Liquid discharge device

Abstract

To efficiently reduce increased viscosity of liquid in a nozzle.SOLUTION: A liquid discharge device executes a first discharge inspecting process of inspecting whether a plurality of nozzles of an inkjet head are abnormal nozzles or not (S101); then executes a post-inspection driving process of making a driving element of the inkjet head perform driving operation of reducing increased viscosity of ink in the abnormal nozzles (S102); and subsequently executes a second discharge inspecting process (S103). When the number ΔN of abnormal nozzles, reduced from the number N1 of abnormal nozzles that is the number of nozzles 10 shown to be the abnormal nozzles by inspected results in the second discharge inspecting process, of the number N2 of abnormal nozzles that is the number of nozzles 10 shown to be the abnormal nozzles by inspected result in the second discharge inspecting process, is above first number Ma (S104:YES), the post-inspection driving process is executed again (S105). When the number ΔN is less than the first number Ma (S104:NO), the post-inspection driving process is not executed again.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] As an example of a liquid ejection device that ejects liquid from nozzles, Patent Document 1 describes an inkjet printer that performs recording by ejecting ink from nozzles. The inkjet printer of Patent Document 1 performs flushing to remove thickened ink near the nozzles, and vibrates the ink in the ink passages during periods when flushing is not performed, thereby efficiently removing the thickened ink. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-034471 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, as described above, in addition to performing flushing to efficiently eliminate thickening of the ink, the ink in the ink passage is vibrated during periods when flushing is not being performed. However, in liquid ejection devices that eject liquid from nozzles, there is a demand for more efficient elimination of thickening of the liquid in the flow passage.

[0005] An object of the present invention is to provide a liquid ejection device that can more efficiently eliminate thickening of the liquid inside the flow path. [Means for solving the problem]

[0006] The liquid ejection device of the present invention comprises a head having a plurality of nozzles and a plurality of driving elements that apply ejection energy to liquid in the plurality of nozzles, an ejection inspection unit that performs an ejection inspection to check whether the nozzle is an abnormal nozzle having an abnormality in ejecting liquid, and a control unit, wherein the control unit causes the ejection inspection unit to perform a first ejection test, and after the first ejection test, causes the plurality of driving elements to perform a post-test drive operation including a plurality of types of drive operations having different drive frequencies for driving the drive elements, and after the post-test drive operation, causes the ejection inspection unit to perform a second ejection test, and if a first condition regarding the relationship between the result of the first ejection test and the result of the second ejection test is satisfied, causes the ejection inspection unit to perform a first operation including the post-test drive operation after the second ejection test, and if the first condition is not satisfied, causes the ejection inspection unit to perform a second operation different from the first operation after the second ejection test.

[0007] In addition, the liquid ejection device of the present invention includes a head having a plurality of nozzles and a plurality of driving elements that apply ejection energy to liquid in the plurality of nozzles, an ejection inspection unit that performs an ejection inspection to check whether the nozzle is an abnormal nozzle having an abnormality in ejecting liquid, and a control unit, wherein the control unit causes the ejection inspection unit to perform a first ejection test, causes the ejection inspection unit to perform a cleaning operation to discharge liquid from the abnormal nozzle after the first ejection test, and causes the ejection inspection unit to perform a second ejection test after the cleaning operation, and if a predetermined condition regarding the relationship between the result of the first ejection test and the result of the second ejection test is satisfied, causes the ejection inspection unit to perform a first operation including the cleaning operation after the second ejection test, and if the predetermined condition is not satisfied, causes the ejection inspection unit to perform a second operation different from the first operation after the second ejection test. Effect of the Invention

[0008] In the present invention, a post-inspection driving operation or cleaning operation is performed after the first discharge inspection, and then a second discharge inspection is performed. Then, when a first condition on the relationship between the results of the first and second discharge inspections is satisfied, a first operation including a post-inspection driving operation or cleaning operation is performed after the second discharge inspection. Also, when the first condition is not satisfied, a second operation different from the first operation is performed after the second discharge inspection. This makes it possible to efficiently eliminate thickening of the liquid according to the results of the first and second discharge inspections. For example, when the effect of eliminating thickening by the post-inspection driving operation or cleaning operation after the first discharge inspection is high, the first operation including the post-inspection driving operation or cleaning operation can be performed after the second discharge inspection to further eliminate thickening. On the other hand, for example, when the effect of eliminating thickening by the post-inspection driving operation or cleaning operation after the first discharge inspection is low, a second operation different from the first operation is performed after the second discharge inspection, so that the post-inspection driving operation or cleaning operation with a low effect of eliminating thickening is not repeated. Here, preventing the repetition of post-inspection driving operations or cleaning operations that have a low effect of eliminating thickening means, for example, not performing a post-inspection driving operation or cleaning operation, or performing a post-inspection driving operation or cleaning operation that has a greater effect of eliminating thickening. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a printer according to a first embodiment. [Diagram 2] 4A to 4C are diagrams for explaining electrodes arranged in a cap and a configuration for applying a voltage to the electrodes. [Diagram 3] FIG. 1A is a diagram for explaining the signal output from the signal processing circuit when the nozzle is normal, and FIG. 1B is a diagram for explaining the signal output from the signal processing circuit when there is an abnormality in the nozzle discharge volume. [Figure 4] FIG. 2 is a block diagram showing the electrical configuration of the printer. [Diagram 5]10A is a flow chart showing the flow of processing when inspecting whether or not a nozzle is abnormal, and FIG. 10B is a flow chart showing the flow of drive processing after the inspection of FIG. [Figure 6] 10 is a flowchart showing a process flow when inspecting whether a nozzle is abnormal in the second embodiment. [Figure 7] 13A is a diagram for explaining a purge level in the third embodiment, and FIG. 13B is a flowchart showing a process flow when inspecting whether a nozzle is abnormal in the third embodiment. [Figure 8] 13A is a flowchart showing the process flow when testing whether a nozzle is abnormal in the fourth embodiment, and FIG. 13B is a diagram for explaining the difference between the first post-inspection drive process and the second post-inspection drive process in the fourth embodiment. [Figure 9] 13 is a flowchart showing a process flow when inspecting whether a nozzle is abnormal in the fifth embodiment. [Figure 10] 13 is a flowchart showing a process flow when inspecting whether a nozzle is abnormal in the sixth embodiment. [Figure 11] (a) is a diagram for explaining the difference between the first post-inspection drive processing and the second post-inspection drive processing in the seventh embodiment, (b) is a diagram for explaining the difference between the first post-inspection drive processing and the second post-inspection drive processing in the eighth embodiment, (c) is a diagram for explaining the difference between the first post-inspection drive processing and the second post-inspection drive processing in the ninth embodiment, (d) is a diagram for explaining the difference between the first post-inspection drive processing and the second post-inspection drive processing in the tenth embodiment, (e) is a diagram for explaining the difference between the first post-inspection drive processing and the second post-inspection drive processing in the eleventh embodiment, and (f) is a diagram for explaining the difference between the first post-inspection drive processing and the second post-inspection drive processing in the twelfth embodiment. [Figure 12] 23 is a flowchart showing the flow of processing when inspecting whether a nozzle is abnormal in the thirteenth embodiment. [Figure 13]23 is a flowchart showing the flow of processing when inspecting whether or not a nozzle is abnormal in the fourteenth embodiment. [Figure 14] 23 is a flowchart showing the flow of processing when inspecting whether a nozzle is abnormal in the fifteenth embodiment. [Figure 15] 23 is a flowchart showing the flow of processing when inspecting whether or not a nozzle is abnormal in the sixteenth embodiment. [Figure 16] 23 is a flowchart showing the flow of processing performed when power is supplied to the printer in the seventeenth embodiment. [Figure 17] 23 is a flowchart showing the flow of processing when inspecting whether or not a nozzle is abnormal in the eighteenth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [First embodiment] A first preferred embodiment of the present invention will now be described.

[0011] <Overall printer configuration> As shown in Fig. 1, the printer 1 according to the first embodiment includes a carriage 2, an inkjet head 4, a platen 5, transport rollers 6 and 7, and a maintenance unit 8. In the first embodiment, the inkjet head 4 corresponds to the "head" of the present invention. Also, in the first embodiment, the maintenance unit 8 corresponds to the "purge section" of the present invention.

[0012] The carriage 2 is supported by two guide rails 11, 12 that extend in a horizontal scanning direction. In the following description, the right and left sides of the scanning direction are defined as shown in FIG. 1. The carriage 2 is connected to a carriage motor 86 shown in FIG. 4 via a belt or the like (not shown). When the carriage motor 86 is driven, the carriage 2 moves in the scanning direction along the guide rails 11, 12.

[0013] The inkjet head 4 is mounted on the carriage 2. The inkjet head 4 includes a plurality of nozzles 10 and a plurality of driving elements 90 shown in FIG. 4. The plurality of nozzles 10 are formed on a nozzle surface 4a, which is the lower surface of the inkjet head 4. The plurality of nozzles 10 are arranged in the transport direction to form a nozzle row 9, and on the nozzle surface 4a, four nozzle rows 9 are lined up in the scanning direction. The plurality of driving elements 90 are provided individually for the plurality of nozzles 10, and apply ejection energy to the ink in the corresponding nozzles 10. The driving elements 90 are, for example, piezoelectric actuators that apply ejection energy to the ink in the nozzles 10 by applying pressure to the ink in a pressure chamber (not shown) that communicates with the nozzles 10.

[0014] In the inkjet head 4, the driving elements 90 are driven to eject ink from the corresponding nozzles 10. Here, black, yellow, cyan, and magenta inks are ejected from the multiple nozzles 10 in order from the nozzles constituting the nozzle row 9 on the right side in the scanning direction. Here, the inkjet head 4 is connected to four ink cartridges (not shown) via tubes (not shown) and the above four colors of ink are supplied from these four ink cartridges.

[0015] The platen 5 is disposed below the inkjet head 4 and faces the multiple nozzles 10. 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. The transport roller 6 is disposed upstream of the inkjet head 4 and the platen 5 in the transport direction. The transport roller 7 is disposed downstream of the inkjet head 4 and the platen 5 in the transport direction. The transport rollers 6 and 7 are connected to a transport motor 87 shown in FIG. 4 via gears (not shown) and the like. When the transport motor 87 is driven, the transport rollers 6 and 7 rotate and the recording paper S is transported in the transport direction.

[0016] The maintenance unit 8 includes a cap 71, a suction pump 72, and a waste liquid tank 73. The cap 71 is disposed to the right of the platen 5 in the scanning direction. When the carriage 2 is positioned at a maintenance position to the right of the platen 5 in the scanning direction, the multiple nozzles 10 face the cap 71.

[0017] The cap 71 is connected to a cap lifting mechanism 88 shown in FIG. 4. When the cap lifting mechanism 88 is driven, the cap 71 is lifted. When the carriage 2 is positioned at the maintenance position so that the nozzles 10 and the cap 71 face each other, the cap 71 is lifted by the cap lifting mechanism 88, and the upper end of the cap 71 comes into close contact with the nozzle surface 4a, resulting in a capped state in which the nozzles 10 are covered by the cap 71. When the cap 71 is lowered, the nozzles 10 are not covered by the cap 71. Note that the cap 71 is not limited to being in close contact with the nozzle surface 4a to cover the nozzles 10. The cap 71 may be in close contact with a frame (not shown) or the like that is arranged around the nozzle surface 4a of the inkjet head 4 to cover the nozzles 10, for example.

