Head unit, and liquid discharge device

Abstract

To provide a head unit having a drive circuit that drives an improved piezoelectric element.SOLUTION: A head unit comprises: a discharge part that includes a piezoelectric element which drives in response to a drive signal and discharges liquid through the drive by the piezoelectric element; and a drive signal output circuit into which a first DC voltage signal with a first voltage value, a second DC voltage signal with a second voltage value and a discharge control signal are input and which outputs the drive signal. The drive signal output circuit comprises: a first switching circuit for switching whether the first DC voltage signal is supplied to the discharge part or not; a second switching circuit for switching whether the second DC voltage signal is supplied to the discharge part or not; and a selection control circuit for controlling the first switching circuit and the second switching circuit on the basis of the discharge control signal. The first switching circuit includes: a first switching element with the first DC voltage signal supplied to one end and electrically connected to the discharge part at the other end; and a second switching element with the first DC voltage signal supplied to one end and electrically connected to the discharge part at the other end.SELECTED DRAWING: Figure 19

Description

[Technical Field]

[0001] The present invention relates to a head unit and a liquid ejection apparatus. [Background technology]

[0002] Known liquid ejection devices that eject liquid include those that use a driving element such as a piezoelectric element. In such liquid ejection devices, the piezoelectric element is driven in response to the potential difference between a drive signal supplied to one end and a reference potential supplied to the other end, and ejects an amount of liquid corresponding to the drive of the piezoelectric element.

[0003] For example, Patent Document 1 discloses a liquid ejection device having multiple drive circuits that output drive signals, each of which has a modulation circuit that modulates a basic drive signal and multiple power amplifier circuits that power-amplify the signal output by the modulation circuit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-063708 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology described in Patent Document 1 is not sufficient for the configuration of a liquid ejection device and head unit that includes a drive circuit for driving a piezoelectric element, and there is room for improvement. [Means for solving the problem]

[0006] One aspect of the head unit according to the present invention is a discharge unit including a piezoelectric element that is driven by a drive signal and that discharges liquid by driving the piezoelectric element; a drive signal output circuit that receives a first DC voltage signal having a first voltage value, a second DC voltage signal having a second voltage value, and an ejection control signal, and outputs the drive signal; Equipped with The drive signal output circuit a first switch circuit that switches whether or not the first DC voltage signal is supplied to the discharge unit; a second switch circuit that switches whether or not the second DC voltage signal is supplied to the discharge unit; a selection control circuit that controls the first switch circuit and the second switch circuit based on the ejection control signal; and The first switch circuit includes a first switch element having one end supplied with the first DC voltage signal and the other end electrically connected to the discharge portion, and a second switch element having one end supplied with the first DC voltage signal and the other end electrically connected to the discharge portion.

[0007] One aspect of the liquid ejection device according to the present invention is a discharge unit including a piezoelectric element that is driven by a drive signal and that discharges liquid by driving the piezoelectric element; a drive signal output circuit that receives a first DC voltage signal having a first voltage value, a second DC voltage signal having a second voltage value, and an ejection control signal, and outputs the drive signal; a control circuit that outputs the ejection control signal; Equipped with The drive signal output circuit a first switch circuit that switches whether or not the first DC voltage signal is supplied to the discharge unit; a second switch circuit that switches whether or not the second DC voltage signal is supplied to the discharge unit; a selection control circuit that controls the first switch circuit and the second switch circuit based on the ejection control signal; and The first switch circuit includes a first switch element having one end supplied with the first DC voltage signal and the other end electrically connected to the discharge portion, and a second switch element having one end supplied with the first DC voltage signal and the other end electrically connected to the discharge portion. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of a schematic structure of a liquid ejection device. [Figure 2] FIG. 2 is a diagram illustrating an example of a functional configuration of the liquid ejection device. [Figure 3] FIG. 1 is a diagram illustrating an example of the structure of a print head. [Figure 4] FIG. 2 is a diagram illustrating an example of the configuration of a drive signal output circuit. [Figure 5] FIG. 4 is a diagram for explaining a latch signal and a change signal. [Figure 6] FIG. 4 is a diagram illustrating an example of a drive signal. [Figure 7] FIG. 2 is a diagram illustrating an example of the configuration of a waveform selection control circuit. [Figure 8] FIG. 2 is a diagram illustrating an example of the configuration of an output circuit. [Figure 9] 5A and 5B are diagrams for explaining the operation of the drive signal output circuit. [Figure 10] 10A and 10B are diagrams illustrating an example of the operation of the decoder and the signal waveform of the drive signal when print data [SIH, SIL]=[1, 1] is input. [Figure 11] 10A and 10B are diagrams illustrating an example of the operation of a decoder and the signal waveform of a drive signal when print data [SIH, SIL]=[1, 0] is input. [Figure 12] 10A and 10B are diagrams illustrating an example of the operation of a decoder and the signal waveform of a drive signal when print data [SIH, SIL]=[0, 1] is input. [Figure 13] 10A and 10B are diagrams illustrating an example of the operation of a decoder and the signal waveform of a drive signal when print data [SIH, SIL]=[0, 0] is input. [Figure 14] FIG. 10 is a diagram showing an example of the configuration of an output switching circuit 252-1 in a modified example. [Figure 15] FIG. 10 is a diagram showing an example of the configuration of an output switching circuit 252-2 in a modified example. [Figure 16] FIG. 10 is a diagram showing the configuration of an output switching circuit 252-7 of a modified example. [Figure 17] 10A and 10B are diagrams illustrating an example of the relationship between the slope of the signal waveform of the drive signal and the voltage control signal of the modified example. [Figure 18] FIG. 10 is a diagram illustrating an example of the configuration of an output circuit according to a second embodiment. [Figure 19] FIG. 10 is a diagram illustrating an example of the configuration of an output switching circuit according to a modified example of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present invention will be described below with reference to the drawings. The drawings used are for the convenience of explanation. Note that the embodiments described below do not unduly limit the content of the present invention as defined in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0010] 1. First embodiment 1.1 Overview of liquid ejection device 1 is a diagram showing an example of the schematic structure of a liquid ejection device 1. The liquid ejection device 1 in the first embodiment is a so-called line printing type inkjet printer that transports a medium P along a transport direction and that forms an image on the medium P by having print heads 21-1 to 21-7 arranged side by side along a main scanning direction that intersects with the transport direction eject ink, as an example of a liquid, onto the transported medium P. This type of liquid ejection device 1 can use any printing target as the medium P, such as printing paper, resin film, or fabric. Note that the liquid ejection device 1 is not limited to a line printing type inkjet printer, and may also be a serial printing type inkjet printer.

[0011] As shown in FIG. 1, the liquid ejection device 1 includes an ink container 5, a control unit 10, a head unit 20, and a transport unit 40.

[0012] The ink container 5 stores ink of a plurality of colors to be ejected onto the medium P. Colors of ink stored in the ink container 5 include black k, cyan c, magenta m, and yellow y. The ink container 5 may be an ink cartridge, a bag-shaped ink pack made of a flexible film, or an ink tank that can be refilled with ink.

[0013] The control unit 10 includes a processing circuit such as a CPU (Central Processing Unit) or FPGA (Field Programmable Gate Array), and a storage circuit such as a semiconductor memory. The control unit 10 controls each element of the liquid ejection device 1 including the head unit 20.

[0014] The head unit 20 has print heads 21-1 to 21-7. The print heads 21-1 to 21-7 are arranged in a staggered pattern in the order of print head 21-1, print head 21-2, print head 21-3, print head 21-4, print head 21-5, print head 21-6, and print head 21-7 along a scanning direction that intersects with the transport direction in which the medium P is transported.

[0015] The head unit 20 receives as input a control signal Ctrl-H and a voltage signal VDD output from the control unit 10. The control signal Ctrl-H and the voltage signal VDD are input to each of the print heads 21-1 to 21-7. Ink stored in the ink container 5 is supplied to each of the print heads 21-1 to 21-7 via a tube or the like (not shown). Each of the print heads 21-1 to 21-7 ejects ink supplied from the ink container 5 based on the input control signal Ctrl-H and voltage signal VDD.

[0016] The transport unit 40 includes a transport motor 41 and a transport roller 42. The transport motor 41 is driven to rotate based on a control signal Ctrl-T input from the control unit 10. The transport roller 42 rotates in accordance with the rotational drive of the transport motor 41. As the transport roller 42 rotates, the medium P is transported in the transport direction.

[0017] As described above, in the liquid ejection device 1 of the first embodiment, the control unit 10 controls the transport of the medium P and the ejection of ink from the head unit 20. As a result, the print heads 21-1 to 21-7 of the head unit 20 eject ink at timing linked to the transport of the medium P by the transport unit 40. As a result, the ink ejected from the head unit 20 lands at a desired position on the medium P, and a desired image is formed on the medium P.

[0018] 1.2 Functional configuration of the liquid ejection device Next, a description will be given of the functional configuration of the liquid ejection device 1. Fig. 2 is a diagram showing an example of the functional configuration of the liquid ejection device 1. As shown in Fig. 2, the liquid ejection device 1 includes a control unit 10, a head unit 20, and a transport unit 40.

[0019] The control unit 10 includes a constant voltage output circuit 50 and a control circuit 100 .

[0020] The control circuit 100 includes a processor such as a microcontroller, and is communicably connected to an external device such as a host computer (not shown) that is provided outside the liquid ejection device 1. An image information signal including image data to be formed on the medium P is input from the external device to the control circuit 100. The control circuit 100 performs predetermined image processing on the input image information signal, thereby generating various data for controlling the liquid ejection device 1 and signals corresponding to the data, and outputs the generated data to the corresponding components.

[0021] The control circuit 100 generates a control signal Ctrl-T for controlling the transport of the medium P and outputs it to the transport unit 40. This causes the transport motor 41 of the transport unit 40 to rotate, controlling the transport of the medium P along the transport direction. Here, the control signal Ctrl-T output by the control circuit 100 may be converted into a signal by a driver circuit (not shown) and then input to the transport motor 41.

[0022] In addition, based on the input image information signal, the control circuit 100 generates a latch signal LAT, a change signal CH, a clock signal SCK, print data signals SI1 to SI7, and a waveform selection signal WS as control signals Ctrl-H for controlling the head unit 20, and outputs them to the head unit 20.

[0023] The control circuit 100 also outputs a voltage value setting signal VSET to the constant voltage output circuit 50. The constant voltage output circuit 50 generates a constant drive voltage signal VDRV at a voltage value defined by the voltage value setting signal VSET as a voltage signal VDD and outputs it to the head unit 20. Such a constant voltage output circuit 50 may be configured to include an AC / DC converter that converts the AC voltage supplied to the liquid ejection device 1 into a DC voltage, or may be configured to include a DC / DC converter that converts the voltage value of the DC voltage used in the liquid ejection device 1. Here, the constant voltage output circuit 50 of the first embodiment may output a plurality of drive voltage signals VDRV with different voltage values. In other words, the constant voltage output circuit 50 may be configured to include at least a plurality of AC / DC converters and / or DC / DC converters.

[0024] Furthermore, the constant voltage output circuit 50 generates a reference voltage signal VBS as a voltage signal VDD, which serves as a reference potential for driving a piezoelectric element 60 (described later) that the head unit 20 has, and outputs it to the head unit 20. The voltage value of the reference voltage signal VBS output by the constant voltage output circuit 50 may be a constant value defined by the voltage value setting signal VSET, or may be a constant value such as 5.5 V or 6 V that is defined regardless of the voltage value setting signal VSET.

[0025] Here, the voltage values ​​of the drive voltage signal VDRV and the reference voltage signal VBS as the voltage signal VDD output by the constant voltage output circuit 50 being constant includes cases where the voltage values ​​can be regarded as constant when taking into account ripples and noise superimposed on the voltage signal VDD, variations in the electronic components that make up the constant voltage output circuit 50, temperature characteristics, etc.

[0026] The head unit 20 has print heads 21-1 to 21-7. Furthermore, the print head 21-i (i is any of 1 to 7) includes a drive signal output circuit 200 and ejection units 600[1] to 600[n].

[0027] The drive signal output circuit 200 includes an integrated circuit device. The drive signal output circuit 200 of the print head 21-i receives a latch signal LAT, a change signal CH, a clock signal SCK, a print data signal SIi, a waveform selection signal WS, and a drive voltage signal VDRV. Based on the input latch signal LAT, change signal CH, clock signal SCK, print data signal SIi, waveform selection signal WS, and drive voltage signal VDRV, the drive signal output circuit 200 generates drive signals VOUT[1] to VOUT[n] corresponding to each of the ejection units 600[1] to 600[n], and outputs them to the corresponding ejection units 600[1] to 600[n]. The configuration and operation of the drive signal output circuit 200 will be described in detail below.

[0028] The drive signal VOUT[j] (j is any value from 1 to n) output by the drive signal output circuit 200 is input to one end of the piezoelectric element 60 of the ejection unit 600[j]. The reference voltage signal VBS output by the constant voltage output circuit 50 is input to the other end of the piezoelectric element 60 of the ejection unit 600[j]. The piezoelectric element 60 of the ejection unit 600[j] is driven in accordance with the potential difference between the drive signal VOUT[j] input to one end and the reference voltage signal VBS input to the other end. Then, an amount of ink corresponding to the drive of the piezoelectric element 60 of the ejection unit 600[j] is ejected from the ejection unit 600[j]. When the ink ejected from this ejection unit 600[j] lands on the medium P, a dot is formed at a desired position on the medium P.

[0029] That is, the head unit 20 of this embodiment includes an ejection section 600[1] that includes a piezoelectric element 60 driven by a drive signal VOUT[1] and ejects ink by driving the piezoelectric element 60, an ejection section 600[2] that includes a piezoelectric element 60 driven by a drive signal VOUT[2] and ejects ink by driving the piezoelectric element 60, and an ejection section 600[j] that includes a piezoelectric element 60 driven by a drive signal VOUT[j] and ejects ink by driving the piezoelectric element 60.

[0030] Here, the print heads 21-1 to 21-7 all have the same configuration, and may be referred to as print head 21 when there is no need to distinguish them. In this case, the description will be given assuming that a print data signal SI as print data signals SI1 to SI7 is input to the print head 21. Also, the ejection units 600[1] to 600[n] of the print head 21 all have the same configuration, and may be referred to simply as ejection unit 600 when there is no need to distinguish them. In this case, the description will be given assuming that a drive signal VOUT as drive signals VOUT[1] to VOUT[n] is supplied to the ejection unit 600.

[0031] 1.3 Printhead Structure Next, an example of the structure of the print head 21 of the head unit 20 will be described. In the following explanation, an X-axis, a Y-axis, and a Z-axis that are perpendicular to each other will be used. When specifying the direction along the X-axis, the starting side of the arrow along the illustrated X-axis will be referred to as the -X side, and the tip side will be referred to as the +X side. When specifying the direction along the Y-axis, the starting side of the arrow along the illustrated Y-axis will be referred to as the -Y side, and the tip side will be referred to as the +Y side. When specifying the direction along the Z-axis, the starting side of the arrow along the illustrated Z-axis will be referred to as the -Z side, and the tip side will be referred to as the +Z side.

[0032] Fig. 3 is a diagram showing an example of the structure of the print head 21. Here, Fig. 3 shows a cross section of the print head 21, which has a plurality of ejection portions 600 arranged in two rows along the Y axis, cut along the X axis so as to include at least one ejection portion 600.

[0033] 3, the print head 21 has a head chip 300 including a plurality of ejection units 600, and a flexible wiring substrate 400 electrically connected to the head chip 300. The head chip 300 also has a nozzle plate 310, a flow path forming substrate 320, a pressure chamber substrate 330, a protection substrate 340, a compliance unit 350, a vibration plate 360, a case 370, and a piezoelectric element 60.

[0034] The nozzle plate 310 has nozzles 651 that eject ink arranged in two rows along the Y axis. The flow path forming substrate 320 defines individual flow paths 614, communicating flow paths 615, and a reservoir 616. The pressure chamber substrate 330 defines pressure chambers 613. The case 370 defines a reservoir 612 and a liquid inlet 611.

[0035] Ink stored in the ink container 5 is supplied to the head chip 300 via a liquid inlet 611. The ink supplied to the head chip 300 reaches a nozzle 651 via an ink flow path 610 that includes reservoirs 612, 616, an individual flow path 614, a pressure chamber 613, and a communicating flow path 615. The ink that has reached the nozzle 651 is then ejected as the piezoelectric element 60 is driven.

[0036] Specifically, the ink flow path 610 is defined by stacking the flow path forming substrate 320, the pressure chamber substrate 330, and the case 370 along the Z axis. Ink introduced from a liquid inlet 611 is stored in a reservoir 612 defined by the case 370 and a reservoir 616 defined by the flow path forming substrate 320. The reservoirs 612 and 616 are provided in common for each of the multiple nozzles 651 provided in the nozzle plate 310. The ink stored in the reservoirs 612 and 616 is supplied to pressure chambers 613 individually provided corresponding to each of the multiple nozzles 651 via individual flow paths 614 individually provided corresponding to each of the multiple nozzles 651. When pressure is applied to the ink supplied to the pressure chambers 613, the ink stored in the pressure chambers 613 is ejected from the nozzles 651 via a communication flow path 615.

[0037] That is, the ink flow path 610 has a liquid inlet 611 and reservoirs 612, 616 that are common to multiple nozzles 651, and individual flow paths 614, pressure chambers 613, and communicating flow paths 615 that branch off from the reservoir 616 and are individually provided corresponding to each of the multiple nozzles 651.

[0038] The vibration plate 360 ​​is located on the -Z side of the pressure chamber substrate 330 and is provided so as to seal the pressure chamber 613. A piezoelectric element 60 is provided on the -Z side of the vibration plate 360. The piezoelectric element 60 is composed of a piezoelectric body and a pair of electrodes formed on both sides of the piezoelectric body. A drive signal VOUT output by the drive signal output circuit 200 is supplied to one of the pair of electrodes of the piezoelectric element 60, and a reference voltage signal VBS output by the constant voltage output circuit 50 is supplied to the other of the pair of electrodes of the piezoelectric element 60. The piezoelectric body of the piezoelectric element 60 is displaced in response to a potential difference generated between the pair of electrodes of the piezoelectric element 60. That is, the piezoelectric element 60 is driven in response to the potential difference between the drive signal VOUT and the reference voltage signal VBS. As the piezoelectric element 60 is driven, the vibration plate 360 ​​on which the piezoelectric element 60 is provided is deformed. The deformation of the vibration plate 360 ​​changes the internal pressure of the pressure chamber 613. This applies pressure to the ink supplied to the pressure chamber 613. As a result, the ink stored in the pressure chamber 613 is ejected from the nozzle 651 via the communication flow path 615.

[0039] The nozzle plate 310 is located on the +Z side of the flow path forming substrate 320, and is fixed to the flow path forming substrate 320 so that multiple nozzles 651 formed in the nozzle plate 310 communicate with corresponding communicating flow paths 615 formed in the flow path forming substrate 320. A compliance section 350 is also fixed to the +Z side of the flow path forming substrate 320. The compliance section 350 is located on the +Z side of the reservoir 616 and the individual flow paths 614, and includes a sealing film 351 and a support 352. The sealing film 351 is a flexible film-like member that seals the +Z side of the reservoir 616 and the individual flow paths 614. The support 352 supports the outer periphery of the sealing film 351 in a frame-like manner. The compliance section 350 configured as described above protects the head chip 300 and reduces fluctuations in pressure applied to ink inside the reservoir 616 and the communicating flow paths 615.

[0040] Here, the configuration including the piezoelectric element 60 , the vibration plate 360 ​​, the pressure chamber 613 , the individual flow path 614 , the communication flow path 615 , and the nozzle 651 corresponds to the ejection section 600 .

[0041] One end of the flexible wiring board 400 is electrically connected to the diaphragm 360, and the other end is electrically connected to a head substrate (not shown). That is, the other end of the flexible wiring board 400 of each of the print heads 21-1 to 21-7 is electrically connected to the head substrate. A semiconductor device 410 is mounted on the flexible wiring board 400 by COF (Chip On Film). The semiconductor device 410 includes the drive signal output circuit 200 described above.

[0042] The print head 21 has a flexible wiring substrate 400 electrically connected to the ejectors 600[1] to 600[n], and the drive signal output circuit 200 is provided on the flexible wiring substrate 400. This shortens the propagation path of the drive signals VOUT[1] to VOUT[n] that the drive signal output circuit 200 outputs to the ejectors 600[1] to 600[n], reducing the risk of waveform distortion in the drive signals VOUT[1] to VOUT[n] due to the influence of the impedance of the propagation path. This improves the driving accuracy of the piezoelectric elements 60 in each of the ejectors 600[1] to 600[n], improving the accuracy of ink ejection from the ejectors 600[1] to 600[n].

[0043] Furthermore, by shortening the propagation paths of the drive signals VOUT[1] to VOUT[n], the propagation distances of the respective drive signals VOUT[1] to VOUT[n] can be made approximately equal. That is, the propagation distance of the drive signal VOUT[1] from the drive signal output circuit 200 to the discharge unit 600[1], the propagation distance of the drive signal VOUT[2] from the drive signal output circuit 200 to the discharge unit 600[2], and the propagation distance of the drive signal VOUT[j] from the drive signal output circuit 200 to the discharge unit 600[j] are all approximately equal. This reduces the risk of variations in the impedances contributing to each of the drive signals VOUT[1] to VOUT[n]. As a result, the risk of variations occurring in the driving of the piezoelectric elements 60 of each of the ejection sections 600[1] to 600[n] is reduced, and the risk of variations occurring in the ejection of ink from the ejection sections 600[1] to 600[n] is reduced.

[0044] The latch signal LAT, change signal CH, clock signal SCK, print data signals SI1 to SI7, waveform selection signal WS, drive voltage signal VDRV, and reference voltage signal VBS input to the head unit 20 propagate through the head substrate and are input to the flexible wiring board 400 of the corresponding print head 21. The latch signal LAT, change signal CH, clock signal SCK, print data signal SI, waveform selection signal WS, and drive voltage signal VDRV then propagate through the flexible wiring board 400 and are input to a semiconductor device 410 including a drive signal output circuit 200.

[0045] The semiconductor device 410 including the drive signal output circuit 200 generates and outputs drive signals VOUT[1] to VOUT[n] corresponding to the ejection sections 600[1] to 600[n] based on the input latch signal LAT, change signal CH, clock signal SCK, print data signal SI, waveform selection signal WS, and drive voltage signal VDRV.

[0046] The drive signal VOUT output by the semiconductor device 410 propagates through a wiring pattern (not shown) formed on the flexible wiring substrate 400 and the diaphragm 360, and is supplied to one of a pair of electrodes of the piezoelectric element 60. A reference voltage signal VBS propagated through a wiring pattern (not shown) formed on the flexible wiring substrate 400 and the diaphragm 360 is supplied to the other of the pair of electrodes of the piezoelectric element 60. This drives the piezoelectric element 60 in accordance with the potential difference between the drive signal VOUT and the reference voltage signal VBS. Then, an amount of ink corresponding to the drive of the piezoelectric element 60 is ejected from the nozzle 651 of the ejection unit 600.

[0047] 1.4 Configuration and operation of the drive signal output circuit 1.4.1 Configuration of the drive signal output circuit The drive signal output circuit 200 generates drive signals VOUT[1] to VOUT[n] corresponding to each of the ejection sections 600[1] to 600[n] from the drive voltage signal VDRV based on the latch signal LAT, the change signal CH, the clock signal SCK, the print data signals SI1 to SI7, and the waveform selection signal WS, and outputs them to the ejection sections 600[1] to 600[n].

[0048] Fig. 4 is a diagram showing an example of the configuration of the drive signal output circuit 200. As shown in Fig. 4, the drive signal output circuit 200 has a waveform selection control circuit 210, a waveform information storage circuit 230, and output circuits 250[1] to 250[n].

[0049] The waveform information storage circuit 230 includes a nonvolatile memory such as a flash memory or an EEPROM (Electronically Erasable Programmable Read Only Memory). The waveform information storage circuit 230 stores information about the signal waveform of the drive signal VOUT output by the drive signal output circuit 200, for example, waveform information that specifies the decoding content in the decoder 216 (described later) according to the signal waveform of the drive signal VOUT output by the drive signal output circuit 200. The waveform information storage circuit 230 reads out waveform information selected by the input waveform selection signal WS and generates a waveform information signal WI that includes the read waveform information. The waveform information storage circuit 230 then outputs the generated waveform information signal WI to the waveform selection control circuit 210. That is, the drive signal output circuit 200 has a waveform information storage circuit 230 that stores waveform information about the drive signals VOUT[1] to VOUT[n].

[0050] The waveform selection control circuit 210 receives as input the latch signal LAT, change signals CHA, CHB, CHC, and CHD as the change signal CH, the clock signal SCK, the print data signal SI, and the waveform information signal WI output by the waveform information storage circuit 230. The waveform selection control circuit 210 then generates and outputs voltage selection signals S[1] to S[n] based on the input latch signal LAT, change signals CHA, CHB, CHC, and CHD, the clock signal SCK, the print data signal SI, and the waveform information signal WI.

