Liquid dispensing device

Abstract

To provide a liquid dispensing device that can improve the accuracy of residual vibration detection. [Solution] A liquid dispensing device comprising: a dispensing unit for dispensing liquid; a residual vibration detection circuit that acquires a residual vibration signal corresponding to residual vibration generated in the dispensing unit and outputs a residual vibration detection signal corresponding to the residual vibration signal; a determination circuit that determines the state of the dispensing unit according to the residual vibration detection signal; a first switch circuit that switches whether or not to supply the residual vibration signal to the residual vibration detection circuit; and a power supply circuit that receives a first power supply signal and outputs a second power supply signal to the first switch circuit, wherein the power supply circuit includes a linear power supply circuit that receives a first power supply signal and outputs a first voltage signal, and a switching power supply circuit that receives a first power supply signal and outputs a second voltage signal, and outputs either the first voltage signal or the second voltage signal as the second power supply signal.

Description

【Technical Field】 【0001】 The present invention relates to a liquid ejection device. 【Background Art】 【0002】 As disclosed in Patent Document 1, in a liquid ejection device that ejects liquid in response to a pressure change in a pressure chamber, a technique for determining the state of a discharge unit based on residual vibration that occurs after the pressure in the pressure chamber changes is known. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2022-098988 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 However, from the viewpoint of further improving the detection accuracy of residual vibration, the technique described in Patent Document 1 alone is not sufficient, and there is room for improvement. 【Means for Solving the Problems】 【0005】 One aspect of the liquid ejection device according to the present invention is a discharge unit that discharges liquid, a residual vibration detection circuit that acquires a residual vibration signal corresponding to the residual vibration generated in the discharge unit and outputs a residual vibration detection signal corresponding to the residual vibration signal, a determination circuit that determines the state of the discharge unit according to the residual vibration detection signal, a first switch circuit that switches whether or not to supply the residual vibration signal to the residual vibration detection circuit, a power supply circuit to which a first power signal is input and that outputs a second power signal to the first switch circuit, and includes the power supply circuit is A linear power supply circuit to which the first power supply signal is supplied and which outputs a first voltage signal, A switching power supply circuit to which the first power supply signal is supplied and which outputs a second voltage signal, Includes, The first voltage signal or the second voltage signal is output as the second power supply signal. [Brief explanation of the drawing] 【0006】 [Figure 1] This figure shows an example of the functional configuration of a liquid dispensing device. [Figure 2] This figure shows an example of a schematic internal structure of a liquid dispensing device. [Figure 3] This is a diagram showing the schematic structure of the discharge section. [Figure 4] This is a diagram showing an example of nozzle arrangement. [Figure 5] This figure shows an example of the functional configuration of a power supply unit. [Figure 6] This figure shows an example of the functional configuration of a head unit. [Figure 7] This diagram shows an example of the configuration of switch W. [Figure 8] This diagram illustrates an example of various signals input to a connection status specification circuit. [Figure 9] This figure shows an example of the configuration of a waveform shaping circuit. [Figure 10] This diagram illustrates an example of the various signals output by the control unit during the dispensing process. [Figure 11] This figure shows an example of the relationship between the individual designation signal Sd[m] and the connection status designation signals Qc[m] and Qs[m] during the period in which the discharge process is being performed. [Figure 12] This diagram illustrates an example of the various signals input to the head unit's power supply switching circuit during the period in which the judgment process is being executed. [Figure 13] This figure shows an example of the relationship between the individual designation signal Sd[m] and the connection status designation signals Qc[m] and Qs[m] during the period in which the judgment process is being executed. [Figure 14] It is a diagram showing an example of the relationship between the individual designation signal Sd[m] and the connection state designation signals Qf, Q1, and Q2 during the period when the determination process is being executed. [Figure 15] It is a diagram for explaining an example of the operation of acquiring a detection potential signal based on a signal corresponding to residual vibration generated in the discharge unit D[m] to be inspected. [Figure 16] It is a diagram showing an example of the functional configuration of the power supply unit included in the liquid discharge device of the second embodiment. [Figure 17] It is a diagram showing an example of the functional configuration of the power supply unit included in the liquid discharge device of the third embodiment. [Figure 18] It is a diagram showing an example of the functional configuration of the power supply unit included in the liquid discharge device of the fourth embodiment. 【Mode for Carrying Out the Invention】 【0007】 Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The drawings used are for convenience of explanation. Note that the embodiments described below do not unduly limit the content of the present invention described in the claims. Also, not all of the configurations described below are essential constituent elements of the present invention. 【0008】 1. First Embodiment 1.1 Outline of the Liquid Discharge Device In this embodiment, as the liquid discharge device 1, an inkjet printer that discharges ink as an example of a liquid onto a medium such as recording paper and forms an image on the medium will be exemplified and described. Note that the liquid discharge device 1 is not limited to an inkjet printer, and may be a color material discharge device used in the manufacture of color filters such as liquid crystal displays, an electrode material discharge device used in the formation of electrodes such as organic EL displays and FEDs (surface emission displays), a biological organic matter discharge device used in the manufacture of biochips, a three-dimensional modeling device, a printing device, and the like. 【0009】 FIG. 1 is a diagram showing an example of the functional configuration of the liquid ejecting apparatus 1. In the liquid ejecting apparatus 1 of the present embodiment, a power supply voltage signal VDC which is a DC voltage signal and an image data signal Img including information on an image to be formed on a medium are input. Then, the liquid ejecting apparatus 1 drives using the power supply voltage signal VDC as driving power to form an image corresponding to the image data signal Img on the medium. Note that the liquid ejecting apparatus 1 is not limited to a configuration in which the power supply voltage signal VDC which is a DC voltage signal is directly input, and may include an unillustrated AC / DC converter that converts a commercial AC voltage into a DC voltage, and a DC voltage signal output from the AC / DC converter may be supplied as the power supply voltage signal VDC to each part of the liquid ejecting apparatus 1. 【0010】 As shown in FIG. 1, the liquid ejecting apparatus 1 includes a control unit 2, a head unit 3, a drive signal output unit 4, a power supply unit 5, a determination unit 6, and a conveyance unit 7. Here, in the present embodiment, it is assumed that the liquid ejecting apparatus 1 includes one or a plurality of head units 3, one or a plurality of drive signal output units 4 corresponding one-to-one to the one or a plurality of head units 3, and one or a plurality of determination units 6 corresponding one-to-one to the one or a plurality of head units 3. However, in the following description, for convenience, as shown in FIG. 1, one of the one or a plurality of head units 3, one drive signal output unit 4 provided corresponding to the one head unit 3, and one determination unit 6 provided corresponding to the one head unit 3 will be focused on and described. 【0011】 The control unit 2 controls each component of the liquid dispensing device 1, including the head unit 3, drive signal output unit 4, power supply unit 5, determination unit 6, and transport unit 7. The control unit 2 is configured to include one or more CPUs (Central Processing Units). The control unit 2 may also be configured to include a programmable logic device such as an FPGA (Field Programmable Gate Array) instead of, or in addition to, the CPUs, and may also be configured to include memory circuits. The control unit 2 generates and outputs signals to control the operation of each part of the liquid dispensing device 1, such as output enable signals EN1, EN2, transport control signal MT, clock signal CL, print data signal SI, latch signal LAT, change signal CH, period specification signal Tsig, and drive waveform specification signal dCom, according to the input image data signal Img. 【0012】 The output enable signals EN1 and EN2 output by the control unit 2 are input to the power supply unit 5. The power supply voltage signal VDC is also input to the power supply unit 5. The power supply unit 5 generates and outputs a power supply voltage signal VHV with a predetermined voltage value used in each part of the liquid dispensing device 1 by stepping down the voltage value of the power supply voltage signal VDC according to the input output enable signals EN1 and EN2. Here, the power supply voltage signal VDC is, for example, a DC voltage signal with a voltage value of 48V, and the power supply voltage signal VHV is, for example, a DC voltage signal with a voltage value of 42V. In addition to the power supply voltage signal VHV, the power supply unit 5 may be configured to output multiple DC voltage signals with voltage values ​​different from the power supply voltage signal VHV, for example, a DC voltage signal with a voltage value of 5V or a DC voltage signal with a voltage value of 3.3V. In this case, the power supply unit 5 may further include a step-down regulator that steps down the voltage value of the power supply voltage signal VHV. 【0013】 The transport control signal MT output by control unit 2 is input to transport unit 7. Transport unit 7 controls the transport of the medium to which the ink will land, according to the input transport control signal MT. This changes the relative position between head unit 3 and the medium. 【0014】 The drive waveform specification signal dCom output by the control unit 2 is input to the drive signal output unit 4. The power supply voltage signal VHV output by the power supply unit 5 is also input to the drive signal output unit 4. The drive signal output unit 4 generates and outputs a drive signal Com that drives the multiple discharge units D described later. Specifically, the drive waveform specification signal dCom is a digital signal that defines the signal waveform of the drive signal Com output by the drive signal output unit 4. The drive signal output unit 4 converts the input drive waveform specification signal dCom into an analog signal using a DA conversion circuit (not shown). The drive signal output unit 4 then generates and outputs a drive signal Com that is an amplified version of the signal waveform defined by the drive waveform specification signal dCom by a Class D amplification according to the voltage value of the power supply voltage signal VHV. Alternatively, the drive signal output unit 4 may generate and output the drive signal Com by amplified the signal waveform defined by the drive waveform specification signal dCom into Class B or Class AB amplification according to the voltage value of the power supply voltage signal VHV. 【0015】 The clock signal CL, print data signal SI, latch signal LAT, change signal CH, and period specification signal Tsig output by the control unit 2, the drive signal Com output by the drive signal output unit 4, and the power supply voltage signal VHV output by the power supply unit 5 are input to the head unit 3. The print data signal SI is a signal propagated in synchronization with the clock signal CL and is a digital signal that specifies the type of operation of the multiple ejector units D in each of the periods defined by the latch signal LAT, change signal CH, and period specification signal Tsig. Specifically, the print data signal SI is a signal that includes information specifying whether or not to supply a drive signal Com to each of the multiple ejector units D in each of the periods defined by the latch signal LAT, change signal CH, and period specification signal Tsig, thereby The operation of the corresponding dispensing unit D is specified individually. 【0016】 The head unit 3 comprises a supply switching circuit 31, a recording head 32, and a detection circuit 33. The recording head 32 also has multiple discharge sections D. Hereinafter, the recording head 32 will be described as having M discharge sections D.When the M discharge sections D of the recording head 32 are specified and described individually, they will be referred to as discharge sections D[1] to D[M].In this case, when the m-th discharge section D of the M discharge sections D of the recording head 32 is specified and described, it may be referred to as discharge section D[m].Note that M is a natural number satisfying "M≧1", and m is any natural number satisfying "1≦m≦M".In addition, in the following description, when indicating that a component of the liquid discharge device 1 or a signal etc. corresponds to discharge section D[m] among the M discharge sections D, the subscript [m] may be added to the symbol representing the component or signal etc. 【0017】 The clock signal CL, print data signal SI, latch signal LAT, change signal CH, period specification signal Tsig, drive signal Com, and power supply voltage signal VHV are input to the supply switching circuit 31 of the head unit 3. At each of the timings defined by the latch signal LAT, change signal CH, and period specification signal Tsig, the supply switching circuit 31 switches whether or not to supply the drive signal Com as a supply drive signal Vin to the corresponding ejection unit D based on the print data signal SI. This supply drive signal Vin is supplied to the piezoelectric element PZ of the ejection unit D, which will be described later, causing the piezoelectric element PZ to be driven, and an amount of ink corresponding to the amount of drive of the piezoelectric element PZ is ejected from the ejection unit D. 【0018】 Furthermore, the supply switching circuit 31, at each of the timings defined by the latch signal LAT, the change signal CH, and the period specification signal Tsig, acquires a signal corresponding to the residual vibration generated in the ejection unit D to be inspected, based on the print data signal SI, and switches whether or not to supply it to the detection circuit 33 as a detection potential signal VX. 【0019】 The detection circuit 33 generates a detection signal SK based on the detection potential signal VX supplied via the supply switching circuit 31 and outputs it from the head unit 3. Specifically, the detection circuit 33 amplifies the input detection potential signal VX, removes noise components, and then converts the signal into a digital signal to generate the detection signal SK, which is then output from the head unit 3. 【0020】 The detection signal SK output from the head unit 3 is input to the determination unit 6. Based on the input detection signal SK, the determination unit 6 determines whether the ink ejection state at the ejection unit D under inspection is normal, and whether the ejection unit D under inspection is in a normal ejection state. Specifically, the determination unit 6 reads predetermined determination threshold information and correction value information from a storage circuit (not shown) including non-volatile memory such as ROM (Read Only Memory) or flash memory. The determination unit 6 corrects the input detection signal SK according to the read correction value information and compares the corrected signal with the predetermined determination threshold information. Then, based on the comparison result, the determination unit 6 determines whether an ejection abnormality has occurred at the ejection unit D under inspection, and whether the ejection unit D under inspection is in a normal ejection state. The determination unit 6 then generates a state determination signal JH indicating the determination result and outputs it to the control unit 2. In the following explanation, determining whether or not a discharge abnormality is occurring in the discharge unit D under inspection, and determining whether or not the discharge unit D under inspection is in a normal discharge state, may be simply referred to as determining the state of the discharge unit D under inspection. 【0021】 Here, "discharge abnormality" refers to a state in which there is an abnormality in the ink discharge state from the discharge unit D being inspected, and is a general term for a state in which ink cannot be accurately discharged from the discharge unit D being inspected. Such discharge abnormalities include, for example, a state in which ink cannot be discharged from the discharge unit D, or a state in which an amount of ink different from the amount of ink discharged from the discharge unit D as defined by the drive signal Com is discharged from the discharge unit D. This includes conditions such as the ejection state, where ink is ejected from the ejection unit D at a speed different from the ink ejection speed defined by the drive signal Com. 