JP7697231B2 - liquid discharge device - Google Patents

Description

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

As an example of a liquid ejection device that ejects liquid from nozzles, Patent Document 1 describes a printer that ejects ink from nozzles to perform recording. In the printer of Patent Document 1, when the printer is in a periodic cleaning mode in which cleaning is performed periodically at predetermined intervals, the ejection state of each nozzle is inspected at predetermined intervals, and a cleaning process is performed based on the inspection results.

JP 2020-157483 A

In Patent Document 1, the timing of switching to the regular cleaning mode may occur during recording. If, at this time, the ejection state is inspected and a cleaning process is performed based on the result after recording is completed, recording will continue in a state where cleaning is required, and there is a risk that ink will not be ejected properly from the nozzles, resulting in a deterioration in the quality of the recorded image.

The object of the present invention is to provide a liquid ejection device that can properly eject liquid onto an ejection medium.

A liquid ejection device of the present invention includes a liquid ejection head having a plurality of nozzles that eject liquid onto an ejection receiving medium, a signal output unit that outputs a determination signal according to whether or not the nozzle is an abnormal nozzle when the liquid ejection head is caused to perform an inspection drive to check whether or not the nozzle is an abnormal nozzle having an abnormality in ejecting liquid, a recovery means that performs a recovery operation to discharge liquid from the nozzle, and a control device, wherein the control device is capable of receiving an ejection instruction signal that instructs the liquid ejection head to perform an ejection operation to eject liquid from the plurality of nozzles, and an inspection instruction signal that is received regardless of the timing of the ejection operation and instructs the liquid ejection head to inspect whether or not the nozzle is the abnormal nozzle, and when the ejection instruction signal is received, causes the liquid ejection head to perform the ejection operation, and when the inspection instruction signal is received, performs the inspection drive for at least two of the plurality of nozzles. The liquid ejection head is caused to perform inspection operations which are performed in sequence, and when the inspection instruction signal is received during the ejection operation, if the number of ejection receiving media to which liquid has not been completely ejected during the ejection operation is equal to or greater than a predetermined number, the liquid ejection head is caused to interrupt the ejection operation and perform the inspection operation , and after the inspection operation is completed, the liquid ejection head is caused to resume the ejection operation, and further, if the determination signal output from the signal output unit during the inspection operation after the inspection operation indicates that an abnormal nozzle is present, after the inspection operation is completed, the recovery means is caused to perform the recovery operation and then the liquid ejection head is caused to resume the ejection operation , and when the inspection instruction signal is received during the ejection operation, if the number of ejection receiving media to which liquid has not been completely ejected during the ejection operation is less than a predetermined number, the liquid ejection head is caused to continue the ejection operation, and after the ejection operation is completed, the liquid ejection head is caused to perform the inspection operation .

Furthermore, a liquid ejection device of the present invention includes a liquid ejection head having a plurality of nozzles that eject liquid onto an ejection receiving medium, a signal output unit that outputs a determination signal according to whether or not the nozzle is an abnormal nozzle when the liquid ejection head is driven for inspection to confirm whether or not the nozzle is an abnormal nozzle having an abnormality in ejecting liquid, recovery means that performs a recovery operation to discharge liquid from the nozzle, and a control device, wherein the control device receives an ejection instruction signal that instructs the liquid ejection head to perform an ejection operation to eject liquid from the plurality of nozzles, and an inspection instruction signal that is received regardless of the timing of the ejection operation and instructs to inspect whether or not the nozzle is the abnormal nozzle. the signal output unit is capable of receiving the signal, and when the ejection instruction signal is received, the liquid ejection head is caused to perform the ejection operation, and when the inspection instruction signal is received, the liquid ejection head is caused to perform an inspection operation in which the inspection drive is performed in sequence for at least two of the plurality of nozzles, and when the ejection instruction signal is received during the inspection operation, the liquid ejection head is caused to perform the ejection operation after the inspection operation is completed, and further, if the determination signal output from the signal output unit during the inspection operation indicates that an abnormal nozzle exists after the inspection operation is completed, the recovery means is caused to perform the recovery operation and then the liquid ejection head is caused to perform the ejection operation after the inspection operation is completed.
Furthermore, a liquid ejection device of the present invention includes a liquid ejection head having a plurality of nozzles that eject liquid onto an ejection receiving medium, a signal output unit that outputs a determination signal according to whether or not the nozzle is an abnormal nozzle when the liquid ejection head is driven for inspection to confirm whether or not the nozzle is an abnormal nozzle having an abnormality in ejecting liquid, a recovery means that performs a recovery operation to discharge liquid from the nozzle, a clock unit that outputs a time signal indicating the time, and a control device, wherein the control device is capable of receiving an ejection instruction signal that instructs the liquid ejection head to perform an ejection operation to eject liquid from the plurality of nozzles, and an inspection instruction signal that is received regardless of the timing of the ejection operation and instructs to inspect whether or not the nozzle is the abnormal nozzle, and when the control device receives the ejection instruction signal and when the inspection instruction signal is received, the liquid ejection head is caused to perform an inspection operation in which the inspection drive is performed in sequence for at least two of the plurality of nozzles. When the inspection instruction signal is received in the middle of the ejection operation, the liquid ejection head is caused to interrupt the ejection operation and perform the inspection operation. After the inspection operation is completed, the liquid ejection head is caused to resume the ejection operation. Furthermore, if the determination signal output from the signal output unit during the inspection operation after the inspection operation indicates that an abnormal nozzle exists, after the inspection operation is completed, the recovery means is caused to perform the recovery operation and then the liquid ejection head is caused to resume the ejection operation. The inspection instruction signal is the time signal indicating that a predetermined time has arrived .

