Liquid dispensing device, head unit, and inspection method for liquid dispensing device

Abstract

The condition of the dispensing part is inspected accurately. [Solution] A liquid dispensing device comprising: a first dispensing unit equipped with a first piezoelectric element that displaces in accordance with a drive signal and capable of dispensing liquid in accordance with the displacement of the first piezoelectric element; a second dispensing unit equipped with a second piezoelectric element that displaces in accordance with a drive signal and capable of dispensing liquid in accordance with the displacement of the second piezoelectric element; and an inspection unit that, when a drive signal is supplied to the second piezoelectric element in a unit period, inspects the state of the first dispensing unit based on a detection signal corresponding to the potential of the first piezoelectric element during an inspection period included in the unit period, wherein the drive signal changes potential from a first potential to a second potential in a second period of the unit period, maintains the second potential in a third period following the second period of the unit period, and changes potential from the second potential to a first potential in a fourth period following the third period of the unit period, the third period includes an inspection period, and the second period is longer than the fourth period.

Description

Technical Field

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[0001] The present invention relates to a liquid ejection device, a head unit, and a method for inspecting a liquid ejection device.

Background Art

[0002] In a liquid ejection device such as an inkjet printer, a piezoelectric element provided in a ejection unit is driven by a drive signal, and the piezoelectric element is displaced to eject a liquid such as ink filled in the ejection unit, and an image is formed on a medium. However, in a liquid ejection device, ejection abnormality may occur where the liquid cannot be normally ejected from the ejection unit. When ejection abnormality occurs, the image quality of the image formed on the medium in the printing process deteriorates. Therefore, conventionally, a technique for inspecting the state of the ejection unit has been proposed. For example, Patent Document 1 discloses a technique for inspecting the state of the ejection unit based on the potential of a piezoelectric element provided in the ejection unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional technology, when the piezoelectric element provided in the ejection unit is driven by a drive signal, vibration may occur in the piezoelectric element. In this case, the potential of the piezoelectric element provided in the ejection unit to be inspected fluctuates, and the state of the ejection unit may not be accurately inspected.

Means for Solving the Problems

[0005] To solve the above problems, the liquid dispensing device according to the present invention comprises: a first dispensing unit equipped with a first piezoelectric element that displaces in accordance with a drive signal and capable of dispensing liquid in accordance with the displacement of the first piezoelectric element; a second dispensing unit equipped with a second piezoelectric element that displaces in accordance with the drive signal and capable of dispensing liquid in accordance with the displacement of the second piezoelectric element; and an inspection unit that, when the drive signal is supplied to the second piezoelectric element in a unit period, inspects the state of the first dispensing unit based on a detection signal corresponding to the potential of the first piezoelectric element during an inspection period included in the unit period, wherein the drive signal is The device is characterized in that, during the first period of the aforementioned unit period, the first potential is maintained; during the second period of the aforementioned unit period following the first period, the potential changes from the first potential to the second potential; during the third period of the aforementioned unit period following the second period, the second potential is maintained; during the fourth period of the aforementioned unit period following the third period, the potential changes from the second potential to the first potential; and during the fifth period of the aforementioned unit period following the fourth period, the first potential is maintained, with the third period including the inspection period, and the second period being longer than the fourth period.

[0006] Furthermore, the liquid dispensing device according to the present invention comprises a first dispensing unit that is capable of dispensing liquid according to the displacement of a first piezoelectric element which is displaced in accordance with a drive signal, and an inspection unit that inspects the state of the first dispensing unit based on a detection signal corresponding to the potential of the first piezoelectric element during an inspection period included in the unit period when the drive signal is supplied to the first piezoelectric element during a drive period included in the unit period, wherein the drive signal maintains a first potential during a first period of the unit period, changes potential from the first potential to a second potential during a second period following the first period of the unit period, maintains the second potential during a third period following the second period of the unit period, changes potential from the second potential to the first potential during a fourth period following the third period of the unit period, maintains the first potential during a fifth period following the fourth period of the unit period, the third period includes the inspection period, the drive period does not include the inspection period and includes at least the second period, and the second period is longer than the fourth period.

[0007] Furthermore, the liquid dispensing device according to the present invention comprises: a first dispensing unit equipped with a first piezoelectric element that displaces in accordance with a drive signal and capable of dispensing liquid in accordance with the displacement of the first piezoelectric element; a second dispensing unit equipped with a second piezoelectric element that displaces in accordance with the drive signal and capable of dispensing liquid in accordance with the displacement of the second piezoelectric element; and an inspection unit that, when the drive signal is supplied to the second piezoelectric element during a unit period, inspects the state of the first dispensing unit based on a detection signal corresponding to the potential of the first piezoelectric element during an inspection period included in the unit period, wherein the drive signal changes potential from a first potential to a second potential during a first transition period within the unit period, maintains the second potential during a maintenance period following the first transition period within the unit period, and changes potential from the second potential to the first potential during a second transition period following the maintenance period within the unit period, the maintenance period includes the inspection period, and the first transition period is longer than the second transition period.

[0008] Furthermore, the head unit according to the present invention comprises: a first discharge unit that includes a first piezoelectric element that displaces in accordance with a drive signal and is capable of discharging liquid in accordance with the displacement of the first piezoelectric element; a second discharge unit that includes a second piezoelectric element that displaces in accordance with the drive signal and is capable of discharging liquid in accordance with the displacement of the second piezoelectric element; and a detection unit that detects the potential of the first piezoelectric element during an inspection period included in a unit period when the drive signal is supplied to the second piezoelectric element during the unit period, wherein the drive signal maintains a first potential during a first period of the unit period, changes potential from the first potential to a second potential during a second period following the first period of the unit period, maintains the second potential during a third period following the second period of the unit period, changes potential from the second potential to the first potential during a fourth period following the third period of the unit period, maintains the first potential during a fifth period following the fourth period of the unit period, the third period includes the inspection period, and the second period is longer than the fourth period.

[0009] Furthermore, the head unit according to the present invention comprises a first piezoelectric element that displaces in accordance with a drive signal, a first discharge unit capable of discharging liquid in accordance with the displacement of the first piezoelectric element, and a detection unit that detects the potential of the first piezoelectric element during an inspection period included in a unit period when the drive signal is supplied to the first piezoelectric element during a drive period included in the unit period, wherein the drive signal maintains a first potential during a first period of the unit period, changes potential from the first potential to a second potential during a second period following the first period of the unit period, maintains the second potential during a third period following the second period of the unit period, changes potential from the second potential to the first potential during a fourth period following the third period of the unit period, maintains the first potential during a fifth period following the fourth period of the unit period, the third period includes the inspection period, the drive period does not include the inspection period and includes at least the second period, and the second period is longer than the fourth period.

[0010] Furthermore, the head unit according to the present invention comprises: a first discharge unit that includes a first piezoelectric element that displaces in accordance with a drive signal and is capable of discharging liquid in accordance with the displacement of the first piezoelectric element; a second discharge unit that includes a second piezoelectric element that displaces in accordance with the drive signal and is capable of discharging liquid in accordance with the displacement of the second piezoelectric element; and a detection unit that detects the potential of the first piezoelectric element during an inspection period included in a unit period when the drive signal is supplied to the second piezoelectric element during the unit period, wherein the drive signal changes potential from a first potential to a second potential during a first transition period of the unit period, maintains the second potential during a maintenance period following the first transition period of the unit period, and changes potential from the second potential to the first potential during a second transition period following the maintenance period of the unit period, the maintenance period includes the inspection period, and the first transition period is longer than the second transition period.

[0011] Furthermore, the inspection method for a liquid dispensing device according to the present invention comprises: a first dispensing unit equipped with a first piezoelectric element that displaces in accordance with a drive signal and capable of dispensing liquid in accordance with the displacement of the first piezoelectric element; and a second dispensing unit equipped with a second piezoelectric element that displaces in accordance with the drive signal and capable of dispensing liquid in accordance with the displacement of the second piezoelectric element, wherein when the drive signal is supplied to the second piezoelectric element in a unit period, the state of the first dispensing unit is inspected based on a detection signal corresponding to the potential of the first piezoelectric element during the inspection period included in the unit period, and the drive signal The device is characterized in that it maintains a first potential during a first period of the unit period, changes potential from the first potential to the second potential during a second period following the first period of the unit period, maintains the second potential during a third period following the second period of the unit period, changes potential from the second potential to the first potential during a fourth period following the third period of the unit period, maintains the first potential during a fifth period following the fourth period of the unit period, the third period includes the inspection period, and the second period is longer than the fourth period.

[0012] Furthermore, the present invention relates to an inspection method for a liquid dispensing device, comprising a first dispensing unit that is equipped with a first piezoelectric element that is displaced in accordance with a drive signal and capable of dispensing liquid in accordance with the displacement of the first piezoelectric element, wherein when the drive signal is supplied to the first dispensing unit during a drive period included in a unit period, the state of the first dispensing unit is inspected based on a detection signal corresponding to the potential of the first piezoelectric element during an inspection period included in the unit period, wherein the drive signal maintains a first potential during a first period of the unit period, changes potential from the first potential to a second potential during a second period following the first period of the unit period, maintains the second potential during a third period following the second period of the unit period, changes potential from the second potential to the first potential during a fourth period following the third period of the unit period, maintains the first potential during a fifth period following the fourth period of the unit period, the third period includes the inspection period, the drive period does not include the inspection period and includes at least the second period, and the second period is longer than the fourth period.

[0013] Furthermore, the method for inspecting a liquid dispensing device according to the present invention is a method for inspecting a liquid dispensing device comprising: a first dispensing unit equipped with a first piezoelectric element that displaces in accordance with a drive signal and capable of dispensing liquid in accordance with the displacement of the first piezoelectric element; and a second dispensing unit equipped with a second piezoelectric element that displaces in accordance with the drive signal and capable of dispensing liquid in accordance with the displacement of the second piezoelectric element, wherein when the drive signal is supplied to the second piezoelectric element in a unit period, the state of the first dispensing unit is inspected based on a detection signal corresponding to the potential of the first piezoelectric element in an inspection period included in the unit period, the drive signal changes potential from a first potential to a second potential in a first transition period of the unit period, maintains the second potential in a maintenance period following the first transition period of the unit period, and changes potential from the second potential to the first potential in a second transition period following the maintenance period of the unit period, the maintenance period includes the inspection period, and the first transition period is longer than the second transition period. [Brief explanation of the drawing]

[0014] [Figure 1] It is a block diagram showing an example of the configuration of an inkjet printer 1 according to an embodiment of the present invention. [Figure 2] It is a perspective view showing an example of the schematic internal structure of the inkjet printer 1. [Figure 3] It is a cross-sectional view for explaining an example of the structure of the ejection part D[m]. [Figure 4] It is a plan view showing an example of the arrangement of the nozzles N in the inkjet printer 1. [Figure 5] It is a block diagram showing an example of the configuration of the head unit 3. [Figure 6] It is a timing chart for explaining an example of the signal supplied to the head unit 3. [Figure 7] It is an explanatory diagram for explaining an example of the operation of the connection state specifying circuit 310. [Figure 8] It is a timing chart for explaining an example of the signal supplied to the head unit 3. [Figure 9] It is an explanatory diagram for explaining an example of the operation of the connection state specifying circuit 310. [Figure 10] It is an explanatory diagram showing an example of the operation of the head unit 3. [Figure 11] It is an explanatory diagram showing an example of the operation of the head unit 3. [Figure 12] It is an explanatory diagram showing an example of the operation of the head unit 3. [Figure 13] It is an explanatory diagram showing an example of the detection potential signal VX[m]. [Figure 14] It is an explanatory diagram showing an example of the detection potential signal VX[m]. [Figure 15] It is an explanatory diagram showing an example of the detection potential signal VX[m]. [Figure 18] It is an explanatory diagram showing an example of the detection potential signal VX[m]. [Figure 17] It is an explanatory diagram showing an example of the detection potential signal VX[m] related to the proportionality. [Figure 18]It is an explanatory diagram showing an example of a detection potential signal VX[m] according to a comparative example. [Figure 19] It is an explanatory diagram for explaining an example of the operation of the connection state specifying circuit 310 according to Modification 1. [Figure 20] It is a timing chart for explaining an example of a signal supplied to the head unit 3 in Modification 2.

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, in each figure, the dimensions and scales of each part are appropriately different from the actual ones. In addition, the embodiments described below are preferred specific examples of the present invention, and thus various technically preferable limitations are imposed. However, the scope of the present invention is not limited to these embodiments unless there is a description to specifically limit the present invention in the following description.

[0016] <<A. Embodiment>> In the present embodiment, an inkjet printer that discharges ink to form an image on a recording paper PP will be exemplified to explain a liquid discharge device.

[0017] <<1. Outline of Inkjet Printer>> Hereinafter, an example of the configuration of the inkjet printer 1 according to the present embodiment will be described with reference to FIGS. 1 to 4.

[0018] FIG. 1 is a functional block diagram showing an example of the configuration of the inkjet printer 1.

[0019] As shown in FIG. 1, print data Img indicating an image to be formed by the inkjet printer 1 is supplied to the inkjet printer 1 from a host computer such as a personal computer or a digital camera. The inkjet printer 1 executes a printing process for forming an image indicated by the print data Img supplied from the host computer on the recording paper PP.

[0020] As shown in Figure 1, the inkjet printer 1 comprises a control unit 2 that controls various parts of the inkjet printer 1, a head unit 3 equipped with an ink ejection unit D, a drive signal generation unit 4 that generates a drive signal Com for driving the ejection unit D, an inspection unit 5 that checks the state of the ejection unit D, a transport unit 7 that changes the relative position of the recording paper PP with respect to the head unit 3, and a storage unit 8 that stores various information. Note that inkjet printer 1 is an example of a "liquid ejection device," ink is an example of a "liquid," and inspection unit 5 is an example of an "inspection unit."

[0021] In this embodiment, we assume that the inkjet printer 1 comprises one or more head units 3, one or more drive signal generation units 4 corresponding one-to-one with one or more head units 3, and one or more inspection units 5 corresponding one-to-one with one or more head units 3. Specifically, in this embodiment, we assume that the inkjet printer 1 comprises four head units 3, four drive signal generation units 4 corresponding one-to-one with the four head units 3, and four inspection units 5 corresponding one-to-one with the four head units 3. However, for the sake of explanation, in the following description, we will focus on one of the four head units 3, one drive signal generation unit 4 provided in correspondence with one of the four drive signal generation units 4, and one inspection unit 5 provided in correspondence with one of the four inspection units 5, as shown in Figure 1.

[0022] The memory unit 8 is configured to include one or both of the following: volatile memory such as RAM (Random Access Memory) and non-volatile memory such as ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), or PROM (Programmable ROM), and stores the control program for the inkjet printer 1.

[0023] The control unit 2 is comprised of one or more CPUs (Central Processing Units). However, the control unit 2 may 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 executes a control program stored in the memory unit 8 and controls each part of the inkjet printer 1 by operating according to the control program.