[0051] The output circuits 250[1] to 250[n] are provided corresponding to the ejection portions 600[1] to 600[n] of the print head 21. The output circuits 250[1] to 250[n] are input with the voltage selection signals S[1] to S[n] output by the waveform selection control circuit 210. The output circuits 250[1] to 250[n] are also input with the drive voltage signals VHV1, VHV2, VHV3, VCV, VBV1, VBV2, and VBV3 as the drive voltage signal VDRV. The output circuits 250[1] to 250[n] select or deselect the drive voltage signals VHV1, VHV2, VHV3, VCV, VBV1, VBV2, and VBV3 based on the corresponding voltage selection signals S[1] to S[n], thereby generating drive signals VOUT[1] to VOUT[n] and outputting them to the corresponding discharge units 600[1] to 600[n].

[0052] Specifically, the voltage selection signal S[1] output by the waveform selection control circuit 210 is input to the output circuit 250[1]. The output circuit 250[1] generates a drive signal VOUT[1] by selecting or deselecting the drive voltage signals VHV1, VHV2, VHV3, VCV, VBV1, VBV2, and VBV3 based on the input voltage selection signal S[1], and outputs the drive signal VOUT[1] to the discharge unit 600[1]. In addition, the voltage selection signal S[j] output by the waveform selection control circuit 210 is input to the output circuit 250[j]. The output circuit 250[j] generates a drive signal VOUT[j] by selecting or deselecting the drive voltage signals VHV1, VHV2, VHV3, VCV, VBV1, VBV2, and VBV3 based on the input voltage selection signal S[j], and outputs the drive signal VOUT[j] to the discharge unit 600[j].

[0053] In the following description, the voltage values ​​of the drive voltage signal VDRV specified by the voltage value setting signal VSET will be referred to as follows: voltage Vh1 for drive voltage signal VHV1, voltage Vh2 for drive voltage signal VHV2, voltage Vh3 for drive voltage signal VHV3, voltage Vc for drive voltage signal VCV, voltage Vb1 for drive voltage signal VBV1, voltage Vb2 for drive voltage signal VBV2, and voltage Vb3 for drive voltage signal VBV3. The voltage values ​​of voltages Vh1, Vh2, Vh3, Vc, Vb1, Vb2, and Vb3 will be described in the order of greatest magnitude: Vh3, Vh2, Vh1, Vc, Vb1, Vb2, and Vb3. That is, voltage Vc is greater than voltages Vb1, Vb2, and Vb3, and voltages Vh1, Vh2, and Vh3 are greater than voltage Vc. Such voltages Vh1, Vh2, Vh3, Vc, Vb1, Vb2, and Vb3 can be changed by voltage value setting signal VSET.

[0054] In the following description, the output circuits 250[1] to 250[n] corresponding to the ejection units 600 may be referred to as output circuits 250. In this case, the description will be given on the assumption that the voltage selection signal S is input to the output circuit 250 as the voltage selection signal S[j].

[0055] As described above, the drive signal output circuit 200 of the first embodiment receives as input the drive voltage signal VHV1 having a voltage value of voltage Vh1, the drive voltage signal VHV2 having a voltage value of voltage Vh2, the drive voltage signal VHV3 having a voltage value of voltage Vh3, the drive voltage signal VCV having a voltage value of voltage Vc, the drive voltage signal VBV1 having a voltage value of voltage Vb1, the drive voltage signal VBV2 having a voltage value of voltage Vb2, the drive voltage signal VBV3 having a voltage value of voltage Vb3, and the print data signal SI. The drive signal output circuit 200 outputs drive signals VOUT[1] to VOUT[n] based on the drive voltage signal VHV1 having a voltage value of voltage Vh1, the drive voltage signal VHV2 having a voltage value of voltage Vh2, the drive voltage signal VHV3 having a voltage value of voltage Vh3, the drive voltage signal VCV having a voltage value of voltage Vc, the drive voltage signal VBV1 having a voltage value of voltage Vb1, the drive voltage signal VBV2 having a voltage value of voltage Vb2, the drive voltage signal VBV3 having a voltage value of voltage Vb3, and the print data signal SI.

[0056] Specifically, the drive signal output circuit 200 selects or deselects the drive voltage signal VHV1, selects or deselects the drive voltage signal VHV2, selects or deselects the drive voltage signal VHV3, selects or deselects the drive voltage signal VCV, selects or deselects the drive voltage signal VBV1, selects or deselects the drive voltage signal VBV2, and selects or deselects the drive voltage signal VBV3 based on the print data signal SI, thereby outputting the drive signals VOUT[1] to VOUT[n].

[0057] 1.4.2 Functions of Latch Signal and Change Signal CH Next, the latch signal LAT and the change signals CHA, CHB, CHC, and CHD input to the drive signal output circuit 200 will be described.

[0058] FIG. 5 is a diagram illustrating the latch signal LAT and the change signals CHA, CHB, CHC, and CHD. As shown in FIG. 5, the latch signal LAT is a pulse signal that defines the dot formation period cd at which dots are formed on the medium P. Specifically, the control circuit 100 acquires the transport position of the medium P using an encoder (not shown) or the like. The control circuit 100 then outputs a latch signal LAT that temporarily goes high at a predetermined timing synchronized with the acquired transport position of the medium P, thereby defining the dot formation period cd at which dots are formed on the medium P in accordance with the transport position of the medium P. Note that if the liquid ejection device 1 is a serial printing inkjet printer, the control circuit 100 may also define the dot formation period cd by outputting a latch signal that temporarily goes high at a predetermined timing synchronized with the scanning position of a carriage that carries the print head 21 and moves in the scanning direction, in addition to the transport position of the medium P.

[0059] Change signal CHA is a pulse signal that divides the dot formation period cd into p periods pa1 to pap (p is an integer greater than or equal to 1). Change signal CHB is a pulse signal that divides the dot formation period cd into q periods pb1 to pbq (q is an integer greater than or equal to 1). Change signal CHC is a pulse signal that divides the dot formation period cd into r periods pc1 to pcr (r is an integer greater than or equal to 1). Change signal CHD is a pulse signal that divides the dot formation period cd into s periods pd1 to pdr (s is an integer greater than or equal to 1). The timing and number at which these change signals CHA, CHB, CHC, and CHD go to H level are controlled by control circuit 100 in accordance with the signal waveform defined by waveform selection signal WS. That is, the control circuit 100 controls the timing at which the change signals CHA, CHB, CHC, and CHD temporarily become H level in the dot formation cycle cd and the number of times that the change signals CHA, CHB, CHC, and CHD temporarily become H level in the dot formation cycle cd, thereby independently controlling the number of divisions of the dot formation cycle cd and the lengths of the periods pa1~pap, pb1~pbq, pc1~pcr, and pd1~pds.

[0060] 1.4.3 Example of drive signal VOUT Next, an example of the drive signal VOUT output by the drive signal output circuit 200 will be described. Fig. 6 is a diagram showing an example of the drive signal VOUT. As shown in Fig. 6, the drive signal output circuit 200 of the first embodiment outputs a drive signal VOUT including a drive waveform DEP, a drive signal VOUT including a drive waveform BSD, a drive signal VOUT including a drive waveform NVT, and a drive signal VOUT including a drive waveform ND.

[0061] The drive waveform DEP has a constant voltage Vc at time t0 when the latch signal LAT rises, a voltage drop at time ta1 after time t0, and then a constant voltage Vb3. The voltage rises at time ta2 after time ta1, and then a constant voltage Vh3. The voltage drop at time ta3 after time ta2, and then a constant voltage Vc. That is, the drive waveform DEP is a signal waveform whose voltage changes in the following order during the dot formation period cd: Vc, Vb3, Vh3, and Vc. When a drive signal VOUT including such a drive waveform DEP is input to the ejection unit 600, the piezoelectric element 60 is driven to draw ink from the reservoir 616 into the pressure chamber 613 during the period from time ta1 to ta2, and is driven to eject the drawn ink from the nozzle 651 during the period from time ta2 to ta3. That is, the drive waveform DEP is a signal waveform that drives the piezoelectric element 60 to eject ink from the ejection unit 600.

[0062] The drive waveform BSD has a constant voltage Vc at time t0 when the latch signal LAT rises. At time tb1 after time t0, the voltage drops, then remains constant at Vb1. At time tb2 after time tb1, the voltage rises, and then remains constant at Vc. That is, the drive waveform BSD is a signal waveform whose voltage changes in the order of Vc, Vb1, and Vc during the dot formation period cd. When a drive signal VOUT including such a drive waveform BSD is input to the ejection unit 600, the piezoelectric element 60 is driven to such an extent that liquid is not ejected from the nozzle 651. As a result, the ink near the nozzle 651 vibrates. This reduces the risk of the ink near the nozzle 651 of the ejection unit 600 drying out and increasing in viscosity. That is, the drive waveform BSD is a signal waveform that drives the piezoelectric element 60 to prevent ink from being ejected from the ejection unit 600.

[0063] The drive waveform NVT has a voltage value that is constant at voltage Vc at time t0 when the latch signal LAT rises. At time tc1 after time t0, the voltage value rises, then remains constant at voltage Vh2. At time tc2 after time tc1, the voltage value drops, then remains constant at voltage Vb2. At time tc3 after time tc2, the voltage value rises, then remains constant at voltage Vc. That is, the drive waveform NVT is a signal waveform whose voltage value changes in the following order during the dot formation period cd: voltage Vc, voltage Vh2, voltage Vb2, and voltage Vc. When a drive signal VOUT including such a drive waveform NVT is input to the ejection unit 600, the piezoelectric element 60 is driven to a degree that prevents liquid from being ejected from the nozzle 651 during the period from time ta2 to ta3, thereby generating a predetermined residual vibration in the ink stored in the pressure chamber 613. At this time, a counter electromotive force associated with the residual vibration is generated in the piezoelectric element 60. It is known that the amplitude and period of the back electromotive force generated by this piezoelectric element 60 changes depending on the state of the ejection section 600. The drive signal output circuit 200 determines the state of the ejection section 600 by acquiring the back electromotive force associated with the residual vibration generated in this piezoelectric element 60. In other words, the drive waveform NVT is a signal waveform for inspecting the state of the ejection section 600.

[0064] The drive waveform ND is a signal waveform whose voltage value is constant at voltage Vc during the dot formation period cd. When a drive signal VOUT including such a drive waveform ND is input to the ejection section 600, the piezoelectric element 60 is not driven and ink is not ejected from the nozzle 651. In other words, the drive waveform ND is a signal waveform that does not drive the piezoelectric element 60 included in the ejection section 600 but keeps it in a constant state.

[0065] That is, the drive signal output circuit 200 outputs a drive signal VOUT[1] including a drive waveform DEP that drives the piezoelectric element 60 included in the ejection section 600[1] so that ink is ejected from the ejection section 600[1], a drive signal VOUT[1] including a drive waveform BSD that drives the piezoelectric element 60 included in the ejection section 600[1] so that ink is not ejected from the ejection section 600[1], and a drive signal VOUT[1] including a drive waveform NVT for inspecting the state of the ejection section 600[1].

[0066] As described above, the drive signal output circuit 200 of this embodiment generates a drive signal VOUT including any one of a drive waveform DEP for ejecting ink from the ejection unit 600, a drive waveform BSD for causing slight vibrations to the extent that ink is not ejected from the ejection unit 600, a drive waveform NVT for determining the state of the ejection unit 600, and a drive waveform ND for not driving the piezoelectric element 60 included in the ejection unit 600, and outputs the drive signal VOUT to the corresponding ejection unit 600. Note that the signal waveform of the drive signal VOUT shown in FIG. 6 is an example and is not limited to this. Furthermore, the drive signal output circuit 200 may output multiple types of drive waveforms DEP for ejecting ink from the ejection unit 600.

[0067] 1.4.4 Configuration of waveform selection control circuit Next, we will explain the configuration of the waveform selection control circuit 210. Figure 7 is a diagram showing an example of the configuration of the waveform selection control circuit 210. In addition to the configuration of the waveform selection control circuit 210, Figure 7 also shows output circuits 250[1] to 250[n] to which voltage selection signals S[1] to S[n] output by the waveform selection control circuit 210 are input, and ejection units 600[1] to 600[n].

[0068] 7, the waveform selection control circuit 210 receives a clock signal SCK, a print data signal SI, a latch signal LAT, change signals CHA, CHB, CHC, CHD, and a waveform information signal WI. The waveform selection control circuit 210 also includes a set of a register 212, a latch circuit 214, and a decoder 216, each of which corresponds to one of the ejection units 600[1] to 600[n]. In other words, the waveform selection control circuit 210 includes the same number of sets of registers 212, latch circuits 214, and decoders 216 as the number of n ejection units 600.

[0069] The print data signal SI is a signal synchronized with the clock signal SCK and includes serially 2-bit print data [SIH, SIL] for selecting the signal waveform included in the drive signal VOUT output to each of the n ejection units 600 from the drive waveforms DEP, BSD, NVT, and ND. In other words, the print data signal SI includes at least a 2n-bit signal. The print data [SIH, SIL] included in the print data signal SI corresponds to the n ejection units 600 and is held in the register 212.

[0070] Specifically, in the waveform selection control circuit 210, the registers 212 are cascaded to one another to form an n-stage shift register. The print data [SIH, SIL] input serially as the print data signal SI is transferred sequentially to the subsequent register 212 in accordance with the clock signal SCK. When the supply of the clock signal SCK stops, the print data [SIH, SIL] corresponding to each of the n ejection units 600 is held in the register 212 corresponding to each of the n ejection units 600. In the following description, in order to distinguish between the n registers 212 that form the shift register, they may be referred to as stage 1, stage 2, ..., stage n, in order from the upstream side to the downstream side along which the print data signal SI is propagated.

[0071] Each of the n latch circuits 214 is provided corresponding to one of the n registers 212. Each of the latch circuits 214 simultaneously latches the print data [SIH, SIL] held in each of the n registers 212 at the rising edge of the latch signal LAT. Each of the n latch circuits 214 then outputs the latched signal to the corresponding decoder 216 as latch signals LS[1], LS[2], ..., LS[n]. In the following description, the signal latched by one of the n latch circuits 214 may be referred to as the latch signal LS, i.e., the latch signals LS[1], LS[2], ..., LS[n].

[0072] In addition to the latch signal LS latched by the latch circuit 214, the decoder 216 also receives the latch signal LAT, the change signals CHA, CHB, CHC, and CHD, and the waveform information signal WI. The decoder 216 decodes the print data [SIH, SIL] included in the input latch signal LS based on the waveform information signal WI, thereby generating a voltage selection signal S of a predetermined logic level for each of the periods pa1-pap, pb1-pbq, pc1-pcr, and pd1-pds defined by the latch signal LAT and the change signals CHA, CHB, CHC, and CHD, and outputs the voltage selection signal S to the output circuit 250. At this time, the decoder 216 outputs a voltage selection signal S whose L level is ground potential and whose H level is level-shifted to voltage Vh3 or a voltage value greater than voltage Vh3.

[0073] 1.4.5 Output circuit configuration Next, a description will be given of the configuration of output circuit 250 to which voltage selection signal S output by waveform selection control circuit 210 is input. Fig. 8 is a diagram showing an example of the configuration of output circuit 250. As shown in Fig. 8, output circuit 250 has output switching circuits 252-1 to 252-7.

[0074] The output switching circuit 252-1 includes a switch sw1a and a constant current circuit ci1. A voltage selection signal S1 as a voltage selection signal S and a drive voltage signal VHV3 are input to the output switching circuit 252-1. The voltage selection signal S1 is input to a control terminal of the switch sw1a. The drive voltage signal VHV3 is input to one terminal of the switch sw1a. The other terminal of the switch sw1a is electrically connected to the input terminal of the constant current circuit ci1.

[0075] When an H-level voltage selection signal S1 is input to the control terminal of the switch sw1a, the switch sw1a is controlled so that one terminal and the other terminal are conductive. As a result, a drive voltage signal VHV3 is supplied to the input terminal of the constant current circuit ci1. This causes the constant current circuit ci1 to output from its output terminal a signal with a constant current value based on the voltage Vh3, which is the voltage value of the drive voltage signal VHV3 supplied to its input terminal, and the voltage value of its output terminal. Here, the switch sw1a and the constant current circuit ci1 may be formed as separate circuit elements or may be formed as a single circuit element.

[0076] The output switching circuit 252-2 includes switches sw2a and sw2b and constant current circuits ci2 and co2. The output switching circuit 252-2 receives voltage selection signals S2a and S2b as the voltage selection signal S, and a drive voltage signal VHV2. The voltage selection signal S2a is input to a control terminal of the switch sw2a. The voltage selection signal S2b is input to a control terminal of the switch sw2b. The drive voltage signal VHV2 is input to one terminal of the switch sw2a and one terminal of the switch sw2b. The other terminal of the switch sw2a is electrically connected to the input terminal of the constant current circuit ci2. The other terminal of the switch sw2b is electrically connected to the output terminal of the constant current circuit co2.

[0077] When a high-level voltage selection signal S2a is input to the control terminal of the switch ws2a, the switch sw2a is controlled so that one terminal and the other terminal are conductive. As a result, a drive voltage signal VHV2 is supplied to the input terminal of the constant current circuit ci2. As a result, the constant current circuit ci2 outputs a signal with a constant current value from its output terminal based on the voltage value of the output terminal and the voltage Vh2, which is the voltage value of the drive voltage signal VHV2 supplied to its input terminal. When a high-level voltage selection signal S2b is input to the control terminal of the switch ws2b, the switch sw2b is controlled so that one terminal and the other terminal are conductive. As a result, the drive voltage signal VHV2 is supplied to the output terminal of the constant current circuit co2. As a result, the constant current circuit co2 outputs a signal with a constant current value from its output terminal based on the voltage value of the input terminal and the voltage Vh2 supplied to its output terminal. Here, the switch sw2a and the constant current circuit ci2 may be configured as separate circuit elements or as a single circuit element. Similarly, the switch sw2b and the constant current circuit co2 may be configured as separate circuit elements, or may be configured as a single circuit element.

[0078] The output switching circuit 252-3 includes switches sw3a and sw3b and constant current circuits ci3 and co3. The output switching circuit 252-3 receives voltage selection signals S3a and S3b as the voltage selection signal S, and a drive voltage signal VHV1. The voltage selection signal S3a is input to a control terminal of the switch sw3a. The voltage selection signal S3b is input to a control terminal of the switch sw3b. The drive voltage signal VHV1 is input to one terminal of the switch sw3a and one terminal of the switch sw3b. The other terminal of the switch sw3a is electrically connected to the input terminal of the constant current circuit ci3. The other terminal of the switch sw3b is electrically connected to the output terminal of the constant current circuit co3.

[0079] When a high-level voltage selection signal S3a is input to the control terminal of the switch ws3a, the switch sw3a is controlled so that one terminal and the other terminal are conductive. As a result, a drive voltage signal VHV1 is supplied to the input terminal of the constant current circuit ci3. As a result, the constant current circuit ci3 outputs a signal with a constant current value from its output terminal based on the voltage Vh1, which is the voltage value of the drive voltage signal VHV1 supplied to its input terminal, and the voltage value of its output terminal. When a high-level voltage selection signal S3b is input to the control terminal of the switch ws3b, the switch sw3b is controlled so that one terminal and the other terminal are conductive. As a result, the drive voltage signal VHV1 is supplied to the output terminal of the constant current circuit co3. As a result, the constant current circuit co3 outputs a signal with a constant current value from its output terminal based on the voltage value of its input terminal and the voltage Vh1 supplied to its output terminal. Here, the switch sw3a and the constant current circuit ci3 may be configured as separate circuit elements or as a single circuit element. Similarly, the switch sw3b and the constant current circuit co3 may be configured as separate circuit elements, or may be configured as a single circuit element.

[0080] The output switching circuit 252-4 includes switches sw4a and sw4b and constant current circuits ci4 and co4. The output switching circuit 252-4 receives voltage selection signals S4a and S4b as the voltage selection signal S, and a drive voltage signal VCV. The voltage selection signal S4a is input to a control terminal of the switch sw4a. The voltage selection signal S4b is input to a control terminal of the switch sw4b. The drive voltage signal VCV is input to one terminal of the switch sw4a and one terminal of the switch sw4b. The other terminal of the switch sw4a is electrically connected to the input terminal of the constant current circuit ci4. The other terminal of the switch sw4b is electrically connected to the output terminal of the constant current circuit co4.

[0081] When a high-level voltage selection signal S4a is input to the control terminal of the switch ws4a, the switch sw4a is controlled to have one terminal and the other terminal conductive. As a result, a drive voltage signal VCV is supplied to the input terminal of the constant current circuit ci4. As a result, the constant current circuit ci4 outputs a signal with a constant current value from its output terminal based on the voltage Vc, which is the voltage value of the drive voltage signal VCV supplied to its input terminal, and the voltage value at its output terminal. When a high-level voltage selection signal S4b is input to the control terminal of the switch ws4b, the switch sw4b is controlled to have one terminal and the other terminal conductive. As a result, a drive voltage signal VCV is supplied to the output terminal of the constant current circuit co4. As a result, the constant current circuit co4 outputs a signal with a constant current value from its output terminal based on the voltage value at its input terminal and the voltage Vc supplied to its output terminal. Here, the switch sw4a and the constant current circuit ci4 may be configured as separate circuit elements or as a single circuit element. Similarly, the switch sw4b and the constant current circuit co4 may be configured as separate circuit elements, or may be configured as a single circuit element.

[0082] The output switching circuit 252-5 includes switches sw5a and sw5b and constant current circuits ci5 and co5. The output switching circuit 252-5 receives voltage selection signals S5a and S5b as the voltage selection signal S, and a drive voltage signal VBV1. The voltage selection signal S5a is input to a control terminal of the switch sw5a. The voltage selection signal S5b is input to a control terminal of the switch sw5b. The drive voltage signal VBV1 is input to one terminal of the switch sw5a and one terminal of the switch sw5b. The other terminal of the switch sw5a is electrically connected to the input terminal of the constant current circuit ci5. The other terminal of the switch sw5b is electrically connected to the output terminal of the constant current circuit co5.

[0083] When a high-level voltage selection signal S5a is input to the control terminal of the switch ws5a, the switch sw5a is controlled to have one terminal and the other terminal conductive. As a result, a drive voltage signal VBV1 is supplied to the input terminal of the constant current circuit ci5. As a result, the constant current circuit ci5 outputs a signal with a constant current value from its output terminal based on the voltage Vb1, which is the voltage value of the drive voltage signal VBV1 supplied to its input terminal, and the voltage value of its output terminal. When a high-level voltage selection signal S5b is input to the control terminal of the switch ws5b, the switch sw5b is controlled to have one terminal and the other terminal conductive. As a result, the drive voltage signal VBV1 is supplied to the output terminal of the constant current circuit co5. As a result, the constant current circuit co5 outputs a signal with a constant current value from its output terminal based on the voltage value of its input terminal and the voltage Vb1 supplied to its output terminal. Here, the switch sw5a and the constant current circuit ci5 may be configured as separate circuit elements or as a single circuit element. Similarly, the switch sw5b and the constant current circuit co5 may be configured as separate circuit elements, or may be configured as a single circuit element.

[0084] The output switching circuit 252-6 includes switches sw6a and sw6b and constant current circuits ci6 and co6. The output switching circuit 252-6 receives voltage selection signals S6a and S6b as the voltage selection signal S, and a drive voltage signal VBV2. The voltage selection signal S6a is input to a control terminal of the switch sw6a. The voltage selection signal S6b is input to a control terminal of the switch sw6b. The drive voltage signal VBV2 is input to one terminal of the switch sw6a and one terminal of the switch sw6b. The other terminal of the switch sw6a is electrically connected to the input terminal of the constant current circuit ci6. The other terminal of the switch sw6b is electrically connected to the output terminal of the constant current circuit co6.

[0085] When a high-level voltage selection signal S6a is input to the control terminal of the switch ws6a, the switch sw6a is controlled to have one terminal and the other terminal conductive. As a result, a drive voltage signal VBV2 is supplied to the input terminal of the constant current circuit ci6. As a result, the constant current circuit ci6 outputs a signal with a constant current value from its output terminal based on the voltage Vb2, which is the voltage value of the drive voltage signal VBV2 supplied to its input terminal, and the voltage value of its output terminal. When a high-level voltage selection signal S6b is input to the control terminal of the switch ws6b, the switch sw6b is controlled to have one terminal and the other terminal conductive. As a result, the drive voltage signal VBV2 is supplied to the output terminal of the constant current circuit co6. As a result, the constant current circuit co6 outputs a signal with a constant current value from its output terminal based on the voltage value of its input terminal and the voltage Vb2 supplied to its output terminal. Here, the switch sw6a and the constant current circuit ci6 may be formed as separate circuit elements or as a single circuit element. Similarly, the switch sw6b and the constant current circuit co6 may be configured as separate circuit elements, or may be configured as a single circuit element.

