Liquid ejecting apparatus

Abstract

To provide a liquid ejecting apparatus which can detect, by a simple configuration, the state of the apparatus including a pump which applies the pressure to a liquid inside a head.SOLUTION: A maintenance unit includes: a nozzle cap configured to cover a plurality of nozzles of an inkjet head; and a negative pressure pump connected to the nozzle cap. By driving the negative pressure pump in a state that the nozzle is covered with the nozzle cap, suction purge in which ink is discharged from the nozzles can be performed. The liquid ejecting apparatus executes a voltage obtainment process (S101) to obtain a voltage generated in a piezoelectric element of the inkjet head during a purge process (S102, S103) in which the suction purge is performed. On the basis of the voltage obtained in the voltage obtainment process, the liquid ejecting apparatus executes an abnormality detection process of detecting that the maintenance unit at least partially has an abnormality (S105).SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a liquid ejection device that ejects a liquid from a nozzle.

Background Art

[0002] As an example of a liquid ejection device that ejects a liquid from a nozzle, an inkjet printer that ejects ink from a nozzle to perform recording is known. For example, as described in Patent Document 1 and the like, in an inkjet printer, it is widely known to perform a purge in which pressure is applied to the ink in the head by a pump to discharge the ink in the inkjet head from the nozzle.

[0003] On the other hand, in Patent Document 2, a pump is provided in a flow path for supplying a pretreatment liquid to a coating roller for applying the pretreatment liquid to a sheet before recording. In addition, electrodes are provided in portions located before and after the pump in this flow path, and the two electrodes are connected to a discrimination circuit via a conversion circuit and an ADC. The discrimination circuit detects a change in impedance between the two electrodes, and detects a pump failure based on the detected change in impedance.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, in order to detect an abnormality of a pump that applies pressure to the ink in the head as described in Patent Document 1, it is considered to provide a configuration similar to that of Patent Document 2. In this case, it is necessary to provide electrodes on both sides of the pump in the flow path to which the pump is connected, or to provide a circuit connected to these electrodes, etc., leading to an increase in the size of the apparatus and an increase in manufacturing costs.

[0006] An object of the present invention is to provide a liquid ejection apparatus capable of detecting the state of an apparatus including a pump that applies pressure to a liquid in a head with a simple configuration.

Means for Solving the Problems

[0007] The liquid ejection apparatus of the present invention includes a head having a head flow path including a nozzle, a piezoelectric element forming a part of the wall of the head flow path, a nozzle cap for covering the nozzle, a negative pressure pump for generating a negative pressure, and a drainage connection flow path for connecting the nozzle cap and the negative pressure pump, and a control unit. The control unit performs a drainage process of discharging the liquid in the head flow path from the nozzle by driving the negative pressure pump with the nozzle covered by the nozzle cap, a voltage acquisition process of acquiring the voltage of the piezoelectric element at least during the drainage process, and an abnormality detection process of outputting an abnormality signal indicating that there is an abnormality in at least a part of the cleaning unit when the voltage acquired in the voltage acquisition process does not satisfy the drainage voltage condition.

[0008] Further, the liquid ejection device of the present invention includes a head having a head flow path including a nozzle, and a piezoelectric element forming a part of the wall of the head flow path, a positive pressure pump that applies a positive pressure to the liquid in the head flow path, a liquid receiving portion for receiving the liquid discharged from the nozzle, and a control unit. The control unit performs a liquid discharge process of discharging the liquid in the head flow path from the nozzle to the ink receiving portion by driving the positive pressure pump, a voltage acquisition process of acquiring the voltage of the piezoelectric element at least during the liquid discharge process, and an abnormality detection process of outputting an abnormality signal indicating that there is an abnormality in the positive pressure pump when the voltage acquired in the voltage acquisition process does not satisfy the voltage condition during liquid discharge.

[0009] Further, the liquid ejection device of the present invention includes a head having a head flow path including a nozzle and a liquid supply port, and a piezoelectric element forming a part of the wall of the head flow path, a liquid storage portion for storing the liquid to be supplied to the head flow path, a supply flow path connecting the discharge port and the liquid storage portion, an exhaust flow path branching from the supply flow path and having an exhaust port, an exhaust cap for covering the exhaust port, a negative pressure pump for generating a negative pressure, and an exhaust connection flow path connecting the exhaust cap and the negative pressure pump. The control unit performs an exhaust process of discharging the gas in the head flow path from the exhaust port by driving the negative pressure pump in a state where the exhaust port is covered by the exhaust cap, a voltage acquisition process of acquiring the voltage of the piezoelectric element at least during the liquid discharge process, and an abnormality detection process of outputting an abnormality signal indicating that there is an abnormality in at least a part of the cleaning unit when the voltage acquired in the voltage acquisition process does not satisfy the voltage condition during exhaust.

Advantages of the Invention

[0010] According to the present invention, it is possible to detect an abnormality in at least a part of the cleaning unit including the negative pressure pump or the positive pressure pump with a simple configuration.

Brief Description of the Drawings

[0011]

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Embodiments for Carrying Out the Invention

[0012] Hereinafter, preferred embodiments of the present invention will be described.

[0013] <Schematic Configuration of Printer> As shown in FIG. 1, the printer 1 of the present embodiment includes a carriage 2, a sub-tank 3, an inkjet head 4, a platen 5, conveyance rollers 6, 7, a maintenance unit 8, and the like. In the present embodiment, the printer 1 corresponds to the "liquid ejection device" of the present invention. Also, the inkjet head 4 corresponds to the "head" of the present invention. Further, the maintenance unit 8 corresponds to the "cleaning unit" of the present invention.

[0014] The carriage 2 is supported by two guide rails 11, 12 so as to be movable in the scanning direction. The carriage 2 is connected to a carriage motor 106 shown in FIG. 10 via a belt (not shown). When the carriage motor 106 is driven, the carriage 2 moves in the scanning direction along the guide rails 11, 12. Hereinafter, as shown in FIG. 1, the right side and the left side in the scanning direction will be defined for explanation.

[0015] The sub-tank 3 is mounted on the carriage 2. A tube joint 16 is provided on the upper surface of the sub-tank 3. The tube joint 16 is connected to a cartridge holder 10 via four tubes 17. Further, an exhaust unit 67 for discharging bubbles mixed in the flow path in the sub-tank 3 is provided on the right side surface of the sub-tank 3. The sub-tank 3 will be described in detail later.

[0016] The cartridge holder 10 includes four cartridge mounting portions 10a arranged in the scanning direction. An ink cartridge 20 is removably mounted on each cartridge mounting portion 10a. The four ink cartridges 20 mounted on the four cartridge mounting portions 10a store black, yellow, cyan, and magenta inks in order from the one located on the right side in the scanning direction. Then, the above four colors of inks stored in the four ink cartridges 20 mounted on the four cartridge mounting portions 41 are supplied to the sub-tank 3 via four ink supply tubes 17. In this embodiment, the ink cartridge 20 corresponds to the "liquid storage portion" of the present invention.

[0017] The inkjet head 4 is attached to the lower part of the sub-tank 3. The inkjet head 4 discharges the above four colors of inks from a plurality of nozzles 40 formed on the nozzle surface 4a which is the lower surface thereof. The details of the inkjet head 4 will be described later.

[0018] The platen 5 is located below the inkjet head 4 and faces the nozzle surface 4a. The platen 5 extends over the entire length of the recording paper S in the scanning direction and supports the recording paper S from below.

[0019] The conveyance roller 6 is a roller extending in the scanning direction and is located upstream of the inkjet head 4 and the platen 5 in the conveyance direction orthogonal to the scanning direction. The conveyance roller 7 is a roller extending in the scanning direction and is located downstream of the inkjet head 4 and the platen 5 in the conveyance direction. The conveyance rollers 6 and 7 are connected to a conveyance motor 107 shown in FIG. 10 via gears (not shown). When the conveyance motor 107 is driven, the conveyance rollers 6 and 7 rotate, and the recording paper S is conveyed in the conveyance direction.

[0020] The maintenance unit 8 is disposed at a position on the right side in the scanning direction from the platen 5. The maintenance unit 8 is for maintaining and recovering the ejection function of the inkjet head 4. The maintenance unit 8 will be described in detail later.

[0021] <inkjet head> Next, the inkjet head 4 will be described in detail. As shown in FIGS. 2 and 3, the inkjet head 4 includes a flow path unit 21 and a piezoelectric actuator 22.

[0022] The flow path unit 21 is formed by laminating four plates 31 to 34 in this order from top to bottom. The flow path unit 21 has a plurality of nozzles 40, a plurality of pressure chambers 41, a plurality of descenders 42, a plurality of connecting flow paths 43, and four manifolds 44.

[0023] The plurality of nozzles 40 are formed on the plate 34. The plurality of nozzles 40 form a nozzle row 9 by being arranged in the conveyance direction, and four rows of nozzle rows 9 are arranged in the scanning direction on the plate 34. From the nozzles 40, black, yellow, cyan, and magenta inks are ejected in order from the ones that form the nozzle row 9 on the right side in the scanning direction. Note that the lower surface of the plate 34 on which the nozzles 40 are formed is the nozzle surface 4a.

[0024] The plurality of pressure chambers 41 are provided individually for the plurality of nozzles 40. The plurality of pressure chambers 41 are formed on the plate 31. Each pressure chamber 41 has a substantially elliptical shape with the scanning direction as the longitudinal direction, and the left end portion in the scanning direction overlaps the corresponding nozzle 40 in the vertical direction.

[0025] The plurality of descenders 42 are provided individually for the plurality of nozzles 40. Each descender 42 extends in the vertical direction across the plates 32 and 33, and connects the corresponding nozzle 40 and the left end portion in the scanning direction of the pressure chamber 41.

[0026] The plurality of connection channels 43 are provided individually for the plurality of pressure chambers 41. Each connection channel 43 is formed in the plate 32, and its upper end is connected to the right end in the scanning direction of the corresponding pressure chamber 41.

[0027] And one individual channel 45 is formed by one nozzle 40, one pressure chamber 41, one descender 42, and one connection channel 43. Thus, the channel unit 21 has a plurality of individual channels 45.

[0028] The four manifolds 44 correspond to the four rows of nozzle rows 9. Each manifold 44 is formed in the plate 33 and extends in the conveyance direction over the entire length of the corresponding nozzle row 9. Each manifold 44 is connected to the lower ends of the plurality of connection channels 43 corresponding to the plurality of nozzles 40 constituting the corresponding nozzle row 9. Further, each manifold 44 extends to the upper surface of the plate 31 at the upstream end in the conveyance direction, and the opening on the upper surface of the plate 31 serves as the ink supply port 44a.

[0029] In this embodiment, the manifold 44 corresponds to the "common channel" of the present invention. And the combination of the plurality of individual channels 45 and the four manifolds 44 corresponds to the "head channel" of the present invention. Also, the combination of the plurality of individual channels 45 including the nozzles 40 constituting the rightmost nozzle row 9 that discharges black ink and the rightmost manifold 44 in the scanning direction connected to these individual channels 45 corresponds to the "first head channel" of the present invention. Further, the combination of the plurality of individual channels 45 including the nozzles 40 constituting the three leftmost nozzle rows 9 that discharge color ink and the three rightmost manifolds 44 in the scanning direction connected to these individual channels 45 corresponds to the "second head channel" of the present invention. Also, the ink supply port 44a corresponds to the "liquid supply port" of the present invention.

[0030] The piezoelectric actuator 22 has piezoelectric layers 51, 52, a common electrode 53, and a plurality of individual electrodes 54. The piezoelectric layers 51, 52 are made of a piezoelectric material mainly composed of lead zirconate titanate, which is a mixed crystal of lead titanate and lead zirconate. The piezoelectric layer 51 is disposed on the upper surface of the plate 31 so as to cover the plurality of pressure chambers 41. Note that, instead of the piezoelectric layer 51, a layer made of an insulating material other than a piezoelectric material, such as a synthetic resin material, may be disposed. The piezoelectric layer 52 is disposed on the upper surface of the piezoelectric layer 51 and extends continuously over the plurality of pressure chambers 41.

[0031] The common electrode 53 extends continuously over the plurality of pressure chambers 41 between the piezoelectric layer 51 and the piezoelectric layer 52. The common electrode 53 is connected to a power supply (not shown) or the like via a wiring member (not shown) and is held at a ground potential.

[0032] The plurality of individual electrodes 54 are provided individually in the plurality of pressure chambers 41. The individual electrode 54 has an elliptical shape that is slightly smaller than the pressure chamber 41 and has a longitudinal direction in the scanning direction in plan view, and overlaps the central portion of the pressure chamber 41 in the vertical direction. In addition, the right end portion of the individual electrode 54 extends to a position that does not overlap the pressure chamber 41 in the vertical direction, and the tip portion thereof serves as a connection terminal 54a. The connection terminal 54a is connected to the driver IC 108 shown in FIG. 10 via a wiring member (not shown). Then, the voltage of the plurality of individual electrodes 54 is individually switched between the ground potential and a predetermined driving potential of, for example, about 20V by the driver IC 108.

[0033] In correspondence with the common electrode 53 and the plurality of individual electrodes 54 being arranged in this way, the portions of the piezoelectric layer 52 sandwiched between the common electrode 53 and each individual electrode 54 are polarized in the vertical direction. And in the piezoelectric actuator 22, the portions that overlap with the respective pressure chambers 41 in the vertical direction serve as piezoelectric elements 50 for applying pressure to the ink in the pressure chambers 41. And each piezoelectric element 50 forms the upper wall of the corresponding pressure chamber 41. In the present embodiment, the piezoelectric element 50 that forms the wall of the pressure chamber 41 corresponding to the nozzle 40 that discharges black ink corresponds to the "first piezoelectric element" of the present invention. Also, the piezoelectric element 50 that forms the wall of the pressure chamber 41 corresponding to the nozzle 40 that discharges color ink corresponds to the "second piezoelectric element" of the present invention.

[0034] Here, a method of driving the piezoelectric element 50 to discharge ink from the corresponding nozzle 40 will be described. In the printer 1, in a standby state where ink is not discharged from the nozzle 40, the individual electrode 54 is held at the ground potential by the driver IC 108. When discharging ink from the nozzle 40, the driver IC 108 switches the potential of the individual electrode 54 from the ground potential to the drive potential. When the potential of the individual electrode 54 is switched to the drive potential, an electric field is generated in the portion of the piezoelectric layer 52 sandwiched between the individual electrode 54 and the common electrode 53 due to the potential difference between the individual electrode 54 and the common electrode 53. This electric field causes this portion of the piezoelectric layer 52 to contract, and the piezoelectric element 50 deforms so as to protrude toward the pressure chamber 41 as a whole. As a result, the volume of the pressure chamber 41 decreases, so that the pressure of the ink in the pressure chamber 41 increases, and ink is discharged from the nozzle 40 communicating with the pressure chamber 41.