[0024] Specifically, the control unit 2 generates a waveform specification signal dCom and supplies the generated waveform specification signal dCom to the drive signal generation unit 4. The waveform specification signal dCom is a digital signal that defines the waveform of the drive signal Com. The drive signal Com is an analog signal for driving the discharge unit D. The drive signal generation unit 4 includes a DA conversion circuit and generates a drive signal Com having the waveform defined by the waveform specification signal dCom. In this embodiment, it is assumed that the drive signal Com includes drive signal Com-A and drive signal Com-B.

[0025] Furthermore, the control unit 2 generates a designated signal SI and supplies the generated designated signal SI to the head unit 3. The designated signal SI is a digital signal that specifies the type of operation of the ejection unit D. Specifically, the designated signal SI specifies whether or not to drive the ejection unit D by supplying a drive signal Com to the ejection unit D, thereby specifying the type of operation of the ejection unit D.

[0026] When printing is performed, the control unit 2 generates signals to control the head unit 3, such as a specified signal SI, based on the print data Img. Also, when printing is performed, the control unit 2 generates signals to control the drive signal generation unit 4, such as a waveform specified signal dCom. Furthermore, when printing is performed, the control unit 2 generates signals to control the transport unit 7. In this way, during printing, the control unit 2 controls the transport unit 7 to change the relative position of the recording paper PP with respect to the head unit 3, while adjusting the presence or absence of ink ejection from the ejection unit D, the timing of ink ejection, etc., and controls each part of the inkjet printer 1 so that an image corresponding to the print data Img is formed on the recording paper PP.

[0027] As shown in Figure 1, the head unit 3 comprises a supply circuit 31, a recording head 32, and a detection circuit 33.

[0028] The recording head 32 is equipped with M ejection units D. Here, the value M is a natural number satisfying "M≧2". In the following, the m-th ejection unit D among the M ejection units D provided on the recording head 32 may be referred to as ejection unit D[m]. Here, the variable m is a natural number satisfying "1≦m≦M". Furthermore, in the following, if a component or signal of the inkjet printer 1 corresponds to ejection unit D[m] among the M ejection units D, the subscript [m] may be added to the code used to represent that component or signal.

[0029] The supply circuit 31 switches whether or not to supply the drive signal Com to the discharge unit D[m] based on the specified signal SI. Hereinafter, the drive signal Com supplied to the discharge unit D[m] may be referred to as the supply drive signal Vin[m]. Furthermore, the supply circuit 31 switches whether or not to supply the detection potential signal VX[m] to the detection circuit 33 based on the specified signal SI. Here, the detection potential signal VX[m] is a signal indicating the potential of the upper electrode Zu[m] provided on the piezoelectric element PZ[m] that is equipped in the discharge unit D[m]. Hereafter, when the detection potential signal VX[m] is supplied from the discharge unit D[m] to the detection circuit 33, the discharge unit D[m] may be referred to as the discharge unit DK under inspection. The piezoelectric element PZ[m] and the upper electrode Zu[m] will be described later in Figure 3.

[0030] The detection circuit 33 generates a detection signal SK[m] based on a detection potential signal VX[m] supplied via the supply circuit 31 from the discharge unit D[m] designated as the discharge unit DK to be inspected. Specifically, the detection circuit 33 generates the detection signal SK[m] by, for example, amplifying the detection potential signal VX[m] and removing noise components. Note that the detection circuit 33 is an example of a "detection unit".

[0031] The inspection unit 5 inspects the state of the discharge unit D[m] designated as the discharge unit DK to be inspected, based on the detection signal SK[m] supplied from the detection circuit 33, and outputs an inspection result signal SS[m] indicating the result of the inspection. In this embodiment, it is assumed that the "inspection of the state of the discharge unit D[m]" is an energy storage capacity inspection. An energy storage capacity inspection is an inspection that determines whether or not the piezoelectric element PZ[m] provided in the discharge unit D[m] has a predetermined energy storage capacity.

[0032] Here, "predetermined energy storage capacity" refers to the ability of a piezoelectric element PZ[m] to maintain a predetermined potential for a predetermined period of time, for example, when a drive signal Com is supplied to the piezoelectric element PZ[m], thereby setting the upper electrode Zu[m] of the piezoelectric element PZ[m] to a desired potential. In other words, "cases where the piezoelectric element PZ[m] does not have the predetermined energy storage capacity" refers to cases where, for example, an electrical short circuit is formed between the piezoelectric element PZ[m] of one ejection unit D[m] and the piezoelectric element PZ of another ejection unit D, and as a result of leakage current flowing through this short circuit, the upper electrode Zu[m] of the piezoelectric element PZ[m] of the ejection unit D[m] cannot maintain the desired potential for a predetermined period of time. Here, "predetermined period" refers to, for example, the period during the printing process in which the upper electrode Zu[m] of the piezoelectric element PZ[m] should maintain the desired potential in order to form the image indicated by the print data Img on the recording paper PP. Specifically, the "predetermined period" may be a period corresponding to the driving cycle of the piezoelectric element PZ[m] by the driving signal Com, or it may be a period shorter than the driving cycle of the piezoelectric element PZ[m] by the driving signal Com. Furthermore, "maintaining the desired potential" includes, for example, maintaining the same potential as the desired potential, as well as maintaining a potential that is approximately the same as the desired potential. Here, "approximately the same potential as the desired potential" may be, for example, a potential that can be considered the same when errors are taken into account.

[0033] If the piezoelectric element PZ[m] of the ejection unit D[m] does not have a predetermined energy storage capacity, the potential of the upper electrode Zu[m] of the piezoelectric element PZ[m] is set to a potential different from the potential defined by the drive signal Com. Therefore, if the piezoelectric element PZ[m] does not have a predetermined energy storage capacity, the ejection unit D[m] ejects an amount of ink different from the amount of ink ejected defined by the drive signal Com, and the ejection unit D[m] ejects ink at a speed different from the ink ejection speed defined by the drive signal Com. Consequently, if the piezoelectric element PZ[m] does not have a predetermined energy storage capacity, the image quality formed by the inkjet printer 1 on the recording paper PP deteriorates.

[0034] In this embodiment, it is assumed that when the discharge unit DD to be driven is driven by the drive signal Com, the state of the discharge unit DK to be inspected is inspected based on the detected potential signal VX[m] detected from the discharge unit DK to be inspected. Here, the discharge unit DD to be driven is a discharge unit D different from the discharge unit DK to be inspected. In this embodiment, as an example, it is assumed that the discharge unit DD to be driven is a discharge unit D adjacent to the discharge unit DK to be inspected.

[0035] Hereinafter, the series of processes performed in the inkjet printer 1 for inspecting the state of the ejection unit DK to be inspected will be referred to as the ejection unit inspection process. Specifically, the ejection unit inspection process is a series of processes that include inspecting the state of the ejection unit DK to be inspected, and preparatory processes such as driving the ejection unit DD to be driven, which are performed for the purpose of inspecting the state of the ejection unit DK to be inspected.

[0036] When the discharge unit inspection process is performed, the control unit 2 supplies a designated signal SI to the head unit 3. This allows the control unit 2 to specify the discharge unit DK to be inspected and the discharge unit DD to be driven from among the discharge units D[1] to D[M]. The control unit 2 then controls the head unit 3 so that the discharge unit DD to be driven is driven by the drive signal Com, and then the detected potential signal VX[m] detected from the discharge unit DK to be inspected is supplied to the detection circuit 33. When the discharge unit inspection process is performed, the detection circuit 33 generates a detection signal SK[m] based on the detected potential signal VX[m] detected from the discharge unit DK to be inspected. When the discharge unit inspection process is performed, the inspection unit 5 inspects the state of the discharge unit D[m] driven as the discharge unit DK to be inspected based on the detection signal SK[m] supplied from the detection circuit 33.

[0037] Figure 2 is a perspective view showing an example of the schematic internal structure of inkjet printer 1.

[0038] As shown in Figure 2, in this embodiment, it is assumed that the inkjet printer 1 is a serial printer. Specifically, when the inkjet printer 1 performs a printing process, it transports the recording paper PP in the X1 direction, and while reciprocating the head unit 3 in the Y1 direction which intersects the X1 direction and the Y2 direction which is the opposite direction of the Y1 direction, it ejects ink from the ejection unit D[m] to form dots Dt on the recording paper PP according to the print data Img.

[0039] In the following, the X1 direction and its opposite direction, the X2 direction, will be collectively referred to as the "X-axis direction," the Y1 direction intersecting the X-axis direction and its opposite direction, the Y2 direction, will be collectively referred to as the "Y-axis direction," and the Z1 direction intersecting the X-axis and Y-axis directions and its opposite direction, the Z2 direction, will be collectively referred to as the "Z-axis direction." In this embodiment, as an example, the case in which the X-axis direction, Y-axis direction, and Z-axis direction are mutually orthogonal will be described. However, the present invention is not limited to this embodiment. The X-axis direction, Y-axis direction, and Z-axis direction only need to intersect each other. In this embodiment, the Z1 direction is the direction in which ink is ejected from the ejection section D [m].

[0040] As shown in Figure 2, the inkjet printer 1 according to this embodiment comprises a housing 100 and a carriage 110 that is capable of reciprocating within the housing 100 in the Y-axis direction and is equipped with four head units 3.

[0041] In this embodiment, as shown in Figure 2, it is assumed that the carriage 110 houses four ink cartridges 120, each corresponding one-to-one with four inks: cyan, magenta, yellow, and black. Furthermore, as described above, this embodiment assumes that the inkjet printer 1 has four head units 3, each corresponding one-to-one with the four ink cartridges 120. Each ejection unit D[m] receives ink from the ink cartridge 120 corresponding to the head unit 3 on which the ejection unit D[m] is located. As a result, each ejection unit D[m] fills itself with the supplied ink, and the ink filled inside the ejection unit D[m] can be ejected from the nozzle N provided in the ejection unit D[m]. Note that the ink cartridges 120 may be located outside the carriage 110.

[0042] Furthermore, as described above, the inkjet printer 1 according to this embodiment includes a transport unit 7. As shown in Figure 2, the transport unit 7 comprises a carriage transport mechanism 71 for reciprocating the carriage 110 in the Y-axis direction, a carriage guide shaft 76 for supporting the carriage 110 so that it can reciprocate in the Y-axis direction, a media transport mechanism 73 for transporting the recording paper PP, and a platen 75 provided in the Z1 direction of the carriage 110. Therefore, when a printing process is performed, the transport unit 7 uses the carriage transport mechanism 71 to reciprocate the head unit 3 together with the carriage 110 along the carriage guide shaft 76 in the Y-axis direction, and the media transport mechanism 73 transports the recording paper PP on the platen 75 in the X1 direction, thereby changing the relative position of the recording paper PP with respect to the head unit 3 and enabling ink to land on the entire recording paper PP.

[0043] Figure 3 is a schematic partial cross-sectional view of the recording head 32, cut to include the ejection section D[m].

[0044] As shown in Figure 3, the ejection unit D[m] comprises a piezoelectric element PZ[m], a cavity CV filled with ink, a nozzle N communicating with the cavity CV, and a diaphragm 321. The ejection unit D[m] ejects ink from the cavity CV through the nozzle N when the piezoelectric element PZ[m] is driven by a supply drive signal Vin[m]. The cavity CV 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 CV communicates with a reservoir 325 via an ink supply port 326. The reservoir 325 communicates with an ink cartridge 120 corresponding to the ejection unit D[m] via a common liquid chamber 327. The piezoelectric element PZ[m] has an upper electrode Zu[m], a lower electrode Zd[m], and a piezoelectric body Zm[m] provided between the upper electrode Zu[m] and the lower electrode Zd[m]. The lower electrode Zd[m] is electrically connected to a power supply line Ld set to a predetermined potential VBS. When a supply drive signal Vin[m] is supplied to the upper electrode Zu[m] and a voltage is applied between the upper electrode Zu[m] and the lower electrode Zd[m], the piezoelectric element PZ[m] is displaced in the Z1 or Z2 direction according to the applied voltage, and as a result the piezoelectric element PZ[m] vibrates. The lower electrode Zd[m] is joined to the diaphragm 321. Therefore, when the piezoelectric element PZ[m] is driven by the supply drive signal Vin[m] and vibrates, the diaphragm 321 also vibrates. Then, the vibration of the diaphragm 321 changes the volume of the cavity CV and the pressure inside the cavity CV, causing the ink filled in the cavity CV to be ejected from the nozzle N.

[0045] In this embodiment, as an example, it is assumed that the flow paths such as cavities CV provided in each of the M ejection sections D[1] to D[M] of the head unit 3 are in communication with a common liquid chamber 327 that stores ink. Therefore, in this embodiment, vibrations generated in one of the M ejection sections D[1] to D[M] of the head unit 3 are transmitted to the other ejection sections D via the ink stored in the common liquid chamber 327.

[0046] Figure 4 is an explanatory diagram illustrating an example of the arrangement of the four head units 3 and the total of 4M nozzles N provided on the four head units 3, when the inkjet printer 1 is viewed from above in the Z2 direction. As shown in Figure 4, the head unit 3 is provided with a nozzle row Ln. Here, the nozzle row Ln is a plurality of nozzles N arranged to extend in a row in a predetermined direction.

[0047] In this embodiment, as an example, we assume that each nozzle row Ln is composed of M nozzles N arranged to extend in the X-axis direction. Specifically, in this embodiment, we assume that M nozzles N corresponding to M discharge sections D[1] to D[M] are arranged in order from the X1 direction to the X2 direction. That is, in this embodiment, we assume that the nozzle N of discharge section D[m0] is arranged adjacent to the nozzle N of discharge section D[m0-1] in the X2 direction of the nozzle N of discharge section D[m0-1], and the nozzle N of discharge section D[m0+1] is arranged adjacent to the nozzle N of discharge section D[m0] in the X2 direction of the nozzle N of discharge section D[m0]. In other words, in this embodiment, we assume that the discharge unit D[m0] is positioned adjacent to the discharge unit D[m0-1] in the X2 direction of the discharge unit D[m0-1], and the discharge unit D[m0+1] is positioned adjacent to the discharge unit D[m0] in the X2 direction of the discharge unit D[m0]. Here, the variable m0 is a natural number satisfying "2≦m0≦M-1".

[0048] <<2. Overview of the Head Unit>> The following describes the overview of the head unit 3 with reference to Figures 5 through 7.

[0049] Figure 5 is a block diagram showing an example of the configuration of the head unit 3.

[0050] As shown in Figure 5, the head unit 3 comprises a supply circuit 31, a recording head 32, and a detection circuit 33. The head unit 3 also includes a wiring La to which the drive signal Com-A is supplied from the drive signal generation unit 4, a wiring Lb to which the drive signal Com-B is supplied from the drive signal generation unit 4, a power supply line Ld set to potential VBS, and a wiring Ls for supplying the detection potential signal VX[m] to the detection circuit 33.

