Liquid dispensing device

Abstract

To appropriately perform purge according to the number of anomalous nozzles when ejecting liquid from a plurality of nozzles forming a plurality of nozzle groups different in liquid ejecting condition for a nozzle due to the purge.SOLUTION: Color suction purge is performed by driving a suction pump while three nozzle arrays different in color of ink ejected from a nozzle are kept covered with a cap. If the respective numbers of anomalous nozzles in the nozzle arrays are Ay, Ac, Am and if at least one of a condition that the number Ay of the anomalous nozzles is equal to or greater than a threshold Hy, a condition that the number Ac of the anomalous nozzles is equal to or greater than a threshold Hc, a condition that the number Am of the anomalous nozzles is equal to or greater than a threshold Hm, and a condition that a total number Ag (=Ay + Ac + Am) of the anomalous nozzles is equal to or greater than a threshold Hg is satisfied (S105: YES), a color purge process is executed to perform the color suction purge (S106).SELECTED DRAWING: Figure 5

Description

Technical Field

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

Background Art

[0002] As an example of a liquid ejection device that ejects a liquid from a nozzle, Patent Document 1 describes an inkjet printer that ejects ink from a nozzle to perform printing. In the inkjet printer described in Patent Document 1, before executing printing, nozzle checks are performed for all nozzles of the inkjet head. Then, when the number of defective ejection nozzles is equal to or greater than a first threshold value, cleaning is performed. Even when the number of defective ejection nozzles is less than the first threshold value, if a command designating a predetermined area is included in the print data, and when the number of defective ejection nozzles detected from the nozzle area corresponding to the predetermined area is equal to or greater than a second threshold value different from the first threshold value, cleaning is performed on the nozzle area corresponding to the predetermined area.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, as cleaning of the nozzle, a liquid ejection device is known that covers a plurality of nozzles with a cap and performs a purge that applies pressure to the ink in the head by a pump. And in such a liquid ejection device, as in Patent Document 1, it is conceivable to perform a purge when the number of abnormal nozzles exceeds a threshold value. Also, in a purge, there are cases where a plurality of types of nozzles with different ejection conditions are covered with a common cap to discharge ink.

[0005] In this case, for example, one could set a threshold for the number of abnormal nozzles in all nozzles covered by the cap to determine whether or not to perform purging. However, in this case, if the number of abnormal nozzles is high in a particular type of nozzle, but the number of abnormal nozzles in all nozzles covered by the cap is below the threshold, purging may not be performed, potentially resulting in poor image quality of the recorded images.

[0006] Alternatively, one could consider setting a threshold for the number of abnormal nozzles for each type of nozzle to determine whether or not to perform purging. However, in this case, even if the number of abnormal nozzles for each type is below the threshold, if the total number of abnormal nozzles is large, purging may not be performed, potentially resulting in poor image quality for the recorded images.

[0007] The object of the present invention is to provide a liquid dispensing device that can cover multiple types of nozzles with different discharge conditions with a common cap and perform purging, and can perform purging appropriately according to the number of abnormal nozzles. [Means for solving the problem]

[0008] The liquid discharge device of the present invention includes a head having a plurality of nozzle groups of a plurality of types, each formed by a plurality of nozzles, wherein the liquid discharge conditions of the nozzles differ; a cap covering the nozzles forming the plurality of nozzle groups; a pump for applying pressure to the liquid in the head; a purging means for performing a purging by driving the pump while the nozzles forming the plurality of nozzle groups are covered by the cap, thereby discharging liquid from the nozzles forming the plurality of nozzle groups; and a control unit, wherein the plurality of nozzle groups include a first nozzle group and a second nozzle group, and the control unit, when a predetermined condition is met, determines the number of first abnormal nozzles, which are abnormal nozzles among the nozzles forming the first nozzle group that have abnormal liquid discharge conditions, and the number of nozzles forming the second nozzle group Abnormal nozzle information is acquired according to the number of abnormal nozzles, namely the second abnormal nozzles, and the total number of abnormal nozzles, which is the sum of the number of abnormal nozzles in the nozzles forming at least some of the nozzle groups of the multiple types of nozzle groups. A decision process is executed to determine whether or not to perform the purging based on the abnormal nozzle information. Based on the decision to perform the purging in the decision process, a purging process is executed to cause the purging means to perform the purging. In the decision process, if at least one of a plurality of purging conditions is met, including a first purging condition that the number of first abnormal nozzles is equal to or greater than a first threshold, a second purging condition that the number of second abnormal nozzles is equal to or greater than a second threshold, and a third purging condition that the total number of abnormal nozzles is equal to or greater than a third threshold, the purging means is determined to perform the purging. Furthermore, the discharge conditions include conditions regarding the nozzle diameter. . Furthermore, the liquid discharge device of the present invention includes a head having a plurality of nozzle groups of a plurality of types, each formed by a plurality of nozzles, wherein the liquid discharge conditions of the nozzles differ; a cap covering the nozzles forming the plurality of nozzle groups; a pump for applying pressure to the liquid in the head; a purging means for performing a purging by driving the pump while the nozzles forming the plurality of nozzle groups are covered by the cap, thereby discharging liquid from the nozzles forming the plurality of nozzle groups; and a control unit, wherein the plurality of nozzle groups include a first nozzle group and a second nozzle group, and the control unit, when a predetermined condition is met, acquires abnormal nozzle information corresponding to the number of first abnormal nozzles which are abnormal nozzles with abnormal liquid discharge among the nozzles forming the first nozzle group, the number of second abnormal nozzles which are abnormal nozzles among the nozzles forming the second nozzle group, and the total number of abnormal nozzles which is the sum of the number of abnormal nozzles in at least some of the nozzle groups forming the plurality of nozzle groups, and executes a decision process to determine whether or not to perform the purging based on the abnormal nozzle information. Based on the determination process that determines to perform the purging, the system executes a purging process to cause the purging means to perform the purging, and in the determination process, if at least one of a plurality of purging conditions is met, including a first purging condition that the number of first abnormal nozzles is equal to or greater than a first threshold, a second purging condition that the number of second abnormal nozzles is equal to or greater than a second threshold, and a third purging condition that the total number of abnormal nozzles is equal to or greater than a third threshold, the system determines to cause the purging means to perform the purging, and the discharge conditions include conditions regarding the characteristics of the liquid to be discharged, and the conditions regarding the characteristics of the liquid include conditions regarding whether the liquid contains a pigment or a dye. Furthermore, the liquid discharge device of the present invention includes a head having a plurality of nozzle groups of a plurality of types, each formed by a plurality of nozzles, wherein the liquid discharge conditions of the nozzles differ; a cap covering the nozzles forming the plurality of nozzle groups; a pump for applying pressure to the liquid in the head; a purging means for performing a purging by driving the pump while the nozzles forming the plurality of nozzle groups are covered by the cap, thereby discharging liquid from the nozzles forming the plurality of nozzle groups; and a control unit, wherein the plurality of nozzle groups include a first nozzle group and a second nozzle group, and the control unit, when a predetermined condition is met, determines the number of first abnormal nozzles which are abnormal nozzles with abnormal liquid discharge among the nozzles forming the first nozzle group, the number of second abnormal nozzles which are abnormal nozzles among the nozzles forming the second nozzle group, and the number of nozzles which are abnormal nozzles among the nozzles forming the plurality of nozzle groups, at least some of the nozzles forming the plurality of nozzle groups The system obtains the total number of abnormal nozzles, which is the sum of the number of abnormal nozzles in the system, and abnormal nozzle information corresponding to that number. Based on the abnormal nozzle information, a decision process is executed to determine whether or not to perform the purging. Based on the decision to perform the purging in the decision process, a purging process is executed to cause the purging means to perform the purging. In the decision process, if at least one of a plurality of purging conditions is met, including a first purging condition that the number of first abnormal nozzles is equal to or greater than a first threshold, a second purging condition that the number of second abnormal nozzles is equal to or greater than a second threshold, and a third purging condition that the total number of abnormal nozzles is equal to or greater than a third threshold, the system causes the purging means to perform the purging. In the decision process, if it is determined not to cause the purging means to perform the purging, and the number of first abnormal nozzles is equal to or greater than a fifth threshold that is smaller than the first threshold, the system determines to cause the head to perform flushing to discharge liquid from the first abnormal nozzles. Furthermore, the liquid discharge device of the present invention includes a head having a plurality of nozzle groups of a plurality of types, each formed by a plurality of nozzles, wherein the liquid discharge conditions of the nozzles differ; a cap covering the nozzles forming the plurality of nozzle groups; a pump for applying pressure to the liquid in the head; a purging means for performing a purging to discharge liquid from the nozzles forming the plurality of nozzle groups by driving the pump while the nozzles forming the plurality of nozzle groups are covered by the cap; a signal transmitting unit that transmits a signal according to whether the nozzles are abnormal nozzles with abnormal liquid discharge when an inspection drive is performed in the head to discharge liquid from the nozzles forming the plurality of nozzle groups; and a control unit, wherein the plurality of nozzle groups include a first nozzle group and a second nozzle group, and the control unit, when a predetermined condition is met, determines the number of first abnormal nozzles that are abnormal nozzles among the nozzles forming the first nozzle group, and the number of second abnormal nozzles that are abnormal nozzles among the nozzles forming the second nozzle group. Abnormal nozzle information is acquired corresponding to the number of abnormal nozzles and the total number of abnormal nozzles, which is the sum of the number of abnormal nozzles in the nozzles forming at least some of the nozzle groups of the plurality of types of nozzle groups, a decision process is executed to determine whether or not to perform the purging based on the abnormal nozzle information, a purging process is executed to cause the purging means to perform the purging based on the decision process to determine whether or not to perform the purging, a decision process is executed to cause the purging means to perform the purging if at least one of a plurality of purging conditions is met, including a first purging condition in which the number of first abnormal nozzles is equal to or greater than a first threshold, a second purging condition in which the number of second abnormal nozzles is equal to or greater than a second threshold, and a third purging condition in which the total number of abnormal nozzles is equal to or greater than a third threshold, a predetermined condition includes the condition that a predetermined time has arrived, and at the predetermined time, the head is made to perform the inspection drive, the abnormal nozzle information is acquired based on the signal transmitted from the signal transmission unit when the inspection drive is performed, and the decision process is executed, and if the decision process determines that the purging should be performed,Subsequently, immediately before discharging liquid from the nozzles forming the group of nozzles described above toward the discharge medium, the purging means is made to perform the purging. Furthermore, the liquid discharge device of the present invention includes a head having a plurality of nozzle groups of a plurality of types, each formed by a plurality of nozzles, wherein the liquid discharge conditions of the nozzles differ; a cap covering the nozzles forming the plurality of nozzle groups; a pump for applying pressure to the liquid in the head; a purging means for performing a purging to discharge liquid from the nozzles forming the plurality of nozzle groups by driving the pump while the nozzles forming the plurality of nozzle groups are covered with the cap; and a control unit, wherein the plurality of nozzle groups include a first nozzle group and a second nozzle group, and the control unit, when a predetermined condition is met, determines the number of first abnormal nozzles which are abnormal nozzles among the nozzles forming the first nozzle group that have an abnormality in liquid discharge; the number of second abnormal nozzles which are abnormal nozzles among the nozzles forming the second nozzle group; and the number of abnormal nozzles in at least some of the nozzles forming the plurality of nozzle groups. The system obtains the total number of abnormal nozzles, which is the sum of the number of nozzles, and abnormal nozzle information corresponding to that number. Based on the abnormal nozzle information, a decision process is executed to determine whether or not to perform the purging. Based on the decision to perform the purging in the decision process, a purging process is executed to cause the purging means to perform the purging. In the decision process, if at least one of a plurality of purging conditions is met, including a first purging condition that the number of first abnormal nozzles is equal to or greater than a first threshold, a second purging condition that the number of second abnormal nozzles is equal to or greater than a second threshold, and a third purging condition that the total number of abnormal nozzles is equal to or greater than a third threshold, the system determines to cause the purging means to perform the purging. The predetermined conditions are those that satisfy either the first predetermined condition or a second predetermined condition different from the first predetermined condition. The system executes the decision process by setting at least one of the first threshold, second threshold, and third threshold values ​​to a different value depending on whether the first predetermined condition is met or the second predetermined condition is met. [Effects of the Invention]

