voltage superimposed on the high voltage voltage signal VHV will be superimposed on the residual vibration signal Vout. As a result, the detection accuracy of the residual vibration signal Vout, that is, the detection accuracy of the residual vibration generated after the piezoelectric element 60 is driven, can be improved.

[0237] Furthermore, in the liquid ejection device 1 and print head 21 of the embodiment, in addition to the switch circuit 234c, i.e., the n-type transistor 236c, which switches whether the residual vibration signal Vout is supplied to the residual vibration detection circuit 250, the switch circuit 242, which switches whether the drive voltage signal ComB is supplied to the residual vibration detection circuit 250, also includes an n-type transistor 242a, which is an N-channel transistor. A ground signal GND, which is a signal of a constant potential and is at a ground potential, is supplied to the backgate terminal of the n-type transistor 236c, and the ground signal GND is also supplied to the backgate terminal of the n-type transistor 242a. In other words, a common signal is supplied to the backgate terminals of the n-type transistor 236c and the n-type transistor 242a. The residual vibration detection circuit 250 then outputs a residual vibration detection signal NVT, which is obtained by differentially amplifying the residual vibration signal Vout input via the n-type transistor 236c and the drive voltage signal ComB input via the n-type transistor 242a.

[0238] In the print head 21 configured as described above, if a signal is superimposed on the residual vibration signal Vout via the backgate terminal of n-type transistor 236c, the same signal is also superimposed on the drive voltage signal ComB via the backgate terminal of n-type transistor 242a. The residual vibration detection circuit 250 then differentially amplifies the residual vibration signal Vout input via n-type transistor 236c and the drive voltage signal ComB input via n-type transistor 242a. The signal superimposed on the residual vibration signal Vout via the backgate terminal of n-type transistor 236c is canceled by the signal superimposed on the drive voltage signal ComB via the backgate terminal of n-type transistor 242a. Thus, even if a signal is superimposed on the residual vibration signal Vout via the backgate terminal of n-type transistor 236c, the likelihood of the signal resulting from the superimposition of the signal on the residual vibration signal Vout contributing to the residual vibration detection signal NVT output by the residual vibration detection circuit 250 is reduced. Consequently, the accuracy of detecting the residual vibration generated after the piezoelectric element 60 is driven can be improved.

[0239] 2. Second Implementation

[0240] Next, a second embodiment of the liquid ejection device 1 will be described. When describing the second embodiment of the liquid ejection device 1, components identical to those of the first embodiment will be denoted by the same reference numerals, and descriptions thereof will be omitted or simplified.

[0241] Figure 16 1 is a diagram showing an example of the circuit configuration of the selection circuit 230, the switching circuit 240, and the residual vibration detection circuit 250 included in the drive signal selection circuit 200 according to the second embodiment. Figure 16As shown, the liquid ejection device 1 of the second embodiment differs from the liquid ejection device 1 of the first embodiment in that, in the drive signal selection circuit 200, the selection circuit 230 includes a logic inversion circuit 232c, the switch circuit 234c of the selection circuit 230 includes a p-type transistor 238c, and the switch circuit 242 of the switching circuit 240 includes a p-type transistor 242b and a logic inversion circuit 243.

[0242] Specifically, in the liquid ejection device 1 of the second embodiment, the switch circuit 234c includes a p-type transistor 238c in addition to an n-type transistor 236c. One end of the n-type transistor 236c is electrically connected to one end of the p-type transistor 238c, and the other end of the n-type transistor 236c is electrically connected to the other end of the p-type transistor 238c. Furthermore, the connection point where one end of the n-type transistor 236c and one end of the p-type transistor 238c are electrically connected is electrically connected to one end of the residual vibration detection circuit 250, and the connection point where the other end of the n-type transistor 236c and the other end of the p-type transistor 238c are electrically connected is electrically connected to one end of the piezoelectric element 60 included in the ejection unit 600-1. Furthermore, a selection signal Sc is supplied to the gate terminal serving as the control terminal of the n-type transistor 236c, and a signal obtained by inverting the logic level of the selection signal Sc using the logic inversion circuit 232c is supplied to the gate terminal serving as the control terminal of the p-type transistor 238c. In other words, the switch circuit 234c of the second embodiment constitutes a transmission gate. Here, the connection point where one end of the n-type transistor 236c is electrically connected to one end of the p-type transistor 238c is equivalent to one end of the switch circuit 234c, and the connection point where the other end of the n-type transistor 236c is electrically connected to the other end of the p-type transistor 238c is equivalent to the other end of the switch circuit 234c.

[0243] The switch circuit 234c constructed as described above is controlled to be conductive at one end and the other end by receiving an H-level selection signal Sc. As a result, the switch circuit 234c outputs the residual vibration signal Vout-1 output by the piezoelectric element 60 included in the ejection section 600-1 to the residual vibration detection circuit 250. On the other hand, the switch circuit 234c is controlled to be non-conductive at one end and the other end by receiving an L-level selection signal Sc. As a result, the switch circuit 234c does not output the residual vibration signal Vout-1 output by the piezoelectric element 60 included in the ejection section 600-1 to the residual vibration detection circuit 250. That is, the switch circuit 234c of the second embodiment switches whether to output the residual vibration signal Vout to the residual vibration detection circuit 250, similarly to the switch circuit 234c of the first embodiment.