[0051] The supply circuit 31 comprises M switches Wa[1] to Wa[M] that correspond one-to-one with M discharge units D[1] to D[M], M switches Wb[1] to Wb[M] that correspond one-to-one with M discharge units D[1] to D[M], M switches Ws[1] to Ws[M] that correspond one-to-one with M discharge units D[1] to D[M], and a connection state specification circuit 310 that specifies the connection state of each switch.

[0052] The connection status specification circuit 310 generates a connection status specification signal Qa[m] that specifies whether switch Wa[m] is on or off, a connection status specification signal Qb[m] that specifies whether switch Wb[m] is on or off, and a connection status specification signal Qs[m] that specifies whether switch Ws[m] is on or off, based on the specification signal SI, latch signal LAT, change signal CH, period specification signal Tsig, and clock signal CL supplied from the control unit 2.

[0053] Switch Wa[m] switches between conductivity and non-conductivity between wiring La and the upper electrode Zu[m] of piezoelectric element PZ[m] based on the connection state specification signal Qa[m]. In this embodiment, switch Wa[m] is turned on when the connection state specification signal Qa[m] is high level and turned off when it is low level. When switch Wa[m] is turned on, the drive signal Com-A supplied to wiring La is supplied as a supply drive signal Vin[m] to the upper electrode Zu[m] of discharge section D[m]. The switch Wb[m] switches between conductivity and non-conductivity between the wiring Lb and the upper electrode Zu[m] of the piezoelectric element PZ[m] based on the connection state specification signal Qb[m]. In this embodiment, the switch Wb[m] is turned on when the connection state specification signal Qb[m] is high level and turned off when it is low level. When the switch Wb[m] is turned on, the drive signal Com-B supplied to the wiring Lb is supplied to the upper electrode Zu[m] of the discharge section D[m] as the supply drive signal Vin[m]. The switch Ws[m] switches between conduction and non-conductivity between the wiring Ls and the upper electrode Zu[m] of the piezoelectric element PZ[m] based on the connection state specification signal Qs[m]. In this embodiment, the switch Ws[m] is turned on when the connection state specification signal Qs[m] is at a high level and turned off when it is at a low level. When the switch Ws[m] is turned on, the potential of the upper electrode Zu[m] provided on the discharge section D[m] is supplied to the detection circuit 33 via the wiring Ls as the detection potential signal VX[m].

[0054] In this embodiment, the detection circuit 33 generates a detection signal SK[m] having a waveform corresponding to the waveform of the detection potential signal VX[m], based on the detection potential signal VX[m] supplied from the wiring Ls. Specifically, the detection circuit 33 generates a signal that is an amplified version of the detection potential signal VX[m], from which noise components have been removed, and outputs the generated signal as the detection signal SK[m].

[0055] In this embodiment, when the inkjet printer 1 performs a printing process, a plurality of unit printing periods TP are set as the operating period of the inkjet printer 1. The inkjet printer 1 can drive each ejection unit D for printing during each unit printing period TP. Hereinafter, the drive signal Com-A supplied to the head unit 3 during a unit printing period TP may be referred to as the printing drive signal Com-AP, and the drive signal Com-B supplied to the head unit 3 during a unit printing period TP may be referred to as the printing drive signal Com-BP. Furthermore, in this embodiment, when the inkjet printer 1 performs an ejection unit inspection process, multiple unit inspection periods TX or multiple unit inspection periods TY are set as the operating period of the inkjet printer 1. In the following, the drive signal Com-A supplied to the head unit 3 during unit inspection period TX may be referred to as the inspection drive signal Com-AX, and the drive signal Com-B supplied to the head unit 3 during unit inspection period TX may be referred to as the inspection drive signal Com-BX. Also, the drive signal Com-A supplied to the head unit 3 during unit inspection period TY may be referred to as the inspection drive signal Com-AY, and the drive signal Com-B supplied to the head unit 3 during unit inspection period TY may be referred to as the inspection drive signal Com-BY. Furthermore, in the following, the unit print period TP, unit check period TX, and unit check period TY may be collectively referred to as the unit operation period TT.

[0056] Figure 6 is a timing chart showing an example of various signals, such as the drive signal Com, supplied to the head unit 3 during each unit printing period TP.

[0057] As shown in Figure 6, when a print operation is performed, the control unit 2 outputs a latch signal LAT having multiple pulse PLLs. This allows the control unit 2 to define the unit print period TP as the period from the rising edge of one pulse PLL to the rising edge of the next pulse PLL.

[0058] Furthermore, when the printing process is executed, the control unit 2 outputs a change signal CH with a pulse PLC during the unit printing period TP. As a result, the control unit 2 divides the unit printing period TP into a control period TQ1 from the rising edge of the pulse PLL to the rising edge of the pulse PLC, and a control period TQ2 from the rising edge of the pulse PLC to the rising edge of the pulse PLL.

[0059] As shown in Figure 6, the designation signal SI includes M individual designation signals Sd[1] to Sd[M] that correspond one-to-one with M ejection units D[1] to D[M]. The individual designation signals Sd[m] specify the mode of operation of the ejection units D[m] in each unit operation period TT (i.e., each unit printing period TP, each unit inspection period TX, or each unit inspection period TY) when the inkjet printer 1 performs printing or ejection unit inspection. When printing is performed, the control unit 2 supplies the designation signal SI, which includes M individual designation signals Sd[1] to Sd[M], to the connection state designation circuit 310 in synchronization with the clock signal CL prior to each unit printing period TP. The connection state designation circuit 310 then generates connection state designation signals Qa[m], Qb[m], and Qs[m] based on the individual designation signals Sd[m] in each unit printing period TP.

[0060] In this embodiment, the individual designation signal Sd[m] can take any one of four values ​​during the unit printing period TP in which the printing process is performed: a value of "1" which designates the ejection unit D[m] as the large dot forming ejection unit DP-1, a value of "2" which designates the ejection unit D[m] as the medium dot forming ejection unit DP-2, a value of "3" which designates the ejection unit D[m] as the small dot forming ejection unit DP-3, and a value of "4" which designates the ejection unit D[m] as the non-dot forming ejection unit DP-4 (see Figure 7 described later).

[0061] Here, the large dot-forming ejection unit DP-1 is the ejection unit D that forms large dots during a unit printing period TP. The medium dot-forming ejection unit DP-2 is the ejection unit D that forms medium dots during a unit printing period TP. The small dot-forming ejection unit DP-3 is the ejection unit D that forms small dots during a unit printing period TP. The non-dot-forming ejection unit DP-4 is the ejection unit D that does not form dots during a unit printing period TP.

[0062] As shown in Figure 6, the print drive signal Com-AP has waveforms PA1 and PA2, which are provided for each unit print period TP. Waveform PA1 is provided for the control period TQ1 of the unit print period TP and is a waveform that returns to the reference potential V0, passing through a potential VL1 which is lower than the reference potential V0, and a potential VH1 which is higher than the reference potential V0. Waveform PA1 is determined so that when the supply drive signal Vin[m] having waveform PA1 is supplied to the ejection unit D[m], ink corresponding to the ink amount ξ1 is ejected from the ejection unit D[m]. Waveform PA2 is provided for the control period TQ2 of the unit print period TP and is a waveform that returns to the reference potential V0, passing through a potential VL2 which is lower than the reference potential V0, and a potential VH2 which is higher than the reference potential V0. The waveform PA2 is defined such that when a supply drive signal Vin[m] having the waveform PA2 is supplied to the ejection unit D[m], ink corresponding to the ink amount ξ2 is ejected from the ejection unit D[m]. In this embodiment, it is assumed that large dots are formed from the sum of ink amounts ξ1 and ξ2, medium dots are formed from ink amount ξ1, and small dots are formed from ink amount ξ2.

[0063] In this embodiment, as an example, we assume that when the potential of the supply drive signal Vin[m] supplied to the ejection unit D[m] is high, the volume of the cavity CV in the ejection unit D[m] becomes smaller compared to when the potential is low. Therefore, when the ejection unit D[m] is driven by a supply drive signal Vin[m] having waveform PA1 or waveform PA2, the ink in the ejection unit D[m] is ejected from the nozzle N as the potential of the supply drive signal Vin[m] changes from low to high.

[0064] As shown in Figure 6, the print drive signal Com-BP has a waveform PB provided for each unit print period TP. Here, the waveform PB is a waveform that includes two micro-vibration waveforms: one provided for the control period TQ1 of each unit print period TP, which returns to the reference potential V0 from a reference potential V0, via a potential VB that is lower than the reference potential V0; and another provided for the control period TQ2 of each unit print period TP, which returns to the reference potential V0 from a reference potential V0, via a potential VB that is lower than the reference potential V0. In this embodiment, the waveform PB is provided so that ink is not ejected from the ejection unit D[m] even when the ejection unit D[m] is driven by the print drive signal Com-BP.

[0065] Figure 7 is an explanatory diagram showing an example of the operation of the connection state specification circuit 310 during a unit printing period TP.

[0066] As shown in Figure 7, when the individual designation signal Sd[m] indicates a value of "1" which designates the ejection unit D[m] as the large dot forming ejection unit DP-1 during the unit printing period TP, the connection state designation circuit 310 maintains the connection state designation signal Qa[m] at a high level for the unit printing period TP. In this case, the switch Wa[m] is turned on for the unit printing period TP. Therefore, during the unit printing period TP, the ejection unit D[m] is driven by the supply drive signal Vin[m] which has waveforms PA1 and PA2, and ejects ink in the sum of ink amounts ξ1 and ξ2, which corresponds to the amount of a large dot. Furthermore, if the individual designation signal Sd[m] indicates a value of "2" which designates the ejection unit D[m] as the medium dot forming ejection unit DP-2 during the unit printing period TP, the connection state designation circuit 310 maintains the connection state designation signal Qa[m] at a high level during the control period TQ1 and maintains the connection state designation signal Qb[m] at a high level during the control period TQ2. In this case, switch Wa[m] is turned on during the control period TQ1 and switch Wb[m] is turned on during the control period TQ2. Therefore, during the control period TQ1, the ejection unit D[m] is driven by the supply drive signal Vin[m] having waveform PA1 and ejects ink with an ink quantity ξ1, which corresponds to the medium dot. Furthermore, if the individual designation signal Sd[m] indicates a value of "3" which designates the ejection unit D[m] as the small dot forming ejection unit DP-3 during the unit printing period TP, the connection state designation circuit 310 maintains the connection state designation signal Qb[m] at a high level during the control period TQ1 and maintains the connection state designation signal Qa[m] at a high level during the control period TQ2. In this case, the switch Wa[m] is turned on during the control period TQ2. Therefore, during the control period TQ2, the ejection unit D[m] is driven by the supply drive signal Vin[m] having waveform PA2 and ejects ink with an ink quantity ξ2, which corresponds to a small dot. Furthermore, if the individual designation signal Sd[m] indicates a value of "4" which designates the ejection unit D[m] as the dot-non-forming ejection unit DP-4 during the unit printing period TP, the connection state designation circuit 310 maintains the connection state designation signal Qb[m] at a high level for the unit printing period TP. In this case, the switch Wb[m] is turned on for the unit printing period TP. Therefore, the ejection unit D[m] is driven not to eject ink by the supply drive signal Vin[m] which has a micro-vibration waveform during the unit printing period TP.

[0067] <<3. Overview of Discharge Section Inspection Process>> The following outline of the discharge section inspection process will be explained with reference to Figures 8 through 18.

[0068] <<3.1. About Inspection Mode MD>> In this embodiment, as an example, we assume that the inkjet printer 1 can perform ejection unit inspection processing using two inspection modes MD: a normal inspection mode MD-X and a high-speed inspection mode MD-Y.

[0069] Here, the normal inspection mode MD-X is an inspection mode MD that inspects the state of the ejector unit DK to be inspected with ink filling the cavities CV of the ejector unit DK to be inspected and the ejector unit DD to be driven. Specifically, the normal inspection mode MD-X is an inspection mode MD that inspects the state of the ejector unit DK to be inspected with ink filling the cavities CV of each of the ejector units D[1] to D[M]. For example, the normal inspection mode MD-X may be an inspection mode MD used in an ejector unit inspection process that is performed after the inkjet printer 1 has been shipped, when the ink cartridge 120 has been installed in the inkjet printer 1 by the user of the inkjet printer 1 and ink has been supplied from the ink cartridge 120 to the cavities CV.

[0070] Furthermore, high-speed inspection mode MD-Y is an inspection mode MD that inspects the state of the target ejector unit DK while the cavities CV of the target ejector unit DK and the drive target ejector unit DD are not filled with ink. Specifically, high-speed inspection mode MD-Y is an inspection mode MD that inspects the state of the target ejector unit DK while the cavities CV of each of the ejector units D[1] to D[M] are not filled with ink. For example, high-speed inspection mode MD-Y may be an inspection mode MD used in an ejector unit inspection process performed before the product shipment of the inkjet printer 1 while the cavities CV of each of the ejector units D[1] to D[M] are not filled with ink.

[0071] In this embodiment, it is assumed that high-speed inspection mode MD-Y is an inspection mode MD used in an inspection process for ejector units when the cavities CV of the ejector unit DK and the ejector unit DD to be driven are not filled with ink. However, the present invention is not limited to this embodiment. High-speed inspection mode MD-Y may also be an inspection mode MD used in an inspection process for ejector units when the cavities CV of the ejector unit DK and the ejector unit DD to be driven are filled with a specific type of liquid. Here, a specific type of liquid is a liquid with lower viscosity than the liquid that is normally filled in the cavity CV of the ejector unit DK and the ejector unit DD to be driven in the inspection mode MD-X. Specifically, the specific type of liquid may be, for example, a liquid that is not used for image formation in the printing process performed by the inkjet printer 1. More specifically, the specific type of liquid may be, for example, a preservative liquid used to protect the ejector unit D of the inkjet printer 1 before shipment, an antifreeze liquid used to prevent the ejector unit D of the inkjet printer 1 from freezing before shipment, or a cleaning liquid used to clean the flow path communicating with the ejector unit D of the inkjet printer 1.

[0072] In this embodiment, the control unit 2 selects the inspection mode MD for executing the ejection unit inspection process based on whether or not an ink cartridge 120 is mounted on the carriage 110, and the type of ink cartridge 120 mounted on the carriage 110. However, the present invention is not limited to this embodiment. The control unit 2 may also select the inspection mode MD for executing the ejection unit inspection process based on the operation of the user of the inkjet printer 1 or the operation of the person setting up the inkjet printer 1.

[0073] <<3.2. Various signals related to the discharge unit inspection process>> Figure 8 is a timing chart showing an example of various signals, such as the drive signal Com, supplied to the head unit 3 during the unit inspection period TX and the unit inspection period TY.

[0074] As shown in Figure 8, when the discharge section inspection process is performed using the normal inspection mode MD-X, the control unit 2 outputs a latch signal LAT having multiple pulses PLX. This allows the control unit 2 to define the unit inspection period TX as the period from the rising edge of one pulse PLX to the rising edge of the next pulse PLX. Furthermore, when the discharge section inspection process is performed using the high-speed inspection mode MD-Y, the control unit 2 outputs a latch signal LAT having multiple pulses PLY. This allows the control unit 2 to define a unit inspection period TY as the period from the rising edge of one pulse PLY to the rising edge of the next pulse PLY, which is shorter than the unit inspection period TX. In the following, unit inspection periods TX and TY may be collectively referred to as unit inspection period TXY.