[0018] The suction pump 72 is a tube pump or the like, and is connected to the cap 71 and the waste liquid tank 73. In the maintenance unit 8, when the suction pump 72 is driven in the above-mentioned capped state, it is possible to perform a so-called suction purge, which discharges ink from inside the inkjet head 4 through the multiple nozzles 10. The ink discharged by the suction purge is stored in the waste liquid tank 73.

[0019] For convenience, the cap 71 covers all the nozzles 10 together, and ink in the inkjet head 4 is discharged from all the nozzles 10 during suction purge. However, the present invention is not limited to this. For example, the cap 71 may have a portion covering the nozzles 10 constituting the rightmost nozzle row 9 that ejects black ink and a portion covering the nozzles 10 constituting the three leftmost nozzle rows 9 that eject color inks, and may selectively discharge either the black ink or the color ink in the inkjet head 4 during suction purge. Here, the color inks refer to yellow, cyan, and magenta inks. Alternatively, for example, the cap 71 may be provided for each nozzle row 9, and ink may be discharged from the nozzles 10 for each nozzle row 9 during suction purge.

[0020] 2, the printer 1 includes a discharge inspection unit 20. The discharge inspection unit 20 includes an electrode 76, a high-voltage power supply circuit 77, a signal processing circuit 78, and a resistor 79.

[0021] The electrode 76 has a rectangular planar shape and is disposed within the cap 71. The electrode 76 is connected to a high-voltage power supply circuit 77 via a resistor 79. The high-voltage power supply circuit 77 applies a predetermined voltage, for example, about 600 V, to the electrode 76. Meanwhile, the inkjet head 4 is held at ground potential. This generates a potential difference between the inkjet head 4 and the electrode 76. The signal processing circuit 78 is connected to the electrode 76. The signal processing circuit 78 includes a differentiation circuit and the like, and outputs an inspection signal that is a voltage signal corresponding to the voltage of the electrode 76. However, the inspection signal output from the signal processing circuit 78 may be a current signal.

[0022] Furthermore, in the first embodiment, after the above-mentioned capping state is achieved, a voltage is applied to the electrode 76 by the high-voltage power supply circuit 77, and a test drive operation can be performed for each of the multiple nozzles 10 to drive the corresponding drive element 90 to eject ink from the nozzle 10 toward the electrode 76.

[0023] When ink is ejected from the nozzle 10 by the test driving operation, the ejected ink is charged due to the potential difference between the electrode 76 and the inkjet head 4. Therefore, the potential of the electrode 76 changes as the charged ink approaches the electrode 76 and until the ink lands on the electrode 76. Then, after the charged ink lands on the electrode 76, the potential of the electrode 76 attenuates and returns to the potential before the ink was ejected.

[0024] As a result, when ink is normally ejected from the nozzle 10 by the test drive operation, the voltage of the test signal output from the signal processing circuit 78 rises and then falls, as shown in Figure 3(a), and then repeats rising and falling while attenuating, returning to the voltage before the test drive operation.

[0025] On the other hand, when there is an abnormality in the nozzle 10 and the amount of ink ejected from the nozzle 10 by the test drive operation is less than normal, the voltage change in the test signal output from the signal processing circuit 78 is smaller than when ink is ejected normally from the nozzle 10, as shown in Figure 3(b). Here, the amount of ink ejected being less than when ink is ejected normally from the nozzle 10 also includes the case where ink is not ejected. When ink is not ejected from the nozzle 10 by the test drive operation, there is almost no change in the voltage of the test signal output from the signal processing circuit 78.

[0026] Thus, in the first embodiment, the change in voltage of the test signal output from the signal processing circuit 78 differs depending on whether ink is normally ejected from the nozzle 10 when the test drive operation is performed. In other words, the test signal output from the signal processing circuit 78 is a signal that indicates whether the nozzle 10 is an abnormal nozzle that is experiencing an abnormality in the ejection of ink.

[0027] In the first embodiment, a predetermined voltage is applied to the electrode 76, the inkjet head 4 is held at ground potential, and the signal processing circuit 78 outputs a signal according to the voltage of the electrode 76. However, the present invention is not limited to this. It is also possible to hold the electrode 76 at ground potential and apply a predetermined voltage to the inkjet head 4 to generate a potential difference between the electrode 76 and the inkjet head 4, and to connect the signal processing circuit 78 to the inkjet head 4 and output an inspection signal according to the voltage of the inkjet head 4.

[0028] <Printer electrical configuration> Next, the electrical configuration of the printer 1 will be described. As shown in Fig. 4, the printer 1 includes a control unit 80. The control unit 80 includes a CPU 81, a ROM 82, a RAM 83, a memory 84, an ASIC 85, etc. The control unit 80 controls a carriage motor 86, a plurality of drive elements 90 of the inkjet head 4, a transport motor 87, a cap lifting mechanism 88, a suction pump 72, a high-voltage power supply circuit 77, a signal processing circuit 78, etc.

[0029] In addition to the configuration described above, the printer 1 also includes an operation panel 69. The operation panel 69 is, for example, a touch panel provided on the housing of the printer 1. Under the control of the control unit 80, an operation screen, messages, etc. are displayed on the operation panel 69. When the user operates the operation panel 69 based on the operation screen, etc., a signal corresponding to the user's operation is transmitted to the control unit 80. Instead of the operation panel 69, a display unit on which messages, etc. are displayed and an operation unit for allowing the user to operate may be provided separately.

[0030] The control unit 80 may be one in which only the CPU 81 performs various processes, one in which only the ASIC 85 performs various processes, or one in which the CPU 81 and the ASIC 85 work together to perform various processes. The control unit 80 may be one in which one CPU 81 performs processes independently, or one in which multiple CPUs 81 share the processes. The control unit 80 may be one in which one ASIC 85 performs processes independently, or one in which multiple ASICs 85 share the processes.

[0031] <Recording control> In the printer 1, the control unit 80 controls the carriage motor 86 to move the carriage 2 in the scanning direction, while repeatedly performing a recording pass in which the inkjet head 4 ejects ink from multiple nozzles 10, and a transport operation in which the transport motor 87 causes the transport rollers 6, 7 to transport the recording paper S, thereby performing recording on the recording paper S.

[0032] <Processing during nozzle inspection> Next, a process performed by the control unit 80 when inspecting each of the nozzles 10 of the inkjet head 4 to determine whether it is an abnormal nozzle will be described.

[0033] When the control unit 80 performs the above inspection, it performs processing according to the flowchart in Fig. 5(a). For example, the flowchart in Fig. 5(a) is started when a predetermined time arrives, when a recording instruction is received that instructs the printer 1 to record an image on the recording paper S, when a user operates the operation panel 69 to instruct the above inspection, etc.

[0034] In the first embodiment, the process is described as being performed for all the nozzles 10 of the inkjet head 4 according to the flowchart in Fig. 5(a), but the present invention is not limited to this. For example, the process may be performed for each nozzle row 9 individually according to the flowchart in Fig. 5(a). The same applies to the following examples.

[0035] To explain the flow chart of FIG. 5(a) in detail, the control unit 80 first executes a first discharge inspection process (S101). In the first discharge inspection process, the control unit 80 controls the carriage motor 86, the cap lifting mechanism 88, etc. to set the above-mentioned cap state, controls the high-voltage power supply circuit 77 to apply a predetermined voltage to the electrode 76, and then causes each of the multiple nozzles 10 to perform an inspection drive operation. Then, the control unit 80 stores in the memory 84 whether each of the multiple nozzles of the inkjet head 4 is an abnormal nozzle or not, based on an inspection signal output from the signal processing circuit 78 when the inspection drive operation is performed for each nozzle 10. Note that in the first embodiment, the operation for inspecting whether a nozzle is abnormal or not, which is performed in the first discharge inspection process, corresponds to the "first discharge inspection" of the present invention.

[0036] Next, the control unit 80 executes a post-inspection drive process (S102). In the post-inspection drive process, the control unit 80 performs the process according to the flowchart in Fig. 5(b). To explain the flowchart in Fig. 5(b) in detail, the control unit 80 first resets a variable K to 0 (S201). The value of the variable K corresponds to the number of times that the non-ejection drive operation, the low-frequency ejection drive operation, and the high-frequency drive operation described below have been repeated.

[0037] Next, the control unit 80 causes the driving element 90 corresponding to the nozzle 10 that is indicated to be an abnormal nozzle by the result of the first ejection inspection process to perform a non-ejection driving operation (S202). The non-ejection driving operation is an operation for driving the driving element 90 so that an ejection energy smaller than the ejection energy required to eject ink from the nozzle 10 is applied to the ink in the nozzle 10. When the non-ejection driving operation is performed, the ink in the ink flow path individual to the abnormal nozzle and the nozzle 10 connected to the abnormal nozzle is agitated, and thickening of the ink is reduced. In the first embodiment, the non-ejection driving operation corresponds to the "first driving operation" of the present invention.

[0038] Next, the control unit 80 causes the driving element 90 corresponding to the nozzle 10 that is indicated to be an abnormal nozzle by the result of the first ejection inspection process to perform a low-frequency ejection drive operation (S203). The low-frequency ejection drive operation is an operation to eject ink from the nozzle 10 by driving the driving element 90 at a drive frequency lower than the high-frequency ejection drive operation described below. When the low-frequency ejection drive operation is performed, ink in the individual ink flow paths is ejected from the abnormal nozzle and the nozzle 10 connected to the abnormal nozzle, and low-viscosity ink is supplied from the ink cartridge side to this ink flow path, reducing the increase in viscosity of the ink. In the first embodiment, the low-frequency ejection drive operation corresponds to the "second drive operation" of the present invention.

[0039] Next, the control unit 80 causes the driving element 90 corresponding to the nozzle 10 that is indicated to be an abnormal nozzle by the result of the first ejection inspection process to perform a high-frequency ejection driving operation (S204). The high-frequency ejection driving operation is an operation to eject ink from the nozzle 10 by driving the driving element 90 at a driving frequency higher than the low-frequency ejection driving operation of S203. When the high-frequency ejection driving operation is performed, ink in the individual ink flow paths is ejected from the abnormal nozzle and the nozzle 10 connected to the abnormal nozzle, and low-viscosity ink is supplied from the ink cartridge side to this ink flow path, thereby reducing the increase in viscosity of the ink. In the first embodiment, the high-frequency ejection driving operation corresponds to the "third driving operation" of the present invention.

[0040] Next, the control unit 80 increments the value of the variable K by 1 (S205), and determines whether the value of the variable K after the increment is equal to or greater than a predetermined value Ka (S206). If the value of the variable K is less than the predetermined value Ka (S206: NO), the process returns to S202, and if the value of the variable K is equal to or greater than the predetermined value Ka (S206: YES), the process returns to the flowchart of FIG. 5(a). As a result, in the first embodiment, the non-ejection drive operation, the low-frequency ejection drive operation, and the high-frequency drive operation are repeatedly performed Ka times in the post-inspection drive process. In the first embodiment, the non-ejection drive operation, the low-frequency ejection drive operation, and the high-frequency drive operation repeatedly performed Ka times correspond to the "post-inspection drive operation" of the present invention.

[0041] Returning to FIG. 5(a), following the post-inspection drive process of S102, the control unit 80 executes a second ejection inspection process (S103). In the second ejection inspection process, the control unit 80 inspects whether each of the nozzles 10 that are indicated to be abnormal by the results of the first ejection inspection process are abnormal, and stores the results in the memory 84. The procedure for inspecting whether each nozzle 10 is abnormal is the same as in the first ejection inspection process. Note that in the first embodiment, the operation for inspecting whether a nozzle is abnormal, which is performed in the second ejection inspection process of S103, corresponds to the "second ejection inspection" of the present invention.

