Ink jet printer and control method for ink jet printer

Abstract

To provide an ink jet printer enabling an operator to easily recognize that a defect of ink supply from a main tank to a supplied side tank is occurring.SOLUTION: An ink jet printer 1 performs error processing when an increase amount, in a prescribed time, of the ink of a main tank 13 calculated at regular time intervals reaches a first reference amount or more than once in a row during ink circulation circulating the ink between the main tank 13 and a supplied tank 12, calculates a change amount of ink in the main tank 13 at regular time intervals during ink circulation, calculates a difference between the calculated amount of change and an amount of change calculated anew, stores as an initial amount of ink an amount of ink in the main tank 13 when absolute value of the difference reaches a second reference amount or less more than once in a row, and then performs error processing also when an increased amount of ink in the main tank 13 from the stored initial amount of ink reaches a third reference amount.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an inkjet printer for printing on a medium, and also to a method for controlling such an inkjet printer. [Background technology]

[0002] Conventionally, inkjet printers that print on media such as paper are known (see, for example, Patent Document 1). The inkjet printer described in Patent Document 1 includes an inkjet head that ejects ink, a main tank that contains the ink, and an ink supply system that supplies ink from the main tank to the inkjet head. The main tank is, for example, an ink container that can be removed from the inkjet printer and replaced.

[0003] In the inkjet printer described in Patent Document 1, the ink supply system includes a sub-tank located midway along the ink supply path from the main tank to the inkjet head, a supply flow path through which ink flows from the main tank to the sub-tank, a circulation path through which ink flows from the sub-tank to the main tank, a pump for causing ink to flow in the supply path, and a pump for causing ink to flow in the circulation path. The supply flow path and the circulation path are, for example, tubes through which ink flows. In the inkjet printer described in Patent Document 1, it is possible to circulate ink between the main tank and the sub-tank, thereby making it possible to suppress settling of ink particles in the main tank and the sub-tank. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-7061 Summary of the Invention [Problem to be solved by the invention]

[0005] In the inkjet printer described in Patent Document 1, when the main tank is an ink container that can be replaced, for example, if a connection failure occurs where the supply channel is not properly connected to the main tank after replacement, the amount of ink flowing from the main tank to the sub-tank decreases, and there is a risk of a poor ink supply where the ink is not properly supplied from the main tank to the sub-tank. In the inkjet printer described in Patent Document 1, if this poor ink supply occurs, it may cause problems in printing on the medium.

[0006] Also, in the inkjet printer described in Patent Document 1, when this poor ink supply occurs, when the ink is circulated between the main tank and the sub-tank, an appropriate amount of ink flows into the main tank while the amount of ink flowing out of the main tank decreases, so there is a risk of ink overflowing from the main tank. Therefore, in the inkjet printer described in Patent Document 1, it is preferable that it is easy for the operator of the inkjet printer to recognize that a poor ink supply has occurred where the ink is not properly supplied from the main tank to the sub-tank.

[0007] Therefore, an object of the present invention is to provide an inkjet printer including a main tank that stores ink, and a supplied-side tank that is disposed on the inkjet head side from the main tank in a piping path between the main tank and the inkjet head and stores ink supplied from the main tank, and that can easily make an operator recognize that a poor ink supply has occurred where the ink is not properly supplied from the main tank to the supplied-side tank. Another object of the present invention is to provide a control method for an inkjet printer including a main tank and a supplied-side tank that stores ink supplied from the main tank, and that can easily make an operator recognize that a poor ink supply has occurred where the ink is not properly supplied from the main tank to the supplied-side tank.

Means for Solving the Problems

[0008] In order to solve the above problems, an inkjet printer according to the present invention is an inkjet printer including an inkjet head that discharges ink. The inkjet printer includes a main tank that stores ink, a supply-side tank that is disposed closer to the inkjet head than the main tank in a piping path between the main tank and the inkjet head and stores ink supplied from the main tank, a pump for circulating ink between the main tank and the supply-side tank, a first piping path that is a supply piping path through which ink flows from the main tank toward the supply-side tank, a second piping path that is a circulation piping path in which the pump is disposed and through which ink flows from the supply-side tank toward the main tank, a detection mechanism for detecting the amount of ink stored in the main tank, and a control unit for controlling the inkjet printer. The control unit calculates, at a predetermined first constant time interval based on the detection result of the detection mechanism, an increase amount of the ink in the main tank over a first constant time during ink circulation when driving the pump to circulate ink between the main tank and the supply-side tank. When the calculated increase amount becomes equal to or greater than a predetermined first reference amount continuously for a plurality of times, the control unit executes a predetermined error process. During ink circulation, the control unit calculates, at a predetermined second constant time interval based on the detection result of the detection mechanism, a change amount of the ink in the main tank over a second constant time, calculates an ink change amount difference, which is a difference between the change amount of the ink in the main tank over the second constant time calculated last time and the change amount of the ink in the main tank over the second constant time calculated this time, at the second constant time interval, stores the amount of ink in the main tank when the absolute value of the calculated ink change amount difference becomes equal to or less than a predetermined second reference amount, which is less than the first reference amount, continuously for a plurality of times, as an initial ink amount, and then executes an error process even when the increase amount of the ink in the main tank from the stored initial ink amount becomes equal to or greater than a predetermined third reference amount, which is greater than the first reference amount.

[0009] Also, in order to solve the above problems, a control method for an inkjet printer according to the present invention includes an inkjet head that discharges ink, a main tank that stores ink, a supplied-side tank that is disposed closer to the inkjet head than the main tank in a piping path between the main tank and the inkjet head and stores ink supplied from the main tank, a pump for circulating ink between the main tank and the supplied-side tank, a first piping path that is a supply piping path through which ink flows from the main tank toward the supplied-side tank, a second piping path that is a circulation piping path in which the pump is disposed and through which ink flows from the supplied-side tank toward the main tank, and a detection mechanism for detecting the amount of ink stored in the main tank. The control method for the inkjet printer is characterized in that, during ink circulation in which the pump is driven to circulate ink between the main tank and the supplied-side tank, an increase amount of ink in the main tank over a first fixed time is calculated at a predetermined first fixed time interval based on the detection result of the detection mechanism, and when the calculated increase amount continuously exceeds a predetermined first reference amount a plurality of times, a predetermined error process is executed. Also, during ink circulation, a change amount of ink in the main tank over a second fixed time is calculated at a predetermined second fixed time interval based on the detection result of the detection mechanism, and an ink change amount difference, which is a difference between the change amount of ink in the main tank over the second fixed time calculated last time and the change amount of ink in the main tank over the second fixed time calculated this time, is calculated at the second fixed time interval. When the absolute value of the calculated ink change amount difference continuously becomes equal to or less than a predetermined second reference amount that is less than the first reference amount a plurality of times, the amount of ink in the main tank at that time is stored as an initial ink amount. Thereafter, even when the increase amount of ink in the main tank from the stored initial ink amount becomes a predetermined third reference amount that is greater than the first reference amount, an error process is executed.

