Liquid discharge device

Abstract

To reduce the number of nozzles which are not subjected to a discharge inspection for checking whether or not abnormal liquid discharge occurs.SOLUTION: A liquid discharge device executes discharge inspection processing for performing a discharge inspection for checking whether or not a nozzle has normally discharged ink on the basis of change in voltages of an electrode at the time when discharging / driving for driving an inkjet head so that the nozzle discharges ink toward the electrode, for each of the plurality of nozzles of the inkjet head, in a state where a potential difference is caused between the inkjet head and the electrode. Even when AC leak in which currents flow in a short time occurs during the discharge inspection processing, the discharge inspection processing is continued. When DC leak in which currents flow in a long time occurs during the discharge inspection processing (S106:YES), the discharge inspection for the nozzles which are not yet subjected to the discharge inspection in the discharge inspection processing is stopped (S108).SELECTED DRAWING: Figure 8

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 a nozzle, Patent Document 1 describes a printer that performs recording by ejecting ink from a nozzle. In the printer described in Patent Document 1, a plurality of nozzles of an inkjet head are opposed to an electrode arranged in a cap, and the inkjet head is driven to eject ink from the nozzle toward the electrode for each of the plurality of nozzles, thereby determining whether or not a nozzle is abnormal. If a leak occurs between the inkjet head and the electrode while determining whether or not a nozzle is abnormal, the determination of whether or not a nozzle is abnormal is stopped. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-16023 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, as described in Patent Document 1, if a leak occurs between the inkjet head and the electrode and the determination as to whether or not a nozzle is abnormal is stopped, there is an issue that the number of nozzles that are not determined to be abnormal will increase. In response to this, the inventor of the present application realized that, depending on the situation when a leak occurs between the inkjet head and the electrode, there are cases where it is highly necessary or not to stop the determination as to whether or not a nozzle is abnormal when a leak occurs.

[0005] An object of the present invention is to provide a liquid ejection device that can minimize the number of nozzles that are not subjected to ejection inspection to determine whether or not there is an abnormality in the ejection of liquid. [Means for solving the problem]

[0006] A liquid ejection device according to the present invention includes a head having a plurality of nozzles, an electrode, and an inspection signal output unit that outputs an inspection signal corresponding to an electrical change in the electrode when the head is driven to eject liquid from the nozzles toward the electrode, a leak signal output unit that outputs a first leak signal when a first leak occurs in which a current of a first predetermined value or more flows between the head and the electrode, and outputs a second leak signal different from the first leak signal when a second leak occurs in which a current of a second predetermined value or more flows between the head and the electrode, and a control unit, The head is driven to eject liquid from each of a plurality of nozzles in turn toward the electrode, and an ejection inspection process is executed to inspect whether there is an abnormality in the ejection of liquid from the nozzle based on the inspection signal output from the inspection signal output unit. Even if the first leak signal is output from the leak signal output unit during the ejection inspection process, the ejection inspection process is continued, and when the second leak signal is output from the leak signal output unit during the ejection inspection process, the ejection inspection of the nozzles for which the ejection inspection has not yet been performed in the ejection inspection process is discontinued.

[0007] A liquid ejection device according to the present invention includes a head having a plurality of nozzles, an electrode, and an inspection signal output section that outputs an inspection signal corresponding to an electrical change in the electrode when the head is driven to eject liquid from the nozzles toward the electrode, a leak signal output section that outputs a leak signal corresponding to whether or not a leak has occurred in which a current of a predetermined value or more flows between the head and the electrode, and a control section, wherein the control section drives the head to eject liquid from the nozzle toward the electrode for each of the plurality of nozzles in turn, and determines whether or not the inspection signal is output from the inspection signal output section. based on the detected signal, an ejection inspection process is executed to inspect whether there is an abnormality in the ejection of liquid from the nozzle, and even if the leak signal is output from the leak signal output unit when the ejection inspection is being performed on a first nozzle of the plurality of nozzles during the ejection inspection process, the ejection inspection process is continued, and if the leak signal is output from the leak signal output unit when the ejection inspection is being performed on a second nozzle different from the first nozzle of the plurality of nozzles during the ejection inspection process, the ejection inspection of the nozzles for which the ejection inspection has not yet been performed in the ejection inspection process is discontinued. Effect of the Invention

[0008] According to the present invention, the discharge inspection process is stopped less frequently than if the discharge inspection process was always stopped when a leak occurred, and the number of nozzles not subjected to discharge inspection can be reduced as much as possible. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a printer according to an embodiment of the present invention; [Diagram 2] 4A to 4C are diagrams for explaining electrodes and the like arranged inside the cap. [Diagram 3] FIG. 2 is a block diagram showing the electrical configuration of the printer. [Figure 4] FIG. 2 is a block diagram showing a configuration of an inspection circuit. [Diagram 5]FIG. 1A is a diagram for explaining the test signal when ink is ejected from the nozzle by ejection driving, and FIG. 1B is a diagram for explaining the test signal when ink is not ejected from the nozzle by ejection driving. [Figure 6] FIG. 1A is a diagram for explaining a signal received by a latch circuit when no AC leakage occurs, FIG. 1B is a diagram for explaining a signal received by a latch circuit when an AC leakage occurs, and FIG. 1C is a diagram for explaining an AC leakage signal. [Figure 7] FIG. 13 is a diagram for explaining a DC leak signal. [Figure 8] 10 is a flowchart showing a process flow when an inspection instruction signal is received. [Figure 9] 13 is a flowchart showing the flow of processing performed when an inspection instruction signal is received after the number of times that AC leakage has occurred during discharge inspection processing has reached a predetermined number. [Figure 10] FIG. 11 is a flowchart showing the flow of processing when an inspection instruction signal is received in an example in which the discharge inspection process is stopped if an AC leak occurs during discharge inspection of any of a predetermined number of nozzles that are successively inspected. [Figure 11] 13 is a flowchart showing the flow of processing when an inspection instruction signal is received in an example in which the discharge inspection process is stopped if an AC leak occurs during the discharge inspection of the second nozzle. [Figure 12] 1A is a diagram for explaining a case where the second nozzle is the nozzle close to the lip, and FIG. 1B is a diagram for explaining a case where a nozzle that has had AC leakage many times during discharge inspection and a nozzle nearby the nozzle are used as the second nozzle. [Figure 13] 13 is a flowchart showing the flow of processing when an inspection instruction signal is received in an example in which the discharge inspection process is stopped if a leak occurs during the discharge inspection of the second nozzle. [Figure 14] 13 is a flowchart showing the flow of processing when an inspection instruction signal is received in an example in which the next ejection inspection process is not executed if the time that has elapsed since the previous ejection inspection process was stopped is short. [Figure 15] 13 is a flowchart showing a process flow when an inspection instruction signal is received in an example in which a leak ejection inspection process is executed before an ejection inspection process. [Figure 16] 13A is a flowchart showing the processing flow when an inspection instruction signal is received in an example in which the discharge inspection process is stopped if an AC leak occurs during discharge inspection for a nozzle that has experienced a small number of AC leaks during discharge inspection, and inkjet head replacement is prompted when the number of nozzles that have experienced AC leaks a predetermined number or more during the discharge inspection process increases, and 13B is a flowchart showing the processing flow for resetting the value of variable KbN in this example. [Figure 17] This is a flowchart showing the processing flow when an inspection instruction signal is received in an example in which, if a DC leak occurs during ejection inspection of a nozzle that has experienced a small number of DC leaks during ejection inspection, the ejection inspection process is stopped, and if a DC leak occurs during ejection inspection of a nozzle that has experienced a large number of DC leaks during ejection inspection, ejection inspection of the nozzle that has experienced a small number of DC leaks during ejection inspection is continued. [Figure 18] 13 is a flowchart showing the flow of processing when an inspection instruction signal is received in an example in which nozzles with a low number of occurrences of AC leaks during ejection inspection are set as targets for ejection inspection. [Figure 19] 13 is a flowchart showing the flow of processing when a print instruction signal is received in an example in which complementary printing is performed when the number of nozzles is greater than or equal to the number of occurrences of AC leaks during ejection inspection. [Figure 20] FIG. 10A is a diagram for explaining printing by non-complementary printing, and FIG. 10B is a diagram for explaining printing by complementary printing, which increases the number of printing passes that form one raster line. [Figure 21] FIG. 1A is a diagram for explaining complementary recording that increases the resolution, and FIG. 1B is a diagram for explaining complementary recording that increases the amount of ink ejected from nozzles adjacent to nozzles with ejection abnormalities and nozzles with leak abnormalities. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Preferred embodiments of the present invention will now be described.

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

[0012] The carriage 2 is supported by two guide rails 11, 12 extending in the scanning direction. The carriage 2 is connected to a carriage motor 36 shown in Fig. 3 via a belt (not shown) or the like. When the carriage motor 36 is driven, the carriage 2 moves in the scanning direction along the guide rails 11, 12. In the following description, the right and left sides of the scanning direction are defined as shown in Fig. 1.

[0013] The inkjet head 4 is mounted on the carriage 2. The inkjet head 4 ejects ink from a plurality of nozzles 10 formed on a nozzle surface 4a, which is the lower surface of the inkjet head 4. More specifically, the plurality of nozzles 10 are arranged in a transport direction perpendicular to the scanning direction to form a nozzle row 9, and four nozzle rows 9 are arranged in the scanning direction on the nozzle surface 4a. The plurality of nozzles 10 eject black, yellow, cyan, and magenta inks in the order of those constituting the nozzle row 9 on the right side of the scanning direction. In addition, a water-repellent film such as a polyimide film may be formed on the nozzle surface 4a. The inkjet head 4 is connected to four ink cartridges (not shown) via tubes (not shown). The four ink cartridges supply the above four colors of ink to the inkjet head 4.

[0014] 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 37 shown in FIG. 3 via gears (not shown) and the like. When the transport motor 37 is driven, the transport rollers 6 and 7 rotate and the recording paper S is transported in the transport direction.

[0015] The maintenance unit 8 includes a cap 21, a suction pump 22, and a waste liquid tank 23. The cap 21 is disposed to the right of the platen 5 in the scanning direction. The cap 21 has a lip portion 29. The lip portion 29 protrudes upward and extends around the entire circumference of the outer edge of the cap 21. In addition, a discharge port 28 for discharging ink is provided at the end of the portion of the cap 21 surrounded by the lip portion 29 on the downstream side in the transport 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 portion of the cap 21 surrounded by the lip portion 29.

[0016] The cap 21 can be raised and lowered by a cap lifting mechanism 38 shown in FIG. 3. When the cap 21 is raised by the cap lifting mechanism 38 in a state where the plurality of nozzles 10 and the cap 21 face each other by positioning the carriage 2 at the maintenance position, the lip portion 29 comes into close contact with the nozzle surface 4a, and the plurality of nozzles 10 are covered by the cap 21 in a capped state. When the cap 21 is lowered by the cap lifting mechanism 38, the plurality of nozzles 10 are in an uncapped state where they are not covered by the cap 21. Note that the cap 21 is not limited to a cap that covers the plurality of nozzles 10 by the lip portion 29 coming into close contact with the nozzle surface 4a. The cap 21 may cover the plurality of nozzles 10 by, for example, coming into close contact with a frame (not shown) or the like that is arranged around the nozzle surface 4a of the inkjet head 4.