[0244] Furthermore, in the liquid ejection device 1 of the second embodiment, the switching circuit 242 includes a p-type transistor 242b in addition to the n-type transistor 242a. One end of the n-type transistor 242a is electrically connected to one end of the p-type transistor 242b, and the other end of the n-type transistor 242a is electrically connected to the other end of the p-type transistor 242b. Furthermore, the connection point between one end of the n-type transistor 242a and one end of the p-type transistor 242b is electrically connected to a wiring pattern for propagating the drive voltage signal ComB, and the connection point between the other end of the n-type transistor 242a and the other end of the p-type transistor 242b is electrically connected to the residual vibration detection circuit 250. Furthermore, the gate terminal, which serves as the control terminal of the n-type transistor 242a, is supplied with a switch control signal SS, and the gate terminal, which serves as the control terminal of the p-type transistor 242b, is supplied with a signal obtained by inverting the logic level of the switch control signal SS using the logic inversion circuit 243. That is, the switching circuit 242 of the second embodiment includes a transmission gate. Here, the connection point where one end of the n-type transistor 242a is electrically connected to one end of the p-type transistor 242b is called one end of the switch circuit 242, and the connection point where the other end of the n-type transistor 242a is electrically connected to the other end of the p-type transistor 242b is called the other end of the switch circuit 242.

[0245] The switch circuit 242 configured as described above is controlled to be conductive at one end and the other end by receiving the H-level switch control signal SS. As a result, the switch circuit 242 outputs the drive voltage signal ComB as the drive voltage signal bCom to the residual vibration detection circuit 250 .

[0246] Next, a specific example of the mounting region Sel in which the selection circuit 230 is mounted according to the second embodiment will be described. Figure 17 FIG. 1 is a diagram showing an example of the configuration of the mounting area Sel for mounting the selection circuit 230 according to the second embodiment. Figure 17 In FIG. 2 , the logic inversion circuits 232a, 232b, and 232c of the selection circuit 230 are simplified. Figure 17 In, use Figure 10 The same axis, that is, the x1 axis and the y1 axis, which are orthogonal to each other, will be described. Figure 17 In the description of Figure 10 Similarly, the front end side of the arrow representing the x1 axis in the figure is called the +x1 side, the starting point side is called the -(negative)x1 side, the front end side of the arrow representing the y1 axis in the figure is called the +y1 side, the starting point side is called the -(negative)y1 side, and observing the installation area Sel from the normal direction of the plane formed by the x1 axis and the y1 axis is called a top view of the installation area Sel.

[0247] like Figure 17As shown, the mounting region Sel of the second embodiment, similar to the mounting region Sel of the first embodiment, includes a P-type substrate region Psub in which impurities such as boron are added to a silicon wafer substrate, and an N-well region Nwell in which impurities such as phosphorus are added to the P-type substrate region Psub. Furthermore, a ground signal GND, representing a ground potential, is supplied to the P-type substrate region Psub, while a voltage signal VHV is supplied to the N-well region Nwell.

[0248] In the P-type substrate region Psub, N-type diffusion layers 331, 332, 333, 341, 342, 343 and electrodes 334, 335, 344, 345 are formed, similarly to the first embodiment. Furthermore, in the N-well region Nwell, P-type diffusion layers 351, 352, 353 and electrodes 354, 355 are formed, similarly to the first embodiment, and P-type diffusion layers 371, 372, 373 and electrodes 374, 375 are also formed.

[0249] P-type diffusion layers 371, 372, and 373 are located on the +y1 side of N-type diffusion layers 341, 342, and 343 and on the -y1 side of P-type diffusion layers 351, 352, and 353, in this order, from the -x1 side toward the +x1 side, along the x1 axis. Electrodes 374 and 375 are located in this order, from the -x1 side toward the +x1 side, along the x1 axis. In this case, electrode 374 is located such that, when viewed from above the mounting region Sel, its end portion on the -(negative) x1 side overlaps with a portion of the P-type diffusion layer 371, and its end portion on the +x1 side overlaps with a portion of the P-type diffusion layer 372. Electrode 375 is located such that, when viewed from above the mounting region Sel, its end portion on the -(negative) x1 side overlaps with a portion of the P-type diffusion layer 372, and its end portion on the +x1 side overlaps with a portion of the P-type diffusion layer 373. Specifically, electrode 374 is located such that it bridges the P-type diffusion layer 371 and the P-type diffusion layer 372 when viewed from above the mounting region Sel, and electrode 375 is located such that it bridges the P-type diffusion layer 372 and the P-type diffusion layer 373 when viewed from above the mounting region Sel. In addition, an oxide film or the like (not shown) is formed as an insulating layer between the electrode 374 and the N-well region Nwell and between the electrode 375 and the N-well region Nwell.

[0250] In the selection circuit 230 mounted in the mounting region Sel as described above, the drive voltage signal ComA is input to the N-type diffusion layer 341 and the P-type diffusion layer 351 via electrodes (not shown), and the drive voltage signal ComB is input to the N-type diffusion layer 343 and the P-type diffusion layer 353 via electrodes (not shown). Furthermore, the selection signal Sa is input to the electrode 344 and, after its logic level is inverted by the logic inversion circuit 232a, is also input to the electrode 354. The selection signal Sb is input to the electrode 345 and, after its logic level is inverted by the logic inversion circuit 232b, is also input to the electrode 355. The selection signal Sc is input to the electrodes 334 and 335 and, after its logic level is inverted by the logic inversion circuit 232c, is also input to the electrodes 374 and 375. Then, the selection circuit 230 installed in the installation area Sel outputs the signals of the N-type diffusion layer 342 and the P-type diffusion layer 352 as a driving voltage signal Vin via an electrode not shown, and outputs the residual vibration signal Vout generated in the corresponding ejection part 600 along with the driving voltage signal Vin from the N-type diffusion layers 331 and 333 via an electrode not shown and the N-type diffusion layer 332, and also outputs it from the P-type diffusion layers 371 and 373 via an electrode not shown and the P-type diffusion layer 372.