[0035] <Sub-tank> Next, the configuration of the sub-tank 3 will be specifically described. As shown in FIGS. 4 and 5, the sub-tank 3 has a horizontally extending main body portion 60 and a connecting portion 61 that extends vertically downward from the upstream end of the main body portion 60 in the conveyance direction. Four ink flow paths 62 through which the above four colors of ink flow are formed in the sub-tank 3. In FIG. 4, for the sake of simplicity of the drawing, only the whole of one of the four ink flow paths 62 is shown, and the illustration of the remaining three ink flow paths 62 is partially omitted. In FIG. 5, the inkjet head 4 is illustrated not in a cross-sectional view but in a side view.

[0036] One end of each of the four ink flow paths 62 is provided at the above-described tube joint 16. And the above four tubes 17 are connected to the four ink flow paths 62 at the tube joint 16. In the present embodiment, the combination of the tube 17 and the ink flow path 62 corresponds to the "supply flow path" of the present invention.

[0037] Each ink flow path 62 includes a damper chamber 64 formed in the main body portion 60 and a communication flow path 65 formed in the connecting portion 61. Flexible films 63 are respectively attached to the upper and lower surfaces of the main body portion 60, and the flow path including the damper chamber 64 formed in the main body portion 60 is covered by the film 63. The damper chamber 64 has a flatter cross-section than the flow path portions connected to the upstream side and the downstream side of the damper chamber 64 of the ink flow path 62. The damper chamber 64 absorbs the pressure fluctuations of the ink flowing through the ink flow path 62 due to the deformation of the film 63. The connecting portion 61 of the sub-tank 3 is connected to the inkjet head 4. Thereby, the lower end of the communication flow path 65 is connected to the ink supply port 44a of the inkjet head 4. And the four colors of ink flowing through the four ink flow paths 62 are supplied to the inkjet head 4 from the four ink supply ports 44a.

[0038] In addition, four exhaust channels 66 branched from the four ink channels 62 are formed in the main body portion 60. As shown in FIG. 4, the four exhaust channels 66 extend to an exhaust unit 67 provided on the right side surface of the sub-tank 3. Further, as shown in FIG. 6(a), a channel portion 66a located inside the exhaust unit 67 of the exhaust channel 66 extends in the vertical direction, and the lower end thereof serves as an exhaust port 66b.

[0039] In addition, a valve housing chamber 66c is provided in the channel portion 66a of each exhaust channel 66. A valve 68 is housed in the valve housing chamber 66c. The valve 68 is for opening and closing the exhaust channel 66. The valve 68 includes a valve body 68a, an O-ring 68b, and a spring 68c. The upper end of the valve body 68a is housed in the valve housing chamber 66c, and the portion located in the valve housing chamber 66c extends downward toward the exhaust port 66b. The O-ring 68b is disposed at the lower end of the valve housing chamber 66c. The spring 68c biases the valve body 68a downward toward the O-ring 68b.

[0040] When the valve body 68a is not pressed by a shaft 86 described later, the valve body 68a is pressed against the O-ring 68b by the biasing force of the spring 68c, and the valve 68 is in a closed state. When the valve body 68a is pressed by the shaft 86 described later, the valve body 68a is pushed upward against the biasing force of the spring 68c and separated from the O-ring 68b, and the valve 68 is in an open state. Here, the valve 68 is a known one as described in, for example, Japanese Patent Laid-Open No. 2017-177773.

[0041] <Maintenance Unit> As shown in FIG. 1, the maintenance unit 8 includes a nozzle cap unit 81, an exhaust cap 82, a negative pressure pump 83, a switching unit 84, a waste liquid tank 85, and the like.

[0042] As shown in FIG. 1, the nozzle cap unit 81 is formed by integrating a first nozzle cap 81a and a second nozzle cap 81b. The second nozzle cap 81b is disposed adjacent to the left side of the first nozzle cap 81a in the scanning direction. When the carriage 2 moves to the maintenance position on the right side of the platen 5, the first nozzle cap 81a faces the rightmost nozzle row 9, and the second nozzle cap 81b faces the three leftmost nozzle rows 9. Further, the nozzle caps 81a and 81b each have connection ports 81a1 and 81b1 at the downstream end in the conveyance direction.

[0043] As shown in FIG. 1, the exhaust cap 82 is disposed on the right side of the nozzle cap unit 81. When the carriage 2 moves to the maintenance position, the exhaust cap 82 faces the four exhaust ports 66b of the exhaust unit 67. Further, as shown in FIGS. 6(a) and 6(b), the bottom 82a of the exhaust cap 82 has a connection port 82b at the upstream end in the conveyance direction. The bottom 82a of the exhaust cap 82 also has four through holes 82c for passing a shaft 86, which will be described later, in a portion downstream of the connection port 82b in the conveyance direction.

[0044] The nozzle cap unit 81 and the exhaust cap 82 can be lifted and lowered integrally by a cap lifting device 109 shown in FIG. 10. When the carriage 2 is in the maintenance position and the cap lifting device 109 raises the nozzle cap unit 81 and the exhaust cap 82, the nozzle cap unit 81 comes into close contact with the nozzle surface 4a, and the exhaust cap 82 comes into close contact with the lower surface of the exhaust unit 67. As a result, a plurality of nozzles 40 constituting the rightmost nozzle row 9 are covered by the first nozzle cap 81a, a plurality of nozzles 40 constituting the three leftmost nozzle rows 9 are covered by the second nozzle cap 81b, and the four exhaust ports 66b are covered by the exhaust cap 82. Hereinafter, this state may be referred to as the cap state.

[0045] Note that the first nozzle cap 81a and the second nozzle cap 81b are not necessarily limited to covering the nozzle 40 by closely adhering to the nozzle surface 4a. For example, when the inkjet head 4 has a frame arranged to surround the nozzle surface 4a to protect the nozzle 40, the first nozzle cap 81a and the second nozzle cap 81b may cover the nozzle 40 by closely adhering to this frame.

[0046] On the other hand, when the nozzle cap unit 81 and the exhaust cap 82 are lowered by the cap lifting device 109, the nozzle cap unit 81 separates from the nozzle surface 4a, and the exhaust cap 82 separates from the lower surface of the exhaust unit 67.

[0047] Also, as shown in FIGS. 6(a) and 6(b), four rod-shaped shafts 86 extending in the vertical direction are provided on the exhaust cap 82. The four shafts 86 are arranged in the conveyance direction and are inserted into four through-holes 82c of the exhaust cap 82, penetrating the bottom 82a of the exhaust cap 82 in the vertical direction.

[0048] The four shafts 86 overlap the four exhaust ports 66b of the four exhaust channels 66 in the vertical direction when the carriage 2 is located at the maintenance position. Among the four shafts 86, the lower end of the shaft 86 on the most upstream side in the conveyance direction is connected to the support portion 87. The support portion 87 can be raised and lowered by a shaft lifting mechanism 110 shown in FIG. 10.

[0049] Also, among the four shafts 86, the three shafts 86 on the downstream side in the conveyance direction are connected to each other by connecting their lower ends to the support portion 88. The support portion 88 can be raised and lowered independently of the support portion 87 by the shaft lifting mechanism 110. Note that the shaft lifting mechanism 110 may raise and lower the support portions 87 and 88 in conjunction with the switching by a switching unit 84 described later, as described in, for example, Japanese Patent Application Laid-Open No. 2017-177773.

[0050] In the state where the support parts 87 and 88 are lowered, as shown in Fig. 6(a), the valve body 68a is not pressed against the shaft 86, and the valve body 68a is pressed against the O-ring 68b by the biasing force of the spring 68c, and the valve 68 is in a closed state.

[0051] When the support part 87 rises in the cap state, as shown in Fig. 7(a), the shaft 86 on the most upstream side in the conveyance direction rises, and the valve body 68a of the valve 68 on the most upstream side in the conveyance direction is pushed up by this shaft 86 against the biasing force of the spring 68c, and this valve 68 opens.

[0052] When the support part 88 rises in the cap state, as shown in Fig. 7(b), the three shafts 86 on the downstream side in the conveyance direction rise, and the valve bodies 68a of the three valves 68 on the downstream side in the conveyance direction are pushed up by these shafts 86 against the biasing force of the spring 68c, and these three valves 68 open.

[0053] The negative pressure pump 83 is, for example, a tube pump and has a pump motor 83a shown in Fig. 10. The negative pressure pump 83 generates a negative pressure by driving the pump motor 83a. The switching unit 84 is connected to the connection port 81a1 of the first nozzle cap 81a via the tube 19a. Also, the switching unit 84 is connected to the connection port 81b1 of the second nozzle cap 81b via the tube 19b. Also, the switching unit 84 is connected to the connection port 82b of the exhaust cap 82 via the tube 19c. Also, the switching unit 84 is connected to the negative pressure pump 83 via the tube 19d. The switching unit 84 switches between a state where the tube 19a and the tube 19d are connected, a state where the tube 19b and the tube 19d are connected, and a state where the tube 19c and the tube 19d are connected. Also, the negative pressure pump 83 is connected to the waste liquid tank 85 via the tube 19e.

[0054] In this embodiment, tubes 19a, 19b, and 19d correspond to the "drain connection channel" of the present invention. Also, tube 19a corresponds to the "first drain connection channel" of the present invention. Further, tube 19b corresponds to the "second drain connection channel" of the present invention. Also, tubes 19c and 19d correspond to the "exhaust connection channel" of the present invention.

[0055] <Operation of Maintenance Unit> In the maintenance unit 8 as described above, in the above cap state, by connecting tube 19a and tube 19d by the switching unit 84 to connect the first nozzle cap 81a and the negative pressure pump 83, and then driving the pump motor 83a of the negative pressure pump 83, black ink in the inkjet head 4 is discharged from a plurality of nozzles 40 constituting the rightmost nozzle row 9 in the scanning direction to the first nozzle cap 81a, and a black suction purge can be performed.

[0056] Also, in the maintenance unit 8, in the above cap state, by connecting tube 19b and tube 19d by the switching unit 84 to connect the second nozzle cap 81b and the negative pressure pump 83, and then driving the pump motor 83a of the negative pressure pump 83, yellow, cyan, and magenta inks in the inkjet head 4 are discharged from a plurality of nozzles 40 constituting the three rightmost nozzle rows 9 in the scanning direction to the second nozzle cap 81b, and a color suction purge can be performed.

[0057] Also, in the maintenance unit 8, in the above-described cap state, the switching unit 84 connects the tube 19c and the tube 19d to connect the exhaust cap 82 and the negative pressure pump 83. Then, as shown in FIG. 7(a), after opening the valve 68 on the most upstream side in the conveyance direction, the pump motor 83a of the negative pressure pump 83 is driven to discharge the gas in the exhaust passage 66 corresponding to the nozzle row 9 on the rightmost side in the scanning direction to the exhaust cap 82, thereby performing a black exhaust purge. During the black exhaust purge, together with the gas in the exhaust passage 66, the black ink in the corresponding ink passage 62 is discharged to the exhaust cap 82 through the exhaust passage 66.

[0058] Also, in the maintenance unit 8, in the above-described cap state, the switching unit 84 connects the tube 19c and the tube 19d to connect the exhaust cap 82 and the negative pressure pump 83. Then, as shown in FIG. 7(b), after opening the three valves 68 on the downstream side in the conveyance direction, the pump motor 83a of the negative pressure pump 83 is driven to discharge the gas in the three exhaust passages 66 corresponding to the three nozzle rows 9 on the left side in the scanning direction to the exhaust cap 82, thereby performing a color exhaust purge. During the color exhaust purge, together with the gas in the exhaust passage 66, the color ink in the corresponding three ink passages 62 is discharged to the exhaust cap 82 through the exhaust passage 66.

[0059] Also, the ink discharged during the black suction purge, color suction purge, black exhaust purge, and color exhaust purge is stored in the waste liquid tank 85.

[0060] <Discharge inspection unit> As shown in FIG. 8, the printer 1 includes a discharge inspection unit 90. The discharge inspection unit 90 includes an electrode 91, a high-voltage power supply circuit 92, a signal processing circuit 93, and a resistor 94. In the present embodiment, the discharge inspection unit 90 corresponds to the "inspection signal output unit" of the present invention.

[0061] The electrode 91 has a rectangular planar shape and is disposed within the first nozzle cap 81a and the second nozzle cap 81b. The electrode 91 is connected to a high-voltage power supply circuit 92 via a resistor 94. And the high-voltage power supply circuit 92 applies a predetermined voltage of, for example, about 600 V to the electrode 91. On the other hand, the flow path unit 21 of the inkjet head 4 is held at the ground potential. Thereby, a potential difference is generated between the inkjet head 4 and the electrode 91. The signal processing circuit 93 is connected to the electrode 91. The signal processing circuit 93 includes a differentiating circuit and the like, and outputs an inspection signal which is a voltage signal corresponding to the voltage of the electrode 91. However, the inspection signal output from the signal processing circuit 93 may be a current signal.

[0062] Also, in the present embodiment, in the above-described cap state, with a voltage applied to the electrode 91 by the high-voltage power supply circuit 92, for each of the plurality of nozzles 40, inspection driving can be performed to drive the inkjet head 4 to eject ink from the nozzle 40.

[0063] When ink is ejected from the nozzle 40 by the inspection driving, the ejected ink is charged by the potential difference between the electrode 91 and the inkjet head 4. And until the charged ink approaches the electrode 91 and lands on the electrode 91, the potential of the electrode 91 changes. And after the charged ink lands on the electrode 91, the potential of the electrode 91 returns to the potential before the ink ejection while decaying.

[0064] Thereby, when ink is normally ejected from the nozzle 40 by the inspection driving, the voltage of the inspection signal output from the signal processing circuit 93 rises and then falls as shown in FIG. 9(a), and then repeats rising and falling while decaying and returns to the voltage before the inspection driving.

[0065] On the other hand, when there is an abnormality in the nozzle 40 and the amount of ink ejected from the nozzle 40 by the inspection drive is less than that in the normal state, as shown in FIG. 9(b), the change in the voltage in the inspection signal output from the signal processing circuit 93 is smaller than when the ink is normally ejected from the nozzle 40. Here, the fact that the amount of ink ejected is less than when the ink is normally ejected from the nozzle 40 includes the case where no ink is ejected. When no ink is ejected from the nozzle 40 by the inspection drive, the voltage of the inspection signal output from the signal processing circuit 93 hardly changes.

[0066] Thus, in this embodiment, depending on whether or not the ink is normally ejected from the nozzle 40 when the inspection drive is performed, the change in the voltage of the inspection signal output from the signal processing circuit 93 is different. That is, the inspection signal output from the signal processing circuit 93 is a signal indicating whether the nozzle 40 is an abnormal nozzle with an abnormality in ink ejection.