[0086] The output switching circuit 252-7 includes a switch sw7b and a constant current circuit co7. A voltage selection signal S7 as the voltage selection signal S and a drive voltage signal VBV3 are input to the output switching circuit 252-7. The voltage selection signal S7 is input to a control terminal of the switch sw7b. The drive voltage signal VBV3 is input to one terminal of the switch sw7b. The other terminal of the switch sw7b is electrically connected to the output terminal of the constant current circuit co7.

[0087] When a high-level voltage selection signal S7 is input to the control terminal of switch ws7b, switch sw7b is controlled to have one terminal and the other terminal conductive. As a result, the drive voltage signal VBV3 is supplied to the output terminal of the constant current circuit co7. This causes the constant current circuit co7 to output a signal with a constant current value based on the voltage value of the input terminal and the voltage Vb3, which is the voltage value of the drive voltage signal VBV3 supplied to the output terminal. Here, switch sw7b and constant current circuit co7 may be formed as separate circuit elements or may be formed as a single circuit element.

[0088] The outputs of the output switching circuits 252-1 to 252-7 are connected in common. The output circuit 250 outputs the signals generated at the outputs of the commonly connected output switching circuits 252-1 to 252-7 as the drive signal VOUT.

[0089] As described above, the output circuit 250 generates the drive signal VOUT by switching whether or not each of the output switching circuits 252-1 to 252-7 outputs the input drive voltage signals VHV1, VHV2, VHV3, VCV, VBV1, VBV2, and VBV3 based on the logic level of the corresponding voltage selection signal S, and outputs the drive signal VOUT to the corresponding discharge unit 600. That is, the constant current circuits ci1, ci2, ci3, ci4, ci5, and ci6 output currents based on the voltage values ​​of the drive voltage signals VHV3, VHV2, VHV1, VCV, VBV1, and VBV2 and the voltage value of the drive signal VOUT to the discharge unit 600. Such constant current circuits ci1, ci2, ci3, ci4, ci5, and ci6 can be configured to include, for example, P-channel field effect transistors (FETs). Furthermore, the constant current circuits co2, co3, co4, co5, co6, and co7 draw currents based on the voltage value of the drive signal VOUT and the voltage values ​​of the drive voltage signals VHV3, VHV2, VHV1, VCV, VBV1, and VBV2 from the discharge unit 600. Such constant current circuits co2, co3, co4, co5, co6, and co7 can be configured to include, for example, N-channel FETs (Field Effect Transistors).

[0090] That is, output switching circuit 252-1 includes a P-channel FET, output switching circuits 252-2 to 252-6 include P-channel FETs and N-channel FETs, and output switching circuit 252-7 includes an N-channel FET.

[0091] As described above, the drive signal output circuit 200 includes the output switching circuit 252-1 that outputs a signal of a constant current value based on the drive voltage signal VHV3, the output switching circuit 252-2 that outputs a signal of a constant current value based on the drive voltage signal VHV2, the output switching circuit 252-3 that outputs a signal of a constant current value based on the drive voltage signal VHV1, the output switching circuit 252-4 that outputs a signal of a constant current value based on the drive voltage signal VCV, the output switching circuit 252-5 that outputs a signal of a constant current value based on the drive voltage signal VBV1, the output switching circuit 252-6 that outputs a signal of a constant current value based on the drive voltage signal VBV2, and the output switching circuit 252-7 that outputs a signal of a constant current value based on the drive voltage signal VBV3.

[0092] Based on the print data signal SI, the waveform selection control circuit 210 controls whether or not the output switching circuit 252-1 outputs a signal of a constant current value based on the drive voltage signal VHV3, whether or not the output switching circuit 252-2 outputs a signal of a constant current value based on the drive voltage signal VHV2, whether or not the output switching circuit 252-3 outputs a signal of a constant current value based on the drive voltage signal VHV1, whether or not the output switching circuit 252-4 outputs a signal of a constant current value based on the drive voltage signal VCV, whether or not the output switching circuit 252-5 outputs a signal of a constant current value based on the drive voltage signal VBV1, whether or not the output switching circuit 252-6 outputs a signal of a constant current value based on the drive voltage signal VBV2, and whether or not the output switching circuit 252-7 outputs a signal of a constant current value based on the drive voltage signal VBV3. In other words, the waveform selection control circuit 210 acquires the waveform information signal WI and controls the output switching circuits 252-1 to 252-7 based on the acquired waveform information signal WI and the print data signal SI.

[0093] As a result, the output switching circuit 252-1 selects or deselects the drive voltage signal VHV3 to switch whether to output a signal of a constant current value based on the drive voltage signal VHV3, the output switching circuit 252-2 selects or deselects the drive voltage signal VHV2 to switch whether to output a signal of a constant current value based on the drive voltage signal VHV2, the output switching circuit 252-3 selects or deselects the drive voltage signal VHV3 to switch whether to output a signal of a constant current value based on the drive voltage signal VHV3, and the output switching circuit 252-4 selects or deselects the drive voltage signal VCV. The output switching circuit 252-5 switches whether to output a signal of a constant current value based on the drive voltage signal VBV1 by selecting or deselecting the drive voltage signal VBV1, the output switching circuit 252-6 switches whether to output a signal of a constant current value based on the drive voltage signal VBV2 by selecting or deselecting the drive voltage signal VBV2, and the output switching circuit 252-7 switches whether to output a signal of a constant current value based on the drive voltage signal VBV3 by selecting or deselecting the drive voltage signal VBV3.

[0094] As a result, the drive signal output circuit 200 outputs drive signals VOUT[1] to VOUT[n] corresponding to a signal of a constant current value based on the drive voltage signal VHV3, a signal of a constant current value based on the drive voltage signal VHV2, a signal of a constant current value based on the drive voltage signal VHV1, a signal of a constant current value based on the drive voltage signal VCV, a signal of a constant current value based on the drive voltage signal VBV1, a signal of a constant current value based on the drive voltage signal VBV2, and a signal of a constant current value based on the drive voltage signal VBV3.

[0095] Here, the output switching circuit 252-1, which switches whether to output a signal based on the drive voltage signal VHV3 with the largest voltage value among the drive voltage signals VHV1, VHV2, VHV3, VCV, VBV1, VBV2, and VBV3, may include a circuit that outputs a signal with a constant current value from the output terminal based on the voltage value of the input terminal and the voltage Vh3 supplied to the output terminal, in addition to the constant current circuit ci1 that outputs a signal with a constant current value from the output terminal based on the voltage value of the input terminal and the voltage Vh3 supplied to the output terminal. Furthermore, output switching circuit 252-7, which switches whether to output a signal based on drive voltage signal VBV3, which has the smallest voltage value among drive voltage signals VHV1, VHV2, VHV3, VCV, VBV1, VBV2, and VBV3, may include a circuit that outputs from its output terminal a signal with a constant current value based on voltage Vb3 supplied to its input terminal and the voltage value at its output terminal, in addition to constant current circuit co7 that outputs from its output terminal a signal with a constant current value based on the voltage value at its input terminal and voltage Vb3 supplied to its output terminal. This allows output switching circuits 252-1 to 252-7 to all have the same configuration, thereby reducing the manufacturing cost of semiconductor device 410 including output switching circuits 252-1 to 252-7.

[0096] 1.4.6 Operation of the drive signal output circuit The operation of the drive signal output circuit 200 will now be described. FIG. 9 is a diagram illustrating the operation of the drive signal output circuit 200. The print data [SIH, SIL] included in the print data signal SI is input serially to the drive signal output circuit 200 in synchronization with the clock signal SCK. The print data [SIH, SIL] input to the drive signal output circuit 200 is sequentially transferred by the registers 212 corresponding to the ejectors 600[1] to 600[n] in synchronization with the clock signal SCK. Thereafter, the supply of the clock signal SCK is stopped, and the registers 212 hold the print data [SIH, SIL] corresponding to each of the ejectors 600[1] to 600[n]. Note that in the first embodiment, the print data [SIH, SIL] included in the print data signal SI is input in the order corresponding to the ejector 600[n], ejector 600[n-1], ..., ejector 600[2], and ejector 600[1].

[0097] Thereafter, when the latch signal LAT rises, the latch circuits 214 simultaneously latch the print data [SIH, SIL] held in the register 212 as a latch signal LS. The latch circuits 214 then input the latch signal LS, which includes the latched print data [SIH, SIL], to the corresponding decoder 216. Each decoder 216 decodes the input latch signal LS based on the waveform information signal WI input from the waveform information storage circuit 230, to generate a voltage selection signal S and output it to the output circuit 250.

[0098] Specifically, the latch circuit 214 corresponding to the ejection unit 600[1] latches the print data [SIH, SIL] held in the register 212 corresponding to the ejection unit 600[1] as a latch signal LS[1] and inputs the latched latch signal LS[1] to the decoder 216 corresponding to the ejection unit 600[1]. The decoder 216 corresponding to the ejection unit 600[1] decodes the latch signal LS[1] based on the waveform information signal WI input from the waveform information storage circuit 230 to generate voltage selection signals S1, S2a, S2b, S3a, S3b, S4a, S4b, S5a, S5b, S6a, S6b, and S7 as the voltage selection signal S[1] and outputs them to the output circuit 250[1].

[0099] Similarly, the latch circuit 214 corresponding to the ejection unit 600[j] latches the print data [SIH, SIL] held in the register 212 corresponding to the ejection unit 600[j] as a latch signal LS[j] and inputs the latched latch signal LS[j] to the decoder 216 corresponding to the ejection unit 600[j]. The decoder 216 corresponding to the ejection unit 600[j] decodes the latch signal LS[j] based on the waveform information signal WI input from the waveform information storage circuit 230 to generate voltage selection signals S1, S2a, S2b, S3a, S3b, S4a, S4b, S5a, S5b, S6a, S6b, and S7 as the voltage selection signal S[j] and outputs them to the output circuit 250[j].

[0100] Next, a specific example of the decoded content in the decoder 216 will be described. Here, the drive signal output circuit 200 of the liquid ejection device 1 of the first embodiment will be described as follows: when the print data is [SIH,SIL]=[1,1], it outputs a drive signal VOUT including a drive waveform DEP to the corresponding ejection unit 600; when the print data is [SIH,SIL]=[1,0], it outputs a drive signal VOUT including a drive waveform BSD to the corresponding ejection unit 600; when the print data is [SIH,SIL]=[0,1], it outputs a drive signal VOUT including a drive waveform NVT to the corresponding ejection unit 600; and when the print data is [SIH,SIL]=[0,0], it outputs a drive signal VOUT including a drive waveform ND to the corresponding ejection unit 600.

[0101] 10 is a diagram showing an example of the operation of the decoder 216 and the signal waveform of the drive signal VOUT when print data [SIH, SIL]=[1,1] is input. As shown in Fig. 10, when a latch signal LS including print data [SIH, SIL]=[1,1] is input, the decoder 216 generates voltage selection signals S1, S2a, S2b, S3a, S3b, S4a, S4b, S5a, S5b, S6a, S6b, and S7 as voltage selection signals S of predetermined logic levels during each of periods pa1 to pa4 defined by the latch signal LAT and the change signal CHA, and outputs these to the output circuit 250.

[0102] Specifically, the period pa1 begins when the latch signal LAT rises. During the period pa1, the decoder 216 sets the logic level of the voltage selection signal S4b it outputs to an H level and the other to an L level. That is, during the period pa1, one end and the other end of the switch sw4b in the output switching circuit 252-4 are controlled to be conductive. As a result, the output circuit 250 outputs a drive signal VOUT whose voltage value is constant at voltage Vc. Note that during the period pa1, the decoder 216 may set the logic level of the voltage selection signal S4a it outputs to an H level and the other to an L level. That is, during the period pa1, one end and the other end of the switch sw4a in the output switching circuit 252-4 may be controlled to be conductive.

[0103] After the latch signal LAT rises, the change signal CHA rises, starting the period pa2. During the period pa2, the decoder 216 sets the logic level of the voltage selection signal S7 it outputs to a high level and the other to a low level. That is, during the period pa2, the switch sw4b of the output switching circuit 252-4 is controlled so that one end and the other end are non-conductive, and the switch sw7b of the output switching circuit 252-7 is controlled so that one end and the other end are conductive. Therefore, the constant current circuit co7 outputs a signal with a constant current value based on the potential difference between the voltage value of the drive signal VOUT supplied to its input terminal and the voltage Vb3 supplied to its output terminal. In other words, the output switching circuit 252-7 draws a signal with a constant current value based on the potential difference between the voltage value of the drive signal VOUT and the voltage Vb3. As a result, the output circuit 250 outputs a drive signal VOUT whose voltage value decreases from voltage Vc to voltage Vb3. When the voltage of the drive signal VOUT supplied to the input terminal of the constant current circuit co7 becomes Vb3, the constant current circuit co7 stops outputting the signal with a constant current value, and the voltage of the drive signal VOUT output by the output circuit 250 becomes constant at Vb3.

[0104] Next, the change signal CHA rises, starting the period pa3. During the period pa3, the decoder 216 sets the logic level of the voltage selection signal S1 it outputs to a high level and the other to a low level. That is, during the period pa3, the switch sw7b of the output switching circuit 252-7 is controlled so that one end and the other end are non-conductive, and the switch sw1a of the output switching circuit 252-1 is controlled so that one end and the other end are conductive. Therefore, the constant current circuit ci1 outputs a signal with a constant current value based on the potential difference between the signal with a voltage value of Vh3 supplied to its input terminal and the voltage value of the drive signal VOUT supplied to its output terminal. In other words, the output switching circuit 252-1 outputs a signal with a constant current value based on the potential difference between the voltage Vh3 and the voltage value of the drive signal VOUT. As a result, the output circuit 250 outputs the drive signal VOUT whose voltage value increases from voltage Vb3 to voltage Vh3. When the voltage of the drive signal VOUT supplied to the output terminal of the constant current circuit ci1 becomes Vh3, the constant current circuit ci1 stops outputting the signal with a constant current value, and the voltage of the drive signal VOUT output by the output circuit 250 becomes constant at Vh3.

[0105] Next, the change signal CHA rises, starting period pa4. During period pa4, the decoder 216 sets the logic level of the voltage selection signal S4b it outputs to a high level and the other to a low level. That is, during period pa4, the switch sw1a in the output switching circuit 252-1 is controlled so that one end and the other end are non-conductive, and the switch sw4b in the output switching circuit 252-4 is controlled so that one end and the other end are conductive. Therefore, the constant current circuit co4 outputs a signal with a constant current value based on the potential difference between the voltage value of the drive signal VOUT supplied to its input terminal and the signal with a voltage Vc supplied to its output terminal. In other words, the output switching circuit 252-4 draws a signal with a constant current value based on the potential difference between the voltage value of the drive signal VOUT and voltage Vc. As a result, the output circuit 250 outputs a drive signal VOUT whose voltage value decreases from voltage Vh3 toward voltage Vc. When the voltage of the drive signal VOUT supplied to the input terminal of the constant current circuit co4 becomes Vc, the constant current circuit co4 stops outputting the signal with a constant current value. As a result, the voltage of the drive signal VOUT output by the output circuit 250 becomes constant at Vc.

[0106] Thereafter, the latch signal LAT rises, ending the dot formation cycle cd. As a result, when print data [SIH, SIL]=[1,1] is input, the drive signal output circuit 200 generates a drive signal VOUT including the drive waveform DEP shown in FIG. 6 during the dot formation cycle cd and outputs it to the corresponding discharge section 600. Here, as shown in FIG. 10, the timing at which the change signal CHA that defines the end of period pa1 rises corresponds to time ta1 shown in FIG. 6, the timing at which the change signal CHA that defines the end of period pa2 rises corresponds to time ta2 shown in FIG. 6, and the timing at which the change signal CHA that defines the end of period pa3 rises corresponds to time ta3 shown in FIG. 6.

[0107] 11 is a diagram showing an example of the operation of the decoder 216 and the signal waveform of the drive signal VOUT when print data [SIH, SIL]=[1, 0] is input. As shown in Fig. 11, when a latch signal LS including print data [SIH, SIL]=[1, 0] is input, the decoder 216 generates voltage selection signals S1, S2a, S2b, S3a, S3b, S4a, S4b, S5a, S5b, S6a, S6b, and S7 as voltage selection signals S of predetermined logic levels during each of periods pb1 to pb3 defined by the latch signal LAT and the change signal CHB, and outputs these to the output circuit 250.

[0108] Specifically, the period pb1 begins when the latch signal LAT rises. During the period pb1, the decoder 216 sets the logic level of the voltage selection signal S4a it outputs to an H level and the other to an L level. That is, during the period pb1, one end and the other end of the switch sw4a in the output switching circuit 252-4 are controlled to be conductive. As a result, the output circuit 250 outputs a drive signal VOUT whose voltage value is constant at voltage Vc. Note that during the period pb1, the decoder 216 may set the logic level of the voltage selection signal S4b it outputs to an H level and the other to an L level. That is, during the period pb1, one end and the other end of the switch sw4b in the output switching circuit 252-4 may be controlled to be conductive.

[0109] After the latch signal LAT rises, the change signal CHB rises, starting the period pb2. During the period pb2, the decoder 216 sets the logic level of the voltage selection signal S5b it outputs to the H level and the other to the L level. That is, during the period pb2, the switch sw4a of the output switching circuit 252-4 is controlled so that one end and the other end are non-conductive, and the switch sw5b of the output switching circuit 252-5 is controlled so that one end and the other end are conductive. Therefore, the constant current circuit co5 outputs a signal with a constant current value based on the potential difference between the voltage value of the drive signal VOUT supplied to its input terminal and the voltage Vb1 supplied to its output terminal. In other words, the output switching circuit 252-5 draws a signal with a constant current value based on the potential difference between the voltage value of the drive signal VOUT and the voltage Vb1. As a result, the output circuit 250 outputs the drive signal VOUT, the voltage value of which decreases from voltage Vc to voltage Vb1. When the voltage of the drive signal VOUT supplied to the input terminal of the constant current circuit co5 becomes Vb1, the constant current circuit co5 stops outputting the signal with a constant current value, and the voltage of the drive signal VOUT output by the output circuit 250 becomes constant at Vb1.

[0110] Then, the next time the change signal CHB rises, period pb3 begins. During period pb3, the decoder 216 sets the logic level of the voltage selection signal S4a it outputs to a high level and the other to a low level. That is, during period pb3, the switch sw5b of the output switching circuit 252-5 is controlled so that one end and the other end are non-conductive, and the switch sw4a of the output switching circuit 252-4 is controlled so that one end and the other end are conductive. Therefore, the constant current circuit ci4 outputs a signal with a constant current value based on the potential difference between the signal with a voltage value of Vb1 supplied to its input terminal and the voltage value of the drive signal VOUT supplied to its output terminal. In other words, the output switching circuit 252-4 outputs a signal with a constant current value based on the potential difference between voltage Vc and the voltage value of the drive signal VOUT. As a result, the output circuit 250 outputs a drive signal VOUT whose voltage value increases from voltage Vb1 to voltage Vc. When the voltage value of the drive signal VOUT supplied to the output terminal of the constant current circuit ci4 becomes voltage Vc, the constant current circuit ci4 stops outputting the signal with a constant current value, and the voltage value of the drive signal VOUT output by the output circuit 250 becomes constant at voltage Vc.

[0111] Thereafter, the latch signal LAT rises, ending the dot formation cycle cd. As a result, when print data [SIH, SIL]=[1, 0] is input, the drive signal output circuit 200 generates a drive signal VOUT including the drive waveform BSD shown in FIG. 6 during the dot formation cycle cd and outputs it to the corresponding discharge section 600. Here, as shown in FIG. 11, the timing at which the change signal CHB that defines the end of period pb1 rises corresponds to time tb1 shown in FIG. 6, and the timing at which the change signal CHB that defines the end of period pb2 rises corresponds to time tb2 shown in FIG. 6.

[0112] 12 is a diagram showing an example of the operation of the decoder 216 and the signal waveform of the drive signal VOUT when print data [SIH, SIL]=[0, 1] is input. As shown in Fig. 12, when a latch signal LS including print data [SIH, SIL]=[0, 1] is input, the decoder 216 generates voltage selection signals S1, S2a, S2b, S3a, S3b, S4a, S4b, S5a, S5b, S6a, S6b, and S7 as voltage selection signals S of predetermined logic levels during each of periods pc1 to pc4 defined by the latch signal LAT and the change signal CHC, and outputs these to the output circuit 250.

[0113] Specifically, the period pc1 begins when the latch signal LAT rises. During the period pc1, the decoder 216 sets the logic level of the voltage selection signal S4a it outputs to an H level and the other to an L level. That is, during the period pc1, one end and the other end of the switch sw4a in the output switching circuit 252-4 are controlled to be conductive. As a result, the output circuit 250 outputs a drive signal VOUT whose voltage value is constant at voltage Vc. Note that during the period pc1, the decoder 216 may set the logic level of the voltage selection signal S4b it outputs to an H level and the other to an L level. That is, during the period pc1, one end and the other end of the switch sw4b in the output switching circuit 252-4 may be controlled to be conductive.

[0114] Then, after the latch signal LAT rises, the change signal CHC rises, starting the period pc2. During the period pc2, the decoder 216 sets the logic level of the voltage selection signal S2a it outputs to the H level and the other to the L level. That is, during the period pa2, the switch sw4a of the output switching circuit 252-4 is controlled so that one end and the other end are non-conductive, and the switch sw2a of the output switching circuit 252-2 is controlled so that one end and the other end are conductive. Therefore, the constant current circuit ci2 outputs a signal with a constant current value based on the potential difference between the voltage Vh2 supplied to the input terminal and the voltage value of the drive signal VOUT supplied to the output terminal. In other words, the output switching circuit 252-2 outputs a signal with a constant current value based on the potential difference between the voltage Vh2 and the voltage value of the drive signal VOUT. As a result, the output circuit 250 outputs the drive signal VOUT whose voltage value increases from voltage Vc to voltage Vh2. When the voltage of the drive signal VOUT supplied to the input terminal of the constant current circuit ci2 becomes Vh2, the constant current circuit ci2 stops outputting the signal with a constant current value, and the voltage of the drive signal VOUT output by the output circuit 250 becomes constant at Vh2.

[0115] The next time the change signal CHC rises, period pc3 begins. During period pc3, the decoder 216 sets the logic level of the voltage selection signal S6b it outputs to a high level and the other to a low level. That is, during period pc3, the switch sw2a in the output switching circuit 252-2 is controlled so that one end and the other end are non-conductive, and the switch sw6b in the output switching circuit 252-6 is controlled so that one end and the other end are conductive. Therefore, the constant current circuit co6 outputs a signal with a constant current value based on the potential difference between the voltage value of the drive signal VOUT supplied to its input terminal and the voltage Vb2 supplied to its output terminal. In other words, the output switching circuit 252-6 draws a signal with a constant current value based on the potential difference between the voltage value of the drive signal VOUT and the voltage Vb2. As a result, the output circuit 250 outputs a drive signal VOUT whose voltage value decreases from voltage Vh2 to voltage Vb2. When the voltage of the drive signal VOUT supplied to the output terminal of the constant current circuit co6 becomes Vb2, the constant current circuit co6 stops outputting the signal with a constant current value, and the voltage of the drive signal VOUT output by the output circuit 250 becomes constant at Vb2.

[0116] Then, the next rising edge of the change signal CHC initiates period pc4. During period pc4, the decoder 216 sets the logic level of the voltage selection signal S4a it outputs to a high level and the other to a low level. That is, during period pc4, the switch sw6b of the output switching circuit 252-6 is controlled so that one end and the other end are non-conductive, and the switch sw4a of the output switching circuit 252-4 is controlled so that one end and the other end are conductive. Therefore, the constant current circuit ci4 outputs a signal with a constant current value based on the potential difference between the voltage Vc supplied to its input terminal and the voltage of the drive signal VOUT supplied to its output terminal. In other words, the output switching circuit 252-4 outputs a signal with a constant current value based on the potential difference between the voltage Vb2 and the voltage of the drive signal VOUT. As a result, the output circuit 250 outputs a drive signal VOUT whose voltage value increases from voltage Vb2 to voltage Vc. When the voltage value of the drive signal VOUT supplied to the output terminal of the constant current circuit ci4 becomes voltage Vc, the constant current circuit ci4 stops outputting the signal with a constant current value. As a result, the voltage value of the drive signal VOUT output by the output circuit 250 becomes constant at voltage Vc.

[0117] Thereafter, the latch signal LAT rises, ending the dot formation cycle cd. As a result, when print data [SIH, SIL]=[0, 1] is input, the drive signal output circuit 200 generates a drive signal VOUT including the drive waveform NVT shown in FIG. 6 during the dot formation cycle cd and outputs it to the corresponding discharge section 600. Here, as shown in FIG. 12, the timing at which the change signal CHC that defines the end of period pc1 rises corresponds to time tc1 shown in FIG. 6, the timing at which the change signal CHC that defines the end of period pc2 rises corresponds to time tc2 shown in FIG. 6, and the timing at which the change signal CHC that defines the end of period pc3 rises corresponds to time tc3 shown in FIG. 6.

