Liquid ejection device

Abstract

To suppress an image quality from deteriorating even if an abnormal state occurs.SOLUTION: A control device of a printer executes: abnormality processing in which abnormality flag information showing occurrence of an abnormal state is memorized in a flash memory; first inspection processing in which when a time signal showing a predetermined time is received, detection of abnormal nozzles is performed and the nozzles determined to be abnormal are memorized in the flash memory; and recovery processing in which if the abnormal flag information is not memorized in the flash memory when a recording command signal is received, suction purge is performed when the number of abnormal nozzles memorized in the flash memory is more than a first threshold, and if the abnormal flag information is memorized in the flash memory, the suction purge is performed when the number of abnormal nozzles memorized in the flash memory is more than a second threshold smaller than the first threshold.SELECTED DRAWING: Figure 7

Description

Technical Field

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

Background Art

[0002] Patent Document 1 describes a liquid ejection device that determines whether to clean a nozzle based on preset information when a nozzle from which liquid is not being ejected is detected by a liquid ejection detection unit for detecting whether liquid has been ejected from the nozzle, and the number of nozzles from which liquid is not being ejected has reached a threshold value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the liquid ejection device described in Patent Document 1, cleaning is performed when the number of nozzles from which liquid is not being ejected reaches a threshold value and the conditions preset by the user are satisfied. However, for example, when an abnormal state occurs such as a jam during the conveyance of the medium (the medium to be ejected), the drying of the liquid in the nozzle progresses, and the number of nozzles from which liquid cannot be ejected rapidly increases, even if the number of nozzles from which liquid is not being ejected has not reached the same threshold value as in normal times, it is impossible to determine whether to clean the nozzle. That is, when an abnormal state occurs and the number of nozzles from which liquid is not ejected is less than the normal threshold value but rapidly increases, although the image quality of the image formed by ejecting liquid from the nozzle after the abnormal state occurs is likely to be significantly lower than the image quality before the abnormal state occurs, there is a problem that the deterioration of the image quality cannot be suppressed by cleaning the nozzle.

[0005] Therefore, an object of the present invention is to provide a liquid ejection device capable of suppressing a decrease in image quality even when an abnormal state occurs.

Means for Solving the Problems

[0006] The liquid ejection device of the present invention is In a first aspect, a liquid ejection device, comprising a liquid ejection head having a plurality of nozzles for ejecting a liquid, a signal output unit that outputs a determination signal indicating whether or not the plurality of nozzles are abnormal nozzles having an abnormality in liquid ejection when inspection driving for checking whether or not the plurality of nozzles are abnormal nozzles is performed on the liquid ejection head, a recovery unit that performs a recovery operation for discharging the liquid from the nozzles, an abnormal state output unit that outputs an abnormal signal when an abnormal state occurs in the liquid ejection device, a storage unit, and a control device. And when the control device receives the abnormal signal transmitted from the abnormal state output unit, it performs an abnormal process of storing abnormal flag information indicating that the abnormal state has occurred in the storage unit, and when it receives an inspection signal, it causes the inspection driving to be performed, performs an abnormal nozzle detection for detecting the abnormal nozzles based on the determination signal transmitted from the signal output unit, and stores the nozzles determined to be the abnormal nozzles among the plurality of nozzles in the storage unit as a first inspection process, when the abnormal processing is executed, a second inspection process of performing the abnormal nozzle detection and storing, in the storage unit, a nozzle determined to be the abnormal nozzle among the plurality of nozzles; when receiving a predetermined signal, if the abnormal flag information is not stored in the storage unit, when the number of the abnormal nozzles stored in the storage unit is greater than a first threshold value, it causes the recovery unit to perform the recovery operation, and if the abnormal flag information is stored in the storage unit, when the number of the abnormal nozzles stored in the storage unit is greater than a second threshold value smaller than the first threshold value, it causes the recovery unit to perform the recovery operation as a recovery process. Also, in a second aspect, the liquid ejection device of the present invention is a liquid ejection device including: a liquid ejection head having a plurality of nozzles that eject liquid; a signal output unit that outputs a determination signal indicating whether or not the plurality of nozzles are abnormal nozzles when inspection driving for checking whether or not the plurality of nozzles are abnormal nozzles in liquid ejection is performed on the liquid ejection head; a recovery unit that performs a recovery operation of discharging liquid from the nozzles; an abnormal state output unit that outputs an abnormal signal when an abnormal state occurs in the liquid ejection device; a storage unit; and a control device. The control device, when receiving the abnormal signal transmitted from the abnormal state output unit, performs an abnormal process of storing, in the storage unit, abnormal flag information indicating that the abnormal state has occurred; when receiving an inspection signal, performs the inspection driving, performs abnormal nozzle detection for detecting the abnormal nozzle based on the determination signal transmitted from the signal output unit, and stores, in the storage unit, a nozzle determined to be the abnormal nozzle among the plurality of nozzles as a first inspection process; when receiving a predetermined signal, if the abnormal flag information is not stored in the storage unit, causes the recovery unit to perform the recovery operation when the number of abnormal nozzles stored in the storage unit is greater than a first threshold, and if the abnormal flag information is stored in the storage unit, causes the recovery unit to perform the recovery operation when the number of abnormal nozzles stored in the storage unit is greater than a second threshold smaller than the first threshold as a recovery process; and when the recovery process is performed, if the abnormal flag information is stored in the storage unit, deletes the abnormal flag information from the storage unit. Also, from a third perspective, the liquid ejection device of the present invention is a liquid ejection device including a liquid ejection head having a plurality of nozzles for ejecting liquid, a signal output unit that outputs a determination signal indicating whether or not the plurality of nozzles are abnormal nozzles with an abnormality in liquid ejection when inspection driving for checking whether or not the plurality of nozzles are abnormal nozzles is performed on the liquid ejection head, a recovery means for performing a recovery operation of discharging liquid from the nozzles, an abnormal state output unit that outputs an abnormal signal when an abnormal state occurs in the liquid ejection device, a storage unit, a control device, and a clock unit that outputs a time signal indicating time. And when the control device receives the abnormal signal transmitted from the abnormal state output unit, it performs an abnormality process of storing abnormal flag information indicating that the abnormal state has occurred in the storage unit, and when it receives the time signal indicating that it is a predetermined time, it performs the inspection driving, performs abnormal nozzle detection for detecting the abnormal nozzles based on the determination signal transmitted from the signal output unit, and stores the nozzles determined to be the abnormal nozzles among the plurality of nozzles in the storage unit as a first inspection process, when the abnormality process is executed, it performs the abnormal nozzle detection and stores the nozzles determined to be the abnormal nozzles among the plurality of nozzles in the storage unit as a second inspection process, and when a predetermined signal is received, if the abnormal flag information is not stored in the storage unit, when the number of the abnormal nozzles stored in the storage unit is greater than a first threshold, it causes the recovery means to perform the recovery operation, and if the abnormal flag information is stored in the storage unit, when the number of the abnormal nozzles stored in the storage unit is greater than a second threshold smaller than the first threshold, it causes the recovery means to perform the recovery operation as a recovery process. Further, in a fourth aspect, the liquid ejection device of the present invention is a liquid ejection device including a liquid ejection head having a plurality of nozzles for ejecting a liquid, conveyance means for conveying a medium to be ejected so as to pass through a region facing the plurality of nozzles of the liquid ejection head, a signal output unit that outputs a determination signal indicating whether or not the plurality of nozzles are abnormal nozzles having an abnormality in liquid ejection when causing inspection driving to be performed on the liquid ejection head to check whether or not the plurality of nozzles are abnormal nozzles, recovery means for performing a recovery operation of discharging liquid from the nozzles, an abnormal state output unit that outputs an abnormal signal when an abnormal state occurs in the liquid ejection device, a storage unit, and a control device. When the control device receives the abnormal signal transmitted from the abnormal state output unit, it performs an abnormal process of storing abnormal flag information indicating that the abnormal state has occurred in the storage unit, and when receiving an inspection signal, it causes the inspection driving to be performed and performs abnormal nozzle detection for detecting the abnormal nozzles based on the determination signal transmitted from the signal output unit, and stores the nozzles determined to be the abnormal nozzles among the plurality of nozzles in the storage unit as a first inspection process. When receiving a predetermined signal, if the abnormal flag information is not stored in the storage unit, when the number of the abnormal nozzles stored in the storage unit is greater than a first threshold, it causes the recovery means to perform the recovery operation, and if the abnormal flag information is stored in the storage unit, when the number of the abnormal nozzles stored in the storage unit is greater than a second threshold smaller than the first threshold, it causes the recovery means to perform the recovery operation as a recovery process. The abnormal state output unit outputs the abnormal signal when a conveyance failure occurs in the medium to be ejected conveyed by the conveyance means as the abnormal state. Further, in a fifth aspect, the liquid ejection device of the present invention is a liquid ejection device including a liquid ejection head having a plurality of nozzles for ejecting liquid, a signal output unit that outputs a determination signal indicating whether or not the plurality of nozzles are abnormal nozzles with an abnormality in liquid ejection when causing the liquid ejection head to perform inspection driving for checking whether or not the plurality of nozzles are abnormal nozzles, a recovery unit that performs a recovery operation for discharging liquid from the nozzles, an abnormal state output unit that outputs an abnormal signal when an abnormal state occurs in the liquid ejection device, a storage unit, a control device, and a clock unit that measures time. Then, when receiving the abnormal signal transmitted from the abnormal state output unit, the control device performs an abnormal process of storing, in the storage unit, abnormal flag information indicating that the abnormal state has occurred, and when receiving an inspection signal, causes the inspection driving to be performed, performs abnormal nozzle detection for detecting the abnormal nozzles based on the determination signal transmitted from the signal output unit, and stores, in the storage unit, the nozzles determined to be the abnormal nozzles among the plurality of nozzles as a first inspection process, and when receiving a predetermined signal, if the abnormal flag information is not stored in the storage unit, causes the recovery unit to perform the recovery operation when the number of the abnormal nozzles stored in the storage unit is greater than a first threshold, and if the abnormal flag information is stored in the storage unit, causes the recovery unit to perform the recovery operation when the number of the abnormal nozzles stored in the storage unit is greater than a second threshold smaller than the first threshold as a recovery process, and the abnormal state output unit outputs the abnormal signal when, as the abnormal state, the clock unit has lost time due to the power supply to the clock unit being interrupted.