[0010] In the present invention, during ink circulation in which ink is circulated between the main tank and the supply-side tank, the increase amount of the ink in the main tank over a first fixed time is calculated at a first fixed time interval based on the detection result of the detection mechanism. When the calculated increase amount becomes equal to or more than a first reference amount a plurality of times continuously, a predetermined error process is executed. Further, during ink circulation, the change amount of the ink in the main tank over a second fixed time is calculated at a second fixed time interval based on the detection result of the detection mechanism. An ink change amount difference, which is the difference between the change amount of the ink in the main tank over the second fixed time calculated last time and the change amount of the ink in the main tank over the second fixed time calculated this time, is calculated at the second fixed time interval. When the absolute value of the calculated ink change amount difference becomes equal to or less than a second reference amount, which is less than the first reference amount, a plurality of times continuously, the amount of ink in the main tank at that time is stored as an initial ink amount. After that, even when the increase amount of the ink in the main tank from the stored initial ink amount becomes equal to or more than a third reference amount, which is more than the first reference amount, an error process is executed.

[0011] That is, in the present invention, an error process is executed when the increase amount of the ink in the main tank over a first fixed time becomes equal to or more than a first reference amount a plurality of times continuously and when the increase amount of the ink from the initial ink amount, which is the amount of ink in the main tank stored at a predetermined timing, becomes equal to or more than a third reference amount. Therefore, in the present invention, it becomes possible to easily make an operator recognize that there is an ink supply failure in which ink is not appropriately supplied from the main tank to the supply-side tank.

[0012] In the present invention, when the amount of ink increase in the main tank within a first fixed time continuously exceeds a first reference amount a plurality of times, and when the amount of ink increase from the ink initial amount stored at a predetermined timing reaches a third reference amount greater than the first reference amount, error processing is executed. Therefore, it becomes possible to execute error processing while suppressing the influence of errors in the detection mechanism and noise on the detection mechanism. Accordingly, in the present invention, it becomes possible to accurately make the operator recognize that there is a supply failure of ink from the main tank to the supply destination tank.

[0013] Furthermore, in the present invention, when the amount of ink increase in the main tank within a first fixed time continuously exceeds a first reference amount a plurality of times, error processing is executed. Therefore, when the degree of decrease in the amount of ink supplied from the main tank to the supply destination tank is large and the amount of ink in the main tank increases significantly in a relatively short time, it becomes possible to make the operator recognize in a short time that there is a supply failure of ink from the main tank to the supply destination tank.

[0014] In the present invention, when the amount of ink increase from the ink initial amount stored at a predetermined timing reaches a third reference amount, error processing is executed. Therefore, even when the degree of decrease in the amount of ink supplied from the main tank to the supply destination tank is small and the amount of ink in the main tank does not increase significantly in a relatively short time, although there is a supply failure of ink from the main tank to the supply destination tank, it becomes possible to make the operator recognize that there is a supply failure of ink from the main tank to the supply destination tank.

[0015] In the present invention, the change amount of the ink in the main tank over a second fixed time interval is calculated. Also, an ink change amount difference, which is the difference between the previously calculated change amount of the ink in the main tank over the second fixed time and the currently calculated change amount of the ink in the main tank over the second fixed time, is calculated at the second fixed time interval. Since the absolute value of the calculated ink change amount difference becomes less than or equal to a second reference amount continuously for a plurality of times, the amount of ink in the main tank at that time is stored as the initial ink amount. Therefore, it becomes possible to store the amount of ink in the main tank when no disturbance or the like has occurred in the main tank (i.e., when the state of the main tank is stable) as the initial ink amount. That is, in the present invention, it becomes possible to accurately set the initial ink amount. Accordingly, in the present invention, based on the accurately set initial ink amount, it becomes possible to accurately cause the operator to recognize that there is a supply failure of the ink from the main tank to the supply-side tank.

[0016] In the present invention, for example, the main tank can be removed from the inkjet printer and is replaceable. In this case, there is a high possibility that a connection failure or the like may occur where the replaced main tank is not properly connected to the first piping path, resulting in a supply failure of the ink from the main tank to the supply-side tank. However, in the present invention, even if a supply failure of the ink from the main tank to the supply-side tank occurs, it becomes possible to easily cause the operator to recognize that there is a supply failure of the ink from the main tank to the supply-side tank.

[0017] In the present invention, an inkjet printer includes, for example, a sub-tank that stores ink supplied to an inkjet head, a buffer tank as a supply-side tank that stores ink supplied to the sub-tank and is supplied from a main tank, a first on-off valve, and a second on-off valve. In the middle of a piping path connecting the buffer tank and the sub-tank, a connection point is provided where the other end of a piping path connected to the main tank is connected. The second piping path is constituted by a third piping path that is a piping path between the buffer tank and the connection point and a fourth piping path that is a piping path between the connection point and the main tank. The pump is disposed in the third piping path, the first on-off valve is disposed in a piping path between the connection point and the sub-tank, the second on-off valve is disposed in the fourth piping path. When the second on-off valve is opened and the pump is driven with the first on-off valve closed, ink flows from the buffer tank toward the main tank. When the first on-off valve is opened and the pump is driven with the second on-off valve closed, ink flows from the buffer tank toward the sub-tank.

[0018] In this case, it becomes possible to supply ink to the sub-tank and circulate ink between the main tank and the supply-side tank by a common pump. Therefore, it becomes possible to simplify the configuration of the inkjet printer. Also, in this case, since the buffer tank is disposed in the piping path between the main tank and the sub-tank, it becomes possible to supply ink from the buffer tank to the sub-tank even during the replacement operation of the main tank. Therefore, it becomes possible to continue the printing operation of the inkjet printer even during the replacement operation of the main tank. Also, in this case, it becomes possible to easily make the operator recognize that a supply failure of ink from the main tank to the buffer tank has occurred.

[0019] In the present invention, an inkjet printer includes, for example, an ink filter disposed in the third piping path, and ink is supplied from the main tank to the buffer tank by a head difference.