[0118] 13 is a diagram showing an example of the operation of the decoder 216 and the signal waveform of the drive signal VOUT when print data [SIH,SIL]=[0,0] is input. As shown in Fig. 13, when a latch signal LS including print data [SIH,SIL]=[0,0] is input, the decoder 216 generates voltage selection signals S1, S2a, S2b, S3a, S3b, S4a, S4b, S5a, S5b, S6a, S6b, and S7 as voltage selection signals S of predetermined logic levels during a period pd1 defined by the latch signal LAT and the change signal CHD, and outputs these to the output circuit 250.

[0119] Specifically, the period pd1 begins when the latch signal LAT rises. During the period pd1, the decoder 216 sets the logic level of the voltage selection signal S4a it outputs to an H level and the other to an L level. That is, during the period pd1, one end and the other end of the switch sw4a in the output switching circuit 252-4 are controlled to be conductive. As a result, the output circuit 250 outputs a drive signal VOUT whose voltage value is constant at voltage Vc. Note that during the period pd1, the decoder 216 may set the logic level of the voltage selection signal S4b it outputs to an H level and the other to an L level. That is, during the period pd1, one end and the other end of the switch sw4b in the output switching circuit 252-4 may be controlled to be conductive.

[0120] After that, the latch signal LAT rises, ending the dot formation cycle cd. As a result, when print data [SIH, SIL]=[0,0] is input, the drive signal output circuit 200 generates a drive signal VOUT including a drive waveform ND during the dot formation cycle cd and outputs it to the corresponding ejection section 600.

[0121] As described above, the drive signal output circuit 200 of the first embodiment selects or deselects each of the drive voltage signals VHV1, VHV2, VHV3, VCV, VBV1, VBV2, and VBV3 as the drive voltage signal VDRV based on the latch signal LAT, change signal CH, clock signal SCK, print data signal SI, and waveform selection signal WS, thereby generating a drive signal VOUT according to the voltage values ​​of the drive waveforms DEP, BSD, NVT, and ND, and outputs it to the corresponding ejection section 600.

[0122] 1.5 Effects In the liquid ejection device 1 and head unit 20 of the first embodiment configured as described above, the drive signal output circuit 200 includes an output switching circuit 252-1 that outputs a signal of a constant current value based on a drive voltage signal VHV3 having a voltage value of voltage Vh3, an output switching circuit 252-2 that outputs a signal of a constant current value based on a drive voltage signal VHV2 having a voltage value of voltage Vh2, an output switching circuit 252-3 that outputs a signal of a constant current value based on a drive voltage signal VHV1 having a voltage value of voltage Vh1, and an output switching circuit 252-4 that outputs a signal of a constant current value based on a drive voltage signal VCV having a voltage value of voltage Vc. The output switching circuit 252-4 outputs a signal of a current value, an output switching circuit 252-5 outputs a signal of a constant current value based on a drive voltage signal VBV1 having a voltage value of voltage Vb1, an output switching circuit 252-6 outputs a signal of a constant current value based on a drive voltage signal VBV2 having a voltage value of voltage Vb2, an output switching circuit 252-7 outputs a signal of a constant current value based on a drive voltage signal VBV3 having a voltage value of voltage Vb3, and a waveform selection control circuit 210 controls the output switching circuits 252-1 to 252-7 based on a print data signal SI.

[0123] The drive signal output circuit 200 outputs a drive signal VOUT that corresponds to a signal of a constant current value based on the drive voltage signal VHV3 output by the output switching circuit 252-1, a signal of a constant current value based on the drive voltage signal VHV2 output by the output switching circuit 252-2, a signal of a constant current value based on the drive voltage signal VHV1 output by the output switching circuit 252-3, a signal of a constant current value based on the drive voltage signal VCV output by the output switching circuit 252-4, a signal of a constant current value based on the drive voltage signal VBV1 output by the output switching circuit 252-5, a signal of a constant current value based on the drive voltage signal VBV2 output by the output switching circuit 252-6, and a signal of a constant current value based on the drive voltage signal VBV3 output by the output switching circuit 252-7.

[0124] That is, the drive signal output circuit 200 generates a drive signal VOUT whose voltage value changes between voltages Vh3, Vh2, Vh1, Vc, Vb1, Vh2, and Vb3 by each of the output switching circuits 252-1 to 252-7 selecting one of the drive voltage signals VHV3, VHV2, VHV1, VCV, VBV1, VBV2, and VHV3, and outputs it to the ejection section 600. As a result, the liquid ejection device 1 and the head unit 20 do not need to use an amplifier circuit such as a class D amplifier or a class AB amplifier for driving the piezoelectric element 60, and the head unit 20 and the liquid ejection device 1 can be made smaller.

[0125] Furthermore, in the liquid ejection device 1 and head unit 20 of the first embodiment, the output switching circuits 252-1 to 252-7 each select one of the ejection section 600 drive voltage signals VHV3, VHV2, VHV1, VCV, VBV1, VBV2, and VHV3, respectively, and the drive signal output circuit 200 outputs a drive signal VOUT whose voltage value varies among voltages Vh3, Vh2, Vh1, Vc, Vb1, Vh2, and Vb3 to each of the ejection sections 600[1] to 600[n]. Therefore, the liquid ejection device 1 and head unit 20 of the first embodiment do not need to use an amplifier circuit such as a class-D amplifier that performs switching operation or a class-AB amplifier through which a large current flows, thereby reducing losses in the liquid ejection device 1 and head unit 20. As a result, power consumption in the liquid ejection device 1 and head unit 20 is reduced.

[0126] Furthermore, the reduction in power consumption in the drive signal output circuit 200 reduces heat generation in the drive signal output circuit 200. This reduces the risk of changes in the characteristics of the ink stored in the print head 21 due to the influence of heat generated by the drive signal output circuit 200. Therefore, in the liquid ejection device 1 and head unit 20 of the first embodiment, the drive signal output circuit 200 that outputs the drive signal VOUT can be disposed near the ejection section 600 on the flexible wiring substrate 400 that transmits various signals to the ejection section 600. As a result, it is possible to shorten the propagation distance over which the drive signal VOUT propagates between the drive signal output circuit 200 and the ejection section 600, reducing the risk of distortion in the signal waveform of the drive signal VOUT due to the influence of the impedance of the propagation path over which the drive signal VOUT propagates. This improves the waveform accuracy of the drive signal VOUT supplied to the ejection section 600, and improves the ejection accuracy of the ink ejected from the ejection section 600.

[0127] Furthermore, by arranging the drive signal output circuit 200, which outputs the drive signal VOUT, near the ejection unit 600, such as the flexible wiring substrate 400, the difference between the propagation distance of the drive signal VOUT[1] output from the drive signal output circuit 200 to the ejection unit 600[1] and the propagation distance of the drive signal VOUT[2] output from the drive signal output circuit 200 to the ejection unit 600[2] is reduced, making these propagation distances approximately equal. This reduces the risk of signal delay between the drive signal VOUT[1] supplied to the ejection unit 600[1] and the drive signal VOUT[2] supplied to the ejection unit 600[2]. As a result, the accuracy of ink ejection from the print head 21, including the ejection units 600[1] and 600[2], is improved.

[0128] Furthermore, in the liquid ejection device 1 and head unit 20 of the first embodiment, the drive signal output circuit 200 outputs a drive signal VOUT corresponding to a signal of a constant current value based on the drive voltage signal VHV3 output by the output switching circuit 252-1, a signal of a constant current value based on the drive voltage signal VHV2 output by the output switching circuit 252-2, a signal of a constant current value based on the drive voltage signal VHV1 output by the output switching circuit 252-3, a signal of a constant current value based on the drive voltage signal VCV output by the output switching circuit 252-4, a signal of a constant current value based on the drive voltage signal VBV1 output by the output switching circuit 252-5, a signal of a constant current value based on the drive voltage signal VBV2 output by the output switching circuit 252-6, and a signal of a constant current value based on the drive voltage signal VBV3 output by the output switching circuit 252-7. In other words, the drive signal VOUT controlled to a constant current value is supplied to the piezoelectric element 60, which is a capacitive load. This reduces the risk that distortion will occur in the signal waveform of the drive signal VOUT due to the capacitive component of the piezoelectric element 60 when the voltage value of the drive signal VOUT changes. Therefore, the waveform accuracy of the drive signal VOUT supplied to the ejection unit 600 is improved, and the ejection accuracy of the ink ejected from the ejection unit 600 is improved.

[0129] 1.6 Variations In the first embodiment of the liquid ejection device 1 described above, the output switching circuit 252-1 of the output circuit 250 has been described as having one pair of a switch sw1a and a constant current circuit ci1 that outputs a signal of a constant current value based on the voltage Vh3, which is the voltage value of the drive voltage signal VHV3, and the voltage value of the drive signal VOUT, to the ejection section 600. However, the output switching circuit 252-1 may have multiple pairs of a switch sw1a and a constant current circuit ci1 that output a signal of a constant current value based on the voltage Vh3 and the voltage value of the drive signal VOUT to the ejection section 600.

[0130] Similarly, the output switching circuit 252-2 may have a plurality of pairs of a switch sw2a and a constant current circuit ci2 that output a signal of a constant current value based on the voltage Vh2 that is the voltage value of the drive voltage signal VHV2 and the voltage value of the drive signal VOUT to the discharge unit 600, the output switching circuit 252-3 may have a plurality of pairs of a switch sw3a and a constant current circuit ci3 that output a signal of a constant current value based on the voltage Vh1 that is the voltage value of the drive voltage signal VHV1 and the voltage value of the drive signal VOUT to the discharge unit 600, and the output switching circuit 252-4 may have a plurality of pairs of a switch sw3a and a constant current circuit ci3 that output a signal of a constant current value based on the voltage Vc that is the voltage value of the drive voltage signal VCV and the voltage value of the drive signal VOUT to the discharge unit 600. The output switching circuit 252-5 may have a plurality of pairs of a switch sw4a and a constant current circuit ci4 that output a signal of a constant current value based on the voltage Vb1 that is the voltage value of the drive voltage signal VBV1 and the voltage value of the drive signal VOUT to the discharge unit 600, and the output switching circuit 252-6 may have a plurality of pairs of a switch sw5a and a constant current circuit ci5 that output a signal of a constant current value based on the voltage Vb2 that is the voltage value of the drive voltage signal VBV2 and the voltage value of the drive signal VOUT to the discharge unit 600.

[0131] Furthermore, in the liquid ejection device 1 of the first embodiment described above, the output switching circuit 252-2 of the output circuit 250 has been described as having one pair of a switch sw2b and a constant current circuit co2 that draws in from the ejection section 600 a signal of a constant current value based on the voltage Vh2, which is the voltage value of the drive voltage signal VHV2, and the voltage value of the drive signal VOUT, but the output switching circuit 252-2 may have multiple pairs of a switch sw2b and a constant current circuit co2 that draw in from the ejection section 600 a current based on the voltage Vh2 and the voltage value of the drive signal VOUT.

[0132] Similarly, the output switching circuit 252-3 may have a plurality of pairs of a switch sw3b and a constant current circuit co3 that draw in from the output unit 600 a signal of a constant current value based on the voltage Vh1 that is the voltage value of the drive voltage signal VHV1 and the voltage value of the drive signal VOUT, the output switching circuit 252-4 may have a plurality of pairs of a switch sw4b and a constant current circuit co4 that draw in from the output unit 600 a signal of a constant current value based on the voltage Vc that is the voltage value of the drive voltage signal VCV and the voltage value of the drive signal VOUT, and the output switching circuit 252-5 may have a plurality of pairs of a switch sw4b and a constant current circuit co4 that draw in from the output unit 600 a signal of a constant current value based on the voltage Vb1 that is the voltage value of the drive voltage signal VBV1 and the voltage value of the drive signal VOUT. The output switching circuit 252-6 may have a plurality of pairs of a switch sw6b and a constant current circuit co6 that draw from the discharge unit 600 a signal of a constant current value based on the voltage Vb2 that is the voltage value of the drive voltage signal VBV2 and the voltage value of the drive signal VOUT, and the output switching circuit 252-7 may have a plurality of pairs of a switch sw7b and a constant current circuit co7 that draw from the discharge unit 600 a signal of a constant current value based on the voltage Vb3 that is the voltage value of the drive voltage signal VBV3 and the voltage value of the drive signal VOUT.

[0133] A specific example of the configuration of the liquid ejection device 1 of the modified example will be described. Fig. 14 is a diagram showing an example of the configuration of the output switching circuit 252-1 of the modified example. As shown in Fig. 14, the output switching circuit 252-1 of the modified example includes switches sw1a-1 to sw1a-4 and constant current circuits ci1-1 to ci1-4. Furthermore, voltage selection signals S1-1, S1-2, S1-3, S1-4 as the voltage selection signal S1, and a drive voltage signal VHV3 are input to the output switching circuit 252-1 of the modified example.

[0134] The voltage selection signal S1-1 is input to the control terminal of the switch sw1a-1. The voltage selection signal S1-2 is input to the control terminal of the switch sw1a-2. The voltage selection signal S1-3 is input to the control terminal of the switch sw1a-3. The voltage selection signal S1-4 is input to the control terminal of the switch sw1a-4. The drive voltage signal VHV3 is input to one terminal of the switches sw1a-1 to sw1a-4. The other terminal of the switch sw1a-1 is electrically connected to the input terminal of the constant current circuit ci1-1. The other terminal of the switch sw1a-2 is electrically connected to the input terminal of the constant current circuit ci1-2. The other terminal of the switch sw1a-3 is electrically connected to the input terminal of the constant current circuit ci1-3. The other terminal of the switch sw1a-4 is electrically connected to the input terminal of the constant current circuit ci1-4.

[0135] In the output switching circuit 252-1 of the modified example configured as described above, when an H-level voltage selection signal S1-1 is input to the control terminal of the switch sw1a-1, one terminal and the other terminal of the switch sw1a-1 are controlled to be conductive. As a result, the drive voltage signal VHV3 is supplied to the input terminal of the constant current circuit ci1-1, and the constant current circuit ci1-1 outputs a signal of a constant current value from the output terminal based on the voltage Vh3 supplied to the input terminal and the voltage value of the output terminal.

[0136] When an H-level voltage selection signal S1-2 is input to the control terminal of the switch sw1a-2, one terminal and the other terminal of the switch sw1a-2 are controlled to be conductive, which supplies the drive voltage signal VHV3 to the input terminal of the constant current circuit ci1-2, and the constant current circuit ci1-2 outputs a signal of a constant current value from its output terminal based on the voltage Vh3 supplied to the input terminal and the voltage value of the output terminal.

[0137] When an H-level voltage selection signal S1-3 is input to the control terminal of the switch sw1a-3, one terminal and the other terminal of the switch sw1a-3 are controlled to be conductive, which supplies a drive voltage signal VHV3 to the input terminal of the constant current circuit ci1-3, and the constant current circuit ci1-3 outputs a signal of a constant current value from its output terminal based on the voltage Vh3 supplied to the input terminal and the voltage value of the output terminal.

[0138] When an H-level voltage selection signal S1-4 is input to the control terminal of the switch sw1a-4, one terminal and the other terminal of the switch sw1a-4 are controlled to be conductive, which supplies the drive voltage signal VHV3 to the input terminal of the constant current circuit ci1-4, and the constant current circuit ci1-4 outputs a signal of a constant current value from its output terminal based on the voltage Vh3 supplied to the input terminal and the voltage value of the output terminal.

[0139] That is, in the output switching circuit 252-1 of the modified example, a set of a switch sw1a-1 and a constant current circuit ci1-1, a set of a switch sw1a-2 and a constant current circuit ci1-2, a set of a switch sw1a-3 and a constant current circuit ci1-3, and a set of a switch sw1a-4 and a constant current circuit ci1-4 are connected in parallel between a wiring pattern to which the drive voltage signal VHV3 is supplied and a wiring pattern to which the drive signal VOUT is output. Then, by individually switching the conduction states of the switches sw1a-1 to sw1a-4 based on the logic levels of the voltage selection signals S1-1 to S1-4, it is possible to switch whether or not the output switching circuit 252-1 of the modified example outputs a signal of a constant current value based on the voltage Vh3 and the voltage value of the output terminal.

[0140] In the following description, the voltage selection signal S1-1 input to the control terminal of switch sw1a-1, the voltage selection signal S1-2 input to the control terminal of switch sw1a-2, the voltage selection signal S1-3 input to the control terminal of switch sw1a-3, and the voltage selection signal S1-4 input to the control terminal of switch sw1a-4 may be collectively referred to as voltage selection signal S1[S1-1, S1-2, S1-3, S1-4].

[0141] When the voltage selection signal S1[S1-1, S1-2, S1-3, S1-4]=[H, L, L, L] is input to the output switching circuit 252-1 of the modified example configured as above, the switch sw1a-1 is controlled so that one end and the other end are conductive, and the switches sw1a-2 to sw1a-4 are controlled so that one end and the other end are non-conductive. At this time, the output switching circuit 252-1 outputs a constant signal to the discharge unit 600 at a current value determined by the constant current circuit ci1-1 based on the voltage Vh3 and the voltage value of the output terminal.

[0142] Furthermore, when the voltage selection signal S1[S1-1, S1-2, S1-3, S1-4]=[H,H,L,L] is input to the output switching circuit 252-1 of the modified example, the switches sw1a-1 and sw1a-2 are controlled so that one end and the other end are conductive, and the switches sw1a-3 and sw1a-4 are controlled so that one end and the other end are non-conductive. At this time, the output switching circuit 252-1 outputs a constant signal to the discharge unit 600 at a current value that is the sum of the current value determined by the constant current circuit ci1-1 and the current value determined by the constant current circuit ci1-2, based on the voltage Vh3 and the voltage value of the output terminal.

[0143] Furthermore, when a voltage selection signal S1[S1-1, S1-2, S1-3, S1-4]=[H,H,H,L] is input to the output switching circuit 252-1 of the modified example, the switches sw1a-1 to sw1a-3 are controlled so that one end and the other end are conductive, and the switch sw1a-4 is controlled so that one end and the other end are non-conductive. At this time, the output switching circuit 252-1 outputs a constant signal to the discharge unit 600 at a current value that is the sum of a current value determined by the constant current circuit ci1-1, a current value determined by the constant current circuit ci1-2, and a current value determined by the constant current circuit ci1-3, based on the voltage Vh3 and the voltage value of the output terminal.

[0144] Furthermore, when a voltage selection signal S1[S1-1, S1-2, S1-3, S1-4]=[H,H,H,H] is input to the output switching circuit 252-1 of the modified example, the switches sw1a-1 to sw1a-4 are controlled so that one end and the other end are conductive. At this time, the output switching circuit 252-1 outputs a constant signal to the discharge unit 600 at a current value that is the sum of a current value determined by the constant current circuit ci1-1, a current value determined by the constant current circuit ci1-2, a current value determined by the constant current circuit ci1-3, and a current value determined by the constant current circuit ci1-4, based on the voltage Vh3 and the voltage value of the output terminal.

[0145] As a result, the output switching circuit 252-1 of the modified example can control the current value output to the discharge unit 600 according to the logic level of the voltage selection signal S1 [S1-1, S1-2, S1-3, S1-4] as the voltage selection signal S output by the waveform selection control circuit 210. Here, the switch sw1a-1 and the constant current circuit ci1-1 may be configured as separate circuit elements or may be configured as a single circuit element. Similarly, the switch sw1a-2 and the constant current circuit ci1-2, the switch sw1a-3 and the constant current circuit ci1-3, and the switch sw1a-4 and the constant current circuit ci1-4 may each be configured as separate circuit elements or may be configured as a single circuit element.

[0146] That is, the output switching circuit 252-1 of the modified example has a constant current circuit ci1-1 which has one end supplied with the drive voltage signal VHV3 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600 and outputs a signal of a constant current value based on the drive voltage signal VHV3, a constant current circuit ci1-2 which has one end supplied with the drive voltage signal VHV3 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600 and outputs a signal of a constant current value based on the drive voltage signal VHV3, a constant current circuit ci1-3 which has one end supplied with the drive voltage signal VHV3 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600 and outputs a signal of a constant current value based on the drive voltage signal VHV3, and a constant current circuit ci1-4 which has one end supplied with the drive voltage signal VHV3 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600 and outputs a signal of a constant current value based on the drive voltage signal VHV3. Then, based on the print data signal SI, the waveform selection control circuit 210 controls whether the constant current circuit ci1-1 outputs a signal of a constant current value based on the drive voltage signal VHV3, whether the constant current circuit ci1-2 outputs a signal of a constant current value based on the drive voltage signal VHV3, whether the constant current circuit ci1-3 outputs a signal of a constant current value based on the drive voltage signal VHV3, and whether the constant current circuit ci1-4 outputs a signal of a constant current value based on the drive voltage signal VHV3, thereby controlling the current value output from the output switching circuit 252-1 of the modified example.

[0147] Fig. 15 is a diagram showing an example of the configuration of an output switching circuit 252-2 of the modified example. As shown in Fig. 15, the output switching circuit 252-2 of the modified example includes switches sw2a-1 to sw2a-4 and sw2b-1 to sw2b-4, and constant current circuits ci2-1 to ci2-4 and co2-1 to co2-4. Furthermore, voltage selection signals S2a-1, S2a-2, S2a-3, and S2a-4 as the voltage selection signal S2a, voltage selection signals S2b-1, S2b-2, S2b-3, and S2b-4 as the voltage selection signal S2b, and a drive voltage signal VHV2 are input to the output switching circuit 252-2.

[0148] The voltage selection signal S2a-1 is input to the control terminal of the switch sw2a-1. The voltage selection signal S2a-2 is input to the control terminal of the switch sw2a-2. The voltage selection signal S2a-3 is input to the control terminal of the switch sw2a-3. The voltage selection signal S2a-4 is input to the control terminal of the switch sw2a-4. The voltage selection signal S2b-1 is input to the control terminal of the switch sw2b-1. The voltage selection signal S2b-2 is input to the control terminal of the switch sw2b-2. The voltage selection signal S2b-3 is input to the control terminal of the switch sw2b-3. The voltage selection signal S2b-4 is input to the control terminal of the switch sw2b-4. The drive voltage signal VHV2 is input to one terminal of the switches sw2a-1 to sw2a-4, sw2b-1 to sw2b-4. The other end of the switch SW2a-1 is electrically connected to the input terminal of the constant current circuit CI2-1. The other end of the switch SW2a-2 is electrically connected to the input terminal of the constant current circuit CI2-2. The other end of the switch SW2a-3 is electrically connected to the input terminal of the constant current circuit CI2-3. The other end of the switch SW2a-4 is electrically connected to the input terminal of the constant current circuit CI2-4. The other end of the switch SW2b-1 is electrically connected to the output terminal of the constant current circuit CO2-1. The other end of the switch SW2b-2 is electrically connected to the output terminal of the constant current circuit CO2-2. The other end of the switch SW2b-3 is electrically connected to the output terminal of the constant current circuit CO2-3. The other end of the switch SW2b-4 is electrically connected to the output terminal of the constant current circuit CO2-4.

[0149] In the output switching circuit 252-2 of the modified example configured as described above, when an H-level voltage selection signal S2a-1 is input to the control terminal of the switch sw2a-1, the switch sw2a-1 is controlled so that one terminal and the other terminal are conductive. As a result, the drive voltage signal VHV2 is supplied to the input terminal of the constant current circuit ci2-1, and the constant current circuit ci2-1 outputs a signal of a constant current value from the output terminal based on the voltage Vh2 supplied to the input terminal and the voltage value of the output terminal.

[0150] When an H-level voltage selection signal S2a-2 is input to the control terminal of the switch sw2a-2, one terminal and the other terminal of the switch sw2a-2 are controlled to be conductive, which supplies a drive voltage signal VHV2 to the input terminal of the constant current circuit ci2-2, and the constant current circuit ci2-2 outputs a signal of a constant current value from its output terminal based on the voltage Vh2 supplied to the input terminal and the voltage value of the output terminal.

[0151] When an H-level voltage selection signal S2a-3 is input to the control terminal of the switch sw2a-3, one terminal and the other terminal of the switch sw2a-3 are controlled to be conductive, which supplies the drive voltage signal VHV2 to the input terminal of the constant current circuit ci2-3, and the constant current circuit ci2-3 outputs a signal of a constant current value from its output terminal based on the voltage Vh2 supplied to the input terminal and the voltage value of the output terminal.

[0152] When an H-level voltage selection signal S2a-4 is input to the control terminal of the switch sw2a-4, one terminal and the other terminal of the switch sw2a-4 are controlled to be conductive, which supplies the drive voltage signal VHV2 to the input terminal of the constant current circuit ci2-4, and the constant current circuit ci2-4 outputs a signal of a constant current value from its output terminal based on the voltage Vh2 supplied to the input terminal and the voltage value of the output terminal.