[0042] Next, the control unit 80 judges whether the number of abnormal nozzles N2, which is the number of nozzles 10 that are indicated to be abnormal by the result of the second discharge inspection process, is reduced by a number ΔN from the number of abnormal nozzles N1, which is the number of nozzles 10 that are indicated to be abnormal by the result of the first discharge inspection process, i.e., [N1-N2], is equal to or greater than the first number Ma (S104). Note that in the first embodiment, the condition that the reduced number ΔN is equal to or greater than the first number Ma corresponds to the "first condition" of the present invention.

[0043] When the reduced number ΔN is less than the first number Ma (S104: NO), the control unit 80 executes a termination process (S107), and the process ends. In the termination process, the control unit 80 performs, for example, various operations for returning to a standby state. Note that in the first embodiment, the operation performed in the termination process of S107 when the reduced number ΔN is less than the first number Ma corresponds to the "second operation" of the present invention.

[0044] If the decrease number ΔN is equal to or greater than the first number Ma (S104: YES), the control unit 80 executes a post-inspection drive process (S105).Then, the control unit 80 executes a third ejection inspection process (S106).

[0045] In the third discharge inspection process, the control unit 80 inspects whether each of the nozzles 10 that are indicated to be abnormal by the results of the second discharge inspection process is an abnormal nozzle, and stores the results in the memory 84. The procedure for inspecting whether each nozzle 10 is an abnormal nozzle is the same as in the first discharge inspection process.

[0046] Then, after the third discharge inspection process is completed, the control unit 80 executes a termination process (S107), and the process ends. Note that in the first embodiment, when the reduction number ΔN is equal to or greater than the first number Ma, the combination of the post-inspection drive process of S105, the third discharge inspection process of S106, and the operations performed in the termination process of S107 corresponds to the "first operation" of the present invention.

[0047] <Effects> When the number of reductions ΔN is large, the effect of eliminating thickening by the post-inspection driving operation after the first discharge inspection is high. On the other hand, when the number of reductions ΔN is small, the effect of eliminating thickening by the post-inspection driving operation after the first discharge inspection is low. Therefore, in the first embodiment, when the first condition that the number of reductions ΔN is equal to or greater than the first number Ma is satisfied, a first operation including a post-inspection driving operation is performed after the second discharge inspection. Also, when the first condition is not satisfied, a second operation that is different from the first operation and does not include a post-inspection driving operation is performed after the second discharge inspection.

[0048] This allows the thickening of the ink in the nozzle 10 to be efficiently eliminated according to the results of the first and second ejection tests. Specifically, if the post-inspection driving operation after the first ejection test has a high effect of eliminating thickening, the post-inspection driving operation can be performed after the second ejection test to further eliminate thickening. On the other hand, if the post-inspection driving operation after the first ejection test has a low effect of eliminating thickening, the post-inspection driving operation is not performed after the second ejection test, so that the post-inspection driving operation with a low effect of eliminating thickening is not repeated, thereby suppressing unnecessary ink consumption and shortening the time required for processing.

[0049] Also, in the first embodiment, the post-inspection drive operation after the first ejection inspection and the second ejection inspection are performed only for nozzles 10 that are indicated as abnormal nozzles by the results of the first ejection inspection process. This makes it possible to reduce the time and amount of ink required for the post-inspection drive operation after the first ejection inspection and the second ejection inspection. Also, in the first embodiment, the post-inspection drive operation after the second ejection inspection is performed only for nozzles 10 that are indicated as abnormal nozzles by the results of the second ejection inspection process. This makes it possible to reduce the time and amount of ink required for the post-inspection drive operation after the second ejection inspection.

[0050] In the first embodiment, the post-inspection driving operation includes three types of driving operations: a non-ejection driving operation that imparts to the ink in the nozzle 10 ejection energy smaller than the ejection energy required to eject ink from the nozzle 10, and a low-frequency ejection driving operation and a high-frequency ejection driving operation that impart the ejection energy required to eject ink from the nozzle 10. This makes it possible to enhance the viscosity elimination effect compared to a case where two or more types of driving operations impart ejection energy smaller than the ejection energy required to eject ink from the nozzle 10. Also, the amount of ink consumed can be reduced compared to a case where all three types of driving operations impart the ejection energy required to eject ink from the nozzle 10.

[0051] In addition, the thickening of the ink in the nozzle 10 can be eliminated more efficiently than when the post-inspection driving operation includes only two types of driving operations. To be more specific, for example, ink is ejected from the nozzle 10 in both the low-frequency ejection driving operation and the high-frequency ejection driving, but the driving frequency of the driving element 90 is different between the low-frequency ejection driving operation and the high-frequency ejection driving. Therefore, the flow of ink in the ink flow path is different between the low-frequency ejection driving operation and the high-frequency ejection driving, and the effect of eliminating thickening due to the ink flow is also different. Therefore, as in the first embodiment, when the post-inspection driving operation includes three types of driving operations, a non-ejection driving operation, a low-frequency ejection driving operation, and a high-frequency ejection driving operation, the thickening of the ink in the nozzle 10 can be eliminated more efficiently than when the post-inspection driving operation includes only two types of driving operations, a non-ejection driving operation, and one of the low-frequency ejection driving operation and the high-frequency ejection driving operation, out of the three types of driving operations.

[0052] [Second embodiment] Next, a second preferred embodiment of the present invention will be described. The second embodiment also relates to a printer 1 similar to the first embodiment. However, in the second embodiment, when inspecting each of the multiple nozzles 10 of the inkjet head 4 to determine whether or not it is an abnormal nozzle, the control unit 80 performs processing according to the flowchart of FIG.

[0053] 6 in detail, the control unit 80 executes the processes of S301 to S303 similar to S101 to S103 similar to those of the first embodiment. Next, the control unit 80 determines whether the ratio [ΔN / N1] of the reduction number ΔN to the number of abnormal nozzles N1 is equal to or greater than a first value Ra (S304). Note that in the second embodiment, the condition that the ratio [ΔN / N1] is equal to or greater than the first value Ra corresponds to the "first condition" of the present invention.

[0054] When the ratio [ΔN / N1] is equal to or greater than the first value Ra (S304: YES), the control unit 80 executes post-inspection drive processing (S305), then executes third ejection inspection processing (S306), and then executes end processing (S307), and the processing ends. When the ratio [ΔN / N1] is less than the first value Ra (S304: NO), the control unit 80 executes end processing (S307), and the processing ends.

[0055] <Effect> When the ratio [ΔN / N1] is large, the effect of eliminating thickening by the post-inspection drive operation after the first ejection inspection is high. On the other hand, when the ratio [ΔN / N1] is small, the effect of eliminating thickening by the post-inspection drive operation after the first ejection inspection is low. Therefore, in the second embodiment, when the first condition that the ratio [ΔN / N1] is equal to or greater than the first value Ra is satisfied, a first operation including a post-inspection drive operation is performed after the second ejection inspection. Further, when the first condition is not satisfied, after the second ejection inspection, a second operation that is different from the first operation and does not include a post-inspection drive operation is performed. Thereby, similar to that described in the first embodiment, it is possible to efficiently eliminate the thickening of the ink in the nozzle 10 according to the results of the first and second ejection inspections.

[0056] [Third Embodiment] Next, a preferred third embodiment of the present invention will be described. The third embodiment also relates to the same printer 1 as the first embodiment. However, in the third embodiment, as shown in FIG. 7(a), six purge levels from "0" to "5" are set according to the range of the number of nozzles 10 indicating that the result of the last performed ejection inspection process is an abnormal nozzle. Here, Na to Ne in FIG. 7(a) have a magnitude relationship of 0 ≦ Na < Nb < Nc < Nd < Ne < Nt, where Nt is the number of nozzles 10 of the inkjet head 4.

[0057] As shown in Fig. 7(a), in the third embodiment, whether or not to perform purging and the type of purge to be performed are set for each purge level and stored in memory 84. In Fig. 7(a), "not performed" indicates that purging is not performed, and "normal purge", "strong purge" and "strongest purge" indicate the type of purge to be performed. Strong purge is a purge that discharges more ink than normal purge. Strongest purge is a purge that discharges more ink than strong purge.

[0058] Also, as shown in FIG. 7(a), in the third embodiment, whether or not to perform purging and the type of purging are set for three cases, "before recording", "before recording (high risk)", and "user instruction". "Before recording" in FIG. 7(a) refers to before recording on the recording paper S other than the case of "before recording (high risk)". "Before recording (high risk)" in FIG. 7(a) refers to before recording on a specific recording paper S, such as glossy paper. "User instruction" in FIG. 7(a) refers to when the user operates the operation panel 69 to instruct purging. Note that in the third embodiment, whether or not to perform purging and the type of purging may be set only for one or two of the above three cases. Alternatively, whether or not to perform purging and the type of purging may be set for cases other than the above three cases.

[0059] Furthermore, in the third embodiment, when inspecting each of the nozzles 10 of the inkjet head 4 to see if it is an abnormal nozzle, the control unit 80 performs processing in accordance with the flowchart of FIG. 7(b).

[0060] 7(b) in detail, the control unit 80 executes the processes of S401 to S403 similar to S101 to S103 similar to those of the first embodiment. Next, the control unit 80 determines whether the purge level has decreased (S404). Here, the purge level having decreased means that the purge level corresponding to the number of abnormal nozzles N2 is lower than the purge level corresponding to the number of abnormal nozzles N1.

[0061] In the third embodiment, the condition that the purge level is lowered corresponds to the "first condition" of the present invention. That is, the condition that the number N1 of abnormal nozzles is a number within a first range corresponding to any purge level, and the number N2 of abnormal nozzles is a number within a second range smaller than the first range corresponding to a lower purge level corresponds to the "first condition" of the present invention.

[0062] If the purge level has decreased (S404: YES), the control unit 80 executes a post-inspection drive process (S405), then executes a third discharge inspection process (S406), then executes an end process (S407), and the process ends. If the purge level has not decreased (S404: NO), the control unit 80 executes an end process (S407), and the process ends.

[0063] <Effects> When the purge level is lowered by the post-inspection driving operation after the first discharge inspection, the post-inspection driving operation has a high effect of eliminating thickening. When the purge level is maintained before and after the post-inspection driving operation after the first discharge inspection, the post-inspection driving operation has a low effect of eliminating thickening. In the third embodiment, when the first condition that the purge level is lowered is satisfied, the first operation including the post-inspection driving operation is performed after the second discharge inspection. Also, when the first condition is not satisfied, the second operation not including the post-inspection driving operation, which is different from the first operation, is performed after the second discharge inspection. As a result, as in the first embodiment, the thickening of the ink in the nozzle 10 can be efficiently eliminated according to the results of the first and second discharge inspections.

[0064] [Fourth embodiment] Next, a fourth preferred embodiment of the present invention will be described. The fourth embodiment also relates to a printer 1 similar to the first embodiment. However, in the fourth embodiment, when inspecting each of the multiple nozzles 10 of the inkjet head 4 to determine whether it is an abnormal nozzle, the control unit 80 performs processing according to the flowchart in FIG. 8(a).

[0065] 8(a) in detail, the control unit 80 executes the processes of S501 to S504 similar to S101 to S104 in the first embodiment. However, in the fourth embodiment, the control unit 80 executes a first post-inspection driving process in S502. The first post-inspection driving process and a second post-inspection driving process described later will be described in detail later. Then, if the reduction number ΔN is less than the first number Ma (S504: NO), the control unit 80 executes an end process (S509), and the process ends.

