Liquid dispensing device

Abstract

To shorten a time taken to start an ejecting operation.SOLUTION: A control device of a printer performs an inspection operation prior to an ejecting operation when performing the ejecting operation in which an ink jet head is caused to eject ink to recording paper from a plurality of nozzles. When it is determined that the number of anomalous nozzles based on a determination signal output from a signal processing circuit by the inspection drive is equal to or larger than a threshold value, recovery processing is performed prior to the ejecting operation. When the recovery processing is performed, the inspection drive is performed after the ejecting operation is finished. When the recovery process is not performed, the inspection drive is not performed after the ejecting operation is finished.SELECTED DRAWING: Figure 7

Description

[Technical field]

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

[0002] Patent document 1 describes an image forming device that performs a head inspection (test drive) to check whether ink is being ejected normally from multiple nozzles, and if a nozzle is abnormal, alternates between cleaning of the print head (recovery operation) and head inspection a predetermined number of times until the abnormal nozzle is repaired, and if the nozzle abnormality is repaired by cleaning, performs a printing process (ejection operation). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-136858 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the image forming device described in Patent Document 1, when there is a nozzle with an abnormality, the print head is cleaned, and then the head inspection is performed again, and the printing process is performed if the nozzle abnormality is resolved, so even if the nozzle abnormality is resolved by performing cleaning, the head inspection is always performed before the printing process. Therefore, after cleaning, it is necessary to wait the time required for the head inspection, which increases the time before the printing process can be started.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a liquid ejection device capable of shortening the time until the start of an ejection operation. [Means for solving the problem]

[0006] According to a first aspect, a liquid ejection device of the present invention includes 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 the liquid ejection head is caused to perform an inspection drive for checking whether or not the plurality of nozzles are abnormal nozzles that are abnormal in ejecting liquid, recovery means that performs a recovery operation to discharge liquid from the nozzles, and a control device. When performing an ejection operation to cause the liquid ejection head to eject liquid from the plurality of nozzles toward an ejection receiving medium, the control device causes the liquid ejection head to perform the inspection drive prior to the ejection operation, and if it is determined in the inspection drive that the number of the abnormal nozzles is equal to or greater than a threshold based on the determination signal output from the signal output unit, causes the recovery means to perform the recovery operation prior to the ejection operation, and if the recovery operation has been performed, causes the inspection drive to be performed after the ejection operation has ended, and if the recovery operation has not been performed, does not cause the inspection drive to be performed after the ejection operation has ended.

[0007] In addition, according to a second aspect, the liquid ejection device of the present invention comprises a liquid ejection head having a plurality of nozzles which eject liquid, a signal output unit which outputs a determination signal which indicates whether or not the plurality of nozzles are abnormal nozzles when the liquid ejection head is driven for inspection to check whether or not the plurality of nozzles are abnormal nozzles having an abnormality in ejecting liquid, recovery means which performs a recovery operation to discharge liquid from the nozzles, and a control device. Then, when the control device performs an ejection operation in which the liquid ejection head ejects liquid from the multiple nozzles toward the ejection medium, it causes the control device to perform the test drive prior to the ejection operation, and if the number of abnormal nozzles is determined to be equal to or greater than a threshold value based on the judgment signal output from the signal output unit during the test drive, it alternately repeats the recovery operation and the test drive until it is determined that the number of abnormal nozzles is less than the threshold value prior to the ejection operation, and when the recovery operation has been performed a predetermined number of times, it causes the ejection operation to be performed, and if the recovery operation is performed between the test drive immediately before the ejection operation and the ejection operation is performed, it causes the test drive to be performed after the ejection operation is completed, and if the recovery operation is not performed between the test drive immediately before the ejection operation and the ejection operation is performed, it does not cause the test drive to be performed after the ejection operation is completed.

[0008] According to a third aspect, a liquid ejection device of the present invention includes a liquid ejection head having a plurality of nozzles that eject liquid, a signal output unit that outputs a determination signal indicating whether the plurality of nozzles are abnormal nozzles or not when the liquid ejection head is caused to perform an inspection drive for checking whether the plurality of nozzles are abnormal nozzles that are abnormal in ejecting liquid, a recovery means that performs a recovery operation to discharge liquid from the nozzles, a clock unit that outputs a time signal indicating the time, a memory unit, and a control device. The control device causes the inspection drive to be performed when it receives the time signal that is a predetermined time output from the clock unit, and when it is determined during the inspection drive that the number of the abnormal nozzles based on the determination signal output from the signal output unit is equal to or greater than a threshold value, stores flag information in the memory unit indicating that the recovery operation needs to be performed, and controls the inspection drive to be performed. for After driving, when an ejection operation is performed to cause the liquid ejection head to eject liquid from the multiple nozzles toward the ejected medium, if the flag information is stored in the memory unit, the recovery means is caused to perform the recovery operation prior to the ejection operation, and if the recovery operation has been performed, the inspection drive is caused to be performed after the ejection operation is completed, and if the recovery operation has not been performed, the inspection drive is not caused to be performed after the ejection operation is completed. Effect of the Invention