[0153] When an H-level voltage selection signal S2b-1 is input to the control terminal of the switch sw2b-1, one terminal and the other terminal of the switch sw2b-1 are controlled to be conductive, which supplies the drive voltage signal VHV2 to the output terminal of the constant current circuit co2-1, and the constant current circuit ci2-1 outputs a signal of a constant current value from the output terminal based on the voltage value of the input terminal and the voltage Vh2 supplied to the output terminal.

[0154] When an H-level voltage selection signal S2b-2 is input to the control terminal of the switch sw2b-2, one terminal and the other terminal of the switch sw2b-2 are controlled to be conductive, which supplies a drive voltage signal VHV2 to the output terminal of the constant current circuit ci2-2, and the constant current circuit ci2-2 outputs a signal of a constant current value from the output terminal based on the voltage value of the input terminal and the voltage Vh2 supplied to the output terminal.

[0155] When an H-level voltage selection signal S2b-3 is input to the control terminal of the switch sw2b-3, one terminal and the other terminal of the switch sw2a-3 are controlled to be conductive, which supplies the drive voltage signal VHV2 to the output terminal of the constant current circuit ci2-3, and the constant current circuit ci2-3 outputs a signal of a constant current value from the output terminal based on the voltage value of the input terminal and the voltage Vh2 supplied to the output terminal.

[0156] When an H-level voltage selection signal S2b-4 is input to the control terminal of the switch sw2b-4, the switch sw2a-4 is controlled so that one terminal and the other terminal are conductive, causing the drive voltage signal VHV2 to be supplied to the output terminal of the constant current circuit ci2-4, which then outputs a signal of a constant current value from its output terminal based on the voltage value of its input terminal and the voltage Vh2 supplied to its output terminal.

[0157] That is, in the output switching circuit 252-2 of the modified example, the following pairs are connected in parallel between the wiring pattern to which the drive voltage signal VHV2 is supplied and the wiring pattern to which the drive signal VOUT is output: a pair of switch sw2a-1 and constant current circuit ci2-1, a pair of switch sw2a-2 and constant current circuit ci2-2, a pair of switch sw2a-3 and constant current circuit ci2-3, a pair of switch sw2a-4 and constant current circuit ci2-4, a pair of switch sw2b-1 and constant current circuit co2-1, a pair of switch sw2b-2 and constant current circuit co2-2, a pair of switch sw2b-3 and constant current circuit co2-3, and a pair of switch sw2b-4 and constant current circuit co2-4.

[0158] The conductive states of the switches sw2a-1 to sw2a-4 can be individually switched based on the logical levels of the voltage selection signals S2a-1 to S2a-4, so that the output switching circuit 252-2 of the modified example switches whether or not to output a signal of a constant current value based on the voltage Vh2 and the voltage value of the output terminal, and the conductive states of the switches sw2b-1 to sw2b-4 can be individually switched based on the logical levels of the voltage selection signals S2b-1 to S2b-4, so that the output switching circuit 252-2 of the modified example switches whether or not to draw in a signal of a constant current value based on the voltage value of the input terminal and voltage Vh2.

[0159] In the following description, the voltage selection signal S2a-1 input to the control terminal of switch sw2a-1, the voltage selection signal S2a-2 input to the control terminal of switch sw2a-2, the voltage selection signal S2a-3 input to the control terminal of switch sw2a-3, and the voltage selection signal S2a-4 input to the control terminal of switch sw2a-4 may be collectively referred to as voltage selection signals S2a [S2a-1, S2a-2, S2a-3, S2a-4]. Similarly, the voltage selection signal S2b-1 input to the control terminal of switch sw2b-1, the voltage selection signal S2b-2 input to the control terminal of switch sw2b-2, the voltage selection signal S2b-3 input to the control terminal of switch sw2b-3, and the voltage selection signal S2b-4 input to the control terminal of switch sw2b-4 may be collectively referred to as voltage selection signals S2b [S2b-1, S2b-2, S2b-3, S2b-4].

[0160] When voltage selection signals S2a[S2a-1, S2a-2, S2a-3, S2a-4]=[H, L, L, L] are input to the output switching circuit 252-2 of the modified example configured as described above, the switch sw2a-1 is controlled so that one end and the other end are conductive, and the switches sw2a-2 to sw2a-4 are controlled so that one end and the other end are non-conductive. At this time, the output switching circuit 252-2 outputs a constant signal to the discharge unit 600 at a current value determined by the constant current circuit ci2-1 based on the voltage Vh2 and the voltage value of the output terminal.

[0161] Furthermore, when the voltage selection signal S2a[S2a-1, S2a-2, S2a-3, S2a-4]=[H,H,L,L] is input to the output switching circuit 252-2 of the modified example, the switches sw2a-1 and sw2a-2 are controlled so that one end and the other end are conductive, and the switches sw2a-3 and sw2a-4 are controlled so that one end and the other end are non-conductive. At this time, the output switching circuit 252-2 outputs a constant signal to the discharge unit 600 at a current value that is the sum of the current value determined by the constant current circuit ci2-1 and the current value determined by the constant current circuit ci2-2, based on the voltage Vh2 and the voltage value of the output terminal.

[0162] Furthermore, when a voltage selection signal S2a [S2a-1, S2a-2, S2a-3, S2a-4] = [H, H, H, L] is input to the output switching circuit 252-2 of the modified example, the switches sw2a-1 to sw2a-3 are controlled so that one end and the other end are conductive, and the switch sw2a-4 is controlled so that one end and the other end are non-conductive. At this time, the output switching circuit 252-2 outputs a constant signal to the discharge unit 600 at a current value that is the sum of a current value determined by the constant current circuit ci2-1, a current value determined by the constant current circuit ci2-2, and a current value determined by the constant current circuit ci2-3, based on the voltage Vh2 and the voltage value of the output terminal.

[0163] Furthermore, when a voltage selection signal S2a [S2a-1, S2a-2, S2a-3, S2a-4] = [H, H, H, H] is input to the output switching circuit 252-2 of the modified example, the switches sw2a-1 to sw2a-4 are controlled so that one end and the other end are conductive. At this time, the output switching circuit 252-2 outputs a constant signal to the discharge unit 600 at a current value that is the sum of a current value determined by the constant current circuit ci2-1, a current value determined by the constant current circuit ci2-2, a current value determined by the constant current circuit ci2-3, and a current value determined by the constant current circuit ci2-4, based on the voltage Vh2 and the voltage value of the output terminal.

[0164] Furthermore, when the voltage selection signals S2b[S2b-1, S2b-2, S2b-3, S2b-4]=[H, L, L, L] are input to the output switching circuit 252-2 of the modified example, the switch sw2b-1 is controlled so that one end and the other end are conductive, and the switches sw2b-2 to sw2b-4 are controlled so that one end and the other end are non-conductive. At this time, the output switching circuit 252-2 draws a constant signal from the discharge unit 600 at a current value determined by the constant current circuit co2-1 based on the voltage value of the input end and the voltage Vh2.

[0165] Furthermore, when the voltage selection signal S2b[S2b-1, S2b-2, S2b-3, S2b-4]=[H,H,L,L] is input to the output switching circuit 252-2 of the modified example, the switches sw2b-1 and sw2b-2 are controlled so that one end and the other end are conductive, and the switches sw2b-3 and sw2b-4 are controlled so that one end and the other end are non-conductive. At this time, the output switching circuit 252-2 draws from the discharge unit 600 a constant signal with a current value that is the sum of the current value determined by the constant current circuit co2-1 and the current value determined by the constant current circuit co2-2, based on the voltage value of the input terminal and the voltage Vh2.

[0166] Furthermore, when the voltage selection signal S2b[S2b-1, S2b-2, S2b-3, S2b-4]=[H,H,H,L] is input to the output switching circuit 252-2 of the modified example, the switches sw2b-1 to sw2b-3 are controlled so that one end and the other end are conductive, and the switch sw2b-4 is controlled so that one end and the other end are non-conductive. At this time, the output switching circuit 252-2 draws a constant signal from the discharge unit 600 with a current value that is the sum of the current value determined by the constant current circuit co2-1, the current value determined by the constant current circuit co2-2, and the current value determined by the constant current circuit co2-3, based on the voltage value of the input terminal and the voltage Vh2.

[0167] Furthermore, when the voltage selection signal S2b[S2b-1, S2b-2, S2b-3, S2b-4]=[H,H,H,H] is input to the output switching circuit 252-2 of the modified example, the switches sw2b-1 to sw2b-4 are controlled so that one end and the other end are conductive. At this time, the output switching circuit 252-2 draws a constant signal from the discharge unit 600 at a current value that is the sum of the current values ​​determined by the constant current circuits co2-1, co2-2, co2-3, and co2-4, based on the voltage value of the input end and the voltage Vh2.

[0168] As a result, the output switching circuit 252-2 of the modified example can control the value of the current output to the output unit 600 according to the logic level of the voltage selection signal S2a [S2a-1, S2a-2, S2a-3, S2a-4] as the voltage selection signal S output by the waveform selection control circuit 210, and can control the value of the current drawn from the output unit 600 according to the logic level of the voltage selection signal S2b [S2b-1, S2b-2, S2b-3, S2b-4] as the voltage selection signal S output by the waveform selection control circuit 210. Here, the switch sw2a-1 and the constant current circuit ci2-1 may be configured as separate circuit elements or may be configured as a single circuit element. Similarly, the switch sw2a-2 and the constant current circuit ci2-2, the switch sw2a-3 and the constant current circuit ci2-3, and the switch sw2a-4 and the constant current circuit ci2-4 may each be configured as separate circuit elements or may be configured as a single circuit element. Furthermore, the switch SW2b-1 and the constant current circuit CO2-1 may be configured as separate circuit elements or as a single circuit element. Similarly, the switch SW2b-2 and the constant current circuit CO2-2, the switch SW2b-3 and the constant current circuit CO2-3, and the switch SW2b-4 and the constant current circuit CO2-4 may each be configured as separate circuit elements or as a single circuit element.

[0169] That is, the output switching circuit 252-2 of the modified example has a constant current circuit ci2-1 which has one end supplied with the drive voltage signal VHV2 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600 and outputs a signal of a constant current value based on the drive voltage signal VHV2, a constant current circuit ci2-2 which has one end supplied with the drive voltage signal VHV2 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600 and outputs a signal of a constant current value based on the drive voltage signal VHV2, a constant current circuit ci2-3 which has one end supplied with the drive voltage signal VHV2 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600 and outputs a signal of a constant current value based on the drive voltage signal VHV2, and a constant current circuit ci2-4 which has one end supplied with the drive voltage signal VHV2 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600 and outputs a signal of a constant current value based on the drive voltage signal VHV2. Then, based on the print data signal SI, the waveform selection control circuit 210 controls whether the constant current circuit ci2-1 outputs a signal of a constant current value based on the drive voltage signal VHV2, whether the constant current circuit ci2-2 outputs a signal of a constant current value based on the drive voltage signal VHV2, whether the constant current circuit ci2-3 outputs a signal of a constant current value based on the drive voltage signal VHV2, and whether the constant current circuit ci2-4 outputs a signal of a constant current value based on the drive voltage signal VHV2, thereby controlling the current value output from the output switching circuit 252-2 of the modified example.

[0170] Furthermore, the output switching circuit 252-2 of the modified example has a constant current circuit co2-1, one end of which is supplied with the drive voltage signal VHV2 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VHV2; a constant current circuit co2-2, one end of which is supplied with the drive voltage signal VHV2 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VHV2; a constant current circuit co2-3, one end of which is supplied with the drive voltage signal VHV2 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VHV2; and a constant current circuit co2-4, one end of which is supplied with the drive voltage signal VHV2 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VHV2. Then, based on the print data signal SI, the waveform selection control circuit 210 controls whether the constant current circuit co2-1 outputs a signal of a constant current value based on the drive voltage signal VHV2, whether the constant current circuit co2-2 outputs a signal of a constant current value based on the drive voltage signal VHV2, whether the constant current circuit co2-3 outputs a signal of a constant current value based on the drive voltage signal VHV2, and whether the constant current circuit co2-4 outputs a signal of a constant current value based on the drive voltage signal VHV2, thereby controlling the current value drawn by the output switching circuit 252-2 of the modified example.

[0171] Here, the output switching circuits 252-3 to 252-6 of the modified example have the same configuration as the output switching circuit 252-2 of the modified example, except that the input signals and output signals are different. Therefore, the configuration of the output switching circuits 252-3 to 252-6 of the modified example is not shown in the figures and the description will be simplified.

[0172] The output switching circuit 252-3 of the modified example has a pair of switch sw3a-1 and constant current circuit ci3-1, a pair of switch sw3a-2 and constant current circuit ci3-2, a pair of switch sw3a-3 and constant current circuit ci3-3, a pair of switch sw3a-4 and constant current circuit ci3-4, a pair of switch sw3b-1 and constant current circuit co3-1, a pair of switch sw3b-2 and constant current circuit co3-2, a pair of switch sw3b-3 and constant current circuit co3-3, and a pair of switch sw3b-4 and constant current circuit co3-4, all connected in parallel between the wiring pattern to which the drive voltage signal VHV1 is supplied and the wiring pattern to which the drive signal VOUT is output.

[0173] Each of the pairs of switch sw3a-1 and constant current circuit ci3-1, switch sw3a-2 and constant current circuit ci3-2, switch sw3a-3 and constant current circuit ci3-3, and switch sw3a-4 and constant current circuit ci3-4 switches whether or not to output a signal of a constant current value based on voltage Vh1 and the voltage value of the output terminal from output switching circuit 252-3 based on the logical level of voltage selection signal S3a [S3a-1, S3a-2, S3a-3, S3a-4] as voltage selection signal S. Similarly, the pair of switch sw3b-1 and constant current circuit co3-1, the pair of switch sw3b-2 and constant current circuit co3-2, the pair of switch sw3b-3 and constant current circuit co3-3, and the pair of switch sw3b-4 and constant current circuit co3-4 each switch whether or not to draw a signal of a constant current value based on the voltage value of the input terminal and voltage Vh1 into the output switching circuit 252-3 based on the logical level of the voltage selection signal S3b [S3b-1, S3b-2, S3b-3, S3b-4] as the voltage selection signal S.

[0174] Therefore, the output switching circuit 252-3 of the modified example can control the current value output to the discharge portion 600 according to the logical level of the voltage selection signal S3a [S3a-1, S3a-2, S3a-3, S3a-4] as the voltage selection signal S output by the waveform selection control circuit 210, and can control the current value drawn from the discharge portion 600 according to the logical level of the voltage selection signal S3b [S3b-1, S3b-2, S3b-3, S3b-4] as the voltage selection signal S output by the waveform selection control circuit 210.

[0175] That is, the output switching circuit 252-3 of the modified example has a constant current circuit ci3-1, which has one end supplied with the drive voltage signal VHV1 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VHV1; a constant current circuit ci3-2, which has one end supplied with the drive voltage signal VHV1 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VHV1; a constant current circuit ci3-3, which has one end supplied with the drive voltage signal VHV1 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VHV1; and a constant current circuit ci3-4, which has one end supplied with the drive voltage signal VHV1 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VHV1. Then, based on the print data signal SI, the waveform selection control circuit 210 controls whether the constant current circuit ci3-1 outputs a signal of a constant current value based on the drive voltage signal VHV1, whether the constant current circuit ci3-2 outputs a signal of a constant current value based on the drive voltage signal VHV1, whether the constant current circuit ci3-3 outputs a signal of a constant current value based on the drive voltage signal VHV1, and whether the constant current circuit ci3-4 outputs a signal of a constant current value based on the drive voltage signal VHV1, thereby controlling the current value output from the output switching circuit 252-3 of the modified example.

[0176] Furthermore, the output switching circuit 252-3 of the modified example has a constant current circuit co3-1, one end of which is supplied with the drive voltage signal VHV1 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VHV1; a constant current circuit co3-2, one end of which is supplied with the drive voltage signal VHV1 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VHV1; a constant current circuit co3-3, one end of which is supplied with the drive voltage signal VHV1 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VHV1; and a constant current circuit co3-4, one end of which is supplied with the drive voltage signal VHV1 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VHV1. Then, based on the print data signal SI, the waveform selection control circuit 210 controls whether the constant current circuit co3-1 outputs a signal of a constant current value based on the drive voltage signal VHV1, whether the constant current circuit co3-2 outputs a signal of a constant current value based on the drive voltage signal VHV1, whether the constant current circuit co3-3 outputs a signal of a constant current value based on the drive voltage signal VHV1, and whether the constant current circuit co3-4 outputs a signal of a constant current value based on the drive voltage signal VHV1, thereby controlling the current value drawn by the output switching circuit 252-3 of the modified example.

[0177] Here, switch SW3a-1 and constant current circuit CI3-1 may be configured as separate circuit elements or as a single circuit element. Similarly, switch SW3a-2 and constant current circuit CI3-2, switch SW3a-3 and constant current circuit CI3-3, and switch SW3a-4 and constant current circuit CI3-4 may each be configured as separate circuit elements or as a single circuit element. Furthermore, switch SW3b-1 and constant current circuit CO3-1 may each be configured as separate circuit elements or as a single circuit element. Similarly, switch SW3b-2 and constant current circuit CO3-2, switch SW3b-3 and constant current circuit CO3-3, and switch SW3b-4 and constant current circuit CO3-4 may each be configured as separate circuit elements or as a single circuit element.

[0178] In addition, the output switching circuit 252-4 of the modified example has a pair of switch sw4a-1 and constant current circuit ci4-1, a pair of switch sw4a-2 and constant current circuit ci4-2, a pair of switch sw4a-3 and constant current circuit ci4-3, a pair of switch sw4a-4 and constant current circuit ci4-4, a pair of switch sw4b-1 and constant current circuit co4-1, a pair of switch sw4b-2 and constant current circuit co4-2, a pair of switch sw4b-3 and constant current circuit co4-3, and a pair of switch sw4b-4 and constant current circuit co4-4, all connected in parallel between the wiring pattern to which the drive voltage signal VCV is supplied and the wiring pattern to which the drive signal VOUT is output.

[0179] Each of the pairs of switch sw4a-1 and constant current circuit ci4-1, switch sw4a-2 and constant current circuit ci4-2, switch sw4a-3 and constant current circuit ci4-3, and switch sw4a-4 and constant current circuit ci4-4 switches whether or not to output a signal of a constant current value based on the voltage Vc and the voltage value of the output terminal from the output switching circuit 252-4 based on the logical level of the voltage selection signal S4a [S4a-1, S4a-2, S4a-3, S4a-4] as the voltage selection signal S. Similarly, the pair of switch sw4b-1 and constant current circuit co4-1, the pair of switch sw4b-2 and constant current circuit co4-2, the pair of switch sw4b-3 and constant current circuit co4-3, and the pair of switch sw4b-4 and constant current circuit co4-4 each switch whether or not to draw a signal of a constant current value based on the voltage value of the input terminal and voltage Vc into the output switching circuit 252-4 based on the logical level of the voltage selection signal S4b [S4b-1, S4b-2, S4b-3, S4b-4] as the voltage selection signal S.

[0180] Therefore, the output switching circuit 252-4 of the modified example can control the current value output to the discharge section 600 according to the logical level of the voltage selection signal S4a [S4a-1, S4a-2, S4a-3, S4a-4] as the voltage selection signal S output by the waveform selection control circuit 210, and can control the current value drawn from the discharge section 600 according to the logical level of the voltage selection signal S4b [S4b-1, S4b-2, S4b-3, S4b-4] as the voltage selection signal S output by the waveform selection control circuit 210.

[0181] That is, the output switching circuit 252-4 of the modified example has a constant current circuit ci4-1, which has one end supplied with the drive voltage signal VCV and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VCV; a constant current circuit ci4-2, which has one end supplied with the drive voltage signal VCV and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VCV; a constant current circuit ci4-3, which has one end supplied with the drive voltage signal VCV and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VCV; and a constant current circuit ci4-4, which has one end supplied with the drive voltage signal VCV and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VCV. Then, based on the print data signal SI, the waveform selection control circuit 210 controls whether the constant current circuit ci4-1 outputs a signal of a constant current value based on the drive voltage signal VCV, whether the constant current circuit ci4-2 outputs a signal of a constant current value based on the drive voltage signal VCV, whether the constant current circuit ci4-3 outputs a signal of a constant current value based on the drive voltage signal VCV, and whether the constant current circuit ci4-4 outputs a signal of a constant current value based on the drive voltage signal VCV, thereby controlling the current value output from the output switching circuit 252-4 of the modified example.

[0182] Furthermore, the output switching circuit 252-4 of the modified example has a constant current circuit co4-1, which has one end supplied with the drive voltage signal VCV and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VCV; a constant current circuit co4-2, which has one end supplied with the drive voltage signal VCV and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VCV; a constant current circuit co4-3, which has one end supplied with the drive voltage signal VCV and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VCV; and a constant current circuit co4-4, which has one end supplied with the drive voltage signal VCV and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VCV. Then, based on the print data signal SI, the waveform selection control circuit 210 controls whether the constant current circuit co4-1 outputs a signal of a constant current value based on the drive voltage signal VCV, whether the constant current circuit co4-2 outputs a signal of a constant current value based on the drive voltage signal VCV, whether the constant current circuit co4-3 outputs a signal of a constant current value based on the drive voltage signal VCV, and whether the constant current circuit co4-4 outputs a signal of a constant current value based on the drive voltage signal VCV, thereby controlling the current value drawn by the output switching circuit 252-4 of the modified example.

[0183] Here, switch SW4a-1 and constant current circuit CI4-1 may be configured as separate circuit elements or may be configured as a single circuit element. Similarly, switch SW4a-2 and constant current circuit CI4-2, switch SW4a-3 and constant current circuit CI4-3, and switch SW4a-4 and constant current circuit CI4-4 may each be configured as separate circuit elements or may be configured as a single circuit element. Furthermore, switch SW4b-1 and constant current circuit CO4-1 may each be configured as separate circuit elements or may be configured as a single circuit element. Similarly, switch SW4b-2 and constant current circuit CO4-2, switch SW4b-3 and constant current circuit CO4-3, and switch SW4b-4 and constant current circuit CO4-4 may each be configured as separate circuit elements or may be configured as a single circuit element.

[0184] Furthermore, the output switching circuit 252-5 of the modified example has a pair of switch sw5a-1 and constant current circuit ci5-1, a pair of switch sw5a-2 and constant current circuit ci5-2, a pair of switch sw5a-3 and constant current circuit ci5-3, a pair of switch sw5a-4 and constant current circuit ci5-4, a pair of switch sw5b-1 and constant current circuit co5-1, a pair of switch sw5b-2 and constant current circuit co5-2, a pair of switch sw5b-3 and constant current circuit co5-3, and a pair of switch sw5b-4 and constant current circuit co5-4, all connected in parallel between the wiring pattern to which the drive voltage signal VBV1 is supplied and the wiring pattern to which the drive signal VOUT is output.

[0185] Each of the pairs of switch sw5a-1 and constant current circuit ci5-1, switch sw5a-2 and constant current circuit ci5-2, switch sw5a-3 and constant current circuit ci5-3, and switch sw5a-4 and constant current circuit ci5-4 switches whether or not to output a signal of a constant current value based on voltage Vb1 and the voltage value of the output terminal from output switching circuit 252-5 based on the logical level of voltage selection signal S5a [S5a-1, S5a-2, S5a-3, S5a-4] as voltage selection signal S. Similarly, the pair of switch sw5b-1 and constant current circuit co5-1, the pair of switch sw5b-2 and constant current circuit co5-2, the pair of switch sw5b-3 and constant current circuit co5-3, and the pair of switch sw5b-4 and constant current circuit co5-4 each switch whether or not to draw a signal of a constant current value based on the voltage value of the input terminal and voltage Vb1 into the output switching circuit 252-5 based on the logical level of the voltage selection signal S5b [S5b-1, S5b-2, S5b-3, S5b-4] as the voltage selection signal S.

[0186] Therefore, the output switching circuit 252-5 of the modified example can control the current value output to the discharge section 600 according to the logical level of the voltage selection signal S5a [S5a-1, S5a-2, S5a-3, S5a-4] as the voltage selection signal S output by the waveform selection control circuit 210, and can control the current value drawn from the discharge section 600 according to the logical level of the voltage selection signal S5b [S5b-1, S5b-2, S5b-3, S5b-4] as the voltage selection signal S output by the waveform selection control circuit 210.