[0066] If the reduced number ΔN is equal to or greater than the first number Ma (S504: YES), the control unit 80 determines whether the reduced number ΔN is equal to or greater than the second number Mb, which is greater than the first number Ma (S505). If the reduced number ΔN is equal to or greater than the second number Mb (S505: YES), the control unit 80 executes a first post-inspection drive process (S506). If the reduced number ΔN is less than the second number Mb (S506: NO), the control unit 80 executes a second post-inspection drive process (S507). After the first post-inspection drive process of S506 or the second post-inspection drive process of S507, the control unit 80 subsequently executes a third discharge inspection process (S508), and subsequently executes an end process (S509), and the process ends.

[0067] In the fourth embodiment, the condition that the reduction number ΔN is equal to or greater than the first number Ma corresponds to the "first condition" of the present invention. Also, in the fourth embodiment, the condition that the reduction number ΔN is equal to or greater than the second number Mb corresponds to the "second condition" of the present invention.

[0068] Here, the first post-inspection driving process of S502 and S506 and the second post-inspection driving process of S507 will be described. In both the first post-inspection driving process and the second post-inspection driving process, the control unit 80 performs the process according to the flowchart of FIG. 5(b) in the same manner as the post-inspection driving process of the first embodiment. In the fourth embodiment, the combination of the non-ejection driving operation, the low frequency driving operation, and the high frequency driving operation repeated Ka times in the first post-inspection driving process corresponds to the "first post-inspection driving operation" of the present invention, and the combination of the non-ejection driving operation, the low frequency driving operation, and the high frequency driving operation repeated Ka times in the second post-inspection driving process corresponds to the "second post-inspection driving operation" of the present invention. In the fourth embodiment, the combination of the first post-inspection driving operation and the operation performed in the third ejection inspection process and the end process corresponds to the "first operation" of the present invention. In the fourth embodiment, the combination of the second post-inspection driving operation and the operation performed in the third ejection inspection process and the end process corresponds to the "second operation" of the present invention.

[0069] However, the first post-inspection driving process and the second post-inspection driving process have different driving conditions for the driving element 90 in the high-frequency ejection driving operation. Specifically, as shown in FIG. 8B, in the first post-inspection driving process, the driving element 90 is driven at the driving frequency F1 for the driving time T1 by applying the driving voltage V1 to the driving element 90 in the high-frequency ejection driving operation. On the other hand, in the second post-inspection driving process, the driving element 90 is driven at the driving frequency F1 for the driving time T2 longer than the driving time T1 by applying the driving voltage V1 to the driving element 90 in the high-frequency ejection driving operation. As a result, the ejection energy imparted to the ink in the nozzle 10 by the second post-inspection driving operation is greater than the ejection energy imparted to the ink in the nozzle 10 by the first post-inspection driving operation.

[0070] <Effects> In the fourth embodiment, if the first condition that the reduced number ΔN is equal to or greater than the first number Ma is not met, the post-inspection driving operation is not performed after the second ejection inspection. On the other hand, if the first condition is met and the second condition that the reduced number ΔN is equal to or greater than the second number Mb that is greater than the first number Ma is met, the first post-inspection driving operation is performed after the second ejection inspection. Also, if the first condition is met but the second condition is not met, the second post-inspection driving operation is performed after the second ejection inspection, in which the ejection energy applied to the ink in the nozzles 10 is greater than that of the first post-inspection driving operation.

[0071] This allows the post-inspection driving operation to be performed after the second ejection inspection only when the number of reductions ΔN is relatively large, and the post-inspection driving operation to be not performed after the second ejection inspection when the number of reductions ΔN is small. Furthermore, when the number of reductions ΔN is sufficiently large, that is, when the effect of eliminating thickening by the first post-inspection driving operation is sufficiently high, the first post-inspection driving operation can be performed after the second ejection inspection to further eliminate thickening. On the other hand, when the number of reductions ΔN is not sufficiently large, that is, when the effect of eliminating thickening by the first post-inspection driving operation is not sufficiently high, the effect of eliminating thickening can be improved by performing the second post-inspection driving operation after the second ejection inspection.

[0072] In addition, in the fourth embodiment, in the second post-inspection driving operation, the driving time of the driving element 90 in the high-frequency ejection driving operation is made longer than in the first post-inspection driving operation, thereby making it possible to increase the ejection energy applied to the ink in the nozzle 10.

[0073] [Fifth embodiment] Next, a fifth preferred embodiment of the present invention will be described. The fifth embodiment also relates to a printer 1 similar to the first embodiment. However, in the fifth embodiment, when inspecting each of the multiple nozzles 10 of the inkjet head 4 to determine whether or not it is an abnormal nozzle, the control unit 80 performs processing according to the flowchart of FIG.

[0074] 9 in detail, the control unit 80 executes the processes of S601 to S604 similar to S301 to S304 in the second embodiment. However, in the fifth embodiment, the control unit 80 executes a first post-inspection driving process in S602. Then, if the ratio [ΔN / N1] is less than the first value Ra (S604: NO), the control unit 80 executes an end process (S609), and the process ends.

[0075] If the ratio [ΔN / N1] is equal to or greater than the first value Ra (S604: YES), the control unit 80 determines whether the ratio [ΔN / N1] is equal to or greater than the second value Rb, which is greater than the first value Ra (S605). If the ratio [ΔN / N1] is equal to or greater than the second value Rb (S605: YES), the control unit 80 executes the first post-inspection drive process (S606), and if the ratio [ΔN / N1] is less than the second value Rb (S606: NO), the control unit 80 executes the second post-inspection drive process (S607). After the first post-inspection drive process of S606 or the second post-inspection drive process of S607, the control unit 80 subsequently executes the third discharge inspection process (S608), and subsequently executes the end process (S609), and the process ends.

[0076] In the fifth embodiment, the condition that the ratio [ΔN / N1] is equal to or greater than the first value Ra corresponds to the "first condition" of the present invention. Also, in the fifth embodiment, the condition that the ratio [ΔN / N1] is equal to or greater than the second value Rb corresponds to the "second condition" of the present invention.

[0077] <Effects> In the fifth embodiment, if the first condition that the ratio [ΔN / N1] is equal to or greater than the first value Ra is not met, the post-inspection driving operation is not performed after the second ejection inspection. On the other hand, if the first condition is met and the second condition that the ratio [ΔN / N1] is equal to or greater than the second value Rb that is greater than the first value Ra is met, the first post-inspection driving operation is performed after the second ejection inspection. Also, if the first condition is met but the second condition is not met, the second post-inspection driving operation is performed after the second ejection inspection, in which the ejection energy applied to the ink in the nozzle 10 is greater than that of the first post-inspection driving operation.

[0078] This allows the post-inspection driving operation to be performed after the second discharge test only when the ratio [ΔN / N1] is relatively large, and the post-inspection driving operation to be not performed after the second discharge test when the ratio [ΔN / N1] is small. Furthermore, when the ratio [ΔN / N1] is sufficiently large, that is, when the effect of eliminating thickening by the first post-inspection driving operation is sufficiently high, the first post-inspection driving operation can be performed after the second discharge test to further eliminate thickening. On the other hand, when the ratio [ΔN / N1] is not sufficiently large, that is, when the effect of eliminating thickening by the first post-inspection driving operation is not sufficiently high, the second post-inspection driving operation can be performed after the second discharge test to improve the effect of eliminating thickening.

[0079] [Sixth embodiment] Next, a sixth preferred embodiment of the present invention will be described. The sixth embodiment also relates to a printer 1 similar to the first embodiment. In the sixth embodiment, as in the third embodiment, six purge levels from "0" to "5" are set, as shown in FIG. 7(a).

[0080] In the sixth embodiment, when inspecting each of the nozzles 10 of the inkjet head 4 to see if it is an abnormal nozzle, the control unit 80 performs processing according to the flowchart of FIG.

[0081] 10 in detail, the control unit 80 executes the processes of S701 to S704 similar to S401 to S404 similar to the third embodiment. However, in the sixth embodiment, the control unit 80 executes the first post-inspection drive process in S702. Then, if the purge level has decreased (S704: YES), the control unit 80 executes the first post-inspection drive process (S705), then executes the third discharge inspection process (S708), and then executes the end process (S709), and the process ends.

[0082] If the purge level has not decreased (S704: NO), the control unit 80 determines whether the purge level corresponding to the number of abnormal nozzles N2 is the same purge level as the purge level corresponding to the number of abnormal nozzles N1, and whether the reduction in the number ΔN is equal to or greater than the third number Mc (S706).

[0083] Here, the third number Mc is a number that is set according to the range of the number of abnormal nozzles corresponding to the purge level corresponding to the number of abnormal nozzles N1. For example, the third number Mc may be a number obtained by dividing the range of the number of abnormal nozzles corresponding to the purge level corresponding to the number of abnormal nozzles N1 by a number A that is greater than 1. In this case, for example, when the purge level corresponding to the number of abnormal nozzles N1 is "2", the range of the number of abnormal nozzles is equal to or greater than N1 and less than N2, while the third number Mc is a number calculated by [(N2-N1) / A].

[0084] If the purge level corresponding to the number of abnormal nozzles N2 is the same purge level as the purge level corresponding to the number of abnormal nozzles N1, and the reduction in number ΔN is greater than or equal to the third number Mc (S706: YES), the control unit 80 executes the second post-inspection drive process (S707), then executes the third ejection inspection process (S708), and then executes the termination process (S709), and the process ends.

[0085] If the purge level corresponding to the number of abnormal nozzles N2 is the same as the purge level corresponding to the number of abnormal nozzles N1, and the reduction number ΔN is less than the third number Mc (S706: NO), the control unit 80 executes termination processing (S709), and the processing ends.

[0086] In the sixth embodiment, the condition that either of the following conditions is satisfied corresponds to the "first condition" of the present invention: (A) the purge level is lowered; and (B) the purge level corresponding to the number of abnormal nozzles N2 is the same as the purge level corresponding to the number of abnormal nozzles N1, and the reduction number ΔN is equal to or greater than the third number Mc. That is, the condition that either of the following conditions is satisfied corresponds to the "first condition" of the present invention: (A) the number of abnormal nozzles N1 is a number within a first range corresponding to a certain purge level, and the number of abnormal nozzles N2 is a number within a second range smaller than the first range corresponding to a purge level lower than the certain purge level; and (B) the number of abnormal nozzles N1 and the number of abnormal nozzles N2 are both numbers within a first range corresponding to the same purge level, and the reduction number ΔN is equal to or greater than the third number Mc determined by the first range. In the sixth embodiment, the above condition (A) corresponds to the "second condition" of the present invention.

[0087] <Effects> In the sixth embodiment, if the first condition is not satisfied, that is, the purge level corresponding to the number of abnormal nozzles N2 is the same as the purge level corresponding to the number of abnormal nozzles N1, and the reduced number ΔN is equal to or greater than the third number Mc, the post-inspection driving operation is not performed after the second ejection inspection. On the other hand, if the first condition is satisfied and the second condition, which is the condition (A), is satisfied, the first post-inspection driving operation is performed after the second ejection inspection. Also, if the first condition is satisfied but the second condition is not satisfied, the second post-inspection driving operation is performed after the second ejection inspection, in which the ejection energy applied to the ink in the nozzles 10 is greater than that of the first post-inspection driving operation.