[0251] Specifically, when an H-level selection signal Sa is input to the selection circuit 230 mounted in the mounting region Sel, a channel having a channel width Wcn2 is formed in the P-type substrate region Psub, which overlaps with the electrode 344, between the N-type diffusion layer 341 and the N-type diffusion layer 342, as viewed from above the mounting region Sel. A channel having a channel width Wcn3 is formed in the N-well region Nwell, which overlaps with the electrode 354, between the P-type diffusion layer 351 and the P-type diffusion layer 352, as viewed from above the mounting region Sel. Consequently, the drive voltage signal ComA supplied to the N-type diffusion layer 341 and the P-type diffusion layer 351 is supplied to the N-type diffusion layer 342 and the P-type diffusion layer 352, and is output as the drive voltage signal Vin.

[0252] Similarly, when an H-level selection signal Sb is input to the selection circuit 230 mounted in the mounting region Sel, a channel having a channel width Wcn2 is formed in the P-type substrate region Psub, which overlaps with the electrode 345, between the N-type diffusion layer 342 and the N-type diffusion layer 343, as viewed from above the mounting region Sel. A channel having a channel width Wcn3 is formed in the N-well region Nwell, which overlaps with the electrode 355, between the P-type diffusion layer 352 and the P-type diffusion layer 353, as viewed from above the mounting region Sel. Consequently, the drive voltage signal ComB supplied to the N-type diffusion layer 343 and the P-type diffusion layer 353 is supplied to the N-type diffusion layer 342 and the P-type diffusion layer 352, and is output as the drive voltage signal Vin.

[0253] In addition, when the selection signal Sc of the H level is input to the selection circuit 230 mounted on the mounting area Sel, a channel with a channel width Wcn1 is formed in the P-type substrate region Psub between the N-type diffusion layer 331 and the N-type diffusion layer 332, overlapping with the electrode 334, when viewed from above the mounting area Sel. A channel with a channel width Wcn1 is formed in the P-type substrate region Psub between the N-type diffusion layer 332 and the N-type diffusion layer 333, overlapping with the electrode 335, when viewed from above the mounting area Sel. A channel with a channel width Wcn5 is formed in the N-well region Nwell between the P-type diffusion layer 371 and the P-type diffusion layer 372, overlapping with the electrode 374, when viewed from above the mounting area Sel. A channel with a channel width Wcn5 is formed in the N-well region Nwell between the P-type diffusion layer 372 and the P-type diffusion layer 373, overlapping with the electrode 375, when viewed from above the mounting area Sel. Thus, the signal supplied to the N-type diffusion layer 332 and the P-type diffusion layer 372, that is, the residual vibration signal Vout corresponding to the residual vibration generated in the corresponding ejection part 600 accompanied by the driving voltage signal Vin, is supplied to the N-type diffusion layers 331, 333 and the P-type diffusion layers 371, 373, and output as the residual vibration signal Vout.

[0254] The residual vibration signal Vout, which is the residual vibration signal dVout output from the N-type diffusion layers 331 and 333 and the P-type diffusion layers 371 and 373 mounted in the mounting area Sel, propagates in the wiring Wvo and is input to the residual vibration detection circuit 250 mounted in the mounting area Amp.

[0255] That is, the N-type diffusion layers 341, 342 and the electrode 344 constitute the n-type transistor 236a included in the switch circuit 234a, the P-type diffusion layers 351, 352 and the electrode 354 constitute the p-type transistor 238a included in the switch circuit 234a, the N-type diffusion layers 343, 342 and the electrode 345 constitute the n-type transistor 236b included in the switch circuit 234b, the P-type diffusion layers 353, 352 and the electrode 355 constitute the p-type transistor 238b included in the switch circuit 234b, the N-type diffusion layers 331, 332 and the electrode 334, and the N-type diffusion layers 332, 333 and the electrode 335 constitute the n-type transistor 236c included in the switch circuit 234c, and the P-type diffusion layers 371, 372 and the electrode 374, and the P-type diffusion layers 372, 373 and the electrode 375 constitute the p-type transistor 238c included in the switch circuit 234c.

[0256] At this time, the ground signal GND of the ground potential supplied to the P-type substrate area Psub is supplied to the back gate terminal of the n-type transistor 236a included in the switching circuit 234a, the back gate terminal of the n-type transistor 236b included in the switching circuit 234b, and the back gate terminal of the n-type transistor 236c included in the switching circuit 234c, and the voltage signal VHV supplied to the N-well area Nwell is supplied to the back gate terminal of the p-type transistor 238a included in the switching circuit 234a, the back gate terminal of the p-type transistor 238b included in the switching circuit 234b, and the back gate terminal of the p-type transistor 238c included in the switching circuit 234c.