[0020] In this case, since the ink filter is disposed in the third piping path, depending on the state of the ink filter (specifically, the degree of clogging of the ink filter), the amount of ink circulating between the main tank and the buffer tank during ink circulation may decrease, and even though a poor supply of ink from the main tank to the supply-side tank has occurred, the amount of ink in the main tank may not increase significantly in a relatively short period of time. However, in the present invention, even when the amount of ink in the main tank does not increase significantly in a relatively short period of time, it is possible to cause the operator to recognize that a poor supply of ink from the main tank to the supply-side tank has occurred.

[0021] Also, in this case, since ink is supplied from the main tank to the buffer tank due to a head difference, if air enters the first piping path when one end of the first piping path is connected to the main tank, the air that has entered may remain in the first piping path, and there is a risk that a poor supply of ink from the main tank to the buffer tank may occur. On the other hand, even if this poor supply occurs, since the degree of decrease in the amount of ink supplied from the main tank to the buffer tank is small, the amount of ink in the main tank does not increase significantly in a relatively short period of time. However, in the present invention, even when the amount of ink in the main tank does not increase significantly in a relatively short period of time, it is possible to cause the operator to recognize that a poor supply of ink from the main tank to the buffer tank has occurred.

Advantages of the Invention

[0022] As described above, in the present invention, in an inkjet printer including a main tank in which ink is stored, and a supply-side tank that is disposed closer to the inkjet head than the main tank in a piping path between the main tank and the inkjet head and stores ink supplied from the main tank, it is possible to easily cause the operator to recognize that a poor supply of ink has occurred in which ink is not appropriately supplied from the main tank to the supply-side tank.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0024] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0025] (Configuration of Inkjet Printer) FIG. 1 is a schematic diagram for explaining the configuration of an inkjet printer 1 according to an embodiment of the present invention. FIG. 2 is a schematic diagram for explaining the configuration of the inkjet printer 1 shown in FIG. 1. FIG. 3 is a block diagram for explaining the configuration of the inkjet printer 1 shown in FIG. 1.

[0026] The inkjet printer 1 of this embodiment (hereinafter referred to as "printer 1") is, for example, an inkjet printer for business use and performs printing on a medium 2 such as paper. The printer 1 includes an inkjet head 3 (hereinafter referred to as "head 3") that discharges ink, a carriage 4 on which the head 3 is mounted, a carriage drive mechanism 5 that moves the carriage 4 in the main scanning direction, a guide rail 6 for guiding the carriage 4 in the main scanning direction, and a platen 7 on which the medium 2 is placed during printing. When printing on the medium 2 with the printer 1, the head 3 discharges ink while the carriage 4 reciprocates in the main scanning direction.

[0027] Further, the printer 1 includes a sub-tank 11 that stores the ink supplied to the head 3, a buffer tank 12 that stores the ink supplied to the sub-tank 11, and a main tank 13 that stores the ink supplied to the buffer tank 12. In this embodiment, for example, one buffer tank 12 is connected to one main tank 13. Also, for example, two sub-tanks 11 are connected to one buffer tank 12, and the ink is supplied from one buffer tank 12 to the two sub-tanks 11. Although one main tank 13 is shown in FIG. 2, the printer 1 includes a plurality of main tanks 13. The printer 1 includes a plurality of buffer tanks 12 and sub-tanks 11 corresponding to the number of main tanks 13.

[0028] Furthermore, the printer 1 includes a pump (liquid feeding pump) 14 and an ink filter 15 (hereinafter referred to as "filter 15") disposed in the piping path between the buffer tank 12 and the sub-tank 11, a detection mechanism 16 for detecting the amount of ink stored in the main tank 13, and a control unit 17 for controlling the printer 1. The printer 1 also includes a piping path 19 connecting the main tank 13 and the buffer tank 12, a piping path 20 connecting the buffer tank 12 and the pump 14, a piping path 21 connecting the pump 14 and the two sub-tanks 11, a piping path 22 connecting the piping path 21 and the main tank 13, an on-off valve 23 disposed in the piping path 19, an on-off valve 24 disposed in the piping path 21, and an on-off valve 25 disposed in the piping path 22.

[0029] In addition, the printer 1 includes an ink filter 27 (hereinafter referred to as "filter 27") disposed in the piping path between the sub-tank 11 and the head 3, a deaeration module 28 for removing gas in the ink, and a pressure adjustment mechanism (not shown) for adjusting the pressure in the sub-tank 11. The deaeration module 28 is disposed in the piping path between the sub-tank 11 and the filter 27. The pressure adjustment mechanism includes a negative pressure (negative pressure) pump for making the inside of the sub-tank 11 a negative pressure, a positive pressure (positive pressure) pump for making the inside of the sub-tank 11 a positive pressure, and the like.

[0030] In the middle of the piping path 21, a connection point (connection location) 30 is provided where the other end of the piping path 22 that is connected to the main tank 13 at one end is connected. That is, a connection point 30 is provided in the middle of the piping path connecting the buffer tank 12 and the sub-tank 11. In this embodiment, a circulation piping path 32 through which ink flows from the buffer tank 12 toward the main tank 13 is formed by the piping path 31 between the buffer tank 12 and the connection point 30 and the piping path 22 between the connection point 30 and the main tank 13.

[0031] The pipe path 32 of this embodiment is the second pipe path, the pipe path 31 is the third pipe path, and the pipe path 22 is the fourth pipe path. Also, the pipe path 19 of this embodiment is the first pipe path, which is a supply pipe path through which ink flows from the main tank 13 toward the buffer tank 12. The pump 14 and the filter 15 are arranged in the pipe path 32, which is the second pipe path. Specifically, the pump 14 and the filter 15 are arranged in the pipe path 31, which is the third pipe path. Also, the filter 15 is arranged in the pipe path 20.

[0032] The two sub-tanks 11 connected to one buffer tank 12 are connected in parallel to the pump 14 via the pipe path 21. The pipe path 21 branches on the sub-tank 11 side from the connection point 30. The on-off valve 24 is arranged in the pipe path between the branch point of the pipe path 21 and the sub-tank 11, and two on-off valves 24 are arranged in the pipe path 21. That is, the on-off valve 24 is arranged in the pipe path between the connection point 30 and the sub-tank 11. The on-off valve 24 of this embodiment is the first on-off valve. Also, the on-off valve 25 of this embodiment is the second on-off valve arranged in the pipe path 22, which is the fourth pipe path.