[0067] Here, in this embodiment, a predetermined voltage is applied to the electrode 91, the inkjet head 4 is held at the ground potential, and the signal processing circuit 93 is configured to output a signal according to the voltage of the electrode 91, but it is not limited to this. By holding the electrode 91 at the ground potential and applying a predetermined voltage to the inkjet head 4, a potential difference is generated between the electrode 91 and the inkjet head 4, and the signal processing circuit 93 may be configured to output an inspection signal according to the voltage of the inkjet head 4, which is connected to the inkjet head 4.

[0068] <Electrical Configuration of Printer> Next, the electrical configuration of the printer 1 will be described. As shown in FIG. 10, the printer 1 includes a control unit 100. The control unit 100 includes a CPU 101, a ROM 102, a RAM 103, a memory 104, an ASIC 105, and the like.

[0069] The control unit 100 controls the carriage motor 106, the conveyance motor 107, the driver IC 108, the cap lifting mechanism 109, the shaft lifting mechanism 110, the pump motor 83a of the negative pressure pump 83, the switching unit 84, the high voltage power supply circuit 92, the signal processing circuit 93, etc. In this embodiment, the control unit 100 controls the inkjet head 4 by controlling the driver IC 108.

[0070] In addition to the configuration described above, the printer 1 includes an operation panel 99. The operation panel 99 is, for example, a touch panel provided on the housing of the printer 1. The control unit 100 controls the operation panel 99 to display various screens and the like on the operation panel 99. Also, when the operation panel 99 is operated by the user, a signal corresponding to the user's operation is transmitted from the operation panel 99 to the control unit 100. In this embodiment, the operation panel 99 corresponds to the "display unit" of the present invention. Also, instead of the operation panel 99, a display unit such as a liquid crystal display and an operation unit such as buttons may be provided separately.

[0071] Also, the control unit 100 may be such that only the CPU 101 performs various processes, or only the ASIC 105 performs various processes, or the CPU 101 and the ASIC 105 cooperate to perform various processes. Also, the control unit 100 may be such that one CPU 101 performs processing alone, or a plurality of CPUs 101 perform processing in a shared manner. Also, the control unit 100 may be such that one ASIC 105 performs processing alone, or a plurality of ASICs 105 perform processing in a shared manner.

[0072] <Processing during recording> In printer 1, the control unit 100 controls the carriage motor 106 to move the carriage 2 in the scanning direction, controls the driver IC 108 to eject ink from a plurality of nozzles 40 of the inkjet head 4 toward the recording paper S, and repeatedly performs a recording operation path and a conveyance operation of controlling the conveyance motor 107 to convey the recording paper S in the conveyance direction by the conveyance rollers 6 and 7, thereby performing recording on the recording paper S.

[0073] <Processing at the time of receiving a cleaning instruction signal> Next, in the present embodiment, the processing by the control unit 100 when receiving a cleaning instruction signal instructing to clean the nozzles 40 will be described. In the present embodiment, when an operation for instructing the user to clean the nozzles 40 is performed on the operation panel 99, the operation panel 99 transmits a cleaning instruction signal, and the control unit 100 receives this cleaning instruction signal. When receiving the cleaning instruction signal, the control unit 100 performs processing according to the flowchart of FIG. 11(a).

[0074] Specifically, when receiving the cleaning instruction signal, the control unit 100 executes a black exhaust purge process (S101). In the black exhaust purge process, the control unit 100 controls the carriage motor 106, the cap lifting mechanism 109, the shaft lifting mechanism 110, the switching unit 84, the pump motor 83a, etc. to perform the above-described black exhaust purge.

[0075] Subsequently, the control unit 100 executes a color exhaust purge process (S102). In the color exhaust purge process, the control unit 100 controls the carriage motor 106, the cap lifting mechanism 109, the shaft lifting mechanism 110, the switching unit 84, the pump motor 83a, etc. to perform the above-described color exhaust purge.

[0076] Subsequently, the control unit 100 starts voltage acquisition processing (S103). In the voltage acquisition processing, the control unit 100 acquires the voltage of the piezoelectric element 50 by acquiring the voltage of the individual electrode 54. Details of the acquisition of the voltage of the piezoelectric element 50 in the voltage acquisition processing will be described later.

[0077] Subsequently, the control unit 100 executes black suction purge processing (S104). In the black suction purge processing, the control unit 100 controls the carriage motor 106, the switching unit 84, the cap lifting mechanism 109, the pump motor 83a, etc. to cause the above-described black suction purge to be performed. Further, in the voltage acquisition processing started in S103, the voltage of the piezoelectric element 50 corresponding to any of the nozzles 40 that discharge black ink is acquired during the black suction purge.

[0078] Subsequently, the control unit 100 executes color suction purge processing (S105). In the color suction purge processing, the control unit 100 controls the carriage motor 106, the switching unit 84, the cap lifting mechanism 109, the pump motor 83a, etc. to cause the above-described color suction purge to be performed. Further, in the voltage acquisition processing started in S103, the voltage of the piezoelectric element 50 corresponding to any of the nozzles 40 that discharge color ink is acquired during the color suction purge.

[0079] Note that in the present embodiment, the black and color suction purges correspond to the "drainage processing" of the present invention. Further, the black suction purge processing corresponds to the "first drainage processing" of the present invention. The color purge processing corresponds to the "second drainage processing" of the present invention. Also, in the voltage acquisition processing, the processing performed during the black suction purge corresponds to the "first voltage acquisition processing" of the present invention, and the processing performed during the color suction purge corresponds to the "second voltage acquisition processing" of the present invention.

[0080] Subsequently, the control unit 100 finishes the voltage acquisition process (S106) and executes an abnormality detection process (S107). In the abnormality detection process, the control unit 100 outputs a signal corresponding to the change in the voltage of the piezoelectric element 50 acquired during the black suction purge and the change in the voltage of the piezoelectric element 50 acquired during the color suction purge to the operation panel 99.

[0081] Specifically, as shown in FIG. 11(b), when the voltage of the piezoelectric element 50 reaches the voltage V1k within the time T1k after the start of the black suction purge and the voltage of the piezoelectric element 50 reaches the voltage V1c within the time T1c after the start of the color suction purge, the control unit 100 outputs a normal signal to the operation panel 99, and as shown in FIG. 11(c), causes the operation panel 99 to display a normal screen 111 indicating that the maintenance unit 8 is normal. Here, the voltage V1k and the voltage V1c may be the same voltage or different voltages. Also, the time T1k and the time T1c may be the same time or different times.

[0082] In this embodiment, the condition that the voltage of the piezoelectric element 50 reaches the voltage V1k within the time T1k after the start of the black suction purge corresponds to the "voltage condition during liquid discharge" and the "first voltage condition during liquid discharge" of the present invention. Also, the condition that the voltage of the piezoelectric element 50 reaches the voltage V1c within the time T1c after the start of the color suction purge corresponds to the "voltage condition during liquid discharge" and the "second voltage condition during liquid discharge" of the present invention. Also, the voltages V1k and V1c correspond to the "predetermined voltage" of the present invention. Also, the times T1k and T2k correspond to the "first time" of the present invention. Also, in FIG. 11(b), for each condition, the case where it is satisfied is indicated by "〇" and the case where it is not satisfied is indicated by "×". The same applies to FIGS. 12(b), 18(b), and 20(b) described later.

[0083] Further, when the voltage of the piezoelectric element 50 does not reach V1k within the time T1k after the start of the black suction purge, and the voltage of the piezoelectric element 50 reaches V1c within the time T1c after the start of the color suction purge, the control unit 100 outputs an abnormal signal A1 to the operation panel 99, and as shown in FIG. 11(d), among the maintenance units 8, an abnormal screen 112A indicating that there is an abnormality in at least any one of the first nozzle cap 81a, the switching unit 84, and the black drain flow path is displayed on the operation panel 99. Here, the black drain flow path is a flow path such as the tube 19a through which black ink flows during the black suction purge and through which color ink does not flow during the color suction purge.

[0084] Further, an abnormality in the first nozzle cap 81a means, for example, that there is a crack in the first nozzle cap 81a, or that the first nozzle cap 81a is clogged with foreign matters such as paper dust and fragments of the recording paper S. Further, an abnormality in the switching unit 84 means, for example, that the above switching by the switching unit 84 is not performed normally, that gas flows in from another flow path such as a gas flow path due to a shortage of internal grease, or that the flow path is blocked by solidified ink or foreign matters. Further, an abnormality in the black drain flow path means, for example, that the tube 19a is bent, the tube 19a is clogged with solidified ink or foreign matters, etc., so that the flow path in the tube 19a is blocked, a crack enters the connection part of the tube 19a, or the tube 19a comes off. Even if it is other than the factors described above, those that affect the change in the suction pressure during the suction purge are considered abnormal, and include abnormalities related to the blockage of the system to which pressure is applied, and abnormalities in which the pressure increase is inhibited by the inflow of gas.

[0085] Also, if the voltage of the piezoelectric element 50 reaches V1k within the time T1k after the start of the black suction purge, and the voltage of the piezoelectric element 50 does not reach V1c within the time T1c after the start of the color suction purge, the control unit 100 outputs an abnormal signal A2 to the operation panel 99, and as shown in FIG. 11(e), on the maintenance unit 8, an abnormal screen 112B indicating that there is an abnormality in at least any one of the second nozzle cap 81b, the switching unit 84, and the color drainage flow path is displayed on the operation panel 99. Here, the color drainage flow path refers to a flow path such as the tube 19b, through which the black ink does not flow during the black suction purge, and through which the color ink flows during the color suction purge.

[0086] Also, an abnormality in the first nozzle cap 81a means, for example, that the second nozzle cap 81b has a crack, or that the second nozzle cap 81b is clogged with foreign substances such as paper dust and fragments of the recording paper S. Also, an abnormality in the color drainage flow path means, for example, that the tube 19b is bent, the tube 19b is clogged with solidified ink or foreign substances, etc., so that the flow path in the tube 19b is blocked, a crack enters the connection part of the tube 19b, or the tube 19b is detached. Even if it is other than the factors described above, anything that affects the change in the suction pressure during the suction purge is considered an abnormality, including abnormalities related to the blockage of the pressure-applying system and abnormalities in which the pressure increase is inhibited by the inflow of gas.

[0087] Also, if the voltage of the piezoelectric element 50 does not reach V1k within the time T1k after the start of the black suction purge, and the voltage of the piezoelectric element 50 does not reach V1c within the time T1c after the start of the color suction purge, the control unit 100 outputs an abnormal signal A3 to the operation panel 99, and as shown in FIG. 11(f), on the maintenance unit 8, an abnormal screen 112C indicating that there is an abnormality in at least any one of the switching unit 84, the negative pressure pump 83, and the common drain passage is displayed on the operation panel 99. Here, the common drain passage is a passage such as the tube 19d through which black ink flows during the black suction purge and color ink flows during the color suction purge.

[0088] Also, an abnormality in the negative pressure pump 83 means, for example, that the pump motor 83a cannot be driven normally due to a broken or rusted wiring of the pump motor 83a, or when the negative pressure pump 83 is a tube pump, the roller of the tube pump is damaged, or the tube is deteriorated and air is leaking. Also, an abnormality in the common drain passage means, for example, that the tube 19d is bent, the tube 19d is clogged with solidified ink or foreign matter, etc., so that the flow path in the tube 19d is blocked, a crack enters the connection part of the tube 19d, or the tube 19d comes off. Even if it is other than the above-described content, anything that affects the change in the suction pressure during the suction purge is considered an abnormality, and it also includes an abnormality related to the blockage of the pressure-applied system and an abnormality in which the pressure increase is inhibited by the inflow of gas.

[0089] <Effect> Here, when the black suction purge is performed normally, the pressure in the plurality of pressure chambers 41 corresponding to the plurality of nozzles 40 that discharge black ink becomes negative pressure, causing the piezoelectric element 50 that forms the walls of these pressure chambers 41 to deform. Then, a voltage is generated in the piezoelectric layer 52 due to the deformation of the piezoelectric element 50. In this embodiment, since the common electrode 53 is held at the ground potential, the voltage of the individual electrode 54 is the voltage generated in the piezoelectric element 50. Therefore, by acquiring the voltage of the individual electrode 54, the voltage of the piezoelectric element 50 can be acquired. And the voltage of the piezoelectric element 50 reaches the voltage V1k within the time T1k after the black suction purge is started. On the other hand, when the black suction purge is not performed normally, the deformation of the piezoelectric element 50 is small, or the deformation of the piezoelectric element 50 is gentle. Therefore, in this case, the voltage of the piezoelectric element 50 may not reach the voltage V1k, or the time from when the black suction purge is started until the voltage of the piezoelectric element 50 reaches the voltage V1k may exceed the time T1k.

[0090] Similarly, when the color suction purge is performed normally, the pressure in the plurality of pressure chambers 41 corresponding to the plurality of nozzles 40 that discharge color ink becomes negative pressure, causing the piezoelectric element 50 that forms the walls of these pressure chambers 41 to deform, and a voltage is generated in the piezoelectric element 50. And the voltage of the piezoelectric element 50 reaches the voltage V1c within the time T1c after the color suction purge is started. On the other hand, when the color suction purge is not performed normally, the voltage of the piezoelectric element 50 may not reach the voltage V1c, or the time from when the color suction purge is started until the voltage of the piezoelectric element 50 reaches the voltage V1c may exceed the time T1c.

[0091] Therefore, in the present embodiment, when the voltage of the piezoelectric element 50 does not reach the voltage V1k within the time T1k after the start of the black suction purge, and when the voltage of the piezoelectric element 50 does not reach the voltage V1c within the time T1c after the start of the color suction purge, an abnormal signal indicating that at least a part of the maintenance unit 8 is abnormal is output. Thereby, at least a part of the maintenance unit 8 including the negative pressure pump 83, that is, the entire maintenance unit 8, the first and second nozzle caps 81a and 81b, the negative pressure pump 83, the switching unit 84, and the tubes 19a to 19d can be detected to have an abnormality with a simple configuration.

[0092] Also, at this time, when the voltage of the piezoelectric element 50 does not reach the voltage V1k within the time T1k after the start of the black suction purge and the voltage of the piezoelectric element 50 reaches the voltage V1c within the time T1c after the start of the color suction purge, there is a high possibility that there is an abnormality in the part of the maintenance unit 8 related to the black suction purge. Therefore, in the present embodiment, in this case, an abnormal signal A1 indicating that there is an abnormality in at least one of the first nozzle cap 81a, the black drain channel, and the switching unit 84, which are related to the black suction purge, among the maintenance unit 8 is output.