Effects of the Invention

[0007] According to the liquid ejection device of the present invention, when an abnormal state occurs in the liquid ejection device, a recovery operation is performed when the number of abnormal nozzles is greater than a second threshold value that is smaller than a first threshold value in a normal state where no abnormal state occurs. Therefore, even if the number of abnormal nozzles rapidly increases due to the occurrence of an abnormal state, the recovery operation is likely to be performed, and it is possible to suppress a decrease in image quality even when an abnormal state occurs.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments of the present invention will be described.

[0010] <Overall Configuration of Printer> As shown in FIG. 1, the 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 "liquid ejection head" of the present invention), a platen 5, conveyance rollers 6, 7, a maintenance unit 8, a power outlet 19, and the like.

[0011] The carriage 2 is supported by two guide rails 11, 12 extending in the scanning direction. The carriage 2 is connected to a carriage motor 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. Hereinafter, as shown in FIG. 1, the right side and the left side in the scanning direction will be defined for the description.

[0012] The sub-tank 3 is mounted on the carriage 2. Here, the printer 1 includes a cartridge holder 13, and four ink cartridges 14 are removably mounted on the cartridge holder 13. The four ink cartridges 14 are arranged side by side in the scanning direction, and store black ink (the "first liquid" of the present invention), yellow, cyan, and magenta color inks (the "second liquid" of the present invention) from the one arranged on the right side in the scanning direction. The sub-tank 3 is connected to the four ink cartridges 14 mounted on the cartridge holder 13 via four tubes 15. Thereby, the above four-color inks are supplied from the four ink cartridges 14 to the sub-tank 3.

[0013] The inkjet head 4 is mounted on the carriage 2 and connected to the lower end of the sub-tank 3. The four-color ink is supplied from the sub-tank 3 to the inkjet head 4. Further, the inkjet head 4 discharges ink from a plurality of nozzles 10 formed on the nozzle surface 4a which is the lower surface thereof. More specifically, the plurality of nozzles 10 are arranged in the conveyance direction orthogonal to the scanning direction to form a nozzle row 9, and on the nozzle surface 4a, four rows of nozzle rows 9 are arranged in the scanning direction. From the plurality of nozzles 10, black, yellow, cyan, and magenta inks are discharged from those constituting the nozzle row 9 on the right side in the scanning direction.

[0014] The platen 5 is disposed below the inkjet head 4 and faces the plurality of nozzles 10. The platen 5 extends over the entire length of the recording paper P (the "medium to be discharged" of the present invention) in the scanning direction and supports the recording paper P from below. The conveyance roller 6 is disposed upstream of the inkjet head 4 and the platen 5 in the conveyance direction. The conveyance roller 7 is disposed downstream of the inkjet head 4 and the platen 5 in the conveyance direction. The conveyance rollers 6 and 7 are connected to a conveyance motor 87 (see FIG. 4) via gears (not shown). When the conveyance motor 87 is driven, the conveyance rollers 6 and 7 rotate, and the recording paper P is conveyed in the conveyance direction. In the present embodiment, the combination of the conveyance rollers 6 and 7 and the conveyance motor 87 corresponds to the "conveyance means" of the present invention. And this conveyance means conveys the recording paper P so as to pass through the region facing the plurality of nozzles 10 of the inkjet head 4.

[0015] The maintenance unit 8 includes a cap 71, a suction pump 72, a waste liquid tank 73, and a switching mechanism 74 (see FIG. 4). The cap 71 is disposed on the right side of the platen 5 in the scanning direction. The cap 71 has a first cap 71a and a second cap 71b, and the first cap 71a and the second cap 71b are integrally formed. When the carriage 2 is positioned at the maintenance position on the right side of the platen 5 in the scanning direction, a plurality of nozzles 10 face the cap 71. At this time, the first cap 71a is disposed so as to be opposed to a nozzle row 9 formed by a plurality of nozzles 10 (the "first nozzles" of the present invention) that discharge black ink. The second cap 71b is disposed so as to be opposed to three nozzle rows 9 formed by a plurality of nozzles 10 (the "second nozzles" of the present invention) that discharge color ink.

[0016] Further, the cap 71 is configured to be movable up and down by a cap lifting mechanism 88 (see FIG. 4). When the carriage 2 is positioned at the maintenance position so that the plurality of nozzles 10 face the cap 71, and the cap 71 is lifted from the uncapping position below the cap position to the cap position by the cap lifting mechanism 88, the upper end portion of the cap 71 comes into close contact with the nozzle surface 4a, and the plurality of nozzles 10 are covered by the cap 71. Thereby, the first cap 71a covers all the nozzles 10 that discharge black ink, and the second cap 71b covers all the nozzles 10 that discharge color ink. Note that the cap 71 is not necessarily limited to covering the plurality of nozzles 10 by coming into close contact with the nozzle surface 4a. The cap 71 may cover the plurality of nozzles 10 by coming into close contact with, for example, a frame (not shown) disposed around the nozzle surface 4a of the inkjet head 4.

[0017] The suction pump 72 is a tube pump or the like, and is connected to the cap 71 and the waste liquid tank 73. The switching mechanism 74 is disposed between the suction pump 72 and the cap 71, and is configured to be able to selectively switch the connection between the first cap 71a and the suction pump 72 and the connection between the second cap 71b and the suction pump 72.