【0022】 As described above, when the ejection process is being performed to form an image on the medium corresponding to the image data signal Img by ejecting ink, the control unit 2 generates a signal such as a print data signal SI to control the head unit 3 so that ink is ejected, based on the image data signal Img, and outputs it to the head unit 3. At the same time, it generates a drive waveform specification signal dCom to control the drive signal output unit 4 so that it outputs a drive signal Com to drive the ejection unit D so that ink is ejected, and outputs it to the drive signal output unit 4. At this time, the control unit 2 generates and outputs a transport control signal MT to control the transport unit 7. As a result, the control unit 2 controls the transport unit 7 so as to change the relative position of the medium with respect to the head unit 3, and controls the presence or absence of ink ejection from each of the multiple ejection units D, the amount of ink ejected, and the timing of ink ejection. As a result, the ink ejected from the ejection unit D lands at the desired position on the medium. As a result, an image corresponding to the image data signal Img is formed on the medium. 【0023】 Furthermore, when the control unit 2 is executing a determination process to determine the state of the ejection unit D, it generates a signal such as a print data signal SI to determine the state of the ejection unit D to be inspected and outputs it to the head unit 3. It also generates a drive waveform specification signal dCom to control the drive signal output unit 4 to output a drive signal Com to determine the state of the ejection unit D and outputs it to the drive signal output unit 4. As a result, the detection circuit 33 receives a detection potential signal VX corresponding to the ejection unit D to be inspected via the supply switching circuit 31. The detection circuit 33 acquires the input detection potential signal VX, generates a detection signal SK corresponding to the acquired detection potential signal VX, and outputs it to the determination unit 6. Based on the input detection signal SK, the determination unit 6 determines whether the ink ejection state at the ejection unit D to be inspected is normal, and whether the ejection unit D to be inspected is in a normal ejection state. The determination unit 6 then generates a state determination signal JH according to the determination result of the state of the ejection unit D to be inspected and outputs it to the control unit 2. This allows the control unit 2 to acquire the state of the ejection unit D of the object being inspected and correct various signals to be output according to the acquired state of the ejection unit D of the object being inspected. As a result, the quality of the image formed on the medium is improved. 【0024】 As described above, the liquid dispensing device 1 of this embodiment performs various processes, including a dispensing process that forms an image on a medium corresponding to an image data signal Img, and a determination process that determines the state of the dispensing unit D that dispenses ink onto the medium. 【0025】 In addition, in the liquid dispensing device 1, the control unit 2 and the determination unit 6 may be mounted on a common semiconductor device. In this case, the drive signal output unit 4 and part or all of the transport unit 7 may be mounted on the same semiconductor device. Furthermore, the supply switching circuit 31 and the detection circuit 33 of the head unit 3 may be mounted on a common semiconductor device. 【0026】 Next, an overview of the structure of the liquid ejection device 1 will be described. Figure 2 is a diagram showing an example of the schematic internal structure of the liquid ejection device 1. As shown in Figure 2, the liquid ejection device 1 of this embodiment is assumed to be a serial inkjet printer. That is, when the liquid ejection device 1 performs the ejection process, it transports a medium P such as recording paper in the sub-scanning direction, and while reciprocating a carriage 110 equipped with a head unit 3 in the main scanning direction intersecting the sub-scanning direction, it ejects ink from the M ejection units D of the head unit 3. At this time, the ink ejected from the M ejection units D lands at the desired position on the medium P. As a result, the liquid ejection device 1 forms dots on the medium P corresponding to the image data signal Img. Note that the liquid ejection device 1 is not limited to serial inkjet printers but can also be used in line-type inkjet printers. An inkjet printer is also acceptable. 【0027】 In the following description, mutually orthogonal X, Y, and Z axes are used. In the following description, the starting point of the arrow indicating the direction along the X axis shown in the diagram will be referred to as the -X side and the tip as the +X side, the starting point of the arrow indicating the direction along the Y axis shown in the diagram will be referred to as the -Y side and the tip as the +Y side, and the starting point of the arrow indicating the direction along the Z axis shown in the diagram will be referred to as the -Z side and the tip as the +Z side. In this embodiment, as illustrated in Figure 2, the liquid dispensing device 1 has a sub-scanning direction located along the X axis and a main scanning direction located along the Y axis, and the medium P is transported along the X axis such that the -X side is the upstream side and the +X side is the downstream side, and the carriage 110 is provided to reciprocate along the Y axis. 【0028】 As shown in Figure 2, the liquid ejection device 1 comprises a housing 100 and a carriage 110 that is reciprocable within the housing 100 in the Y-axis direction and is equipped with one or more head units 3. The carriage 110 is also equipped with four ink cartridges 120 that correspond one-to-one with four colors of ink: cyan, magenta, yellow, and black. In this embodiment, as an example, the liquid ejection device 1 is assumed to have four head units 3 that correspond one-to-one with four ink cartridges 120. 【0029】 Each of the four head units 3 has M ejection ports D, which are supplied with ink from the corresponding ink cartridge 120. As a result, the inside of the 4M ejection ports D of each of the four head units 3 are filled with ink supplied from the corresponding ink cartridge 120. Each of the 4M ejection ports D of each of the four head units 3 then ejects the filled ink toward the medium P. Note that the ink cartridge 120 may not be mounted on the carriage 110, but may be provided outside the carriage 110. 【0030】 Furthermore, the liquid dispensing device 1 of this embodiment includes, as the transport unit 7 described above, a carriage transport mechanism 71 for reciprocating the carriage 110 along the Y axis, a carriage guide shaft 76 for supporting the carriage 110 so that it can reciprocate in the direction along the Y axis, a media transport mechanism 73 for transporting the media P, and a platen 75 provided on the -Z side of the carriage 110. When a printing process is performed, the transport unit 7 uses the carriage transport mechanism 71 to reciprocate the carriage 110, on which the head unit 3 is mounted, along the carriage guide shaft 76 along the Y axis, and the media transport mechanism 73 transports the media P on the platen 75 along the X axis from the -X side to the +X side. As a result, the relative position of the media P with respect to the head unit 3 changes, making it possible for ink to land on the entire surface of the media P. 【0031】 Here, an example of the structure of an ejection unit D that ejects ink onto a medium P will be described. Figure 3 is a schematic diagram of one ejection unit D. As shown in Figure 3, the ejection unit D includes a piezoelectric element PZ, a cavity 322 filled with ink, a nozzle N communicating with the cavity 322, and a diaphragm 321. When a supply drive signal Vin is supplied to the piezoelectric element PZ, the piezoelectric element PZ is driven, and the driving of the piezoelectric element PZ ejects the ink stored inside the cavity 322 from the nozzle N. 【0032】 The cavity 322 is a space partitioned by a cavity plate 324, a nozzle plate 323 on which the nozzle N is formed, and a diaphragm 321. The cavity 322 communicates with a reservoir 325 via an ink supply port 326, and the reservoir 325 communicates with an ink cartridge 120 corresponding to the ejection unit D via an ink intake port 327. As a result, ink is supplied to the inside of the cavity 322 from the corresponding ink cartridge 120 via the ink intake port 327, the reservoir 325, and the ink supply port 326. Therefore, the inside of the cavity 322 is supplied with ink from the corresponding ink cartridge 120. The ink supplied from the device is filled in. 【0033】 The piezoelectric element PZ has an upper electrode Zu, a lower electrode Zd, and a piezoelectric body Zm. The piezoelectric body Zm is located between the upper electrode Zu and the lower electrode Zd. The upper electrode Zu is supplied with a supply drive signal Vin output by the supply switching circuit 31. The lower electrode Zd is supplied with a reference voltage signal Vbs propagating through the wiring Lb. The piezoelectric body Zm is displaced along the Z-axis to the +Z side or the -Z side according to the potential difference between the upper electrode Zu and the lower electrode Zd, which is the potential difference between the voltage value of the supply drive signal Vin supplied to the upper electrode Zu and the voltage value of the reference voltage signal Vbs supplied to the lower electrode Zd. In other words, the piezoelectric element PZ is driven to be displaced along the Z-axis to the +Z side or the -Z side according to the potential difference between the voltage value of the supply drive signal Vin and the voltage value of the reference voltage signal Vbs. Here, the reference voltage signal Vbs supplied to the lower electrode Zd is a signal that serves as the reference potential for driving the piezoelectric element PZ, and its potential is constant, such as 5.5V, 6V, or ground potential. 【0034】 The lower electrode Zd is joined to the diaphragm 321. Therefore, when the piezoelectric element PZ is driven to displace along the Z-axis by the supply drive signal Vin, the diaphragm 321 also displaces along the Z-axis. This displacement of the diaphragm 321 changes the internal volume and internal pressure of the cavity 322. Then, in accordance with the changes in the internal volume and internal pressure of the cavity 322, the ink filled inside the cavity 322 is ejected from the nozzle N. That is, an amount of ink corresponding to the amount of drive of the piezoelectric element PZ is ejected from the nozzle N of the ejection unit D. In other words, the piezoelectric element PZ ejects an amount of ink from the ejection unit D corresponding to the displacement caused by the supply drive signal Vin corresponding to the drive signal Com. That is, the ejection unit D includes a piezoelectric element PZ driven by the drive signal Com, and ejects ink by driving the piezoelectric element PZ. In other words, the liquid ejection device 1 has an ejection unit D that ejects ink, which is an example of a liquid. 【0035】 Figure 4 shows an example of the arrangement of a total of 4M discharge units D and 4M nozzles N, which are provided on four head units 3. As shown in Figure 4, the four head units 3 are positioned side by side along the Y-axis on the carriage 110. At this time, the M discharge units D and nozzles N of each of the four head units 3 are arranged side by side along the X-axis. Specifically, the M discharge units D[1] to D[M] of the head unit 3 are arranged in the order of discharge unit D[1], discharge unit D[2], discharge unit D[3], ..., discharge unit D[M] along the X-axis from the -X side to the +X side. That is, the head unit 3 includes a nozzle row NL formed so that the M nozzles N of each of the M discharge units D are arranged side by side along the X-axis from the -X side to the +X side. Therefore, the carriage 110 has four rows of nozzle rows NL, each of the four head units 3, arranged along the Y-axis. Then, ink is ejected from each of the nozzles N that form the nozzle row NL contained in each of the four head units 3. 【0036】 1.2 Power Supply Unit Configuration The functional configuration of the power supply unit 5 will now be described. Figure 5 shows an example of the functional configuration of the power supply unit 5. As shown in Figure 5, the power supply unit 5 has a switching power supply circuit 50 and a linear power supply circuit 55. The power supply unit 5 receives a power supply voltage signal VDC as input and outputs a power supply voltage signal VHV. 【0037】 The switching power supply circuit 50 includes a control circuit 51, a switching circuit 52, a smoothing circuit 53, and a feedback circuit 54. The switching circuit 52 includes transistors 521 and 522, the smoothing circuit 53 includes an inductor 531 and a capacitor 532, and the feedback circuit 54 includes resistors 541 and 542. 【0038】 The control circuit 51 receives an output enable signal EN1. If the input output enable signal EN1 contains information to enable the operation of the switching power supply circuit 50, the control circuit 51 outputs a signal that controls the conduction state of transistors 521 and 522 included in the switching circuit 52, according to the voltage value of the feedback signal FB1, which will be described later and is input from the feedback circuit 54. On the other hand, if the input output enable signal EN1 contains information to disable the operation of the switching power supply circuit 50, the control circuit 51 outputs a signal that controls transistors 521 and 522 included in the switching circuit 52 to a non-conducting state, regardless of the feedback signal FB1. In the following explanation, the logic level of the output enable signal EN1 containing information to enable the operation of the switching power supply circuit 50 is assumed to be H level, and the logic level of the output enable signal EN1 containing information to disable the operation of the switching power supply circuit 50 is assumed to be L level. Note that the relationship between the information to enable or disable the operation of the switching power supply circuit 50 and the output enable signal EN1 is not limited to this. 【0039】 Transistors 521 and 522 are, for example, n-channel type MOS-FETs (Metal-Oxide-Semiconductor Field-Effect Transistors). The drain terminal of transistor 521 is input to the power supply voltage signal VDC. The source terminal of transistor 521 is electrically connected to the drain terminal of transistor 522. The source terminal of transistor 522 is supplied with ground potential. In addition, the gate terminals of transistor 521 and 522, which are control terminals that control the conduction state between the drain and source terminals of transistor 521 and transistor 522, are each input to a signal that controls the conduction state of transistors 521 and 522, output by the control circuit 51. In other words, the switching circuit 52 controls the conduction state of transistors 521 and 522 under the control of the control circuit 51, thereby outputting a pulse signal from the connection point where the source terminal of transistor 521 and the drain terminal of transistor 522 are electrically connected, the voltage value of which switches between the power supply voltage signal VDC and the ground potential. 【0040】 One end of inductor 531 is electrically connected to the source terminal of transistor 521 and the drain terminal of transistor 522. The other end of inductor 531 is electrically connected to one end of capacitor 532. Ground potential is supplied to the other end of capacitor 532. In other words, the smoothing circuit 53 constitutes a low-pass filter including inductor 531 and capacitor 532. The smoothing circuit 53 then smooths the pulse signal generated at the connection point where the source terminal of transistor 521 and the drain terminal of transistor 522 are electrically connected. The signal smoothed by this smoothing circuit 53 is output as a voltage signal Vsw from the switching power supply circuit 50. 【0041】 One end of resistor 541 is electrically connected to the other end of inductor 531 and one end of capacitor 532. The other end of resistor 541 is electrically connected to one end of resistor 542. Ground potential is supplied to the other end of resistor 542. The potential at the connection point where the other end of resistor 541 and one end of resistor 542 are electrically connected is input to the control circuit 51 as a feedback signal FB1. In other words, the feedback circuit 54 divides the voltage value of the voltage signal Vsw output by the switching power supply circuit 50, which is the voltage value at the connection point where the other end of inductor 531 and one end of capacitor 532 are electrically connected, by resistors 541 and 542, and feeds it back to the control circuit 51. 【0042】 The operation of the switching power supply circuit 50 configured as described above will now be explained. When the output enable signal EN1 at a high level is input to the control circuit 51, if the voltage value of the feedback signal FB1 input from the feedback circuit 54 is higher than a predetermined voltage value, the transistor... The circuit outputs a signal that controls the connection between the drain terminal and source terminal of transistor 521 to be non-conductive, and a signal that controls the connection between the drain terminal and source terminal of transistor 522 to be conductive. At this time, the voltage value at the connection point where the source terminal of transistor 521 and the drain terminal of transistor 522 are electrically connected becomes ground potential. Therefore, the voltage value of the voltage signal Vsw output from the smoothing circuit 53 decreases. 【0043】 Furthermore, during the period when an H-level output enable signal EN1 is input, if the voltage value of the feedback signal FB1 input from the feedback circuit 54 is lower than a predetermined voltage value, the control circuit 51 outputs a signal to control the connection between the drain terminal and source terminal of transistor 521 to conduct, and a signal to control the connection between the drain terminal and source terminal of transistor 522 to non-conduct. At this time, the voltage value at the connection point where the source terminal of transistor 521 and the drain terminal of transistor 522 are electrically connected becomes the voltage value of the power supply voltage signal VDC. Consequently, the voltage value of the voltage signal Vsw output from the smoothing circuit 53 increases. 