[0187] That is, the output switching circuit 252-5 of the modified example has a constant current circuit ci5-1, one end of which is supplied with the drive voltage signal VBV1 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VBV1; a constant current circuit ci5-2, one end of which is supplied with the drive voltage signal VBV1 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VBV1; a constant current circuit ci5-3, one end of which is supplied with the drive voltage signal VBV1 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VBV1; and a constant current circuit ci5-4, one end of which is supplied with the drive voltage signal VBV1 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VBV1. Then, based on the print data signal SI, the waveform selection control circuit 210 controls whether the constant current circuit ci5-1 outputs a signal of a constant current value based on the drive voltage signal VBV1, whether the constant current circuit ci5-2 outputs a signal of a constant current value based on the drive voltage signal VBV1, whether the constant current circuit ci5-3 outputs a signal of a constant current value based on the drive voltage signal VBV1, and whether the constant current circuit ci5-4 outputs a signal of a constant current value based on the drive voltage signal VBV1, thereby controlling the current value output from the output switching circuit 252-5 of the modified example.

[0188] Furthermore, the output switching circuit 252-5 of the modified example has a constant current circuit co5-1, one end of which is supplied with the drive voltage signal VBV1 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VBV1; a constant current circuit co5-2, one end of which is supplied with the drive voltage signal VBV1 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VBV1; a constant current circuit co5-3, one end of which is supplied with the drive voltage signal VBV1 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VBV1; and a constant current circuit co5-4, one end of which is supplied with the drive voltage signal VBV1 and the other end of which is electrically connected to the piezoelectric element 60 of the discharge section 600, and which outputs a signal of a constant current value based on the drive voltage signal VBV1. Then, based on the print data signal SI, the waveform selection control circuit 210 controls whether the constant current circuit co5-1 outputs a signal of a constant current value based on the drive voltage signal VBV1, whether the constant current circuit co5-2 outputs a signal of a constant current value based on the drive voltage signal VBV1, whether the constant current circuit co5-3 outputs a signal of a constant current value based on the drive voltage signal VBV1, and whether the constant current circuit co5-4 outputs a signal of a constant current value based on the drive voltage signal VBV1, thereby controlling the current value drawn by the output switching circuit 252-5 of the modified example.

[0189] Here, switch SW5a-1 and constant current circuit CI5-1 may be configured as separate circuit elements or may be configured as a single circuit element. Similarly, switch SW5a-2 and constant current circuit CI5-2, switch SW5a-3 and constant current circuit CI5-3, and switch SW5a-4 and constant current circuit CI5-4 may each be configured as separate circuit elements or may be configured as a single circuit element. Furthermore, switch SW5b-1 and constant current circuit CO5-1 may each be configured as separate circuit elements or may be configured as a single circuit element. Similarly, switch SW5b-2 and constant current circuit CO5-2, switch SW5b-3 and constant current circuit CO5-3, and switch SW5b-4 and constant current circuit CO5-4 may each be configured as separate circuit elements or may be configured as a single circuit element.

[0190] Furthermore, the output switching circuit 252-6 of the modified example has a pair of a switch sw6a-1 and a constant current circuit ci6-1, a pair of a switch sw6a-2 and a constant current circuit ci6-2, a pair of a switch sw6a-3 and a constant current circuit ci6-3, a pair of a switch sw6a-4 and a constant current circuit ci6-4, a pair of a switch sw6b-1 and a constant current circuit co6-1, a pair of a switch sw6b-2 and a constant current circuit co6-2, a pair of a switch sw6b-3 and a constant current circuit co6-3, and a pair of a switch sw6b-4 and a constant current circuit co6-4, all connected in parallel between the wiring pattern to which the drive voltage signal VBV2 is supplied and the wiring pattern to which the drive signal VOUT is output.

[0191] Then, each of the pair of switch sw6a-1 and constant current circuit ci6-1, the pair of switch sw6a-2 and constant current circuit ci6-2, the pair of switch sw6a-3 and constant current circuit ci6-3, and the pair of switch sw6a-4 and constant current circuit ci6-4 switches whether or not to output a signal of a constant current value based on voltage Vb2 and the voltage value of the output terminal from output switching circuit 252-6 based on the logical level of voltage selection signal S6a [S6a-1, S6a-2, S6a-3, S6a-4] as voltage selection signal S. Similarly, the pair of switch sw6b-1 and constant current circuit co6-1, the pair of switch sw6b-2 and constant current circuit co6-2, the pair of switch sw6b-3 and constant current circuit co6-3, and the pair of switch sw6b-4 and constant current circuit co6-4 each switch whether or not to draw a signal of a constant current value based on the voltage value of the input terminal and voltage Vb2 into the output switching circuit 252-6 based on the logical level of voltage selection signal S6b [S6b-1, S6b-2, S6b-3, S6b-4] as voltage selection signal S.

[0192] Therefore, the output switching circuit 252-6 of the modified example can control the current value output to the discharge section 600 according to the logical level of the voltage selection signal S6a [S6a-1, S6a-2, S6a-3, S6a-4] as the voltage selection signal S output by the waveform selection control circuit 210, and can control the current value drawn from the discharge section 600 according to the logical level of the voltage selection signal S6b [S6b-1, S6b-2, S6b-3, S6b-4] as the voltage selection signal S output by the waveform selection control circuit 210.

[0193] That is, the output switching circuit 252-6 of the modified example has a constant current circuit ci6-1, which has one end supplied with the drive voltage signal VBV2 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VBV2; a constant current circuit ci6-2, which has one end supplied with the drive voltage signal VBV2 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VBV2; a constant current circuit ci6-3, which has one end supplied with the drive voltage signal VBV2 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VBV2; and a constant current circuit ci6-4, which has one end supplied with the drive voltage signal VBV2 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VBV2. Then, based on the print data signal SI, the waveform selection control circuit 210 controls whether the constant current circuit ci6-1 outputs a signal of a constant current value based on the drive voltage signal VBV2, whether the constant current circuit ci6-2 outputs a signal of a constant current value based on the drive voltage signal VBV2, whether the constant current circuit ci6-3 outputs a signal of a constant current value based on the drive voltage signal VBV2, and whether the constant current circuit ci6-4 outputs a signal of a constant current value based on the drive voltage signal VBV2, thereby controlling the current value output from the output switching circuit 252-6 of the modified example.

[0194] Furthermore, the output switching circuit 252-6 of the modified example has a constant current circuit co6-1, which has one end supplied with the drive voltage signal VBV2 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VBV2; a constant current circuit co6-2, which has one end supplied with the drive voltage signal VBV2 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VBV2; a constant current circuit co6-3, which has one end supplied with the drive voltage signal VBV2 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VBV2; and a constant current circuit co6-4, which has one end supplied with the drive voltage signal VBV2 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VBV2. Then, based on the print data signal SI, the waveform selection control circuit 210 controls whether the constant current circuit co6-1 outputs a signal of a constant current value based on the drive voltage signal VBV2, whether the constant current circuit co6-2 outputs a signal of a constant current value based on the drive voltage signal VBV2, whether the constant current circuit co6-3 outputs a signal of a constant current value based on the drive voltage signal VBV2, and whether the constant current circuit co6-4 outputs a signal of a constant current value based on the drive voltage signal VBV2, thereby controlling the current value drawn by the output switching circuit 252-6 of the modified example.

[0195] Here, switch SW6a-1 and constant current circuit CI6-1 may be configured as separate circuit elements or may be configured as a single circuit element. Similarly, switch SW6a-2 and constant current circuit CI6-2, switch SW6a-3 and constant current circuit CI6-3, and switch SW6a-4 and constant current circuit CI6-4 may each be configured as separate circuit elements or may be configured as a single circuit element. Furthermore, switch SW6b-1 and constant current circuit CO6-1 may each be configured as separate circuit elements or may be configured as a single circuit element. Similarly, switch SW6b-2 and constant current circuit CO6-2, switch SW6b-3 and constant current circuit CO6-3, and switch SW6b-4 and constant current circuit CO6-4 may each be configured as separate circuit elements or may be configured as a single circuit element.

[0196] Fig. 16 is a diagram showing the configuration of an output switching circuit 252-7 of the modified example. As shown in Fig. 16, the output switching circuit 252-7 of the modified example includes switches sw7b-1 to sw7b-4 and constant current circuits co7-1 to co7-4. Furthermore, voltage selection signals S7-1, S7-2, S7-3, and S7-4 as the voltage selection signal S7, and a drive voltage signal VBV3 are input to the output switching circuit 252-7 of the modified example.

[0197] The voltage selection signal S7-1 is input to the control terminal of the switch sw7b-1. The voltage selection signal S7-2 is input to the control terminal of the switch sw7b-2. The voltage selection signal S7-3 is input to the control terminal of the switch sw7b-3. The voltage selection signal S7-4 is input to the control terminal of the switch sw7b-4. The drive voltage signal VBV3 is input to one terminal of the switches sw7b-1 to sw7b-4. The other terminal of the switch sw7b-1 is electrically connected to the output terminal of the constant current circuit co7-1. The other terminal of the switch sw7b-2 is electrically connected to the output terminal of the constant current circuit co7-2. The other terminal of the switch sw7b-3 is electrically connected to the output terminal of the constant current circuit co7-3. The other terminal of the switch sw7b-4 is electrically connected to the output terminal of the constant current circuit co7-4.

[0198] In the output switching circuit 252-7 of the modified example configured as described above, when an H-level voltage selection signal S7-1 is input to the control terminal of the switch sw7b-1, one terminal and the other terminal of the switch sw7b-1 are controlled to be conductive, which supplies the drive voltage signal VBV3 to the output terminal of the constant current circuit co7-1, and the constant current circuit co7-1 outputs a signal of a constant current value from the output terminal based on the voltage value of the input terminal and the voltage Vb3 supplied to the output terminal.

[0199] When an H-level voltage selection signal S7-2 is input to the control terminal of the switch sw7b-2, one terminal and the other terminal of the switch sw7b-2 are controlled to be conductive, which supplies the drive voltage signal VBV3 to the input terminal of the constant current circuit co7-2, and the constant current circuit co7-2 outputs a signal of a constant current value from its output terminal based on the voltage value of the input terminal and the voltage Vb3 supplied to its output terminal.

[0200] When an H-level voltage selection signal S7-3 is input to the control terminal of the switch sw7b-3, one terminal and the other terminal of the switch sw7b-3 are controlled to be conductive, which supplies the drive voltage signal VBV3 to the input terminal of the constant current circuit co7-3, and the constant current circuit co7-3 outputs a signal of a constant current value from its output terminal based on the voltage value of the input terminal and the voltage Vb3 supplied to its output terminal.

[0201] When an H-level voltage selection signal S7-4 is input to the control terminal of the switch sw7b-4, one terminal and the other terminal of the switch sw7b-4 are controlled to be conductive, which supplies the drive voltage signal VBV3 to the input terminal of the constant current circuit co7-4, and the constant current circuit co7-4 outputs a signal of a constant current value from its output terminal based on the voltage value of the input terminal and the voltage Vb3 supplied to its output terminal.

[0202] That is, in the output switching circuit 252-7 of the modified example, a set of a switch sw7b-1 and a constant current circuit co7-1, a set of a switch sw7b-2 and a constant current circuit co7-2, a set of a switch sw7b-3 and a constant current circuit co7-3, and a set of a switch sw7b-4 and a constant current circuit co7-4 are connected in parallel between a wiring pattern to which the drive voltage signal VBV3 is supplied and a wiring pattern to which the drive signal VOUT is output. Then, by individually switching the conduction states of the switches sw7b-1 to sw7b-4 based on the logic levels of the voltage selection signals S7-1 to S7-4, the output switching circuit 252-7 of the modified example can switch whether or not to output a signal of a constant current value based on the voltage value of the input terminal and the voltage Vb3.

[0203] In the following description, the voltage selection signal S7-1 input to the control terminal of switch sw7b-1, the voltage selection signal S7-2 input to the control terminal of switch sw7b-2, the voltage selection signal S7-3 input to the control terminal of switch sw7b-3, and the voltage selection signal S7-4 input to the control terminal of switch sw7b-4 may be collectively referred to as voltage selection signals S7[S7-1, S7-2, S7-3, S7-4].

[0204] When voltage selection signals S7[S7-1, S7-2, S7-3, S7-4]=[H, L, L, L] are input to the output switching circuit 252-7 of the modified example configured as described above, the switch sw7b-1 is controlled so that one end and the other end are conductive, and the switches sw7b-2 to sw7b-4 are controlled so that one end and the other end are non-conductive. At this time, the output switching circuit 252-7 draws a constant signal from the output unit 600 at a current value determined by the constant current circuit co7-1 based on the voltage value of the input end and the voltage Vb3.

[0205] Furthermore, when the voltage selection signal S7[S7-1, S7-2, S7-3, S7-4]=[H,H,L,L] is input to the output switching circuit 252-7 of the modified example, the switches sw7b-1 and sw7b-2 are controlled so that one end and the other end are conductive, and the switches sw7b-3 and sw7b-4 are controlled so that one end and the other end are non-conductive. At this time, the output switching circuit 252-7 draws from the discharge unit 600 a constant signal with a current value that is the sum of the current value determined by the constant current circuit co7-1 and the current value determined by the constant current circuit co7-2, based on the voltage value of the input terminal and the voltage Vb3.

[0206] Furthermore, when the voltage selection signal S7[S7-1, S7-2, S7-3, S7-4]=[H, H, H, L] is input to the output switching circuit 252-7 of the modified example, the switches sw7b-1 to sw7b-3 are controlled so that one end and the other end are conductive, and the switch sw7b-4 is controlled so that one end and the other end are non-conductive. At this time, the output switching circuit 252-7 draws a constant signal from the discharge unit 600 with a current value that is the sum of the current value determined by the constant current circuit co7-1, the current value determined by the constant current circuit co7-2, and the current value determined by the constant current circuit co7-3, based on the voltage value of the input terminal and the voltage Vh3.

[0207] When the output switching circuit 252-7 of the modified example receives a voltage selection signal S7[S7-1, S7-2, S7-3, S7-4]=[H,H,H,H], the switches sw7b-1 to sw7b-4 are controlled so that one end and the other end are conductive. At this time, the output switching circuit 252-7 draws a constant signal from the discharge unit 600 at a current value that is the sum of the current values ​​determined by the constant current circuits co7-1, co7-2, co7-3, and co7-4, based on the voltage value at the input end and the voltage Vb3.

[0208] As a result, the output switching circuit 252-7 of the modified example can control the value of the current drawn from the discharge unit 600 according to the logic level of the voltage selection signal S7 [S7-1, S7-2, S7-3, S7-4] as the voltage selection signal S output by the waveform selection control circuit 210. Here, the switch sw7b-1 and the constant current circuit co7-1 may be configured as separate circuit elements or may be configured as a single circuit element. Similarly, the switch sw7b-2 and the constant current circuit co7-2, the switch sw7b-3 and the constant current circuit co7-3, and the switch sw7b-4 and the constant current circuit co7-4 may each be configured as separate circuit elements or may be configured as a single circuit element.

[0209] That is, the output switching circuit 252-7 of the modified example has a constant current circuit co7-1, which has one end supplied with the drive voltage signal VBV3 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VBV3; a constant current circuit co7-2, which has one end supplied with the drive voltage signal VBV3 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VBV3; a constant current circuit co7-3, which has one end supplied with the drive voltage signal VBV3 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VBV3; and a constant current circuit co7-4, which has one end supplied with the drive voltage signal VBV3 and the other end electrically connected to the piezoelectric element 60 of the discharge section 600, and outputs a signal of a constant current value based on the drive voltage signal VBV3. Then, based on the print data signal SI, the waveform selection control circuit 210 controls whether the constant current circuit co7-1 outputs a signal of a constant current value based on the drive voltage signal VBV3, whether the constant current circuit co7-2 outputs a signal of a constant current value based on the drive voltage signal VBV3, whether the constant current circuit co7-3 outputs a signal of a constant current value based on the drive voltage signal VBV3, and whether the constant current circuit co7-4 outputs a signal of a constant current value based on the drive voltage signal VBV3, thereby controlling the current value drawn by the output switching circuit 252-7 of the modified example.

[0210] In the liquid ejection device 1 of the modified example configured as above, each of the output switching circuits 252-1 to 252-7 of the output circuit 250 can control the value of current supplied to the ejection section 600 and the value of current drawn from the ejection section 600, thereby controlling the slope of the signal waveform of the drive signal VOUT to be output. Fig. 17 is a diagram showing an example of the relationship between the slope of the signal waveform of the drive signal VOUT and the voltage control signal of the modified example.

[0211] The piezoelectric element 60 to which the drive signal VOUT is supplied is a capacitive load, and therefore the voltage value supplied to the piezoelectric element 60 is the amount of charge stored in the piezoelectric element 60, and is proportional to the amount of current of the drive signal VOUT supplied to the piezoelectric element 60. Therefore, as in the liquid ejection device 1 of the modified example, each of the output switching circuits 252-1 to 252-7 of the output circuit 250 controls the current value supplied to the ejection unit 600 and the current value drawn from the ejection unit 600, thereby controlling the slope of the signal waveform of the drive signal VOUT output by the drive signal output circuit 200.

[0212] For example, when the voltage selection signals S7[S7-1, S7-2, S7-3, S7-4]=[H,H,H,H], the output switching circuit 252-7 draws a constant signal from the output unit 600 at a current value that is the sum of the current values ​​determined by the constant current circuits co7-1, co7-2, co7-3, and co7-4 based on the voltage value at the input terminal and the voltage Vb3. On the other hand, when the voltage selection signals S7[S7-1, S7-2, S7-3, S7-4]=[H,L,L,L], the output switching circuit 252-7 draws a constant signal from the output unit 600 at a current value determined by the constant current circuit co7-1 based on the voltage value at the input terminal and the voltage Vb3. That is, when the voltage selection signal S7[S7-1, S7-2, S7-3, S7-4]=[H, H, H, H], the amount of current drawn by the output switching circuit 252-7 from the discharge section 600 is greater than the amount of current drawn by the output switching circuit 252-7 from the discharge section 600 when the voltage selection signal S7[S7-1, S7-2, S7-3, S7-4]=[H, L, L, L]. Therefore, as shown in Figure 17, when the voltage value of the drive waveform DEP changes from voltage Vc to voltage Vb3 during period pa2, by inputting voltage selection signal S7[S7-1, S7-2, S7-3, S7-4] = [H, H, H, H] to output circuit 250, the voltage value of the drive waveform DEP can be changed more sharply compared to when voltage selection signal S7[S7-1, S7-2, S7-3, S7-4] = [H, L, L, L] is input.

[0213] Furthermore, for example, when the voltage selection signals S2a[S2a-1, S2a-2, S2a-3, S2a-4]=[H,H,H,L], the output switching circuit 252-2 supplies a constant signal with a current value that is the sum of the current values ​​determined by the constant current circuits ci2-1, ci2-2, and ci2-3 based on the voltage Vh2 and the voltage value of the output terminal to the output unit 600. On the other hand, when the voltage selection signals S2a[S2a-1, S2a-2, S2a-3, S2a-4]=[H,H,L,L], the output switching circuit 252-2 supplies a constant signal with a current value that is the sum of the current values ​​determined by the constant current circuits ci2-1 and ci2-2 based on the voltage Vh2 and the voltage value of the output terminal to the output unit 600. That is, when the voltage selection signal S2a[S2a-1, S2a-2, S2a-3, S2a-4]=[H,H,H,L], the amount of current supplied by the output switching circuit 252-2 to the discharge section 600 is greater than the amount of current supplied by the output switching circuit 252-2 to the discharge section 600 when the voltage selection signal S2a[S2a-1, S2a-2, S2a-3, S2a-4]=[H,H,L,L]. Therefore, as shown in Figure 17, when the voltage value of the drive waveform NVT changes from voltage Vc to voltage Vh2 during period pc2, by inputting voltage selection signals S2a[S2a-1, S2a-2, S2a-3, S2a-4] = [H, H, H, L] to the output circuit 250, the voltage value of the drive waveform NVT can be changed more sharply compared to when voltage selection signals S2a[S2a-1, S2a-2, S2a-3, S2a-4] = [H, H, L, L] are input.

[0214] As described above, in the liquid ejection device 1 of the modified example, it is possible to control the slope of the voltage change of the drive waveforms DEP, BSD, and NVT included in the drive signal VOUT. This allows the drive signal output circuit 200 in the liquid ejection device 1 of the modified example to output an optimum waveform of the drive signal VOUT according to the operating environment of the liquid ejection device 1 and the physical properties of the ink being used. Therefore, in addition to the above-mentioned effects, the liquid ejection device 1 of the modified example can enhance the versatility of the liquid ejection device 1.

[0215] 2. Second embodiment Next, the configuration of a liquid ejection device 1 of a second embodiment will be described. The liquid ejection device 1 of the second embodiment differs from the liquid ejection device 1 of the first embodiment in the configuration of the output circuit 250 of the drive signal output circuit 200. In describing the liquid ejection device 1 of the second embodiment, the same components as those of the liquid ejection device 1 of the first embodiment will be assigned the same reference numerals, and their description will be simplified or omitted. Furthermore, in the liquid ejection device 1 of the second embodiment, the waveform selection control circuit 210 of the drive signal output circuit 200 will be described as generating voltage selection signals S11 to S17 as the voltage selection signal S based on the latch signal LAT, change signal CH, clock signal SCK, print data signal SI, and waveform selection signal WS, and outputting them to the corresponding output circuit 250. Furthermore, the output circuit 250 of the liquid ejection device 1 of the second embodiment will be described as having an output switching circuit 252a-1 equivalent to the output switching circuit 252-1 that selects whether to output the drive voltage signal VHV3 in the liquid ejection device 1 of the first embodiment, an output switching circuit 252a-2 equivalent to the output switching circuit 252-2 that selects whether to output the drive voltage signal VHV2, an output switching circuit 252a-3 equivalent to the output switching circuit 252-3 that selects whether to output the drive voltage signal VHV1, an output switching circuit 252a-4 equivalent to the output switching circuit 252-4 that selects whether to output the drive voltage signal VCV, an output switching circuit 252a-5 equivalent to the output switching circuit 252-5 that selects whether to output the drive voltage signal VBV1, an output switching circuit 252a-6 equivalent to the output switching circuit 252-6 that selects whether to output the drive voltage signal VBV2, and an output switching circuit 252a-7 equivalent to the output switching circuit 252-7 that selects whether to output the drive voltage signal VBV3.

[0216] 2.1 Configuration of the output circuit of the second embodiment Fig. 18 is a diagram showing an example of the configuration of the output circuit 250 of the second embodiment. As shown in Fig. 18, the output circuit 250 has output switching circuits 252a-1 to 252a-7, similar to the first embodiment.

[0217] The output switching circuit 252a-1 of the second embodiment includes an inverter inv1 and a transfer gate tg1. A voltage selection signal S11 as the voltage selection signal S and a drive voltage signal VHV3 are input to the output switching circuit 252a-1. The voltage selection signal S11 is input to the positive control terminal of the transfer gate tg1, and after its logical level is inverted by the inverter inv1, it is also input to the negative control terminal marked with a circle of the transfer gate tg1. The drive voltage signal VHV3 is also input to the input terminal of the transfer gate tg1.

[0218] When an H-level voltage selection signal S11 is input to this output switching circuit 252a-1, conduction occurs between the input and output terminals of the transfer gate tg1, and when an L-level voltage selection signal S11 is input, conduction occurs between the input and output terminals of the transfer gate tg1. In other words, when an H-level voltage selection signal S11 is input to the output switching circuit 252a-1, the transfer gate tg1 supplies current to the output unit 600 or draws current from the output unit 600 so that the voltage value of the drive signal VOUT becomes voltage Vh3, which is the voltage value of the drive voltage signal VHV3.

[0219] In other words, the waveform selection control circuit 210 controls the output switching circuit 252a-1 based on the print data signal SI, and the output switching circuit 252a-1 switches whether or not to supply the drive voltage signal VHV3 to the ejection section 600.

[0220] The output switching circuit 252a-2 of the second embodiment includes an inverter inv2 and a transfer gate tg2. The output switching circuit 252a-2 receives a voltage selection signal S12 as the voltage selection signal S and a drive voltage signal VHV2. The voltage selection signal S12 is input to a positive control terminal of the transfer gate tg2, and after its logical level is inverted by the inverter inv2, it is also input to a negative control terminal marked with a circle of the transfer gate tg2. The drive voltage signal VHV2 is also input to an input terminal of the transfer gate tg2.

[0221] When an H-level voltage selection signal S12 is input to this output switching circuit 252a-1, conduction occurs between the input and output terminals of the transfer gate tg2, and when an L-level voltage selection signal S12 is input, conduction does not occur between the input and output terminals of the transfer gate tg2. In other words, when an H-level voltage selection signal S12 is input to the output switching circuit 252a-2, the transfer gate tg2 supplies current to the output unit 600 or draws current from the output unit 600 so that the voltage value of the drive signal VOUT becomes voltage Vh2, which is the voltage value of the drive voltage signal VHV2.

[0222] In other words, the waveform selection control circuit 210 controls the output switching circuit 252a-2 based on the print data signal SI, and the output switching circuit 252a-2 switches whether or not to supply the drive voltage signal VHV2 to the ejection section 600.