[0088] This allows the post-inspection driving operation to be performed after the second ejection inspection when the number of abnormal nozzles reduced by the first post-inspection driving operation after the first ejection inspection is relatively large, and the post-inspection driving operation with a low viscosity reduction effect to be not performed after the second ejection inspection when the number of abnormal nozzles reduced by the first post-inspection driving operation after the first ejection inspection is small. Furthermore, when the number of abnormal nozzles reduced by the first post-inspection driving operation after the first ejection inspection is large enough to lower the purge level, that is, when the viscosity reduction effect of the first post-inspection driving operation is sufficiently high, the first post-inspection driving operation can be performed after the second ejection inspection to further reduce viscosity. On the other hand, when the number of abnormal nozzles is reduced to a certain extent by the first post-inspection driving operation after the first ejection inspection, but the purge level is maintained before and after the first post-inspection driving operation, that is, when the viscosity reduction effect of the first post-inspection driving operation is not sufficiently high, the second post-inspection driving operation can be performed after the second ejection inspection to improve the viscosity reduction effect.

[0089] [Seventh to Twelfth Embodiments] Next, preferred seventh to twelfth embodiments of the present invention will be described. The seventh to twelfth embodiments also relate to a printer 1 similar to the first embodiment. In the seventh to twelfth embodiments, when inspecting each of the multiple nozzles 10 of the inkjet head 4 to determine whether or not it is an abnormal nozzle, the control unit 80 performs processing according to any one of the flowcharts of FIG. 8(a), FIG. 9, or FIG. 10. When the control unit 80 performs processing according to the flowchart of FIG. 10, six purge levels from "0" to "5" are set, as in the third embodiment, as shown in FIG. 7(a).

[0090] However, in the seventh to twelfth embodiments, the first post-inspection driving process and the second post-inspection driving process are different from those described in the fourth embodiment. The first post-inspection driving process and the second post-inspection driving process in each embodiment will be described below.

[0091] 11(a), in the high-frequency ejection drive operation performed in the first post-inspection drive process, the drive element 90 is driven J1 times at the drive frequency F1 by applying a drive voltage V1 to the drive element 90. Meanwhile, in the high-frequency ejection drive operation performed in the second post-inspection drive process, the drive element 90 is driven J2 times, which is greater than the drive frequency J1, at the drive frequency F1 by applying a drive voltage V1 to the drive element 90.

[0092] <Effects> In the seventh embodiment, in the second post-test driving operation, the number of times the driving element 90 is driven in the high-frequency ejection driving operation is greater than in the first post-test driving operation, thereby making it possible to increase the ejection energy imparted to the ink in the nozzle 10.

[0093] 11(b), in the high-frequency ejection drive operation performed in the first post-inspection drive process, the drive element 90 is driven at a drive frequency F1 for a drive time T1 by applying a drive voltage V1 to the drive element 90. Meanwhile, in the high-frequency ejection drive operation performed in the second post-inspection drive process, the drive element 90 is driven at a drive frequency F2, which is higher than the drive frequency F1, for a drive time T1 by applying a drive voltage V1 to the drive element 90.

[0094] 11(c), in the high-frequency ejection drive operation performed in the first post-inspection drive process, the drive element 90 is driven J1 times at a drive frequency F1 by applying a drive voltage V1 to the drive element 90. Meanwhile, in the high-frequency ejection drive operation performed in the second post-inspection drive process, the drive element 90 is driven J1 times at a drive frequency F2 higher than the drive frequency F1 by applying a drive voltage V1 to the drive element 90.

[0095] <Effects> In the eighth and ninth embodiments, in the second post-inspection driving operation, the driving frequency of the driving element 90 in the high-frequency ejection driving operation is made higher than that in the first post-inspection driving operation, thereby making it possible to increase the ejection energy imparted to the ink in the nozzle 10.

[0096] 11(d), in the high-frequency ejection drive operation performed in the first post-inspection drive process, the drive element 90 is driven at the drive frequency F1 for the drive time T1 by applying a drive voltage V1 to the drive element 90. Meanwhile, in the high-frequency ejection drive operation performed in the second post-inspection drive process, the drive element 90 is driven at the drive frequency F1 for the drive time T1 by applying a drive voltage V2 higher than the drive voltage V1 to the drive element 90.

[0097] 11(e), in the high-frequency ejection drive operation performed in the first post-inspection drive process, the drive element 90 is driven J1 times at the drive frequency F1 by applying a drive voltage V1 to the drive element 90. Meanwhile, in the high-frequency ejection drive operation performed in the second post-inspection drive process, the drive element 90 is driven J1 times at the drive frequency F1 by applying a drive voltage V2 higher than the drive voltage V1 to the drive element 90.

[0098] <Effects> In the tenth and eleventh embodiments, in the second post-inspection driving operation, the driving voltage applied to the driving element 90 in the high-frequency ejection driving operation is made higher than that in the first post-inspection driving operation, thereby making it possible to increase the ejection energy imparted to the ink in the nozzle 10.

[0099] In the twelfth embodiment, in both the first inspection post-drive process and the second inspection post-drive process, when performing the process according to the flowchart of FIG. 5(b), the same non-ejection drive operation, low-frequency drive operation, and high-frequency drive operation are performed. However, in the twelfth embodiment, the value of the predetermined value Ka when performing the process according to the flowchart of FIG. 5(b) is made different between the first inspection post-drive process and the second inspection post-drive process. Specifically, as shown in FIG. 11(f), when executing the first inspection post-drive process, the predetermined value Ka is set to Ka1. Also, when executing the second inspection post-drive process, the predetermined value Ka is set to Ka2, which is larger than Ka1. That is, in the twelfth embodiment, in the second inspection post-drive process, the number of repetitions of the non-ejection drive operation, low-frequency drive operation, and high-frequency drive operation is increased compared to the first inspection post-drive process.

[0100] <Effect> In the twelfth embodiment, in the second inspection post-drive operation, by increasing the number of repetitions of the non-ejection drive operation, low-frequency drive operation, and high-frequency ejection drive operation compared to the first inspection post-drive operation, the ejection energy applied to the ink in the nozzle 10 can be increased.

[0101] [Thirteenth Embodiment] Next, a preferred thirteenth embodiment of the present invention will be described. The thirteenth embodiment also relates to the same printer 1 as in the first embodiment. However, in the thirteenth embodiment, when inspecting each of the plurality of nozzles 10 of the inkjet head 4 to determine whether it is an abnormal nozzle, the control unit 80 performs the process according to the flowchart of FIG. 12.

[0102] Explaining the flowchart of FIG. 12 in detail, the control unit 80 executes the first ejection inspection process (S801). Subsequently, the control unit 80 determines whether the number of abnormal nozzles N1 is less than the fourth number Nf, and whether the number of abnormal nozzles N1 is abnormal with respect to the fifth number Ng (S802, S803). Here, the fourth number Nf and the fifth number Ng are numbers that satisfy the magnitude relationship of 0 < Nf < Ng < Nt, where Nt is the number of nozzles 10 of the inkjet head 4.

[0103] If the number of abnormal nozzles N1 is not less than the fourth number Nf (S802: NO) and the number of abnormal nozzles N1 is not greater than or equal to the fifth number Ng (S803: NO), that is, if the number of abnormal nozzles N1 is greater than or equal to the fourth number Nf and less than the fifth number Ng, the control unit 80 executes a post-inspection drive process (S804), and then executes a second ejection inspection process (S805).

[0104] Next, the control unit 80 judges whether or not a first condition is satisfied (S805). The first condition in S805 is, for example, the same condition as the first condition in any of the first to third embodiments. If the first condition is satisfied (S805: YES), the control unit 80 executes a post-inspection drive process (S807), then executes a third ejection inspection process (S808), then executes an end process (S809), and the process ends. If the first condition is not satisfied (S805: NO), the control unit 80 executes an end process (S809), and the process ends.

[0105] If the number N1 of abnormal nozzles is less than the fourth number Nf (S802: YES), the control unit 80 executes an end process (S809), and the process ends.

[0106] If the number N1 of abnormal nozzles is equal to or greater than the fifth number Ng (S802: NO, S803: YES), the control unit 80 executes a purge process (S810). In the purge process, the control unit 80 controls the carriage motor 86, the cap lifting mechanism 88, the suction pump 72, etc. to perform suction purging. Next, the control unit 80 executes a third discharge inspection process (S808), and then executes an end process (S809), ending the process.

[0107] <Effects> In the thirteenth embodiment, when the number of abnormal nozzles N1 is relatively large, such as the fourth number Nf or more, a post-inspection driving operation is performed after the first ejection inspection, thereby further eliminating the thickening. Also, when the number of abnormal nozzles N1 is small, such as less than the fourth number Nf, there is little need to eliminate the thickening, so by not performing the post-inspection driving operation after the first ejection inspection, it is possible to prevent the unnecessary post-inspection driving operation from being performed. Also, when the number of abnormal nozzles N1 is too large, such as the fifth number Ng or more, the ink in the inkjet head 4 has significantly thickened, and there is a low possibility that the thickening will be eliminated even if a post-inspection driving operation is performed after the first ejection inspection, so by not performing the post-inspection driving operation after the first ejection inspection, it is possible to prevent the unnecessary post-inspection driving operation from being performed.

[0108] Furthermore, in the thirteenth embodiment, if the number N1 of abnormal nozzles is too large, equal to or greater than the fifth number Ng, the thickening of the ink in the nozzles 10 can be eliminated by performing a suction purge after the first ejection test.

[0109] [Fourteenth embodiment] Next, a fourteenth embodiment of the present invention will be described. The fourteenth embodiment also relates to a printer 1 similar to the first embodiment. However, in the fourteenth embodiment, when inspecting each of the multiple nozzles 10 of the inkjet head 4 to determine whether it is an abnormal nozzle, the control unit 80 performs processing according to the flowchart of FIG.

[0110] 13 in detail, the control unit 80 executes a first discharge inspection process similar to S101 in the first embodiment (S901). Next, the control unit 80 determines whether the number N1 of abnormal nozzles is less than the fourth number Nf and whether the number N1 of abnormal nozzles is equal to or greater than the fifth number Ng (S902, S903).

[0111] When the number of abnormal nozzles is not less than the fourth number Nf (S902: NO) and the number of abnormal nozzles N1 is not greater than the fifth number Ng (S903: NO), that is, when the number of abnormal nozzles N1 is not less than the fourth number Nf and less than the fifth number Ng, the control unit 80 determines whether the number of abnormal nozzles N1 is not less than the fourth number Nf and less than the sixth number Nh (S904). Here, the sixth number Nh is a number that satisfies the magnitude relationship of Nf < Nh < Ng. When the number of abnormal nozzles N1 is not less than the fourth number Nf and less than the sixth number Nh (S904: YES), the control unit 80 determines whether the number of abnormal nozzles N1 is not less than the fourth number Nf and less than the seventh number Ni (S905). Here, the seventh number Ni is a number that satisfies the magnitude relationship of Nf < Ni < Nh.

[0112] When the number of abnormal nozzles N1 is not less than the seventh number Ni and less than the sixth number Nh (S905: NO), the control unit 80 executes the first inspection post-drive process (S906). The first inspection post-drive process of S906 is the same process as the first inspection post-drive process of any of the fourth to twelfth embodiments.

[0113] When the number of abnormal nozzles N1 is not less than the fourth number Nf and less than the seventh number Ni (S905: YES), the control unit 80 executes the third inspection post-drive process (S907). Also in the third inspection post-drive process, the control unit 80 causes the non-ejection drive operation, the low-frequency ejection drive operation, and the high-frequency ejection drive operation to be performed in the same manner as in the first inspection post-drive process. Further, in the third inspection post-drive process, the control unit 80 makes the ejection energy applied to the ink in the nozzle 10 smaller than that in the first inspection post-ejection drive process by making the drive condition of the drive element 90 in the high-frequency ejection drive operation different from that in the first inspection post-drive process.