[0033] The sub-tank 11 is mounted on the carriage 4. The main tank 13 is, for example, a hard ink bottle formed of resin. The main tank 13 stores ink that is supplied to the head 3 via the buffer tank 12 and the sub-tank 11 and ejected from the head 3. The capacity of the main tank 13 is, for example, 10 liters. The main tank 13 can be removed from the printer 1 and replaced. When the ink in the main tank 13 runs out, the main tank 13 is replaced. One end of the pipe path 19 is connected to the main tank 13 via the joint 33. One end of the pipe path 22 (that is, one end of the pipe path 32) is connected to the main tank 13 via the joint 34. At the joints 33 and 34, it is possible to disconnect the main tank 13 from the pipe paths 19 and 22.

[0034] The buffer tank 12 is an ink pack formed in a bag shape. The buffer tank 12 includes a bag-shaped tank body composed of a flexible film, and an ink inlet and an outlet attached to the tank body. The buffer tank 12 is, for example, an aluminum pack having an aluminum-made tank body. The capacity of the buffer tank 12 is, for example, 2 liters. Ink is supplied from the main tank 13 to the buffer tank 12 by a head difference. That is, ink is supplied from the main tank 13 to the buffer tank 12 by utilizing the difference in the height of the ink liquid level in the main tank 13 and the height of the ink liquid level in the buffer tank 12. The buffer tank 12 of this embodiment is a tank on the supplied side that stores the ink supplied from the main tank 13, and is arranged on the head 3 side from the main tank 13 in the piping path between the main tank 13 and the head 3.

[0035] The on-off valves 23 to 25 are solenoid valves. The on-off valves 23 to 25 are electrically connected to the control unit 17. In this embodiment, when the pump 14 is driven with the on-off valve 24 open and the on-off valve 25 closed, ink flows from the buffer tank 12 toward the sub-tank 11. Also, when the pump 14 is driven with the on-off valve 25 open and the on-off valve 24 closed, ink flows from the buffer tank 12 toward the main tank 13, and the ink in the buffer tank 12 returns to the main tank 13. Further, when the pump 14 is driven with the on-off valves 23 and 25 open and the on-off valve 24 closed, ink circulates between the main tank 13 and the buffer tank 12.

[0036] In this way, the pump 14 functions to supply ink from the buffer tank 12 to the sub-tank 11 and to circulate the ink between the main tank 13 and the buffer tank 12. The pump 14 is electrically connected to the control unit 17. The detection mechanism 16 is a load cell for detecting the weight of the ink contained in the main tank 13. The detection mechanism 16 includes a sensor 35. The sensor 35 is a strain gauge and is electrically connected to the control unit 17. The control unit 17 calculates the amount of ink contained in the main tank 13 based on the detection result of the detection mechanism 16 (specifically, the detection result of the sensor 35).

[0037] (Control Method of Inkjet Printer) FIG. 4 and FIG. 5 are flowcharts for explaining the procedure for detecting the occurrence of a poor ink supply in which ink is not appropriately supplied from the main tank 13 shown in FIG. 2 to the buffer tank 12. FIG. 6 is a graph for explaining the procedure for detecting the occurrence of a poor ink supply in which ink is not appropriately supplied from the main tank 13 shown in FIG. 2 to the buffer tank 12.

[0038] During the printing of the medium 2, the control unit 17 drives the pump 14 with the on-off valves 23 and 24 open and the on-off valve 25 closed based on the detection result of a detection mechanism (not shown) for detecting the amount of ink contained in the sub-tank 11 to supply ink from the buffer tank 12 to the sub-tank 11. During the printing of the medium 2, ink is supplied from the buffer tank 12 to the sub-tank 11. Therefore, even when the ink in the main tank 13 runs out during the printing of the medium 2 and the replacement operation of the main tank 13 is being performed, ink is supplied from the buffer tank 12 to the sub-tank 11. Note that the replacement operation of the main tank 13 during the printing of the medium 2 is performed after closing the on-off valve 23, and when the replacement operation of the main tank 13 is completed, the on-off valve 23 is opened.

[0039] Also, in the printer 1, in order to suppress the sedimentation of ink particles in the main tank 13 and the buffer tank 12, ink is circulated during a pause in which printing of the medium 2 is not performed and the carriage 4 has stopped for a predetermined time or longer. Specifically, the control unit 17 closes the on-off valve 24 and opens the on-off valves 23 and 25 to form a circulation path for the ink passing through the main tank 13 and the buffer tank 12, and then drives the pump 14 to circulate the ink in this circulation path.

[0040] As described above, in this embodiment, the main tank 13 is replaceable, and when the ink in the main tank 13 runs out, the main tank 13 is replaced. Therefore, for example, if a connection failure occurs in which the piping path 19 is not properly connected to the main tank 13 after replacement (that is, a connection failure in which the main tank 13 and the piping path 19 are not properly connected at the joint 33), the amount of ink flowing out from the main tank 13 to the buffer tank 12 decreases, and there is a possibility that an ink supply failure may occur in which ink is not properly supplied from the main tank 13 to the buffer tank 12.

[0041] Therefore, in this embodiment, when circulating the ink between the main tank 13 and the buffer tank 12 by driving the pump 14 with the on-off valve 24 closed and the on-off valves 23 and 25 open, the control unit 17 detects whether or not an ink supply failure from the main tank 13 to the buffer tank 12 has occurred, and when an ink supply failure from the main tank 13 to the buffer tank 12 occurs, a predetermined error process is executed. Specifically, as shown in the flowchart of FIG. 4, the control unit 17 detects whether or not an ink supply failure from the main tank 13 to the buffer tank 12 has occurred, and when an ink supply failure from the main tank 13 to the buffer tank 12 occurs, an error process is executed.

[0042] That is, when the ink circulation is started, the control unit 17 first calculates the amount of ink in the main tank 13 based on the detection result of the detection mechanism 16 (step S1). After that, when a certain time T1 elapses after the control unit 17 calculates the amount of ink in the main tank 13 in step S1, the control unit 17 calculates the amount of ink in the main tank 13 again based on the detection result of the detection mechanism 16 (steps S2 and S3). In this embodiment, the certain time T1 is 1 minute. Also, in this embodiment, in steps S1 and S3, the control unit 17 calculates the capacity of the ink in the main tank 13 from the weight of the main tank 13 measured by the detection mechanism 16.