[0017] The suction pump 22 is a tube pump or the like, and is connected to the exhaust port 28 of the cap 21 and the waste liquid tank 23. In the maintenance unit 8, when the suction pump 22 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 23.

[0018] For convenience, the cap 21 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 21 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, yellow, cyan, and magenta, separately, so that either the black ink or the color ink in the inkjet head 4 can be selectively discharged during suction purge. Alternatively, for example, the cap 21 may be provided for each nozzle row 9, and ink can be discharged from the nozzles 10 for each nozzle row 9 individually during suction purge.

[0019] Suction purging is performed, for example, when an abnormality in the ink ejection is detected from a predetermined number or more of nozzles 10 in an ejection inspection process described below. Suction purging is also performed, for example, when a paper jam occurs during recording on the recording paper S in the printer 1 and the jammed recording paper S is removed. Suction purging is also performed, for example, when a user performs an operation on the operation panel 39 to instruct a suction purging.

[0020] In addition, in the maintenance unit 8, when the suction pump 22 is driven in the uncapped state, the ink accumulated in the cap 21 can be discharged from the discharge port 28 by suction purging or the like, that is, so-called idle suction can be performed. The ink discharged from the cap 21 by idle suction is also stored in the waste liquid tank 23.

[0021] 2, an electrode 26 having a rectangular planar shape is disposed within the cap 21. The electrode 26 constitutes an inspection circuit 27 shown in FIGS. 3 and 4. The inspection circuit 27 is controlled by a control unit 30 shown in FIGS. 3 and 4. In this embodiment, in the above-mentioned capped state, while generating a potential difference between the inkjet head 4 and the electrode 26 as described below, the inkjet head 4 is driven to eject ink from the nozzle 10. Based on a change in voltage of the electrode 26, it is possible to perform an ejection inspection to determine whether or not there is an abnormality in the ejection of ink from the nozzle 10.

[0022] <Printer electrical configuration> Next, the electrical configuration of the printer 1 will be described. As shown in Fig. 3, the printer 1 includes a control unit 30. The control unit 30 includes a CPU 31, a ROM 32, a RAM 33, a memory 34, an ASIC 35, and the like. The control unit 30 controls the operations of a carriage motor 36, an inkjet head 4, a conveying motor 37, a cap lifting mechanism 38, a suction pump 22, an inspection circuit 27, and the like. The control unit 30 also receives signals from the inspection circuit 27.

[0023] The control unit 30 may be one in which only the CPU 31 performs various processes, one in which only the ASIC 35 performs various processes, or one in which the CPU 31 and the ASIC 35 work together to perform various processes. The control unit 30 may be one in which one CPU 31 performs processes independently, or one in which multiple CPUs 31 share the processes. The control unit 30 may be one in which one ASIC 35 performs processes independently, or one in which multiple ASICs 35 share the processes.

[0024] <Inspection circuit> Next, a description will be given of the inspection circuit 27. As shown in Fig. 4, the inspection circuit 27 includes the above-mentioned electrode 26, a voltage supply circuit 51, a high-pass filter 52, an amplifier circuit 53, a latch circuit 54, and a low-pass filter 55.

[0025] The voltage supply circuit 51 is controlled by the control unit 30 to apply a voltage to the electrode 26 , thereby generating a potential difference between the inkjet head 4 and the electrode 26 .

[0026] One end of the high-pass filter 52 is connected between the power supply circuit 51 and the electrode 26. The amplifier circuit 53 is connected to the other end of the high-pass filter 52. When a voltage fluctuation occurs in the electrode 26, which is located upstream of the high-pass filter 52 in the voltage supply, the DC component of the voltage is removed by the high-pass filter 52 downstream of the high-pass filter 52 in the voltage supply. The voltage that has passed through the high-pass filter 52 is amplified by the amplifier circuit 53 and output as an inspection signal. As a result, the inspection signal is a signal in which the high-frequency component of the voltage of the electrode 26 has been amplified.

[0027] Here, the voltage of the electrode 26 will be described when the inkjet head 4 is driven to eject ink from the nozzle 10 in the above-mentioned capped state and a potential difference is generated between the inkjet head 4 and the electrode 26 by applying a voltage to the electrode 26 by the voltage supply circuit 51. When ink is normally ejected from the nozzle 10 by the ejection drive, a small current flows between the inkjet head 4 and the electrode 26 via the ejected ink, and the voltage of the electrode 26 changes due to this current. The change in the voltage of the electrode 26 at this time is rapid. On the other hand, when the amount of ink from the nozzle 10 due to the ejection drive is less than normal, the change in the voltage of the electrode 26 is smaller than normal. Here, the fact that the amount of ink from the nozzle 10 due to the ejection drive is less than normal includes the fact that ink is not ejected. When ink is not ejected from the nozzle 10 by the ejection drive, the voltage of the electrode 26 hardly changes. For these reasons, the high-frequency component of the voltage of the electrode 26 differs depending on whether ink is normally ejected from the nozzle 10 by the ejection drive.

[0028] When ink is normally ejected from the nozzle 10 by the ejection drive, the voltage of the test signal output from the amplifier circuit 53 changes relative to V0, as shown in Fig. 5(a). V0 is, for example, a voltage close to the ground potential. However, the amount of change in the voltage of the electrode 26 when ink is ejected from the nozzle 10 by the ejection drive is smaller than the amount of change in the voltage of the electrode 26 when an AC leak occurs between the inkjet head 4 and the electrode 26, which will be described later. Therefore, in this embodiment, the signal output from the high-pass filter 52 is amplified by the amplifier circuit 53 and output as the test signal.

[0029] On the other hand, when the amount of ink ejected from the nozzle 10 due to the ejection drive is less than normal, as shown in Figure 5(b), the change in the voltage of the inspection signal output from the amplifier circuit 53 relative to V0 is smaller than when ink is ejected normally from the nozzle 10 due to the ejection drive.

[0030] In this way, the test signal is a signal that indicates whether or not there is an abnormality in the ink ejection from the nozzles 10 during ejection driving.

[0031] The latch circuit 54 is connected in parallel to the amplifier circuit 53 at the other end of the high-pass filter 52. The latch circuit 54 receives a signal obtained by removing the DC component, i.e., the high voltage component applied by the voltage supply circuit 51, from the voltage of the electrode 26 by the high-pass filter 52. The latch circuit 54 is configured to output a signal when a voltage equal to or higher than a predetermined voltage is input, and not to output a signal when a voltage lower than the predetermined voltage is input. Furthermore, once the latch circuit 54 outputs a signal, it maintains the output. The output of the latch circuit 54 continues until it receives a release signal from the control unit 30 instructing it to release the output.

[0032] Here, for example, a temporary discharge may occur in the gap between the ink in the cap 21 and the nozzle surface 4a, causing an AC leak in which a current of a first predetermined value or more flows between the inkjet head 4 and the electrode 26 for less than a predetermined time. The first predetermined value is greater than the current value of the current that flows between the inkjet head 4 and the electrode 26 via the ejected ink when ink is normally ejected from the nozzle 10 by the ejection drive. The AC leak is likely to occur, for example, when there is a lot of ink floating between the electrode 26 and the nozzle surface 4a, or when a liquid puddle or liquid column is formed by the ink in the cap 21 but the electrode 26 and the nozzle surface 4a are not completely connected via the ink. In this embodiment, the AC leak corresponds to the "first leak" of the present invention.

[0033] When an AC leak occurs, a temporary voltage change occurs in the electrode 26. Furthermore, when an AC leak occurs between the inkjet head 4 and the electrode 26, the temporary voltage change in the electrode 26 is sudden. Therefore, the high frequency components of the voltage of the electrode 26 differ depending on whether or not an AC leak occurs between the inkjet head 4 and the electrode 26. Furthermore, the amount of change in the voltage of the electrode 26 at this time is greater than the amount of change in the voltage of the electrode 26 when ink is ejected from the nozzle 10 by the ejection drive.

[0034] Therefore, when no AC leakage occurs between the inkjet head 4 and the electrode 26, as shown in Fig. 6(a), the voltage of the signal output from the high-pass filter 52 and received by the latch circuit 54 changes very little. As a result, the latch circuit 54 does not output a signal. On the other hand, when AC leakage occurs between the inkjet head 4 and the electrode 26, as shown in Fig. 6(b), the voltage of the signal received by the latch circuit 54 changes temporarily. However, this voltage change lasts for a short period of time.

[0035] When a voltage change occurs in the signal received by the latch circuit 54 due to the occurrence of AC leakage between the inkjet head 4 and the electrode 26, the latch circuit 54 outputs a signal and maintains that state. As a result, the AC leakage signal output from the latch circuit 54 is a signal whose voltage is V0 when no AC leakage occurs between the inkjet head 4 and the electrode 26, as shown in FIG. 6(c), and whose voltage becomes V2a (>V0) when AC leakage occurs between the inkjet head 4 and the electrode 26, and the output of that signal is maintained. That is, the AC leakage signal when AC leakage occurs is a signal corresponding to a large voltage change in a short period of time at the electrode 26, that is, a signal indicating a voltage change due to leakage caused by discharge. Discharge means that a current flows for only a very short period of time that is less than a predetermined time.

[0036] 6(b) and (c) show a case where AC leakage occurs between the inkjet head 4 and the electrode 26 at time T1. Furthermore, if AC leakage continues to occur between the inkjet head 4 and the electrode 26, the signal output from the latch circuit 54 will continue to have a voltage state of V2a. When the control unit 30 determines that it is not necessary to maintain the output from the latch circuit 54, it outputs a release signal, and the latch circuit 54 receives the release signal from the control unit 30. Upon receiving the release signal, the latch circuit 54 stops outputting the latch signal. Note that FIG. 6(c) shows a case where the latch circuit 54 receives the release signal at time T2, which is later than time T1.

[0037] In this way, the AC leak signal output from the latch circuit 54 is a signal that indicates whether or not an AC leak has occurred between the inkjet head 4 and the electrode 26. The AC leak signal when an AC leak has occurred between the inkjet head 4 and the electrode 26 corresponds to the "first leak signal" of the present invention.

[0038] One end of low-pass filter 55 is connected between voltage supply circuit 51 and electrode 26. Low-pass filter 55 outputs, from the other end, a signal from which high-frequency components have been removed in response to fluctuations in the voltage of electrode 26, as a DC leak signal. In other words, the DC leak signal is a signal that is mainly the direct current component of the voltage of electrode 26.