【0044】 Furthermore, the control circuit 51 outputs a signal that controls the connection between the drain terminal and source terminal of transistor 521 to be non-conductive, and a signal that controls the connection between the drain terminal and source terminal of transistor 522 to be non-conductive, during the period when the low-level output enable signal EN1 is input. As a result, the switching power supply circuit 50 stops outputting the voltage signal Vsw. 【0045】 As described above, the switching power supply circuit 50 controls the conduction state of transistors 521 and 522 so that the voltage value of the voltage signal Vsw, which is the voltage value of the feedback signal FB1 input from the feedback circuit 54, remains constant during the period when an H-level output enable signal EN1 is input, thereby generating and outputting a voltage signal Vsw whose voltage value is constant at a predetermined value. At this time, the voltage value of the voltage signal Vsw output by the switching power supply circuit 50 is the voltage value used as the power supply voltage for each component of the liquid dispensing device 1, and is constant at 42V. In other words, the switching power supply circuit 50 operates so that the voltage value of the output voltage signal Vsw is the voltage value used as the power supply voltage for each component of the liquid dispensing device 1, and is constant at 42V. Note that the configuration of the switching power supply circuit 50 is not limited to this, and for example, a diode may be used instead of the transistor 522. 【0046】 The linear power supply circuit 55 includes a control circuit 56, a transistor 57, and a feedback circuit 58, the feedback circuit 58 including resistors 581 and 582. 【0047】 The control circuit 56 receives an output enable signal EN2. If the input output enable signal EN2 contains information that enables the operation of the linear power supply circuit 55, the control circuit 56 outputs a signal that controls the conduction state of transistor 57 according to the voltage value of the feedback signal FB2, which will be described later and is input from the feedback circuit 58. On the other hand, if the input output enable signal EN2 contains information that disables the operation of the linear power supply circuit 55, the control circuit 56 outputs a signal that controls transistor 57 to be non-conductive, regardless of the feedback signal FB2. In the following explanation, the logic level of the output enable signal EN2 containing information that enables the operation of the linear power supply circuit 55 is assumed to be H level, and the logic level of the output enable signal EN2 containing information that disables the operation of the linear power supply circuit 55 is assumed to be L level. Note that the relationship between the information that enables or disables the operation of the linear power supply circuit 55 and the output enable signal EN2 is not limited to this. 【0048】 Transistor 57 is, for example, an NPN bipolar transistor. The power supply voltage signal VDC is input to the collector terminal, which is one end of transistor 57. The voltage value at the emitter terminal, which is the other end of transistor 57, is output as a voltage signal Vln from the linear power supply circuit 55. Also, the collector terminal of transistor 57 and The gate terminal, which is a control terminal that controls the conduction state with respect to the emitter terminal, receives a signal that controls the conduction state of transistor 57, output by the control circuit 56. In other words, the conduction state of transistor 57 is controlled under the control of the control circuit 56, thereby continuously controlling the amount of current output from the emitter terminal of transistor 57. 【0049】 One end of resistor 581 is electrically connected to the emitter terminal of transistor 57. The other end of resistor 581 is electrically connected to one end of resistor 582. The other end of resistor 582 is supplied with ground potential. The potential at the connection point where the other end of resistor 581 and one end of resistor 582 are electrically connected is input to the control circuit 56 as a feedback signal FB2. In other words, the feedback circuit 58 divides the voltage value of the voltage signal Vln output by the linear power supply circuit 55, which is the voltage value at the collector terminal of transistor 57, by resistors 581 and 582, and feeds it back to the control circuit 56. 【0050】 The operation of the linear power supply circuit 55 configured as described above will now be explained. When the output enable signal EN2 at a high level is input, the control circuit 56 reduces the amount of current supplied to the base terminal of transistor 57 if the voltage value of the feedback signal FB2 input from the feedback circuit 58 is higher than a predetermined voltage value. As a result, the amount of current flowing from the collector terminal to the emitter terminal of transistor 57 decreases. Consequently, the amount of current output from the linear power supply circuit 55 decreases, and the voltage value of the voltage signal Vln output by the linear power supply circuit 55 decreases. 【0051】 Furthermore, during the period when a high-level output enable signal EN2 is input, the control circuit 56 increases the amount of current supplied to the base terminal of transistor 57 if the voltage value of the feedback signal FB2 input from the feedback circuit 58 is lower than a predetermined voltage value. This increases the amount of current flowing from the collector terminal to the emitter terminal of transistor 57. As a result, the amount of current output from the linear power supply circuit 55 increases, and the voltage value of the voltage signal Vln output by the linear power supply circuit 55 increases. 【0052】 Furthermore, the control circuit 56 outputs a signal that controls the connection between the collector terminal and emitter terminal of transistor 57 to non-conductive during the period when an L-level output enable signal EN2 is input. As a result, the linear power supply circuit 55 stops outputting the voltage signal Vln. 【0053】 In other words, the linear power supply circuit 55 is configured to include a series regulator circuit. The linear power supply circuit 55 controls the conduction state of transistor 57 so that the voltage value of the voltage signal Vln, which is the voltage value of the feedback signal FB2 input from the feedback circuit 58, remains constant during the period when an H-level output enable signal EN2 is input, thereby generating and outputting a voltage signal Vln whose voltage value is constant at a predetermined value. At this time, the voltage value of the voltage signal Vln output by the linear power supply circuit 55 is the voltage value used as the power supply voltage for each component of the liquid dispensing device 1, and is constant at 42V. In other words, the linear power supply circuit 55 operates so that the voltage value of the output voltage signal Vln is the voltage value used as the power supply voltage for each component of the liquid dispensing device 1, and is constant at 42V. Note that the linear power supply circuit 55 may be configured to include a shunt regulator circuit instead of, or in addition to, the series regulator circuit. 【0054】 As described above, the power supply unit 5 includes a linear power supply circuit 55 that receives a power supply voltage signal VDC and outputs a voltage signal Vln which is a 42V DC voltage, and a switching power supply circuit 50 that receives a power supply voltage signal VDC and outputs a voltage signal Vsw which is a 42V DC voltage. The power supply unit 5 then controls the output of the linear power supply circuit 55 to output the voltage signal Vln, or the switching power supply circuit 50 to output the voltage signal Vsw, depending on the input output enable signals EN1 and EN2. The applied voltage signal Vsw is output as the power supply voltage signal VHV. 【0055】 1.3 Head Unit Configuration Next, the functional configuration of the head unit 3 will be described. Figure 6 is a diagram showing an example of the functional configuration of the head unit 3. As described above, the head unit 3 has a supply switching circuit 31, a recording head 32, and a detection circuit 33. Figure 6 also illustrates the wiring Lc through which the drive signal Com propagates, the wiring Lb through which the reference voltage signal Vbs propagates, and the wiring Ls through which the detection potential signal VX propagates to the detection circuit 33 in the head unit 3. 【0056】 The supply switching circuit 31 includes switches Wc[1] to Wc[M], switches Ws[1] to Ws[M], switch Wf, resistor Rf, and a connection state specification circuit 310. Switches Wc[1] to Wc[M] and switches Ws[1] to Ws[M] are provided in the supply switching circuit 31 corresponding to the discharge sections D[1] to D[M]. Specifically, in the supply switching circuit 31, switches Wc[m] and Ws[m] are provided corresponding to the discharge section D[m]. 【0057】 The head unit 3 receives the power supply voltage signal VHV, clock signal CL, print data signal SI, latch signal LAT, change signal CH, and period specification signal Tsig. The power supply voltage signal VHV, clock signal CL, print data signal SI, latch signal LAT, change signal CH, and period specification signal Tsig are input to the connection status specification circuit 310. 【0058】 The connection state specification circuit 310 generates signals that specify the conduction state of switches Wc[1]~Wc[M], switches Ws[1]~Ws[M], and switch Wf, respectively, in accordance with the print data signal SI that propagates in synchronization with the clock signal CL during the period specified by the input latch signal LAT, change signal CH, and period specification signal Tsig. Subsequently, the connection state designation circuit 310 outputs connection state designation signals Qc[1]~Qc[M] by level-shifting the signals that specify the conduction state of switches Wc[1]~Wc[M] to high-amplitude logic signals of the voltage value of the power supply voltage signal VHV; outputs connection state designation signals Qs[1]~Qs[M] by level-shifting the signals that specify the conduction state of switches Ws[1]~Ws[M] to high-amplitude logic signals of the voltage value of the power supply voltage signal VHV; and outputs connection state designation signal Qf by level-shifting the signal that specifies the conduction state of switch Wf to high-amplitude logic signals of the voltage value of the power supply voltage signal VHV. In other words, the connection state designation circuit 310 generates and outputs connection state designation signals Qc[1]~Qc[M], Qs[1]~Qs[M], and Qf, where the H level is the power supply voltage signal VHV and the L level is the ground potential. 【0059】 The connection status designation signals Qc[1]~Qc[M] output by the connection status designation circuit 310 are input to the control terminals of switches Wc[1]~Wc[M], the connection status designation signals Qs[1]~Qs[M] output by the connection status designation circuit 310 are input to the control terminals of switches Ws[1]~Ws[M], and the connection status designation signal Qf output by the connection status designation circuit 310 is input to the control terminal of switch Wf. This controls the conduction state of switches Wc[1]~Wc[M], Ws[1]~Ws[M], and Wf, respectively. In other words, the power supply voltage signal VHV is supplied to switches Wc[1]~Wc[M], Ws[1]~Ws[M], and Wf. 【0060】 Such a connection state specification circuit 310 includes, for example, a register that holds print data signals SI propagated in synchronization with a clock signal CL corresponding to the ejection units D[1] to D[M], a decoder that decodes the print data signals SI held in the register to generate signals that specify the conduction state of switches Wc[1] to Wc[M], Ws[1] to Ws[M], and Wf, and a level shift circuit that outputs connection state specification signals Qc[1] to Qc[M], Qs[1] to Qs[M], Qf, etc., obtained by level shifting the logic of the signals generated by the decoder to a high-amplitude logic signal of the voltage value of the power supply voltage signal VHV. 【0061】 Switch Wc[m], one of the switches Wc[1] to Wc[M], has one end electrically connected to the wiring Lc and the other end electrically connected to the upper electrode Zu[m] of the piezoelectric element PZ[m] included in the discharge section D[m]. The connection state designation signal Qc[m], one of the connection state designation signals Qc[1] to Qc[M], is input to the control terminal of switch Wc[m]. Switch Wc[m] switches the conduction state between one end and the other according to the logic level of the connection state designation signal Qc[m] input to the control terminal. In other words, switch Wc[m] switches the connection state between the wiring Lc and the upper electrode Zu[m] according to the logic level of the connection state designation signal Qc[m] input to the control terminal. As a result, the switch Wc[m] switches whether or not to supply the drive signal Com, which propagates through the wiring Lc, as the supply drive signal Vin[m] to the upper electrode Zu[m] of the discharge section D[m], according to the connection status specification signal Qc[m]. 【0062】 Switch Ws[m], one of the switches Ws[1] to Ws[M], has one end electrically connected to wiring Ls and the other end electrically connected to the upper electrode Zu[m] of the piezoelectric element PZ[m] included in the discharge section D[m]. The connection state designation signal Qs[m], one of the connection state designation signals Qs[1] to Qs[M], is input to the control terminal of switch Ws[m]. Switch Ws[m] switches the conduction state between one end and the other according to the logic level of the connection state designation signal Qs[m] input to the control terminal. That is, switch Ws[m] switches the connection state between wiring Ls and the upper electrode Zu[m] according to the logic level of the connection state designation signal Qs[m] input to the control terminal. As a result, the switch Ws[m] switches whether or not to supply the signal generated at the upper electrode Zu[m] of the piezoelectric element PZ[m] to the wiring Ls in response to the residual vibration generated at the discharge section D[m], according to the connection status specification signal Qs[m]. 【0063】 Switch Wf has one end electrically connected to wiring Lc and the other end electrically connected to one end of resistor Rf. The other end of resistor Rf is electrically connected to wiring Ls. In other words, switch Wf has one end electrically connected to wiring Lc and the other end electrically connected to wiring Ls via resistor Rf. A connection state specification signal Qf is input to the control terminal of switch Wf. Switch Wf switches the conduction state between one end and the other end according to the logic level of the connection state specification signal Qf input to the control terminal. In other words, switch Wf switches the connection state between wiring Lc and wiring Ls according to the logic level of the connection state specification signal Qf input to the control terminal. 【0064】 In other words, the supply switching circuit 31 has switches Ws[1]~Ws[M] that switch whether or not to supply the detection potential signal VX to the detection circuit 33, and switches Wc[1]~Wc[M] that switch whether or not to supply the drive signal Com to the piezoelectric elements PZ[1]~PZ[M]. Switches Ws[1]~Ws[M] switch whether or not to supply the detection potential signal VX to the detection circuit 33 based on connection status designation signals Qs[1]~Qs[M] corresponding to the power supply voltage signal VHV, and switches Wc[1]~Wc[M] switch whether or not to supply the drive signal Com to the piezoelectric elements PZ[1]~PZ[M] based on connection status designation signals Qc[1]~Qc[M] corresponding to the power supply voltage signal VHV. 【0065】 Each of these switches Wc[1]~Wc[M] and Ws[1]~Ws[M] can be configured, for example, as a transmission gate. Here, we will describe an example of the configuration of a transmission gate that constitutes switches Wc[1]~Wc[M] and Ws[1]~Ws[M]. Note that switches Wc[1]~Wc[M] and Ws[1]~Ws[M] have the same configuration, differing only in the input signal and the output signal. Therefore, in the following description, switches Wc[1]~Wc[M] and Ws[1]~Ws[M] will not be distinguished and will simply be referred to as switch W. In this case, one end of switch W is electrically connected to the wiring Lc through which the drive signal Com propagates, or to the wiring Ls through which the detection potential signal VX propagates to the detection circuit 33, and the other end of switch W is connected to the discharge section D[1 The upper electrode Zu of the piezoelectric element PZ, which is the discharge part D as ]~D[M], is electrically connected, and the connection status specification signal Q, which is the connection status specification signal Qc[1]~Qc[M], Qs[1]~Qs[M], is input to the control terminal of the switch W. 【0066】 Figure 7 shows an example of the configuration of switch W. As shown in Figure 7, switch W includes a transistor Wnm, which is an n-channel MOS-FET, a transistor Wpm, which is a p-channel MOS-FET, and an inverter Wiv. 【0067】 One end of transistor Wnm and one end of transistor Wpm are electrically connected to each other, and the other end of transistor Wnm and the other end of transistor Wpm are electrically connected to each other. Here, one end of transistor Wnm corresponds to the drain terminal of switch Wc[1]~Wc[M] and the source terminal of switch Ws[1]~Ws[M], the other end of transistor Wnm corresponds to the source terminal of switch Wc[1]~Wc[M] and the drain terminal of switch Ws[1]~Ws[M], one end of transistor Wpm corresponds to the source terminal of switch Wc[1]~Wc[M] and the drain terminal of switch Ws[1]~Ws[M], and the other end of transistor Wpm corresponds to the drain terminal of switch Wc[1]~Wc[M] and the source terminal of switch Ws[1]~Ws[M]. 