[0043] After that, the control unit 17 calculates the increased amount of ink obtained by subtracting the amount of ink calculated in step S1 from the amount of ink calculated in step S3 (step S4). That is, in step S4, the control unit 17 calculates the increased amount of ink in the main tank 13 over a certain time T1. Also, in step S4, the control unit 17 calculates the increased capacity of the ink. After that, the control unit 17 determines whether the increased amount of ink calculated in step S4 is equal to or greater than a predetermined reference amount M1 (step S5). In this embodiment, the capacity of the ink sent from the buffer tank 12 to the main tank 13 by the pump 14 is 90 (cc (ml)) per minute, and the reference amount M1 is 50 (cc), which is about half of the capacity of the ink sent from the buffer tank 12 to the main tank 13 per minute.

[0044] In step S5, when the ink increase amount is equal to or greater than the reference amount M1, the control unit 17 increments a count value indicating the number of times the ink increase amount has become equal to or greater than the reference amount M1 (step S6). That is, in step S6, the control unit 17 increments the count value by one. In the first step S6 after the ink circulation is started, the count value becomes "1". On the other hand, in step S5, when the ink increase amount is less than the reference amount M1, the control unit 17 resets the count value (step S9) and returns to step S2. In step S9, the control unit 17 resets the count value to "0". When returning to step S2, after calculating the amount of ink in the main tank 13 in the previous step S3, the control unit 17 calculates the amount of ink in the main tank 13 again after a certain time T1 has elapsed (steps S2, S3).

[0045] Further, when the control unit 17 increments the count value in step S6, it determines whether the count value is equal to a predetermined reference value V1 (step S7). The reference value V1 is an integer of 2 or more. In this embodiment, the reference value V1 is "3". In step S7, when the count value is not equal to the reference value V1, the process returns to step S2, and after a certain time T1 has elapsed since the control unit 17 calculated the amount of ink in the main tank 13 in the previous step S3, the control unit 17 calculates the amount of ink in the main tank 13 again (steps S2, S3).

[0046] On the other hand, in step S7, when the count value is equal to the reference value V1 (that is, when the ink increase amount calculated in step S4 has been equal to or greater than the reference amount M1 three times in a row), the control unit 17 determines that there is a failure in the supply of ink from the main tank 13 to the buffer tank 12 and executes a predetermined error process (step S8). In step S8, the control unit 17 displays, for example, a predetermined error display on a predetermined display unit 45 such as a display.

[0047] Note that in step S4 after steps S7 and S9, the control unit 17 calculates the increase amount of ink by subtracting the amount of ink calculated in the previous step S3 from the amount of ink calculated in the current step S3. Also, the control of the printer 1 shown in the control flow of FIG. 4 stops when the ink circulation ends (for example, when the ink circulation ends to supply ink from the buffer tank 12 to the sub-tank 11), and then resumes when the ink circulation restarts.

[0048] For example, if the amount of ink in the main tank 13 before starting the ink circulation is 6 liters (i.e., 6000 (cc)), and the increase amount of ink calculated from the first step S4 to the third step S4 after the ink circulation is started is continuously 50 (cc), then the amount of ink in the main tank 13 increases as shown by the straight line L1 in FIG. 6 over time. In this case, error processing is executed 3 minutes after the ink circulation is started.

[0049] In this way, when circulating ink between the main tank 13 and the buffer tank 12, the control unit 17 calculates the increase amount of ink in the main tank 13 at intervals of a certain time T1 based on the detection result of the detection mechanism 16, and executes error processing when the calculated increase amount of ink continuously exceeds a reference amount M1 a plurality of times (specifically, 3 times). The certain time T1 in this embodiment is the first certain time, and the reference amount M1 is the first reference amount.

[0050] Also, in this embodiment, in addition to the above, as shown in the flowchart of FIG. 5, the control unit 17 detects whether there is a supply failure of ink from the main tank 13 to the buffer tank 12, and executes predetermined error processing when a supply failure of ink from the main tank 13 to the buffer tank 12 occurs.

[0051] That is, when the ink circulation is started, the control unit 17 first calculates the amount of ink in the main tank 13 based on the detection result of the detection mechanism 16 (step S11). After that, when a fixed time T2 has elapsed since the control unit 17 calculated the amount of ink in the main tank 13 in step S11, the control unit 17 calculates the amount of ink in the main tank 13 again based on the detection result of the detection mechanism 16 (steps S12 and S13). In this embodiment, the fixed time T2 is 1 minute. Also, in this embodiment, in steps S11 and S13, the control unit 17 calculates the capacity of the ink in the main tank 13 from the weight of the main tank 13 measured by the detection mechanism 16. In this embodiment, since the fixed time T1 and the fixed time T2 are equal, the processes of steps S1 to S3 shown in FIG. 4 become the processes of steps S11 to S13 shown in FIG. 5.

[0052] After that, the control unit 17 calculates and stores the change amount of ink, which is the change amount of the amount of ink calculated in step S13 with respect to the amount of ink calculated in step S11 (step S14). That is, in step S14, the control unit 17 calculates and stores the change amount of the ink in the main tank 13 over a fixed time T2. Also, in step S14, the control unit 17 calculates and stores the change capacity of the ink. After that, when a fixed time T2 has elapsed since the control unit 17 calculated the amount of ink in the main tank 13 in step S13, the control unit 17 calculates the amount of ink in the main tank 13 again based on the detection result of the detection mechanism 16 (steps S15 and S16).

[0053] After that, the control unit 17 calculates the change amount of ink, which is the change amount of the amount of ink calculated in step S16 with respect to the amount of ink calculated in step S13 (step S17). Also, the control unit 17 calculates the ink change amount difference, which is the difference between the change amount of ink calculated and stored in step S14 and the change amount of ink calculated in step S17 (step S18). That is, in step S18, the control unit 17 calculates the ink change amount difference, which is the difference (difference) between the change amount of the ink in the main tank 13 calculated at the previous time over a fixed time T2 and the change amount of the ink in the main tank 13 calculated this time over a fixed time T2.

[0054] Thereafter, the control unit 17 determines whether or not the absolute value of the ink change amount difference calculated in step S18 is equal to or less than a predetermined reference amount M2 (step S19). The reference amount M2 is an amount smaller than the reference amount M1, and in this embodiment, it is 10 (cc). In step S19, when the absolute value of the ink change amount difference is equal to or less than the reference amount M2, the control unit 17 increments a count value indicating the number of times the absolute value of the ink change amount difference has become equal to or less than the reference amount M2 (step S20). That is, in step S20, the control unit 17 increases the count value by one. In the first step S20 after the ink circulation is started, the count value becomes "1".