[0039] Here, for example, when the inkjet head 4 and the electrode 26 are connected via the ink in the cap 21, a DC leak may occur in which a current of a second predetermined value or more flows between the inkjet head 4 and the electrode 26 for a predetermined time or more. Here, the second predetermined value is greater than the current value of a current that flows between the inkjet head 4 and the electrode 26 via the ejected ink when ink is normally ejected from the nozzle 10 by the ejection drive. In addition, the second predetermined value may be the same value as the above-mentioned first predetermined value, or may be a value different from the first predetermined value. DC leaks are likely to occur, for example, when the electrode 26 and the nozzle surface 4a are completely connected by a liquid puddle or liquid column formed by the ink in the cap 21. In this embodiment, the DC leak corresponds to the "second leak" of the present invention.

[0040] When a DC leak occurs between the inkjet head 4 and the electrode 26, a current continues to flow between the inkjet head 4 and the electrode 26, causing the magnitude of the voltage at the electrode 26 to decrease.

[0041] Therefore, as shown in FIG. 7, when there is no DC leak between the inkjet head 4 and the electrode 26, the magnitude |V3| of the voltage V3 of the DC leak signal output from the low-pass filter 55 is about the voltage V3a (V3a>0). When a DC leak occurs between the inkjet head 4 and the electrode 26, the magnitude |V3| of the voltage V3 of the DC leak signal output from the low-pass filter 55 becomes smaller than the voltage V3b (<V3a). That is, the DC leak signal when a DC leak occurs is a signal corresponding to a large voltage change over a long time at the electrode 26, that is, a signal indicating a voltage change corresponding to a leak due to a short circuit. A short circuit means that current flows for a long time of a predetermined time or more. Note that FIG. 7 shows a case where no DC leak occurs between the inkjet head 4 and the electrode 26 until time T3, and a DC leak occurs between the inkjet head 4 and the electrode 26 from time T3.

[0042] As described above, the DC leak signal is a signal indicating whether or not a DC leak has occurred between the inkjet head 4 and the electrode 26. The DC leak signal when a DC leak occurs between the inkjet head 4 and the electrode 26 corresponds to the "second leak signal" of the present invention.

[0043] In this embodiment, among the inspection circuits 27, the portion including the electrode 26, the voltage supply circuit 51, the high-pass filter 52, and the amplifier circuit 53 corresponds to the "inspection signal output unit" of the present invention. Also, in this embodiment, among the inspection circuits 27, the portion including the electrode 26, the voltage supply circuit 51, the high-pass filter 52, the latch circuit 54, and the low-pass filter 55 corresponds to the "leak signal output unit" of the present invention.

[0044] <Processing at the time of receiving a recording instruction signal> Next, the flow of processing of the control unit 30 when receiving a recording instruction signal for instructing recording on the recording paper S will be described. Note that the recording instruction signal of this embodiment corresponds to the "discharge instruction signal" of the present invention.

[0045] When a recording instruction signal is received, the control unit 30 controls the carriage motor 36 to move the carriage 2 in the scanning direction, while repeatedly performing a recording pass in which the inkjet head 4 ejects ink from the multiple nozzles 10 toward the recording paper S, and a transport operation in which the transport motor 37 causes the transport rollers 6, 7 to transport the recording paper S, thereby performing recording on the recording paper S.

[0046] <Processing when receiving an inspection command signal> Next, a description will be given of the flow of processing by the control unit 30 when an inspection instruction signal is received instructing to perform a discharge inspection of the nozzle 10. For example, when a user operates an operation unit (not shown) of the printer 1 or a PC connected to the printer to instruct to perform a discharge inspection of the nozzle 10, an inspection instruction signal is sent from the operation unit of the printer 1, the PC, etc., and the control unit 30 receives the inspection instruction signal. Then, when the control unit 30 receives the inspection instruction signal, it performs processing according to the flowchart of FIG.

[0047] 8 in detail, the control unit 30 starts the discharge inspection process (S101). In the discharge inspection process, the control unit 30 controls the carriage motor 36, the cap lifting mechanism 38, etc. to set the above-mentioned cap state, and then controls the voltage supply circuit 51 of the inspection circuit 27 to cause the inkjet head 4 to sequentially perform discharge drive for each of the multiple nozzles 10 while applying a predetermined voltage to the electrodes 26. Then, while the control unit 30 is causing each nozzle 10 to be driven to discharge, it acquires a test signal output from the amplifier circuit 53, and performs a discharge inspection for that nozzle 10 based on the acquired test signal.

[0048] After starting the discharge inspection process in S101, the control unit 30 determines whether or not a DC leak has occurred based on the DC leak signal output from the low-pass filter 55 (S102). If a DC leak has occurred (S102: YES), the control unit 30 stops the discharge inspection process (S104) and the process ends. Here, stopping the discharge inspection process means stopping the discharge inspection of nozzles 10 that have not yet been inspected for discharge. The same applies to the following explanation.

[0049] If no DC leak has occurred (S102: NO), the control unit 30 then determines whether the discharge inspection process has been completed (S103). If the discharge inspection process has not been completed (S103: NO), the process returns to S102. When the discharge inspection process is completed (S103: YES), the process ends. In this embodiment, when an inspection instruction signal is received, the control unit 30 performs the process according to the flowchart of FIG. 8, so that the discharge inspection process continues even if an AC leak occurs during the discharge inspection process. In this embodiment, the control unit 30 performs the process according to the flowchart of FIG. 8 when an inspection instruction signal is received, so that the discharge inspection process continues even if an AC leak occurs during the discharge inspection process. In this embodiment, the control unit 30 performs the process according to the flowchart of FIG. 8 when an inspection instruction signal is received. In this embodiment, the control unit 30 performs the process according to the flowchart of FIG. 8 ...

[0050] <Effects> In this embodiment, as described above, when ink is normally ejected from the nozzle 10 of the inkjet head 4 by the ejection drive in the ejection inspection process, a small current flows between the inkjet head 4 and the electrode 26, causing a change in the voltage of the electrode 26. Then, an ejection inspection is performed to determine whether ink is normally ejected from the nozzle 10 based on the change in the voltage of the electrode 26 when the ejection drive is performed. At this time, a leak in which a current larger than that when the ejection drive is performed flows between the inkjet head 4 and the electrode 26 may occur due to ink floating between the electrode 26 and the nozzle surface 4a, or a liquid puddle or liquid column formed by the ink in the cap 21.

[0051] When a leak occurs, a current may flow through the ink in the nozzle 10. In particular, when a water-repellent film is formed on the nozzle surface 4a, the water-repellent film generally has high insulating properties, so that a current is likely to flow through the ink in the nozzle 10. The nozzle 10 is damaged according to the current that flows. More specifically, when a large current flows, the components in the ink precipitate, and the precipitated components may remain attached to the wall of the nozzle 10 and block the nozzle flow path, which causes abnormalities in the ink ejection. In addition, the degree of precipitation of the ink components varies depending on the magnitude and length of the current that flows through the ink in the nozzle 10. In addition, when a leak occurs during the ejection inspection process, the longer the time that the current flows due to the leak, the greater the need to stop the ejection inspection process.

[0052] Furthermore, in an AC leak, a current equal to or greater than a first predetermined value flows between the electrode 26 and the nozzle surface 4a for only a very short period of time that is less than a predetermined time. On the other hand, in a DC leak, a current equal to or greater than a second predetermined value flows between the electrode 26 and the nozzle surface 4a for a long period of time that is greater than or equal to a predetermined time. Therefore, when a DC leak occurs during the discharge inspection process, in which a current equal to or greater than the second predetermined value flows for a predetermined period of time or more, there is a greater need to stop the discharge inspection process than when an AC leak occurs during the discharge inspection process, in which a current equal to or greater than the first predetermined value flows for less than a predetermined period of time.

[0053] Therefore, in this embodiment, the discharge inspection process is continued even if an AC leak occurs during the discharge inspection process, and the discharge inspection process is stopped when a DC leak occurs during the discharge inspection process. This reduces the frequency of stopping the discharge inspection process compared to when the discharge inspection process is stopped when both an AC leak and a DC leak occur during the discharge inspection process, and makes it possible to minimize the number of nozzles 10 for which discharge inspection is not performed. Even if the discharge inspection process is continued when an AC leak occurs during the discharge inspection process, problems such as an increase in the degree of precipitation of components in the ink are unlikely to occur.

[0054] <Modification> Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and various modifications are possible within the scope of the claims.

[0055] In the above embodiment, when an AC leak occurs during the discharge inspection process, the discharge inspection process is always stopped, but the present invention is not limited to this.

[0056] In the first modification, when an inspection instruction signal is received, the control unit 30 performs processing in accordance with the flowchart of FIG.

[0057] 9 in detail, the control unit 30 first resets the value of a variable Ka to 0 (S201). The variable Ka corresponds to the number of times that an AC leak occurs during the discharge inspection process described below. Next, the control unit 30 starts the discharge inspection process in the same manner as S101 in the above-described embodiment (S202).

[0058] After starting the discharge inspection process in S202, the control unit 30 determines whether or not an AC leak is occurring based on the AC leak signal output from the latch circuit 54 (S203). If an AC leak is not occurring (S203: NO), the process proceeds to S206.

[0059] If an AC leak occurs (S203: YES), the control unit 30 increments the value of the variable Ka by 1 (S204) and determines whether the value of the variable Ka is equal to or greater than a predetermined value Ka1 (S205). If the value of the variable Ka is less than the predetermined value Ka1 (S205: NO), the process proceeds to S206. If the value of the variable Ka is equal to or greater than the predetermined value Ka1 (S205: YES), the control unit 30 stops the discharge inspection process (S208), and the process ends.

[0060] In S206, the control unit 30 determines whether or not a DC leak has occurred, similarly to S102 in the above-described embodiment (S206). If a DC leak has occurred (S206: YES), the control unit 30 stops the discharge inspection process (S208), and the process ends.

[0061] If no DC leak has occurred (S206: NO), the control unit 30 then determines whether the discharge inspection process has been completed (S207). If the discharge inspection process has not been completed (S207: NO), the process returns to S203. When the discharge inspection process has been completed (S207: YES), the process ends.

[0062] Although there is less need to stop the discharge inspection process for an AC leak compared to a DC leak, it is preferable to stop the discharge inspection process if an AC leak occurs many times during the discharge inspection process. Therefore, in Modification 1, even if an AC leak occurs during the discharge inspection process, the discharge inspection process is stopped when the variable Ka is equal to or greater than a predetermined value Ka1, that is, when the number of AC leaks that have occurred during the discharge inspection process reaches Ka1.

[0063] Here, in Modification 1, each time a discharge inspection is performed on one nozzle 10, a determination is made as to whether or not an AC leak has occurred in S203, and a determination is made as to whether or not a DC leak has occurred in S206, and if an AC leak occurs during a discharge inspection of one nozzle 10, the value of variable Ka is incremented by 1. Therefore, during a discharge inspection of one nozzle 10, variable Ka is not incremented by 2 or more, in other words, AC leaks are not counted multiple times.