The present invention allows liquid to be appropriately ejected from the nozzle during the ejection operation.

1 is a schematic configuration diagram of a printer according to an embodiment of the present invention; 4A and 4B 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 determination circuit. FIG. 1A is a diagram showing the change in potential of the detection electrode when ink is ejected from the nozzle, and FIG. 1B is a diagram showing the change in potential of the detection electrode when ink is not ejected from the nozzle. FIG. 2 is a block diagram showing the electrical configuration of the printer. 4 is a flowchart showing a flow of processing by a control device. 6 is a flowchart showing the flow of processing after A shown in FIG. 5 . 6 is a flowchart showing the flow of processing after B shown in FIG. 5 . 8 is a flowchart corresponding to FIG. 7 of Modification 1. 8 is a flowchart corresponding to FIG. 7 of Modification 2. FIG. 13 is a diagram for explaining a table that associates image quality modes with predetermined values Nt in Modification 3. FIG. 13 is a block diagram showing the electrical configuration of a printer according to a fourth modified example. 13 is a flowchart of a fourth modified example corresponding to FIG. 5 . 13 is a flowchart showing the process flow from C onward in FIG. 12 . 13 is a flowchart showing the process flow after D in FIG. 12 .

A preferred embodiment of the present invention is described below.

<Overall printer configuration>
As shown in FIG. 1, a printer 1 (the "liquid ejection device" of the present invention) according to this 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.

The carriage 2 is supported by two guide rails 11, 12 that extend 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.

The subtank 3 is mounted on the carriage 2. Here, the printer 1 is equipped with a cartridge holder 13, in which four ink cartridges 14 are removably attached. The four ink cartridges 14 are lined up in the scanning direction, and from the one positioned on the right side of 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.

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 also ejects ink from multiple nozzles 10 formed on its lower surface, the nozzle surface 4a. More specifically, the multiple nozzles 10 are arranged in a transport direction perpendicular to the scanning direction to form a nozzle row 9, and on the nozzle surface 4a, four nozzle rows 9 are lined up in the scanning direction. From the multiple nozzles 10, black, yellow, cyan, and magenta inks are ejected from the nozzle row 9 on the right side of the scanning direction.

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 "ejected 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.

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 the maintenance position to the right of the platen 5 in the scanning direction, the multiple nozzles 10 face the cap 71.

The cap 71 can be raised and lowered by a cap lifting mechanism 88 (see FIG. 4). When the carriage 2 is positioned in the maintenance position so that the multiple nozzles 10 and the cap 71 face each other, the cap 71 is raised by the cap lifting mechanism 88, and the upper end of the cap 71 comes into close contact with the nozzle surface 4a, covering the multiple nozzles 10. Note that the cap 71 is not limited to covering the multiple nozzles 10 by coming into close contact with the nozzle surface 4a. The cap 71 may cover the multiple nozzles 10, for example, 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.

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 multiple nozzles 10 covered by the cap 71 as described above, a so-called suction purge can be performed, which discharges ink from within the inkjet head 4 through the multiple nozzles 10. The ink discharged by the suction purge is stored in the waste liquid tank 73.

For the sake of 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 purging. However, this is not limited to the above. 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 either the black ink or the color ink in the inkjet head 4 may be selectively discharged during suction purging. 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 purging.

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 positive potential (e.g., about 600 V) is applied to the detection electrode 76 by the high-voltage power supply circuit 77 during the determination drive described below. Meanwhile, the inkjet head 4 is held at ground potential. This creates a predetermined potential difference 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.

To explain in more detail, since a potential difference occurs between the inkjet head 4 and the detection electrode 76, the ink ejected from the nozzle 10 is charged. When ink is ejected from the nozzle 10 toward the detection electrode 76 with the carriage 2 positioned in the maintenance position, as shown in FIG. 3(a), the charged ink approaches the detection electrode 76, and the potential of the detection electrode 76 drops from the potential Va when the inkjet head 4 is not driven until the ink lands on the detection electrode 76, 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, the potential of the detection electrode 76 changes during the drive period Td of the inkjet head 4.

On the other hand, when ink is not being ejected from the nozzle 10, as shown in FIG. 3B, the potential of the detection electrode 76 hardly changes from the potential Va during the drive period Td of the inkjet head 4. Therefore, the judgment circuit 78 is set with a threshold value Vt (Vb<Vt<Va) to distinguish between these. The judgment circuit 78 compares the maximum potential of the voltage signal output from the detection electrode 76 with the threshold value Vt during the drive period Td of the inkjet head 4, and outputs a judgment signal according to the judgment result. In this embodiment, the combination of the detection electrode 76, the high voltage power supply circuit 77, the resistor 79, and the judgment circuit 78 corresponds to the "signal output unit" of the present invention. The signal output unit outputs a judgment signal according to whether the nozzle 10 is an abnormal nozzle that does not eject ink.

In addition, here, a positive potential is applied to the detection electrode 76 by the high voltage power supply circuit 77, but a negative potential (for example, about -600V) may also be applied to the detection electrode 76 by the high voltage power supply circuit 77. In this case, contrary to the above, when ink is ejected from the nozzle 10 toward the detection electrode 76 with the carriage 2 positioned in the maintenance position, the charged ink approaches the detection electrode 76, and the potential of the detection electrode 76 rises from potential Va until the ink lands on the detection electrode 76, and after the ink lands on the detection electrode 76, the potential of the detection electrode 76 gradually decreases and returns to potential Va.