[0010] In this invention, purging can be performed appropriately according to the number of abnormal nozzles. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of the printer according to the first embodiment. [Figure 2] This diagram illustrates the electrodes placed inside the cap, and the connection relationships between the electrodes and the high-voltage power supply circuit and signal processing circuit. [Figure 3] (a) is a diagram showing the signal output from the signal processing circuit when ink is ejected from the nozzle during the test drive, and (b) is a diagram showing the signal output from the signal processing circuit when ink is not ejected from the nozzle during the test drive. [Figure 4] This is a block diagram showing the electrical configuration of a printer. [Figure 5] (a) is a flowchart showing the processing flow when power is supplied to the printer in the first embodiment, and (b) is a diagram for explaining predetermined conditions. [Figure 6] This flowchart shows the processing flow that takes place when power is supplied to the printer in the second embodiment. [Figure 7] This is a flowchart showing the processing flow that takes place when power is supplied to the printer in the third embodiment. [Figure 8] (a) is a flowchart showing the processing flow when power is supplied to the printer in the fourth embodiment, and (b) is a flowchart showing the processing flow when a record command is input in the fourth embodiment. [Figure 9] This flowchart shows the processing flow that takes place when power is supplied to the printer in the fifth embodiment. [Figure 10] (a) is a diagram illustrating the first and second predetermined conditions, (b) is a diagram illustrating the threshold to be set when the first and second conditions are met, and (c) is a flowchart showing the process flow for resetting the suction purge count value. [Figure 11]It is a flowchart showing the flow of processing performed when a purge instruction signal is received in the sixth embodiment. [Figure 12] It is a schematic configuration diagram of the printer of the seventh embodiment. [Figure 13] It is a flowchart showing the flow of processing performed when power is supplied to the printer in the seventh embodiment.

Mode for Carrying Out the Invention

[0012] [First Embodiment] Hereinafter, a preferred first embodiment of the present invention will be described.

[0013] [Overall Configuration of Printer] As shown in FIG. 1, a printer 1 (the "liquid ejection device" of the present invention) according to the first embodiment includes a carriage 2, a sub-tank 3, an inkjet head 4 (the "head" of the present invention), a platen 5, conveyance rollers 6, 7 (the "conveyance unit" of the present invention), a maintenance unit 8 (the "purge means" of the present invention), and the like.

[0014] The carriage 2 is supported by two guide rails 11, 12 extending in the scanning direction. Hereinafter, as shown in FIG. 1, the right side and the left side in the scanning direction will be defined for the description. The carriage 2 is connected to a carriage motor 86 (see FIG. 4) via a belt or the like not shown. When the carriage motor 86 is driven, the carriage 2 moves in the scanning direction along the guide rails 11, 12.

[0015] The sub-tank 3 is mounted on the carriage 2. Here, the printer 1 includes a cartridge holder 13. Four ink cartridges 14 are removably mounted on the cartridge holder 13. The four ink cartridges 14 mounted on the cartridge holder 13 are arranged in the scanning direction and store black, yellow, cyan, and magenta inks (the "liquid" of the present invention) in order from the one located on the right side in the scanning direction.

[0016] The inkjet head 4 is mounted on the carriage 2 and connected to the lower end of the sub-tank 3. The inkjet head 4 is supplied with the four colors of ink from the sub-tank 3. The inkjet head 4 also ejects ink from a plurality of nozzles 10 formed on its lower surface, the nozzle surface 4a. More specifically, the plurality of nozzles 10 are arranged in the transport direction to form a nozzle row 9 (the "nozzle group" of this invention), and four rows of nozzle rows 9 are arranged in the scanning direction on the nozzle surface 4a. From the plurality of nozzles 10, black, yellow, cyan, and magenta inks are ejected in order, starting from the nozzle row 9 on the right side in the scanning direction.

[0017] Thus, in the first embodiment, the color of the ink ejected from the nozzle 10 differs among the four nozzle rows 9. Furthermore, this results in differences among the four nozzle rows 9 in terms of the viscosity of the ink ejected from the nozzle 10, and whether the ink contains pigment or dye. In other words, in the first embodiment, the characteristics of the ink ejected from the nozzle 10 differ among the four nozzle rows 9. Consequently, in the first embodiment, the ink ejection conditions at the nozzle 10 differ among the four nozzle rows 9.

[0018] In the first embodiment, one of the three nozzle rows 9 on the left corresponds to the "first nozzle group" of the present invention, another nozzle row 9 corresponds to the "second nozzle group" of the present invention, and the remaining nozzle row 9 corresponds to the "third nozzle group" of the present invention.

[0019] The platen 5 is positioned below the inkjet head 4 and faces multiple nozzles 10. The platen 5 extends along the entire length of the recording paper P in the scanning direction and supports the recording paper P from below. The transport roller 6 is positioned upstream of the inkjet head 4 and platen 5 in the transport direction. The transport roller 7 is positioned downstream of the inkjet head 4 and platen 5 in the transport direction. The transport rollers 6 and 7 are connected to a transport motor 87 (see Figure 4) via gears or the like (not shown). When the transport motor 87 is driven, the transport rollers 6 and 7 rotate, and the recording paper P is transported in the transport direction.

[0020] The maintenance unit 8 comprises a cap 71, a switching unit 72, a suction pump 73, and a waste liquid tank 74. The cap 71 is positioned to the right of the platen 5 in the scanning direction. The cap 71 has two cap portions 71a and 71b aligned in the scanning direction. When the carriage 2 is positioned in the maintenance position to the right of the platen 5 in the scanning direction, multiple nozzles 10 face the cap 71. More specifically, when the carriage 2 is positioned in the maintenance position, the rightmost row of nozzles 9 faces cap portion 71a, and the leftmost three rows of nozzles 9 face cap portion 71b.

[0021] Furthermore, the cap 71 is connected to a cap lifting mechanism 88 (see Figure 4). When the cap lifting mechanism 88 is driven, the cap 71 moves up and down. With the carriage 2 positioned in the maintenance position described above, the cap 71 faces the multiple nozzles 10. When the cap 71 is raised by the cap lifting mechanism 88, the upper end of the cap 71 comes into close contact with the nozzle surface 4a. As a result, the multiple nozzles 10 forming the rightmost nozzle row 9 are covered by the cap portion 71a, and the multiple nozzles 10 forming the leftmost three rows of nozzle rows 9 are covered by the cap portion 71b. When the cap 71 is lowered, the multiple nozzles 10 are not covered by the cap 71. Note that the cap 71 is not limited to covering the multiple nozzles 10 by coming into close contact with the nozzle surface 4a. The cap 71 may, for example, cover the multiple nozzles 10 by coming into close contact with a frame (not shown) arranged around the nozzle surface 4a of the inkjet head 4.

[0022] The switching unit 72 is connected to the cap sections 71a and 71b. The switching unit 72 is also connected to the suction pump 73. The switching unit 72 selectively connects either the cap section 71a or 71b to the suction pump 73.

[0023] The suction pump 73 is a tube pump or the like and is connected to the switching unit 72 and the waste liquid tank 74. In the maintenance unit 8, when the cap is in the state described above and the switching unit 72 connects the cap part 71a to the suction pump 73, driving the suction pump 73 allows for black suction purging, which discharges the black ink from the inkjet head 4 from the multiple nozzles 10 that form the rightmost nozzle row 9. Also in the maintenance unit 8, when the cap is in the state described above and the switching unit 72 connects the cap part 71b to the suction pump 73, driving the suction pump 73 allows for color suction purging, which discharges the color inks (yellow, cyan, and magenta inks) from the inkjet head 4 from the multiple nozzles 10 that form the leftmost three rows of nozzles 9. The ink discharged by the black and color suction purging is stored in the waste liquid tank 74.

[0024] Furthermore, as shown in Figure 2, electrodes 76 having a rectangular planar shape are arranged inside the cap 71 (inside cap portions 71a and 71b). The electrodes 76 are connected to a high-voltage power supply circuit 77 via a resistor 79. The high-voltage power supply circuit 77 applies a predetermined voltage (for example, about 600V) to the electrodes 76 when performing the test drive described later. Meanwhile, the inkjet head 4 is held at ground potential. This creates a predetermined potential difference between the inkjet head 4 and the electrodes 76. A signal processing circuit 78 is connected to the electrodes 76. The signal processing circuit 78 includes a differentiating circuit and outputs a signal corresponding to the voltage of the electrodes 76. However, the signal output from the signal processing circuit 78 may be a current signal.

[0025] With the capped state described above, and with a voltage applied to the electrode 76 by the high-voltage power supply circuit 77, and without performing the test drive described later, the voltage of the signal output from the signal processing circuit 78 will be the voltage V0 shown in Figures 3(a) and (b).

[0026] Furthermore, in the first embodiment, with the cap in place, a voltage can be applied to the electrode 76 by the high-voltage power supply circuit 77, causing the inkjet head 4 to perform a test drive to eject ink from the nozzle 10 toward the electrode 76.

[0027] When ink is ejected from nozzle 10 by the test drive, the ejected ink is charged. As a result, the charged ink approaches electrode 76, and the potential of electrode 76 changes until the ink lands on electrode 76. After the charged ink lands on electrode 76, the potential of electrode 76 decays and returns to the potential it was at before the ink was ejected.

[0028] At this time, as shown in Figure 3(a), the signal output from the signal processing circuit 78 rises from voltage V0 to voltage V1, which is higher than voltage V0, then falls to voltage V2, which is lower than voltage V0, and then returns to voltage V0 while repeatedly rising and falling with attenuation. As a result, the signal output from the signal processing circuit 78 has a maximum value of voltage V1 and a minimum value of voltage V2.

[0029] On the other hand, if ink is not ejected from the nozzle 10 due to the test drive, the signal output from the signal processing circuit 78 hardly changes from the voltage V0, as shown in Figure 3(b).

[0030] Thus, in the first embodiment, the signal output from the signal processing circuit 78 differs depending on whether or not ink is ejected from the nozzle 10 by the test drive. In the first embodiment, this can be used to determine whether or not the nozzle 10 is a defective nozzle with an abnormality in ink ejection.