【0068】 Furthermore, the connection point where one end of transistor Wnm and one end of transistor Wpm are connected is electrically connected to wiring L, and the connection point where the other end of transistor Wnm and the other end of transistor Wpm are connected to each other is electrically connected to the upper electrode Zu of piezoelectric element PZ. In other words, the connection point where one end of transistor Wnm and one end of transistor Wpm are connected to each other corresponds to one end of switch W, and the connection point where the other end of transistor Wnm and the other end of transistor Wpm are connected to each other corresponds to the other end of switch W. 【0069】 Then, the gate terminal of transistor Wnm is input with a connection state designation signal Q, and the gate terminal of transistor Wpm is input with a signal obtained by inverting the logic level of the connection state designation signal Q via inverter Wiv. In other words, the conduction state of transistors Wnm and Wpm is controlled by the connection state designation signal Q based on the power supply voltage signal VHV. 【0070】 Furthermore, ground potential is supplied to the back gate terminal of transistor Wnm, and power supply voltage signal VHV is supplied to the back gate terminal of transistor Wpm. 【0071】 In the switch W configured as described above, when a high-level connection status signal Q is input, the connection between one end and the other end of transistor Wnm, and between one end and the other end of transistor Wpm are controlled to conduct, and when a low-level connection status signal Q is input, the connection between one end and the other end of transistor Wnm, and between one end and the other end of transistor Wpm are controlled to be non-conductive. In other words, when a high-level connection status signal Q is input to the control terminal of switch W, one end and the other end are controlled to conduct, and when a low-level connection status signal Q is input to the control terminal of switch W, one end and the other end are controlled to be non-conductive. 【0072】 In addition, the switch W may have a connection status specification signal Q input to the gate terminal of transistor Wpm, and a signal with the logic level of the connection status specification signal Q inverted via inverter Wiv input to the gate terminal of transistor Wnm. In this case, the switch W may be controlled to conduct when an L-level connection status specification signal Q is input to the control terminal of the switch W, and to not conduct when an H-level connection status specification signal Q is input to the control terminal of the switch W. 【0073】 Specifically, the switches Wc[1]~Wc[M] include transistors Wnm and Wpm that switch whether or not to supply the drive signal Com to the piezoelectric elements PZ[1]~PZ[M], and the power supply voltage signal VHV is supplied to the back gate terminal of transistor Wpm. The switches Ws[1]~Ws[M] include transistors Wnm and Wpm that switch whether or not to supply the detection potential signal VX to the detection circuit 33, and the power supply voltage signal VHV is supplied to the back gate terminal of transistor Wpm. 【0074】 Returning to Figure 6, the connection status specification circuit 310 generates connection status specification signals Q1 and Q2 in accordance with the print data signal SI propagated based on the clock signal CL during the period specified by the input latch signal LAT, change signal CH, and period specification signal Tsig, and outputs them to the detection circuit 33. 【0075】 Here, an example of various signals input to the connection state specification circuit 310 will be described. Figure 8 is a diagram illustrating an example of various signals input to the connection state specification circuit 310. As shown in Figure 8, the liquid dispensing device 1 of this embodiment defines one or more unit periods TP as the operating period, and controls the driving of the dispensing unit D [m] and the operation of the detection circuit 33 in each of the defined unit periods TP. 【0076】 Specifically, the control unit 2 generates a latch signal LAT including a pulse PLL and outputs it to the connection state specification circuit 310. For example, the control unit 2 may generate a latch signal LAT including a pulse PLL by setting the logic level of the latch signal LAT to a high level for a short time at a timing based on at least one of the transport position of the medium P transported along the sub-scanning direction and the scanning position of the carriage 110 that reciprocates along the main scanning direction, and output it to the connection state specification circuit 310. Alternatively, for example, the control unit 2 may generate a latch signal LAT including a pulse PLL by setting the logic level of the latch signal LAT to a high level for a short time at predetermined time intervals, and output it to the connection state specification circuit 310. The period from the rising edge of the pulse PLL included in this latch signal LAT until the next rising edge of the pulse PLL corresponds to the unit period TP described above. 【0077】 Furthermore, the control unit 2 generates a change signal CH that includes a pulse PLC and outputs it to the connection state specification circuit 310. For example, the control unit 2 generates a change signal CH that includes a pulse PLC by setting the logic level of the change signal CH to a high level for a short time after a predetermined time has elapsed from the rising edge of the pulse PLL, and outputs it to the connection state specification circuit 310. The pulse PLC included in this change signal CH divides the unit period TP into a control period TQ1 and a control period TQ2. Specifically, the change signal CH divides the unit period TP into a control period TQ1, which is the period from the rising edge of the pulse PLL to the rising edge of the pulse PLC, and a control period TQ2, which is the period from the rising edge of the pulse PLC to the rising edge of the pulse PLL. Note that the number of divisions of the unit period TP by the change signal CH is not limited to two. 【0078】 Furthermore, the control unit 2 generates a period specification signal Tsig, which includes pulses PLT1 and PLT2, and outputs it to the connection state specification circuit 310. For example, the control unit 2 generates pulse PLT1 by setting the logic level of the period specification signal Tsig to H level at a predetermined time after the rising edge of the pulse PLL, and then setting the logic level of the period specification signal Tsig to L level, and outputs it to the connection state specification circuit 310. After generating pulse PLT1, the control unit 2 generates pulse PLT2 by setting the logic level of the period specification signal Tsig to H level at a predetermined time after the rising edge of the pulse PLL, and then setting the logic level of the period specification signal Tsig to L level, and outputs it to the connection state specification circuit 310. The pulses PLT1 and PLT2 included in this period specification signal Tsig divide the unit period TP into control periods TT1 to TT5. Specifically, the period specification signal Tsig divides the unit period TP into control periods TT1 to TT5. The control period is divided into the following: control period TT1, which is the period from the beginning of pulse PLT1 to the rising edge of pulse PLT1; control period TT2, which is the period from the rising edge of pulse PLT1 to the falling edge of pulse PLT1; control period TT3, which is the period from the falling edge of pulse PLT1 to the rising edge of pulse PLT2; control period TT4, which is the period from the rising edge of pulse PLT2 to the falling edge of pulse PLT2; and control period TT5, which is the period from the falling edge of pulse PLT2 to the rising edge of pulse PLL. Note that the number of divisions of the unit period TP by the period designation signal Tsig is not limited to five. 【0079】 Furthermore, the control unit 2 generates a print data signal SI that serially includes the individual designation signals Sd[1] to Sd[M] and outputs it to the connection status designation circuit 310. Each of the individual designation signals Sd[1] to Sd[M] is a signal containing 3 bits of information and defines the driving mode of each of the ejection units D[1] to D[M]. Hereinafter, the 3 bits of information contained in the individual designation signal Sd[m] will be referred to as bits S1, S2, and S3, and the individual designation signal Sd[m] = [S1, S2, S3] will be used.In addition, in the following explanation, if the bits S1, S2, and S3 contained in the individual designation signal Sd[m] can be either "1" or "0", then "*" will be used to represent it. 【0080】 Specifically, the control unit 2 generates a print data signal SI that includes individual designation signals Sd[1] to Sd[M] that define the driving mode of the ejection units D[1] to D[M] and the operation of the detection circuit 33 during the unit period TP to be controlled, prior to the unit period TP to be controlled, and outputs it to the connection state designation circuit 310. The print data signal SI is held in a register (not shown) in the connection state designation circuit 310, with the individual designation signals Sd[1] to Sd[M] corresponding to each of the ejection units D[1] to D[M]. Then, when it becomes the unit period TP to be controlled, the connection state designation circuit 310 simultaneously latches the 3 bits of information contained in each of the individual designation signals Sd[1] to Sd[M] that it holds, and decodes the latched 3 bits of information to generate connection state designation signals Qc[1] to Qc[M], Qs[m] to Qs[M], Qf, Q1, and Q2 at a logic level corresponding to the decoded content for each of the control periods TQ1 and TQ2, or each of the control periods TT1 to TT5, within the unit period TP to be controlled, and outputs them to the respective control terminals of the switches Wc[1] to Wc[M], Ws[1] to Ws[M], Wf, W1, and W2. 【0081】 This controls the conduction state of switches Wc[1]~Wc[M], Ws[1]~Ws[M], Wf, W1, and W2 during each of the control periods TQ1 and TQ2, or each of the control periods TT1 to TT5. As a result, the driving mode of the discharge units D[1]~D[M] and the operation of the detection circuit 33 are controlled during each of the control periods TQ1 and TQ2, or each of the control periods TT1 to TT5. 【0082】 Returning to Figure 6, the detection circuit 33 receives the detection potential signal VX propagating through the wiring Ls and the connection status specification signals Q1 and Q2 output by the connection status specification circuit 310. The detection circuit 33 also includes a waveform shaping circuit 330 and an AD conversion circuit 331. The waveform shaping circuit 330 acquires the detection potential signal VX according to the connection status specification signals Q1 and Q2. The waveform shaping circuit 330 then removes noise from the acquired detection potential signal VX and amplifies it to shape the signal waveform of the detection potential signal VX, outputting it as the detection signal aSK. The AD conversion circuit 331 converts the analog signal of the detection signal aSK output by the waveform shaping circuit 330 into a digital signal and outputs it as the detection signal SK. This detection signal SK is output from the detection circuit 33 and the head unit 3. In other words, the detection circuit 33 converts the signal corresponding to the residual vibration generated in the ejection section D into a digital signal and outputs it as the detection signal SK. In other words, the detection circuit 33 acquires a detection potential signal VX corresponding to the residual vibration generated in the discharge section D and outputs it as a detection signal SK. At this time, the detection circuit 33 in this embodiment includes an AD conversion circuit 331, which converts the acquired detection potential signal VX into a digital signal, thereby converting the detection signal SK into a digital signal. Outputs. 【0083】 Here, an example of the configuration of the waveform shaping circuit 330 included in the detection circuit 33 will be described. Figure 9 is a diagram showing an example of the configuration of the waveform shaping circuit 330. As shown in Figure 9, the waveform shaping circuit 330 includes a capacitor C1, operational amplifiers OP1 and OP2, switches W1 and W2, and resistors R1 to R3. 【0084】 A detection potential signal VX output by the supply switching circuit 31 is input to one end of capacitor C1. The other end of capacitor C1 is electrically connected to one end of resistor R1 and one end of switch W1. Analog ground AG, fixed at a constant potential, is supplied to the other end of resistor R1 and the other end of switch W1. In other words, resistor R1 and switch W1 are connected in parallel. A connection state specification signal Q1 is input to the control terminal of switch W1. When a high-level connection state specification signal Q1 is input to the control terminal of switch W1, the connection between one end and the other becomes conductive, and when a low-level connection state specification signal Q1 is input to the control terminal, the connection between one end and the other becomes non-conductive. In other words, switch W1 switches the conduction state between one end of resistor R1 and analog ground AG. The capacitor C1, resistor R1, and switch W1 configured as described above function as a high-pass filter, extracting and outputting a predetermined high-frequency component signal from the detected potential signal VX input during the period when switch W1 is controlled to be non-conductive. Here, switch W1 may be configured as a transmission gate, for example, as shown in Figure 7. The analog ground AG may also be, for example, the center potential between the high-potential power supply potential and the low-potential power supply potential supplied to the head unit 3. 【0085】 The positive input terminal of operational amplifier OP1 is electrically connected to the connection point where the other end of capacitor C1, one end of resistor R1, and one end of switch W1 are electrically connected. In other words, the signal output by the high-pass filter composed of capacitor C1, resistor R1, and switch W1 is input to the positive input terminal of operational amplifier OP1. The negative input terminal of operational amplifier OP1 is electrically connected to the connection point where one end of resistor R2 and one end of resistor R3 are electrically connected. The output terminal of operational amplifier OP1 is electrically connected to the other end of resistor R2. In addition, analog ground AG is supplied to the other end of resistor R3. In other words, operational amplifier OP1 and resistors R2 and R3 function as a non-inverting amplifier circuit that amplifies the signal input to the positive input terminal of operational amplifier OP1 according to the resistance values ​​of resistors R2 and R3 and outputs it from the output terminal of operational amplifier OP1. Here, the non-inverting amplifier circuit, which includes the operational amplifier OP1 and resistors R2 and R3, may be configured to output an amplified signal after superimposing a predetermined offset voltage onto the signal output by a high-pass filter consisting of capacitor C1, resistor R1, and switch W1. 【0086】 The positive input terminal of op-amp OP2 is electrically connected to the output terminal of op-amp OP1. In other words, the signal output by the non-inverting amplifier circuit, which consists of op-amp OP1 and resistors R2 and R3, is input to the positive input terminal of op-amp OP2. The negative input terminal of op-amp OP2 is electrically connected to the output terminal of op-amp OP2. In other words, op-amp OP2 constitutes a voltage follower circuit. As a result, op-amp OP2 converts the impedance of the signal output by the non-inverting amplifier circuit, which consists of op-amp OP1 and resistors R2 and R3, and outputs it. 【0087】 One end of switch W2 is electrically connected to the output terminal of operational amplifier OP2. The signal from the other end of switch W2 is output from the waveform shaping circuit 330 as the detection signal aSK. A connection status specification signal Q2 is input to the control end of switch W2. When a high-level connection status specification signal Q2 is input to the control end of switch W2, conduction occurs between the one end and the other end. When a low-level connection status specification signal Q2 is input to the control end, conduction occurs between the one end and the other end. The section between these two points becomes non-conductive. This switch W2 switches whether or not the signal output by the operational amplifier OP2 is output from the waveform shaping circuit 330 as a detection signal aSK, depending on the logic level of the connection status specification signal Q2 input to the control terminal. 【0088】 As described above, the waveform shaping circuit 330 removes noise components from the detected potential signal VX using a high-pass filter consisting of a capacitor C1, a resistor R1, and a switch W1. The signal from which the noise components have been removed is then amplified by a non-inverting amplifier circuit consisting of an operational amplifier OP1 and resistors R2 and R3. The waveform shaping circuit 330 then performs impedance conversion using a voltage follower circuit consisting of an operational amplifier OP2, and outputs the signal as the detected signal aSK. At this time, switches W1 and W2 switch whether or not the waveform shaping circuit 330 acquires the detected potential signal VX and outputs it as the detected signal aSK. 【0089】 The detection signal aSK output by the waveform shaping circuit 330 is then input to the AD conversion circuit 331. The AD conversion circuit 331 converts the detection signal aSK into a digital signal. The signal converted to digital by the AD conversion circuit 331 is then output as the detection signal SK from the detection circuit 33 and the head unit 3. 