[0009] According to a first aspect of the liquid ejection device of the present invention, when a recovery operation is performed, the test drive is not performed before the ejection operation is started, and the test drive is performed after the ejection operation is completed. Therefore, the time until the ejection operation is started is shortened by the amount of the test drive not being performed between the end of the previous recovery operation and the start of the ejection operation. In addition, since the test drive is performed after the ejection operation is completed, it is possible to determine whether the number of abnormal nozzles after the recovery operation is performed is equal to or greater than a threshold value. According to a second aspect of the liquid ejection device of the present invention, when the recovery operation is performed a predetermined number of times, the inspection drive is not performed before the ejection operation is started, and the inspection drive is performed after the ejection operation is completed. Therefore, the time until the ejection operation is started is shortened by the amount of the inspection drive not performed between the end of the previous recovery operation and the start of the ejection operation. In addition, since the inspection drive is performed after the ejection operation is completed, it is possible to determine whether or not the number of abnormal nozzles after the recovery operation is performed is equal to or greater than a threshold value. In addition, since the recovery operation can be repeatedly performed a predetermined number of times before the ejection operation, it is possible to perform the ejection operation with a reduced number of abnormal nozzles. According to a third aspect of the liquid ejection device of the present invention, when a recovery operation is performed, the inspection drive is not performed before the ejection operation is started, and the inspection drive is performed after the ejection operation is completed. Therefore, the time until the ejection operation is started is shortened by the amount of the inspection drive not being performed between the end of the previous recovery operation and the start of the ejection operation. In addition, since the inspection drive is performed after the ejection operation is completed, it is possible to determine whether the number of abnormal nozzles after the recovery operation is performed is equal to or greater than a threshold value. In addition, the inspection drive is performed by receiving a time signal indicating that it is a predetermined time. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram of a printer according to a first embodiment of the present invention. [Diagram 2] 4A to 4C are diagrams for explaining detection electrodes disposed in a cap, and the connection relationship between the detection electrodes and a high-voltage power supply circuit and a signal processing circuit. [Diagram 3] FIG. 4A is a diagram showing a determination signal when ink is ejected from a nozzle, and FIG. 4B is a diagram showing a determination signal when ink is not ejected from a nozzle. [Figure 4] FIG. 2 is a block diagram showing the electrical configuration of the printer. [Diagram 5] 5 is a flowchart showing an operation of the printer when in standby mode. [Figure 6] 8 is a flowchart showing a flow of the first inspection process shown in FIG. 5 and the second inspection process shown in FIG. 7. [Figure 7] 4 is a flowchart showing the operation of the printer during printing. [Figure 8] 10 is a flowchart showing an operation during printing of a printer according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Preferred embodiments of the present invention will now be described.

[0012] <Overall printer configuration> 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 subtank 3, an inkjet head 4 (the "liquid ejection head" of the present invention), a platen 5, transport rollers 6 and 7, a maintenance unit 8, etc.

[0013] 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 (not shown) or the like, and when the carriage motor 86 is driven, the carriage 2 moves in the scanning direction along the guide rails 11, 12. In the following description, the right and left sides of the scanning direction are defined as shown in FIG. 1.

[0014] The subtank 3 is mounted on the carriage 2. Here, the printer 1 includes a cartridge holder 13, in which four ink cartridges 14 are removably attached. The four ink cartridges 14 are aligned in the scanning direction, and from the one arranged on the right side in the scanning direction, they store black, yellow, cyan, and magenta inks ("liquid" of the present invention). The subtank 3 is connected to the four ink cartridges 14 attached to the cartridge holder 13 via four tubes 15. In this way, the four colors of ink are supplied to the subtank 3 from the four ink cartridges 14.

[0015] The inkjet head 4 is mounted on the carriage 2 and connected to the lower end of the subtank 3. The inkjet head 4 is supplied with the four colors of ink from the subtank 3. The inkjet head 4 ejects ink from a plurality of nozzles 10 formed on its lower surface, a nozzle face 4a. More specifically, the nozzles 10 are arranged in a transport direction perpendicular to the scanning direction to form a nozzle row 9, and on the nozzle face 4a, four nozzle rows 9 are lined up in the scanning direction. From the nozzles 10, black, yellow, cyan, and magenta inks are ejected starting from the nozzle row 9 on the right side of the scanning direction.

[0016] The platen 5 is disposed below the inkjet head 4 and faces the multiple nozzles 10. The platen 5 extends over the entire length of the recording paper P (the "ejection receiving medium" of the present invention) in the scanning direction and supports the recording paper P from below. The transport roller 6 is disposed upstream of the inkjet head 4 and the platen 5 in the transport direction. The transport roller 7 is disposed downstream of the inkjet head 4 and the platen 5 in the transport direction. The transport rollers 6 and 7 are connected to a transport motor 87 (see FIG. 4) via gears and 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.

[0017] The maintenance unit 8 includes a cap 71, a suction pump 72, and a waste liquid tank 73. The cap 71 is disposed to the right of the platen 5 in the scanning direction. When the carriage 2 is positioned at a maintenance position to the right of the platen 5 in the scanning direction, the multiple nozzles 10 face the cap 71.

[0018] The cap 71 can be raised and lowered 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 and the cap 71 face each other, the cap 71 is raised by the cap lifting mechanism 88, whereby the upper end 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. Note that the cap 71 is not 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 a frame (not shown) or the like that is arranged around the nozzle surface 4a of the inkjet head 4, for example.

[0019] The suction pump 72 is a tube pump or the like, and is connected to the cap 71 and the waste liquid tank 73. In the maintenance unit 8, when the suction pump 72 is driven with the plurality of nozzles 10 covered by the cap 71 as described above, it is possible to perform a so-called suction purge (the "recovery operation" of the present invention) in which ink is discharged from within the inkjet head 4 through the plurality of nozzles 10. The ink discharged by the suction purge is stored in the waste liquid tank 73.

[0020] For convenience, the cap 71 covers all the nozzles 10 together, and ink in the inkjet head 4 is discharged from all the nozzles 10 during suction purge. However, the present invention is not limited to this. For example, the cap 71 may have a portion covering the nozzles 10 constituting the rightmost nozzle row 9 that ejects black ink and a portion covering the nozzles 10 constituting the three leftmost nozzle rows 9 that eject color inks (yellow, cyan, and magenta inks), and may selectively discharge either the black ink or the color ink in the inkjet head 4 during suction purge. Alternatively, for example, the cap 71 may be provided for each nozzle row 9, and ink may be discharged from the nozzles 10 for each nozzle row 9 separately during suction purge.