[0257] Next, a specific example of the mounting region Sw in which the switch circuit 242 is mounted according to the second embodiment will be described. Figure 18 2 is a diagram showing an example of the configuration of the mounting area Sw for mounting the switch circuit 242 according to the second embodiment. Figure 18 In FIG. 2 , a simplified diagram is given of the logic inversion circuit 243 of the switch circuit 242. Figure 18 In, use Figure 11 The same axis, that is, the x2 axis and the y2 axis, which are orthogonal to each other, are used for explanation. Figure 18 In the description, the front end side of the arrow representing the x2 axis in the figure is sometimes referred to as the +x2 side, the starting point side is sometimes referred to as the -(negative)x2 side, the front end side of the arrow representing the y2 axis in the figure is sometimes referred to as the +y2 side, the starting point side is sometimes referred to as the -(negative)y2 side, and observing the installation area Sw from the normal direction of the plane formed by the x2 axis and the y2 axis is sometimes referred to as a top view of the installation area Sw.

[0258] like Figure 18 As shown, the mounting region Sw of the second embodiment includes, in addition to the P-type substrate region Psub in the first embodiment, which is a silicon wafer substrate doped with impurities such as boron, the mounting region Sw also includes an N-well region Nwell in which impurities such as phosphorus are doped. Furthermore, a ground signal GND is supplied to the P-type substrate region Psub, and a voltage signal VHV is supplied to the N-well region Nwell. The N-well region Nwell included in the mounting region Sw of the second embodiment and the N-well region Nwell included in the mounting region Sel can be either a single integrated region or separate, independent regions.

[0259] In the P-type substrate region Psub of the mounting region Sw, N-type diffusion layers 361, 362, 363 and electrodes 364, 365 are formed similarly to the first embodiment. Furthermore, in the N-well region Nwell of the mounting region Sw, P-type diffusion layers 381, 382, ​​383 and electrodes 384, 385 are formed.

[0260] P-type diffusion layers 381, 382, ​​and 383 are located on the +y1 side of N-type diffusion layers 361, 362, and 363, with P-type diffusion layer 381, P-type diffusion layer 382, ​​and P-type diffusion layer 383 arranged in this order along the x2 axis from the -(negative) x2 side toward the +x2 side. Electrodes 384 and 385 are located in this order along the x2 axis from the -(negative) x2 side toward the +x2 side. Electrode 384 is located so that its end on the -(negative) x2 side overlaps with a portion of the P-type diffusion layer 381 and its end on the +x2 side overlaps with a portion of the P-type diffusion layer 382, ​​respectively, as viewed from above the mounting region Sw. Electrode 385 is located so that its end on the -(negative) x2 side overlaps with a portion of the P-type diffusion layer 382 and its end on the +x2 side overlaps with a portion of the P-type diffusion layer 383, as viewed from above the mounting region Sw. Specifically, the electrode 384 is located between the P-type diffusion layer 381 and the P-type diffusion layer 382, ​​as viewed from above the mounting region Sw, so as to bridge the P-type diffusion layer 381 and the P-type diffusion layer 382. The electrode 385 is located between the P-type diffusion layer 382 and the P-type diffusion layer 383, so as to bridge the P-type diffusion layer 382 and the P-type diffusion layer 383, as viewed from above the mounting region Sw. Furthermore, an oxide film (not shown) or the like is formed as an insulating layer between the electrode 384 and the N-well region Nwell, and between the electrode 385 and the N-well region Nwell.

[0261] In the switch circuit 242 mounted in the mounting region Sw as described above, the drive voltage signal ComB is input to the N-type diffusion layers 361 and 363 and the P-type diffusion layers 381 and 383 via electrodes (not shown). Furthermore, the switch control signal SS is input to the electrodes 364, 365, 384, and 385. The switch circuit 242 mounted in the mounting region Sw then outputs the signals from the N-type diffusion layer 362 and the P-type diffusion layer 382 as the drive voltage signal bCom via electrodes (not shown).

[0262] Specifically, when an H-level switch control signal SS is input to the switch circuit 242 mounted in the mounting area Sw, a channel with a channel width Wcn4 is formed in the P-type substrate region Psub between the N-type diffusion layer 361 and the N-type diffusion layer 362, overlapping with the electrode 364, when viewed from above the mounting area Sw; a channel with a channel width Wcn4 is formed in the P-type substrate region Psub between the N-type diffusion layer 362 and the N-type diffusion layer 363, overlapping with the electrode 365, when viewed from above the mounting area Sw; a channel with a channel width Wcn6 is formed in the N-well region Nwell between the P-type diffusion layer 381 and the P-type diffusion layer 382, ​​overlapping with the electrode 384, when viewed from above the mounting area Sw; and a channel with a channel width Wcn6 is formed in the N-well region Nwell between the P-type diffusion layer 382 and the P-type diffusion layer 383, overlapping with the electrode 385, when viewed from above the mounting area Sw. Thus, the driving voltage signal ComB supplied to the N-type diffusion layers 361 and 363 and the P-type diffusion layers 381 and 382 is supplied to the N-type diffusion layer 362 and the P-type diffusion layer 382 and output as the driving voltage signal bCom.

[0263] The driving voltage signal bCom output from the N-type diffusion layer 362 and the P-type diffusion layer 382 mounted in the mounting region Sw propagates through the wiring Wbc and is input to the residual vibration detection circuit 250 mounted in the mounting region Amp.

[0264] That is, N-type diffusion layers 361, 362 and electrode 364, as well as N-type diffusion layers 362, 363 and electrode 365, constitute n-type transistor 242a, and P-type diffusion layers 381, 382 and electrode 384, as well as P-type diffusion layers 382, ​​383 and electrode 385, constitute p-type transistor 242b. At this time, a ground signal GND, which is a ground potential supplied to the P-type substrate region Psub, is supplied to the back gate terminal of n-type transistor 242a, while a voltage signal VHV supplied to the N-well region Nwell is supplied to the back gate terminal of p-type transistor 242b.