[0031] In the first embodiment, a predetermined voltage is applied to the electrode 76, the inkjet head 4 is held at ground potential, and the signal processing circuit 78 is configured to output a signal corresponding to the voltage of the electrode 76. However, the invention is not limited to this configuration. Alternatively, the electrode 76 may be held at ground potential, and a predetermined voltage may be applied to the inkjet head 4 to create a potential difference between the electrode 76 and the inkjet head 4. The signal processing circuit 78 may then be connected to the inkjet head 4 and output a signal corresponding to the voltage of the inkjet head 4.

[0032] <Electrical configuration of the printer> Next, the electrical configuration of printer 1 will be described. As shown in Figure 4, printer 1 is equipped with a control unit 80. The control unit 80 consists of a CPU (Central Processing Unit) 81, ROM (Read Only Memory) 82, RAM (Random Access Memory) 83, flash memory 84 (the "storage unit" of the present invention), ASIC (Application Specific Integrated Circuit) 85, etc. The control unit 80 controls the operation of the carriage motor 86, inkjet head 4, transport motor 87, cap lifting mechanism 88, switching unit 72, suction pump 73, high voltage power supply circuit 77, etc. The control unit 80 also receives signals from the signal processing circuit 78, etc.

[0033] In addition to the configuration described above, the printer 1 also includes a display unit 69 and an operation unit 68. The display unit 69 is, for example, a liquid crystal display provided on the housing of the printer 1. The control unit 80 controls the display unit 69 to display information necessary for the operation of the printer 1 on the display unit 69. The operation unit 68 is, for example, buttons provided on the housing of the printer 1 or a touch panel provided on the display unit 69. The operation unit 68 receives signals based on user operations and transmits the received signals to the control unit 80.

[0034] Furthermore, the control unit 80 may be configured such that only the CPU 81 performs the various processing, or only the ASIC 85 performs the various processing, or the CPU 81 and ASIC 85 perform the various processing in cooperation. Also, the control unit 80 may be configured such that one CPU 81 performs the processing alone, or multiple CPUs 81 share the processing. Furthermore, the control unit 80 may be configured such that one ASIC 85 performs the processing alone, or multiple ASICs 85 share the processing.

[0035] <Processing to initiate suction purging> Next, the processing of the control unit 80 for causing suction purging in printer 1 will be described. While power is supplied to printer 1, such as when the outlet of printer 1 (not shown) is connected to the commercial power supply, the control unit 80 performs processing according to the flow shown in Figure 5(a) to cause suction purging.

[0036] To explain the flow in Figure 5, the control unit 80 determines whether or not predetermined conditions are met (S101). Here, predetermined conditions are conditions under which the number of abnormal nozzles in the inkjet head 4 may change. In the first embodiment, a list of predetermined conditions is stored in the flash memory 84, as shown in Figure 5(b). In S101, it is determined that the predetermined conditions are met if any of these conditions are met.

[0037] The control unit 80 waits until the predetermined conditions are not met (S101: NO). When the predetermined conditions are met, the control unit 80 then performs the inspection process (S102). In the inspection process, the control unit 80 sets the nozzle to the capped state and, with voltage applied to the electrode 76 by the high-voltage power supply circuit 77, causes the inkjet head 4 to perform an inspection drive for each of the multiple nozzles 10. Based on the signal output from the signal processing circuit 78 when the inspection drive is performed, the control unit 80 acquires abnormal nozzle information indicating whether each nozzle 10 is an abnormal nozzle or not.

[0038] Next, the control unit 80 determines, based on the abnormal nozzle information acquired in S102, whether the number of abnormal nozzles Ak (number of black abnormal nozzles) in the rightmost nozzle row 9 is greater than or equal to the threshold Hk (S103). If the number of abnormal nozzles Ak is less than the threshold Hk (S103: NO), the process proceeds to S105. If the number of abnormal nozzles Ak is greater than or equal to the threshold Hk (S103: YES), the control unit 80 performs a black purge process (S104) and then proceeds to S105. In the black purge process, the control unit 80 controls the switching unit 72, the suction pump 73, etc., to perform the black suction purge described above.

[0039] In S105, the control unit 80 determines whether any of the following conditions are met based on the abnormal nozzle information acquired in S102: the number of abnormal nozzles Ay (number of yellow abnormal nozzles) in the second nozzle row 9 from the right is greater than or equal to the threshold Hy; the number of abnormal nozzles Ac (number of cyan abnormal nozzles) in the third nozzle row 9 from the right is greater than or equal to the threshold Hc; the number of abnormal nozzles Am (number of magenta abnormal nozzles) in the leftmost nozzle row 9 is greater than or equal to the threshold Hm; and the total number of abnormal nozzles Ag (=Ay+Ac+Am), which is the sum of the number of abnormal nozzles in the three leftmost nozzle rows 9, is greater than or equal to the threshold Hg (the "third threshold" of the present invention) (the "third purging condition" of the present invention). The thresholds Hy, Hc, and Hm are different values ​​from each other. Also, the threshold Hg is greater than the thresholds Hy, Hc, and Hm, and less than the sum of the thresholds Hy, Hc, and Hm (Hy+Hc+Hm).

[0040] In the first embodiment, an abnormal nozzle in nozzle row 9 corresponding to the first nozzle group corresponds to the "first abnormal nozzle" of the present invention, an abnormal nozzle in nozzle row 9 corresponding to the second nozzle group corresponds to the "second abnormal nozzle" of the present invention, and an abnormal nozzle in nozzle row 9 corresponding to the third nozzle group corresponds to the "third abnormal nozzle" of the present invention. Furthermore, of the number of abnormal nozzles Ay, Ac, and Am, the number of abnormal nozzles in nozzle row 9 corresponding to the first nozzle group corresponds to the "number of first abnormal nozzles" of the present invention, the number of abnormal nozzles in nozzle row 9 corresponding to the second nozzle group corresponds to the "number of second abnormal nozzles" of the present invention, and the number of abnormal nozzles in nozzle row 9 corresponding to the third nozzle group corresponds to the "number of third abnormal nozzles" of the present invention.

[0041] Furthermore, in the first embodiment, among the thresholds Hy, Hc, and Hm, the threshold set for the number of first abnormal nozzles corresponds to the "first threshold" of the present invention, the threshold set for the number of second abnormal nozzles corresponds to the "second threshold" of the present invention, and the threshold set for the number of third abnormal nozzles corresponds to the "fourth threshold" of the present invention. In addition, among the conditions that the number of abnormal nozzles Ay is greater than or equal to the threshold Hy, the number of abnormal nozzles Ac is greater than or equal to the threshold Hc, and the number of abnormal nozzles Am is greater than or equal to the threshold Hm, the condition corresponding to the number of first abnormal nozzles and the first threshold corresponds to the "first purge condition" of the present invention, the condition corresponding to the number of second abnormal nozzles and the second threshold corresponds to the "second purge condition" of the present invention, and the condition corresponding to the number of third abnormal nozzles and the fourth threshold corresponds to the "fourth purge condition" of the present invention.

[0042] If none of the following conditions are met (S105:NO): the number of abnormal nozzles Ay is greater than or equal to the threshold Hy, the number of abnormal nozzles Ac is greater than or equal to the threshold Hc, the number of abnormal nozzles Am is greater than or equal to the threshold Hm, and the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg, the process returns to S101. If at least one of these conditions is met (S105:YES), the control unit 80 performs a color purge process (S106) and then returns to S101. In the color purge process, the control unit 80 controls the switching unit 72, the suction pump 73, etc., to perform the color suction purge described above.

[0043] <Effects> In the first embodiment, color suction purging is used to discharge ink from nozzles that eject yellow, cyan, and magenta inks. In contrast, in the first embodiment, color suction purging is performed when the number of abnormal nozzles Ay is greater than or equal to a threshold Hy, when the number of abnormal nozzles Ac is greater than or equal to a threshold Hc, when the number of abnormal nozzles Am is greater than or equal to a threshold Hm, and when the total number of abnormal nozzles Ag, which is the sum of Ay, Ac, and Am, is greater than or equal to a threshold Hg. As a result, color suction purging is performed when there are many abnormal nozzles Ay, many abnormal nozzles Ac, and many abnormal nozzles Am. Furthermore, color suction purging is also performed when the number of abnormal nozzles Ay, Ac, and Am is not very large, but the total number of abnormal nozzles Ag, which is their sum, is large. This allows for appropriate color suction purging according to the number of abnormal nozzles.

[0044] Furthermore, in the first embodiment, multiple nozzles 10 forming three nozzle rows 9 with different characteristics of the ink ejected from the nozzles 10, such as the color of the ink ejected from the nozzles 10, whether the ink ejected from the nozzles 10 contains pigment or dye, and the viscosity of the ink ejected from the nozzles 10, are covered with the cap portion 71b to perform color suction purging. In contrast, color suction purging can be performed appropriately according to the number of abnormal nozzles.

[0045] Furthermore, in the first embodiment, by setting threshold values ​​Hy, Hc, and Hm to different values, color suction purging can be performed appropriately according to the number of abnormal nozzles in each of the three nozzle rows 9 that eject color ink.

[0046] Furthermore, in the first embodiment, the threshold Hg is greater than the thresholds Hy, Hc, and Hm, and less than their sum (Hy + Hc + Hm). As a result, even when the number of abnormal nozzles Ay is less than the threshold Hy, the number of abnormal nozzles Ac is less than the threshold Hc, and the number of abnormal nozzles Am is less than the threshold Hm, color suction purging is performed when the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg. This allows suction purging to be performed even when the number of abnormal nozzles Ay, Ac, and Am is not very large, but the total number of abnormal nozzles Ag is large.

[0047] [Second Embodiment] Next, a preferred second embodiment of the present invention will be described. The second embodiment also relates to a printer 1 similar to that of the first embodiment. In the second embodiment, while power is supplied to the printer 1, the control unit 80 performs suction purging by processing according to the flow shown in Figure 6.

[0048] To explain the flow in Figure 6, the control unit 80 executes the processes S101 to S103, similar to the first embodiment. If the number of abnormal nozzles Ak is greater than or equal to the threshold Hk (S103: YES), the control unit 80 executes a black purge process (S104) and then proceeds to S105, similar to the first embodiment. On the other hand, if the number of abnormal nozzles Ak is less than the threshold Hk (S103: NO), the control unit 80 determines whether the number of abnormal nozzles Ak is greater than or equal to the threshold Fk (S201). The threshold Fk is a value smaller than the threshold Hk. If the number of abnormal nozzles Ak is less than the threshold Fk (S201: NO), the process proceeds to S105. If the number of abnormal nozzles Ak is greater than or equal to the threshold Fk (S201: YES), the control unit 80 executes a black flashing process (S202) and then proceeds to S105. In the black flushing process, the control unit 80 causes the inkjet head 4 to perform black flushing, which involves ejecting black ink from the abnormal nozzle in the rightmost nozzle row 9.

[0049] Furthermore, in S105, if at least one of the following conditions is met (S105:YES): the number of abnormal nozzles Ay is greater than or equal to the threshold Hy, the number of abnormal nozzles Ac is greater than or equal to the threshold Hc, the number of abnormal nozzles Am is greater than or equal to the threshold Hm, and the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg, the control unit 80 performs a color purge process (S106) as in the first embodiment, and returns to S101.