[0021] As shown in FIG. 2, a detection electrode 76 having a rectangular planar shape is disposed within the cap 71. The detection electrode 76 is connected to a high-voltage power supply circuit 77 via a resistor 79. A predetermined potential (for example, about 600 V) is applied to the detection electrode 76 by the high-voltage power supply circuit 77 during driving for inspection, which will be described later. Meanwhile, the inkjet head 4 is held at a ground potential. This generates a predetermined potential difference between the inkjet head 4 and the detection electrode 76. A signal processing circuit 78 is connected to the detection electrode 76. The signal processing circuit 78 includes a differentiation circuit and the like, and outputs a signal obtained by performing processing, including differentiation, on the potential signal output from the detection electrode 76. That is, the signal output from the signal processing circuit 78 is a potential signal corresponding to the potential of the detection electrode 76. However, the signal output from the signal processing circuit 78 may be a current signal. In this embodiment, the combination of the detection electrode 76, the high-voltage power supply circuit 77, the signal processing circuit 78, and the resistor 79 corresponds to the "signal output section" of the present invention.

[0022] After the carriage 2 is positioned at the maintenance position, a potential difference is generated between the inkjet head 4 and the detection electrode 76 by the high-voltage power supply circuit 77. At this time, when the inspection drive described below is not being performed, the value of the signal (non-driven signal) output from the signal processing circuit 78 becomes a predetermined reference value V0, as shown in Figures 3(a) and (b).

[0023] In this embodiment, after the carriage 2 is positioned at the maintenance position, a potential difference is generated between the inkjet head 4 and the detection electrode 76 by the high-voltage power supply circuit 77, and a test drive is performed in which the inkjet head 4 is driven to eject ink from the nozzles 10 toward the detection electrode 76.

[0024] In the test drive, if the nozzle 10 is not an abnormal nozzle having an abnormality in ink ejection, charged ink is ejected from the nozzle 10. This causes the charged ink to approach the detection electrode 76, and the potential of the detection electrode 76 changes until the ink lands on the detection electrode 76. Then, after the charged ink lands on the detection electrode 76, the potential of the detection electrode 76 attenuates and returns to the potential before the ink was ejected.

[0025] At this time, the signal output from the signal processing circuit 78 (the "judgment signal" of the present invention) rises from the point when the ink starts to be ejected from the nozzle 10, reaches a maximum value V1 higher than the reference value V0, and then drops to a minimum value V2 lower than the reference value V0, as shown in Figure 3(a).The signal then increases and decreases while attenuating, converging to the reference value V0.

[0026] On the other hand, if the nozzle 10 is an abnormal nozzle, even if the test drive is performed, ink will not be ejected from the nozzle 10. Therefore, the signal (determination signal) output from the signal processing circuit 78 indicative of the potential of the detection electrode 76 does not change from a predetermined reference value V0, as shown in FIG.

[0027] In this manner, in this embodiment, the signal output from the signal processing circuit 78 when the determination drive is performed differs depending on whether the nozzle 10 is an abnormal nozzle. This fact is utilized in this embodiment to determine whether the nozzle 10 is an abnormal nozzle, as described below.

[0028] <Printer electrical configuration> 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 is composed of a CPU (Central Processing Unit) 81, a ROM (Read Only Memory) 82, a RAM (Random Access Memory) 83, a flash memory (the "storage unit" of the present invention) 84, an ASIC (Application Specific Integrated Circuit) 85, and the like. The control device 80 controls the operations of a carriage motor 86, an inkjet head 4, a conveying motor 87, a cap lifting mechanism 88, a suction pump 72, a high-voltage power supply circuit 77, and the like. A determination signal is also input to the control device 80 from a signal processing circuit 78.

[0029] In addition to the components described above, the printer 1 also has a clock unit 68. The control device 80 receives a time signal indicating the time from the clock unit 68. Power is supplied to the printer 1 from an outlet (not shown), and power is supplied to the control device 80 and the clock unit 68.

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

[0031] <Standby control> Next, a description will be given of the control by the control device 80 during standby in the printer 1. During the standby state in the printer 1, the control device 80 performs processing according to the flow of FIG.

[0032] 5 in more detail, the control device 80 judges whether or not the time signal received from the clock unit 68 indicates that it is the predetermined time (S101). If the time signal received from the clock unit 68 does not indicate that it is the predetermined time (S101: NO), S101 is repeated. The predetermined time in this embodiment is set early in the morning, such as 6:00 AM, but is not particularly limited thereto.

[0033] On the other hand, if the time signal received from the clock unit 68 indicates that it is the predetermined time (S101: YES), the control device 80 judges whether the first inspection process has been executed during one day based on the time signal from the clock unit 68 and the inspection history information stored in the flash memory 84 (S102). In this embodiment, one day refers to the period from 0:00 AM to 0:00 AM of the next day, but the start time and end time may be set appropriately as long as it is 24 hours. In this embodiment, the control device 80 judges in S102 whether the inspection history information indicates that the first inspection process has been executed at least once between 0:00 AM and the predetermined time (6:00 AM).

[0034] If the first inspection process has not been performed even once (S102: NO), the control device 80 executes the first inspection process (S103). If the first inspection process has been performed even once (S102: YES), the control device 80 ends the standby flow.

[0035] <First inspection process> The first inspection process will now be described with reference to Fig. 6. In the first inspection process, the control device 80 first controls the carriage motor 86 to move the carriage 2 to the maintenance position (S201). If the carriage 2 is located at the maintenance position at the start of the flow in Fig. 6, the carriage 2 is maintained at the maintenance position in S201.