[0075] As shown in Figure 8, when the ejection unit inspection process is performed using the normal inspection mode MD-X, the control unit 2 outputs a period specification signal Tsig having pulses PTX1 and PTX2. As a result, the control unit 2 divides the unit inspection period TX into three control periods: TSX1, from the rising edge of pulse PLX to the rising edge of pulse PTX1; TSX2, from the rising edge of pulse PTX1 to the rising edge of pulse PTX2; and TSX3, from the rising edge of pulse PTX2 to the rising edge of pulse PLX. Furthermore, when the ejection section inspection process is performed using the high-speed inspection mode MD-Y, the control unit 2 outputs a period specification signal Tsig having pulses PTY1 and PTY2. As a result, the control unit 2 divides the unit inspection period TY into three control periods: TSY1, from the rising edge of pulse PLY to the rising edge of pulse PTY1; TSY2, from the rising edge of pulse PTY1 to the rising edge of pulse PTY2; and TSY3, from the rising edge of pulse PTY2 to the rising edge of pulse PLY.

[0076] In this embodiment, as an example, we assume that control period TSX1 has a longer duration than control period TSY1, control period TSX2 and control period TSY2 have the same duration, and control period TSX3 and control period TSY3 have the same duration. Hereafter, control period TSX1 and control period TSY1 may be collectively referred to as control period TS1, control period TSX2 and control period TSY2 may be collectively referred to as control period TS2, and control period TSX3 and control period TSY3 may be collectively referred to as control period TS3.

[0077] As shown in Figure 8, when the discharge section inspection process is performed in normal inspection mode MD-X, the control unit 2 controls the drive signal generation unit 4 so that the inspection drive signal Com-AX is supplied as drive signal Com-A and the inspection drive signal Com-BX is supplied as drive signal Com-B. Furthermore, when the discharge section inspection process is performed using the high-speed inspection mode MD-Y, the control unit 2 controls the drive signal generation unit 4 so that the inspection drive signal Com-AY is supplied as drive signal Com-A and the inspection drive signal Com-BY is supplied as drive signal Com-B.

[0078] As shown in Figure 8, the test drive signal Com-AX has a waveform PA-X provided in the unit test period TX. Here, the waveform PA-X is a waveform in which the reference potential V0 is maintained during the control period TX1 of the unit test period TX, the potential changes from the reference potential V0 to the drive potential VH during the control period TX2 following the control period TX1 of the unit test period TX, the drive potential VH is maintained during the control period TX3 following the control period TX2 of the unit test period TX, the potential changes from the drive potential VH to the reference potential V0 during the control period TX4 following the control period TX3 of the unit test period TX, and the reference potential V0 is maintained during the control period TX5 following the control period TX4 of the unit test period TX. Of these, control period TX1 is included in control period TSX1, starts simultaneously with the start of control period TSX1, and ends before the end of control period TSX1. Control period TX2 is included in control period TSX1, starts after the start of control period TSX1, and ends before the end of control period TSX1. Control period TX3 includes part of control period TSX1, all of control period TSX2, and part of control period TSX3, starts after the start of control period TSX1 and before the start of control period TSX2, and ends after the end of control period TSX2 and before the end of control period TSX3. In other words, control period TSX2 is included in control period TX3. Control period TX4 is included in control period TSX3, starts after the start of control period TSX3, and ends before the end of control period TSX3. Control period TX5 is included in control period TSX3, starts after the start of control period TSX3, and ends simultaneously with the end of control period TSX3. In this embodiment, the duration of the control period TX2 is longer than the duration of the control period TX4.

[0079] Furthermore, in this embodiment, it is assumed that the driving potential VH is higher than the reference potential V0, but the present invention is not limited to this embodiment. The driving potential VH may be lower than the reference potential V0. Also, in this embodiment, it is assumed that the waveform PA-X maintains the reference potential V0 during the control period TX1, but the present invention is not limited to this embodiment. The waveform PA-X is sufficient if the potential at the start and end of the control period TX1 is at least the reference potential V0. Also, in this embodiment, it is assumed that the waveform PA-X maintains the reference potential V0 during the control period TX5, but the present invention is not limited to this embodiment. The waveform PA-X is sufficient if the potential at the start and end of the control period TX5 is at least the reference potential V0.

[0080] Furthermore, the test drive signal Com-BX has a waveform PB-X provided for the unit test period TX. Here, the waveform PB-X maintains the reference potential V0 during control periods TSX1 and TSX2 of the unit test period TX, and a micro-oscillating waveform is provided during control period TSX3 of the unit test period TX. As mentioned above, the micro-oscillating waveform is a waveform that returns to the reference potential V0 from the reference potential V0, via a potential VB that is lower than the reference potential V0.

[0081] As shown in Figure 8, the test drive signal Com-AY has a waveform PA-Y provided for the unit test period TY. Here, the waveform PA-Y is a waveform in which the reference potential V0 is maintained during the control period TY1 of the unit test period TY, the potential changes from the reference potential V0 to the drive potential VH during the control period TY2 following the control period TY1 of the unit test period TY, the drive potential VH is maintained during the control period TY3 following the control period TY2 of the unit test period TY, the potential changes from the drive potential VH to the reference potential V0 during the control period TY4 following the control period TY3 of the unit test period TY, and the reference potential V0 is maintained during the control period TY5 following the control period TY4 of the unit test period TY. Of these, control period TY1 is included in control period TSY1, starts simultaneously with the start of control period TSY1, and ends before the end of control period TSY1. Control period TY2 is included in control period TSY1, starts after the start of control period TSY1, and ends before the end of control period TSY1. Control period TY3 includes part of control period TSY1, all of control period TSY2, and part of control period TSY3, starts after the start of control period TSY1 and before the start of control period TSY2, and ends after the end of control period TSY2 and before the end of control period TSY3. In other words, control period TSY2 is included in control period TY3. Control period TY4 is included in control period TSY3, starts after the start of control period TSY3, and ends before the end of control period TSY3. Control period TY5 is included in control period TSY3, starts after the start of control period TSY3, and ends simultaneously with the end of control period TSY3. In this embodiment, the duration of the control period TY2 is shorter than the duration of the control period TX2. Also, in this embodiment, the duration of the control period TY2 is less than or equal to the duration of the control period TY4. However, the present invention is not limited to these embodiments. The duration of the control period TY2 may be longer than the duration of the control period TY4.

[0082] Furthermore, in this embodiment, it is assumed that the waveform PA-Y maintains the reference potential V0 during the control period TY1, but the present invention is not limited to this embodiment. The waveform PA-Y is sufficient if the potential at the start and end of the control period TY1 is the reference potential V0. Furthermore, in this embodiment, it is assumed that the waveform PA-Y maintains the reference potential V0 during the control period TY5, but the present invention is not limited to this embodiment. The waveform PA-Y is sufficient if the potential at the start and end of the control period TY5 is the reference potential V0.

[0083] Furthermore, the test drive signal Com-BY has a waveform PB-Y provided for the unit test period TY. Here, the waveform PB-Y maintains the reference potential V0 during control periods TSY1 and TSY2 of the unit test period TY, and a micro-oscillating waveform is provided during control period TSY3 of the unit test period TY. As mentioned above, the micro-oscillating waveform is a waveform that returns to the reference potential V0, passing through a potential VB that is lower than the reference potential V0.

[0084] In this embodiment, it is assumed that the length of the unit inspection period TX is longer than the length of the unit printing period TP, and that the length of the unit inspection period TY is equal to the length of the unit printing period TP. However, the present invention is not limited to this embodiment. For example, the length of the unit inspection period TX may be the same as the length of the unit printing period TP. Also, the length of the unit inspection period TY may be shorter than or longer than the length of the unit printing period TP. It is sufficient that the length of the unit inspection period TX is equal to or greater than the length of the unit inspection period TY.

[0085] In the following, the test drive signals Com-AX and Com-AY may be collectively referred to as the test drive signal Com-AXY, and the test drive signals Com-BX and Com-BY may be collectively referred to as the test drive signal Com-BXY. Also, in the following, the waveforms PA-X and PA-Y may be collectively referred to as the waveform PA-XY, and the waveforms PB-X and PB-Y may be collectively referred to as the waveform PB-XY.

[0086] As shown in Figure 8, when the discharge unit inspection process is performed, the control unit 2 supplies a designation signal SI containing M individual designation signals Sd[1] to Sd[M] to the connection state designation circuit 310 in synchronization with the clock signal CL prior to each unit inspection period TXY (unit inspection period TX or unit inspection period TY). Then, in each unit inspection period TXY, the connection state designation circuit 310 generates connection state designation signals Qa[m], Qb[m], and Qs[m] based on the individual designation signal Sd[m].

[0087] Figure 9 is an explanatory diagram showing an example of the operation of the connection state specification circuit 310 during a unit inspection period TXY (unit inspection period TX or unit inspection period TY).

[0088] As shown in Figure 9, the individual designation signal Sd[m] can take any one of three values ​​during the unit inspection period TXY (unit inspection period TX or unit inspection period TY) in which the discharge unit inspection process is performed: a value of "5" which designates the discharge unit D[m] as the target discharge unit DD, a value of "6" which designates the discharge unit D[m] as the target discharge unit DK, and a value of "7" which designates the discharge unit D[m] as the standby discharge unit DW.

[0089] Here, the discharge unit DD to be driven is, as described above, the discharge unit D that is to be driven in the discharge unit inspection process. The discharge unit DK to be inspected is, as described above, the discharge unit D that is to be inspected in the discharge unit inspection process. As described above, in this embodiment, we assume that the discharge unit DK to be inspected and the discharge unit DD to be driven are adjacent to each other. The standby discharge unit DW is one of the M discharge units D[1] to D[M] provided by the head unit 3, other than the discharge unit DK to be inspected and the discharge unit DD to be driven.

[0090] As shown in Figure 9, when the individual designation signal Sd[m] indicates a value of "5" which designates the discharge unit D[m] as the drive target discharge unit DD during the unit inspection period TXY, the connection state designation circuit 310 maintains the connection state designation signal Qa[m] at a high level throughout the unit inspection period TXY. In this case, the switch Wa[m] is turned on throughout the unit inspection period TXY. Therefore, during the unit inspection period TXY, the discharge unit D[m] is driven by the supply drive signal Vin[m] having waveform PA-X or waveform PA-Y, and the potential during the control period TS2 (control period TSX2 or control period TSY2) is set to the drive potential VH. Furthermore, if the individual designation signal Sd[m] indicates a value of "7" which designates the discharge unit D[m] as the standby discharge unit DW during the unit inspection period TXY, the connection status designation circuit 310 maintains the connection status designation signal Qb[m] at a high level throughout the unit inspection period TXY. In this case, the switch Wb[m] is turned on throughout the unit inspection period TXY. Therefore, during the unit inspection period TXY, the discharge unit D[m] is driven by the supply drive signal Vin[m] having waveform PB-X or waveform PB-Y, and its potential during the control period TS2 (control period TSX2 or control period TSY2) is set to the reference potential V0.

[0091] As shown in Figure 9, when the individual designation signal Sd[m] indicates a value of "6" which designates the discharge unit D[m] as the discharge unit DK to be inspected during the unit inspection period TXY, the connection state designation circuit 310 maintains the connection state designation signal Qb[m] at a high level during control periods TS1 and TS3, and maintains the connection state designation signal Qs[m] at a high level during control period TS2. In this case, the switch Wb[m] is turned on during control periods TS1 and TS3, and the switch Ws[m] is turned on during control period TS2. Then, during control period TS2 (control period TSX2 or control period TSY2), the detection circuit 33 detects the potential of the upper electrode Zu[m] of the discharge unit D[m] as a detected potential signal VX[m] via the switch Ws[m].

[0092] In this embodiment, it is assumed that in each unit inspection period TXY, one discharge unit D[m] out of M discharge units D[1] to D[M] is designated as the discharge unit DK to be inspected, one discharge unit D is designated as the discharge unit DD to be driven, and the remaining (M-2) discharge units D are designated as standby discharge units DW. However, the present invention is not limited to this embodiment. In each unit inspection period TXY, one discharge unit D[m] out of M discharge units D[1] to D[M] may be designated as the discharge unit DK to be inspected, some or all of the remaining (M-1) discharge units D may be designated as the discharge unit DD to be driven, and the discharge units D that were not designated as the discharge unit DK to be inspected or the discharge unit DD to be driven may be designated as standby discharge units DW.

[0093] <<3.3. Operation of Head Unit 3 during Discharge Section Inspection Process>> Figures 10 to 12 are explanatory diagrams showing an example of the operation of the head unit 3. In the examples shown in Figures 10 to 12, for the sake of explanation, two discharge units D[1] and D[2] are shown out of the M discharge units D[1] to D[M] that the head unit 3 is equipped with. Also, in the examples shown in Figures 10 to 12, the case in which discharge unit D[1] is designated as the discharge unit DK to be inspected and discharge unit D[2] is designated as the discharge unit DD to be driven is illustrated. Furthermore, the example shown in Figure 10 shows an example of the operation of the head unit 3 during the control period TS1 within the unit inspection period TXY. Furthermore, the example shown in Figure 11 shows an example of the operation of the head unit 3 during the control period TS2 that follows the control period TS1 shown in Figure 10, in which each of the M discharge units D[1] to D[M] equipped with the head unit 3 has a predetermined energy storage capacity. Furthermore, the example shown in Figure 12 illustrates an example of the operation of the head unit 3 during a control period TS2 following the control period TS1 shown in Figure 10, where a short-circuit path LK is formed between discharge section D[1] and discharge section D[2] of the M discharge sections D[1] to D[M] provided by the head unit 3, and discharge sections D[1] and D[2] do not have a predetermined energy storage capacity.

[0094] As shown in Figure 10, in a unit inspection period TXY, if the discharge unit D[1] is designated as the discharge unit DK to be inspected and the discharge unit D[2] is designated as the discharge unit DD to be driven, then in the control period TS1 of the unit inspection period TXY, the upper electrode Zu[1] of the discharge unit D[1] and the wiring Lb are electrically connected via switch Wb[1], and the upper electrode Zu[2] of the discharge unit D[2] and the wiring La are electrically connected via switch Wa[2]. Therefore, in the control period TS1, the potential of the upper electrode Zu[1] is set to the reference potential V0, which is the potential of the inspection drive signal Com-BXY (inspection drive signal Com-BX or inspection drive signal Com-BY) in the control period TS1. Furthermore, during the control period TS1, the potential of the upper electrode Zu[2] changes from the reference potential V0 to the drive potential VH, similar to the potential change of the test drive signal Com-AXY (test drive signal Com-AX or test drive signal Com-AY) during the control period TS1.