[0093] On the other hand, when the voltage of the piezoelectric element 50 reaches the voltage V1k within the time T1k after the start of the black suction purge and the voltage of the piezoelectric element 50 does not reach the voltage V1c within the time T1c after the start of the color suction purge, there is a high possibility that there is an abnormality in the part of the maintenance unit 8 related to the color suction purge. Therefore, in the present embodiment, in this case, an abnormal signal A2 indicating that there is an abnormality in at least one of the second nozzle cap 81b, the color drain channel, and the switching unit 84, which are related to the color suction purge, among the maintenance unit 8 is output.

[0094] In addition, in the maintenance unit 8, the possibility that abnormalities occur simultaneously in the part related to the black suction purge and not related to the color suction purge, and the part related to the color suction purge and not related to the black suction purge is low. Therefore, when the voltage of the piezoelectric element 50 does not reach the voltage V1k within the time T1k after the start of the black suction purge and the voltage of the piezoelectric element 50 does not reach the voltage V1c within the time T1c after the start of the color suction purge, there is a high possibility that there is an abnormality in the part of the maintenance unit 8 related to both the black suction purge and the color suction purge. Therefore, in the present invention, in this case, an abnormality signal A3 indicating that there is an abnormality in at least any one of the switching unit 84, the negative pressure pump 83, and the common drain channel related to both the black suction purge and the color suction purge is output.

[0095] In addition, in the present embodiment, by outputting any one of the abnormality signals A1 to A3, it indicates that there is an abnormality in at least a part of the maintenance unit 8, and any one of the abnormality screens 112A to 112C that prompt the replacement of at least a part of the maintenance unit 8 is displayed on the operation panel 99. Thereby, the user can be made to recognize that it is better to replace at least a part of the maintenance unit 8.

[0096] In addition, in the present embodiment, when the voltage of the piezoelectric element 50 reaches the voltage V1k within the time T1k after the start of the black suction purge and the voltage of the piezoelectric element 50 reaches the voltage V1c within the time T1c after the start of the color suction purge, there is a high possibility that the maintenance unit 8 is normal. Therefore, in the present embodiment, in this case, a normal signal indicating that the maintenance unit 8 is normal is output, and a normal screen 111 indicating that the maintenance unit 8 is normal is displayed on the operation panel 99. Thereby, the user can be made to recognize that the maintenance unit 8 is normal.

[0097] Also, in the printer 1, when the user performs an operation for instructing cleaning on the operation panel 99, there are often problems with the recording result on the recording paper S. On the other hand, when there is a problem with the recording on the recording paper S, since there is an abnormality in at least a part of the maintenance unit 8, there is a possibility that the ink was not sufficiently discharged in the suction purge performed before the recording on the recording paper S.

[0098] Therefore, in the present embodiment, when the operation panel 99 transmits a cleaning instruction signal by the user's operation on the operation panel 99 and the control unit 100 receives this cleaning instruction, the control unit 100 executes a process for detecting whether there is an abnormality in the maintenance unit 8.

[0099] <Modification example> As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments, and various modifications are possible as long as they are within the scope described in the claims.

[0100] In the above-described embodiment, in the abnormality detection process, a signal corresponding to whether the voltage of the piezoelectric element 50 reaches V1k within the time T1k after the start of the black suction purge and whether the voltage of the piezoelectric element 50 reaches V1c within the time T1c after the start of the color suction purge was output, but it is not limited to this.

[0101] For example, in the abnormality detection process, regardless of the time from the start of the black suction purge, it is determined whether the voltage of the piezoelectric element 50 obtained by the voltage acquisition process reaches V1k during the black suction purge, and regardless of the time from the start of the color suction purge, it is determined whether the voltage of the piezoelectric element 50 obtained by the voltage acquisition process reaches V1c during the color suction purge, and a signal corresponding thereto may be output. In this case, the condition that the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during the black suction purge reaches the voltage V1k corresponds to the "drain voltage condition" and the "first drain voltage condition" of the present invention. Also, the condition that the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during the color suction purge reaches the voltage V1c corresponds to the "drain voltage condition" and the "second drain voltage condition" of the present invention.

[0102] Further, in the abnormality detection process, a signal corresponding to the voltage of the piezoelectric element 50 during and after the suction purge may be output. For example, in Modification 1, when a cleaning instruction signal is received, the control unit 100 performs processing according to the flowchart of FIG. 12(a).

[0103] Specifically, the control unit 100 executes the processes of S201 to S205, which are the same as S101 to S105 in the above-described embodiment. After the completion of the color suction purge, the control unit 100 continues the voltage acquisition process until a predetermined time elapses (S206: NO). Here, the predetermined time is set to a time such that when a predetermined time has elapsed after the completion of the color suction purge, after the completion of the black suction purge, the time T2k has elapsed, and after the completion of the color suction purge, the time T2c has elapsed. Here, the time T2k and the time T2c may be the same length of time or different lengths of time.

[0104] After the completion of the color suction purge, when a predetermined time has elapsed (S206: YES), the control unit 100 executes the processes of S207 and S208, which are the same as S106 and S107 in the above-described embodiment.

[0105] However, in the abnormality detection process of S208, as shown in FIG. 12(b), the control unit 100 determines that the voltage of the piezoelectric element 50 corresponding to the nozzle 40 that discharges black ink, which is obtained in the voltage acquisition process, reaches the voltage V2k during the black suction purge, and after the completion of the black suction purge, it is maintained at or above the voltage V2k for a time T2k or more, and the voltage of the piezoelectric element 50 corresponding to the nozzle 40 that discharges color ink reaches the voltage V2c during the color suction purge, and after the completion of the color suction purge, it is maintained at or above the voltage V2c for a time T2c or more. In this case, a normal signal is output to display the normal screen 111 shown in FIG. 11(c) on the operation panel 99. Here, the voltage V2k may be the same voltage as the voltage V1k in the above-described embodiment, or may be a voltage different from the voltage V1k. Also, the voltage V2c may be the same voltage as the voltage V1c in the above-described embodiment, or may be a voltage different from the voltage V1c.

[0106] Further, in the abnormality detection process of S208, when the voltage of the piezoelectric element 50 corresponding to the nozzle 40 that discharges black ink does not reach the voltage V2k during the black suction purge, or although it reaches the voltage V2k during the black suction purge, it is not maintained at or above the voltage V2k for a time T2k or more after the completion of the black suction purge, and the voltage of the piezoelectric element 50 corresponding to the nozzle 40 that discharges color ink reaches the voltage V2c during the color suction purge, and after the completion of the color suction purge, it is maintained at or above the voltage V2c for a time T2c or more, the control unit 100 outputs an abnormality signal A1 to display the abnormality screen 112A shown in FIG. 11(d) on the operation panel 99.

[0107] Also, in the abnormality detection process of S208, when the voltage of the piezoelectric element 50 corresponding to the nozzle 40 that discharges black ink reaches the voltage V2k during the black suction purge, and after the completion of the black suction purge, it is maintained at the voltage V2k or higher for a time T2k or more, and the voltage of the piezoelectric element 50 corresponding to the nozzle 40 that discharges color ink does not reach the voltage V2c during the color suction purge, or although it reaches the voltage V2c during the color suction purge, it is not maintained at the voltage V2c or higher for a time T2c or more after the completion of the color suction purge, the control unit 100 outputs an abnormality signal A2 and causes the abnormality screen 112B shown in FIG. 11(e) to be displayed on the operation panel 99.

[0108] Also, in the abnormality detection process of S208, when the voltage of the piezoelectric element 50 corresponding to the nozzle 40 that discharges black ink does not reach the voltage V2k during the black suction purge, or although it reaches the voltage V2k during the black suction purge, it is not maintained at the voltage V2k or higher for a time T2k or more after the completion of the black suction purge, and the voltage of the piezoelectric element 50 corresponding to the nozzle 40 that discharges color ink does not reach the voltage V2c during the color suction purge, or although it reaches the voltage V2c during the color suction purge, it is not maintained at the voltage V2c or higher for a time T2c or more after the completion of the color suction purge, the control unit 100 outputs an abnormality signal A3 and causes the abnormality screen 112C shown in FIG. 11(f) to be displayed on the operation panel 99.

[0109] In addition, in Modification 1, the condition that the voltage of the piezoelectric element 50 corresponding to the nozzle 40 that discharges black ink reaches the voltage V2k during the black suction purge and is maintained at the voltage V2k or higher for a time T2k or longer after the completion of the black suction purge corresponds to the "voltage condition during drainage" and the "first voltage condition during drainage" of the present invention. Also, the condition that the voltage of the piezoelectric element 50 corresponding to the nozzle 40 that discharges color ink reaches the voltage V2c during the color suction purge and is maintained at the voltage V2c or higher for a time T2c or longer after the completion of the color suction purge corresponds to the "voltage condition during drainage" and the "second voltage condition during drainage" of the present invention. Further, the voltages V2k and V2c correspond to the "predetermined voltage" of the present invention. Also, the times T2k and T2c correspond to the "second time" of the present invention.

[0110] When the maintenance unit 8 is normal, even if the negative pressure pump 83 is stopped after the suction purge, for a while, the negative pressure in the flow path in the inkjet head 4 is maintained and the voltage generated in the piezoelectric element 50 is maintained. On the other hand, when there is an abnormality in at least a part of the maintenance unit 8, when the negative pressure pump 83 is stopped after the suction purge, it is difficult to maintain the negative pressure in the head flow path, and the voltage of the piezoelectric element 50 may immediately decrease.

[0111] Therefore, in Modification 1, by the voltage acquisition process, for black and color suction purges, the voltages of the piezoelectric element 50 during and after the suction purge are acquired. Then, when the voltage of the piezoelectric element 50 does not reach the voltage V2k during the black suction purge, or when the voltage of the piezoelectric element 50 reaches the voltage V2k during the black suction purge but the voltage of the piezoelectric element 50 is not maintained at V2k or higher for a time T2k or more after the black suction purge, an abnormal signal indicating that at least a part of the maintenance unit 8 is abnormal is output. Also, when the voltage of the piezoelectric element 50 does not reach the voltage V2c during the color suction purge, or when the voltage of the piezoelectric element 50 reaches the voltage V2c during the color suction purge but the voltage of the piezoelectric element 50 is not maintained at V2c or higher for a time T2c or more after the color suction purge, an abnormal signal indicating that at least a part of the maintenance unit 8 is abnormal is output. Thereby, it is possible to detect that there is an abnormality in at least a part of the maintenance unit 8 including the negative pressure pump 83 with a simple configuration.

[0112] Further, when the pump motor 83a of the negative pressure pump 83 outputs a drive state signal indicating its own drive state, in the abnormality detection process, a signal corresponding to the change in the voltage of the piezoelectric element 50 and the drive state signal may be output. For example, in Modification 2, as described above, the pump motor 83a of the negative pressure pump 83 outputs a drive state signal indicating its own drive state. Then, in Modification 2, when a cleaning instruction signal is received, the control unit 100 performs processing along the flowchart of FIG. 13(a).

[0113] Specifically, the control unit 100 executes the processes of S301 and S302 similar to S101 and S102 of the above-described embodiment. Subsequently, the control unit 100 starts the voltage acquisition process and the drive state signal acquisition process (S303). The voltage acquisition process is the same as that of the above-described embodiment. In the drive state signal acquisition process, the control unit 100 acquires the drive state signal output from the pump motor 83a.

[0114] Subsequently, the control unit 100 executes the processes of S304 and S305, which are the same as S104 and S105 in the above-described embodiment. Subsequently, the control unit 100 ends the voltage acquisition process and the drive state signal acquisition process (S306), and executes an abnormality detection process similar to S107 in the above-described embodiment (S307).

[0115] In the abnormality detection process of S307, the control unit 100 outputs a normal signal, an abnormal signal A1, an abnormal signal A2, and an abnormal signal A3 based on the change in the voltage of the piezoelectric element 50 acquired by the voltage acquisition process during the black suction purge and the change in the voltage of the piezoelectric element 50 acquired by the voltage acquisition process during the color suction purge, in the same manner as described in the above-described embodiment.

[0116] However, in the abnormality detection process of S307, unlike the above-described embodiment, when the abnormal signal A3 is output, as shown in FIG. 13(b), when the drive state signal acquired by the drive state signal acquisition process indicates that the pump motor 83a is being driven normally, an abnormal signal A3a is output as the abnormal signal A3, and as shown in FIG. 13(c), an abnormal screen 112C1 indicating that there is an abnormality in any of the switching unit 84, the portion other than the pump motor 83a of the negative pressure pump 83, and the common drain passage in the maintenance unit 8 is displayed on the operation panel 99. Here, the presence of an abnormality in the portion other than the pump motor 83a of the negative pressure pump 83 means, for example, that a foreign object is clogging the flow path in the negative pressure pump 83, the pump motor 83a is being driven normally, but the ink or air in the negative pressure pump 83 does not flow normally, or air leaks due to deterioration of the tube of the pressure pump 83, the pump motor 83a is being driven normally, but the ink or air in the negative pressure pump 83 does not flow normally. In the second modification, the condition that the drive state signal indicates that the pump motor 83a is being driven normally corresponds to the "drive signal condition" of the present invention.

[0117] Also, in the abnormality detection process of S307, when outputting the abnormal signal A3, if the drive state signal obtained in the drive state signal acquisition process during the suction purge processes of S304 and S305 indicates that the pump motor 83a is not driving normally, the abnormal signal A3b is output as the abnormal signal A3, and as shown in FIG. 13(d), an abnormal screen 112C2 indicating that there is an abnormality in the pump motor 83a among the maintenance units 8 is displayed on the operation panel 99.

[0118] Here, when there is an abnormality in the pump motor 83a, usually, the drive state signal obtained in the drive state signal acquisition process during both black and color suction purges indicates that the pump motor 83a is not driving normally. Therefore, in the abnormality detection process of S307, for example, when at least one of the drive state signals obtained by the drive state signal acquisition process for black and color suction purges indicates that the pump motor 83a is not driving normally, it is determined that the drive state signal indicates that the pump motor 83a is not driving normally. Alternatively, for example, when both of the drive state signals obtained by the drive state signal acquisition process for black and color suction purges indicate that the pump motor 83a is not driving normally, it is determined that the drive state signal indicates that the pump motor 83a is not driving normally.

[0119] In Modification 2, when the voltage of the piezoelectric element 50 does not reach the voltage V1k within the time T1k after the start of the black suction purge and does not reach the voltage V1c within the time T1c after the start of the color suction purge, the drive state signal determines whether the pump motor 83a is driving normally. Depending on the result, as the abnormal signal A3, an abnormal signal A3a indicating an abnormality in at least any one of the switching unit 84, the parts other than the pump motor 83a of the negative pressure pump 83, and the common drain flow path, or an abnormal signal A3b indicating an abnormality in the pump motor 83a is output. Thereby, it is possible to distinguish and detect whether there is an abnormality in the pump motor 83a or at least any one of the switching unit 84, the parts other than the pump motor 83a of the negative pressure pump 83, and the common drain flow path.