[0064] In the second modification, when an inspection instruction signal is received, the control unit 30 performs processing according to the flowchart of FIG.

[0065] 10 in detail, the control unit 30 starts the discharge inspection process in the same manner as S101 in the above-described embodiment (S301). After starting the discharge inspection process in S301, the control unit 30 judges whether or not an AC leak has occurred during the discharge inspection of any of the K2 nozzles 10 for which discharge inspection is performed consecutively (S302). If an AC leak has occurred during the discharge inspection of any of the K2 nozzles 10 for which discharge inspection is performed consecutively (S302: YES), the control unit 30 stops the discharge inspection process (S305), and the process ends.

[0066] If no AC leak has occurred (S302: NO), the control unit 30 determines whether or not a DC leak has occurred (S303) in the same manner as in S206 of the above embodiment. If a DC leak has occurred (S303: YES), the control unit 30 stops the discharge inspection process (S305), and the process ends.

[0067] If no DC leak has occurred (S303: NO), the control unit 30 then determines whether the discharge inspection process has been completed (S304). If the discharge inspection process has not been completed (S304: NO), the process returns to S302. When the discharge inspection process has been completed (S304: YES), the process ends.

[0068] When an AC leak occurs, it is less necessary to stop the discharge inspection process than when a DC leak occurs. However, if an AC leak occurs during any of the discharge inspections of a large number of nozzles 10 that are continuously inspected during the discharge inspection process, it is preferable to stop the discharge inspection process. Therefore, in the second modified example, the discharge inspection process is stopped when an AC leak occurs during any of the discharge inspections of K2 nozzles 10 that are continuously inspected. This is because it has been found through experiments and the like that, while DC leaks are likely to occur due to the surrounding environment, whereas AC leaks are likely to occur due to the nozzle 10 itself, when AC leaks occur continuously, it is highly likely that the AC leaks are caused by the surrounding environment.

[0069] In the third modification, when an inspection instruction signal is received, the control unit 30 performs processing according to the flowchart of FIG.

[0070] 11 in detail, the control unit 30 starts a discharge inspection process similar to S101 in the above-described embodiment (S401). After starting the discharge inspection process in S401, the control unit 30 determines whether or not an AC leak has occurred (S402). If an AC leak has occurred (S402: YES), the control unit 30 determines whether or not the AC leak occurred during a discharge inspection of the second nozzle, which will be described later (S403).

[0071] Here, in the third modification, the multiple nozzles 10 of the inkjet head 4 are grouped into multiple first nozzles and multiple second nozzles. Specifically, as shown in Fig. 12(a), among the multiple nozzles 10 of the inkjet head 4, the nozzles 10a located in the central region E1 of the nozzle surface 4a are defined as the first nozzles. Among the multiple nozzles 10 of the inkjet head 4, the nozzles 10b located in the region E2 surrounding the central region E1 of the nozzle surface 4a are defined as the second nozzles. As a result, in the capped state, the second nozzles are closer to the lip portion 29 of the cap 21 than the first nozzles.

[0072] If the AC leak occurred during the discharge inspection of the second nozzle (S403: YES), the control unit 30 stops the discharge inspection process (S406), and the process ends.

[0073] If an AC leak occurs during the ejection inspection of the first nozzle (S403: NO), the control unit 30 determines whether or not a DC leak has occurred (S404) in the same manner as S206 in the above embodiment. If a DC leak has occurred (S404: YES), the control unit 30 stops the ejection inspection process (S406) and the process ends.

[0074] If no DC leak has occurred (S404: NO), the control unit 30 then determines whether the discharge inspection process has been completed (S405). If the discharge inspection process has not been completed (S405: NO), the process returns to S402. When the discharge inspection process has been completed (S405: YES), the process ends.

[0075] In the fourth modification, similarly to the third modification, when an inspection instruction signal is received, the control unit 30 performs processing according to the flowchart of Fig. 11. However, in the fourth modification, the first nozzle and the second nozzle are different from those in the third modification.

[0076] More specifically, in the fourth modification, information on the number of times that AC leakage has occurred during discharge inspection is stored in the memory 34 for each of the nozzles 10 of the inkjet head 4. In the fourth modification, as shown in FIG. 12(b), among the nozzles 10 of the inkjet head 4, the nozzle 10c in which the number of times that AC leakage has occurred during discharge inspection is a predetermined number or more, and the nozzle 10d in which the distance from the nozzle 10c is within a range of R or less are set as second nozzles. That is, the nozzles 10c and 10d located within a circle F of radius R centered on the nozzle 10c are set as second nozzles. In the fourth modification, among the nozzles 10 of the inkjet head 4, the nozzle 10e other than the nozzles 10c and 10d are set as first nozzles. That is, the nozzle 10 located outside the circle F is set as the first nozzle. Note that the nozzle 10 only partially located within the circle F may be set as either the first nozzle or the second nozzle.

[0077] The necessity to stop the discharge inspection process may differ depending on which nozzle 10 an AC leak occurred during the discharge inspection. For example, in the case of the modified example 3, the nozzle 10b close to the lip portion 29 is more likely to continue to have a current flow when an AC leak occurs through ink attached to the lip portion 29 during the discharge inspection than the nozzle 10a far from the lip portion 29, and therefore it is more necessary to stop the discharge inspection process when an AC leak occurs. Also, for example, in the case of the modified example 4, the nozzle 10c with a high number of occurrences of AC leaks and the nozzle 10d close to the nozzle 10c are more likely to have AC leaks than the other nozzles 10e, and therefore it is more necessary to stop the discharge inspection process when an AC leak occurs.

[0078] Therefore, in Modifications 3 and 4, if an AC leak occurs during the discharge inspection of the first nozzle, the discharge inspection process is continued, and if an AC leak occurs during the discharge inspection of the second nozzle, the discharge inspection process is stopped. This makes it possible to stop the discharge inspection process if there is a high need to stop the discharge inspection process even if an AC leak occurs during the discharge inspection process.

[0079] Furthermore, when the control unit 30 performs processing according to the flowchart of Figure 11 upon receiving an inspection instruction signal, which of the multiple nozzles 10 of the inkjet head 4 is set as the first nozzle and which nozzle 10 is set as the second nozzle may be different from that in variants 3 and 4.

[0080] In the third and fourth modified examples, if a DC leak occurs during a discharge inspection, the discharge inspection is stopped no matter which nozzle 10 the DC leak occurs in during the discharge inspection, but the present invention is not limited to this.

[0081] In the fifth modification, the first nozzle and the second nozzle are set in the same manner as in the third or fourth modification. In the fifth modification, when an inspection instruction signal is received, the control unit 30 performs processing according to the flowchart of FIG.

[0082] 13 in detail, the control unit 30 starts the discharge inspection process in the same manner as S202 in the above-described embodiment (S501). After starting the discharge inspection process in S501, the control unit 30 judges whether a leak has occurred (S502). Here, the occurrence of a leak in S502 means that either a DC leak or an AC leak has occurred. If no leak has occurred (S502: NO), the process proceeds to S504.

[0083] If a leak occurs (S502: YES), it is determined whether or not a leak occurred during the discharge test for the second nozzle (S503). If a leak occurs during the discharge test for the second nozzle (S503: YES), the control unit 30 stops the discharge test process (S506) and the process ends. If a leak occurs during the discharge test for the first nozzle (S503: NO), the process proceeds to S504.

[0084] In S504, the control unit 30 determines whether the discharge inspection process is completed. If the discharge inspection process is not completed (S504: NO), the process returns to S502. If the discharge inspection process is completed (S504: YES), the process ends.

[0085] The need to stop the discharge inspection process may differ depending on which nozzle 10 a leak occurred during the discharge inspection. Modification 5 continues the discharge inspection process regardless of whether an AC leak or a DC leak occurs during the discharge inspection of the first nozzle, and stops the discharge inspection process regardless of whether an AC leak or a DC leak occurs during the discharge inspection of the second nozzle. This reduces the frequency with which the discharge inspection process is stopped compared to when the discharge inspection process is always stopped when a leak occurs, and makes it possible to minimize the number of nozzles for which discharge inspection is not performed.

[0086] Furthermore, the closer the nozzle 10 is to the lip portion 29, the more likely it is that a current will continue to flow when leakage occurs through ink adhering to the lip portion 29 during discharge testing, and the greater the need to stop the discharge testing process when leakage occurs. Therefore, in Modification 5, as shown in Figure 12(a), by setting the nozzle 10 closer to the lip portion 29 as the second nozzle and the nozzle 10 farther from the lip portion 29 as the first nozzle, problems such as an increase in the degree of precipitation of components in the ink are less likely to occur, even if the discharge testing process is continued when leakage occurs during discharge testing of the first nozzle.

[0087] Also, the nozzle 10c with a high number of occurrences of AC leakage and the nozzle 10d close to the nozzle 10c are more likely to cause AC leakage than the other nozzles 10. Therefore, in the fifth modified example, as shown in FIG. 12(b), the nozzle 10c with a high number of occurrences of leakage and the nozzle 10d close to the nozzle 10c are set as the second nozzle, and the other nozzle 10e is set as the first nozzle. This allows the first nozzle and the second nozzle to be set appropriately according to the likelihood of leakage. As a result, even if the ejection inspection process is continued when a leak occurs during the ejection inspection of the first nozzle, problems such as the degree of precipitation of components in the ink becoming large are unlikely to occur.

[0088] Moreover, in the fifth modification, which nozzles 10 among the multiple nozzles 10 of the inkjet head 4 are set as the first nozzles and which nozzles 10 are set as the second nozzles may be different from those in the third and fourth modifications.

[0089] In the sixth modification, when an inspection instruction signal is received, the control unit 30 performs processing according to the flowchart of FIG.

[0090] To explain the flow chart of FIG. 14 in detail, the control unit 30 judges whether the previous discharge inspection process was stopped (S601). If the previous discharge inspection process was stopped (S601: YES), the control unit 30 judges whether the elapsed time Ta since the previous discharge inspection process was stopped is equal to or longer than the first time Ta1 (S602). If the elapsed time Ta is less than the first time Ta1 (S602: NO), the control unit 30 outputs an error signal to the operation panel 39, thereby causing the operation panel 39 to display an error screen for notifying the user that the discharge inspection process cannot be performed because the elapsed time since the previous discharge inspection process was stopped is short (S603), and the process ends. In this case, the discharge inspection process is not performed.

[0091] Furthermore, if the previous discharge inspection process was not stopped (S601: NO), if the previous discharge inspection process was stopped (S601: YES), and if the elapsed time Ta since the previous discharge inspection process was stopped is equal to or longer than the first time Ta1 (S602: YES), the control unit 30 executes the processes of S604 to S607 similar to S101 to S104 in the above-described embodiment. Note that instead of the processes of S604 to S607, any of the processes of S201 to S208 in Modification 1, the processes of S301 to S305 in Modification 2, and the processes of S401 to S406 in Modifications 3 and 4 may be executed.