[0018] In the maintenance unit 8, as described above, with the plurality of nozzles 10 covered by the cap 71, when the suction pump 72 is driven with the first cap 71a and the suction pump 72 connected by the switching mechanism 74, black ink in the inkjet head 4 is discharged from the plurality of nozzles 10. When the suction pump 72 is driven with the second cap 71b and the suction pump 72 connected, color ink in the inkjet head 4 is discharged from the plurality of nozzles 10, and a so-called suction purge (recovery operation) can be performed. The ink discharged by the suction purge is stored in the waste liquid tank 73.

[0019] Note that the cap 71 may not be divided into the first cap 71a and the second cap 71b, and may be a cap that can cover all the nozzles 10 at once. In this case, the maintenance unit 8 may not have the switching mechanism 74, and a suction purge for discharging ink from all the nozzles 10 may be performed by driving the suction pump 72. Alternatively, for example, the cap 71 may be provided individually for each nozzle row 9, and ink may be discharged from the nozzles 10 individually for each nozzle row 9 in the suction purge.

[0020] Also, as shown in FIG. 2, a detection electrode 76 having a rectangular planar shape is disposed in the cap 71. The detection electrode 76 is connected to a high-voltage power supply circuit 77 via a resistor 79. When performing inspection driving described later, a predetermined positive potential (for example, about 600 V) is applied to the detection electrode 76 by the high-voltage power supply circuit 77. On the other hand, the inkjet head 4 is held at the ground potential. Thereby, a predetermined potential difference is generated between the inkjet head 4 and the detection electrode 76. A determination circuit 78 is connected to the detection electrode 76. The determination circuit 78 compares the potential of the signal output from the detection electrode 76 with a threshold value Vt and outputs a signal according to the result.

[0021] More specifically, since there is a potential difference between the inkjet head 4 and the detection electrode 76, the ink ejected from the nozzle 10 is charged. When the carriage 2 is positioned at the maintenance position and ink is ejected from the nozzle 10 toward the detection electrode 76, as shown in Fig. 3(a), the charged ink approaches the detection electrode 76, and until the ink lands on the detection electrode 76, the potential of the detection electrode 76 decreases from the potential Va when the inkjet head 4 is not driven and reaches a potential Vb lower than the potential Va. Then, after the charged ink lands on the detection electrode 76, the potential of the detection electrode 76 gradually rises and returns to the potential Va. That is, during the driving period Td of the inkjet head 4, the potential of the detection electrode 76 changes.

[0022] On the other hand, when no ink is ejected from the nozzle 10, as shown in Fig. 3(b), during the driving period Td of the inkjet head 4, the potential of the detection electrode 76 hardly changes from the potential Va. Therefore, a threshold value Vt (Va < Vt < Vb) is set in the determination circuit 78 to distinguish between these cases. Then, the determination circuit 78 compares the maximum potential of the voltage signal output from the detection electrode 76 with the threshold value Vt during the driving period Td of the inkjet head 4 and outputs a determination signal according to the determination result. In this embodiment, the combination of the detection electrode 76, the high-voltage power supply circuit 77, the resistor 79, and the determination circuit 78 corresponds to the "signal output unit" of the present invention. And this signal output unit outputs a determination signal according to whether the nozzle 10 is an abnormal nozzle from which no ink is ejected.

[0023] Also, here, the high-voltage power supply circuit 77 applies a positive potential to the detection electrode 76. However, the high-voltage power supply circuit 77 may apply a negative potential (e.g., about -600 V) to the detection electrode 76. In this case, contrary to the above, when the carriage 2 is positioned at the maintenance position and ink is ejected from the nozzle 10 toward the detection electrode 76, the charged ink approaches the detection electrode 76, and the potential of the detection electrode 76 rises from the potential Va until the ink lands on the detection electrode 76. After the ink lands on the detection electrode 76, the potential of the detection electrode 76 gradually decreases and returns to the potential Va.

[0024] The power socket 19 can be connected to a commercial power supply (not shown). And in the printer 1, when the power socket 19 is inserted and connected to the commercial power supply, power is supplied from the power socket 19. When the power socket 19 is unplugged, the supply of power from the power socket 19 is interrupted.

[0025] <Electrical Configuration of the Printer> Next, the electrical configuration of the printer 1 will be described. As shown in FIG. 4, the printer 1 has a control device 80. The control device 80 includes a CPU (Central Processing Unit) 81, a ROM (Read Only Memory) 82, a RAM (Random Access Memory) 83, a flash memory 84, an ASIC (Application Specific Integrated Circuit) 85, and the like. The control device 80 controls the operations of the carriage motor 86, the inkjet head 4, the conveyance motor 87, the cap lifting mechanism 88, the suction pump 72, the switching mechanism 74, the high-voltage power supply circuit 77, the driver IC 89, etc. In this embodiment, the control device 80 controls the inkjet head 4 by controlling the driver IC 89. Also, a determination signal is input to the control device 80 from the determination circuit 78.

[0026] In addition to the configuration described above, the printer 1 further includes a display unit 69, an operation unit 70, a clock unit 68, a battery 66, a power supply detection circuit 90, an encoder 91, a position sensor 92, and a paper sensor 93. The display unit 69 is, for example, a liquid crystal display provided on the housing of the printer 1. The control device 80 controls the display unit 69 to display information necessary for the operation of the printer 1. The operation unit 70 is, for example, buttons provided on the housing of the printer 1, a touch panel provided on the display unit 69, and the like. By operating the operation unit 70 by the user, a signal can be input to the control device 80.

[0027] Also, in the present embodiment, the operation unit 70 includes a power switch (not shown). By operating the power switch by the user, the power of the printer 1 can be switched between on and off. Further, when the user operates the power switch of the operation unit 70 to turn on the power of the printer 1, a power-on signal indicating that the power of the printer 1 has been turned on is output from the operation unit 70, and the control device 80 receives this power-on signal.

[0028] The clock unit 68 measures time, and the control device 80 receives a time signal (the "inspection signal" of the present invention) indicating the time from the clock unit 68. The battery 66 is connected to at least the control device 80 and the clock unit 68. In the printer 1, when power is supplied from the outlet 19, the battery 67 is charged. Further, in the printer 1, when the outlet 19 is unplugged and the power supply from the outlet 19 is interrupted, if the battery 67 is not out of power, power is supplied from the battery 67 to at least the control device 80 and the clock unit 68.

[0029] The power supply detection circuit 90 is connected to the battery 67 and the control device 80, and when the charge amount of the battery 67 reaches the lower limit value determined to be out of battery, it outputs an abnormal signal indicating an abnormal state to the control device 80. When the battery 67 runs out of power, the power supply to the clock unit 68 is interrupted, and the clock unit 68 loses track of the time. For this reason, the first inspection process and the like described later cannot be executed normally, and an abnormal state may occur in which the ink in the nozzle 10 dries out and ejection abnormalities (a state in which ink is not ejected normally from the nozzle 10) occur. As a modification, when the printer 1 is not provided with the battery 67, the power supply detection circuit 90 may be provided in the path through which power is supplied from the power outlet 19 to the control device 80. Then, the power supply detection circuit 90 may output an abnormal signal to the control device 80 when the power supply from the power outlet 19 to the control device 80 is interrupted.

[0030] The encoder 91 detects the position of the carriage 2 in the scanning direction and outputs a signal indicating the position of the carriage 2 to the control device 80. The position sensor 92 is a sensor that detects the position of the cap 71, and when the cap 71 is in the cap position, it outputs a signal indicating that fact to the control device 80.