[0120] Also, in Modification 2, instead of the above, when the drive state signal indicates that the pump motor 83a is driving normally, an abnormal signal indicating an abnormality in at least any one of the switching unit 84 and the tube 19c may be output as the abnormal signal A3. Further, when the drive state signal indicates that there is an abnormality in the pump motor 83a, an abnormal signal indicating an abnormality in the negative pressure pump 83 may be output as the abnormal signal A3.

[0121] Also, in the above-described embodiment, when the control unit 100 receives the cleaning instruction signal, it executes a process for determining whether there is an abnormality in the maintenance unit 8, but it is not limited to this.

[0122] In Modification 3, when the control unit 100 receives an inspection instruction signal instructing to inspect a plurality of nozzles 40 of the inkjet head 4, the control unit 100 performs processing according to the flowchart of FIG. 14. For example, when an operation for instructing the inspection of the nozzles 40 is performed by the user on the operation panel 99, the operation panel 99 transmits the inspection instruction signal, and the control unit 100 receives this inspection instruction signal. Alternatively, for example, when a preset time is reached, the control unit 100 receives the inspection instruction signal.

[0123] Referring to the flowchart of FIG. 14 in detail, when the inspection instruction signal is received, the control unit 100 first executes the ejection inspection process (S401). In the ejection inspection process, the control unit 100 controls the carriage motor 106, the cap lifting mechanism 109, etc. to set the above cap state, controls the high-voltage power supply circuit 92 to apply a predetermined voltage to the electrode 91, and then controls the driver IC 108 to perform inspection driving for each of the plurality of nozzles 40 of the inkjet head 4. Then, based on the signal output from the signal processing circuit 93 during the inspection driving for each nozzle 40, ejection inspection information regarding whether the nozzle 40 is an abnormal nozzle is stored in the memory 104.

[0124] Subsequently, the control unit 100 determines whether the number N1 of abnormal nozzles is equal to or greater than a predetermined number N1a based on the ejection inspection information stored in the memory 104 (S402). Here, the predetermined number N1a may be one or two or more.

[0125] If the number N1 of abnormal nozzles is less than the predetermined number N1a (S402: NO), the process ends. If the number N1 of abnormal nozzles is equal to or greater than the predetermined number N1a (S402: YES), the control unit 100 determines the piezoelectric element 50 corresponding to any normal nozzle that is not an abnormal nozzle among the nozzles 40 that eject black ink, and the piezoelectric element 50 corresponding to any normal nozzle that is not an abnormal nozzle among the nozzles 40 that eject color ink, as the piezoelectric element 50 for obtaining the voltage in the voltage acquisition process (S403). Subsequently, the control unit 100 executes the processes of S404 to S408, which are the same as S101 to S105 of the above-described embodiment. Also, in the voltage acquisition process starting from S404, the control unit 100 acquires the voltage of the piezoelectric element 50 determined in S403.

[0126] When there are no abnormal nozzles or when the number of abnormal nozzles is small, the maintenance unit 8 is normal, and ink has been sufficiently discharged by the previous suction purge, so there is a high possibility that the abnormal nozzles have recovered. On the other hand, when the number of abnormal nozzles is large, since there is an abnormality in at least a part of the maintenance unit 8, there is a possibility that the ink has not been sufficiently discharged by the previous suction purge.

[0127] Therefore, in Modification 3, when the number N1 of abnormal nozzles is equal to or greater than a predetermined number N1a, black and color suction purges are performed, and the voltage of the piezoelectric element 50 is acquired during each suction purge. Then, based on the acquired voltage, an abnormality detection process is executed. As a result, if the maintenance unit 8 is normal, the abnormal nozzles can be recovered by the suction purge, and if there is an abnormality in at least a part of the maintenance unit, this can be detected.

[0128] Also, in Modification 3, during the black and color suction purges, the voltage of the piezoelectric element 50 corresponding to any normal nozzle among the nozzles 40 that discharge black and color ink, which is not an abnormal nozzle, is acquired respectively. Thereby, for example, it is possible to prevent erroneously detecting that there is an abnormality in at least a part of the maintenance unit 8 based on the voltage of the abnormal piezoelectric element 50.

[0129] In Modification 4, when a test instruction signal is received, the control unit 100 performs processing according to the flowchart of FIG. 15. Specifically, when a test instruction signal is received, the control unit 100 executes a first ejection test process similar to the ejection test process of S401 in Modification 4 (S501). Also, in the first ejection test process, the first ejection test information is stored in the memory 104 as ejection test information. Subsequently, the control unit 100 determines whether the number N1 of abnormal nozzles is equal to or greater than a predetermined number N1a based on the first ejection test information stored in the memory 104, similar to S402 in Modification 4 (S502). If the number N1 of abnormal nozzles is less than the predetermined number N1a (S502: NO), the process ends.

[0130] When the number N1 of abnormal nozzles is equal to or greater than a predetermined number N1a (S502: YES), the control unit 100 then determines whether or not abnormal detection flag information is stored in the memory 104 (S503). The abnormal detection flag is stored in the memory 104 in S514, which will be described later, when processing is performed according to the flowchart of FIG. 15 in the past.

[0131] When the abnormal detection flag information is not stored in the memory 104 (S503: NO), the control unit 100 executes a suction purge process (S504). In the suction purge process of S504, the control unit 100 executes at least one of a black purge process and a color purge process. More specifically, when the first ejection inspection information indicates that the nozzle 40 that ejects any black ink is an abnormal nozzle, in the purge process of S504, the control unit 100 executes the black purge process. Also, when the first ejection inspection information indicates that the nozzle 40 that ejects any color ink is an abnormal nozzle, in the purge process of S504, the control unit 100 executes the color purge process. Then, after the purge process of S504, the process proceeds to S512.

[0132] When the abnormal detection flag information is stored in the memory 104 (S503: YES), the control unit 100 executes processes S505 to S510 similar to S403 to S408 of Modification 4. Subsequently, the control unit 100 deletes the abnormal detection flag information stored in the memory 104 (S511), and the process proceeds to S512.

[0133] In S512, the control unit 100 executes a second ejection inspection process. In the second ejection inspection process, the control unit 100 causes the inkjet head 4 to perform inspection driving in the same manner as in the first ejection inspection process for the nozzle 40 for which it is stored in the memory 104 that it is an abnormal nozzle in at least the first ejection inspection process of S501, and stores second ejection inspection information in the memory 104 as ejection inspection information.

[0134] Subsequently, the control unit 100 determines whether the ratio [N2 / N1] of the number N2 of abnormal nozzles indicated by the second discharge inspection information to the number N1 of abnormal nozzles indicated by the first discharge inspection information is less than a predetermined ratio Ra (S513). The smaller the ratio [N2 / N1], the higher the ratio of abnormal nozzles recovered by the suction purge in S504 or the suction purges in S507 and S508. Note that, in Modification 4, the condition that the ratio [N2 / N1] is equal to or greater than the predetermined ratio Ra corresponds to the "difference condition" of the present invention.

[0135] If the ratio [N2 / N1] is less than the predetermined ratio Ra (S513: YES), the process ends as it is. If the ratio [N2 / N1] is equal to or greater than the predetermined ratio Ra (S513: NO), the abnormality detection flag information is stored in the memory 104 (S514), and the process ends.

[0136] In Modification 4, when the number N1 of abnormal nozzles indicated by the first discharge inspection information is equal to or greater than a predetermined number N1a and the abnormality detection flag information is stored in the memory 104, a black suction purge and a color suction purge are performed, and the voltage of the piezoelectric element 50 is acquired during each suction purge. Then, based on the acquired voltage, an abnormality detection process is executed. Thereby, if the maintenance unit 8 is normal, the abnormal nozzles can be recovered by the suction purge, and if there is an abnormality in at least a part of the maintenance unit, it can be detected.

[0137] Furthermore, in Modification 4, subsequently, a second discharge inspection process is executed. At this time, if the maintenance unit 8 is normal, most of the abnormal nozzles are recovered by the above-described suction purge, and the ratio [N2 / N1] is likely to be small. On the other hand, if there is an abnormality in at least a part of the maintenance unit 8, there are many abnormal nozzles that cannot be recovered by the above-described suction purge, and the ratio [N2 / N1] is likely to be large.

[0138] Therefore, in Modification 4, when the ratio [N2 / N1] is equal to or greater than a predetermined ratio Ra, the abnormality detection flag information is stored in the memory 104. As a result, when there is a high possibility that at least a part of the maintenance unit 8 is abnormal, when the suction purge is performed next, the voltage of the piezoelectric element 50 is acquired, and based on the acquired voltage, it is possible to detect whether or not at least a part of the maintenance unit 8 is abnormal. On the other hand, when the ratio [N2 / N1] is less than the predetermined ratio Ra, the abnormality detection flag information is not stored in the memory 104. As a result, when it is highly possible that the maintenance unit 8 is normal, at the time of the next suction purge, the acquisition of the voltage of the piezoelectric element 50 and the detection of whether or not at least a part of the maintenance unit 8 is abnormal are not performed, and the processing can be simplified.

[0139] Further, in Modification 4, the condition that the ratio [N2 / N1] is equal to or greater than the predetermined ratio Ra is used as the differential condition, but another condition regarding the difference between the number N1 of abnormal nozzles and the number N2 of abnormal nozzles may be used as the differential condition. For example, a condition that the value [N1 - N2] obtained by subtracting the number N2 of abnormal nozzles indicated by the second ejection inspection information from the number N1 of abnormal nozzles indicated by the first ejection inspection information is less than a predetermined value may be used as the differential condition.

[0140] Further, in Modification 4, the next suction purge after the abnormality flag detection information is stored in the memory 104 is described as being the suction purge in S507 and S508 that is performed when the number N1 of abnormal nozzles indicated by the first ejection inspection information is equal to or greater than a predetermined number N1a in the flowchart of FIG. 15, but this is not limited thereto. The next suction purge after the abnormality flag detection information is stored in the memory 104 may be a suction purge performed at a different timing.

[0141] Further, in Modifications 3 and 4, similar to the above-described embodiments, during the black and color suction purges, the voltages of the piezoelectric elements 50 corresponding to the nozzles 40 set regardless of the result of the ejection inspection process among the nozzles 40 that eject black and color inks may be acquired.

[0142] Also, in the above-described embodiments and Modifications 1 and 2, when sucking and purging black and color, the voltage of the piezoelectric element 50 corresponding to any normal nozzle that is not an abnormal nozzle may be acquired. In this case, based on the result of the ejection inspection process performed before performing the process along the flowcharts of FIGS. 11(a), 12(a), and 13, the piezoelectric element 50 corresponding to any normal nozzle that is not an abnormal nozzle is determined.

[0143] Also, in the above-described embodiments and Modifications 1 and 2, in which the voltage of the piezoelectric element 50 set regardless of the result of the ejection inspection process is acquired during sucking and purging of black and color, the ejection inspection unit 90 may not be provided.

[0144] Also, in the above-described embodiments and Modifications 1 and 2, when receiving a cleaning instruction signal, the exhaust purge process for black and color may not be executed. When the exhaust purge process for black and color is not executed when receiving a cleaning instruction signal in the above-described embodiments and Modifications 1 and 2, and in Modifications 3 and 4, the printer 1 may not include a configuration for performing an exhaust purge, such as the exhaust flow path 66, the exhaust unit 67, and the exhaust cap 82.

[0145] Also, in Modifications 3 and 4, when the number of abnormal nozzles is particularly large, for example, before starting the voltage acquisition process or before executing the sucking and purging process, the exhaust purge process for black and color may be executed.

[0146] Also, in a printer capable of performing an exhaust purge, such as the printer 1 of the above-described embodiment, it may be detected that there is an abnormality in the maintenance unit 8 based on the change in the voltage of the piezoelectric element 50 during sucking and purging and the change in the voltage of the piezoelectric element 50 during exhaust purging.

[0147] For example, in Modification 5, when receiving a cleaning instruction signal, the control unit 100 performs processing along the flowchart of FIG. 16(a).

[0148] Specifically, when receiving a cleaning instruction signal, the control unit 100 starts a voltage acquisition process (S601), and then executes the processes of S602 to S605 similar to S101, S102, S104, and 105 in the above-described embodiment.

[0149] Also, in the voltage acquisition process started in S601, during the black exhaust purge in S602, the voltage of the piezoelectric element 50 corresponding to any of the nozzles 40 that discharges black ink is acquired. Also, in the voltage acquisition process started in S601, during the color exhaust purge in S603, the voltage of the piezoelectric element 50 corresponding to any of the nozzles 40 that discharges color ink is acquired. Note that in Modification 5, the black and color exhaust purge processes correspond to the "exhaust process" of the present invention. Also, among the voltage acquisition processes, the processes performed during the black and color exhaust purge processes correspond to the "voltage acquisition process during exhaust" of the present invention.

[0150] Also, in Modification 5, among the voltage acquisition processes started in S601, the processes performed during the black suction purge in S604 and the color suction purge in S605 are the same as those in the above-described embodiment. And among the voltage acquisition processes, the processes performed during the black and color suction purge processes correspond to the "voltage acquisition process during liquid discharge" of the present invention.

[0151] Subsequently, the control unit 100 ends the voltage acquisition process (S606) and executes an abnormality detection process (S607). In the abnormality detection process of S607, as shown in FIG. 16(b), the control unit 100 outputs a signal according to whether there is an abnormality in the change in the voltage of the piezoelectric element 50 acquired by the voltage acquisition process during suction purge and whether there is an abnormality in the change in the voltage of the piezoelectric element 50 acquired by the voltage acquisition process during exhaust purge.

[0152] Specifically, in Modification 5, that there is no abnormality in the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during suction purge means that the voltage of the piezoelectric element 50 reaches the voltage V1k within the time T1k from the start of black suction purge, and the voltage of the piezoelectric element 50 reaches the voltage V1c within the time T1c from the start of color suction purge.

[0153] Also, in Modification 5, that there is an abnormality in the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during suction purge means that the voltage of the piezoelectric element 50 does not reach the voltage V1k within the time T1k from the start of black suction purge, or the voltage of the piezoelectric element 50 does not reach the voltage V1c within the time T1c from the start of color suction purge.

[0154] Also, in Modification 5, that there is no abnormality in the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during exhaust purge means that the voltage of the piezoelectric element 50 reaches the voltage V3k within the time T3k from the start of black exhaust purge, and the voltage of the piezoelectric element 50 reaches the voltage V3c within the time T3c from the start of color exhaust purge. Here, the voltage V3k is, for example, a voltage lower than the voltage V1k, and the voltage V3c is, for example, a voltage lower than the voltage V1c.