[0092] If the discharge inspection process is performed again immediately after the discharge inspection process is stopped, there is a high possibility that the discharge inspection process will also be stopped again. Therefore, in the sixth modification, the discharge inspection process is not performed even if an inspection instruction signal is received before the first time Ta1 has elapsed since the discharge inspection process was stopped, and the discharge inspection process is performed when an inspection instruction signal is received after the first time Ta1 or more has elapsed since the discharge inspection process was stopped. This makes it possible to prevent the discharge inspection process from being performed again when there is a high possibility that the discharge inspection process will be stopped.

[0093] In the seventh modification, when an inspection instruction signal is received, the control unit 30 performs processing according to the flowchart of FIG.

[0094] 15 in detail, the control unit 30 executes a leak inspection process (S701). In the leak inspection process, the control unit 30 controls the carriage motor 36, the cap lifting mechanism 38, etc. to set the above-mentioned cap state, and then controls the voltage supply circuit 51 of the inspection circuit 27 to apply a predetermined voltage to the electrode 26. Then, based on the DC leak signal output from the low-pass filter 55, it detects whether or not a DC leak has occurred, and based on the AC leak signal output from the latch circuit 54, it detects whether or not an AC leak has occurred. Unlike the ejection inspection process, in the leak inspection process, the inkjet head 4 is not driven to eject in the leak inspection process.

[0095] Next, the control unit 30 determines whether the elapsed time Tb from the previous suction purge is equal to or greater than the second time Tb1 (S702).

[0096] If the elapsed time Tb is less than the second time Tb1 (S702: NO), the control unit 30 judges whether or not an AC leak has occurred as a result of the leak inspection process, and whether or not a DC leak has occurred as a result of the leak inspection process (S703, S704). If either an AC leak or a DC leak has occurred as a result of the leak inspection process (S703: YES or S704: YES), the control unit 30 outputs an error signal to the operation panel 39, thereby causing the operation panel 39 to display an error screen to inform the user that a leak has occurred because the time elapsed since the previous suction purge is short, and the discharge inspection process cannot be performed (S705), and the process ends. In this case, the discharge inspection process is not performed.

[0097] If the leak check process finds that neither AC leak nor DC leak has occurred (S703: NO, S704: NO), the control unit 30 executes the processes of S706 to S709 similar to S101 to S104 in the above embodiment.

[0098] If the elapsed time Tb is equal to or greater than the second time Tb1 (S702: YES), the control unit 30 determines whether or not a DC leak has occurred as a result of the leak inspection process (S704). If a DC leak has occurred (S704: YES), the control unit 30 outputs an error signal to the operation panel 39, causing the operation panel 39 to display the error screen (S705), and the process ends. In this case, the discharge inspection process is not executed.

[0099] If the leak check process finds that no DC leak has occurred (S704: NO), the control unit 30 executes the processes of S706 to S709 similar to S101 to S104 in the above embodiment.

[0100] In addition, in the seventh modification, instead of the processes of S706 to S709, any one of processes similar to S201 to S208 in the first modification, processes similar to S301 to S305 in the second modification, and processes similar to S401 to S406 in the third and fourth modifications may be executed.

[0101] Immediately after the suction purge, leakage is likely to occur through ink adhering to the inkjet head 4, the electrode 26, the cap 21, etc. Therefore, in the seventh modification, when an inspection command signal is received before the second time Tb1 has elapsed after the suction purge, the leakage inspection process is executed, and when either an AC leak or a DC leak occurs, the discharge inspection process is not executed. Also, when an inspection command signal is received after the second time Tb1 or more has elapsed after the suction purge, the leakage inspection process is executed, and even if an AC leak occurs, the discharge inspection process is executed, and when a DC leak occurs, the discharge inspection process is not executed. This makes it possible to prevent the discharge inspection process from being executed when there is a high possibility of leakage occurring during the discharge inspection process.

[0102] In the eighth modification, a variable Kb indicating the number of times that an AC leak occurs during a discharge inspection of each of the nozzles 10 of the inkjet head 4 is set. N The value of Kb is stored in the memory 34. In the eighth modification, the nozzles 10 of the inkjet head 4 are individually assigned nozzle numbers 1, 2, 3, . . . N In the above, N indicates the nozzle number. Also, the variable Kb N The value of Kb is reset to 0 when the printer 1 is first powered on. N The value corresponds to the "information on the number of occurrences of AC leaks" of the present invention.

[0103] In addition, in the eighth modification, when an inspection command signal is received, the control unit 30 performs processing according to the flowchart in FIG. 16(a). More specifically, the control unit 30 starts the discharge inspection process (S801), similar to S101 in the above embodiment. Next, the control unit 30 determines whether or not an AC leak has occurred (S802), similar to S203 in the above embodiment. If an AC leak has occurred (S802: YES), the control unit 30 sets the variable Kb N After increasing the value of this variable Kb by 1 (S803), N It is determined whether the value of is equal to or greater than a predetermined value Kb1 (S804).

[0104] Variable Kb N If the value of the variable Kb is less than the predetermined value Kb1 (S804: NO), the control unit 30 stops the discharge inspection process (S807), and the process ends. N If the value of is equal to or larger than the predetermined value Kb1 (S804: NO), the process proceeds to S805. If no AC leak has occurred (S802: NO), the process also proceeds to S805.

[0105] In S805, the control unit 30 determines whether or not a DC leak has occurred, similar to S102 in the above embodiment. If a DC leak has occurred (S805: YES), the discharge inspection process is stopped (S807), and the process ends. If a DC leak has not occurred (S805: NO), the control unit 30 determines whether or not the discharge inspection process has been completed (S806). If the discharge inspection process has not been completed (S806: NO), the process returns to S802.

[0106] When the ejection inspection process is completed (S806: YES), the control unit 30 selects the nozzles 10 of the inkjet head 4 as the nozzles having the variable Kb N It is determined whether the number G of nozzles 10 whose value is equal to or greater than the predetermined value Kb2 is equal to or greater than the predetermined number G1 (S808). Here, the predetermined value Kb2 may be the same value as the predetermined value Kb1, or may be a value different from the predetermined value Kb1. NIf the number G of nozzles 10 whose value is equal to or greater than the predetermined value Kb2 is less than the predetermined number G1 (S808: NO), the process ends. N If the number G of nozzles 10 whose value is equal to or greater than the predetermined value Kb2 is equal to or greater than the predetermined number G1 (S808: YES), the control unit 30 outputs a head replacement signal to the operation panel 39, thereby causing the operation panel 39 to display a screen prompting the user to replace the inkjet head 4 (S809), and the processing ends.

[0107] In the eighth modification, the control unit 30 performs processing according to the flowchart of Fig. 16(b) while power is being supplied to the printer 1. More specifically, the control unit 30 determines whether the inkjet head 4 has been replaced (S811).

[0108] For example, a head sensor is provided to detect that the inkjet head 4 is attached to the printer 1. Then, in S811, the control unit 30 determines that the inkjet head 4 has been replaced when the state switches from one in which the head sensor detects that the inkjet head 4 is attached to one in which the head sensor no longer detects that the inkjet head 4 is attached, and then switches back to one in which the head sensor detects that the inkjet head 4 is attached.

[0109] Alternatively, for example, when the user performs an operation on the operation panel 39 corresponding to replacement of the inkjet head 4, the operation panel 39 is configured to output a signal indicating that this operation has been performed. Then, in S811, when this signal is output from the operation panel 39, the control unit 30 determines that the inkjet head 4 has been replaced.

[0110] The control unit 30 waits without performing any process while the inkjet head 4 has not been replaced (S811: NO). When the inkjet head 4 has been replaced (S811: YES), the control unit 30 sets the variables Kb NThe value is reset to 0 (S812), and the process returns to S811.

[0111] If an AC leak occurs during a discharge inspection of a nozzle 10 where AC leaks have occurred many times, there is a high possibility that the cause of the AC leak is that nozzle 10 itself. Therefore, there is a low possibility that an AC leak will occur during a discharge inspection of other nozzles 10, and there is a low need to stop the discharge inspection process. On the other hand, if an AC leak occurs during a discharge inspection of a nozzle 10 where AC leaks have occurred few times, there is a high possibility that the cause of the AC leak is something other than that nozzle 10 itself. Therefore, there is a high possibility that an AC leak will occur during a discharge inspection of other nozzles 10, and there is a high need to stop the discharge inspection process.

[0112] Therefore, in the eighth modification, when an AC leak occurs during the discharge inspection of a certain nozzle 10 during the discharge inspection process, the variable Kb N If the value of Kb is equal to or greater than the predetermined value Kb1, that is, if the number of occurrences of AC leakage for the nozzle 10 is equal to or greater than Kb1, the discharge inspection process is continued. N is less than a predetermined value Kb1, i.e., if the number of occurrences of AC leakage for the nozzle 10 is less than Kb1, the discharge inspection process is stopped. This makes it possible to stop the discharge inspection process if there is a high need to stop the discharge inspection process even when an AC leakage occurs during the discharge inspection process. Note that in Modification 8, Kb1 corresponds to the "first number" of the present invention.

[0113] For example, leakage is likely to occur in nozzles 10 close to the scratches on the nozzle surface 4a when the nozzle surface 4a is scratched, or in nozzles 10 close to the peeled part of the water-repellent film formed on the nozzle surface 4a when the water-repellent film is peeled off. Such nozzles 10 are also likely to leak during discharge testing. In this way, when the nozzle 10 itself has a cause for leakage, it is problematic that the discharge testing of the nozzles 10 that are to be tested after the nozzle 10 is not performed. If the discharge testing process is stopped when leakage occurs during the discharge testing of such a nozzle 10, the discharge testing of the nozzles 10 that are less likely to leak that were to be tested after that will not be performed, and other abnormalities may occur in these nozzles 10. Since a nozzle 10 that has a high number of occurrences of AC leakage is likely to be a nozzle 10 that is prone to leakage as described above, if leakage occurs during the discharge testing of that nozzle 10, it may be better to continue the discharge testing process in order to protect the nozzles 10 of the entire inkjet head 4.

[0114] Also, if the number of occurrences of AC leakage from many nozzles 10 is high, there is a high possibility that the inkjet head 4 is broken, for example, when the recording paper S comes into contact with the nozzle surface 4a when a paper jam occurs, causing the water-repellent film formed on the nozzle surface 4a to peel off, or when there are many scratches in the area of ​​the nozzle surface 4a near the nozzles 10. Therefore, in the eighth modification, the variable Kb N When the number G of nozzles 10 for which the value of is equal to or greater than a predetermined value Kb2 reaches or exceeds a predetermined number G1, that is, when the number of occurrences of AC leaks for G1 or more nozzles 10 reaches or exceeds Kb2 times, a screen for urging the user to replace the inkjet head 4 is displayed on the operation panel 39. This makes it possible to urge the user to replace the inkjet head 4 when there is a high possibility that the inkjet head 4 is broken. In the eighth modification, Kb2 times corresponds to the "second number" of the present invention.