[0031] For example, when the printer 1 is turned on (at the time of "power-on" in the present invention), the control device 80 receives a power-on signal. At this time, normally, the position of the carriage 2 indicated by the signal from the encoder 91 is the maintenance position, and the position of the cap 71 indicated by the signal from the position sensor 92 is the cap position. However, before turning on the power of the printer 1 this time, due to some reason (such as a power outage or unplugging the power outlet 19), the inkjet head 4 may not be capped by the cap 71 and the power may be turned off. In this case, the ink in the plurality of nozzles 10 may dry out and ejection abnormalities may occur. When such an abnormal state occurs in the printer 1, the signals received by the control device 80 from the encoder 91 and the position sensor 92 become signals other than those indicating the maintenance position and the cap position, and these signals (the "abnormal signals" in the present invention) indicate the abnormal state.

[0032] The paper sensor 93 is disposed between the inkjet head 4 and the conveyance roller 6 in the conveyance direction, detects the recording paper P conveyed by the conveyance roller 6, and outputs a signal indicating that the recording paper P has been conveyed to the control device 80.

[0033] For example, if the paper sensor 93 does not detect the recording paper P even after a predetermined time has elapsed since the conveyance of the recording paper P started during recording, a conveyance failure such as a jam has occurred in the recording paper P. In this case, ink drying may occur in the plurality of nozzles 10, or the recording paper P may come into contact with the nozzles 10 and be damaged, resulting in abnormal ink ejection from the nozzles 10. When such an abnormal state occurs in the printer 1, the signal received by the control device 80 from the paper sensor 93 (the signal after a predetermined time has elapsed since the conveyance of the recording paper P started) becomes a signal other than the signal indicating the detection of the recording paper P, and this signal (the "abnormal signal" in the present invention) indicates the abnormal state. The power supply detection circuit 90, the encoder 91, the position sensor 92, and the paper sensor 93 in the present embodiment correspond to the "abnormal state output unit" of the present invention.

[0034] Note that the control device 80 may be configured such that only the CPU 81 performs various processes, or only the ASIC 85 performs various processes, or the CPU 81 and the ASIC 85 cooperate to perform various processes. Also, the control device 80 may be configured such that one CPU 81 performs processing alone, or a plurality of CPUs 81 perform processing in a shared manner. Further, the control device 80 may be configured such that one ASIC 85 performs processing alone, or a plurality of ASICs 85 perform processing in a shared manner.

[0035] <When detecting an abnormal state> Next, in the printer 1, the control by the control device 80 indicating the operation at the time of detecting whether an abnormal state has occurred will be described. In the printer 1, at the time of the above detection, the control device 80 performs processing along the flow of FIG. 5. Here, the flow of FIG. 5 continues while power is being supplied from the outlet or the battery 66 to the control device 80 and the clock unit 68.

[0036] Explaining the flow of FIG. 5 in more detail, the control device 80 determines whether an abnormal signal has been received (S101). That is, it is determined whether a signal indicating an abnormal state and showing an abnormal signal is output from the power supply detection circuit 90, the encoder 91, the position sensor 92, and the paper sensor 93 to the control device 80. When an abnormal signal is received (S101: YES), the control device 80 stores the abnormal flag information in the flash memory 84 (S102: "abnormal processing" of the present invention). The abnormal flag information is flag information indicating that the above abnormal state has occurred in the printer 1. When an abnormal signal is not received (S101: NO), S101 is repeated.

[0037] Next, the control device 80 executes the second inspection process (S103). In the second inspection process, the control device 80 causes the inkjet head 4 to be arranged at the maintenance position and transmits a drive signal to the driver IC 89 for performing inspection driving to drive the ink to be ejected in order from each of the plurality of nozzles 10. At this time, the control device 80 causes the flash memory 84 to store inspection history information, which is information on the time when the inspection driving was performed, based on the time signal from the clock unit 68. Then, the control device 80 determines whether or not it is an abnormal nozzle based on the determination signal output from the determination circuit 78 for each nozzle 10 during the inspection driving ("abnormal nozzle detection" of the present invention). Then, the control device 80 stores all the nozzles 10 determined to be abnormal nozzles among the plurality of nozzles 10 in the flash memory 84. That is, the information on the nozzle 10 that was the previous abnormal nozzle stored in the flash memory 84 is updated to the information on the nozzle 10 that is the current abnormal nozzle. Thus, the flow of the detection process for the abnormal state ends.

[0038] <Control during standby> Subsequently, control by the control device 80 during standby in the printer 1 will be described. In the printer 1, during the above standby, the control device 80 performs processing according to the flow of FIG. 6. Here, the flow of FIG. 6 continues while power is being supplied from the power outlet or the battery 66 to the control device 80 and the clock unit 68.

[0039] Explaining the flow of FIG. 6 in more detail, the control device 80 determines whether or not the time signal received from the clock unit 68 indicates a predetermined time (S201). If the time signal received from the clock unit 68 does not indicate a predetermined time (S201: NO), S201 is repeated. The predetermined time in the present embodiment is set in the early morning such as AM6:00, but is not particularly limited.

[0040] On the other hand, when the time signal received from the clock unit 68 (the "inspection signal" of the present invention) indicates that it is a predetermined time (S201: YES), the control device 80 executes the first inspection process (S202). The first inspection process is the same as the second inspection process, except for the execution timing. That is, the control device 80 stores inspection history information, which is information on the time when the inspection drive was performed, in the flash memory 84 based on the time signal from the clock unit 68. Then, the control device 80 determines whether or not it is an abnormal nozzle based on the determination signal output from the determination circuit 78 for each nozzle 10 during the inspection drive ("abnormal nozzle detection" of the present invention). Then, the control device 80 stores all the nozzles 10 determined to be abnormal nozzles among the plurality of nozzles 10 in the flash memory 84. That is, the information on the nozzle 10 that was the previous abnormal nozzle stored in the flash memory 84 is updated to the information on the nozzle 10 that is the current abnormal nozzle. Thus, the standby flow ends.

[0041] As a modification of the control flow during standby, after the above-described first inspection process, flushing for discharging ink from the nozzle 10 determined to be an abnormal nozzle and stored in the flash memory 84 may be performed. Then, the first inspection process may be executed again. By doing so, it becomes possible to recover the nozzle 10 that became an abnormal nozzle due to the ink in the nozzle 10 becoming slightly thickened and then execute the first inspection process again.

[0042] <Control during recording> Subsequently, the control when recording on the recording paper P in the printer 1 will be described. In the printer 1, when the control device 80 receives a recording command signal (the "discharge instruction signal: predetermined signal" of the present invention) instructing to perform recording on the recording paper P, the control device 80 performs processing along the flow of FIG. 7. The recording command signal is a signal instructing to perform recording on the recording paper P in the printer 1 and is transmitted from an external device or the like to the control device 80.

[0043] Explaining the flow of FIG. 7 in more detail, the control device 80 first determines whether it has received a recording command signal (S301). If it has not received the recording command signal (S301: NO), S301 is repeated. If it has received the recording command signal (S301: YES), the control device 80 determines whether abnormal flag information is stored in the flash memory 84 (S302).

[0044] If abnormal flag information is not stored in the flash memory 84 (S302: NO), the control device 80 determines whether the number of abnormal nozzles stored in the flash memory 84 is equal to or less than a first threshold value (S303). The first threshold value here is a threshold value for executing a recovery process immediately before the decrease in image quality becomes noticeable when the number of abnormal nozzles gradually increases during a long period while the printer 1 is used normally without the above abnormal state occurring and the image quality decreases. Further, the first threshold value has a value (for example, 20) for the number of abnormal nozzles related to the nozzle 10 that discharges black ink and a value (for example, 60) for the number of abnormal nozzles related to the nozzle 10 that discharges color ink individually. Note that the value (for example, 60) for the number of abnormal nozzles related to the nozzle that discharges color ink is the sum of the value (for example, 20) for the number of abnormal nozzles related to the nozzle 10 that discharges yellow ink, the value (for example, 20) for the number of abnormal nozzles related to the nozzle 10 that discharges cyan ink, and the value (for example, 20) for the number of abnormal nozzles related to the nozzle 10 that discharges magenta ink. Thereby, it becomes possible to determine whether either the number of abnormal nozzles related to the nozzle 10 that discharges black ink or the number of abnormal nozzles related to the nozzle 10 that discharges color ink exceeds the individual value of the first threshold value.