[0050] On the other hand, if none of these conditions are met (S105: NO), the control unit 80 determines whether any of the following conditions are met: the number of abnormal nozzles Ay is greater than or equal to the threshold Fy, the number of abnormal nozzles Ac is greater than or equal to the threshold Fc, the number of abnormal nozzles Am is greater than or equal to the threshold Fm, and the total number of abnormal nozzles Ag is greater than or equal to the threshold Fg (S203). The threshold Fy is a value smaller than the threshold Hy. The threshold Fc is a value smaller than the threshold Hc. The threshold Fm is a value smaller than the threshold Hm. The threshold Fg is a value smaller than the threshold Hg. In the second embodiment, among the thresholds Fy, Fc, and Fm, the threshold corresponding to the number of abnormal nozzles in the nozzle row 9 corresponding to the first nozzle group corresponds to the "fifth threshold" of the present invention.

[0051] If none of the following conditions are met (S203:NO): the number of abnormal nozzles Ay is greater than or equal to the threshold Fy, the number of abnormal nozzles Ac is greater than or equal to the threshold Fc, the number of abnormal nozzles Am is greater than or equal to the threshold Fm, or the total number of abnormal nozzles Ag is greater than or equal to the threshold Fg, the process returns to S101. If at least one of these conditions is met, the control unit 80 performs a color flashing process (S204) and then returns to S101. In the color flashing process, the control unit 80 causes the inkjet head 4 to perform a color flashing, which involves ejecting color ink from the abnormal nozzles in the nozzle rows 9 of the leftmost three columns.

[0052] <Effects> In the second embodiment, even if it is determined that color suction purging should not be performed, color flushing is performed if any of the following conditions are met: the number of abnormal nozzles Ay is greater than or equal to the threshold Fy; the number of abnormal nozzles Ac is greater than or equal to the threshold Fc; the number of abnormal nozzles Am is greater than or equal to the threshold Fm; or the total number of abnormal nozzles Ag is greater than or equal to the threshold Fg. This allows for the recovery of abnormal nozzles while suppressing ink discharge when the number of abnormal nozzles is small.

[0053] [Third Embodiment] Next, a preferred third embodiment of the present invention will be described. The third embodiment also relates to a printer 1 similar to the first and second embodiments. In the third embodiment, while power is supplied to the printer 1, the control unit 80 performs suction purging by processing according to the flow shown in Figure 7.

[0054] To explain the flow shown in Figure 7, the control unit 80 executes the processes S101 to S103, similar to the first embodiment. If the number of abnormal nozzles Ak is less than the threshold Hk (S103: NO), the process proceeds to S105.

[0055] On the other hand, if the number of abnormal nozzles Ak is greater than or equal to the threshold Hk (S103: YES), the control unit 80 performs a black flashing process similar to that in S202 of the second embodiment (S301). Subsequently, the control unit 80 performs a black inspection process (S302). In the black inspection process, the control unit 80 causes the inkjet head 4 to perform an inspection drive for each of the plurality of nozzles 10 that form the rightmost nozzle row 9, that is, each of the plurality of nozzles 10 that eject black ink, and acquires abnormal nozzle information for these nozzles 10 based on the signals output from the signal processing circuit 78 when the inspection drive is performed.

[0056] Next, the control unit 80 determines again, based on the abnormal nozzle information acquired in S302, whether the number of abnormal nozzles Ak is equal to or greater than the threshold Hk (S303). If the number of abnormal nozzles Ak is less than the threshold Hk (S303: NO), the process proceeds to S105. If the number of abnormal nozzles Ak is equal to or greater than the threshold Hk (S303: YES), the control unit 80 performs a black purge process (S104) and then proceeds to S105.

[0057] Furthermore, if none of the following conditions are met in S105 (S105:NO): the number of abnormal nozzles Ay is greater than or equal to the threshold Hy; the number of abnormal nozzles Ac is greater than or equal to the threshold Hc; the number of abnormal nozzles Am is greater than or equal to the threshold Hm; and the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg, the process returns to S101.

[0058] On the other hand, if at least one of these conditions is met (S105: YES), the control unit 80 performs a color flashing process similar to that in S204 of the second embodiment (S304). Subsequently, the control unit 80 performs a color inspection process (S305). In the color inspection process, the control unit 80 causes the inkjet head 4 to perform an inspection drive for each of the plurality of nozzles 10 that form the nozzle rows 9 in the three left columns, that is, each of the plurality of nozzles 10 that eject color ink, and acquires abnormal nozzle information for these nozzles 10 based on the signals output from the signal processing circuit 78 when the inspection drive is performed.

[0059] Next, the control unit 80 makes the same decision as in S105 based on the abnormal nozzle information acquired in S305 (S306). If none of the following conditions are met (S306: NO): the number of abnormal nozzles Ay is greater than or equal to the threshold Hy, the number of abnormal nozzles Ac is greater than or equal to the threshold Hc, the number of abnormal nozzles Am is greater than or equal to the threshold Hm, and the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg, the process returns to S101. If at least one of these conditions is met (S306: YES), the control unit 80 performs a color purge process (S106) and then returns to S101.

[0060] <Effects> In the third embodiment, color flushing is performed when at least one of the following conditions is met: the number of abnormal nozzles Ay is greater than or equal to the threshold Hy; the number of abnormal nozzles Ac is greater than or equal to the threshold Hc; the number of abnormal nozzles Am is greater than or equal to the threshold Hm; and the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg. After color flushing, color suction purging is performed only if at least one of the above conditions is met. This allows for reduced ink discharge by not performing color suction purging if the abnormal nozzles have been recovered to some extent by color flushing.

[0061] [Fourth Embodiment] Next, a preferred fourth embodiment of the present invention will be described. The fourth embodiment also relates to a printer 1 similar to the first to third embodiments. In the fourth embodiment, while power is supplied to the printer 1, the control unit 80 performs processing according to the flow shown in Figure 8(a).

[0062] To explain the flow in Figure 8(a), the control unit 80 waits until the predetermined time has not arrived (S401: NO), and when the predetermined time arrives (S401: YES), it executes the processes of S102 and S103, as in the first embodiment. In the third embodiment, the condition that the predetermined time has arrived corresponds to the "predetermined condition" of the present invention.

[0063] Then, if the number of abnormal nozzles Ak is less than the threshold Hk (S103:YES), the process proceeds to S105. If the number of abnormal nozzles Ak is equal to or greater than the threshold Hk (S103:YES), the control unit 80 performs a black flashing process (S402), stores the black purge flag information in the flash memory 84 (S403), and then proceeds to S105.

[0064] Furthermore, if none of the following conditions are met in S105 (S105:NO): the number of abnormal nozzles Ay is greater than or equal to the threshold Hy, the number of abnormal nozzles Ac is greater than or equal to the threshold Hc, the number of abnormal nozzles Am is greater than or equal to the threshold Hm, and the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg, the process returns to S101.

[0065] On the other hand, if at least one of these conditions is met (S105: YES), the control unit 80 performs a color flashing process (S404), stores the color purge flag information in the flash memory 84 (S405), and then returns to S101.

[0066] In the fourth embodiment, when the control unit 80 receives a recording command instructing it to record on the recording paper P, it processes according to the flow shown in Figure 8(b). For example, when a user performs an operation on the operation unit 68 to instruct it to record on the recording paper P, the operation unit 68 transmits a recording command, and the control unit 80 receives this recording command.

[0067] To explain the flow in Figure 8(b), the control unit 80 first determines whether or not black purge flag information is stored in the flash memory 84 (S501). If black purge flag information is not stored in the flash memory 84 (S501: NO), the process proceeds to S504. If black purge flag information is stored in the flash memory 84 (S501: YES), the control unit 80 performs a black purge process (S502), erases the black purge flag information stored in the flash memory 84 (S503), and then proceeds to S504.

[0068] In S504, the control unit 80 determines whether or not color purge flag information is stored in the flash memory 84. If color purge flag information is not stored in the flash memory 84 (S504: NO), the process proceeds to S507. If color purge flag information is stored in the flash memory 84 (S504: YES), the control unit 80 performs a color purge process (S505), erases the color purge flag information stored in the flash memory 84 (S506), and then proceeds to S507.

[0069] In S507, the control unit 80 performs recording processing. In the recording processing, the control unit 80 repeatedly performs a recording path in which it controls the carriage motor 86 to move the carriage 2 in the scanning direction and the inkjet head 4 to eject ink from multiple nozzles 10 onto the recording paper P, and a transport operation in which it controls the transport motor 87 to transport the recording paper P to the transport rollers 6 and 7 a predetermined distance, thereby recording onto the recording paper P.

[0070] <Effects> In the fourth embodiment, the inspection drive is performed at a predetermined time, and a decision is made based on the result whether or not to perform a suction purge. Then, when recording is performed on the recording paper P, the suction purge is performed based on the result of the above decision. This prevents noise generation by ensuring that the suction purge is not performed at the predetermined time, even if the predetermined time is set to a time when it is desirable to minimize noise generation, such as late at night or early in the morning.

[0071] Furthermore, if it is determined that a suction purge should be performed at a predetermined time, flushing is performed immediately afterward, and then the purge is performed just before the first recording on the recording sheet P. This prevents noise generation by ensuring that the suction purge is not performed at the predetermined time, even if the predetermined time is set to a time when it is desirable to minimize noise generation, such as late at night or early in the morning. In addition, performing flushing immediately after the above determination allows for some degree of recovery of the abnormal nozzle. On the other hand, since flushing generates less noise than purging, almost no noise is generated even if flushing is performed at the predetermined time. Also, if it is determined that a suction purge should be performed, the suction purge is performed just before the first recording on the recording sheet P, allowing for recovery of the abnormal nozzle before recording on the recording sheet P.

[0072] [Fifth Embodiment] Next, a preferred fifth embodiment of the present invention will be described. The fifth embodiment also relates to a printer 1 similar to the first to fourth embodiments. In the fifth embodiment, while power is supplied to the printer 1, the control unit 80 performs processing according to the flow shown in Figure 9.

[0073] To explain the flow in Figure 9, the control unit 80 first determines whether or not predetermined conditions are met (S601). In the fifth embodiment, as shown in Figure 10(a), the flash memory 84 stores a list of first predetermined conditions and a list of second predetermined conditions as a list of predetermined conditions.

[0074] The first predetermined condition includes the condition that the cumulative number of recorded sheets since the previous suction purge has reached a predetermined value. The first predetermined condition also includes the condition that an abnormality affecting ink ejection has occurred in printer 1. An abnormality affecting ink ejection is, for example, an abnormality such as a jam in the recording paper P. The first predetermined condition also includes the condition that recording has been performed on recording paper P whose length in the transport direction is greater than or equal to a predetermined length. The first predetermined condition also includes the condition that recording has been performed continuously on a predetermined number of recording sheets P or more.

[0075] The second predetermined condition is any condition other than the first predetermined condition. In the fifth embodiment, the first predetermined condition is a condition that makes it more likely than the second predetermined condition that the abnormal nozzle needs to be restored by suction purging.

[0076] In S601, the control unit determines that the predetermined conditions are met if either of the first predetermined conditions or the second predetermined conditions shown in Figure 10(a) is met. The control unit 80 waits until the predetermined conditions are not met (S601: NO), and when the predetermined conditions are met (S601: YES), it sets the threshold values ​​Hk, Hy, Hc, Hm, and Hg (S602).

