Discharge state determination method and liquid discharge device

Abstract

To provide a discharge state determination method that can improve the detection speed of residual vibration. [Solution] The pre-charge step includes a timing step of acquiring the elapsed time since the previous pre-charge step was performed, a charging time determination step of determining a charging time for accumulating charge in the capacitive component of the residual vibration detection circuit according to the elapsed time, and a charging step of accumulating charge in the capacitive component of the residual vibration detection circuit according to the charging time. The discharge state determination step includes a determination drive step of supplying a drive waveform signal as a drive signal to a drive element, a residual vibration acquisition step of acquiring a residual vibration detection signal output by the residual vibration detection circuit after the determination drive step, and a discharge unit determination step of determining the state of the discharge unit based on the residual vibration detection signal acquired in the residual vibration acquisition step.

Description

Technical Field

[0001] The present invention relates to a discharge state determination method and a liquid discharge device.

Background Art

[0002] In a liquid discharge device that discharges liquid according 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.

[0003] For example, Patent Document 1 discloses a technique for improving the detection accuracy of residual vibration by charging a capacitance component generated in a wiring through which a signal corresponding to the residual vibration propagates before detecting the residual vibration.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, from the viewpoint of improving the detection speed of residual vibration, only the technique described in Patent Document 1 is not sufficient, and there is room for improvement.

Means for Solving the Problems

[0006] One aspect of the discharge state determination method according to the present invention is a plurality of discharge units that discharge liquid by being supplied with a drive signal, a residual vibration detection circuit that acquires any one of residual vibration signals corresponding to residual vibration that occurs after each drive element output by each of the plurality of discharge units is driven, and outputs a residual vibration detection signal corresponding to the acquired residual vibration signal, a determination circuit that determines the state of the discharge unit according to the residual vibration detection signal, A method for determining the discharge state in a liquid discharge device equipped with the following: A pre-charge step in which charge is stored in the capacitive component of the residual vibration detection circuit, A discharge state determination step, which determines the state of the discharge unit based on the residual vibration detection signal, Includes, The pre-charge step and the discharge state determination step are performed repeatedly. The aforementioned pre-charge process is A timing step to obtain the elapsed time since the previous pre-charge step was performed, A charging time determination step, which determines the charging time for accumulating charge in the capacitive component of the residual vibration detection circuit according to the elapsed time, A charging step in which charge is stored in the capacitive component of the residual vibration detection circuit according to the charging time, Includes, The aforementioned discharge state determination step is: A determination drive step in which a drive waveform signal is supplied to the drive element as the drive signal, After the determination drive step, a residual vibration acquisition step is performed to acquire the residual vibration detection signal output by the residual vibration detection circuit, A discharge unit determination step, which determines the state of the discharge unit based on the residual vibration detection signal obtained in the residual vibration acquisition step, Includes.

[0007] One embodiment of the liquid dispensing device according to the present invention is: Multiple dispensing units that dispense liquid when a drive signal is supplied, A residual vibration detection circuit acquires one of the residual vibration signals corresponding to the residual vibration generated after the drive element output by each of the plurality of discharge units is driven, and outputs a residual vibration detection signal corresponding to the acquired residual vibration signal. A determination circuit that determines the state of the discharge unit in accordance with the residual vibration detection signal, Equipped with, The charging time for accumulating charge in the capacitive component of the residual vibration detection circuit before the determination circuit determines the state of the discharge unit is determined according to the elapsed time since charge was previously accumulated in the capacitive component of the residual vibration detection circuit.

Brief Description of the Drawings

[0008] [Figure 1] It is a diagram showing an example of the functional configuration of a liquid ejection device. [Figure 2] It is a diagram showing an example of the schematic internal structure of a liquid ejection device. [Figure 3] It is a diagram showing the schematic structure of the ejection part. [Figure 4] It is a diagram showing an example of the arrangement of nozzles. [Figure 5] It is a diagram showing an example of the functional configuration of a head unit. [Figure 6] It is a diagram for explaining an example of various signals input to a connection state specifying circuit. [Figure 7] It is a diagram showing an example of the configuration of a waveform shaping circuit. [Figure 8] It is a diagram for explaining an example of various signals supplied to a head unit during the period when ejection processing is being executed. [Figure 9] It is a diagram showing an example of the relationship between an individual specification signal and a connection state specification signal during the period when ejection processing is being executed. [Figure 10] It is a diagram for explaining an example of various signals input to the supply circuit of a head unit during the period when state determination processing is being executed. [Figure 11] It is a diagram showing an example of the relationship between an individual specification signal and a connection state specification signal during the period when determination processing is being executed. [Figure 12] It is a diagram showing an example of the relationship between an individual specification signal and a connection state specification signal during the period when determination processing is being executed. [Figure 13] It is a diagram for explaining an example of the acquisition operation of a detection potential signal based on a signal corresponding to residual vibration generated in the ejection part to be inspected. [Figure 14] It is a diagram showing an example of the relationship between an individual specification signal and a connection state specification signal during the period when determination preparation processing is being executed. [Figure 15]This is a diagram for explaining an example of various signals input to the supply circuit of the head unit during the period when the correction value acquisition process is being executed. [Figure 16] This is a diagram for explaining an example of the operation of the liquid ejection device during the period when the acquisition process is being executed. [Figure 17] This is a diagram showing an example of a correction value acquisition method. [Figure 18] This is a diagram showing an example of a discharge determination method. [Figure 19] This is a diagram showing an example of a printing process. [Figure 20] This is a diagram showing an example of a state determination process.

Embodiments for Carrying Out the Invention

[0009] 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.

[0010] 1. Outline of the Liquid Ejection Device In the present embodiment, as the liquid ejection device 1, an inkjet printer that ejects 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. FIG. 1 is a diagram showing an example of the functional configuration of the liquid ejection device 1. Image data Img indicating an image to be formed on the medium by the liquid ejection device 1 is input to the liquid ejection device 1 from an external device such as a personal computer connected externally. Then, the liquid ejection device 1 executes a printing process for forming the image indicated by the input image data Img on the medium.

[0011] As shown in Figure 1, the liquid ejection device 1 comprises a control unit 2 for controlling each part of the liquid ejection device 1, a head unit 3 having a plurality of ejection units D for ejecting ink onto a medium, a drive signal output unit 4 that outputs a drive signal Com for driving the plurality of ejection units D, a transport unit 7 for changing the relative position of the medium with respect to the head unit 3, a determination unit 8 for determining the ink ejection state at the plurality of ejection units D, and a storage unit 9 that stores determination conditions and correction values ​​for the determination unit 8. In this embodiment, it is assumed that the liquid ejection device 1 comprises one or more head units 3, one or more drive signal output units 4 corresponding one-to-one with the one or more head units 3, and one or more determination units 8 corresponding one-to-one with the one or more head units 3. However, for the sake of explanation, in the following description, we will focus on one of the one or more head units 3, one drive signal output unit 4 provided in correspondence with the one head unit 3, and one determination unit 8 provided in correspondence with the one head unit 3, as shown in Figure 1.

[0012] The control unit 2 is configured to include one or more CPUs (Central Processing Units). The control unit 2 may also include a programmable logic device such as an FPGA (Field Programmable Gate Array) instead of, or in addition to, a CPU. The control unit 2 generates and outputs signals for controlling the operation of various parts of the liquid dispensing device 1, such as a clock signal CL, a print data signal SI, a latch signal LAT, a change signal CH, a period specification signal Tsig, and a drive waveform specification signal dCom.

[0013] Furthermore, the control unit 2 outputs a control signal to control the transport unit 7. This causes the transport unit 7 to change the relative position of the medium with respect to the head unit 3.

[0014] The drive waveform specification signal dCom output by the control unit 2 is input to the drive signal output unit 4. 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, and the drive signal Com is an analog signal for driving the output unit D, which will be described later. The drive signal output unit 4 includes a DA conversion circuit. The drive waveform specification signal dCom input to the drive signal output unit 4 is converted into an analog signal by the DA conversion circuit. The drive signal output unit 4 generates a drive signal Com, which is an amplified version of the signal waveform defined by the drive waveform specification signal dCom, by performing a Class D amplification of the analog signal converted by the DA conversion circuit, and outputs it to the head unit 3. Here, the drive signal output unit 4 may generate a drive signal Com, which is an amplified version of the signal waveform defined by the drive waveform specification signal dCom, by performing a Class B or Class AB amplification instead of Class D amplification, and output it to the head unit 3.

[0015] Furthermore, 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 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 for 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 specifies whether or not to supply a drive signal Com to each of the multiple ejector units D for each of the periods defined by the latch signal LAT, change signal CH, and period specification signal Tsig, thereby specifying the operation of the corresponding ejector unit D.

[0016] The head unit 3 comprises a supply circuit 31, a recording head 32, and a detection circuit 33. The recording head 32 also has M discharge units D. In the following description, when any m-th discharge unit D among the M discharge units D of the recording head 32 is specified and described, it may be referred to as discharge unit D[m]. That is, the recording head 32 has discharge units D[1] to D[M] as M discharge units D. Here, M is a natural number satisfying "M≧1" and m is a natural number satisfying "1≦m≦M". In the following description, when indicating that a component of the liquid dispensing device 1 or a signal etc. corresponds to discharge unit D[m] among the M discharge units D, the subscript [m] may be added to the symbol representing that component or signal etc.

[0017] The clock signal CL, print data signal SI, latch signal LAT, change signal CH, and period specification signal Tsig, along with the drive signal Com, are input to the supply 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 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. The supply drive signal Vin is then supplied to the piezoelectric element PZ, which will be described later, located in the ejection unit D, thereby driving the piezoelectric element PZ. An amount of ink corresponding to the amount of drive of this piezoelectric element PZ is ejected from the ejection unit D.

[0018] Furthermore, the supply circuit 31 switches whether or not to supply a signal corresponding to the residual vibration generated in the ejection unit D as a detection potential signal VX to the detection circuit 33 at each of the timings defined by the latch signal LAT, the change signal CH, and the period specification signal Tsig, based on the print data signal SI.

[0019] The detection circuit 33 generates a detection signal SK based on the detection potential signal VX supplied via the supply 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 8. Based on the input detection signal SK, the determination unit 8 determines whether the ink ejection state at the ejection unit D is normal, and whether it is a normal ejection state in which no ejection abnormality has occurred at the ejection unit D. Specifically, the determination unit 8 reads predetermined determination threshold information and correction value information stored in the storage unit 9, which includes non-volatile memory such as ROM (Read Only Memory) or flash memory. Here, the determination threshold information is a threshold for determining whether it is a normal ejection state in which no ejection abnormality has occurred at the ejection unit D, and the correction value information is correction value information for correcting the detection signal SK. The determination unit 8 corrects the input detection signal SK according to the read correction value information, and compares the corrected signal with the determination threshold information read from the storage unit 9 to determine whether an ejection abnormality has occurred at the ejection unit D, that is, whether the ejection unit D is in a normal ejection state. The determination unit 8 then generates ejection state determination information JH indicating the determination result and outputs it to the control unit 2. In the following explanation, determining whether or not a discharge abnormality has occurred in the discharge unit D, and determining whether or not the discharge unit D is in a normal discharge state, may be simply referred to as determining the state of the discharge unit D.

[0021] Here, "discharge abnormality" refers to a state in which the ink discharge condition at the discharge unit D is abnormal, and is a general term for a state in which ink cannot be accurately discharged from the discharge unit D. Examples of such discharge abnormalities include a state in which ink cannot be discharged from the discharge unit D, a state in which the discharge unit D discharges an amount of ink different from the amount of ink discharged as defined by the drive signal Com, and a state in which the discharge unit D discharges ink at a speed different from the ink discharge speed defined by the drive signal Com.

[0022] As described above, when printing is being performed, the control unit 2 generates signals to control the head unit 3, such as a print data signal SI, based on the image data Img, and outputs them to the head unit 3. It also generates signals to control the drive signal output unit 4, such as a drive waveform specification signal dCom, and outputs them to the drive signal output unit 4. At the same time, the control unit 2 generates and outputs signals to control the transport unit 7. As a result, the control unit 2 controls the transport unit 7 to change the relative position of the medium with respect to the head unit 3, while adjusting the presence or absence of ink ejection from the ejection unit D, the amount of ink ejected, and the timing of ink ejection. This forms an image on the medium corresponding to the image data Img.