【0090】 In the head unit 3 of this embodiment, configured as described above, the supply switching circuit 31 controls the conduction state of switch Wc[m] in accordance with the print data signal SI propagated based on the clock signal CL during each of the control periods TQ1, TQ2, or control periods TT1 to TT5 defined by the latch signal LAT, change signal CH, and period specification signal Tsig. This switches whether or not to supply the drive signal Com propagating through the wiring Ls as the supply drive signal Vin[m] to the piezoelectric element PZ[m] of the ejection unit D[m]. This controls the driving mode of the ejection unit D[m]. 【0091】 Furthermore, in this embodiment, the head unit 3 has a supply switching circuit 31 that controls the conduction state of switch Ws[m] in accordance with the print data signal SI propagated based on the clock signal CL during each of the control periods TQ1, TQ2 or control periods TT1 to TT5 defined by the latch signal LAT, the change signal CH, and the period specification signal Tsig. This allows the circuit to acquire a signal corresponding to the residual vibration generated in the ejection section D[m] and switch whether or not to output it to the detection circuit 33 as a detected potential signal VX. At this time, the detection circuit 33 amplifies and shapes the signal waveform of the input detected potential signal VX according to the conduction state of switches W1 and W2 and outputs it as a detected signal SK. 【0092】 In other words, the detection circuit 33 acquires the electromotive force generated in the piezoelectric element PZ as a detection potential signal VX when the piezoelectric element PZ is displaced in response to residual vibrations generated in the discharge section D, amplifies and shapes the signal waveform of the acquired detection potential signal VX, and outputs it as a detection signal SK. 【0093】 The detection signal SK output by the detection circuit 33 is then input to the determination unit 6. The determination unit 6 determines the state of the target discharge section D[m] based on the input detection signal SK. In other words, the liquid discharge device 1 of this embodiment includes a determination unit 6 that determines the state of the discharge section D to be inspected according to the detection signal SK. 【0094】 Here, the supply switching circuit 31 of the head unit 3 is composed of one or more semiconductor devices. In this case, part or all of the detection circuit 33 may be mounted together with the supply switching circuit 31 on the semiconductor device. 【0095】 As described above, the liquid dispensing device 1 of this embodiment includes a piezoelectric element PZ to which a supply drive signal Vin corresponding to a drive signal Com is supplied, and dispenses ink in accordance with the drive of the piezoelectric element PZ. The system also includes a plurality of discharge units D that output signals corresponding to residual vibrations that occur after the piezoelectric element PZ is driven, a detection circuit 33 that acquires one of the signals corresponding to residual vibrations that occur after the piezoelectric element PZ is driven, output by each of the plurality of discharge units D, and outputs a detection signal SK corresponding to the acquired signal, switches Ws[1] to Ws[m] that switch whether or not to supply a signal corresponding to residual vibrations that occur after the piezoelectric element PZ is driven to the detection circuit 33, and a determination unit 6 that determines the state of the discharge unit D according to the detection signal SK. 【0096】 1.4 Operation of the liquid ejection device and head unit during the printing process The operation of the liquid dispensing device 1 configured as described above will now be explained. As previously stated, the liquid dispensing device 1 of this embodiment performs a dispensing process in which ink is dispensed onto the medium P to form an image corresponding to the image data signal Img, and a determination process in which the state of the dispensing unit D that dispenses ink onto the medium P is determined. The operation of the dispensing process and the determination process performed by the liquid dispensing device 1 will be explained below. 【0097】 1.4.1 Discharge process Figure 10 is a diagram illustrating an example of various signals output by the control unit 2 during the period in which the dispensing process is being performed. 【0098】 The control unit 2 generates a drive waveform specification signal dCom that defines the signal waveform of the drive signal Com output by the drive signal output unit 4 during the period in which the ejection process is being performed, and outputs it to the drive signal output unit 4. In response to the input drive waveform specification signal dCom, the drive signal output unit 4 generates a drive signal Com with a continuous signal waveform consisting of a drive waveform PP1 placed in the control period TQ1 and a drive waveform PP2 placed in the control period TQ2 for each unit period TP as shown in Figure 10, and supplies it to the head unit 3. 【0099】 The drive waveform PP1 is a signal waveform in which the voltage value starts at a reference potential V0, changes to a potential VL1 which is lower than the reference potential V0, then becomes a potential VH1 which is higher than the reference potential V0, and then ends at the reference potential V0. When this drive waveform PP1 is supplied to the piezoelectric element PZ[m], the piezoelectric element PZ[m] is driven so that ink amount ξ1 is ejected from the nozzle N[m]. In other words, the drive waveform PP1 is a signal waveform that causes ink amount ξ1 to be ejected from the nozzle N[m]. 【0100】 The drive waveform PP2 is a signal waveform in which the voltage value starts at a reference potential V0, changes to a potential VL2 which is lower than the reference potential V0, then becomes a potential VH2 which is higher than the reference potential V0, and then ends at the reference potential V0. When this drive waveform PP2 is supplied to the piezoelectric element PZ[m], the piezoelectric element PZ[m] is driven so that ink amount ξ2 is ejected from the nozzle N[m]. In other words, the drive waveform PP2 is a signal waveform that causes ink amount ξ2 to be ejected from the nozzle N[m]. 【0101】 In this embodiment, the liquid dispensing device 1 forms multi-gradation dots on the medium P by selecting to form one of the following dots on the medium P: a large dot, a medium dot smaller than a large dot, or a small dot smaller than a medium dot, or by selecting not to form any dots at all, for each unit period TP during the dispensing process. That is, in this embodiment, the liquid dispensing device 1 selects whether to dispense an amount of ink equivalent to a large dot, an amount of ink equivalent to a medium dot, or an amount of ink equivalent to a small dot from the dispensing unit D[m] for each unit period TP during the dispensing process, or not to dispensing any ink. In this case, in the liquid dispensing device 1 of this embodiment, the amount of ink ξ1 dispensed from the dispensing unit D[m] when the drive waveform PP1 is supplied to the piezoelectric element PZ[m] is the amount of ink equivalent to a medium dot, and the amount of ink ξ2 dispensed from the dispensing unit D[m] when the drive waveform PP2 is supplied to the piezoelectric element PZ[m] is the amount of ink equivalent to a small dot, which is a smaller amount of ink than the amount of ink ξ1. This explanation assumes that the total amount of ink volume ξ1 and ink volume ξ2 corresponds to the amount of ink equivalent to a large dot. 【0102】 Furthermore, during the period in which the liquid dispensing device 1 of this embodiment is performing the dispensing process, the individual designation signal Sd[m] input to the connection state designation circuit 310 controls whether, for each unit period TP, a supply drive signal Vin[m] including the drive waveform PP1 located in the control period TQ1 and the drive waveform PP2 located in the control period TQ2 is supplied to the dispensing unit D[m], whether a supply drive signal Vin[m] including the drive waveform PP1 located in the control period TQ1 is supplied to the dispensing unit D[m], whether a supply drive signal Vin[m] including the drive waveform PP2 located in the control period TQ2 is supplied to the dispensing unit D[m], or whether a supply drive signal Vin[m] that does not include either the drive waveform PP1 located in the control period TQ1 or the drive waveform PP2 located in the control period TQ2 is supplied to the dispensing unit D[m]. This controls whether, during a unit period TP in which the liquid dispensing device 1 is performing the dispensing process, the dispensing section D[m] dispenses an amount of ink equivalent to a large dot, an amount of ink equivalent to a medium dot, an amount of ink equivalent to a small dot, or no ink at all. As a result, the dot size formed on the medium P is controlled. 【0103】 Here, we will explain an example of the relationship between the individual designation signals Sd[1]~Sd[M] included in the print data signal SI input to the connection status designation circuit 310 during the period when the liquid discharge device 1 is performing the discharge process, and the connection status designation signals Qc[1]~Qc[M], Qs[1]~Qs[M] output by the connection status designation circuit 310, specifically the decoding content of the individual designation signals Sd[1]~Sd[M] performed by the connection status designation circuit 310. 【0104】 Figure 11 shows an example of the relationship between the individual designation signal Sd[m] and the connection status designation signals Qc[m] and Qs[m] during the period in which the discharge process is being performed. 【0105】 As shown in Figure 11, when the individual specification signal Sd[m]=[0,1,1] is input to the connection state specification circuit 310, the connection state specification circuit 310 generates a connection state specification signal Qc[m] that is at an H level during control period TQ1 and at an H level during control period TQ2, and outputs it to the control terminal of the switch Wc[m]. As a result, the switch Wc[m] is controlled to conduct during control period TQ1 and to conduct during control period TQ2. Therefore, the piezoelectric element PZ[m] is supplied with a supply drive signal Vin[m] including the drive waveform PP1 during control period TQ1, and with a supply drive signal Vin[m] including the drive waveform PP2 during control period TQ2. Consequently, ink with an ink amount ξ1 is ejected from the nozzle N[m] during control period TQ1, and ink with an ink amount ξ2 is ejected during control period TQ2. Then, the ink amount ξ1 ejected during control period TQ1 and the ink amount ξ2 ejected during control period TQ2 land on the medium P and combine, forming large dots on the medium P during unit period TP. 【0106】 Furthermore, when the individual specification signal Sd[m]=[0,1,0] is input to the connection state specification circuit 310, the connection state specification circuit 310 generates a connection state specification signal Qc[m] that is at an H level during control period TQ1 and at an L level during control period TQ2, and outputs it to the control terminal of the switch Wc[m]. As a result, the switch Wc[m] is controlled to conduct during control period TQ1 and to not conduct during control period TQ2. Therefore, the piezoelectric element PZ[m] is supplied with a supply drive signal Vin[m] including the drive waveform PP1 during control period TQ1, and is not supplied with a supply drive signal Vin[m] including the drive waveform PP2 during control period TQ2. Here, during the control period TQ2 in which the supply drive signal Vin[m] including the drive waveform PP2 is not supplied to the piezoelectric element PZ[m], the upper electrode Zu[m] has a voltage value of the signal that was supplied to the upper electrode Zu[m] immediately before, where the reference potential V0 is equal to the piezoelectric element PZ[m] It is held by the capacitance component of ]. That is, during the control period TQ2 in which the supply drive signal Vin[m] including the drive waveform PP2 is not supplied to the piezoelectric element PZ[m], a constant signal at a reference potential V0 is supplied to the upper electrode Zu[m]. As a result, ink amount ξ1 is ejected from the nozzle N[m] during the control period TQ1, and no ink is ejected during the control period TQ2. Then, the ink amount ξ1 ejected during the control period TQ1 lands on the medium P, forming a medium dot on the medium P during the unit period TP. 【0107】 Furthermore, when the individual specification signal Sd[m]=[0,0,1] is input to the connection state specification circuit 310, the connection state specification circuit 310 generates a connection state specification signal Qc[m] that is L level during control period TQ1 and H level during control period TQ2, and outputs it to the control terminal of switch Wc[m]. As a result, switch Wc[m] is controlled to be non-conductive during control period TQ1 and conductive during control period TQ2. Therefore, the piezoelectric element PZ[m] is not supplied with a supply drive signal Vin[m] including the drive waveform PP1 during control period TQ1, but is supplied with a supply drive signal Vin[m] including the drive waveform PP2 during control period TQ2. Here, during the control period TQ1 in which the supply drive signal Vin[m] including the drive waveform PP1 is not supplied to the piezoelectric element PZ[m], the upper electrode Zu[m] maintains a reference potential V0, which is the voltage value of the signal that was supplied to the upper electrode Zu[m] immediately before, due to the capacitive component of the piezoelectric element PZ[m]. That is, during the control period TQ1 in which the supply drive signal Vin[m] including the drive waveform PP1 is not supplied to the piezoelectric element PZ[m], a constant signal with a reference potential V0 is supplied to the upper electrode Zu[m]. As a result, no ink is ejected from the nozzle N[m] during the control period TQ1, and ink amount ξ2 is ejected during the control period TQ2. Then, the ink amount ξ2 ejected during the control period TQ2 lands on the medium P, forming small dots on the medium P during the unit period TP. 【0108】 Furthermore, when the individual specification signal Sd[m]=[0,0,0] is input to the connection state specification circuit 310, the connection state specification circuit 310 generates a connection state specification signal Qc[m] that is L level during control period TQ1 and L level during control period TQ2, and outputs it to the control terminal of switch Wc[m]. As a result, switch Wc[m] is controlled to be non-conductive during control period TQ1 and non-conductive during control period TQ2. Therefore, the piezoelectric element PZ[m] is not supplied with a supply drive signal Vin[m] including the drive waveform PP1 during control period TQ1, and is not supplied with a supply drive signal Vin[m] including the drive waveform PP2 during control period TQ2. Here, during control period TQ1, in which the supply drive signal Vin[m] including the drive waveform PP1 is not supplied to the piezoelectric element PZ[m], and during control period TQ2, in which the supply drive signal Vin[m] including the drive waveform PP2 is not supplied, the upper electrode Zu[m] maintains a reference potential V0, which is the voltage value of the signal that was supplied to the upper electrode Zu[m] immediately before, due to the capacitive component of the piezoelectric element PZ[m]. That is, during control period TQ1, in which the supply drive signal Vin[m] including the drive waveform PP1 is not supplied to the piezoelectric element PZ[m], and during control period TQ2, in which the supply drive signal Vin[m] including the drive waveform PP2 is not supplied, a constant signal with a reference potential V0 is supplied to the upper electrode Zu[m]. As a result, no ink is ejected from the nozzle N[m] during control period TQ1, and no ink is ejected during control period TQ2. Therefore, no dots are formed on the medium P during the unit period TP. 【0109】 As described above, when the liquid dispensing device 1 performs dispensing, the connection state specification circuit 310 outputs logic-level connection state specification signals Qs[1] to Qs[M] based on individual specification signals Sd[1] to Sd[M] during each of the control periods TQ1 and TQ2 within the unit period TP. This controls the conduction state of switches Wc[1] to Wc[m] during the control periods TQ1 and TQ2 within the unit period TP, and controls the amount of ink dispensed from each of the dispensing units D[1] to D[M] during the control periods TQ1 and TQ2 within the unit period TP. In other words, the dot size formed on the medium P during the unit period TP is controlled. As a result, the liquid dispensing device 1 controls the image during the period in which the dispensing process is performed. An image corresponding to the data signal Img can be formed on the medium P. 【0110】 Here, as shown in Figure 11, during the period when the liquid dispensing device 1 is performing the dispensing process, the connection state designation circuit 310 continues to output a connection state designation signal Qs[m] at an L level, regardless of the input individual designation signal Sd[m]. Therefore, during the period when the dispensing process is being performed, the switch Ws[m] is controlled to be non-conductive. As a result, during the period when the liquid dispensing device 1 is performing the dispensing process, the upper electrode Zu[m] and the wiring Ls are not electrically connected, and therefore, the signal corresponding to the residual vibration generated in the dispensing section D[m] is not supplied to the detection circuit 33. Therefore, the detection circuit 33 does not acquire the detection potential signal VX during the period when the liquid dispensing device 1 is performing the dispensing process. For this reason, although not shown in the figure, during the period when the liquid dispensing device 1 is performing the dispensing process, the connection state designation circuit 310 continues to output connection state designation signals Qf, Q1, and Q2 at an L level. 