[0045] When abnormal flag information is stored in the flash memory 84 (S302: YES), the control device 80 determines whether the number of abnormal nozzles stored in the flash memory 84 is equal to or less than a second threshold value (S304). The second threshold value mentioned here is a threshold value for executing a recovery process immediately before the deterioration of the image quality becomes noticeable due to the sudden increase in the number of abnormal nozzles in a short period due to the occurrence of the above abnormal state. Also, similar to the first threshold value, the second threshold value also has a value (for example, 10) for the number of abnormal nozzles related to the nozzle 10 that discharges black ink and a value (for example, 30) for the number of abnormal nozzles related to the nozzle 10 that discharges color ink, respectively. The value of the second threshold value for the number of abnormal nozzles related to the nozzle 10 that discharges black ink is smaller than the value of the first threshold value for the number of abnormal nozzles related to the nozzle 10 that discharges black ink. Also, the value of the second threshold value for the number of abnormal nozzles related to the nozzle 10 that discharges color ink is smaller than the value of the first threshold value for the number of abnormal nozzles related to the nozzle 10 that discharges color ink. Note that the value (for example, 30) for the number of abnormal nozzles related to the nozzle that discharges color ink is the total number obtained by adding the value (for example, 10) for the number of abnormal nozzles related to the nozzle 10 that discharges yellow ink, the value (for example, 10) for the number of abnormal nozzles related to the nozzle 10 that discharges cyan ink, and the value (for example, 10) for the number of abnormal nozzles related to the nozzle 10 that discharges magenta ink. Thereby, it becomes possible to determine whether either the number of abnormal nozzles related to the nozzle 10 that discharges black ink or the number of abnormal nozzles related to the nozzle 10 that discharges color ink exceeds the individual value of the second threshold value.

[0046] In S303, when at least either the number of abnormal nozzles related to the nozzles 10 that discharge black ink or the number of abnormal nozzles related to the nozzles 10 that discharge color ink exceeds the corresponding individual value of the first threshold (S303: NO), the control device 80 executes a recovery process (S305). Also, in S304, when at least either the number of abnormal nozzles related to the nozzles 10 that discharge black ink or the number of abnormal nozzles related to the nozzles 10 that discharge color ink exceeds the corresponding individual value of the second threshold (S304: NO), the control device 80 executes a recovery process (S305).

[0047] In the recovery process in this embodiment, the control device 80 causes a suction purge to be performed. At this time, in S303 and S304, when only the number of abnormal nozzles related to the nozzles 10 that discharge black ink among the number of abnormal nozzles related to the nozzles 10 that discharge black ink and the number of abnormal nozzles related to the nozzles 10 that discharge color ink exceeds the corresponding individual value of the first threshold, the control device 80 drives the suction pump 72 with the first cap 71a and the suction pump 72 connected, and discharges the black ink in the inkjet head 4 from the plurality of nozzles 10. On the other hand, when only the number of abnormal nozzles related to the nozzles 10 that discharge color ink exceeds the corresponding individual value of the first threshold, the control device 80 drives the suction pump 72 with the second cap 71b and the suction pump 72 connected, and discharges the black ink in the inkjet head 4 from the plurality of nozzles 10. Also, when both the number of abnormal nozzles related to the nozzles 10 that discharge black ink and the number of abnormal nozzles related to the nozzles 10 that discharge color ink exceed the corresponding individual value of the first threshold, the control device 80 sequentially switches the connection of the first cap 71a and the second cap 71b to the suction pump 72, and discharges ink from all the nozzles.

[0048] After S305, when both the number of abnormal nozzles related to nozzle 10 that discharges black ink and the number of abnormal nozzles related to nozzle 10 that discharges color ink in S303 are equal to or less than the corresponding individual values of the first threshold (S303: YES), and when both the number of abnormal nozzles related to nozzle 10 that discharges black ink and the number of abnormal nozzles related to nozzle 10 that discharges color ink in S304 are equal to or less than the corresponding individual values of the second threshold (S304: YES), if the control device 80 stores abnormal flag information in the flash memory 84, the control device 80 erases the abnormal flag information (S306).

[0049] Next, the control device 80 executes printing processing (S307). That is, the control device 80 controls the conveyance motor 87 based on the recording command signal to convey the recording paper P to the conveyance rollers 6 and 7 until the area where an image is to be recorded in the first recording path of the recording paper P faces the plurality of nozzles 10 of the inkjet head 4. Then, the control device 80 controls the carriage motor 86 to move the carriage 2 in the scanning direction, and controls the driver IC 89 to drive a plurality of drive elements to cause the inkjet head 4 to perform a recording pass in which ink is discharged from the plurality of nozzles 10 toward the recording paper P.

[0050] After that, if the recording on one sheet of recording paper P is not completed, the control device 80 controls the conveyance motor 87 to convey the recording paper P by a predetermined distance by the conveyance rollers 6 and 7, and repeatedly performs the operation of causing the recording pass again until the recording on one sheet of recording paper P is completed. When the recording of an image on one sheet of recording paper P is completed, the control device 80 controls the conveyance motor 87 to discharge the recording paper P on which the recording is completed by the conveyance rollers 6 and 7. In this way, the flow during recording ends.

[0051] As described above, according to the printer 1 of the present embodiment, when an abnormal state occurs in the printer 1, when the number of abnormal nozzles is greater than a second threshold value that is smaller than a first threshold value in a normal state where no abnormal state occurs (S304: NO), the recovery process of S305 is performed. For this reason, even if the number of abnormal nozzles rapidly increases due to the occurrence of an abnormal state, the recovery process is likely to be performed, and it is possible to suppress a deterioration in image quality even when an abnormal state occurs.

[0052] Further, when the control device 80 executes S102 (abnormal processing), in S103, the control device 80 executes a second inspection process. After that, when a recording command signal is received in S301, and when the number of abnormal nozzles exceeds the corresponding threshold value in S303 or S304, the control device 80 executes a recovery process in S305. In this way, when an abnormal state occurs, the second inspection process is executed, and it becomes possible to store the nozzles determined to be abnormal nozzles in the flash memory 84. Then, when the number of abnormal nozzles stored in the flash memory 84 is greater than the second threshold value, it becomes possible to cause the recovery process to be performed.

[0053] Further, if the number of abnormal nozzles exceeds the corresponding value of the first or second threshold value after the control device 80 receives the recording command signal in S301 and before executing the printing process of S307, the control device 80 executes a recovery process. Thereby, it becomes possible to cause the recovery process to be performed before starting ink ejection onto the recording paper P. For this reason, the image quality is surely improved.

[0054] Further, when the control device 80 stores abnormal flag information after executing the recovery process in S306, the control device 80 deletes the abnormal flag information. As a result, the abnormal flag information is deleted from the flash memory 84 when the recovery process is performed.

[0055] Further, when the control device 80 receives a time signal indicating a predetermined time in S201, the control device 80 executes a first inspection process in S202.

[0056] Also, when the abnormality processing in S102 is executed between the execution of the first inspection process in S202 and the reception of the recording command signal in S301, the control device 80 executes the second inspection process in S103. After that, when the control device 80 receives the recording command signal in S301 and the number of abnormal nozzles exceeds the corresponding threshold value in S303 or S304, the control device 80 executes the recovery process in S305. In this way, when an abnormal state occurs, the second inspection process is executed, and it becomes possible to store the nozzles determined to be abnormal nozzles in the flash memory 84. And when the number of abnormal nozzles stored in the flash memory 84 is larger than the second threshold value, it becomes possible to cause the recovery process to be performed. Also, it becomes possible to execute the second inspection process earlier after the abnormal state occurs.