[0115] In the ninth modification, a variable Kc which is information on the number of times that a DC leak occurs during a discharge test for each of the nozzles 10 of the inkjet head 4 is set individually for each of the nozzles 10. N The value of the variable Kc is stored in the memory 34. N In the above, N indicates the nozzle number as described in the eighth modification. In addition, the variable Kc N The value of Kc is reset to 0, for example, when the printer 1 is first powered on. In this embodiment, the individual variables Kc N The value corresponds to the "information on the number of occurrences of DC leakage" of the present invention.

[0116] In addition, in the ninth modification, when an inspection command signal is received, the control unit 30 performs processing according to the flowchart of Fig. 17. More specifically, the control unit 30 starts the discharge inspection process (S901) in the same manner as S101 in the above-mentioned embodiment. After starting the discharge inspection process in S901, the control unit 30 determines whether or not a DC leak has occurred in the same manner as S102 in the above-mentioned embodiment (S902).

[0117] If a DC leak occurs (S902: YES), the control unit 30 sets the variable Kc N The value of the variable Kc for this nozzle 10 is increased by 1 (S903). N It is determined whether the value of is equal to or larger than a predetermined value Kc1 (S904).

[0118] Variable Kc N If the value of the variable Kc is less than the predetermined value Kc1 (S904: NO), the discharge inspection process is stopped (S907), and the process ends. N If the value of Kc1 is equal to or greater than the predetermined value Kc1 (S904: YES), the current variable Kc N Any nozzle 10 for which the value is less than a predetermined value Kc1 is set as a target for discharge inspection (S905), and the process proceeds to S906. If no DC leak has occurred (S902: NO), the process also proceeds to S906.

[0119] In S906, the control unit 30 determines whether the discharge inspection process is complete. If the control unit 30 has performed the process of S905, the control unit 30 determines in S906 that the discharge inspection process is complete if the discharge inspection of all nozzles 10 set as targets for discharge inspection in S905 has been completed. If the discharge inspection process is not complete (S906: NO), the process returns to S902. When the discharge inspection process is complete (S906: YES), the process ends.

[0120] The cause of the occurrence of a DC leak is likely to be the environment surrounding the nozzle 10. Therefore, when a DC leak occurs during a discharge inspection of a nozzle 10 where a DC leak occurs many times, it is likely that the environment surrounding the nozzle 10 where the DC leak occurs many times is an environment where a DC leak is likely to occur, but it is likely that the environment surrounding a nozzle 10 where a DC leak occurs few times is not an environment where a DC leak is likely to occur.

[0121] On the other hand, when a DC leak occurs during an ejection inspection of a nozzle 10 where DC leaks have occurred a small number of times, the environment around the other nozzles 10 is more likely to be one in which DC leaks are more likely to occur than when a DC leak occurs during an ejection inspection of a nozzle 10 where DC leaks have occurred a large number of times.

[0122] Therefore, in the ninth modification, the variable Kc N When a DC leak occurs during a discharge inspection of a nozzle 10 where the value of Kc1 is equal to or greater than a predetermined value, that is, when a DC leak occurs during a discharge inspection of a nozzle 10 where the number of occurrences of a DC leak is Kc1 or more, the variable Kc N A discharge inspection is performed on the nozzles 10 for which the value of Kc is less than a predetermined value Kc1, i.e., the number of times that DC leakage has occurred is less than Kc1, and the variable Kc NFor nozzles where the value of Kc1 is equal to or greater than a predetermined value Kc1, ejection inspection is not performed. This makes it possible to minimize the number of nozzles 10 that are not subjected to ejection inspection. Note that in Modification Example 9, Kc1 times corresponds to the "third number of times" of the present invention.

[0123] On the other hand, the variable Kc N If a DC leak occurs during ejection inspection of a nozzle 10 for which the value of Kc1 is less than the predetermined value Kc1, the ejection inspection process is stopped. This makes it possible to stop the ejection inspection process when it is highly necessary.

[0124] In the tenth modification, as in the eighth modification, a variable Kb indicating the number of times that an AC leak occurs during a discharge inspection of each of the nozzles 10 of the inkjet head 4 is set. N The value of is stored in the memory 34. In the tenth modification, when an inspection instruction signal is received, the control unit 30 performs processing according to the flowchart of FIG.

[0125] To explain the flow chart of FIG. 18 in detail, the control unit 30 sets a variable Kb N The nozzles 10 for which the value is less than a predetermined value Kb3 are set as targets for discharge inspection (S1001), and the discharge inspection process is started in the same manner as S102 in the above embodiment (S1002). However, in the discharge inspection process started in S1002, discharge inspection is performed only on the nozzles 10 set as targets for discharge inspection in S1001.

[0126] After starting the discharge inspection process in S1002, the control unit 30 determines whether or not an AC leak has occurred (S1003), in the same manner as in S103 in the above embodiment. If an AC leak has not occurred (S1003: NO), the process proceeds to S1005. If an AC leak has occurred (S1003: YES), the control unit 30 sets the variable Kb N is incremented by 1 (S1004), and the process proceeds to S1005.

[0127] In S1005, the control unit 30 determines whether or not a DC leak has occurred, similar to S102 in the above embodiment. If a DC leak has occurred (S1005: YES), the control unit 30 stops the discharge inspection process (S1007), and the process ends.

[0128] If no DC leak has occurred (S1005: NO), the control unit 30 determines whether the discharge inspection process has been completed (S1006). If the discharge inspection has not been completed (S1006: NO), the process returns to S1003. When the discharge inspection has been completed (S1006: YES), the control unit 30 executes the processes of S1008 and S1009, which are the same as S808 and S809 in the eighth modification, and the process ends. That is, in the tenth modification as well, the variable Kb N is equal to or greater than G1, a head replacement signal is output and a screen is displayed on the operation panel 39 to prompt the user to replace the inkjet head 4.

[0129] In addition, in the tenth modification, as in the eighth modification, the control unit 30 performs processing according to the flowchart of FIG. 16B while power is being supplied to the printer 1. As a result, when the inkjet head 4 is replaced, the variable Kb N The value is reset to 0.

[0130] For nozzles 10 where AC leakage occurs frequently, there is a high possibility that AC leakage will occur during the subsequent discharge inspection process. N Only nozzles 10 for which the value of Kb3 is less than a predetermined value are subject to discharge inspection. In other words, discharge inspection is performed on each of the nozzles 10 excluding nozzles 10 for which the number of times AC leakage has occurred is equal to or greater than Kb3. This makes it possible to make AC leakage less likely to occur during the discharge inspection process. In the tenth modification, Kb3 times corresponds to the "fourth number" of the present invention.

[0131] Furthermore, when the inkjet head 4 is replaced, the likelihood of AC leakage occurring in each nozzle 10 changes. Therefore, in the tenth modification, when the inkjet head 4 is replaced, the variable Kb N This resets the value of the variable Kb N The value of can be set appropriately according to the state of the ink-jet head 4.

[0132] In the eighth and tenth modified examples, when the inkjet head 4 is replaced, the variables Kb N I reset the value of the variable Kb N For example, the value of the variable Kb stored in the memory 34 may not be reset. N If the value of indicates the number of times that AC leakage occurred during the discharge inspection of the corresponding nozzle 10 during the period from the current time to the time a predetermined time ago, the variable Kb N The value of Kb N The value of gradually approaches the value corresponding to the state of the ink-jet head 4 over time.

[0133] In addition, in the eighth and tenth modified examples, the control unit 30 outputs a head replacement signal to the operation panel 39, thereby causing the operation panel 39 to display a screen for urging the user to replace the inkjet head 4, but this is not limited to the above. The user may be urged to replace the inkjet head 4 by another method in response to the output of the head replacement signal from the control unit 30. For example, the printer may be provided with an LED lamp, and the control unit 30 may output a head replacement signal to the LED lamp to turn on or blink the LED lamp, thereby urging the user to replace the inkjet head 4. Alternatively, the printer 1 may be provided with a speaker, and the control unit 30 may output a head replacement signal to the speaker to cause the speaker to generate a sound, thereby urging the user to replace the inkjet head 4.

[0134] In addition, in the eighth and tenth modified examples, the variable Kb N When the number G of nozzles 10 for which the value is equal to or greater than the predetermined value Kb2 becomes equal to or greater than G1, a head replacement signal is output to prompt the user to replace the inkjet head 4, but this is not limited to this. It is also possible that the head replacement signal does not need to be output when the number G of nozzles 10 becomes equal to or greater than G1.

[0135] In the eleventh modification, the control unit 30 performs the same process as that described in the tenth modification. Furthermore, in the eleventh modification, when the control unit 30 receives a recording instruction signal, it performs the process according to the flowchart of FIG. 19. In detail, the control unit 30 judges whether or not the number Kd of abnormal discharge nozzles indicated by the result of the previous discharge inspection process is equal to or greater than a predetermined number Kd1 (S1101). Here, the predetermined number Kd1 may be one, or may be two or more. If the number Kd of abnormal discharge nozzles is equal to or greater than the predetermined number Kd1 (S1101: YES), the control unit 30 executes a complementary recording process (S1104), and the process ends. The complementary recording process will be described in detail later.

[0136] If the number Kd of nozzles with ejection abnormalities is less than the predetermined number Kd1 (S1101: NO), the control unit 30 N The control unit 30 determines whether the number Ke of leak abnormal nozzles, which are nozzles 10 having a value of Kb3 or more, is equal to or greater than a predetermined number Ke1 (S1102). Here, the predetermined number Ke1 may be 1, or may be 2 or more. If the number Ke of leak abnormal nozzles is equal to or greater than the predetermined number Ke1 (S1102: YES), the control unit 30 executes a complementary recording process (S1104) and ends the process. If the number Ke of leak abnormal nozzles is less than the predetermined number Ke1 (S1102: NO), the control unit 30 executes a non-complementary recording process (S1103) and ends the process.

[0137] <Non-complementary record processing and complementary record processing> The non-complementary recording process of S1103 and the complementary recording process of S1104 will be described. In both the non-complementary recording process of S1103 and the complementary recording process of S1104, the control unit 30 causes the recording pass and the conveying operation to be repeated, thereby recording an image on the recording paper S.

[0138] In the non-complementary recording process, the control unit 30 performs non-complementary recording in which one raster line L formed by arranging multiple dots D in the scanning direction is formed in one recording pass, as shown in FIG. 20(a). As a result, in an image recorded by non-complementary recording, multiple dots D forming one raster line L are all formed by ink ejected from one nozzle 10. In the non-complementary recording process, the control unit 30 conveys the recording paper S by a conveyance amount B1 in the conveyance operation. The conveyance amount B1 corresponds to the length of the nozzle row 9 in the conveyance direction. Here, FIG. 20(a) shows a dot D formed in the K-th recording pass and a dot D formed in the (K+1)-th recording pass, where K is an integer equal to or greater than 1.