[0036] Next, the control device 80 controls the high-voltage power supply circuit 77 to apply a voltage to the detection electrode 76, thereby generating a potential difference between the detection electrode 76 and the inkjet head 4 (S202).

[0037] Next, the control device 80 sets one of the nozzles 10 of the inkjet head 4 as a target nozzle for determining whether it is an abnormal nozzle or not (S203). At this time, the nozzle 10 set as an unrecoverable nozzle (described later) is excluded from the target nozzles. An unrecoverable nozzle refers to a nozzle in which the ink inside the nozzle 10 has dried up and the nozzle 10 is no longer able to eject ink, or a nozzle 10 that has been damaged and is no longer able to eject ink or eject ink in a specified direction, and is a nozzle that is determined to be unlikely to be recovered even if suction purging is repeatedly performed as a recovery operation.

[0038] Next, the control device 80 executes a test drive process (S204). In S204, the control device 80 causes the inkjet head 4 to perform a test drive for ejecting ink from the target nozzle. At this time, the control device 80 stores, in the flash memory 84, test history information, which is information on the time when the test drive was performed, based on a time signal from the clock unit 68.

[0039] Next, when the test drive is performed by S204, the control device 80 determines, based on the judgment signal output from the signal processing circuit 78, whether or not the difference [Va1-Vb1] between the maximum value Va1 and the minimum value Vb1 of the judgment signal in the first period T1 is greater than or equal to the threshold value Vt (S205).

[0040] Here, the first period T1 is a part of the determination period T as shown in FIG. 3(a), and may include a first timing U1 at which the value of the determination signal is assumed to be a maximum value V1 when the test drive is performed and ink is ejected from the nozzle 10, and a second timing U2 at which the value of the determination signal is assumed to be a minimum value V2. Note that the determination period T is a period starting from the start of the test drive as shown in FIG. 3(a) until the signal output from the signal processing circuit 78 is sufficiently attenuated when ink is ejected from the nozzle 10 by the test drive. In this embodiment, the first timing U1 and the second timing U2 are obtained by experiments or the like during the manufacturing stage of the printer 1, and information on the first period T1 is stored in the flash memory 84 based on the first timing U1 and the second timing U2.

[0041] If the difference [Va1-Vb1] between the maximum value Va1 and the minimum value Vb1 of the judgment signal is equal to or greater than the threshold value Vt (S205: YES), the control device 80 stores in the flash memory 84 that the target nozzle is not an abnormal nozzle (S206). At this time, the value of the variable C for the target nozzle is reset to 0. Note that the variable C here is a parameter related to the state of the target nozzle, and is a variable for determining whether or not a parameter condition that may cause the nozzle to become unrecoverable has been reached, and is stored for each nozzle 10. In this embodiment, the parameter condition is reached when the variable C reaches the threshold value for an unrecoverable nozzle.

[0042] If the difference [Va1-Vb1] between the maximum value Va1 and the minimum value Vb1 of the judgment signal is less than the threshold value Vt (S205: NO), the control device 80 stores in the flash memory 84 that the target nozzle is an abnormal nozzle (S207). At this time, the value of the variable C for the target nozzle is increased by 1 (the "second parameter information" of the present invention).

[0043] Next, the controller 80 determines whether or not the parameter condition for an unrecoverable nozzle has been reached (S208). That is, the controller 80 determines whether or not the variable C stored in the flash memory 84 reaches the threshold value for an unrecoverable nozzle.

[0044] If the variable C reaches the threshold value for an unrecoverable nozzle (S208: YES), the control device 80 stores and sets the target nozzle (abnormal nozzle) as an unrecoverable nozzle in the flash memory 84 (S209). In other words, by setting the abnormal nozzle as an unrecoverable nozzle, it is excluded from the abnormal nozzles.

[0045] After S206 or S209, the control device 80 determines whether or not all nozzles 10 in the inkjet head 4 have been inspected to determine whether they are abnormal (S210). If there is a nozzle 10 for which inspection to determine whether or not it is abnormal has not been completed (S210: NO), the control device 80 changes the target nozzle to any of the nozzles 10 for which inspection to determine whether or not it is abnormal has not been completed (S211), and returns to S204. At this time, the nozzle 10 that has been set as an unrecoverable nozzle is excluded from the target nozzles.

[0046] If inspection of all nozzles 10 of the inkjet head 4 to determine whether they are abnormal nozzles has been completed (S210: YES), the control device 80 controls the high-voltage power supply circuit 77 to stop applying voltage to the detection electrode 76 (S212). Then, the process proceeds to S104.

[0047] In S104, the control device 80 determines whether the number of abnormal nozzles stored in the flash memory 84 is equal to or greater than a threshold value. At this time, nozzles 10 that are set as unrecoverable nozzles are not included in the abnormal nozzles and are excluded. If the number of abnormal nozzles stored in the flash memory 84 is equal to or greater than the threshold value (S104: YES), the control device 80 stores recovery flag information in the flash memory 84 (S105). Note that the recovery flag information is flag information to be stored in the flash memory 84 in order to later execute a suction purge to recover the abnormality of the nozzles 10 when the number of abnormal nozzles is equal to or greater than the threshold value.

[0048] In S104, if the number of abnormal nozzles stored in the flash memory 84 is less than the threshold value (S104: NO), the control device 80 erases the recovery flag information if recovery flag information is stored in the flash memory 84 (S106). In this way, the standby flow ends.

[0049] <Recording control> Next, a description will be given of the control when the printer 1 records on the recording paper P. When the printer 1 receives a recording command signal instructing to record on the recording paper P, the control device 80 performs processing according to the flow of Fig. 7. The recording command signal is a signal that instructs the printer 1 to record on the recording paper P, and is transmitted to the control device 80 from an external device or the like.