[0114] For example, in the third post-inspection drive process, the drive time of the drive element 90 in the high-frequency ejection drive operation is made shorter than that in the first post-inspection drive process. Alternatively, for example, in the third post-inspection drive process, the drive frequency of the drive element 90 in the high-frequency ejection drive operation is made lower than that in the first post-inspection drive process. Alternatively, for example, in the third post-inspection drive process, the number of times the drive element 90 is driven in the high-frequency ejection drive operation is made smaller than that in the first post-inspection drive process. Alternatively, for example, in the third post-inspection drive process, the drive voltage of the drive element 90 in the high-frequency ejection drive operation is made lower than that in the first post-inspection drive process. Alternatively, in the third post-inspection drive process, the number of times the above three types of drive operations are repeated in the high-frequency ejection drive operation is made smaller than that in the first post-inspection drive process. In the fourteenth embodiment, the non-ejection drive operation, the low-frequency ejection drive operation, and the high-frequency ejection drive operation performed in the first post-inspection drive process of S906 and the third post-inspection drive process of S907 correspond to the "first post-inspection drive operation" of the present invention.

[0115] If the number N1 of abnormal nozzles is equal to or greater than the sixth number Nh and less than the fifth number Ng (S904: NO), the control unit 80 executes a second post-inspection drive process (S908). The second post-inspection drive process of S908 is the same process as the second post-inspection drive process of any of the fourth to twelfth embodiments.

[0116] After executing any one of the first post-inspection drive process of S906, the third post-inspection drive process of S907, and the second post-inspection drive process of S908, the control unit 80 executes a second discharge inspection process (S909), and then determines whether or not a first condition is satisfied (S910). The first condition in S910 is, for example, the same condition as the first condition in any one of the first to third embodiments.

[0117] If the first condition is satisfied (S910: YES), the control unit 80 executes the first post-inspection drive process (S911), then executes the third ejection inspection process (S912), then executes the termination process (S913), and the process ends. If the first condition is not satisfied (S910: NO), the control unit 80 executes the termination process (S913), and the process ends.

[0118] If the number of abnormal nozzles N1 is less than the fourth number Nf (S902: YES), the control unit 80 executes a termination process (S913) and the process ends. If the number of abnormal nozzles N1 is equal to or greater than the fifth number Ng (S902: NO, S903: YES), the control unit 80 executes a purge process (S914), then executes a third discharge inspection process (S912), then executes a termination process (S913), and the process ends.

[0119] <Effects> The greater the number of abnormal nozzles, the greater the possibility that the ink has thickened. In the fourteenth embodiment, if the number of abnormal nozzles N1 is in a range of the fourth number Nf or more and less than the sixth number Nh among the range of the number of abnormal nozzles N1 being the fourth number Nf or more and less than the fifth number Ng, a first post-test driving operation is performed after the first ejection test. Also, if the number of abnormal nozzles N1 is in a range of the sixth number Nh or more and less than the fifth number Ng among the range of the fourth number Nf or more and less than the fifth number Ng, a second post-test driving operation is performed after the first ejection test, in which the ejection energy applied to the ink in the nozzles 10 is greater than that of the first post-test driving operation. This allows the post-test driving operation after the first ejection test to be appropriate according to the degree of thickening of the ink.

[0120] [Fifteenth embodiment] Next, a fifteenth embodiment of the present invention will be described. The fifteenth embodiment also relates to a printer 1 similar to the first embodiment. However, in the fifteenth embodiment, when inspecting each of the multiple nozzles 10 of the inkjet head 4 to determine whether or not it is an abnormal nozzle, the control unit 80 performs processing according to the flowchart of FIG.

[0121] 14 in detail, the control unit 80 executes the processes of S1001 to S1003 similar to S101 to S103 in the first embodiment. Next, the control unit 80 determines whether the number of abnormal nozzles N1 is less than the fourth number Nf (S1004). If the number of abnormal nozzles N1 is equal to or greater than the fourth number Nf (S1004: NO), the control unit 80 executes the processes of S1005 to S1008 similar to S806 to S809 in the thirteenth embodiment, and the process ends.

[0122] If the number of abnormal nozzles N1 is less than the fourth number Nf (S1004: YES), the control unit 80 executes the end process (S1008), and the process ends. In other words, if the number of abnormal nozzles N1 is less than the fourth number Nf, the control unit 80 does not execute the post-inspection drive process after the second ejection inspection.

[0123] <Effects> If the number of abnormal nozzles N1 is sufficiently small, the number of abnormal nozzles will also be sufficiently small after the post-test drive operation following the first discharge test. Therefore, in this invention, in such a case, regardless of the result of the second discharge test, the post-test drive operation is not performed after the second discharge test. This makes it possible to prevent unnecessary post-test drive operations from being performed.

[0124] [Sixteenth embodiment] Next, a sixteenth embodiment of the present invention will be described. The sixteenth embodiment also relates to a printer 1 similar to the first embodiment. However, in the sixteenth embodiment, when inspecting each of the multiple nozzles 10 of the inkjet head 4 to determine whether or not it is an abnormal nozzle, the control unit 80 performs processing according to the flowchart of FIG.

[0125] 15 in detail, the control unit 80 executes the processes of S1101 to S1103 similar to S501 to S503 in the fourth embodiment. Then, the control unit 80 determines whether or not a first condition is satisfied (S1104). Here, the first condition in S1104 is, for example, any one of the first conditions described in the first to third embodiments.

[0126] If the first condition is satisfied (S1104: YES), the control unit 80 executes a first post-inspection drive process (S1105). If the first condition is not satisfied (S1104: NO), the control unit 80 executes a second post-inspection drive process (S1106). The first post-inspection drive process of S1102 and S1105, and the second post-inspection drive process of S1106 are similar to those described in any of the fourth to twelfth embodiments.

[0127] After executing either the first post-inspection drive process in S1105 or the second post-inspection drive process in S1106, the control unit 80 executes a third ejection inspection process (S1107), and then executes an end process (S1108), whereupon the process ends.

[0128] <Effects> In the sixteenth embodiment, by differentiating the driving conditions of the driving element 90 in at least one of a plurality of types of driving operations between a first post-test driving operation performed in the first operation and a second post-test driving operation performed in the second operation, it is possible to efficiently eliminate ink thickening depending on the results of the first and second ejection tests.

[0129] [Seventeenth embodiment] Next, a seventeenth embodiment of the present invention will be described. The seventeenth embodiment also relates to a printer 1 similar to the first embodiment. However, in the seventeenth embodiment, while power is being supplied to the printer 1, the control unit 80 performs processing according to the flowchart of FIG.

[0130] 16 in detail, the control unit 80 stands by when it is not the predetermined time (S1201: NO) and when it has not received a recording instruction signal instructing recording on the recording paper S (S1202: NO). In the seventeenth embodiment, the recording instruction signal corresponds to the "ejection instruction signal" of the present invention.

[0131] When the specified time arrives (S1201: YES), the control unit 80 executes the processes of S1203 to S1205 which are similar to S101 to S103 in the first embodiment, and then executes the processes of S1206 to S1208 and S1212 which are similar to S806 to S809 in the 13th embodiment, and the process returns to S1201.

[0132] Furthermore, when a recording instruction signal is received (S1202: YES), the control unit 80 determines whether or not a third condition is satisfied for the result of the last executed second ejection test (S1209). Here, the third condition is a condition that is satisfied when the result of the second ejection test indicates a high need for purging before recording on the recording paper S. The third condition may be, for example, a condition that "the number N2 of abnormal nozzles is equal to or greater than a predetermined number." Alternatively, the third condition may be, for example, a condition that "the ratio [N2 / Nt] of the number N2 of abnormal nozzles to the number Nt of nozzles 10 of the inkjet head 4 is equal to or greater than a predetermined value."

[0133] If the third condition is satisfied (S1209: YES), the control unit 80 executes a purge process (S1210), and then executes a recording process (S1211). If the third condition is not satisfied (S1209: NO), the control unit 80 executes a recording process (S1211) without executing a purge process. In the recording process of S1211, the control unit 80 causes the recording pass and the conveying operation to be repeated, as described in the first embodiment, to perform recording on the recording paper S. Then, after the recording process of S1211 is completed, the control unit 80 executes an end process (S1212), and the process returns to S1201.

[0134] <Effects> In the seventeenth embodiment, at a predetermined time, a first ejection test, a post-test drive operation thereafter, and a second ejection test thereafter are performed, and then, depending on whether a first condition is satisfied, it is determined whether to perform a first operation including a post-test drive operation after the second ejection test, or a second operation not including a post-test drive operation. This makes it possible to efficiently eliminate thickening of the ink depending on the results of the first and second ejection tests.

[0135] Then, when a recording instruction signal is received thereafter, depending on whether the third condition is satisfied, it is determined whether or not to perform suction purging before recording on the recording paper S. In this way, purging can be performed before ejecting ink onto the recording paper S only when it is highly necessary.

[0136] [Eighteenth embodiment] Next, a preferred 18th embodiment of the present invention will be described. The 18th embodiment also relates to a printer 1 similar to the first embodiment. However, in the 18th embodiment, when inspecting each of the multiple nozzles 10 of the inkjet head 4 to determine whether it is an abnormal nozzle, the control unit 80 performs processing according to the flowchart of FIG.

[0137] To explain the flowchart of FIG. 17 in detail, the control unit 80 executes a first ejection inspection process (S1301). Then, the control unit 80 executes a cleaning process (S1302). In the cleaning process, the control unit 80 performs a cleaning operation to eliminate the abnormality in the ejection of liquid from the abnormal nozzle. For example, in the cleaning process, the control unit 80 controls the carriage motor 86, the cap lifting mechanism 88, the suction pump 72, etc. to perform suction purging as the cleaning operation. Alternatively, for example, in the cleaning process, the control unit 80 controls the multiple drive elements 90, etc. to perform flushing to discharge ink from the abnormal nozzle as the cleaning operation. Alternatively, for example, in the cleaning process, the control unit 80 controls the multiple drive elements 90, etc. to perform a non-ejection drive operation to vibrate the ink in the abnormal nozzle as the cleaning operation.

[0138] Next, a second discharge inspection process is executed (S1303), and it is determined whether or not a predetermined condition is satisfied (S1304). The predetermined condition is a condition regarding the relationship between the result of the first discharge inspection and the result of the second discharge inspection. The predetermined condition is, for example, the same condition as the first condition in any of the first to third embodiments. If the predetermined condition is satisfied (S1304: YES), the control unit 80 executes a cleaning process similar to S1302 (S1305), then executes a third discharge inspection process (S1306), then executes an end process (S1307), and the process ends. If the predetermined condition is not satisfied (S1304: NO), the control unit 80 executes an end process (S1307), and the process ends.

[0139] <Effects> In the eighteenth embodiment, a cleaning operation is performed after the first discharge test, and then a second discharge test is performed. Depending on whether a predetermined condition is satisfied regarding the relationship between the results of the first discharge test and the results of the second discharge test, it is determined whether to perform a first operation including a cleaning operation or a second operation different from the first operation after the second discharge test. This makes it possible to efficiently eliminate the thickening of the ink in the nozzle 10 according to the results of the first and second discharge tests. For example, if the effect of eliminating the thickening by the cleaning operation after the first discharge test is high, the first operation including the cleaning operation can be performed after the second discharge test to further eliminate the thickening. On the other hand, for example, if the effect of eliminating the thickening by the cleaning operation after the first discharge test is low, the second operation different from the first operation can be performed after the second discharge test to prevent the cleaning operation with a low effect of eliminating the thickening from being repeated.