[0023] Furthermore, when printing is being performed, the control unit 2 generates a signal to control the head unit 3, such as a print data signal SI that determines the state of the ejection unit D, and outputs it to the head unit 3. It also generates a signal to control the drive signal output unit 4, such as a drive waveform specification signal dCom, and outputs it to the drive signal output unit 4. As a result, the detection circuit 33 outputs a detection signal SK based on the detection potential signal VX supplied via the supply circuit 31 to the determination unit 8. Based on the input detection signal SK, the determination unit 8 determines whether the ink ejection state in the ejection unit D is normal and whether it is a normal ejection state in which no ejection abnormality has occurred in the ejection unit D. The determination unit 8 then outputs ejection state determination information JH to the control unit 2 according to the determination result of the state of the ejection unit D. As a result, the control unit 2 can correct the output signal according to the state of the ejection unit D, improving the quality of the image formed on the medium.

[0024] As described above, in the liquid dispensing device 1 of this embodiment, the printing process for forming an image corresponding to the image data Img includes a dispensing process for dispensing ink onto a medium and a state determination process for determining the state of the dispensing unit D that dispenses ink onto the medium.

[0025] In the liquid dispensing device 1, the control unit 2, the determination unit 8, and the memory unit 9 are a common circuit and may be configured to be mounted on a common semiconductor device, for example. In this case, part or all of the drive signal output unit 4 and the transport unit 7 may also be included in the semiconductor device.

[0026] Next, the general structure of the liquid ejection device 1 will be described. Figure 2 is a diagram showing an example of the general 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. Specifically, when the liquid ejection device 1 performs a printing 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 M ejection units D of the head unit 3, thereby forming dots on the medium P corresponding to the image data Img. Note that the liquid ejection device 1 is not limited to a serial inkjet printer but may also be a line-type inkjet printer. Furthermore, the liquid ejection device 1 is not limited to an inkjet printer but may also be a colorant ejection device used in the manufacture of color filters for liquid crystal displays, an electrode material ejection device used in the formation of electrodes for organic EL displays and FEDs (surface-emitting displays), a bio-organic material ejection device used in the manufacture of biochips, a three-dimensional molding device, and a textile printing device, etc.

[0027] In the following explanation, we will use mutually orthogonal X, Y, and Z axes. Furthermore, in the following explanation, the starting point of an arrow indicating direction along the X axis will be referred to as the -X side and the tip as the +X side; the starting point of an arrow indicating direction along the Y axis will be referred to as the -Y side and the tip as the +Y side; and the starting point of an arrow indicating direction along the Z axis 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 along the X-axis and a main scanning direction along the Y-axis, and the medium P is transported along the X-axis with the -X side being the upstream side and the +X side being 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 units D, which receive ink from the corresponding ink cartridge 120. As a result, the inside of the 4M ejection units D of each of the four head units 3 is filled with ink supplied from the corresponding ink cartridge 120. Then, each of the 4M ejection units D of each of the four head units 3 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, thereby changing the relative position of the media P with respect to the head unit 3. This enables ink to be deposited 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 section 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 filled with ink supplied from the corresponding ink cartridge 120.

[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 circuit 31. The lower electrode Zd is supplied with a reference voltage signal Vbs propagating through the wiring Lb. The piezoelectric body Zm is located between the upper electrode Zu and the lower electrode Zd The piezoelectric element PZ is displaced along the Z-axis to the +Z side or the -Z side, depending on 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 displace along the Z-axis to the +Z side or the -Z side, depending on 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 is a signal with a constant potential 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 response to 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.

[0035] 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.

[0036] Figure 4 shows an example of the arrangement of a total of 4M discharge units D provided on four head units 3 and 4M nozzles N provided on each of the 4M discharge units D. As shown in Figure 4, the four head units 3 are positioned side by side along the Y-axis on the carriage 110. In this arrangement, the M discharge units D and nozzles N of each of the four head units 3 are positioned side by side along the X-axis.

[0037] Specifically, the M ejection sections D[1] to D[M] of the head unit 3 are arranged in the order of ejection section D[1], ejection section D[2], ejection section D[3], ..., ejection section 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 by the M nozzles N, each of the M ejection sections D, being arranged in parallel along the X-axis from the -X side to the +X side. Therefore, the carriage 110 has four rows of nozzle rows NL, each containing one of the four head units 3, arranged along the Y-axis. Ink is then ejected from each of the nozzles N that form the nozzle row NL contained in each of the four head units 3.

[0038] 2. Head Unit Configuration Next, the functional configuration of the head unit 3 will be described. Figure 5 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 circuit 31, a recording head 32, and a detection circuit 33. Figure 5 also shows 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.

[0039] The supply circuit 31 includes switches Wc[1]~Wc[M], switches Ws[1]~Ws[M], switch Wf, resistor Rf, and a connection state specification circuit 310. Switches Wc[1]~Wc[M] and Ws[1]~Ws[M] correspond one-to-one with the discharge sections D[1]~D[M] in the supply circuit 31.

[0040] The clock signal CL, print data signal SI, latch signal LAT, change signal CH, and period specification signal Tsig input to the head unit 3 are input to the connection state specification circuit 310. The connection state specification circuit 310 specifies the connection state of switches Wc[1] to Wc[M] according to the print data signal SI propagated based on the clock signal CL during the period defined by the input latch signal LAT, change signal CH, and period specification signal Tsig. The following signals are generated: connection status specification signals Qc[1]~Qc[M], connection status specification signals Qs[1]~Qs[M] which specify the connection status of switches Ws[1]~Ws[M], and connection status specification signal Qf which specifies the connection status of switch Wf. These signals are then output to the corresponding switches Wc[1]~Wc[M], Ws[1]~Ws[M], and Wf.

[0041] Such a connection state designation circuit 310 includes registers that hold print data signals SI propagated based on a clock signal CL in correspondence with the output units D[1] to D[M], and a decoder that decodes the print data signals SI held in the registers to output connection state designation signals Qc[1] to Qc[M], Qs[1] to Qs[M], Qf, etc., at predetermined logic levels.

[0042] 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]. When a high-level connection state designation signal Qc[m] is input to the control terminal of switch Wc[m], the connection between one end and the other becomes conductive, and when a low-level connection state designation signal Qc[m] is input to the control terminal, the connection between one end and the other becomes non-conductive. 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 unit D[m], in accordance with the connection state specification signal Qc[m]. Such a switch Wc[m] is composed of, for example, a transmission gate.

[0043] 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]. When a high-level connection state designation signal Qs[m] is input to the control terminal of switch Ws[m], the connection between one end and the other becomes conductive, and when a low-level connection state designation signal Qs[m] is input to the control terminal, the connection between one end and the other becomes non-conductive. In other words, 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 state specification signal Qs[m]. Such a switch Ws[m] is composed of, for example, a transmission gate.

[0044] 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. When a high-level connection state specification signal Qf is input to the control terminal of switch Wf, the connection between the one end and the other becomes conductive, and when a low-level connection state specification signal Qf is input to the control terminal, the connection between the one end and the other becomes non-conductive. 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. Such a switch Wf is composed of, for example, a transmission gate.

[0045] Furthermore, 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 defined by the input latch signal LAT, change signal CH, and period specification signal Tsig, and the detection circuit 3 Output to 3.

[0046] Here, an example of various signals input to the connection state specification circuit 310 will be described. Figure 6 is a diagram illustrating an example of various signals input to the connection state specification circuit 310. As shown in Figure 6, 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.

[0047] 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.

[0048] 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 briefly setting the logic level of the change signal CH to a high level at a predetermined time after 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.

[0049] 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 high level after a predetermined time has elapsed from the rising edge of the pulse PLL, and then setting the logic level of the period specification signal Tsig to low 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 high level after a predetermined time has elapsed, and then setting the logic level of the period specification signal Tsig to low 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 (from the rising edge of the pulse PLL to the rising edge of pulse PLT1), TT2 (from the rising edge of pulse PLT1 to the falling edge of pulse PLT1), TT3 (from the falling edge of pulse PLT1 to the rising edge of pulse PLT2), TT4 (from the rising edge of pulse PLT2 to the falling edge of pulse PLT2), and TT5 (from the falling edge of pulse PLT2 to the rising edge of the pulse PLL). Note that the number of divisions of the unit period TP by the period specification signal Tsig is not limited to five.

[0050] Furthermore, the control unit 2 generates a print data signal SI that includes the individual designation signals Sd[1] to Sd[M] in serial format and outputs it to the connection status designation circuit 310. Individual designation signal Sd[1] ~Sd[M] are signals each containing 3 bits of information, defining the respective driving modes of the output units D[1]~D[M]. In the following explanation, the 3 bits of information contained in the individual designation signal Sd[m] are referred to as bits S1, S2, and S3, and the individual designation signal Sd[m] = [S1, S2, S3] may be used. Also, in the following explanation, if bits S1, S2, and S3 contained in the individual designation signal Sd[m] can be either "1" or "0", then "*" may be used to represent this.

[0051] 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.

[0052] 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.

[0053] Returning to Figure 5, 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.

[0054] Here, an example of the configuration of the waveform shaping circuit 330 included in the detection circuit 33 will be described. Figure 7 is a diagram showing an example of the configuration of the waveform shaping circuit 330. As shown in Figure 7, the waveform shaping circuit 330 includes a capacitor C1, operational amplifiers OP1 and OP2, switches W1 and W2, and resistors R1 to R3.

[0055] A detection potential signal VX output by the supply 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. An analog ground AG fixed at a constant potential is supplied to the other end of resistor R1 and the other end of switch W1. That is, resistor R1 and switch W1 are connected in parallel. A connection status specification signal Q1 is input to the control terminal of switch W1. When a high-level connection status specification signal Q1 is input to the control terminal of switch W1, the two ends conduct, and when a low-level connection status specification signal Q1 is input to the control terminal, the two ends conduct. The connection between the end and the switch 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 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, and outputting it. Here, switch W1 may be configured as, for example, a transmission gate. Also, analog ground AG may 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.

[0056] The positive input terminal of op-amp 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 op-amp OP1. The negative input terminal of op-amp 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 op-amp 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, op-amp OP1 and resistors R2 and R3 function as a non-inverting amplifier circuit that amplifies the signal input to the positive input terminal of op-amp OP1 according to the resistance values ​​of resistors R2 and R3 and outputs it from the output terminal of op-amp 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.

[0057] 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.

[0058] 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 a 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, the two ends become conductive. When a low-level connection status specification signal Q2 is input to the control end of switch W2, the two ends become non-conductive. Switch W2 switches whether or not to output the signal output by operational amplifier OP2 as a detection signal aSK from the waveform shaping circuit 330, depending on the logic level of the connection status specification signal Q2 input to the control end of switch W2.

[0059] 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.

[0060] 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 output as a detection signal SK from the detection circuit 33 and the head unit 3.

[0061] In the head unit 3 of this embodiment, configured as described above, the supply 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].

[0062] Furthermore, in this embodiment, the head unit 3 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, change signal CH, and period specification signal Tsig. This allows the head unit 3 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. The detected signal SK output by the detection circuit 33 is input to the determination unit 8. The determination unit 8 then determines the state of the target ejection section D[m] based on the input detected signal SK.

[0063] Here, the supply 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 circuit 31 on the semiconductor device.

[0064] 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, a plurality of dispensing units D that dispensing ink in accordance with the driving of the piezoelectric element PZ and outputting a signal corresponding to the residual vibration that occurs after the piezoelectric element PZ is driven, a detection circuit 33 that acquires one of the signals corresponding to the residual vibration that occurs after the piezoelectric element PZ is driven output by each of the plurality of dispensing 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 the residual vibration that occurs after the piezoelectric element PZ is driven to the detection circuit 33, a storage unit 9 that stores correction value information for the detection signal SK, and a determination unit 8 that determines the state of the dispensing unit in accordance with the detection signal SK and the correction value information.

[0065] 3. Operation of the liquid ejection device and head unit during the printing process. The operation of the liquid ejection device 1 equipped with the head unit 3 configured as described above will now be explained. As previously stated, the printing process in which the liquid ejection device 1 of this embodiment forms an image corresponding to the image data Img includes an ejection process that forms dots at desired positions on the medium P by ejecting ink onto the medium P, and a state determination process that determines the state of the ejection unit D that ejects ink onto the medium P. In the following, when explaining the operation of the liquid ejection device 1 during the period in which the printing process is being executed, the operation of the liquid ejection device 1 in the ejection process and the state determination process will be explained separately.

[0066] 3.1 Discharge Process Figure 8 is a diagram illustrating an example of various signals supplied to the head unit 3 during the period in which the ejection process is being performed.

[0067] During the period in which the discharge process is being performed, the control unit 2 controls the drive signal output unit 4 A drive waveform specification signal dCom, which defines the signal waveform of the drive signal Com output by the unit, is generated and output to the drive signal output unit 4. As a result, the drive signal output unit 4 generates a drive signal Com with a continuous signal waveform, as shown in Figure 8, consisting of a drive waveform PP1 placed in the control period TQ1 and a drive waveform PP2 placed in the control period TQ2, in accordance with the input drive waveform specification signal dCom, and supplies it to the head unit 3.