[0077] In S602, as shown in Figure 10(b), the control unit 80 sets the thresholds Hk, Hy, Hc, Hm, and Hg to Hk1, Hy1, Hc1, Hm1, and Hg1 respectively if the first predetermined condition is met, and sets the thresholds Hk, Hy, Hc, Hm, and Hg to Hk2, Hy2, Hc2, Hm2, and Hg2 respectively if the second predetermined condition is met. Here, Hk1 is smaller than Hk2, Hy1 is smaller than Hy2, Hc1 is smaller than Hc2, Hm1 is smaller than Hm2, and Hg1 is smaller than Hg2. Also, Hg1 is larger than Hk1, Hy1, Hc1, and Hm1, and smaller than the sum of Hy1, Hc1, and Hm1 (Hy1 + Hc1 + Hm1). Furthermore, Hg2 is greater than Hk2, Hy2, Hc2, and Hm2, and less than the sum of Hy2, Hc2, and Hm2 (Hy2 + Hc2 + Hm2).

[0078] Returning to Figure 9, after S602, the control unit 80 performs an inspection process similar to that in S102 of the first embodiment (S603). Subsequently, the control unit 80 determines whether the number of abnormal nozzles Ak is greater than or equal to the threshold Hk based on the result of the inspection process in S603 (S604). If the number of abnormal nozzles Ak is less than the threshold Hk (S604: NO), the process proceeds to S609.

[0079] If the number of abnormal nozzles Ak is greater than or equal to the threshold Hk (S604: YES), the control unit 80 determines whether the first predetermined condition is met (S605). If the first predetermined condition is met (S605: YES), the process proceeds to S607. If the first predetermined condition is not met (the second predetermined condition is met) (S605: NO), the control unit 80 determines whether the purge count Ctk is greater than or equal to a predetermined number Ctk1 (S606). The purge count Ctk is the number of times black suction purging has been performed within a predetermined period T1. The purge count Ctk is reset to 0 when power is first supplied to the printer 1. Furthermore, as will be described later, the purge count Ctk is reset to 0 each time the predetermined period T1 has elapsed. Also, the purge count Ctk increases by 1 each time black suction purging is performed.

[0080] If the number of purges Ctk is equal to or greater than the predetermined number Ctk1 (S606:YES), proceed to S609. If the number of purges Ctk is less than the predetermined number Ctk1 (S606:NO), proceed to S607.

[0081] In S607, the control unit 80 performs a black purging process similar to that in S104 of the first embodiment. After the black purging process in S607 has performed the suction purging of black, the control unit 80 increments the purging count Ctk by 1 (S608) and proceeds to S609.

[0082] In S609, the control unit 80 makes the same determination as in S105 of the first embodiment. If none of the following conditions are met (S609:NO): the number of abnormal nozzles Ay is greater than or equal to the threshold Hy, the number of abnormal nozzles Ac is greater than or equal to the threshold Hc, the number of abnormal nozzles Am is greater than or equal to the threshold Hm, and the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg, the process returns to S601.

[0083] If at least one of these conditions is met (S609: YES), the control unit 80 determines whether the first predetermined condition is met, similar to S605 (S610). If the first predetermined condition is met (S610: YES), the process proceeds to S612. If the first predetermined condition is not met (the second predetermined condition is met) (S610: NO), the control unit 80 determines whether the purge count Ctc is equal to or greater than a predetermined number Ctc1 (S611). The purge count Ctc is the number of color suction purges performed within a predetermined period T1. The purge count Ctc is reset to 0 when power is first supplied to the printer 1. Furthermore, as will be described later, the purge count Ctc is reset to 0 each time a predetermined period T1 has elapsed. Also, the purge count Ctc increases by 1 each time a color suction purge is performed.

[0084] If the number of purges Ctc is equal to or greater than the predetermined number Ctc1 (S611:YES), the process returns to S601. If the number of purges Ctc is less than the predetermined number Ctk1 (S611:NO), the process proceeds to S612.

[0085] In S612, the control unit 80 performs a color purging process similar to that in S106 of the first embodiment. After the color purging process in S612 has performed color suction purging, the control unit 80 increases the purging count Ctc by 1 (S613) and returns to S601.

[0086] In the fifth embodiment, while power is supplied to the printer 1, processing is performed according to the flow shown in Figure 10(c) to reset the purge counts Ctk and Ctc. To explain the flow in Figure 10(c) in detail, the control unit 80 determines whether the elapsed time T is equal to or greater than a predetermined time T1 (S701). The elapsed time T is the time elapsed since it was reset to 0. The elapsed time T is also reset to 0 when power is first supplied to the printer 1.

[0087] The control unit 80 waits while the elapsed time T is less than a predetermined time T1 (S701: NO), and when the elapsed time T becomes equal to or greater than the predetermined time T1 (S701: YES), it resets the purge count Ctk, Ckc to 0 (S702), resets the elapsed time T to 0 (S703), and returns to S701.

[0088] <Effects> In the fifth embodiment, by determining whether or not to perform color suction purging by setting different threshold values ​​Hy, Hc, Hm, and Hg depending on whether or not the first predetermined condition is met and whether or not the second predetermined condition is met, it is possible to determine whether or not to perform color suction purging appropriately according to the state of the printer 1.

[0089] Furthermore, in the fifth embodiment, the first predetermined condition is set to a condition in which there is a higher probability that color suction purging should be performed than the second predetermined condition. When the first predetermined condition is met, the threshold values ​​Hy, Hc, Hm, and Hg are set to smaller values ​​than when the second predetermined condition is met, and a decision is made as to whether or not to perform color suction purging. This makes it easier for the printer 1 to decide to perform color suction purging when there is a high probability that color suction purging should be performed.

[0090] Furthermore, in the fifth embodiment, when the second predetermined condition is met, the likelihood of performing a suction purge is lower than when the first predetermined condition is met. Therefore, in the fifth embodiment, when it is determined that a suction purge should be performed for black and color inks when the second predetermined condition is met, the number of suction purges is limited so that a predetermined number of suction purges Ctk1 and Ctc1 or more are not performed for black and color inks within a predetermined period T1, respectively. This reduces the amount of ink discharged.

[0091] In the fifth embodiment, when the first predetermined condition is met, there is a higher probability that suction purging should be performed than when the second predetermined condition is met. Therefore, in the fifth embodiment, when it is determined that suction purging of black and color should be performed when the first predetermined condition is met, the number of times suction purging of black and color should be performed within the predetermined period T is not limited. This allows the printer 1 to appropriately perform suction purging in situations where there is a high probability that suction purging should be performed.

[0092] [Sixth Embodiment] Next, a preferred sixth embodiment of the present invention will be described. The sixth embodiment, like the first to fifth embodiments, relates to a printer 1.

[0093] However, in the sixth embodiment, it is possible to selectively perform either a weak black purging or a strong black purging as the black suction purging. The strong black purging exerts a stronger force to discharge ink from the nozzle 10 than the weak black purging. For example, the strong black purging requires a longer operating time for the suction pump 73 than the weak black purging. Alternatively, for example, the strong black purging requires a faster rotation speed for the suction pump 73 than the weak black purging. Alternatively, for example, the strong black purging requires a longer operating time for the suction pump 73 and a faster rotation speed for the suction pump 73 than the weak black purging.

[0094] Furthermore, in the sixth embodiment, it is possible to selectively perform either a weak color purge (the "first purge" of the present invention) or a strong color purge (the "second purge" of the present invention) as the color suction purge. The strong color purge has a stronger force for expelling ink from the nozzle 10 than the weak color purge. For example, the strong color purge has a longer operating time for the suction pump 73 than the weak color purge. Alternatively, for example, the strong color purge has a faster rotation speed for the suction pump 73 than the weak color purge. Alternatively, for example, the strong color purge has a longer operating time for the suction pump 73 and a faster rotation speed for the suction pump 73 than the weak color purge.

[0095] In the sixth embodiment, when a user performs an operation to instruct the operation unit 68 (the "signal receiving unit" of the present invention) to perform a suction purge, the operation unit 68 receives a purge instruction signal that instructs the operation to perform a suction purge, and transmits the received purge instruction signal to the control unit 80. When the control unit 80 receives the purge instruction signal, it processes the signal according to the flow shown in Figure 11.

[0096] To explain the flow in Figure 11 in detail, the control unit 80 performs an inspection process similar to that in S102 of the first embodiment (S801). Subsequently, the control unit 80 determines whether the number of abnormal nozzles Ak is greater than or equal to the threshold Hk, similar to that in S103 of the first embodiment (S802).

[0097] If the number of abnormal nozzles Ak is greater than or equal to the threshold Hk (S802: YES), the control unit 80 performs a strong black purge process (S803) and then proceeds to S805. In the strong black purge process, the control unit 80 controls the switching unit 72, the suction pump 73, etc., to perform the strong black purge described above.

[0098] If the number of abnormal nozzles Ak is less than the threshold Hk (S802: NO), the control unit 80 performs a weak black purge process (S804) and then proceeds to S805. In the weak black purge process, the control unit 80 controls the switching unit 72, the suction pump 73, etc. to perform the weak black purge described above.

[0099] In S805, the control unit 80 makes the same determination as in S105 of the first embodiment. If at least one of the following conditions is met (S805:YES): the number of abnormal nozzles Ay is greater than or equal to the threshold Hy, the number of abnormal nozzles Ac is greater than or equal to the threshold Hc, the number of abnormal nozzles Am is greater than or equal to the threshold Hm, and the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg, the control unit 80 executes a strong color purge process (S806) and terminates the process. In the strong color purge process, the control unit 80 controls the switching unit 72, the suction pump 73, etc., to perform the strong color purge described above.

[0100] If none of these conditions are met (S805: NO), the control unit 80 performs a weak color purge process (S807) and terminates the process. In the weak color purge process, the control unit 80 controls the switching unit 72, the suction pump 73, etc., to perform the weak color purge described above.

[0101] <Effects> In the sixth embodiment, it is possible to selectively perform either a weak color purge or a strong color purge, which has a stronger ink discharge force than the weak color purge. However, the strong color purge discharges more ink than the weak color purge. Therefore, in the sixth embodiment, a strong color purge, which has a stronger ink discharge force, is performed when at least one of the following conditions is met: the number of abnormal nozzles Ay is greater than or equal to the threshold Hy; the number of abnormal nozzles Ac is greater than or equal to the threshold Hc; the number of abnormal nozzles Am is greater than or equal to the threshold Hm; and the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg. This ensures that abnormal nozzles are reliably recovered. On the other hand, if none of these conditions are met, a weak color purge, which has a weaker ink discharge force, is performed. This allows for the recovery of abnormal nozzles while suppressing the amount of ink discharged.

[0102] Furthermore, if a black suction purge is not performed when the user instructs a suction purge, simply because the number of abnormal nozzles Ak is less than the threshold Hk, the user may become dissatisfied or mistakenly believe that printer 1 is malfunctioning. Similarly, if a color suction purge is not performed simply because none of the following conditions are met: the number of abnormal nozzles Ay is greater than or equal to the threshold Hy, the number of abnormal nozzles Ac is greater than or equal to the threshold Hc, the number of abnormal nozzles Am is greater than or equal to the threshold Hm, and the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg, the user may become dissatisfied or mistakenly believe that printer 1 is malfunctioning. Therefore, in the sixth embodiment, when a suction purge is instructed by the user, a weak black purge is performed even if the number of abnormal nozzles Ak is less than the threshold Hk. Furthermore, if the user instructs a suction purge, a weak color purge will be performed even if none of the following conditions are met: the number of abnormal nozzles Ay is greater than or equal to the threshold Hy; the number of abnormal nozzles Ac is greater than or equal to the threshold Hc; the number of abnormal nozzles Am is greater than or equal to the threshold Hm; or the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg. This prevents the user from feeling dissatisfied or mistakenly believing that printer 1 is malfunctioning. In addition, a weak black purge and a weak color purge can recover the abnormal nozzles while reducing ink discharge.