[0155] Also, in Modification 5, that there is an abnormality in the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during exhaust purge means that the voltage of the piezoelectric element 50 does not reach the voltage V3k within the time T3k from the start of black exhaust purge, or the voltage of the piezoelectric element 50 does not reach the voltage V3c within the time T3c from the start of color exhaust purge.

[0156] However, the criteria for determining whether there is an abnormality in the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during suction purge and the criteria for determining whether there is an abnormality in the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during exhaust purge are not limited to those described above. For example, from the same perspective as Modification 1, whether the voltage of the piezoelectric element reaches a predetermined voltage during suction purge and whether the voltage of the piezoelectric element 50 is maintained at or above the predetermined voltage for a predetermined time or more after suction purge may be used as the criteria for determining whether there is an abnormality in the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during suction purge. Also, whether the voltage of the piezoelectric element reaches a predetermined voltage during exhaust purge and whether the voltage of the piezoelectric element 50 is maintained at or above the predetermined voltage for a predetermined time or more after exhaust purge may be used as the criteria for determining whether there is an abnormality in the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during exhaust purge.

[0157] When there is no abnormality in the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during suction purge and there is no abnormality in the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during exhaust purge, the control unit 100 outputs a normal signal and causes the normal screen 111 shown in FIG. 11(c) similar to the above-described embodiment to be displayed on the operation panel 99.

[0158] When there is an abnormality in the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during suction purge and there is no abnormality in the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during exhaust purge, the control unit 100 outputs an abnormal signal A. At this time, the control unit 100 outputs any one of the abnormal signals A1 to A3 described in the above embodiment as the abnormal signal A according to the mode of the abnormality in the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during suction purge.

[0159] Specifically, as shown in Fig. 16(c), if there is an abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during the black suction purge, and there is no abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during the color suction purge, the control unit 100 outputs an abnormal signal A1 as the abnormal signal A, and causes the operation panel 99 to display an abnormal screen 112A shown in Fig. 11(d) similar to the above-described embodiment.

[0160] Also, if there is no abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during the black suction purge, and there is an abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during the color suction purge, the control unit 100 outputs an abnormal signal A2 as the abnormal signal A, and causes the operation panel 99 to display an abnormal screen 112B shown in Fig. 11(e) similar to the above-described embodiment.

[0161] Also, if there is an abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during the black suction purge, and there is an abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during the color suction purge, the control unit 100 outputs an abnormal signal A3 as the abnormal signal A, and as shown in Fig. 17(a), causes the operation panel 99 to display an abnormal screen 112D indicating that there is an abnormality in either the switching unit 84 or the negative pressure pump 83 among the maintenance units 8.

[0162] Also, if there is no abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during the suction purge, and there is an abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during the exhaust purge, the control unit 100 outputs an abnormal signal B. At this time, the control unit 100 outputs one of the abnormal signals B1 to B3 as the abnormal signal B according to the abnormal mode of the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during the exhaust purge.

[0163] Specifically, as shown in Fig. 16(d), if there is an abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during black exhaust purge, and there is no abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during color exhaust purge, the control unit 100 outputs an abnormality signal B1 as the abnormality signal B, and as shown in Fig. 17(b), an abnormality screen 113A indicating an abnormality in the black shaft 86 of the maintenance unit 8 is displayed on the operation panel 99.

[0164] Here, the black shaft 86 refers to the shaft 86 corresponding to the exhaust passage 66 communicating with the passage through which the black ink flows. Also, an abnormality in the black shaft 86 means, for example, that the shaft 86 is broken and the corresponding valve 68 cannot be opened.

[0165] If there is no abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during black exhaust purge, and there is an abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during color exhaust purge, the control unit 100 outputs an abnormality signal B2 as the abnormality signal B, and as shown in Fig. 17(c), an abnormality screen 113B indicating an abnormality in the color shaft 86 of the maintenance unit 8 is displayed on the operation panel 99.

[0166] Here, the color shaft 86 refers to the three shafts 86 corresponding to the three exhaust passages 66 communicating with the passage through which the color ink flows. Also, an abnormality in the color shaft 86 means, for example, that any of the three shafts 86 is broken and the corresponding valve 68 cannot be opened.

[0167] When there is an abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during black exhaust purge, and there is an abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during color exhaust purge, the control unit 100 outputs an abnormality signal B3 as an abnormality signal B, and as shown in FIG. 17(d), causes the operation panel 99 to display an abnormality screen 113C indicating that there is an abnormality in either the exhaust cap 82 or the exhaust passage in the maintenance unit 8. Here, the exhaust passage refers to a passage such as the tube 19c through which ink flows during black and color exhaust purges and through which ink does not flow during black and color suction purges.

[0168] An abnormality in the exhaust cap 82 means, for example, that there is a crack in the exhaust cap 82, or that the exhaust cap 82 is clogged with foreign substances such as paper dust and fragments of the recording paper S. Further, an abnormality in the exhaust passage means, for example, that the tube 19c is bent, that the tube 19c is clogged with solidified ink or foreign substances, so that the flow path in the tube 19c is blocked, that a crack has occurred in the connection part of the tube 19c, or that the tube 19a has come off. Even if it is other than the factors described above, anything that affects the change in the suction pressure during suction purge is considered an abnormality, and it also includes abnormalities related to the blockage of the system to which pressure is applied and abnormalities in which the pressure increase is inhibited by the inflow of gas.

[0169] When there is an abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during suction purge, and there is an abnormality in the voltage change of the piezoelectric element 50 obtained by the voltage acquisition process during exhaust purge, the control unit 100 outputs an abnormality signal C, and as shown in FIG. 17(e), causes the operation panel 99 to display an abnormality screen 114 indicating that there is an abnormality in either the negative pressure pump 83, the switching unit 84, or the drain / exhaust common flow path in the maintenance unit 8. Here, the drain / exhaust common flow path refers to a passage such as the tube 19d through which ink flows during both black and color suction purges and exhaust purges.

[0170] Regarding the abnormalities of the negative pressure pump 83 and the switching unit 84, they are the same as those described in the above-described embodiment. An abnormality in the drainage / vent common flow path means, for example, that the tube 19d is bent, the ink or foreign matter solidified in the tube 19d is clogged, etc., so that the flow path in the tube 19d is blocked, a crack occurs in the connection part of the tube 19d, or the tube 19d is disconnected. Even if it is other than the above-described content, anything that affects the change in the suction pressure during the suction purge is considered an abnormality, including an abnormality related to the blockage of the system to which pressure is applied and an abnormality in which the pressure increase is inhibited by the inflow of gas.

[0171] Here, as described in the above-described embodiment, when the black suction purge is normally performed, the voltage of the piezoelectric element 50 reaches the voltage V1k within the time T1k after the start of the black suction purge. On the other hand, when the black suction purge is not normally performed, the voltage of the piezoelectric element 50 may not reach the voltage V1k, or the time from the start of the black suction purge until the voltage of the piezoelectric element 50 reaches the voltage V1k may exceed the time T1k.

[0172] Also, when the color suction purge is normally performed, the voltage of the piezoelectric element 50 reaches the voltage V1c within the time T1k after the start of the color suction purge. On the other hand, when the color suction purge is not normally performed, the voltage of the piezoelectric element 50 may not reach the voltage V1c, or the time from the start of the color suction purge until the voltage of the piezoelectric element 50 reaches the voltage V1c may exceed the time T1c.

[0173] Also, when the black exhaust purge is performed normally, the pressure in the plurality of pressure chambers 41 corresponding to the plurality of nozzles 40 that discharge black ink becomes negative pressure, so that the voltage of the corresponding piezoelectric element 50 changes. Then, the voltage of the piezoelectric element 50 reaches the voltage V3k within the time T3k after the black exhaust purge is started. On the other hand, when the black exhaust purge is not performed normally, the voltage of the piezoelectric element 50 may not reach the voltage V3k, or the time from when the black exhaust purge is started until the voltage of the piezoelectric element 50 reaches the voltage V3k may exceed the time T3k.

[0174] Similarly, when the color exhaust purge is performed normally, the pressure in the plurality of pressure chambers 41 corresponding to the plurality of nozzles 40 that discharge color ink becomes negative pressure, so that the voltage of the corresponding piezoelectric element 50 changes. Then, the voltage of the piezoelectric element 50 reaches the voltage V3c within the time T3c after the color exhaust purge is started. On the other hand, when the color exhaust purge is not performed normally, the voltage of the piezoelectric element 50 may not reach the voltage V3c, or the time from when the color suction purge is started until the voltage of the piezoelectric element 50 reaches the voltage V3c may exceed the time T3c.

[0175] From these, when there is no abnormality in the change in the voltage of the piezoelectric element 50 during the suction purge and there is no abnormality in the change in the voltage of the piezoelectric element 50 during the exhaust purge, there is a high possibility that the maintenance unit 8 is normal. Therefore, in this case, a normal signal indicating that the maintenance unit 8 is normal is output.

[0176] Also, when there is an abnormality in the change in the voltage of the piezoelectric element 50 during the suction purge and there is no abnormality in the change in the voltage of the piezoelectric element 50 during the exhaust purge, there is a high possibility that there is an abnormality in the part of the maintenance unit 8 related to the suction purge. Therefore, in this case, an abnormal signal A indicating that there is an abnormality in at least any one of the first and second nozzle caps 81a and 81b, the drain flow path, and the switching unit 84 related to the suction purge in the maintenance unit 8 is output.

[0177] Furthermore, at this time, based on whether there is an abnormality in the voltage change of the piezoelectric element 50 during black suction purge and whether there is an abnormality in the voltage change of the piezoelectric element 50 during color suction purge, any one of the abnormal signals A1, A2, and A3 for causing the operation panel 99 to display the abnormal screens 112A, 112B, and 112D respectively is output as the abnormal signal A.

[0178] Also, when there is no abnormality in the voltage change of the piezoelectric element 50 during suction purge but there is an abnormality in the voltage change of the piezoelectric element 50 during exhaust purge, there is a high possibility that there is an abnormality in the part of the maintenance unit 8 related to exhaust purge. Therefore, in this case, an abnormal signal B indicating that there is an abnormality in at least any one of the exhaust cap 82, the exhaust flow path, and the switching unit 84, which are related to exhaust purge in the maintenance unit 8, is output.

[0179] Furthermore, at this time, based on whether there is an abnormality in the voltage change of the piezoelectric element 50 during black exhaust purge and whether there is an abnormality in the voltage change of the piezoelectric element 50 during color exhaust purge, any one of the abnormal signals B1, B2, and B3 for causing the operation panel 99 to display the abnormal screens 113A, 113B, and 113C respectively is output as the abnormal signal B.

[0180] Also, when there is an abnormality in the voltage change of the piezoelectric element 50 during suction purge and there is an abnormality in the voltage change of the piezoelectric element 50 during exhaust purge, there is a high possibility that there is an abnormality in the part of the maintenance unit 8 related to both suction purge and exhaust purge. Therefore, in this case, an abnormal signal C indicating that there is an abnormality in at least any one of the switching unit 84, the negative pressure pump 83, and the tube 19d, which are related to both suction purge and exhaust purge in the maintenance unit 8, is output.

[0181] Alternatively, without obtaining the voltage of the piezoelectric element 50 during suction purge, it may be determined whether there is an abnormality in the maintenance unit 8 based on the voltage of the piezoelectric element 50 during exhaust purge. In this case, compared with the case of Modification 5, since the voltage of the piezoelectric element 50 during suction purge is not obtained, the processing for detecting whether there is an abnormality in at least a part of the maintenance unit 8 can be simplified.

[0182] For example, in Modification 6, when the cleaning instruction signal is received, the control unit 100 performs processing according to the flowchart of FIG. 18(a). Specifically described, when the cleaning instruction signal is received, the control unit 100 starts the voltage acquisition process (S701), executes the black exhaust purge process (S702), and executes the color exhaust purge process (S703). Subsequently, the control unit 100 ends the voltage acquisition process (S704) and executes the abnormality detection process (S705). Then, after the abnormality detection process in S705, the control unit 100 executes the black suction purge process (S706), and subsequently executes the color suction purge process (S707).

[0183] In the abnormality detection process of S705, the control unit 100 outputs a signal according to the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during the black exhaust purge and the change in the voltage of the piezoelectric element 50 obtained by the voltage acquisition process during the color exhaust purge.

[0184] Specifically, as shown in FIG. 18(b), within time T3k after the start of the black exhaust purge, the voltage of the piezoelectric element 50 obtained by the voltage acquisition process reaches voltage V3k, and within time T3c after the start of the color exhaust purge, the voltage of the piezoelectric element 50 obtained by the voltage acquisition process reaches voltage V3c. In this case, the control unit 100 outputs a normal signal to the operation panel 99 to cause the operation panel 99 to display the normal screen 111 shown in FIG. 11(c) similar to the above-described embodiment.

[0185] Also, if the voltage of the piezoelectric element 50 obtained by the voltage acquisition process does not reach V3k within the time T3k after the start of the black exhaust purge, and the voltage of the piezoelectric element 50 obtained by the voltage acquisition process reaches V3c within the time T3c after the start of the color exhaust purge, the control unit 100 outputs an abnormal signal B1 to the operation panel 99, thereby causing the operation panel 99 to display an abnormal screen 113A shown in FIG. 17(b) similar to Modification 5.

[0186] Also, if the voltage of the piezoelectric element 50 obtained by the voltage acquisition process reaches V3k within the time T3k after the start of the black exhaust purge, and the voltage of the piezoelectric element 50 obtained by the voltage acquisition process does not reach V3c within the time T3c after the start of the color exhaust purge, the control unit 100 outputs an abnormal signal B2 to the operation panel 99, thereby causing the operation panel 99 to display an abnormal screen 113B shown in FIG. 17(c) similar to Modification 5.

[0187] Also, if the voltage of the piezoelectric element 50 obtained by the voltage acquisition process does not reach V3k within the time T3k after the start of the black exhaust purge, and the voltage of the piezoelectric element 50 obtained by the voltage acquisition process does not reach V3c within the time T3c after the start of the color exhaust purge, the control unit 100 outputs an abnormal signal B3 to the operation panel 99, and as shown in FIG. 18(c), causes the operation panel 99 to display an abnormal screen 113D indicating that there is an abnormality in any one of the exhaust cap 82, the exhaust passage 66, the switching unit 84, and the negative pressure pump 83 in the maintenance unit 8.

[0188] In Modification 6, when the voltage of the piezoelectric element 50 does not reach the voltage V3k within the time T3k after the start of the black exhaust purge, and when the voltage of the piezoelectric element 50 does not reach the voltage V3c within the time T3c after the start of the color exhaust purge, an abnormal signal indicating that at least a part of the maintenance unit 8 is abnormal is output. Thereby, it is possible to detect that there is an abnormality in at least a part of the maintenance unit 8 including the negative pressure pump 83 with a simple configuration.