<Printer Electrical Configuration>
Next, the electrical configuration of the printer 1 will be described. As shown in Fig. 4, the printer 1 is equipped with a control device 80. The control device 80 is made up of 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, etc. The control device 80 controls the operations of a carriage motor 86, an inkjet head 4, a transport motor 87, a cap lifting mechanism 88, a suction pump 72, a high-voltage power supply circuit 77, etc.

In addition to the components described above, the printer 1 also includes a clock unit 70. The clock unit 70 keeps track of time and outputs a time signal indicating the current time. The control device 80 receives the time signal from the clock unit 70.

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 a single CPU 81 performs processes independently, or one in which multiple CPUs 81 share the processing load. The control device 80 may be one in which a single ASIC 85 performs processes independently, or one in which multiple ASICs 85 share the processing load.

<Control of the printer by the control device>
Next, a description will be given of the control of the printer 1 by the control device 80. The control device 80 controls the operation of the printer 1 by carrying out processes in accordance with the flow of FIG.

To explain in more detail, the control device 80 is in standby while it has not received a time signal (the "inspection instruction signal" of the present invention) from the clock unit 70 indicating that a predetermined time has arrived (S101: NO) and has not received a recording command (the "ejection instruction signal" of the present invention) instructing recording on the recording paper P (S102: NO).

When a time signal indicating that the specified time has arrived is received (S101: YES), the control device 80 starts the inspection operation (S103) and proceeds to the flow of FIG. 6. The inspection operation is an operation in which the inkjet head 4 sequentially performs inspection driving for each of the multiple nozzles 10 with the carriage 2 positioned at the maintenance position. The inspection driving is the driving of the inkjet head 4 to eject ink from the nozzles 10. In other words, the inspection driving is the driving of the inkjet head 4 to check whether the nozzle 10 is an abnormal nozzle having an abnormality in ejecting ink.

Explaining the flow of FIG. 6, while the control device 80 has not received a recording command (S201: NO), it continues the inspection operation as is until the inspection operation is completed (S203: NO). When a recording command is received during the inspection operation (S201: YES), it stores a recording flag indicating the need to record in the flash memory 84 (S202) and continues the inspection operation (proceed to S203).

When the inspection operation is completed (S203: YES), the control device 80 judges whether or not there is an abnormal nozzle based on the signal output from the judgment circuit 78 during the inspection operation (S204). If there is no abnormal nozzle (S204: NO), it judges whether or not a recording flag is stored in the flash memory 84 (S205). If a recording flag is not stored in the flash memory 84 (S205: NO), the process returns to S101 in FIG. 5. If a recording flag is stored in the flash memory 84 (S205: YES), the process proceeds to S212.

If an abnormal nozzle is present (S204: YES), the control device 80 stores a recovery flag indicating that a recovery operation is necessary in the flash memory 84 (S206), and, with the carriage 2 positioned in the maintenance position, causes the inkjet head 4 to perform flushing to expel ink from at least the abnormal nozzle (S207).

Next, if a recording flag is not stored in the flash memory 84 (S208: NO), the process returns to S101 in FIG. 5. If a recording flag is stored in the flash memory 84 (S208: YES), the control device 80 determines whether the number N of abnormal nozzles is equal to or greater than a predetermined value Nt based on the signal output from the determination circuit 78 during the inspection operation (S209). Note that in this embodiment, the condition that the number N of abnormal nozzles is equal to or greater than the predetermined value Nt corresponds to the "predetermined condition" of the present invention.

If the number N of abnormal nozzles is less than the predetermined value Nt (S209: NO), proceed directly to S212. If the number N of abnormal nozzles is equal to or greater than the predetermined value Nt (S209: YES), the control device 80 performs suction purging (S210), erases the recovery flag stored in the flash memory 84 (S211), and then proceeds to S212. In this embodiment, flushing and suction purging correspond to the "recovery operation" of the present invention. Also, the inkjet head 4 that performs flushing and the maintenance unit 8 that performs suction purging correspond to the "recovery means" of the present invention.

In S212, the control device 80 causes the recording operation (the "ejection operation" of the present invention) to be performed. More specifically, the control device 80 causes the recording operation to be performed by repeating a recording pass in which the inkjet head 4 ejects ink from the multiple nozzles 10 toward the recording paper P while controlling the carriage motor 66 to move the carriage 2 in the scanning direction, and a transport operation in which the transport rollers 6, 7 transport the recording paper P in the transport direction by controlling the transport motor 67. Then, after completing the recording operation in S212, the control device 80 erases the recording flag stored in the flash memory 84 (S213), and then returns to S101 in FIG. 5.

Returning to FIG. 5, when a recording command is received (S102: YES) without receiving a time signal indicating that the specified time has arrived (S101: NO), the control device 80 judges whether or not a recovery flag is stored in the flash memory 84 (S104). If a recovery flag is not stored in the flash memory 84 (S104: NO), the process proceeds to S107. If a recovery flag is stored in the flash memory 84 (S104: YES), the control device 80 performs suction purge as in S210 (S105), erases the recovery flag stored in the flash memory 84 (S106), and then proceeds to S107. The cases in which it is judged that a recovery flag is stored in the flash memory 84 in S104 are, for example, when it is judged that a recovery flag is stored in S206 and that a recording flag is not stored in S208, or when it is judged that a recovery flag is stored in S206 and that the number N of abnormal nozzles is less than the specified value Nt in S209. As a result, in this embodiment, if the control device 80 determines that an abnormal nozzle exists based on the results of the inspection operation, a suction purge will be performed when the first recording command is received after the inspection operation.