[0068] 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].

[0069] 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].

[0070] In this embodiment, the liquid dispensing device 1 achieves multi-gradation dot formation on the medium P by either forming a large dot, a medium dot smaller than the large dot, or a small dot smaller than the medium dot on the medium P for each unit period TP during the dispensing process, or by not recording any dots. That is, the dispensing unit D[m] can select whether to dispensing an amount of ink equivalent to a large dot, an amount equivalent to a medium dot, or an amount equivalent to a small dot, or not dispensing any ink, for each unit period TP during the dispensing process.

[0071] In this embodiment, the liquid dispensing device 1 is described as follows: when the drive waveform PP1 is supplied to the piezoelectric element PZ[m], the amount of ink ξ1 dispensed from the dispensing unit D[m] corresponds to the amount of ink equivalent to the medium dot described above; when the drive waveform PP2 is supplied to the piezoelectric element PZ[m], the amount of ink ξ2 dispensed from the dispensing unit D[m] is less than the amount of ink ξ1 and corresponds to the amount of ink equivalent to the small dot described above; and the sum of the amounts of ink ξ1 and ξ2 corresponds to the amount of ink equivalent to the large dot described above.

[0072] 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 determines whether, during a unit period TP in which the liquid dispensing device 1 is performing the dispensing process, 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 is dispensed from the dispensing section D[m], and as a result, the dot size formed on the medium P is controlled.

[0073] 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.

[0074] Figure 9 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.

[0075] As shown in Figure 9, 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 high level during control period TQ1 and high 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 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 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.

[0076] 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 high level during control period TQ1 and low 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 conduct during control period TQ1 and to non-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] holds 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 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 with 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.

[0077] 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 low level during control period TQ1 and high 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] holds the 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, the piezoelectric element PZ[m] receives the drive waveform PP During control period TQ1, when the supply drive signal Vin[m] containing 1 is not supplied, a constant signal at 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 ink amount ξ2 is ejected during control period TQ2. Then, the ink amount ξ2 ejected during control period TQ2 lands on the medium P, forming small dots on the medium P during unit period TP.

[0078] 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 low level during control period TQ1 and low 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.

[0079] 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 can form an image on the medium P corresponding to the image data Img during the period in which the dispensing process is being performed.

[0080] Here, as shown in Figure 9, during the period when the liquid dispensing device 1 is performing the dispensing process, the connection state designation circuit 310 continues to output a low-level connection state designation signal Qs[m] 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, a signal corresponding to 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. Therefore, 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 low-level connection state designation signals Qf, Q1, and Q2.

[0081] 3.2 State determination process Next, we will explain the state determination process for determining the state of the ejection unit D, which ejects ink onto the medium P during the printing process. It is known that residual vibration occurs in the ejection unit, which 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 of the damped vibration, such as the amplitude, amplitude damping rate, period, and frequency, changes depending on the state of the discharge section. For example, if the viscosity of the liquid stored in the discharge section changes, the amplitude and amplitude damping rate of the residual vibration generated in the discharge section will change. Also, for example, if air bubbles are mixed into the inside of the discharge section, the frequency of the residual vibration generated in the discharge section will increase.

[0082] In the liquid dispensing device 1 of this embodiment, in the state determination process for determining the state of the dispensing unit D that dispenses ink onto the medium P, the supply 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 8 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. The determination unit 8 then generates dispensing state determination information JH indicating the determination result and outputs it to the control unit 2. As a result, the control unit 2 can acquire the state of the dispensing unit D[m] to be inspected, correct the various signals to be output according to the acquired state of the dispensing unit D[m] to be inspected, or inform the user of the state of the dispensing unit D[m] to be inspected.

[0083] Figure 10 is a diagram illustrating an example of various signals input to the supply circuit 31 of the head unit 3 during the period in which the state determination process is being executed.

[0084] During the period in which the state determination process is being executed, 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, and outputs it to the drive signal output unit 4. As a result, 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 10, according to the input drive waveform specification signal dCom, and supplies it to the head unit 3.

[0085] 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, residual vibration occurs in the ejection section D[m] at the timing when the voltage value of the drive signal Com becomes 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.

[0086] During the period when the liquid dispensing device 1 performs state determination processing, the connection state specification circuit 310 controls the conduction state of switches Wc[1]~Wc[M], Ws[1]~Ws[M], Wf, W1, and W2 in each of the control periods TT1 to TT5 based on the individual specification signals Sd[1]~Sd[M] included in the print data signal SI. 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 8 determines the state of the dispensing unit D[m] under inspection based on the detection signal SK.

[0087] Here, the state determination process in the liquid dispensing device 1 of this embodiment includes a determination process that acquires a detection potential signal VX based on a signal corresponding to residual vibration occurring in the dispensing section D[m] to be inspected, and determines the state of the dispensing section D[m] to be inspected based on the acquired detection potential signal VX, and a determination preparation process to improve the accuracy of the determination of the state of the dispensing section D[m] to be inspected in the determination process.

[0088] First, 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 dispensing 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. Figure 11 shows an example of the relationship between the individual designation signal Sd[m] and the connection status designation signals Qc[m], Qs[m] during the period when the determination process is being executed. Hereinafter, in the liquid dispensing device 1 of this embodiment, the control unit 2 outputs an individual designation signal Sd[m]=[1,0,0] to the connection status designation circuit 310 during the determination process if the dispensing unit D[m] is not the object of inspection, and outputs an individual designation signal Sd[m]=[1,0,1] to the connection status designation circuit 310 if the dispensing unit D[m] is the object of inspection.

[0089] As shown in Figure 11, 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 generates a connection state designation signal Qc[m] that is low level during the control period TT1 to TT5 and outputs it to the control terminal of switch Wc[m], and generates a connection state designation signal Qs[m] that is low level during the control period TT1 to TT5 and outputs it to the control terminal of switch Ws[m]. As a result, switch Wc[m] is controlled to be non-conductive during the control period TT1 to TT5, and switch Ws[m] is controlled to be non-conductive during the control period TT1 to TT5. At this time, the piezoelectric element PZ[m] of the discharge section D[m] that is not the subject of inspection 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. 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 this change in potential is not supplied to the wiring Ls. Consequently, the state of the discharge section D[m] is not determined.

[0090] Furthermore, when the individual designation signal Sd[m]=[1,0,1] is input to the connection state designation circuit 310, the connection state designation circuit 310 generates a connection state designation signal Qc[m] which is high level during control periods TT1, TT2, and TT5 and 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 designation signal Qs[m] which is high level during control periods TT2 to TT4 and 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 non-conductive during control periods TT3 and TT4, and switch Ws[m] is controlled to conduct during control periods TT2 to TT4 and to non-conductive during control periods TT1 and TT5.

[0091] Figure 12 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 12, 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,*].

[0092] As shown in Figure 12, 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 high level during control periods TT2 to TT4 and 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 high level during control periods TT1, TT2, TT4, and TT5 and 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 high level during control period TT3 and 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.

[0093] 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 13 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.

[0094] As shown in Figure 13, for each unit period TP during the period in which the state determination process is being executed, the connection 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 in 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 in the control periods TT2 to TT4, and ends at the reference potential V0 in the control period TT5.

[0095] During the period in which the state determination 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.

[0096] 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. 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, in response to the residual vibration generated in the discharge section D[m] under inspection, the piezoelectric element Zm[m] deforms, 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.

[0097] 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.

[0098] 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 8 as a detection signal SK.

[0099] The determination unit 8 calculates waveform information such as amplitude, period, and frequency of the detected potential signal VX, which is the waveform information of the residual vibration generated in the discharge section D[m] under inspection, based on the input detection signal SK. Then, the determination unit 8 determines the state of the discharge section D[m] under inspection based on the calculated waveform information and outputs discharge state determination information JH indicating the determination result to the control unit 2.

[0100] 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.

[0101] Here, as shown in Figure 5, during the period when switches Ws[1]~Ws[M] are controlled to be non-conductive and switch Wf is controlled to be non-conductive, the voltage value of wiring Ls is ideally kept constant at potential VS2, which is the potential of the signal propagating through wiring Ls immediately before switches Ws[1]~Ws[M] and Wf are controlled to be non-conductive, and is the voltage value of the drive signal Com when acquiring a signal corresponding to the residual signal. However, even during the period when switches Ws[1]~Ws[M] are controlled to be non-conductive and switch Wf is controlled to be non-conductive, the voltage value of wiring Ls may change due to the influence of leakage current flowing into or out of wiring Ls. Therefore, during periods when the dispensing process is being performed, when switches Ws[1] to Ws[M] are controlled to be non-conductive and switch Wf is controlled to be non-conductive, a potential difference may occur between the upper electrode Zu[m] of the piezoelectric element PZ[m] included in the dispensing section D[m] under inspection and the wiring Ls.

[0102] Then, when a potential difference is generated between the upper electrode Zu[m] of the piezoelectric element PZ[m] included in the discharge section D[m] under inspection and the wiring Ls, and the switch Ws[m] is controlled to conduct, a signal corresponding to the residual vibration generated in the discharge section D[m] under inspection is superimposed with a signal corresponding to the said potential difference, and this signal propagates through the wiring Ls as the detected potential signal VX. At this time, the amplitude of the signal corresponding to the residual vibration generated in the discharge section D[m] under inspection is about several tens of mV. Consequently, the amplitude of the signal generated by the potential difference between the upper electrode Zu[m] of the piezoelectric element PZ[m] included in the discharge section D[m] under inspection and the wiring Ls can reach several volts. When such a signal is superimposed on a signal corresponding to residual vibrations occurring in the discharge section D[m] under inspection, the signal accuracy of the detected potential signal VX propagating through the wiring Ls is significantly reduced. As a result, the accuracy of calculating waveform information such as amplitude, period, and frequency of residual vibrations occurring in the discharge section D[m] under inspection is significantly reduced, and the accuracy of determining the state of the discharge section D[m] under inspection by the judgment unit 8 is significantly reduced.

[0103] In contrast, the liquid dispensing device 1 of this embodiment performs a judgment preparation process immediately before the judgment process is executed to control the voltage value of the wiring Ls to a potential VS2, which is the intermediate potential of the signal corresponding to the residual vibration generated in the dispensing section D[m] under inspection, and is the voltage value of the drive signal Com when residual vibration occurs in the dispensing section D[m] under inspection. This makes it possible to reduce the potential difference between the upper electrode Zu[m] of the piezoelectric element PZ[m] included in the dispensing section D[m] under inspection and the wiring Ls when the judgment process is executed, thereby improving the accuracy of the detected potential signal VX propagating through the wiring Ls, and improving the accuracy of the calculation of waveform information such as amplitude, period, and frequency of the residual vibration generated in the dispensing section D[m] under inspection by the judgment unit 8. As a result, the accuracy of the judgment of the state of the dispensing section D[m] under inspection is improved in the judgment process.

[0104] During the period in which this judgment preparation process is being executed, 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 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 will be explained, and an example of the decoding content of the individual designation signals Sd[1]~Sd[M] executed by the connection status designation circuit 310 during the period in which the judgment preparation process is being executed will be described. Here, the drive signal Com input to the connection status designation circuit 310 during the period in which the judgment preparation process is being executed is the same as the drive signal Com input to the connection status designation circuit 310 during the period in which the judgment process is being executed, so its explanation will be omitted.

[0105] Figure 14 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 when the judgment preparation process is being executed. As shown in Figure 14, during the period when the judgment preparation process is being executed, the connection status designation circuit 310 receives the individual designation signal Sd[1]~Sd[M]=[1,1,1]. At this time, the connection status designation circuit 310 outputs connection status designation signals Qc[1]~Qc[M], Qs[1]~Qs[M], Q1, and Q2, which are low levels during the control period TT1~TT5, and a connection status designation signal Qf, which is low levels during the control period TT1 and TT5, and high levels during the control period TT2~TT4. As a result, switches Wc[1]~Wc[M], Ws[1]~Ws[M], W1, and W2 are controlled to be non-conductive during control periods TT1~TT5, and switch Wf is controlled to be non-conductive during control periods TT1 and TT5, and conductive during control periods TT2~TT4. In other words, during control periods TT2~TT4 within the period in which the judgment preparation process is being executed, wiring Ls and wiring Lc are electrically connected via resistor Rf.