【0111】 Furthermore, during the period when the liquid dispensing device 1 is performing the dispensing process, the control unit 2 generates an H-level output enable signal EN1 and an L-level output enable signal EN2, and outputs them to the power supply unit 5. As a result, during the period when the liquid dispensing device 1 is performing the dispensing process, the switching power supply circuit 50 outputs a voltage signal Vsw, and the linear power supply circuit 55 stops outputting a voltage signal Vln. Therefore, the power supply unit 5 outputs the voltage signal Vsw output by the switching power supply circuit 50 as a power supply voltage signal VHV. 【0112】 Here, the losses of transistors 521 and 522 in the switching power supply circuit 50 are smaller than the losses of transistor 57 in the linear power supply circuit 55. Therefore, the power consumption of the switching power supply circuit 50 when it generates a voltage signal Vsw from the power supply voltage signal VDC is smaller than the power consumption of the linear power supply circuit 55 when it generates a voltage signal Vln from the power supply voltage signal VDC. In other words, in the liquid dispensing device 1 of this embodiment, the power consumption of the power supply unit 5 during the period in which the dispensing process is performed can be reduced. To put it another way, during the period in which the dispensing process is performed in which ink is dispensed from the dispensing unit D, the power supply unit 5 outputs the voltage signal Vsw as the power supply voltage signal VHV. 【0113】 1.4.2 State determination process Next, we will explain the determination process for determining the state of the ejection unit D that ejects ink onto the medium P. It is known that residual vibration occurs in an ejection unit that ejects liquid such as ink by being driven by a driving element such as a piezoelectric element after the driving element has been driven. This residual vibration that occurs in the ejection unit is a so-called damped vibration in which the amplitude decreases over time, and the waveform information such as the amplitude, the rate of amplitude damping, the period, and the frequency of the damped vibration changes depending on the state of the ejection unit. For example, if the viscosity of the liquid stored in the ejection unit changes, the amplitude and the rate of amplitude damping of the residual vibration that occurs in the ejection unit will change, and if air bubbles are mixed inside the ejection unit, for example, the frequency of the residual vibration that occurs in the ejection unit will increase. 【0114】 In the liquid dispensing device 1 of this embodiment, in the determination process for determining the state of the dispensing unit D that dispenses ink onto the medium P, the supply switching circuit 31 of the head unit 3 acquires a signal corresponding to the residual vibration generated in the dispensing unit D[m] to be inspected and outputs it to the detection circuit 33 as a detected potential signal VX. The detection circuit 33 generates a detected signal SK by shaping the signal waveform of the input detected potential signal VX. Then, the determination unit 6 calculates waveform information such as the amplitude, period, and frequency of the residual vibration generated in the dispensing unit D[m] to be inspected, which is the waveform information of the detected potential signal VX based on the input detected signal SK, and determines the state of the dispensing unit D[m] to be inspected based on the calculated waveform information. After that, the determination unit 6 generates a state determination signal JH indicating the determination result and outputs it to the control unit 2. As a result, the control unit 2 acquires the state of the dispensing unit D[m] to be inspected and corrects the various signals to be output according to the acquired state of the dispensing unit D[m] to be inspected, or informs the user of the state of the dispensing unit D[m] to be inspected. It can report the state of [m]. 【0115】 Figure 12 is a diagram illustrating an example of various signals input to the supply switching circuit 31 of the head unit 3 during the period in which the determination process is being executed. 【0116】 The control unit 2 generates a drive waveform specification signal dCom that defines the signal waveform of the drive signal Com output by the drive signal output unit 4 during the period in which the determination process is being executed, and outputs it to the drive signal output unit 4. The drive signal output unit 4 generates a drive signal Com including the drive waveform PS for each unit period TP as shown in Figure 12, according to the input drive waveform specification signal dCom, and supplies it to the head unit 3. 【0117】 The drive waveform PS is a signal waveform in which the voltage value starts at a reference potential V0 during the control period TT1, changes to a potential VS1 which is lower than the reference potential V0, then becomes a potential VS2 which is higher than the reference potential V0, maintains the potential VS2 during the control periods TT2, TT3, and TT4, and ends at the reference potential V0 during the control period TT5. When this drive waveform PS is supplied to the piezoelectric element PZ[m], the piezoelectric element PZ[m] is driven so that ink is not ejected from the nozzle N[m], and after the piezoelectric element PZ[m] is driven, a predetermined residual vibration occurs in the ejection section D[m] at the timing when the voltage value of the drive signal Com becomes the potential VS2. In other words, the drive waveform PS is a signal waveform that drives the piezoelectric element PZ[m] so that ink is not ejected from the nozzle N[m], and a predetermined residual vibration occurs in the ejection section D[m], and when the drive waveform PS is supplied to the piezoelectric element PZ[m], it is driven so that ink is not ejected from the ejection section D[m] and residual vibration occurs. 【0118】 During the period when the liquid dispensing device 1 performs the determination process, the connection state designation circuit 310 controls the conduction state of switches Wc[1]~Wc[M], Ws[1]~Ws[M], Wf, W1, and W2 based on the individual designation signals Sd[1]~Sd[M] included in the print data signal SI during each of the control periods TT1~TT5. This supplies a supply drive signal Vin[m] including the drive waveform PS to the dispensing unit D[m] under inspection, and acquires a signal corresponding to the residual vibration generated in the dispensing unit D[m] under inspection as a result of the supply drive signal Vin[m] including the drive waveform PS being supplied, and outputs it to the detection circuit 33 as a detected potential signal VX. The detection circuit 33 then generates a detection signal SK by shaping the signal waveform of the input detected potential signal VX, and the determination unit 6 determines the state of the dispensing unit D[m] under inspection based on the detection signal SK. 【0119】 Here, we will explain an example of the relationship between the individual designation signals Sd[1]~Sd[M] included in the print data signal SI input to the connection status designation circuit 310 during the period when the liquid discharge device 1 performs a determination process, and the connection status designation signals Qc[1]~Qc[M], Qs[1]~Qs[M], Qf, Q1, Q2 output by the connection status designation circuit 310, specifically the decoding content of the individual designation signals Sd[1]~Sd[M] performed by the connection status designation circuit 310 during the period when the determination process is being executed. 【0120】 Figure 13 shows an example of the relationship between the individual designation signal Sd[m] and the connection status designation signals Qc[m] and Qs[m] during the period in which the judgment process is being executed. Here, in the liquid dispensing device 1 of this embodiment, the control unit 2 outputs the individual designation signal Sd[m]=[1,0,0] to the connection status designation circuit 310 when the dispensing unit D[m] is not the object of inspection during the period in which the judgment process is being executed, and outputs the individual designation signal Sd[m]=[1,0,1] to the connection status designation circuit 310 when the dispensing unit D[m] is the object of inspection. 【0121】 As shown in Figure 13, when the individual designation signal Sd[m]=[1,0,0] is input to the connection state designation circuit 310, the connection state designation circuit 310 will be L-type during the control period TT1 to TT5. A connection status specification signal Qc[m] that is a bell is generated and output to the control terminal of switch Wc[m], and a connection status specification signal Qs[m] that is at an L level during the control period TT1 to TT5 is generated and output to the control terminal of switch Ws[m]. As a result, during the control period TT1 to TT5, switch Wc[m] is controlled to be non-conductive and switch Ws[m] is controlled to be non-conductive. At this time, the piezoelectric element PZ[m] of the discharge section D[m] that is not being inspected is not supplied with a supply drive signal Vin[m] corresponding to the drive signal Com. Therefore, no residual vibration occurs in the discharge section D[m] that is not being inspected, and even if the potential of the upper electrode Zu[m] of the piezoelectric element PZ[m] included in the discharge section D[m] that is not being inspected changes, the signal associated with the change in potential is not supplied to the wiring Ls. Therefore, the state of the discharge section D[m] that is not being inspected is not determined. 【0122】 Furthermore, when the individual specification signal Sd[m]=[1,0,1] is input to the connection state specification circuit 310, the connection state specification circuit 310 generates a connection state specification signal Qc[m] which is at a high level during control periods TT1, TT2, and TT5 and at a low level during control periods TT3 and TT4, and outputs it to the control terminal of switch Wc[m]. It also generates a connection state specification signal Qs[m] which is at a high level during control periods TT2 to TT4 and at a low level during control periods TT1 and TT5, and outputs it to the control terminal of switch Ws[m]. As a result, switch Wc[m] is controlled to conduct during control periods TT1, TT2, and TT5 and to be non-conductive during control periods TT3 and TT4, and switch Ws[m] is controlled to conduct during control periods TT2 to TT4 and to be non-conductive during control periods TT1 and TT5. 【0123】 Figure 14 shows an example of the relationship between the individual designation signal Sd[m] and the connection status designation signals Qf, Q1, and Q2 during the period in which the judgment process is being executed. Here, during the period in which the judgment process is being executed, the connection status designation circuit 310 outputs connection status designation signals Qf, Q1, and Q2 of the same logic level in each of the control periods TT1 to TT5, depending on whether the individual designation signal Sd[m]=[1,0,0] or the individual designation signal Sd[m]=[1,0,1] is input. Therefore, in Figure 14, the individual designation signal Sd[m]=[1,0,0] and the individual designation signal Sd[m]=[1,0,1] are shown together as the individual designation signal Sd[m]=[1,0,*]. 【0124】 As shown in Figure 14, when the individual designation signal Sd[m]=[1,0,*] is input to the connection state designation circuit 310, the connection state designation circuit 310 generates a connection state designation signal Qf that is at a high level during control periods TT2 to TT4 and at a low level during control periods TT1 and TT5, and outputs it to the control terminal of switch Wf. It also generates a connection state designation signal Q1 that is at a high level during control periods TT1, TT2, TT4, and TT5 and at a low level during control period TT3, and outputs it to the control terminal of switch W1. Finally, it generates a connection state designation signal Q2 that is at a high level during control period TT3 and at a low level during control periods TT1, TT2, TT4, and TT5, and outputs it to the control terminal of switch W2. As a result, switch Wf is controlled to conduct during control periods TT2 to TT4 and to not conduct during control periods TT1 and TT5; switch W1 is controlled to conduct during control periods TT1, TT2, TT4, and TT5 and to not conduct during control period TT3; and switch W2 is controlled to conduct during control period TT3 and to not conduct during control periods TT1, TT2, TT4, and TT5. 【0125】 Here, we will describe an example of the operation of the liquid dispensing device 1 when an individual designation signal Sd[m]=[1,0,1] is input to the connection state designation circuit 310, in which the detection circuit 33 acquires a detection potential signal VX based on a signal corresponding to residual vibrations occurring in the dispensing section D[m] to be inspected. Figure 15 is a diagram illustrating an example of the acquisition operation of a detection potential signal VX based on a signal corresponding to residual vibrations occurring in the dispensing section D[m] to be inspected. 【0126】 As shown in Figure 15, for each unit period TP during the period in which the determination process is being executed, connection The state specification circuit 310 is supplied with a drive signal Com that includes a drive waveform PS, the voltage value of which starts at a reference potential V0 during the control period TT1, changes to a potential VS1 that is lower than the reference potential V0, then becomes a potential VS2 that is higher than the reference potential V0, maintains the potential VS2 during the control periods TT2 to TT4, and ends at the reference potential V0 during the control period TT5. 【0127】 During the period in which the judgment process is being executed, the control unit 2 outputs an individual designation signal Sd[m]=[1,0,1] corresponding to the discharge section D[m] to be inspected to the connection state designation circuit 310. At this time, discharge sections D[1]~D[m-1] and D[m+1]~D[M] are excluded from inspection. That is, the control unit 2 outputs individual designation signals Sd[1]~Sd[m-1] and Sd[m+1]~Sd[M]=[1,0,0] to the connection state designation circuit 310. 【0128】 When a print data signal SI including the individual designation signal Sd[m]=[1,0,1] and the individual designation signals Sd[1]~Sd[m-1],Sd[m+1]~Sd[M]=[1,0,0] is input to the connection state designation circuit 310, during the control periods TT1 and TT2, switch Wc[m] is controlled to conduct, and switches Wc[1]~Wc[m-1],Wc[m+1]~Wc[M] are controlled to not conduct. Therefore, during control periods TT1 and TT2, the upper electrode Zu[m] is supplied with a supply drive signal Vin[m] whose voltage value starts at the reference potential V0, changes to a potential VS1 lower than the reference potential V0, then becomes a potential VS2 higher than the reference potential V0, and maintains the potential VS2. Subsequently, the upper electrodes Zu[1]~Zu[m-1] and Zu[m+1]~Zu[M] maintain the reference potential V0. At this time, residual vibration occurs in the discharge section D[m] under inspection at the timing when the voltage value of the supplied supply drive signal Vin[m] becomes constant at potential VS2. Then, the piezoelectric element Zm[m] deforms in response to the residual vibration generated in the discharge section D[m] under inspection, and an electromotive force corresponding to the deformation of the piezoelectric element Zm[m] is generated in the upper electrode Zu[m]. In other words, a signal corresponding to the residual vibration generated in the discharge section D[m] under inspection is generated in the upper electrode Zu[m] of the piezoelectric element PZ[m] included in the discharge section D[m] under inspection. In other words, the discharge section D[m] includes a piezoelectric element PZ[m] that outputs a signal corresponding to the electromotive force corresponding to the residual vibration. 【0129】 During the control period TT2, switch Ws[m] is controlled to conduct, switches Ws[1]~Ws[m-1] and Ws[m+1]~Ws[M] are controlled to be non-conductive, and switch Wf is controlled to conduct. As a result, a signal corresponding to the residual vibration generated in the discharge section D[m] of the object being inspected propagates through the wiring Ls as a detected potential signal VX. At this time, switch W1 is controlled to conduct and switch W2 is controlled to be non-conductive. Therefore, during the control period TT2, the waveform shaping circuit 330 of the detection circuit 33 does not acquire the detected potential signal VX propagating through the wiring Ls, and therefore does not output a detected signal aSK corresponding to the detected potential signal VX. 【0130】 Then, during the control period TT3, switch W1 is controlled to be non-conductive and switch W2 is controlled to be conductive, so the waveform shaping circuit 330 of the detection circuit 33 acquires a detection potential signal VX that corresponds to the residual vibration generated in the discharge section D[m] of the object to be inspected and propagates through the wiring Ls, and shapes the signal waveform of the acquired detection potential signal VX and outputs it as a detection signal aSK. This detection signal aSK output by the waveform shaping circuit 330 is converted into a digital signal by the AD conversion circuit 331 and then input to the judgment unit 6 as a detection signal SK. 【0131】 The judgment unit 6 calculates waveform information such as amplitude, period, and frequency of the detected potential signal VX, based on the input detection signal SK, and also calculates waveform information such as amplitude, period, and frequency of residual vibration generated at the discharge section D [m] of the object to be inspected. Then, the judgment unit 6 uses the calculated waveform information to determine the waveform information Based on this, the state of the discharge section D[m] to be inspected is determined, and a state determination signal JH indicating the determination result is output to the control unit 2. 