[0057] Also, the first threshold value and the second threshold value respectively have values for the number of abnormal nozzles related to the nozzles (first nozzles) that eject black ink and values for the number of abnormal nozzles related to the nozzles (second nozzles) that eject color ink. Thereby, when at least either the number of abnormal nozzles related to the nozzles that eject black ink or the number of abnormal nozzles related to the nozzles that eject color ink exceeds the individual values of the first threshold value and the individual values of the second threshold value, the recovery process will be performed.

[0058] Also, the cap 71 has a first cap 71a and a second cap 71b. Thereby, it becomes possible to individually cover the nozzles that eject black ink and the nozzles that eject color ink. As a result, it also becomes possible to perform the recovery process individually.

[0059] Also, even if a predetermined time has elapsed since the conveyance of the recording paper P started during recording (i.e., when a conveyance failure has occurred), the control device 80 recognizes that a signal indicating that the recording paper P is not detected from the paper sensor 93 (abnormal state output unit) is an abnormal signal (abnormal signal) indicating an abnormal state. As a result, when an abnormal state occurs in which a conveyance failure occurs in the recording paper P and many nozzles 10 may progress to abnormal nozzles due to drying of the ink in the nozzles 10, it becomes possible to store the abnormal flag information in the flash memory 84.

[0060] Also, when the charge amount of the battery 67 reaches the lower limit value determined to be out of battery, the power supply detection circuit 90 (abnormal state output unit) outputs an abnormal signal indicating an abnormal state to the control device 80. When the user takes a state of not using for a long time, for example, by unplugging the power outlet 19, the battery 67 runs out of battery and the clock unit 68 loses the time. In such a state, an abnormal state may occur in which many nozzles 10 may progress to abnormal nozzles due to drying of the ink in the nozzles 10, and when such an abnormal state occurs, it becomes possible to store the abnormal flag information in the flash memory 84.

[0061] Also, when the printer 1 is turned on, due to some cause (such as a power outage or unplugging the power outlet 19) before turning on the printer 1 this time, the inkjet head 4 may not be capped by the cap 71 and the power may be off. In this case, the signals received by the control device 80 from the encoder 91 and the position sensor 92 become signals other than those indicating the maintenance position and the cap position. The control device 80 recognizes these signals output from the encoder 91 and the position sensor 92 as abnormal signals. As a result, for example, when an abnormal state occurs in which a plurality of nozzles 10 are not covered by the cap 71 when the power is off and many nozzles 10 may progress to abnormal nozzles due to drying of the ink in the nozzles 10, it becomes possible to store the abnormal flag information in the flash memory 84.

[0062] Next, the printer according to the second embodiment will be described below with reference to FIG. 8. The printer in this embodiment is the same as the printer 1 of the first embodiment except that a part of the control during recording is different. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

[0063] <Control during recording> In the printer of this embodiment, the control device 80 performs processing in accordance with the flow of FIG. 8. First, the control device 80 executes S401 and S402, which are the same as S301 and S302 described above.

[0064] If abnormal flag information is stored in the flash memory 84 in S402 (S402: YES), the control device 80 executes a second inspection process, which is the same as S103 described above (S403). Note that when executing the second inspection process in S403, S103 described above may be omitted.

[0065] If abnormal flag information is not stored in the flash memory 84 in S402 (S402: NO), the control device 80 executes S404, which is the same as S303 described above.

[0066] After S403, the control device 80 executes S405, which is the same as S304 described above. After that, the control device 80 executes S406 to S408, which are the same as S305 to S307. Thus, the flow during recording ends.

[0067] According to the printer of this embodiment, in S402, if abnormal flag information is stored in the flash memory 84, the second inspection process in S403 is executed. That is, the control device 80 executes the second inspection process in S403 when the abnormality process in S102 is executed after the first inspection process in S202 and before receiving the recording command signal in S301, and before the recovery process in S406 is executed. After that, in S404 or S405, if the number of abnormal nozzles exceeds the corresponding threshold value, the control device 80 executes the recovery process in S406. In this way, when an abnormal state occurs, it is possible to execute the recovery process according to the number of abnormal nozzles in the second inspection process in S403 from when the recording command signal is received until the recovery process is performed. Note that the same effect can be obtained in the same configuration as the first embodiment.

[0068] In the above-described first embodiment, the second inspection process was performed in S103, but the second inspection process may not be performed. The control device 80, when the abnormality process in S102 is executed between the execution of the first inspection process in S202 and the reception of the recording command signal in S301, and when the number of abnormal nozzles stored in the flash memory 84 by the first inspection process is larger than the second threshold value in S304, executes the recovery process in S305. Thereby, even if an abnormal state occurs after the first inspection process, it becomes possible to determine whether to execute the recovery process using the number of abnormal nozzles by the first inspection process. For this reason, it is not necessary to detect abnormal nozzles again in the second inspection process.

[0069] As described above, the preferred embodiments of the present invention have been explained. However, the present invention is not limited to the above-described embodiments, and various modifications are possible as long as they are within the scope described in the claims. In each of the above embodiments, the control device 80 has a power supply detection circuit 90, an encoder 91, a position sensor 92, and a paper sensor 93 as an abnormal state output unit that outputs an abnormal signal which triggers the execution of abnormal processing. However, it is sufficient to have any one of these. Further, an abnormal button may be provided on the operation unit 70, and the user may press the abnormal button for some reason to output an abnormal signal to the control device 80. Further, a temperature sensor may be provided as an abnormal state output unit in the printer, and when the signal output from the temperature sensor to the control device 80 indicates a temperature exceeding a predetermined temperature range, the signal may be recognized as an abnormal signal.

[0070] Also, each of the first threshold value and the second threshold value may be a value with respect to the total number of abnormal nozzles related to the nozzles 10 that eject black ink and the number of abnormal nozzles related to the nozzles 10 that eject color ink. That is, the value of the first threshold value may be the total value (for example, 80) of the value (for example, 20) with respect to the number of abnormal nozzles related to the nozzles 10 that eject black ink described above and the value (for example, 60) with respect to the number of abnormal nozzles related to the nozzles 10 that eject color ink. The value of the second threshold value may be the total value (for example, 40) of the value (for example, 10) with respect to the number of abnormal nozzles related to the nozzles 10 that eject black ink described above and the value (for example, 30) with respect to the number of abnormal nozzles related to the nozzles 10 that eject color ink. In this case, by providing one cap that covers all the nozzles 10, it becomes possible to execute the recovery process for all the nozzles 10 at once when the number of abnormal nozzles exceeds the threshold value. Note that in this modification, it is not necessary to provide the switching mechanism 74.

[0071] Further, the value with respect to the number of abnormal nozzles related to the nozzles 10 that eject the color inks of the first threshold value and the second threshold value in each of the above-described embodiments may be an individual value for each color. In this case, by providing individual caps that cover a plurality of nozzles 10 for each color, it becomes possible to execute a recovery process on the nozzles 10 that eject the ink of the color for which the number of abnormal nozzles has exceeded the threshold value. That is, it becomes possible to execute the recovery process individually for each color. For this reason, it is not necessary to discharge the ink from the nozzles that eject the ink of the color for which the number of abnormal nozzles does not exceed the threshold value, and the ink consumption amount is reduced. Note that the switching mechanism in this modification example is such that each individual cap and the suction pump 72 can be individually connected.

[0072] Further, in each of the above-described embodiments, the trigger for executing the first inspection process is a time signal indicating a predetermined time, but the first inspection process may be executed by other triggers. Also, in each of the above-described embodiments, the recovery process has been performed after receiving a recording command signal, but it may be executed by the user operating from the operation unit 70, or may be executed each time a predetermined period elapses.