[0106] As described above, during the period in which the judgment preparation process is being executed, the drive signal output unit 4 outputs a drive signal Com with a constant voltage value of potential VS2 during the control period TT2 to TT4. Therefore, during the control period TT2 to TT4 within the period in which the judgment preparation process is being executed, the switch Wf is controlled to conduct, and a signal with a constant voltage value of potential VS2 is supplied to the wiring Ls via the resistor Rf. As a result, during the period in which the judgment preparation process is being executed, the voltage value of the wiring Ls is controlled to be potential VS2. Consequently, during the period in which the judgment process is being executed after the judgment preparation process has been executed, the upper electrode Zu[m] of the piezoelectric element PZ[m] included in the discharge section D[m] to be inspected and the wiring Ls The potential difference can be reduced. As a result, the accuracy of the detected potential signal VX propagating through the wiring Ls is improved during the period in which the judgment process is being performed, and the accuracy of the judgment of the state of the discharge section D[m] of the object to be inspected in the judgment unit 8 is improved.

[0107] Here, when controlling the voltage value of wiring Ls to be constant at potential VS2, the time required for this control is determined by the parasitic capacitance of wiring Ls and the resistance value of resistor Rf, and can be up to several hundred μs. In contrast, the time from control period TT2 to control period TT4 within the period in which the state determination process is executed is only about several tens of μs, and if the determination preparation process is performed only once, it may not be possible to control the voltage value of wiring Ls to be constant at potential VS2. Therefore, in the liquid dispensing device 1 of this embodiment, the determination preparation process is repeatedly executed multiple times immediately before the determination process is executed within the period in which the state determination process is executed. This ensures sufficient time to control the voltage value of wiring Ls to be constant at potential VS2, and the voltage value of wiring Ls during the period in which the determination process is executed can be controlled to potential VS2.

[0108] 4. Correction value acquisition process As described above, in the liquid dispensing device 1 of this embodiment, by performing a judgment preparation process immediately before executing the judgment process, it is possible to reduce the potential difference between the upper electrode Zu[m] of the piezoelectric element PZ[m] included in the dispensing section D[m] to be inspected and the wiring Ls during the period in which the judgment process is performed. This improves the accuracy of the detection potential signal VX acquired by the detection circuit 33 during the period in which the judgment process is performed, and improves the accuracy of the judgment unit 8 in determining the state of the dispensing section D[m] to be inspected.

[0109] On the other hand, leakage current flows into or out of the wiring Ls even during the period in which the judgment process is being executed. Therefore, even during the control periods TT1, TT5, etc., in which switches Ws[1] to Ws[M] are controlled to be non-conductive and switch Wf is controlled to be non-conductive, the voltage value of the wiring Ls changes slightly due to the leakage current. In the liquid dispensing device 1 of this embodiment, correction value information corresponding to the change in the voltage value generated in the wiring Ls due to the leakage current is stored in the storage unit 9, and the judgment unit 8 corrects the detection signal SK using this correction value information, thereby contributing to the change in the voltage value of the wiring Ls that occurs during the period in which the judgment process is being executed, and reducing the risk of a decrease in the judgment accuracy of the state of the dispensing section D[m] to be inspected in the judgment unit 8.

[0110] Here, we will describe the correction value acquisition process, which acquires correction value information stored in the memory unit 9 and used by the determination unit 8 to correct the detection signal SK. In this correction value acquisition process, the supply circuit 31 receives the same signal as in the state determination process described above, except that the signal waveform of the drive signal Com is different. That is, the supply circuit 31 performs the same operation in the correction value acquisition process as in the state determination process described above. Therefore, the correction value acquisition process includes an acquisition process corresponding to the determination process described above, and an acquisition preparation process corresponding to the determination preparation process described above, which is executed immediately before the acquisition process.

[0111] Figure 15 is a diagram illustrating an example of various signals input to the supply circuit 31 of the head unit 3 during the period in which the correction value acquisition process is being executed.

[0112] During the period in which the correction value acquisition process is being executed, 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, and outputs it to the drive signal output unit 4. As a result, the drive signal output unit 4 generates a drive signal Com including the drive waveform PC for each unit period TP as shown in Figure 15, according to the input drive waveform specification signal dCom, and supplies it to the head unit 3.

[0113] The drive waveform PC is a signal waveform in which the voltage value starts at the reference potential V0 during the control period TT1, becomes a potential VC that is higher than the reference potential V0, maintains the potential VC during the control periods TT2, TT3, and TT4, and ends at the reference potential V0 during the control period TT5. The amount of change in voltage value per short time during the control period TT1 is smaller compared to the drive waveforms PP1, PP2, and PS. In other words, the amount of change in voltage value per unit time of the drive waveform PC is smaller than the amount of change in voltage value per unit time of the drive waveform PS. When the drive waveform PC is supplied to the piezoelectric element PZ[m] of the ejection unit D[m], the piezoelectric element PZ[m] is driven so that ink is not ejected from the nozzle N[m] of the ejection unit D[m] and no residual start occurs in the ejection unit D[m]. In other words, the drive waveform PC is a signal waveform that drives the piezoelectric element PZ[m] so that ink is not ejected from the nozzle N[m] of the ejection unit D[m], and does not generate residual vibration in the ejection unit D[m]. When the drive waveform PC is supplied, the piezoelectric element PZ[m] is driven so that no residual vibration occurs in the ejection unit D[m].

[0114] First, let's explain the acquisition preparation process within the correction value acquisition process. The acquisition preparation process is a process for controlling the voltage value of the wiring Ls during the period in which the acquisition process is executed to the potential VC, which is the voltage value of the drive signal Com during the control period TT2 to TT4 within the period in which the correction value acquisition process is executed. During the period in which this acquisition preparation process is executed, the supply circuit 31 is input with the same clock signal CL, print data signal SI, latch signal LAT, change signal CH, and period specification signal Tsig as during the period in which the judgment preparation process described above is executed.

[0115] In other words, during the period when the acquisition preparation process is being executed, the connection state specification circuit 310 of the supply circuit 31 is input a print data signal SI that includes the individual specification signals Sd[1]~Sd[M]=[1,1,1]. As a result, the connection state specification circuit 310 outputs connection state specification signals Qc[1]~Qc[M], Qs[1]~Qs[M], Q1, Q2, which are low level during the control period TT1~TT5 as shown in Figure 14, and a connection state specification signal Qf, which is low level during the control periods TT1 and TT5 and high level during the control periods TT2~TT4. Therefore, switches Wc[1]~Wc[M], Ws[1]~Ws[M], W1, W2 are controlled to be non-conductive during the control period TT1~TT5, and switch Wf is controlled to be non-conductive during the control periods TT1 and TT5 and conductive during the control period TT2~TT4. As a result, during the control period TT2 to TT4 within the period in which the acquisition preparation process is being executed, wiring Ls and wiring Lc are electrically connected via resistor Rf.

[0116] As shown in Figure 15, during the period in which the acquisition preparation process is being executed, the drive signal output unit 4 outputs a drive signal Com whose voltage value is constant at potential VC during the control period TT2 to TT4. Therefore, during the control period TT2 to TT4 within the period in which the acquisition preparation process is being executed, the switch Wf is controlled to conduct, and a signal with a voltage value constant at potential VC is supplied to the wiring Ls via the resistor Rf. As a result, during the period in which the acquisition preparation process is being executed, the voltage value of the wiring Ls is controlled to be at potential VC. At this time, the acquisition preparation process may be executed repeatedly multiple times within the period in which the correction value acquisition process is being executed, immediately before the acquisition process is executed, similar to the judgment preparation process described above. This makes it possible to secure sufficient time to control the voltage value of the wiring Ls to be constant at potential VC, and the voltage value of the wiring Ls during the period in which the acquisition process is being executed can be controlled to be at potential VC.

[0117] Next, the acquisition process within the correction value acquisition process will be explained. The acquisition process is executed following the acquisition preparation process described above, and is the process of acquiring correction value information that is stored in the storage unit 9 and used by the determination unit 8 to correct the detection signal SK. During the period in which this acquisition process is being executed, the supply circuit 31 receives the same clock signal CL, print data signal SI, latch signal LAT, change signal CH, and during the period in which the determination process described above is being executed. A time period specification signal Tsig is input.

[0118] During the period when the liquid dispensing device 1 performs the acquisition process, the connection state designation circuit 310 of the supply circuit 31 receives a print data signal SI which includes an individual designation signal Sd[m]=[1,0,1] corresponding to any dispensing section D[m] and individual designation signals Sd[1]~Sd[m-1],[m+1]~[M]=[1,0,0] corresponding to dispensing sections D[1]~D[m-1],[m+1]~[M] other than dispensing section D[m].

[0119] The connection state designation circuit 310 generates connection state designation signals Qc[1]~Qc[m-1],Qc[m+1]~Qc[M] which are low level during the control period TT1~TT5, based on the input individual designation signals Sd[1]~Sd[m-1],[m+1]~[M]=[1,0,0] and the decoded content shown in Figure 11, and outputs them to the control terminals of the corresponding switches Wc[1]~Wc[m-1],Wc[m+1]~Wc[M]. It also generates connection state designation signals Qs[1]~Qs[m-1],Qs[m+1]~Qs[M] which are low level during the control period TT1~TT5, and outputs them to the control terminals of the corresponding switches Ws[1]~Ws[m-1],Ws[m+1]~Ws[M]. As a result, switches Wc[1]~Wc[m-1] and Wc[m+1]~Wc[M] are controlled to be non-conductive during the control period TT1~TT5, and switches Ws[1]~Ws[m-1] and Ws[m+1]~Ws[M] are controlled to be non-conductive during the control period TT1~TT5.

[0120] Furthermore, the connection state designation circuit 310 generates a connection state designation signal Qc[m] that is high level during control periods TT1, TT2, and TT5 and low level during control periods TT3 and TT4, based on the input individual designation signal Sd[m]=[1,0,1] and the decoded content shown in Figure 11, and outputs it to the control terminal of switch Wc[m]. It also generates a connection state designation signal Qs[m] that is high level during control periods TT2 to TT4 and 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 non-conductive during control periods TT3 and TT4, and switch Ws[m] is controlled to conduct during control periods TT2 to TT4 and to non-conductive during control periods TT1 and TT5.

[0121] Furthermore, the connection state designation circuit 310 generates a connection state designation signal Qf, which is high level during control periods TT2 to TT4 and low level during control periods TT1 and TT5, based on the input individual designation signals Sd[1] to Sd[M] = [1, 0, *] and the decoded content shown in Figure 12, and outputs it to the control terminal of switch Wf; generates a connection state designation signal Q1, which is high level during control periods TT1, TT2, TT4, and TT5 and low level during control period TT3, and outputs it to the control terminal of switch W1; and generates a connection state designation signal Q2, which is high level during control period TT3 and 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.

[0122] Here, we will explain the operation of the liquid dispensing device 1 during the period in which the acquisition process is being performed. Figure 16 is a diagram illustrating an example of the operation of the liquid dispensing device 1 during the period in which the acquisition process is being performed. As shown in Figure 16, for each unit period TP during the period in which the acquisition process is being performed, the voltage value in the connection state designation circuit 310 starts at the reference potential V0 in the control period TT1, becomes a potential VC that is higher than the reference potential V0, maintains the potential VC in the control periods TT2, TT3, and TT4, and ends at the reference potential V0 in the control period TT5. A drive signal Com, including the drive waveform PC, is supplied.

[0123] Furthermore, during the period in which the acquisition process is performed, the control unit 2 outputs a print data signal SI that includes the individual designation signal Sd[m]=[1,0,1] and the individual designation signals Sd[1]~Sd[m-1],[m+1]~[M]=[1,0,0]. When the print data signal SI, which includes 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, the switch Wc[m] is controlled to conduct and the switches Wc[1]~Wc[m-1],Wc[m+1]~Wc[M] are controlled to not conduct during the control periods TT1 and TT2. Therefore, during control periods TT1 and TT2, the upper electrode Zu[m] is supplied with a supply drive signal Vin[m] that starts at the reference potential V0, becomes a potential VC higher than the reference potential V0, and maintains the potential VC. The upper electrodes Zu[1]~Zu[m-1] and Zu[m+1]~Zu[M] are continuously supplied with the reference potential V0. At this time, no residual vibration occurs in the discharge section D[m] to which the supply drive signal Vin[m] is supplied, and also no residual vibration occurs in the discharge sections D[1]~D[m-1] and D[m+1]~D[M] because the supply drive signals Vin[1]~Vin[m-1] and Vin[m+1]~Vin[M] are not supplied.

[0124] Then, during the control period TT2, switches Ws[m] and Wf are controlled to conduct. At this time, switches Ws[1] to Ws[m-1] and Ws[m+1] to Ws[M] remain non-conductive. When switch Ws[m] is controlled to conduct, if the voltage value of wiring Ls changes due to leakage current flowing into or out of wiring Ls, a signal is propagated in wiring Ls as a detected potential signal VX, in which a differential pulse PLd corresponding to the potential difference between the voltage value of wiring Ls and the potential of the upper electrode Zu[m] is superimposed on the potential VC, which is the potential of the upper electrode Zu[m]. At this time, switch W1 is controlled to conduct, and switch W2 is controlled to 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 in wiring Ls, and does not output a detection signal aSK corresponding to the detected potential signal VX.