[0103] [Seventh Embodiment] Next, a preferred seventh embodiment of the present invention will be described. As shown in Figure 12, the printer 100 according to the seventh embodiment has some modifications to the configuration of the printer 1.

[0104] To explain in more detail, in printer 100, the sub-tank 103 is connected to a single ink cartridge 114 mounted in a cartridge holder 113 via a single tube 115. One color of ink is supplied from this ink cartridge 114 to the sub-tank 103, and this single color of ink is supplied from the sub-tank 103 to the inkjet head 104.

[0105] Furthermore, the printer 100 has two nozzle rows 109 arranged in the scanning direction of the inkjet head 104. The nozzles 10 forming the right nozzle row 109 have a smaller diameter than the nozzles 10 forming the left nozzle row 109. As a result, the ink ejection conditions at the nozzles 10 differ between the right nozzle row 109 and the left nozzle row 109. In the seventh embodiment, one of the two nozzle rows 109 corresponds to the "first nozzle group" of the present invention, and the other nozzle row 109 corresponds to the "second nozzle group" of the present invention.

[0106] Furthermore, in the printer 100, the maintenance unit 108 does not have a switching unit 72 (see Figure 1), and the cap 171 is directly connected to the suction pump 73. Also, when the carriage 2 is in the maintenance position, the cap 171 is raised by the cap lifting mechanism 88 (see Figure 4), and the multiple nozzles 10 that form the two nozzle rows 109 are covered by the cap 171. Then, with the multiple nozzles 10 that form the two nozzle rows 109 covered by the cap 171, a suction purge can be performed to discharge ink from the multiple nozzles 10 that form the two nozzle rows 109 by driving the suction pump 73.

[0107] Furthermore, while power is supplied to the printer 100, the control unit 80 processes according to the flow shown in Figure 13. To explain the flow in Figure 13 in detail, the control unit 80 waits as long as the predetermined conditions are not met (S901: NO), and when the predetermined conditions are met (S901: YES), it performs the same inspection process as in S102 of the first embodiment (S902).

[0108] Next, the control unit 80 determines, based on the results of the inspection process in S902, whether any of the following conditions are met: the number of abnormal nozzles A1 in the right nozzle row 109 is equal to or greater than the threshold H1; the number of abnormal nozzles A2 in the left nozzle row 109 is equal to or greater than the threshold H2; and the total number of abnormal nozzles Ag (=A1+A2), which is the sum of the number of abnormal nozzles in the two nozzle rows 9, is equal to or greater than the threshold Hg (the "third purge condition" of the present invention) (S903).

[0109] Here, thresholds H1 and H2 are different values. Also, threshold Hg is greater than thresholds H1 and H2, and less than the sum of thresholds H1 and H2, which is (H1 + H2). In the seventh embodiment, the abnormal nozzle in nozzle row 109 corresponding to the first nozzle group corresponds to the "first abnormal nozzle" of the present invention, and the abnormal nozzle in nozzle row 109 corresponding to the second nozzle group corresponds to the "second abnormal nozzle" of the present invention. Also, of the numbers of abnormal nozzles A1 and A2, the number of abnormal nozzles corresponding to the first nozzle group corresponds to the "number of first abnormal nozzles" of the present invention, and the number of abnormal nozzles corresponding to the second nozzle group corresponds to the "number of second abnormal nozzles" of the present invention. Also, of thresholds H1 and H2, the threshold corresponding to the number of first abnormal nozzles corresponds to the "first threshold" of the present invention, and the threshold corresponding to the number of second abnormal nozzles corresponds to the "second threshold" of the present invention. Furthermore, among the conditions that the number of abnormal nozzles A1 is equal to or greater than the threshold H1, and the number of abnormal nozzles A2 is equal to or greater than the threshold H2, the conditions corresponding to the number of first abnormal nozzles and the first threshold correspond to the "first purge condition" of the present invention, and the conditions corresponding to the number of second abnormal nozzles and the second threshold correspond to the "second purge condition" of the present invention.

[0110] If none of the following conditions are met (S903:NO): the number of abnormal nozzles A1 is greater than or equal to the threshold H1, the number of abnormal nozzles A2 is greater than or equal to the threshold H2, and the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg, the process returns to S901. If at least one of these conditions is met (S903:YES), the control unit 80 performs a purge process (S904) and then returns to S901. During the purge process, the control unit 80 controls the suction pump 73 and the like to perform the suction purge described above.

[0111] <Effects> In the seventh embodiment, when the diameters of the nozzles 10 differ between two nozzle rows 109, and when suction purging is performed by covering the multiple nozzles 10 forming the two nozzle rows 109 with a cap 171, the suction purging can be performed appropriately according to the number of abnormal nozzles.

[0112] [Differentiation] Although preferred first to seventh embodiments of the present invention have been described above, the present invention is not limited to the first to seventh embodiments, and various modifications are possible as long as they are within the scope of the claims.

[0113] For example, in the first to sixth embodiments, a threshold was set for the number of abnormal nozzles in each of the three nozzle rows 9 covered by the cap portion 71b, and the total number of abnormal nozzles in these three nozzle rows 9 was used as the total number of abnormal nozzles, and a threshold was set for the total number of abnormal nozzles to determine whether or not to perform a suction purge. However, the invention is not limited to this. For example, a threshold may be set for the number of abnormal nozzles in each of two of the three nozzle rows 9 covered by the cap portion 71b. Alternatively, the total number of abnormal nozzles in two of the three nozzle rows 9 covered by the cap portion 71b may be used as the total number of abnormal nozzles, and a threshold may be set for the total number of abnormal nozzles.

[0114] Furthermore, in the first to sixth embodiments, the inkjet head 4 had three nozzle rows 9, each having different ink characteristics ejected from the nozzles 10 and covered by the cap portion 71b, but it is not limited to this. The inkjet head 4 may have two or more nozzle rows 9, each having different ink characteristics ejected from the nozzles 10 and covered by the cap portion 71b. In this case, a threshold may be set for the number of abnormal nozzles in at least two of these two or more nozzle rows 9, and the total number of abnormal nozzles in at least two of these two or four nozzle rows 9 may be used as the total number of abnormal nozzles, and a threshold may be set for the total number of abnormal nozzles to determine whether or not to perform a suction purge.

[0115] Furthermore, in the seventh embodiment, the inkjet head 104 had two nozzle rows 109 with different nozzle diameters and covered by the cap 171, but it is not limited to this. The inkjet head 104 may have three or more nozzle rows 109 with different nozzle diameters and covered by the cap 171. In this case, a threshold may be set for the number of abnormal nozzles in at least two of these three or more nozzle rows 109, and the number of abnormal nozzles in at least two of these three or more nozzle rows 109 may be used as the total number of abnormal nozzles, and a threshold may be set for the total number of abnormal nozzles to determine whether or not to perform a suction purge.

[0116] Furthermore, in the first to sixth embodiments, the characteristics of the ink ejected from the nozzles 10 differed among the nozzle rows 9 due to differences in conditions regarding the color of the ink ejected from the nozzles 10, whether the ink ejected from the nozzles 10 contains pigment or dye, and the viscosity of the ink ejected from the nozzles 10, but this is not limited to this. Only some of these may differ among the nozzle rows 9. Alternatively, other characteristics of the ink ejected from the nozzles 10 may differ among the nozzle rows 9.

[0117] Furthermore, in the first to sixth embodiments, the ink ejection conditions at the nozzles 10 differ between nozzle rows 9 due to differences in the characteristics of the ink ejected from the nozzles 10. Also, in the seventh embodiment, the ink ejection conditions at the nozzles 10 differ between nozzle rows 109 due to differences in the diameters of the nozzles 10. However, this is not limited to these embodiments. Different conditions other than those mentioned above may also result in different ink ejection conditions at the nozzles 10.

[0118] Furthermore, in the first to sixth embodiments, the thresholds Hy, Hc, and Hm were different from each other, but two or three of the thresholds Hy, Hc, and Hm may be the same. Also, in the seventh embodiment, the thresholds H1 and H2 were different, but the thresholds H1 and H2 may be the same.

[0119] Furthermore, in the first to fourth and sixth embodiments, the threshold Hg is greater than any of Hy, Hc, and Hm, and less than their sum (Hy + Hc + Hm). Also, in the fifth embodiment, the threshold Hg1 is greater than any of Hy1, Hc1, and Hm1, and less than their sum (Hy1 + Hc1 + Hm1), and the threshold Hg2 is greater than any of Hy2, Hc2, and Hm2, and less than their sum (Hy2 + Hc2 + Hm2). However, the embodiments are not limited to these.

[0120] For example, in the first to fourth and sixth embodiments, the threshold Hg may be greater than two of the thresholds Hy, Hc, and Hm, and less than the sum of these two thresholds. Similarly, in the fifth embodiment, for example, the threshold Hg1 may be greater than two of the thresholds Hy1, Hc1, and Hm1, and less than the sum of these two thresholds. Also, in the fifth embodiment, for example, the threshold Hg2 may be greater than two of the thresholds Hy2, Hc2, and Hm2, and less than the sum of these two thresholds.

[0121] Furthermore, in the second embodiment, the inkjet head 4 was made to perform color flushing, which discharges color ink from abnormal nozzles in the leftmost three nozzle rows 9, when at least one of the following conditions was met: the number of abnormal nozzles Ay is greater than or equal to the threshold Fy; the number of abnormal nozzles Ac is greater than or equal to the threshold Fc; the number of abnormal nozzles Am is greater than or equal to the threshold Fm; and the total number of abnormal nozzles Ag is greater than or equal to the threshold Fg. However, it is not limited to this. For example, if only one or two of the three conditions—the number of abnormal nozzles Ay is greater than or equal to the threshold Fy; the number of abnormal nozzles Ac is greater than or equal to the threshold Fc; and the number of abnormal nozzles Am is greater than or equal to the threshold Fy—is met, the ink may be discharged only from the abnormal nozzles in the one or two nozzle rows 9 corresponding to these one or two conditions.

[0122] Furthermore, in the third embodiment, in S105, if at least one of the following conditions is met—that the number of abnormal nozzles Ay is greater than or equal to the threshold Hy, that the number of abnormal nozzles Ac is greater than or equal to the threshold Hc, that the number of abnormal nozzles Am is greater than or equal to the threshold Hm, and that the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg—color flushing is performed before the color inspection process is executed. Then, based on the results of the color inspection process, it is decided whether or not to perform color suction purging again. However, this is not limited to this.

[0123] For example, in S105 of the third embodiment, if only one or two of the three conditions are met—that the number of abnormal nozzles Ay is greater than or equal to the threshold Hy, that the number of abnormal nozzles Ac is greater than or equal to the threshold Hc, and that the number of abnormal nozzles Am is greater than or equal to the threshold Hm—then in the color flushing process of S304, flushing may be performed to discharge ink only from the abnormal nozzles in one or two nozzle rows 9 corresponding to the one or two conditions mentioned above, before the color inspection process is executed.