[0140] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and various modifications are possible within the scope of the claims.

[0141] In the third and sixth embodiments, the first and second ranges in the first condition correspond to the purge level, but are not limited to this. The first and second ranges in the first condition may be set regardless of the purge level.

[0142] In the fourth to twelfth, fourteenth and sixteenth embodiments, the ejection energy applied to the ink in the nozzle 10 is made different between the first post-inspection drive process and the second post-inspection drive process by making one of the drive time of the drive element 90, the drive count of the drive element 90, the drive frequency of the drive element 90 and the drive voltage applied to the drive element 90 different in the high-frequency ejection drive operation, or by making the number of repetitions of the non-ejection drive operation, the low-frequency ejection drive operation and the high-frequency ejection drive operation different. In the fourteenth embodiment, the ejection energy applied to the ink in the nozzle 10 is made different between the first post-inspection drive process and the third post-inspection drive process by making one of the drive time of the drive element 90, the drive count of the drive element 90, the drive frequency of the drive element 90 and the drive voltage applied to the drive element 90 different in the high-frequency ejection drive operation, or by making the number of repetitions of the non-ejection drive operation, the low-frequency ejection drive operation and the high-frequency ejection drive operation different. However, this is not limited to this.

[0143] For example, between the first post-inspection driving process and the second post-inspection driving process, or between the first post-inspection driving process and the third post-inspection driving process, two or more of the driving time of the driving element 90, the number of times the driving element 90 is driven, the driving frequency of the driving element 90, and the driving voltage applied to the driving element 90 in the high-frequency ejection driving operation may be different.

[0144] Alternatively, between the first post-inspection driving process and the second post-inspection driving process, or between the first post-inspection driving process and the third post-inspection driving process, at least one of the driving time of the driving element 90, the number of times the driving element 90 is driven, the driving frequency of the driving element 90, and the driving voltage applied to the driving element 90 in the high-frequency ejection driving operation may be made different, and the number of times the non-ejection driving operation, the low-frequency ejection driving operation, and the high-frequency ejection driving operation are repeated may be made different.

[0145] Alternatively, for example, between the first post-inspection driving process and the second post-inspection driving process, or between the first post-inspection driving process and the third post-inspection driving process, at least one of the driving time of the driving element 90, the number of times the driving element 90 is driven, the driving frequency of the driving element 90, and the driving voltage applied to the driving element 90 in at least one of the non-ejection driving and low-frequency ejection driving operations may be made different.

[0146] Alternatively, for example, between the first post-inspection driving process and the second post-inspection driving process, or between the first post-inspection driving process and the third post-inspection driving process, at least one of the driving time of the driving element 90, the number of times the driving element 90 is driven, the driving frequency of the driving element 90, and the driving voltage applied to the driving element 90 may be different in two or more driving operations among the non-ejection driving operation, the low-frequency ejection driving operation, and the high-frequency ejection driving operation.

[0147] In addition, between the first post-inspection driving process and the second post-inspection driving process, or between the first post-inspection driving process and the third post-inspection driving process, parameters other than those mentioned above, such as the driving waveform of the driving element 90, may be different in at least one of the driving operations among the non-ejection driving operation, the low-frequency ejection driving operation, and the high-frequency ejection driving operation.

[0148] In the first to seventeenth embodiments, three types of drive operations, that is, the non-ejection drive operation, the low-frequency ejection drive operation, and the high-frequency ejection drive operation, are performed in the post-inspection drive process, but the present invention is not limited to this.

[0149] For example, in the post-inspection driving process, two types of ejection driving operations, a non-ejection driving operation and an ejection driving operation, may be performed. In this case, the driving frequency of the driving element 90 in the ejection driving operation may be the same as either the low-frequency ejection driving or the high-frequency ejection driving, or may be different from either the low-frequency ejection driving or the high-frequency ejection driving. Alternatively, in the post-inspection driving process, two types of driving operations, a low-frequency ejection driving operation and a high-frequency ejection driving operation, may be performed.

[0150] Alternatively, four or more types of driving operations may be performed in the post-inspection driving process. In this case, the four or more types of driving operations may include one type of non-ejection driving operation, two or more types of non-ejection driving operations with different driving frequencies of the driving element 90, one type of ejection driving operation, or two or more types of ejection driving operations with different driving frequencies of the driving element 90.

[0151] In the fourteenth embodiment, when the number of abnormal nozzles N1 is equal to or greater than the fourth number Nf and less than the sixth number Nh, the first inspection drive process is executed when the number of abnormal nozzles N1 is equal to or greater than the seventh number Ni and less than the sixth number Nh, and the third post-inspection drive process is executed when the number of abnormal nozzles N1 is equal to or greater than the fourth number Nf and less than the seventh number Ni, but this is not limiting. For example, when the number of abnormal nozzles N1 is equal to or greater than the fourth number Nf and less than the sixth number Nh, the first post-inspection drive process may be executed in all cases.

[0152] In the thirteenth and fourteenth embodiments, the purging process is performed when the number N1 of abnormal nozzles is equal to or greater than the fifth number Ng, but this is not limiting. When the number N1 of abnormal nozzles is equal to or greater than the fifth number Ng, the purging process and the subsequent third ejection inspection process do not have to be performed. In this case, for example, a message or the like urging replacement of the inkjet 4 may be displayed on the operation panel 69.

[0153] In the first to seventeenth embodiments, in the post-inspection drive processing after the first ejection test, the non-ejection drive operation, the low-frequency ejection drive operation, and the high-frequency drive operation are performed only on the nozzles 10 that are shown to be abnormal as a result of the first ejection test, but this is not limited to this. In the post-inspection drive processing after the first ejection test, the non-ejection drive operation, the low-frequency ejection drive operation, and the high-frequency drive operation may be performed on all the nozzles 10 of the inkjet head 4.

[0154] In the first to eighteenth embodiments, in the second ejection test, only the nozzles 10 that are shown to be abnormal in the results of the first ejection test are inspected to see if they are abnormal, but this is not limited to this. In the second ejection test, all nozzles 10 of the inkjet head 4 may be inspected to see if they are abnormal.

[0155] In the first to seventeenth embodiments, in the post-inspection drive process after the second ejection inspection, the non-ejection drive operation, the low-frequency ejection drive operation, and the high-frequency drive operation are performed only on the nozzles 10 that are shown to be abnormal nozzles as a result of the second ejection inspection process, but this is not limited to this. In the post-inspection drive process after the second ejection inspection, the non-ejection drive operation, the low-frequency ejection drive operation, and the high-frequency drive operation may be performed on all the nozzles 10 of the inkjet head 4.

[0156] In the first to eighteenth embodiments, in the third ejection inspection process, only the nozzles 10 that are shown to be abnormal in the results of the second ejection inspection process are inspected to see if they are abnormal, but this is not limited to this. In the third ejection inspection process, all the nozzles 10 of the inkjet head 4 may be subjected to a non-ejection drive operation, a low-frequency ejection drive operation, and a high-frequency drive operation.

[0157] Furthermore, in the first to seventeenth embodiments, when a post-inspection drive process is executed after the second ejection inspection process, the third ejection inspection process is executed after this post-inspection drive process. Furthermore, in the eighteenth embodiment, when a cleaning process is executed after the second ejection inspection process, the third ejection inspection process is executed after this cleaning process. However, this is not limited to this. In these cases, the third ejection inspection process may not be executed, and the ejection inspection process may be executed again later when information on the results of the ejection inspection becomes necessary.

[0158] In the first to seventeenth embodiments, the first condition for determining whether to perform the first operation or the second operation after the second discharge inspection is not limited to the one described in the above example, and may be another condition regarding the relationship between the result of the first discharge inspection and the result of the second discharge inspection. In the first to seventeenth embodiments, when a post-inspection driving operation is performed after the second discharge inspection, the second condition for determining whether to perform the first post-inspection driving operation or the second post-inspection driving operation is not limited to the one described in the above example, and may be another condition regarding the relationship between the result of the first discharge inspection and the result of the second discharge inspection. In the eighteenth embodiment, the predetermined condition for determining whether to perform the first operation or the second operation after the second discharge inspection is not limited to the one described in the above example, and may be another condition regarding the relationship between the result of the first discharge inspection and the result of the second discharge inspection.

[0159] Moreover, the first operation and the second operation are not limited to those described above. In the first to seventeenth embodiments, the first operation may be another operation including a post-inspection driving operation. In the eighteenth embodiment, the first operation may be another operation including a cleaning operation. In the first to eighteenth embodiments, the second operation may be another operation different from the first operation described above. In the first to seventeenth embodiments, the second operation may not include a post-inspection driving operation, or may include a post-inspection driving operation of a different type from the first operation. In the eighteenth embodiment, the second operation may not include a cleaning operation, or may include a cleaning operation of a different type from the first operation.

[0160] In the above example, the printer 1 performs suction purge as a purge, but this is not limited to this. For example, a pressure pump that pressurizes the ink in the inkjet head 4 may be provided in a flow path between the ink cartridge and the inkjet head 4. Then, with the nozzles 10 covered with the cap 71, the pressure pump may be driven to perform a pressure purge that discharges the ink in the inkjet head 4. In this case, the combination of the cap 71 and the pressure pump corresponds to the "purge unit" of the present invention.

[0161] In addition, both the suction purge by driving the suction pump 72 and the pressure purge by driving the pressure pump may be performed. In this case, the combination of the maintenance unit 8 and the pressure pump corresponds to the "purge section" of the present invention.

[0162] In the above embodiment, a test drive operation is performed on the inkjet head 4, and the signal output from the signal processing circuit 78 in response to a change in voltage from the nozzle 10 to the electrode 76 arranged in the cap 71 is used to check whether or not the nozzle is abnormal. However, this is not limited to this.

[0163] For example, instead of electrode 76, an electrode may be provided that extends vertically and faces the space below nozzle 10 when carriage 2 is in the maintenance position. Then, signal processing circuit 78 may output a signal corresponding to the change in voltage of the electrode when an inspection drive operation is performed with carriage 2 in the maintenance position, and based on this signal it may be possible to inspect whether or not a nozzle is abnormal.

[0164] Alternatively, for example, an optical sensor may be provided that directly detects ink ejected from the nozzles 10 and outputs a signal according to the detection result while the carriage 2 is in a predetermined position such as a maintenance position. Then, based on the signal output from this optical sensor, it may be possible to inspect whether or not a nozzle is abnormal.

[0165] Alternatively, for example, whether or not a nozzle is abnormal may be inspected in the same manner as described in Japanese Patent No. 4929699. Specifically, a voltage detection circuit that detects a change in voltage when ink is ejected from a nozzle may be connected to a plate on which the nozzles of an inkjet head are formed, and whether or not a nozzle is abnormal may be inspected based on a signal output from the voltage detection circuit when an operation to eject ink from the nozzle is performed with the carriage moved to the inspection position.

[0166] Alternatively, for example, it may be possible to check whether a nozzle is abnormal in the same manner as described in Japanese Patent No. 6231759. Specifically, the substrate of the inkjet head may be provided with a temperature detection element. Then, after applying a first applied voltage to drive the heater for ink ejection, a second applied voltage is applied to drive the heater so that ink is not ejected, and it may be possible to check whether a nozzle is abnormal based on the change in temperature detected by the temperature detection element during the period from when the second applied voltage is applied until a predetermined time has elapsed.