[0125] Then, during the control period TT3, switch W1 is controlled to be non-conductive and switch W2 is controlled to be conductive, causing the waveform shaping circuit 330 of the detection circuit 33 to acquire the detection potential signal VX propagating through the wiring Ls, shape the signal waveform of the acquired detection potential signal VX, and output it as the 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 output to the judgment unit 8 as the detection signal SK. The judgment unit 8 then stores the input detection signal SK as correction value information in the storage unit 9. In other words, the judgment unit 8 stores the signal corresponding to the differential pulse PLd as correction value information in the storage unit 9. In other words, the memory unit 9 stores the detection signal SK output by the detection circuit 33 as correction value information, which includes the signal output from the discharge section D after the drive waveform PC is supplied to the piezoelectric element PZ[m] as a supply drive signal Vin[m] based on the drive signal Com, and corresponds to the detection potential signal VX propagating through the wiring Ls.

[0126] 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.

[0127] Here, the differential pulse PLd, which forms the basis of the correction value information stored in the memory unit 9, is a signal corresponding to the potential difference that occurs between the voltage value of the wiring Ls and the potential of the upper electrode Zu[m] when switch Ws[m] is controlled to conduct during the period in which the acquisition process is performed. It is a signal corresponding to the voltage value of the wiring Ls that changes due to leakage current flowing into or out of the wiring Ls during the period in which the acquisition process is performed when switches Ws[1]~Ws[M] and switch Wf are controlled to be non-conductive.

[0128] Furthermore, even in the judgment process that is executed after the judgment preparation process, the voltage value of the wiring Ls changes due to leakage current flowing into or out of the wiring Ls during the period when switches Ws[1] to Ws[M] and switch Wf are controlled to be non-conductive. Therefore, in the judgment process, the detection potential signal VX propagating through the wiring Ls includes a signal corresponding to the residual vibration generated in the discharge section D[m] of the object being inspected, and a signal corresponding to the potential difference between the voltage value of the wiring Ls and the potential of the upper electrode Zu[m] immediately before switch Ws[m] is controlled to be conductive.

[0129] As described above, the only difference between the correction value acquisition process and the state determination process is the signal waveform of the drive signal Com; the same signal is input to the supply circuit 31 of the head unit 3. Therefore, in the unit period TP during which the correction value acquisition process is being executed, the lengths of the control periods TT1 to TT5 defined by the latch signal LAT and the period specification signal Tsig are approximately equal to the lengths of the control periods TT1 to TT5 defined by the latch signal LAT and the period specification signal Tsig in the unit period TP during which the state determination process is being executed. Consequently, in the unit period TP during which the correction value acquisition process is being executed, the length of the period during which switches Ws[1] to Ws[M] and switch Wf are controlled to be non-conductive is approximately equal to the length of the period during which switches Ws[1] to Ws[M] and switch Wf are controlled to be non-conductive. Therefore, the amount of leakage current flowing into or out of wiring Ls is approximately equal during the period when the correction value acquisition process is being executed and during the period when the state determination process is being executed. Thus, the amount of change in the voltage value of wiring Ls is approximately equal during the period when the correction value acquisition process is being executed and during the period when the state determination process is being executed.

[0130] Therefore, during the period in which the correction value acquisition process is performed, the differential pulse PLd propagating through the wiring Ls is approximately equal to the signal generated during the period in which the determination process is performed, in accordance with the potential difference between the voltage value of the wiring Ls immediately before the switch Ws[m] included in the detected potential signal VX propagating through the wiring Ls is controlled to conduct, and the potential of the upper electrode Zu[m].

[0131] In the liquid dispensing device 1 of this embodiment, in the correction value acquisition process, a signal corresponding to the differential pulse PLd as described above is stored in the storage unit 9 as correction value information, and in the state determination process, the determination unit 8 corrects the detection signal SK using the correction value information of the signal corresponding to the differential pulse PLd stored in the storage unit 9, thereby further improving the determination accuracy of the state of the dispensing section D[m] in the determination unit 8.

[0132] In other words, in the liquid dispensing device 1 of this embodiment, the determination unit 8 determines the state of the dispensing unit D[m] based on a signal obtained by correcting the detection signal SK output by the detection circuit 33 in accordance with the detection potential signal VX propagating through the wiring Ls using correction value information stored in the storage unit 9. This reduces the influence of leakage current flowing into or out of the wiring Ls during the period in which the determination process is performed, and as a result, the determination accuracy of the state of the dispensing unit D[m] in the determination unit 8 can be further improved.

[0133] 5. Method for determining the discharge state in a liquid dispensing device The method for determining the discharge state in the liquid dispensing device 1 configured as described above will now be explained. The method for determining the discharge state in the liquid dispensing device 1 of this embodiment includes a correction value acquisition method in which the determination unit 8 acquires correction value information used to correct the input detection signal SK and stores it in the storage unit 9, and a discharge determination method that determines the state of the discharge unit D during the period in which an image corresponding to the image data Img is formed on the medium. The correction value acquisition method may be performed as part of the discharge determination method, or it may be performed as a process independent of the discharge determination method in the manufacturing process of the liquid dispensing device 1, etc.

[0134] 5.1 Method for obtaining correction values Figure 17 shows an example of a method for acquiring a correction value. As shown in Figure 17, when the correction value acquisition method is started, the control unit 2 sets the charge count Pcc1 to "0" as an initial setting (step S10). After the initial setting is completed, the acquisition preparation process, including the acquisition preparation process described above, is executed (step S20).

[0135] As shown in Figure 17, in the acquisition preparation step, the drive signal output unit 4 outputs a drive signal Com including the drive waveform PC (step S21). Specifically, in the acquisition preparation step, the control unit 2 generates a drive waveform specification signal dCom corresponding to the drive waveform PC and outputs it to the drive signal output unit 4. The drive signal output unit 4 amplifies the signal waveform defined by the input drive waveform specification signal dCom and outputs a drive signal Com including the drive waveform PC. Here, as described above, the drive waveform PC is a signal waveform that drives the piezoelectric element PZ[m] so that ink is not ejected from the ejection unit D[m] and residual vibration does not occur when it is input to the ejection unit D[m].

[0136] Furthermore, during the acquisition preparation process, the control unit 2 generates a print data signal SI to control switch Wf to conduction during the control period TT2 to TT4, in which the voltage value of the drive signal Com output by the drive signal output unit 4 and the voltage value of the drive waveform PC are constant at potential VC, and outputs this to the connection state specification circuit 310. As a result, the connection state specification circuit 310 controls switch Wf to conduction during the control period TT2 to TT4. Consequently, during the control period TT2 to TT4, wiring Ls and wiring Lc on which the drive signal Com propagates are electrically connected, and potential VC is supplied to wiring Ls (step S22).

[0137] Subsequently, the control unit 2 adds "1" to the charge count Pcc1 (step S23) and determines whether the added charge count Pcc1 is equal to or greater than the charge limit count Pcl1 (step S24). If the control unit 2 determines that the charge count Pcc1 is not equal to or greater than the charge limit count Pcl1 (N in step S24), the processes described in steps S21 to S23 are executed again. In other words, in the acquisition preparation process, the processes in steps S21 to S23 are repeatedly executed the number of times specified by the charge limit count Pcl1. On the other hand, if the control unit 2 determines that the charge count Pcc1 is equal to or greater than the charge limit count Pcl1 (N in step S24), the acquisition preparation process ends.

[0138] Here, the charge limit count Pcl1 is determined according to the time required for the voltage value of the wiring Ls to become potential VC by the process of supplying potential VC to the wiring Ls shown in step S22. For example, if the maximum time required for the voltage value of the wiring Ls to become potential VC is 400 μs, and the time from control period TT2 to control period TT4 in the acquisition preparation process is 40 μs, then the charge limit count Pcl1 is set to "10". This allows the voltage value of the wiring Ls to become potential VC in the acquisition preparation process. Note that the charge limit count Pcl1 may be a fixed value pre-stored by the manufacturer during the manufacturing stage of the liquid dispensing device 1, or it may be a value that can be appropriately changed during the specification stage of the liquid dispensing device 1 according to the user's requirements or the operating status of the liquid dispensing device 1.

[0139] After the acquisition preparation process is completed, the acquisition process, which includes the acquisition process described above, is executed (step S30). That is, the acquisition process, which acquires the correction value information and stores it in the storage unit 9, is executed after the acquisition preparation process, which stores charge in the capacitive component of the detection circuit 33, which includes the wiring Ls.

[0140] In the acquisition process, the drive signal output unit 4 outputs a drive signal Com including the drive waveform PC (step S31). Specifically, in the acquisition process, the control unit 2 outputs a drive waveform specification signal dCom corresponding to the drive waveform PC to the drive signal output unit 4, and the drive signal output unit 4 outputs a drive signal Com including the drive waveform PC by amplifying the signal waveform defined by the input drive waveform specification signal dCom.

[0141] Furthermore, during the acquisition process, the control unit 2 generates a print data signal SI to control the switch Ws[m] to conduction during the control period TT2 to TT4, in which the voltage value of the drive waveform PC, which is the voltage value of the drive signal Com output by the drive signal output unit 4, is constant at the potential VC, and outputs this to the connection state specification circuit 310. As a result, the switch Ws[m] is controlled to conduction during the control period TT2 to TT4 (step S32). Therefore, the upper electrode Zu[m] of the piezoelectric element PZ[m] and the wiring Ls are electrically connected, and a detection potential signal VX corresponding to the potential of the upper electrode Zu[m] of the piezoelectric element PZ[m] propagates through the wiring Ls.

[0142] At this time, the detection potential signal VX propagating through the wiring Ls is a signal in which a differential pulse PLd corresponding to the potential difference that occurs between the upper electrode Zu[m] of the piezoelectric element PZ[m] and the wiring Ls just before the switch Ws[m] is controlled to conduct is superimposed on the potential VC, which is the voltage value of the upper electrode Zu[m] of the piezoelectric element PZ[m] during the control period TT2. Subsequently, in the control period TT3, in accordance with the print data signal SI output by the control unit 2, the switch W1 is controlled to be non-conductive and the switch W2 is controlled to conduct. As a result, the detection circuit 33 acquires the detection potential signal VX, which is the potential VC superimposed with the differential pulse PLd (step S33). The detection circuit 33 then generates a detection signal SK corresponding to the acquired detection potential signal VX and outputs it to the determination unit 8.

[0143] The determination unit 8 stores the detection signal SK corresponding to the input detection potential signal VX as correction value information in the storage unit 9. That is, the determination unit 8 holds the detection signal SK corresponding to the detection potential signal VX as correction value information (step S34). Once the correction value information is stored in the storage unit 9, the acquisition process is completed, and the correction value acquisition method is finished.

[0144] As described above, the acquisition step included in the correction value acquisition method is a step of acquiring correction value information to correct the detection signal SK, and includes step S31 of supplying the drive waveform PC to the piezoelectric element PZ[m] as a supply drive signal Vin[m] based on the drive signal Com; step S32 of switching the switch Ws[m] after step S31 so that a signal corresponding to the residual vibration generated in the discharge section D[m] propagates through the wiring Ls and is supplied to the detection circuit 33 as a detection potential signal VX; and step S34 of holding the detection signal SK corresponding to the detection potential signal VX output by the detection circuit 33 as correction value information after step S32 (CL1,CL13_9913).

[0145] 5.2 Printing Method Figure 18 shows an example of a discharge determination method. As shown in Figure 18, the discharge determination process starts when power voltage is supplied to the various components of the liquid discharge device 1 (step S100). Here, the start of supplying power voltage to the various components of the liquid discharge device 1 is not limited to the start of supplying commercial power voltage to the liquid discharge device 1, but also includes a power supply circuit (not shown) that, when commercial power voltage is supplied to the liquid discharge device 1, determines the power supply corresponding to the various components of the liquid discharge device 1 based on the commercial power supply. This includes generating a pressure-value power supply voltage and starting to supply the generated power supply voltage to the various components of the liquid discharge device 1.

[0146] Then, after the supply of power voltage to the various components of the liquid dispensing device 1 begins, the control unit 2 sets the elapsed time information Et to a fixed value Etm as an initial setting (step S110). Here, the fixed value Etm is a value greater than the charge limit number Pcl2, which will be described later, and is, for example, the maximum value of the elapsed time that can be measured in the liquid dispensing device 1, which will be described later. After the above initial setting is completed, the liquid dispensing device 1 moves to the state determination step (step S120). The state determination step is a step that includes the state determination process described above, and is a step that determines the state of the dispensing unit D that dispenses ink onto the medium P. Details of the state determination step will be described later.