In S107, the control device 80 starts the recording operation. After starting the recording operation in S107, the process proceeds to the flow in FIG. 7.

To explain the flow of FIG. 7 in detail, the recording operation continues until the recording operation is completed (S301: NO) unless a time signal indicating that the specified time has arrived is received (S302: NO). When the recording operation is completed (S301: YES), the process returns to S101 in FIG. 5. When a time signal indicating that the specified time has arrived is received during the recording operation (S301: NO) (S302: YES), if the number Mr of recording sheets P on which the recording operation has not been completed is less than the specified number Mt (S303: NO), the control device 80 continues the recording operation until the recording operation is completed (S304: NO), and when the recording operation is completed (S304: YES), the process returns to S103 in FIG. 5.

If the number Mr of sheets of recording paper P on which recording has not been completed is equal to or greater than the predetermined number Mt (S303: YES), the control device 80 interrupts the recording operation (S305) and performs an inspection operation (S306). After the inspection operation is completed, the control device 80 determines whether or not there is an abnormal nozzle based on the signal output from the determination circuit 78 during the inspection operation (S307). If there is no abnormal nozzle (S307: NO), proceed to S313.

If an abnormal nozzle is present (S307: YES), the control device 80 stores a recovery flag in the flash memory 84 (S308) and performs flushing (S309).

Next, based on the signal output from the judgment circuit 78 during the inspection operation, it is judged whether the number N of abnormal nozzles is equal to or greater than the predetermined value Nt (S310). If the number N of abnormal nozzles is less than the predetermined value Nt (S310: NO), proceed directly to S313. If the number N of abnormal nozzles is equal to or greater than the predetermined value Nt (S310: YES), the control device 80 performs suction purging (S311), erases the recovery flag stored in the flash memory 84 (S312), and proceeds to S313. In S313, the control device 80 resumes the interrupted recording operation. Then, the recording operation is continued until the recording operation is completed (S314: NO), and when the recording operation is completed, the process returns to S101 in FIG. 5.

＜Effects＞
In this embodiment, when a time signal indicating a predetermined time has come is received during a printing operation as an inspection instruction signal for inspecting whether or not there is an abnormal nozzle, the printing operation is interrupted and an inspection operation is performed, and the printing operation is resumed after the inspection operation is completed. Furthermore, if there is an abnormal nozzle, a recovery operation is performed after the inspection operation is completed, and then the printing operation is resumed. This allows ink to be ejected properly from the nozzle 10 at least during the resumed printing operation.

In addition, in the first embodiment, when a time signal indicating that a predetermined time has arrived is received during a recording operation, if the number Mr of sheets of recording paper P on which recording has not been completed is large (greater than the predetermined number Mt), the recording operation is interrupted and an inspection operation is performed. This allows ink to be properly ejected from the nozzles 10 at least during the recording operation after it is resumed. On the other hand, if the number Mr of sheets of recording paper P is small (less than the predetermined number Mt), the recording operation is continued and an inspection operation is performed after the recording operation is completed. This allows the recording operation to be completed more quickly.

In addition, in this embodiment, when a recording command is received during an inspection operation, the recording operation is performed after the inspection operation is completed. Also, if an abnormal nozzle is present, a recovery operation is performed after the inspection operation is completed, and then the recording operation is performed. This allows ink to be ejected appropriately from the nozzle 10 during the recording operation.

In addition, in this embodiment, if the condition that an abnormal nozzle is present and the number N of abnormal nozzles is equal to or greater than a predetermined value Nt is met, a suction purge is performed before the recording operation, and if this condition is not met, the recording operation is performed without a suction purge, and the suction purge is performed after the recording operation. In this way, when there is a high need for suction purge, ink can be ejected appropriately from the nozzles 10 by performing a suction purge before the recording operation. On the other hand, when there is a low need for suction purge, the recording operation can be completed sooner by not performing a suction purge before the recording operation.

In addition, in this embodiment, if a recording operation is performed without suction purging, the suction purging operation can be performed immediately before the next recording operation, allowing ink to be appropriately ejected from the nozzles 10 in the next recording operation. Also, if the next recording operation is not performed until the next specified time, the ink required for the recovery operation can be reduced.

In addition, in this embodiment, if an abnormal nozzle is present, flushing, which does not take much time, is performed after the inspection operation is completed, and then the recording operation is performed. This allows the recording operation to be started or resumed quickly, and allows the recording operation to be performed in a state where abnormal nozzles that can be recovered by flushing have been recovered. Furthermore, by performing a suction purge after the recording operation is completed, the abnormal nozzles can be reliably recovered.

In addition, in this embodiment, a time signal indicating that a specified time has arrived is received as an inspection instruction signal, so that an inspection operation can be performed each time the specified time arrives. Furthermore, there is no relationship between the timing of the specified time (the timing of receiving the time signal indicating that the specified time has arrived) and the timing of the ejection operation. Therefore, in this embodiment, a time signal indicating that a specified time has arrived may be received in the middle of a recording operation. Furthermore, a recording command may be received in the middle of an inspection operation.