[0124] Furthermore, only some of the following conditions may be used to make a judgment in S105 and S306: the condition that the number of abnormal nozzles Ay is greater than or equal to the threshold Hy; the condition that the number of abnormal nozzles Ac is greater than or equal to the threshold Hc; the condition that the number of abnormal nozzles Am is greater than or equal to the threshold Hm; and the condition that the total number of abnormal nozzles Ag is greater than or equal to the threshold Hg. In this case, for example, if the conditions other than those mentioned above are met in S105, color suction purging may be performed without performing color flushing.

[0125] Furthermore, in the fourth embodiment, when a predetermined time is reached and the number of abnormal nozzles Ak is equal to or greater than the threshold Hk, black flashing is performed immediately thereafter, but this black flashing does not have to be performed. Also, in the fourth embodiment, when a predetermined time is reached and at least one of the following conditions is met: the number of abnormal nozzles Ay is equal to or greater than the threshold Hy, the number of abnormal nozzles Ac is equal to or greater than the threshold Hc, the number of abnormal nozzles Am is equal to or greater than the threshold Hm, and the total number of abnormal nozzles Ag is equal to the threshold Hg, color flashing is performed immediately thereafter, but this color flashing does not have to be performed.

[0126] Furthermore, in the fourth embodiment, when it was determined to perform black and color suction purging based on the results of the inspection process performed at a predetermined time, these suction purging was performed immediately before the first recording on the recording paper P thereafter, but this is not limited to this. For example, when it was determined to perform black and color suction purging based on the results of the inspection process performed at a predetermined time, these suction purging may be performed immediately thereafter.

[0127] Furthermore, in the fifth embodiment, the threshold values ​​Hk, Hy, Hc, Hm, and Hg were all different depending on whether the first predetermined condition was met or the second predetermined condition was met, but this is not limited to this. Only some of the threshold values ​​among Hk, Hy, Hc, Hm, and Hg may be different depending on whether the first predetermined condition was met or the second predetermined condition was met.

[0128] Furthermore, the first predetermined conditions in the fifth embodiment are not limited to the four conditions shown in Figure 10(a). For example, the first predetermined conditions may include only some of the four conditions shown in Figure 10(a). Alternatively, for example, the first predetermined conditions may include conditions other than the four conditions shown in Figure 10(a).

[0129] Furthermore, in the fifth embodiment, when it is determined that suction purging should be performed when the second predetermined condition is met, the number of suction purgings within the predetermined time T1 is limited, and when it is determined that suction purging should be performed when the first predetermined condition is met, the number of suction purgings within the predetermined time T1 is not limited, but this is not limited. For example, when it is determined that suction purging should be performed when either the first or second predetermined condition is met, the number of suction purgings within the predetermined time T1 may be limited. Alternatively, for example, when it is determined that suction purging should be performed when either the first or second predetermined condition is met, the number of suction purgings within the predetermined time T1 may not be limited.

[0130] Furthermore, in the fifth embodiment, the number of suction purges within a predetermined time T1 was limited, but this is not limited to that. For example, the number of suction purges within another predetermined cycle may be limited, such as limiting the number of suction purges during the period from the previous suction purge until a predetermined number of recording sheets P are recorded.

[0131] Furthermore, while the operation unit 68 is configured to receive a purge instruction signal when the user performs an operation to instruct it to perform a suction purge, it is not limited to this configuration. For example, the printer 1 may be connected to an external device such as a PC, and the user may perform an operation to instruct the external device to perform a suction purge. In this case, the connection part of the printer 1 to the external device corresponds to the "signal receiving unit" of the present invention.

[0132] Furthermore, in the sixth embodiment, processing was performed according to the flow shown in Figure 11 when a purge instruction signal from the user was received, but this is not limited to this. Processing may also be performed according to the flow shown in Figure 11 when other predetermined conditions besides receiving a purge instruction signal from the user are met.

[0133] Furthermore, in the first to third, fifth, and seventh embodiments, when predetermined conditions are met, an inspection process is executed to obtain abnormal nozzle information, and a decision is made on whether or not to perform a suction purge based on this abnormal nozzle information. However, this is not limited to this. For example, if the time from the time the last inspection process was executed to the time when the predetermined conditions are met is short, when the predetermined conditions are met, the abnormal nozzle information stored by the previously executed inspection process may be obtained from the flash memory 84, and a decision may be made on whether or not to perform a suction purge based on this abnormal nozzle information.

[0134] Furthermore, although suction purging was performed as the purging method in the above example, the invention is not limited to this. For example, a pressure pump may be provided in the flow path between the ink cartridge 14 and the inkjet head 4 to pressurize the ink in the inkjet head 4. Then, as the purging method, pressurized purging may be performed by driving the pressure pump while multiple nozzles 10 are covered with caps 71, thereby discharging the ink from the inkjet head 4. In this case, the caps 71 and the pressure pump constitute the "purging means" of the present invention.

[0135] Alternatively, both suction purging by driving the suction pump 73 and pressurized purging by driving the aforementioned pressurized pump may be performed. In this case, the maintenance unit 8 and the pressurized pump constitute the "purging means" of the present invention.

[0136] Furthermore, in the above example, the determination of whether the nozzle 10 is an abnormal nozzle was made based on the signal output from the signal processing circuit 78 in response to the change in voltage at the electrode 76 located inside the cap 71 from the nozzle 10 when the inkjet head 4 was driven for inspection, but this is not the only method.

[0137] For example, instead of electrode 76, an electrode extending vertically and facing the space below nozzle 10 when carriage 2 is in the maintenance position may be provided. The signal processing circuit 78 may then output a signal corresponding to the change in voltage of the above electrode when inspection drive is performed with carriage 2 in the maintenance position.

[0138] Alternatively, for example, an optical sensor may be provided that directly detects the ink ejected from the nozzle 10 when the carriage 2 is in a predetermined position such as a maintenance position, and outputs a signal according to the detection result. Based on the signal output from this optical sensor, it may be determined whether or not the nozzle 10 is an abnormal nozzle.

[0139] Alternatively, for example, as described in Japanese Patent Publication No. 4929699, a voltage detection circuit that detects changes in voltage when ink is ejected from a nozzle may be connected to the plate on which the nozzles of the inkjet head are formed, and it may be determined whether a nozzle is an abnormal nozzle based on the signal output from the voltage detection circuit when the operation to eject ink from the nozzle is performed with the carriage moved to the inspection position.

[0140] Alternatively, for example, the substrate of the inkjet head may be equipped with a temperature sensing element, as described in Japanese Patent Publication No. 6231759. Then, after applying a first applied voltage to drive the heater for ink ejection, a second applied voltage may be applied to drive the heater to prevent ink ejection, and a signal may be output based on the temperature change detected by the temperature sensing element from the time the second applied voltage is applied until a predetermined time has elapsed, indicating whether the nozzle 10 is an abnormal nozzle or not.

[0141] Alternatively, the printer may be instructed to record a predetermined test pattern, and the presence or absence of a faulty nozzle may be determined based on the recorded test pattern. In this case, if the printer is a multifunction device with a scanner, the recorded test pattern may be input by having the scanner read the test pattern. Alternatively, the recorded test pattern may be input by having the user operate the control unit 68 or an external device based on the recorded test pattern.

[0142] Furthermore, in the above example, all nozzles 10 of the inkjet head 4 were subjected to a test drive to determine whether or not a nozzle 10 was an abnormal nozzle, but this is not limited to this. For example, only some nozzles 10 of the inkjet head 4, such as every other nozzle 10 in each nozzle row 9, may be subjected to a test drive to determine whether or not a nozzle 10 is an abnormal nozzle. Then, for the remaining nozzles 10, it may be estimated whether or not a nozzle 10 is an abnormal nozzle based on the results of the determination for the aforementioned partial nozzles 10.

[0143] Furthermore, in the above example, we determined whether nozzle 10 is a defective nozzle based on whether or not ink was ejected from nozzle 10, but this is not the only way. For example, we may also determine whether or not nozzle 10 is a defective nozzle based on the direction and speed of ink ejection.

[0144] Furthermore, while the above describes an example of applying the present invention to a printer equipped with a so-called serial head that ejects ink from multiple nozzles while moving in the scanning direction with the carriage, the 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 along the entire length of the recording paper in the scanning direction.

[0145] Furthermore, while the above description has focused on an example of applying the present invention to a printer that ejects ink from a nozzle to record on recording paper P, the invention is not limited to this. It can also be applied to printers that record images on recording media other than recording paper, such as T-shirts, outdoor advertising sheets, cases for mobile devices such as smartphones, cardboard, and resin materials. It can also be applied to liquid dispensing devices that dispense liquids other than ink, such as liquid resin or metal. [Explanation of Symbols]

[0146] 1: Printer 4: Inkjet head 6,7: Conveyor rollers 8: Maintenance Unit 9: Nozzle row 10: Nozzle 69:Operation unit 71: Cap 73: Pump 80: Control Unit 84: Flash memory 100: Printer 104: Inkjet head 108: Maintenance Unit 109: Nozzle row 171: Cap

Claims

1. A head having multiple nozzle groups of different types, each formed by multiple nozzles, wherein the liquid discharge conditions of the nozzles differ, A purging means includes a cap that covers the nozzles forming the group of multiple types of nozzles, and a pump that applies pressure to the liquid in the head, wherein the pump is driven while the nozzles forming the group of multiple types of nozzles are covered with the cap, thereby performing a purge to discharge liquid from the nozzles forming the group of multiple types of nozzles. It comprises a control unit and, The aforementioned group of multiple types of nozzles includes a first nozzle group and a second nozzle group, The control unit, When predetermined conditions are met, abnormal nozzle information is obtained corresponding to the number of first abnormal nozzles, which are abnormal nozzles with abnormal liquid discharge among the nozzles forming the first nozzle group; the number of second abnormal nozzles, which are abnormal nozzles among the nozzles forming the second nozzle group; and the total number of abnormal nozzles, which is the sum of the number of abnormal nozzles in the nozzles forming at least some of the nozzle groups of the multiple types of nozzle groups. Based on the abnormal nozzle information, a decision process is executed to determine whether or not to perform the purging. Based on the determination process that determines to perform the purging, the purging process is executed to cause the purging means to perform the purging. In the aforementioned decision process, The system determines to have the purging means perform the purging when at least one of a plurality of purging conditions is met, including a first purging condition in which the number of first abnormal nozzles is equal to or greater than a first threshold, a second purging condition in which the number of second abnormal nozzles is equal to or greater than a second threshold, and a third purging condition in which the total number of abnormal nozzles is equal to or greater than a third threshold. The liquid dispensing device is characterized in that the aforementioned dispensing conditions include conditions regarding the diameter of the nozzle.