[0095] As shown in Figure 11, when the discharge units D[1] and D[2] have a predetermined energy storage capacity, in the control period TS2 following the control period TS1 shown in Figure 10, the upper electrode Zu[1] of the discharge unit D[1] and the wiring Ls are electrically connected via switch Ws[1], and the upper electrode Zu[2] of the discharge unit D[2] and the wiring La are electrically connected via switch Wa[2]. Therefore, in the control period TS2, the potential of the upper electrode Zu[2] is set to the drive potential VH, which is the potential of the test drive signal Com-AXY in the control period TS2. Also, in the control period TS2, the potential of the upper electrode Zu[1] maintains the reference potential V0, which is the potential set in the control period TS1, and a detection potential signal VX[1] indicating the reference potential V0 is supplied to the detection circuit 33 via wiring Ls.

[0096] As shown in Figure 12, when a short circuit LK is formed between the upper electrode Zu[1] and the upper electrode Zu[2], at the start of the control period TS2 following the control period TS1 shown in Figure 10, the potential of the upper electrode Zu[1] is set to the reference potential V0, and the potential of the upper electrode Zu[2] is set to the drive potential VH. However, during the control period TS2, as a leakage current flows through the short circuit LK, the potential of the upper electrode Zu[1] changes to approach the potential of the upper electrode Zu[2]. That is, during the control period TS2, the potential of the upper electrode Zu[1] changes from the reference potential V0 to approach the drive potential VH. Therefore, during the control period TS2, the detection circuit 33 detects a detection potential signal VX[1] in which the potential changes from the reference potential V0 to approach the drive potential VH.

[0097] <<3.4. Regarding the detected potential signal VX[m] in the discharge section inspection process>> In this embodiment, the inspection unit 5 uses the detection signal SK[m] generated by the detection circuit 33 based on the detected potential signal VX[m] to determine whether the potential change of the detected potential signal VX[m] during the control period TS2 is greater than or equal to the threshold dVth. Specifically, the inspection unit 5 determines, based on the detection signal SK[m], whether the detected potential signal VX[m] during the control period TS2 is greater than or equal to the threshold potential Vth. Here, the threshold potential Vth is the potential obtained by adding the threshold dVth to the reference potential V0. If the result of the determination is negative, that is, if the amount of potential change of the detected potential signal VX[m] during the control period TS2 is less than the threshold dVth, an inspection result signal SS[m] is output that indicates a value (for example, "1") corresponding to the determination that the discharge unit D[m] has a predetermined energy storage capacity. On the other hand, if the result of the determination is positive, that is, if the amount of potential change of the detected potential signal VX[m] during the control period TS2 is greater than or equal to the threshold dVth, an inspection result signal SS[m] is output that indicates a value (for example, "0") corresponding to the determination that the discharge unit D[m] does not have a predetermined energy storage capacity.

[0098] Figure 13 shows the potential change of the upper electrode Zu[m] when the discharge section inspection process is performed using the normal inspection mode MD-X. This figure assumes that the discharge section D[m] designated as the discharge section DK to be inspected has a predetermined energy storage capacity.

[0099] As described above, the test drive signal Com-AX changes potential from the reference potential V0 to the drive potential VH during the control period TX2, and maintains the drive potential VH during the control period TX3. In other words, at time t0, when the control period TX2 ends, the potential change of the test drive signal Com-AX stops. As a result, vibration occurs in the discharge unit DD to be driven at time t0. The vibration that occurred in the discharge unit DD to be driven at time t0 propagates to the discharge unit D[m] designated as the discharge unit DK to be inspected. When the discharge unit D[m] vibrates, the piezoelectric element PZ[m] is displaced in accordance with the vibration. As a result, as shown in Figure 13, the potential of the detected potential signal VX[m] fluctuates at time t0. Subsequently, the vibration remaining in the discharge unit D[m] is attenuated, and the amplitude of the detected potential signal VX[m] is also attenuated.

[0100] In this embodiment, the inspection unit 5 inspects the state of the discharge unit D[m] based on the potential of the detected potential signal VX[m] during the control period TSX2. Specifically, the inspection unit 5 inspects the state of the discharge unit D[m] by checking whether the potential of the detected potential signal VX[m] is equal to or greater than the threshold potential Vth during the control period TSX2. In this embodiment, in the discharge unit inspection process using the normal inspection mode MD-X, it is assumed that if the discharge unit D[m] designated as the discharge unit DK to be inspected has a predetermined energy storage capacity, the slope of the waveform PA-X during the control period TX2 is set such that the amplitude dVx of the detected potential signal VX[m] is less than the threshold dVth at time t1 when the control period TSX2 starts. In other words, in this embodiment, in the discharge unit inspection process using the normal inspection mode MD-X, if the discharge unit D[m] designated as the discharge unit DK to be inspected has a predetermined energy storage capacity, it is assumed that the waveform PA-X is set so that the detected potential signal VX[m] does not exceed the threshold potential Vth during the period from time t1 when the control period TSX2 starts to time t2 when the control period TSX2 ends.

[0101] Figure 14 shows the potential change of the upper electrode Zu[m] when the discharge section inspection process is performed using the normal inspection mode MD-X. Note that this figure assumes that the discharge section D[m] designated as the discharge section DK to be inspected does not have the predetermined energy storage capacity.

[0102] As described above, in the discharge section inspection process, if the discharge section D[m] designated as the discharge section DK to be inspected does not have a predetermined energy storage capacity, the potential of the upper electrode Zu[m] during the control period TSX2 changes from the reference potential V0 to approach the drive potential VH. Therefore, in the discharge section inspection process using the normal inspection mode MD-X, if the discharge section D[m] designated as the discharge section DK to be inspected does not have a predetermined energy storage capacity, the potential of the detected potential signal VX[m] oscillates with an amplitude dVx less than the threshold dVth during the control period TSX2, as shown in Figure 14, and the amplitude center changes from the reference potential V0 to approach the drive potential VH. In this embodiment, in the discharge unit inspection process using the normal inspection mode MD-X, if the discharge unit D[m] designated as the discharge unit DK to be inspected does not have a predetermined energy storage capacity, it is assumed that the drive potential VH of the waveform PA-X is set such that the detected potential signal VX[m] is equal to or greater than the threshold potential Vth during the period from time t1 when the control period TSX2 starts to time t2 when the control period TSX2 ends. Therefore, in this embodiment, in the normal inspection mode MD-X, the inspection unit 5 can inspect the state of the discharge unit D[m] by checking whether the potential of the detected potential signal VX[m] during the control period TSX2 is equal to or greater than the threshold potential Vth.

[0103] Figure 15 shows the potential change of the upper electrode Zu[m] when the discharge section inspection process is performed using the high-speed inspection mode MD-Y. In this figure, it is assumed that the discharge section D[m] designated as the discharge section DK to be inspected has a predetermined energy storage capacity.

[0104] As described above, the test drive signal Com-AY changes potential from the reference potential V0 to the drive potential VH during the control period TY2, and maintains the drive potential VH during the control period TY3. Furthermore, the control period TY2 is shorter than the control period TX2. In other words, the slope of the waveform PA-Y of the test drive signal Com-AY during the control period TY2 is steeper than the slope of the waveform PA-X of the test drive signal Com-AX during the control period TX2. For this reason, when the discharge unit inspection process is performed using the high-speed inspection mode MD-Y, the amplitude of vibration occurring in the drive target discharge unit DD at time t3 when the control period TY2 ends is greater than the amplitude of vibration occurring in the drive target discharge unit DD at time t0 when the control period TX2 ends, when the discharge unit inspection process is performed using the normal inspection mode MD-X.

[0105] On the other hand, as described above, when the ejection unit inspection process is performed using the high-speed inspection mode MD-Y, the cavity CV of the ejection unit D[m] is not filled with ink (or is filled with a specific type of liquid with lower viscosity than ink). Therefore, when the ejection unit inspection process is performed using the high-speed inspection mode MD-Y, the vibration attenuation is greater when vibration is transmitted from the driven ejection unit DD to the ejection unit D[m] designated as the ejection unit DK to be inspected, compared to the case of the normal inspection mode MD-X. Furthermore, when the ejection unit inspection process is performed using the high-speed inspection mode MD-Y, the vibration transmitted to the ejection unit DK to be inspected is attenuated more rapidly compared to the case of the normal inspection mode MD-X. Therefore, in this embodiment, when the ejection unit inspection process is performed using the high-speed inspection mode MD-Y, the amplitude dVy of the detected potential signal VX[m] during the control period TSY2 is smaller than the amplitude dVx of the detected potential signal VX[m] during the control period TSX2 when the ejection unit inspection process is performed using the normal inspection mode MD-X. In other words, in this embodiment, when the discharge unit inspection process is performed using the high-speed inspection mode MD-Y, the amplitude dVy of the detected potential signal VX[m] during the control period TSY2 is less than the threshold dVth. That is, in this embodiment, when the discharge unit inspection process is performed using the high-speed inspection mode MD-Y, if the discharge unit D[m] designated as the discharge unit DK to be inspected has a predetermined energy storage capacity, the detected potential signal VX[m] will not be greater than or equal to the threshold potential Vth during the period from the start time t4 of the control period TSY2 to the end time t5 of the control period TSY2.

[0106] Figure 16 shows the potential change of the upper electrode Zu[m] when the discharge section inspection process is performed using the high-speed inspection mode MD-Y. In this figure, it is assumed that the discharge section D[m] designated as the discharge section DK to be inspected does not have the predetermined energy storage capacity.

[0107] As described above, in the discharge section inspection process, if the discharge section D[m] designated as the discharge section DK to be inspected does not have a predetermined energy storage capacity, the potential of the upper electrode Zu[m] during the control period TSY2 changes from the reference potential V0 to approach the drive potential VH. Therefore, in the discharge section inspection process using the high-speed inspection mode MD-Y, if the discharge section D[m] designated as the discharge section DK to be inspected does not have a predetermined energy storage capacity, the potential of the detected potential signal VX[m] oscillates with an amplitude dVy less than the threshold dVth during the control period TSY2, as shown in Figure 16, and the amplitude center changes from the reference potential V0 to approach the drive potential VH. In this embodiment, in the discharge unit inspection process using the high-speed inspection mode MD-Y, if the discharge unit D[m] designated as the discharge unit DK to be inspected does not have a predetermined energy storage capacity, it is assumed that the drive potential VH of the waveform PA-Y is set such that the detected potential signal VX[m] is equal to or greater than the threshold potential Vth during the period from time t4 when the control period TSY2 starts to time t5 when the control period TSY2 ends. Therefore, in this embodiment, in the high-speed inspection mode MD-Y, the inspection unit 5 can inspect the state of the discharge unit D[m] by checking whether the potential of the detected potential signal VX[m] during the control period TSY2 is equal to or greater than the threshold potential Vth.

[0108] In this embodiment, it is assumed that the potential set for the test drive signal Com-AX during the control period TSX2 and the potential set for the test drive signal Com-AY during the control period TSY2 are both drive potential VH, but the present invention is not limited to this embodiment. The potential set for the test drive signal Com-AX during the control period TSX2 and the potential set for the test drive signal Com-AY during the control period TSY2 may be different potentials. In this case, the potential set for the test drive signal Com-AX during the control period TSX2 should be such that, in the discharge section inspection process using the normal inspection mode MD-X, the discharge section D[m] designated as the discharge section DK to be inspected does not have a predetermined energy storage capacity, and the detected potential signal VX[m] becomes greater than or equal to the threshold potential Vth during the control period TSX2. Furthermore, the potential set by the inspection drive signal Com-AY during the control period TSY2 is such that, in the discharge section inspection process using the high-speed inspection mode MD-Y, if the discharge section D[m] designated as the discharge section DK to be inspected does not have a predetermined energy storage capacity, the detected potential signal VX[m] becomes equal to or greater than the threshold potential Vth during the control period TSY2.

[0109] In order to clarify the advantages of the discharge section inspection process according to this embodiment, the discharge section inspection process related to proportionality will be described below.

[0110] In the proportional ejection unit inspection process, regardless of whether ink is filled in the cavity CV of the ejection unit DK to be inspected and the ejection unit DD to be driven, the inspection mode MD is the same as the high-speed inspection mode MD-Y in this embodiment, where a unit inspection period TY is set as the operating period of the inkjet printer, and an inspection drive signal Com-AY is supplied to the head unit 3 as drive signal Com-A, and an inspection drive signal Com-BY is supplied as drive signal Com-B.

[0111] Figure 17 shows the potential change of the upper electrode Zu[m] when a proportional dispensing unit inspection process is performed. This figure assumes that the dispensing unit D[m] designated as the dispensing unit DK to be inspected has a predetermined energy storage capacity, and that ink is filled in both the dispensing unit DK to be inspected and the dispensing unit DD to be driven.

[0112] As described above, the control period TY2 during which the potential of the inspection drive signal Com-AY changes from the reference potential V0 to the drive potential VH is shorter than the control period TX2 during which the potential of the inspection drive signal Com-AX changes from the reference potential V0 to the drive potential VH. Therefore, when a proportional discharge unit inspection process is performed, the amplitude of vibration that occurs in the drive target discharge unit DD at time t3 when the control period TY2 ends is greater than the amplitude of vibration that occurs in the drive target discharge unit DD at time t0 when the normal inspection mode MD-X of this embodiment is performed.

[0113] On the other hand, as described above, the proportional ejection unit inspection process assumes that ink is filled in the cavity CV of the ejection unit D[m]. Therefore, when the proportional ejection unit inspection process is performed, the vibrations propagated from the driven ejection unit DD to the ejection unit D[m] designated as the ejection unit DK are greater compared to when the ejection unit inspection process using the normal inspection mode MD-X according to this embodiment is performed. Furthermore, when the proportional ejection unit inspection process is performed, the rate of vibration damping in the inspected ejection unit DK is about the same compared to when the ejection unit inspection process using the normal inspection mode MD-X according to this embodiment is performed. Therefore, when the proportional ejection unit inspection process is performed, the amplitude dVz in the control period TSY2 of the detected potential signal VX[m] is greater than the amplitude dVx in the control period TSX2 of the detected potential signal VX[m] when the ejection unit inspection process using the normal inspection mode MD-X according to this embodiment is performed. For example, when a proportional discharge unit inspection process is performed, the amplitude dVz of the detected potential signal VX[m] during the control period TSY2 will be greater than or equal to the threshold dVth. That is, in a proportional discharge unit inspection process, even if the discharge unit D[m] designated as the discharge unit DK to be inspected has a predetermined energy storage capacity, the detected potential signal VX[m] will be greater than or equal to the threshold potential Vth during the control period TSY2.

[0114] Figure 18 shows the potential change of the upper electrode Zu[m] when a proportional dispensing unit inspection process is performed. This figure assumes that the dispensing unit D[m] designated as the dispensing unit DK to be inspected does not have a predetermined energy storage capacity, and that ink is filled in both the dispensing unit DK to be inspected and the dispensing unit DD to be driven.