[0050] 7 in more detail, the control device 80 first judges whether or not a recording command signal has been received (S301). If a recording command signal has not been received (S301: NO), S301 is repeated. If a recording command signal has been received (S301: YES), the control device 80 judges whether or not the first inspection process has been executed during the day based on the time signal from the clock unit 68 and the inspection history information stored in the flash memory 84, similar to S102 (S302).

[0051] If the first inspection process has never been executed (S302: NO), the control device 80 executes a first inspection process similar to S103 (S303). After that, the control device 80 executes S304 to S306 similar to S104 to S106.

[0052] If the first inspection process has been executed at least once (S302: YES), the control device 80 determines whether recovery flag information is stored in the flash memory 84 (S307).

[0053] After S305, and if recovery flag information is stored in the flash memory 84 in S307 (S307: YES), the control device 80 executes recovery processing (S308).

[0054] In the recovery process in this embodiment, the control device 80 causes a suction purge to be performed. After the suction purge is completed, the control device 80 stores in the flash memory 84 recovery execution flag information indicating that the recovery process has been executed.

[0055] After S306 and S308, and if recovery flag information is not stored in the flash memory 84 in S307 (S307: NO), the control device 80 executes a print process (S309). That is, based on the received recording command signal, the control device 80 controls the paper feed mechanism (not shown) and the transport motor 87 to cause the paper feed mechanism to supply the recording paper P, and causes the transport rollers 6 and 7 to transport the recording paper P to a position where an area on the recording paper P where an image is to be recorded in the first recording pass faces the multiple 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, while controlling the inkjet head 4 to perform a recording pass in which ink is discharged from the multiple nozzles 10 toward the recording paper P (the "discharge operation" of the present invention).

[0056] Thereafter, if recording on one sheet of recording paper P is not complete, the control device 80 controls the transport motor 87 to cause the transport rollers 6, 7 to transport the recording paper P a predetermined distance, and repeats the operation of causing the transport rollers 6, 7 to perform a recording pass again until recording on one sheet of recording paper P is complete. If recording of an image on one sheet of recording paper P is complete, the control device 80 controls the transport motor 87 to cause the transport rollers 6, 7 to discharge the recording paper P on which recording has been completed.

[0057] Next, the control device 80 judges whether or not a recording command signal other than the recording command signal received in S301 has been received. That is, the control device 80 judges whether or not a different recording command signal has been received before executing the second inspection process described below after the printing process (ejection operation) in S309. If a different recording command signal has been received (S310: YES), the control device 80 executes the printing process based on the different recording command signal received, as in S309.

[0058] After S311, and if no other recording command signal has been received in S310 (S310: NO), the control device 80 determines whether recovery execution flag information is stored in the flash memory 84 (S312).

[0059] If recovery execution flag information is not stored in the flash memory 84 (S312: NO), the control device 80 ends the flow at the time of recording. Thus, in this embodiment, if recovery execution flag information is not stored in the flash memory 84, that is, if recovery processing has not been performed, the control device 80 does not execute the second inspection processing described below after the printing processing. On the other hand, if recovery execution flag information is stored in the flash memory 84 (S312: YES), the control device 80 executes the second inspection processing (S313).

[0060] The second inspection process is an inspection process that is performed after the printing process (ejection operation) associated with the received recording command signal and when the recovery process is performed before the printing process. The second inspection process is almost the same as the first inspection process shown in Fig. 6, so only the differences will be described and the same points will not be described.

[0061] In the second inspection process in this embodiment, the period of the determination signal in S205 in the first inspection process is different. That is, in S205 in the second inspection process, the control device 80 determines whether or not the difference [Va2-Vb2] between the maximum value Va2 and the minimum value Vb2 of the determination signal in the second period T2 is equal to or greater than the threshold value Vt, based on the determination signal output from the signal processing circuit 78.

[0062] Here, the second period T2 is a part of the judgment period T as shown in FIG. 3(a), and may include the first timing U1 and the second timing U2, similar to the first period T1. The second period T2 is longer than the first period T1. Therefore, although the judgment time in S205 in the second inspection process is longer than that in the first inspection process, the longer period makes it possible to accurately detect the maximum value Va2 and the minimum value Vb2 even if the first timing U1 and the second timing U2 are slightly shifted forward or backward from the expected value. Therefore, it becomes possible to accurately determine whether the nozzle is an abnormal nozzle. Information on the second period T2 is also stored in the flash memory 84.

[0063] Furthermore, the second inspection process in this embodiment differs from the first inspection process in the increment of the value of the variable C for the target nozzle in S207. That is, in the second inspection process, the value of the variable C is incremented by 2 ("first parameter information" of the invention). Note that differences between the second inspection process and the first inspection process are indicated in parentheses in FIG. 6.

[0064] Next, the control device 80 erases the recovery execution flag information stored in the flash memory 84 (S314). Thereafter, the control device 80 executes S315 and S316 similar to S304 and S306. Note that even if the number of abnormal nozzles equal to or greater than the threshold is stored in the flash memory 84 in S315 (S315: YES), the process of storing the recovery flag information is omitted because the previous recovery flag information has already been stored in the flash memory 84. In this way, the flow during recording ends.

[0065] As described above, according to the printer 1 of this embodiment, when the recovery process (recovery operation) is executed in S308, the test drive is not executed until the printing process (ejection operation) of S309 is started, and the test drive is executed in S313 after the printing process of S309 is finished. Therefore, the time until the printing process starts is shortened by the amount of the test drive not executed between the end of the previous recovery process and the start of the printing process. In addition, since the test drive is executed in S313 after the printing process of S309 is finished, it is possible to determine whether the number of abnormal nozzles after the recovery process of S308 is equal to or greater than the threshold (S315). In addition, the first test process (test drive) of S103 is executed by receiving a time signal indicating that it is a predetermined time.