[0265] As described above, in the liquid ejection device 1 of the second embodiment, the drive voltage signal bCom and the residual vibration signal dVout are input to the residual vibration detection circuit 250 installed in the installation area Amp. Then, the residual vibration detection circuit 250 installed in the installation area Amp amplifies a signal corresponding to the difference between the drive voltage signal ComB as the input drive voltage signal bCom and the residual vibration signal Vout as the residual vibration signal dVout, thereby generating and outputting the residual vibration detection signal NVT. In other words, the residual vibration detection circuit 250 of the second embodiment outputs the residual vibration detection signal NVT obtained by differentially amplifying the residual vibration signal Vout input via the p-type transistor 238c and the drive voltage signal ComB input via the p-type transistor 242b.

[0266] Even in the liquid ejection device 1 of the second embodiment, the residual vibration detection circuit 250 differentially amplifies the residual vibration signal Vout input via the p-type transistor 238c and the drive voltage signal ComB input via the p-type transistor 242b. Therefore, even if a ripple voltage of the voltage signal VHV input to the backgate terminal is superimposed on the residual vibration signal Vout input via the p-type transistor 238c, the ripple voltage is canceled out. As a result, the accuracy of detecting the residual vibration generated after the piezoelectric element 60 is driven can be improved.

[0267] At this time, the wiring Wvo for electrically connecting the p-type transistor 238c and the residual vibration detection circuit 250 of the selection circuit 230 installed in the installation area Sel and for transmitting the residual vibration signal Vout as the residual vibration signal dVout, the wiring Wbc for electrically connecting the p-type transistor 238c and the residual vibration detection circuit 250 of the switch circuit 242 installed in the installation area Sw and for transmitting the drive voltage signal ComB as the drive voltage signal bCom, and the wiring Wbc for transmitting the voltage signal VHV to the selection circuit 230 installed in the installation area Sel are as follows: The wiring Wvh of the mounting area Sel of the circuit 230 and the mounting area Sw in which the switching circuit 242 is mounted, that is, the wiring Wvh for transmitting the voltage signal VHV supplied to the back gate terminal of the p-type transistor 238c of the selection circuit 230 and the back gate terminal of the p-type transistor 242b of the switching circuit 242, preferably, in the integrated circuit 300, at least a portion of the wiring Wvo is configured along the wiring Wvh, at least a portion of the wiring Wbc is configured along the wiring Wvh, and the wiring Wvh is located between the wiring Wvo and the wiring Wbc.

[0268] Figure 19 1 is a diagram showing an example of the structure of the integrated circuit 300 of the second embodiment in which the drive signal selection circuit 200 of the liquid ejection device 1 is mounted, that is, the integrated circuit 300 of the second embodiment. Figure 19 As shown, in the integrated circuit 300 of the second embodiment, the wiring Wvh for propagating the voltage signal VHV extends along the long side of the integrated circuit 300, i.e., the Y axis, between the mounting area Dec and the mounting area Sel, and is electrically connected to the m mounting areas Sel, the mounting area Sw, and the mounting area Amp. Furthermore, the wiring Wvo for propagating the residual vibration signal Vout, which serves as the residual vibration signal dVout, is located between the mounting area Dec and the mounting area Sel on the +Y side of the wiring Wvh and extends along the long side of the integrated circuit 300, i.e., the Y axis. Furthermore, the wiring Wbc for propagating the drive voltage signal ComB, which serves as the drive voltage signal bCom, is located on the - (negative) Y side of the wiring Wvh and extends along the long side of the integrated circuit 300, i.e., the Y axis.

[0269] And, as Figure 19 As shown, between mounting area Sw and mounting area Amp, at least a portion of wiring Wvo is arranged along wiring Wvh, and at least a portion of wiring Wbc is arranged along wiring Wvh, with wiring Wvh located between wiring Wvo and wiring Wbc. This reduces the difference between the contribution of the ripple voltage of voltage signal VHV to residual vibration signal Vout, which is residual vibration signal dVout propagating through wiring Wvo, and the contribution of the ripple voltage of voltage signal VHV to drive voltage signal ComB, which is drive voltage signal bCom propagating through wiring Wbc. Consequently, in residual vibration detection circuit 250, which differentially amplifies residual vibration signal Vout input via p-type transistor 238c and drive voltage signal ComB input via p-type transistor 242b, the ripple voltage of voltage signal VHV superimposed on residual vibration signal Vout can be more accurately canceled. Consequently, the accuracy of detecting residual vibration generated after piezoelectric element 60 is driven can be further improved.

[0270] Furthermore, in the liquid ejection device 1 of the second embodiment, the m mounting areas Sel are electrically connected to the wiring Wvo. Specifically, the wiring Wvo is electrically connected to m p-type transistors 238c, each of which has a backgate terminal supplied with the voltage signal VHV. Therefore, the ripple voltage of the voltage signal VHV may contribute to the residual oscillation signal dVout propagating through the wiring Wvo via the backgate terminals of the m p-type transistors 238c.

[0271] From the perspective of reducing the influence of the ripple voltage of the voltage signal VHV that contributes to the residual vibration signal dVout propagating in the wiring Wvo via the m p-type transistors 238c electrically connected to such a wiring Wvo, it is preferred that the total channel width of one or more transistors whose back gate terminals are supplied with the voltage signal VHV among the one or more transistors electrically connected to the wiring Wvo and the total channel width of one or more transistors whose back gate terminals are supplied with the voltage signal VHV among the one or more transistors electrically connected to the wiring Wbc are approximately equal.