[0147] Then, when the state determination process in step S120 is completed, the control unit 2 determines whether or not image data Img has been input to the liquid dispensing device 1 (step S130). If the control unit 2 determines that image data Img has not been input to the liquid dispensing device 1 (N in step S130), the control unit 2 waits until image data Img is input to the liquid dispensing device 1. If image data Img is not input for a certain period of time, the control unit 2 may stop supplying power voltage to the various components of the liquid dispensing device 1 and terminate this dispensing determination method.

[0148] On the other hand, if the control unit 2 determines that image data Img has been input to the liquid dispensing device 1 (Y in step S130), the liquid dispensing device 1 proceeds to a printing process that includes the printing process described above and forms an image corresponding to the image data Img on the medium P (step S140).

[0149] Figure 19 shows an example of the printing process. As shown in Figure 19, in the printing process, the control unit 2 executes an ejection process including the ejection process described above (step S200). In the ejection process, the drive signal output unit 4 outputs a drive signal Com including drive waveforms PP1 and PP2 (step S201). Specifically, in the ejection process, the control unit 2 outputs a drive waveform specification signal dCom corresponding to the drive waveforms PP1 and PP2 to the drive signal output unit 4, and the drive signal output unit 4 outputs a drive signal Com including drive waveforms PP1 and PP2 by amplifying the signal waveform defined by the input drive waveform specification signal dCom.

[0150] Furthermore, during the ejection process, the control unit 2 generates print data signals SI to control the conduction state of switches Wc[1] to Wc[M] corresponding to each of the ejection units D[1] to D[M] during each of the control periods TQ1 and TQ2, and outputs them to the connection state specification circuit 310. This controls the conduction state of switches Wc[1] to Wc[M] during each of the control periods TQ1 and TQ2, and controls the signal waveforms of the supply drive signals Vin[1] to Vin[M] supplied to each of the ejection units D[1] to D[M] during each of the control periods TQ1 and TQ2. Consequently, the amount of ink ejected from each of the ejection units D[1] to D[M] is defined during each of the control periods TQ1 and TQ2, and the dot size formed on the medium P for each unit period TP is defined by the ink ejected from each of the ejection units D[1] to D[M]. In other words, dots corresponding to the print data signal SI are formed on the medium P (step S202). This completes the ejection process.

[0151] Subsequently, the control unit 2 determines whether a request has been made to perform a state determination process to determine the state of the discharge unit D[m] (step S210). If the control unit 2 determines that a request has been made to perform a state determination process (Y in step S210), the liquid discharge device 1 proceeds to a state determination process including the state determination process described above (step S220), and determines the state of the discharge unit D that discharges ink onto the medium P. Details of the state determination process will be described later.

[0152] Here, the request to perform the state determination process in step S210 may occur, for example, when the medium P on which the image is formed reaches between pages, or between ejection paths that eject ink onto the medium P. It may also occur at the request of the user. That is, the state determination process, including the state determination process, may be performed between pages of the medium P on which the ink ejected from the multiple ejection units D lands, or between ejection paths. Here, between ejection paths, for example, the timing when the direction of movement of the carriage 110 changes.

[0153] If the control unit 2 determines that there is no request to perform a state determination process (N in step S210), or after the state determination process in step S220 is completed, the control unit 2 determines whether the process of forming the image corresponding to the image data Img on the medium P has been completed. That is, the control unit 2 determines whether the ejection process corresponding to the image data Img has been completed (step S230). If the control unit 2 determines that the ejection process corresponding to the image data Img has not been completed (N in step S230), the control unit 2 executes the ejection process, including the ejection process in step S200, again. That is, the ejection process and the state determination process are executed repeatedly. On the other hand, if the control unit 2 determines that the ejection process corresponding to the image data Img has been completed (Y in step S230), the printing process is terminated, and the operation of the liquid ejection device 1 returns to the state before transitioning to the printing process.

[0154] Next, the state determination process that follows from steps S120 and S220 will be described. Figure 20 is a diagram showing an example of the state determination process. As shown in Figure 20, in the state determination process, the control unit 2 sets the charge count Pcc2 to "0" as an initial setting (step S300). After the initial setting is completed, the determination preparation process, which includes the determination preparation process described above, is executed (step S310).

[0155] In the judgment preparation step, the control unit 2 acquires elapsed time information Et (step S311). The elapsed time information Et corresponds to the elapsed time since the judgment preparation step was previously executed. Here, if the system first proceeds to the state determination step after the power supply voltage is supplied to the various components of the liquid discharge device 1, that is, if the system proceeds to the state determination step in step S120, the elapsed time count has not started, and therefore the information of the elapsed time information Et is undefined. In this embodiment, if the system first proceeds to the state determination step after the power supply voltage is supplied to the various components of the liquid discharge device 1, and the system proceeds to the state determination step in step S120, then in step S110, the elapsed time information Et is set to a fixed value Etm. That is, in step S310, which follows step S120, the fixed value Etm is acquired as the elapsed time information Et.

[0156] After acquiring the elapsed time information Et, the control unit 2 determines whether the acquired elapsed time information Et is greater than a predetermined time threshold Tth (step S312). Then, if the elapsed time information Et is greater than the predetermined time threshold Tth (Y in step S312), the control unit 2 sets the charge limit count Pcl2 to "n1" (step S313). If the elapsed time information Et is not greater than the predetermined time threshold Tth (N in step S312), the control unit 2 sets the charge limit count Pcl2 to "n2", which is smaller than the aforementioned "n1" (step S313). In other words, the charge limit count Pcl2 set when the elapsed time information Et is less than the time threshold Tth is smaller than the charge limit count Pcl2 set when the elapsed time information Et is greater than the time threshold Tth.

[0157] Subsequently, the drive signal output unit 4 outputs a drive signal Com including the drive waveform PS (step S315). Specifically, the control unit 2 generates a drive waveform specification signal dCom corresponding to the drive waveform PS and outputs it to the drive signal output unit 4, and the drive signal output unit 4 amplifies the signal waveform defined by the input drive waveform specification signal dCom to drive A drive signal Com, including waveform PS, is output. Here, as described above, the drive waveform PC is a signal waveform that drives the piezoelectric element PZ[m] so that when input to the ejection unit D[m], ink is not ejected from the ejection unit D[m] and a predetermined residual vibration occurs.

[0158] Furthermore, the control unit 2 generates a print data signal SI for controlling switch Wf to conduction during the control period TT2 to TT4, when the voltage value of the drive signal Com output by the drive signal output unit 4 and the voltage value of the drive waveform PS are constant at potential VS2, and outputs this to the connection state specification circuit 310. As a result, the connection state specification circuit 310 controls switch Wf to conduction during the control period TT2 to TT4. Consequently, during the control period TT2 to TT4, wiring Ls and wiring Lc on which the drive signal Com propagates are electrically connected, and potential VS2 is supplied to wiring Ls (step S316).

[0159] Subsequently, the control unit 2 adds "1" to the charge count Pcc2 (step S317) and determines whether the added charge count Pcc2 is equal to or greater than the charge limit count Pcl2 (step S318). If the control unit 2 determines that the charge count Pcc2 is not equal to or greater than the charge limit count Pcl2 (N in step S318), the processes described in steps S315 to S317 are executed again. In other words, in the determination preparation step, the processes in steps S315 to S317 are repeatedly executed a number of times specified by the charge limit count Pcl2.

[0160] On the other hand, if the control unit 2 determines that the number of charges Pcc2 is equal to or greater than the number of charges Pcl2 (N in step S318), the control unit 2 initializes the elapsed time information Et to "0", then starts counting the elapsed time information Et (step S319), and ends the determination preparation process.

[0161] Here, the number of times the process in steps S315 to S317 is repeated, and the charge limit count Pcl2 which defines the number of times the potential VS2 is supplied to the wiring Ls, is defined according to the time required for the voltage value of the wiring Ls to become the potential VS2 by the process of supplying the potential VS2 to the wiring Ls shown in step S316. For example, if the maximum time required for the voltage value of the wiring Ls to become the potential VS2 is 400 μs, and the time from the control period TT2 to TT4 for supplying the potential VS2 to the wiring Ls is 40 μs, then "n1" which is set as the charge limit count Pcl2 is set to "10", and "n2" which is set as the charge limit count Pcl2 is set to a value smaller than "10".

[0162] On the other hand, the time required for the voltage value of wiring Ls to reach potential VS2 is also influenced by the voltage value of wiring Ls immediately before the process of supplying potential VS2 to wiring Ls begins, and immediately before the judgment preparation process is executed. Specifically, the voltage value of wiring Ls changes due to the leakage current that occurs in wiring Ls. Therefore, the amount of change in the voltage value of wiring Ls increases as the elapsed time since the previous judgment preparation process was executed increases. When the amount of change in the voltage value of wiring Ls is large, the time required for the voltage value of wiring Ls to reach potential VS2 increases, and when the amount of change in the voltage value of wiring Ls is small, the time required for the voltage value of wiring Ls to reach potential VS2 decreases.

[0163] In the liquid dispensing device 1 of this embodiment, when the elapsed time information Et is greater than the time threshold Tth, that is, when a long time has elapsed since the previous determination preparation step was performed and the change in the voltage value of the wiring Ls is large, the charge limit count Pcl2 is set to "n1". When the elapsed time information Et is less than the time threshold Tth, that is, when a short time has elapsed since the previous determination preparation step was performed and the change in the voltage value of the wiring Ls is small, the charge limit count Pcl2 is set to "n2", which is smaller than the aforementioned "n1". The time required to control the voltage value of the wiring Ls to potential VS2 is set to control the time required for the wiring Ls to It can be controlled according to the pressure value. This makes it possible to shorten the time required to control the voltage value of the wiring Ls to the potential VS2, and thus shorten the time required for the state determination process.

[0164] In other words, in this embodiment, the determination preparation step for storing charge in the capacitive component of the detection circuit 33 including the wiring Ls includes: step S311 of acquiring elapsed time information Et corresponding to the elapsed time since the previous determination preparation step was performed; steps S312, S313, S314 of determining the charging time for storing charge in the capacitive component of the detection circuit 33 including the wiring Ls according to the acquired elapsed time information Et; and step S316 of storing charge in the capacitive component of the detection circuit 33 including the wiring Ls by supplying a potential VS2 to the wiring Ls according to the determined charging time. In other words, the charging time for storing charge in the capacitive component of the detection circuit 33 including the wiring Ls is determined according to the elapsed time since charge was previously stored in the capacitive component of the detection circuit 33 including the wiring Ls.

[0165] In this case, the charging time when the elapsed time since the previous determination preparation step was executed is shorter than a predetermined time threshold Tth is shorter than the charging time when the elapsed time since the previous determination preparation step was executed is longer than a predetermined time threshold Tth. Therefore, the number of times the process of step S316, in which charge is stored in the capacitive component of the detection circuit 33 including the wiring Ls by supplying a potential VS2 to the wiring Ls when the elapsed time since the previous determination preparation step was executed is shorter than a predetermined time threshold Tth is set to be less than the number of times the process of step S316, in which charge is stored in the capacitive component of the detection circuit 33 including the wiring Ls by supplying a potential VS2 to the wiring Ls when the elapsed time since the previous determination preparation step was executed is longer than a predetermined time threshold Tth is executed.

[0166] This reduces the time required for the judgment preparation process and thus the time required for the state determination process.

[0167] Furthermore, in this embodiment, the charging time determined in steps S312, S313, and S314 of the determination preparation process, which is the first execution after the power supply voltage is started, and the number of times the process of step S316, in which charge is stored in the capacitive component of the detection circuit 33 including the wiring Ls, is executed, is a constant value in step S110, regardless of the elapsed time since the previous determination preparation process was executed, because the elapsed time information Et is set to a fixed value Etm, and is specifically determined to be "n1".

[0168] During periods when the power supply voltage is interrupted, the amount of leakage current generated in the wiring Ls increases. As a result, the amount of change in the voltage value of the wiring Ls increases, and in particular, when the supply circuit 31 is composed of one or more semiconductor devices, the amount of leakage current generated in the wiring Ls increases significantly, resulting in a significant change in the voltage value of the wiring Ls. In this embodiment, in the determination preparation step that is first performed after the power supply voltage is started, the number of times the process of step S316, in which charge is stored in the capacitive component of the detection circuit 33 including the wiring Ls is performed is set to a constant value, "n1", regardless of the elapsed time since the previous determination preparation step was performed, thereby making it possible to more reliably control the voltage value of the wiring Ls to potential VS2 in the determination preparation step. This makes it possible to improve the accuracy of the detection potential signal VX propagating through the wiring Ls, and to improve the determination accuracy of the state of the discharge section D[m].