【0132】 During the subsequent control period TT4, switch W1 is controlled to conduct and switch W2 is controlled to deconduct, causing the waveform shaping circuit 330 to stop acquiring the detection potential signal VX propagating through the wiring Ls and to stop outputting the detection signal aSK. Then, during the control period TT5, switch Wc[m] is controlled to conduct and switch Ws[m] is controlled to deconduct, stopping the supply of the signal generated at the upper electrode Zu[m] to the wiring Ls, and simultaneously supplying a reference potential V0 drive signal Vin[m] to the upper electrode Zu[m] of the piezoelectric element PZ[m] of the discharge unit D[m] under inspection. As a result, the potential of the upper electrode Zu[m] of the piezoelectric element PZ[m] of the discharge unit D[m] under inspection is controlled to the reference potential V0. 【0133】 Furthermore, as shown in Figure 12, during the control periods TT1 and TT5 while the liquid dispensing device 1 is performing its decision-making process, the control unit 2 generates an H-level output enable signal EN1 and an L-level output enable signal EN2, and outputs them to the power supply unit 5. As a result, during the control periods TT1 and TT5 while the liquid dispensing device 1 is performing its decision-making process, the switching power supply circuit 50 outputs a voltage signal Vsw, and the linear power supply circuit 55 stops outputting a voltage signal Vln. Therefore, during the control periods TT1 and TT5 while the liquid dispensing device 1 is performing its decision-making process, the power supply unit 5 outputs the voltage signal Vsw as a power supply voltage signal VHV. 【0134】 Furthermore, during the control period TT2 to TT4 while the liquid dispensing device 1 is performing its judgment process, the control unit 2 generates an L-level output enable signal EN1 and an H-level output enable signal EN2, and outputs them to the power supply unit 5. As a result, during the control period TT2 to TT4 while the liquid dispensing device 1 is performing its judgment process, the switching power supply circuit 50 stops outputting the voltage signal Vsw, and the linear power supply circuit 55 outputs the voltage signal Vln. Therefore, during the control period TT2 to TT4 while the liquid dispensing device 1 is performing its judgment process, the power supply unit 5 outputs the voltage signal Vln output by the linear power supply circuit 55 as the power supply voltage signal VHV. In other words, during the control period TT3, when the detection circuit 33 acquires a signal corresponding to the residual vibration generated in the dispensing section D[m] under inspection as a detection potential signal VX, the power supply unit 5 outputs the voltage signal Vln output by the linear power supply circuit 55 as the power supply voltage signal VHV. In other words, during the period in which the determination process is executed, preferably during the control period TT2 to TT4 within the period in which the determination process is executed, the power supply unit 5 outputs the voltage signal Vln as the power supply voltage signal VHV. 【0135】 The switching power supply circuit 50 generates a pulse signal whose voltage value changes between the power supply voltage signal VHV and the ground potential through the operation of transistors 521 and 522 included in the switching circuit 52, and the smoothing circuit 53 smooths this pulse signal to generate a voltage signal Vsw. Therefore, while the switching power supply circuit 50 can reduce power consumption compared to the linear power supply circuit 55, a ripple voltage is superimposed on the output voltage signal Vsw. Therefore, during the period when the power supply unit 5 is outputting the voltage signal Vsw as the power supply voltage signal VHV, there is a risk that the ripple voltage superimposed on the voltage signal Vsw may be superimposed on the drive signal Com propagating through the wiring Lc, and on the detection potential signal VX, which corresponds to the residual vibration generated in the discharge section D[m] of the object being inspected and propagates through the wiring Ls, via the wiring pattern, the parasitic capacitance between the gate terminal, drain terminal, and source terminal of the transistors Wnm and Wpm of switches Wc[1]~Wc[M], Ws[1]~Ws[M], and Wf, respectively, and the parasitic capacitance between the back gate terminal, drain terminal, and source terminal of the transistor Wpm of switches Wc[1]~Wc[M], Ws[1]~Ws[M], and Wf, respectively. 【0136】 The voltage oscillation of the ripple voltage superimposed on the voltage signal Vsw output by the switching power supply circuit 50 The amplitude is generally around several tens of mV to 100 mV, which is sufficiently small compared to the voltage value of the drive signal Com, whose voltage amplitude is several tens of volts. Therefore, even if the ripple voltage superimposed on the voltage signal Vsw output by the switching power supply circuit 50 is superimposed on the drive signal Com, it will not have a significant effect on the ink ejection from the ejection unit D[m]. 【0137】 On the other hand, the voltage amplitude of the detected potential signal VX, which corresponds to the residual vibration generated in the discharge section D[m] under inspection, is only about tens of mV to 100 mV. Therefore, if a ripple voltage superimposed on the voltage signal Vsw is superimposed on the detected potential signal VX, which corresponds to the residual vibration generated in the discharge section D[m] under inspection, the waveform information of the detected potential signal VX, such as amplitude, amplitude attenuation rate, period, and frequency, changes significantly. In other words, the waveform accuracy of the signal waveform of the detected potential signal VX input to the detection circuit 33 decreases. As a result, the accuracy of the determination of the state of the discharge section D[m] under inspection by the determination unit 6 decreases. 【0138】 In the liquid dispensing device 1 of this embodiment, during the period in which a signal corresponding to the residual vibration generated in the dispensing section D[m] to be inspected is acquired as a detection potential signal VX, the power supply unit 5 outputs a voltage signal Vln output by a linear power supply circuit 55 that does not have ripple voltage superimposed on it as a power supply voltage signal VHV. This reduces the risk of a decrease in the signal accuracy of the detection potential signal VX, which corresponds to the residual vibration generated in the dispensing section D[m] to be inspected, and as a result, reduces the risk of a decrease in the judgment accuracy of the state of the dispensing section D[m] to be inspected by the judgment unit 6. 【0139】 Here, detection circuit 33 is an example of a residual vibration detection circuit, power supply unit 5 is an example of a power supply circuit, determination unit 6 is an example of a determination circuit, switch Ws[m] is an example of a first switch circuit, switch Wc[m] is an example of a second switch circuit, transistor Wpm is an example of a transistor element, and AD conversion circuit 331 is an example of an AD conversion circuit. Also, power supply voltage signal VDC is an example of a first power supply signal, power supply voltage signal VHV is an example of a second power supply signal, voltage signal Vln is an example of a first voltage signal, voltage signal Vsw is an example of a second voltage signal, detection potential signal VX is an example of a residual vibration signal, detection signal SK is an example of a residual vibration detection signal, connection state specification signal Qs[m] is an example of a first selection signal, and connection state specification signal Qc[m] is an example of a second selection signal. The period during which the determination process is performed is preferably an example of the first period, where the control period TT2 to TT4 within the period during which the determination process is performed is an example of the second period, where the ejection process in which ink is ejected from the ejection unit D is performed is an example of the second period. 【0140】 1.5 Effects As described above, the liquid dispensing device 1 of this embodiment includes a dispensing unit D that dispenses ink, which is an example of a liquid; a detection circuit 33 that acquires a detection potential signal VX corresponding to residual vibrations generated in the dispensing unit D and outputs it as a detection signal SK; a determination unit 6 that determines the state of the dispensing unit D to be inspected according to the detection signal SK; switches Ws[1]~Ws[M] that switch whether or not to supply the detection potential signal VX to the detection circuit 33; and a power supply that receives a power supply voltage signal VDC and supplies it to switches Wc[1]~Wc[M], Ws[1]~Ws[M], and Wf. The power supply unit 5 includes a power supply unit 5 that outputs a voltage signal VHV. The power supply unit 5 includes a linear power supply circuit 55 that receives a power supply voltage signal VDC and outputs a voltage signal Vln which is a 42V DC voltage, and a switching power supply circuit 50 that receives a power supply voltage signal VDC and outputs a voltage signal Vsw which is a 42V DC voltage. Depending on the input output enable signals EN1 and EN2, the power supply unit 5 outputs either the voltage signal Vln output by the linear power supply circuit 55 or the voltage signal Vsw output by the switching power supply circuit 50 as the power supply voltage signal VHV. In other words, the power supply unit 5 can select either the voltage signal Vsw output by the low-power switching power supply circuit 50 or the voltage signal Vln output by the linear power supply circuit 55 that does not generate ripple voltage, and output it as the power supply voltage signal VHV. 【0141】 Therefore, by switching switches Ws[1] to Ws[M], when supplying a signal corresponding to small residual vibrations as a detection potential signal VX to the detection circuit 33, the voltage signal Vln output by the linear power supply circuit 55 with a small ripple voltage can be supplied to switches Ws[1] to Ws[M] as a power supply voltage signal VHV. As a result, the risk of ripple voltages that can be superimposed on the power supply voltage signal VHV, which are voltage changes that occur in the power supply voltage signal VHV, contributing to the signal corresponding to small residual vibrations and the detection potential signal VX via switches Ws[1] to Ws[M] is reduced. Thus, the waveform accuracy of the detection potential signal VX acquired by the detection circuit 33 and the detection signal SK output by the detection circuit 33 is improved, and the judgment accuracy of the judgment unit 6 regarding the state of the discharge section D of the inspection target according to the detection signal SK is improved. In other words, the detection accuracy of residual vibrations occurring in the discharge section D of the inspection target is improved. 【0142】 Furthermore, in the liquid dispensing device 1 of this embodiment, the power supply unit 5 can select either the voltage signal Vsw output by the low-power switching power supply circuit 50 or the voltage signal Vln output by the linear power supply circuit 55 that does not generate ripple voltage, and output it as a power supply voltage signal VHV. Therefore, even if the switches Ws[1] to Ws[M] include transistors Wnm and Wpm that switch whether or not to supply the detection potential signal VX to the detection circuit 33, and the power supply voltage signal VHV is supplied to the back gate terminal of transistor Wpm to improve the operational stability of transistor Wpm, the detection accuracy of residual vibrations generated in the dispensing section D to be inspected can be improved. 【0143】 In particular, in the liquid dispensing device 1 of this embodiment, the power supply unit 5 outputs a voltage signal Vsw as a power supply voltage signal VHV during the period in which the dispensing process is performed, and outputs a voltage signal Vln as a power supply voltage signal VHV during the period in which the determination process is performed, preferably during the control period TT2 to TT4 within the period in which the determination process is performed. This allows the power supply unit 5 to optimally control the period in which the voltage signal Vln output by the linear power supply circuit 55, which has a higher power consumption than the switching power supply circuit 50, is output as a power supply voltage signal VHV. As a result, it is possible to achieve both a reduction in the power consumption of the liquid dispensing device 1 and an improvement in the detection accuracy of residual vibrations generated in the dispensing section D of the object to be inspected. 【0144】 2. Second Embodiment Next, the liquid dispensing device 1 of the second embodiment will be described. In describing the liquid dispensing device 1 of the second embodiment, components similar to those of the liquid dispensing device 1 of the first embodiment will be denoted by the same reference numerals, and their descriptions will be simplified or omitted. 【0145】 Figure 16 shows an example of the functional configuration of the power supply unit 5 of the liquid dispensing device 1 of the second embodiment. In the liquid dispensing device 1 of the first embodiment, the control unit 2 outputs output enable signals EN1 and EN2, and the power supply unit 5 controls the operation of the switching power supply circuit 50 according to the logic level of the output enable signal EN1 and the operation of the linear power supply circuit 55 according to the logic level of the output enable signal EN2, thereby switching whether to output the voltage signal Vsw output by the switching power supply circuit 50 as the power supply voltage signal VHV or the voltage signal Vln output by the linear power supply circuit 55 as the power supply voltage signal VHV. However, the liquid dispensing device 1 of the second embodiment differs in that the control unit 2 outputs an output enable signal EN, and the power supply unit 5 switches whether to output the voltage signal Vsw output by the switching power supply circuit 50 as the power supply voltage signal VHV or the voltage signal Vln output by the linear power supply circuit 55 as the power supply voltage signal VHV, according to the logic level of the output enable signal EN. 【0146】 As shown in Figure 16, the power supply unit 5 of the second embodiment has a power supply selection circuit 59a. The output enable signal EN output by the control unit 2 is input to the power supply selection circuit 59a. When the input output enable signal EN is at the H level, the power supply selection circuit 59a switches The switching power supply circuit 50 outputs an H-level output enable signal EN1a to its control circuit 51, and the linear power supply circuit 55 outputs an L-level output enable signal EN2a to its control circuit 56. At this time, the switching power supply circuit 50 outputs a voltage signal Vsw, and the linear power supply circuit 55 does not output a voltage signal Vln. Therefore, the power supply unit 5 outputs the voltage signal Vsw output by the switching power supply circuit 50 as the power supply voltage signal VHV. On the other hand, when the input output enable signal EN is at an L level, the power supply selection circuit 59a outputs an L-level output enable signal EN1a to the control circuit 51 of the switching power supply circuit 50, and an H-level output enable signal EN2a to the control circuit 56 of the linear power supply circuit 55. At this time, the switching power supply circuit 50 does not output a voltage signal Vsw, and the linear power supply circuit 55 outputs a voltage signal Vln. Therefore, the power supply unit 5 outputs the voltage signal Vln output by the linear power supply circuit 55 as the power supply voltage signal VHV. 【0147】 Even with the liquid dispensing device 1 of the second embodiment configured as described above, the same effects and advantages as the liquid dispensing device 1 of the first embodiment can be achieved. 【0148】 3. Third Embodiment Next, the liquid dispensing device 1 of the third embodiment will be described. In describing the liquid dispensing device 1 of the third embodiment, components similar to those of the liquid dispensing device 1 of the first and second embodiments will be denoted by the same reference numerals, and their descriptions will be simplified or omitted. 【0149】 Figure 17 shows an example of the functional configuration of the power supply unit 5 of the liquid dispensing device 1 of the third embodiment. The liquid dispensing device 1 of the third embodiment differs from the liquid dispensing device 1 of the first embodiment in that the control unit 2 outputs an output enable signal EN, and the power supply unit 5 has a power supply selection circuit 59b that switches whether or not to supply the power supply voltage signal VDC as power supply voltage signal VDC1 to the switching power supply circuit 50 and whether or not to supply the power supply voltage signal VDC as power supply voltage signal VDC2 to the linear power supply circuit 55, depending on the logic level of the output enable signal EN. 【0150】 As shown in Figure 17, the power supply unit 5 of the third embodiment has a power supply selection circuit 59b. The output enable signal EN output by the control unit 2 is input to the power supply selection circuit 59b. The power supply voltage signal VDC is also input to the power supply selection circuit 59b. When the input output enable signal EN is at the H level, the power supply selection circuit 59b supplies the power supply voltage signal VDC as power supply voltage signal VDC1 to the switching power supply circuit 50 and supplies the power supply voltage signal VDC2 at ground potential to the linear power supply circuit 55. At this time, the switching power supply circuit 50 outputs a voltage signal Vsw, and the linear power supply circuit 55 does not output a voltage signal Vln. Therefore, the power supply unit 5 outputs the voltage signal Vsw output by the switching power supply circuit 50 as the power supply voltage signal VHV. On the other hand, when the input output enable signal EN is at the L level, the power supply selection circuit 59b supplies the power supply voltage signal VDC1 at ground potential to the switching power supply circuit 50 and supplies the power supply voltage signal VDC as power supply voltage signal VDC2 to the linear power supply circuit 55. At this time, the switching power supply circuit 50 does not output the voltage signal Vsw, and the linear power supply circuit 55 outputs the voltage signal Vln. Therefore, the power supply unit 5 outputs the voltage signal Vln output by the linear power supply circuit 55 as the power supply voltage signal VHV. 