[0055] On the other hand, in step S20, when the absolute value of the ink change amount exceeds the reference amount M2, the control unit 17 resets the count value (step S22), stores the ink change amount calculated in step S17 (step S23), and then returns to step S15. In step S22, the control unit 17 resets the count value to "0". When returning to step S15, the control unit 17 calculates the amount of ink in the main tank 13 again after a certain time T2 has elapsed after calculating the amount of ink in the main tank 13 in the previous step S16 (steps S15, S16).

[0056] Also, when the control unit 17 increments the count value in step S20, it determines whether the count value is equal to a predetermined reference value V2 (step S24). The reference value V2 is an integer of 2 or more, and in this embodiment, it is "3". In step S24, if the count value is not equal to the reference value V2, the process proceeds to step S23, where the change amount of the ink calculated in step S17 is stored, then returns to step S15. The control unit 17 calculates the amount of ink in the main tank 13 again after a certain time T2 has elapsed since the amount of ink in the main tank 13 was calculated in the previous step S16 (steps S15, S16). On the other hand, in step S24, if the count value is equal to the reference value V2 (that is, when the absolute value of the difference in the ink change amount calculated in step S18 is less than or equal to the reference amount M2 three times in a row), the control unit 17 stores the amount of ink in the main tank 13 at that time as the initial ink amount (step S25).

[0057] Thereafter, when a certain time T2 has elapsed since the control unit 17 calculated the amount of ink in the main tank 13 in step S16, the control unit 17 calculates the amount of ink in the main tank 13 again based on the detection result of the detection mechanism 16 (steps S26, S27). Thereafter, the control unit 17 calculates the increase amount of the ink by subtracting the initial ink amount stored in step S25 from the amount of ink calculated in step S27 (step S28). That is, in step S28, the control unit 17 calculates the increase amount of the ink in the main tank 13 from the initial ink amount. Thereafter, the control unit 17 determines whether the increase amount of the ink calculated in step S28 is equal to or greater than a predetermined reference amount M3 (step S29). The reference amount M3 is greater than the reference amount M1, and in this embodiment, it is 150 (cc).

[0058] In step S29, if the increase amount of ink is less than the reference amount M3, the process returns to step S26. When a fixed time T2 has elapsed since the control unit 17 calculated the amount of ink in the main tank 13 in the previous step S27, the control unit 17 calculates again the amount of ink in the main tank 13 (steps S26, S27). On the other hand, in step S29, if the increase amount of ink is equal to or more than the reference amount M3, the control unit 17 determines that a supply failure of ink from the main tank 13 to the buffer tank 12 has occurred, and executes error processing (step S30). In step S30, the control unit 17 displays a predetermined error display on the display unit 45, for example, in the same manner as in step S8.

[0059] Note that in step S17 after step S23, the control unit 17 calculates the change amount of ink, which is the change amount of the amount of ink calculated in the current step S16 with respect to the amount of ink calculated in the previous step S16. Also, in step S18 after step S23, the control unit 17 calculates the difference in the change amount of ink, which is the difference between the change amount of ink stored in step S23 and the change amount of ink calculated in step S17. That is, in step S18 after step S23, the control unit 17 calculates the difference in the change amount of ink, which is the difference between the change amount of ink in the main tank 13 calculated at the previous fixed time T2 and the change amount of ink in the main tank 13 calculated at the current fixed time T2. Further, the control of the printer 1 shown in the control flow of FIG. 5 is stopped when the ink circulation ends (for example, when the ink circulation ends to supply ink from the buffer tank 12 to the sub-tank 11), and then restarted when the ink circulation restarts.

[0060] For example, the amount of ink in the main tank 13 before starting the ink circulation is 6000 (cc). After the ink circulation is started, if the absolute value of the difference in the ink change amount calculated from the first step S18 to the third step S18 is continuously a certain amount of 10 (cc) or less (specifically, 0), and the amount of ink in the main tank 13 is increasing, then as time passes, the amount of ink in the main tank 13 increases as shown by the straight line L2 in FIG. 6. In this case, the amount of ink in the main tank 13 4 minutes after the ink circulation is started is stored as the initial ink amount. Also, in this case, for example, if the amount of ink in the main tank 13 continues to increase at a certain rate as shown by the straight line L2 in FIG. 6, then 19 minutes after the ink circulation is started, the increase amount of the ink in the main tank 13 from the initial ink amount becomes 150 (cc) (that is, the reference amount M3), and error processing is executed.

[0061] In this way, during the ink circulation, the control unit 17 calculates the change amount of the ink in the main tank 13 at intervals of a certain time T2 based on the detection result of the detection mechanism 16, and calculates the ink change amount difference, which is the difference between the change amount of the ink in the main tank 13 at the certain time T2 calculated last time and the change amount of the ink in the main tank 13 at the certain time T2 calculated this time, at intervals of the certain time T2. Also, the control unit 17 stores the amount of ink in the main tank 13 when the absolute value of the calculated ink change amount difference becomes less than or equal to a reference amount M2, which is less than the reference amount M1, continuously for a plurality of times (specifically, 3 times), as the initial ink amount. Then, when the increase amount of the ink in the main tank 13 from the stored initial ink amount becomes a reference amount M3, which is more than the reference amount M1, error processing is executed. The certain time T2 in this embodiment is the second certain time, the reference amount M2 is the second reference amount, and the reference amount M3 is the third reference amount.

[0062] If the amount of ink in the buffer tank 12 before the start of ink circulation is small, after the start of ink circulation, the amount of ink flowing out from the main tank 13 to the buffer tank 12 may be larger than the amount of ink flowing from the buffer tank 12 to the main tank 13, and the amount of ink in the main tank 13 may decrease. Even when the amount of ink in the main tank 13 decreases after the start of ink circulation, if the absolute value of the ink change amount difference calculated in step S18 is equal to or less than the reference amount M2, the process proceeds to step S20.

[0063] (Main effects of this embodiment) As described above, in this embodiment, when the ink circulation control unit 17 circulates ink between the main tank 13 and the buffer tank 12, when the amount of ink increase in the main tank 13 at a fixed time T1 continuously exceeds the reference amount M1 a plurality of times, and when the amount of ink increase from the initial ink amount in the main tank 13 stored at a predetermined timing reaches the reference amount M3, error processing is executed. Therefore, in this embodiment, it becomes possible for the operator to easily recognize that there is a poor ink supply in which ink is not appropriately supplied from the main tank 13 to the buffer tank 12.