[0115] As described above, in the discharge section inspection process, if the discharge section D[m] designated as the discharge section DK to be inspected does not have the predetermined energy storage capacity, the potential of the upper electrode Zu[m] during the control period TSY2 changes from the reference potential V0 to approach the drive potential VH. Therefore, in the proportional discharge section inspection process, if the discharge section D[m] designated as the discharge section DK to be inspected does not have the predetermined energy storage capacity, the potential of the detected potential signal VX[m] oscillates with an amplitude dVz greater than or equal to the threshold dVth during the control period TSY2, as shown in Figure 18, and the amplitude center changes from the reference potential V0 to approach the drive potential VH. Furthermore, in the proportional discharge section inspection process, if the discharge section D[m] designated as the discharge section DK to be inspected does not have the predetermined energy storage capacity, the detected potential signal VX[m] becomes greater than or equal to the threshold potential Vth during the control period TSY2. In other words, in the proportional discharge unit inspection process, regardless of whether the discharge unit D[m] has a predetermined energy storage capacity, the detected potential signal VX[m] during the control period TSY2 will be equal to or greater than the threshold potential Vth.

[0116] <<4. Summary of this embodiment>> Thus, in the proportional discharge unit inspection process, the duration of the control period TY2 is less than or equal to the duration of the control period TY4 in the inspection drive signal Com-AY used to drive the target discharge unit DD. Therefore, regardless of whether the discharge unit D[m] has a predetermined energy storage capacity or not, the amplitude of the detected potential signal VX[m] in the control period TSY2 becomes greater than or equal to the threshold dVth, and the detected potential signal VX[m] in the control period TSY2 becomes greater than or equal to the threshold potential Vth. For this reason, it was difficult to inspect the state of the discharge unit D[m] based on the detected potential signal VX[m] in the proportional discharge unit inspection process.

[0117] In contrast, according to the present embodiment, in the ejection unit inspection process in the normal inspection mode MD-X, in the inspection drive signal Com-AX used to drive the drive target ejection unit DD, the time length of the control period TX2 is set to be longer than the time length of the control period TX4. Therefore, according to the present embodiment, in the ejection unit inspection process in the normal inspection mode MD-X, when the ejection unit D[m] has a predetermined power storage capacity, it is possible to suppress the detected potential signal VX[m] in the control period TSX2 from becoming a potential equal to or higher than the threshold potential Vth, and only when the ejection unit D[m] does not have a predetermined power storage capacity, the detected potential signal VX[m] in the control period TSX2 can be set to a potential equal to or higher than the threshold potential Vth. As a result, according to the present embodiment, it is possible to suppress the possibility that the inspection accuracy of the ejection unit inspection process decreases due to vibrations propagating from the drive target ejection unit DD.

[0118] Further, according to the present embodiment, in addition to the ejection unit inspection process in the normal inspection mode MD-X, an ejection unit inspection process in the high-speed inspection mode MD-Y is possible. Therefore, compared with a mode in which only the ejection unit inspection process in the normal inspection mode MD-X is possible, when the cavity CV of the ejection unit D[m] is not filled with ink (or when a specific type of liquid having a lower viscosity than ink is filled), it is possible to shorten the execution time of the ejection unit inspection process.

[0119] <<B. Modification Example>> Each of the above embodiments can be variously modified. Specific modification modes are exemplified below. Two or more modes arbitrarily selected from the following examples can be appropriately combined within a range where they do not conflict with each other. In the modification examples exemplified below, for elements whose actions and functions are equivalent to those of the embodiment, the reference numerals referred to in the above description are used, and the detailed description of each is appropriately omitted.

[0120] <<Modification Example 1>> In the above-described embodiment, the case where the drive target ejection unit DD is a different ejection unit D from the inspection target ejection unit DK has been exemplified and described, but the present invention is not limited to such a mode. The drive target ejection unit DD may be the same ejection unit D as the inspection target ejection unit DK.

[0121] Figure 19 is an explanatory diagram showing an example of the operation of the connection state specification circuit 310 in this modified example during the unit inspection period TXY (unit inspection period TX or unit inspection period TY).

[0122] As shown in Figure 19, the individual designation signal Sd[m] in this modified example can take one of two values ​​during the unit inspection period TXY in which the discharge unit inspection process is performed: a value of "6" which designates the discharge unit D[m] as the discharge unit DK to be inspected, and a value of "7" which designates the discharge unit D[m] as the standby discharge unit DW.

[0123] In this modified example, we assume that the discharge unit DK to be inspected is both driven and inspected during the discharge unit inspection process. That is, in this modified example, the discharge unit DK to be inspected performs the role of the discharge unit DK to be inspected according to the embodiment, as well as the role of the driven discharge unit DD according to the embodiment.

[0124] As shown in Figure 19, in this modified example, when the individual designation signal Sd[m] indicates a value of "6" which designates the discharge unit D[m] as the discharge unit DK to be inspected during the unit inspection period TXY, the connection state designation circuit 310 maintains the connection state designation signal Qa[m] at a high level during control periods TS1 and TS3, and maintains the connection state designation signal Qs[m] at a high level during control period TS2. In this case, the switch Wa[m] is turned on during control periods TS1 and TS3, and the switch Ws[m] is turned on during control period TS2. Therefore, during control period TS1, the discharge unit D[m] is driven by the inspection drive signal Com-AXY (inspection drive signal Com-AX or inspection drive signal Com-AY) having waveform PA-XY (waveform PA-X or waveform PA-Y), and the potential of the upper electrode Zu[m] of the discharge unit D[m] changes from the reference potential V0 to the drive potential VH. Then, during the control period TS2 (control period TSX2 or control period TSY2), the detection circuit 33 detects the potential of the upper electrode Zu[m] of the discharge unit D[m] as a detection potential signal VX[m] via the switch Ws[m]. Furthermore, if the individual designation signal Sd[m] indicates a value of "7" which designates the discharge unit D[m] as the standby discharge unit DW during the unit inspection period TXY, the connection status designation circuit 310 maintains the connection status designation signal Qb[m] at a high level throughout the unit inspection period TXY. In this case, the potential of the discharge unit D[m] during the control period TS2 (control period TSX2 or control period TSY2) is set to the reference potential V0.

[0125] In this modified example, it is assumed that in each unit inspection period TXY, one of the M discharge units D[1] to D[M] is designated as the discharge unit DK to be inspected, and the remaining (M-1) discharge units D are designated as the standby discharge units DW.

[0126] In this modified example, if the discharge unit D[m] driven as the discharge unit DK to be inspected has a predetermined energy storage capacity, the potential of the upper electrode Zu[m] during the control period TS2 is maintained at the drive potential VH. On the other hand, in this modified example, if the discharge unit D[m] driven as the discharge unit DK to be inspected does not have a predetermined energy storage capacity, that is, if a short circuit LK exists between the upper electrode Zu[m] of the discharge unit D[m] designated as the discharge unit DK to be inspected and the upper electrode Zu of the discharge unit D designated as the standby discharge unit DW, the potential of the upper electrode Zu[m] during the control period TS2 changes from the drive potential VH to approach the reference potential V0. Therefore, in this modified example, the detection circuit 33 can check whether the discharge unit D[m] has a predetermined energy storage capacity by determining, based on the detection signal SK[m], whether the amount of potential change of the detection potential signal VX[m] during the control period TS2 is less than the threshold potential Vth.

[0127] <<Modification 2>> In the embodiments and modification 1 described above, when the ejection unit inspection process is performed using the normal inspection mode MD-X, the head unit 3 is supplied with an inspection drive signal Com-AX as the drive signal Com-A. However, the present invention is not limited to this embodiment. For example, when the ejection unit inspection process is performed using the normal inspection mode MD-X, the head unit 3 may be supplied with a signal having a different waveform from the inspection drive signal Com-AX as the drive signal Com-A.

[0128] Figure 20 is a timing chart showing an example of various signals, such as the drive signal Com, supplied to the head unit 3 during the unit inspection period TX and unit inspection period TY in this modified example.

[0129] As shown in Figure 20, this modified example differs from the discharge unit inspection process according to the embodiment in that, when the discharge unit inspection process is performed, the head unit 3 is supplied with an inspection drive signal Com-AW instead of an inspection drive signal Com-AX.

[0130] As shown in Figure 20, the test drive signal Com-AW has a waveform PA-W provided for the unit test period TX. Here, the waveform PA-W is a waveform in which, during the unit test period TX, the reference potential V0 is maintained during the control period TX1, the potential changes from the reference potential V0 to the drive potential VH during the control period TX2w following the control period TX1, the drive potential VH is maintained during the control period TX3w following the control period TX2w, the potential changes from the drive potential VH to the reference potential V0 during the control period TX4 following the control period TX3w, and the reference potential V0 is maintained during the control period TX5 following the control period TX4. Of these, the control period TX2w is included in the control period TSX1, starts after the beginning of control period TSX1, and ends before the end of control period TSX1. In this modified example, the length of the control period TX2w is the same as the length of the control period TY2. Furthermore, the control period TX3w includes a portion of the control period TSX1, all of the control period TSX2, and a portion of the control period TSX3, and begins after the start of the control period TSX1 and before the start of the control period TSX2, and ends after the end of the control period TSX2 and before the end of the control period TSX3. In other words, in this modified example, the control period TSX2 is included in the control period TX3w. Also, in this modified example, the duration of the control period TX3w is longer than the duration of the control period TY3. Specifically, the interval dTHw from the start of the control period TX3w to the start of the control period TSX2 is longer than the interval dTHv from the start of the control period TY3 to the start of the control period TSY2.

[0131] Thus, according to this modified version, the interval dTHw from when the discharge unit DD to be driven is driven by the inspection drive signal Com-AW used in the normal inspection mode MD-X until the detection circuit 33 starts detecting the detection potential signal VX[m] from the discharge unit DK to be inspected is longer than the interval dTHv from when the discharge unit DD to be driven is driven by the inspection drive signal Com-AY used in the high-speed inspection mode MD-Y until the detection circuit 33 starts detecting the detection potential signal VX[m] from the discharge unit DK to be inspected. Therefore, according to this modified version, for example, compared to a proportional discharge unit inspection process, it is possible to attenuate the amplitude of vibrations in the detection potential signal VX[m] caused by vibrations propagating from the discharge unit DD to the discharge unit DK to be inspected more significantly. As a result, according to this modified version, it is possible to suppress the possibility that the inspection accuracy of the discharge unit inspection process will decrease due to vibrations propagating from the discharge unit DD to be driven.

[0132] <<Modification 3>> In the embodiments and modifications 1 and 2 described above, the case in which the inkjet printer 1 can perform ejection unit inspection processing using two inspection modes MD, a normal inspection mode MD-X and a high-speed inspection mode MD-Y, was explained as an example, but the present invention is not limited to such embodiments. The inkjet printer 1 only needs to be able to perform ejection unit inspection processing using at least the normal inspection mode MD-X.

[0133] <<Modification Example 4>> In the above-described embodiments, modification examples 2 and 3, the case where the inspection target ejection unit DK and the drive target ejection unit DD are adjacent ejection units D to each other has been illustrated and described. However, the present invention is not limited to such a mode. The inspection target ejection unit DK and the drive target ejection unit DD may be ejection units D that are not adjacent to each other.

[0134] <<Modification Example 5>> In the above-described embodiments and modification examples 1 to 4, the case where the inkjet printer 1 includes four head units 3 has been assumed. However, the present invention is not limited to such a mode. The inkjet printer 1 may include one or more and three or less head units 3, or may include five or more head units 3.

[0135] <<Modification Example 6>> In the above-described embodiments and modification examples 1 to 5, the case where the inkjet printer 1 is a serial printer has been illustrated. However, the present invention is not limited to such a mode. The inkjet printer 1 may be a so-called line printer in which a plurality of nozzles N are provided in the head unit 3 so as to extend wider than the width of the recording paper PP.

[0136] <<C. Supplementary Note>> Aspects related to the above embodiments and modification examples are appended below. In order to facilitate the understanding of each aspect, in the following, the description will be made with reference numerals of the drawings appended, but the present invention is not intended to be limited to the illustrated aspects.

[0137] <<C.1. Supplementary Note 1>> Hereinafter, Supplementary Note 1 will be described. In the following, the variable m1 is a natural number satisfying "1 ≤ m1 ≤ M", and the variable m2 is a natural number satisfying "1 ≤ m2 ≤ M" and "m1 ≠ m2".

[0138] <<Supplementary Note 1-1>> The inkjet printer 1 described in Appendix 1-1 comprises an inspection target ejection unit DK equipped with a piezoelectric element PZ[m1] that displaces in accordance with a drive signal Com, and capable of ejecting ink in accordance with the displacement of the piezoelectric element PZ[m1], and an inspection target ejection unit DD equipped with a piezoelectric element PZ[m2] that displaces in accordance with a drive signal Com, and capable of ejecting ink in accordance with the displacement of the piezoelectric element PZ[m2], and an inspection unit that, when a drive signal Com (more specifically, an inspection drive signal Com-AX) is supplied to the piezoelectric element PZ[m2] during a unit inspection period TX, inspects the state of the inspection target ejection unit DK based on a detection signal SK[m1] corresponding to the potential of the piezoelectric element PZ[m1] during a control period TSX2 included in the unit inspection period TX. The unit 5 comprises a drive signal Com that maintains a reference potential V0 during the control period TX1 of the unit inspection period TX, changes potential from the reference potential V0 to a drive potential VH during the control period TX2 following the control period TX1 of the unit inspection period TX, maintains the drive potential VH during the control period TX3 following the control period TX2 of the unit inspection period TX, changes potential from the drive potential VH to a reference potential V0 during the control period TX4 following the control period TX3 of the unit inspection period TX, maintains the reference potential V0 during the control period TX5 following the control period TX4 of the unit inspection period TX, the control period TX3 includes the control period TSX2, and the control period TX2 is longer than the control period TX4. In Note 1, piezoelectric element PZ[m1] is an example of a "first piezoelectric element", piezoelectric element PZ[m2] is an example of a "second piezoelectric element", the discharge unit DK to be inspected is an example of a "first discharge unit", the discharge unit DD to be driven is an example of a "second discharge unit", the inspection unit 5 is an example of an "inspection unit", the unit inspection period TX is an example of a "unit period", the control period TSX2 is an example of an "inspection period", the control period TX1 is an example of a "first period", the control period TX2 is an example of a "second period", the control period TX3 is an example of a "third period", the control period TX4 is an example of a "fourth period", the control period TX5 is an example of a "fifth period", the reference potential V0 is an example of a "first potential", and the drive potential VH is an example of a "second potential".

[0139] According to Appendix 1-1, since the control period TX2 is longer than the control period TX4, vibrations occurring in the driven discharge unit DD at the end of the control period TX2 can be suppressed, thus reducing noise superimposed on the detection signal SK[m1] due to vibrations propagating from the driven discharge unit DD to the inspected discharge unit DK. Also, according to Appendix 1-1, since the control period TX4 is shorter than the control period TX2, the length of the unit inspection period TX required for inspecting the state of the inspected discharge unit DK can be shortened.