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

In the above embodiment, when a time signal indicating that a predetermined time has come is received during recording, the decision as to whether to interrupt the recording operation and perform an inspection operation is made depending on whether the number Mr of sheets of recording paper P on which recording has not been completed in the current recording operation is equal to or greater than a predetermined number Mt, but this is not limiting.

In the first modification, the control device 80 starts the recording operation in S107 of FIG. 5, and then performs processing according to the flow of FIG. 8. To explain the flow of FIG. 8 in more detail, the control device 80 executes the processing of S301 and S302, as in the above-described embodiment. Then, when a time signal indicating that a predetermined time has arrived is received (S302: YES), if the recording paper P on which recording is currently being performed is the last recording paper P among the recording papers P to be recorded in the recording operation started in S107 (S401: YES), the control device 80 executes the processing of S304, as in the above-described embodiment.

If the recording paper P on which recording is currently being performed is not the last recording paper P among the recording papers P to be recorded on in the recording operation started in S108 (S401: NO), the recording operation continues until recording on the recording paper P currently being recorded on is completed (S402: NO), and when recording on this recording paper P is completed (S402: YES), the same processes of S305 to S314 as in the above embodiment are executed.

In variant 1, when a time signal indicating that a specified time has arrived is received as an inspection instruction signal during a recording operation, after the recording on the currently being recorded on recording paper P is completed and before recording on the next recording paper P, the recording operation is interrupted and an inspection operation is performed. This makes it possible to complete recording on the currently being recorded on recording paper P more quickly.

In addition, in the first modified example, after the completion of recording on the currently being recorded recording paper P and before recording on the next recording paper P, the recording operation is interrupted and an inspection operation is performed, but this is not limited to the above. For example, after a time signal indicating that a predetermined time has been received as an inspection instruction signal, after recording on any other recording paper P is completed, the recording operation may be interrupted and an inspection operation performed before recording on the next recording paper P.

In the second modification, the control device 80 starts the recording operation in S107 of FIG. 5, and then performs processing according to the flow of FIG. 9. To explain the flow of FIG. 9 in more detail, the control device 80 executes the processes of S301 and S302, as in the above-described embodiment. Then, when a time signal indicating that a predetermined time has arrived is received (S302: YES), the control device 80 continues the recording operation as long as the recording operation is not completed (S501: NO) and it is not a waiting time during the recording operation (hereinafter sometimes simply referred to as "waiting time") (S502: NO).

The standby time is, for example, a standby time provided each time a predetermined number of recording passes are performed, or each time a predetermined number of sheets of recording paper P are recorded, in order to lower the temperature of the inkjet head 4 that has risen due to driving in a recording pass. The standby time also includes a state in which recording cannot continue due to a paper shortage or an error.

When the recording operation is completed (S501: YES), the process proceeds to S103 in FIG. 5. When the standby time has elapsed (S502: YES), the control device 80 executes the same processes of S305 to S314 as in the above embodiment.

In the second modification, when a time signal indicating that a predetermined time has come is received as an inspection instruction signal during a recording operation, the recording operation is interrupted during a waiting time provided during the recording operation to perform an inspection operation. This allows at least a part of the inspection operation to be performed during the waiting time, and makes it possible to minimize the time until the recording operation is completed while still performing the inspection operation.

In addition, in the above-described embodiment and modified examples 1 and 2, when a time signal indicating that a specified time has arrived is received as an inspection instruction signal during a recording operation, whether or not to interrupt the recording operation and perform an inspection operation is determined depending on the status of the currently ongoing recording operation, but this is not limited to the above. For example, when a time signal indicating that a specified time has arrived is received during a recording operation, the recording operation may be immediately interrupted and an inspection operation may be performed regardless of the status of the currently ongoing recording operation.

In addition, in the above embodiment, when a recording operation is performed after an inspection operation (the processes of S212 and S313 are executed) and an abnormal nozzle is present, whether or not to perform suction purging before the recording operation is determined based on whether the number N of abnormal nozzles is equal to or greater than a uniform predetermined value Nt, but this is not limited to the above.

In variant 3, the printer is capable of selectively recording in either low-image-quality mode or high-image-quality mode, and the recording command includes information indicating which image-quality mode to record in. Also, a table is stored in flash memory 84, as shown in FIG. 10, in which image-quality modes are associated with a predetermined value Nt. The predetermined value Nt2 associated with the low-image-quality mode is greater than the predetermined value Nt1 associated with the high-image-quality mode.

In Modification 3, as in the above-described embodiment, the control device 80 also performs processing in accordance with the flow charts in FIGS. 5 to 7. However, unlike the above-described embodiment, Modification 3 determines in S308 and S310 whether the number N of abnormal nozzles is equal to or greater than a predetermined value Nt (Nt1 or Nt2) set based on the table in FIG. 10. In Modification 3, the condition that the number N of abnormal nozzles is equal to or greater than the predetermined value Nt set based on the table in FIG. 10 corresponds to the "predetermined condition" of the present invention.

In variant 3, if the condition that an abnormal nozzle is present and the number N of abnormal nozzles is equal to or greater than a predetermined value Nt set based on the image quality mode is met, then suction purging is performed before the recording operation, and if this condition is not met, then the recording operation is performed without suction purging. In this way, when there is a high need for suction purging, ink can be ejected appropriately from the nozzles 10 by performing suction purging before the recording operation. On the other hand, when there is a low need for suction purging, the recording operation can be completed sooner by not performing suction purging before the recording operation.