[0064] Also, in this embodiment, when the amount of ink increase in the main tank 13 at a fixed time T1 continuously exceeds the reference amount M1 a plurality of times, and when the amount of ink increase from the initial ink amount stored at a predetermined timing reaches the reference amount M3 which is larger than the reference amount M1, error processing is executed. Therefore, it becomes possible to execute error processing while suppressing the influence of errors in the detection mechanism 16 and noise on the detection mechanism 16. Accordingly, in this embodiment, it becomes possible for the operator to accurately recognize that there is a poor ink supply from the main tank 13 to the buffer tank 12.

[0065] Furthermore, in this embodiment, since error processing is executed when the amount of ink increase in the main tank 13 within a certain time T1 has exceeded the reference amount M1 continuously for a plurality of times, when the degree of decrease in the ink supplied from the main tank 13 to the buffer tank 12 is large and the amount of ink in the main tank 13 increases significantly in a relatively short time, it becomes possible to let the operator recognize in a short time that there is a problem with the ink supply from the main tank 13 to the buffer tank 12.

[0066] That is, for example, even if a connection defect occurs where the main tank 13 after replacement is not properly connected to the piping path 19 and the amount of ink in the main tank 13 increases significantly in a relatively short time, it becomes possible to let the operator recognize in a short time that there is a problem with the ink supply from the main tank 13 to the buffer tank 12. Specifically, for example, as shown in FIG. 6, by executing error processing 3 minutes after starting the ink circulation, it becomes possible to let the operator recognize that there is a problem with the ink supply from the main tank 13 to the buffer tank 12 3 minutes after starting the ink circulation.

[0067] Also, in this embodiment, since error processing is executed when the amount of ink increase from the initially stored ink amount at a predetermined timing reaches the reference amount M3, even if the degree of decrease in the ink supplied from the main tank 13 to the buffer tank 12 is small and the amount of ink in the main tank 13 does not increase significantly in a relatively short time, it becomes possible to let the operator recognize that there is a problem with the ink supply from the main tank 13 to the buffer tank 12. Specifically, for example, as shown by the straight line L2 in FIG. 6, even when the amount of ink in the main tank 13 does not increase significantly in a relatively short time, it becomes possible to let the operator recognize that there is a problem with the ink supply from the main tank 13 to the buffer tank 12.

[0068] Also, in this embodiment, since ink is supplied from the main tank 13 to the buffer tank 12 due to the head difference, when the main tank 13 is replaced (specifically, when connecting the main tank 13 and the piping path 19), if air enters the piping path 19, the air that has entered may remain in the piping path 19, resulting in a possible poor supply of ink from the main tank 13 to the buffer tank 12. On the other hand, even if this supply failure occurs, since the degree of decrease in the ink supplied from the main tank 13 to the buffer tank 12 is small, the amount of ink in the main tank 13 does not increase significantly in a relatively short time. However, in this embodiment, even when the amount of ink in the main tank 13 does not increase significantly in a relatively short time, it is possible to make the operator recognize that there is a poor supply of ink from the main tank 13 to the buffer tank 12.

[0069] Also, in this embodiment, depending on the state of the filter 15 (specifically, the degree of clogging of the filter 15), the amount of ink circulating between the main tank 13 and the buffer tank 12 during ink circulation may decrease, and even though there is a poor supply of ink from the main tank 13 to the buffer tank 12, there may be a case where the amount of ink in the main tank 13 does not increase significantly in a relatively short time. However, in this embodiment, even when the amount of ink in the main tank 13 does not increase significantly in a relatively short time, it is possible to make the operator recognize that there is a poor supply of ink from the main tank 13 to the buffer tank 12.

[0070] In this embodiment, the change amount of the ink in the main tank 13 over a certain period of time T2 is calculated at intervals of the certain period of time T2. Also, an ink change amount difference, which is the difference between the change amount of the ink in the main tank 13 calculated last time over the certain period of time T2 and the change amount of the ink in the main tank 13 calculated this time over the certain period of time T2, is calculated at intervals of the certain period of time T2. Since the amount of ink in the main tank 13 when the absolute value of the calculated ink change amount difference becomes less than or equal to the reference amount M2 for a plurality of consecutive times is stored as the initial ink amount, it becomes possible to store the amount of ink in the main tank 13 when no disturbance or the like has occurred in the main tank 13 (that is, when the state of the main tank 13 is stable) as the initial ink amount. That is, in this embodiment, it becomes possible to set the initial ink amount with high accuracy. Therefore, in this embodiment, based on the accurately set initial ink amount, it becomes possible to accurately let the operator recognize that there is a supply failure of the ink from the main tank 13 to the buffer tank 12.

[0071] In this embodiment, by means of the common pump 14, the supply of the ink from the buffer tank 12 to the sub-tank 11 and the circulation of the ink between the main tank 13 and the buffer tank 12 are carried out. Therefore, in this embodiment, compared with the case where a pump for supplying the ink from the buffer tank 12 to the sub-tank 11 and a pump for circulating the ink between the main tank 13 and the buffer tank 12 are provided separately, it becomes possible to simplify the configuration of the printer 1.

[0072] In this embodiment, the buffer tank 12 is arranged in the piping path between the main tank 13 and the sub-tank 11. Therefore, in this embodiment, even during the replacement operation of the main tank 13, it becomes possible to supply the ink from the buffer tank 12 to the sub-tank 11. Accordingly, in this embodiment, even during the replacement operation of the main tank 13, it becomes possible to continue the printing operation of the printer 1.

[0073] (Other embodiments) The above-described embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

[0074] In the above-described embodiment, the fixed time T1 and the fixed time T2 are equal, but the fixed time T1 and the fixed time T2 do not have to be equal. Further, in the above-described embodiment, the fixed time in step S26 does not have to be the fixed time T2. For example, the fixed time in step S26 may be longer than the fixed time T2. Furthermore, in the above-described embodiment, the reference value V1 may be an integer of "2" or "4" or more, and the reference value V2 may be an integer of "2" or "4" or more. Also, in the above-described embodiment, the pump for supplying ink from the buffer tank 12 to the sub-tank 11 and the pump for circulating the ink between the main tank 13 and the buffer tank 12 may be provided separately.

[0075] In the above-described embodiment, at least one of the on-off valves 23 to 25 may be a manual valve that is manually opened and closed. Also, in the above-described embodiment, the detection mechanism 16 may be a detection mechanism other than a load cell. Furthermore, in the above-described embodiment, the buffer tank 12 does not have to be an ink pack. For example, the buffer tank 12 may be a hard ink bottle formed of resin. Also, in the above-described embodiment, the filter 15 may be disposed on the discharge side of the pump 14.