[0066] Furthermore, if another recording command signal is received before the second test process is executed (S310: YES), the print process of S311 is executed prior to the second test process (S313) following the print process of S309. This shortens the time from when another recording command signal is received until the print process of S311 (another ejection operation) starts.

[0067] Furthermore, since the second period T2 is longer than the first period T1, the time required to determine whether the nozzle 10 is an abnormal nozzle by the test drive of the second test process is longer than the time required to determine whether the nozzle 10 is an abnormal nozzle by the test drive of the first test process (S103, S303) before the printing process (S309). This makes it possible to improve the accuracy of determining whether a nozzle is abnormal in the test drive of the second test process executed in the printing process of S309. Note that, as a modified example, the first period T1 and the second period T2 may be the same. Also, as another modified example, the first period T1 may be longer than the second period T2.

[0068] Furthermore, the value of variable C is incremented by 2 as a parameter relating to the state of nozzle 10 determined to be an abnormal nozzle in the second inspection process (first parameter information). Then, in S208, if the value of variable C reaches the threshold value for an unrecoverable nozzle (S208: YES), the control device 80 stores and sets the target nozzle as an unrecoverable nozzle in the flash memory 84 (S209). This makes it possible to set, among the abnormal nozzles, nozzles that cannot be recovered even by executing recovery processing as unrecoverable nozzles.

[0069] In this embodiment, the value of the variable C of a target nozzle that is determined to be abnormal in succession is increased and the nozzle is set as an unrecoverable nozzle when the value reaches a threshold, but the value of the variable C of a target nozzle that is determined to be abnormal in succession may be decreased and the nozzle may be set as an unrecoverable nozzle when the value reaches a threshold. Also, when a nozzle is determined to be abnormal in the second inspection process, a larger increase is added to the variable C, but the same value as in the first inspection process may be added, or it may be set appropriately.

[0070] Furthermore, the increment value of the variable C is greater when the nozzle is determined to be abnormal in the second inspection process than when the nozzle is determined to be abnormal in the first inspection process, making it easier to reach the parameter condition (threshold value) that may make the nozzle unrecoverable. This allows the setting of an unrecoverable nozzle to be performed effectively. Note that, as a modified example, a larger increment value of the variable C is added when the nozzle is determined to be abnormal in the second inspection process (i.e., the second inspection process is weighted more than the first inspection process), but the same value as in the first inspection process may be added, and may be set appropriately. Also, as another modified example, the value of the variable C may not be increased in the first inspection process. In other words, the value of the variable C may be changed so that the parameter condition is easier to reach only when the nozzle is determined to be abnormal in the second inspection process.

[0071] Furthermore, in S209, the control device 80 sets the abnormal nozzle as an unrecoverable nozzle, thereby excluding the abnormal nozzle. This makes it possible to effectively detect abnormal nozzles other than the unrecoverable nozzles.

[0072] Next, a printer according to the second embodiment will be described below with reference to Fig. 8. The printer according to this embodiment is the same as the printer 1 of the first embodiment except for a part of the control during printing. Therefore, the same reference numerals are used for the same parts as the first embodiment and the description will be omitted.

[0073] <Recording control> In the printer of this embodiment, the control device 80 performs processing according to the flow of Fig. 8. The control device 80 first executes S401, which is similar to S301 described above. If a recording command signal has not been received (S401: NO), S401 is repeated. If a recording command signal has been received (S401: YES), the control device 80 executes S402, which is similar to S307 described above.

[0074] If recovery flag information is not stored in the flash memory 84 in S402 (S402: NO), the control device 80 executes a first inspection process similar to S303 described above (S403). After this, S404 to S406 similar to S304 to S306 described above are executed. After S406, the process proceeds to S409.

[0075] After S405, and if recovery flag information is stored in the flash memory 84 in S402 (S402: YES), the control device 80 executes recovery processing (S407). At this time, the control device 80 stores recovery execution flag information indicating that recovery processing has been executed in the flash memory 84. Furthermore, in this embodiment, the control device 80 increments the variable D by 1 each time recovery processing is executed. The variable D here is a value that counts how many times recovery processing has been executed, and is stored in the flash memory 84.

[0076] Next, the control device 80 judges whether the number of times the recovery process has been executed has reached a predetermined number (S408). That is, the control device 80 judges whether the variable D has reached a value of a predetermined number (e.g., 3 times). If the number of times the recovery process has been executed has not reached the predetermined number (S408: NO), the process returns to S403.

[0077] After S406, and in S408, if the number of times the recovery process has been performed reaches a predetermined number (S408: YES), the control device 80 executes a print process similar to S309 (S409). In this way, if the recovery process of S407 has not been performed the predetermined number of times, the control device 80 alternately executes the recovery process (S407) and the first inspection process (S403) prior to the print process of S409 until it is determined in S404 that the number of abnormal nozzles is less than the threshold. Then, when the recovery process (S407) has been performed the predetermined number of times, the process proceeds to the print process of S409.

[0078] Next, the control device 80 resets the variable D, which is the number of times the recovery process has been performed, to 0 (S410). After that, the control device 80 executes S411 to S413, which are similar to the above-mentioned S310 to S312.

[0079] If the recovery execution flag information is not stored in the flash memory 84 (S413: NO), the control device 80 ends the flow at the time of recording. Thus, in this embodiment as well, if the recovery execution flag information is not stored in the flash memory 84, that is, if the recovery process has not been performed, the control device 80 does not execute the second inspection process after the printing process.