Furthermore, the predetermined conditions for determining whether or not to perform suction purging before performing a recording operation when an abnormal nozzle is present are not limited to those in the above-described embodiment and modification example 3. The predetermined conditions may be conditions related to the results indicated by the determination signal output from the determination circuit 78 during the inspection operation, other than the number of abnormal nozzles. Alternatively, the predetermined conditions may be conditions related to the results indicated by the determination signal output from the determination circuit 78 during the inspection operation, other than the number of abnormal nozzles, and the image quality mode. The results indicated by the determination signal output from the determination circuit 78 during the inspection operation, other than the number of abnormal nozzles, may be, for example, the distribution of abnormal nozzles.

In the above example, if a recording command is received during an inspection operation and an abnormal nozzle is present, and suction purging is not performed before the recording operation based on that recording command, then when a recording command is first received after the inspection operation, suction purging is performed before the recording operation based on that recording command, but this is not limited to the above.

For example, in a printer that can selectively perform recording in either high-quality mode or low-quality mode, if a recording command is received during an inspection operation and an abnormal nozzle is found, and suction purging is not performed before the recording operation based on the recording command, a recovery operation may be performed when a recording command instructing recording in high-quality mode is first received after the inspection operation. Alternatively, for example, if an abnormal nozzle is found at any time after the inspection operation, the user may be notified of this and be allowed to select whether or not to perform suction purging, and if suction purging is selected, suction purging may be performed.

In the above example, when a recording command is received during an inspection operation and an abnormal nozzle is present, if a predetermined condition is met, suction purging is performed before the recording operation based on the recording command, and if the predetermined condition is not met, suction purging is not performed, but is instead performed after the recording operation based on the recording command. However, this is not limited to this. When a recording command is received during an inspection operation and an abnormal nozzle is present, suction purging may always be performed before the recording operation based on the recording command.

In addition, in the above embodiment, the time signal indicating that a specific time has arrived is received as an inspection instruction signal instructing the nozzle 10 to be inspected to see if it is an abnormal nozzle, but this is not limited to the above.

In the fourth modification, as shown in FIG. 11, the printer 100 is a printer 1 equipped with a timer 101 instead of the clock unit 70. The timer 101 outputs an elapsed time signal indicating the elapsed time since it was reset.

In variant 4, when the printer 100 is first turned on, the control device 80 performs an inspection operation, and when the inspection operation is completed, the control device 80 resets the timer 101. Thereafter, as described below, the control device 80 resets the timer 101 when the inspection operation is completed.

In the fourth modification, the control device 80 performs processing according to the flow in FIG. 12. More specifically, the control device 80 is in standby while it has not received an elapsed time signal (the "inspection instruction signal" of the present invention) from the timer 101 indicating that a predetermined time has elapsed (S601: NO) and while it has not received a recording command (S102: NO).

When the control device 80 receives an elapsed time signal from the timer 101 indicating that a predetermined time has elapsed (S601: YES), it starts the inspection operation (S103) as in the above embodiment, and proceeds to the flow of FIG. 13. When the control device 80 receives a recording command (S102: YES) without receiving an elapsed time signal from the timer 101 indicating that a predetermined time has elapsed (S601: NO), the control device 80 executes the processes of S104 to S107 as in the above embodiment, starts the recording operation in S107, and then proceeds to the flow of FIG. 14.

Regarding the flow of FIG. 13, the control device 80 executes the same processes of S201 to S203 as in the above-mentioned embodiment. Then, when it is determined in S203 that the inspection operation is completed (S203: YES), the control device 80 resets the timer 101 (S701) and executes the same processes of S204 to S213 as in the above-mentioned embodiment. Then, if it is determined in S204 that no abnormal nozzle exists (S204: NO), if it is determined in S205 or S208 that no recording flag is stored in the flash memory 84 (S208: NO), or after erasing the recording flag stored in the flash memory 84 in S213, the process returns to S101 in FIG. 12.

Regarding the flow of FIG. 14, the control device 80 executes the same processes of S301 to S306 as in the above-mentioned embodiment. After completing the inspection operation of S306, the control device 80 resets the timer 101 (S801) and executes the same processes of S307 to S314 as in the above-mentioned embodiment. When it is determined in S304 that the recording operation is complete (S304: YES), the process returns to S103 in FIG. 12. When it is determined in S301 that the recording operation is complete (S301: YES) and when it is determined in S314 that the recording operation is complete (S314: YES), the process returns to S101 in FIG. 12.

In addition, in Modification 4, the control device 80 performs processing according to the flows in Figures 12 to 14, so that the elapsed time signal output from the timer 101 indicates the elapsed time since the last inspection operation was performed. In Modification 3, the inspection operation corresponds to the "predetermined operation" of the present invention.

In the fourth variant, an elapsed time signal indicating that a predetermined time has elapsed since the last inspection operation is performed is received as an inspection instruction signal, so that an inspection operation can be performed each time the predetermined time elapses. Furthermore, the timing at which the predetermined time elapses since the last inspection operation is performed is unrelated to the timing of the ejection operation.

In addition, in variants 1 to 3, an elapsed time signal indicating that a predetermined time has elapsed may be received from timer 101 as an inspection instruction signal.

In addition, in the fourth modified example, the elapsed time signal output from the timer 101 indicates the elapsed time since the last inspection operation was performed, but this is not limited to this. The elapsed time signal output from the timer 101 may indicate, for example, the elapsed time since another predetermined operation, such as a recovery operation, was last performed.