【0151】 Even with the liquid dispensing device 1 of the third embodiment configured as described above, the same effects and advantages as the liquid dispensing device 1 of the first embodiment can be achieved. 【0152】 4. Fourth Embodiment Next, the liquid dispensing device 1 of the fourth embodiment will be described. In describing the liquid dispensing device 1 of the fourth embodiment, the liquid dispensing devices of the first embodiment, the second embodiment, and the third embodiment will be described. For configurations similar to those in 1, the same reference numerals are used, and their explanations are simplified or omitted. 【0153】 Figure 18 shows an example of the functional configuration of the power supply unit 5 of the liquid dispensing device 1 of the fourth embodiment. The liquid dispensing device 1 of the fourth embodiment differs from the liquid dispensing device 1 of the first embodiment in that the control unit 2 outputs an output enable signal EN, and the power supply unit 5 has a power supply selection circuit 59c that switches whether to output the voltage signal Vsw output by the switching power supply circuit 50 as the power supply voltage signal VHV, or the voltage signal Vln output by the linear power supply circuit 55 as the power supply voltage signal VHV, depending on the logic level of the output enable signal EN. 【0154】 As shown in Figure 18, the power supply unit 5 of the fourth embodiment has a power supply selection circuit 59c. The output enable signal EN output by the control unit 2 is input to the power supply selection circuit 59c. The power supply selection circuit 59c is also input to the voltage signal Vsw output by the switching power supply circuit 50 and the voltage signal Vln output by the linear power supply circuit 55. When the input output enable signal EN is at the H level, the power supply selection circuit 59c outputs the voltage signal Vsw output by the switching power supply circuit 50 as the power supply voltage signal VHV, and when the input output enable signal EN is at the L level, it outputs the voltage signal Vln output by the linear power supply circuit 55 as the power supply voltage signal VHV. 【0155】 Even with the liquid dispensing device 1 of the fourth embodiment configured as described above, the same effects and advantages as the liquid dispensing device 1 of the first embodiment can be achieved. 【0156】 5. Variations In this embodiment, the piezoelectric element PZ is described as being driven to eject ink from the ejection unit D and outputting a signal corresponding to the residual vibration generated in the ejection unit D. However, the ejection unit D may also include separately a piezoelectric element as a driving element for ejecting ink and a piezoelectric element as a detection element for detecting the residual vibration generated in the ejection unit D. Furthermore, in this case, the driving element for ejecting ink in the ejection unit D is not limited to a piezoelectric element as long as it is an element that can convert electrical signals into mechanical vibrations, and the detection element for detecting the residual vibration generated in the ejection unit D is not limited to a piezoelectric element as long as it is an element that can convert mechanical vibrations into electrical signals. 【0157】 Furthermore, although this embodiment has described the output of a signal corresponding to the residual vibration generated in the discharge unit D based on the potential generated at the upper electrode Zu of the piezoelectric element PZ, the output of a signal corresponding to the residual vibration generated in the discharge unit D based on the potential generated at the lower electrode Zd of the piezoelectric element PZ may also be used. 【0158】 Furthermore, the signal corresponding to the residual vibration generated in the discharge unit D may be a signal in which the current oscillates in response to the residual vibration generated in the discharge unit D, or it may be a signal in which the voltage oscillates in response to the residual vibration generated in the discharge unit D. Therefore, the detection circuit 33 may be configured to detect the voltage value of the signal corresponding to the residual vibration generated in the discharge unit D, or it may be configured to detect the current value of the signal corresponding to the residual vibration generated in the discharge unit D. 【0159】 Furthermore, although this embodiment has described that the signal waveform of the drive signal Com output by the drive signal output unit 4 can be switched between drive waveforms PP1, PP2, drive waveform PS, and drive waveform PC, the drive signal output unit 4 may also include, separately, an amplification circuit that outputs drive waveforms PP1 and PP2, an amplification circuit that outputs drive waveform PS, and an amplification circuit that outputs drive waveform PC. 【0160】 Although embodiments and modifications have been described above, the present invention is not limited to these embodiments and can be implemented in various forms without departing from its essence. For example, the above embodiments can be combined as appropriate. 【0161】 The present invention includes configurations that are substantially identical to those described in the embodiments (for example, configurations with the same function, method, and result, or configurations with the same purpose and effect). Furthermore, the present invention includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as those described in the embodiments. Furthermore, the present invention includes configurations that add known technology to the configurations described in the embodiments. 【0162】 The following conclusions can be drawn from the embodiments described above. 【0163】 One embodiment of a liquid dispensing device is: A dispensing section for dispensing liquid, A residual vibration detection circuit that acquires a residual vibration signal corresponding to the residual vibration generated in the discharge section and outputs a residual vibration detection signal corresponding to the residual vibration signal, A determination circuit that determines the state of the discharge unit in accordance with the residual vibration detection signal, A first switch circuit that switches whether or not to supply the residual vibration signal to the residual vibration detection circuit, A power supply circuit that receives a first power supply signal and outputs a second power supply signal to the first switch circuit, Equipped with, The aforementioned power supply circuit is A linear power supply circuit to which the first power supply signal is supplied and which outputs a first voltage signal, A switching power supply circuit to which the first power supply signal is supplied and which outputs a second voltage signal, Includes, The first voltage signal or the second voltage signal is output as the second power supply signal. 【0164】 In this liquid dispensing device, a power supply circuit that receives a first voltage signal and outputs a second power supply signal to a first switch circuit that switches whether or not to supply a residual vibration signal generated in the dispensing section to a residual vibration detection circuit includes a linear power supply circuit that receives a first power supply signal and outputs a first voltage signal, and a switching power supply circuit that receives a first power supply signal and outputs a second voltage signal. By outputting either the first voltage signal or the second voltage signal as the second power supply signal, the power supply circuit can output the first voltage signal, which is output by the linear power supply circuit and is less likely to have ripple voltage superimposed on it, as the second power supply signal to the first switch circuit during the period when the first switch circuit supplies the residual vibration signal to the residual vibration detection circuit. As a result, the risk of ripple voltage superimposed on the second power supply signal being superimposed on the residual vibration signal via the first switch circuit is reduced. Therefore, the accuracy of the residual vibration signal corresponding to the residual vibration generated in the dispensing section acquired by the residual vibration detection circuit is improved, and the accuracy of the residual vibration detection signal corresponding to the residual vibration signal output by the residual vibration detection circuit is improved. As a result, the judgment accuracy of the judgment circuit that determines the state of the discharge section in response to the residual vibration detection signal is improved. In other words, the accuracy of residual vibration detection is improved. 【0165】 In one embodiment of the liquid dispensing device, The first switch circuit includes a transistor element that switches whether or not to supply the residual vibration signal to the residual vibration detection circuit. The second power supply signal may be supplied to the back gate terminal of the transistor element. 【0166】 In this liquid dispensing device, because the accuracy of residual vibration detection is improved, the first switch circuit includes a transistor element that switches whether or not to supply a residual vibration signal to the residual vibration detection circuit, and in order to improve the stability of the operation of the first switch circuit, the second power supply signal is transmitted to the transistor Even when supplied to the back gate terminal of the element, the risk of superimposing on the residual vibration signal is reduced via the first switch circuit, improving the accuracy of residual vibration detection. 【0167】 In one embodiment of the liquid dispensing device, The first switch circuit may switch whether or not to supply the residual vibration signal to the residual vibration detection circuit based on a first selection signal corresponding to the second power supply signal. 【0168】 In this liquid dispensing device, because the accuracy of residual vibration detection is improved, even when the first switch circuit switches whether or not to supply the residual vibration signal to the residual vibration detection circuit based on a first selection signal corresponding to the second power supply signal, the risk of superimposition on the residual vibration signal via the first switch circuit is reduced, thus improving the accuracy of residual vibration detection. 【0169】 In one embodiment of the liquid dispensing device, During the first period in which the first switch circuit supplies the residual vibration signal to the residual vibration detection circuit, the power supply circuit may output the first voltage signal as the second power supply signal. 【0170】 In this liquid dispensing device, during the first period in which the first switch circuit supplies the residual vibration signal to the residual vibration detection circuit, the power supply circuit outputs a first voltage signal as a second power supply signal. This reduces the risk of superimposition on the residual vibration signal via the first switch circuit, thus improving the accuracy of residual vibration detection. 【0171】 In one embodiment of the liquid dispensing device, During the second period in which liquid is discharged from the discharge unit, the power supply circuit may output the second voltage signal as the second power supply signal. 【0172】 In this liquid dispensing device, during the second period in which liquid is dispensed from the dispensing section, the power supply circuit outputs a second voltage signal as a second power supply signal, thereby reducing the power consumption of the liquid dispensing device during the period when the first switch circuit does not supply a residual vibration signal to the residual vibration detection circuit. 【0173】 In one embodiment of the liquid dispensing device, The linear power supply circuit may include a series regulator circuit. 【0174】 This liquid dispensing device can reduce the power consumption of the linear power supply circuit. 【0175】 In one embodiment of the liquid dispensing device, The residual vibration detection circuit may include an AD conversion circuit and output the residual vibration detection signal as a digital signal. 【0176】 This liquid dispensing device offers even greater accuracy in detecting residual vibrations. 【0177】 In one embodiment of the liquid dispensing device, The discharge unit includes a piezoelectric element that is driven by a drive signal. The system includes a second switch circuit that switches whether or not to supply the drive signal to the piezoelectric element, The second switch circuit may switch whether or not to supply the drive signal to the piezoelectric element based on a second selection signal corresponding to the second power supply signal. 【0178】 In one embodiment of the liquid dispensing device, The residual vibration detection circuit is generated when the piezoelectric element is displaced in response to the residual vibration. The electromotive force may be obtained as the residual vibration signal. 【0179】 In one embodiment of the liquid dispensing device, The dispensing unit may dispense liquid by driving the piezoelectric element. [Explanation of symbols] 【0180】 1...Liquid dispensing device, 2...Control unit, 3...Head unit, 4...Drive signal output unit, 5...Power supply unit, 6...Determination unit, 7...Transport unit, 31...Supply switching circuit, 32...Recording head, 33...Detection circuit, 50...Switching power supply circuit, 51...Control circuit, 52...Switching circuit, 53...Smoothing circuit, 54...Feedback circuit, 55...Linear power supply circuit, 56...Control circuit, 57...Transistor, 58...Feedback circuit, 59a, 59b, 59c...Power supply selection circuit, 71...Carriage transport mechanism, 73...Media transport mechanism, 75...Platen, 76...Carriage guide shaft, 100...Housing, 110...Carriage, 120...Ink cartridge, 310...Connection status specification circuit, 321...Vibration Plate, 322...Cavity, 323...Nozzle plate, 324...Cavity plate, 325...Reservoir, 326...Ink supply port, 327...Ink intake, 330...Waveform shaping circuit, 331...AD conversion circuit, 521, 522...Transistors, 531...Inductor, 532...Capacitor, 541, 542, 581, 582...Resistors, C1...Capacitor, D...Ejector, N...Nozzle, NL...Nozzle row, OP1, OP2...Operational amplifier, P...Medium, PZ...Piezoelectric element, R1~R3, Rf...Resistors, W, W1, W2, Wc, Wf...Switches, Wiv...Inverter, Wnm, Wpm...Transistors, Ws...Switch, Zd...Lower electrode, Zm...Piezoelectric element, Zu...Upper electrode

Claims

[Claim 1] A dispensing section for dispensing liquid, A residual vibration detection circuit that acquires a residual vibration signal corresponding to the residual vibration generated in the discharge section and outputs a residual vibration detection signal corresponding to the residual vibration signal, A determination circuit that determines the state of the discharge unit in accordance with the residual vibration detection signal, A first switch circuit that switches whether or not to supply the residual vibration signal to the residual vibration detection circuit, A power supply circuit that receives a first power supply signal and outputs a second power supply signal to the first switch circuit, Equipped with, The aforementioned power supply circuit is A linear power supply circuit to which the first power supply signal is supplied and which outputs a first voltage signal, A switching power supply circuit to which the first power supply signal is supplied and which outputs a second voltage signal, Includes, The first voltage signal or the second voltage signal is output as the second power supply signal. A liquid dispensing device characterized by the following features. [Claim 2] The first switch circuit includes a transistor element that switches whether or not to supply the residual vibration signal to the residual vibration detection circuit. The second power supply signal is supplied to the back gate terminal of the transistor element. The liquid dispensing device according to feature 1. [Claim 3] The first switch circuit switches whether or not to supply the residual vibration signal to the residual vibration detection circuit based on a first selection signal corresponding to the second power supply signal. The liquid dispensing device according to feature 1. [Claim 4] During the first period in which the first switch circuit supplies the residual vibration signal to the residual vibration detection circuit, the power supply circuit outputs the first voltage signal as the second power supply signal. The liquid dispensing device according to feature 1. [Claim 5] During the second period in which liquid is discharged from the discharge unit, the power supply circuit outputs the second voltage signal as the second power supply signal. The liquid dispensing device according to feature 1. [Claim 6] The linear power supply circuit includes a series regulator circuit. The liquid dispensing device according to feature 1. [Claim 7] The residual vibration detection circuit includes an AD conversion circuit and outputs the residual vibration detection signal as a digital signal. The liquid dispensing device according to feature 1. [Claim 8] The discharge unit includes a piezoelectric element that is driven by a drive signal. The system includes a second switch circuit that switches whether or not to supply the drive signal to the piezoelectric element, The second switch circuit switches whether or not to supply the drive signal to the piezoelectric element based on a second selection signal corresponding to the second power supply signal. A liquid dispensing device according to any one of claims 1 to 7. [Claim 9] The residual vibration detection circuit acquires the electromotive force generated by the displacement of the piezoelectric element in response to the residual vibration as the residual vibration signal. The liquid dispensing device according to feature 8. [Claim 10] The discharge unit discharges liquid by driving the piezoelectric element. The liquid dispensing device according to feature 9.

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