[0189] Also, in Modification 6, after the abnormality detection process of S705, the process may end without performing the black suction purge process of S706 and the color suction purge process of S707.

[0190] Also, in Modifications 5 and 6, for example, from the same viewpoint as in Modification 1, whether the voltage of the piezoelectric element reaches a predetermined voltage during the exhaust purge and whether the voltage of the piezoelectric element 50 is maintained at or above the predetermined voltage for a predetermined time or more after the exhaust purge may be used as a condition for determining whether there is an abnormality in at least a part of the maintenance unit 8.

[0191] Also, in the above-described embodiments and Modifications 1 to 5, different abnormality signals are output when the first drainage voltage condition is satisfied and the second drainage voltage condition is not satisfied, when the first drainage voltage condition is not satisfied and the second drainage voltage condition is satisfied, and when neither the first drainage voltage condition nor the second drainage voltage condition is satisfied. However, the present invention is not limited to this. For example, the same abnormality signal may be output in these three cases. In this case, the condition of satisfying at least one of the first drainage voltage condition and the second drainage voltage condition corresponds to the "drainage voltage condition" of the present invention.

[0192] Also, in the above examples, the first nozzle cap 81a that covers the nozzle 40 that discharges black ink and the second nozzle cap 81b that covers the nozzle 40 that discharges color ink are provided separately, and black suction purge and color suction purge can be performed separately. However, the present invention is not limited to this. For example, it may have a nozzle cap that covers all the nozzles 40 of the inkjet head 4. Then, by driving the pump motor 83a of the negative pressure pump 83 with a plurality of nozzles 40 covered by the nozzle cap, a suction purge for discharging the ink in the inkjet head 4 from the plurality of nozzles 40 may be performed. And in this case, when the voltage of the piezoelectric element 50 during or after the suction purge does not satisfy the drainage voltage condition, an abnormality signal indicating that there is an abnormality in at least a part of the maintenance unit 8 may be output.

[0193] Also, in Modifications 5 and 6, different abnormal signals were output when the voltage condition at the first exhaust was satisfied but the voltage condition at the second exhaust was not satisfied, when the voltage condition at the first exhaust was not satisfied but the voltage condition at the second exhaust was satisfied, and when the voltage condition at the first exhaust was not satisfied and the voltage condition at the second exhaust was not satisfied. However, this is not limitative. For example, the same abnormal signal may be output in these three cases. In this case, the condition of satisfying at least one of the voltage condition at the first exhaust and the voltage condition at the second exhaust corresponds to the "voltage condition at exhaust" of the present invention.

[0194] Also, in the above example, the shaft 86 corresponding to the exhaust passage 66 through which black ink flows and the three shafts 86 corresponding to the exhaust passage 66 through which color ink flows can be moved up and down separately, and black exhaust purge and color exhaust purge can be performed separately. However, this is not limitative. For example, the four shafts 86 may be connected to each other and be integrally movable up and down. Then, in the above cap state, after raising the four shafts 86 to open the four valves 68, by driving the pump motor 83a of the negative pressure pump 83, an exhaust purge for discharging the gas in the four exhaust passages 66 to the exhaust cap 82 may be performed. And in this case, when the voltage of the piezoelectric element 50 during or after the exhaust purge does not satisfy the voltage condition at exhaust, an abnormal signal indicating that there is an abnormality in at least a part of the maintenance unit 8 may be output.

[0195] Also, the above example relates to the printer 1 capable of performing suction purge by the maintenance unit 8 provided with the negative pressure pump 83, but this is not limitative.

[0196] In Modification 7, as shown in FIG. 19, the printer 150 includes a positive pressure pump 151 and an ink receiving portion 152 instead of the maintenance unit 8 of the printer 1. Also, the printer 150 does not have a configuration for exhaust purge such as an exhaust flow path. However, the printer 150 may be provided with a configuration for exhaust purge. Since the other configurations of the printer 150 are substantially the same as those of the printer 1, the description thereof is omitted here. In Modification 7, the ink receiving portion 152 corresponds to the "liquid receiving portion" of the present invention.

[0197] The positive pressure pump 151 is provided for the four tubes 17 and applies a positive pressure to the ink in each tube 17. The ink receiving portion 152 is provided at the position in the printer 150 where the nozzle cap unit 81 is disposed in the printer 1. Thereby, when the carriage 2 is moved to the maintenance position, a plurality of nozzles 40 of the ink jet head 4 face the ink receiving portion 152.

[0198] Then, in Modification 7, with the carriage 2 positioned at the maintenance position, a positive pressure purge can be performed in which the positive pressure pump 151 applies a positive pressure to the ink in the four tubes 17 to discharge the ink in the ink jet head 4 from the plurality of nozzles 40 to the ink receiving portion 152.

[0199] In Modification 7, when a cleaning instruction signal is received, the control unit 100 performs processing along the flowchart of FIG. 20(a).

[0200] Specifically, when receiving a cleaning instruction signal, the control unit 100 starts a voltage acquisition process (S801). Subsequently, the control unit 100 executes a positive pressure purge process (S802). In the positive pressure purge process, the control unit 100 controls the carriage motor 106, the positive pressure pump 151, etc. to perform a positive pressure purge. In Modification 7, the positive pressure purge process corresponds to the "liquid discharge process" of the present invention. Also, when the positive pressure purge is performed normally, the ink in the plurality of pressure chambers 41 becomes positive pressure, so that the portion covering the plurality of pressure chambers 41 of the piezoelectric layer 52 deforms, and a voltage is generated in the piezoelectric layer 52. In the voltage acquisition process started in S801, the voltage generated in the piezoelectric element 50 due to the voltage generated in the piezoelectric layer 52 is acquired.

[0201] Subsequently, the control unit 100 ends the voltage acquisition process (S803) and executes an abnormality detection process (S804). In the abnormality detection process, as shown in FIG. 20(a), when the voltage of the piezoelectric element 50 acquired in the voltage acquisition process reaches the voltage V4 within the time T4 after the start of the exhaust purge, the control unit 100 outputs a normal signal to the operation panel 99, so that, as shown in FIG. 20(b), a normal screen 115 indicating that the positive pressure pump 151 is normal is displayed on the operation panel 99.

[0202] Also, when the voltage of the piezoelectric element 50 acquired in the voltage acquisition process does not reach the voltage V4 within the time T4 after the start of the exhaust purge, the control unit 100 outputs an abnormal signal to the operation panel 99, so that, as shown in FIG. 20(c), an abnormal screen 116 indicating that there is an abnormality in the positive pressure pump 151 is displayed on the operation panel 99.

[0203] When the positive pressure purge is performed normally, the pressure in the plurality of pressure chambers 41 corresponding to the plurality of nozzles 40 becomes a positive pressure, so that the piezoelectric element 50 forming the wall of the pressure chamber 41 is deformed and the voltage of the piezoelectric element 50 changes. Then, the voltage of the piezoelectric element 50 reaches the voltage V4 within the time T4 after the start of the positive pressure purge. On the other hand, when the positive pressure purge is not performed normally, the voltage of the piezoelectric element 50 may not reach the voltage V4, or the time from the start of the positive pressure purge until the voltage of the piezoelectric element 50 reaches the voltage V4 may exceed the time T4.

[0204] Therefore, in the present embodiment, when the voltage of the piezoelectric element 50 does not reach the voltage V4 within the time T4 after the start of the positive pressure purge, an abnormal signal indicating that there is an abnormality in the positive pressure pump 151 is output. Thereby, it is possible to detect that there is an abnormality in the positive pressure pump 151 with a simple configuration.

[0205] In addition, in Modification 7, whether to output a normal signal or an abnormal signal is determined based on whether or not the condition that the voltage of the piezoelectric element 50 reaches the voltage V4 within the time T4 after the start of the positive pressure purge is satisfied, but the present invention is not limited to this.

[0206] For example, regardless of the time after the start of the positive pressure purge, whether to output a normal signal or an abnormal signal may be determined based on whether or not the condition that the voltage of the piezoelectric element 50 reaches the voltage V4 during the positive pressure purge is satisfied. Alternatively, for example, whether to output a normal signal or an abnormal signal may be determined based on whether or not the condition that the voltage of the piezoelectric element 50 reaches the voltage V4 during the positive pressure purge and the voltage of the piezoelectric element 50 is maintained at a state equal to or higher than the voltage V4 for a predetermined time or more after the completion of the positive pressure purge is satisfied.

[0207] In the seventh modification, the positive pressure pump 151 is provided in the tube 17, but the present invention is not limited to this. For example, the positive pressure pump may be provided in the cartridge holder 10 and configured to apply a positive pressure to the ink in the ink cartridge 20 mounted on the cartridge mounting portion 10a. That is, the positive pressure pump may be provided in another portion upstream of the ink flow from the inkjet head 4.

[0208] In addition, the discharging voltage conditions, the first discharging voltage conditions, the second discharging voltage conditions, and the exhausting voltage conditions are not limited to those described in the above examples. At least one of the discharging voltage conditions, the first discharging voltage conditions, the second discharging voltage conditions, and the exhausting voltage conditions may be different from those described in the above examples.

[0209] In the above examples, the voltage of one piezoelectric element 50 is acquired during the black and color suction purging, the black and color exhaust purging, and the positive pressure purging, respectively. However, the voltages of two or more piezoelectric elements 50 may be acquired. In this case, for example, based on the average value, maximum value, minimum value, median value, etc. of the voltages of two or more piezoelectric elements 50, it may be detected that there is an abnormality in at least a part of the maintenance unit or the positive pressure pump.

[0210] In the above examples, based on the change in the voltage of the piezoelectric element 50 for applying pressure to the ink in the pressure chamber 41 to eject the ink from the nozzle 40, it is detected that there is an abnormality in the maintenance unit or the positive pressure pump. However, the present invention is not limited to this. Among the ink flow paths in the inkjet head, a wall of a flow path portion other than the pressure chamber 41 is formed by a piezoelectric element, and based on the change in the voltage of this piezoelectric element, it may be detected that there is an abnormality in the maintenance unit or the positive pressure pump. For example, the flow path in the inkjet head has a shape similar to that of the pressure chamber 41 but has a dummy pressure chamber that is not involved in the ejection of ink, and the wall of the dummy pressure chamber is formed by a piezoelectric element. Based on the change in the voltage of the piezoelectric element forming the wall of the dummy pressure chamber, it may be detected that there is an abnormality in the maintenance unit or the positive pressure pump.

[0211] Also, in the above example, the abnormal signal was a signal for causing an abnormal screen prompting replacement of at least a part of the maintenance unit or the positive pressure pump to be displayed on the operation panel 99, but this is not limiting. For example, if the printer is equipped with an LED lamp, the abnormal signal may be a signal for lighting or flashing this LED lamp to notify the user that there is an abnormality in at least a part of the maintenance unit or the positive pressure pump. Alternatively, if the printer is equipped with a speaker, the abnormal signal may be a signal for generating sound from this speaker to notify the user that there is an abnormality in at least a part of the maintenance unit or the positive pressure pump. Alternatively, the abnormal signal may be a signal transmitted to an external device such as a PC connected to the printer 1.

[0212] Also, in the above example, the normal signal was a signal for causing a normal screen indicating that the maintenance unit or the positive pressure pump is normal to be displayed on the operation panel 99, but this is not limiting. For example, if the printer is equipped with an LED lamp, the normal signal may be a signal for lighting or flashing this LED lamp to notify the user that the maintenance unit or the positive pressure pump is normal. Alternatively, if the printer is equipped with a speaker, the normal signal may be a signal for generating sound from this speaker to notify the user that the maintenance unit or the positive pressure pump is normal. Alternatively, the normal signal may be a signal transmitted to an external device such as a PC connected to the printer 1.

[0213] Also, in the above example, a normal signal was output when the maintenance unit or the positive pressure pump was normal, and an abnormal signal was output when there was an abnormality in at least a part of the maintenance unit or the positive pressure pump, but this is not limiting. For example, an abnormal signal may be output when there is an abnormality in at least a part of the maintenance unit or the positive pressure pump, and no signal may be output when the maintenance unit or the positive pressure pump is normal.

[0214] In the above example, ink is supplied from the removable ink cartridge 20 in the cartridge mounting portion 10a to the inkjet head 4, but this is not the only case. For example, an ink tank having an ink refill port for refilling ink from the outside may be fixed to the printer, and ink may be supplied from the ink tank to the inkjet head 4. In this case, the ink tank fixed to the printer corresponds to the "liquid storage portion" of the present invention.

[0215] Also, in the above-described embodiment, the ejection inspection unit 90 inspects whether or not a nozzle is abnormal based on an inspection signal output from the signal processing circuit 93 according to a change in voltage at the electrode 91 disposed in the first and second nozzle caps 81a and 81b1 from the nozzles 40 when the inkjet head 4 is driven for inspection. However, this is not the only case.

[0216] The ejection inspection unit may have, for example, an electrode that extends in the vertical direction and faces the space below the nozzle 40 in a state where the carriage 2 is located at the maintenance position, instead of the electrode 91, in the ejection inspection unit 90. Then, the ejection inspection unit may output a signal corresponding to a change in voltage of the above electrode when performing inspection driving with the carriage 2 located at the maintenance position from the signal processing circuit 93, and inspect whether or not a nozzle is abnormal based on this signal.

[0217] Alternatively, the ejection inspection unit may have, for example, an optical sensor that directly detects the ink ejected from the nozzle 40 in a state where the carriage 2 is located at a predetermined position such as the maintenance position and outputs a signal corresponding to the detection result. Then, it may be inspected whether or not a nozzle is abnormal based on the signal output from this optical sensor.

[0218] Alternatively, the ejection inspection unit may inspect whether a nozzle is abnormal in the same manner as described in, for example, Japanese Patent No. 4929699. Specifically, the ejection inspection unit connects a voltage detection circuit that detects a change in voltage when ink is ejected from a nozzle to a plate on which the nozzles of the inkjet head are formed, and inspects whether a nozzle is abnormal based on a signal output from the voltage detection circuit when an operation for ejecting ink from the nozzle is performed with the carriage moved to the inspection position.

[0219] Alternatively, the ejection inspection unit may inspect whether a nozzle is abnormal in the same manner as described in, for example, Japanese Patent No. 6231759. Specifically, the ejection inspection unit may include a temperature detection element on the substrate of the inkjet head. Then, after applying a first applied voltage to drive the heater for ink ejection, the ejection inspection unit applies a second applied voltage to drive the heater so that ink is not ejected, and inspects whether a nozzle is abnormal based on a change in temperature detected by the temperature detection element after the second applied voltage is applied and until a predetermined time has elapsed.