[0169] Then, after the determination preparation step is completed, the liquid dispensing device 1 executes a determination step including the determination process described above (step S320). That is, after charge is accumulated in the capacitive component of the detection circuit 33 including the wiring Ls, the determination unit 8 determines the state of the dispensing section D[m] according to the detection signal SK output by the detection circuit 33. In other words, charge is accumulated in the capacitive component of the detection circuit 33 including the wiring Ls before the determination unit 8 determines the state of the dispensing section D[m] according to the detection signal SK output by the detection circuit 33.

[0170] In the determination step, the drive signal output unit 4 outputs a drive signal Com including the drive waveform PS (step S321). Specifically, in the determination step, the control unit 2 outputs a drive waveform specification signal dCom corresponding to the drive waveform PS to the drive signal output unit 4, and the drive signal output unit 4 outputs a drive signal Com including the drive waveform PS by amplifying the signal waveform defined by the input drive waveform specification signal dCom.

[0171] Furthermore, in the determination process, the control unit 2 generates a print data signal SI which controls the switch Wc[m] corresponding to the ejection section D[m] to be inspected to conduction during control periods TT1 and TT2 in which the voltage value of the drive signal Com output by the drive signal output unit 4 is the voltage value of the drive waveform PS, which starts at a reference potential V0, changes to a potential VS1 which is lower than the reference potential V0, and then becomes a potential VS2 which is higher than the reference potential V0, and maintains the potential VS2, and controls the switch Ws[m] corresponding to the ejection section D[m] to be inspected to conduction during control periods TT2 to TT4 in which the voltage value of the drive waveform PS is the potential VS2, and outputs this print data signal SI to the connection state specification circuit 310. In other words, the switch Ws[m] is controlled to conduction (step S322). As a result, a signal corresponding to the residual vibration generated in the ejection section D[m] that occurs in the upper electrode Zu[m] of the piezoelectric element PZ[m] propagates through the wiring Ls as a detection potential signal VX and is input to the detection circuit 33.

[0172] Subsequently, in accordance with the print data signal SI output by the control unit 2, during the control period TT3, switch W1 is controlled to be non-conductive and switch W2 is controlled to be conductive. As a result, the detection circuit 33 acquires a detection potential signal VX corresponding to the residual vibration generated in the ejection section D[m] (step S323), and outputs a detection signal SK corresponding to the acquired detection potential signal VX to the determination unit 8. At this time, noise components superimposed on the detection potential signal VX are removed.

[0173] Then, the determination unit 8 acquires a detection signal SK corresponding to the detection potential signal VX output by the detection circuit 33 (step S324), corrects the acquired detection signal SK based on the detection potential signal VX with correction value information, calculates waveform information such as the amplitude, amplitude attenuation rate, period, and frequency of residual vibration generated in the discharge section D[m] based on the corrected signal, and determines the state of the discharge section D[m] to be inspected according to the calculated waveform information. In other words, the state of the discharge section D[m] to be inspected is determined based on the signal obtained by correcting the detection signal SK based on the detection potential signal VX with correction value information (step S325).

[0174] In addition, the state determination process may determine the state of multiple discharge units D, in which case steps S321 to S324 are repeatedly executed in accordance with each of the multiple discharge units D to be inspected.

[0175] As described above, the determination step for determining the state of the discharge section D[m] based on the correction value information and the detection signal SK based on the detection potential signal VX includes: step S321 of supplying the drive waveform PS to the piezoelectric element PZ[m] as a supply drive signal Vin[m] based on the drive signal Com; step S322 of switching the switch Ws[m] after step S321 so that a signal corresponding to the residual vibration generated in the discharge section D[m] propagates through the wiring Ls and is supplied to the detection circuit 33 as the detection potential signal VX; step S324 of acquiring the detection signal SK corresponding to the detection potential signal VX output by the detection circuit 33 after step S322; and step S325 of determining the state of the discharge section D[m] based on the signal obtained by correcting the detection signal SK acquired in step S324 with the correction value information.

[0176] Here, the discharge sections D[1] to D[M] are examples of multiple discharge sections, the detection circuit 33 including the wiring Ls is an example of a residual vibration detection circuit, and the determination unit 8 is an example of a determination circuit. Also, the drive signal Com and the supply drive signal Vin based on the drive signal Com are examples of drive signals. The drive waveform PS is an example of a drive waveform signal, the signal generated at the upper electrode Zu[m] of the piezoelectric element PZ[m] and the detection potential signal VX including said signal are examples of residual vibration signals, the detection signal SK is an example of a residual vibration detection signal, and the time threshold Tth is an example of a threshold time. Furthermore, the determination preparation step is an example of a pre-charge step, step S311 is an example of a timing step, steps S312 to S314 are examples of a charging time determination step, and steps S315 to S316 are examples of a charging step. Furthermore, the determination step is an example of a discharge state determination step, step S321 is an example of a determination drive step, step S324 is an example of a residual vibration acquisition step, and step S325 is an example of a discharge section determination step.

[0177] 6. Effects In the liquid discharge state determination method of the liquid discharge device 1 configured as described above, the acquisition step for acquiring correction value information includes step S31 of supplying a drive waveform PC to the piezoelectric element PZ[m] as a supply drive signal Vin[m] based on the drive signal Com; step S32 after step S31 of switching the switch Ws[m] so that a signal corresponding to the residual vibration generated in the discharge section D[m] propagates through the wiring Ls and is supplied to the detection circuit 33 as a detected potential signal VX; and step S34 after step S32 of holding a detection signal SK corresponding to the detected potential signal VX output by the detection circuit 33 as correction value information. The determination step for acquiring correction value information based on the differential pulse PLd generated according to the potential difference between the wiring Ls through which the detected potential signal VX output by the detection circuit 33 propagates and the piezoelectric element PZ[m], and determining the state of the discharge section D[m], is based on the drive signal Com. The procedure includes the steps of: step S321, supplying the drive waveform PS to the piezoelectric element PZ[m] as the supply drive signal Vin[m]; step S322, after step S321, switching the switch Ws[m] so that a signal corresponding to the residual vibration generated in the discharge section D[m] propagates through the wiring Ls and is supplied to the detection circuit 33 as a detected potential signal VX; step S324, after step S322, acquiring a detection signal SK corresponding to the detected potential signal VX output by the detection circuit 33; and step S325, determining the state of the discharge section D[m] based on the signal obtained by correcting the detection signal SK acquired in step S324 with correction value information. By including these steps, when determining the state of the discharge section D[m], even if a potential difference occurs between the wiring Ls on which the detected potential signal VX output by the detection circuit 33 propagates and the piezoelectric element PZ[m], the likelihood that this potential difference will affect the accuracy of determining the discharge state from the discharge section D[m] is reduced. As a result, even if the voltage value of the wiring Ls through which the detection potential signal VX output by the detection circuit 33 propagates changes due to leakage current or the like, and a potential difference is generated between the wiring Ls through which the detection potential signal VX output by the detection circuit 33 propagates and the piezoelectric element PZ[m], the accuracy of determining the discharge state of the discharge section D[m] based on residual vibrations generated in the discharge section D[m] can be improved.

[0178] Furthermore, in the liquid dispensing device 1 of this embodiment, an acquisition preparation step is performed to store charge in the capacitive component of the detection circuit 33 including the wiring Ls before executing the acquisition step, and a determination preparation step is performed to store charge in the capacitive component of the detection circuit 33 including the wiring Ls before executing the determination step. This makes it possible to reduce the potential difference between the terminals of the switch Ws[m] in the acquisition step and the determination step, specifically the potential difference between the wiring Ls through which the detection potential signal VX output by the detection circuit 33 propagates and the piezoelectric element PZ[m]. As a result, the signal accuracy of the detection signal SK is improved, and the accuracy of determining the dispensing state from the dispensing unit D[m] based on the signal obtained by correcting the detection signal SK with correction value information can be further enhanced.

[0179] Furthermore, in the method for determining the discharge state of the liquid discharge device 1 in this embodiment configured as described above, the determination preparation step of storing charge in the capacitive component of the detection circuit 33 including the wiring Ls includes: step S311 of acquiring elapsed time information Et corresponding to the elapsed time since the previous determination preparation step was performed; steps S312, S313, S314 of determining the charging time for storing charge in the capacitive component of the detection circuit 33 including the wiring Ls according to the acquired elapsed time information Et; and the determined charging The process includes a step S316 in which a potential VS2 is supplied to the wiring Ls according to the charging time, thereby accumulating charge in the capacitive component of the detection circuit 33 including the wiring Ls. This allows the time required to accumulate charge in the capacitive component of the detection circuit 33 including the wiring Ls to be defined according to the voltage value of the wiring Ls.

[0180] This reduces the time required for the judgment preparation process and thus the time required for the state determination process.

[0181] Furthermore, in the liquid dispensing device 1 configured in this embodiment, the storage unit 9 stores the detection signal SK output by the detection circuit 33 as correction value information, which includes the signal output from the dispensing unit D after the drive waveform PC is supplied to the piezoelectric element PZ[m] as a supply drive signal Vin[m] based on the drive signal Com, and corresponds to the detection potential signal VX propagating through the wiring Ls. The determination unit 8 determines the state of the dispensing unit D[m] based on the signal obtained by correcting the detection signal SK output by the detection circuit 33 with the correction value information stored in the storage unit 9, which includes the signal output from the dispensing unit D after the drive waveform PS is supplied to the piezoelectric element PZ[m] as a supply drive signal Vin[m] based on the drive signal Com, and corresponds to the detection potential signal VX propagating through the wiring Ls, using the correction value information stored in the storage unit 9. This makes it possible to reduce the potential difference between the two terminals of the switch Ws[m], which is the potential difference between the wiring Ls through which the detection potential signal VX output by the detection circuit 33 propagates and the piezoelectric element PZ[m].

[0182] This improves the signal accuracy of the detection signal SK, and further enhances the accuracy of determining the discharge state from the discharge unit D[m] based on the signal obtained by correcting the detection signal SK with correction value information.

[0183] Furthermore, in the liquid dispensing device 1 of this embodiment, the charging time for storing charge in the capacitive component of the detection circuit 33 including the wiring Ls is determined according to the elapsed time since charge was previously stored in the capacitive component of the detection circuit 33 including the wiring Ls. This makes it possible to shorten the time required to execute the judgment preparation step and shorten the time required for the state determination step.

[0184] 7. 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.

[0185] 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.

[0186] 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.

[0187] Furthermore, in this embodiment, the signal waveform of the drive signal Com output by the drive signal output unit 4 is described as being switchable between drive waveforms PP1, PP2, drive waveform PS, and drive waveform PC. As explained above, 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.

[0188] Although embodiments and modified examples have been described above, the present invention is not limited to these embodiments and can be implemented in various forms without departing from its spirit. For example, the above embodiments can be combined as appropriate.

[0189] 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). The present invention also 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. Finally, the present invention includes configurations that add known technology to the configurations described in the embodiments.

[0190] The following conclusions can be drawn from the embodiments described above.

[0191] One embodiment of the method for determining the discharge state is: Multiple dispensing units that dispense liquid when a drive signal is supplied, A residual vibration detection circuit that acquires one of the residual vibration signals corresponding to the residual vibration generated after the drive element output by each of the plurality of discharge units is driven, and outputs a residual vibration detection signal corresponding to the acquired residual vibration signal, A determination circuit that determines the state of the discharge unit in accordance with the residual vibration detection signal, A method for determining the discharge state in a liquid discharge device equipped with the following: A pre-charge step in which charge is stored in the capacitive component of the residual vibration detection circuit, A discharge state determination step, which determines the state of the discharge unit based on the residual vibration detection signal, Includes, The pre-charge step and the discharge state determination step are performed repeatedly. The aforementioned pre-charge process is A timing step to obtain the elapsed time since the previous pre-charge step was performed, A charging time determination step, which determines the charging time for accumulating charge in the capacitive component of the residual vibration detection circuit according to the elapsed time, A charging step in which charge is stored in the capacitive component of the residual vibration detection circuit according to the charging time, Includes, The aforementioned discharge state determination step is: A determination drive step in which a drive waveform signal is supplied to the drive element as the drive signal, After the determination drive step, a residual vibration acquisition step is performed to acquire the residual vibration detection signal output by the residual vibration detection circuit, A discharge unit determination step, which determines the state of the discharge unit based on the residual vibration detection signal obtained in the residual vibration acquisition step, Includes.