[0272] Specifically, in the integrated circuit 300 of the liquid ejection device 1 according to the second embodiment, a wiring Wvo is electrically connected to m mounting regions Sel. Specifically, m P-channel transistors, each comprising P-type diffusion layers 371 and 372 and an electrode 374, and m P-channel transistors, each comprising P-type diffusion layers 372 and 373 and an electrode 375, are electrically connected to the wiring Wvo. Therefore, the sum of the channel widths of one or more transistors electrically connected to the wiring Wvo, whose back gate terminals are supplied with the voltage signal VHV, is the sum of the channel widths of the m P-channel transistors, each comprising P-type diffusion layers 371 and 372 and an electrode 374 (m×Wcn5), and the channel widths of the m P-channel transistors, each comprising P-type diffusion layers 372 and 373 and an electrode 375 (m×Wcn5), resulting in a value of 2×m×Wcn5.

[0273] On the other hand, in the integrated circuit 300 of the liquid ejection device 1 according to the second embodiment, wiring Wbc is electrically connected to the mounting area Sw. Specifically, wiring Wvo is electrically connected to a P-channel transistor composed of P-type diffusion layers 381 and 382 and electrode 384, and a P-channel transistor composed of P-type diffusion layers 382 and 383 and electrode 385. Therefore, the sum of the channel widths of one or more transistors electrically connected to wiring Wbc, whose back gate terminals are supplied with voltage signal VHV, is the sum of the channel widths of the P-channel transistors composed of P-type diffusion layers 381 and 382 and electrode 384 (i.e., "Wcn6") and the channel widths of the P-channel transistors composed of P-type diffusion layers 382 and 383 and electrode 385 (i.e., "Wcn6"), which equals "2×Wcn5."

[0274] Furthermore, by making the total channel widths of the one or more transistors electrically connected to wiring Wvo, whose backgate terminals are supplied with voltage signal VHV, (i.e., "2×m×Wcn5"), and the total channel widths of the one or more transistors electrically connected to wiring Wbc, whose backgate terminals are supplied with voltage signal VHV, (i.e., "2×Wcn5"), approximately equal, the difference between the contribution of the ripple voltage of voltage signal VHV to residual vibration signal dVout propagating in wiring Wvo via the backgate terminals of m p-type transistors 238c connected to wiring Wvo and the contribution of the ripple voltage of voltage signal VHV to drive voltage signal ComB, which is drive voltage signal bCom, propagating in wiring Wbc can be reduced. Consequently, in residual vibration detection circuit 250, the ripple voltage of voltage signal VHV superimposed on residual vibration signal Vout can be more accurately canceled. Consequently, the accuracy of detecting residual vibration generated after piezoelectric element 60 is driven can be further improved.

[0275] Specifically, by making the combined channel widths of the transistor group consisting of one or more transistors, including p-type transistor 238c, one end of which is electrically connected to wiring Wvo and whose backgate terminals are supplied with voltage signal VHV, and the combined channel widths of the transistor group consisting of one or more transistors, including p-type transistor 242b, one end of which is electrically connected to wiring Wbc and whose backgate terminals are supplied with voltage signal VHV, substantially equal, residual vibration detection circuit 250 can more accurately cancel out the ripple voltage of voltage signal VHV that is superimposed on residual vibration signal Vout. Consequently, the accuracy of detecting residual vibration generated after piezoelectric element 60 is driven can be further improved.

[0276] 3. Modifications

[0277] In the liquid ejection device 1 of the present embodiment described above, the ejection portion 600 for ejecting ink is illustrated and described as having a structure of one pressure chamber 631, but the structure of the ejection portion 600 for ejecting ink is not limited thereto. For example, even if there are two or more pressure chambers 631 relative to one nozzle 651 and a piezoelectric element 60 corresponding to each pressure chamber 631, the same effect can be achieved.

[0278] In addition, in the liquid ejection device 1 of this embodiment, the volume of the pressure chamber 631 is changed by driving the piezoelectric element 60, and the piezoelectric element 60 outputs a signal corresponding to the residual vibration generated by the volume change of the pressure chamber 631. However, the piezoelectric element 60 that changes the volume of the pressure chamber 631 and the piezoelectric element 60 that outputs the signal corresponding to the residual vibration generated by the volume change of the pressure chamber 631 may be different piezoelectric elements. Even with such a configuration, the same functional effects can be achieved.

[0279] Although the embodiments and modifications have been described above, the present invention is not limited to these embodiments and can be implemented in various forms without departing from the spirit and scope of the present invention. For example, the above embodiments can be appropriately combined.

[0280] The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations with the same functions, methods, and results, or configurations with the same purpose and effect). Furthermore, the present invention includes configurations obtained by replacing non-essential portions of the configurations described in the embodiments. Furthermore, the present invention includes configurations that can achieve the same functions and effects as the configurations described in the embodiments, or configurations that can achieve the same purpose. Furthermore, the present invention includes configurations obtained by adding known techniques to the configurations described in the embodiments.

[0281] The following can be derived from the above-mentioned embodiments.

[0282] One type of print head has:

[0283] a pressure chamber whose volume changes according to the driving signal;

[0284] a nozzle, connected to the pressure chamber and configured to spray liquid;

[0285] a piezoelectric element that outputs a residual vibration signal corresponding to residual vibration generated by a volume change of the pressure chamber;

[0286] a residual vibration detection circuit that receives the residual vibration signal and outputs a residual vibration detection signal corresponding to the residual vibration signal; and

[0287] a first switch circuit for switching whether to supply the residual vibration signal to the residual vibration detection circuit;

[0288] The first switch circuit is an N-channel transistor.