[0223] The output switching circuit 252a-3 of the second embodiment includes an inverter inv3 and a transfer gate tg3. A voltage selection signal S13 as the voltage selection signal S and a drive voltage signal VHV1 are input to the output switching circuit 252a-3. The voltage selection signal S13 is input to the positive control terminal of the transfer gate tg3, and after its logical level is inverted by the inverter inv3, it is also input to the negative control terminal marked with a circle of the transfer gate tg3. The drive voltage signal VHV1 is also input to the input terminal of the transfer gate tg3.

[0224] When an H-level voltage selection signal S13 is input to such an output switching circuit 252a-3, conduction occurs between the input and output terminals of the transfer gate tg3, and when an L-level voltage selection signal S13 is input, conduction does not occur between the input and output terminals of the transfer gate tg3. In other words, when an H-level voltage selection signal S13 is input to the output switching circuit 252a-3, the transfer gate tg3 supplies current to the output unit 600 or draws current from the output unit 600 so that the voltage value of the drive signal VOUT becomes voltage Vh1, which is the voltage value of the drive voltage signal VHV1.

[0225] In other words, the waveform selection control circuit 210 controls the output switching circuit 252a-3 based on the print data signal SI, and the output switching circuit 252a-3 switches whether or not to supply the drive voltage signal VHV1 to the ejection section 600.

[0226] The output switching circuit 252a-4 of the second embodiment includes an inverter inv4 and a transfer gate tg4. The output switching circuit 252a-4 receives a voltage selection signal S14 as the voltage selection signal S and a drive voltage signal VCV. The voltage selection signal S14 is input to the positive control terminal of the transfer gate tg4, and after its logical level is inverted by the inverter inv4, it is also input to the negative control terminal marked with a circle of the transfer gate tg4. The drive voltage signal VCV is also input to the input terminal of the transfer gate tg4.

[0227] When an H-level voltage selection signal S14 is input to this output switching circuit 252a-4, conduction occurs between the input and output terminals of the transfer gate tg4, and when an L-level voltage selection signal S14 is input, conduction does not occur between the input and output terminals of the transfer gate tg4. In other words, when an H-level voltage selection signal S14 is input to the output switching circuit 252a-4, the transfer gate tg4 supplies current to the output unit 600 or draws current from the output unit 600 so that the voltage value of the drive signal VOUT becomes voltage Vc, which is the voltage value of the drive voltage signal VCV.

[0228] In other words, the waveform selection control circuit 210 controls the output switching circuit 252a-4 based on the print data signal SI, and the output switching circuit 252a-4 switches whether or not to supply the drive voltage signal VCV to the discharger 600.

[0229] The output switching circuit 252a-5 of the second embodiment includes an inverter inv5 and a transfer gate tg5. The output switching circuit 252a-5 receives a voltage selection signal S15 as the voltage selection signal S and a drive voltage signal VBV1. The voltage selection signal S15 is input to the positive control terminal of the transfer gate tg5, and after its logical level is inverted by the inverter inv5, it is also input to the negative control terminal marked with a circle of the transfer gate tg5. The drive voltage signal VBV1 is also input to the input terminal of the transfer gate tg5.

[0230] When an H-level voltage selection signal S15 is input to such an output switching circuit 252a-5, conduction occurs between the input and output terminals of the transfer gate tg5, and when an L-level voltage selection signal S15 is input, conduction does not occur between the input and output terminals of the transfer gate tg5. In other words, when an H-level voltage selection signal S15 is input to the output switching circuit 252a-5, the transfer gate tg5 supplies current to the output unit 600 or draws current from the output unit 600 so that the voltage value of the drive signal VOUT becomes voltage Vb1, which is the voltage value of the drive voltage signal VBV1.

[0231] In other words, the waveform selection control circuit 210 controls the output switching circuit 252a-5 based on the print data signal SI, and the output switching circuit 252a-5 switches whether or not to supply the drive voltage signal VBV1 to the ejection section 600.

[0232] The output switching circuit 252a-6 of the second embodiment includes an inverter inv6 and a transfer gate tg6. The output switching circuit 252a-6 receives a voltage selection signal S16 as the voltage selection signal S and a drive voltage signal VBV2. The voltage selection signal S16 is input to the positive control terminal of the transfer gate tg6, and after its logical level is inverted by the inverter inv6, it is also input to the negative control terminal marked with a circle of the transfer gate tg6. The drive voltage signal VBV2 is also input to the input terminal of the transfer gate tg6.

[0233] When an H-level voltage selection signal S16 is input to such an output switching circuit 252a-6, conduction occurs between the input and output terminals of the transfer gate tg6, and when an L-level voltage selection signal S16 is input, conduction occurs between the input and output terminals of the transfer gate tg6. In other words, when an H-level voltage selection signal S16 is input to the output switching circuit 252a-6, the transfer gate tg6 supplies current to the output unit 600 or draws current from the output unit 600 so that the voltage value of the drive signal VOUT becomes voltage Vb2, which is the voltage value of the drive voltage signal VBV2.

[0234] In other words, the waveform selection control circuit 210 controls the output switching circuit 252a-6 based on the print data signal SI, and the output switching circuit 252a-6 switches whether or not to supply the drive voltage signal VBV2 to the discharger 600.

[0235] The output switching circuit 252a-7 of the second embodiment includes an inverter inv7 and a transfer gate tg7. The output switching circuit 252a-7 receives a voltage selection signal S17 as the voltage selection signal S and a drive voltage signal VBV3. The voltage selection signal S17 is input to the positive control terminal of the transfer gate tg7, and after its logical level is inverted by the inverter inv7, it is also input to the negative control terminal marked with a circle of the transfer gate tg7. The drive voltage signal VBV3 is also input to the input terminal of the transfer gate tg7.

[0236] When an H-level voltage selection signal S17 is input to such an output switching circuit 252a-7, conduction occurs between the input and output terminals of the transfer gate tg7, and when an L-level voltage selection signal S17 is input, conduction does not occur between the input and output terminals of the transfer gate tg7. In other words, when an H-level voltage selection signal S17 is input to the output switching circuit 252a-7, the transfer gate tg7 supplies current to the output unit 600 or draws current from the output unit 600 so that the voltage value of the drive signal VOUT becomes voltage Vb3, which is the voltage value of the drive voltage signal VBV3.

[0237] In other words, the waveform selection control circuit 210 controls the output switching circuit 252a-7 based on the print data signal SI, and the output switching circuit 252a-7 switches whether or not to supply the drive voltage signal VBV3 to the discharger 600.

[0238] Even in the liquid ejector 1 of the second embodiment having the output circuit 250 configured as described above, the waveform selection control circuit 210 outputs a voltage selection signal S of a predetermined logic level based on the latch signal LAT, change signals CHA, CHB, CHC, CHD, clock signal SCK, print data signal SI, and waveform information signal WI, and the output switching circuits 252a-1 to 252a-7 select or deselect each of the drive voltage signals VHV1, VHV2, VHV3, VCV, VBV1, VBV2, and VBV1 based on the logic level of the input voltage selection signal S, thereby generating a drive signal VOUT and outputting it to the corresponding ejection section 600. As a result, even in the liquid ejector 1 and head unit 20 of the second embodiment, it is possible to achieve the same effects as the liquid ejector 1 of the first embodiment.

[0239] 2.2 Modification of the output circuit of the second embodiment In the second embodiment of the liquid ejection device 1 described above, the output switching circuit 252a-1 of the output circuit 250 has one pair of transfer gate tg1 and inverter inv1, and is described as switching the conduction state between one end and the other end of the transfer gate tg1 to switch whether or not to output the drive voltage signal VHV3 as the drive signal VOUT, but the output switching circuit 252a-1 may have multiple pairs of transfer gate tg1 and inverter inv1.

[0240] Similarly, the output switching circuit 252a-2 may have multiple pairs of transfer gate tg2 and inverter inv2, the output switching circuit 252a-3 may have multiple pairs of transfer gate tg3 and inverter inv3, the output switching circuit 252a-4 may have multiple pairs of transfer gate tg4 and inverter inv4, the output switching circuit 252a-5 may have multiple pairs of transfer gate tg5 and inverter inv5, the output switching circuit 252a-6 may have multiple pairs of transfer gate tg6 and inverter inv6, and the output switching circuit 252a-7 may have multiple pairs of transfer gate tg7 and inverter inv7.

[0241] A specific example of the configuration of a modified example of the liquid ejection device 1 of the second embodiment will be described. Fig. 19 is a diagram showing an example of the configuration of an output switching circuit 252a-1 of the modified example of the second embodiment. As shown in Fig. 19, the output switching circuit 252a-1 of the modified example of the second embodiment includes transfer gates tg1-1 to tg1-4 and inverters inv1-1 to inv1-4. Furthermore, voltage selection signals S11-1, S11-2, S11-3, and S11-4 as the voltage selection signal S11, and a drive voltage signal VHV3 are input to the output switching circuit 252a-1 of the modified example of the second embodiment.

[0242] The voltage selection signal S11-1 is input to the positive control terminal of the transfer gate tg1-1, and after its logic level is inverted by the inverter inv1-1, it is also input to the negative control terminal marked with a circle of the transfer gate tg1-1. The drive voltage signal VHV3 is input to the input terminal of the transfer gate tg1-1. The voltage selection signal S11-2 is input to the positive control terminal of the transfer gate tg1-2, and after its logic level is inverted by the inverter inv1-2, it is also input to the negative control terminal marked with a circle of the transfer gate tg1-2. The drive voltage signal VHV3 is input to the input terminal of the transfer gate tg1-2. The voltage selection signal S11-3 is input to the positive control terminal of the transfer gate tg1-3, and after its logic level is inverted by the inverter inv1-3, it is also input to the negative control terminal marked with a circle of the transfer gate tg1-3. A drive voltage signal VHV3 is input to the input terminal of the transfer gate tg1-3. A voltage selection signal S11-4 is input to the positive control terminal of the transfer gate tg1-4, and after its logical level is inverted by an inverter inv1-4, it is also input to the negative control terminal marked with a circle of the transfer gate tg1-4. A drive voltage signal VHV3 is input to the input terminal of the transfer gate tg1-4. In the output switching circuit 252a-2, the output terminals of the transfer gates tg1-1 to tg1-4 are commonly connected. The output switching circuit 252a-1 of the modified example of the second embodiment outputs the signal from the output terminals of the commonly connected transfer gates tg1-1 to tg1-4 as a drive signal VOUT to the corresponding ejection unit 600.

[0243] When an H-level voltage selection signal S11-1 is input to the output switching circuit 252a-1 of the modified example of the second embodiment configured as described above, one end and the other end of the transfer gate tg1-1 are controlled to be conductive, and when an L-level voltage selection signal S11-1 is input, one end and the other end of the transfer gate tg1-1 are controlled to be non-conductive. Similarly, when an H-level voltage selection signal S11-2 is input to the output switching circuit 252a-1 of the modified example of the second embodiment, one end and the other end of the transfer gate tg1-2 are controlled to be conductive, and when an L-level voltage selection signal S11-2 is input, one end and the other end of the transfer gate tg1-2 are controlled to be non-conductive. Similarly, when an H-level voltage selection signal S11-3 is input to the output switching circuit 252a-1 of the modified example of the second embodiment, one end and the other end of the transfer gate tg1-3 are controlled to be conductive, and when an L-level voltage selection signal S11-3 is input, one end and the other end of the transfer gate tg1-3 are controlled to be non-conductive. Similarly, when an H-level voltage selection signal S11-4 is input to the output switching circuit 252a-1 of the modified example of the second embodiment, one end and the other end of the transfer gate tg1-4 are controlled to be conductive, and when an L-level voltage selection signal S11-4 is input, one end and the other end of the transfer gate tg1-4 are controlled to be non-conductive.

[0244] That is, in the output switching circuit 252a-1 of the modified example of the second embodiment, transfer gates tg1-1, tg1-2, tg1-3, and tg1-4 are connected in parallel between a wiring pattern to which the drive voltage signal VHV3 is supplied and a wiring pattern to which the drive signal VOUT is output. Each of the transfer gates tg1-1 to tg1-4 switches whether or not to output the drive signal VOUT corresponding to the voltage Vh3 based on the logic level of the corresponding voltage selection signal S11-1 to S11-4. Hereinafter, the voltage selection signals S11-1 to S11-4 may be collectively referred to as voltage selection signals S11 [S11-1, S11-2, S11-3, S11-4].

[0245] When the voltage selection signals S11 [S11-1, S11-2, S11-3, S11-4] = [H, L, L, L] are input to the output switching circuit 252a-1 of the modified example of the second embodiment configured as described above, the transfer gate tg1-1 is controlled so that one end and the other end are conductive, and the transfer gates tg1-2 to tg1-4 are controlled so that one end and the other end are non-conductive. At this time, the voltage value of the drive signal VOUT output by the output switching circuit 252a-1 rises or falls toward the voltage Vh3 in a time corresponding to a time constant determined by the resistance value of the on-resistance of the transfer gate tg1-1 and the capacitance component of the piezoelectric element 60 of the corresponding ejection portion 600.

[0246] Furthermore, when the voltage selection signal S11 [S11-1, S11-2, S11-3, S11-4] = [H, H, L, L] is input to the output switching circuit 252a-1 of the modified example of the second embodiment, the transfer gates tg1-1 and tg1-2 are controlled so that one end and the other end are conductive, and the transfer gates tg1-3 to tg1-4 are controlled so that one end and the other end are non-conductive. At this time, the voltage value of the drive signal VOUT output from the output switching circuit 252a-1 rises or falls toward the voltage Vh3 within a time period determined by the combined resistance of the resistance of the on-resistance of the transfer gate tg1-1 and the resistance of the on-resistance of the transfer gate tg1-2 and the capacitance component of the piezoelectric element 60 of the corresponding ejection portion 600.

[0247] Furthermore, when a voltage selection signal S11 [S11-1, S11-2, S11-3, S11-4] = [H, H, H, L] is input to the output switching circuit 252a-1 of the modified example of the second embodiment, the transfer gates tg1-1 to tg1-3 are controlled so that one end and the other end are conductive, and the transfer gate tg1-4 is controlled so that one end and the other end are non-conductive. At this time, the voltage value of the drive signal VOUT output from the output switching circuit 252a-1 rises or falls toward the voltage Vh3 within a time period determined by a combined resistance value of the resistance values ​​of the on-resistances of the transfer gates tg1-1, tg1-2, and tg1-1, and the capacitance component of the piezoelectric element 60 of the corresponding ejection portion 600.

[0248] Furthermore, when a voltage selection signal S11 [S11-1, S11-2, S11-3, S11-4] = [H, H, H, H] is input to the output switching circuit 252a-1 of the modified example of the second embodiment, the transfer gates tg1-1 to tg1-4 are controlled so that one end and the other end are conductive. At this time, the voltage value of the drive signal VOUT output from the output switching circuit 252a-1 rises or falls toward the voltage Vh3 within a time period determined by a combined resistance value of the on-resistances of the transfer gates tg1-1, tg1-2, tg1-3, and tg1-4, and the capacitance component of the piezoelectric element 60 of the corresponding ejection portion 600.

[0249] That is, the output switching circuit 252a-1 of the modified example of the second embodiment controls the time during which the voltage value of the drive signal VOUT output by the output switching circuit 252a-1 changes toward voltage Vh3, depending on the logical level of the input voltage selection signal S11 [S11-1, S11-2, S11-3, S11-4].

[0250] As described above, the output switching circuit 252a-1 of the modified example of the second embodiment includes a transfer gate tg1-1 having one end supplied with the drive voltage signal VHV3 and the other end electrically connected to the ejection section 600, a transfer gate tg1-2 having one end supplied with the drive voltage signal VHV3 and the other end electrically connected to the ejection section 600, a transfer gate tg1-3 having one end supplied with the drive voltage signal VHV3 and the other end electrically connected to the ejection section 600, and a transfer gate tg1-4 having one end supplied with the drive voltage signal VHV3 and the other end electrically connected to the ejection section 600. Then, the waveform selection control circuit 210 outputs voltage selection signals S11-1, S11-2, S11-3, and S11-4 based on the print data signal SI, so that the conduction state between one end and the other end of transfer gate tg1-1 is controlled by voltage selection signal S11-1, the conduction state between one end and the other end of transfer gate tg1-2 is controlled by voltage selection signal S11-2, the conduction state between one end and the other end of transfer gate tg1-3 is controlled by voltage selection signal S11-3, and the conduction state between one end and the other end of transfer gate tg1-4 is controlled by voltage selection signal S11-4.

[0251] Here, the output switching circuits 252a-2 to 252a-7 of the modified example of the second embodiment have the same configuration as the output switching circuit 252a-1 of the modified example of the second embodiment, except for the input and output signals, and therefore the configurations of the output switching circuits 252a-2 to 252a-7 of the modified example of the second embodiment are not shown in the figures and the description will be simplified.

[0252] The output switching circuit 252a-2 of the modified second embodiment receives voltage selection signals S12-1 to S12-4 as the voltage selection signal S12 and a drive voltage signal VHV2. The output switching circuit 252a-2 of the modified second embodiment also has transfer gates tg2-1, tg2-2, tg2-3, and tg2-4 connected in parallel between a wiring pattern to which the drive voltage signal VHV2 is supplied and a wiring pattern to which the drive signal VOUT is output. Each of the transfer gates tg2-1 to tg2-4 included in the output switching circuit 252a-2 of the modified second embodiment switches whether or not to output a drive signal VOUT corresponding to the voltage Vh2, based on the logic level of the corresponding voltage selection signal S12-1 to S12-4. In the following description, the voltage selection signals S12-1 to S12-4 may be collectively referred to as voltage selection signal S12 [S12-1, S12-2, S12-3, S12-4].

[0253] The output switching circuit 252a-2 of the modified example of the second embodiment configured as described above, like the output switching circuit 252a-1 of the modified example of the second embodiment, controls the conduction state of each of the transfer gates tg2-1 to tg2-4 according to the logic level of the input voltage selection signal S12 [S12-1, S12-2, S12-3, S12-4], thereby controlling the time during which the voltage value of the drive signal VOUT output by the output switching circuit 252a-2 changes toward the voltage Vh2.

[0254] That is, the output switching circuit 252a-2 of the modified example of the second embodiment includes a transfer gate tg2-1 having one end supplied with the drive voltage signal VHV2 and the other end electrically connected to the ejection section 600, a transfer gate tg2-2 having one end supplied with the drive voltage signal VHV2 and the other end electrically connected to the ejection section 600, a transfer gate tg2-3 having one end supplied with the drive voltage signal VHV2 and the other end electrically connected to the ejection section 600, and a transfer gate tg2-4 having one end supplied with the drive voltage signal VHV2 and the other end electrically connected to the ejection section 600. Then, the waveform selection control circuit 210 outputs voltage selection signals S12-1, S12-2, S12-3, and S12-4 based on the print data signal SI, so that the conduction state between one end and the other end of transfer gate tg2-1 is controlled by voltage selection signal S12-1, the conduction state between one end and the other end of transfer gate tg2-2 is controlled by voltage selection signal S12-2, the conduction state between one end and the other end of transfer gate tg2-3 is controlled by voltage selection signal S12-3, and the conduction state between one end and the other end of transfer gate tg2-4 is controlled by voltage selection signal S12-4.

[0255] Similarly, the output switching circuit 252a-3 of the modified second embodiment receives voltage selection signals S13-1 to S13-4 as the voltage selection signal S13 and a drive voltage signal VHV1. The output switching circuit 252a-3 of the modified second embodiment also has transfer gates tg3-1, tg3-2, tg3-3, and tg3-4 connected in parallel between the wiring pattern to which the drive voltage signal VHV1 is supplied and the wiring pattern to which the drive signal VOUT is output. Each of the transfer gates tg3-1 to tg3-4 included in the output switching circuit 252a-3 of the modified second embodiment switches whether or not to output the drive signal VOUT corresponding to the voltage Vh1, based on the logic level of the corresponding voltage selection signal S13-1 to S13-4. In the following description, the voltage selection signals S13-1 to S13-4 may be collectively referred to as voltage selection signal S13 [S13-1, S13-2, S13-3, S13-4].

[0256] The output switching circuit 252a-3 of the modified example of the second embodiment configured as described above, like the output switching circuit 252a-1 of the modified example of the second embodiment, controls the conduction state of each of the transfer gates tg3-1 to tg3-4 according to the logic level of the input voltage selection signal S13 [S13-1, S13-2, S13-3, S13-4], thereby controlling the time during which the voltage value of the drive signal VOUT output by the output switching circuit 252a-3 changes toward the voltage Vh1.

[0257] That is, the output switching circuit 252a-3 of the modified example of the second embodiment includes a transfer gate tg3-1 having one end supplied with the drive voltage signal VHV1 and the other end electrically connected to the ejection section 600, a transfer gate tg3-2 having one end supplied with the drive voltage signal VHV1 and the other end electrically connected to the ejection section 600, a transfer gate tg3-3 having one end supplied with the drive voltage signal VHV1 and the other end electrically connected to the ejection section 600, and a transfer gate tg3-4 having one end supplied with the drive voltage signal VHV1 and the other end electrically connected to the ejection section 600. Then, the waveform selection control circuit 210 outputs voltage selection signals S13-1, S13-2, S13-3, and S13-4 based on the print data signal SI, so that the conduction state between one end and the other end of transfer gate tg3-1 is controlled by voltage selection signal S13-1, the conduction state between one end and the other end of transfer gate tg3-2 is controlled by voltage selection signal S13-2, the conduction state between one end and the other end of transfer gate tg3-3 is controlled by voltage selection signal S13-3, and the conduction state between one end and the other end of transfer gate tg3-4 is controlled by voltage selection signal S13-4.

[0258] Similarly, the output switching circuit 252a-4 of the modified second embodiment receives voltage selection signals S14-1 to S14-4 as the voltage selection signal S14 and a drive voltage signal VCV. The output switching circuit 252a-4 of the modified second embodiment also has transfer gates tg4-1, tg4-2, tg4-3, and tg4-4 connected in parallel between the wiring pattern to which the drive voltage signal VCV is supplied and the wiring pattern to which the drive signal VOUT is output. Each of the transfer gates tg4-1 to tg4-4 included in the output switching circuit 252a-4 of the modified second embodiment switches whether or not to output the drive signal VOUT corresponding to the voltage Vc, based on the logic level of the corresponding voltage selection signal S14-1 to S14-4. In the following description, the voltage selection signals S14-1 to S14-4 may be collectively referred to as voltage selection signal S14 [S14-1, S14-2, S14-3, S14-4].

[0259] The output switching circuit 252a-4 of the modified example of the second embodiment configured as described above, like the output switching circuit 252a-1 of the modified example of the second embodiment, controls the conduction state of each of the transfer gates tg4-1 to tg4-4 in accordance with the logic level of the input voltage selection signal S14 [S14-1, S14-2, S14-3, S14-4], thereby controlling the time it takes for the voltage value of the drive signal VOUT output by the output switching circuit 252a-4 to change towards the voltage Vc.

[0260] That is, the output switching circuit 252a-4 of the modified example of the second embodiment includes a transfer gate tg4-1 having one end supplied with the drive voltage signal VCV and the other end electrically connected to the ejection section 600, a transfer gate tg4-2 having one end supplied with the drive voltage signal VCV and the other end electrically connected to the ejection section 600, a transfer gate tg4-3 having one end supplied with the drive voltage signal VCV and the other end electrically connected to the ejection section 600, and a transfer gate tg4-4 having one end supplied with the drive voltage signal VCV and the other end electrically connected to the ejection section 600. Then, the waveform selection control circuit 210 outputs voltage selection signals S14-1, S14-2, S14-3, and S14-4 based on the print data signal SI, so that the conduction state between one end and the other end of transfer gate tg4-1 is controlled by voltage selection signal S14-1, the conduction state between one end and the other end of transfer gate tg4-2 is controlled by voltage selection signal S14-2, the conduction state between one end and the other end of transfer gate tg4-3 is controlled by voltage selection signal S14-3, and the conduction state between one end and the other end of transfer gate tg4-4 is controlled by voltage selection signal S14-4.

[0261] Similarly, the output switching circuit 252a-5 of the modified second embodiment receives voltage selection signals S15-1 to S15-4 as the voltage selection signal S15 and a drive voltage signal VBV1. The output switching circuit 252a-5 of the modified second embodiment also has transfer gates tg5-1, tg5-2, tg5-3, and tg5-4 connected in parallel between the wiring pattern to which the drive voltage signal VBV1 is supplied and the wiring pattern to which the drive signal VOUT is output. Each of the transfer gates tg5-1 to tg5-4 included in the output switching circuit 252a-5 of the modified second embodiment switches whether or not to output the drive signal VOUT corresponding to the voltage Vb1, based on the logic level of the corresponding voltage selection signal S15-1 to S15-4. In the following description, the voltage selection signals S15-1 to S15-4 may be collectively referred to as voltage selection signal S15 [S15-1, S15-2, S15-3, S15-4].