[0140] <<Note 1-2>> The inkjet printer 1 described in Appendix 1-2 is the same as the inkjet printer 1 described in Appendix 1-1, characterized in that, during the unit inspection period TX, the inspection target ejection unit DK and the drive target ejection unit DD are filled with ink.

[0141] According to Appendix 1-2, since the inspection of the state of the inspection target ejector DK is performed with ink filled in the inspection target ejector DK and the drive target ejector DD, the effort required to switch between image formation by ink ejection from the inkjet printer 1 and inspection of the inspection target ejector DK can be reduced compared to the method of inspecting the state of the inspection target ejector DK when the inspection target ejector DK and the drive target ejector DD are not filled with ink.

[0142] <<Notes 1-3>> The inkjet printer 1 according to Appendix 1-3 is an inkjet printer 1 according to Appendix 1-1 or Appendix 1-2, characterized in that the flow path provided in the inspection target ejection unit DK and the flow path provided in the drive target ejection unit DD are in communication with a common liquid chamber 327 for storing ink.

[0143] According to Appendix 1-3, vibrations generated in the discharge unit DD, which is the target of driving, in response to the driving of the discharge unit DD by the drive signal Com, are propagated to the discharge unit DK, the target of inspection, via the common liquid chamber 327. However, since the control period TX2 is longer than the control period TX4, vibrations generated in the discharge unit DD are suppressed, thus reducing the noise superimposed on the detection signal SK[m1] due to vibrations propagated from the discharge unit DD to the discharge unit DK, the target of inspection.

[0144] <<Notes 1-4>> The inkjet printer 1 described in Appendix 1-4 comprises an inspection target ejection unit DK that is equipped with a piezoelectric element PZ[m1] that displaces in accordance with a drive signal Com and is capable of ejecting ink in accordance with the displacement of the piezoelectric element PZ[m1], and an inspection unit 5 that, when a drive signal Com (more specifically, an inspection drive signal Com-AX) is supplied to the piezoelectric element PZ[m1] during a control period TSX1 included in the unit inspection period TX, inspects the state of the inspection target ejection unit DK based on a detection signal SK[m1] corresponding to the potential of the piezoelectric element PZ[m1] during a control period TSX2 included in the unit inspection period TX, wherein the drive signal Com is a reference potential during the control period TX1 of the unit inspection period TX The following characteristics are observed: V0 is maintained; in control period TX2 following control period TX1 within the unit inspection period TX, the potential changes from reference potential V0 to driving potential VH; in control period TX3 following control period TX2 within the unit inspection period TX, the driving potential VH is maintained; in control period TX4 following control period TX3 within the unit inspection period TX, the potential changes from driving potential VH to reference potential V0; and in control period TX5 following control period TX4 within the unit inspection period TX, the reference potential V0 is maintained; control period TX3 includes control period TSX2; control period TSX1 does not include control period TSX2 but includes at least control period TX2, and control period TX2 is longer than control period TX4. Note 1: In this document, the control period TSX1 is an example of a "drive period".

[0145] According to Appendix 1-1, since the control period TX2 is longer than the control period TX4, vibrations occurring in the discharge unit DK under inspection at the end of the control period TX2 can be suppressed, thereby reducing noise superimposed on the detection signal SK[m1] due to vibrations occurring in the discharge unit DK under inspection. Also, according to Appendix 1-1, since the control period TX4 is shorter than the control period TX2, the length of the unit inspection period TX required for inspecting the state of the discharge unit DK under inspection can be shortened.

[0146] <<Appendix 1-5>> The inkjet printer 1 described in Appendix 1-5 is the inkjet printer 1 described in Appendix 1-1 to Appendix 1-4, and the inspection unit 5 is characterized in that, if the potential change of the piezoelectric element PZ[m1] during the control period TSX2 is greater than or equal to the threshold dVth, it outputs an inspection result signal SS[m] indicating that the state of the ejection unit DK to be inspected is not normal. In Note 1, the threshold dVth is an example of a "reference quantity," and the test result signal SS[m] is an example of a "test result."

[0147] According to Appendix 1-5, it becomes possible to check whether the piezoelectric element PZ[m1] has a predetermined energy storage capacity based on the potential change of the piezoelectric element PZ[m1] during the control period TSX2.

[0148] <<Notes 1-6>> The inkjet printer 1 according to Supplementary Note 1-6 includes a piezoelectric element PZ[m1] that is displaced in response to a drive signal Com, and an inspection target ejection unit DK that can eject ink in response to the displacement of the piezoelectric element PZ[m1]; a piezoelectric element PZ[m2] that is displaced in response to a drive signal Com, and a drive target ejection unit DD that can eject ink in response to the displacement of the piezoelectric element PZ[m2]; and an inspection unit 5 that inspects the state of the inspection target ejection unit DK based on a detection signal SK[m1] corresponding to the potential of the piezoelectric element PZ[m1] in a control period TSX2 included in a unit inspection period TX when a drive signal Com (more specifically, an inspection drive signal Com-AX) is supplied to the piezoelectric element PZ[m2] in the unit inspection period TX. The drive signal Com changes in potential from a reference potential V0 to a drive potential VH in a control period TX2 within the unit inspection period TX, maintains the drive potential VH in a control period TX3 following the control period TX2 within the unit inspection period TX, changes in potential from the drive potential VH to the reference potential V0 in a control period TX4 following the control period TX3 within the unit inspection period TX. The control period TX3 includes the control period TSX2, and the control period TX2 is longer than the control period TX4. In Supplementary Note 1, the control period TX2 is an example of a "first transition period", the control period TX3 is an example of a "maintenance period", and the control period TX4 is an example of a "second transition period".

[0149] <<C.2. Supplementary Note 2>> The following describes Supplementary Note 2. In Supplementary Note 2, the control period TX1 and the control period TY1 may be referred to as a control period TXY1, the control period TX2 and the control period TY2 may be referred to as a control period TXY2, the control period TX3 and the control period TY3 may be referred to as a control period TXY3, the control period TX4 and the control period TY4 may be referred to as a control period TXY4, and the control period TX5 and the control period TY5 may be referred to as a control period TXY5.

[0150] <<Supplementary Note 2-1>> The inkjet printer 1 described in Appendix 2-1 comprises: an inspection target ejection unit DK equipped with a piezoelectric element PZ[m1] that displaces in accordance with a drive signal Com, and capable of ejecting ink in accordance with the displacement of the piezoelectric element PZ[m1]; a drive target ejection unit DD equipped with a piezoelectric element PZ[m2] that displaces in accordance with a drive signal Com, and capable of ejecting ink in accordance with the displacement of the piezoelectric element PZ[m2]; and an inspection unit 5 that, when a drive signal Com (more specifically, an inspection drive signal Com-AXY) is supplied to the piezoelectric element PZ[m2] during a unit inspection period TXY, inspects the state of the inspection target ejection unit DK based on a detection signal SK[m1] corresponding to the potential of the piezoelectric element PZ[m1] during a control period TS2 included in the unit inspection period TXY; the inspection unit 5 includes a normal inspection mode MD-X that inspects the state of the inspection target ejection unit DK when the inspection target ejection unit DK and the drive target ejection unit DD are filled with ink; and a mode that inspects the state of the inspection target ejection unit DK in a shorter time than the normal inspection mode MD-X. The system allows inspection of the discharge unit DK to be inspected using multiple inspection modes MD, including the high-speed inspection mode MD-Y. The drive signal Com maintains a reference potential V0 during the control period TXY1 of the unit inspection period TXY, changes potential from the reference potential V0 to the drive potential VH during the control period TXY2 following the control period TXY1 of the unit inspection period TXY, maintains the drive potential VH during the control period TXY3 following the control period TXY2 of the unit inspection period TXY, changes potential from the drive potential VH to the reference potential V0 during the control period TXY4 following the control period TXY3 of the unit inspection period TXY, maintains the reference potential V0 during the control period TXY5 following the control period TXY4 of the unit inspection period TXY, and the control period TXY3 includes the control period TS2. The duration of the control period TXY2 (i.e., control period TX2) in the normal inspection mode MD-X is longer than the duration of the control period TXY2 (i.e., control period TY2) in the high-speed inspection mode MD-Y. In addition, in Appendix 2, piezoelectric element PZ[m1] is an example of the "first piezoelectric element", piezoelectric element PZ[m2] is an example of the "second piezoelectric element", the discharge unit DK to be inspected is an example of the "first discharge unit", the discharge unit DD to be driven is an example of the "second discharge unit", the inspection unit 5 is an example of the "inspection unit", the normal inspection mode MD-X is an example of the "first inspection mode", the high-speed inspection mode MD-Y is an example of the "second inspection mode", the unit inspection period TXY is an example of the "unit period", the control period TS2 is an example of the "inspection period", the control period TXY1 is an example of the "first period", the control period TXY2 is an example of the "second period", the control period TXY3 is an example of the "third period", the control period TXY4 is an example of the "fourth period", the control period TXY5 is an example of the "fifth period", the reference potential V0 is an example of the "first potential", and the drive potential VH is an example of the "second potential".

[0151] When the target ejector unit DD is driven by the drive signal Com, vibration occurs in the target ejector unit DD. Furthermore, when the target ejector unit DD is filled with ink, the vibration generated in the target ejector unit DD persists for a longer period compared to when it is not filled. In addition, when the target ejector unit DD is driven by the drive signal Com, and both the target ejector unit DD and the target ejector unit DK are filled with ink, stronger vibrations are transmitted from the target ejector unit DD to the target ejector unit DK compared to when they are not filled. As a result, when both the target ejector unit DD and the target ejector unit DK are filled with ink, noise is superimposed on the detection signal SK[m1] due to the vibrations transmitted from the target ejector unit DD to the target ejector unit DK. This sometimes reduced the inspection accuracy of the target ejector unit DK based on the detection signal SK[m1] during the ejector unit inspection process. In contrast, according to Appendix 2-1, when the drive target ejector unit DD and the inspection target ejector unit DK are filled with ink, it is possible to perform ejector unit inspection processing using the normal inspection mode MD-X with a long control period TXY2. Therefore, according to Appendix 2-1, compared to the configuration in which only ejector unit inspection processing using the high-speed inspection mode MD-Y is possible, vibrations transmitted from the drive target ejector unit DD to the inspection target ejector unit DK can be reduced, and the inspection accuracy of the inspection target ejector unit DK in the ejector unit inspection processing can be improved. Furthermore, according to Appendix 2-1, since the discharge section inspection process can be performed using the high-speed inspection mode MD-Y, which allows for inspection in a shorter time than the normal inspection mode MD-X, if the vibrations transmitted from the driven discharge section DD to the inspected discharge section DK are small, the discharge section inspection process can be performed in a short time.

[0152] <<Note 2-2>> The inkjet printer 1 relating to Appendix 2-2 is the same as the inkjet printer 1 relating to Appendix 2-1, characterized in that the high-speed inspection mode MD-Y is an inspection mode MD that inspects the state of the ejection unit DK when the ejection unit DK and the ejection unit DD to be driven are not filled with ink.

[0153] According to Appendix 2-2, when the target ejector unit DD is not filled with ink, the ejector unit inspection process is performed using the high-speed inspection mode MD-Y, in which the control period TXY2 is set to a short value. When the target ejector unit DD is not filled with ink, compared to when the target ejector unit DD is filled with ink, the vibrations generated in the target ejector unit DD when it is driven by the drive signal Com disappear in a short time. Therefore, the decrease in inspection accuracy of the ejector unit inspection process caused by vibrations propagating from the target ejector unit DD to the target ejector unit DK can be suppressed. Thus, according to Appendix 2-2, it is possible to achieve both the suppression of the decrease in inspection accuracy of the ejector unit inspection process and the acceleration of the ejector unit inspection process.

[0154] <<Note 2-3>> The inkjet printer 1 described in Appendix 2-3 is the same as the inkjet printer 1 described in Appendix 2-1, characterized in that the normal inspection mode MD-X is an inspection mode MD that inspects the state of the ejection unit DK when the ejection unit DK and the drive target ejection unit DD are filled with ink, and the high-speed inspection mode MD-Y is an inspection mode MD that inspects the state of the ejection unit DK when the ejection unit DK and the drive target ejection unit DD are filled with a specific type of liquid with a lower viscosity than ink. In addition, in Appendix 2, ink is an example of a "Type 1 liquid," and specific types of liquids are an example of a "Type 2 liquid."

[0155] According to Appendix 2-3, when the target ejector unit DD is filled with high-viscosity ink, the ejector unit inspection process is performed using the normal inspection mode MD-X with a long control period TXY2. When the target ejector unit DD is filled with a specific type of low-viscosity liquid, the ejector unit inspection process is performed using the high-speed inspection mode MD-Y with a short control period TXY2. Therefore, according to Appendix 2-3, when the target ejector unit DD is filled with high-viscosity ink and vibrations generated in the target ejector unit DD persist for a long time, the vibrations generated in the target ejector unit DD are suppressed, and the decrease in inspection accuracy of the ejector unit inspection process caused by vibrations propagating from the target ejector unit DD to the target ejector unit DK is suppressed. On the other hand, when the target ejector unit DD is filled with a specific type of low-viscosity liquid and vibrations generated in the target ejector unit DD disappear in a short time, priority is given to speeding up the ejector unit inspection process rather than suppressing vibrations generated in the target ejector unit DD. Therefore, according to Appendix 2-3, it is possible to achieve both the suppression of a decrease in the inspection accuracy of the discharge part inspection process and the acceleration of the discharge part inspection process.

[0156] <<Note 2-4>> The inkjet printer 1 described in Appendix 2-4 comprises a test target ejection unit DK equipped with a piezoelectric element PZ[m1] that displaces in accordance with a drive signal Com, and capable of ejecting ink in accordance with the displacement of the piezoelectric element PZ[m1], and an inspection unit 5 that, when a drive signal Com (more specifically, an inspection drive signal Com-AXY) is supplied to the piezoelectric element PZ[m1] during a control period TS1 included in the unit inspection period TXY, inspects the state of the test target ejection unit DK based on a detection signal SK[m1] corresponding to the potential of the piezoelectric element PZ[m1] during a control period TS2 included in the unit inspection period TXY, wherein the inspection unit 5 is capable of inspecting the test target ejection unit DK using multiple inspection modes MD, including a normal inspection mode MD-X that inspects the state of the test target ejection unit DK when the test target ejection unit DK is filled with ink, and a high-speed inspection mode MD-Y that inspects the state of the test target ejection unit DK in a shorter time than the normal inspection mode MD-X. The drive signal Com maintains a reference potential V0 during the control period TXY1 of the unit inspection period TXY, changes potential from the reference potential V0 to the drive potential VH during the control period TXY2 following the control period TXY1 of the unit inspection period TXY, maintains the drive potential VH during the control period TXY3 following the control period TXY2 of the unit inspection period TXY, changes potential from the drive potential VH to the reference potential V0 during the control period TXY4 following the control period TXY3 of the unit inspection period TXY, maintains the reference potential V0 during the control period TXY5 following the control period TXY4 of the unit inspection period TXY, the control period TXY3 includes the control period TS2, the control period TS1 does not include the control period TS2 but includes at least the control period TXY2, and the duration of the control period TXY2 (i.e., control period TX2) in the normal inspection mode MD-X is longer than the duration of the control period TXY2 (i.e., control period TY2) in the high-speed inspection mode MD-Y. Note 2 states that the control period TS1 is an example of a "drive period".