[0289] In this printhead, since the first switch circuit that switches whether the residual vibration signal is supplied to the residual vibration detection circuit is composed of an N-channel transistor, the backgate terminal of the N-channel transistor can be set to ground potential. This reduces the likelihood that ripple voltage from a signal supplied to the backgate terminal, such as a high-voltage signal, will be superimposed on the residual vibration signal passing through the first switch circuit. As a result, the accuracy of the residual vibration detection signal output by the residual vibration detection circuit, corresponding to the residual vibration signal, is improved, specifically, the accuracy of detecting the residual vibration generated by the volume change of the pressure chamber.

[0290] In one embodiment of the above-mentioned print head, it is also possible that:

[0291] The piezoelectric element is displaced according to the driving signal,

[0292] The volume of the pressure chamber changes according to the displacement of the piezoelectric element.

[0293] According to this print head, it is not necessary to provide a dedicated piezoelectric element for causing residual vibration in the pressure chamber, and the print head can be miniaturized.

[0294] In one embodiment of the above-mentioned print head, it is also possible that:

[0295] The voltage value of the residual vibration signal during the period when the first switching circuit supplies the residual vibration signal to the residual vibration detection circuit is less than the value obtained by subtracting the voltage value of the threshold voltage at which the first switching circuit switches whether to supply the residual vibration signal to the residual vibration detection circuit from the voltage value of the signal input to the control terminal of the first switching circuit.

[0296] This printhead reduces the on-resistance of the N-channel transistor in the first switching circuit. This improves the accuracy of the residual vibration detection signal corresponding to the residual vibration signal passing through the first switching circuit, that is, the accuracy of detecting the residual vibration generated by the volume change of the pressure chamber.

[0297] In one embodiment of the above-mentioned print head, it is also possible that:

[0298] The print head includes a second switch circuit that switches whether to supply the drive signal to the residual vibration detection circuit.

[0299] The second switch circuit is an N-channel transistor.

[0300] This printhead reduces the likelihood of ripple voltage being superimposed on a signal, such as a high voltage signal, supplied to the backgate terminal via the second switching circuit. Consequently, the accuracy of the residual vibration detection signal output by the residual vibration detection circuit, corresponding to the residual vibration signal, is improved, specifically, the accuracy of detecting the residual vibration generated by the volume change of the pressure chamber.

[0301] In one embodiment of the above-mentioned print head, it is also possible that:

[0302] The residual vibration detection circuit outputs the residual vibration detection signal corresponding to the difference between the residual vibration signal input via the first switch circuit and the drive signal input via the second switch circuit.

[0303] In this printhead, the residual vibration detection circuit outputs a residual vibration detection signal corresponding to the difference between the residual vibration signal input via the first switching circuit (an N-channel transistor) and the drive signal input via the second switching circuit (an N-channel transistor). Therefore, even if noise is superimposed on the residual vibration signal input via the first switching circuit (an N-channel transistor) via the backgate terminal of the N-channel transistor, the same noise is also superimposed on the drive signal input via the second switching circuit (an N-channel transistor). By obtaining the difference, the noise superimposed via the backgate terminal of the N-channel transistor is canceled out. Consequently, the accuracy of the residual vibration detection signal output by the residual vibration detection circuit, which corresponds to the residual vibration signal, is improved, that is, the accuracy of detecting the residual vibration generated by the volume change of the pressure chamber is improved.

[0304] One embodiment of a liquid ejection device comprises:

[0305] A driving circuit outputting a driving signal;

[0306] a pressure chamber, the volume of which changes according to the driving signal;

[0307] a nozzle, connected to the pressure chamber and configured to spray liquid;

[0308] a piezoelectric element that outputs a residual vibration signal corresponding to residual vibration generated by a volume change of the pressure chamber;

[0309] a residual vibration detection circuit which receives the residual vibration signal and outputs a residual vibration detection signal corresponding to the residual vibration signal;

[0310] a first switch circuit for switching whether to supply the residual vibration signal to the residual vibration detection circuit; and

[0311] a processor that determines a discharge state of liquid discharged from the nozzle based on the residual vibration detection signal,

[0312] The first switch circuit is an N-channel transistor.

[0313] In this liquid ejection device, the first switch circuit that switches whether the residual vibration signal from the print head is supplied to the residual vibration detection circuit is composed of an N-channel transistor. This allows the backgate terminal of the N-channel transistor to be set to ground potential. This reduces the likelihood that ripple voltage from a signal supplied to the backgate terminal, such as a high-voltage signal, will be superimposed on the residual vibration signal passing through the first switch circuit. Consequently, the accuracy of the residual vibration detection signal output by the residual vibration detection circuit, which corresponds to the residual vibration signal, and the accuracy of detecting the residual vibration generated by the volume change of the pressure chamber are improved.

[0314] In one embodiment of the liquid ejection device,

[0315] The piezoelectric element is displaced according to the driving signal,

[0316] The volume of the pressure chamber changes according to the displacement of the piezoelectric element.

[0317] According to this liquid ejecting device, it is unnecessary to provide a dedicated piezoelectric element for generating residual vibration in the pressure chamber, and thus the liquid ejecting device can be miniaturized.