[0262] The output switching circuit 252a-5 of the modified example of the second embodiment configured as described above, like the output switching circuit 252a-1 of the modified example of the second embodiment, controls the conduction state of each of the transfer gates tg5-1 to tg5-4 according to the logic level of the input voltage selection signal S15 [S15-1, S15-2, S15-3, S15-4], thereby controlling the time it takes for the voltage value of the drive signal VOUT output by the output switching circuit 252a-5 to change towards voltage Vb1.

[0263] That is, the output switching circuit 252a-5 of the modified example of the second embodiment includes a transfer gate tg5-1 having one end supplied with the drive voltage signal VBV1 and the other end electrically connected to the ejection section 600, a transfer gate tg5-2 having one end supplied with the drive voltage signal VBV1 and the other end electrically connected to the ejection section 600, a transfer gate tg5-3 having one end supplied with the drive voltage signal VBV1 and the other end electrically connected to the ejection section 600, and a transfer gate tg5-4 having one end supplied with the drive voltage signal VBV1 and the other end electrically connected to the ejection section 600. Then, the waveform selection control circuit 210 outputs voltage selection signals S15-1, S15-2, S15-3, and S15-4 based on the print data signal SI, so that the conduction state between one end and the other end of transfer gate tg5-1 is controlled by voltage selection signal S15-1, the conduction state between one end and the other end of transfer gate tg5-2 is controlled by voltage selection signal S15-2, the conduction state between one end and the other end of transfer gate tg5-3 is controlled by voltage selection signal S15-3, and the conduction state between one end and the other end of transfer gate tg5-4 is controlled by voltage selection signal S15-4.

[0264] Similarly, the output switching circuit 252a-6 of the modified second embodiment receives voltage selection signals S16-1 to S16-4 as the voltage selection signal S16 and a drive voltage signal VBV2. The output switching circuit 252a-6 of the modified second embodiment also has transfer gates tg6-1, tg6-2, tg6-3, and tg6-4 connected in parallel between the wiring pattern to which the drive voltage signal VBV2 is supplied and the wiring pattern to which the drive signal VOUT is output. Each of the transfer gates tg6-1 to tg6-4 included in the output switching circuit 252a-6 of the modified second embodiment switches whether or not to output the drive signal VOUT corresponding to the voltage Vb2, based on the logic level of the corresponding voltage selection signal S16-1 to S16-4. In the following description, the voltage selection signals S16-1 to S16-4 may be collectively referred to as voltage selection signal S16 [S16-1, S16-2, S16-3, S16-4].

[0265] The output switching circuit 252a-6 of the modified example of the second embodiment configured as described above, like the output switching circuit 252a-1 of the modified example of the second embodiment, controls the conduction state of each of the transfer gates tg6-1 to tg6-4 in accordance with the logic level of the input voltage selection signal S16 [S16-1, S16-2, S16-3, S16-4], thereby controlling the time it takes for the voltage value of the drive signal VOUT output by the output switching circuit 252a-6 to change toward voltage Vb2.

[0266] That is, the output switching circuit 252a-6 of the modified example of the second embodiment includes a transfer gate tg6-1 having one end supplied with the drive voltage signal VBV2 and the other end electrically connected to the ejection section 600, a transfer gate tg6-2 having one end supplied with the drive voltage signal VBV2 and the other end electrically connected to the ejection section 600, a transfer gate tg6-3 having one end supplied with the drive voltage signal VBV2 and the other end electrically connected to the ejection section 600, and a transfer gate tg6-4 having one end supplied with the drive voltage signal VBV2 and the other end electrically connected to the ejection section 600. Then, the waveform selection control circuit 210 outputs voltage selection signals S16-1, S16-2, S16-3, and S16-4 based on the print data signal SI, so that the conduction state between one end and the other end of transfer gate tg6-1 is controlled by voltage selection signal S16-1, the conduction state between one end and the other end of transfer gate tg6-2 is controlled by voltage selection signal S16-2, the conduction state between one end and the other end of transfer gate tg6-3 is controlled by voltage selection signal S16-3, and the conduction state between one end and the other end of transfer gate tg6-4 is controlled by voltage selection signal S16-4.

[0267] Similarly, the output switching circuit 252a-7 of the modified second embodiment receives voltage selection signals S17-1 to S17-4 as the voltage selection signal S17 and a drive voltage signal VBV3. The output switching circuit 252a-7 of the modified second embodiment also has transfer gates tg7-1, tg7-2, tg7-3, and tg7-4 connected in parallel between the wiring pattern to which the drive voltage signal VBV3 is supplied and the wiring pattern to which the drive signal VOUT is output. Each of the transfer gates tg7-1 to tg7-4 included in the output switching circuit 252a-7 of the modified second embodiment switches whether or not to output a drive signal VOUT corresponding to the voltage Vb3, based on the logic level of the corresponding voltage selection signal S17-1 to S17-4. In the following description, the voltage selection signals S17-1 to S17-4 may be collectively referred to as voltage selection signal S17 [S17-1, S17-2, S17-3, S17-4].

[0268] The output switching circuit 252a-7 of the modified example of the second embodiment configured as described above, like the output switching circuit 252a-1 of the modified example of the second embodiment, controls the conduction state of each of the transfer gates tg7-1 to tg7-4 according to the logic level of the input voltage selection signal S17 [S17-1, S17-2, S17-3, S17-4], thereby controlling the time it takes for the voltage value of the drive signal VOUT output by the output switching circuit 252a-7 to change towards voltage Vb3.

[0269] That is, the output switching circuit 252a-7 of the modified example of the second embodiment includes a transfer gate tg7-1 having one end supplied with the drive voltage signal VBV3 and the other end electrically connected to the ejection section 600, a transfer gate tg7-2 having one end supplied with the drive voltage signal VBV3 and the other end electrically connected to the ejection section 600, a transfer gate tg7-3 having one end supplied with the drive voltage signal VBV3 and the other end electrically connected to the ejection section 600, and a transfer gate tg7-4 having one end supplied with the drive voltage signal VBV3 and the other end electrically connected to the ejection section 600. Then, the waveform selection control circuit 210 outputs voltage selection signals S17-1, S17-2, S17-3, and S17-4 based on the print data signal SI, so that the conduction state between one end and the other end of transfer gate tg7-1 is controlled by voltage selection signal S17-1, the conduction state between one end and the other end of transfer gate tg7-2 is controlled by voltage selection signal S17-2, the conduction state between one end and the other end of transfer gate tg7-3 is controlled by voltage selection signal S17-3, and the conduction state between one end and the other end of transfer gate tg7-4 is controlled by voltage selection signal S17-4.

[0270] In the liquid ejector 1 of the modified example of the second embodiment configured as described above, the slope of the signal waveform of the drive signal VOUT can be controlled by controlling the time required for a change in the voltage value of the drive signal VOUT output by each of the output switching circuits 252a-1 to 252a-7 of the output circuit 250. Therefore, in addition to the effects of the liquid ejector 1 of the second embodiment described above, the drive signal output circuit 200 can output an optimum waveform of the drive signal VOUT depending on the usage environment of the liquid ejector 1 and the physical properties of the ink used, thereby improving the versatility of the liquid ejector 1.

[0271] Here, the drive voltage signal VCV is an example of a first DC voltage signal, the voltage Vc is an example of a first voltage value, any of the drive voltage signals VBV1, VBV2, and VBV3 is an example of a second DC voltage signal, any of the corresponding voltages Vb1, Vb2, and Vb3 is an example of a second voltage value, any of the drive voltage signals VHV1, VHV2, and VHV3 is an example of a third DC voltage signal, and any of the corresponding voltages Vc1, Vc2, and Vc3 is an example of a third voltage value. The print data signal SI is an example of an ejection control signal. The output switching circuit 252a-4 of the output circuit 250 is an example of a first switch circuit, the transfer gate tg4-1 is an example of a first switch element, the transfer gate tg4-2 is an example of a second switch element, the voltage selection signal S14-1 is an example of a first switch control signal, and the voltage selection signal S14-2 is an example of a second switch control signal. Furthermore, any one of the output switching circuits 252a-5, 252a-6, and 252a-7 is an example of a second switch circuit, the corresponding transfer gates tg5-1, tg6-1, and tg6-1 are an example of a third switch element, the corresponding transfer gates tg5-2, tg6-2, and tg6-2 are an example of a fourth switch element, the corresponding voltage selection signals S15-1, S16-1, and S17-1 are an example of a third switch control signal, and the corresponding voltage selection signals S15-2, S16-2, and S17-2 are an example of a fourth switch control signal. Further, any one of the output switching circuits 252a-1, 252a-2, and 252a-3 is an example of a third switch circuit, the corresponding transfer gates tg1-1, tg2-1, and tg3-1 are examples of fifth switch elements, the corresponding transfer gates tg1-2, tg2-2, and tg3-2 are examples of sixth switch elements, the corresponding voltage selection signals S11-1, S12-1, and S13-1 are examples of fifth switch control signals, and the corresponding voltage selection signals S11-2, S12-2, and S13-2 are examples of sixth switch control signals. Further, the drive waveform DEP is an example of an ejection waveform, the drive waveform BSD is an example of a micro-vibration waveform, and the drive waveform NVT is an example of an inspection waveform.

[0272] Although the embodiments and modifications have been described above, the present invention is not limited to these embodiments and can be embodied in various forms without departing from the spirit of the present invention. For example, the above embodiments can be combined as appropriate.

[0273] 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 effects). The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that achieve the same effects as the configurations described in the embodiments or that can achieve the same purpose. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments.

[0274] The following can be derived from the above-described embodiment.

[0275] One aspect of the head unit is a discharge unit including a piezoelectric element that is driven by a drive signal and that discharges liquid by driving the piezoelectric element; a drive signal output circuit that receives a first DC voltage signal having a first voltage value, a second DC voltage signal having a second voltage value, and an ejection control signal, and outputs the drive signal; Equipped with The drive signal output circuit a first switch circuit that switches whether or not the first DC voltage signal is supplied to the discharge unit; a second switch circuit that switches whether or not the second DC voltage signal is supplied to the discharge unit; a selection control circuit that controls the first switch circuit and the second switch circuit based on the ejection control signal; and The first switch circuit includes a first switch element having one end supplied with the first DC voltage signal and the other end electrically connected to the discharge portion, and a second switch element having one end supplied with the first DC voltage signal and the other end electrically connected to the discharge portion.

[0276] According to this head unit, there is no need to use an amplifier circuit to generate the first drive signal, and therefore it is possible to reduce power loss that may occur in the amplifier circuit.

[0277] In one aspect of the head unit, the selection control circuit outputs a first switch control signal and a second switch control signal based on the ejection control signal; a conduction state between one end and the other end of the first switch element is controlled by the first switch control signal; The conduction state between one end and the other end of the second switch element may be controlled by the second switch control signal.

[0278] With this head unit, the conduction states of the first switch element and the second switch element can be set arbitrarily, allowing the slope of the signal waveform of the first drive signal to be set arbitrarily, which increases the variety of signal waveforms of the output first drive signal and improves the versatility of the head unit.

[0279] In one aspect of the head unit, the second switch circuit includes a third switch element having one end supplied with the second DC voltage signal and the other end electrically connected to the discharge portion, and a fourth switch element having one end supplied with the second DC voltage signal and the other end electrically connected to the discharge portion, the selection control circuit outputs a third switch control signal and a fourth switch control signal based on the ejection control signal; a conduction state between one end and the other end of the third switch element is controlled by the third switch control signal; The conduction state between one end and the other end of the fourth switch element may be controlled by the fourth switch control signal.

[0280] This head unit includes a third switch element and a fourth switch element, and the conductive states of the third switch element and the fourth switch element can be set arbitrarily, thereby allowing the slope of the signal waveform of the first drive signal to be set arbitrarily. As a result, the number of types of signal waveforms of the output first drive signal increases, further increasing the versatility of the head unit.

[0281] In one aspect of the head unit, a third DC voltage signal having a third voltage value is further input to the drive signal output circuit; the drive signal output circuit has a third switch circuit that switches whether or not the third DC voltage signal is supplied to the ejection unit, The third switch circuit may include a fifth switch element having one end supplied with the third DC voltage signal and the other end electrically connected to the discharge portion, and a sixth switch element having one end supplied with the third DC voltage signal and the other end electrically connected to the discharge portion.

[0282] According to this head unit, by further generating the first drive signal using a third DC voltage signal having a third voltage value, the number of types of signal waveforms of the output first drive signal increases, further increasing the versatility of the head unit.

[0283] In one aspect of the head unit, the selection control circuit outputs a fifth switch control signal and a sixth switch control signal based on the ejection control signal; a conduction state between one end and the other end of the fifth switch element is controlled by the fifth switch control signal, The conduction state between one end and the other end of the sixth switch element may be controlled by the sixth switch control signal.

[0284] With this head unit, the conduction states of the fifth switch element and the sixth switch element can be set arbitrarily, allowing the slope of the signal waveform of the first drive signal to be set arbitrarily, thereby increasing the variety of signal waveforms of the output first drive signal and further increasing the versatility of the head unit.

[0285] In one aspect of the head unit, The drive signal output circuit may output the drive signal including an ejection waveform that drives the piezoelectric element so as to eject liquid from the ejection portion.

[0286] In one aspect of the head unit, The drive signal output circuit may output the drive signal including a micro-vibration waveform that drives the piezoelectric element so as to prevent liquid from being ejected from the ejection portion.

[0287] In one aspect of the head unit, The drive signal output circuit may output the drive signal including a test waveform for testing the state of the ejection portion.

[0288] In one aspect of the head unit, The first voltage value and the second voltage value may be changeable.

[0289] One aspect of the liquid ejection device is a discharge unit including a piezoelectric element that is driven by a drive signal and that discharges liquid by driving the piezoelectric element; a drive signal output circuit that receives a first DC voltage signal having a first voltage value, a second DC voltage signal having a second voltage value, and an ejection control signal, and outputs the drive signal; a control circuit that outputs the ejection control signal; Equipped with The drive signal output circuit a first switch circuit that switches whether or not the first DC voltage signal is supplied to the discharge unit; a second switch circuit that switches whether or not the second DC voltage signal is supplied to the discharge unit; a selection control circuit that controls the first switch circuit and the second switch circuit based on the ejection control signal; and The first switch circuit includes a first switch element having one end supplied with the first DC voltage signal and the other end electrically connected to the discharge portion, and a second switch element having one end supplied with the first DC voltage signal and the other end electrically connected to the discharge portion.

[0290] According to this liquid ejection device, there is no need to use an amplifier circuit to generate the first drive signal, and therefore it is possible to reduce power loss that may occur in the amplifier circuit.

[0291] In one aspect of the liquid ejection device, the selection control circuit outputs a first switch control signal and a second switch control signal based on the ejection control signal; a conduction state between one end and the other end of the first switch element is controlled by the first switch control signal; The conduction state between one end and the other end of the second switch element may be controlled by the second switch control signal.

[0292] According to this liquid ejection device, the conduction states of the first switch element and the second switch element can be set arbitrarily, and the slope of the signal waveform of the first drive signal can be set arbitrarily. As a result, the number of types of signal waveforms of the output first drive signal increases, and the versatility of the head unit is improved.

[0293] In one aspect of the liquid ejection device, the second switch circuit includes a third switch element having one end supplied with the second DC voltage signal and the other end electrically connected to the discharge portion, and a fourth switch element having one end supplied with the second DC voltage signal and the other end electrically connected to the discharge portion, the selection control circuit outputs a third switch control signal and a fourth switch control signal based on the ejection control signal; a conduction state between one end and the other end of the third switch element is controlled by the third switch control signal; The conduction state between one end and the other end of the fourth switch element may be controlled by the fourth switch control signal.

[0294] This liquid ejection device includes a third switch element and a fourth switch element, and the conductive states of the third switch element and the fourth switch element can be set arbitrarily, thereby allowing the slope of the signal waveform of the first drive signal to be set arbitrarily.As a result, the number of types of signal waveforms of the output first drive signal increases, further increasing the versatility of the head unit.

[0295] In one aspect of the liquid ejection device, a third DC voltage signal having a third voltage value is further input to the drive signal output circuit; the drive signal output circuit has a third switch circuit that switches whether or not the third DC voltage signal is supplied to the ejection unit, The third switch circuit may include a fifth switch element having one end supplied with the third DC voltage signal and the other end electrically connected to the discharge portion, and a sixth switch element having one end supplied with the third DC voltage signal and the other end electrically connected to the discharge portion.

[0296] According to this liquid ejection device, by further generating the first drive signal using a third DC voltage signal having a third voltage value, the number of types of signal waveforms of the output first drive signal increases, further increasing the versatility of the head unit.

[0297] In one aspect of the liquid ejection device, the selection control circuit outputs a fifth switch control signal and a sixth switch control signal based on the ejection control signal; a conduction state between one end and the other end of the fifth switch element is controlled by the fifth switch control signal, The conduction state between one end and the other end of the sixth switch element may be controlled by the sixth switch control signal.

[0298] According to this liquid ejection device, the conduction states of the fifth switch element and the sixth switch element can be set arbitrarily, and the slope of the signal waveform of the first drive signal can be set arbitrarily. As a result, the number of types of signal waveforms of the output first drive signal increases, further increasing the versatility of the head unit.

[0299] In one aspect of the liquid ejection device, The drive signal output circuit may output the drive signal including an ejection waveform that drives the piezoelectric element so as to eject liquid from the ejection portion.

[0300] In one aspect of the liquid ejection device, The drive signal output circuit may output the drive signal including a micro-vibration waveform that drives the piezoelectric element so as to prevent liquid from being ejected from the ejection portion.

[0301] In one aspect of the liquid ejection device, The drive signal output circuit may output the drive signal including a test waveform for testing the state of the ejection portion.

[0302] In one aspect of the liquid ejection device, The first voltage value and the second voltage value may be changeable. [Explanation of symbols]

[0303] 1...liquid ejection device, 5...ink container, 10...control unit, 20...head unit, 21...print head, 40...transport unit, 41...transport motor, 42...transport roller, 50...constant voltage output circuit, 60...piezoelectric element, 100...control circuit, 200...drive signal output circuit, 210...waveform selection control circuit, 212...register, 214...latch circuit, 216...decoder, 230...waveform information storage circuit, 250...output circuit, 252-1 to 252-7, 252a-1 to 252a-7...output switching circuit, 300...head chip, 310...nozzle plate, 320...flow path forming substrate, 330...pressure chamber substrate, 340...protection Substrate, 350... compliance portion, 351... sealing film, 352... support, 360... vibration plate, 370... case, 400... flexible wiring substrate, 410... semiconductor device, 600... ejection portion, 610... ink flow path, 611... liquid inlet, 612... reservoir, 613... pressure chamber, 614... individual flow path, 615... communicating flow path, 616... reservoir, 651... nozzle, P... medium, ci1 to ci6, co2 to co7... constant current circuit, inv1 to inv7... inverter, sw1a to sw6a, sw2a to sw7b... switches, tg1 to tg7... transfer gate, ws2a to ws6a, ws2b to ws7b... switches

Claims

1. an ejection section including a piezoelectric element that is driven by a drive signal and that ejects liquid by driving the piezoelectric element; a drive signal output circuit which receives a first DC voltage signal having a first voltage value, a second DC voltage signal having a second voltage value, and an ejection control signal, and outputs the drive signal; Equipped with The drive signal output circuit includes: a first switch circuit that switches whether or not the first DC voltage signal is supplied to the discharge unit; a second switch circuit that switches whether or not the second DC voltage signal is supplied to the discharge unit; a selection control circuit that controls the first switch circuit and the second switch circuit based on the ejection control signal; having the first switch circuit includes a first switch element having one end to which the first DC voltage signal is supplied and the other end electrically connected to the discharge portion, and a second switch element having one end to which the first DC voltage signal is supplied and the other end electrically connected to the discharge portion, A head unit characterized by:

2. The selection control circuit outputs a first switch control signal and a second switch control signal based on the ejection control signal, a conductive state between one end and the other end of the first switch element is controlled by the first switch control signal; A conductive state between one end and the other end of the second switch element is controlled by the second switch control signal.

2. The head unit according to claim 1.

3. the second switch circuit includes a third switch element having one end to which the second DC voltage signal is supplied and the other end electrically connected to the discharge portion, and a fourth switch element having one end to which the second DC voltage signal is supplied and the other end electrically connected to the discharge portion, the selection control circuit outputs a third switch control signal and a fourth switch control signal based on the ejection control signal; a conductive state between one end and the other end of the third switch element is controlled by the third switch control signal, A conductive state between one end and the other end of the fourth switch element is controlled by the fourth switch control signal.

3. The head unit according to claim 2.

4. a third DC voltage signal having a third voltage value is further input to the drive signal output circuit; the drive signal output circuit has a third switch circuit that switches whether or not the third DC voltage signal is supplied to the ejection unit, the third switch circuit includes a fifth switch element having one end to which the third DC voltage signal is supplied and the other end electrically connected to the discharge portion, and a sixth switch element having one end to which the third DC voltage signal is supplied and the other end electrically connected to the discharge portion.

4. The head unit according to claim 3.

5. The selection control circuit outputs a fifth switch control signal and a sixth switch control signal based on the ejection control signal, a conductive state between one end and the other end of the fifth switch element is controlled by the fifth switch control signal, A conductive state between one end and the other end of the sixth switch element is controlled by the sixth switch control signal.

5. The head unit according to claim 4.

6. the drive signal output circuit outputs the drive signal including an ejection waveform that drives the piezoelectric element so as to eject liquid from the ejection portion.

2. The head unit according to claim 1.

7. the drive signal output circuit outputs the drive signal including a micro-vibration waveform that drives the piezoelectric element so as to prevent liquid from being ejected from the ejection portion.

2. The head unit according to claim 1.

8. the drive signal output circuit outputs the drive signal including a test waveform for testing a state of the ejection unit.

2. The head unit according to claim 1.

9. The first voltage value and the second voltage value are variable.

2. The head unit according to claim 1.

10. an ejection section including a piezoelectric element that is driven by a drive signal and that ejects liquid by driving the piezoelectric element; a drive signal output circuit which receives a first DC voltage signal having a first voltage value, a second DC voltage signal having a second voltage value, and an ejection control signal, and outputs the drive signal; A control circuit that outputs the ejection control signal; Equipped with The drive signal output circuit includes: a first switch circuit that switches whether or not the first DC voltage signal is supplied to the discharge unit; a second switch circuit that switches whether or not the second DC voltage signal is supplied to the discharge unit; a selection control circuit that controls the first switch circuit and the second switch circuit based on the ejection control signal; having the first switch circuit includes a first switch element having one end to which the first DC voltage signal is supplied and the other end electrically connected to the discharge portion, and a second switch element having one end to which the first DC voltage signal is supplied and the other end electrically connected to the discharge portion, A liquid ejection device comprising:

11. The selection control circuit outputs a first switch control signal and a second switch control signal based on the ejection control signal, a conductive state between one end and the other end of the first switch element is controlled by the first switch control signal; A conductive state between one end and the other end of the second switch element is controlled by the second switch control signal. The liquid ejection device according to claim 10 .

12. the second switch circuit includes a third switch element having one end to which the second DC voltage signal is supplied and the other end electrically connected to the discharge portion, and a fourth switch element having one end to which the second DC voltage signal is supplied and the other end electrically connected to the discharge portion, the selection control circuit outputs a third switch control signal and a fourth switch control signal based on the ejection control signal; a conductive state between one end and the other end of the third switch element is controlled by the third switch control signal, A conductive state between one end and the other end of the fourth switch element is controlled by the fourth switch control signal. The liquid ejection device according to claim 11 .

13. a third DC voltage signal having a third voltage value is further input to the drive signal output circuit; the drive signal output circuit has a third switch circuit that switches whether or not the third DC voltage signal is supplied to the ejection unit, the third switch circuit includes a fifth switch element having one end to which the third DC voltage signal is supplied and the other end electrically connected to the discharge portion, and a sixth switch element having one end to which the third DC voltage signal is supplied and the other end electrically connected to the discharge portion. The liquid ejection device according to claim 12 .

14. The selection control circuit outputs a fifth switch control signal and a sixth switch control signal based on the ejection control signal, a conductive state between one end and the other end of the fifth switch element is controlled by the fifth switch control signal, A conductive state between one end and the other end of the sixth switch element is controlled by the sixth switch control signal. The liquid ejection device according to claim 13 .

15. the drive signal output circuit outputs the drive signal including an ejection waveform that drives the piezoelectric element so as to eject liquid from the ejection portion. The liquid ejection device according to claim 10 .

16. the drive signal output circuit outputs the drive signal including a micro-vibration waveform that drives the piezoelectric element so as to prevent liquid from being ejected from the ejection portion. The liquid ejection device according to claim 10 .

17. the drive signal output circuit outputs the drive signal including a test waveform for testing a state of the ejection unit. The liquid ejection device according to claim 10 .

18. The first voltage value and the second voltage value are variable. The liquid ejection device according to claim 10 .

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