[0073] Also, in each of the above-described embodiments, inspection driving has been performed for all the nozzles 10 of the inkjet head 4, but this is not limiting. For example, inspection driving may be performed only for some of the nozzles 10 of the inkjet head 4, such as every other nozzle 10 in each nozzle row 9, and for the other nozzles 10, it may be estimated whether or not they are abnormal nozzles based on the determination signal output from the determination circuit 78 during the inspection driving.

[0074] Also, in the above-described embodiment, the determination circuit 78 outputs a signal corresponding to whether or not it is an abnormal nozzle according to the potential of the detection electrode 76 when ink is ejected from the nozzle 10 toward the detection electrode 76, but this is not limiting.

[0075] For example, detection electrodes extending in the vertical direction may be arranged, and a signal corresponding to whether the nozzle is abnormal may be output from the determination circuit according to the potential of the detection electrode when ink is ejected so as to pass through the region facing the detection electrode from the nozzle 10. Alternatively, an optical sensor (the "signal output unit" of the present invention) for detecting the ink ejected from the nozzle 10 may be provided, and a signal corresponding to whether the nozzle is abnormal may be output from the optical sensor.

[0076] Alternatively, for example, in the same manner as described in Japanese Patent No. 4929699, a voltage detection circuit (the "signal output unit" of the present invention) for detecting a change in voltage when ink is ejected from the nozzle may be connected to the plate on which the nozzles of the inkjet head are formed, and a signal corresponding to whether the nozzle is abnormal may be output from the voltage detection circuit to the control device 80.

[0077] Alternatively, for example, in the same manner as described in Japanese Patent No. 6231759, the substrate of the inkjet head may be provided with a temperature detection element (the "signal output unit" of the present invention). Then, after applying a first applied voltage to drive the heater for ink ejection, a second applied voltage is applied to drive the heater so that ink is not ejected. Based on the change in the temperature detected by the temperature detection element after applying the second applied voltage until a predetermined time elapses, a signal corresponding to whether the nozzle 10 is an abnormal nozzle may be output.

[0078] Also, in the above examples, the nozzle 10 from which ink is not ejected is determined to be an abnormal nozzle, but this is not limitative. For example, a signal output unit that outputs a signal corresponding to whether the ejection direction of the ink from the nozzle 10 is normal may be provided, and based on the signal from this signal output unit, the nozzle 10 with an abnormal ejection direction may be determined to be an abnormal nozzle.

[0079] Further, a signal output unit may be provided that outputs a signal according to the state of an abnormal nozzle other than the non-discharge of ink, and information regarding the state of the abnormal nozzle may be acquired based on the signal from the signal output unit. The state of the abnormal nozzle refers to, for example, a state in which there is an abnormality in the ink ejection direction, splashing occurs, bubbles are mixed in, or paper dust is clogged in the abnormal nozzle. At this time, as the inspection drive, pressure may be applied to the ink to such an extent that the ink is not ejected from the nozzle 10, and the ink in the vicinity of the nozzle 10 may be vibrated. Then, a signal corresponding to the vibration state of the ink in the vicinity of the nozzle 10 may be output from the signal output unit to acquire information regarding the state of the abnormal nozzle.

[0080] Also, although suction purge is performed in the recovery process, it is not limited to this. For example, a pressure pump may be provided in the middle part of the tube 15 connecting the sub-tank 3 and the ink cartridge 14. Alternatively, a pressure pump connected to the ink cartridge may be provided in the printer. Then, with the plurality of nozzles 10 covered with the cap 71, by driving the pressure pump, the ink in the inkjet head 4 is pressurized to discharge the ink in the inkjet head 4 from the nozzle 10, and a so-called pressure purge may be performed. When performing the pressure purge for each color, a pressure pump may be provided individually for each color, or a switching mechanism for switching the connection to the pressure pump may be provided.

[0081] Furthermore, in the purge process, both suction by the suction pump 72 and pressurization by the pressure pump may be performed.

[0082] Also, it is not limited to recovering the abnormal nozzle by purge. For example, the abnormal nozzle may be recovered by flushing the inkjet head 4 to discharge the ink from the nozzle 10. Alternatively, the abnormal nozzle may be recovered by both purge and flushing. Alternatively, depending on the number of abnormal nozzles, etc., the abnormal nozzle may be recovered by selectively performing either purge or flushing.

[0083] In addition, an example in which the present invention is applied to a printer equipped with a so-called serial head that discharges ink from a plurality of nozzles while moving in the scanning direction together with a carriage has been described, but the present invention is not limited to this. For example, it is also possible to apply the present invention to a printer equipped with a so-called line head that extends over the entire length of a recording paper P in the scanning direction.

[0084] In addition, an example in which the present invention is applied to a printer that discharges ink from nozzles to perform recording on a recording paper P has been described, but the present invention is not limited to this. The present invention can also be applied to printers that record images on recording media other than recording paper, such as T-shirts, sheets for outdoor advertisements, cases of portable terminals such as smartphones, cardboard, and resin members. Further, the present invention can also be applied to liquid discharge devices that discharge liquids other than ink, for example, resins or metals in a liquid state.

Explanation of Reference Numerals

[0085] 1 Printer (Liquid Discharge Device) 4 Inkjet Head (Liquid Discharge Head) 6, 7 Conveyor Rollers 6, 7 (Part of Conveying Means) 8 Maintenance Unit (Recovery Means) 10 Nozzle (First Nozzle, Second Nozzle) 68 Clock Unit 71 Cap 71a First Cap 71b Second Cap 76 Detection Electrode (Part of Signal Output Unit) 77 High-Voltage Power Supply Circuit (Part of Signal Output Unit) 78 Judgment Circuit (Part of Signal Output Unit) 79 Resistor (Part of Signal Output Unit) 80 Control Device 84 Flash Memory (Storage Unit) 87 Conveyor Motor (Part of Conveying Means) 90 Power Supply Detection Circuit (Abnormal State Output Unit) 91 Encoder (Abnormal State Output Unit) 92 Position Sensor (Abnormal State Output Unit) 93 Paper Sensor (Abnormal State Output Unit)

Claims

1. A liquid ejection device, comprising: a liquid ejection head having a plurality of nozzles for ejecting liquid; a signal output unit that outputs a determination signal indicating whether or not the plurality of nozzles are abnormal nozzles having an abnormality in liquid ejection when inspection driving for checking whether or not the plurality of nozzles are abnormal nozzles is performed on the liquid ejection head; recovery means for performing a recovery operation of discharging liquid from the nozzles; an abnormal state output unit that outputs an abnormal signal when an abnormal state occurs in the liquid ejection device; a storage unit; a control device, wherein the control device performs an abnormality process of storing, in the storage unit, abnormality flag information indicating that the abnormal state has occurred when receiving the abnormal signal transmitted from the abnormal state output unit; performs an abnormal nozzle detection process of performing the inspection driving when receiving an inspection signal, detecting the abnormal nozzles based on the determination signal transmitted from the signal output unit, and storing, in the storage unit, the nozzles determined to be the abnormal nozzles among the plurality of nozzles; performs a second inspection process of performing the abnormal nozzle detection when the abnormality process is executed and storing, in the storage unit, the nozzles determined to be the abnormal nozzles among the plurality of nozzles; when receiving a predetermined signal, if the abnormality flag information is not stored in the storage unit, causes the recovery means to perform the recovery operation when the number of the abnormal nozzles stored in the storage unit is greater than a first threshold, and if the abnormality flag information is stored in the storage unit, causes the recovery means to perform the recovery operation when the number of the abnormal nozzles stored in the storage unit is greater than a second threshold smaller than the first threshold. A liquid ejection device characterized by executing a recovery process.

2. The predetermined signal is a discharge instruction signal for instructing the liquid ejection head to eject liquid toward a medium to be ejected from the nozzles, wherein the control device causes the recovery process to be performed between receiving the discharge instruction signal and starting liquid discharge to the medium to be ejected based on the discharge instruction signal. The liquid ejection device according to claim 1.