[0157] According to Appendix 2-4, when the dispensing unit DK to be inspected is filled with ink, it is possible to perform dispensing unit inspection processing using the normal inspection mode MD-X with a long control period TXY2. Therefore, according to Appendix 2-4, compared to a configuration in which only dispensing unit inspection processing using the high-speed inspection mode MD-Y is possible, vibrations occurring in the dispensing unit DK to be inspected can be reduced, and the inspection accuracy of the dispensing unit DK to be inspected during the dispensing unit inspection process can be improved. Furthermore, according to Appendix 2-4, since the discharge section inspection process can be performed using the high-speed inspection mode MD-Y, which allows for inspection in a shorter time than the normal inspection mode MD-X, the discharge section inspection process can be performed in a short time if the vibrations occurring in the discharge section DK to be inspected are small.

[0158] <<Note 2-5>> The inkjet printer 1 described in Appendix 2-5 is the inkjet printer 1 described in Appendix 2-1 to Appendix 2-4, characterized in that the inspection unit 5 outputs an inspection result signal SS[m] indicating that the state of the inspection target ejection unit DK is not normal when the potential change of the piezoelectric element PZ[m1] during the control period TS2 is greater than or equal to the threshold dVth. In Note 2, the threshold dVth is an example of a "reference quantity," and the test result signal SS[m] is an example of a "test result."

[0159] According to Appendix 2-5, it becomes possible to check whether the piezoelectric element PZ[m1] has a predetermined energy storage capacity based on the potential change of the piezoelectric element PZ[m1] during the control period TS2.

[0160] <<Note 2-6>> The inkjet printer 1 described in Appendix 2-6 comprises: an inspection target ejection unit DK equipped with a piezoelectric element PZ[m1] that displaces in accordance with a drive signal Com, and capable of ejecting ink in accordance with the displacement of the piezoelectric element PZ[m1]; a drive target ejection unit DD equipped with a piezoelectric element PZ[m2] that displaces in accordance with a drive signal Com, and capable of ejecting ink in accordance with the displacement of the piezoelectric element PZ[m2]; and an inspection unit 5 that, when a drive signal Com (more specifically, an inspection drive signal Com-AXY) is supplied to the piezoelectric element PZ[m2] during a unit inspection period TXY, inspects the state of the inspection target ejection unit DK based on a detection signal SK[m1] corresponding to the potential of the piezoelectric element PZ[m1] during a control period TS2 included in the unit inspection period TXY, wherein the inspection unit 5 inspects the state of the inspection target ejection unit DK when the inspection target ejection unit DK and the drive target ejection unit DD are filled with ink. The system allows inspection of the target discharge unit DK using multiple inspection modes MD, including a normal inspection mode MD-X and a high-speed inspection mode MD-Y that inspects the state of the target discharge unit DK in a shorter time than the normal inspection mode MD-X. The drive signal Com changes potential from a reference potential V0 to a drive potential VH during the control period TXY2 of the unit inspection period TXY, maintains the drive potential VH during the control period TXY3 following the control period TXY2 of the unit inspection period TXY, and changes potential from a drive potential VH to a reference potential V0 during the control period TXY4 following the control period TXY3 of the unit inspection period TXY. The control period TXY3 includes the control period TS2, and the duration of the control period TXY2 in the normal inspection mode MD-X (i.e., the control period TX2) is longer than the duration of the control period TXY2 in the high-speed inspection mode MD-Y (i.e., the control period TY2). In Note 2, control period TXY2 is an example of a "first transition period," control period TXY3 is an example of a "maintenance period," and control period TXY4 is an example of a "second transition period." [Explanation of symbols]

[0161] 1... Inkjet printer, 2... Control unit, 3... Head unit, 4... Drive signal generation unit, 5... Inspection unit, 31... Supply circuit, 32... Recording head, 33... Detection circuit, D... Ejector, PZ... Piezoelectric element.

Claims

1. A first discharge unit comprising a first piezoelectric element that displaces in accordance with a drive signal, and capable of discharging liquid in accordance with the displacement of the first piezoelectric element, A second discharge unit comprising a second piezoelectric element that displaces in accordance with the drive signal, and capable of discharging liquid in accordance with the displacement of the second piezoelectric element, When the drive signal is supplied to the second piezoelectric element during a unit period, An inspection unit that inspects the state of the first discharge unit based on a detection signal corresponding to the potential of the first piezoelectric element during the inspection period included in the unit period, Equipped with, The aforementioned drive signal is During the first period of the aforementioned unit period, the first potential is maintained. In the second period following the first period within the aforementioned unit period, the potential changes from the first potential to the second potential. In the third period following the second period within the aforementioned unit period, the second potential is maintained. In the fourth period following the third period within the aforementioned unit period, the potential changes from the second potential to the first potential. In the fifth period following the fourth period of the aforementioned unit period, the first potential is maintained. The aforementioned third period includes the inspection period, The second period is longer than the fourth period. A liquid dispensing device characterized by the following features.

2. During the aforementioned unit period, the first dispensing section and the second dispensing section are filled with liquid. The liquid dispensing device according to claim 1, characterized in that...

3. The flow path provided in the first discharge section and the flow path provided in the second discharge section are in communication with a common liquid chamber for storing liquid. The liquid dispensing device according to claim 2, characterized in that

4. A first discharge unit comprising a first piezoelectric element that displaces in accordance with a drive signal, and capable of discharging liquid in accordance with the displacement of the first piezoelectric element, When the drive signal is supplied to the first piezoelectric element during the drive period included in the unit period, An inspection unit that inspects the state of the first discharge unit based on a detection signal corresponding to the potential of the first piezoelectric element during the inspection period included in the unit period, Equipped with, The aforementioned drive signal is During the first period of the aforementioned unit period, the first potential is maintained. In the second period following the first period within the aforementioned unit period, the potential changes from the first potential to the second potential. In the third period following the second period within the aforementioned unit period, the second potential is maintained. In the fourth period following the third period within the aforementioned unit period, the potential changes from the second potential to the first potential. In the fifth period following the fourth period of the aforementioned unit period, the first potential is maintained. The aforementioned third period includes the inspection period, The aforementioned driving period does not include the aforementioned inspection period, but includes at least the aforementioned second period. The second period is longer than the fourth period. A liquid dispensing device characterized by the following features.

5. A first discharge unit comprising a first piezoelectric element that displaces in accordance with a drive signal, and capable of discharging liquid in accordance with the displacement of the first piezoelectric element, A second discharge unit comprising a second piezoelectric element that displaces in accordance with the drive signal, and capable of discharging liquid in accordance with the displacement of the second piezoelectric element, When the drive signal is supplied to the second piezoelectric element during a unit period, An inspection unit that inspects the state of the first discharge unit based on a detection signal corresponding to the potential of the first piezoelectric element during the inspection period included in the unit period, Equipped with, The aforementioned drive signal is During the first transition period of the aforementioned unit period, the potential changes from the first potential to the second potential. During the maintenance period following the first transition period within the aforementioned unit period, the second potential is maintained. During the second transition period following the maintenance period within the aforementioned unit period, the potential changes from the second potential to the first potential. The aforementioned maintenance period includes the aforementioned inspection period, The first transition period is longer than the second transition period. A liquid dispensing device characterized by the following features.

6. The inspection unit outputs an inspection result indicating that the state of the first discharge unit is not normal if the amount of change in the potential of the first piezoelectric element during the inspection period is greater than or equal to a standard amount. A liquid dispensing device according to any one of claims 1 to 5, characterized in that...

7. A first discharge unit comprising a first piezoelectric element that displaces in accordance with a drive signal, and capable of discharging liquid in accordance with the displacement of the first piezoelectric element, A second discharge unit comprising a second piezoelectric element that displaces in accordance with the drive signal, and capable of discharging liquid in accordance with the displacement of the second piezoelectric element, When the drive signal is supplied to the second piezoelectric element during a unit period, A detection unit for detecting the potential of the first piezoelectric element during the inspection period included in the unit period, Equipped with, The aforementioned drive signal is During the first period of the aforementioned unit period, the first potential is maintained. In the second period following the first period within the aforementioned unit period, the potential changes from the first potential to the second potential. In the third period following the second period within the aforementioned unit period, the second potential is maintained. In the fourth period following the third period within the aforementioned unit period, the potential changes from the second potential to the first potential. In the fifth period following the fourth period of the aforementioned unit period, the first potential is maintained. The aforementioned third period includes the inspection period, The second period is longer than the fourth period. A head unit characterized by the following features.

8. During the aforementioned unit period, the first dispensing section and the second dispensing section are filled with liquid. The head unit according to claim 7, characterized in that

9. The flow path provided in the first discharge section and the flow path provided in the second discharge section are in communication with a common liquid chamber for storing liquid. The head unit according to claim 8, characterized in that

10. A first discharge unit comprising a first piezoelectric element that displaces in accordance with a drive signal, and capable of discharging liquid in accordance with the displacement of the first piezoelectric element, When the drive signal is supplied to the first piezoelectric element during the drive period included in the unit period, A detection unit for detecting the potential of the first piezoelectric element during the inspection period included in the aforementioned unit period, Equipped with, The aforementioned drive signal is During the first period of the aforementioned unit period, the first potential is maintained. In the second period following the first period within the aforementioned unit period, the potential changes from the first potential to the second potential. In the third period following the second period within the aforementioned unit period, the second potential is maintained. In the fourth period following the third period within the aforementioned unit period, the potential changes from the second potential to the first potential. In the fifth period following the fourth period of the aforementioned unit period, the first potential is maintained. The aforementioned third period includes the inspection period, The aforementioned driving period does not include the aforementioned inspection period, but includes at least the aforementioned second period. The second period is longer than the fourth period. A head unit characterized by the following features.

11. A first discharge unit comprising a first piezoelectric element that displaces in accordance with a drive signal, and capable of discharging liquid in accordance with the displacement of the first piezoelectric element, A second discharge unit comprising a second piezoelectric element that displaces in accordance with the drive signal, and capable of discharging liquid in accordance with the displacement of the second piezoelectric element, When the drive signal is supplied to the second piezoelectric element during a unit period, A detection unit for detecting the potential of the first piezoelectric element during the inspection period included in the aforementioned unit period, Equipped with, The aforementioned drive signal is During the first transition period of the aforementioned unit period, the potential changes from the first potential to the second potential. During the maintenance period following the first transition period within the aforementioned unit period, the second potential is maintained. During the second transition period following the maintenance period within the aforementioned unit period, the potential changes from the second potential to the first potential. The aforementioned maintenance period includes the aforementioned inspection period, The first transition period is longer than the second transition period. A head unit characterized by the following features.

12. The detection unit supplies a detection signal corresponding to the detection result of the detection unit to an inspection unit that inspects the state of the first discharge unit based on the detection result of the detection unit. The inspection unit outputs an inspection result indicating that the state of the first discharge unit is not normal if the amount of change in the potential of the first piezoelectric element during the inspection period is greater than or equal to a standard amount. A head unit according to any one of claims 7 to 11, characterized in that...

13. A first discharge unit comprising a first piezoelectric element that displaces in accordance with a drive signal, and capable of discharging liquid in accordance with the displacement of the first piezoelectric element, A second discharge unit comprising a second piezoelectric element that displaces in accordance with the drive signal, and capable of discharging liquid in accordance with the displacement of the second piezoelectric element, A method for inspecting a liquid dispensing device, comprising: When the drive signal is supplied to the second piezoelectric element during a unit period, The state of the first discharge unit is inspected based on a detection signal corresponding to the potential of the first piezoelectric element during the inspection period included in the unit period. The aforementioned drive signal is During the first period of the aforementioned unit period, the first potential is maintained. In the second period following the first period within the aforementioned unit period, the potential changes from the first potential to the second potential. In the third period following the second period within the aforementioned unit period, the second potential is maintained. In the fourth period following the third period within the aforementioned unit period, the potential changes from the second potential to the first potential. In the fifth period following the fourth period of the aforementioned unit period, the first potential is maintained. The aforementioned third period includes the inspection period, The second period is longer than the fourth period. A method for inspecting a liquid dispensing device, characterized by the following features.

14. During the aforementioned unit period, the first dispensing section and the second dispensing section are filled with liquid. The inspection method according to claim 13, characterized in that

15. The flow path provided in the first discharge section and the flow path provided in the second discharge section are in communication with a common liquid chamber for storing liquid. The inspection method according to claim 14, characterized in that

16. A first discharge unit comprising a first piezoelectric element that displaces in accordance with a drive signal, and capable of discharging liquid in accordance with the displacement of the first piezoelectric element, A method for inspecting a liquid dispensing device, comprising: When the drive signal is supplied to the first discharge unit during the drive period included in the unit period, The state of the first discharge unit is inspected based on a detection signal corresponding to the potential of the first piezoelectric element during the inspection period included in the unit period. The aforementioned drive signal is During the first period of the aforementioned unit period, the first potential is maintained. In the second period following the first period within the aforementioned unit period, the potential changes from the first potential to the second potential. In the third period following the second period within the aforementioned unit period, the second potential is maintained. In the fourth period following the third period within the aforementioned unit period, the potential changes from the second potential to the first potential. In the fifth period following the fourth period of the aforementioned unit period, the first potential is maintained. The aforementioned third period includes the inspection period, The aforementioned driving period does not include the aforementioned inspection period, but includes at least the aforementioned second period. The second period is longer than the fourth period. A method for inspecting a liquid dispensing device, characterized by the following features.

17. A first discharge unit comprising a first piezoelectric element that displaces in accordance with a drive signal, and capable of discharging liquid in accordance with the displacement of the first piezoelectric element, A second discharge unit comprising a second piezoelectric element that displaces in accordance with the drive signal, and capable of discharging liquid in accordance with the displacement of the second piezoelectric element, A method for inspecting a liquid dispensing device, comprising: When the drive signal is supplied to the second piezoelectric element during a unit period, The state of the first discharge unit is inspected based on a detection signal corresponding to the potential of the first piezoelectric element during the inspection period included in the unit period. The aforementioned drive signal is During the first transition period of the aforementioned unit period, the potential changes from the first potential to the second potential. During the maintenance period following the first transition period within the aforementioned unit period, the second potential is maintained. During the second transition period following the maintenance period within the aforementioned unit period, the potential changes from the second potential to the first potential. The aforementioned maintenance period includes the aforementioned inspection period, The first transition period is longer than the second transition period. A method for inspecting a liquid dispensing device, characterized by the following features.

18. If the change in the potential of the first piezoelectric element during the inspection period is greater than or equal to a standard amount, an inspection result indicating that the state of the first discharge unit is not normal is output. The inspection method according to any one of claims 13 to 17, characterized in that

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