[0139] In Fig. 20(a), the hatched dots D indicate dots D formed in each printing pass, and the non-hatched dots D indicate dots D formed in the previous printing passes. The same applies to Figs. 20(b), 21(a), and (b) described later.

[0140] Here, when non-complementary recording is performed in a state where there is a nozzle with an abnormal discharge, ink may not be discharged from the nozzle with an abnormal discharge, and the corresponding dot D may not be formed. Also, when non-complementary recording is performed in a state where there is a nozzle with an abnormal leak, when the inkjet head 4 is driven to discharge ink from the nozzle with an abnormal leak, the ink may scatter and the corresponding dot D may not be formed. Therefore, when non-complementary recording is performed in a state where there is a nozzle with an abnormal discharge and a nozzle with an abnormal leak, all of the dots D forming the raster line L corresponding to the nozzle with an abnormal discharge and the nozzle with an abnormal leak may not be formed, and white streaks W extending in the scanning direction may occur in the recorded image. The white streaks W are linear areas that extend over the entire length of the image in the scanning direction where the recording paper S is exposed due to the absence of dots D. The greater the number of nozzles with an abnormal discharge, the greater the number of white streaks W, or the greater the length of the white streaks W in the transport direction. The greater the number of nozzles with an abnormal leak, the greater the number of white streaks W, or the greater the length of the white streaks W in the transport direction. The greater the number of white streaks W, the more noticeable the deterioration of image quality becomes. Furthermore, the longer the length of the white streak W in the transport direction, the more noticeable the degradation in image quality becomes.

[0141] In Fig. 20(a), the nozzles 10 marked with an x ​​indicate that they are abnormal ejection nozzles or abnormal leak nozzles, and the dots D indicated by dashed lines indicate dots D that are not formed corresponding to the abnormal ejection nozzles or abnormal leak nozzles. The same applies to Figs. 20(b), 21(a), and (b) described below.

[0142] 20(b), in the complementary recording process, the control unit 30 sets the transport amount of the recording paper in the transport operation to transport amount B2, which is one-third of transport amount B1, and performs complementary recording in which ink is ejected from the nozzles 10 in each recording pass to form only about one-third of the multiple dots D that form a raster line L. As a result, in complementary recording, one raster line L is formed in three recording passes, and the multiple dots D that form one raster line L are formed by ink ejected from three different nozzles 10.

[0143] In this case, even if one or two of the three nozzles 10 used to form one raster line L are abnormal discharge nozzles or abnormal leak nozzles, ink is discharged from the remaining nozzles 10 that are neither abnormal discharge nozzles nor abnormal leak nozzles, and dots D corresponding to the nozzles 10 that are neither abnormal discharge nozzles nor abnormal leak nozzles are formed among the multiple dots D that form the raster line L. Therefore, the white streaks W that extend over the entire length of the recorded image in the scanning direction as described above are unlikely to occur in the recorded image, and deterioration of image quality can be made less noticeable. Here, when recording is performed by complementary recording, the number of recording passes is greater than when recording is performed by non-complementary recording, and therefore the recording time is longer.

[0144] Thus, in the eleventh modified example, in complementary recording, some of the dots D that form the raster lines L corresponding to the abnormal ejection nozzles and abnormal leak nozzles when recording is performed by non-complementary recording are formed by ink ejected from the other nozzles 10 that are neither abnormal ejection nozzles nor abnormal leak nozzles. In other words, the ejection of ink from the abnormal ejection nozzles or abnormal leak nozzles is complemented by the ejection of ink from the other nozzles 10 that are neither abnormal ejection nozzles nor abnormal leak nozzles.

[0145] Nozzles 10 where AC leaks have occurred many times are likely to be unable to eject ink normally. For example, when the inkjet head 4 is driven to eject ink from a nozzle 10 where AC leaks have occurred many times, there is a high possibility that ink will be ejected from this nozzle 10 in a splattering manner. Furthermore, in the ejection inspection process, ejection inspection is not performed on nozzles 10 where AC leaks have occurred Kb3 or more times, and therefore these may be nozzles with ejection abnormalities. Therefore, in Modification 11, when liquid is ejected from multiple nozzles 10 onto the ejection receiving medium, the variable Kb NThe nozzles 10 whose value is equal to or greater than a predetermined value Kb3, i.e., the nozzles 10 whose AC leaks have occurred Kb3 or more times, are considered to be ejecting ink from the nozzles 10. N The value of Kb3 is less than the predetermined value, that is, the number of occurrences of AC leaks is less than Kb3. This makes it possible to prevent ink from being ejected from nozzles 10 that are highly likely to be unable to eject ink normally.

[0146] In the eleventh modification, in complementary printing, the multiple dots D that form one raster line L are printed in three printing passes, but this is not limited to this. In complementary printing, the multiple dots D that form one raster line L may be printed in two or four or more printing passes.

[0147] Furthermore, in complementary printing, by printing multiple dots D that form one raster line L in multiple printing passes, the ink ejection from the abnormal ejection nozzle and the abnormal leak nozzle can be complemented by the ink ejection from other nozzles 10 that are neither abnormal ejection nozzles nor abnormal leak nozzles.

[0148] In the modified example 12, the control unit 30 performs the non-complementary recording process in the same manner as described in the modified example 11. However, in the modified example 12, unlike the modified example 11, the control unit 30 converts the recording data in the complementary recording process to one that instructs the recording of an image with higher resolution in the scanning direction and the transport direction. Then, as shown in FIG. 21(a), in each recording pass, the interval between the ink landing positions in the scanning direction is made shorter than that in the non-complementary recording process, and the amount of ink ejected from the nozzle 10 is made smaller than that in the non-complementary recording process. To make the interval between the ink landing positions in the scanning direction in a recording pass shorter than that in the non-complementary recording process, for example, the time interval at which ink is ejected from the nozzle 10 in the recording pass is made shorter than that in the non-complementary recording process, or the moving speed of the carriage 2 in the recording pass is made slower than that in the non-complementary recording process.

[0149] In addition, in the twelfth modification, in complementary recording, M is an odd number equal to or greater than 1, and the transport amount B3 of the recording paper S in the transport operation is set to (M / 2) times the distance A between the nozzles 10 in the nozzle row 9. Note that FIG. 21(a) shows the case where M=3.

[0150] As a result, in the modified example 12, an image with higher resolution in the scanning direction and the transport direction is recorded in the complementary recording than in the non-complementary recording. In this case, when there is a discharge abnormal nozzle or a leak abnormal nozzle, the dots D formed by the ink discharged from the other nozzles 10 that are neither discharge abnormal nozzles nor leak abnormal nozzles are arranged in a part of the area where the dots D corresponding to the discharge abnormal nozzles and the leak abnormal nozzles are not formed when the recording paper S is recorded by the non-complementary recording. In other words, the discharge of the ink from the discharge abnormal nozzles and the leak abnormal nozzles can be complemented by the discharge of the ink from the other nozzles 10 that are neither discharge abnormal nozzles nor leak abnormal nozzles. As can be seen by comparing FIG. 20(a) and FIG. 21(a), when recording is performed by the complementary recording, the length of the white stripe W in the transport direction is shorter than when recording is performed by the non-complementary recording, and the white stripe W becomes less noticeable. Here, even in the modified example 12, when recording is performed on the recording paper S by the complementary recording, the number of recording passes is greater than when recording on the recording paper S by the non-complementary recording, and therefore the recording time is longer.

[0151] In addition, in the modification 12, the resolution in both the scanning direction and the transport direction is higher in the complementary recording than in the non-complementary recording, but this is not limited to this. In the complementary recording of the modification 12, the resolution in only the transport direction out of the scanning direction and the transport direction may be higher than in the non-complementary recording.

[0152] In the modified example 13, the control unit 30 executes the non-complementary recording process in the same manner as described in the modified example 11. However, in the modified example 13, unlike the modified example 11, in the complementary recording process, as shown in FIG. 21(b), the amount of ink discharged from the nozzles 10 adjacent to the abnormal discharge nozzle and the abnormal leak nozzle in the transport direction in the recording pass is increased compared to that in the non-complementary recording process, thereby increasing the size of the dots D formed by the ink discharged from the nozzles 10. As a result, a part of the dots D formed by the ink discharged from the nozzles 10 adjacent to the abnormal discharge nozzle and the abnormal leak nozzle in the transport direction protrudes into the area of ​​the recording paper S where the dots D corresponding to the abnormal discharge nozzle and the abnormal leak nozzle were not formed. In other words, the discharge of the ink from the abnormal discharge nozzle and the abnormal leak nozzle is complemented by the discharge of the ink from the other nozzles 10 that are neither the abnormal discharge nozzle nor the abnormal leak nozzle. As a result, as can be seen by comparing FIG. 20(a) and FIG. 21(b), the length of the white streak W in the transport direction is shortened, and the white streak W becomes less noticeable.

[0153] In addition, in the thirteenth modification, in complementary recording, the amount of ink ejected from the nozzles 10 adjacent to the abnormal ejection nozzle and the abnormal leak nozzle on the upstream and downstream sides in the transport direction is made larger than in non-complementary recording, but this is not limited to the above. In complementary recording, the amount of ink ejected from only one of the nozzles 10 adjacent to the abnormal ejection nozzle and the abnormal leak nozzle on the upstream and downstream sides in the transport direction may be made larger than in non-complementary recording.

[0154] In addition, in Modification 13, when the most upstream nozzle 10 in the transport direction is an abnormal ejection nozzle or a leak abnormal nozzle, the most downstream nozzle 10 in the transport direction may be regarded as the nozzle 10 adjacent to the most upstream nozzle 10 in the transport direction, and the amount of ink ejected may be greater than in non-complementary recording. In addition, in Modification 13, when the most downstream nozzle 10 in the transport direction is an abnormal ejection nozzle or a leak abnormal nozzle, the most upstream nozzle 10 in the transport direction may be regarded as the nozzle 10 adjacent to the most downstream nozzle 10 in the transport direction, and the amount of ink ejected may be greater than in non-complementary recording.

[0155] In addition, in the complementary recording, the ink ejection from the abnormal ejection nozzle and the abnormal leak nozzle may be complemented by the ink ejection from the other nozzles 10 that are neither the abnormal ejection nozzle nor the abnormal leak nozzle, in a method different from that described above. In addition, in the modified examples 11 to 13, both the ink ejection from the abnormal ejection nozzle and the ink ejection from the abnormal leak nozzle are complemented by the ink ejection from the other nozzles 10, but this is not limited to this. For example, the ink ejection from the abnormal leak nozzle may be complemented as described in the modified examples 11 to 13, and the ink ejection from the abnormal ejection nozzle may not be complemented as described in the modified examples 11 to 13. In this case, for example, if the number Kd of the abnormal ejection nozzles is equal to or greater than a predetermined number Kd1, the abnormal ejection nozzle may be restored by performing suction purging before recording on the recording paper S.