[0080] On the other hand, if recovery execution flag information is stored in the flash memory 84 (S413: YES), the control device 80 executes a second inspection process similar to S313 described above (S414). After that, S415 to S417 similar to S314 to S316 described above are executed. In this way, the recording flow ends.

[0081] As described above, according to the printer of this embodiment, when the recovery process of S407 is executed a predetermined number of times, the test drive is not executed before the printing process (ejection operation) of S409 is started, and the test drive is executed in S414 after the printing process of S409 is finished. Therefore, the time until the printing process starts is shortened by the amount of the test drive not executed between the end of the previous recovery process and the start of the printing process. In addition, since the test drive is executed in S414 after the printing process of S409 is finished, it is possible to determine whether the number of abnormal nozzles after the recovery process of S407 is executed is equal to or greater than the threshold (S416). Note that the same effect can be obtained for a configuration similar to that of the first embodiment described above.

[0082] Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible within the scope of the claims. In the above-mentioned embodiments, the test drive is triggered by the reception of a time signal indicating a predetermined time and a recording command signal, but the test drive for performing the first test process may be executed by other triggers. In this case, the clock unit 68 may not be provided.

[0083] Furthermore, in each of the above-described embodiments, if the parameter condition for an unrecoverable nozzle is reached (S208: YES), the target nozzle is set as an unrecoverable nozzle in S209, but it is not necessary to set the target nozzle as an unrecoverable nozzle.

[0084] In addition, in each of the above-described embodiments, in S203 and S211, one nozzle 10 out of the multiple nozzles 10 of the inkjet head 4 is set as the target nozzle for determining whether or not it is an abnormal nozzle, but this is not limited to the above. Two or more nozzles may be set as the target nozzle and the inspection drive process (S204) may be performed. In this case, a threshold value may be set according to the number of target nozzles. For example, the greater the number of target nozzles, the greater the threshold value may be set.

[0085] In addition, in each of the above-described embodiments, the inspection drive is performed on all the nozzles 10 of the inkjet head 4, but this is not limited to the above. For example, the inspection drive may be performed on only some of the nozzles 10 of the inkjet head 4, such as every other nozzle 10 in each nozzle row 9, and the remaining nozzles 10 may be determined to be abnormal or not based on the determination signal output from the signal processing circuit 78 during the inspection drive.

[0086] Furthermore, in the above-described embodiment, the signal processing circuit 78 outputs a signal indicating whether or not the nozzle is abnormal, depending on the potential of the detection electrode 76 when ink is ejected from the nozzle 10 toward the detection electrode 76, but this is not limited to the above.

[0087] For example, a detection electrode extending in the vertical direction may be disposed, and a signal processing circuit may output a signal indicating whether or not the nozzle is abnormal, depending on the potential of the detection electrode when ink is ejected from the nozzle 10 so as to pass through a region facing the detection electrode. Alternatively, an optical sensor (the "signal output unit" of the present invention) may be provided to detect ink ejected from the nozzle 10, and a signal indicating whether or not the nozzle is abnormal may be output from the optical sensor.

[0088] Alternatively, for example, as described in Patent Gazette No. 4929699, a voltage detection circuit (the "signal output section" of the present invention) that detects the change in voltage when ink is ejected from the nozzles can be connected to a plate on which the nozzles of the inkjet head are formed, and a signal indicating whether or not the nozzle is abnormal can be output from the voltage detection circuit to the control device 80.

[0089] Alternatively, for example, the substrate of the inkjet head may be provided with a temperature detection element (the "signal output unit" of the present invention) as described in Japanese Patent No. 6231759. Then, after applying a first applied voltage to drive the heater for ejecting ink, a second applied voltage is applied to drive the heater so that ink is not ejected, and a signal is output in accordance with whether the nozzle 10 is an abnormal nozzle or not based on the change in temperature detected by the temperature detection element during the period from when the second applied voltage is applied until a predetermined time has elapsed.

[0090] In the above example, the nozzle 10 from which ink is not ejected is determined to be an abnormal nozzle, but this is not limited to the above. For example, a signal output unit may be provided that outputs a signal depending on whether the direction of ink ejection from the nozzle 10 is normal or not, and a nozzle 10 with an abnormality in the ejection direction may be determined to be an abnormal nozzle based on the signal from this signal output unit.

[0091] Also, a signal output unit may be provided that outputs a signal corresponding to the abnormal nozzle state other than the ink not being ejected, and information regarding the abnormal nozzle state may be obtained based on the signal from the signal output unit. The abnormal nozzle state may be, for example, a state in which the ink ejection direction is abnormal, splashes occur, air bubbles are mixed in, or the ink is clogged with paper powder. In this case, the inspection drive may apply pressure to the ink to the extent that the ink is not ejected from the nozzle 10, thereby vibrating the ink in the vicinity of the nozzle 10. 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 obtain information regarding the abnormal nozzle state.

[0092] In addition, although the suction purge is performed in the recovery process, the present invention is not limited to this. For example, a pressure pump may be provided in the middle of the tube 15 that connects the subtank 3 and the ink cartridge 14. Alternatively, a pressure pump connected to the ink cartridge may be provided in the printer. Then, with the nozzles 10 covered with the caps 71, the pressure pump may be driven to pressurize the ink in the inkjet head 4 and discharge the ink in the inkjet head 4 from the nozzles 10, thereby performing a so-called pressure purge.

[0093] Furthermore, in the recovery process, both suction by the suction pump 72 and pressurization by the pressure pump may be performed.

[0094] Furthermore, the method of recovering abnormal nozzles is not limited to purging. For example, abnormal nozzles may be recovered by flushing, which causes the inkjet head 4 to discharge ink from the nozzles 10. Alternatively, abnormal nozzles may be recovered by both purging and flushing. Alternatively, abnormal nozzles may be recovered by selectively performing either purging or flushing depending on the number of abnormal nozzles, etc.