[0318] In one embodiment of the liquid ejection device,

[0319] The voltage value of the residual vibration signal during the period when the first switching circuit supplies the residual vibration signal to the residual vibration detection circuit is less than the value obtained by subtracting the voltage value of the threshold voltage at which the first switching circuit switches whether to supply the residual vibration signal to the residual vibration detection circuit from the voltage value of the signal input to the control terminal of the first switching circuit.

[0320] According to this liquid ejection device, the on-resistance of the N-channel transistor serving as the first switching circuit can be reduced. This improves the accuracy of the residual vibration detection signal corresponding to the residual vibration signal passing through the first switching circuit, that is, the accuracy of detecting the residual vibration generated by the volume change of the pressure chamber.

[0321] In one embodiment of the liquid ejection device,

[0322] The liquid ejection device includes a second switch circuit that switches whether to supply the drive signal to the residual vibration detection circuit.

[0323] The second switch circuit is an N-channel transistor.

[0324] According to this liquid ejection device, the possibility of ripple voltage being superimposed on a signal, such as a high voltage signal, supplied to the backgate terminal via the second switching circuit is reduced. As a result, the accuracy of the residual vibration detection signal corresponding to the residual vibration signal output by the residual vibration detection circuit, that is, the accuracy of detecting the residual vibration generated by the volume change of the pressure chamber, is improved.

[0325] In one embodiment of the liquid ejection device,

[0326] The residual vibration detection circuit outputs the residual vibration detection signal corresponding to the difference between the residual vibration signal input via the first switch circuit and the drive signal input via the second switch circuit.

[0327] According to this liquid ejection device, the residual vibration detection circuit outputs a residual vibration detection signal corresponding to the difference between the residual vibration signal input via the first switching circuit, which is an N-channel transistor, and the drive signal input via the second switching circuit, which is an N-channel transistor. Therefore, even if noise is superimposed on the residual vibration signal input via the first switching circuit, which is an N-channel transistor, via the backgate terminal of the N-channel transistor, the same noise is also superimposed on the drive signal input via the second switching circuit, which is an N-channel transistor. By obtaining the difference, the noise superimposed via the backgate terminal of the N-channel transistor is canceled out. Consequently, the accuracy of the residual vibration detection signal corresponding to the residual vibration signal output by the residual vibration detection circuit, that is, the accuracy of detecting the residual vibration generated by the volume change of the pressure chamber, is improved.

Claims

1. A print head, characterized in that: have: a pressure chamber whose volume changes according to the driving signal; a nozzle, connected to the pressure chamber and configured to spray liquid; a piezoelectric element that outputs a residual vibration signal corresponding to residual vibration generated by a volume change of the pressure chamber; a residual vibration detection circuit that receives the residual vibration signal and outputs a residual vibration detection signal corresponding to the residual vibration signal; and a first switch circuit for switching whether to supply the residual vibration signal to the residual vibration detection circuit; The first switch circuit is an N-channel transistor.

2. The print head according to claim 1, wherein The piezoelectric element is displaced according to the driving signal, The volume of the pressure chamber changes according to the displacement of the piezoelectric element.

3. The print head according to claim 1, wherein The voltage value of the residual vibration signal during the period when the first switching circuit supplies the residual vibration signal to the residual vibration detection circuit is less than the value obtained by subtracting the voltage value of the threshold voltage at which the first switching circuit switches whether to supply the residual vibration signal to the residual vibration detection circuit from the voltage value of the signal input to the control terminal of the first switching circuit.

4. The print head according to claim 1, wherein: The print head includes a second switch circuit that switches whether to supply the drive signal to the residual vibration detection circuit. The second switch circuit is an N-channel transistor.

5. The print head according to claim 4, wherein: The residual vibration detection circuit outputs the residual vibration detection signal corresponding to the difference between the residual vibration signal input via the first switch circuit and the drive signal input via the second switch circuit.

6. A liquid ejection device, characterized in that: have: A driving circuit outputting a driving signal; a pressure chamber, the volume of which changes according to the driving signal; a nozzle, connected to the pressure chamber and configured to spray liquid; a piezoelectric element that outputs a residual vibration signal corresponding to residual vibration generated by a volume change of the pressure chamber; a residual vibration detection circuit which receives the residual vibration signal and outputs a residual vibration detection signal corresponding to the residual vibration signal; a first switch circuit for switching whether to supply the residual vibration signal to the residual vibration detection circuit; as well as a processor that determines a discharge state of liquid discharged from the nozzle based on the residual vibration detection signal, The first switch circuit is an N-channel transistor.

7. The liquid ejection device according to claim 6, wherein: The piezoelectric element is displaced according to the driving signal, The volume of the pressure chamber changes according to the displacement of the piezoelectric element.

8. The liquid ejection device according to claim 6, wherein: The voltage value of the residual vibration signal during the period when the first switching circuit supplies the residual vibration signal to the residual vibration detection circuit is less than the value obtained by subtracting the voltage value of the threshold voltage at which the first switching circuit switches whether to supply the residual vibration signal to the residual vibration detection circuit from the voltage value of the signal input to the control terminal of the first switching circuit.

9. The liquid ejection device according to claim 6, wherein: The liquid ejection device includes a second switch circuit that switches whether to supply the drive signal to the residual vibration detection circuit. The second switch circuit is an N-channel transistor.

10. The liquid ejection device according to claim 9, wherein: The residual vibration detection circuit outputs the residual vibration detection signal corresponding to the difference between the residual vibration signal input via the first switch circuit and the drive signal input via the second switch circuit.

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