3. A liquid ejection device, comprising: a liquid ejection head having a plurality of nozzles for ejecting liquid; When causing the liquid ejection head to perform an inspection drive for checking whether or not the plurality of nozzles are abnormal nozzles with abnormal liquid ejection, a signal output unit that outputs a determination signal indicating whether or not the plurality of nozzles are the abnormal nozzles; Recovery means for performing a recovery operation of discharging liquid from the nozzles; An abnormal state output unit that outputs an abnormal signal when an abnormal state occurs in the liquid ejection device; A storage unit; A control device, and comprising: The control device: An abnormality process of storing, in the storage unit, abnormality flag information indicating that the abnormal state has occurred when receiving the abnormal signal transmitted from the abnormal state output unit; When receiving an inspection signal, causing the inspection drive to be performed, performing detection of the abnormal nozzles based on the determination signal transmitted from the signal output unit, and storing, in the storage unit, the nozzles determined to be the abnormal nozzles among the plurality of nozzles; a first inspection process; When receiving a predetermined signal, when the abnormality flag information is not stored in the storage unit, causing the recovery means to perform the recovery operation when the number of the abnormal nozzles stored in the storage unit is greater than a first threshold value, and when the abnormality flag information is stored in the storage unit, causing the recovery means to perform the recovery operation when the number of the abnormal nozzles stored in the storage unit is greater than a second threshold value smaller than the first threshold value; a recovery process; A liquid ejection device, characterized in that when the recovery process is performed, when the abnormality flag information is stored in the storage unit, the abnormality flag information is erased from the storage unit.

4. A liquid ejection device, comprising: A liquid ejection head having a plurality of nozzles for ejecting liquid; When causing the liquid ejection head to perform an inspection drive for checking whether or not the plurality of nozzles are abnormal nozzles with abnormal liquid ejection, a signal output unit that outputs a determination signal indicating whether or not the plurality of nozzles are the abnormal nozzles; Recovery means for performing a recovery operation of discharging liquid from the nozzles; An abnormal state output unit that outputs an abnormal signal when an abnormal state occurs in the liquid ejection device; A storage unit; A control device; A clock unit that outputs a time signal indicating time, and comprising: The control device: An abnormality process of storing, in the storage unit, abnormality flag information indicating that the abnormal state has occurred when receiving the abnormal signal transmitted from the abnormal state output unit; When receiving the time signal indicating a predetermined time, causing the inspection drive to be performed, performing abnormal nozzle detection for detecting an abnormal nozzle based on the determination signal transmitted from the signal output unit, and storing, in the storage unit, the nozzle determined to be the abnormal nozzle among the plurality of nozzles; a first inspection process; When the abnormal process is executed, performing abnormal nozzle detection, and storing, in the storage unit, the nozzle determined to be the abnormal nozzle among the plurality of nozzles; a second inspection process; When a predetermined signal is received, if the abnormal flag information is not stored in the storage unit, when the number of abnormal nozzles stored in the storage unit is greater than a first threshold, causing the recovery means to perform the recovery operation, and if the abnormal flag information is stored in the storage unit, when the number of abnormal nozzles stored in the storage unit is greater than a second threshold smaller than the first threshold, causing the recovery means to perform the recovery operation; a recovery process, characterized in that a liquid discharge device executes the above.

5. The liquid discharge head is provided with a plurality of first nozzles for discharging a first liquid and a plurality of second nozzles for discharging a second liquid different in type from the first liquid; The liquid discharge device according to any one of claims 1 to 4, characterized in that the first threshold and the second threshold are values with respect to the total of the number of abnormal nozzles related to the first nozzles and the number of abnormal nozzles related to the second nozzles.

6. The liquid discharge head is provided with a plurality of first nozzles for discharging a first liquid and a plurality of second nozzles for discharging a second liquid different in type from the first liquid; The liquid discharge device according to any one of claims 1 to 4, characterized in that the first threshold and the second threshold individually have values with respect to the number of abnormal nozzles related to the first nozzles and values with respect to the number of abnormal nozzles related to the second nozzles.

7. The recovery means is provided with a first cap capable of covering the plurality of first nozzles and a second cap capable of covering the plurality of second nozzles. The liquid discharge device according to claim 6, characterized in that it has the above.

8. A liquid discharge device, comprising a liquid discharge head having a plurality of nozzles for discharging liquid and conveying means for conveying a medium to be discharged so as to pass through a region facing the plurality of nozzles of the liquid discharge head. When causing the liquid ejection head to perform inspection driving for checking whether or not the plurality of nozzles are abnormal nozzles with abnormal liquid ejection, a signal output unit that outputs a determination signal indicating whether or not the plurality of nozzles are the abnormal nozzles; Recovery means for performing a recovery operation of discharging liquid from the nozzles; An abnormal state output unit that outputs an abnormal signal when an abnormal state occurs in the liquid ejection device; A storage unit; A control device, and comprising: The control device: When receiving the abnormal signal transmitted from the abnormal state output unit, an abnormal process of storing abnormal flag information indicating that the abnormal state has occurred in the storage unit; When receiving an inspection signal, causing the inspection driving to be performed, performing detection of the abnormal nozzles based on the determination signal transmitted from the signal output unit, and storing the nozzles determined to be the abnormal nozzles among the plurality of nozzles in the storage unit A first inspection process; When receiving a predetermined signal, if the abnormal flag information is not stored in the storage unit, when the number of the abnormal nozzles stored in the storage unit is greater than a first threshold, causing the recovery means to perform the recovery operation, and when the abnormal flag information is stored in the storage unit, when the number of the abnormal nozzles stored in the storage unit is greater than a second threshold smaller than the first threshold, causing the recovery means to perform the recovery operation Recovery process, and execute; The abnormal state output unit outputs the abnormal signal when a conveyance failure occurs in the medium to be ejected conveyed by the conveyance means as the abnormal state. A liquid ejection device characterized by this.

9. A liquid ejection device, comprising: A liquid ejection head having a plurality of nozzles for ejecting liquid; When causing the liquid ejection head to perform inspection driving for checking whether or not the plurality of nozzles are abnormal nozzles with abnormal liquid ejection, a signal output unit that outputs a determination signal indicating whether or not the plurality of nozzles are the abnormal nozzles; Recovery means for performing a recovery operation of discharging liquid from the nozzles; An abnormal state output unit that outputs an abnormal signal when an abnormal state occurs in the liquid ejection device; A storage unit; A control device; A clock unit for measuring time, and comprising: The control device: When receiving the abnormal signal transmitted from the abnormal state output unit, an abnormal process of storing abnormal flag information indicating that the abnormal state has occurred in the storage unit; When receiving the inspection signal, perform abnormal nozzle detection to cause the inspection drive to be performed and detect the abnormal nozzle based on the determination signal transmitted from the signal output unit, and store the nozzle determined to be the abnormal nozzle among the plurality of nozzles in the storage unit as the first inspection process; When receiving a predetermined signal, if the abnormal flag information is not stored in the storage unit, when the number of abnormal nozzles stored in the storage unit is greater than a first threshold, cause the recovery means to perform the recovery operation; if the abnormal flag information is stored in the storage unit, when the number of abnormal nozzles stored in the storage unit is greater than a second threshold smaller than the first threshold, cause the recovery means to perform the recovery operation, and execute the recovery process; The abnormal state output unit outputs the abnormal signal when the clock unit has lost time due to the interruption of power supply to the clock unit as the abnormal state, characterized in that it is a liquid ejection device.

10. The recovery means has a cap capable of covering the plurality of nozzles; The abnormal state output unit outputs the abnormal signal when the plurality of nozzles are not covered by the cap at the time of power-on as the abnormal state, characterized in that it is the liquid ejection device according to any one of claims 1 to 9.

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