[0220] Alternatively, the ejection inspection unit may inspect whether a nozzle is abnormal in the same manner as described in, for example, Japanese Unexamined Patent Application Publication Nos. 2004-284189 and 2011-240563. Specifically, when the inkjet head applies pressure to the ink in the pressure chamber communicating with the nozzle by a piezoelectric element to eject ink from the nozzle, the ejection inspection unit may be provided with a residual vibration type inspection device that detects the residual vibration generated in the piezoelectric element due to the pressure change of the ink in the pressure chamber. Then, the ejection inspection unit may inspect whether a nozzle is abnormal based on the vibration pattern of the residual vibration detected by the residual vibration type inspection device when the piezoelectric element is driven to eject ink from the nozzle.

[0221] In the above description, an example of applying the present invention to a printer equipped with a so-called serial head that discharges ink from a plurality of nozzles while moving in the scanning direction together with a carriage has been described, but the present invention is not limited to this. For example, it is also possible to apply the present invention to a printer equipped with a so-called line head that extends over the entire length of a recording paper in the scanning direction.

[0222] In the above description, an example of applying the present invention to a printer that discharges ink from nozzles to perform recording on a recording paper S has been described, but the present invention is not limited to this. The present invention can also be applied to a recording apparatus that records an image on a recording medium other than recording paper, such as a T-shirt, an outdoor advertising sheet, a case of a portable terminal such as a smartphone, a cardboard box, and a resin member. Further, the present invention can also be applied to a liquid discharge apparatus that discharges a liquid other than ink droplets, for example, a liquid resin or a liquid metal.

Explanation of Reference Numerals

[0223] 1: Printer 4: Inkjet Printer 8: Maintenance Unit 17: Tube 19a~19e: Tubes 20: Ink Cartridge 40: Nozzle 44: Manifold 44a: Ink Supply Port 45: Individual Flow Path 50: Piezoelectric Element 62: Supply Flow Path 66: Exhaust Flow Path 67b: Exhaust Port 81a: First Nozzle Cap 81b: Second Nozzle Cap 82: Exhaust Cap 83: Negative Pressure Pump 83a: Pump Motor 84: Switching Unit 99: Operation Panel 100: Control Unit 150: Printer 151: Positive Pressure Pump 152: Ink Receiver

Claims

1. A head comprising a head flow path including a nozzle, and a piezoelectric element forming part of the wall of the head flow path A cleaning unit having a nozzle cap for covering the nozzle, a negative pressure pump for generating a negative pressure, and a drainage connection flow path for connecting the nozzle cap and the negative pressure pump A control unit, The control unit A drainage process of discharging the liquid in the head flow path from the nozzle by driving the negative pressure pump with the nozzle covered by the nozzle cap A voltage acquisition process of acquiring the voltage of the piezoelectric element at least during the drainage process An abnormality detection process of outputting an abnormality signal indicating that there is an abnormality in at least a part of the cleaning unit when the voltage acquired in the voltage acquisition process does not satisfy the drainage voltage condition. A liquid ejection device characterized by executing the process

2. The liquid ejection device according to claim 1, wherein the drainage voltage condition is a condition that the voltage of the piezoelectric element reaches a predetermined voltage during the drainage process

3. The liquid ejection device according to claim 2, wherein the drainage voltage condition is a condition that the voltage of the piezoelectric element reaches the predetermined voltage within the first hour after the start of the drainage process

4. The control unit In the voltage acquisition process, the voltage of the piezoelectric element is acquired at least during the drainage process and after the drainage process The liquid ejection device according to claim 1, wherein the drainage voltage condition is a condition that the voltage of the piezoelectric element reaches a predetermined voltage during the drainage process, and the voltage of the piezoelectric element is maintained at the predetermined voltage or higher for 2 hours or more after the drainage process is completed and the driving of the negative pressure pump is stopped

5. A display unit, The control unit In the abnormality detection process, the liquid ejection device according to claim 1, characterized in that an abnormality signal is output to the display unit to cause the display unit to display a screen prompting replacement of at least a part of the cleaning

6. The liquid ejection device according to claim 1, wherein at least a part of the cleaning unit is any one of the whole of the cleaning unit, the nozzle cap, the negative pressure pump, and the drainage connection flow path

7. The negative pressure pump includes a motor, and generates a negative pressure by driving the motor The motor outputs a drive state signal indicating a drive state during driving The control unit executes a drive state signal acquisition process for acquiring the drive state signal, In the abnormal signal output process, when the drain voltage condition is not satisfied and the drive signal condition for the drive state signal is satisfied, an abnormal signal indicating that there is an abnormality in a part other than the motor in the cleaning unit is output, The liquid discharge device according to claim 1, wherein when the drain voltage condition is not satisfied and the drive signal condition is not satisfied, an abnormal signal indicating that there is an abnormality in the motor is output.

8. The head has a first head flow path including a first nozzle, a second head flow path including a second nozzle different from the first nozzle and not communicating with the first head flow path, a first piezoelectric element provided for the first head flow path, and a second piezoelectric element provided for the second head flow path. The cleaning unit has a first nozzle cap for covering the first nozzle, a second nozzle cap for covering the second nozzle, a first drain connection flow path connected to the first nozzle cap, a second drain connection flow path connected to the second nozzle cap, and a switching unit for switching between a state where the first drain connection flow path is connected to the negative pressure pump and a state where the second drain connection flow path is connected to the negative pressure pump. The control unit performs a first drain process of discharging the liquid in the first head flow path from the first nozzle by driving the negative pressure pump in a state where the first nozzle is covered with the first nozzle cap and the first drain connection flow path is connected to the negative pressure pump by the switching unit, and a second drain process of discharging the liquid in the second head flow path from the second nozzle by driving the negative pressure pump in a state where the second nozzle is covered with the second nozzle cap and the second drain connection flow path is connected to the negative pressure pump by the switching unit. The voltage acquisition process includes a first voltage acquisition process for acquiring at least the voltage of the first piezoelectric element during the first drain process, and a second voltage acquisition process for acquiring at least the voltage of the second piezoelectric element during the second drain process. In the abnormality detection process, When at least one of the cases where the voltage acquired in the first voltage acquisition process does not satisfy the first drainage voltage condition and the voltage acquired in the second voltage acquisition process does not satisfy the second drainage voltage condition occurs, the liquid discharge device according to claim 1, wherein the abnormal signal is output.

9. In the abnormal detection process, the control unit When the voltage acquired in the first voltage acquisition process does not satisfy the first drainage voltage condition and the voltage acquired in the second voltage acquisition process satisfies the second drainage voltage condition, among the cleaning units, an abnormal signal indicating that there is an abnormality in at least one of the first nozzle cap, the first drainage connection flow path, and the switching unit is output. When the voltage acquired in the first voltage acquisition process satisfies the first drainage voltage condition and the voltage acquired in the second voltage acquisition process does not satisfy the second drainage voltage condition, among the cleaning units, an abnormal signal indicating that there is an abnormality in at least one of the second nozzle cap, the second drainage connection flow path, and the switching unit is output. The liquid discharge device according to claim 8, characterized in that

10. In the abnormal detection process, the control unit When the voltage acquired in the first voltage acquisition process satisfies the first drainage voltage condition and the voltage acquired in the second voltage acquisition process satisfies the second drainage voltage condition, a normal signal indicating that the cleaning unit is normal is output. The liquid discharge device according to claim 8, characterized in that

11. In the abnormal detection process, the control unit When the voltage acquired in the first voltage acquisition process does not satisfy the first drainage voltage condition and the voltage acquired in the second voltage acquisition process does not satisfy the second drainage voltage condition, among the cleaning units, an abnormal signal indicating that there is an abnormality in at least one of the negative pressure pump and the switching unit is output. The liquid discharge device according to claim 8, characterized in that

12. The control unit When receiving an instruction signal for instructing the user to execute the drainage process, the liquid discharge device according to claim 1, wherein the drainage process, the voltage acquisition process, and the abnormal detection process are executed.

13. A discharge inspection signal output unit that outputs a discharge inspection signal according to whether there is an abnormality in the discharge of liquid from the nozzle when inspection driving for discharging liquid from the nozzle is performed in the head. The control unit Causes the head to perform the inspection driving, and when the discharge inspection signal output from the discharge inspection signal output unit during the inspection driving indicates that there is an abnormality in the discharge of liquid from the nozzle, executes the drainage process, the voltage acquisition process, and the abnormality detection process. The liquid discharge device according to claim 1, characterized in that.

14. The head flow path has a plurality of the nozzles. A discharge inspection signal output unit that outputs a discharge inspection signal according to whether there is an abnormality in the discharge of liquid from the nozzle when inspection driving for discharging liquid from the nozzle is performed in the head. The control unit For each of the plurality of nozzles, causes the head to perform the inspection driving, and based on the discharge inspection signal output from the discharge inspection signal output unit during the inspection driving, executes a first discharge inspection process for acquiring first discharge inspection information regarding the number of nozzles with abnormal liquid discharge. After acquiring the first discharge inspection information, after executing the drainage process, for each of at least the nozzles with abnormal liquid discharge, causes the head to perform the inspection driving again, and based on the discharge inspection signal output from the discharge inspection signal output unit during the inspection driving again, executes a second discharge inspection process for acquiring second discharge inspection information regarding the number of nozzles with abnormal liquid discharge. When the difference condition regarding the difference between the number of nozzles with abnormal liquid discharge indicated by the first discharge inspection information and the number of nozzles with abnormal liquid discharge indicated by the second discharge inspection information is satisfied, the voltage acquisition process and the abnormality detection process are executed during the next drainage process. The liquid discharge device according to claim 1, characterized in that when the difference condition is not satisfied, the voltage acquisition process and the abnormality detection process are not executed during the next drainage process.

15. The head includes a plurality of the nozzles. A head flow path including a plurality of individual flow paths corresponding to the plurality of nozzles individually, and a common flow path connected to the plurality of individual flow paths. A plurality of piezoelectric elements provided individually for the plurality of individual flow paths and applying pressure for discharging liquid from the nozzle to the liquid in the individual flow paths. A memory unit, A discharge inspection signal output unit that outputs a discharge inspection signal according to whether there is an abnormality in the discharge of liquid from the nozzle when inspection driving for discharging liquid from the nozzle is performed in the head, and is provided with, The control unit, For each of the plurality of nozzles, the inspection driving is performed, and based on the discharge inspection signal output from the discharge inspection signal output unit during the inspection driving, discharge inspection information regarding whether there is an abnormality in the discharge of liquid is stored in the memory unit by executing a discharge inspection process, In the voltage acquisition process, the voltage of the piezoelectric element provided for the individual flow path including the nozzle indicated by the discharge inspection information stored in the memory unit that there is no abnormality in the discharge of liquid is acquired. The liquid discharge device according to claim 1, characterized in that.

16. The head flow path includes a liquid supply port, A liquid storage unit that stores liquid for supplying to the head flow path, A supply flow path that connects the liquid supply port and the liquid storage unit, and further includes, An exhaust flow path that branches from the supply flow path and has an exhaust port, An exhaust cap for covering the exhaust port, An exhaust connection flow path for connecting the exhaust cap and the negative pressure pump, A switching unit that switches between a state where the drain connection flow path and the negative pressure pump are connected and a state where the exhaust connection flow path and the negative pressure pump are connected, and is provided with, The control unit, In the drain process, with the nozzle covered by the nozzle cap and the drain connection flow path and the negative pressure pump connected by the switching unit, the negative pressure pump is driven, An exhaust process of discharging gas in the head flow path from the discharge port by driving the negative pressure pump in a state where the exhaust port is covered by the exhaust cap and the exhaust connection flow path and the negative pressure pump are connected by the switching unit, The voltage acquisition process is, A drain-time voltage acquisition process that acquires the voltage of the piezoelectric element at least during the drain process, An exhaust-time voltage acquisition process that acquires the voltage of the piezoelectric element at least during the exhaust process, and includes, In the abnormality detection process, When the voltage acquired in the drain-time voltage acquisition process satisfies the drain-time voltage condition and the voltage acquired in the exhaust-time voltage acquisition process satisfies the exhaust-time voltage condition, a normal signal indicating that the cleaning unit is normal is output. When the voltage acquired in the drainage voltage acquisition process does not satisfy the drainage voltage condition and the voltage acquired in the exhaust voltage acquisition process satisfies the exhaust voltage condition, an abnormal signal indicating that there is an abnormality in at least one of the nozzle cap, the drainage connection flow path, and the switching unit in the cleaning unit is output. When the voltage acquired in the drainage voltage acquisition process satisfies the drainage voltage condition and the voltage acquired in the exhaust voltage acquisition process does not satisfy the exhaust voltage condition, an abnormal signal indicating that there is an abnormality in at least one of the exhaust cap, the exhaust connection flow path, and the switching unit in the cleaning unit is output. The liquid discharge device according to claim 1, wherein when the voltage acquired in the drainage voltage acquisition process does not satisfy the drainage voltage condition and the voltage acquired in the exhaust voltage acquisition process does not satisfy the exhaust voltage condition, an abnormal signal indicating that there is an abnormality in at least one of the switching unit and the negative pressure pump in the cleaning unit is output.

17. A head having a head flow path including a nozzle and a piezoelectric element forming a part of the wall of the head flow path. A positive pressure pump for applying a positive pressure to the liquid in the head flow path. A liquid receiving portion for receiving the liquid discharged from the nozzle. A control unit. The control unit. By driving the positive pressure pump, a drainage process of discharging the liquid in the head flow path from the nozzle to the liquid receiving portion. A voltage acquisition process of acquiring the voltage of the piezoelectric element at least during the drainage process. An abnormal detection process of outputting an abnormal signal indicating that there is an abnormality in the positive pressure pump when the voltage acquired in the voltage acquisition process does not satisfy the drainage voltage condition. The liquid discharge device is characterized by executing the above processes.

18. A head having a head flow path having a nozzle and a liquid supply port and a piezoelectric element forming a part of the wall of the head flow path. A liquid storage portion for storing the liquid to be supplied to the head flow path. A supply flow path connecting the discharge port and the liquid storage portion. An exhaust flow path branched from the supply flow path and having an exhaust port. A cleaning unit having an exhaust cap for covering the exhaust port, a negative pressure pump for generating a negative pressure, and an exhaust continuous connection flow path connecting the exhaust cap and the negative pressure pump. A control unit. The control unit. By driving the negative pressure pump with the exhaust port covered by the exhaust cap, an exhaust process for discharging the gas in the head flow path from the exhaust port is performed. A voltage acquisition process for acquiring the voltage of the piezoelectric element at least during the liquid discharge process. An abnormality detection process for outputting an abnormality signal indicating that there is an abnormality in at least a part of the cleaning unit when the voltage acquired in the voltage acquisition process does not satisfy the exhaust voltage condition. A liquid discharge device characterized by performing the above processes.

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