[0156] In the above example, the first leak is an AC leak in which a current equal to or greater than a first predetermined value flows for less than a predetermined time, and the second leak is a DC leak in which a current equal to or greater than a second predetermined value flows for more than a predetermined time, but this is not limiting. The first leak may be a leak different from the AC leak. The second leak may be a leak different from the DC leak.

[0157] For example, in the case where the inspection circuit 27 can detect DC leaks but cannot detect AC leaks, a DC leak in which a current equal to or greater than a second predetermined value flows for a period of time equal to or greater than a first time and less than a second time may be defined as a first leak, and a DC leak in which a current equal to or greater than a second predetermined value flows for a period of time equal to or greater than a second time may be defined as a second leak. Alternatively, a leak in which an AC leak or a DC leak occurs intermittently for a period of time equal to or greater than a first time and less than a second time may be defined as a first leak, and a leak in which an AC leak or a DC leak occurs intermittently for a period of time equal to or greater than a second time may be defined as a second leak. In these cases, since the second leak is a leak in which a current flows for a longer period of time than the first leak, it is more necessary to stop the discharge inspection process when the second leak occurs than when the first leak occurs.

[0158] Alternatively, for example, the second predetermined value may be greater than the first predetermined value, the first leak may be a leak through which a current equal to or greater than the first predetermined value and less than the second predetermined value flows, and the second leak may be a leak through which a current equal to or greater than the second predetermined value flows. In this case, since the second leak is greater than the current value of the first leak, when the second leak occurs, it is more necessary to stop the discharge inspection process than when the first leak occurs.

[0159] In the above, an example has been described in which it is determined whether or not a leak has occurred each time a discharge test is performed on one nozzle 10, but this is not limiting. For example, it may be determined whether or not a leak has occurred each time a discharge test is performed on a predetermined number of nozzles 10 (two or more). Alternatively, it may be determined whether or not a leak has occurred just once before discharge tests are performed on all nozzles 10.

[0160] Alternatively, the discharge inspection process and the process of determining whether or not a leak has occurred may be executed in parallel. In this case, the process of determining whether or not a leak has occurred may be continued from the start to the completion of the discharge inspection process.

[0161] 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 caps 21, the pressure pump may be driven to perform a pressure purge that discharges the ink in the inkjet head 4.

[0162] Also, both the suction purge by driving the suction pump 22 and the pressure purge by driving the pressure pump described above may be performed.

[0163] 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.

[0164] 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]

[0165] 1: Printer 4: Inkjet head 8: Maintenance unit 10, 10a to 10e: Nozzle 21: Cap 22: Pump 26: Electrode 27: Inspection circuit 29: Lip section 30: Control unit 34: Memory

Claims

1. A head having a plurality of nozzles; an inspection signal output unit having an electrode, the inspection signal output unit outputting an inspection signal corresponding to an electrical change in the electrode when the head is driven to eject liquid from the nozzle toward the electrode; a leak signal output section that outputs a first leak signal when a first leak occurs in which a current of a first predetermined value or more flows between the head and the electrode, and outputs a second leak signal different from the first leak signal when a second leak occurs different from the first leak in which a current of a second predetermined value or more flows between the head and the electrode; A control unit, The control unit is driving the head to eject liquid from each of the plurality of nozzles toward the electrode in sequence, and executing an ejection inspection process to inspect whether or not there is an abnormality in the ejection of liquid from the nozzle based on the inspection signal output from the inspection signal output unit; even if the first leak signal is output from the leak signal output unit during the discharge inspection process, the discharge inspection process is continued; A liquid ejection device characterized in that, when the second leak signal is output from the leak signal output unit during the ejection inspection process, the ejection inspection for the nozzles for which the ejection inspection has not yet been performed in the ejection inspection process is stopped.

2. the first leakage is leakage during which a time during which a current equal to or greater than the first predetermined value flows between the head and the electrode is shorter than a predetermined time, 2. The liquid ejection device according to claim 1, wherein the second leakage is leakage during which a current equal to or greater than the second predetermined value flows between the head and the electrode for a period of time equal to or greater than the predetermined period of time.

3. The control unit is A liquid ejection device as described in claim 1, characterized in that when the number of nozzles that have obtained the first leak signal from the leak signal output unit reaches a predetermined number during the ejection inspection process, the ejection inspection of the nozzles that have not yet been subjected to the ejection inspection in the ejection inspection process is discontinued.

4. The control unit is The liquid ejection device according to claim 1, characterized in that, when the first leak signal is output from the leak signal output unit during any of the ejection inspections for a predetermined number of nozzles that are successively subjected to the ejection inspection during the ejection inspection process, the ejection inspection for the nozzles that have not yet been subjected to the ejection inspection in the ejection inspection process is discontinued.

5. the plurality of nozzles includes a first nozzle and a second nozzle, The control unit is continuing the discharge inspection process even if the first leak signal is output from the leak signal output unit during the discharge inspection of the first nozzle during the discharge inspection process; A liquid ejection device as described in claim 1, characterized in that when the first leak signal is output from the leak signal output unit during the ejection inspection process for the second nozzle, the ejection inspection for the nozzle that has not yet been subjected to the ejection inspection in the ejection inspection process is stopped.

6. The control unit is When the second leak signal is output from the leak signal output unit during the ejection inspection process, After the second leak signal is output from the leak signal output unit and the ejection inspection of the nozzles that have not yet been subjected to the ejection inspection in the ejection inspection process is stopped, When an inspection instruction signal instructing to perform the discharge inspection is received again before the first time has elapsed, the discharge inspection process is not executed, 2. The liquid ejection device according to claim 1, wherein when the inspection command signal is received again after the first time period has elapsed, the ejection inspection process is executed.

7. a cap having the electrodes disposed therein and covering the plurality of nozzles; a pump that generates pressure to eject liquid from the plurality of nozzles; The control unit is activating the pump in a state in which the plurality of nozzles are covered with a cap to perform purging by discharging liquid from the plurality of nozzles into the cap; when an inspection instruction signal for performing the ejection inspection is received before a second time has elapsed after the purging, a leak inspection process is executed to generate a potential difference between the electrode and the head without driving the head to eject liquid from the nozzle toward the electrode; When neither the first leak signal nor the second leak signal is output from the leak signal output unit by the leak check process, the leak check process is executed; When the leak test process outputs either the first leak signal or the second leak signal from the leak signal output unit, the ejection test process is not executed, When the inspection instruction signal is received after the second time or more has elapsed after the purging, the leak inspection process is executed; executes the ejection inspection process when neither the first leak signal nor the second leak signal is output from the leak signal output unit by the leak inspection process, and when the first leak signal is output from the leak signal output unit; 2. The liquid ejection device according to claim 1, wherein the ejection inspection process is not executed when the second leak signal is output from the leak signal output section by the leak inspection process.

8. A storage unit, The control unit is storing information on the number of occurrences of the first leak for each of the plurality of nozzles in the storage unit; When the first leak signal is output from the leak signal output unit while the ejection inspection is being performed on a certain nozzle during the ejection inspection process, When the number of occurrences of the first leak indicated by the information for the certain nozzle is equal to or greater than a first number, the ejection inspection process is continued; A liquid ejection device as described in claim 1, characterized in that if the number of occurrences of the first leak indicated by the information for a certain nozzle is less than the first number, the ejection inspection for the nozzle that has not yet been subjected to the ejection inspection in the ejection inspection process is terminated.

9. The control unit is A liquid ejection device as described in claim 8, characterized in that when the number of occurrences of the first leak indicated by the information for a predetermined number or more of the nozzles becomes a second number or more, a head replacement signal is output to prompt replacement of the head.

10. A storage unit, The control unit is storing information regarding the number of occurrences of the second leak for each of the plurality of nozzles; when the second leak signal is output from the leak signal output unit during the discharge inspection process for the nozzles for which the number of occurrences of the second leak indicated by the information is a third number or more, the discharge inspection is performed for the nozzles for which the discharge inspection has not yet been performed in the discharge inspection process and for which the number of occurrences of the second leak indicated by the information is less than the third number, and the discharge inspection is not performed for the nozzles for which the number of occurrences of the second leak indicated by the information is the third number or more, The liquid ejection device according to claim 1, characterized in that when the second leak signal is output from the leak signal output unit during the ejection inspection process for a nozzle for which the number of occurrences of the second leak indicated by the information is less than a third number, the ejection inspection for the nozzle for which the ejection inspection has not yet been performed in the ejection inspection process is terminated.

11. A storage unit, The control unit is storing information regarding the number of occurrences of the first leak for each of the plurality of nozzles; 2. The liquid ejection device according to claim 1, wherein in the ejection inspection process, the ejection inspection is performed on each of the nozzles excluding the nozzles for which the number of occurrences of the first leak indicated by the information is four or more.

12. The control unit is The liquid ejection device according to claim 11, characterized in that when the head ejects liquid from the multiple nozzles onto the ejection medium, the ejection of liquid from a nozzle where the number of occurrences of the first leak indicated by the information is equal to or greater than the fourth number is complemented by the ejection of liquid from another nozzle where the number of occurrences of the first leak indicated by the information is less than the fourth number.

13. The control unit is 12. The liquid ejection device according to claim 11, wherein the information stored in the memory unit is reset when a replacement signal indicating that the head has been replaced is received.

14. A head having a plurality of nozzles; an inspection signal output unit having an electrode, the inspection signal output unit outputting an inspection signal corresponding to an electrical change in the electrode when the head is driven to eject liquid from the nozzle toward the electrode; a leak signal output unit that outputs a leak signal according to whether or not a leak occurs between the head and the electrode, in which a current of a predetermined value or more flows; A control unit, The control unit is driving the head to eject liquid from each of the plurality of nozzles toward the electrode in sequence, and executing an ejection inspection process to inspect whether or not there is an abnormality in the ejection of liquid from the nozzle based on the inspection signal output from the inspection signal output unit; continuing the discharge inspection process even if the leak signal is output from the leak signal output unit while the discharge inspection is being performed on a first nozzle of the plurality of nozzles during the discharge inspection process; A liquid ejection device characterized in that, when the leak signal is output from the leak signal output unit during the ejection inspection process while the ejection inspection is being performed on a second nozzle among the plurality of nozzles that is different from the first nozzle, the ejection inspection of the nozzles in the ejection inspection process that have not yet been subjected to the ejection inspection is stopped.

15. a cap having a lip portion, the electrode being disposed therein, the cap covering the plurality of nozzles; The liquid ejection device according to claim 14 , wherein the second nozzle is closer to the lip portion than the first nozzle when the plurality of nozzles are covered by the cap.

16. A storage unit, The control unit is storing information on the number of occurrences of the leak for each of the plurality of nozzles in the storage unit; Among the plurality of nozzles, a nozzle for which the number of occurrences of the leak indicated by the information is equal to or greater than a predetermined number and a nozzle located at a distance from the nozzle indicated by the information equal to or less than a predetermined distance are set as the second nozzle; The liquid ejection apparatus according to claim 14 , wherein the nozzles other than the second nozzles among the plurality of nozzles are set as the first nozzles.

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