[0095] In addition, although the present invention has been described as being applied to a printer equipped with a so-called serial head that ejects ink from multiple nozzles while moving in the scanning direction together with the carriage, the present invention is not limited to this. For example, the present invention can also be applied to a printer equipped with a so-called line head that extends across the entire length of the recording paper P in the scanning direction.

[0096] Also, although an example of application of the present invention to a printer that ejects ink from nozzles to perform recording on recording paper P has been described, 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 advertising, cases for mobile terminals such as smartphones, cardboard, and resin members. The present invention can also be applied to liquid ejection devices that eject liquids other than ink, such as liquid resins and metals. [Explanation of symbols]

[0097] 1. Printer (liquid ejection device) 4. Inkjet head (liquid ejection head) 8 Maintenance Unit (Recovery Method) 10 Nozzles 68 Clock Section 76 Detection electrode (part of the signal output section) 77 High voltage power supply circuit (part of the signal output section) 78 Signal processing circuit (part of the signal output section) 79 Resistor (part of signal output section) 80 Control device 84 Flash memory (storage section)

Claims

1. 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 when the liquid ejection head is driven for inspection to confirm whether or not the plurality of nozzles are abnormal nozzles having an abnormality in ejecting liquid; A recovery means for performing a recovery operation to discharge liquid from the nozzle; A control device, The control device includes: When a discharge operation is performed in which the liquid discharge head discharges liquid from the plurality of nozzles toward a discharge receiving medium, performing the test driving prior to the ejection operation; when it is determined that the number of the abnormal nozzles is equal to or greater than a threshold value based on the determination signal output from the signal output unit during the test drive, the recovery means is caused to perform the recovery operation prior to the ejection operation; When the recovery operation is performed, the test driving is performed after the ejection operation is completed. The liquid ejection apparatus according to claim 1, wherein, if the recovery operation is not being performed, the test driving is not performed after the ejection operation is completed.

2. 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 when the liquid ejection head is driven for inspection to confirm whether or not the plurality of nozzles are abnormal nozzles having an abnormality in ejecting liquid; A recovery means for performing a recovery operation to discharge liquid from the nozzle; A control device, The control device includes: When a discharge operation is performed in which the liquid discharge head discharges liquid from the plurality of nozzles toward a discharge receiving medium, performing the test driving prior to the ejection operation; when it is determined that the number of the abnormal nozzles is equal to or greater than a threshold value based on the determination signal output from the signal output unit during the test driving, the recovery operation and the test driving are alternately repeated until it is determined that the number of the abnormal nozzles is less than the threshold value prior to the ejection operation; When the recovery operation has been performed a predetermined number of times, the ejection operation is performed. When the recovery operation is performed after the test drive immediately before the discharge operation and before the discharge operation is performed, the test drive is performed after the discharge operation is completed; A liquid ejection device characterized in that if the recovery operation is not performed from the test drive immediately before the ejection operation to the time the ejection operation is performed, the test drive is not executed after the ejection operation is completed.

3. The control device includes: A liquid ejection device as described in claim 1 or 2, characterized in that when the test drive after the ejection operation is executed, if a signal for performing an ejection operation other than the ejection operation is received before the test drive after the ejection operation, the other ejection operation is executed prior to the test drive after the ejection operation.

4. A liquid ejection device as described in any one of claims 1 to 3, characterized in that the time required to determine whether or not the nozzle is an abnormal nozzle by the inspection drive after the ejection operation is longer than the time required to determine whether or not the nozzle is an abnormal nozzle by the inspection drive before the ejection operation.

5. Further comprising a storage unit, The control device includes: For the nozzle determined to be the abnormal nozzle by the inspection driving after the ejection operation, parameters related to the state of the nozzle are stored in the storage unit as first parameter information; 5. The liquid ejection device according to claim 1, wherein the nozzle in which the first parameter information stored in the storage unit has reached a predetermined condition is set as an unrecoverable nozzle.

6. The control device includes: For the nozzle determined to be the abnormal nozzle by the inspection driving before the ejection operation, parameters related to the state of the nozzle are stored in the storage unit as second parameter information; setting the nozzle that has reached a predetermined condition as the non-recoverable nozzle based on the first parameter information and the second parameter information stored in the storage unit; The liquid ejection device according to claim 5 , wherein the first parameter information is set so that the state of the nozzle is more likely to reach a predetermined condition than the second parameter information having the same nozzle state.

7. The control device includes:

7. The liquid ejection apparatus according to claim 5, wherein the nozzles set as the unrecoverable nozzles are excluded from the abnormal nozzles determined by the inspection drive.

8. 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 when the liquid ejection head is driven for inspection to confirm whether or not the plurality of nozzles are abnormal nozzles having an abnormality in ejecting liquid; A recovery means for performing a recovery operation to discharge liquid from the nozzle; A clock unit that outputs a time signal indicating the time; A storage unit; A control device, The control device includes: performing the test driving when the time signal, which is a predetermined time output from the clock unit, is received; when it is determined that the number of the abnormal nozzles is equal to or greater than a threshold value based on the determination signal output from the signal output unit during the test drive, flag information indicating that the recovery operation needs to be performed is stored in the storage unit; after the inspection driving, when a discharge operation is performed in which the liquid discharge head discharges liquid from the plurality of nozzles toward a discharge receiving medium, if the flag information is stored in the storage unit, the recovery unit is caused to perform the recovery operation prior to the discharge operation; When the recovery operation is performed, the test driving is performed after the ejection operation is completed. The liquid ejection apparatus according to claim 1, wherein, if the recovery operation is not being performed, the test driving is not performed after the ejection operation is completed.

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