[0192] In this discharge state determination method, the pre-charge step for storing charge in the capacitive component of the residual vibration detection circuit includes a timing step for acquiring the elapsed time since the previous pre-charge step was performed, a charging time determination step for determining the charging time for storing charge in the capacitive component of the residual vibration detection circuit according to the elapsed time, and a charging step for storing charge in the capacitive component of the residual vibration detection circuit according to the charging time. This allows the time for storing charge in the capacitive component of the residual vibration detection circuit to be determined based on the elapsed time since the previous pre-charge step was performed and the amount of charge stored in the capacitive component of the residual vibration detection circuit. As a result, if sufficient charge is stored in the capacitive component of the residual vibration detection circuit, the time for storing charge in the capacitive component of the residual vibration detection circuit can be shortened. This makes it possible to shorten the time required to execute a discharge state determination method, which includes a pre-charge step of storing charge in the capacitive component of a residual vibration detection circuit, and a discharge state determination step of determining the state of the discharge unit based on the residual vibration detection signal, without reducing the accuracy of determining the state of the discharge unit.

[0193] One embodiment of the discharge state determination method is as follows: The charging time when the elapsed time is shorter than a predetermined threshold time may be shorter than the charging time when the elapsed time is longer than the threshold time.

[0194] In this discharge state determination method, if sufficient charge is stored in the capacitive component of the residual vibration detection circuit, the time required to store charge in the capacitive component of the residual vibration detection circuit can be shortened, thereby shortening the time required to execute the discharge state determination method.

[0195] One embodiment of the discharge state determination method is as follows: If the elapsed time is shorter than a predetermined threshold time, the number of charging cycles in which charge is stored in the capacitive component of the residual vibration detection circuit during the charging process may be less than the number of charging cycles in which charge is stored in the capacitive component of the residual vibration detection circuit during the charging process when the elapsed time is longer than the threshold time.

[0196] In this discharge state determination method, if sufficient charge is stored in the capacitive component of the residual vibration detection circuit, the time required to store charge in the capacitive component of the residual vibration detection circuit can be shortened, thereby shortening the time required to execute the discharge state determination method.

[0197] One embodiment of the discharge state determination method is as follows: The pre-charge step and the discharge state determination step may be performed between pages of the medium to which the liquid discharged from the plurality of discharge units lands.

[0198] One embodiment of the discharge state determination method is as follows: The pre-charge step and the discharge state determination step may be performed between discharge paths.

[0199] One embodiment of the discharge state determination method is as follows: In the charging time determination step included in the pre-charge step that is first performed after the power supply voltage is started, the charging time may be determined to a constant value regardless of the elapsed time.

[0200] During periods when the power supply voltage is interrupted, leakage current increases, and the decrease in charge in the capacitive component of the residual vibration detection circuit increases. In contrast, in this discharge state determination method, in the charging time determination step included in the pre-charge step that is first performed after the power supply voltage is started, the charging time is determined to a constant value regardless of the elapsed time. This makes it possible to store sufficient charge in the capacitive component of the residual vibration detection circuit during the discharge state determination step, thereby reducing the risk of a decrease in the accuracy of determining the state of the discharge section.

[0201] One embodiment of the discharge state determination method is as follows: The discharge unit may include a piezoelectric element that outputs an electromotive force corresponding to residual vibration as the residual vibration signal.

[0202] One embodiment of the discharge state determination method is as follows: The driving element is a piezoelectric element, and the piezoelectric element may discharge a quantity of liquid from the discharge section corresponding to the displacement caused by the supply of the driving signal.

[0203] One embodiment of a liquid dispensing device is: Multiple dispensing units that dispense liquid when a drive signal is supplied, A residual vibration detection circuit that acquires one of the residual vibration signals corresponding to the residual vibration generated after the drive element output by each of the plurality of discharge units is driven, and outputs a residual vibration detection signal corresponding to the acquired residual vibration signal, A determination circuit that determines the state of the discharge unit in accordance with the residual vibration detection signal, Equipped with, The charging time for accumulating charge in the capacitive component of the residual vibration detection circuit before the determination circuit determines the state of the discharge unit is determined according to the elapsed time since charge was previously accumulated in the capacitive component of the residual vibration detection circuit.

[0204] In this liquid dispensing device, the charging time for accumulating charge in the capacitive component of the residual vibration detection circuit before the determination circuit determines the state of the dispensing section is determined according to the elapsed time since charge was previously accumulated in the capacitive component of the residual vibration detection circuit. Therefore, if sufficient charge is already accumulated in the capacitive component of the residual vibration detection circuit, the time required to accumulate charge in the capacitive component of the residual vibration detection circuit can be shortened. This makes it possible to shorten the time required to accumulate charge in the capacitive component of the residual vibration detection circuit, which is the detection speed of the signal corresponding to residual vibration, without reducing the accuracy of determining the state of the dispensing section.

[0205] In one embodiment of the liquid dispensing device, The charging time when the elapsed time is shorter than a predetermined threshold time may be shorter than the charging time when the elapsed time is longer than the threshold time.

[0206] In this liquid dispensing device, if sufficient charge is stored in the capacitive component of the residual vibration detection circuit, the time required to store charge in the capacitive component of the residual vibration detection circuit can be shortened.

[0207] In one embodiment of the liquid dispensing device, When the elapsed time is shorter than a predetermined threshold time, the number of charging cycles for accumulating charge in the capacitive component of the residual vibration detection circuit may be less than the number of charging cycles for accumulating charge in the capacitive component of the residual vibration detection circuit when the elapsed time is longer than the threshold time.

[0208] In this liquid dispensing device, if sufficient charge is stored in the capacitive component of the residual vibration detection circuit, the time required to store charge in the capacitive component of the residual vibration detection circuit can be shortened.

[0209] In one embodiment of the liquid dispensing device, Between the pages of the medium to which the liquid discharged from the plurality of discharge units lands, charge is accumulated in the capacitive component of the residual vibration detection circuit, and thereafter, the determination circuit may determine the state of the discharge unit in accordance with the residual vibration detection signal output by the residual vibration detection circuit.

[0210] In one embodiment of the liquid dispensing device, Between the discharge paths, charge may be accumulated in the capacitive component of the residual vibration detection circuit, and thereafter, the determination circuit may determine the state of the discharge unit in accordance with the residual vibration detection signal output by the residual vibration detection circuit.

[0211] In one embodiment of the liquid dispensing device, The initial charging time after the power supply voltage is started may be determined to a constant value, regardless of the elapsed time.

[0212] During periods when the power supply voltage is interrupted, leakage current increases, and the decrease in charge in the capacitive component of the residual vibration detection circuit increases. In contrast, in this liquid dispensing device, the power supply voltage... By setting the initial charging time, determined after the start of supply, to a constant value regardless of the elapsed time, it becomes possible to store sufficient charge in the capacitive component of the residual vibration detection circuit, thereby reducing the risk of a decrease in the accuracy of determining the state of the discharge section.

[0213] In one embodiment of the liquid dispensing device, The discharge unit may include a piezoelectric element that outputs an electromotive force corresponding to residual vibration as the residual vibration signal.

[0214] In one embodiment of the liquid dispensing device, The driving element is a piezoelectric element, and the piezoelectric element may discharge a quantity of liquid from the discharge section corresponding to the displacement caused by the supply of the driving signal. [Explanation of Symbols]

[0215] 1...Liquid dispensing device, 2...Control unit, 3...Head unit, 4...Drive signal output unit, 7...Transport unit, 8...Determination unit, 9...Storage unit, 31...Supply circuit, 32...Recording head, 33...Detection 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...Diaphragm, 322...Cavity, 32 3...Nozzle plate, 324...Cavity plate, 325...Reservoir, 326...Ink supply port, 327...Ink intake, 330...Waveform shaping circuit, 331...AD conversion circuit, C1...Capacitor, D...Ejection unit, Lb,Lc,Ls...Wiring, N...Nozzle, NL...Nozzle row, OP1,OP2...Operational amplifier, P...Medium, PZ...Piezoelectric element, R1~R3,Rf...Resistor, W1,W2,Wc,Wf,Ws...Switch, Zd...Lower electrode, Zm...Piezoelectric element, Zu...Upper electrode

Claims

1. Multiple dispensing units that dispense liquid when a drive signal is supplied, A residual vibration detection circuit acquires one of the residual vibration signals corresponding to the residual vibration generated after the drive element output by each of the plurality of discharge units is driven, and outputs a residual vibration detection signal corresponding to the acquired residual vibration signal. A determination circuit that determines the state of the discharge unit in accordance with the residual vibration detection signal, A method for determining the discharge state in a liquid discharge device equipped with the following: A pre-charge step in which charge is stored in the capacitive component of the residual vibration detection circuit, A discharge state determination step, which determines the state of the discharge unit based on the residual vibration detection signal, Includes, The pre-charge step and the discharge state determination step are performed repeatedly. The aforementioned pre-charge process is A timing step to obtain the elapsed time since the previous pre-charge step was performed, A charging time determination step, which determines the charging time for accumulating charge in the capacitive component of the residual vibration detection circuit according to the elapsed time, A charging step in which charge is stored in the capacitive component of the residual vibration detection circuit according to the charging time, Includes, The aforementioned discharge state determination step is: A determination drive step in which a drive waveform signal is supplied to the drive element as the drive signal, After the determination drive step, a residual vibration acquisition step is performed to acquire the residual vibration detection signal output by the residual vibration detection circuit, A discharge unit determination step, which determines the state of the discharge unit based on the residual vibration detection signal obtained in the residual vibration acquisition step, including, A method for determining the discharge state, characterized by the above.

2. The charging time when the elapsed time is shorter than a predetermined threshold time is shorter than the charging time when the elapsed time is longer than the threshold time. The method for determining the discharge state according to feature 1.

3. When the elapsed time is shorter than a predetermined threshold time, the number of charging cycles in which charge is stored in the capacitive component of the residual vibration detection circuit during the charging process is less than the number of charging cycles in which charge is stored in the capacitive component of the residual vibration detection circuit during the charging process when the elapsed time is longer than the threshold time. The method for determining the discharge state according to feature 1.

4. The pre-charge step and the discharge state determination step are performed between pages of the medium to which the liquid discharged from the plurality of discharge units lands. The method for determining the discharge state according to feature 1.

5. The pre-charge step and the discharge state determination step are performed between discharge paths. The method for determining the discharge state according to feature 1.

6. In the charging time determination step included in the pre-charge step that is first performed after the power supply voltage is started, the charging time is determined to a constant value regardless of the elapsed time. The method for determining the discharge state according to feature 1.

7. The discharge unit comprises a piezoelectric element that outputs an electromotive force corresponding to the residual vibration as the residual vibration signal. include, The method for determining the discharge state according to feature 1.

8. The driving element is a piezoelectric element, and the piezoelectric element discharges an amount of liquid from the discharge section corresponding to the displacement caused by the supply of the driving signal. The method for determining the discharge state according to feature 1.

9. Multiple dispensing units that dispense liquid when a drive signal is supplied, A residual vibration detection circuit acquires one of the residual vibration signals corresponding to the residual vibration generated after the drive element output by each of the plurality of discharge units is driven, and outputs a residual vibration detection signal corresponding to the acquired residual vibration signal. A determination circuit that determines the state of the discharge unit in accordance with the residual vibration detection signal, Equipped with, Before the determination circuit determines the state of the discharge unit, the charging time for accumulating charge in the capacitive component of the residual vibration detection circuit is determined according to the elapsed time since charge was previously accumulated in the capacitive component of the residual vibration detection circuit. A liquid dispensing device characterized by the following features.

10. The charging time when the elapsed time is shorter than a predetermined threshold time is shorter than the charging time when the elapsed time is longer than the threshold time. The liquid dispensing device according to feature 9.

11. When the elapsed time is shorter than a predetermined threshold time, the number of charging cycles for storing charge in the capacitive component of the residual vibration detection circuit is less than the number of charging cycles for storing charge in the capacitive component of the residual vibration detection circuit when the elapsed time is longer than the threshold time. The liquid dispensing device according to feature 9.

12. Between the pages of the medium to which the liquid discharged from the plurality of discharge units lands, an electric charge is accumulated in the capacitive component of the residual vibration detection circuit, and thereafter, the determination circuit determines the state of the discharge unit in accordance with the residual vibration detection signal output by the residual vibration detection circuit. The liquid dispensing device according to feature 9.

13. Between the discharge paths, charge is accumulated in the capacitive component of the residual vibration detection circuit, and thereafter, the determination circuit determines the state of the discharge unit according to the residual vibration detection signal output by the residual vibration detection circuit. The liquid dispensing device according to feature 9.

14. The initial charging time after the power supply voltage is started is determined to a constant value, regardless of the elapsed time. The liquid dispensing device according to feature 9.

15. The discharge unit includes a piezoelectric element that outputs an electromotive force corresponding to the residual vibration as the residual vibration signal. The liquid dispensing device according to feature 9.

16. The driving element is a piezoelectric element, and the piezoelectric element discharges an amount of liquid from the discharge section corresponding to the displacement caused by the supply of the driving signal. The liquid dispensing device according to feature 9.

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