[0167] Alternatively, for example, it may be possible to inspect whether a nozzle is abnormal in the same manner as described in JP 2004-284189 A, JP 2011-240563 A, etc. Specifically, in the case of an inkjet head in which a piezoelectric element applies pressure to ink in a pressure chamber communicating with the nozzle to cause the ink to be ejected from the nozzle, a residual vibration inspection device may be provided that detects residual vibrations generated in the piezoelectric element due to pressure changes in the ink in the pressure chamber. Then, it may be possible to inspect whether a nozzle is abnormal based on the vibration pattern of the residual vibrations detected by the residual vibration inspection device when the piezoelectric element is driven to eject ink from the nozzle.

[0168] In the above, an example has been described in which the present invention is applied to a printer equipped with a so-called serial head that ejects ink from multiple nozzles while moving in the scanning direction together with the carriage, but the present invention is not limited to this. For example, the present invention can also be applied to a printer equipped with a so-called line head that extends across the entire length of the recording paper in the scanning direction.

[0169] In the above, an example of applying the present invention to a printer that ejects ink from nozzles to perform recording on 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 device that records images on recording media other than recording paper, such as T-shirts, sheets for outdoor advertising, cases for mobile terminals such as smartphones, cardboard, and resin members. The present invention can also be applied to a liquid ejection device that ejects liquid other than ink droplets, such as liquid resin or metal liquid. [Explanation of symbols]

[0170] 1: Printer 4: Inkjet head 8: Maintenance unit 10: Nozzle 20: Discharge inspection section 80: Control unit 84: Memory 90: Drive element

Claims

1. a head having a plurality of nozzles and a plurality of drive elements that apply ejection energy to liquid in the plurality of nozzles; a discharge inspection unit that performs a discharge inspection to inspect whether the nozzle is an abnormal nozzle having an abnormality in discharging liquid; A control unit, The control unit is causing the discharge inspection unit to perform a first discharge inspection; After the first ejection inspection, a post-inspection driving operation including a plurality of types of driving operations in which the driving elements are driven at different driving frequencies is performed on the plurality of driving elements; After the post-inspection driving operation, the ejection inspection unit is caused to perform a second ejection inspection; when a first condition regarding a relationship between a result of the first ejection test and a result of the second ejection test is satisfied, a first operation including the post-inspection driving operation is performed after the second ejection test; If the first condition is not satisfied, a second operation different from the first operation is performed after the second ejection inspection.

2. The liquid ejection apparatus according to claim 1, wherein the second operation does not include the post-inspection driving operation.

3. The control unit is performing the post-inspection driving operation after the first ejection inspection and the second ejection inspection only for the nozzles which are indicated as being abnormal nozzles as a result of the first ejection inspection; 3. The liquid ejection device according to claim 2, wherein the post-inspection drive operation in the first operation is performed only on the nozzles that are shown to be abnormal nozzles as a result of the second ejection inspection.

4. The liquid ejection device according to claim 1, characterized in that the first condition is a condition that the number of abnormal nozzles indicated by the result of the second ejection test is reduced by a first number from the number of abnormal nozzles indicated by the result of the first ejection test.

5. The liquid ejection device described in claim 1, characterized in that the first condition is a condition that the ratio of the number of abnormal nozzles indicated by the result of the second ejection test to the number of abnormal nozzles indicated by the result of the first ejection test, reduced by the number of abnormal nozzles indicated by the result of the first ejection test, to the number of abnormal nozzles indicated by the result of the first ejection test, is greater than or equal to a first value.

6. The liquid ejection device described in claim 1, characterized in that the first condition is a condition in which the number of abnormal nozzles indicated by the results of the first ejection test is a number within a first range, and the number of abnormal nozzles indicated by the results of the second ejection test is a number within a second range that is smaller than the first range.

7. the first operation includes a first post-inspection driving operation, The liquid ejection device according to claim 1, characterized in that the second operation includes a second post-inspection driving operation in which the driving conditions of the driving element of at least one of the multiple types of driving operations are different from those of the first post-inspection driving operation.

8. The control unit is performing a post-first-inspection driving operation after performing the first ejection inspection; performing the second ejection inspection after the driving operation after the first inspection; If the first condition is not satisfied, the second operation not including the post-inspection driving operation is performed after the second ejection inspection; performing the first operation including a post-first-test drive operation after the second discharge test when the first condition is satisfied and a second condition, which is different from the first condition and relates to a relationship between a result of the first discharge test and a result of the second discharge test, is satisfied; The liquid ejection device described in claim 1, characterized in that if the first condition is satisfied but the second condition is not satisfied, after the second ejection inspection, the first operation is performed, which includes a second post-inspection driving operation in which the driving conditions of the driving element of at least one of the multiple types of driving operations are different from those of the first post-inspection driving operation.

9. the first condition is a condition that a number of the abnormal nozzles indicated by the result of the second ejection test is reduced from the number of the abnormal nozzles indicated by the result of the first ejection test by a first number or more; 9. The liquid ejection device according to claim 8, wherein the second condition is that the number of the reduced droplets is equal to or greater than a second number that is greater than the first number.

10. the first condition is a condition that a ratio of a decrease in the number of the abnormal nozzles indicated by the result of the second ejection test from the number of the abnormal nozzles indicated by the result of the first ejection test to the number of the abnormal nozzles indicated by the result of the first ejection test is equal to or greater than a first value; 9. The liquid ejection apparatus according to claim 8, wherein the second condition is that the ratio is equal to or greater than a second value that is greater than the first value.

11. The first condition is: (A) a condition that the number of the abnormal nozzles indicated by the result of the first ejection test is a number within a first range, and the number of the abnormal nozzles indicated by the result of the second ejection test is a number within a second range that is smaller than the first range; (B) the number of abnormal nozzles indicated by the result of the first discharge test and the number of abnormal nozzles indicated by the result of the second discharge test are both numbers within a first range, and the number of abnormal nozzles indicated by the result of the second discharge test is reduced from the number of abnormal nozzles indicated by the result of the first discharge test by a third number or more determined by the first range, 9. The liquid ejection apparatus according to claim 8, wherein the second condition is the condition (A).

12. a purge unit that performs purging to discharge liquid from the plurality of nozzles; A storage unit, The control unit stores information about the abnormal nozzle in the last ejection test in the storage unit, A liquid ejection device as described in claim 6 or 11, characterized in that the settings regarding the purging are different when the information indicates that the number of the abnormal nozzles is within the first range and when the information indicates that the number of the abnormal nozzles is within the second range.

13. The control unit is when the number of the abnormal nozzles indicated by the result of the first ejection test is equal to or greater than a fourth number and less than a fifth number, performing the post-inspection driving operation after the first ejection test; A liquid ejection device as described in claim 1, characterized in that if the number of abnormal nozzles indicated by the results of the first ejection test is less than the fourth number or is equal to or greater than the fifth number, the post-inspection driving operation is not performed after the first ejection test.

14. a purge unit that performs purging to discharge liquid from the plurality of nozzles, The control unit is The liquid ejection device according to claim 13 , wherein if the number of the abnormal nozzles indicated by the result of the first ejection inspection is equal to or greater than the fifth number, the purge section is caused to perform the purge after the first ejection inspection.

15. The control unit is when the number of the abnormal nozzles indicated by the result of the first ejection test is equal to or greater than the fourth number and is less than a sixth number between the fourth number and the fifth number, performing a post-first-test driving operation after the first ejection test; The liquid ejection device described in claim 13, characterized in that if the number of abnormal nozzles indicated by the results of the first ejection test is equal to or greater than the sixth number and less than the fifth number, after the first ejection test, a second post-inspection driving operation is performed in which the driving conditions of the driving elements in at least one of the multiple types of driving operations are different from those of the first post-inspection driving operation so that the ejection energy applied to the liquid in the nozzles is greater than that of the first post-inspection driving operation.

16. The control unit is When the number of the abnormal nozzles indicated by the result of the first ejection test is less than a fourth number, performing the post-inspection driving operation after the first ejection inspection; performing the second ejection inspection after the post-inspection driving operation; 2. The liquid ejection device according to claim 1, wherein the post-inspection driving operation is not performed after the second ejection inspection, regardless of the result of the second ejection inspection.

17. A liquid ejection device as described in any one of claims 7, 8 and 15, characterized in that in the second post-inspection driving operation, the driving time of the driving element in at least one of the multiple types of driving operations is made longer than that in the first post-inspection driving operation.

18. A liquid ejection device as described in any one of claims 7, 8 and 15, characterized in that in the second post-inspection driving operation, the driving frequency of the driving element in at least one of the multiple types of driving operations is made higher than that in the first post-inspection driving operation.

19. A liquid ejection device as described in any one of claims 7, 8 and 15, characterized in that in the second post-inspection driving operation, the number of times the driving element is driven in at least one of the multiple types of driving operations is greater than the first post-inspection driving operation.

20. The driving element applies a larger ejection energy to the liquid in the nozzle when a higher driving voltage is applied to the driving element, A liquid ejection device as described in any one of claims 7, 8 and 15, characterized in that in the second post-inspection driving operation, a driving voltage applied to the driving element in at least one of the multiple types of driving operations is made higher than that in the first post-inspection driving operation.

21. the post-inspection driving operation is an operation of repeating the plurality of types of driving operations, 16. The liquid ejection device according to claim 7, wherein in the second post-inspection driving operation, the number of times the plurality of types of driving operations are repeated is greater than in the first post-inspection driving operation.

22. The plurality of types of driving operations include a first driving operation for driving the driving element so as to impart to the liquid in the nozzle an ejection energy smaller than an ejection energy required to eject the liquid from the nozzle; The liquid ejection device according to claim 1 , further comprising: a second driving operation for driving the driving element so as to impart to the liquid in the nozzle an ejection energy required for ejecting the liquid from the nozzle.

23. 23. The liquid ejection apparatus according to claim 22, wherein the plurality of types of driving operations include a third driving operation different from the first driving operation and the second driving operation.

24. a purge unit that performs purging to discharge liquid from the plurality of nozzles, The control unit is When a predetermined time arrives, the ejection inspection unit is caused to perform the first ejection inspection; performing the post-inspection driving operation after the first ejection inspection; After the post-inspection driving operation, the ejection inspection unit is caused to perform a second ejection inspection; When the first condition is satisfied, the first operation is performed after the second ejection inspection; If the first condition is not satisfied, the second operation is performed after the second ejection inspection. Thereafter, when an ejection instruction signal instructing the ejection of liquid onto the ejection receiving medium is received, When a third condition is satisfied as a result of the second ejection test, the purge unit performs the purge, and then the plurality of drive elements are driven to eject liquid from the plurality of nozzles toward an ejection receiving medium; The liquid ejection device according to claim 1, characterized in that if the third condition is not satisfied, the purge section is not caused to perform the purge, and instead the plurality of drive elements are driven to eject liquid from the plurality of nozzles toward the ejection medium.

25. a head having a plurality of nozzles and a plurality of drive elements that apply ejection energy to liquid in the plurality of nozzles; a discharge inspection unit that performs a discharge inspection to inspect whether the nozzle is an abnormal nozzle having an abnormality in discharging liquid; A control unit, The control unit is causing the discharge inspection unit to perform a first discharge inspection; After the first ejection inspection, a cleaning operation is performed to discharge liquid from the abnormal nozzle; After the cleaning operation, the ejection inspection unit is caused to perform a second ejection inspection. when a predetermined condition regarding a relationship between a result of the first ejection test and a result of the second ejection test is satisfied, a first operation including the cleaning operation is performed after the second ejection test; If the predetermined condition is not satisfied, a second operation different from the first operation is performed after the second ejection inspection.

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