2. A head having multiple nozzle groups of different types, each formed by multiple nozzles, wherein the liquid discharge conditions of the nozzles differ, A purging means includes a cap that covers the nozzles forming the group of multiple types of nozzles, and a pump that applies pressure to the liquid in the head, wherein the pump is driven while the nozzles forming the group of multiple types of nozzles are covered with the cap, thereby performing a purge to discharge liquid from the nozzles forming the group of multiple types of nozzles. It comprises a control unit and, The aforementioned group of multiple types of nozzles includes a first nozzle group and a second nozzle group, The control unit, When predetermined conditions are met, abnormal nozzle information is obtained corresponding to the number of first abnormal nozzles, which are abnormal nozzles with abnormal liquid discharge among the nozzles forming the first nozzle group; the number of second abnormal nozzles, which are abnormal nozzles among the nozzles forming the second nozzle group; and the total number of abnormal nozzles, which is the sum of the number of abnormal nozzles in the nozzles forming at least some of the nozzle groups of the multiple types of nozzle groups. Based on the abnormal nozzle information, a decision process is executed to determine whether or not to perform the purging. Based on the determination process that determines to perform the purging, the purging process is executed to cause the purging means to perform the purging. In the aforementioned decision process, The system determines to have the purging means perform the purging when at least one of a plurality of purging conditions is met, including a first purging condition in which the number of first abnormal nozzles is equal to or greater than a first threshold, a second purging condition in which the number of second abnormal nozzles is equal to or greater than a second threshold, and a third purging condition in which the total number of abnormal nozzles is equal to or greater than a third threshold. The aforementioned discharge conditions include conditions regarding the characteristics of the liquid to be discharged. A liquid dispensing device characterized in that the conditions for the properties of the liquid include conditions for whether the liquid contains a pigment or a dye.

3. A head having multiple nozzle groups of different types, each formed by multiple nozzles, wherein the liquid discharge conditions of the nozzles differ, A purging means includes a cap that covers the nozzles forming the group of multiple types of nozzles, and a pump that applies pressure to the liquid in the head, wherein the pump is driven while the nozzles forming the group of multiple types of nozzles are covered with the cap, thereby performing a purge to discharge liquid from the nozzles forming the group of multiple types of nozzles. It comprises a control unit and, The aforementioned group of multiple types of nozzles includes a first nozzle group and a second nozzle group, The control unit, When predetermined conditions are met, abnormal nozzle information is obtained corresponding to the number of first abnormal nozzles, which are abnormal nozzles with abnormal liquid discharge among the nozzles forming the first nozzle group; the number of second abnormal nozzles, which are abnormal nozzles among the nozzles forming the second nozzle group; and the total number of abnormal nozzles, which is the sum of the number of abnormal nozzles in the nozzles forming at least some of the nozzle groups of the multiple types of nozzle groups. Based on the abnormal nozzle information, a decision process is executed to determine whether or not to perform the purging. Based on the determination process that determines to perform the purging, the purging process is executed to cause the purging means to perform the purging. In the aforementioned decision process, The system determines to have the purging means perform the purging when at least one of a plurality of purging conditions is met, including a first purging condition in which the number of first abnormal nozzles is equal to or greater than a first threshold, a second purging condition in which the number of second abnormal nozzles is equal to or greater than a second threshold, and a third purging condition in which the total number of abnormal nozzles is equal to or greater than a third threshold. A liquid discharge device characterized in that, in the determination process described above, it is determined not to allow the purging means to perform the purging, and if the number of the first abnormal nozzles is greater than or equal to a fifth threshold which is less than the first threshold, and less than the first threshold, it is determined to allow the head to perform flushing to discharge liquid from the first abnormal nozzles.

4. A head having multiple nozzle groups of different types, each formed by multiple nozzles, wherein the liquid discharge conditions of the nozzles differ, A purging means includes a cap that covers the nozzles forming the group of multiple types of nozzles, and a pump that applies pressure to the liquid in the head, wherein the pump is driven while the nozzles forming the group of multiple types of nozzles are covered with the cap, thereby performing a purge to discharge liquid from the nozzles forming the group of multiple types of nozzles. When an inspection drive is performed in the head to discharge liquid from the nozzles forming the group of multiple types of nozzles, a signal transmission unit transmits a signal indicating whether or not the nozzle is an abnormal nozzle with an abnormality in liquid discharge, It comprises a control unit and, The aforementioned group of multiple types of nozzles includes a first nozzle group and a second nozzle group, The control unit, When predetermined conditions are met, abnormal nozzle information is obtained corresponding to the number of first abnormal nozzles which are abnormal nozzles among the nozzles forming the first nozzle group, the number of second abnormal nozzles which are abnormal nozzles among the nozzles forming the second nozzle group, and the total number of abnormal nozzles which is the sum of the number of abnormal nozzles in the nozzles forming at least some of the nozzle groups of the multiple types of nozzle groups, and a decision process is executed to determine whether or not to perform the purging based on the abnormal nozzle information. Based on the determination process that determines to perform the purging, the purging process is executed to cause the purging means to perform the purging. In the aforementioned decision process, The system determines to have the purging means perform the purging when at least one of a plurality of purging conditions is met, including a first purging condition in which the number of first abnormal nozzles is equal to or greater than a first threshold, a second purging condition in which the number of second abnormal nozzles is equal to or greater than a second threshold, and a third purging condition in which the total number of abnormal nozzles is equal to or greater than a third threshold. The aforementioned predetermined conditions include the condition that a predetermined time has arrived. At the predetermined time, the head is made to perform the inspection drive, and the abnormal nozzle information is acquired based on the signal transmitted from the signal transmission unit when the inspection drive is performed, and the determination process is executed. A liquid dispensing device characterized in that, when the judgment process determines that the purging should be performed, the purging means is made to perform the purging immediately before the liquid is first discharged from the nozzles forming the plurality of types of nozzles toward the medium to be discharged.

5. A head having multiple nozzle groups of different types, each formed by multiple nozzles, wherein the liquid discharge conditions of the nozzles differ, A purging means includes a cap that covers the nozzles forming the group of multiple types of nozzles, and a pump that applies pressure to the liquid in the head, wherein the pump is driven while the nozzles forming the group of multiple types of nozzles are covered with the cap, thereby performing a purge to discharge liquid from the nozzles forming the group of multiple types of nozzles. It comprises a control unit and, The aforementioned group of multiple types of nozzles includes a first nozzle group and a second nozzle group, The control unit, When predetermined conditions are met, abnormal nozzle information is obtained corresponding to the number of first abnormal nozzles, which are abnormal nozzles with abnormal liquid discharge among the nozzles forming the first nozzle group; the number of second abnormal nozzles, which are abnormal nozzles among the nozzles forming the second nozzle group; and the total number of abnormal nozzles, which is the sum of the number of abnormal nozzles in the nozzles forming at least some of the nozzle groups of the multiple types of nozzle groups. Based on the abnormal nozzle information, a decision process is executed to determine whether or not to perform the purging. Based on the determination process that determines to perform the purging, the purging process is executed to cause the purging means to perform the purging. In the aforementioned decision process, The system determines to have the purging means perform the purging when at least one of a plurality of purging conditions is met, including a first purging condition in which the number of first abnormal nozzles is equal to or greater than a first threshold, a second purging condition in which the number of second abnormal nozzles is equal to or greater than a second threshold, and a third purging condition in which the total number of abnormal nozzles is equal to or greater than a third threshold. The aforementioned predetermined condition is that either the first predetermined condition or a second predetermined condition, which is different from the first predetermined condition, is satisfied. A liquid dispensing device characterized in that, when the first predetermined condition is met and when the second predetermined condition is met, at least one of the first threshold, the second threshold, and the third threshold is set to a different value, and the judgment process is executed.

6. The aforementioned group of multiple types of nozzles further includes a third nozzle group, The abnormal nozzle information is information corresponding to the number of first abnormal nozzles, the number of second abnormal nozzles, the number of third abnormal nozzles which are abnormal nozzles among the nozzles forming the third nozzle group, and the total number of abnormal nozzles. The control unit, In the aforementioned decision process, A liquid discharge device according to any one of claims 1 to 5, characterized in that it is determined to have the purging means perform the purging when at least one of the plurality of purging conditions, which include the first purging condition, the second purging condition, the third purging condition, and the fourth purging condition that the number of abnormal nozzles is equal to or greater than the fourth threshold, is satisfied.

7. The liquid dispensing apparatus according to any one of claims 1, 3 to 6, characterized in that the dispensing conditions include conditions regarding the characteristics of the liquid to be dispensed.

8. The liquid dispensing device according to claim 7, characterized in that the conditions for the properties of the liquid include conditions for the color of the liquid.

9. The liquid dispensing device according to claim 7, characterized in that the conditions for the properties of the liquid include conditions for the viscosity of the liquid.

10. A liquid dispensing device according to any one of claims 1 to 9, characterized in that the first threshold and the second threshold are different.

11. The liquid dispensing apparatus according to any one of claims 1 to 10, characterized in that the third threshold is less than the sum of the first threshold and the second threshold, and greater than either the first threshold or the second threshold.

12. The control unit, In the aforementioned decision process, If the first purging condition is met, the head is made to perform flushing to discharge liquid from the first abnormal nozzle, and then the abnormal nozzle information is acquired again. The liquid discharge device according to any one of claims 1 to 11, characterized in that it determines to have the purging means perform the purging when the abnormal nozzle information acquired again satisfies at least one of the plurality of purging conditions.

13. The control unit, In the aforementioned decision process, If the first purge condition and the second purge condition are met, the head is made to perform flushing to discharge liquid from at least the first abnormal nozzle and the second abnormal nozzle, and then the abnormal nozzle information is acquired again. The liquid discharge device according to any one of claims 1 to 12, characterized in that it determines to have the purging means perform the purging when the abnormal nozzle information acquired again satisfies at least one of the plurality of purging conditions.

14. The control unit, In the aforementioned decision process, If the third purging condition is met, the head is made to perform flushing, which involves discharging liquid from the abnormal nozzle among the nozzles forming the group of multiple types of nozzles, and then the abnormal nozzle information is acquired again. The liquid discharge device according to any one of claims 1 to 13, characterized in that it determines to have the purging means perform the purging when the abnormal nozzle information acquired again satisfies at least one of the plurality of purging conditions.

15. The control unit, The liquid discharge device according to claim 4, characterized in that, when the judgment process determines to have the purging means perform the purging, immediately thereafter, the head is made to perform flushing, which discharges liquid from the abnormal nozzle among the nozzles forming the plurality of types of nozzle group.

16. The first predetermined condition is, The condition is that the cumulative number of discharged media from which liquid was discharged since the previous purge has reached a predetermined value, The condition is that an abnormality occurs in the liquid dispensing device that affects the dispensing of liquid from at least one of the nozzles forming the group of multiple types of nozzles, The liquid dispensing device has a conveying section that conveys the medium to be dispensed in the conveying direction, and the liquid is dispensed onto the medium to be dispensed, the length of which in the conveying direction is greater than or equal to a predetermined length, The condition includes at least one of the following conditions: that liquid was continuously discharged into a predetermined number or more of the discharge media, The second predetermined condition is a condition other than the first predetermined condition, The control unit, The liquid dispensing device according to claim 5, characterized in that when the first predetermined condition is met, at least one of the first threshold, second threshold, and third threshold is set to a value smaller than the value when the second predetermined condition is met, and the determination process is executed.

17. The control unit, The liquid discharge device according to claim 16, characterized in that, in the determination process executed when the second predetermined condition is met, it is determined to have the purging means perform the purging, the number of times the purging is performed is limited so as not to be performed more than a predetermined number of times within a predetermined cycle.

18. The control unit, The liquid dispensing device according to claim 17, characterized in that, in the determination process executed when the first predetermined condition is met, it is determined to have the purging means perform the purging, the number of times the purging is performed within the predetermined cycle is not limited.

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