In addition, in the above examples, the inspection instruction signal that is unrelated to the timing of the recording operation is either a time signal indicating that a specific time has arrived, or an elapsed time signal indicating that a specific time has elapsed since the last time a specific operation was performed, but this is not limited to this. The inspection instruction signal may be another signal that is unrelated to the timing of the recording operation.

In the above example, suction purging is performed as the purging, but this is not limited to this. For example, a pressure pump may be provided in the middle of the tube 15 connecting 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 purging. In this case, the pressure pump for performing the pressure purging and the inkjet head 4 for performing the flushing correspond to the "recovery means" of the present invention.

Furthermore, during purging, both suction by the suction pump 72 and pressurization by the pressurization pump may be performed. In this case, the maintenance unit 8, the pressurization pump, and the inkjet head 4 correspond to the "recovery means" of the present invention.

In addition, in the above example, a uniform suction purge is performed regardless of the number of abnormal nozzles, but this is not limited to the above. For example, a suction purge that discharges more ink may be performed as the number of abnormal nozzles increases.

In the above example, the recovery operation for discharging ink from the nozzle 10 to recover the abnormal nozzle includes flushing and suction purging. If an abnormal nozzle is present, flushing is performed immediately after the inspection operation, and suction purging is performed immediately before the subsequent printing operation, but this is not limited to the above.

For example, flushing may not be performed immediately after the inspection operation, and flushing and suction purging may be performed immediately before the subsequent recording operation. Alternatively, the recovery operation may be only one of suction purging and flushing, and either one of the above may be performed immediately after the inspection operation or immediately before the subsequent recording operation. If the recovery operation is only suction purging, the maintenance unit 8 corresponds to the "recovery means" of the present invention. If the recovery operation is only flushing, the inkjet head 4 corresponds to the "recovery means" of the present invention.

In the above embodiment, 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 determination circuit 78 during the inspection drive.

In addition, in the above embodiment, the determination 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.

For example, a detection electrode extending vertically may be disposed, and a determination 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 an area 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 the optical sensor may output a signal indicating whether or not the nozzle is abnormal.

Alternatively, for example, as described in Patent No. 4929699, a voltage detection circuit (the "signal output unit" of the present invention) that detects the change in voltage when ink is ejected from the nozzles may 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 may be output from the voltage detection circuit to the control device 80.

Alternatively, for example, 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 in order to eject ink, a second applied voltage may be applied to drive the heater so that ink is not ejected, and a signal may be 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.

In addition, in the above example, the signal output unit outputs a signal corresponding to whether or not ink has been ejected from the nozzle 10, but this is not limited to the above. For example, a signal output unit may be provided that outputs a signal corresponding to whether or not an abnormality other than the nozzle 10 not ejecting ink has occurred, and whether or not the nozzle 10 is an abnormal nozzle may be determined based on the signal from the signal output unit. An abnormality other than the nozzle not ejecting ink may be, for example, an abnormality in the direction of ink ejection.

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

Although the above describes an example in which the present invention is applied to a printer that ejects ink from a nozzle to record on recording paper P, the present invention is not limited to this. It can also be applied to printers that record images on recording media other than recording paper, such as T-shirts, sheets for outdoor advertising, cases for mobile devices such as smartphones, cardboard, and plastic members. It can also be applied to liquid ejection devices that eject liquids other than ink, such as liquid resins and metals.

REFERENCE SIGNS LIST 1 Printer 4 Inkjet head 8 Maintenance unit 10 Nozzle 70 Clock section 72 Suction pump 76 Detection electrode 77 High voltage power supply circuit 78 Determination circuit 79 Resistor 80 Control device 84 Flash memory 100 Printer 101 Timer

Claims (8)