[0076] In the above-described embodiment, the printer 1 may not include the buffer tank 12. In this case, the sub-tank 11 serves as a tank on the supply side for storing the ink supplied from the main tank 13, and is disposed on the head 3 side rather than the main tank 13 in the piping path between the main tank 13 and the head 3. In this case, the ink may be supplied from the main tank 13 to the sub-tank 11 by a pump, or the ink may be supplied from the main tank 13 to the sub-tank 11 by a head difference. Further, in this case, the ink is circulated between the main tank 13 and the sub-tank 11. The printer 1 includes a pump for sending the ink from the sub-tank 11 toward the main tank 13. That is, the printer 1 includes a pump for circulating the ink between the main tank 13 and the sub-tank 11.

[0077] In the above-described embodiment, the printer 1 may include a pump disposed in the piping path 19. In this case, the ink is supplied from the main tank 13 to the buffer tank 12 by this pump. Further, in this case, the printer 1 may not include the on-off valve 23. Further, in the above-described embodiment, the printer 1 is a device for performing printing on the medium 2, but the printer 1 may be used for applications other than printing on the medium 2. For example, the printer 1 may be a 3D printer for forming a three-dimensional object. Further, the printer 1 may be an inkjet printer for general consumers.

Description of Reference Numerals

[0078] 1 Printer (Inkjet Printer) 3 Head (Inkjet Head) 11 Sub-tank 12 Buffer Tank (Tank on the Supply Side) 13 Main Tank 14 Pump 15 Filter (Ink Filter) 16 Detection Mechanism 17 Control Unit 19 Piping Path (First Piping Path) 22 Pipe Route (Fourth Pipe Route) 24 On-Off Valve (First On-Off Valve) 25 On-Off Valve (Second On-Off Valve) 30 Connection Point 31 Pipe Route (Third Pipe Route) 32 Pipe Route (Second Pipe Route) M1 Reference Quantity (First Reference Quantity) M2 Reference Quantity (Second Reference Quantity) M3 Reference Quantity (Third Reference Quantity) T1 Fixed Time (First Fixed Time) T2 Fixed Time (Second Fixed Time)

Claims

1. In an inkjet printer including an inkjet head that discharges ink, a main tank that stores ink, a supply-side tank that is disposed closer to the inkjet head than the main tank in a piping path between the main tank and the inkjet head and stores ink supplied from the main tank, a pump for circulating ink between the main tank and the supply-side tank, a first piping path that is a supply piping path through which ink flows from the main tank toward the supply-side tank, a second piping path that is a circulation piping path in which the pump is disposed and through which ink flows from the supply-side tank toward the main tank, a detection mechanism for detecting the amount of ink stored in the main tank, and a control unit for controlling the inkjet printer, the control unit when circulating ink between the main tank and the supply-side tank by driving the pump, calculates an increase amount of the ink in the main tank over a predetermined first fixed time interval based on a detection result of the detection mechanism, and when the calculated increase amount becomes equal to or greater than a predetermined first reference amount a plurality of times in succession, executes predetermined error processing, and when circulating the ink, calculates a change amount of the ink in the main tank over a predetermined second fixed time interval based on a detection result of the detection mechanism, calculates an ink change amount difference, which is a difference between the change amount of the ink in the main tank over the predetermined second fixed time interval calculated last time and the change amount of the ink in the main tank over the predetermined second fixed time interval calculated this time, over the predetermined second fixed time interval, stores the amount of ink in the main tank when the absolute value of the calculated ink change amount difference becomes equal to or less than a predetermined second reference amount, which is less than the first reference amount, a plurality of times in succession, as an initial ink amount, and thereafter, also executes the error processing when the increase amount of the ink in the main tank from the stored initial ink amount becomes a predetermined third reference amount, which is greater than the first reference amount. An inkjet printer characterized by the above.

2. The inkjet printer according to claim 1, wherein the main tank is detachable from the inkjet printer and can be replaced.

3. A sub-tank that stores the ink supplied to the inkjet head, a buffer tank that stores the ink supplied to the sub-tank and is the supply-side tank for the ink supplied from the main tank, a first on-off valve, and a second on-off valve. In the middle of the piping path connecting the buffer tank and the sub-tank, a connection point is provided where the other end of the piping path connected to the main tank is connected. The second piping path is constituted by a third piping path that is a piping path between the buffer tank and the connection point, and a fourth piping path that is a piping path between the connection point and the main tank. The pump is disposed in the third piping path. The first on-off valve is disposed in the piping path between the connection point and the sub-tank. The second on-off valve is disposed in the fourth piping path. When the pump is driven with the second on-off valve open and the first on-off valve closed, ink flows from the buffer tank toward the main tank. The inkjet printer according to claim 2, wherein when the pump is driven with the first on-off valve open and the second on-off valve closed, ink flows from the buffer tank toward the sub-tank.

4. An ink filter disposed in the third piping path is provided. The inkjet printer according to claim 3, wherein ink is supplied from the main tank to the buffer tank by a head difference.

5. An inkjet printer control method including an inkjet head that discharges ink, a main tank that stores ink, a supply-side tank that is disposed closer to the inkjet head side than the main tank in the piping path between the main tank and the inkjet head and stores the ink supplied from the main tank, a pump for circulating ink between the main tank and the supply-side tank, a first piping path that is a supply piping path through which ink flows from the main tank toward the supply-side tank, a second piping path that is a circulation piping path in which the pump is disposed and through which ink flows from the supply-side tank toward the main tank, and a detection mechanism for detecting the amount of ink stored in the main tank. When circulating ink between the main tank and the supply-side tank by driving the pump, the increase amount of the ink in the main tank over a predetermined first fixed time interval is calculated based on the detection result of the detection mechanism, and when the calculated increase amount becomes equal to or greater than a predetermined first reference amount continuously for a plurality of times, a predetermined error process is executed, and When circulating the ink, the change amount of the ink in the main tank over a predetermined second fixed time interval is calculated based on the detection result of the detection mechanism, and an ink change amount difference, which is the difference between the change amount of the ink in the main tank over the second fixed time calculated last time and the change amount of the ink in the main tank over the second fixed time calculated this time, is calculated at the second fixed time interval. When the absolute value of the calculated ink change amount difference becomes equal to or less than a predetermined second reference amount, which is less than the first reference amount, continuously for a plurality of times, the amount of the ink in the main tank at that time is stored as an initial ink amount. After that, even when the increase amount of the ink in the main tank from the stored initial ink amount becomes a predetermined third reference amount, which is greater than the first reference amount, the error process is executed. A control method for an inkjet printer is characterized by the above.

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