a liquid ejection head having a plurality of nozzles for ejecting liquid onto an ejection receiving medium;
a signal output section that outputs a determination signal corresponding to whether or not the nozzle is an abnormal nozzle when the liquid ejection head is driven for inspection to confirm whether or not the nozzle is an abnormal nozzle 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:
a discharge instruction signal that instructs the liquid discharge head to perform a discharge operation to discharge liquid from the plurality of nozzles, and a test instruction signal that is received regardless of the timing of the discharge operation and that instructs the liquid discharge head to test whether the nozzle is an abnormal nozzle;
When the ejection instruction signal is received, the liquid ejection head is caused to perform the ejection operation.
When the inspection command signal is received, the liquid ejection head is caused to perform an inspection operation in which the inspection drive is performed in sequence for at least two nozzles among the plurality of nozzles;
When the inspection instruction signal is received during the ejection operation, if the number of ejection receiving media to which the liquid has not been ejected is equal to or greater than a predetermined number,
causing the liquid ejection head to suspend the ejection operation and perform the inspection operation, and causing the liquid ejection head to resume the ejection operation after the inspection operation is completed;
moreover,
After the inspection operation is completed, if the determination signal output from the signal output unit during the inspection operation indicates that an abnormal nozzle exists,
After the inspection operation is completed, the recovery means is caused to perform the recovery operation, and then the liquid ejection head is caused to resume the ejection operation.
When the inspection instruction signal is received during the ejection operation, if the number of ejection receiving media to which the liquid has not been ejected is less than a predetermined number in the ejection operation,
a liquid ejection head that continues the ejection operation and, after the ejection operation is completed, causes the liquid ejection head to perform the inspection operation. a liquid ejection head having a plurality of nozzles for ejecting liquid onto an ejection receiving medium;
a signal output section that outputs a determination signal corresponding to whether or not the nozzle is an abnormal nozzle when the liquid ejection head is driven for inspection to confirm whether or not the nozzle is an abnormal nozzle 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:
a discharge instruction signal that instructs the liquid discharge head to perform a discharge operation to discharge liquid from the plurality of nozzles, and a test instruction signal that is received regardless of the timing of the discharge operation and that instructs the liquid discharge head to test whether the nozzle is an abnormal nozzle;
When the ejection instruction signal is received, the liquid ejection head is caused to perform the ejection operation.
When the inspection command signal is received, the liquid ejection head is caused to perform an inspection operation in which the inspection drive is performed in sequence for at least two nozzles among the plurality of nozzles;
when the ejection instruction signal is received during the inspection operation, the ejection operation is performed by the liquid ejection head after the inspection operation is completed;
moreover,
After the inspection operation is completed, if the determination signal output from the signal output unit during the inspection operation indicates that an abnormal nozzle exists,
a recovery unit that recovers the liquid after the inspection operation is completed, and then the liquid discharge head is caused to perform the discharge operation. The control device includes:
After the inspection operation is completed, if the determination signal output from the signal output unit during the inspection operation indicates that an abnormal nozzle exists,
When a condition other than the presence of the abnormal nozzle is satisfied, the predetermined condition regarding the determination signal output from the signal output unit during the inspection operation is satisfied.
After the inspection operation is completed, the recovery means is caused to perform the recovery operation, and then the liquid ejection head is caused to perform the ejection operation.
If the above-mentioned conditions are not met,
After the inspection operation is completed, the recovery unit is not caused to perform the recovery operation, and the liquid discharge head is caused to perform the discharge operation.
3. The liquid ejection apparatus according to claim 1, wherein the recovery unit is caused to perform the recovery operation after the ejection operation. the ejection operation is an operation of recording an image on a liquid receiving medium by ejecting liquid from the plurality of nozzles of the liquid ejection head toward the liquid receiving medium,
The control device includes:
Selectively performing the liquid ejection operation in one of a plurality of image quality modes related to the image quality of the image to be recorded;
When the determination signal output from the signal output unit during the inspection operation indicates that an abnormal nozzle exists,
When a condition other than the presence of the abnormal nozzle is satisfied, the condition satisfies a predetermined condition related to the judgment signal output from the signal output unit during the inspection operation and the image quality mode,
After the inspection operation is completed, the recovery means is caused to perform the recovery operation, and then the liquid ejection head is caused to perform the ejection operation.
If the above-mentioned conditions are not met,
After the inspection operation is completed, the recovery unit is not caused to perform the recovery operation, and the liquid discharge head is caused to perform the discharge operation.
4. The liquid ejection apparatus according to claim 3, wherein the recovery means performs the recovery operation after the ejection operation. The control device includes:
A liquid ejection device as described in claim 3 or 4, characterized in that if the liquid ejection head is caused to perform the ejection operation without the recovery means performing the recovery operation, the next time the ejection instruction signal is received, the recovery means is caused to perform the recovery operation and then the ejection operation is performed. a liquid ejection head having a plurality of nozzles for ejecting liquid onto an ejection receiving medium;
a signal output section that outputs a determination signal corresponding to whether or not the nozzle is an abnormal nozzle when the liquid ejection head is driven for inspection to confirm whether or not the nozzle is an abnormal nozzle 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 control device,
The control device includes:
a discharge instruction signal that instructs the liquid discharge head to perform a discharge operation to discharge liquid from the plurality of nozzles, and a test instruction signal that is received regardless of the timing of the discharge operation and that instructs the liquid discharge head to test whether the nozzle is an abnormal nozzle;
When the ejection instruction signal is received, the liquid ejection head is caused to perform the ejection operation.
When the inspection command signal is received, the liquid ejection head is caused to perform an inspection operation in which the inspection drive is performed in sequence for at least two nozzles among the plurality of nozzles;
When the inspection instruction signal is received during the discharge operation,
causing the liquid ejection head to stop the ejection operation and perform the inspection operation;
After the inspection operation is completed, the liquid ejection head is caused to resume the ejection operation.
moreover,
After the inspection operation is completed, if the determination signal output from the signal output unit during the inspection operation indicates that an abnormal nozzle exists,
After the inspection operation is completed, the recovery means is caused to perform the recovery operation, and then the liquid ejection head is caused to resume the ejection operation.
The liquid ejection device according to claim 1, wherein the inspection instruction signal is a time signal indicating that a predetermined time has come. The recovery means includes:
The liquid ejection head;
a pump connected to the liquid ejection head;
The recovery operation includes:
flushing the liquid ejection head to discharge liquid from the nozzles;
and purging the liquid in the liquid ejection head through the nozzles by driving the pump.
The control device includes:
A liquid ejection device as described in any one of claims 1 to 6, characterized in that when the judgment signal output from the signal output unit during the inspection operation indicates the presence of an abnormal nozzle, after the inspection operation is completed, the liquid ejection head is made to perform the flushing and then the ejection operation, and after the ejection operation is completed, the pump is made to perform the purging. a timer that outputs an elapsed time signal indicating an elapsed time since a predetermined operation was last performed in the liquid ejection device;
8. The liquid ejection device according to claim 1, wherein the inspection instruction signal is an elapsed time signal indicating that the elapsed time has reached a predetermined time.

Images